Adjustable pulse width control power supply conversion method and device

Abstract

The invention relates to an adjustable pulse width control power supply conversion method and device, wherein the device comprises an adjustable pulse width PFM control circuit, a PWM control circuit, a PWM / PFM switching unit, a switch circuit and a load state detection circuit; and before a PWM mode is switched into a PFM mode, the grade is increased by preset pulse width, the pulse width of a PFM control signal of a sequence is gradually adjusted from low to high sequentially to an optimum pulse width valve, and then the output voltage is supplied to the load by the PFM mode, so that the output voltage wave form when in the PFM mode can be improved, and the output stability of the power supply conversion device is better.

Description

technical field [0001] The invention relates to the design of a power conversion device, in particular to a power conversion method and device with adjustable pulse width control. Background technique [0002] In increasingly complex electronic and computer system devices, power conversion devices play a pivotal role. refer to figure 1 As shown, it is a control circuit diagram showing a known power conversion device. The known power conversion device 100 is mainly composed of a control logic circuit 1 that generates a sequence of pulse control signals Pout1 to control the switch circuit 2, so that the semiconductor elements (such as MOSFETs) in the switch circuit 2 are turned on or off, and then passed through a filter circuit 21. The input voltage source Vin is converted into the output voltage Vout1 required by the load 3 . [0003] The control logic circuit 1 generally adopts pulse width modulation (Pulse Width Modulation, PWM) mode for output control. The characterist...

AI Technical Summary

Problems solved by technology

[0006] However, it is known that the power conversion device that switches from PWM mode to PFM mode at light load, because the switching voltage difference, load size, and external components (inductor, capacitor) are ignored when operating in PFM mode, the pulse width of the pulse control signal is uniform. is a fixed value, so in PFM mode, the output voltage waveform (refer to image 3 ) relatively speaking than the output voltage waveform when working in PWM mode (refer to figure 2 ) is large, and the output voltage waveform will also become larger with the increase of the voltage difference, which becomes the problem of this type of power conversion device

Images