The Design Of Two-phase Hybrid Stepping Motor Subdivision Controller

Stepper motors with high positioning accuracy, no accumulative error, no brush, starting and stopping with fast reaction speed, open loop control performance is good, etc., which makes the use of stepper motor in digital control filed increasing. And Hybrid stepper motors with small size, low noise, small vibration characteristics, has become the most widely used in the motor, therefore, the research of hybrid stepper motor contorller has become a popular research in the motor industry. In view of the shortcomings of the two-phase hybrid stepping motor, such as strong vibration and high noise in low frequency running, the torque decreases and the load capacity is insufficient at high frequency running. In this paper, we propose a new method of subdivision control of stepping motor based on alternating freewheeling mode, and complete the design of the controller.In this paper, the structure and working principle of two-phase hybrid stepper motor are analyzed and explained in detail, and the flux linkage and inductance are analyzed and calculated in detail, then the mathematical model of two-phase hybrid stepper motor is derived, these are the theoretical basis of subdivision control of two-phase hybrid stepper motor. This paper briefly explains the components of the common stepper motor driver, analyzes the working principle of several traditional driving modes, and summarizes their respective advantages and disadvantages, then determines the use of constant current chopper driving circuit and H-bridge driver circuit in this design.Based on the mathematical model of two-phase hybrid stepper motor, the mathematical derivation of subdivision control is carried out, and the changes of torque, current and rotor of motor 4 in subdivisions mode is introduced in detail, and the principle and realization method of SPWM control are described in detail in this paper. Analyzed the role of freewheeling circuit in motor drives, then analyzed several common freewheeling circuit working principles, advantages and disadvantages. Two new freewheeling circuits(a fast freewheeling circuit and a low freewheeling circuit) are designed, which are based on the common freewheeling circuit, and the principle and characteristics of their respective work are analyzed. And a new freewheeling control ideas by self-adjusting the speed of freewheeling and a new method of alternately current control are proposed, and the realization principle is presented. So the subdivision control and freewheeling control are the two key points and difficulties in this design.In this paper, the design of controller was elaborated from hardware circuit design and software circuit design. Regarding hardware circuit design, the part of PIC16F73 Control Circuit, D/A Switching Circuit, PWM Constant Current Chopper Drive Circuit, Logic Circuit, Power Driver Circuit and Power Supply Circuit are analyzed. On the basis of the hardware circuit, the software design is analyzed from two aspects: the master program design and the interrupt program design. The interrupt program is the key parts to achieve the subdivision and freewheeling control of stepper motor.At the end of this paper, the system object is tested, and the test and analysis of the single phase current waveforms of different subdivision are carried out. The design can effectively reduce the low frequency oscillation and noise, and meet the requirements.