JP6017100B1 - Motor control device - Google Patents

Abstract

A converter circuit unit (11), a DC circuit unit (12), an inverter circuit unit (13), a bus voltage detection unit (14), a frequency command generation unit (16) that outputs a frequency command (f1), Based on the bus voltage detection signal Vdc, a voltage control unit (15) that outputs a frequency correction value (Δf) and a corrected frequency command (f2) obtained by correcting the frequency command or the frequency command (f1) with the frequency correction value (Δf) ) To output a voltage command (V1) from the voltage command generator (17), and an inverter that outputs an output voltage command, which is a voltage value, necessary for driving the motor (3) based on the voltage command (V2) A drive unit (20), and when the inverter circuit unit (13) decelerates the motor (3) by reducing the frequency of the AC power output to the motor (3), the frequency command ( f1 ) Or AC power having a frequency corresponding to the correction frequency command (f1) is output to the motor (3).

Description

  The present invention relates to a motor control device that controls driving of a motor.

  Conventionally, an inverter is used as power supply means for driving a motor at an arbitrary rotational speed. In the inverter, the commercial power supply is rectified and converted into direct current, and further converted into a voltage and frequency suitable for driving the motor and supplied. A DC voltage smoothing capacitor is connected to the DC circuit portion of the inverter. When the motor decelerates, regenerative operation is performed, but this regenerative energy causes the voltage of the DC voltage smoothing capacitor to suddenly rise and become overvoltage, resulting in damage. This phenomenon is particularly remarkable when the moment of inertia of the load applied to the motor is large and when the motor is suddenly decelerated.

  In Patent Document 1, the voltage applied to the motor at the time of deceleration of the motor is increased to amplify the current flowing through the motor and the motor magnetic flux accompanying the current to increase the motor loss, thereby suppressing the regenerative energy toward the inverter. A method is disclosed. In general, when generating an output voltage command to an inverter corresponding to a voltage command, it is necessary to detect the voltage of the DC circuit unit and divide the voltage command. In Patent Document 1, during deceleration control, the time constant of the voltage detection filter of the DC circuit section is changed to remove the transient increase in the DC circuit section voltage associated with the deceleration control. As a result, the amplitude of the output voltage command can be maintained and a high voltage can be applied to the motor, which increases the motor loss.

JP 2005-295614 A

  However, in the prior art of Patent Document 1, the motor is decelerated according to a preset deceleration rate even when the voltage of the DC voltage smoothing capacitor can be afforded by the overvoltage protection operation. Requires rate adjustment. In other words, before starting actual operation, if the voltage of the DC voltage smoothing capacitor has sufficient margin, information on how much the deceleration rate can be increased must be obtained by repeating the test, and the adjustment work in advance There is a problem that is complicated and long.

  The present invention has been made in view of the above, and obtains a motor control device capable of reducing the burden of adjustment and rapidly decelerating the motor more quickly while preventing damage due to overvoltage caused by regenerative operation. For the purpose.

In order to solve the above-described problems and achieve the object, the present invention provides a converter circuit unit that rectifies an AC output from an AC power source, a DC circuit unit that accumulates a rectified output of the converter circuit unit, and the DC circuit. An inverter circuit unit that converts DC power from the unit into AC power having an arbitrary frequency and outputs it to a motor, a bus voltage detection unit that detects a bus voltage that is a voltage across the DC circuit unit, and the inverter circuit unit A frequency command generation unit that outputs a frequency command for instructing the frequency of the AC power output from the power source, and a frequency correction value that corrects the frequency command based on the bus voltage detection signal detected by the bus voltage detection unit. A voltage control unit, a voltage command generation unit that outputs a voltage command from the frequency command or a corrected frequency command obtained by correcting the frequency command with the frequency correction value, An output voltage that is a voltage value of AC power output from the inverter circuit unit necessary for driving the motor at a rotational speed corresponding to the frequency command or the corrected frequency command obtained by correcting the frequency command with the frequency correction value An inverter drive unit that outputs a command based on the voltage command, and the inverter circuit unit reduces the frequency of the AC power output to the motor to decelerate the motor when the output voltage command According to the frequency command or the corrected frequency command, and outputs the AC power to the motor, and the voltage control unit rotates the motor when the bus voltage detection signal is larger than a predetermined bus voltage limit value. Outputting the frequency correction value for reducing the deceleration of the number .

  The motor control device according to the present invention has an effect that a motor control device capable of reducing the adjustment burden and rapidly decelerating the motor earlier can be obtained while preventing damage due to overvoltage caused by the regenerative operation. .

The block diagram which shows the structure of the motor control apparatus concerning embodiment of this invention The figure which shows an example of the hardware constitutions of the structure part of the motor control apparatus concerning embodiment of this invention The flowchart explaining the flow of the deceleration control operation | movement of the motor in the motor control apparatus concerning embodiment of this invention. The time chart which shows an example of the change of the bus-line voltage detection signal and motor rotation speed at the time of the deceleration adjustment operation of the motor in the motor control apparatus concerning embodiment of this invention The time chart which shows an example of the change of a motor current detection signal and a voltage command at the time of control of the motor current sent through a motor in the motor control device concerning an embodiment of the invention The time chart which shows the other example of the change of a bus-bar voltage detection signal and the motor rotation speed at the time of the deceleration adjustment operation | movement in the motor control apparatus concerning embodiment of this invention.

