JP2011015587A - Motor control system - Google Patents

Abstract

A motor control system is provided that is capable of both reducing cogging torque and improving motor efficiency.
A main motor control device having a control means for generating a motor drive command, a PWM inverter circuit for supplying a drive voltage to a motor, a data communication means for supplying a motor drive command, and a main motor. Data communication means 7b for receiving a motor drive command from the control device 9, a slave motor control device 10 having a PWM inverter circuit 5b for supplying a drive voltage to the motor, and 3 × M pieces (M is an integer of 2 or more) The motor 11 includes a three-phase main winding wound around a pole and a sub-winding motor 11, and the main winding of the motor 11 is connected to the main motor control device 9. The sub-winding is a sub-motor control device. 10 has a command distributor 4 that provides a phase difference between the motor current supplied to the slave winding and the motor current supplied to the slave winding. Driving the motor 11.
[Selection] Figure 1

Description

  The present invention relates to a motor control device that efficiently drives one motor by a plurality of inverter circuits.

  In order to drive a motor with a high output, a motor control device equipped with a power device capable of flowing a large current is required. However, a power device that supports a large current is particularly expensive and has a large loss. It is necessary to increase the size of the cooling device. Moreover, in order to reduce switching loss and suppress heat generation, the carrier frequency must be set low, and there is a problem that torque ripple increases.

  Thus, as a method for driving a high-output motor, a multiple inverter system using a plurality of low-output inverter circuits has been proposed (see, for example, Patent Document 1).

  FIG. 5 is a block diagram showing a system configuration when two inverter circuits are used. It comprises a main motor control device that receives a command from a host and a slave motor control device that receives a command from the main motor control device. When receiving a command from the host, the main motor control device generates a torque command based on the motor position information detected by a sensor attached to the rotor and the command from the host. The generated torque command is output to the inverter circuit, and a drive command is issued to the slave motor inverter circuit. The motor is configured to generate torque by PWM drive in the master and slave inverter circuits.

  Since these high-power motors are often directly connected to equipment, reduction of cogging torque and torque ripple is required more than ever. To solve this problem, a motor configuration has been proposed in which the least common multiple of the number of magnet magnet poles and salient pole magnetic poles is increased (see, for example, Patent Document 2).

  Further, there has been proposed a method of reducing iron loss by shifting the motor driving current between inverters by 180 degrees to reduce the ripple of the composite magnetic flux by the multiple inverter method (see, for example, Patent Document 3).

JP 62-44063 A JP-A-62-110468 JP-A-6-197593

  However, the motor configuration example of Patent Document 2 is an example in which the number of poles of the rotor magnet is 14, the number of salient pole poles of the stator is 12, and the least common multiple is 84. In this combination, the U-phase windings are composed of two adjacent sets and two sets on the opposite side of 180 degrees, for a total of four sets. At this time, each counter electromotive force generated by the adjacent windings UA and UB has a phase difference as shown in FIG. 6, and the U-phase counter electromotive force is a combination of UA and UB.

  Since the output of the synthesized counter electromotive force becomes smaller than the sum of the peak values of the respective counter electromotive forces, the motor torque is reduced and the motor efficiency is lowered, so that another problem remains.

  On the other hand, in the method of Patent Document 3, the ripple of the composite magnetic flux is reduced by shifting the phase of the motor current between the inverters by 180 degrees as shown in FIG. However, the ripple reduction of the composite magnetic flux is effective mainly at the yoke portion which is the outer peripheral portion of the motor stator, but there is a problem that the ripple of the pole salient magnetic pole portion to be wound is not reduced and the cogging torque cannot be reduced.

  The present invention solves the above-described conventional problems, and achieves both reduction of cogging torque and improvement of motor efficiency in a motor control system having a multiple inverter configuration in which one motor is driven using a plurality of motor control devices. An object of the present invention is to provide a motor control system that can be used.

  In order to solve the above problem, a motor control system according to claim 1 is a motor control system having a multiple inverter configuration in which a single motor is driven using a plurality of motor control devices. A main motor control device having control means for generating a command, a PWM inverter circuit for supplying a drive voltage to the motor according to the motor drive command, a data communication means for supplying a motor drive command to another motor control device, Data communication means for receiving a motor drive command from the motor control device, a slave motor control device having a PWM inverter circuit for supplying a drive voltage to the motor in accordance with the motor drive command received from the main motor control device, and 3 × M ( M is an integer of 2 or more) salient poles, and three-phase main and sub-windings wound around the salient poles independently. And a main winding of the motor is connected to the main motor control device, the sub winding is connected to the sub motor control device, and the main motor control device supplies the main winding. And a command distributor for providing a phase difference in the motor current supplied to the secondary winding with respect to the motor current to be driven, and one motor is driven by the motor drive command.

