CN103312262B - Electric motor drives, fluid compression systems and air conditioners - Google Patents

Abstract

The invention provides a motor driving device with high reliability, a fluid compression system and an air conditioner. The motor control device is provided with an element short-circuit protection unit (12) which stops the driving of the switching element when the current value input from the current detector (20) exceeds a short-circuit protection threshold value for preventing short circuit in the inverter circuit (11), wherein the inverter control unit (40) estimates the motor current flowing into the motor (M) according to the current value input from the current detector (20), and executes the processing of stopping the driving of the switching element when the motor current exceeds other current threshold values related to the temperature protection of the switching element and/or the demagnetization protection of the motor (M), the processing of the element short-circuit protection unit (12) is executed without intervention of a microcomputer, and the processing of the inverter control unit (40) is executed when the microcomputer is involved.

Description

Electric motor drives, fluid compression systems and air conditioners

technical field

The invention relates to a driving device for an electric motor, a fluid compression system and an air conditioner.

Background technique

The air conditioner sends the indoor air into the heat exchanger by rotating the indoor fan installed in the indoor equipment, and exchanges heat with the refrigerant circulating in the heat exchanger to heat or cool the air. Air is supplied to the room for air conditioning. In addition, a compressor constituting a part of the heat pump cycle is installed in the outdoor equipment of the air conditioner, and the refrigerant is compressed by the compressor and discharged at high temperature and high pressure.

In addition, as the permanent magnets included in the motor of the compressor, ferrite magnets are used when the price is important, and rare earth magnets such as neodymium magnets are used when the performance is important. Among them, the ferrite magnet has the characteristic of being easily demagnetized in a low temperature environment, and the rare earth magnet has the characteristic of being easily demagnetized in a high temperature environment. Here, "demagnetization" means that the magnetic moment of the entire magnet decreases due to temperature rise due to eddy current loss of the magnet, reverse magnetic field due to current flowing into the coil, and the like.

However, in an environment where an air conditioner is used, the temperature around the motor inside the compressor becomes very low at the start of the heating operation in winter, which is approximately equal to the outside air temperature. Running in outside air becomes very high temperature.

Therefore, a compressor installed in an outdoor device must be driven in a low-temperature environment or a high-temperature environment, and a high driving capability is required. In order to exhibit a high driving capability according to an operation request based on indoor temperature, outdoor temperature, etc., it is necessary to increase the current flowing through the motor. Accordingly, there is a possibility that the permanent magnets (ferrite magnets or rare earth magnets) included in the motor may be demagnetized.

In addition to preventing demagnetization, in order to prevent damage to the switching elements provided in the inverter circuit, it is also necessary to suppress the current flowing through the switching elements to a predetermined allowable current value or less.

The following techniques are known as conventional techniques for partially coping with these problems.

For example, Patent Document 1 describes a brushless motor drive device for compressors that calculates a motor phase current by a phase current calculation unit (current reproduction unit) based on the output of a DC current detection circuit (current detector), and has A current limiting function that lowers the frequency of the brushless motor (motor) when the motor phase current exceeds a predetermined threshold.

In the technique described in Patent Document 1, the demagnetization of the permanent magnet is prevented by changing the overcurrent protection stop threshold determined by the voltage comparator circuit to a predetermined value smaller than the demagnetization current.

In addition, Patent Document 2 describes a technique in which a control circuit controls an IGBT (Insulated Gate Bipolar Transistor) to be on/off to drive a motor, and when a current limit command signal is input from a current limit circuit, the IGBT is turned on. cut-off state to cut off the motor current. In addition, the current limiting circuit outputs a current limiting instruction signal to the control circuit when the load current exceeds the prescribed overcurrent upper limit. This prevents demagnetization of the permanent magnets included in the motor.

Patent Document 1: Japanese Patent Laid-Open No. 2009-198139

Patent Document 2: Japanese Patent Application Laid-Open No. 07-337072

However, when a short-circuit current flows through the inverter circuit due to a malfunction or the like, it is necessary to stop the inverter circuit instantaneously (approximately within several μsec) in order to prevent damage to the switching elements.

However, in the techniques described in Patent Documents 1 and 2, since the stop instruction to the inverter circuit is given via the microcomputer, a delay occurs in the cycle time of the microcomputer (approximately 10 to several hundreds of μsec). Therefore, it is necessary to predict the cycle time and set the operating threshold of the overcurrent protection unit lower than the original threshold. In addition, this problem can be avoided by using a microcomputer with a short cycle time, but it is more expensive than when a microcomputer with a cycle time of several μsec is used for a general household electric appliance. Therefore, if such a microcomputer is installed in an air conditioner, the price competitiveness of the product will decrease.

Contents of the invention

Therefore, an object of the present invention is to provide a highly reliable motor drive device, fluid compression system, and air conditioner.

In order to solve the above-mentioned problems, the present invention provides a motor drive device characterized by including an element short-circuit protection unit for preventing a short-circuit protection threshold for preventing a short-circuit in an inverter circuit when the current value input from the current detection unit exceeds the short-circuit protection threshold. The driving of the switching element is stopped, and the control unit estimates the motor current flowing into the motor according to the current value input from the current detection unit, and when the motor current exceeds the temperature protection of the switching element and/or the temperature protection of the motor In the case of other current thresholds related to demagnetization protection, the process of stopping the drive of the switching element is executed, and the processing of the element short-circuit protection unit is executed without intervening in the microcomputer, and is executed in the case of intervening in the microcomputer processing of the control unit.

Invention effect

According to the present invention, it is possible to provide a highly reliable motor drive device, a fluid compression system, and an air conditioner.

Description of drawings

FIG. 1 is a system configuration diagram including a motor drive device according to a first embodiment of the present invention.

FIG. 2( a ) is a flowchart showing the flow of processing by the overcurrent determination unit, and FIG. 2( b ) is a flowchart showing the flow of processing by the element short-circuit protection unit.

3 is an explanatory diagram schematically showing temporal changes in motor current when a short-circuit current flows in an inverter circuit.

4 is a system configuration diagram including a motor drive device according to a second embodiment of the present invention.

5 is a graph showing changes in the absolute rating of the element, the motor demagnetization current, the motor demagnetization protection threshold, and the element short-circuit protection threshold with respect to the motor winding temperature in a motor using a permanent magnet having low-temperature demagnetization characteristics picture.

Fig. 6 is a graph showing changes in element absolute rating, motor demagnetization current, motor demagnetization protection threshold, and element short-circuit protection threshold with respect to motor winding temperature in a motor using a permanent magnet having high-temperature demagnetization characteristics picture.

7 is a system configuration diagram including a motor drive device according to a third embodiment of the present invention.

8 is a graph showing changes in element absolute ratings, element short-circuit protection thresholds, temperature destruction current values, element temperature protection thresholds, and current limit thresholds with respect to element temperatures of switching elements included in the inverter circuit.

9 is a flowchart showing a flow of processing of an element temperature protection overcurrent determination unit included in the motor drive device according to the third embodiment of the present invention.

FIG. 10 is a system configuration diagram including a motor drive device according to a fourth embodiment of the present invention.

Symbol Description

100, 100A, 100B, 100C Motor Drives

10 power module (power module)

11 inverter (inverter) circuit

12 element short circuit protection unit

13 Inverter drive circuit

20 current detector (current detection unit)

30 amps

40, 40A, 40B, 40C inverter control unit (control unit)

41 motor current reproduction part

42 Speed command department

43 Overcurrent Judgment Unit (Control Unit)

44 Drive signal generation part (control unit)

45 Motor demagnetization protection threshold setting unit (control unit)

46 Motor demagnetization protection overcurrent determination unit (control unit)

47 element temperature protection threshold setting part (control unit)

48 element temperature protection overcurrent determination unit (control unit)

50 motor winding temperature detector (winding temperature detection unit)

60 element temperature detector (element temperature detection unit)

200 AC power

300 converter (converter) circuit

M motor

detailed description

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings as appropriate. In addition, the same code|symbol is attached|subjected to the common part in each drawing, and overlapping description is abbreviate|omitted.

