JPH11164598A - Controller for permanent magnet synchronous motor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable highly-efficient operation of a vector controller for a permanent magnet synchronous motor. SOLUTION: A highly-efficient controller 9, which calculates the effective value of the primary current i1 of a permanent magnet synchronous motor 2 from the square root of the sum of the square of a q-axis current command iqc and the square of a d-axis current command idc, and outputs such a d-axis current command idc so as to minimize the effective value of the primary current i1 is provided. A vector controller, which minimizes the primary current i1 passing through the permanent-magnet synchronous motor 2 and enables operation with efficiency, is obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a control system for driving a permanent magnet type synchronous motor, and more particularly, to a permanent magnet type synchronous motor which enables high efficiency operation by minimizing a current flowing through the permanent magnet type synchronous motor. Control device.

[0002]

2. Description of the Related Art FIG. 2 shows an example of a block diagram for performing high-efficiency control of a conventional permanent magnet type synchronous motor, which will be described with reference to FIG. In FIG. 2, the speed controller 6 includes a rotation speed command ωc of the permanent magnet type synchronous motor 2 and a speed detector 4.
And outputs a torque command Tc such that the rotation speed follows the rotation speed command. The q-axis current command generator 7 outputs the torque command Tc and the d-axis current command id.
and outputs a q-axis current command iqc such that the output torque of the permanent magnet synchronous motor matches the torque command. The d-axis current command generator 10 outputs a q-axis current command iqc
And outputs a d-axis current command idc. The current controller 8 receives the q-axis current command iqc, the d-axis current command idc, the output i1 of the current detector 5 and the output θg of the position detector 3, and detects a current flowing through the permanent magnet type synchronous motor. The output of the unit 5 is a q-axis current command iqc and a d-axis current command id
A control signal that matches c is output. Power converter 1
Supplies electric power to the permanent magnet synchronous motor 2.

[0003] As a high efficiency control method of a permanent magnet type synchronous motor, [1] Denki Kagaku D, Vol. 114, No. 6, 1994, p.
662 to 667, and [1] is a method of controlling the d-axis current command idc as in the following equation based on the relationship derived from the condition that maximizes the torque with respect to the current flowing through the permanent magnet type synchronous motor. It is. idc = φa / (2 * Lq−2 * Ld) −sqrt [φa * φa / (2 * Lq−2 * Ld) / (2 * Lq−2 * Ld) + iqc * iqc] (1) where φa Is the magnetic flux of the permanent magnet, Lq is the q-axis inductance, Ld is the d-axis inductance, and sqrt [] is a function of the square root.

[0004]

However, in the conventional configuration, the motor constant of the permanent magnet type synchronous motor is required for high efficiency operation. If the motor constant has an error or changes due to temperature or the like, high-efficiency operation becomes impossible, as is apparent from equation (1). The present invention has been made in view of the above points, and its purpose is to
It is an object of the present invention to solve these disadvantages and to provide a permanent magnet synchronous motor control device capable of operating with high efficiency.

[0005]

Means for achieving the object are as follows: 1) In claim 1, the primary current of the permanent magnet type synchronous motor is converted into a d-axis current component parallel to the magnetic flux of the permanent magnet and a permanent current. In the control device of the permanent magnet type synchronous motor that controls by dividing the q-axis current component perpendicular to the magnetic flux of the magnet, the magnitude of the d-axis current component parallel to the magnetic flux of the permanent magnet is reduced by setting the effective value of the primary current to the minimum. And a high-efficiency controller that makes

[0006] 2) The high-efficiency controller according to claim 2, wherein the high-efficiency controller calculates an effective value of the primary current from a d-axis current command and a q-axis current command, and an effective value of the primary current. , A comparator for detecting the sign of the output of the differentiator, an exclusive-OR circuit for performing an exclusive-OR operation from the output of the comparator and the output of the primary delay circuit, A first-order delay circuit that outputs the output of the exclusive-OR circuit with a predetermined time delay, and d from the output of the exclusive-OR circuit.
It comprises a d-axis current command adjuster that outputs a shaft current command. Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings.

