JP7205306B2 - Rotating machine system and magnetic flux linkage estimation method - Google Patents

Description

The present invention relates to a rotating machine system and a magnetic flux linkage estimation method.

A rotating machine such as a permanent magnet synchronous motor (PMSM) includes a rotor having permanent magnets and a stator having multi-phase coils. In a rotating machine system using such a rotating machine, for example, in order to perform position sensorless control, to estimate the temperature of the permanent magnets provided in the rotor, or to perform direct torque control, a chain of permanent magnets is used. The alternating magnetic flux may be estimated in real time.

Patent Literature 1 below discloses an example of a conventional method for estimating a magnetic flux linkage. Specifically, in Patent Document 1 below, in a rotating machine provided with a position detector for detecting the position of the rotor, the rotation speed of the rotor calculated based on the detection result of the rotor position and d− A method of estimating the state quantity related to the armature flux linkage based on the voltage command on the q axis and the current command on the dq axis is disclosed.

Japanese Patent No. 6218976

By the way, if the method disclosed in the above-mentioned Patent Document 1 is used, the interlinkage magnetic flux of the permanent magnet can be estimated in real time while the rotating machine is being driven. However, the method disclosed in the above-mentioned Patent Document 1 estimates the interlinkage magnetic flux of the permanent magnet by performing various calculations (for example, calculating the rotation speed of the rotor based on the detection result of the rotor position). Therefore, there is a problem that the error is large. Moreover, in order to shorten the time required for calculation, there is also the problem that a calculation device with high calculation capability is required.

The interlinkage magnetic flux of the permanent magnet is the voltage (line It can also be obtained from the voltage between The interlinkage magnetic flux obtained by this method is obtained from the induced voltage of the coil, and does not require the various calculations described above, and therefore has high accuracy. However, this method cannot be used in a state in which the rotating machine is being driven (a state in which a driving current is being supplied to the rotating machine).

The present invention has been made in view of the above circumstances, and is capable of estimating the interlinkage magnetic flux of a permanent magnet with high accuracy while a rotating machine is being driven without requiring an arithmetic device with high arithmetic performance. It is an object of the present invention to provide a rotating machine system and an interlinkage magnetic flux estimation method.

In order to solve the above problems, a rotating machine system (1) according to one aspect of the present invention includes a rotating machine (20) including a rotor having permanent magnets and a stator having multi-phase coils; a drive circuit (30) for supplying drive power to the multi-phase coils of the rotating machine, a detector (41) for detecting the line-to-line voltage of the rotating machine, and controlling the drive circuit to control the multi-phase coils of the rotating machine stop the supply of the driving power for a predetermined period of time, acquire the line voltage detected by the detector within the certain period of time, and use the acquired line voltage to chain in the rotating machine and a control unit (42) for estimating the alternating magnetic flux (φm).

Further, in the rotating machine system according to one aspect of the present invention, the control unit controls the drive circuit to restart the supply of the drive power in accordance with the rotation of the rotor after the certain period of time has elapsed.

Further, in the rotating machine system according to one aspect of the present invention, the control unit can stop the supply of the driving power to the rotating machine, acquire the line voltage, and estimate the interlinkage magnetic flux in the rotating machine by a human. Repeat at intervals longer than the longest wavelength in the audible range.

Further, in the rotating machine system according to an aspect of the present invention, the control unit acquires the maximum or minimum value of the line voltage, and uses the acquired maximum or minimum value of the line voltage to Estimate the flux linkage at

Alternatively, in the rotating machine system according to an aspect of the present invention, the control unit acquires the maximum and minimum values of the line voltage, and uses the difference between the acquired maximum and minimum values of the line voltage to A magnetic flux linkage in the rotating machine is estimated.

Alternatively, in the rotating machine system according to an aspect of the present invention, the control unit estimates the interlinkage magnetic flux in the rotating machine by integrating the absolute value of the line voltage over one cycle of the line voltage. do.

