KR100313970B1 - Control device of permanent magnet synchronous motor - Google Patents

Abstract

In case of PWM control of permanent magnet synchronous motor, voltage short circuit of arm short circuit prevention time is prevented.

The coordinate conversion means 22 inputs the output current 6a of the inverter (not shown) and the angular data 8a of the motor (not shown) to input the torque current threshold value 22b and the reactive (excited) current feedback value. Output 22a. The torque current feedback value 22b is controlled in accordance with the torque current command value iq * and the reactive current feedback value 22a is controlled in accordance with the reactive current command value id *.

At this time, the reactive current command value id * is set to a predetermined value Kid, the output current of the inverter is set to a value other than 0, and the phase voltage is stored at a stable potential.

Description

Control device of permanent magnet synchronous motor

The present invention relates to a device for controlling pulse width modulation (PWM) according to a torque current command value and a reactive current command value.

1, 2, 4 and 13 show a control device of a conventional permanent magnet synchronous motor in which some circuits have been added, for example, as described in Japanese Patent Application Laid-Open No. 4-69066. 2 is a block diagram of a hardware portion of the current control operation means, FIG. 4 is an operation explanatory diagram, FIG. 13 is a block diagram of a software portion of the current control operation means, and like reference numerals denote like parts. do.

Since the angle is also used in the present invention except for a part, details will be described later, but only the main points will be described.

The alternating current of the three-phase alternating current power source 1 is converted into direct current in the converter 2 and input to the inverter 4. The inverter 4 switches the phase and the lower switching elements 4A and 4B on and off in accordance with the PWM control signals 12a and 12b, converts direct current into three-phase alternating current, and provides a permanent magnet synchronous motor 7 ).

The output current 6a of the inverter 4 and the angular data 8a of the motor 7 are returned to the current control operation means 9, and the output current 6a is the reactive current feedback value 22a and the torque current feedback value ( It is separated into two components of 22b).

The reactive current feedback value 22a is controlled in contrast with the reactive current command value id * (= 0) set by the reactive current command control means 23c, and the torque current feedback value 22b is fed to the torque current command calculation means 24. It is controlled in contrast to the calculated torque journal command value iq * and sent to the output circuit 12 as the voltage command value 9a.

On the other hand, according to the phase voltage detected by the phase voltage detection circuit 5, the short-circuit prevention time Td which turns off phase and hearth switching elements 4A and 4b simultaneously is set. The operating waveforms of each part are shown in FIG.

In the control apparatus of the conventional permanent magnet synchronous motor as described above, since the short-circuit prevention time Td is a period in which the upper and lower switching elements 4A and 4B are turned off at the same time, the current iu flowing in the motor 7 is near 0. As shown in Fig. 4E, the phase voltage Vu is not established and becomes an unstable potential. The state of the output signal of the phase voltage detection circuit 5 when this phenomenon occurs is shown in Fig. 4F.

For this reason, the influence of voltage distortion appears on the motor 7, and there is a problem that an imbalance occurs in the rotation of the motor 7.

The present invention has been made to solve the above problems, and an object thereof is to provide a control device for a permanent magnet type synchronous motor which can smoothly rotate an electric motor without distortion of a current waveform flowing in the electric motor.

The control device of the permanent magnet synchronous motor according to the first invention of the present invention is to control the reactive current command value when the motor current is controlled by separating the torque current and the reactive current.

Further, the control device of the permanent magnet synchronous motor according to the second aspect of the invention allows the reactive current command value to flow in the direction of strengthening the field of the conductor in the first invention.

The control device for permanent magnet synchronous motors according to the third aspect of the invention sets the reactive current command value to the second predetermined value when the torque current feedback value is less than or equal to the first predetermined value according to the first to third inventions. When the value is larger than 1, the reactive current command value is set to zero.

BRIEF DESCRIPTION OF THE DRAWINGS The whole structure figure which shows Embodiment 1 of this invention and the control apparatus of the conventional permanent magnet synchronous motor.

2 is a block diagram of a hardware portion of the current control operation means of FIG.