[0007]

FIG. 1 is a block diagram showing an embodiment of the present invention, and FIG. 1 will be described below. The description of the same parts as in FIG. 2 of the prior art is omitted. In FIG. 1, a primary current effective value calculator 91 is a d-axis current command idc.
Value of the primary current i1 of the permanent magnet type synchronous motor from the square root of the sum of the square value of the square current and the square value of the q axis current command iqc
Calculate s. The differentiator 92 outputs a fluctuation amount Pirms of the output irms of the primary current effective value calculator 91.
The comparator 93 outputs a value S corresponding to a sign that becomes 1 if the output Pirms of the differentiator 92 is positive and 0 if it is negative. The exclusive OR circuit 94 calculates an exclusive OR from the output S of the comparator 93 and the output of the primary delay circuit 95 and outputs the result. The primary delay circuit 95 delays the output of the exclusive OR 94 by a predetermined time and outputs it. If the output of the exclusive OR circuit 94 is 1, d-axis current command adjuster 96
The axis current command idc is increased at a predetermined slope, and if the output of the exclusive OR circuit 94 is 0, the d-axis current command idc is reduced at a predetermined slope.

When the effective value irms of the primary current is switched to increase, the output S of the comparator 93 becomes 1 and the output of the exclusive OR circuit 94 is inverted.
The increase or decrease of the d-axis current command idc by the shaft current command adjuster 96 is switched, and the effective value irm of the primary current is changed.
decrease s. Further, the effective value irms of the primary current
Is switched to a decrease, the output S of the comparator 93 is reduced.
Becomes 0 and the output of the exclusive OR circuit 94 remains unchanged, and the d-axis current command i
The same operation is repeated with the increase or decrease of dc, and the effective value irms of the primary current is further reduced.

[0009] The primary delay circuit 95 generates a signal d at a predetermined frequency in the vicinity where the effective value irms of the primary current is minimum.
The axis current command idc is inserted to repeat a minute increase / decrease.

[0010]

As described above, according to the present invention, the torque of the permanent magnet type synchronous motor can be efficiently controlled without knowing the motor constant of the permanent magnet type synchronous motor. It is extremely useful.

[Brief description of the drawings]

FIG. 1 is a block diagram of one embodiment of the present invention.

FIG. 2 is a block diagram of an example of the related art.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 power converter 2 permanent magnet synchronous motor 3 position detector 4 speed detector 5 current detector 6 speed controller 7 q-axis current command generator 8 current controller 9 high efficiency controller 91 primary effective current value calculator 92 Differentiator 93 Comparator 94 Exclusive OR circuit 95 Primary delay circuit 96 d-axis current command increase / decrease device 10 d-axis current command generator

Claims (2)

[Claims] 1. A control device for a permanent magnet type synchronous motor for controlling a primary current of a permanent magnet type synchronous motor by dividing the primary current into a d-axis current component parallel to the magnetic flux of the permanent magnet and a q-axis current component perpendicular to the magnetic flux of the permanent magnet. At d, which is parallel to the magnetic flux of the permanent magnet
A control device comprising a high-efficiency controller for setting the magnitude of an axial current component such that the effective value of the primary current is minimized. 2. The high-efficiency controller includes a d-axis current command and a q-axis current command.
A primary current effective value calculator for calculating an effective value of the primary current from a shaft current command; a differentiator for differentiating the effective value of the primary current; a comparator for detecting a sign of an output of the differentiator; An exclusive-OR circuit that performs an exclusive-OR operation from the output of the device and the output of the first-order delay circuit; the first-order delay circuit that outputs the output of the exclusive-OR circuit with a predetermined time delay; 2. The control device for a permanent magnet synchronous motor according to claim 1, comprising a d-axis current command adjuster that outputs a d-axis current command from an output of the OR circuit.