A Novel Pollution-Free High-Power Switching Power Supply

The technology of high frequency of switching power supply "20 KHz power supply technique revolution" that brings, not only in the direct current steady power supply field to play the predominant position, at the field of many industry power supply such as the electric arc machine, the high frequency inductive to heat, the aviation power supply, and the laser power supply etc., but also got the extensive application with the development. The wide application of Switching-Mode-Power- Supply (SMPS), especially high power SMPS brings "pollution" to power system. What have made a large amount of harmonic and high Electro-Magnetic Interference (EMI) has two reasons. The first reason is mainly the hard-switching PWM mode. The switch turns on at high voltage and turns off at high current in a short time (ns), which leads to a high du/dt and di/dt and EMI. The second reason is the nonlinear rectifier with a bulky capacitor in the input stage of the SMPS, which leads to a narrow pulse and rich harmonics. It is reported that the total harmonic distortion (THD) of the single-phase power supply is 100% above which beyond the China standard and international standard such as IEC 1000-10-3-2, IEEE 519, IEC 555-2, IEC 6100-3-2 etc. by a long way. For this, the many power factor correctors to resolve the best method of this problem has been developed and manufactured out.To dissolve the switching power supply electro magnetism pollution towards environment, soft-switching PWM mode has been used instead of hard-switching PWM mode and a PFC stage has been added normally. The two-stage converter has some disadvantages such as the complexity, high cost and low efficiency. The other way is to use a single-stage power processor to correct power factor and regulate voltage simultaneously. However, the technology has only been applied in low power of single-phase AC input and has no use in high power of three-phase.So, the three-phase high power supply as the main EMI equipment is becoming one of the hot points in international research.A novel high-power pollution-free SMPS is presented in this paper, which accomplishes simultaneously the goal of soft-switching PWM, the input/output isolation, the output voltage regulation and three-phase PFC with a single-stage power processor and simple pseudo-phase-shift control circuit. Therefore, compared with the normal two-stage system, the single-stage power supply has simpler structure, lower cost, higher efficiency and easier to control. The proposed SMPS can be used in the three-phase power system, and can output high power over KW-order and input/output (I/O) isolation DC power supply.Its operation process principle and critical parameters are analyzed and discussed. At last, the computer simulation and experiment of the proposed SMPS give the excellent proof to feasibility and validity.