WO2005034335A1

WO2005034335A1 - Motor operation control device

Info

Publication number: WO2005034335A1
Application number: PCT/JP2004/013654
Authority: WO
Inventors: Harunobu Nukushina
Original assignee: Toshiba Carrier Corporation
Priority date: 2003-10-02
Filing date: 2004-09-17
Publication date: 2005-04-14
Also published as: CN1860675A; CN100448160C; JP2005110470A

Abstract

There is provided a motor operation control device capable of performing stable speed control even at a low rotation speed near to zero. A power conversion unit (3) converts DC current to AC current for supply to a motor (4). Current detection means (8) detects current flowing in the winding of the motor according to the voltage generated in a resistor (6) connected to a current input route for the power conversion unit. Rotor speed estimation means (9) estimates the rpm of the motor according to the torque component of the voltage instruction value supplied to the motor, the excitation component, and the current detected by the current detection means. Waveform generation means (15) generates a drive waveform signal for driving the power conversion unit according to the torque component of the voltage instruction value, the excitation component, and the motor rpm estimated by the rotor speed estimation means. Excitation correction control means (16) increases the excitation component of the voltage instruction value while keeping the motor rpm estimated by the rotor speed estimation means (9) within a range not greater than a predetermined value.

Description

Specification

Motor operation control device

Technical field

The present invention relates to a motor operation control device that detects a winding current of a motor and controls the motor by PWM control.

Background art

[0002] As this type of operation control device, a voltage application circuit that applies a voltage to a motor, two current sensors that respectively detect currents of two motor wires out of three motor wires, A drive control means for applying a driving voltage to the electric motor based on the estimated value while sequentially correcting an error included in the estimated electric angle of the rotor based on the relationship between the voltage and the current; and A polarity determining means for determining the polarity of the rotor at a predetermined timing, wherein the polarity determining means controls a voltage applying circuit so as to apply a predetermined determining voltage; Japanese Patent Application Laid-Open No. 2002-95282 discloses a device including a determination unit that determines the polarity based on a change in current detected by a sensor.

Disclosure of the invention

Problems to be solved by the invention

[0003] In the capacity control operation of the compressor of the air conditioner, the compressor drive motor is operated at a low rotation speed such as 1 Orps. It has been demanded. In that case, stable operation at extremely low speed of 5rps or 3rps is required. In addition, since the rotation direction of the compressor drive motor is one direction, there is no need to operate the compressor in the opposite direction.

[0004] However, in a blower or the like provided in an outdoor unit of an air conditioner, the rotation direction of the motor may be reversed due to the influence of outdoor wind or the like. After returning, it is necessary to rotate in the normal direction. Therefore, these motors are required to have stable control in a low-speed region during normal rotation or in low-speed regions on both sides including zero. [0005] The above-described conventional operation control device accelerates the motor up to a predetermined rotation speed when driving the electric motor. Therefore, since a torque for acceleration is required, the rotation control device detects the rotation speed in a relatively large current range. As a result, the detection error was small and stable control was possible.

[0006] However, this operation control device is intended to be applied to an electric motor that drives a compressor of an air conditioner that operates at a low speed, or is rotated at a low speed by natural wind despite the fact that it is driven. However, if it is applied to a motor that drives a blower of an outdoor unit of an air conditioner that rotates in the opposite direction, the winding current force with a small value at low speed rotation must be estimated because its rotation speed must be estimated. There was a problem that the accuracy was reduced and the control of the motor became unstable. In addition, when the motor rotating in the reverse direction is turned to the normal direction, it must pass through a low rotation speed range including 0, so that control in such an unstable state is not performed. It was inevitable.

[0007] Ming disclosure

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and an object of the present invention is to provide an operation control device for an electric motor capable of controlling the speed stably even at a low speed near zero.

[0008] Another object of the present invention is to provide a motor operation control device capable of stably turning in the forward direction even when the motor is rotating in the reverse direction.

