JPH0360399A - Stepping motor driving circuit - Google Patents

Abstract

PURPOSE:To prevent over current due to a pinched cable, etc., and also to prevent the breakdown of a power supply part by performing the current detection for chopper control with the common currents of a motor. CONSTITUTION:This is composed of a power supply part 1 for driving a motor 3, a phase control part 10 for changing over the exciting phase of the motor 3, and a chopper control part 2 for making the current flowing through a motor coil 9 constant. The chopper control part 2 amplifies the potential difference at detection resistor R4, and compares it with reference voltage E8. That is, the driving current detection for the chopper control part 2 is made with the common currents of the motor 3. Moreover, in the case that the cable 11 of the motor 3 is short-circuited with a housing to which the motor 3 is attached, the chopper control part 2 is located between the power supply part 1 and the motor 3. Thus, it can prevent the current from flowing until the power supply part 1 is damaged.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to a stepping motor drive circuit.

[Conventional technology]

FIG. 2 is a circuit diagram showing a conventional example.

The stepping motor drive circuit shown in FIG. 2 is composed of a power supply section 1, a phase control section 10, and a chopper control section 2.

The chopper control section 2 detects the motor current flowing from the phase control section 10 and performs chopper operation.

[Problem to be solved by the invention]

In conventional stepping motor drive circuits, current detection was performed using the phase current of the motor, so if the phase current stops flowing due to the motor cable getting caught, current detection cannot be performed and the chopper operation will not work. Overcurrent will flow. Therefore, there is a drawback that the power supply section is destroyed.

[Means to solve the problem]

The constant current chopper type stepping motor drive circuit of the present invention includes a motor drive power supply section, a motor phase control section, and a chopper control section that detects a common current of the motor and performs constant current drive.

〔Example〕

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

It consists of a power supply section 1 for driving the motor 3, a phase control section 10 for switching the excitation phase of the motor, and a chopper control section 2 for making the current flowing through the motor coil 9 constant.

Now, when the phase excitation clock φ6 is supplied to the transistor of the phase control section 10, the motor current flows in the order of the power supply section 1→detection resistor R4→coil 9→phase control section 10.

The chopper control unit 2 amplifies the potential difference across the detection resistor R4 and compares it with a reference voltage E8.

When the motor current increases and the potential difference at the detection resistor R4 becomes larger than the reference voltage E8, the converter 7 turns off the transistor of the power supply section 1.

Then, a motor current flows through the motor in the order of flywheel diode 5 → detection resistor R4 → coil 9 → phase control unit 10.

When the motor current decreases and the potential difference across the detection resistor R4 decreases, the comparator 7 causes the power supply unit 1 to
transistor is turned on, and the above-described operation is repeated.

Now, even if the motor cable 11 is short-circuited to the casing to which the motor is attached for some reason, the chopper control section 2 is located between the power supply section 1 and the motor 3, so power can be supplied. Current is prevented from flowing until part 1 is destroyed.

〔Effect of the invention〕

As explained above, the present invention detects the current for chopper control using the common current of the motor, thereby preventing overcurrent due to cable entanglement, etc., and also preventing damage to the power supply section. There is an effect.

[Brief explanation of drawings]

FIG. 1 is a circuit diagram showing an embodiment of the present invention, and FIG. 2 is a circuit diagram showing a conventional example. 1... Power supply section, 2... Chopper control section, 3.
...Motor, 4...Detection resistor, 5...Flyhole diode, 6...Phase switching clock, 7...Comparator, 8...Reference voltage source, 9...Motor coil, O. ...Phase switching section.

Claims (1)

[Claims] A constant current chopper type stepping motor drive circuit having a power supply section, a motor phase switching section, and a chopper control section, wherein the drive current of the chopper control section is detected using a common current of the step motor. Current chopper stepping motor drive circuit.