Stepping motor chopper drive，Chopper constant current drive circuit is a better performance
Fig. 9 is a schematic diagram of a chopper constant current drive circuit with only one phase driving circuit, and the rest of the two phases are the same. The switching of the phase winding is controlled by the switch tube VT1 and VT2. The emitter of the VT2 is connected with a sampling resistor R. The voltage drop on the resistor is in direct proportion to the phase winding current I.
Chopper constant current drive circuit is one of the driving methods with better performance and more current use. The basic idea is that the current of the conduction phase winding is rated regardless of whether the motor is in the locked state or in low frequency or high frequency operation.
When the control pulse UI is high, the two switching tubes of VT1 and VT2 are all connected, and the DC power supply is supplied to the winding. Due to the influence of winding inductance, voltage sampling resistor R gradually increased, when the voltage exceeds a given value of UA, the comparator output low level, and also make the output low, VT1 is off, the DC power supply is cut off, the winding current is I by VT2, R, VD2 and the continuous flow attenuation, voltage sampling resistor R the fall. When the voltage on the sampling resistor R is less than the given voltage UA, the comparator outputs a high level, and the gate also outputs a high level, and the VT1 is re connected, and the DC power supply begins to supply the winding. In this way, the current of the phase winding is stabilized at a value determined by the given voltage ua.