Fig. 3 is a block diagram of a software portion of the current control computing means showing Embodiment 1 of the present invention.

Fig. 4 is an operation explanatory diagram showing a control device of Embodiment 1 of the present invention and a conventional permanent magnet synchronous motor.

Fig. 5 is a block diagram of a software portion of the current control computing means showing Embodiment 2 of the present invention.

Fig. 6 is a flowchart of reactive current command control operation which shows Embodiment 2 of this invention.

Fig. 7 is a block diagram of the software portion of the current control computing means for displaying Embodiment 3 of the present invention.

Fig. 8 is a flowchart of reactive current command control operation which shows Embodiment 3 of this invention.

Fig. 9 is a flowchart of the reactive current command control operation in accordance with the fourth embodiment of the present invention.

Fig. 10 is a curve diagram of torque current feedback value and reactive current command value, showing Embodiment 4 of the present invention;

Fig. 11 is a flowchart of reactive current command control operation which shows Embodiment 5 of this invention.

Fig. 12 is a torque current limit value and a reactive current command value curve showing Embodiment 5 of the present invention;

Fig. 13 is a block diagram of the software portion of the current control operation means of the control apparatus of the conventional permanent magnet synchronous motor.

<Description of the symbols for the main parts of the drawings>

4. Inverter, 4A. Phase Switching Element,

4B. Hearth switching element, 5. Phase voltage detection circuit,

6. Current detector, 6a. Inverter output current,

7. permanent magnet synchronous motor, 8. encoder,

8a. Angular data, 9. current control computing means,

10. Short circuit prevention time correction means, 11. Short circuit prevention time preparation means,

12. output means, 22. coordinate changing means,

22a. Reactive current return value, 22b.torque current return value,

23,23A, 23B. Reactive current command control means, 24. torque current command calculation means,

28. reactive current control calculation means, 29. torque current control calculation means,

id *. Reactive current setpoint, iq *. Torque current command value,

Iu. Inverter output current.

Embodiment 1

1 to 4 show an embodiment of the first, second and third inventions of the present invention, FIG. 1 is an overall configuration diagram, FIG. 2 is a block diagram of a hardware portion of the current control operation means, 3 is a block diagram of a software portion, FIG. 4 is an operation diagram, and like reference numerals denote like parts. (The same as the embodiment below)

In Fig. 1, 1 is a three-phase AC power supply, 2 is a converter for converting alternating current of the three-phase AC power source 1 composed of a transistor and a diode, 3 is a flat capacitor connected to the output side of the converter 2, 4 is a flat capacitor. An inverter for converting to three-phase alternating current connected to (3), comprising: a phase switching element 4A and a low switching element 4B connected in series with one phase, and a flywheel diode 4a connected in parallel to them; It consists of 4b.

5 is a phase voltage detection circuit composed of current control resistors 5A, 5B and photocoupler 5C and detects a phase voltage Vu, 6 is a current detector for detecting an output current 6a of the inverter 4, 7 is a permanent magnet synchronous motor connected to the output side of the inverter 4, 8 is the angular data 8a of the electric motor 7, that is, an encoder for outputting speed, 9 is a current 6a and an angular data 8a. It is an electric current control calculation means which inputs and calculates and outputs the voltage command value 9a.

10 denotes a short circuit prevention by inputting the phase voltage Vu detected by the phase voltage detection circuit 5 and correcting and outputting the comfort prevention time Td for simultaneously turning off the phase and the lower switching elements 4A and 4B according to the input signal. The time correction means, 11 is a short circuit prevention time generating means for setting an optimum short circuit prevention time Td according to the output of the short circuit prevention time correction means 10, 12 is a current control operation means 9 and a short circuit prevention time creating means 11 ) Is an output circuit for outputting PWM (pulse width modulation) control signals 12a and 12b to the upper and lower switching elements 4A and 4B.

