电除尘高压电源LCC变换器电流断续模式分析

Analysis of LCC Converter in Current Discontinuous Mode in Electrostatic Precipitators High Voltage Power Supply

为了克服串联谐振、并联谐振及LCC串并联谐振连续模式应用于高压大功率静电除尘电源方面的不足,采用LCC串并联电流断续模式进行设计。基于断续电流模式下的电路模型,采用时域状态法对串并联谐振变换器工作方式进行分析和数学描述,推导得出了变换器特性解析表达式,探讨了串并联电容比值对变换器输出电压的影响,深入研究了电流断续电流模式下变换器的电压增益以及效率特性。结果表明:电流断续工作模式实现了开关管的全时零电流开通及零电流/零电压关断;增加串并联电容的比值m,可以增大输出电压,但会降低效率;在一定的范围内增大开关频率可增大电压基准增益进而提高效率。仿真及样机实验表明:所做理论分析正确,将采用电流断续工作模式的LCC变换器在应用于电除尘高压大功率电源可行。

Applying resonant converters working in series resonance, parallel resonance and LCC series-parallel resonant continuous modes to power supply of high-voltage high power electrostatic precipitator has certain disadvantages. Hence, we designed a converter using the LCC series-parallel discontinuous current mode. On the basis of the circuit model of discontinuous current mode, we used the time-domain state method to analyze the working mode of series-parallel resonant converter and gave its mathematical description, then deduced the characteristic analytical expressions of the converter. At the same time, we discussed the influences of the ratio（m） of series capacitance to parallel capacitance on the output and voltage gain of the converter and efficiency characteristics in current discontinuous current mode. It is concluded that the proposed mode can realize the full-time zero current turn-on and the zero current/zero voltage turn-off of the converter. Moreover, increasing m will raise the output voltage, but reduce the efficiency of the converter. Meanwhile, the efficiency can be raised by increasing the switch frequency, which magnifies the reference voltage gain. Further simulation and tests with prototype verify our theoretical analysis, and prove that applying LCC converter in discontinuous current mode to the power supply of high-voltage high-power electrostatic precipitator is feasible.