JP5371382B2 - Power converter - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a power conversion apparatus which controls speed overshoot and speed offset at the completion of acceleration and deceleration with respect to acceleration and the deceleration at a torque limit. <P>SOLUTION: An electric motor drive system 50 includes the power conversion apparatus 1, wherein a speed reference rate circuit 6 operates a speed reference SP_R by a change rate of the speed reference SP_R and operates a deviation SP_DEV between a detected speed SP_F of an electric motor 2 and the speed reference SP_R, and a speed control circuit 7 makes an output for controlling the speed of the electric motor 2 based on the deviation SP_DEV, differentiates the speed reference SP_R, operates an acceleration-deceleration torque reference TCMP, compensates the acceleration-deceleration torque reference TCMP for the output of the speed control circuit 7, controls the electric motor 2 based on the compensated output, changes the change rate of the speed reference rate circuit 6 based on the speed SP_F so as that the deviation SP_DEV is kept constant. <P>COPYRIGHT: (C)2010,JPO&amp;INPIT

Description

  The present invention relates to a power conversion device that controls an electric motor.

Conventionally, in an electric power converter that controls an electric motor, it is known to compensate an acceleration / deceleration torque reference calculated from a change rate of a speed reference to an output of speed control (see, for example, Patent Document 1).
Japanese Patent Laid-Open No. 01-243866

  However, in the above-described power converter, when accelerating / decelerating at the torque limit, when the acceleration / deceleration of the motor is completed, in order to compensate for the output of the speed control, if the torque calculated from the speed reference change rate is greater than zero, Speed overshoots. On the other hand, if this torque is less than zero, a speed offset occurs.

  At this time, the speed overshoot and speed offset at the completion of acceleration / deceleration depend on the response of the speed control.

  However, it is difficult to sufficiently suppress this speed overshoot and speed offset only by speed control.

  Therefore, an object of the present invention is to provide a power converter that can suppress speed overshoot and speed offset at the time of acceleration / deceleration completion in acceleration / deceleration at a torque limit.

A power conversion device according to an aspect of the present invention includes a speed reference calculating unit that calculates the speed reference based on a rate of change of a speed reference that is a reference for the speed of the motor, Based on the speed deviation calculating means for calculating a deviation between the speed reference calculated by the speed reference calculating means and the speed calculated by the speed calculating means, and based on the deviation calculated by the speed deviation calculating means, Speed control means for outputting speed control for controlling the speed of the electric motor, and acceleration / deceleration torque serving as a reference for acceleration / deceleration torque of the electric motor based on the speed reference calculated by the speed reference calculating means Acceleration / deceleration torque reference calculation means for calculating a reference and acceleration / deceleration torque reference calculated by the acceleration / deceleration torque reference calculation means are output from the speed control means. A speed control output compensating means for compensating the output of the serial speed control, the output of the speed control, which is compensated by the speed control output compensating means, and the torque limiter to the process of limiting the torque of the electric motor by the limit value, the Based on the output of the speed control processed by the torque limiter, using a di / dt change rate, a torque reference calculation means for calculating a torque reference serving as a reference for the torque of the motor, and a calculation by the torque reference calculation means The acceleration / deceleration torque reference calculation means when the acceleration / deceleration of the electric motor is completed based on the deviation calculated by the speed deviation calculation means and the control means for controlling the electric motor based on the torque reference. the computed by the acceleration and deceleration torque reference to zero, the change of the di / dt rate of change of the torque reference calculating means And a di / dt change ratio varying unit that.

  ADVANTAGE OF THE INVENTION According to this invention, in the acceleration / deceleration in a torque limit, the power converter device which can suppress the speed overshoot and speed offset at the time of completion of acceleration / deceleration can be provided.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

(First embodiment)
FIG. 1 is a configuration diagram showing a configuration of an electric motor drive system 50 according to the first embodiment of the present invention. In addition, the same code | symbol is attached | subjected to the same part in subsequent figures, the detailed description is abbreviate | omitted, and a different part is mainly described. In the following embodiments, the same description is omitted.

  The electric motor drive system 50 includes a power converter 1, an electric motor 2, a control device 3, current transformers CT1 and CT2, and a speed detector SS.

  The power converter 1 converts DC power into three-phase AC power and outputs it. The power converter 1 supplies the converted AC power to the electric motor 2. The power converter 1 controls the speed and output torque of the electric motor 2 with AC power supplied to the electric motor 2.

  The control device 3 controls the AC power output from the power converter 1. The control device 3 measures the current amount of the three-phase alternating current output from the power converter 1 using the current transformers CT1 and CT2. The control device 3 measures the rotation speed of the electric motor 2 with the speed detector SS. The control device 3 controls the AC power output from the power converter 1 based on the measured current amount and rotation speed.