2, 15 is a CPU, 16 is a ROM in which a current control operation program is stored, 17 is a RAM, 18 is an analog switch to which the output current 6a of the inverter 4 is input, and 19 is A connected to the analog switch 18. The / D converter 20 is an encoder gate day to which angle data 8a is input, and these elements 15 to 17, 19, 20 and output circuit 12 are connected to each other.

3 to 21 are sine and cosine function calculating means for calculating the sine function and the cosine function from the angle data 8a, and 22 is the output current 6a of the inverter 4 and the sine and cosine function calculating means 21. Coordinate converting means for inputting an output signal to convert three-phase alternating current into two-axis direct current and outputting reactive current feedback value 22a and torque current feedback value 22b. 23 denotes a predetermined value Kid as the reactive current command value iq *. The reactive current command control means 24 to be given is a torque current command calculation means for calculating the torque current command value id * from the speed command value and the actual speed.

25 and 26 are adding means, 27 is inputting reactive current feedback value 22a and torque current feedback value 22b, and interference voltage compensating means for compensating for errors caused by their interaction, 28 is adding means ( Reactive current control calculation means connected to 25, 29 are torque current control calculation means 30, 31 for adding means, 32 for adding means 30, 31 and sine connected to the adding means 26. -Coordinate conversion means connected to the cosine function calculating means 21 to convert the biaxial direct current into three-phase alternating current and output the voltage command value 9a.

Next, the operation of the present embodiment will be described.

In addition, since all three phases of the inverter 4 have the same structure, only one phase is demonstrated. The alternating current of the three-phase alternating current power supply 1 is converted into direct current in the converter 2, smoothed in the smoothing capacitor 3, and input to the inverter 4. The inverter 4 turns on and off the phase and bottom switching elements 4A and 4B according to the PWM control signals 12a and 12b input from the output circuit 12, so that the direct current is converted into three-phase alternating current. It converts and supplies it to a permanent magnet synchronous motor 7 to drive it.

The output current 6a detected by the current detector 6 and the angular data 8a detected by the encoder 8 are fed back to the current control calculating means 9. The output current 6a is input to the coordinate converting means 22, and the angular data 8a is calculated through the sine and cosine function calculating means 21, and the sine and cosine functions are calculated. Input to the output, the reactive current feedback value 22a and the torque current feedback value 22b are output.

The reactive current command value id * = predetermined value Kid supplied from the reactive current command control means 23 and the reactive current feedback value 22a are matched by the adder 25, and the deviation is compared to the reactive current control calculation means 28. It is input so that the deviation is controlled to be zero. The torque current command value iq * calculated by the torque current command calculation means 24 and the torque current feedback value 22b are compared with the addition means 26, and the deviation is inputted to the torque current control calculation means 29. The deviation is controlled to be zero.

The output of the reactive current control calculating means 28 and the output of the torque current control calculating means 29 and the output of the interference voltage compensating means 27 are collated by the adding means 30 and 31, respectively, and then the coordinate converting means. Inputted to (32), it is converted into three-phase alternating current and becomes voltage command value 9a.

On the other hand, the phase voltage detection circuit 5 detects the phase voltage Vu of the phase V through the photocoupler 5c, and according to the input signal, the short-circuit prevention time correction means 10 includes the upper and lower switch elements 4A, The short-circuit prevention time Td (FIG. 4) which simultaneously turns off (4B) is corrected. And the short circuit prevention time preparation means 11 sets the optimal short circuit prevention time signal 11a.

The output circuit 12 inputs the voltage command value 9a calculated by the current control operation means 9 and the short-circuit prevention time 11a set by the short-circuit prevention time generating means 11, and generates a PWM control signal 12a, ( 12b) is output to control on and off of the upper and lower switching elements 4A and 4B.

Next, the operation of this embodiment will be described with reference to FIG. 4 including the conventional apparatus. 4A shows the output phase voltage of the abnormal inverter, FIG. 4B shows that the phase switching element 4A is turned on, the lower switching element 4B is turned off, and the output current Iu flows in the direction shown. The operation signal of the phase switching element when the phase switching element 4A is turned off in the state and shifts to the short-circuit prevention time Td. In the flowing state, the phase switching element 4A is turned off and the half-lay wheel diode 4b is turned off through the induction current by the electric motor 7, so that the switching element 4B is turned off to the short-circuit prevention time Td. The operation signal of the switching device in case of shift is displayed.