  Hereinafter, a motor control device according to an embodiment of the present invention will be described in detail with reference to the drawings. Note that the present invention is not limited to the embodiments.

Embodiment FIG. 1 is a configuration diagram showing a configuration of a motor control device 1 according to an embodiment of the present invention. FIG. 2 is a diagram illustrating an example of the hardware configuration of the components of the motor control device 1 according to the embodiment of the present invention. In the motor control device 1, a three-phase AC power source 2 is connected to an AC input terminal, and a motor 3 that is operated with a three-phase AC voltage as a load is connected to an output terminal.

  The motor control device 1 converts the converter circuit unit 11 connected to the three-phase AC power source 2, the DC circuit unit 12 that accumulates the rectified output of the converter circuit unit 11, and converts the DC output of the DC circuit unit 12 into an AC output. And an inverter circuit unit 13 that outputs to the motor 3.

  In addition, the motor control device 1 includes a bus voltage detection unit 14 disposed at a subsequent stage of the DC circuit unit 12, a voltage control unit 15 that outputs a frequency correction value Δf to control the voltage of the DC circuit unit 12, a motor 3 and a frequency command generation unit 16 that outputs a basic frequency command f1 of AC power to be output. The motor control device 1 also includes a voltage command calculation unit 18 that generates a voltage command V1 based on a frequency command, and a voltage command amplification unit 19 that amplifies the voltage command V1 and generates a voltage command V2. A voltage command generation unit 17 that generates a command, and an inverter drive unit 20 that is a drive circuit that controls the drive of the inverter circuit unit 13 based on the voltage command V2.

  In addition, the motor control device 1 includes a current detection unit 21 disposed between the inverter circuit unit 13 and the motor 3, and a current control unit 22 that generates a voltage command correction value ΔV for reducing the motor current. I have.

  The motor control device 1 also includes a bus voltage limit value storage memory 23 for storing the bus voltage limit value Vdc *, a subtraction connected to the bus voltage detection unit 14, the bus voltage limit value storage memory 23, and the voltage control unit 15. Connected to the voltage controller 24, the voltage controller 15, the frequency command generator 16, and the voltage command calculator 18, the voltage command amplifier 19, the inverter driver 20, and the current controller 22. And a subtractor 26.

  The motor 3 performs a power running operation and a regenerative operation. When the motor 3 performs a regenerative operation, the regenerative power charges the DC circuit unit 12 via the inverter circuit unit 13 and raises the bus voltage.

The converter circuit unit 11 converts the three-phase AC power fed from the three-phase AC power supply 2 through the three AC input terminals in the converter circuit unit 11 into DC power and rectifies it.

  The DC circuit unit 12 is composed of a DC voltage smoothing capacitor, smoothes and outputs the output voltage of the DC power rectified by the converter circuit unit 11, and forms a bus voltage between the positive bus P and the negative bus N To do.

  The inverter circuit unit 13 converts the bus voltage into AC power having an arbitrary magnitude and frequency by switching the bus voltage in accordance with an output voltage command whose switching element is a drive signal from the inverter drive unit 20, and from the output terminal Output to the motor 3. The inverter circuit unit 13 is exemplified by a pulse width modulation (PWM) inverter.

  The bus voltage detection unit 14 detects a bus voltage between the positive bus P and the negative bus N, which is a voltage across the DC circuit unit 12, and outputs the detected bus voltage to the voltage control unit 15 as a bus voltage detection signal Vdc.

  The voltage control unit 15 determines the voltage of the DC circuit unit 12 from the bus voltage detection signal Vdc detected by the bus voltage detection unit 14 and the bus voltage limit value Vdc * stored in the bus voltage limit value storage memory 23. In order to control, a frequency correction value Δf for correcting the frequency command f1 output by the frequency command generation unit 16 is determined. The frequency correction value Δf is a correction amount for correcting the frequency of the AC power in order to control the rotation speed of the motor 3. The bus voltage limit value Vdc * is a predetermined limit value of the bus voltage that is determined in advance so that the voltage of the DC circuit unit 12 does not become an overvoltage due to a voltage increase of the DC circuit unit 12 due to the regenerative power of the motor 3. Is set smaller than the overvoltage value of the DC circuit unit 12 in consideration of the safety factor. The bus voltage limit value Vdc * is held in the bus voltage limit value storage memory 23 in advance. Further, the bus voltage limit value Vdc * can be changed as appropriate by inputting information instructing to change the bus voltage limit value Vdc * from the outside to the bus voltage limit value storage memory 23.

