JP2010088176A - Drive unit of three-phase motor, and drive control device equipped with same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reduce an offset current of a current fed to each phase of a three-phase motor. <P>SOLUTION: In an offset current detection mode, each phase drive part 11u, 11v and 11w sequentially and individually drives each phase 31u, 31v and 31w of the three-phase motor 30 at the current according to a current command value 0. In this time, a current value of a neutral point N of the three-phase motor 30 is detected by a neutral point current detector 27, and stored in an offset current storage part 21 as an offset current value of each phase. In a normal operation mode, the offset current value of each phase stored in the offset current storage part 21 is sent to a corrector 19 of each drive part 11u, 11v and 11w, and the current command value is corrected by the corrector 19. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a drive device that supplies a current corresponding to a current command value for each phase for a three-phase motor to each phase, and a drive control device including the drive device.

  As a drive device for a three-phase linear motor, for example, there is one disclosed in Patent Document 1 below.

  In the driving device disclosed in Patent Document 1, current values supplied to the U phase, V phase, and W phase of the three-phase linear motor are detected, and supplied to each phase based on the current detection value of each phase. The command value of the current to be controlled is controlled. That is, this drive device feedback controls the current values supplied to the U-phase, V-phase, and W-phase of the three-phase linear motor to reduce the error with respect to the current command value.

JP 2003-235292 JP

  The error with respect to the current command value includes a gain error and an offset current. When the current value is feedback-controlled as in the prior art, the current value is stable with respect to the gain error at a constant ratio, and therefore this gain error can be dealt with. However, in this case, the error caused by the offset current is affected by the dynamic range with the maximum current, so it is difficult to reduce the error caused by the offset current to a small value. There is a problem that it is not possible. In particular, when moving the mover of a three-phase linear motor at a constant speed, the current value supplied to each phase is a value close to 0. Therefore, if there is an offset current, a current that accurately corresponds to the command value for each phase. Cannot be supplied, causing a thrust ripple component.

  An object of the present invention is to provide a drive device for a three-phase motor and a drive control device provided with the drive device that can suppress the influence of an offset current, paying attention to such problems of the prior art.

A driving device for a three-phase motor according to an invention for solving the above-mentioned problems
A current detector that detects the current value at the neutral point of the three-phase motor;
For each phase, when the current command value for one of the three phases is zero and the one phase is driven independently, the offset current value for each phase detected by the current detector, or three phases For each combination of the two phases, the current command value for the two phases constituting the set is zero, and when only the two phases are driven, for each phase obtained from the current value detected by the current detector Offset current storage means for storing the offset current value of
A corrector that corrects the current command value for each phase so that the offset current of each phase is canceled using the offset current value for each phase stored in the offset current storage means;
It is characterized by having.

Further, a drive control device for a three-phase motor for solving the above problems is
The drive device, and a control device for controlling the operation of the drive device,
The control device includes:
Current command value generating means for generating the current command value for each phase;
Drive command generation means for generating the drive command for each phase;
For each phase, the current command value generation means generates a zero current command value for one of the three phases, and the drive command generation means causes the current command value generation means to When a zero current command value is output to the output, a drive command for driving the one phase alone is output, and the driving device is caused to output zero from the current command value generating means to the one phase. Offset current detection control means for outputting that the one-phase offset current detection mode is output when a current command value is output, or the current command value for every combination of two phases of three phases. The generating means generates a zero current command value for the two phases forming a set, and the driving command generating means outputs a zero current command value for the two phases from the current command value generating means. Drive only the two phases when A drive command is output, and when the zero current command value is output for the two phases from the current command value generating means to the drive device, the two-phase offset current detection mode is indicated. Offset current detection control means for outputting
It is characterized by having.

  According to the present invention, the offset current value for each phase is measured, and the current command value for each phase is corrected based on the measured offset current value for each phase. Can be suppressed.