"First Embodiment"

<System configuration>

FIG. 1 is a system configuration diagram including a motor drive device according to a first embodiment of the present invention. The AC power supply 200 represents a power supply of AC power transmitted and distributed by a power plant (not shown) or the like.

The converter circuit 300 is a circuit for converting an AC voltage input from the AC power supply 200 into a DC voltage, and includes a diode bridge in which diodes D1 and D3 are forwardly connected in series, and the connection point between them serves as a converter input terminal. In addition, the same applies to diodes D2 and D4. In addition, a smoothing capacitor C for smoothing a ripple component contained in the DC voltage is connected in parallel to the above-mentioned diode bridge.

Furthermore, the AC power supply 200 and the converter circuit 300 connected to the AC power supply 200 constitute a "DC power supply".

The motor drive device 100 converts the DC voltage input from the converter circuit 300 into a predetermined AC voltage and outputs it to the motor M through inverter control. Note that details of the processing performed by the motor drive device 100 will be described later.

The motor M is, for example, a permanent magnet synchronous motor, and is connected to the inverter circuit 11 via a three-phase winding. That is, the motor M rotates by attracting a permanent magnet (not shown) serving as a rotor by a rotating magnetic field generated by an alternating current flowing in a three-phase winding. Furthermore, the electric motor M is used, for example, in a compressor (not shown) constituting a heat pump cycle of an air conditioner (not shown).

<Configuration of motor drive unit>

As shown in FIG. 1 , the motor drive device 100 includes a power module 10 , a current detector 20 , an amplifier 30 , and an inverter control unit 40 .

The power module 10 employs an inverter circuit 11 including a plurality of switching elements (not shown) for outputting a prescribed AC voltage to the motor M, an element short-circuit protection unit 12 for protecting the switching elements, and an element short-circuit protection unit 12 for driving The inverter drive circuit 13 for the switching elements is collectively and integrally configured.

The current detector (current detection unit) 20 is connected in series to the bus bar between the converter circuit 300 and the inverter circuit 11, detects the DC current supplied to the inverter circuit 11, and outputs it to the amplifier 30 and element short circuit at all times. Protection unit 12.

The amplifier 30 has, for example, a transistor, amplifies the detection signal input from the current detector 20 , and outputs it to the motor current reproduction unit 41 of the inverter control unit 40 .

The inverter control unit (control unit) 40 calculates an AC voltage to be applied to the motor M based on the detection signal input from the amplifier 30 and the rotation speed command value ω of the motor M, converts it into a drive signal, and outputs it.

In addition, the rotation speed command value ω is determined based on set temperature information input from a remote controller (not shown), indoor temperature detected by a thermistor (not shown) of an indoor device (not shown), and the like. , the rotation speed command value of the motor M.

(1. Power module)

The power module 10 includes an inverter circuit 11 , an element short-circuit protection unit 12 , and an inverter drive circuit 13 .

The inverter circuit 11 has a plurality of switching elements (not shown), switches ON/OFF of each switching element in accordance with a PWM signal input from the inverter drive circuit 13, and turns a predetermined The three-phase AC voltage is output to the motor M. Then, a three-phase AC current corresponding to the three-phase AC voltage flows into the motor M to generate the above-mentioned rotating magnetic field.

In addition, as a switching element included in the inverter circuit 11, for example, an IGBT can be used.

The component short-circuit protection unit 12 compares the current detection value input from the current detector 20 with a preset component short-circuit protection threshold, and outputs a stop command signal to the inverter when the above-mentioned current detection value exceeds the component short-circuit protection threshold drive circuit 13.

In addition, the processing of the element short-circuit protection unit 12 is executed without intervening a microcomputer.

The inverter drive circuit 13 outputs a PWM signal (Pulse Width Modulation: Pulse Width Modulation signal) to each switching element (not shown) included in the inverter circuit 11 according to the drive signal input from the drive signal generator 44 . In addition, when a stop instruction signal is input from element short-circuit protection means 12, inverter drive circuit 13 stops the output of the PWM signal.

(2. Inverter control unit)

The inverter control unit (control unit) 40 includes a motor current reproduction unit 41 , a speed command unit 42 , an overcurrent determination unit 43 , and a drive signal generation unit 44 . In addition, the processing of the inverter control unit 40 is performed by a microcomputer (Microcomputer) (or intervening microcomputer). The microcomputer is composed of an electronic circuit (not shown) including a CPU (Central Processing Unit), ROM (Read Only Memory), RAM (Random Access Memory), and various interfaces, and reads out a program stored in the ROM and expands it to the RAM. , various processing is performed by the CPU.

The motor current reproduction unit 41 reproduces the current flowing in the motor M (hereinafter referred to as motor current) based on the detection signal detected by the current detector 20 and further amplified by the amplifier 30 , and outputs it to the overcurrent determination unit 43 .

The speed command unit 42 calculates the three-phase AC command voltage and the PWM frequency command value to be applied to the motor M based on the motor current input from the motor current reproduction unit 41 and the rotation speed command value ω input from the outside, and outputs to the driver. Signal generating part 44 .

The overcurrent determination unit 43 compares the motor current input from the motor current reproduction unit 41 with an overcurrent threshold value (other threshold value) stored in the microcomputer, and sends a signal to the drive signal generation unit 44 when the motor current exceeds the overcurrent threshold value. Output stop command signal. In addition, details about the overcurrent threshold will be described later.

The drive signal generation unit 44 generates a drive signal based on the command value input from the speed command unit 42 and outputs it to the inverter drive circuit 13 . In addition, when the above-mentioned stop command signal is input from the overcurrent determination unit 43 , the drive signal generation unit 44 stops the process of generating the drive signal in accordance with the command.

Hereinafter, the determination process performed by the overcurrent determination part 43 and the determination process performed by the element short-circuit protection means 12 are demonstrated sequentially.

Among them, the overcurrent determination unit 43 performs determination processing on occurrence of an actual abnormality (out-of-tuning of the motor M, etc.) after several msec or more have elapsed since the detection of the sign of the abnormality. On the other hand, the element short-circuit protection unit 12 performs a determination process on occurrence of an actual abnormality (short circuit of the inverter circuit 11, etc.) after several μsec has elapsed.

<Processing by the Overcurrent Judgment Unit>

As described above, the overcurrent determination unit 43 compares the motor current input from the motor current reproduction unit 41 with the overcurrent threshold value stored in the microcomputer, and when the motor current exceeds the overcurrent threshold value (other threshold value), sends the drive signal to The processing of the generating unit 44 stops.

The processing of the overcurrent determination unit 43 is executed by a microcomputer (not shown). Therefore, the overcurrent determination unit 43 can perform a highly accurate determination using a complicated calculation formula. In addition, the operation time of the microcomputer required for the determination process performed in this embodiment is 10 μsec to several hundreds of μsec.

In addition, the time Δt _p from when an overcurrent is detected in the inverter circuit 11 by the current detector 20 to when the operation of the inverter circuit 11 is stopped by the inverter control unit 40 is as follows.

That is, the above-mentioned time Δt _p is the time Δt _p 1 until the signal from the current detector 20 is input to the inverter control unit 40, until the inverter control unit 40 determines that there is an overcurrent and drives the signal generating unit The sum of the time Δt _p 2 until the inverter control unit 40 stops and the time Δt _p 3 until the inverter circuit 11 is actually in the OFF state by receiving the drive signal from the inverter control unit 40 is as follows (Formula 1 ).

Δt _p ＝Δt _p 1+Δt _p 2+Δt _p 3...(Formula 1)

Here, the current detector 20, between the current detector 20 and the inverter control unit 40, between the inverter control unit 40 and the inverter circuit 11, and the inverter circuit 11 are made without intervening micro The so-called hardware circuit structure of a computer. Therefore, the time Δt _p 1 until the signal from the current detector 20 is transmitted to the inverter control unit 40, and the time until the inverter circuit 11 is turned off due to the stop of receiving the drive signal from the inverter control unit 40 Δt _p 3, several μsec, respectively.