  In the voltage control unit 15, a subtracter 24 receives a difference value between the bus voltage detection signal Vdc detected by the bus voltage detection unit 14 and the bus voltage limit value Vdc * stored in the bus voltage limit value storage memory 23. It is input from. The subtractor 24 calculates the difference value between the bus voltage detection signal Vdc and the bus voltage limit value Vdc * by performing the calculation according to the following equation (1), and outputs the difference value to the voltage controller 15. The voltage control unit 15 determines the frequency correction value Δf based on the difference value output from the subtractor 24. Note that the voltage controller 15 may have the function of the subtractor 24. In this case, the bus voltage limit value storage memory 23 may be provided in the voltage control unit 15.

  “Bus voltage limit value Vdc * −Bus voltage detection signal Vdc” (1)

  The frequency command generation unit 16 outputs a frequency command f1 for controlling the rotation speed of the motor 3. The frequency command generation unit 16 generates a frequency command f1 and outputs the frequency command f1 to the voltage command calculation unit 18 in order to perform control for reducing the rotation speed of the motor 3 during the deceleration operation of the motor 3. The frequency command generation unit 16 outputs a frequency command f1 that is a command of a frequency smaller than the frequency corresponding to the current rotational speed of the motor 3 in order to perform control to reduce the rotational speed of the motor 3 during the deceleration operation. . The frequency command generator 16 determines a frequency command f1 that is a deceleration frequency command at the time of deceleration according to a predetermined deceleration rate, based on information instructing deceleration input from the outside.

The voltage command calculation unit 18 calculates a voltage command V1 based on the frequency command f1 output from the frequency command generation unit 16 and the frequency correction value Δf output from the voltage control unit 15, and the voltage command amplification unit 19 Output to. The adder 25 includes a frequency command f1 outputted from the frequency command generation unit 16 adds a frequency correction value Δf output from the voltage control unit 15, the correction frequency corrected frequency command f1 in frequency correction value Δf Command f2 is calculated. Then, the adder 25 outputs the calculated correction frequency command f2 to the voltage command calculation unit 18. The voltage command calculation unit 18 calculates the voltage command V1 by a preset calculation based on the correction frequency command f2, and outputs the voltage command V1 to the voltage command amplification unit 19. Note that the voltage command calculation unit 18 may have the function of the adder 25.

  The voltage command amplification unit 19 amplifies the voltage command V1 input from the voltage command calculation unit 18 with a preset amplification factor, generates a voltage command V2, and outputs the voltage command V2 to the inverter drive unit 20. The function of the voltage command amplification unit 19 may be performed by the voltage command calculation unit 18. When the subtractor 26 and the current control unit 22 are to function, the voltage command V <b> 2 is output to the subtractor 26, and the calculation result in the subtracter 26 is output to the inverter driving unit 20. The case where the subtractor 26 and the current control unit 22 are functioned will be described later. Here, the case where the voltage command V2 is first input to the inverter drive unit 20 without being calculated by the subtractor 26 will be described.

  The inverter drive unit 20 calculates a voltage command that is a voltage value of AC power output from the inverter circuit unit 13 to the motor 3 in accordance with the voltage command V2 from the voltage command amplification unit 19, and the inverter circuit unit 13 as an output voltage command. Output to.

  The current detection unit 21 detects the drive current that flows from the inverter circuit unit 13 to the motor 3 and outputs the detected drive current to the current control unit 22 as a motor current detection signal I.

  Based on the motor current detection signal I and the current limit value Ilim, the current control unit 22 corrects the voltage command V2 and generates a voltage command correction value ΔV for reducing the motor current. The current limit value Ilim is a motor current limit reference value set to prevent motor burnout due to excessive motor current flowing through the motor 3, and is lower than the level of overcurrent that causes motor burnout. Yes, and stored in the current limit value storage memory 27 in advance. Further, the current limit value Ilim can be changed as appropriate by inputting information instructing the change of the current limit value Ilim from the outside to the current limit value storage memory 27.

  Bus voltage detection unit 14, voltage control unit 15, frequency command generation unit 16, voltage command calculation unit 18, voltage command amplification unit 19, inverter drive unit 20, bus voltage limit value storage memory 23, subtraction A regenerative power control unit is configured by the device 24 and the adder 25. Further, the bus voltage detection unit 14, the voltage control unit 15, the frequency command generation unit 16, the voltage command calculation unit 18, the voltage command amplification unit 19, the inverter drive unit 20, the current detection unit 21, and the current control The motor current control unit is configured by the unit 22, the bus voltage limit value storage memory 23, the subtractor 24, the adder 25, the subtractor 26, the current limit value storage memory 27, and the subtractor 28. .

  Of the configurations of the regenerative power control unit and the motor current control unit, the bus voltage detection unit 14 and the current detection unit 21 can be configured using a detector that is generally used in a motor control device. Moreover, each component other than the bus-bar voltage detection part 14 and the electric current detection part 21 among the structures of a regenerative electric power control part and a motor current control part is implement | achieved as a processing circuit of the hardware constitutions shown, for example in FIG. . For example, the processor 101 shown in FIG. 2 executes a program stored in the memory 102 for each component other than the bus voltage detector 14 and the current detector 21 in the configurations of the regenerative power controller and the motor current controller. This is realized. A plurality of processors and a plurality of memories may cooperate to realize the above function. In addition, a part of the functions other than the bus voltage detection unit 14 and the current detection unit 21 in the configuration of the regenerative power control unit and the motor current control unit is mounted as an electronic circuit, and the other parts are the processor 101 and the memory 102. You may make it implement | achieve using.

