An on-load variable pwm controller

Abstract

The present invention provides an on-load variable PWM controller, which includes a frequency signal generation circuit and a main control circuit. The frequency signal generation circuit includes a shift register chip U2, and pin 1 of the shift register chip U2 is connected to a The number pins are connected by wires, the first branch of the No. 1 pin of the shift register chip U2 is connected to the output terminal of the inverter chip U4A through a wire, and the second branch is connected to the NAND gate chip U1C through a wire. The No. 9 pin of the shift register chip U2 is connected to the input end of the inverter chip U4C through a wire, and the No. 8 pin of the shift register chip U2 is connected to the output of the NAND chip U1A through a wire Compared with the prior art, the present invention has the following beneficial effects: the design realizes the function of seamless switching between duty cycle control and phase shift control, improves the full-scale output of the switching frequency under light load conditions, and reduces dummy load stress.

Description

technical field [0001] The invention is an on-load variable PWM controller, which belongs to the field of switching power supply equipment. Background technique [0002] Switching power supplies are widely used in modern industry and national defense and other fields. With the development of modern technology, the requirements for power level, voltage level, efficiency, volume and weight of the power supply continue to increase. Increasing the switching frequency is to reduce the volume and weight of the power converter. , an effective way to increase the power density of the converter, high-power AC / DC converters generally use the full-bridge topology technology of phase shift control, this method can obtain higher dv / dt values, and for all primary-side semiconductors of the power stage Provide zero-voltage switching. Traditional control methods mainly use integrated phase-shift control chips, such as UC38XX series PWM control ICs. The main advantage of this solution is to ...

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Problems solved by technology

[0002] Switching power supplies are widely used in modern industry and national defense and other fields. With the development of modern technology, the requirements for power level, voltage level, efficiency, volume and weight of the power supply continue to increase. Increasing the switching frequency is to reduce the volume and weight of the power converter. , an effective way to increase the power density of the converter, high-power AC / DC converters generally use the full-bridge topology technology of phase shift control, this method can obtain higher dv / dt values, and for all primary-side semiconductors of the power stage Provide zero-voltage switching. Traditional control methods mainly use integrated phase-shift control chips, such as UC38XX series PWM control ICs. The main advantage of this solution is to simplify the design steps and save debugging time. The existing control method phase-shift angle cannot be adjusted to Close to zero, when the switching frequency increases, it will cause the power supply’s no-load and small voltage output to be uncontrolled, and there is a fixed value output, which cannot meet the output requirements of the test power supply

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