On the other hand, since the inverter control unit 40 executes the processing from the input of the detection signal from the current detector 20 to the output of the stop command signal to the inverter drive circuit 13 through a microcomputer (not shown), it is necessary to Time from 10 μsec to hundreds of μsec. Therefore, the time Δt _p shown in (Equation 1) above is also 10 μsec to several hundreds of μsec.

Therefore, the processing using the overcurrent determination unit 43 of the microcomputer is suitable for characteristics that require several msec or more from detection of an abnormality (sign) such as the above-mentioned out-of-adjustment to occurrence of the influence.

For example, as the determination process applied to the overcurrent determination unit 43 using a microcomputer, there are listed: out-of-balance protection of the motor M, winding temperature protection of the motor M, demagnetization protection of the motor M, and switching elements (not shown). Temperature rise protection, compressor (not shown) over-temperature protection, compressor pressure protection, etc. These characteristics require several msec or more time until an abnormality occurs due to electrical time constants, thermal capacities, etc., and thus can be adequately handled even in processing using a microcomputer.

In this determination process, control information such as the amplitude and phase of the motor current, the amplitude and phase of the motor applied voltage, and the DC voltage and current input to the inverter circuit 11 can be used.

Alternatively, a room temperature thermistor (not shown), an outside air temperature thermistor (not shown), a frost thermistor (not shown), a discharge temperature thermistor (not shown), Sensor information acquired by a human body detection sensor (not shown), a thermopile (not shown), and the like.

In the present embodiment, as an example of the determination process performed by the overcurrent determination unit 43, a case is described in which a sign (that is, an increase in the current input from the current detector 20) when the motor M is out of tune is detected and the motor M is stopped. .

As described above, the synchronous motor rotates by attracting the rotor (permanent magnet) by the rotating magnetic field generated by the alternating current. However, in the event of an overload, a sudden speed change, etc., the synchronization between the PWM signal input from the inverter drive circuit 13 and the rotation of the motor M may be lost, causing a loss of adjustment.

Here, before an imbalance occurs in the motor M, the deviation between the applied voltage and the motor induced voltage becomes large. For example, when phase control of voltage and current is performed by vector control, it takes several hundred msec until the motor M becomes out of tune, and the motor current increases.

Therefore, the overcurrent determination unit 43 compares a predetermined overcurrent determination threshold value (other threshold value) stored in advance with the motor current value, and stops the processing of the drive signal generation unit 44 when the motor current value exceeds the overcurrent determination threshold value. . As a result, the motor drive device 100 can immediately stop the drive of the motor M when an out-of-adjustment (sign) is detected.

Here, the overcurrent determination threshold may be a preset fixed value, or an optimum overcurrent determination threshold may be calculated by the overcurrent determination unit 43 based on a phase difference between the applied voltage and the induced voltage of the motor M, or the like.

FIG. 2( a ) is a flowchart showing the flow of processing performed by the overcurrent protection determination unit. In addition, in the following description, ON/OFF operation of the switching element of the inverter circuit 11 based on the PWM signal from the inverter drive circuit 13 may be individually described as "driving the switching element". In addition, at the beginning of the flowchart shown in FIG. 2( a ), it is assumed that the switching element is being driven.

In step S101, the overcurrent determination unit 43 determines whether or not a predetermined time Δt _A has elapsed since the start of the process. Here, the predetermined time Δt _A is a cycle time of the microcomputer for executing the processing of the overcurrent determination unit 43 and is a preset value.

When the predetermined time Δt _A has elapsed since the start of the process (S101→YES), the process of the overcurrent determination unit 43 proceeds to step S102. On the other hand, when the predetermined time Δt _A has not elapsed since the start of the process (S101→No), the overcurrent determination unit 43 repeats the process of step S101.

In step S102, the overcurrent determination unit 43 determines whether or not the motor current value I _M input from the motor current reproduction unit 41 is greater than a predetermined overcurrent threshold value I _E (other threshold value).

When the motor current value I _M is greater than the overcurrent threshold I _E (S102→YES), the process of the overcurrent determination unit 43 proceeds to step S103. On the other hand, when the motor current value I _M is equal to or less than the overcurrent threshold value I _E (S102→No), the process of the overcurrent determination unit 43 returns to "Start".

In step S103, the overcurrent determination unit 43 stops the driving of the switching element. As a result, the electric power supply to the motor M ends, and the motor M stops.

<Handling of component short-circuit protection unit>

FIG. 2( b ) is a flowchart showing the flow of processing performed by the element short-circuit protection unit. However, at the beginning of this flowchart, it is assumed that the switching element of the inverter circuit 11 is being driven.

In step S201, the element short-circuit protection unit 12 determines whether or not a predetermined time Δt _B has elapsed since the process was started. Among them, the predetermined time Δt _B is the cycle time of the element short-circuit protection unit 12 and is a preset value.

When the predetermined time Δt _B has elapsed from the start of the process (S201→YES), the process of the element short-circuit protection unit 12 proceeds to step S202. On the other hand, when the predetermined time Δt _B has not elapsed since the start of the process (S201→No), the element short-circuit protection unit 12 repeats the process of step S201.

In step S202, the element short-circuit protection unit 12 determines whether the current detection value I _S input from the current detector 20 is greater than the element short-circuit protection threshold ID _.

When the current detection value I _S is greater than the element short-circuit protection threshold ID ₍ S202→YES), the process of the element short-circuit protection unit 12 proceeds to step S203. On the other hand, when the current detection value _IS is equal to or less than the element short-circuit protection threshold ID ( _S202 →No), the process of the element short-circuit protection means 12 returns to "start".

In step S203 , the element short-circuit protection unit 12 outputs a stop command signal to the inverter driving circuit 13 . Moreover, when a stop command signal is input from the element short-circuit protection means 12, the drive of the switching element of the inverter drive circuit 13 stops, and as a result, the drive of the electric motor M also stops.

Furthermore, the drive stop processing of the switching element based on the determination result of the overcurrent determination unit 43 and the drive stop process of the switching element based on the determination result of the element short circuit protection unit 12 are executed independently. For example, when the stop processing by the element short protection means 12 is executed before the stop processing by the overcurrent determination unit 43 , the motor M is stopped by the stop command signal output from the element short protection means 12 as a trigger.

<effect>

According to the motor drive device 100 according to the present embodiment, the comparison and judgment process using a microcomputer is performed for characteristics (disturbance, etc.) that take several msec or more from detection of an abnormal sign to actual influence, and the The driving of the switching element is stopped. Therefore, since the microcomputer enables the control information and sensor information related to the motor M to perform complicated calculations, it is possible to perform highly accurate determination processing.

That is, since the timing at which the out-of-tuning occurs is slower than the timing at which the arithmetic processing of the microcomputer ends, the drive of the motor M can be stopped before the out-of-tuning occurs.

In addition, as described above, the time from the detection of overcurrent by the element short-circuit protection unit 12 to the output of the stop instruction signal to the inverter drive circuit 13 is the required time (for example, 3 μsec) without intervening in the hardware circuit of the microcomputer, So extremely short. Thus, when the current detected by the current detector 20 exceeds the element short-circuit protection threshold _ID , the stop command based on the element short-circuit protection unit 12 is earlier than the stop command based on the motor demagnetization protection overcurrent determination unit 46. is output. Therefore, it is possible to reliably prevent the destruction of the switching element due to the short-circuit current.

3 is an explanatory diagram schematically showing temporal changes in motor current when a short-circuit current flows through a switching element. _A case is considered in which the motor current _rises sharply from time _t0 shown in FIG _.

In addition, the element absolute rating I _R shown in FIG. 3 is a value at which the motor current is set to a current value that should not be exceeded even momentarily.

