Power switch device pulse transformer isolation driving circuit

Abstract

The invention discloses a power switch device pulse transformer isolation driving circuit. The power switch device pulse transformer isolation driving circuit comprises a primary-side circuit, a pulse transformer Tr and a secondary-side circuit, wherein the primary-side circuit comprises an NPN transistor Q2, a PNP transistor Q3 and a blocking capacitor C1, and the secondary-side circuit comprises a power switch device Q1, a driving resistor Rg, a gate discharge resistor Rs, a diode D1, a compensation capacitor C2, a voltage-regulator tube Z1 and a negative pressure holding capacitor C3. The power switch device pulse transformer isolation driving circuit of the invention can be applied to all switching converters such as a boost converter, a buck converter, a forward converter, a flyback converter, a half-bridge switching converter, a half-bridge converter, a full-bridge converter and a push-pull converter, and can effectively improve the reliability of the switching converters.

Description

technical field [0001] The invention relates to the field of switch mode power converters, in particular to a pulse transformer isolation drive circuit for a power switching device in the power converter. Background technique [0002] In switch-mode power converters, power switching devices often need to be isolated and driven. The conventional method is to use optocoupler isolation plus a power amplifier circuit to drive the power switching devices, but this method requires an independent isolated driving power supply, which will increase additional costs. and circuit complexity. In small and medium power applications, pulse transformers are usually used to isolate the drive circuit to reduce additional drive power and reduce costs, such as figure 1 As shown, it is the first pulse transformer isolation driving circuit, which includes transistor Q 2 and Q 3 , DC blocking capacitor C 1 , pulse transformer Tr, Q 1 is the power switching device MOSFET (or IGBT) in the conv...

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Problems solved by technology

It can be seen that after the pulse transformer Tr, the power switching device Q 1 The positive and negative amplitudes of the drive signal obtained are related to the duty cycle D of the PWM signal. When the duty cycle D is small, the positive amplitude of the drive signal is large, and the negative amplitude is small. When the value is large, the positive amplitude of the driving signal is small, and the negative amplitude is large, even failing to reach the Q of the power switching device. 1 required drive voltage amplitude, therefore, figure 1 The first pulse transformer isolated drive circuit shown is not suitable for applications with widely varying duty cycles

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