An ARCP soft switch circuit with voltage clamp function

Abstract

The invention discloses an ARCP flexible switch circuit with voltage clamping function, which comprises a first master power switch and a second master power switch with one ends respectively connected with a DC power supply positive pole and a negative pole and the other ends connected with a filtering circuit; a series branch composed of a third switch and a resonant inductor with one end connected with a zero potential reference end of the DC power supply and the other end connected with the input end of a filtering circuit; and a fourth clamping fly-wheel switch and a fifth clamping fly-wheel switch with one ends respectively connected with the DC power supply positive pole and the negative pole and the other ends connected with one point between the third switch and the resonant inductor, and used for introducing the excess energy in the series branch to a circuit loop when the third switch is switched off. The inventive circuit can consume or absorb the excess energy in the resonant inductor, reduce the peak high voltage in the ARCP circuit due to the parasitic capacitance in the resonant inductor, improve the reliability and efficiency of the circuit, and has the advantage of low cost.

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. The schematic diagram of its circuit is shown in Figure 1. 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 ...

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Problems solved by technology

In this way, there will be P=1 / 2*L2*(13)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 Therefore, 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 The switching circuit has completely lost the use value of improving efficiency, and if the current 13 increases 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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