Means for solving the problem

[0009] In order to achieve the above object, an operation control device for an electric motor according to claim 1 includes:

A power conversion unit that converts DC to AC and supplies the AC to the motor;

Current detection means for detecting a current flowing through a winding of the motor;

A rotor speed estimating means for estimating the number of revolutions of the motor based on a torque component and an exciting component of a voltage command value supplied to the motor and a current detected by the current detecting means; and a torque component, an exciting component and a rotor speed of the voltage command value. Waveform generation means for generating a drive waveform signal for driving the power conversion unit based on the rotation speed of the motor estimated by the estimation calculation means;

When the rotation speed of the motor estimated by the rotor speed Excitation correction control means for increasing the excitation component of the pressure command value,

It is provided with.

Brief Description of Drawings

FIG. 1 is a circuit diagram partially showing a configuration of a first embodiment of the present invention by blocks.

FIG. 2 shows the state of the target value of the excitation component current in relation to the estimated rotation speed of the motor and the target value of the torque component current in order to explain the operation of the first embodiment shown in FIG. Time chart.

FIG. 3 is a circuit diagram partially showing a configuration of a second embodiment of the present invention by blocks.

FIG. 4 is a circuit diagram partially showing the configuration of a third embodiment of the present invention by blocks.

FIG. 5 is a graph showing the state of the target value of the exciting component current in relation to the estimated rotational speed of the motor and the target value of the torque component current in order to explain a modification of each embodiment of the present invention. Sim chart.

BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, the present invention will be described in detail based on preferred embodiments shown in the drawings.

FIG. 1 is a circuit diagram partially showing the configuration of the first embodiment of the present invention by blocks. In FIG. 1, a smoothing capacitor 2 and a power converter 3 are connected in parallel between the positive and negative output terminals of the DC power supply 1. The power converter 3 is composed of six switching elements in which a reflux diode is connected in anti-parallel and connected in a three-phase bridge, and is an interconnection point between the positive switching element and the negative switching element, that is, The phase winding of the motor 4 is connected to the output terminal of the three-phase AC voltage.

[0012] A resistor 6 is connected between the negative side of DC power supply unit 1 and the negative side arm for three phases of power conversion unit 3, and a DC voltage detection unit 7 is connected in parallel with smoothing capacitor 2. Connected, and controls the switching elements of the power conversion unit 3 to be turned on and off based on the current detection value generated as a voltage at the resistor 6 and the DC voltage detection value detected by the DC voltage detection unit 7. The motor control unit 101 is provided.

Next, a detailed configuration of the motor control unit 101 will be described. The motor control unit 101 is provided with a target rotation speed co rel ^ from the outside, and also adds the respective detection values of the voltage generated in the resistor 6 and the voltage detected by the DC voltage detection unit 7. Of these, The detected value of the voltage generated at each of the resistors 6 is applied to the current detector 8. The current detection unit 8 converts the torque component current Iq and the excitation component current Id converted into coordinates on the rotor shaft based on the detected voltage value and the estimated rotor position est of the electric motor described later. It is an operation. A rotor speed estimation calculation unit 9 is connected to the current detection unit 8.

[0014] The rotor speed estimation calculation unit 9 includes a torque component current Iq and an excitation component current Id, a voltage detected by the DC voltage detection unit 7, a d-axis component Vd and a q-axis component Vq of a voltage command value described later. And the estimated rotational speed ω est of the rotor is calculated based on! The estimated rotation speed ω est of the rotor speed estimation calculation unit 9 is applied to the integration unit 10, the subtractor 21, and the excitation correction control unit 16. The integrator 10 integrates the estimated rotation speed w est and outputs it as the estimated rotor position 位置 est of the electric motor. The subtractor 21 subtracts the estimated rotational speed ω est from the target rotational speed core and adds the same to the PI control unit 11. The excitation correction control unit 16 outputs a correction value Idre! 2 of the excitation component of the voltage command value when the estimated rotation speed ω est of the motor estimated by the rotor speed estimation calculation unit 9 is within a predetermined value or less. .