Further, in the rotating machine system according to one aspect of the present invention, the drive circuit is an inverter including a plurality of switching elements (SW1 to SW6), and the control unit controls the switching frequency (f _SW ) of the switching elements. When the ratio of the frequency (f _LV ) of the line voltage is equal to or less than the allowable error (Err) of the interlinkage magnetic flux in the rotating machine, the line voltage is obtained within one cycle, and the chain in the rotating machine is obtained. If it is greater than the permissible error of the alternating magnetic flux, the line voltage is acquired over a plurality of cycles.

A magnetic flux linkage measurement method according to an aspect of the present invention specifies in advance the supply of drive power to the multi-phase coils of a rotating machine (20) that includes a rotor having permanent magnets and a stator having multi-phase coils. a step (S11) of stopping the rotating machine for a certain period of time; a step of acquiring the line voltage detected by a detector (41) for detecting the line voltage of the rotating machine within the certain period of time (S12); and a step (S13) of estimating the interlinkage magnetic flux (φm) in the rotating machine using the obtained line voltage.

ADVANTAGE OF THE INVENTION According to this invention, there exists an effect that the magnetic flux linkage of a permanent magnet can be estimated with high precision in the state in which the rotating machine is driving, without requiring the arithmetic unit with high arithmetic performance.

1 is a block diagram showing the main configuration of a rotating machine system according to an embodiment of the present invention; FIG. It is a figure for demonstrating the estimation method of the interlinkage magnetic flux in one Embodiment of this invention. It is a figure for demonstrating the acquisition method of the voltage between lines in one Embodiment of this invention. FIG. 10 is a diagram for explaining the interval of performing a series of operations for estimating interlinkage magnetic flux in one embodiment of the present invention; 4 is a flow chart showing an operation example of the rotary machine system according to the embodiment of the present invention;

Hereinafter, a rotating machine system and a magnetic flux linkage estimation method according to an embodiment of the present invention will be described in detail with reference to the drawings.

<Rotating machine system>
FIG. 1 is a block diagram showing the essential configuration of a rotating machine system according to one embodiment of the present invention. As shown in FIG. 1 , a rotating machine system 1 of this embodiment includes a power supply device 10 , a motor 20 (rotating machine), an inverter 30 (drive circuit), and an inverter control section 40 . Such a rotating machine system 1 drives the motor 20 by converting the power supplied from the power supply device 10 into drive power by the inverter 30 and supplying the power to the motor 20 under the control of the inverter control unit 40. System.

The power supply device 10 is a device that supplies power (direct current power) necessary for driving the motor 20 . A secondary battery such as a nickel-metal hydride battery or a lithium-ion battery can be used as the power supply device 10 . Also, the power supply device 10 can use an electric double layer capacitor (capacitor) instead of the secondary battery. Furthermore, the power supply device 10 may be a device that converts AC power supplied from an AC power source into DC power.

Motor 20 is an electric motor driven by drive power supplied from inverter 30 under the control of inverter control unit 40 . In this embodiment, the motor 20 is a three-phase (U-phase, V-phase, W-phase) brushless motor. Specifically, the motor 20 includes a rotor having permanent magnets, and a stator in which coils corresponding to three phases (U-phase, V-phase, and W-phase) are sequentially wound in the rotation direction of the rotor. stator). The coils of each phase provided in the motor 20 are connected to the inverter 30, and the power of each phase of the three-phase AC power is supplied to the coils of each phase as driving power.

Inverter 30 converts the DC power supplied from power supply device 10 into drive power (three-phase AC power) under the control of inverter control unit 40 and supplies the drive power (three-phase AC power) to motor 20 . The inverter 30 has input terminals T11, T12 and output terminals T21, T22, T23. The input terminal T11 is connected to the positive terminal of the power supply 10 and the input terminal T12 is connected to the negative terminal of the power supply 10 . The output terminal T21 is connected to the U-phase coil of the motor 20, the output terminal T22 is connected to the V-phase coil of the motor 20, and the output terminal T23 is connected to the W-phase coil of the motor 20. It is Therefore, the inverter 30 converts the DC power input from the input terminals T11 and T12 into three-phase AC power and outputs the three-phase AC power from the output terminals T21 to T23.

