Intensified full-bridge phase-shift soft switch method and converter

Abstract

This invention relates a reinforcement full bridge phase-shift soft-switch method and a converter used in power source or power system, including a full bridge phase-shift circuit made up from switchtubes and a primary side end inductor L1 serial-connected to the transformer. It is characterized by the said full bridge phase-shift circuit connecting to the voltage resonant network which enables delayed switch tubes to have the complete zero voltage when turned-on, and to suppress the peak voltage of output commutation diode. The voltage resonant network comprises connecting points parallel-connected to the transformer primaryside, inductory L1 connecting point, capacitor C1 at both ends of input voltage, diode D1 and capacitor C2 and diode D2 to form voltage resonance via inductor L1 serial-connected to the transformer primary side.

Description

[technical field] [0001] The invention relates to a conversion method and equipment for a power supply or a similar power system, in particular to an enhanced full-bridge phase-shifting soft switching method and a converter. [Background technique] [0002] The full-bridge phase-shift soft switching technology can realize the zero-voltage turn-on of the switch tube, and has been widely used in high-power applications. Its basic topology is as follows: figure 1 as shown, figure 1 The four switching tubes Q1, Q2, Q3 and Q4 are driven with a duty ratio close to 50%, wherein the switching tubes Q1 and Q2 are driven complementary, and the switching tubes Q3 and Q4 are driven complementary; the driving of the switching tube Q4 is delayed by a certain amount relative to the switching tube Q1 Assuming that the initial state is that the switch tube Q1 and Q4 are turned on, the energy is transferred from the primary side to the secondary side. Assuming that the output rectifier tube D...

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Problems solved by technology

[0004] 1. The energy of the junction capacitance of the lagging arm is small, so it may not be able to achieve zero voltage turn-on at light load, so the light load loss is large

[0005] 2. The commutation process of the output rectifier tube causes voltage oscillation at both ends, increasing diode loss and voltage stress

[0006] In order to solve the above problems, at present, some use auxiliary network, such as figure 2 As shown, the principle is that when the switch tube Q3 or Q4 is turned on, the auxiliary capacitor and the inductor resonate. When the voltage across the capacitor is zero, the anti-parallel diode conducts, and the current in the auxiliary inductor remains approximately constant. When the switch tube Q3 or Q4 When it is turned off, the current in the resonant inductor and the current in the inductor L1 drain the energy of the junction capacitance of the switching tube Q3 and Q4 together, and the voltage oscillation during the commutation process of the output rectifier tube of this method still exists

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