  Hereinafter, an embodiment of a drive control device for a three-phase motor according to the present invention will be described with reference to FIG.

  The three-phase motor that is driven and controlled by the drive control device of the present embodiment is a three-phase linear motor 30. The three-phase linear motor 30 includes a load coil that forms a mover or a stator, and a permanent magnet (not shown) that forms a stator or a mover. The load coils include a U-phase coil 31u, a V-phase coil 31v, and a W-phase coil 31w. The terminals on the side opposite to the drive side of each phase coil 31u, 31v, 31w are connected to each other to form a neutral point. This neutral point is connected to the ground of the power supply circuit 50.

  The drive control device for driving and controlling the above three-phase linear motor 30 outputs a current command indicating the value of the current supplied to each phase of the three-phase linear motor 30 and a drive command indicating ON / OFF of each phase. The apparatus 40 and the drive apparatus 10 which adjusts the electric current from the power supply circuit 50 to the electric current according to the electric current command for every phase and the electric driving command, and supplies it to each phase of the three-phase linear motor 30 are provided.

  Functionally, the control device 40 generates a current command generation unit 41 that generates a current command indicating the value of the current supplied to each phase of the three-phase linear motor 30, and a drive command that indicates ON / OFF of each phase. And an offset current detection control unit 43 that outputs an offset current detection mode signal indicating that an offset current of any phase of the three-phase linear motor 30 is detected.

  The control device 40 is a computer in terms of hardware, and includes a CPU that executes various arithmetic processes, a ROM that stores programs and data executed by the CPU in advance, and a RAM that serves as a work area for the CPU. And an input device such as a keyboard, and an interface for transmitting and receiving signals between the driving device 10. Each of the aforementioned functional units 41, 42, and 43 of the control device 10 functions when the CPU executes a program stored in a ROM or the like.

  The drive device 10 supplies current to the U-phase drive unit 11u that supplies current to the U-phase coil 31u of the three-phase linear motor 30, the V-phase drive unit 11v that supplies current to the V-phase coil 31v, and the W-phase coil 31w. The supplied W-phase drive unit 11w, the neutral point current detector 27 that detects the current at the neutral point N of the three-phase linear motor 30, and the current value amplifier that amplifies the output from the neutral point current detector 27 28, an A / D converter 29 that converts the analog output from the current value amplifier 28 into a digital signal, and an offset current storage unit 21 that stores the current value detected by the neutral point current detector 27. ing.

  The drive units 11u, 11v, and 11w for each phase are the corrector 19 that corrects the current command value indicated by the current command from the control device 40 with the offset current value from the offset current storage unit 21, and the corrector 19. A D / A converter 12 that converts the corrected digital signal current command into an analog signal; an error calculator 13 that calculates an error between the current command value indicated by the current command and the actually detected current value; A drive circuit 14 that adjusts the current value of the current from the power supply circuit 50 according to the output from the calculator 13, and supplies the adjusted current to the corresponding phase coil of the three-phase linear motor 30. A phase current detector 17 that detects the current value of the current supplied to the corresponding phase coil; and an amplifier 18 that amplifies the output from the phase current detector 17 and outputs the amplified output to the error calculator 13. That.

  The drive circuit 14 corresponds to a PWM (Pulse Width Modulation) control circuit 15 that changes the duty cycle of the pulse width according to the level of the input signal, and the current from the power supply circuit 50 according to the output from the PWM control circuit 15. And an output stage circuit 16 that outputs an ON drive command from the control device 40 in place of the current having the current value. In this embodiment, the PWM control circuit 15 with high efficiency and low heat generation is used for current value control, but another control circuit such as a linear control circuit may be used instead.

  The offset current storage unit 21 is a microcomputer. The CPU 22 executes various arithmetic processes, the ROM 23 stores a program executed by the CPU 22, various data, and the like. It has a RAM 24 for storing current values, and interfaces 25 and 26 with the outside.

