JPH0232797A - Drive of pulse motor - Google Patents

Abstract

PURPOSE:To perform effective drive of a pulse motor by increasing the current in a leading edge section for phase current more than the current in a trailing edge section in its acceleration or in its high speed operation, and conversely by increasing the current in the trailing edge section more than the current in the leading edge section for the phase current in the deceleration of the motor. CONSTITUTION:In high speed operation in acceleration of a pulse motor, control waveforms in phase A and B are outputted as shown in Fig. 1. In this case, the level of a leading edge section (a) for control waveform is set higher than that of a trailing edge section (b) where (a) is asymmetrical to (b). Thus, the force to promote the rotation of a rotor is to act on, so that the depression of torque will be reduced. Conversely, in its deceleration the control waveforms in phases A and B are outputted as shown in Fig. 2. In this case, the level of the trailing edge section (b) for control waveform is set higher than that of the leading edge section (a). This shows that the force will act on the direction to stop the rotation of the rotor, so that the motor can be decelerated effectively.

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Field of Industrial Application This invention relates to a method for driving a pulse motor, and particularly to a driving method that is devised to improve driving efficiency.

(b) Conventional technology-i, a pulse motor is equipped with A-phase and B-phase windings on a stator, and rotates with a single salient pole whose pitch is slightly different from that of the stator core. By sequentially exciting the A-phase and B-phase windings of the stator, the salient poles of the rotor are successively attracted and rotated. And is the control current of conventional pulse motors on the position side? As shown in FIG. 4, the rising portion a and the falling portion are already symmetrical so as to be suitable for ff1l.

(C) Problems to be Solved by the Invention In the conventional pulse motor described above, in phase L of FIG. Move to phase position. In this intermediate state, phase t2, the salient poles of the rotor receive equal forces from the A phase and B phase, and move to an intermediate position during low speed operation. The phase current vector at this time is shown as t2·a in FIG. At this position, keep the rotor quiet.
There is no problem when the motor is stopped, but when the motor is rotated, the vector of the phase current moves from the B phase to the A phase, and the current that rubs against the B phase at this time causes the stator to slow down the rotation. act. Furthermore, when rotating at high speed,
The current flowing through the motor due to the inductance of the motor is delayed in phase with respect to the control waveform (therefore, the generated torque at high speeds and accelerations is small.As a result, efficiency is poor during high speed rotations, accelerations, and decelerations. This requires a very large power source and generates a lot of heat, so there is a problem in that it requires a large heat dissipation section.

The present invention has been made in view of the above-mentioned problems, and it is an object of the present invention to provide a method for driving a pulse motor that can improve efficiency during high-speed rotation, acceleration, and deceleration.

(d) Means and operation for solving the problems The pulse motor driving method of the present invention is a method for controlling the rotational state of a motor by controlling the phase current of the motor.
When the motor is accelerating or at high speed, the current at the rising part of the phase current is made larger than the current at the falling part (see Figure 1), and when the motor is decelerating, the current at the falling part of the phase current is made larger than the current at the falling part. The current is made to be larger than the current at the rising edge (
(See Figure 2).

According to this pulse motor drive method, during acceleration or high speed, the rising part of the phase current is made larger than the falling part, so a force acts in the direction of speeding up the rotation, resulting in a drop in torque. On the other hand, during deceleration, the falling part of the phase current is made larger than the rising part, so a force acts in the direction of stopping rotation, so deceleration can be achieved efficiently.

(E) Examples The present invention will be explained in more detail with reference to Examples below.

FIG. 3 is a circuit diagram of a pulse smoke drive circuit showing one embodiment of the present invention. In the figure, LA and LA are phase windings for the A phase and human phase of the stator of the pulse motor, and are connected in series to switching transistors TSA and TS for polarity switching, respectively. connected in parallel.

Similarly, LB and LB are phase windings for the B phase and B phase of the stator of the pulse motor, and switching transistors TSB and TSIII for polarity switching are connected in series and in parallel with each other, respectively. .

In addition, a transistor TRA for controlling the phase current of the A phase is connected between the connection point of the phase windings LA and LA and the power supply +7, and a transistor TRA for controlling the phase current of the A phase is connected between the connection point of the emitters of the transistors TSA, TS and the ground. A resistor RA for phase current detection is connected. Similarly, a transistor TRB for controlling the phase current of the B phase is connected between the connection point of the phase windings LB and L7 and the power supply +7, and a transistor TRB for controlling the phase current of the B phase is connected between the connection point of the emitters of the transistors TSB and TSr3 and the ground. A resistor RB for current detection is connected.

The setting section 1 is provided to set the rotational speed of the motor, and the set rotational speed is taken into the CPU 2. The CPU 2 determines the optimal phase current shape for the operating conditions such as rotational speed, and sends the control signal to the D/A converter 4.
Output to A and 4B.