  The control device 3 includes a speed signal calculator 4, an integrator 5, a speed reference rate circuit 6, a speed control circuit 7, a torque limiter 8, a di / dt circuit 9, a current reference circuit 10, and a current detection. Circuit 11, current control circuit 12, voltage reference circuit 13, PWM circuit 14, acceleration / deceleration rate setting unit 16, constant acceleration detection unit 19, memory circuit 20, torque limit setting unit 23, di / dt setter 24, adder AD1, differentiator DF1, differentiator DF11, gain circuit G1, holding circuit HO11, OR circuit OR11, subtractors SU1, SU2, SU11, selectors SW11A, SW11B, And a zero hold circuit ZH11.

  Next, the operation at the initial stage of the operation start of the control device 3 will be described.

  In the acceleration / deceleration rate setter 16, an initial value of the rate setting value is set.

  The holding circuit HO11 outputs the signal SEL as “0” in the initial state. For this reason, the selector SW11B is inserted. On the other hand, the selector SW11A is turned off. The OR circuit OR11 receives the rate set value from the acceleration / deceleration rate setter 16. On the other hand, the OR circuit OR11 has no input from the memory circuit 20. Accordingly, the OR circuit OR11 outputs the initial value of the rate setting value to the speed reference rate circuit 6.

  When the reset signal RESET is input, the holding circuit HO11 sets the signal SEL to “0”. The function of the holding circuit HO11 is locked when the enable signal ENABLE is not input. In this case, the rate set value set in the acceleration / deceleration rate setter 16 is always input to the OR circuit OR11.

  The speed reference rate circuit 6 receives an external speed reference SP_REF1. The external speed reference SP_REF1 is a reference for calculating a speed reference SP_R that is a reference for the speed of the electric motor 2. In the initial state, the speed reference rate circuit 6 receives the rate set value set in the acceleration / deceleration rate setter 16. The speed reference rate circuit 6 calculates the speed reference SP_R based on the external speed reference SP_REF1, using the rate setting value as the rate of change. The speed reference rate circuit 6 outputs the calculated speed reference SP_R to the subtractor SU1 and the differentiator DF1.

  The speed signal calculator 4 receives a rotation speed detection signal of the electric motor 2 from the speed detector SS. The speed signal calculator 4 calculates a phase θ that is information on the magnetic flux position of the electric motor 2 based on the input rotational speed. The speed signal calculator 4 outputs the calculated phase θ to the integrator 5 and the current detection circuit 11.

  The integrator 5 integrates the phase θ input from the speed signal calculator 4 and calculates the motor speed SP_F. The integrator 5 outputs the calculated motor speed SP_F to the subtractor SU1 and the differentiator DF11.

  The subtracter SU1 receives the speed reference SP_R from the speed reference rate circuit 6. The subtractor SU1 receives the motor speed SP_F from the integrator 5. The subtractor SU1 subtracts the motor speed SP_F from the speed reference SP_R to calculate a speed deviation SP_DEV. The subtractor SU1 outputs the calculated speed deviation SP_DEV to the speed control circuit 7.

  The speed control circuit 7 calculates a speed control output ASPR_OUT based on the speed deviation SP_DEV input from the subtracter SU1. The speed control circuit 7 outputs the calculated speed control output ASPR_OUT to the adder AD1.

  The differentiator DF1 differentiates the speed reference SP_R input from the speed reference rate circuit 6. The differentiator DF1 outputs the differentiated calculation result to the gain circuit G1.

  The gain circuit G1 calculates the acceleration / deceleration torque TCMP by multiplying the calculation result input from the differentiator DF1 by a gain. The acceleration / deceleration torque TCMP is an ideal torque of the electric motor 2. The gain circuit G1 outputs the calculated acceleration / deceleration torque TCMP to the adder AD1.

  The speed control output ASPR_OUT is input from the speed control circuit 7 to the adder AD1. The adder AD1 receives the acceleration / deceleration torque TCMP from the adder AD1. The adder AD1 adds the acceleration / deceleration torque TCMP to the speed control output ASPR_OUT. The adder AD1 outputs the added calculation result to the torque limiter 8.

  The torque limiter 8 performs a limit process on the calculation result input from the adder AD1 with the limit value set by the torque limit setting unit 23. The torque limiter 8 outputs the calculation result subjected to the limit process to the di / dt circuit 9.

  The di / dt circuit 9 limits the calculation result input from the torque limiter 8 by the rate of change set in the di / dt setting unit 24, and calculates a torque reference T_R. The di / dt circuit 9 outputs the calculated torque reference T_R to the current reference circuit 10.

  The current reference circuit 10 divides the torque reference T_R input from the di / dt circuit 9 by the magnetic flux. Thereby, the current reference circuit 10 calculates the magnetic flux reference according to the torque current reference Iq_R and the speed reference. The current reference circuit 10 calculates a magnetic flux current reference Id_R corresponding to this magnetic flux. The current reference circuit 10 outputs the calculated torque current reference Iq_R and magnetic flux current reference Id_R to the subtractor SU2.

  The current detection circuit 11 receives the phase θ from the speed signal calculator 4. The current detection circuit 11 receives the two-phase alternating current output from the power converter 1 from the current transformers CT1 and CT2. The current detection circuit 11 calculates the torque current Iq_F and the magnetic flux current Id_F using the phase θ from the speed signal calculator 4 based on the amount of alternating current input from the current transformers CT1 and CT2. The current detection circuit 11 outputs the calculated torque current Iq_F and magnetic flux current Id_F to the subtractor SU2.

  The current control unit 12 compares the torque current reference Iq_R input from the current reference circuit 10 with the torque current Iq_F input from the current detection circuit 11, and calculates a voltage reference Eq_R. The current control unit 12 compares the magnetic flux current reference Id_R input from the current reference circuit 10 with the magnetic flux current Id_F input from the current detection circuit 11, and calculates the voltage reference Ed_R. The current control unit 12 outputs the calculated voltage reference Eq_R and voltage reference Ed_R to the voltage reference circuit 13.

  The voltage reference circuit 13 receives the voltage reference Eq_R and the voltage reference Ed_R from the current control unit 12. The voltage reference circuit 13 receives the phase θ from the speed signal calculator 4. The voltage reference circuit 13 calculates the voltage reference of each phase of the three-phase AC voltage output from the power converter 1 by using the voltage reference Eq_R and the voltage reference Ed_R using the phase θ. The voltage reference circuit 13 outputs the calculated voltage reference for each phase to a PWM (Pulse Width Modulation) control unit 14.

  The PWM control unit 14 generates a gate pulse signal based on the voltage reference of each phase input from the voltage reference circuit 13. The PWM control unit 14 outputs the generated gate pulse signal to the power converter 1. Thereby, the PWM control unit 14 controls the power converter 1.

  Next, the operation of the control device 3 after starting to drive the electric motor 2 will be described.

  When the electric motor 2 is driven, the electric motor speed SP_F is input from the integrator 5 to the differentiator DF11.

  The differentiator DF11 differentiates the motor speed SP_F input from the integrator 5 and calculates an acceleration. The differentiator DF11 outputs the calculated acceleration to the memory circuit 20, the zero hold circuit ZH11, and the subtractor SU11.

  The memory circuit 20 stores the acceleration input from the differentiator DF11 as needed. At this time, the memory circuit 20 has not finalized the acceleration to be finally stored. When the memory circuit 20 receives a constant acceleration signal AC output from the constant acceleration detector 19 described later, the memory circuit 20 stops writing and finally determines the acceleration to be stored as the latest acceleration. As a result, this finally stored acceleration is the maximum acceleration of the electric motor 2.

  The zero hold circuit ZH11 temporarily holds the acceleration input from the differentiator DF11. The zero hold circuit ZH11 outputs the temporarily held acceleration to the subtractor SU11 as the acceleration before one sampling.

  The subtractor SU11 receives the latest acceleration from the differentiator DF11. The subtracter SU11 receives the acceleration before one sampling from the zero hold circuit ZH11. The subtractor SU11 calculates the difference between the latest acceleration and the acceleration before one sampling. The subtractor SU <b> 11 outputs the calculated difference to the constant acceleration detection unit 19.

  The constant acceleration detection unit 19 detects that the acceleration (change rate differentiated by the differentiator 15) becomes constant based on the difference input from the subtractor SU11. When detecting that the acceleration is constant, the constant acceleration detecting unit 19 outputs a constant acceleration signal AC to the memory circuit 20 and the holding circuit HO11.

  When the constant acceleration signal AC is input, the holding circuit HO11 holds the signal SEL at “1” and outputs it to the selectors SW11A and SW11B.

  The selector SW11B is turned off when the signal SEL is received as “1”. As a result, the set value from the acceleration / deceleration rate setter 16 is not input to the OR circuit OR11.

  The selector SW11A is turned on when the signal SEL is received as “1”. As a result, the acceleration stored in the memory circuit 20 is input to the OR circuit OR11.

  The OR circuit OR11 receives the acceleration stored in the memory circuit 20 when “1” is output as the signal SEL from the holding circuit HO11. Thus, the OR circuit OR11 outputs the acceleration stored in the memory circuit 20 to the speed reference rate circuit 6.

  When the speed reference rate circuit 6 receives the acceleration stored in the memory circuit 20 from the OR circuit OR11, the speed reference rate circuit 6 calculates the speed reference SP_R using the acceleration as a change rate.

  The control device 3 controls the power converter 1 by repeating the above operation.

  According to the present embodiment, the speed reference rate circuit 6 is set with an acceleration / deceleration rate at a torque limit. Thereby, the speed deviation SP_DEV between the speed SP_F of the electric motor 2 and the speed reference SP_R becomes constant, so that the control device 3 can optimize the timing at which the acceleration / deceleration torque TCMP obtained by differentiating the speed reference SP_R becomes zero. it can.

  FIG. 2 is a graph showing characteristics of the electric motor drive system 50 according to the present embodiment.