Inverter 30 includes a plurality of switching elements. Specifically, as shown in FIG. 1, six switching elements SW1 to SW6 are provided. The inverter control unit 40 controls switching between the ON state and the OFF state of these switching elements SW1 to SW6, so that the DC power supplied from the power supply device 10 is converted into three-phase AC power and supplied to the motor 20. .

In this embodiment, a case where the switching elements SW1 to SW6 provided in the inverter 30 are FETs (Field Effective Transistors) will be described, but the present invention is not limited to this. The switching elements SW1 to SW6 provided in the inverter 30 may be, for example, IGBTs (insulated gate bipolar transistors) or BJTs (bipolar junction transistors). Further, the number of switching elements provided in inverter 30 is not limited to six.

The switching elements SW1 and SW2 are connected in series between the input terminals T11 and T12. The switching elements SW3 and SW4 are connected in series between the input terminals T11 and T12. The switching elements SW5 and SW6 are connected in series between the input terminals T11 and T12. In other words, the switching elements SW1 and SW2 connected in series, the switching elements SW3 and SW4 connected in series, and the switching elements SW5 and SW6 connected in series are connected in parallel between the input terminals T11 and T12.

A drain terminal of the switching element SW1 is connected to the input terminal T11. A source terminal of the switching element SW2 is connected to the input terminal T12. A connection point between the source terminal of the switching element SW1 and the drain terminal of the switching element SW2 is connected to the output terminal T21. A U-phase coil of the motor 20 is connected to the output terminal T21.

A drain terminal of the switching element SW3 is connected to the input terminal T11. A source terminal of the switching element SW4 is connected to the input terminal T12. A connection point between the source terminal of the switching element SW3 and the drain terminal of the switching element SW4 is connected to the output terminal T22. A V-phase coil of the motor 20 is connected to the output terminal T22.

A drain terminal of the switching element SW5 is connected to the input terminal T11. A source terminal of the switching element SW6 is connected to the input terminal T12. A connection point between the source terminal of the switching element SW5 and the drain terminal of the switching element SW6 is connected to the output terminal T23. A W-phase coil of the motor 20 is connected to the output terminal T23.

Gate terminals of the switching elements SW1 to SW6 are connected to the inverter control section 40 .

The inverter control unit 40 controls driving of the inverter 30 . Specifically, the inverter control unit 40 includes a line voltage detection unit 41 and a control unit 42, and refers to the detection result of the line voltage detection unit 41 to control switching of the switching elements SW1 to SW6. The line voltage detection unit 41 detects the voltage between the U phase and the V phase (the line voltage V _UV ), the voltage between the V phase and the W phase (the line voltage V _VW ), and the voltage between the W phase and the U phase ( At least one of the line voltages V _WU ) is detected. In this embodiment, for ease of understanding, the line voltage detector 41 detects the line voltage _VUV .

The control unit 42 controls switching of the switching elements SW1 to SW6 at an arbitrary switching frequency. For example, the control unit 42 outputs a control signal to the gate terminals of the switching elements SW1 to SW6 to perform switching control to turn on or off the switching elements SW1 to SW6. This control signal is, for example, a PWM (Pulse Width Modulation) signal.

The control unit 42 temporarily stops the supply of driving power to the motor 20 while the motor 20 is being driven, and based on the obtained detection result of the line voltage detection unit 41, interlinkage magnetic flux in the motor 20 (permanent magnet Estimate the flux linkage). Specifically, the control unit 42 controls the inverter 30 to supply drive power to the coils of each phase (U-phase, V-phase, W-phase) of the motor 20 for a predetermined period of time (for example, 1 to 5 msec), and the line voltage (line voltage V _UV ) detected by the line voltage detection unit 41 is acquired. Then, the control unit 42 estimates the interlinkage magnetic flux in the motor 20 using the obtained line voltage. It should be noted that the control unit 42 controls the inverter 30 to restart the supply of drive power in accordance with the rotation of the rotor of the motor 20 after the above-described fixed period of time has elapsed.