In this case, at time t ₂ after time Δt _q (=several μsec) has elapsed from time t ₁ , the drive of the switching element is stopped by the element short-circuit protection unit 12 . As a result, the motor current decreases sharply after time _t2 (see the solid arrow in FIG. 3 ), and the motor current can be prevented from reaching the element absolute rating value I _R . In addition, this time Δt _q is shorter than the time (short-circuit withstand capacity) of a switching element such as an IGBT withstanding a short-circuit current.

On the other hand, assuming that a microcomputer performs element short-circuit protection threshold judgment processing, since time t ₃ after time Δt _p (=10 μsec to several hundreds of μsec) has elapsed since time t ₁ , the driving of the switching element is stopped, so the motor current I ₃ exceeding the absolute rating I _R of the element flows (refer to the dotted arrow in FIG. 3 ), thereby causing destruction of the switching element.

According to the motor drive device 100 according to this embodiment, the element short-circuit protection unit 12 is provided outside the inverter control unit 40 which is a microcomputer, and the determination process is executed without intervening in the microcomputer. Accordingly, it is possible to quickly catch the increase in the current of the inverter circuit 11 when the short circuit occurs, and stop the drive of the switching element in the middle of the increase, thereby reliably preventing the breakage of the switching element.

Also, because weak currents are handled in electronic circuits, they are susceptible to noise. In the motor drive device 100 according to the present embodiment, the driving of the switching element can be quickly stopped in a few μsec. Therefore, the element short-circuit protection threshold can be set to a value at which it can be determined that a short circuit has reliably occurred in the inverter circuit 11 . That is, since the element short-circuit protection threshold can be raised to near the absolute rated value of the element, malfunction due to noise (stopping of the motor M) can be eliminated.

"Second Embodiment"

The motor drive device 100A according to the second embodiment includes a motor demagnetization protection overcurrent determination unit 46 instead of the overcurrent determination unit 43 described in the first embodiment, and further includes a motor winding temperature detector 50 and a motor demagnetization protection unit. The threshold setting unit 45 is the same as that of the first embodiment except for the above points. Therefore, descriptions are made for different parts, and descriptions for overlapping parts are omitted.

<Configuration of motor drive unit>

Fig. 4 is a system configuration diagram including a motor drive device.

The motor winding temperature detector (winding temperature detection unit) 50 detects the motor winding temperature of the motor M, and outputs it to the motor demagnetization protection threshold setting unit 45 at all times.

The motor demagnetization protection threshold setting unit 45 sets a demagnetization protection threshold (other threshold) for preventing demagnetization of the permanent magnet based on the motor winding temperature input from the motor winding temperature detector 50 . Note that the processing performed by the motor demagnetization protection threshold setting unit 45 will be described later.

The motor demagnetization protection overcurrent determination unit 46 determines whether or not more than the demagnetization current has flowed in the motor M based on the motor current input from the motor current reproduction unit 41 and the demagnetization protection threshold input from the motor demagnetization protection threshold setting unit 45 . Magnetic protection threshold for overcurrent. Then, when it is determined that an overcurrent exceeding the demagnetization protection threshold has flowed in the motor M, the motor demagnetization protection overcurrent determination unit 46 stops the processing of the drive signal generation unit 44 .

<In the case of low temperature demagnetization characteristics>

(1. Setting of motor demagnetization protection threshold)

In the following description, the motor current value when demagnetization occurs in the permanent magnet of the motor M is referred to as "motor demagnetization current".

When the permanent magnet is exposed to an excessive reverse magnetic field, demagnetization is caused, the magnetism becomes weak, and the characteristics of the magnet deteriorate. That is, when an excessive current flows through the permanent magnets used in the motor M, demagnetization occurs in the reverse magnetic field generated by the current. Therefore, it is necessary that an overcurrent exceeding the motor demagnetization current does not flow into the motor M.

The motor demagnetization protection threshold setting unit 45 sets a demagnetization protection threshold (other threshold) that is a threshold when the drive of the switching element is stopped based on the detected temperature input from the motor winding temperature detector 50, and outputs the demagnetization protection threshold to the motor. Demagnetization protects the overcurrent determination unit 46 .

Among them, the processing of the motor demagnetization protection threshold setting unit 45 is executed by the microcomputer.

5 is a graph showing changes in the absolute rating of the element, the motor demagnetization current, the motor demagnetization protection threshold, and the element short-circuit protection threshold with respect to the motor winding temperature in a motor using a permanent magnet having low-temperature demagnetization characteristics picture.

As shown in FIG. 5 , a permanent magnet having low-temperature demagnetization characteristics (for example, a ferrite magnet) has a smaller value of motor demagnetization current (ie, becomes easy to demagnetize) as its temperature becomes lower.

Therefore, the motor demagnetization protection threshold setting unit 45 sets the motor demagnetization protection threshold to be smaller as the motor winding temperature becomes lower.

In addition, the motor demagnetization protection threshold is set so as to be smaller than the value of the motor demagnetization current at any motor winding temperature. Wherein, in the example shown in FIG. 5 , in order to simplify the processing of the microcomputer software, multiple line segments are used to represent the temperature characteristics of the motor demagnetization protection threshold.

(2. Setting of component short circuit protection threshold)

The element short-circuit protection unit 12 sets the element short-circuit protection threshold ID for preventing short-circuiting of the switching elements of the inverter circuit 11 to a predetermined value lower than the element absolute rating I _{R (} see FIG. 5 ). In addition, the element short-circuit protection threshold ID is set to a fixed value _regardless of the temperature of the motor winding.

Even in this embodiment, as in the first embodiment, the processing of the element short-circuit protection unit 12 is executed without intervening the microcomputer, and the switching element is _driven when the motor current exceeds the element short-circuit protection threshold ID. stop.

In addition, in the example shown in FIG. 5 , in the region where the motor winding temperature is above _{T 0} , the motor demagnetization protection threshold I _M is set to a predetermined value _{ΔI 1} (=ID − I ₀ ) fixed value. This is because, when the motor current exceeds the element short-circuit protection threshold _ID , the element short-circuit protection unit 12 stops the drive of the inverter circuit 11 earlier than the motor demagnetization protection overcurrent determination unit 46 .

Among them, there is a temperature region (such as a high temperature region) where the motor demagnetization protection threshold exceeds the element short circuit protection threshold, and in other temperature regions (such as a low temperature region), it can also be determined that the motor demagnetization protection threshold is below the element short circuit protection threshold. way to set.

<In the case of high temperature demagnetization characteristics>

Fig. 6 is a graph showing changes in element absolute rating, motor demagnetization current, motor demagnetization protection threshold, and element short-circuit protection threshold with respect to motor winding temperature in a motor using a permanent magnet having high-temperature demagnetization characteristics picture.

As shown in FIG. 6 , permanent magnets (eg, neodymium magnets) having high-temperature demagnetization characteristics have smaller values of motor demagnetization current (ie, become easier to demagnetize) as the temperature becomes higher.

Therefore, the motor demagnetization protection threshold setting unit 45 sets the demagnetization protection threshold to be smaller as the temperature of the motor winding becomes higher.

Among them, in the example shown in Figure 6, the temperature characteristics of the motor demagnetization protection threshold are represented by multiple line segments, and in the region below the motor winding temperature T2, the motor demagnetization protection threshold is set to be higher _than the element temperature protection The threshold ID is higher than the predetermined value of _ΔI2 (=I _{2 −ID} ). In addition, in a region where the motor winding temperature is higher _than the temperature T3, the element short-circuit protection threshold is set to be larger than the motor demagnetization protection threshold.

In addition, the permanent magnets having high-temperature demagnetization properties are not limited to neodymium magnets, and may be other rare earth magnets.

<Operation of the motor drive unit>

The motor demagnetization protection threshold setting part 45 sets the characteristic motor demagnetization protection threshold shown in FIG. The unit 46 outputs the information of the threshold value.

Further, motor demagnetization protection overcurrent determination unit 46 compares the motor current input from motor current reproducing unit 41 with the motor demagnetization protection threshold input from motor demagnetization protection threshold setting unit 45 .

