Asymmetric regular sampling SPWM method based on tangent approximation algorithm

  Objectives  In order to improve the quality of sinusoidal waveform output by the ship's high-frequency inverter charging device and reduce the CPU occupancy rate, an asymmetric regular sampling sinusoidal pulse width modulation (SPWM) method based on tangent approximation is proposed.

  Methods  According to the basic principle and calculation method of the asymmetric regular sampling SPWM method based on tangent approximation, a Matlab/Simulink simulation model is built, and then the software algorithm flow that can be used in the high-frequency inverter charging device is designed together with the actual output of the tangent approximation method. The effects are then compared and verified by experiments.

  Results  The simulation results show that under pure resistive load and resistive inductive load, the total harmonic distortion (THD) of the load-end waveform based on tangent approximation method is 2.12% and 2.08%, respectively, and its waveform quality is better than symmetric regular sampling. The experimental results show that the THD of load-end waveform based on the tangent approximation method is significantly lower than the symmetric regular sampling method. When the effective value of the input line voltage is 580 V (the modulation ratio is 0.8), the quality of the output waveform is relatively optimal.

  Conclusions  The asymmetric regular sampling SPWM method based on tangent approximation overcomes the shortcomings of the traditional symmetric regular sampling method, such as the low quality of the output waveform and the traditional asymmetric regular sampling method's high sampling frequency and high CPU occupancy rate. The research results can provide reference for the design of ship's high frequency inverter charging devices.