The PI control unit 11 outputs the target value Iqr _e of the torque component current by proportionally and integrating the output of the subtractor 21, that is, the difference between the target rotation speed co ref and the estimated rotation speed co est. It is. The target value Iqref of the torque component current output from the PI control unit 11 is calculated by the calculation unit 12 and the subtractor 22. The calculation unit 12 converts the target value Iqre of the torque component current into the target value Idrefl of the excitation component current, and the subtractor 22 subtracts the torque component current Iq from the target value Iqre of the torque component current. Things. The output of the subtracter 22, that is, the difference between the target value Iqref of the torque component current and the torque component current Iq is added to the PI control unit 13, where the proportional and integral operation is performed to calculate the q-axis component of the voltage command value. Vq is output

[0016] The target value Idrefl of the excitation component current output from the calculation unit 12 is added to the adder 23, where it is added to the correction value Idref2 of the excitation component of the voltage command value, and the result is added to the excitation component current. The flow target value Idref is supplied to the subtractor 24. The subtractor 24 subtracts the exciting component current Id from the target value Idre of the exciting component current, and outputs the result to the PI control unit 14. The PI control unit 14 outputs the q-axis component Vq of the voltage command value by calculating the output of the subtractor 24, that is, the difference between the target value Idref of the excitation component current and the excitation component current Id in proportion and integration. It is.

The q-axis component Vq of the voltage command value output from the PI control unit 13 and the d-axis component Vd of the voltage command value output from the PI control unit 14 are added to the rotor speed estimation calculation unit 9 described above. Further, it is also applied to the waveform synthesizing unit 15. The waveform synthesizing unit 15 determines the driving voltages Vu, Vv on the stator shaft of the motor 4 based on the q-axis component Vq and the d-axis component Vd of the voltage command value, the voltage signal of the DC voltage detecting unit 7 and the estimated rotor position estest. , Vw, and further generates a drive waveform signal for driving the switching element of the power conversion unit 3 in accordance with the drive voltage.

The operation of the first embodiment configured as described above will be described below. The voltage supplied from the DC power supply 1 is smoothed by the smoothing capacitor 2 and supplied to the power converter 3. The power conversion unit 3 is driven by the motor control unit 101, converts DC into three-phase AC, and supplies the three-phase AC to the electric motor 4.

At this time, the voltage supplied to power conversion unit 3 is detected by DC voltage detection unit 7, and the winding current of motor 4 is detected by current detection unit 8 via resistor 6. The current detector 8 converts the currents of the three phases into a torque component current Iq and an excitation component current Id represented by coordinates on the rotor axis according to the estimated rotor position est and outputs the converted current.

At this time, in the motor control unit 101, the target rotation speed co ref and the estimated rotation speed w est are added to the subtractor 21, and the difference is proportionally and integratedly calculated by the PI control unit 11 to obtain the torque component current. Is output as the target value of Iqref. The target value Iqref of the torque component current is input to the calculation unit 12, where a predetermined calculation is performed, and the target value Iqref is converted into the target value Idrefl of the excitation component current. Also, the excitation correction control unit 16 outputs a correction value Idref2 of the excitation component current when the estimated rotational speed ω est of the electric motor estimated by the rotor speed estimation calculation unit 9 is equal to or less than a predetermined value. The target value Idrefl of the excitation component current and its correction value Idre! 2 are added by the adder 23 and output as the target value Idref of the excitation component current.

Next, the difference between the target value Iqref of the torque component current and the torque component current Iq is calculated by the subtractor 22, and this difference is proportionally and integrated calculated by the PI control unit 13 to calculate the q-axis component of the voltage command value. Output as minute Vq. Further, a subtractor 24 calculates a difference between the target value Idref of the exciting component current and the exciting component current Id, and this difference is proportionally and integratedly calculated by the PI control unit 14. Output as d-axis component Vd of voltage command value. Then, the q-axis component Vq and the d-axis component Vd are added to the rotor speed estimation calculation section 9 and the waveform synthesis section 15. Further, the estimated rotation speed w est is integrated by the integration unit 10, output as the rotor estimated position est est, and applied to the current detection unit 8 and the waveform synthesis unit 15.