4 (d) shows the phase voltage Vu at this time.

Since the short-circuit prevention time Td is a period in which the phase switching devices 4A and 4B are turned off at the same time, in the conventional apparatus, the potential of the phase voltage Vu is not established when the current flowing in the electric motor 7 is near 0, It becomes unstable value as shown to FIG. 4 (C). For this reason, when the on / off detection value of the upper and lower switching elements 4A and 4B is set to several 10 V, the short circuit prevention time Td at which the unstable voltage is generated, both the elements 4A and 4B. Is turned on and off, and the output of the phase voltage detection circuit 5 is as shown in Fig. 4 (f).

In this embodiment, since a predetermined value Kid is assigned to the reactive current command value id *, for example, even if the torque current command value iq * becomes 0, the reactive current does not become near the output current Iu by that much. Therefore, the potential of the phase voltage Vu is also established, which becomes the waveform shown in FIG. 4 (d), and the output of the phase voltage detection circuit 5 becomes the waveform shown in FIG. 4 (a), and provides a stable short-circuit prevention time Td. It is possible to obtain.

The magnetic flux on the magnetic field side of the electric motor 7 at this time is a combination of a permanent magnet and an excitation current component, that is, a reactive current component. In this case, the latter is sufficiently small with respect to the former, so the electric field becomes a strong field because the magnetic flux due to the reactive current component is superimposed on the magnetic flux by the permanent magnet. In the case where the motor 7 is controlled at the rotational speed, the torque current is further increased, but its effect is small.

That is, when the motor 7 is being controlled for rotation speed, the torque current component also increases automatically by making the current direction of the reactive current component to be injected into the strong field side, so that the absolute value of the reactive current component to be injected can be set small.

That is, the basic relational expression of the motor,

N = E / K∮ = IR / K∮

Is displayed. N is the rotational speed, E is the voltage, K is the constant, 자 is the magnetic flux, I is the current, and R is the winding resistance.

In the common sense, when the rotational speed N is constant, increasing the magnetic flux 하면 increases the current I.

Embodiment 2

5 and 6 show embodiments of the fourth and fifth inventions of the present invention, FIG. 5 is a block diagram of a software portion of the current control operation means, and FIG. 6 is a reactive current command control operation flowchart. .

1, 2, and 4 are also common to the second embodiment.

In Fig. 5, 23A is a reactive current command control means for controlling the reactive current command value id * by inputting the torque current feedback value 22b.

Next, the operation of this embodiment will be described with reference to FIG. 6. In step S1, it is determined whether the torque current limiting value 22b is larger than the first predetermined value Kiq, and if it is large, the reactive current command value iq * is set to zero in step S2. If the first predetermined value Kiq or less, the reactive current command value id * is set to the second predetermined value Kid in step S3.

In this way, the reactive current is injected only when the torque current feedback value 22b is close to zero, i.e., below the first predetermined value Kiq, so that the output current Iu is not close to zero.

Therefore, it is possible to prevent the temperature rise of the electric motor 7 and to improve the operating efficiency of the electric motor 7 without passing an extra reactive current unless necessary. In Embodiment 2, after the output current 6a is separated into the torque current component and the reactive current component, the injection of the reactive current is judged by the torque current feedback value 22b, but the output current 6a before the separation is determined. The same effect can be obtained even by detecting near zero current and judging injection of reactive current components by itself. (Omitted)

Embodiment 3

7 and 8 show an embodiment of the sixth invention of the present invention, FIG. 7 is a block diagram of the software portion of the current control operation means, and FIG. 8 is a flowchart of the reactive current command control operation.

1, 2, and 4 are also common to the third embodiment. In Fig. 7, 23B is a reactive current command control means for controlling the reactive current command value id * by inputting the torque current command value iq *.