When the motor current exceeds the motor demagnetization protection threshold value, the motor demagnetization protection overcurrent determination unit 46 stops the processing of the drive signal generation unit 44 . As a result, the driving of the switching element is stopped, the power supply to the motor M is terminated, and the motor M is stopped.

On the other hand, when the motor current is equal to or less than the motor demagnetization protection threshold value, the motor demagnetization protection overcurrent determination unit 46 repeats the comparison process described above every predetermined time.

<effect>

According to the motor drive device 100A according to the present embodiment, for the motor M provided with a permanent magnet having low-temperature demagnetization characteristics such as ferrite magnets or high-temperature demagnetization characteristics such as neodymium magnets, it is possible to place The flowing current is set to be smaller than the motor demagnetization current, and demagnetization of the permanent magnet can be reliably prevented. That is, the drive of the switching element is stopped after highly accurate determination processing is performed on the demagnetization characteristic with a large time constant under the control of the microcomputer.

As a result, as shown in FIGS. 5 and 6 , the motor demagnetization protection threshold can be specified extremely finely according to the motor winding temperature. That is, since demagnetization of the motor M can be prevented and a maximum current corresponding to the temperature of the motor winding can flow through the motor winding, the performance of the motor M can be maximized.

On the other hand, when the circuit needs to be disconnected in a short time, such as when the switching element is short-circuited, the drive of the switching element is stopped by a circuit (element short-circuit protection means 12 ) that does not involve the microcomputer.

Accordingly, it is possible to prevent demagnetization of the permanent magnet included in the electric motor M, and to reliably protect the switching elements of the inverter circuit 11 .

In addition, the correlation between the motor winding temperature and the motor demagnetization protection threshold can be determined by a plurality of parameters. That is, only by changing these constants according to the motor M to be driven, the same microcomputer software can be used for various kinds of permanent magnets, and the development of microcomputer software can be simplified. The temperature characteristic of the motor demagnetization protection threshold is represented by one or more curves (including a straight line), and the motor demagnetization protection threshold is set to a fixed value I _M in a region above a predetermined temperature T ₀ (see FIG. 5 ). Therefore, the processing load of the microcomputer can be reduced.

"Third Embodiment"

The motor drive device 100B according to the third embodiment includes an element temperature protection overcurrent determination unit 48 instead of the overcurrent determination unit 43 described in the first embodiment, and further includes an element temperature detector 60 and an element temperature protection threshold value setting. The portion 47 is the same as that of the first embodiment except for the above points. Therefore, the different part will be described, and the description of the overlapping part will be omitted.

<Configuration of motor drive unit>

FIG. 7 is a diagram showing a system configuration including a motor drive device.

The element temperature detector (element temperature detection unit) 60 detects the temperature of the switching element included in the inverter circuit 11, and outputs the detected element temperature to the element temperature protection threshold value setting unit every moment.

The element temperature protection threshold setting unit 47 sets an element temperature protection threshold (other threshold) based on the element temperature input from the element temperature detector 60 . Note that details of the processing performed by the element temperature protection threshold setting unit 47 will be described later.

The element temperature protection overcurrent determination unit 48 determines whether an element temperature protection threshold exceeding the element temperature protection has flowed in the motor M based on the motor current input from the motor current reproduction unit 41 and the element temperature protection threshold input from the element temperature protection threshold setting unit 47 . threshold overcurrent. Then, when an overcurrent exceeding the element temperature protection threshold value flows in the motor M, the element temperature protection overcurrent determination unit 48 stops the processing of the drive signal generation unit 44 .

Among them, the processing of the device temperature protection threshold value setting unit 47 is executed by the microcomputer.

On the other hand, the element short-circuit protection unit 12 executes the same processing as that of the first embodiment. That is, when the current detected by the current detector 20 exceeds the short-circuit protection threshold value, the element short-circuit protection unit 12 stops the drive of the switching element by a circuit that does not involve a microcomputer in order to quickly stop the inverter circuit 11. . Accordingly, when a short circuit occurs in the inverter circuit 11 , the driving of the switching element can be quickly stopped, and destruction of the switching element can be reliably prevented.

8 is a graph showing changes in element absolute ratings, element short-circuit protection thresholds, temperature destruction current values, element temperature protection thresholds, and current limit thresholds with respect to element temperatures of switching elements included in the inverter circuit.

As shown in Figure 8, the component short-circuit protection threshold is set at a current value lower than the absolute rating of the component. In addition, the element temperature destruction current value is a current value that causes destruction of the switching element when a current equal to or greater than the current value flows. The element temperature protection threshold is set to a current value smaller than the element temperature destruction current value by a predetermined value. In addition, the current limit threshold is a threshold when the motor M is decelerated, and is set to a current value smaller than the element temperature protection threshold by a predetermined value.

As shown in Figure 8, the area above the element temperature protection threshold and below the element temperature destruction current value is set as the "stop area". In addition, the area above the current limit threshold and below the element temperature protection threshold is set as the "deceleration area". In addition, a region smaller than the current limit value is set as a "stable region".

FIG. 9 is a flowchart showing an operation flow of an element temperature protection overcurrent determination unit.

In step S301, the element temperature protection overcurrent determination unit 48 determines whether or not a predetermined time Δt _C has elapsed since the start of the process. Note that the predetermined time Δt _C is a cycle time of the microcomputer for executing the processing of the element temperature protection overcurrent determination unit 48 and is a value set in advance.

When the predetermined time Δt _C has elapsed from the start of the process (S301→YES), the process of the element temperature protection overcurrent determination unit 48 proceeds to step S302. On the other hand, when the predetermined time Δt _C has not elapsed since the start of the process (S301→No), the element temperature protection overcurrent determination unit 48 repeats the process of step S301.

In step S302, the element temperature protection overcurrent determination unit 48 determines whether or not the motor current value I _M input from the motor current reproduction unit 41 is greater than the element temperature protection threshold value I _T . When the motor current value I _M is greater than the element temperature protection threshold _IT (S302→YES), the processing of the element temperature protection overcurrent determination unit 48 proceeds to step S303. On the other hand, when motor current value I _M is equal to or less than element temperature protection threshold _IT (S302→NO), the process of element temperature protection overcurrent determination unit 48 proceeds to step S304.

In step S303 , the element temperature protection overcurrent determination unit 48 stops the processing of the drive signal generation unit 44 . That is, the element temperature protection overcurrent determination unit 48 stops the driving of the switching element.

Wherein, when the motor current is below the element short-circuit protection threshold and greater than the element temperature protection threshold, the element short-circuit protection unit 12 constituted by a hardware circuit does not work.

In step S304, the element temperature protection overcurrent determination unit 48 determines whether or not the motor current value I _M is greater than the current limit threshold value I _L . When the motor current value I _M is greater than the current limit threshold I _L (S304→YES), the processing of the element temperature protection overcurrent determination unit 48 proceeds to step S305. On the other hand, when the motor current value I _M is equal to or less than the current limit threshold I _L (S304→No), the process of the element temperature protection overcurrent determination unit 48 returns to "Start".

In step S305 , the element temperature protection overcurrent determination unit 48 outputs a predetermined command signal to the drive signal generation unit 44 to decelerate the motor M.

<effect>

According to the motor drive device 100B according to the present embodiment, the comparison and judgment process using a microcomputer is performed on the temperature characteristics of the switching elements that take several msec or more from the detection of an abnormality (sign) to the actual occurrence of the abnormality, and if necessary And the driving of the switching element is stopped. In addition, since the element temperature protection threshold value used when performing the comparison process is determined based on the element temperature input from the element temperature detector 60, an overcurrent can be determined with high accuracy.

In addition, since the switching element has a predetermined heat capacity, the drive of the motor M is stopped before the switch is destroyed due to a temperature rise.

In addition, in the element temperature protection threshold setting unit 47, for the element temperature protection threshold, as shown in FIG. Specify the expression. Therefore, the constants of the above calculation expressions can be set to appropriate values, and the settings can be easily changed, and the microcomputer software can be made the same even for different types of inverter circuits 11, so that the procedure of product development can be simplified.