  Therefore, as shown in FIG. 2, the motor drive system 50 can suppress speed overshoot and speed offset when acceleration / deceleration is completed. Thereby, the electric motor drive system 50 can minimize the acceleration / deceleration time of the electric motor 2.

  In the present embodiment, since the electric motor 2 performs acceleration / deceleration at the torque limit, the acceleration / deceleration characteristics can be improved without affecting the acceleration / deceleration time due to the change rate of the speed reference rate being changed.

(Second Embodiment)
FIG. 3 is a configuration diagram showing a configuration of an electric motor drive system 50A according to the second embodiment of the present invention.

  In the electric motor drive system 50 according to the first embodiment shown in FIG. 1, the electric motor drive system 50A replaces the control device 3 with the control device 3A. The other points are the same configuration.

  The control device 3A includes a speed signal calculator 4, an integrator 5, a speed reference rate circuit 6, a speed control circuit 7, a torque limiter 8, a di / dt circuit 9, a current reference circuit 10, and a current detection. Circuit 11, current control circuit 12, voltage reference circuit 13, PWM circuit 14, acceleration / deceleration rate setter 16, constant speed deviation detector 22, torque limit setter 23, and di / dt setter 24 , Adder AD1, differentiator DF1, gain circuit G1, holding circuit HO21, OR circuit OR21, subtractors SU1, SU2, SU21, SU22, selectors SW21A, SW21B, SW22, SW23, setting VL21 and zero hold circuits ZH21 and ZH22.

  Next, an operation at an initial stage of operation start of the control device 3A will be described.

  First, in the initial stage, selectors SW21B, SW22, and SW23 are inserted. On the other hand, the selector SW21A is turned off.

  In the torque limit setting device 23, an initial value of the torque limit value TR_MAX is set. The torque limit setter 23 outputs the set torque limit value TR_MAX to the OR circuit OR21 via the selectors SW21B and SW22 sequentially.

  The OR circuit OR21 has no input from the subtractor SU22 because the selector SW21A is cut off. Accordingly, the OR circuit OR21 outputs the torque limit value TR_MAX set in the torque limit setting unit 23 to the torque limiter 8. Thereby, the torque limiter 8 operates with the torque limit value TR_MAX set in the torque limit setting unit 23.

  The OR circuit OR21 outputs the torque limit value TR_MAX set in the torque limit setter 23 to the zero hold circuit ZH22.

  When the torque limit value TR_MAX set in the torque limit setting unit 23 is set in the torque limiter 8, the permission signal ENABLE is input. Thereby, selector SW21B is cut off. On the other hand, the selector SW21A is inserted.

  The zero hold circuit ZH22 temporarily holds the torque limit value TR_MAX input from the OR circuit OR21. The zero hold circuit ZH22 outputs the temporarily held torque limit value TR_MAX to the subtractor SU22 as the torque limit value TR_MAX before one sampling.

  “1” is set in the setting device VL21. The setter VL21 outputs the set “1” to the subtractor SU22.

  The subtractor SU22 receives the torque limit value TR_MAX before one sampling from the zero hold circuit ZH22. The subtracter SU22 receives “1” from the setter VL21. The subtractor SU22 calculates a value obtained by subtracting “1” from the torque limit value TR_MAX before one sampling as the latest torque limit value TR_MAX. The subtractor SU22 outputs the calculated torque limit value TR_MAX to the OR circuit OR21.

  The OR circuit OR21 has no input from the torque limit setting unit 23 because the selector SW21B is cut off. Therefore, the OR circuit OR21 outputs the torque limit value TR_MAX input from the subtractor SU22 to the torque limiter 8. Thereby, the torque limiter 8 operates with the latest torque limit value TR_MAX.

  By this series of processes, the initial value of the torque limit value TR_MAX set in the torque limit setting unit 23 is continuously subtracted until the speed deviation SP_DEV becomes constant. The torque limiter 8 operates at the latest torque limit value TR_MAX that continues to be subtracted from the torque limit value TR_MAX set in the setting device 23.

  Next, when the electric motor 2 is driven, the electric motor speed SP_F is input from the integrator 5 to the subtractor SU1.

  The subtractor SU1 calculates a speed deviation SP_DEV between the speed reference SP_R and the motor speed SP_F. The subtractor SU1 outputs the calculated speed deviation SP_DEV to the speed control circuit 7, the zero hold circuit ZH21, and the subtractor SU21.

  The zero hold circuit ZH21 temporarily holds the speed deviation SP_DEV input from the subtracter SU1. The zero hold circuit ZH21 outputs the temporarily held speed deviation SP_DEV to the subtracter SU21 as a speed deviation before one sampling.

  The latest speed deviation SP_DEV is input to the subtractor SU21 from the subtractor SU1. The subtractor SU21 receives the speed deviation SP_DEV one sampling before from the zero hold circuit ZH21. The subtractor SU21 calculates the difference between the latest speed deviation SP_DEV and the speed deviation SP_DEV one sampling before. The subtractor SU21 outputs the calculated difference to the constant speed deviation detection unit 22.

  The speed deviation constant detection unit 22 detects that the speed deviation SP_DEV has become constant based on the difference input from the subtractor SU21. When the constant speed deviation detector 22 detects that the speed deviation SP_DEV has become constant, it outputs a constant speed deviation signal DC to the holding circuit HO21.

  When the constant speed deviation signal DC is input, the holding circuit HO21 holds the signal DCX at “1” and outputs it to the selectors SW22 and SW23. When the reset signal RESET is input, the holding circuit HO21 sets the signal DCX to “0”.

  The selector SW22 is turned off when the signal DCX is received as “1”. As a result, the set value from the torque limit setting device 23 is not input to the OR circuit OR21.

  The selector SW23 is turned off when the signal DCX is received as “1”. As a result, the subtracter SU22 does not receive “1” set in the setting unit VL21. That is, the selector SW23 does not subtract the torque limit value TR_MAX before one sampling.

  Therefore, after the speed deviation SP_DEV is constant, the torque limiter 8 operates with the torque limit value TR_MAX immediately after the speed deviation SP_DEV becomes constant.

  According to the present embodiment, the initial value of the torque limit value TR_MAX set in the torque limit setting unit 23 is continuously subtracted until the speed deviation SP_DEV becomes constant. By operating the torque limiter 8 at the variable torque limit value TR_MAX, the speed deviation SP_DEV can be made constant. Thereby, the timing at which the acceleration / deceleration torque TCMP becomes zero can be optimized.

  Therefore, the motor drive system 50A can suppress speed overshoot and speed offset when acceleration / deceleration is completed.

  The electric motor drive system 50A according to the present embodiment is particularly effective when priority is given to speed overshoot and speed offset suppression upon completion of acceleration / deceleration over acceleration / deceleration time.

(Third embodiment)
FIG. 4 is a configuration diagram showing a configuration of an electric motor drive system 50B according to the third embodiment of the present invention.

  In the electric motor drive system 50B according to the first embodiment shown in FIG. 1, the electric motor drive system 50B replaces the control device 3 with the control device 3B. The other points are the same configuration.

  The control device 3B includes a speed signal calculator 4, an integrator 5, a speed reference rate circuit 6, a speed control circuit 7, a torque limiter 8, a di / dt circuit 9, a current reference circuit 10, and a current detection. Circuit 11, current control circuit 12, voltage reference circuit 13, PWM circuit 14, acceleration / deceleration rate setter 16, constant speed deviation detector 22, torque limit setter 23, and di / dt setter 24 A multiplier 25, an adder AD1, a differentiator DF1, a gain circuit G1, G31, a holding circuit HO31, a NOT circuit NO31, an OR circuit OR31, subtractors SU1, SU2, SU31, and a selector. SW31A, SW31B, SW32 and a zero hold circuit ZH31 are provided.

  Next, the operation at the initial stage of the operation start of the control device 3B will be described.

  First, in the initial stage, selectors SW31B and SW32 are inserted. On the other hand, the selector SW31A is turned off.

  The di / dt setting unit 24 is set with an initial value of the rate of change of the di / dt circuit 9. The di / dt setting unit 24 outputs the initial value of the set change rate to the OR circuit OR31 via the selector SW31B. The di / dt setting device 24 outputs an initial value of the set change rate to the accumulator 25.

  The OR circuit OR31 has no input from the integrator 25 because the selector SW31A is cut off. Accordingly, the OR circuit OR31 outputs the initial value of the change rate set in the di / dt setting device 24 to the di / dt circuit 9 as the signal LMT_DIDT. Thereby, the di / dt circuit 9 receives the initial value of the change rate set in the di / dt setter 24 by the signal LMT_DIDT. The di / dt circuit 9 operates using the received signal LMT_DIDT as a change rate. Accordingly, the di / dt circuit 9 operates with the initial value of the change rate set in the di / dt setter 24.

  When the change rate set in the di / dt setting unit 24 is set in the di / dt circuit 9, an enable signal ENABLE is input. As a result, the selector SW31B is turned off. On the other hand, the selector SW31A is inserted. Accordingly, the change rate set in the di / dt setting unit 24 is input to the di / dt circuit 9 via the integrator 25.

  Next, when the electric motor 2 is driven, the electric motor speed SP_F is input from the integrator 5 to the subtractor SU1.

  The subtractor SU1 calculates a speed deviation SP_DEV between the speed reference SP_R and the motor speed SP_F. The subtractor SU1 outputs the calculated speed deviation SP_DEV to the speed control circuit 7, the zero hold circuit ZH31, and the subtractor SU31.

  The zero hold circuit ZH31 temporarily holds the speed deviation SP_DEV input from the subtracter SU1. The zero hold circuit ZH31 outputs the temporarily held speed deviation SP_DEV to the subtractor SU31 as a speed deviation before one sampling.

  The latest speed deviation SP_DEV is input to the subtractor SU31 from the subtractor SU1. The subtractor SU31 receives the speed deviation SP_DEV before one sampling from the zero hold circuit ZH31. The subtractor SU31 calculates the difference between the latest speed deviation SP_DEV and the speed deviation SP_DEV one sampling before. The subtractor SU31 outputs the calculated difference to the speed deviation constant detection unit 22 and the gain circuit G31.

  The gain circuit G31 multiplies the difference between the speed deviations SP_DEV input from the subtractor SU31 by a gain and outputs the result to the accumulator 25.

  The integrator 25 receives the difference of the speed deviation SP_DEV multiplied by the gain from the gain circuit G31. The accumulator 25 receives the initial value of the change rate from the di / dt setter 24. The accumulator 25 multiplies the difference between the speed deviation SP_DEV multiplied by the gain and the initial value of the change rate.

  The accumulator 25 outputs the calculation result to the di / dt circuit 9 as the signal LMT_DIDT via the OR circuit OR31. Accordingly, the di / dt circuit 9 operates using the signal LMT_DIDT input from the accumulator 25 as a rate of change.

  By this series of processing, the signal LMT_DIDT used as the rate of change in the di / dt circuit 9 increases in proportion to the increase in the speed deviation SP_DEV until the speed deviation SP_DEV becomes constant. The di / dt circuit 9 operates using the latest signal LMT_DIDT, which continues to increase in proportion to the increase in the speed deviation SP_DEV, as the rate of change.

  The speed deviation constant detection unit 22 detects that the speed deviation SP_DEV has become constant based on the difference input from the subtractor SU31. When the constant speed deviation detector 22 detects that the speed deviation SP_DEV has become constant, it outputs a constant speed deviation signal DC to the holding circuit HO31.

  When the constant speed deviation signal DC is input, the holding circuit HO31 holds the signal DCX at “1” and outputs it to the NOT circuit NO31. As a result, the NOT circuit NO31 sets the signal to “0” and outputs it to the selector SW32. When the reset signal RESET is input, the holding circuit HO31 sets the signal DCX to “0”.

  The selector SW32 is turned off when the signal is received as "0" from the NOT circuit NO31. As a result, no signal is input from the accumulator 25 to the OR circuit OR31.

  Therefore, when the speed deviation SP_DEV becomes constant, the di / dt circuit 9 finally operates with the signal LMT_DIDT input from the accumulator 25 as the rate of change.

  According to the present embodiment, until the speed deviation SP_DEV becomes constant, the rate of change set in the di / dt setter 24 is proportional to the magnitude of the speed deviation SP_DEV, and is supplied to the di / dt circuit 9 as the signal LMT_DIDT. Entered. The di / dt circuit 9 applies a signal LMT_DIDT proportional to the magnitude of the speed deviation SP_DEV as the rate of change.

  Thereby, when the acceleration / deceleration time of the electric motor 2 to the speed reference SP_R is shortened by changing the load of the electric motor 2, the time during which the acceleration / deceleration torque TCMP decreases can be shortened. Thereby, the timing when the acceleration / deceleration torque TCMP becomes zero can be optimized.

  Therefore, the motor drive system 50B can suppress speed overshoot and speed offset when acceleration / deceleration is completed.

(Fourth embodiment)
FIG. 5 is a configuration diagram showing a configuration of an electric motor drive system 50C according to the fourth embodiment of the present invention.

  In the electric motor drive system 50 according to the first embodiment shown in FIG. 1, the electric motor drive system 50C replaces the control device 3 with the control device 3C. The other points are the same configuration.

  The control device 3C includes a speed signal calculator 4, an integrator 5, a speed reference rate circuit 6, a speed control circuit 7, a torque limiter 8, a di / dt circuit 9, a current reference circuit 10, and a current detection. A circuit 11, a current control circuit 12, a voltage reference circuit 13, a PWM circuit 14, an acceleration / deceleration rate setting device 16, a torque limit setting device 23, a di / dt setting device 24, and a speed deviation setting device 26. , Comparator 27, adder AD1, differentiator DF1, gain circuit G1, holding circuit HO41, OR circuit OR41, subtractors SU1, SU2, SU41, selectors SW41A, SW41B, and setting device VL41. And.

  Next, an operation at an initial stage of operation start of the control device 3C will be described.

  First, in the initial stage, the selector SW41B is inserted. On the other hand, the selector SW41A is turned off.

  The differentiator DF1 differentiates the speed reference SP_R input from the speed reference rate circuit 6. The differentiator DF1 outputs the differentiated calculation result to the gain circuit G1.

  The gain circuit G1 calculates the acceleration / deceleration torque TCMP by multiplying the calculation result input from the differentiator DF1 by a gain. The acceleration / deceleration torque TCMP is an ideal torque of the electric motor 2. The gain circuit G1 outputs the calculated acceleration / deceleration torque TCMP to the OR circuit OR41 via the selector SW41B.