[0022] In the waveform synthesizing unit 15, the driving voltages Vu, VV, Vw on the stator shaft of the electric motor 4 are based on the q-axis component Vq, the d-axis component Vd, the rotor estimated position 及び est, and the DC voltage Vdc of the voltage command value. Then, a driving waveform signal for driving the switching element of the power conversion unit 3 is generated in accordance with the driving voltage.

Here, the above-described rotor speed estimation calculation unit 9 calculates the estimated rotation speed ω est of the motor from the winding current of the motor by the circuit equation of the motor, and the integration unit 10 integrates the estimated rotation speed ω est. By doing so, the estimated rotor position estest of the motor is output. In this case, the circuit equation of the motor is represented by the following equation.

Vd = (R + PLd) X Id-ω X Lq X Iq… hi)

Vq = ω X LdX Id + (R + PLq) X Iq + ω X

However,

Ρ: Differential operator

R: Winding resistance

Ld: d-axis inductance

Lq: q-axis inductance

ω: rotation speed

Φ: induced voltage coefficient

It is.

According to the circuit equation of the electric motor, when the rotation speed ω is small, the values of the second term on the right side of equation (1) and the first and third terms on the right side of equation (2) become small. In addition, the winding resistance R of the motor is a loss of the motor. Therefore, the winding resistance R is designed to be as small as possible to increase the motor efficiency. Also, the excitation component current Id does not directly contribute to the driving of the motor, so that it is controlled to a small value in order to improve efficiency. On the other hand, the torque component current Iq is a current that generates the torque of the motor, and has a small value when the rotation speed of the motor is low, since the load on the motor is small. The error of the current detection unit 8 includes a component proportional to the detected value (such as a gain error of an amplifier circuit) and a fixed component (such as an offset voltage) that does not depend on the detected value. Because of this, the relative error increases. Since the motor control unit 101 also estimates the rotational speed for the current value force, the error in the rotational speed increases as the error in the current value increases. Therefore, it was difficult to stably rotate the electric motor at a low rotation speed.

That is, when the electric motor is started, as described above, the motor is accelerated to a predetermined rotational speed, so that a torque for acceleration is required. At this time, the estimated error is small because the current is relatively large. It was difficult to rotate the motor stably when the rotation speed was less than lOrps, such as the electric motor that drives the compressor of the harmony machine. Also, in the case of an outdoor fan of an air conditioner, it is necessary to perform low-speed control in a predetermined range including zero rotation when the wind is rotated reversely by the outdoor wind and returned to normal rotation. In addition, it was difficult to control the electric motor stably, which made it difficult.

In this embodiment, the excitation correction control unit 16 outputs the correction value Idref2 of the excitation component current and outputs the voltage when the rotation speed co est of the motor estimated by the rotor speed estimation calculation unit 9 is within a predetermined value or less. By increasing the excitation component Vd of the command value, it is possible to control stably at both forward and reverse low-speed rotations including zero rotation.

FIG. 2 shows that the state of the target value Idref of the excitation component current is related to the estimated rotational speed ω est of the motor of the rotor speed estimation calculation unit 9 and the target value Iqref of the torque component current by the excitation correction control unit 16. It is a time chart represented. This is because, if the direction of rotation of the blower is reversed to the normal direction by turning in the opposite direction due to the effect of outdoor wind, the rotor speed estimation calculation unit 9 The excitation current is input to 16 and the excitation correction control unit 16 increases the excitation current by 1.5 A, for example, when a certain rotational speed in the reverse direction is reached (corresponding to the lower limit of a predetermined range of low speed, for example, -lOOrpm). Value Idref2 for increasing the excitation current when a certain number of rotations in the positive direction (for example, +80 rpm) is reached.

