Control system and control method for frequency interpolation pattern cascading off-line PFC-PWM switch power converter

Abstract

The invention provides a control system and a control method for a frequency interpolation pattern cascading off-line PFC-PWM switch power converter. An PFC module converts an AC voltage to a DC voltage; a control signal of a first switch block of a PFC module is generated by a PFC control signal generation module; the input current of the PFC module is adjusted and the DC voltage output by a first capacitor is steadily kept at the set value; a PWM module converts the output voltage of the PFC module to the output voltage of the control system; a control signal of a second switch block is generated by a frequency interpolation pattern PWM control signal generation module, so that the output voltage of the control system reaches the set DC voltage value; when the first capacitor is charged, the second capacitor is charged at intervals. The invention has the advantages of improving the frequency feature of the DC-DC part, reducing the ripple voltage of the capacitor and the cost, and improving the power factor adjusting coefficients of the cascading off-line PFC-PWM switch power converter.

Description

technical field [0001] The invention relates to off-line switching power converter technology, in particular to a cascaded off-line PFC-PWM switching power converter control system and method. Background technique [0002] At present, the switching power converter control system, especially the high-power switching power converter control system, widely adopts the synchronous control mode cascaded PFC-PWM switching power converter control system, and its control loop is simple, without slope compensation and frequency compensation. , The required peripheral components are less, which is convenient for customers to use. [0003] Such as figure 1 The synchronous control mode cascaded PFC-PWM switching power converter control system shown includes two-stage circuits, wherein the first stage is a step-up power factor adjustment circuit, including a PFC module (10) and a PFC control signal generation module (12) , the PFC module (10) includes an inductor L1, a switch SW1, a swi...

AI Technical Summary

Problems solved by technology

[0013] The disadvantages of the cascaded PFC-PWM switching power converter control system in the above synchronous control mode are: since PFC and PWM use synchronous clocks, PFC and PWM can only use the same operating frequency

Since the operating frequency of the first-stage converter is limited by the power frequency, the frequency is lower

When the second-stage converter uses a synchronous clock, it means that the operating frequency of the second-stage converter is also limited

Second-stage converters have frequency limitations for faster and more precise voltage control

But at this time, the time when SCV1 and SCV3 are turned on at the same time will be reduced to as follows figure 1 The synchronous control mode shown in cascaded half of the PFC-PWM switching power converter control system will result in larger ripple

Images