  Further, in the motor control system according to claim 2, the command distributor has a 360 / (3 × M) degree order between the motor current supplied to the main winding and the motor current supplied to the slave winding. Provide a phase difference.

  Further, in the motor control system according to claim 3, the number of the main motor control devices and the sub motor control devices is N (N is an integer of 2 or more), and the number of magnet poles of the motor is 2 × P (P is (Integer), the number of salient poles is S (S is a multiple of 3 × N), and the motor is configured by a combination in which the least common multiple of P and S is P × S.

  According to the motor control system of the first aspect, a large capacity motor can be efficiently driven using a plurality of small capacity inverters. By using a small-capacity inverter, the carrier frequency can be increased and torque ripple can be reduced.

  In addition, according to the motor control system of the second aspect, the counter electromotive force and the current phase of each motor can be matched, so that the motor can be driven more efficiently.

  Furthermore, according to the motor control system of the third aspect, the cogging torque of the motor can be reduced.

  Therefore, it is possible to provide a motor control system that realizes reduction of cogging torque and torque ripple and improvement of efficiency.

1 is a block diagram of a motor control system in Embodiment 1 of the present invention. Structural diagram of the motor used in the multiple inverter of Example 1 Winding diagram of motor used in multiple inverter of embodiment 1 Explanatory drawing of the back electromotive force and current waveform of the motor of Example 1. Block diagram of motor control system in conventional example Illustration of electromotive force and current waveform in conventional motor Other explanatory views of electromotive force and current waveform in the conventional motor

Example 1
A motor control system according to the present invention will be described with reference to FIGS.

  1 is a block diagram of a motor control system when two motor control devices are used to drive one motor, FIG. 2 is a structural diagram of the motor, FIG. 3 is a winding connection diagram of the motor, and FIG. The back electromotive force and the current waveform diagram are shown. The role of each block will be described below.

  In FIG. 1, 1 is a controller that outputs a command for operating a motor, 11 is a multi-inverter motor wound so that two motor control devices can be independently connected, and 9 and 9b are controllers 1 Is a motor control device that drives the motor 11 based on a command from the main motor control device and a sub motor control device, respectively.

  The main motor control device 9 includes a control unit 8, a command distributor 4, a data communication unit 7a, and a PWM inverter circuit 5a.

  The control means 8 includes a position / speed controller 2, a voltage generator 3, and a rotor position detector 6, and an operation command 31 is input from the controller 1 to the position / speed controller 2. The operation command 31 is a position command, a speed command, or a torque command.

  In the case of a position command, pulse signal input is often used, and the motor is rotated by an angle corresponding to the number of input pulses. In the case of a speed command or torque command, analog signal input is often used, and a speed command or torque command corresponding to the applied analog voltage is input to the position / speed controller. Recently, there are many cases where position commands, speed commands, and torque commands are given using a communication function.

  The rotor position detector 6 detects rotor information 40 from an encoder 12 attached to the rotor of the motor 11. The rotor information 40 may be received directly from the encoder 12 such as a two-phase pulse signal or sine wave signal, or may be received as serial data after being processed in the encoder.

  In the case of a two-phase pulse signal, the number of pulses output when the rotor makes one revolution is set in advance. By counting this number of pulses with the rotor position detector 6, the current rotation state of the rotor is determined. To detect. In the case of a two-phase sine wave, the rotor position detector 6 detects the rotational state of the rotor by converting the two-phase sine wave signal into an angle signal by inverse triangular transformation.

  In the case of serial data, the rotor position detector can receive not only the rotor information but also the internal information of the encoder such as error information as serial data, and the serial signal can be wired with a total of four power supplies and signals. In many cases, serial data methods are used.

  Rotor information detected by the rotor position detector 6 is calculated into rotor position information and rotor rotational speed information, and is output as position / speed information 36 and rotor position information 35.

  The position / speed controller 2 uses the input position / speed / torque command and the position / speed information 36 detected by the rotor position detector 6 so as to be equal to the command value by proportional / integral control or the like. And output as a torque command value 32.

  The voltage command generator 3 calculates the magnitude and phase of the voltage applied to the three-phase winding of the motor from the torque command value 32 and the rotor position information 35 and outputs a voltage command value 33. The above is the operation of the control means 8.

  The command distributor 4 determines the magnitude and phase of the voltage applied to the motor 11 by the main motor control device 9 and the sub motor control device 10 for the voltage command 33, and the main motor voltage command value 34 is used for the main motor control device. Is output to the PWM inverter circuit 5a, and the control information 37 to the slave motor is output to the data communication means A.

