JPS5932375A - Controller for drive of alternating current synchronous motor - Google Patents

Abstract

PURPOSE:To shorten a time when the AC synchronuos motor is synchronized by making driving currents before the motor is synchronized larger than the ones on synchronizing on the basis of the result of detection of the synchronous state of the AC synchronous motor. CONSTITUTION:When the AC synchronous motor 3 is started, a speed sensor 6 outputs a sensor signal corresponding to an asynchronous state, and a control section 7 to which the sensor signal is inputted outputs a switch signal. Consequently, constant voltage is applied to an inverter drive circuit 4, and the motor 3 is given large driving currents on the basis of low impedance on starting. When the motor 3 is brought to a synchronous state after starting, the supply of constant voltage is interrupted because the control section 7 stops the output of the switch signal on the basis of the sensor signal of the speed sensor 6, and constant currents are outputted from a constant-current power supply 1. Accordingly, the time when the AC synchronous motor is synchronized can be shortened.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an AC synchronous motor drive control device that increases the drive current at startup to shorten the time required to reach synchronization.

An example of an AC synchronous motor drive control device is one that is equipped with a capacitor that controls the drive current according to internal impedance in order to reduce speed fluctuations of an AC synchronous motor that rotates a rotating polygon mirror (polygon) of a laser printer. It has been proposed by the same applicant (for example, "AC synchronous motor drive circuit" according to a patent application filed on February 6, 1982). FIG. 1 shows this AC synchronous motor drive control device, which includes a DC constant current power source 1, a parallel capacitor 2 having a sufficiently large capacity compared to the circuit constant, and an inverter that supplies drive current to the AC synchronous motor 3. Drive circuit 4
The inverter drive circuit 4 has a rectangular wave generating circuit 5 which outputs three-phase rectangular waves P1 and P2 having a phase difference of 120 degrees at 1 ps. The inverter drive circuit 4 includes three pairs of complementary transistors 4 a e 4 b (emitter follower type in which emitters are connected together) (when driving a three-phase synchronous motor), and transistors 4 a and 4 b.
The rectangular wave of the rectangular wave generating circuit 4 is input to the pace of the transistor 4ae4b.

In the above configuration, when the rectangular wave generating circuit 4 outputs a rectangular wave P1sP1eP having a phase difference of 1200, the transistors 4m and 4b of the inverter driving circuit 4
its switching is controlled with a phase difference of 200;
The accumulation of the current value I0 of the constant current power supply 1 and the internal impedance z1n (DC impedance including the impedance of the motor 3 and excluding the high frequency component due to switching) as seen from the input of the drive circuit 4. - A square wave voltage based on Zin is applied to the motor 3, thereby driving the motor 3 and rotating, for example, a rotating polygon of a laser grinter. When the torque angle of the motor 3 changes due to load fluctuations (for example, uneven rotation due to minute torque fluctuations in the bearing), the internal impedance z1n changes, and the voltage flows into the capacitor 2 according to the voltage change based on the change. Since the current increases and decreases, the current flowing into the inverter drive circuit 4 can be controlled. For example, when the internal impedance Zln of the motor 3 increases due to fluctuations in the torque angle, current flows into the capacitor 2 and the inverter drive circuit 4
Since the current value decreases, the motor 3 is braked, thereby making it possible to reduce speed fluctuations of the motor 3. Based on such control, it is possible to reduce rotational irregularities called hunting (turbulence) to an accuracy of 10-5 or less.

However, in this AC synchronous motor drive control device,
Since the drive is based on a constant current power supply during both startup and synchronization, it takes a relatively long time to reach synchronization due to the low startup internal impedance. Printing operations may be inaccurate.

The present invention has been made in view of the above, and in order to shorten the time it takes to reach synchronization of an AC synchronous motor that is driven with a constant current during synchronization, synchronization is achieved based on the detection result of the synchronization state of the motor. An object of the present invention is to provide an AC synchronous motor drive control device in which the previous drive current is larger than that at the time of synchronization.

The AC cyclic motor drive control device according to the present invention will be explained in detail below.

FIG. 2 shows a first embodiment of the present invention, and in addition to common configurations indicated by the same reference numerals as the reference numerals in FIG. 1,
A speed sensor 6 (for example, a tacho generator) that detects the synchronous or asynchronous state of the AC motor 3, a control section 7 that outputs a switch signal according to the sensor signal of the speed sensor 6, and a resistor R1 that outputs the switch signal. Transistor 8 is turned on when input to the pace via the transistor 8 (field effect type may be used instead of bipolar type. The same applies to each transistor hereinafter), and A constant voltage (v) is applied to the inverter drive circuit 4.
Transistor 9 (CC-vax(mat))
However, vam(sat) is the voltage between the collector and emitter of transistor 9, and the resistor R connected to the pace
.

