Design And Implementation Of Multi-Output Two-Phase Hybrid Stepper Motor Driver With High Accuracy And Stability

With the development of microelectronic, computer and control technique, the driver technique for the two-phase hybrid stepping motor is developed rapidly, and the demands of the stepper motor is going up. Stepper motor cannot work without any drivers. Thus, the operating performance of the stepper motor is not only affected by the characteristics of the motor but also depended by the quality of the driver. Now, most of the stepper motor drivers on the market are only applicable to a single motor, which means that a driver can only drive one stepper motor. When multiple stepper motors are utilized, more than one driver has to be provided. Obviously, in this case, the cost of the product increases and the size of the product with multiple stepper motors become larger. In general, it is very important to develop a new kind of multi-output stepper motor driver with both high accuracy and stability.The stepper motor has the disadvantages that the vibration and noise occur when it runs at the low speed and when it runs at the high speed, big step angle, poor accuracy and small torque arise. In order to overcome these disadvantages, a multi-output two-phase hybrid stepper motor driver with high accuracy and stability is designed and implemented based on the operating characteristics of the two-phase hybrid stepper motor and the subdivision control technology. By taking the single-chip microcomputer of STM32F103R8T6as the core of the two-phase hybrid stepper motor driver, both the hardware and software of the multi-output stepper motor driver are designed. Its hardware section contains the isolation circuit of external input signals, the filtering circuit, the processing unit for the button and LCD, the driver amplifier circuit, the sampling circuit for the current, the over-temperature protection circuit, the power processing circuit and etc. Its software design includes the treatment of the interrupt for the input pulses, the outputting of the PWM based on the technique of the current vector even rotation with constant amplitude, the processing of the width and phase for the PWM, the sampling of the current, the adjusting of the duty ratio with the PI controller and so on. In addition, a technique of solving the key problem in the software and hardware design of the stepper motor driver is proposed and a scheme of achieving the scalable multi-output driver is presented in the paper. The model of expansion slot is applied to implement the technique of controlling with the multiple stepper motors. Firstly, the enabling bit is used to enable the expansion slot of the multi-output motor driver. Then, the multiple input signals are processed in the same external interrupt in the real time, and the PWM is generated and enabled to control the operation of the stepper motors.The designed driver for the two-phase hybrid stepper motor has some important advantages. The stepper motor runs smoothly when it is motivated by the designed driver. When the motor runs, the noise and the vibration at the low speed is small and the output torque keeps basically constant when the speed of the motor becomes higher. And the driver can drive two or more motors at the same time. Thus, using the designed driver, the operating performance of the stepper motor is improved and the operation precision is increased. The designed motor will play a positive role for promoting the application of the two-phase hybrid stepper motor.