Grinders and grinding wheel motors used in standard machining are operated according to the traditional starting circuit. After the motor is started, it operates at the rated speed. Due to the fluctuation of the grid voltage and the constant change of the abrasive load of the grinding wheel workpiece, the motor speed error will be affected. The standard grinding wheel motor starting circuit generally has only one processing speed, which is difficult to adapt to different workpiece sizes and require different processing relative linear speeds, so that the processing precision of the processed workpiece is difficult to guarantee. Therefore, from the aspects of improving the processing quality and efficiency, saving energy and so on, the application of frequency conversion speed regulation technology to grinding machines can achieve satisfactory results. The machining industry processes a wide range of products, different sizes of workpieces, and requires different processing accuracy. It is required that the speed of the grinding wheel is different from the speed of the main axis. It is difficult to adjust the speed of the main axis to meet the linear speed of the workpiece processing. In addition, due to the stress bending generated during the processing of shaft rods, the grinding process will produce different feed torques of the grinding wheel, which will lead to different changes in the output speed/torque of the grinding wheel, which will correspondingly produce chattering/burning lines, etc. It is difficult to ensure the grinding accuracy, which will result in low production efficiency and low rate of high-quality products. With the development of power electronics technology, frequency conversion speed regulation technology is becoming more and more popular, and the application of frequency converter in mechanical processing industry has achieved good results. Among them, the stepless speed regulation of frequency converter, soft start and constant torque output greatly meet the requirements of machining equipment for constant speed/constant torque.