  Next, the deceleration control operation of the rotational speed of the motor 3 in the motor control device 1 according to the present embodiment will be described. FIG. 3 is a flowchart for explaining the flow of the deceleration control operation of the motor 3 in the motor control device 1 according to the present embodiment.

  When the motor 3 is rotating at a predetermined rotation speed and the speed reduction operation of the rotation speed of the motor 3 is started, the frequency command generation unit 16 sends the frequency command f1 to the voltage command calculation unit 18 in step S10. Output. When the motor 3 is suddenly decelerated, the regenerative power from the motor 3 charges the DC circuit unit 12 via the inverter circuit unit 13 and raises the bus voltage.

  Therefore, in order to confirm the rising state of the bus voltage, the bus voltage detection unit 14 detects the bus voltage detection signal Vdc at a predetermined cycle and outputs it to the subtracter 24 in step S20.

  In step S <b> 30, the subtractor 24 calculates the difference value between the bus voltage detection signal Vdc and the bus voltage limit value Vdc * by performing the calculation according to the above equation (1), and outputs the difference value to the voltage control unit 15. Based on the difference value output from the subtractor 24, the voltage control unit 15 performs a preset operation, for example, PI control, calculates the frequency correction value Δf, and outputs the frequency correction value Δf to the voltage command calculation unit 18. When the bus voltage detection signal Vdc makes a transition larger than the predetermined bus voltage limit value Vdc *, the voltage control unit 15 performs control in a direction to reduce the deceleration of the rotation speed of the motor 3, that is, the rotation speed of the motor 3. In order to perform control in a direction in which the descending direction becomes gentle, a frequency correction value Δf for performing correction for increasing the frequency command f1 is calculated. As will be described later, the time charts of the rotation speed of the motor 3 and the correction frequency command f2 have the same form. For this reason, the direction to reduce the deceleration of the rotation speed of the motor 3 is the direction to reduce the deceleration of the correction frequency command f2.

  Further, when the bus voltage detection signal Vdc makes a transition smaller than the predetermined bus voltage limit value Vdc *, the voltage control unit 15 controls the direction in which the deceleration of the rotation speed of the motor 3 is increased, that is, the rotation of the motor 3. In order to perform control in a direction in which the number decreases rapidly, a frequency correction value Δf for performing correction to decrease the frequency command f1 is calculated. As will be described later, the time charts of the rotation speed of the motor 3 and the correction frequency command f2 have the same form. For this reason, the direction to increase the deceleration of the rotation speed of the motor 3 is the direction to increase the deceleration of the correction frequency command f2. During the deceleration control operation of the motor 3, the voltage control unit 15 always calculates the frequency correction value Δf for each predetermined calculation cycle and outputs it to the voltage command calculation unit 18.

  Next, in step S40, the adder 25 adds the frequency command f1 output from the frequency command generation unit 16 and the frequency correction value Δf output from the voltage control unit 15 to calculate a correction frequency command f2. . Then, the adder 25 outputs the calculated correction frequency command f2 to the voltage command calculation unit 18. When the correction frequency command f2 is increased, that is, the deceleration of the rotational speed of the motor 3 is decreased, the regenerative power from the motor 3 toward the DC circuit unit 12 is reduced and the DC bus voltage is decreased. Conversely, when the correction frequency command f2 is decreased, that is, the deceleration of the rotation speed of the motor 3 is increased, the regenerative power from the motor 3 toward the DC circuit unit 12 is increased and the DC bus voltage is increased. By repeating this operation, the DC bus voltage can be decelerated while being kept in the vicinity of the bus voltage limit value Vdc *. The adder 25 calculates a new corrected frequency command f2 when a new frequency correction value Δf is input and when a new frequency command f1 is input.

  In step S50, the voltage command calculation unit 18 calculates a voltage command V1 corresponding to the correction frequency command f2 by a preset calculation based on the correction frequency command f2, and outputs the voltage command V1 to the voltage command amplification unit 19. . Further, the voltage command calculation unit 18 calculates a new voltage command V1 when a new correction frequency command f2 is input.

  Next, in step S60, the voltage command amplification unit 19 amplifies the voltage command V1 input from the voltage command calculation unit 18 with a preset amplification factor to generate the voltage command V2, and the inverter drive unit 20 Output to.

  Next, in step S <b> 70, the inverter drive unit 20 calculates an output voltage command value corresponding to the voltage command V <b> 2 input from the voltage command amplification unit 19 by a preset calculation, and outputs it to the inverter circuit unit 13. .

  Next, in step S80, based on the output voltage command value input from the inverter drive unit 20, the inverter circuit unit 13 converts the bus voltage into AC power having a frequency corresponding to the corrected frequency command f2, and from the output terminal. Output to the motor 3. The motor 3 is driven by AC power.