[0029] Thus, the rotation speed of the motor that is rotating in reverse is reduced, and the estimated rotation speed west is reduced, and the accuracy of the estimated rotation speed is reduced to reach a rotation speed at which control becomes unstable (for example, 60 rpm). Before, the eye of the excitation component current

Estimated rotational speed co est And the control can be prevented from becoming unstable.

[0030] Also, after the accuracy of the estimated rotational speed ω est is ensured and the rotational speed reaches a stably controllable rotational speed (corresponding to the upper limit of a low-speed predetermined range, for example, 80 rpm), the target value of the excitation component current is increased. Since Idrel ^ is reduced, efficient operation can be achieved by suppressing an increase in loss due to the excitation component current Id. However, since the motor that drives the compressor does not rotate in the reverse direction, the low speed region in the forward rotation direction (for example, 0 to 80 rpm) corresponds to the predetermined low speed range of the present invention.

The accuracy of the estimated rotation speed ω est, which is the output of the rotor speed estimation calculation unit 9, decreases because the rotation speed decreases during the forward rotation and the detection accuracy of the current relatively decreases. Therefore, when the rotational speed decreases, the accuracy gradually decreases, and eventually the control becomes unstable.

[0032] For this reason, stable control is possible by gradually increasing the target value 1 (1 1 電流) of the excitation component current. If the target value Idref ^ of the excitation component current is rapidly changed, the motor However, there is a problem that the control is likely to be unstable because the vector of the voltage applied to the device changes rapidly.

As shown in FIG. 2, in the present embodiment, when the motor during reverse rotation is rotated forward, when the rotation speed reaches a certain rotational speed in the reverse direction (for example, −100 rpm), the correction value Idre! It increases as the rotational speed increases from zero to a certain value (for example, 1.5 A), and conversely, when a certain rotational speed in the positive direction (for example, +60 rpm) is reached, the correction value Idre! 2 is rotated. Control is performed such that the number gradually decreases to zero as the number increases. Thereby, the electric motor can be controlled stably.

[0034] In general, increasing the exciting component current Id increases the loss in the motor, and decreasing the exciting component current Id increases the efficiency of the motor. In the present embodiment, when a certain number of rotations in the positive direction (for example, +60 rpm) is reached, the correction value Idre! 2 is gradually reduced to zero as the number of rotations increases. It can be controlled efficiently.

As a modification of the first embodiment described with reference to FIG. 1 and FIG. 2, when the target value Iqrel ^ of the torque component current is large, the excitation component current correction value of the excitation By correcting Id ref2 to be small, increase in loss due to excitation component current Id is suppressed. In addition, the motor can be stably controlled. That is, if the target value Iqrel ^ of the torque component current is large, the winding current of the motor also increases, so that the accuracy of the estimated rotational speed ωest can be secured without making the excitation component current Id so large.

As another modified example of the first embodiment described with reference to FIGS. 1 and 2, instead of changing the output of the excitation correction control unit 16 in accordance with the rotation speed, a predetermined rotation is performed. Even if the number is reached and the force is output as a function of the elapsed time, the same effect as described above can be obtained if the change in the rotation speed of the motor does not change significantly.

FIG. 3 is a circuit diagram partially showing the configuration of the second embodiment of the present invention by blocks. In the figure, the same elements as those in FIG. 1 showing the first embodiment are denoted by the same reference numerals, and description thereof will be omitted. In this embodiment, the excitation correction control unit 16 and the adder 23 in FIG. 1 are removed, and instead, the output path of the rotor speed estimation calculation unit 9 has its estimated rotation speed co estl within a predetermined range (for example, (100 rpm-+60 rpm), the rotor speed estimation control unit 17 that estimates the current rotation speed from the rotation speed before the decrease and outputs the estimated rotation speed ω est2, and the estimated rotation speed co estl is a certain value or less. In the range, the estimated rotation speed ω est2 of the rotor speed estimation control unit 17 is selected instead of the estimated rotation speed ω estl of the rotor speed estimation calculation unit 9, and this is set as the current estimated rotation speed ω est, and the integration unit 10 and The difference from the first embodiment lies in the point that it is configured to be added to the subtractor 21, and the remaining configuration is the same as that of the first embodiment. Note that the rotor speed estimation control unit 17 and the speed selection unit 18 correspond to the rotation speed substitution estimation calculation means of the present invention.