By adjusting the voltage and sufficiently saturating the transistor 9, it is possible to make this a sufficiently small constant value.

In the above configuration, when the AC synchronous motor 3 is started,
The speed sensor 6 detects an asynchronous state and outputs a sensor signal according to the state, and the control section 7 that receives the sensor signal outputs a switch signal. Based on the switch signal, the transistor 8 is turned on, and then the transistor 9 is turned on, so that a constant voltage (CC-VB) is applied to the inverter drive circuit 4.
(sat) ) is added, and a large starting current is given to the motor 3 based on the low impedance at starting. After starting, when the motor 3 reaches a synchronized state, the control unit 7 stops outputting the switch signal based on the sensor signal of the speed sensor 6, so the transistor 8 and then the transistor 9 are turned off and a constant voltage (vcc -vcm(sat))
The supply of constant current is cut off, and a constant current is output from the constant current power supply 1.

FIG. 3 shows a second embodiment of the invention, which, in addition to the configuration in common with the first embodiment (indicated by the same reference numerals), has a plurality of Constant current power supply section 11.・・・・・・・・・、
1n (constant current values are different, (V, -V□)/H
Determined by However, ■ is Zener diode 1
zener voltage of &, ■□ is the pace of transistor 1b.
the emitter voltage (and R is the resistance value of the resistor 1c), a plurality of switch sections 81 . . . . , 8n and the sensor signal of the speed sensor 6 are processed and the corresponding switch section 81 . . . . 8n is operated, and the control unit 10 (for example, input/output interface, ROM for GLODARAM, CPU for calculation, and RA for storage of calculation results)
A microcomputer (having a microcomputer with M) and a diode 12 that prevents reverse flow of current based on the charge charged in the capacitor 2.

In the above configuration, when the AC synchronous motor 3 is started,
The speed sensor 6 outputs a sensor signal according to the asynchronous state, and the sensor signal is arithmetic processed by the CPU of the control unit 10,
The switch section 81 is activated according to the sensor signal.

When the transistor 1b of the constant current power supply section 11 is turned on by the operation of the switch section 81, the constant current (V, -V
□)/R (which is different from the constant current value in the synchronous state) is supplied to the inverter drive circuit 4. The control unit 10 controls a plurality of switch units 81 . ...
. . , a plurality of constant current power supply units 11. ...
..., thereby supplying the optimum starting current to the motor 3 whose internal impedance changes transiently. When the speed sensor 6 detects the synchronized state of the motor 3, for example, the switch section 8n is operated by the control section 10, and the constant current power supply section 1n supplies a constant current during synchronization. According to this embodiment, since a predetermined constant current is supplied from the time of startup, a rush current flowing into the capacitor 2 at the time of startup can be prevented.

Figure 4 (a), (b), and (c) show the inverter drive circuit 4
(a) shows a totem pole type, (b) shows a collector follower type, and (c) shows an example using a field effect transistor.

As described above, according to the AC synchronous motor drive control device according to the present invention, the drive current before reaching synchronization is made larger than that at the time of synchronization based on the detection result of the synchronization state of the AC synchronous motor. The time required for the driven AC synchronous motors to reach synchronization can be shortened.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram showing a proposed AC synchronous motor drive control device. FIGS. 2 and 3 are explanatory diagrams showing first and second embodiments of the present invention. FIGS. 4A, 4B, and 4C are explanatory diagrams showing three modified examples of the inverter drive circuit. Explanation of symbols 1...constant current power supply section, 2...capacitor, 3...
AC synchronous motor, 4... Inverter drive circuit, 5...
・Square wave generation open circuit, 6...Speed sensor, 7.10...
・Control unit.

Claims (1)

[Claims] A drive control device that drives an AC synchronous motor at a constant current during synchronization, comprising: means for outputting a senna signal according to a state of synchronization of the AC synchronous motor; An alternating current motor characterized by comprising: means for outputting a control signal when a certain thing is detected; and means for supplying a drive current to the alternating current synchronous motor that is equal to a constant current value during synchronization based on the control signal. Synchronous motor drive control device.