  By performing such control, it is possible to reduce the regenerative power toward the DC circuit unit 12, and it is possible to prevent damage to the motor control device 1 due to overvoltage of the DC circuit unit 12 during the regenerative operation. Further, when the bus voltage has a margin to the limit value, the deceleration of the rotation speed of the motor 3 can be increased to perform rapid deceleration.

  FIG. 4 is a time chart showing an example of changes in the bus voltage detection signal and the motor rotational speed during the deceleration adjustment operation of the motor 3 in the motor control device 1 according to the present embodiment. The overvoltage level shown in FIG. 4 is a bus voltage value level at which the DC circuit unit 12 becomes overvoltage and the motor control device 1 is damaged. Although FIG. 4 shows the motor rotation speed, when the correction frequency command f2 is shown in the time chart of FIG. 4, the time chart of the correction frequency command f2 has the same form as the motor rotation speed. In FIG. 4, the decelerations in the section from t1 to t2, the section from t2 to t3, and the section from t3 to t4 are averaged.

  When normal motor driving is performed at a predetermined rotational speed, deceleration control based on the frequency command f1 is started at time t1. The motor 3 performs a regenerative operation, and the regenerative power charges the DC circuit unit 12 via the inverter circuit unit 13 to increase the bus voltage.

  After the time t2, the voltage control unit 15 determines that the bus voltage detection signal Vdc has transitioned to a state greater than the bus voltage limit value Vdc *, and the deceleration of the correction frequency command f2 decreases as described above. Control for reducing the deceleration of the rotational speed of the motor 3 is performed. Thereby, regenerative electric power decreases.

  After the time t3, the voltage control unit 15 determines that the bus voltage detection signal Vdc has transitioned to a state smaller than the bus voltage limit value Vdc *, and the deceleration of the correction frequency command f2 increases as described above. Then, the control in the direction to increase the deceleration of the rotation speed of the motor 3 is performed. Thereby, it becomes possible to decelerate the rotation speed of the motor 3 earlier than the period from the time t2 to the time t3.

  After the time t4, the bus voltage detection signal Vdc becomes larger than the bus voltage limit value Vdc * again, and the deceleration of the correction frequency command f2 is decreased as described above, and the rotation speed of the motor 3 is decreased. Reduction control is performed. Thereby, regenerative electric power decreases. Thereafter, at time t5, the motor 3 stops.

  As described above, in the motor control device 1 according to the present embodiment, the deceleration of the rotational speed of the motor 3 is corrected based on the bus voltage detection signal Vdc that is the voltage value across the DC circuit unit 12. That is, when the bus voltage detection signal Vdc makes a transition larger than the bus voltage limit value Vdc *, the regenerative power can be reduced by reducing the deceleration of the rotational speed of the motor 3. Further, when the bus voltage detection signal Vdc makes a transition smaller than the bus voltage limit value Vdc *, the deceleration of the rotation speed of the motor 3 is increased to perform rapid deceleration, and the time until the motor 3 is stopped is shortened. This makes it possible to reduce the deceleration adjustment time for rapid deceleration.

  Further, in the motor control device 1 according to the present embodiment, since the adjustment of the deceleration of the rotation speed of the motor 3 is automatically performed at the time of actual operation, a test is performed in advance to determine the deceleration of the rotation speed of the motor 3. It is not necessary to prepare an adjustment value, and the adjustment burden related to sudden deceleration can be reduced.

  Further, by performing the above-described control when the bus voltage detection signal Vdc transitions larger than the bus voltage limit value Vdc * and when the bus voltage detection signal Vdc transitions smaller than the bus voltage limit value Vdc *. As shown in FIG. 4, it can be seen that the deceleration of the motor rotational speed or the deceleration of the correction frequency command f2 increases or decreases in conjunction with the fluctuation of the bus voltage detection signal Vdc. In particular, when the bus voltage detection signal Vdc makes a transition smaller than the bus voltage limit value Vdc *, the deceleration of the motor speed or the deceleration of the correction frequency command f2 increases.

  Next, control of the motor current during the deceleration control operation of the motor 3 in the motor control device 1 according to the present embodiment will be described.

  The subtractor 26 calculates a voltage command V3 by subtracting the voltage command correction value ΔV input from the current control unit 22 from the voltage command V2 output from the voltage command amplification unit 19. Then, the subtractor 26 outputs the voltage command V3 to the inverter drive unit 20.

  As described above, when control is performed to increase the motor loss and reduce the regenerative power toward the DC circuit unit 12, the control is applied to the motor 3 in order to prevent motor burnout due to excessive current flowing through the motor 3. It is necessary to suppress the motor current.

