调频式谐振特高压试验电源最优PWM波形分析与实现

针对新型调频式谐振特高压试验电源(UHV frequencytuned resonant test power supply,UHV-FTRTPS)输出信号频率较宽,不易获得最佳波形这一问题,提出了一种新的特高压试验电源方案。在167～300 Hz高频率段,采用同步正弦脉宽调制(sinusoidal pulse-width modulation,SPWM),把载波比N的数值选择与输出滤波器本身结构相结合,得到合理的最佳N值和滤波器最小视在功率。同时,在30～167 Hz低频率段,采用特定次谐波消除方法在线计算各开关角度,消弱低次谐波,把低次谐波转移到高次谐波,以利于输出滤波器滤除。最后,在输出滤波器电容上串联1个虚拟电阻,在不增加硬件及不改变输出滤波器结构的基础上,从软件控制方法上来增强其阻尼性,使之更好地滤除高次谐波。仿真及试验结果验证了该方案的正确性和有效性,对新型特高压试验电源的工程应用及产品化具有一定的指导和借鉴作用。

Analysis and Implementation of Optimal PWM Waveform of Frequency-Tuned Resonant Test Power Supply for UHVAC Power Transmission Equipment

In allusion to the problem of the wide frequency range of output signals of new type of UHV frequency-tuned resonant test power supply(FTRTPS) for UHVAC power transmission equipment and the difficulty to attain optimal waveform,a new scheme for UHV FTRTPS is proposed.In the higher frequency range from 167 Hz to 300 Hz,the output waveform is modulated by sinusoidal pulse-width modulation(SPWM) and the selection of carrier wave ratio N is combined with its own structure of output filter to attain reasonable value of N and minimum apparent power of the filter.Meanwhile,in the lower frequency range from 30 Hz to 167 Hz,a method of eliminating specified orders of harmonics is adopted to perform on-line calculation of switching angles,impair low-order harmonics and transfer low-order harmonics to high-order harmonics to facilitate the filtering of harmonics.Finally,a virtual resistance is connected in series to the capacitor of output filter,thus without adding extra hardware and changing the structure of output filter its damping is intensified by control software,therefore the filtering of high-order harmonics becomes better.The correctness and effectiveness of the proposed method are verified by simulation and test results.