Next, the operation of this embodiment will be described with reference to FIG. 8.

In step S5, it is determined whether the torque current command value iq * is larger than the third predetermined value Kiq. If the torque current command value iq * is larger, the reactive current command value id * is set to 0 in step S2. If the value is equal to or less than the third predetermined value Kiq, the reactive current command value id * is set to the second predetermined value in step S3.

In the second embodiment, the actual motor current is monitored so that reactive current flows when it approaches zero. However, the torque current command value iq * is monitored here so that reactive current flows when it approaches zero. Injecting reactive current in anticipation of being zero.

In this case, since the injection is judged by the command value instead of the current value, for example, as described in the second embodiment, when the injection of the reactive current is judged by the motor current value, the motor current value becomes less than the predetermined value and the reactive current is determined. When the synthesized current flows after injection, the operation becomes larger than the predetermined value and the injection is stopped.

That is, the presence or absence of injection repeatedly occurs, so that a so-called oscillation state is generated, but the oscillation can be prevented by judging the injection by the command value.

Embodiment 4

9 and 10 show an embodiment of the seventh invention of the present invention. FIG. 9 is a flowchart of the reactive current command operation, and FIG. 10 is a torque current feedback value and a reactive current command value curve.

1, 2, 3, and 4 and 5 also share the fourth embodiment.

Next, operation | movement of this embodiment is demonstrated.

In step S1, it is determined whether the torque current feedback value 22b is larger than the first predetermined value Kiq, and if it is large, in step S11, it is determined whether the flag Fid is "1".

As described later in step S15, before the time T _{1 in} FIG. 10, the flag Fid is "0". Therefore, the flow advances to step S2 and the reactive current command value id * is set to 0, and the flag Fid is set to "0" in step S14. .

When the torque current feedback value 22b becomes equal to or less than the first predetermined value Kiq at time T ₁ , the progress flag Fid is set to "1" from step S1 to step S15.

In step S16, it is determined whether the reactive current command value id * is equal to or greater than the second predetermined value Kid. Since the second predetermined value Kid has not been reached yet, the reactive current command value id * increases at a predetermined inclination (primary delay) by adding the small value? Id * to each reactive pole in step S17 to the reactive current command value id *. As a result, the state is maintained when the reactive current command value id * reaches the second predetermined value Kid.

If the torque current feedback value 22b becomes larger than the first predetermined value Kiq at time T ₂ , the process proceeds to step S1? S11? S12 and determines whether the reactive current command value id * is equal to or less than zero. Since the second predetermined value Kid is still maintained, the reactive current command value id * is gradually decreased by a predetermined slope by subtracting the minute value? Id * from the reactive current command value id * for each operation cycle in step S13.

As a result, when reactive current command value id * becomes 0, it progresses from step S12 to S2, reactive current command value id * is set to 0, and flag Fid is set to "0" in step S14.

In addition, the above has described the case where the reactive current command value id * is controlled by monitoring the torque current feedback value 22b as shown in FIG. 5, but the reactive current command value id * is monitored by monitoring the torque current command value iq * as shown in FIG. It is also applicable to the control. It is also applicable to the case where the reactive current command value id * is controlled by monitoring the motor current 6a.

As described above, in the second and third embodiments, if a command is issued step by step when injecting reactive current, the torque of the electric motor 7 is affected depending on the response of the control system. There is something that happens.

In other words, applying a predetermined value as a reactive current at once causes the input of the control system to change drastically, and a change in the rotational speed of the electric motor 7 may occur in response to the change.

In this case, when the reactive current is injected, the RAM table input can be used to suppress the generation of vibration and to facilitate rotation.

In addition, the injection of reactive current causes the electric motor field to change with the magnetic flux caused by the reactive current in addition to the magnetic flux of the permanent magnet, and the rotation speed becomes the reference command in the rotation speed control system, so that the torque current change, that is, the torque current control system is sufficiently followed. It is desirable to be able to do this.