Note that the ROM 3 stores control waveform patterns and the like corresponding to operating conditions. The D/A converter 4A outputs a control waveform Vr*fA and applies it to the pulse width modulation circuit 5A. The pulse width modulation circuit 5A has a control waveform V□ and a resistor R.
Pulse width modulation is performed to control the ON time of the transistor TRA so that the voltage VMA corresponding to the phase current from A becomes equal. Similarly, the D/A converter R34B uses the control waveform V
ret8 is output and applied to the pulse width modulation circuit 5B.

The pulse width modulation circuit 5B performs pulse width modulation so that the control waveforms (2), arII and the voltage (2) corresponding to the phase current from the resistor RB are equal, and controls the ON time of the transistor TRB. In addition, the polarity switching signal SΔ from the CPU2
is added directly to the transistor TSA and to the transistor TS through the inverter 6A, and the transistors TSA, T
It turns on/off the S person and switches the polarity of the A phase and input phase. Similarly, the polarity switching signal SB from the CPU 2 is applied directly to the transistor TSB and to the transistor TSB via the inverter 6B to turn on/off the transistors TSB and TSr3, thereby switching the polarity between the B phase and the B phase.

In the above pulse motor drive circuit, during low speed operation,
The A-phase and B-phase control waveforms shown in FIG. 4 are output from the CPU 2. In this case, the rising portion a and the falling portion S of the control waveform have the same level and are symmetrical waveforms. The operation in this case is not particularly different from the conventional one.

During high-speed operation and acceleration, the CPU 2 outputs A-phase and B-phase control waveforms shown in FIG. In this case, the level of the rising portion a of the control waveform is set higher than the level of the falling portion, and is asymmetrical.

In this control waveform example, in phase L1, the salient poles of the rotor are at the position of the B-phase winding of the stator, and in phase t3, the salient poles of the rotor are at the position of the B-phase winding of the stator.
As in the case shown in the figure, move to the position of the A-phase winding of the stator. In phase t2, which is an intermediate state, the salient poles of the rotor receive a larger attraction force from the human face than in phase B. If this state is represented by a vector, it becomes L2·b in FIG. This applies a force that further promotes the rotation of the rotor, and therefore reduces the drop in torque.

Conversely, during deceleration, the CPU 2 outputs control waveforms of phase A and phase B shown in FIG. In this case, the level of the falling portion a of the control waveform is set higher than the level of the rising portion a, which is also asymmetrical. Also in this control waveform example, the salient poles of the rotor are at the position of the B-phase winding in phase t, and similarly move to the position of the A-phase winding of the stator in phase L3.

However, there is an intermediate state phase. Then, since the level of the falling part of the B phase is higher than the level of the rising part of the A phase, the vector is also as shown at t2C in Fig. 5,
The salient poles of the rotor receive a larger attractive force from the B phase than from the A phase. This is a force that acts in the direction of stopping the rotation of the rotor, and can efficiently decelerate the rotor.

(f) Effects of the Invention According to the present invention, during acceleration or high speed, the current at the rising edge of the phase current is made thicker (thus promoting rotation) than the current at the falling edge, and conversely, during deceleration, Since the current in the falling part of the phase current is made larger than the current in the rising part to facilitate stopping, efficient driving can be achieved, and the driving power supply can be made smaller accordingly. And because it generates less heat,
The heat dissipation section can be easily configured, and the entire system can be made inexpensive and compact.

[Brief explanation of the drawing]

FIG. 1 is a control waveform diagram for explaining the operation of a pulse motor drive circuit according to an embodiment of the present invention during high speed and acceleration, and FIG. 2 is a control waveform diagram for explaining the operation of the pulse motor drive circuit during deceleration. 3 is a circuit diagram showing the drive circuit of the pulse motor, FIG. 4 is a control waveform diagram for explaining the conventional driving method, and FIG. 5 is a control waveform diagram showing the drive circuit of the pulse motor. FIG. 5 is a diagram showing output current vectors of each control waveform in FIGS. 2 and 4; FIG. ■, A-LA-LB-LB: Aimaki g, TRA-,
TRB: Current control transistor, TSA-TSX-T
SB-TSr3 Transistor for bipolar switching, 2: CPU, 4A/4 B: D/A converter, 5
A.5B: Pulse width modulation circuit. Figure 1 Figure 2 Patent Applicant Shimadzu Corporation Agent Patent Attorney Shigeru Nakamura

Claims (1)

[Claims] (1) In a pulse motor drive method that controls the rotational state of the motor by controlling the phase currents of the motor, when the motor is accelerating or at high speed, the rising part of the phase current is changed to the falling part of the current. A method for driving a pulse motor, characterized in that the current at a falling portion of the phase current is made larger than the current at a rising portion of the phase current when the motor is decelerated.