Here, temporarily, a current command value of command value 0 is output from the current command generation unit 41 of the control device 40 to the drive units 11u, 11v, and 11w of each phase, and the drive command generation unit 42 of the control device 40 is output. , An ON drive command is output, and offset currents I _U0 , I _V0 , and I _W0 flow through the phase coils 31u, 31v, and 31w, respectively.

In this case, a current I _n0 represented by the following formula flows through the neutral point N. Here, ± of the current is (+) in the direction in which the current is directed to each phase coil 31u, 31v, 31w.

I _n0 = − (I _U0 + I _V0 + I _W0 )
Thus, when the offset currents I _U0 , I _V0 , and I _W0 flow through the phase coils 31u, 31v, and 31w, the amount corresponding to the difference between the offset currents I _U0 , I _V0 , and I _{W0 is obtained} . A thrust ripple of the magnetic pole pitch component of the motor is generated.

By the way, as described above, the offset currents I _U0 , I _V0 , and I _W0 for each phase cannot be grasped from the current In ₀ that flows through the neutral point N when all three phases are driven.

Therefore, in the present embodiment, as will be described below, in response to an instruction from the control device 40, each phase is driven independently for all three phases, and the current value at the neutral point N at that time is neutral. By measuring with the point current detector 27, the offset currents I _U0 , I _V0 , I _W0 for each phase are grasped.

  When the offset current detection control unit 43 of the control device 40 receives an offset current detection instruction from the outside or when a predetermined period has elapsed, the current command generation unit 41, the drive command generation unit 42, and the offset current storage unit 21. In contrast, an offset current detection mode signal for the U phase, an offset current detection mode signal for the V phase, and an offset current detection mode signal for the W phase are sequentially output.

  Upon receiving the offset current detection mode signal related to the U phase, the current command generation unit 41 outputs a current command having a command value 0 to the U phase drive unit 11u. Further, when receiving the offset current detection mode signal related to the U phase, the drive command generation unit 42 outputs an ON drive command to the U phase drive unit 11u, and sends it to the other V phase and W phase drive units 11v and 11w. On the other hand, an OFF drive signal is output.

  That is, when the offset current detection control unit 43 of the control device 40 outputs the offset current detection mode signal related to the U phase, only the U phase drive unit 11u among the drive units 11u, 11v, and 11w of the drive device 10 is used alone. The current corresponding to the current command value 0 is supplied from the U-phase drive unit 11u to the U-phase 31u of the three-phase linear motor 30.

In the offset current detection mode related to the U phase, the current flowing through the neutral point N is the U phase offset current I _U0 . The current flowing through the neutral point N, that is, the U-phase offset current I _U0 is detected as -I _U0 by the neutral point current detector 27, and the offset current storage unit via the amplifier 28 and the A / D converter 29. 21.

At this time, since the CPU 22 of the offset current storage unit 21 has received the offset current detection mode signal related to the U phase from the offset current detection control unit 43 of the control device 40, it is sent from the neutral point current detector 27. The current value -I _U0 is recognized as an offset current value of the U phase, and this current value -I _U0 is associated with the U phase and stored in the RAM 24.

When the offset current detection control unit 43 of the control device 40 outputs the offset current detection mode signal for the V phase and the offset current detection mode signal for the W phase, the current command generation unit 41 and the drive command generation unit are the same as above. 42. The phase driving units 11v and 11w are operated, and the offset current values -I _V0 and -I _W0 of the V phase and the W phase are stored in the RAM 24 of the offset current storage unit 21.

  When the three-phase linear motor 30 is normally operated, the offset current detection control unit 43 outputs a normal operation mode signal to the current command generation unit 41, the drive command generation unit 42, and the offset current storage unit 21.

At this time, the current command generation unit 41 outputs a current command indicating a predetermined command value to each phase drive unit 11u, 11v, 11w, and the drive command generation unit 42 outputs each phase drive unit 11u, 11v, against 11 w, and outputs an oN drive command, the offset current storage unit 21, phase driver 11u, 11v, each 11 w, corresponding offset current value -I _U0, -I _V0, and outputs the -I _W0 .