[0038] Next, the operation of the second embodiment will be described below, particularly focusing on parts different from the first embodiment shown in FIG. As described above, when operating at a rotational speed of lOrps or less, such as an electric motor for driving a compressor of an air conditioner, it was difficult to achieve stable control. Also, like an air conditioner outdoor unit blower, it is rotated in the reverse direction by the outdoor wind, and when returning the object to normal rotation, it is necessary to perform low-speed control within a predetermined range including zero rotation. However, also in this case, it was difficult to stably control the electric motor.

In the present embodiment, when the inertia of the load connected to the electric motor, such as a blower of an air conditioner, is large V, the estimated rotational speed ω est in the low speed region where the error of the estimated rotational speed ω est is predicted to increase. Is determined based on the time change rate of the high-speed region before reaching the low-speed region. As shown in Fig. 2 above, the rotation speed of the motor during reverse rotation is gradually reduced to bring the number of rotations to zero, and then the motor is rotated forward to increase its speed. In this case, the rotor speed estimation control unit 17 calculates the estimated rotation speed co estl until the estimated rotation speed co estl of the electric motor during reverse rotation gradually decreases to a certain value (for example, −100 rpm) and its time change rate. , And calculates a rotation speed that changes in accordance with the passage of time thereafter, and outputs it as an estimated rotation speed cost2.

[0040] The speed selection unit 18 selects the estimated rotation speed ω estl of the rotor speed estimation calculation unit 9 until the estimated rotation speed co estl becomes a certain value in the negative direction (for example, −100 rpm). ω est, and the rotor speed estimating and controlling section 17 elapses after the estimated rotational speed co estl exceeds a certain value in the negative direction (for example, −100 rpm) until it reaches a certain value in the positive direction (for example, +80 rpm). The estimated rotation speed co est2 is selected and output as the estimated rotation speed ω est, and after the estimated rotation speed co estl becomes a certain value in the positive direction (for example, +80 rpm), the rotor speed estimation calculation unit 9 The estimated rotational speed ω estl is selected and output as the estimated rotational speed ω est.

[0041] As a result, in the low-speed range where the rotation speed of the motor rotating in the reverse direction is reduced, the accuracy of the estimated rotation speed is reduced, and the control becomes unstable, the estimated rotation speed ω est is further improved. By switching to ω est2, the accuracy of the estimated rotational speed w est can be ensured, and the control can be prevented from becoming unstable. After the accuracy of the estimated rotational speed co estl calculated from the current is secured and reaches a rotational speed that can be controlled stably (for example, +80 rpm), the estimated rotational speed is switched to the estimated rotational speed ω estl by the rotor speed estimation calculation unit 9. Therefore, the motor can be controlled stably.

FIG. 4 is a circuit diagram partially showing the configuration of the third embodiment of the present invention by blocks. In the drawing, the same elements as those in FIG. 3 showing the second embodiment are denoted by the same reference numerals, and description thereof will be omitted. In this embodiment, when the error of the estimated rotation speed co estl by the rotor speed estimation calculation unit 9 is large between the PI control unit 11 and the subtractor 22, that is, the speed selection unit 18 When the estimated rotation speed ω est2 is selected, the target value Iqre of the current torque component current outputted from the PI control unit 11 and estimated from the previous target value Iqrefl of the torque component current, and the torque current component is estimated. When the speed selection unit 18 selects the output of the rotor speed estimation control unit 17 and the PI control unit 1 Instead of the target value Iqrefl of the torque component current of 1, the target value Iqref2 of the torque component current of the Iqre determination unit 19 is selected and added to the subtractor 22 as the current target value Iqref of the torque component current. The configuration of the second embodiment differs from that of the second embodiment in that the configuration is different from that of the second embodiment. It should be noted that the above-described Iqre determination section 19 and Iqref selection section 20 constitute a torque substitution estimation calculating means of the present invention.