  Therefore, at the time of deceleration control of the motor 3, the current detection unit 21 detects the motor current flowing from the inverter circuit unit 13 to the motor 3 at a predetermined period and sets it as the motor current detection signal I. A difference value between the motor current detection signal I detected by the current detector 21 and the predetermined current limit value Ilim stored in the current limit value storage memory 27 is input from the subtractor 28 to the current controller 22. The The subtractor 28 performs a calculation according to the following equation (2), calculates a difference value between the motor current detection signal I and the current limit value Ilim, and outputs the difference value to the current control unit 22. Based on the difference value between the motor current detection signal I and the current limit value Ilim, the current control unit 22 performs a preset operation, for example, PI control to calculate the voltage command correction value ΔV. Note that the function of the subtractor 28 may be included in the current control unit 22. In this case, the current limit value storage memory 27 may be provided in the current control unit 22.

  “Current limit value Ilim−motor current detection signal I” (2)

  When the motor current detection signal I is larger than the current limit value Ilim, the current control unit 22 performs a preset calculation and sets the voltage command correction value ΔV so that the voltage command V3 becomes small. The operation of increasing is performed, and the calculated voltage command correction value ΔV is output to the subtractor 26.

  The subtractor 26 calculates the voltage command V3 by subtracting the voltage command correction value ΔV input from the current control unit 22 from the voltage command V2 input from the voltage command amplification unit 19. Then, the subtractor 26 outputs the voltage command V3 to the inverter drive unit 20. The inverter drive unit 20 calculates an output voltage command value corresponding to the voltage command V <b> 3 and outputs it to the inverter circuit unit 13. By outputting the output voltage command value calculated based on the voltage command V3 smaller than the voltage command V2 to the inverter circuit unit 13, the current flowing through the motor 3 can be reduced.

  When the motor current detection signal I is in a state smaller than the current limit value Ilim, the current control unit 22 performs a preset calculation and sets the voltage command correction value ΔV so that the voltage command V3 becomes large. The operation of decreasing is performed, and the calculated voltage command correction value ΔV is output to the subtractor 26. As a result, the current reduction control is released.

  Since the voltage command input to the inverter drive unit 20 can be reduced by performing the above-described control, the current output from the inverter circuit unit 13 to the motor 3 is reduced, and an excessive current is supplied to the motor 3. It can be prevented from flowing. As a result, it is possible to prevent motor burnout due to an excessive current flowing through the motor 3. Note that the function of the subtractor 26 may be performed by the inverter driving unit 20.

  FIG. 5 shows a motor current detection signal I when controlling the motor current flowing through the motor 3 when the motor control apparatus 1 according to the present embodiment performs control to increase the number of rotations of the motor 3 and reduce the regenerative power. It is a time chart which shows an example of the change of voltage command V2, V3.

  When normal motor driving is performed at a predetermined rotational speed, deceleration control using the correction frequency command f2 is started at time t11.

  After the time t12, the motor current detection signal I becomes larger than the current limit value Ilim. Then, as described above, the voltage command correction value ΔV is generated, and control is performed to reduce the current flowing through the motor 3 by reducing the voltage command input to the inverter drive unit 20. That is, the voltage command V3 obtained by subtracting the voltage command correction value ΔV output from the current control unit 22 from the voltage command V2 output from the voltage command amplification unit 19 is used as the voltage command. This prevents an excessive current from flowing through the motor 3.

  At time t13, the current control unit 22 determines that the increase in the motor current detection signal I has stopped. In this case, the voltage command correction value ΔV is decreased by a predetermined small amount, and the total voltage command input to the inverter drive unit 20 is increased by a small amount, thereby performing control to increase the current flowing through the motor 3 by a small amount. Is called. The regenerative electric power can be increased to increase the deceleration of the rotation speed of the motor 3, and the rotation speed of the motor 3 can be decelerated earlier than the period from time t12 to time t13.

  After the time t14, the motor current detection signal I becomes smaller than the current limit value Ilim. In this case, the voltage command correction value ΔV decreases, and the control for reducing the voltage command input to the inverter drive unit 20 is released.

  At time t15, deceleration control using the correction frequency command f2 is started.

  As described above, in the motor control device 1 according to the present embodiment, when the voltage command is increased during motor deceleration to increase the loss of the motor 3 and sudden deceleration is performed, the motor current detection signal I is the current limit value Ilim. By performing control to reduce the motor current so as to be within, it is possible to perform rapid deceleration while preventing motor burnout.

  4 and 5, the bus voltage limit value Vdc * and the current limit value Ilim are fixed values, but variable values may be used. FIG. 6 is a time chart showing another example of changes in the bus voltage detection signal and the motor rotational speed during the deceleration adjustment operation in the motor control device 1 according to the present embodiment. Although FIG. 6 shows the motor rotation speed, when the correction frequency command f2 is described in the time chart of FIG. 6, the time chart of the correction frequency command f2 has the same form as the motor rotation speed.

  When normal motor driving is performed at a predetermined rotational speed, deceleration control by the frequency command f1 is started at time t21. The motor 3 performs a regenerative operation, and the regenerative power charges the DC circuit unit 12 via the inverter circuit unit 13 to increase the bus voltage.

