Drive Systems, Microcontroller-based Stepper Motor Segments

As an integrated system including with both hybrid stepping motor and driver, its quality of operation is depended on the performanceof motor, driver and controller. In the open-loop state, the noise of the stepping motor is great, and control precision is low, which can't meet request of the high running quality in many situations. So the performance is improved in stepping motor operation through realizing the closed-loop operation of stepping motor. The main intention of the research in this paper is to develop stepping motor subdivision system based on microcontroller, which realizes the closed-loop operation of stepping motor.On deep research of the structure, running mechanism of the stepping motor and subdivided driving principle, the paper's author presents the sine wave current subdividing and current tracking PWM technology, which realizes the constant torque operation of stepping motor and improves the running precision. Considering the nonlinear of stepping motor, the author discusses that the method of minimum square is adopted to fit and correct the error curve of subdivision stepping angle.As for control method, by analyzing the mathematics models of two-phase hybrid stepping motor, the structure of the stepping motor's velocity closed-loop control is constructed. The fuzzy PI control method is used in the speed loop. To validate its feasibility, the author estabilishes the simulation model of driving system, and does the simulation research contrastively on the fuzzy PI control method and general PI control method.Based on the above research, the author designs the hardware and software of driving controller, in order to meet the requirements of the two-phase hybrid stepping motor's dynamic characteristics. It consists of digital control part, GAL logic integrated unit, TL494 constant current control circuit, dirving circuit, current feedback circuit, velocity collection circuit, over current protecting and the power supply block. The driving system uses singlechip DS89C450 as the control core and has the functions of constant current control, forward/reverse working, over-current protection and multilevel subdivision driving. Velocity collection circuit uses incremental optical-electrical encoder as feedback element which feeds back the fact velocity of stepping motor, and realizes the closed-loop control strategy, so as to achieve the better control effect.The driving controller has completed and tested, the test results are presented in the paper, and the tested wave forms are analyzed. Experiments indicate that the design of hardware and software is reasonable and feasible, and successfully meets the design needs, improves the running characteristics of stepping motor, and has the good application prospect.