In each phase drive unit 11u, 11v, 11w, the corrector 19 receives the current command and the offset current value −I ₀ from the control device 40, and adds the offset current value −I ₀ to the command value indicated by the current command value. The value after the addition is output to the D / A converter 12 as a new current command value.

  In the following, the current corresponding to the new current command value is supplied from the drive circuit 14 to the corresponding phase coil of the three-phase linear motor 30 as in the case described above.

As a result, in the present embodiment, in the normal operation mode, the offset current for each phase is canceled by the offset current values −I _U0 , −I _V0 , and −I _W0 output from the offset current storage unit 21, and the thrust Ripple can be suppressed.

  In particular, even when the current value supplied to each phase is set to a value close to 0 in order to move the mover of the three-phase linear motor 30 at a constant speed, in this embodiment, the offset current of each phase can be eliminated. A current corresponding to the command value can be supplied to each phase accurately, and fluctuations in the speed of the mover due to thrust ripple can be suppressed, that is, accurate constant-velocity movement of the mover can be realized.

  In the present embodiment, the offset current detection control unit 43 of the control device 40 outputs an offset current detection mode signal when receiving an offset current detection instruction from the outside or when a predetermined period has elapsed. Each time this offset current detection mode signal is output, a new offset current value is stored in the offset current storage unit 21. For this reason, in this embodiment, it is possible to cope with a change with time of each phase driving unit 11u, 11v, 11w and the like, and a change in offset current accompanying a change in the installation environment of the motor.

  In the present embodiment, when grasping the offset current of each phase, one of the three phases is driven individually, and the current value at the neutral point N at that time is measured, whereby each phase is measured. We know the offset current, but for every combination of the two phases of the three phases, drive the two phases that make up the set, and calculate the offset current of each phase from the current value at the neutral point N at that time It is also possible to grasp.

  In this case, the offset current detection control unit 43 of the control device 40 sends an offset current detection mode signal related to the U and V phases to the current command generation unit 41, the drive command generation unit 42, and the offset current storage unit 21, and V and W. The offset current detection mode signal for the phase and the offset current detection mode signal for the W and U phases are sequentially output.

  When receiving the offset current detection mode signal related to the U and V phases, the current command generating unit 41 outputs a current command having a command value of 0 to the U phase driving unit 11u and the V phase driving unit 11v. Further, when receiving the offset current detection mode signal related to the U and V phases, the drive command generation unit 42 outputs an ON drive command to the U phase drive unit 11u and the phase drive unit 11v, and the remaining W phase drive units For 11w, an OFF drive signal is output.

In the offset current detection mode related to the U and V phases, the current flowing through the neutral point N is a sum of the U phase offset current I _U0 and the V phase offset current I _V0 . This current value is detected by the neutral point current detector 27 and temporarily stored in the RAM 24 of the offset current storage unit 21.

Similarly, in the offset current detection mode for the _V and W phases, the current value of the sum of the V phase offset current I _V0 and the W phase offset current I _W0 is temporarily stored in the RAM 24 of the offset current storage unit 21. In the offset current detection mode stored in the W and U phases, the current value of the current that is the sum of the W phase offset current I _W0 and the U phase offset current I _U0 is temporarily stored in the RAM 24 of the offset current storage unit 21. Remembered.

  The CPU 22 of the offset current storage unit 21 creates a ternary simultaneous equation using the three current values temporarily stored in the RAM 24 as described above, solves the ternary simultaneous equation, and calculates the offset current of each phase. Is stored again in the RAM 24.

  As described above, the offset current of each phase can be grasped without driving only one of the three phases. However, in consideration of the calculation load of the offset current storage unit 21 and the like, it is preferable to grasp the offset current of each phase by driving only one phase alone.