  After the time t22, the voltage control unit 15 determines that the bus voltage detection signal Vdc is larger than the bus voltage limit value Vdc *, and the deceleration of the correction frequency command f2 is reduced as described above. Control for reducing the deceleration of the rotational speed of 3 is performed. Thereby, regenerative electric power decreases. When the voltage control unit 15 determines that the bus voltage detection signal Vdc is smaller than the bus voltage limit value Vdc *, the deceleration of the correction frequency command f2 increases as described above, and the motor 3 Control in the direction to increase the deceleration of the rotational speed is performed. Thereby, it becomes possible to decelerate the rotation speed of the motor 3 faster than the control by the deceleration corresponding to the frequency command f1 determined by the frequency command generation unit 16. In FIG. 6, the control for reducing the deceleration of the rotation speed of the motor 3 and the control for increasing the deceleration of the rotation speed of the motor 3 are repeated, but the motor rotation speed is not for individual control. Shown on average.

  Thereafter, the control for reducing the deceleration of the rotational speed of the motor 3 and the control for increasing the deceleration of the rotational speed of the motor 3 are repeated. Here, voltage control is performed when a predetermined time from time t23 to time t24 elapses when the bus voltage detection signal Vdc is within the predetermined level range set in advance from the bus voltage limit value Vdc *. Unit 15 increases the setting of bus voltage limit value Vdc * by a predetermined amount within a range in which the overvoltage level is not reached. That is, when the bus voltage detection signal Vdc varies within a preset range from the bus voltage limit value Vdc * exceeds a predetermined elapsed time, the bus voltage detection signal Vdc further increases. Therefore, the bus voltage limit value Vdc * can be increased by a predetermined amount. In this case, the overvoltage level is not reached even when the bus voltage detection signal Vdc exceeds the increased bus voltage limit value Vdc *, and is set small enough not to reach the overvoltage in consideration of a predetermined safety factor. . The predetermined level range from the bus voltage limit value Vdc * is ± α% of the bus voltage limit value Vdc *.

  By adopting a configuration in which the bus voltage limit value Vdc * is increased by a predetermined amount to increase the deceleration of the rotation speed of the motor 3, a more rapid deceleration is possible. That is, increasing the bus voltage limit value Vdc * increases the time during which the control for increasing the deceleration of the motor 3 can be increased, so that a faster deceleration is possible than when the bus voltage limit value Vdc * is not increased. Become.

  As described above, in the motor control device 1 according to the present embodiment, the deceleration of the rotational speed of the motor 3 is determined based on the bus voltage detection signal Vdc that is a voltage detection value of the DC circuit unit 12. That is, when the bus voltage detection signal Vdc makes a transition larger than the bus voltage limit value Vdc *, the regenerative power can be reduced by reducing the deceleration of the rotational speed of the motor 3. Further, when the bus voltage detection signal Vdc makes a transition smaller than the bus voltage limit value Vdc *, the deceleration of the rotation speed of the motor 3 is increased to perform rapid deceleration, and the time until the motor 3 is stopped is shortened. This makes it possible to reduce the deceleration adjustment time for rapid deceleration. Therefore, according to the motor control device 1 according to the present embodiment, the motor can be rapidly decelerated more quickly while preventing damage due to the regenerative operation.

  In the motor control device 1 according to the present embodiment, the motor current detection signal I falls within the current limit value Ilim when the voltage command is increased at the time of motor deceleration to increase the loss of the motor 3 and suddenly decelerate. Thus, control is performed to reduce the motor current. Therefore, according to the motor control device 1 according to the present embodiment, it is possible to perform rapid deceleration while preventing motor burnout.

  The configuration described in the above embodiment shows an example of the contents of the present invention, and can be combined with another known technique, and can be combined with other configurations without departing from the gist of the present invention. It is also possible to omit or change the part.

  DESCRIPTION OF SYMBOLS 1 Motor control apparatus, 2 3 phase alternating current power supply, 3 Motor, 11 Converter circuit part, 12 DC circuit part, 13 Inverter circuit part, 14 Bus voltage detection part, 15 Voltage control part, 16 Frequency command generation part, 17 Voltage command generation Unit, 18 voltage command calculation unit, 19 voltage command amplification unit, 20 inverter drive unit, 21 current detection unit, 22 current control unit, 23 bus voltage limit value storage memory, 24 subtractor, 25 adder, 26 subtractor, 27 Current limit value storage memory, 28 subtractor, 101 processor, 102 memory, f1 frequency command, f2 correction frequency command, I motor current detection signal, Ilim current limit value, N negative bus, P positive bus, V1, V2, V3 voltage Command, Vdc bus voltage detection signal, Vdc * bus voltage limit value, Δf frequency correction value, ΔV voltage command correction value.

