Zero-voltage switch insoalting transformer with fixed transmission ratio

Abstract

The invention relates to an insulated converter with zero voltage switch and fixed transmission rate. The secondary winding of high frequency transformer via rectification unit is connected to outputting filtering capacitance directly. In topology such as single end positive excitation, push-pull, semi bridge and full bridge, the catching diode is connected to high frequency choking inductance in parallel, and then they are cascaded into networks in side of supplied power. The control circuit uses conventional integrated circuit of pulse-duration modulation as main body. The turning on or off of the power switch and rectifying diode can be realized at zero voltage within full load region and full inputting voltage region, since changed circuit structure and optimized controlling mode of powre switch in the invention. Thus the shortcomings of large electromagnetic interference and large dissipation in traditional technique are solved in the invention.

Description

technical field [0001] The present invention relates to a switch isolation converter, in particular to a fixed transmission ratio zero-voltage switch isolation converter with small switching loss and electromagnetic interference. In the full load range and full input voltage range, its power switch and rectifier diode are Switching function is realized under zero voltage condition. Background technique [0002] In a conventional high-frequency switching converter, the power switch as a regulating tube works in an alternate switching state, the voltage at both ends is approximately zero when it is turned on, and the current passing through it is approximately zero when it is turned off, so the conduction and The power consumption during the turn-off period is approximately zero; but the transition between on and off is not completed instantaneously. During the transition process, the voltage at both ends and the passing current are not zero, and their product is the power swi...

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Problems solved by technology

For the same reason, image 3 , Figure 4 and Figure 5 Medium power switches and rectifier diodes have large switching losses, and image 3 and Figure 4 It also requires a driving pulse with a duty cycle DUTY≥50%, which cannot be directly applied to a common PWM (pulse width modulation) chip

[0007] The above description explains, figure 1 , image 3 , Figure 4 and Figure 5 The power switch and rectifier diode in the high-frequency switching isolation converter with fixed transmission ratio in the prior art shown are all working in the state of hard switching, which has large switching loss and electromagnetic interference

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