Also, when the motor current is within the circuit deceleration region (see FIG. 8 ), element temperature protection overcurrent determination unit 48 outputs a predetermined command signal to drive signal generation unit 44 to decelerate motor M. Accordingly, the current flowing into the switching element can be reduced, and the driving of the motor M can be maintained while reducing the temperature of the switching element.

"Fourth Embodiment"

The motor drive device 100C according to the fourth embodiment is different from the third embodiment in that a motor winding temperature detector 50 , a motor demagnetization protection threshold value setting unit 45 , and a motor demagnetization protection overcurrent determination unit 46 are added. , other than the above point, the rest are the same as the third embodiment. Therefore, different parts will be described, and the description of parts overlapping with the third embodiment will be omitted.

FIG. 10 is a diagram showing a system configuration including a motor drive device.

The motor winding temperature detector (winding temperature detection unit) 50 detects the winding temperature of the motor M, and outputs it to the motor demagnetization temperature protection threshold setting unit 45 every moment.

The motor demagnetization temperature protection threshold setting unit 45 sets the demagnetization protection threshold based on the motor winding temperature input from the motor winding temperature detector 50 , and outputs it to the motor demagnetization protection overcurrent determination unit 46 .

The motor demagnetization protection overcurrent determination unit 46 stops the processing of the drive signal generation unit 44 when the motor current exceeds the demagnetization protection threshold based on the motor current and the demagnetization protection threshold.

In addition, since the process performed by the motor winding temperature detector 50, the motor demagnetization protection threshold value setting part 45, and the motor demagnetization protection overcurrent determination part 46 is the same as that of 2nd Embodiment, detailed description is abbreviate|omitted.

In addition, the processing of the inverter control unit 40C is executed with the intervention of a microcomputer. That is, the demagnetization protection threshold is set extremely finely according to the temperature characteristics of the switching elements and the temperature characteristics (low-temperature demagnetization characteristics or high-temperature demagnetization characteristics) of the permanent magnets of the motor M, and the inverter circuit 11 is adjusted as necessary. The drive stops.

On the other hand, the processing of the element short-circuit protection unit 12 is executed without intervening a microcomputer. Accordingly, the element short-circuit protection unit 12 stops the drive of the inverter circuit 11 within several μsec from the time when the motor current exceeds the element short-circuit protection threshold.

<effect>

According to the motor drive device 100C according to the present embodiment, the processing of the inverter control unit 40C is executed using a microcomputer. Thus, an appropriate element temperature protection threshold can be set based on the temperature of the switching element input from the element temperature detector 60, and an appropriate demagnetization can be set based on the temperature of the motor winding input from the motor winding temperature detector 50. protection threshold. That is, it is possible to drive the motor M with the maximum current while preventing temperature destruction of the switching elements and demagnetization of the permanent magnets included in the motor M.

Therefore, according to the motor drive device 100C according to the present embodiment, the performance of the switching element and the performance of the motor M can be fully utilized, and reliability can be improved.

In addition, by performing processing by the element short-circuit protection unit 12 without intervening in a microcomputer, it is possible to stop the drive of the inverter circuit 11 within several μsec after overcurrent detection. Accordingly, it is possible to reliably prevent the switching elements included in the inverter circuit 11 from being destroyed by overcurrent.

"Modification"

As mentioned above, although the motor drive apparatus concerning this invention was demonstrated based on each embodiment, embodiment of this invention is not limited to these description, Various changes etc. are possible.

For example, in the above-mentioned third and fourth embodiments, the temperature of the switching element is detected by the element temperature detector 60 , but the present invention is not limited thereto. That is, instead of the element temperature detector 60 (see FIG. 7 ), a power module temperature detection unit (not shown) for detecting the surface temperature of the power module 10 (see FIG. 7 ) may be provided to indirectly detect the switching element temperature. temperature.

In this case, the correlation between the temperature of the switching element and the element temperature protection threshold is replaced by the correlation between the surface temperature of the power module 10 including the inverter circuit 11 and the element temperature protection threshold.

That is, the inverter control unit 40 sets the element temperature protection threshold in accordance with the temperature input from the above-mentioned power module temperature detection unit, and stops the drive of the switching element when the motor current exceeds the element temperature protection threshold.

As a result, even when the power module 10 is used, the temperature protection of the switching elements can be reliably performed, so that the installation structure of the temperature detector (power module temperature detection unit) and the drawing structure of the signal line become simple, and the size can be reduced. manufacturing cost.

In addition, instead of the element temperature detection unit (see FIG. 7 ), a board temperature detection unit (not shown) for detecting the surface temperature of a board (not shown) on which the inverter circuit 11 is mounted may be provided. The temperature of the switching element is thus detected indirectly.

In this case, the inverter control unit 40 sets the element temperature protection threshold according to the temperature input from the above-mentioned substrate temperature detection unit, and stops driving the switching element when the motor current exceeds the element temperature protection threshold.

Accordingly, even when the substrate temperature detection unit is used, the temperature protection of the element can be reliably performed, and the mounting structure of the temperature detector and the drawing structure of the signal line are simplified, and the manufacturing cost can be reduced.

In addition, instead of the element temperature detector 60 (refer to FIG. 7 ), a heat sink temperature detection unit (not shown) for detecting the temperature of a heat sink (not shown) cooling the inverter circuit 11 may be provided, thereby indirectly ground to detect the temperature of the switching element.

In this case, the inverter control unit 40 sets the element temperature protection threshold according to the temperature input from the above-mentioned heat sink temperature detection unit, and makes the driving of the switching element when the motor current exceeds the element temperature protection threshold. stop.

In addition, in each of the above-mentioned embodiments, the case where all the switching elements included in the inverter circuit 11 are IGBTs has been described, but the present invention is not limited thereto.

That is, at least one switching element included in the inverter circuit 11 may be a MOSFET (Metal-Oxide-Semiconductor Field-Effect Transistor), and the correlation with the element temperature protection threshold may be set based on the temperature of the MOSFET.

Among them, MOSFETs have larger losses (that is, generated heat) than IGBTs when the current increases. In particular, even a MOSFET having a super junction structure among MOSFETs has high efficiency even when the current value is small, but since the loss increases when the current value increases, it is easy to cause thermal runaway.

Therefore, the temperature of the MOSFET type switching element is detected by the element temperature detector 60 , and the element temperature protection threshold value corresponding to the temperature is set by the element temperature protection threshold value setting unit 47 . Accordingly, temperature protection of the switching element (including prevention of thermal runaway of the MOSFET) can be reliably performed, and efficient operation can be performed in normal times.

In addition, in the second embodiment and the fourth embodiment described above, although the winding temperature of the motor M is detected by the motor winding temperature detector 50, the present invention is not limited thereto. That is, a compressor (not shown) driven by the motor M may be provided instead of the motor winding temperature detector 50 (see FIG. A profile temperature detection unit (not shown) is used to indirectly detect the winding temperature of the motor M.

That is, the correlation between the winding temperature of the motor M and the demagnetization protection threshold is replaced by the correlation between the external temperature of the compressor and the demagnetization protection threshold.

In this case, the inverter control unit 40 sets the demagnetization protection threshold value corresponding to the temperature input from the above-mentioned external temperature detection unit, and stops the driving of the switching element when the motor current exceeds the demagnetization protection threshold value. .

Accordingly, since the motor demagnetization protection is performed based on the correlation between the external temperature of the compressor and the motor demagnetization protection threshold value, the demagnetization protection of the motor M can be appropriately performed. In addition, the installation structure of the temperature detector (outside temperature detection unit) and the lead-out structure of the signal line are simplified compared with the case where the temperature detector is provided inside the high-pressure compressor, and the manufacturing cost can be reduced.

Therefore, it is possible to provide a fluid compression system capable of appropriately preventing demagnetization of the permanent magnets included in the electric motor M. FIG.