<Method for estimating magnetic flux linkage>
Next, a specific method for estimating the interlinkage magnetic flux will be described. The control unit 42 estimates the interlinkage magnetic flux φm in the motor 20 by, for example, one of the following three methods (A1) to (A3). The method described below is merely an example, and it is also possible to estimate the interlinkage magnetic flux φm using methods other than those shown. Below, the frequency of the line voltage is assumed to be f [Hz]. FIG. 2 is a diagram for explaining a method of estimating interlinkage magnetic flux in one embodiment of the present invention.

(A1) Method using maximum or minimum value of line _{voltage As} shown in FIG. This is a method of estimating the interlinkage magnetic flux φm using the following equation (1). Since this method uses only one of the maximum and minimum values of the line voltage, it is possible to estimate the interlinkage magnetic flux φm in a short period of time.

(A2) Method using the difference between the maximum and minimum values of the line voltage Obtain the maximum and minimum values of the line voltage, and as shown in FIG. This is a method of obtaining the difference V _pp [V] from the value and estimating the interlinkage magnetic flux φm using the following equation (2). Since this method uses both the maximum and minimum values of the line voltage, the effect of the line voltage offset can be eliminated.

(A3) Method of Integrating Line Voltage Obtain the line voltage V [V] for one cycle, and integrate the line voltage V using the following equation (3) (the absolute value of the line voltage V is , integrated over one cycle of the line voltage) to estimate the interlinkage magnetic flux φm. In this method, since the absolute value of the line voltage V is integrated over one period of the line voltage, the influence of the line voltage offset can be eliminated.

<How to obtain the line voltage>
Next, a specific method for acquiring the line voltage will be described. The line voltage of the motor 20 changes depending on the rotation speed and the number of pole pairs of the motor 20 . Therefore, it is necessary to change the method of acquiring the line voltage according to the rotation speed and the number of pole pairs of the motor 20 . FIG. 3 is a diagram for explaining a method of acquiring line voltages in one embodiment of the present invention. The acquisition method described here is a method of acquiring the maximum value or minimum value of the line voltage.

Let f _SW be the switching frequency of the switching control performed by the control unit 42 , f _LV be the frequency of the line voltage, and Err [%] be the allowable error of the interlinkage magnetic flux φm. The control unit _{42 performs} the _following ( _B1 ), ( As per B2), change the method of obtaining the line voltage.

(B1) When f _LV /f _SW ≤ Err When the frequency f _LV of the line voltage is lower than the switching frequency f _SW and the relational expression f _LV /f _SW ≤ Err holds, the controller 42 , the line voltage is obtained within one cycle, as shown in FIG. Specifically, the control unit 42 temporarily stops the supply of the drive current to the motor 20 (PWM off), the maximum value V _p [V] (or the minimum value V _p [V]) of the line voltage is obtained. The control unit 42 obtains the phase angle and speed of the rotor of the motor 20 using the detection result of the line voltage detection unit 41 and uses them for control.

(B2) When f _LV /f _SW >Err When the frequency f _LV of the line voltage is higher than the switching frequency f _SW and the relational expression f _LV /f _SW >Err holds, the control unit 42 , the line voltage is obtained over a plurality of cycles, as shown in FIG. 3(b). When the frequency _fLV of the line voltage is higher than the switching frequency _fSW , it is difficult to temporarily stop the supply of the drive current to the motor 20 at a specific phase angle as in (B1) above. Therefore, it is conceivable that the maximum value V _p [V] (or the minimum value V _p [V]) of the line voltage cannot be obtained with only one cycle. For this reason, as shown in FIG. 2B, the operation of stopping the supply of the driving current to the motor 20 at a predetermined cycle shorter than the cycle of the line voltage and obtaining the line voltage is repeatedly performed over a plurality of cycles. . The maximum line voltage obtained in this manner is set as the maximum line voltage V _p [V] (or the minimum line voltage is set as the minimum line voltage V _p [V]).