  Since the selector SW41A is cut off, the OR circuit OR41 does not receive an input from the setter VL41. Therefore, the OR circuit OR41 outputs the acceleration / deceleration torque TCMP output from the gain circuit G1 to the adder AD1 as the acceleration / deceleration torque TCMPA.

  Next, the operation of the control device 3 after starting to drive the electric motor 2 will be described.

  When the motor 2 is driven, the motor speed SP_F is input from the integrator 5 to the subtractor SU41.

  The subtractor SU41 receives the external speed reference SP_REF1. The subtractor SU41 calculates a speed deviation from the motor speed SP_F input from the integrator 5 and the external speed reference SP_REF1. The subtractor SU41 outputs the calculated speed deviation to the comparator 27.

  The speed deviation setter 26 is set with a set value SP_DEV_SET for comparison by the comparator 27. The speed deviation setter 26 outputs the set value SP_DEV_SET to the comparator 27.

  The comparator 27 receives the set value SP_DEV_SET from the speed deviation setter 26. The comparator 27 receives the speed deviation from the subtractor SU41. The comparator 27 outputs a signal CMP to the holding circuit HO41 when the speed deviation from the subtractor SU41 becomes equal to or less than the set value SP_DEV_SET.

  When the signal CMP is input from the comparator 27, the holding circuit HO41 holds the signal CMPX at “1” and outputs it to the selectors SW41A and SW41B. When the reset signal RESET is input, the holding circuit HO41 sets the signal CMPX to “0”.

  The selector SW41B is turned off when the signal CMPX is received as “1”. As a result, the acceleration / deceleration torque TCMP from the gain circuit G1 is not input to the OR circuit OR41.

  The selector SW41A is turned on when the signal CMPX is received as "1". As a result, “0” set in the setting device VL41 is input to the OR circuit OR41.

  When the holding circuit HO41 outputs the signal CMPX as “1”, the OR circuit OR41 receives “0” set in the setting device VL41. On the other hand, the OR circuit OR41 does not receive the acceleration / deceleration torque TCMP from the gain circuit G1. Therefore, the OR circuit OR41 outputs “0” set in the setting device VL41 to the adder AD1 as the acceleration / deceleration torque TCMA.

  According to the present embodiment, the speed control output ASPR_OUT output from the speed control circuit 7 when the difference between the external speed reference SP_REF1 and the motor speed SP_F is equal to or less than the set value SP_DEV_SET set in the speed deviation setting device 26. Acceleration / deceleration torque TCMPA, which is a compensation amount to zero, is made zero.

  As a result, the control device 3 can make the acceleration / deceleration torque TCMPA zero when the speed of the motor 2 reaches the external speed reference SP_REF1 when the motor 2 is accelerated or decelerated at the torque limit.

  Therefore, the motor drive system 50C can suppress the speed overshoot when the acceleration / deceleration is completed by advancing the timing at which the acceleration / deceleration torque TCMC is made zero by the primary delay time of the current control system.

(Fifth embodiment)
FIG. 6 is a configuration diagram showing a configuration of an electric motor drive system 50D according to the fifth embodiment of the present invention.

  The motor drive system 50D has a configuration in which a first-order lag filter 28 is additionally provided between the OR circuit OR41 and the adder AD1 in the control device 3C of the motor drive system 50C according to the fourth embodiment shown in FIG. It is. The other points are the same configuration.

  The primary delay filter 28 is a filter for simulating the primary delay of the current control system. The first-order lag filter 28 approximates the operation in which the acceleration / deceleration torque TCMPA output from the OR circuit OR41 becomes “0” to the first-order lag of the current control system.

  According to the present embodiment, in addition to the operational effects of the fourth embodiment, the following operational effects can be obtained.

  By adding a first-order lag filter 28 that simulates the current control system to the configuration that outputs the acceleration / deceleration torque TCMPA, the operation in which the acceleration / deceleration torque TCMC becomes zero can be approximated to the first-order lag of the current control system.

  Therefore, the electric motor drive system 50D can optimize the timing for zeroing the acceleration / deceleration torque TCMPA. Therefore, the electric motor drive system 50D can suppress speed overshoot and speed offset when acceleration / deceleration is completed.

(Sixth embodiment)
FIG. 7 is a configuration diagram showing a configuration of an electric motor drive system 50E according to the sixth embodiment of the present invention.

  The motor drive system 50E includes a comparator 29 and a setter VL51 in place of the speed control circuit 7E instead of the speed control circuit 7E in the control device 3D of the motor drive system 50D according to the fifth embodiment shown in FIG. This is a configuration provided. The other points are the same configuration.

  The comparator 29 receives the acceleration / deceleration torque TCMPA from the primary delay filter 28. The comparator 29 compares the received acceleration / deceleration torque TCMPA with “0” set in the setting unit VL51. If the acceleration / deceleration torque TCMPA is not “0”, the comparator 29 outputs an enable signal ASPR_ENABLE to the speed control circuit 7E.

