An ARCP soft switch circuit with voltage clamp function

Abstract

The invention discloses an ARCP soft switch circuit with a voltage clamping function, which comprises a first main power switch, a second main power switch, a series branch composed of a third switch and a resonant inductance, and a fourth clamping freewheeling circuit switch and the fifth clamping freewheeling switch, wherein the fourth clamping freewheeling switch and the fifth clamping freewheeling switch are used to introduce excess energy in the series branch into the circuit loop when the third switch is turned off, One end of the fourth clamp freewheeling switch is connected to the positive pole of the DC power supply, and the other end is connected to a point between the third switch and the resonant inductor. One end of the fifth clamping freewheeling switch is connected to the negative pole of the DC power supply, and the other end is connected to the third switch One point is connected with the resonant inductance. The circuit of the invention can consume or absorb excess energy in the resonant inductance, reduce the peak high voltage of the ARCP circuit caused by the parasitic capacitance of the resonant inductance, improve the reliability and efficiency of the circuit, and have the advantage of low cost at the same time.

Description

technical field [0001] The invention relates to a soft switching circuit, in particular to an ARCP soft switching circuit with a voltage clamping function. Background technique [0002] Among the current soft switching circuits, there is an ARCP (auxiliaryresonant commutated pole) soft switching circuit in the form of "inductor + switch" series connection, which is favored by many switching power supply industry personnel because of its simple hardware circuit, easy control and good effect. Its circuit schematic diagram is as figure 1 shown. The main idea of ​​this circuit is to generate a resonant current I2 on the resonant inductance L2 through the auxiliary switch SW3 in the same direction as the current I1 of the main circuit filter inductance L1, through which the soft switching (ZVS) of the main power switch tubes SW1 and SW2 can be realized . [0003] From the analysis of the working principle of the circuit, it can be seen that for the auxiliary switch tube SW3, i...

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Problems solved by technology

In this way, there will be P=1 / 2*L2*(I3)2 energy in the inductor L2 at the moment when the switch tube SW3 is turned off, and the original circuit does not provide a circuit that consumes this part of energy, nor does it provide a discharge path, so this part of the energy will generate a very high SPIKE peak voltage between the two ends of SW3—that is, between point A and point N, which is theoretically infinite, which is enough to damage the switch tube SW3 and cause the circuit to fail

[0004] The above problems are not only caused by the existence of parasitic capacitance C4: when the circuit input voltage, output load and other reference quantities change suddenly, or when the main switch tube SW1 and SW2 drive abnormally, and when the circuit just starts to start, the above problems will occur

But for the ARCP soft switching circuit topology, the situation is completely different: the inductance that causes the peak voltage across the switch tube is not leakage inductance or parasitic inductance, but the resonant inductance L2 used to realize soft switching. Usually this inductance is On the order of millihenry (for a single-phase 30KVA / 480V half-bridge inverter circuit, the inductance of this resonant inductance is 10 millihenry), the energy stored in the inductance that generates the peak voltage P=1 / 2*L2*(I3) 2 It is proportional to the inductance value. Since the inductance value in the ARCP circuit is an order of magnitude (1000 times) larger than the leakage inductance or parasitic inductance in the usual power electronic circuit, the energy in the inductor is correspondingly 1000 times larger under the same current times, if the RC or RCD snubber circuit used in general circuits is used, the required power of the snubber circuit capacitance and resistance should be increased by about 1000 times, which will make the snubber circuit very large, and because the RC and RCD snubber snubber circuits belong to Energy consumption type, that is, P=1 / 2*L2*(I3)2 is completely consumed, if the ARCP soft switch circuit also adopts the usual consumption absorption, it will not only cause the volume to be too large, but also cause low efficiency, making the soft switch circuit The switching circuit completely loses the use value of improving efficiency, and if the current I3 is considered to increase with the increase of power, it is very likely that the efficiency will not increase but decrease after the ARCP circuit is adopted.

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