  The data communication means A7a serves to transmit control information 37 to the slave motor to the slave motor control device. Data communication by serial communication is generally used, and the data communication means A7a converts the control information 37 to the slave motor into serial data and transmits it as data communication information 38 to the data communication means B7b.

  The data communication means B7b receives the data communication information 38 from the main motor control device 9, converts it from serial to parallel data, and outputs it to the PWM inverter circuit 5b as the voltage command value 39 of the slave motor control device 10.

  The PWM inverter circuits 5a and 5b have a three-phase full bridge inverter circuit configuration, and are composed of six power devices. Based on each voltage command value, a voltage by PWM control is applied to each motor line of the main motor line 14 and the sub motor line 13.

  The above is the description of the block diagram of the motor control system. Next, the structure of the motor 11 and the winding method will be described with reference to FIGS.

  FIG. 2 shows an example of a motor structure when driven by two motor control devices. The number of poles of the rotor magnet is 10 and the number of salient poles of the stator is 12. A stator 15 that generates a salient pole by winding, a rotor 16 that is a rotating portion of the motor, a magnet that is arranged on the outer periphery or inside of the rotor, and windings 17a, 17b, 18a, and 18b (U-phase Only windings are shown).

  A method for connecting the motor 11 to the two motor control devices 9 and 10 with independent windings will be described below.

  Winding is concentrated on one salient pole, which is referred to as winding 17a. A coil 17b is a coil wound on the opposite salient pole magnetic pole facing the coil 17a, and the coil 17a and the coil 17b are connected. Since the magnetic pole SN of the magnet 19 facing the salient pole is opposite, the windings are connected so that the winding directions are opposite as shown in FIG. 2, and the UA-phase winding is formed from UA + to UA−. Next to the winding 17a, the winding 18a is wound in a reverse winding with respect to the winding 17a, and the winding 18b is wound in a reverse winding with respect to the winding 17b on the opposite salient pole facing the winding 18a. The winding 18a and the winding 18b are connected to form a UB + to UB− UB-phase winding.

  Similarly, the VA phase winding is wound next to the UB phase, the VB phase winding is wound next to the VA phase, the WA phase winding is wound next to the VB phase, and the WB phase winding is wound next to the WA phase. 3 combination of UA phase, VA phase and WA phase as shown in Fig. 3 and B combination of UB phase, VB phase and WB phase. Configure the winding.

  The above is the structure of the motor 11 and the winding method. Next, a connection and energization method between the motor control device and the motor will be described with reference to FIG.

  When the motor 11 configured as shown in FIGS. 2 and 3 is driven, the back electromotive forces 50 and 51 generated in the U phase of the A connection and the B connection are as shown by UA and UB in FIG. Become. Since the structure of the motor 11 has 12 salient poles, a phase difference of 360/12 = 30 degrees in electrical angle occurs.

  The V-phase counter electromotive forces VA and VB are 120 degrees out of phase with each other from the U-phase counter electromotive forces UA50 and UB51, and VA and VB are 30 degrees out of phase with each other. The same applies to the W-phase back electromotive force.

  For such a motor 11, the A group connection (hereinafter referred to as the main winding) of the motor 11 is connected to the main motor control device 9, and the B combination connection (hereinafter referred to as the sub winding) is connected to the sub motor control device 10. Connecting. Here, the command distributor 4 in FIG. 1 sets the voltage command value 34 of the main motor control device 9 so that the U-phase current IUA 53 of the main winding is in phase with the counter electromotive force UA 50, and the voltage of the sub motor control device 10. The command value 39 distributes the voltage command so that the U-phase current IUB 54 of the secondary winding is in phase with the counter electromotive force UB 51.

  The back electromotive force phase information can be obtained by detecting the rotor information 40 by the rotor position detector 6 because the positions of the rotor 16 and the encoder 12 are determined in advance. Although only the U-phase back electromotive force and the phase current are shown in FIG. 4, the V and W phases are 120 ° and 240 ° out of phase with respect to the U phase, respectively, and are easily controlled. Is possible.

  As described above, by setting the phase difference between the motor current of the main motor control device 9 and the motor current of the sub motor control device 10 to 360 / (3 × M) degrees (3 × M is the number of salient poles), Since the counter electromotive force and current phase generated by the main winding can be set to the same phase as the counter electromotive force and current phase generated by the sub winding, respectively, the motor can be driven efficiently.

  Further, although the main motor control device 9 and the main winding are connected, and the sub motor control device 10 and the sub winding are connected, there is no problem even if they are connected in reverse. In that case, the same effect can be obtained as long as the current phase is matched with the phase of the connected back electromotive force.

