Research on the precise control method based on the new style PWM with variable pulse width

It has been a very common application of the DC-motor PWM speed regulation system based on the speed and current dual-closed-loop control strategy. To improve the control accuracy of current loop in speed regulation system and to further relax the dependence of the regulation system on the performance and the speed of the microcontroller, A new accurate PWM control method with variable pulse width is proposed in this paper based on the dual-closed-loop speed regulation principle and the frequency conditions which guaranteeing the current of the armature coil is continuous. The proposed method employs a common microcontroller to generate non-uniform PWM multi pulse whose average value is used to improve the accuracy of the armature voltage. Then the control mode can be changed from the uniform PWM one to the non-uniform PWM one under stated conditions. Finally, an experiment is carried out, in which an 8-bit microcontroller is used to generate non-uniform PWM multi pulse to control the PWM driving FET. Experiment results show that the accuracy of the average voltage of PWM can reach to millesimal by applying the newly proposed method, which is illustrated by the experimental data and pulse waveform. Therefore, it is demonstrated that the proposed method is applicable in the practical applications.