JPH06351297A - Motor drive circuit - Google Patents

Abstract

PURPOSE:To realize downsizing while reducing the power consumption by sharing the drive control circuit and the driver between a DC brushless motor and a step motor. CONSTITUTION:The motor drive circuit comprises a reference signal generating section 4 for setting the rotational speed of motor, a pulse width control circuit 14 using the speed and current of the motor, and a drive signal generating section 8 receiving a commutation signal representative of the position of DC motor to generate a drive signal corresponding to the angle. Since the DC motor stops when a step motor is being driven, speed and current of the DC motor go to zero and a stabilized pulse is outputted from the pulse width control circuit. A drive signal to be fed to the step motor can also be produced because a constant commutation signal is delivered from the motor.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a motor drive circuit, and more particularly to a solar cell extension / rotation drive using both a brushless DC motor and a stepping motor.

[0002]

2. Description of the Related Art A conventional drive circuit for extending / rotating a solar cell has a brushless DC motor drive circuit and a step motor drive circuit independently as shown in FIG.

The brushless DC motor drive circuit comprises a reference signal generating section 4, a pulse width control circuit 14, a drive signal generating section 8 and a driver 12. The pulse width control circuit 14 controls the rotational speed as a reference. The signal is compared with the actual speed signal of the DC motor, amplified by the amplifier 5, the current flowing through the DC motor is added to the output, and the pulse width control signal 13 amplified by the amplifier is compared with the output of the triangular wave oscillator 7. The pulse width control of the electric power for driving the motor is performed by the comparison by the device 18.

A pulse (motor drive signal) 11 output from the pulse width control circuit 14 and UE, VE, and WE commit signals 1, 2, and 3 indicating the actual motor position are used for winding in accordance with the motor position. The driver 12 generates drive signals U, V, W for the DC motor by using the output of the drive signal generator 8 which generates the drive signal for the line.

On the other hand, the step motor drive circuit is composed of a reference clock generator 15, a timing controller 16 and a driver 17, and outputs the reference clock output from the reference clock generator 15 which determines the rotation speed of the step motor. Timing control of the output is performed by the timing control unit 16, and the driver 17 drives the drive signal C. T, A and B are generated.

[0006]

In a conventional motor drive circuit used for extending / rotating a solar cell, a drive circuit is provided for each of the DC motor and the step motor, which leads to an increase in size and an increase in power consumption. There was such a problem.

An object of the present invention is to provide a motor drive circuit which solves the above problems.

[0008]

A motor drive circuit according to the present invention shows a driver circuit for driving a brushless DC motor, an oscillation circuit for stabilizing the rotation speed of the brushless DC motor, and the position of the motor. It is characterized by having a circuit for inputting a commit signal and a switching unit for switching between driving of a brushless DC motor and driving of a step motor.

[0009]

Embodiments of the present invention will now be described with reference to the drawings.

FIG. 1 is a block diagram of an embodiment of the present invention. In this motor drive circuit, the step motor drive circuits 15, 16 and 17 in the configuration of FIG. 3 are removed, and a motor drive switching unit 9 is provided between the drive signal generation unit 8 and the driver 12 of the brushless DC motor drive circuit. The step motor circuit clock 10 is supplied to one input terminal of the switching unit 9. The other configurations are the same as those in FIG. 3, and thus the same components as those in FIG. 3 are designated by the same reference numerals.

Next, the operation of this embodiment will be described with reference to the time chart of FIG.

When driving the brushless DC motor, the step motor rotation clock 10 is set to the "L" level.

The DC motor speed signal and the DC motor current are fed back to the reference signal from the reference signal generator 4 for setting the rotation speed of the brushless DC motor, and the pulse width control signal 13 and the triangular wave generator 7 which are the difference are taken. The drive voltage 11 of the brushless DC motor is generated by comparing the output of the brushless DC motor. This enables pulse width control when driving the DC motor. On the other hand, from the brushless DC motor, a commit signal (UE / VE /
WE) 1, 2, 3 are input to the drive signal generator 8 to generate driver gate signals U ', V', W '. By obtaining the logical product of the driver gate signal and the drive signal 11 in the driver 12, the drive signal U,
V and W are generated to drive the brushless DC motor.

When driving the step motor, a clock corresponding to the rotation speed is input to the step motor rotation clock 10. At this time, since the brushless DC motor does not rotate, both the speed signal and the motor current from the DC motor become 0, and a stable drive voltage 11 can be obtained by comparing the reference signal and the output of the triangular wave generator. it can. On the other hand, since the brushless DC motor is stopped, the commit signal (UE / V
E / WE) also shows a constant value. By applying the logical sum of these commit signals, the applied voltage C. Generate T.

The stepping motor rotation clock 10 and the drive signal 11 output one drive voltage 11 in the "H" section of the rotation clock 10 so that the drive signals are output alternately A and B. The drive signals A and B of the stepping motor can be obtained.

As described above, according to this embodiment,
The DC motor drive circuit has a reference signal generator 4 for setting the rotation speed of the motor and a pulse width control circuit 14 that uses the speed and current of the motor, and commits signals UE, VE, WE indicating the position of the DC motor. Has a drive signal generator 8 for generating a drive signal according to the angle, and the fact that the DC motor is stopped when the stepping motor is driven makes the speed and current of the DC motor zero. Therefore, a stable pulse is output from the pulse width control circuit 14 and the commit signal from the motor is also constant, so that a drive signal to be supplied to the step motor can be generated.

[0017]

As described above, according to the present invention, by sharing the DC motor drive circuit and the stepping motor drive circuit, it is possible to reduce the size and power consumption when the DC motor and the stepping motor are independently driven. Has the effect.

[Brief description of drawings]

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

FIG. 2 is a time chart for explaining the operation of FIG.

FIG. 3 is a block diagram showing a conventional example.

[Explanation of symbols]

 1 Commutation signal UE 2 Commutation signal VE 3 Commitation signal WE 4 DC motor rotation speed determination reference signal generator 5, 6 amplifier 7 triangular wave oscillator 8 drive signal generator 9 motor drive switching unit 10 step motor rotation clock 11 motor Drive signal 12 Driver 13 Pulse width control signal 14 Pulse width control circuit 15 Reference clock generator 16 Timing controller 17 Stepping motor driver 18 Comparator

Claims (2)

[Claims] 1. For driving a brushless DC motor,
A driver circuit, an oscillation circuit for stabilizing the rotation speed of the brushless DC motor, a circuit for inputting a commit signal indicating the position of the motor, and a switching unit for switching between driving the brushless DC motor and driving the step motor. A motor drive circuit characterized by the above. 2. The oscillator circuit includes a reference signal generator that generates a reference signal for setting the rotation speed of a brushless DC motor, a pulse width of the brushless DC motor speed signal and a brushless DC motor current fed back to the reference signal. A circuit for forming a control signal; a triangular wave generator; and a comparator for comparing the pulse width control signal with the output of the triangular wave generator to generate a drive voltage for the brushless DC motor. The motor drive circuit according to claim 1.