  The UA-phase motor winding 17a and the UB-phase motor winding 18a are reversely wound from the arrangement of the magnet 19, but may be wound in the same direction to shift the phase of the UB-phase motor current by 180 degrees. By winding in the same direction as described above, the motor can be easily manufactured and the manufacturing cost can be reduced.

  In addition, the command distributor 4 determines the magnitude of the voltage and the phase of the motor current that the main motor control device 9 and the sub motor control device 10 apply the voltage command 33 to the motor 11 (main winding and sub winding), respectively. However, the magnitude of the voltage generated by the command distributor 4 and the value of the current phase are assumed to be the same, and the control information 37 is transmitted to the slave motor control device 10. A configuration may be adopted in which the magnitude of the voltage applied to the line and the current phase are determined.

The current phase applied by the slave motor control device 10 may be data preset in a memory in the slave motor control device 10. Alternatively, data set in advance in the memory of the main motor control device 9 and transmitted to the sub motor control device 10 together with the control information 37 for the sub motor may be used.
Also, the smaller the number of salient poles, the more effective the effect. In the example, the motor 11 has two sets of connections, 10 magnets, and 12 salient poles, and the current phase difference between the main motor controller 9 and the sub motor controller 10 is 30 degrees. When no phase difference is provided, the effective rate of each back electromotive force is COS (30/2) = 0.966. On the other hand, when the phase difference is set to 30 degrees, COS (0) = 1, and the efficiency can be improved by about 3.4%. When the number of salient poles is 24, the effective rate of back electromotive force is 0.991, and the effect of providing a phase difference is reduced. Further, when the number of salient poles is 6, the effective rate of back electromotive force is 0.866, so that there is an improvement effect of about 13.4%.

  Further, the number of motor control devices is N (N is an integer of 2 or more), the number of magnet poles is 2 × P (P is an integer), and the number of salient poles is S (S is a multiple of 3 × N). And a motor structure in which the least common multiple of S is P × S, the above-described effects can be obtained, and cogging can be further reduced.

  The motor control system of the present invention is particularly effective for devices that require high output, high efficiency, and low torque ripple, and is also used for FA motors used in industrial equipment, drive motors for electric vehicles, etc. Useful.

DESCRIPTION OF SYMBOLS 1 Controller 2 Position / speed controller 3, 3a Voltage command generator 4 Command distributor 5a, 5b PWM inverter circuit 6 Rotor position detector 7a, 7b Data communication means A, Data communication means B
8, 8a Control means 9, 9a Main motor control device 10, 10a Sub motor control device 11, 11a Motor 12 Encoder 13 Sub motor wire 14 Main motor wire 15 Stator 16 Rotor 17a, 17b UA phase winding 18a, 18b UB phase Winding 19 Magnet 31 Position / speed command value 32 Torque command value 33 Voltage command value 34, 41 Voltage command value of main motor 35 Rotor position information 36 Position / speed information 37, 41 Control information to slave motor 38 Data communication information 39 Voltage command value of slave motor 40 Rotor information 50, 50a, 50b Back electromotive force of UA winding 51, 51a, 51b Back electromotive force of UB winding 52, 52a Back electromotive force combining UA winding and UB winding 53, 53b Motor current of UA phase 54, 54b Motor current of UB phase 55 Motor current of U phase

Claims (3)

In a motor control system of a multiple inverter configuration that drives a single motor using a plurality of motor control devices,
Main means having a control means for generating a motor drive command from the inputted command, a PWM inverter circuit for supplying a drive voltage to the motor by the motor drive command, and a data communication means for supplying the motor drive command to another motor control device A motor control device;
Data communication means for receiving a motor drive command from the main motor control device, a slave motor control device having a PWM inverter circuit for supplying a drive voltage to the motor in accordance with the motor drive command received from the main motor control device,
3 × M (M is an integer equal to or greater than 2) salient poles, and a motor in which the three-phase main and slave windings wound around the salient poles are independently configured,
The main winding of the motor is connected to the main motor control device, the slave winding is connected to the slave motor control device,
The main motor control device has a command distributor for providing a phase difference between the motor current supplied to the main winding and the motor current supplied to the sub winding, and one motor is controlled by the motor drive command. A motor control system characterized by driving.   2. The motor control system according to claim 1, wherein the command distributor provides a phase difference of 360 / (3 × M) degrees between the motor current supplied to the main winding and the motor current supplied to the secondary winding.   The number of the main motor control devices and the sub motor control devices is N (N is an integer of 2 or more), the number of magnet poles of the motor is 2 × P (P is an integer), and the number of salient poles is S (S is 3). The motor control system according to claim 1, wherein the motor is configured by a combination in which a least common multiple of P and S is P × S.

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