<Implementation interval>
Next, the interval between operations for estimating the interlinkage magnetic flux φm (supply of drive power to the motor 20, acquisition of the line voltage, and estimation of the interlinkage magnetic flux φm in the motor 20) will be described. FIG. 4 is a diagram for explaining intervals of a series of operations for estimating interlinkage magnetic flux in one embodiment of the present invention.

The control unit 42 repeatedly performs a series of operations for estimating the interlinkage magnetic flux φm at time intervals longer than the longest wavelength in the human audible range. The reason why a series of operations are performed at such time intervals is to prevent abnormal noise from being generated. As described above, in this embodiment, the supply of drive power to the motor 20 is temporarily stopped while the motor 20 is being driven in order to estimate the interlinkage magnetic flux φm. If the time interval for stopping the supply of the drive power is about the same as the wavelength included in the human audible range, the user will perceive it as an abnormal sound. In order to avoid such abnormal sounds, a series of operations are repeatedly performed at time intervals longer than the longest wavelength in the human audible range.

Here, the human audible range is said to be about 20 [Hz] to 20 [kHz] although there are individual differences. The shortest wavelength in the human audible range is obtained by the reciprocal of the highest frequency, and is approximately 50 [μsec]. Also, the longest wavelength in the human audible range is obtained by the reciprocal of the lowest frequency, which is about 50 [msec]. Therefore, as shown in FIG. 4, the control unit 42 repeats a series of operations for estimating the interlinkage magnetic flux φm at time intervals ΔT longer than the longest wavelength (50 [msec]) in the human audible range.

<Operation of rotating machine system>
FIG. 5 is a flow chart showing an operation example of the rotating machine system according to one embodiment of the present invention. The flowchart shown in FIG. 5 is started, for example, when the motor 20 is driven, and is repeated at a time interval ΔT longer than the longest wavelength (50 [msec]) in the human audible range while the motor 20 is being driven.

When the process of the flowchart shown in FIG. 5 is started, first, the control unit 42 performs control to stop the supply of drive power to the motor 20 for a certain period of time (step S11). Specifically, the inverter 30 is controlled by the control unit 42, and driving power is supplied to the coils of each phase (U-phase, V-phase, W-phase) of the motor 20 for a predetermined period (for example, 1 to 5 msec). degree) is controlled to stop.

Next, while the supply of driving power is stopped, the control unit 42 performs a process of acquiring the line voltage (step S12). Specifically, the control unit 42 performs a process of acquiring the line voltage (line voltage V _UV ) detected by the line voltage detection unit 41 during the certain period of time. For example, depending on the magnitude relationship between the ratio of the frequency f _LV of the line voltage to the switching frequency f _SW (f _LV /f _SW ) and the allowable error Err of the interlinkage magnetic flux φm, the control unit 42 performs the above-described (B1) or the acquisition method of (B2).

Then, the controller 42 performs a process of estimating the interlinkage magnetic flux φm in the motor 20 using the acquired line voltage (step S13). For example, the controller 42 performs a process of estimating the interlinkage magnetic flux φm in the motor 20 by any of the three methods shown in (A1) to (A3) described above. In addition, when the line voltage is obtained by the obtaining method (B1) or the obtaining method (B2) described above, the obtained line voltage is the maximum value V _p [V] (or the minimum value V _p [V]), the process of estimating the interlinkage magnetic flux φm in the motor 20 is performed by the method (A1) or (A2) described above.

After the predetermined period of time during which the supply of the driving power to the motor 20 is stopped, the inverter 30 is controlled by the control unit 42, and the supply of the driving power corresponding to the rotation of the rotor of the motor 20 is resumed. . Specifically, the control unit 42 utilizes the phase angle and speed of the rotor of the motor 20 obtained using the detection result of the line voltage detection unit 41 to generate a rotating magnetic field that synchronizes the rotation. .

