Research And Design Of ESP High-frequency Power Supply Based On Resonant Soft Switch

Electrostatic precipitation (ESP) is the primary technology for resolving industrial dust pollution, since it can control a mass of smoke with high efficiency and easy maintenance. Conventional ESP frequency high voltage power supply (HVPS) has several shortcomings: great bulk, low efficiency and slow real-time response, which restricts further improvement of ESP collection efficiency. High-frequency HVPS overcomes above-mentioned deficiencies and has been a development trend of ESP high voltage power supply. This paper achieves main circuit design of high frequency HVPS, hardware structure and software control algorithm of control unit for power supply based on detailed study of LCC resonant soft switch.Series Parallel Resonant Convertor (LCC) combined with soft switching could utilize the parasitic elements of the transformer, such as leakage inductance and parallel capacitance as resonant elements. Zero Current Switching at IGBT turning-on and Zero Current Switching at turning-off can be achieved. A complete study of the DCM invertor operating at four topological modes is presented. The key parameters of resonant circuit are given to aid the circuit design.Two control strategies are suitable for LCC circuit to realize soft-switching for a wide operation range:variable frequency control and variable phase control. The strategy of variable frequency with fixed pulse width is utilized in this design to change the inverter’s switching frequency and achieve ZCS. Spark detection and control methods are proposed to aid the closed-loop control of output voltage.The ESP power supply system of this paper has been put into use at a power plant in Tangshan City. The actual operating data and waveform verified the characteristics of soft switching.