In addition, instead of the above-mentioned motor winding temperature detector 50 (see FIG. 4 ), it is also possible to detect the temperature of the discharge pipe by detecting the temperature of the discharge pipe (not shown) of the compressor (not shown) driven by the motor M. A unit (not shown) indirectly detects the winding temperature of the motor M.

In this case, the inverter control unit 40 sets the demagnetization protection threshold value corresponding to the temperature input from the discharge pipe temperature detection unit described above, and when the motor current exceeds the demagnetization protection threshold value, the switching element The drive stops.

Thereby, the demagnetization protection of the motor M can be reliably performed, and the mounting structure of the temperature detector (discharge pipe temperature detection means) and the drawing structure of the signal line are simplified, and the manufacturing cost can be reduced.

In addition, the motor may be estimated based on the external temperature of the compressor input from an external temperature detection unit (not shown) that detects the external temperature of the compressor and the current detection value input from the current detector 20. M winding temperature.

The temperature of the winding of the motor M is higher than the temperature of the outside of the compressor due to heat generation (motor loss) associated with the flow of current. Therefore, using the current detection value input from the current detector 20 as a parameter, it is corrected to what extent the winding temperature of the motor M is higher than the external temperature of the compressor.

In this case, the inverter control unit 40 calculates the heat generated by the motor M, that is, the motor loss, based on the external temperature input from the external temperature detection unit and the current value input from the current detector 20, and correspondingly The winding temperature of the motor M is estimated from the calculated motor loss. That is, the winding temperature of the motor M is corrected using the current detection value input from the current detector 20 as a parameter.

Further, the inverter control unit 40 sets a demagnetization protection threshold in accordance with the estimated motor winding temperature, and stops driving of the switching element when the motor current exceeds the demagnetization protection threshold.

Accordingly, the winding temperature of the motor M can be reproduced with high precision, the operable range of the motor M can be expanded, and the demagnetization protection of the motor M can be performed more reliably.

In addition, the motor may be estimated based on the discharge pipe temperature of the compressor input from a discharge pipe temperature detection unit (not shown) that detects the discharge pipe temperature of the compressor and the current detection value input from the current detector 20. M winding temperature. In this case, the winding temperature of the motor M is corrected using the current detection value input from the current detector 20 as a parameter, as in the above case.

In addition, since the processing of the inverter control unit 40 is the same as the above case, the description thereof will be omitted.

In addition, in each of the above-described embodiments and modified examples, a DC brushless motor using a permanent magnet may be used as the motor M. In addition, a compressor (not shown) can be used as a compressor of a high-pressure chamber driven by the DC brushless motor.

In this way, by using the DC brushless motor as the motor M for the compressor, high energy efficiency can be realized. In addition, it is possible to provide a fluid compression system that can appropriately protect the switching elements of the inverter circuit 11 and that can prevent demagnetization of the motor M reliably.

In addition, as a compressor (not shown), a compressor in a low-voltage chamber driven by a DC brushless motor may be used instead of the above-mentioned motor winding temperature detector 50 (see FIG. 4 ), or a compressor installed in an outdoor device (not shown) may be used. Shown) frost detection unit (not shown) and indoor temperature detection unit (not shown) installed in the indoor equipment (not shown) instead.

In this case, during heating operation, the winding temperature of the motor M is indirectly detected by the frost detection means provided in the outdoor equipment. Thereafter, the inverter control unit 40 sets the demagnetization protection threshold based on the temperature input from the frost detection unit, and stops driving of the switching element when the motor current exceeds the demagnetization protection threshold.

On the other hand, during the cooling operation, the winding temperature of the motor M is indirectly detected by the indoor temperature detection means provided in the indoor equipment. Thereafter, the inverter control unit 40 sets the demagnetization protection threshold according to the temperature input from the indoor temperature detection unit, and stops driving of the switching element when the motor current exceeds the demagnetization protection threshold.

That is, the inverter control unit 40 estimates the winding temperature by using the thermal correlation between the winding temperature of the motor M and the frosting temperature of the heat exchanger, or the thermal correlation between the winding temperature of the motor M and the room temperature. temperature.

Thereby, demagnetization of the motor M can be reliably prevented, and the mounting structure of the temperature detector (the frost detection means and the indoor temperature detection means) and the lead-out structure of the signal line are simplified, and the manufacturing cost can be reduced.

In addition, an air conditioner (not shown) may be equipped with the fluid compression system demonstrated above. In this case, the compressor including the above-mentioned electric motor M is installed in outdoor equipment.

Thereby, the protection of a switching element and the demagnetization protection of the motor M can be reliably performed, and the air conditioner with high reliability can be provided. In addition, the air conditioner can maximize the air-conditioning capacity even when a large capacity is required in a low-temperature or high-temperature environment with a large air-conditioning load.

In addition, in each of the above-mentioned embodiments, a case where a permanent magnet type synchronous motor is used as the motor M has been described, but the present invention is not limited thereto. That is, each of the above-described embodiments can be similarly applied to other synchronous motors such as a winding-type synchronous motor and a reluctance motor.

In addition, in each of the above-mentioned embodiments, it has been described that the AC voltage input from the AC power supply 200 is converted into a DC voltage by the converter circuit 300, and the DC voltage is further converted into a predetermined voltage by driving the switching elements of the inverter circuit 11. The case of AC voltage, but not limited to this. For example, a DC voltage may be input to the inverter circuit 11 from a storage battery (DC power supply: not shown).

Alternatively, an active circuit (not shown) may be used to actively control the DC voltage.

Claims (19)

1. a motor drive, possesses: has switch element, and will become from the DC voltage conversion of DC supply input The inverter circuit of alternating voltage；And to supplying the current detecting list detected to the DC current of described inverter circuit Unit, and drive motor by the alternating electromotive force exported from described inverter circuit according to described conversion,

Described motor drive is characterised by possessing:

Control unit, it controls the on/off of described switch element；And

Element short protected location, it exceedes for preventing described inverter at the current value inputted from described current detecting unit In the case of the short-circuit protection threshold value of the short circuit in circuit, stop instruction signal is exported to inverter driving circuit, make described The driving of switch element stops,

Described control unit estimates according to the current value inputted from described current detecting unit and flows into the electronic of described motor Electromechanics flows, and the magnetic that subtracts exceeded with the temperature protection of described switch element and/or described motor at this motor current is protected In the case of other relevant current thresholds, perform to make the process driving stopping of described switch element,

The current value detected by described current detecting unit is imported into described element short protected location, and is imported into Carry out in the microcomputer of the calculation process relevant to described control unit,

The process of described element short protected location is performed in the case of staying out of described microcomputer,

The process of described control unit is performed in the case of getting involved described microcomputer,

Detect that the current value of described input exceedes described short-circuit protection threshold value and plays to institute from described element short protected location The time till inverter driving circuit exports described stop instruction signal of stating is the hardware electricity staying out of described microcomputer Required time under road.

Motor drive the most according to claim 1, it is characterised in that

Described motor drive possesses winding temperature detector unit, and this winding temperature detector unit detects directly or indirectly The winding temperature of described motor,

What other current thresholds described included the subtracting magnetic characteristic of magnet having based on described motor and set subtracts magnetic protection threshold Value,

Described subtract magnetic protection threshold value temperature characterisitic have described short-circuit protection threshold value be more than described in subtract magnetic protection threshold value temperature Region,

Described control unit subtracts magnetic protection described in setting from the winding temperature of described winding temperature detector unit input Threshold value, and in the case of subtracting magnetic protection threshold value at described motor current described in exceeding, make the driving of described switch element stop.

Motor drive the most according to claim 1, it is characterised in that

Described motor drive possesses component temperature detector unit, and this component temperature detector unit detects directly or indirectly The temperature of described switch element,

The component temperature protection threshold value that other current thresholds described include element characteristic based on described switch element and set,

The temperature characterisitic of described component temperature protection threshold value has described short-circuit protection threshold value and protects threshold more than described component temperature The temperature province of value,

Described control unit is corresponding to setting institute from the temperature of the described switch element of described component temperature detector unit input State component temperature protection threshold value, and in the case of described motor current exceedes described component temperature protection threshold value, make described The driving of switch element stops.