As described above, in the present embodiment, the supply of drive power to each phase coil of the motor 20 is stopped for a predetermined period of time, the line-to-line voltage of the motor 20 is detected during this period of time, and the acquired line-to-line voltage The voltage is used to estimate the interlinkage magnetic flux φm in the rotating machine. As a result, the induced voltage induced in the coil by the permanent magnet of the motor 20 is directly detected to estimate the interlinkage magnetic flux φm. It can be estimated with high accuracy. Further, since the interlinkage magnetic flux φm in the motor 20 can be estimated using the formulas (1) to (3) described above, no complicated calculations are required, so a calculation device with high calculation capability is not required.

Although the rotating machine system and the magnetic flux linkage estimation method according to one embodiment of the present invention have been described above, the present invention is not limited to the above-described embodiment, and can be freely modified within the scope of the present invention. For example, in the above-described embodiment, the line voltage _detection unit 41 _detects only the line _{voltage VUV .} You may make it detect the voltage between. Further, the motor 20 may be either a motor provided with a position detection sensor for detecting the position of the rotor or a motor not provided with a position detection sensor.

REFERENCE SIGNS LIST 1 rotating machine system 20 motor 30 inverter 41 line voltage detector 42 control unit Err tolerance of magnetic flux linkage f _SW switching frequency f _LV frequency of line voltage , SW1 to SW6... switching elements, φm... magnetic flux linkage

Claims (7)

A rotating machine comprising a rotor having permanent magnets and a stator having multi-phase coils;
a drive circuit that supplies drive power to the multi-phase coils of the rotating machine;
a detector that detects the line voltage of the rotating machine;
controlling the drive circuit to stop the supply of the drive power to the coils of the multiple phases of the rotating machine for a predetermined period of time, and acquiring the line voltage detected by the detector within the period of time; , a control unit that estimates a magnetic flux linkage in the rotating machine using the acquired line voltage;
with
The control unit repeats stopping the supply of the driving power to the rotating machine, acquiring the line voltage, and estimating the magnetic flux linkage in the rotating machine at time intervals longer than the longest period in the human audible range. conduct,
rotating machine system. 2. The rotating machine system according to claim 1, wherein said control unit controls said drive circuit to restart supply of said drive power in accordance with rotation of said rotor after said fixed period of time has elapsed. 2. The control unit acquires the maximum or minimum value of the line voltage, and uses the acquired maximum or minimum value of the line voltage to estimate the interlinkage magnetic flux in the rotating machine. Item 3. The rotary machine system according to item 2. The control unit acquires the maximum and minimum values of the line voltage, and estimates the interlinkage magnetic flux in the rotating machine using a difference between the acquired maximum and minimum values of the line voltage. 3. The rotating machine system according to claim 1 or 2. 3. The rotating machine according to claim 1 , wherein the control unit estimates the interlinkage magnetic flux in the rotating machine by integrating the absolute value of the line voltage over one cycle of the line voltage. system. The drive circuit is an inverter comprising a plurality of switching elements,
The control unit acquires the line voltage within one cycle when the ratio of the frequency of the line voltage to the switching frequency of the switching element is equal to or less than the allowable error of the interlinkage magnetic flux in the rotating machine. , if it is larger than the allowable error of the interlinkage magnetic flux in the rotating machine, the line voltage is obtained over a plurality of cycles;
The rotating machine system according to any one of claims 1 to 4 . a first step of stopping supply of drive power to the multi-phase coils of a rotating machine comprising a rotor having permanent magnets and a stator having multi-phase coils for a predetermined period of time;
a second step of acquiring the line voltage detected by a detector that detects the line voltage of the rotating machine within the fixed period;
a third step of estimating a magnetic flux linkage in the rotating machine using the obtained line voltage;
including
The first step, the second step, and the third step are repeated at time intervals longer than the longest period in the human audible range,
Magnetic flux linkage estimation method.

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