Single voltage drive is to point to in the working process of the motor winding, using only one direction for winding the power supply voltage. As shown in figure 2, L for motor winding, VCC power supply. When the input signal In high electricity at ordinary times, provide enough base current triode T In a saturated state, if ignore its saturation pressure drop, all the power supply voltage on the motor windings. When In low electricity at ordinary times, triode deadline, no current through the winding. To make the power winding current quickly achieve preset current, the series resistance of the Rc; To prevent shut off when T winding current rate of change is too big, and produce a lot of back emf will T breakdown, in the ends of the winding parallel a diode D and resistor Rd, provide a discharge circuit for the winding current, also known as 'fly-wheel circuit'. Single voltage power drive circuit has the advantage of simple circuit structure, less components, low cost, high reliability. But because the series resistance, power consumption, the low efficiency of the power drive circuit, the only suitable for small power stepping motor. In order to make the power winding can quickly reach the set current, shut off the winding current decay quickly to zero, at the same time has high efficiency, the high and low voltage drive mode. As shown in figure 3, Th, T1, high pressure and low pressure pipe, respectively, the Vh, V1, high and low voltage power supply, respectively, the pulse signal on Ih, I1 of high and low respectively. In conduction frontier in the forefront of high voltage power supply to improve the current rate of climb, after the in front to maintain the low voltage winding of electric current. High and low voltage driver can achieve good high frequency characteristics, but because of the high pressure pipe conduction time constant, at low frequency, winding won too much energy, easy to cause oscillation. But by changing the high pressure pipe conduction time to solve the problem of low frequency oscillation, the voltage control circuit is complex, however, lower reliability, once high pressure pipe is out of control, will be for damage to the motor current is too big. Autonomous constant current chopper driver block diagram. The step motor winding current value is converted into A certain percentage of the voltage, and compares the default values of D/A converter output, control the switch of power tube, so as to achieve the purpose of the control winding current. Theoretically, self-excited constant current chopper drive of the motor winding current can be controlled at a constant value. But because the chopping frequency is variable, and can make the winding has high surge voltage, and thus produce very big interference to control circuit, prone to oscillation, reliability is reduced greatly. the main products: stepper motor, brushless motor, servo motor, stepping motor drive, brake motor, linear motor and other kinds of models of the stepper motor, welcome to inquire. Telephone:
