JP2002136199A - Pm motor control method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce a cogging torque without requiring phase adjustments. SOLUTION: A speed control unit 12 for outputting a q-axis command Iq and a d-axis command Id for speed control, a q-axis current control unit 23 for calculating and amplifying a difference between the q-axis torque command and a q-axis detection current and a d-axis current control unit 24 for calculating and amplifying a difference between the d-axis command and a d-axis detection current are provided to control a PM motor 1, based on the q-axis current command and d-axis current command from the current control units 23 and 24. A circuit 13 for setting a d-axis DC brake command (+Id), which is larger than the cogging torque is also provided to add 14 this command (+Id) in order to cancel the cogging torque to a d-axis enhanced field current command from a speed control unit 12. A command of the d-axis current control unit during speed control is added 14 to the d-axis enhanced field current command (+Id) (fixed value). This command is larger than the cogging torque, and therefore the cogging torque can be controlled.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for controlling a PM motor (permanent magnet motor) which can reduce the pulsation of the PM motor.

[0002]

2. Description of the Related Art A PM motor includes a stator having a stator core wound with a winding and a rotor provided with a plurality of permanent magnets. The magnetomotive force distribution of the stator winding has a distribution in which a spatial harmonic is superimposed on a sine wave (fundamental wave), and varies with time in proportion to the stator winding current. The torque acting on the rotor is the angular derivative of the magnetic energy stored in the air cap.

[0003] The attraction force of the magnet is a cogging torque that is large or small depending on the position of the armature. This size and period are PM
It depends on the structure of the motor. When the inertia is small, the cogging torque generates a torque for moving the magnetic pole. When a PM motor with very small inertia is rotated by ASR control (speed control), the magnitude of cogging changes as shown in FIG. 6 due to a change in electrical angle, and this torque disturbs and the ASR system becomes unstable. It becomes.

In the control of a conventional PM motor, as shown in FIG. 4, an ASR controller 12 calculates and amplifies a deviation between a speed command and a speed detected by a speed detector 2 to output a torque command.
The CR control (current control) unit 25 calculates and amplifies the difference between the torque command and the detected current from the current detection unit 15 and outputs a torque current command. The driver unit 28 controls the PM motor based on the torque current command. Controlling.

In the control of the PM motor, if the response speed of the ASR control system is set high, the speed fluctuation becomes small as shown in FIG. 7, but the vibration and noise of the PM motor increase. If the response speed of the ASR control system is set low in order to reduce vibration and noise, rotation unevenness and speed accuracy are reduced as shown in FIG.

Further, as shown in FIG. 5, a cogging torque compensating circuit 26 for taking in the detected speed from the speed detector 2 and outputting a cogging torque canceling signal is provided, and is output from the current control unit 25 to the driver unit 28. There is one in which a cogging torque canceling signal is added to the torque current command so as to cancel the cogging torque. However, when the cogging torque canceling signal is added to the torque command, it is necessary to adjust the phase and the amplitude. If there is a phase error, the control becomes unstable due to the added torque.

SUMMARY OF THE INVENTION The present invention has been made in view of such problems, and an object of the present invention is to provide a method of controlling a PM motor which can reduce vibration and noise without requiring phase adjustment or the like. It is in.

[0008]

A control method of a PM motor according to the present invention calculates and amplifies a deviation between a speed command and a detected speed, outputs a q-axis command and a d-axis command during speed control, and increases the d-axis during braking. A speed control unit for outputting a field current command and a zero q-axis current command; a difference between the q-axis command and the q-axis detection current being input to output a q-axis torque current command;
A current control unit that receives a difference between the axis detection currents and outputs a d-axis current command, and wherein the PM motor control method controls the PM motor based on the q-axis current command and the d-axis current command. D axis that outputs the d-axis enhanced field current command
A C brake command circuit is provided and this d-axis DC
A brake command is a d-axis strengthening field current command of the current control unit, and a DC brake current is supplied to the PM motor to reduce the influence of cogging torque.

The fixed value d-axis strengthening field current command may be a torque command that is equal to or greater than the cogging torque. Further, it is preferable that the fixed d-axis strengthening field current command is added to the d-axis current command output from the speed control unit at all times or only at a low speed to the d-axis current command output from the speed control unit. Good. The d-axis stronger field current command circuit may be constituted by a setting device, and the d-axis stronger field current command having a fixed value may be adjusted.

[0010]

FIG. 1 is a control block diagram of a PM motor according to an embodiment of the present invention. Reference numeral 12 denotes an ASR control unit which arithmetically amplifies a deviation between an ASR-time speed command and a speed detected by the speed detector 2, and outputs a q-axis torque command Iq as shown in FIG. , D-axis current command, and outputs a stronger field current command Id and a q-axis torque command Iq = 0 during DC braking as shown in FIG. 3B.

