Switching frequency period modulated triangle wave generating circuit

Abstract

This invention relates to a triangle wave generating circuit for modulating a switch frequency period composed of a modulation wave circuit and a triangle wave circuit, in which, the input of the modulation wave circuit is sine half-wave voltage to be processed by a branch circuit and a follow circuit and added with a DC bias component to get a modulated wave voltage after shift, the triangle wave circuit inputs said modulation wave voltage to generate triangle wave voltage signals modulating the frequency period via a charge and discharge circuit and comparing circuit to be output via a voltage follower, which generates triangle wave signal with the switch frequency varying along with the sine half-wave period as the carrier signal to reduce the magnetic interference intensity of the system based on the theory of voltage-frequency conversion.

Description

technical field [0001] The present invention relates to a triangular wave generating circuit with periodic modulation of switching frequency, in particular to an active power electronic converter suitable for active power factor correction (PFC), active power filter (APF) and switching power supply (SMPS). The triangular wave generating circuit whose switching frequency is modulated according to the law of the sine half wave has a very wide range of applications. Background technique [0002] Since power electronic conversion technology generally adopts high-frequency PWM (pulse width modulation) chopping technology, high-intensity electromagnetic interference (EMI) will be generated, and power electronic conversion products must pass relevant EMI tests before they go on the market, such as continuous disturbance radiation, For test items such as power radiation, EMI design has already accounted for an important part of the initial product design cost, so suppressing EMI int...

AI Technical Summary

Problems solved by technology

The traditional PWM chopping technology adopts a fixed switching frequency modulation scheme. In its high-frequency harmonic distribution law, the interference level of the integer multiple of the switching frequency and its side frequency is quite high, and the interference level of other areas is relatively low, which belongs to narrow-band distribution. Certain spectral regions have difficulty passing quasi-peak and average EMI standard limits

For this reason, some new switching frequency modulation techniques have emerged, such as random modulation of switching frequency, random modulation of pulse position, and switching frequency jitter technology. The technology has not yet been popularized and applied in the field of power electronic converters, so it is necessary to find a switching frequency modulation technology that is simple and easy to implement and has a good EMI suppression effect

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