Next, the operation of the third embodiment will be described below, particularly focusing on parts that differ from the second embodiment shown in FIG. Here, the Iqre determination unit 19 monitors the current target value Iqrefl of the torque component current output from the PI control unit 11 and estimates the subsequent target value Iqre of the torque component current based on the result. Outputs the torque current component setting Iqre! 2. If the speed selection unit 18 selects the estimated rotation speed ω est2 of the rotor speed estimation control unit 17 and outputs it as the estimated rotation speed ω est, the PI control unit 11 outputs Instead of the target value Iqrefl of the current torque component current, the set value Iqre! 2 of the torque component current of the Iqre determination unit 19 is selected and added to the subtractor 22 as the current target value Iqref of the torque component current. Further, when the speed selection unit 18 selects the estimated rotation speed ω estl of the rotor speed estimation calculation unit 9, the selection of the torque current component set value Iqref2 of the Iqre determination unit 19 is stopped, and the PI control unit 11 The target value Iqrefl of the torque current component is selected and output as the target value Iqref of the torque current component.

Iqref shown in FIG. 2 is a set value of a torque component current output by Iqre determination unit 19 in accordance with a state of selection of the estimated rotation speed by speed selection unit 18, and Iqref2 is a target value of the torque current component. This shows the state used as I qref.

[0045] This makes it possible to stabilize the target value Iqrei 電流 of the torque current component and suppress fluctuations in the generated torque, thereby increasing the accuracy when the estimated rotation speed ω est2 is used as the estimated rotation speed ω est and stabilizing the motor. And can be controlled. Further, since the torque generation current can be set as large as possible until the rotation direction of the motor becomes the normal direction, the rotation speed of the motor can reach the target rotation speed ωref in a short time.

As a modified example of the second embodiment described with reference to FIGS. 3 and 2, instead of the speed selection unit 18, the estimated rotation speed co estl from the rotor speed estimation calculation unit 9 and the rotor speed Even if the estimated rotational speed ω est2 from the estimation control unit 17 is synthesized and estimated, Operation control can be performed. As a method of synthesizing the estimated rotation speeds ω estl and ω est2, a method of synthesizing them at a fixed ratio, or changing the synthesis ratio depending on the rotation speed, and increasing the ratio of the estimated rotation speed co est2 at lower speed You may do it. Further, the rotor speed estimation control unit 17 may also calculate the speed force before lowering the upper limit value and the lower limit value, and limit or correct the output of the rotor speed estimation calculation unit 9.

On the other hand, the configuration of FIG. 3 shown as the second embodiment, that is, the configuration having the rotor speed estimation control unit 17 and the speed selection unit 18 is different from the excitation correction configuring the first embodiment. By adding the control unit 16 and simultaneously performing the control for increasing the exciting current, the control of the motor can be further stabilized, and the control can be stably performed even at around Orpm.

[0048] Fig. 5 is a time chart showing this relationship. In the case where the speed of the rotating motor is changed to the normal direction to increase the speed, the motor falls in the low speed range—the estimated rotation speed between lOOrpm and + 60rpm. more precisely the high number omega est, switched to the estimated rotational speed omega est2, in conjunction with the changeover made to have a target value Idr _e temporal change of the exciting component current is increased by the correction value Idref2, rotates in the direction of the normal When the vehicle exits the low-speed range, the correction value Idref2 is set to zero with a temporal change, and control is performed to return to the original target value Idref of the excitation component current. As a result, stable control can be achieved even near Or pm.

