JPS60167695A - Speed control system of polyphase dc brushless motor - Google Patents

Abstract

PURPOSE:To improve the variation in the speed due to a transient cause by sequentially calculating the periods of pole detection signals from the periods of stored pole detection signals and the period of a composite signal to control the speed of a motor. CONSTITUTION:A motor has full-wave 3-phases, 16 poles and 300rpm, and 3 Hall switches 1, 2, 3 as pole position detectors. An operation for obtaining a speed detection signal from a load signal SLOAD is executed by a microcomputer 10. The period of a composite signal is stored in a memory as a reference signal. Then, a period for calculating the speed is obtained from the stored periods and the present period of the composite signal, and the speed at the present period of the composite signal is calculated. The speed of the motor is controlled on the basis of the detected speed obtained in this manner.

Description

DETAILED DESCRIPTION OF THE INVENTION Technical Field The present invention relates to a speed control method for a polyphase DC brushless motor.

<Prior Art> FIG. 1 is a circuit diagram of a conventional example of a speed control system for a polyphase DC brushless motor, and FIG. 2 is a time chart of signals at various parts in FIG. In this conventional speed control method of a multi-phase DC brushless motor, since it is a six-phase motor in this case, a plurality of Hall switches, which are magnetic pole detectors, are used in 1.2.
3 and 6 are provided, and each magnetic pole detection signal SI + S2
r S3 is connected to exclusive OR circuits 4, 5 . Differentiator circuit (flip-flops 6, 7, exclusive OR circuit 8) within the dash-dotted line,
The clock pulse generator 9 combines and synthesizes the signal S LOAD with a frequency higher than the original magnetic pole detection signal SI h S2 r S3, in this case six times the frequency. By sequentially adding six periods, each magnetic pole detection signal S, , S2 . S
3 period Tn,,,TH.

2+ ”+3+ Tn +4+ Tn+5+ Tn+6
+Tn+, +l l """ is calculated, and each interval ['n,.

Pn+2+ Pn+3+ ” +4+ Pn+5+ ”
+6 + "+I + + "" Detection speed V n, , Vn, 2. Vn, 3. Vn, 4.
Vn.

5 + Vn+l + Vn+, II +...
・Speed control was performed by obtaining ・.

This eliminates the influence of variations in the spacing between the magnetic pole detection signals of each phase due to variations in the magnetization strength of the rotor, variations in the distance between the magnetic pole detector and the rotor, and changes due to temperature of the Hall element that is the magnetic pole detector. I had lost it.

In this conventional method, for example, the speed detected at the time point PB is calculated from the period 'rn +1, so the points FA and pB
This speed is the average speed between points FA and PB, and this speed is the midpoint P between points FA and PB.
It is considered to be the speed of C. Therefore, it is considered that the speed detection is delayed by the time Tn+1/2.

In this way, in this conventional method, the average speed detection time is T+/2 (T 1 = Tn , , Tn +2 ,
, , , , , ), there was a drawback that transient speed fluctuations (uneven rotation) due to sudden changes in load or power supply voltage could not be improved.

<Object of the Invention> Therefore, an object of the present invention is to provide a speed control method for a multiphase DC brushless motor that improves speed fluctuations (rotation unevenness) caused by transient factors such as sudden load fluctuations and sudden changes in power supply voltage. There is a particular thing.

<Structure of the Invention> For this purpose, the present invention stores in advance the period of each magnetic pole detection signal and each period of the composite signal at the reference speed, and stores the period of each magnetic pole detection signal stored in advance during steady operation. The period of each magnetic pole detection signal is calculated sequentially from each period of the composite signal and the current period of the composite signal, and the speed detection signal is obtained from this period to perform speed control. be.

<Example> Hereinafter, an example of the present invention will be described with reference to the drawings. FIG. 6 is a circuit diagram of a multi-phase DC brushless motor drive device to which an embodiment of the present invention is applied.

The motor is 6 phase full wave, 16 poles, 600 PM, equipped with 6 Hall switches 1°2.6 as magnetic pole position detectors, and controlled at constant speed. ″Load signal S LOA
The circuit up to the output of D is the same as the conventional example shown in FIG. The operation of receiving the speed detection signal from the load signal (combined signal) 5LOAD of the present invention is performed by the microcomputer 10.
It will be held in

This operation will be explained below with reference to the flowchart shown in FIG.

(1) It is determined whether the operation mode is the initial mode or the steady operation mode (step 21).

(Step 22).

(3) Each period trn of the composite signal at the reference speed, 1 (i=
1 to 6) are stored in memory as reference values (step 2
6).

(41 (Once the process of 31 is completed, change to steady operation mode (step 24).

The period T for speed calculation from the period trn, i stored in (5i, +3) and the current period in, i of the composite signal
Calculate n and i (step 25).

(6) From the period Tn, i obtained in (5), calculate the velocity V, n, i at the current period tn, i of the composite signal (step 26).

Based on the detected speed Vn, i obtained in this way, the speed of the motor is controlled in the following steps.

(7) Command speed V stored in program memory
Calculate the difference E between ref and detection speed Vn,i (step 27
).

(8) Calculate the control operation amount PD (step 28).

(9) Input magnetic pole detection signal Sl + S2 + S3)1. , I2°13 (step 29) (1ω) Phase order calculation is performed (step 60).

01) Output the ξ pulse width modulated signal θ1 (i=1 to 6) to the terminal Qi (i=1 to 6) (step 61)
. This output signal is input to the driver 11, power amplified, and current is applied to the coil 12 of the motor to control the rotation.

The delay in speed detection in this example is t n + i
/2, which is significantly improved from about 124 in the conventional example shown in FIG.

By storing all the periods trn,i for one revolution of the rotor as reference values, it is possible to eliminate not only the influence of the installation accuracy and operation variations of the magnetic pole detectors, but also the influence of the magnetization accuracy of the rotor.

<Effect of the invention> According to the present invention, the delay in speed detection time is significantly reduced.

[Brief explanation of the drawing]

Fig. 1 is a circuit diagram of a conventional speed control method for a polyphase DC brushless motor, Fig. 2 is a time chart of signals of each part in Fig. 1, and Fig. 6 is a flowchart showing the multiphase operation of the present invention. It is. 1.2.5: Hall switch, 4.5, 8: Exclusive OR circuit 6.7 two flip-flops, 9: Clock noise generator, 10: Microcomputer - Figure 1 Figure 2 Body 3 Figure

Claims (1)

[Claims] A speed control method for a multi-phase DC brushless motor equipped with a plurality of magnetic pole detectors that detect the magnetic poles of a rotor composed of permanent magnets, in which the magnetic pole detection signals of each magnetic pole detector are combined,
In a speed control method for a polyphase DC brushless motor that uses a synthesized signal with a higher frequency than the original magnetic pole detection signal as a speed control signal, the period of each magnetic pole detection signal at the reference speed and the synthesized signal are Each period is stored in advance, and during steady operation, the period of each magnetic pole detection signal is calculated from the period of each magnetic pole detection signal stored in advance, each period of the composite signal, and the current period of the composite signal. 1. A speed control method for a polyphase DC brushless motor, characterized in that the speed is sequentially calculated and a speed detection signal is used from this period to perform speed control.