Claims (8)

A converter circuit for rectifying the AC output from the AC power supply;
A DC circuit section for storing the rectified output of the converter circuit section;
An inverter circuit unit that converts DC power from the DC circuit unit into AC power having an arbitrary frequency and outputs the AC power to the motor;
A bus voltage detecting unit for detecting a bus voltage which is a voltage across the DC circuit unit;
A frequency command generation unit that outputs a frequency command that indicates the frequency of the AC power output from the inverter circuit unit;
A voltage control unit that outputs a frequency correction value for correcting the frequency command based on a bus voltage detection signal detected by the bus voltage detection unit;
A voltage command generation unit that outputs a voltage command from the frequency command or a corrected frequency command obtained by correcting the frequency command with the frequency correction value;
Output that is a voltage value of AC power output from the inverter circuit unit necessary for driving the motor at a rotation speed corresponding to the frequency command or the corrected frequency command obtained by correcting the frequency command with the frequency correction value An inverter drive unit that outputs a voltage command based on the voltage command;
With
When the inverter circuit unit decelerates the motor by reducing the frequency of the AC power output to the motor, the inverter circuit unit generates AC power having a frequency corresponding to the frequency command or the correction frequency command according to the output voltage command. Output to
The voltage control unit, when the bus voltage detection signal is larger than a predetermined bus voltage limit value, to output the frequency correction value to reduce the deceleration of the rotation speed of the motor;
A motor control device. The voltage control unit, when the bus voltage detection signal is less than the predetermined bus voltage limit value, it outputs the frequency correction value for increasing the rotational speed of the deceleration of the motor,
The motor control device according to claim 1 .   A converter circuit for rectifying the AC output from the AC power supply;
  A DC circuit section for storing the rectified output of the converter circuit section;
  An inverter circuit unit that converts DC power from the DC circuit unit into AC power having an arbitrary frequency and outputs the AC power to the motor;
  A bus voltage detecting unit for detecting a bus voltage which is a voltage across the DC circuit unit;
  A frequency command generation unit that outputs a frequency command that indicates the frequency of the AC power output from the inverter circuit unit;
  A voltage control unit that outputs a frequency correction value for correcting the frequency command based on a bus voltage detection signal detected by the bus voltage detection unit;
  A voltage command generation unit that outputs a voltage command from the frequency command or a corrected frequency command obtained by correcting the frequency command with the frequency correction value;
  Output that is a voltage value of AC power output from the inverter circuit unit necessary for driving the motor at a rotation speed corresponding to the frequency command or the corrected frequency command obtained by correcting the frequency command with the frequency correction value An inverter drive unit that outputs a voltage command based on the voltage command;
  With
  When the inverter circuit unit decelerates the motor by reducing the frequency of the AC power output to the motor, the inverter circuit unit generates AC power having a frequency corresponding to the frequency command or the correction frequency command according to the output voltage command. Output to
  The voltage control unit, when the bus voltage detection signal is smaller than a predetermined bus voltage limit value, to output the frequency correction value to increase the deceleration of the rotation speed of the motor;
  A motor control device. A current detection unit connected between the motor and the inverter circuit unit for detecting a motor current of the motor;
A current control unit that outputs a voltage command correction value for correcting the voltage command and reducing the motor current based on a motor current detection signal detected by the current detection unit;
With
The inverter drive unit outputs the output voltage command based on the voltage command corrected by the voltage command correction value;
The motor control apparatus according to any one of claims 1 to 3, characterized in. The current control unit outputs the voltage command correction value for decreasing the voltage command when the motor current detection signal transits to a state larger than a predetermined current limit value;
The motor control device according to claim 4 .   A converter circuit for rectifying the AC output from the AC power supply;
  A DC circuit section for storing the rectified output of the converter circuit section;
  An inverter circuit unit that converts DC power from the DC circuit unit into AC power having an arbitrary frequency and outputs the AC power to the motor;
  A bus voltage detecting unit for detecting a bus voltage which is a voltage across the DC circuit unit;
  A frequency command generation unit that outputs a frequency command that indicates the frequency of the AC power output from the inverter circuit unit;
  A voltage control unit that outputs a frequency correction value for correcting the frequency command based on a bus voltage detection signal detected by the bus voltage detection unit;
  A voltage command generation unit that outputs a voltage command from the frequency command or a corrected frequency command obtained by correcting the frequency command with the frequency correction value;
  Output that is a voltage value of AC power output from the inverter circuit unit necessary for driving the motor at a rotation speed corresponding to the frequency command or the corrected frequency command obtained by correcting the frequency command with the frequency correction value An inverter drive unit that outputs a voltage command based on the voltage command;
  With
  When the inverter circuit unit decelerates the motor by reducing the frequency of the AC power output to the motor, the inverter circuit unit generates AC power having a frequency corresponding to the frequency command or the correction frequency command according to the output voltage command. Output to
  The voltage control unit is configured to change the bus voltage limit value to the DC circuit when the bus voltage detection signal fluctuates within a preset range from the bus voltage limit value exceeds a predetermined elapsed time. Increase within a range that does not reach the overvoltage of the part,
  A motor control device.   A current detection unit connected between the motor and the inverter circuit unit for detecting a motor current of the motor;
  A current control unit that outputs a voltage command correction value for correcting the voltage command and reducing the motor current based on a motor current detection signal detected by the current detection unit;
  With
  The inverter drive unit outputs the output voltage command based on the voltage command corrected by the voltage command correction value;
  The motor control device according to claim 6.   The current control unit outputs the voltage command correction value for decreasing the voltage command when the motor current detection signal transits to a state larger than a predetermined current limit value;
  The motor control device according to claim 7.

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