Similarly to this, the configuration of FIG. 4 shown as the third embodiment, namely, the rotor speed estimation control unit 17 and the speed selection unit 18, the Iqre determination unit 19 and the Iqrefig selection unit 20 By adding the excitation correction control unit 16 that constitutes the first embodiment to the configuration equipped with the above, the control of increasing the excitation current is performed at the same time, so that the control of the motor is more stable, and even around Orpm And can be controlled.

In each of the above embodiments, a resistor is connected in series with each negative arm of the power converter 3 to detect the current flowing through the winding of the electric motor. By connecting a resistor to one current path between the power converter 3 and the power converter 3, and measuring the voltage at both ends when each switching element of the power converter 3 is turned on, the current flowing through the winding of the motor is measured. Can be detected.

Industrial applicability

According to the present invention, it is possible to control the speed stably even at a low-speed rotation close to zero. Wear. In addition, even when the motor is rotating in the reverse direction, the direction can be stably changed in the forward direction.

Claims

The scope of the claims

[1] a power conversion unit that converts a direct current into an alternating current and supplies it to an electric motor;

Current detection means for detecting a current flowing through a winding of the electric motor,

Rotor speed estimation calculating means for estimating the number of revolutions of the motor based on the torque component and the excitation component of the voltage command value supplied to the motor and the current detected by the current detecting means;

Waveform generation means for generating a drive waveform signal for driving the power conversion unit based on the torque component and the excitation component of the voltage command value and the number of revolutions of the motor estimated by the rotor speed estimation calculation means. When,

Excitation correction control means for increasing the excitation component of the voltage command value within a range where the rotation speed of the motor estimated by the rotor speed estimation calculation means is equal to or less than a predetermined value;

The operation control device of the electric motor provided with.

[2] In the operation control device for an electric motor according to claim 1,

Control means for reversing the rotation direction of the motor, wherein the excitation correction control means increases the excitation component of the voltage command value when the rotation speed of the motor exceeds a predetermined value after the rotation direction of the motor is reversed. An operation control device for an electric motor that stops control.

[3] a power converter for converting a direct current into an alternating current and supplying it to the electric motor;

When the rotation speed of the electric motor estimated by the rotor speed estimation calculating means is within a predetermined range of low speed, the rotation speed is estimated and output from the rotation speed before the rotation speed falls within the predetermined range. Alternative estimation calculating means,

Waveform generation means for generating a drive signal for driving the power conversion unit based on the torque component and the excitation component of the voltage command value and the rotation speed of the motor estimated by the rotor speed estimation means or the rotation speed substitution estimation means. When,

The operation control device of the electric motor provided with.

[4] In the operation control device for an electric motor according to claim 3,

The waveform generating means is capable of outputting an output for decelerating the motor and reversing the rotation direction when the motor is rotating in the reverse direction, and for estimating the rotor speed when the motor is rotating in the opposite direction to the predetermined rotation direction. When the rotation speed of the motor estimated by the calculation means is out of the predetermined range, the rotation speed of the motor estimated by the rotor speed estimation calculation means is supplied to the waveform generation means, and is estimated by the rotor speed estimation calculation means. When the rotation speed of the motor falls within the predetermined range, the rotation speed of the motor estimated by the rotation speed substitution estimating unit is supplied to the waveform generation unit, and the rotation of the motor after the rotation direction of the motor is reversed. Speed selection means for selecting the number of rotations of the motor estimated by the rotor speed estimation means to be supplied to the waveform generation means when the number exceeds the predetermined range. The control device.

[5] In the operation control device for an electric motor according to claim 3,

Torque calculation means for generating a torque component and an excitation component of the voltage command value based on a deviation between the set speed command value and an estimated value of the rotation speed of the motor; and a torque component of the voltage command value for the motor. A torque alternative estimation calculating means for estimating and outputting from the torque component before the estimated value of the rotation speed falls within the predetermined range, and the speed selection means selecting a rotation speed output by the motor speed estimation calculation means. Means for selecting the torque component estimated by the torque alternative estimating means.

[6] In the operation control device for an electric motor according to claim 4,