Motor drive the most according to claim 1, it is characterised in that

Described motor drive possesses:

Winding temperature detector unit, it detects the winding temperature of described motor directly or indirectly；And

Component temperature detector unit, it detects the temperature of described switch element directly or indirectly,

What other current thresholds described included the subtracting magnetic characteristic of magnet having based on described motor and set subtracts magnetic protection threshold Value and element characteristic based on described switch element and the component temperature protection threshold value that sets,

Described subtract magnetic protection threshold value temperature characterisitic have described short-circuit protection threshold value be more than described in subtract magnetic protection threshold value temperature Region,

The temperature characterisitic of described component temperature protection threshold value has described short-circuit protection threshold value and protects threshold more than described component temperature The temperature province of value,

Described control unit subtracts magnetic protection described in setting from the winding temperature of described winding temperature detector unit input Threshold value, and corresponding to setting described component temperature from the temperature of the described switch element of described component temperature detector unit input Protection threshold value, and subtract described in exceeding at described motor current among magnetic protection threshold value and described component temperature protection threshold value In the case of at least one party, the driving of described switch element is made to stop.

5. according to the motor drive described in claim 2 or 4, it is characterised in that

The magnet that described motor has have become low temperature along with the temperature of this magnet and subtract that magnetoelectricity flow valuve diminishes to subtract magnetic special Property,

Described control unit is set to based on described the subtracting magnetic characteristic of magnet: along with inputting from described winding temperature detector unit Described winding temperature become low temperature and subtract magnetic protection threshold value described in making and diminish.

Motor drive the most according to claim 5, it is characterised in that

The described magnet that described motor has is ferrimagnet.

7. according to the motor drive described in claim 2 or 4, it is characterised in that

The magnet that described motor has have become high temperature along with the temperature of this magnet and subtract that magnetoelectricity flow valuve diminishes to subtract magnetic special Property,

Described control unit is set to based on described the subtracting magnetic characteristic of magnet: along with inputting from described winding temperature detector unit Described winding temperature become high temperature and subtract magnetic protection threshold value described in making and diminish.

Motor drive the most according to claim 7, it is characterised in that

The described magnet that described motor has is rare earth magnet.

9. according to the motor drive described in claim 3 or 4, it is characterised in that

The described component temperature detector unit of the temperature indirectly detecting described switch element is to including described inverter circuit Surface temperature at interior power model carries out the temperature of power module detector unit detected,

Described control unit is corresponding to setting described component temperature from the temperature of described temperature of power module detector unit input Protection threshold value, and in the case of described motor current exceedes described component temperature protection threshold value, make described switch element Drive and stop.

10. according to the motor drive described in claim 3 or 4, it is characterised in that

The described component temperature detector unit of the temperature indirectly detecting described switch element is to being equipped with described inverter electricity The surface temperature of the substrate on road carries out the substrate temperature detector unit detected,

Described control unit is corresponding to setting the protection of described component temperature from the temperature of described substrate temperature detector unit input Threshold value, and in the case of described motor current exceedes described component temperature protection threshold value, make the driving of described switch element Stop.

11. according to the motor drive described in claim 3 or 4, it is characterised in that

The described component temperature detector unit of the temperature indirectly detecting described switch element is to cooling down described inverter circuit The temperature of fin carry out the heatsink temperature detector unit that detects,

Described control unit is protected corresponding to setting described component temperature from the temperature of described heatsink temperature detector unit input Protect threshold value, and in the case of described motor current exceedes described component temperature protection threshold value, make driving of described switch element Dynamic stopping.

12. according to the motor drive described in claim 3 or 4, it is characterised in that

At least one among the described switch element that described inverter circuit has is MOSFET,

Described component temperature detector unit detects the temperature of described MOSFET and exports to described control unit,

Described control unit is corresponding to setting described from the temperature of the described MOSFET of described component temperature detector unit input Component temperature protection threshold value.

13. 1 kinds of fluid compression systems, it is characterised in that possess:

Motor drive described in claim 2 or 4；And

The compressor being driven by described motor,

The described winding temperature detector unit of the winding temperature indirectly detecting described motor is the gabarit to described compressor Temperature carries out the gabarit temperature detecting unit detected,

Described control unit subtracts magnetic protection threshold value described in setting from the temperature of described gabarit temperature detecting unit input, And in the case of subtracting magnetic protection threshold value at described motor current described in exceeding, make the driving of described switch element stop.

14. fluid compression systems according to claim 13, it is characterised in that

Described motor is the use of the DC Brushless Motor of permanent magnet,

Described compressor is the compressor of the altitude chamber driven by described DC Brushless Motor.

15. 1 kinds of fluid compression systems, it is characterised in that possess:

Motor drive described in claim 2 or 4；And

The compressor being driven by described motor,

The described winding temperature detector unit of the winding temperature indirectly detecting described motor is the discharge to described compressor Pipe arrangement temperature carries out the discharge pipe arrangement temperature detecting unit detected,

Described control unit subtracts magnetic protection described in setting from the temperature of described discharge pipe arrangement temperature detecting unit input Threshold value, and in the case of subtracting magnetic protection threshold value at described motor current described in exceeding, make the driving of described switch element stop.

16. 1 kinds of fluid compression systems, it is characterised in that possess:

Motor drive described in claim 2 or 4；And

The compressor being driven by described motor,

The described winding temperature detector unit of the winding temperature indirectly detecting described motor is the gabarit to described compressor Temperature carries out the gabarit temperature detecting unit that detects and the DC current to supply to described inverter circuit detects Described current detecting unit,

Described control unit,

Based on the temperature inputted from described gabarit temperature detecting unit and the current value inputted from described current detecting unit Calculate heat, the i.e. generator loss produced by described motor,

The described generator loss corresponding to be calculated to estimate the winding temperature of described motor,

The described winding temperature corresponding to be estimated subtracts magnetic protection threshold value described in setting,

The driving of described switch element is made to stop in the case of subtracting magnetic protection threshold value at described motor current described in exceeding.

17. 1 kinds of fluid compression systems, it is characterised in that possess:

Motor drive described in claim 2 or 4；And

The compressor being driven by described motor,

The described winding temperature detector unit of the winding temperature indirectly detecting described motor is the discharge to described compressor Pipe arrangement temperature carries out the discharge pipe arrangement temperature detecting unit that detects and flows to the unidirectional current of supply to described inverter circuit The described current detecting unit of row detection,

Described control unit,

Based on the temperature inputted from described discharge pipe arrangement temperature detecting unit and the electric current inputted from described current detecting unit Value calculates heat, the i.e. generator loss produced by described motor,

The described generator loss corresponding to be calculated to estimate the winding temperature of described motor,

The described winding temperature corresponding to be estimated subtracts magnetic protection threshold value described in setting,

The driving of described switch element is made to stop in the case of subtracting magnetic protection threshold value at described motor current described in exceeding.

18. 1 kinds of fluid compression systems, it is characterised in that possess:

Motor drive described in claim 2 or 4；And

By the compressor of the low-pressure chamber of described motor-driven,

Described motor is the use of the DC Brushless Motor of permanent magnet,

When heating runs, indirectly detected the winding of described motor by the frosting detector unit being arranged at outdoor equipment Temperature,

When refrigeration runs, indirectly detect described motor by the indoor temperature detector unit being arranged at indoor equipment Winding temperature,

Described control unit sets corresponding to the temperature inputted from described frosting detector unit or described indoor temperature detector unit Subtract magnetic protection threshold value described in Ding, and make described switch unit in the case of subtracting magnetic protection threshold value described in exceeding at described motor current The driving of part stops.

19. 1 kinds of air conditioners, it is characterised in that possess the fluid compression system described in claim 13.