The Design Of A Novel High-Subdivision Stepping Motor Driving System

The stepping motor is widely used in the industry control, which has advantages of low cost and simple driving circuit. With the development of programmable logic device, the technology of the motor control is developing in direction of the digitalization. The fully digitized control for the three-phase hybrid stepping motor is deeply studied. A novel integrated driving system of the three-phase hybrid stepping motor is developed based on FPGA. The system can be reconstructed by using programmable technology and has advantages of lower design cost and better performance.At first, focusing on the disadvantages of oscillation and losing step of the three-phase hybrid stepping motor at opened-loop, the scheme of the sine-wave subdivision driving is presented by analyzing of operating characteristic of the stepping motor. By analyzing of the precision of operation at subdivision, the auto-adjustment of best subdivision level is designed taking the least speed error as the criterion. The regulation algorithm of closed-loop current of control system is improved, and the regulating methods of the traditional PID and parameter self-regulation Fuzzy-PID are applied respectively at different operating states. Therefore, the self-adapting performance of control system is enhanced.Secondly, the hardware system for three-phase hybrid stepping motor is developed. The controller and driver are integrated on a piece of FPGA, which implements the integrated control and enhances the anti-interference ability. The IPM is applied for power unit to drive the motor. The high-precision hall current sensor is applied for feedback unit to sample the winding current. This hardware construction has advantages of small volume, reliable performance, strong driving ability and low cost.Thirdly, using the module design method from top to bottom, all modules of the motor control system are programmed by VHDL at Xilinx ise7.1, and the programs are synthesized, implemented and simulated. The current, speed and direction control of the stepping motor, PID regulation and PWM modulation are realized by digital hardware logic circuit. And the system is optimized making the system operation at 200MHz, thus raising the system control precision.In the end, after a large amount of experiments were carried on, the current waveforms of the stator winding at the different speed are given. The experimental results indicate that the developed integrated sine-wave subdivision driving control system of the three-phase hybrid stepping motor has superior control characteristics, which can drive the three-phase hybrid stepping motor to run smoothly at different subdivision level, at the same time it improves the performance of the stepping motor at low frequency.