  The speed control circuit 7E has a configuration in which a function of “operate while receiving the permission signal ASPR_ENABLE” is added to the speed control circuit 7 according to the first embodiment.

  The speed control circuit 7E operates while receiving the permission signal ASPR_ENABLE from the comparator 29. On the other hand, the speed control circuit 7E stops when it does not receive the permission signal ASPR_ENABLE from the comparator 29. At this time, the speed control circuit 7E does not output the speed control output ASPR_OUT.

  Therefore, when the acceleration / deceleration torque TCMPA is not “0”, the torque limiter 8 receives a signal obtained by adding the acceleration / deceleration torque TCMPA to the speed control output ASPR_OUT from the adder AD1. On the other hand, when the acceleration / deceleration torque TCMPA is “0”, the torque limiter 8 receives a signal for only the acceleration / deceleration torque TCMPA. At this time, the control device 3E controls the power converter 1 based on the acceleration / deceleration torque TCMPA.

  According to the present embodiment, in addition to the functions and effects of the fifth embodiment, the following functions and effects can be obtained.

  By detecting that the acceleration / deceleration torque TCMPA obtained by differentiating the speed reference SP_R is output and stopping the operation of the speed control circuit 7E, the torque of the electric motor 2 is the acceleration / deceleration torque TCMP during the acceleration / deceleration of the electric motor 2. Can only be controlled.

  Therefore, the electric motor drive system 50E can accelerate and decelerate the electric motor 2 without depending on the characteristics of the speed controller 7E.

  Note that the present invention is not limited to the above-described embodiment as it is, and can be embodied by modifying the constituent elements without departing from the scope of the invention in the implementation stage. In addition, various inventions can be formed by appropriately combining a plurality of components disclosed in the embodiment. For example, some components may be deleted from all the components shown in the embodiment. Furthermore, constituent elements over different embodiments may be appropriately combined.

1 is a configuration diagram showing a configuration of an electric motor drive system according to a first embodiment of the present invention. The graph which shows the characteristic of the electric motor drive system which concerns on 1st Embodiment. The block diagram which shows the structure of the electric motor drive system which concerns on the 2nd Embodiment of this invention. The block diagram which shows the structure of the electric motor drive system which concerns on the 3rd Embodiment of this invention. The block diagram which shows the structure of the electric motor drive system which concerns on the 4th Embodiment of this invention. The block diagram which shows the structure of the electric motor drive system which concerns on the 5th Embodiment of this invention. The block diagram which shows the structure of the electric motor drive system which concerns on the 6th Embodiment of this invention.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Power converter, 2 ... Electric motor, 3 ... Control apparatus, 4 ... Speed signal calculator, 5 ... Integrator, 6 ... Speed reference rate circuit, 7 ... Speed control circuit, 8 ... Torque limiter, 9 ... di / dt Circuit 10, current reference circuit 12, current control circuit 13 voltage reference circuit 14 PWM circuit 16 acceleration / deceleration rate setting unit 19 acceleration constant detection unit 20 memory circuit 23 torque limit setting 24 ... di / dt setting device, 50 ... motor drive system, AD1 ... adder, CT1, CT2 ... current transformer, DF1, DF11 ... differentiator, G1 ... gain circuit, HO11 ... hold circuit, OR11 ... OR circuit SS, speed detector, SU1, SU2, SU11, subtractor, SW11A, SW11B, selector, ZH11, zero hold circuit.

Claims (2)

Speed reference calculation means for calculating the speed reference according to the rate of change of the speed reference, which is a reference for the speed of the motor,
Speed calculating means for calculating the speed of the electric motor;
Speed deviation calculating means for calculating a deviation between the speed reference calculated by the speed reference calculating means and the speed calculated by the speed calculating means;
Speed control means for outputting a speed control for controlling the speed of the electric motor based on the deviation calculated by the speed deviation calculating means;
Based on the speed reference calculated by the speed reference calculation means, an acceleration / deceleration torque reference calculation means for calculating an acceleration / deceleration torque reference serving as a reference for the acceleration / deceleration torque of the electric motor;
Speed control output compensation means for compensating the acceleration / deceleration torque reference calculated by the acceleration / deceleration torque reference calculation means with the output of the speed control output from the speed control means;
A torque limiter for performing a process of limiting the torque of the electric motor with a limit value to the output of the speed control compensated by the speed control output compensation unit;
Torque reference calculation means for calculating a torque reference that is a reference for the torque of the electric motor using a di / dt change rate based on the output of the speed control processed by the torque limiter;
Control means for controlling the electric motor based on the torque reference calculated by the torque reference calculating means ;
On the basis of the calculated the difference by the speed deviation computing means, upon completion of acceleration and deceleration of the motor, so as to the acceleration and deceleration torque reference is calculated as zero by the acceleration and deceleration torque reference calculating means, the torque reference A power conversion apparatus comprising: di / dt change rate varying means for changing the di / dt change rate of the computing means. The power conversion device according to claim 1;
An electric motor drive system comprising the electric motor .

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