Embodiment 5

11 and 12 show an embodiment of the eighth invention of this invention, and FIG. 11 is a reactive current command value curve.

1, 2, 4, and 5 also share the fifth embodiment.

In addition, the operation of this embodiment will be described.

In step S1, it is determined whether the torque current feedback value 22b is larger than the first predetermined value Kiq, and if it is large, in step S11, it is determined whether the flag Fid is "1". Time T ₁ before the flag Fid is 12 sets the flag Fid to step S22 to a reactive current command value id * to zero "0" because "0".

When the torque current feedback value 22b becomes equal to or less than the first predetermined value Kiq at time T ₁ , the flow advances from step S1 to step S15, and the flag Fid is set to "1". In step S23, the reactive current command value id * is set to the second predetermined value Kid and held therein. (The increase in reactive current command value id * increases as described, but the explanation is omitted.)

If the torque current feedback value 22b is larger than the first predetermined value Kiq at time T ₂ , the flow advances to step S1? S11? S21, and it is determined whether the torque current feedback value 22b is greater than the fourth predetermined value Kiq max. If the fourth predetermined value Kiq max or less, the reactive current command value id * is set to the second predetermined value Kid in step S23.

If larger than the fourth predetermined value Kiq max, the flag Fid is set to "0" and the reactive current command value id * is set to 0 in step S22.

That is, in the section where the flag Fid is "1", even if the torque current feedback value 22b becomes larger than the first predetermined value Kiq, the process proceeds to step S1-> S11-> S21 and the torque current feedback value 22b is the fourth predetermined value Kiq. The reactive current command value id * must not be zero unless it is larger than max.

Thus, since the reactive current command value id * is given and it is judged as 4th predetermined value Kiq max until it returns to 0, the potential of a phase voltage is established, the distortion of a current waveform is corrected, and the vibration of the electric motor 7 is corrected. It becomes possible to suppress it.

In other words, when the reactive current is injected, the torque current command value jq * is also affected. In some cases, the torque current command value iq * or the torque current itself increases, and the injection of the reactive current continues with the first predetermined value Kiq, so-called oscillation state. It is anxious to cause.

In addition, although the output current 6a of the current detector 6 is separated into a torque current and a reactive current, the injection of the reactive current from the electron is judged, but it is also considered that the current is the motor current itself. In some cases, the first predetermined value Kiq may be exceeded immediately by the injection of, and the injection of the reactive current may be interrupted to cause a so-called oscillation state. In this case, the oscillation is prevented by making the injection conditions hysteretic.

As described above, in the first invention of the present invention, the reactive current command value is controlled so that the output current of the inverter does not become 0, the potential of the phase voltage is established, there is no distortion of the current waveform, and the vibration of the motor is prevented. It can be suppressed.

Further, in the second invention, the reactive current command value is flowed in the direction of strengthening the field of the motor, so that the absolute value of the reactive current component to be injected can be reduced.

In the third invention, the reactive current command value is set to the second predetermined value when the coat current feedback value is less than or equal to the first predetermined value, and the reactive current command value is set to zero when the torque current feedback value is larger than the first predetermined value. It is possible to prevent the output current of near 0, to suppress the vibration of the motor, and to prevent the temperature rise of the motor and to improve the operating efficiency of the motor without flowing a reactive current unless necessary.

Claims (2)

It consists of switching elements connected in series and has an inverter whose shifts are controlled so that these switching elements have a time delay from each other, and a permanent magnet synchronous motor connected to the inverter, and the torque current flowing in the motor is converted into torque current command value and torque. And a reactive current command control means for controlling the reactive current command value so as to contrast the current feedback value and to control the pulse width modulation control of the electric motor so as to flow in a direction of strengthening the field of the electric motor. Control device of magnet synchronous motor. The method of claim 1, The reactive current command control means is configured to set the reactive current command value to the second predetermined value when the torque current feedback value is less than or equal to the first predetermined value, and to set the reactive current command value to zero when the torque current feedback value is larger than the first predetermined value. Control device of a permanent magnet synchronous motor, characterized in that.