  In addition, when the offset current of the entire three phases is known, either one of the three phases is driven independently to grasp the offset current of each of the two phases, and then the remaining one phase is obtained. You may do it.

1 is a configuration diagram of a three-phase linear motor and a drive control device thereof as one embodiment according to the present invention.

Explanation of symbols

10: drive device, 11u: U-phase drive unit, 11v: V-phase drive unit, 11W: W-phase drive unit, 13: error calculator, 14: drive circuit, 17: phase current detector, 21: offset current storage unit 21, 30: three-phase linear motor, 31u: U-phase coil, 31v: V-phase coil, 31W: W-phase coil, 40: control device, 41: current command generator, 42: drive command generator, 43: offset current Detection control unit, 50: power supply circuit

Claims (4)

In the drive device of the three-phase motor that supplies the current according to the current command value for each phase for the three-phase motor to each phase,
A current detector for detecting a current value at a neutral point of the three-phase motor;
For each phase, when the current command value for one of the three phases is zero and the one phase is driven independently, the offset current value for each phase detected by the current detector, or three phases For each combination of the two phases, the current command value for the two phases constituting the set is zero, and when only the two phases are driven, for each phase obtained from the current value detected by the current detector Offset current storage means for storing the offset current value of
A corrector that corrects the current command value for each phase so that the offset current of each phase is canceled using the offset current value for each phase stored in the offset current storage means;
A drive device for a three-phase motor, comprising: A control device that outputs a current command value and a drive command for each phase for a three-phase motor, and a drive device that supplies a current for each phase according to the current command value and the drive command for each phase from the control device And a three-phase motor drive control device comprising:
The control device includes:
Current command value generating means for generating the current command value for each phase;
Drive command generation means for generating the drive command for each phase;
For each phase, the current command value generation means generates a zero current command value for one of the three phases, and the drive command generation means causes the current command value generation means to When a zero current command value is output to the output, a drive command for driving the one phase alone is output, and the driving device is caused to output zero from the current command value generating means to the one phase. An offset current detection control means for outputting that the one-phase offset current detection mode is output when a current command value is output;
Have
The driving device includes:
A current detector for detecting a current value at a neutral point of the three-phase motor;
An offset current storage means for storing an offset current value for each phase detected by the current detector each time it receives an offset current detection mode for each phase from the offset current detection control means,
A corrector that corrects the current command value for each phase so that the offset current of each phase is canceled using the offset current value for each phase stored in the offset current storage means;
have,
A drive control device for a three-phase motor. A control device that outputs a current command value and a drive command for each phase for a three-phase motor, and a drive device that supplies a current for each phase according to the current command value and the drive command for each phase from the control device And a three-phase motor drive control device comprising:
The control device includes:
Current command value generating means for generating the current command value for each phase;
Drive command generation means for generating the drive command for each phase;
For every combination of two phases of the three phases, the current command value generating means generates a zero current command value for the two phases forming the set, and the drive command generating means When a zero current command value is output from the generating unit to the two phases, a driving command for driving only the two phases is output, and the driving device is configured to output the driving command from the current command value generating unit. An offset current detection control means for outputting that the two-phase offset current detection mode is output when a zero current command value is output for the two phases;
Have
The driving device includes:
A current detector for detecting a current value at a neutral point of the three-phase motor;
Each time it receives from the offset current detection control means that it is the offset current detection mode for each set, it temporarily stores the current value detected by the current detector, and from each current value for each set, each phase Offset current storage means for obtaining an offset current value for each phase and storing the offset current value for each phase;
A corrector that corrects the current command value for each phase so that the offset current of each phase is canceled using the offset current value for each phase stored in the offset current storage means;
have,
A drive control device for a three-phase motor. In the three-phase motor drive control device according to any one of claims 2 and 3,
The offset current detection control means of the control device outputs to the drive device that it is in the offset current detection mode every time a predetermined condition is satisfied.
A drive control device for a three-phase motor.

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