Reference numeral 13 denotes a fixed value DC brake command (+ I
d: a DC brake command circuit that outputs a stronger field current, and outputs a DC brake command (+ Id) that satisfies the condition of brake command (+ Id)> cogging torque during ASR control as shown in FIG. . Cogging torque is 2
In the case of 3%, the DC brake command (+ Id) to be set is 4
%. This brake command (+ Id) is added to adder 1
4, the brake command Id (ASR
(At the time of control Id = 0).

Reference numeral 16 denotes a q-axis current command unit, and 17 denotes a d-axis current detection unit, each of which is a PM detected by a current detector (not shown).
The q-axis current component and the d-axis current component of the three-phase current of the motor are detected.

Reference numeral 23 denotes an ACR control unit.
The difference between the q-axis current command Iq from the SR control unit 12 and the q-axis detection current from the q-axis current detection unit 16 is arithmetically amplified and a q-axis torque current command is output to the driver unit 28. Also, 2
Reference numeral 4 denotes a d-axis ACR control unit, which is a brake command (+ Id) from an adder 14 that adds a d-axis current command Id (= 0) from the ASR control unit 12 and a DC brake command (+ Id) from the DC brake command circuit 13. ) (Fixed value) and the difference between the d-axis detection current from the d-axis current detection unit 17 are arithmetically amplified and a d-axis torque current command is output to the driver unit 28.

Reference numeral 28 denotes a driver unit, and an ACR control unit 2
Based on the q-axis and d-axis torque current commands from
The M motor 1 is controlled.

With the above configuration, the ASR
At the time of control, the adder 14 outputs D
C brake command (+ Id) is applied to d-axis D of ACR control unit 24
Since the C brake command is issued, the DC brake is applied to the PM motor 1 to suppress the cogging torque.

According to the above embodiment, at the time of ASR control,
Since a constant DC brake current flows through the PM motor, the effect of cogging torque is reduced, and the armature angle changes linearly and the speed detection pulse becomes uniform, as shown in FIG.

In the above description, the adder 14 is used during the ASR control.
From the DC brake command (+
Id) is output as a d-axis DC brake command. However, the same effect can be obtained by monitoring the speed and outputting it at a low speed of the ASR control. In addition, DC brake command (+ I
The setting of d) is a variable value using a setting device or the like.
It is possible to easily correct errors in design values and to cope with PM motors having different specifications.

[0018]

Since the present invention is configured as described above, the following effects can be obtained. (1) The signal for canceling the cogging torque is a strong field current command having a fixed value, and does not require adjustment of phase, amplitude, and the like. (2) It is stable without increasing the ASR response,
Vibration and noise can be reduced. (3) ASR due to provision of strong field current command circuit
Response does not decrease. (4) Cogging torque can be reduced at low cost.

[Brief description of the drawings]

FIG. 1 is a control block diagram of a PM motor according to an embodiment.

FIG. 2 is a graph showing armature angles and speed detection pulses of a PM motor.

FIGS. 3A, 3B, and 3C are graphs showing the relationship between a torque command and a brake command when a stronger field current command is given during ASR control, DC braking, and ASR control, respectively. .

FIG. 4 is a control block diagram of a PM motor for explaining countermeasures against cogging torque in an ASR control system according to a conventional example.

FIG. 5 is a control block diagram of a PM motor that takes measures against cogging torque in an ACR control system according to a conventional example.

FIG. 6 is a graph showing a relationship between an electrical angle and a cogging torque.

FIG. 7 is a graph showing armature angles and speed detection pulses when the gain of the conventional ASR control system is increased.

FIG. 8 is a graph showing armature angles and speed detection pulses when the gain of the conventional ASR control system is reduced.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... PM motor 12 ... ASR control part 13 ... DC brake command circuit for cogging torque measures 23, 24 ... q-axis, d-axis ACR control part

Claims (5)

[Claims] A speed controller for calculating and amplifying a difference between a speed command and a detected speed to output a q-axis command and a d-axis command; A current control unit that outputs a difference between the d-axis command and the d-axis detection current and outputs a d-axis current command, and controls a PM motor based on the q-axis current command and the d-axis current command. In the motor control method, a d-axis strengthening field current command circuit that outputs a fixed-value d-axis current command is provided, and the d-axis strengthening field current command is used as a d-axis current command of the current control unit during speed control. DC to PM motor
A method of controlling a PM motor, comprising: flowing a brake current to reduce the influence of cogging torque. 2. The PM motor control method according to claim 1, wherein the d-axis strengthening field current command having a fixed value is a torque command that is equal to or greater than a cogging torque. 3. The control method for a PM motor according to claim 1, wherein the fixed d-axis strengthening field current is constantly added to a d-axis brake command output from a speed control unit. 4. The control method for a PM motor according to claim 1, wherein the d-axis strengthening field current command having a fixed value is added to a d-axis current command output from a speed control unit only at a low speed. . 5. The PM motor according to claim 1, wherein the d-axis strengthening field current command circuit comprises a setting device, and the d-axis strengthening field current command having a fixed value is adjustable. Control method.