A Method to Eliminate Subharmonic Oscillation of Switching Power Supply

Abstract

The invention relates to a method for eliminating the sub-harmonic oscillation of a switching power supply. The method is based on a control system comprising a sampling module, an error calculation module, a proportion integration differentiation (PID) module and a pulse modulation module; the control system is connected with the controlled switching power supply, so that a closed loop is formed. The sampling module is used for sampling the output voltage of the switching power supply and calculating so as to obtain Vo; the error calculation module subtracts the Vo from a reference voltage Vref so as to obtain current sampling error e1; the PID module performs PID operation according to the error e1 and PI parameter values so as to obtain a compensation result VPI, and outputs same to the pulse modulation module; the pulse modulation module outputs duty for controlling the switching power supply. According to the method, a time length calculation module and a sub-harmonic cancellation module are additionally arranged, the time length calculation module is used for calculating different switching time lengths, the sub-harmonic cancellation module can be further used for determining a compensation function and calculating the compensation quantity of control current, and the sub-harmonic oscillation can be eliminated by compensating the control current.

Description

technical field [0001] The invention relates to a switching power supply converter. Subharmonic oscillation may occur after the switching power supply is introduced into a current control method. The invention provides a method for eliminating the subharmonic oscillation of the switching power supply. Background technique [0002] Switching power supplies are usually used as power supplies for various types of electrical equipment to convert unadjusted AC or DC input voltages into adjusted AC or DC output voltages. In switching current control systems, control methods such as peak current control and average current control are often used. Since the switching power supply needs to adapt to different working conditions, the anti-interference ability is very important. After introducing these control methods, there may be sub-harmonic oscillations caused by disturbances. This subharmonic oscillation is due to the initial disturbance of the inductor current (which can be expre...

AI Technical Summary

Problems solved by technology

However, the implementation of slope compensation is more difficult. Its digital implementation requires a high-speed DAC to generate the slope, or an ADC to obtain the sampling current, which will make the circuit cost too high and fail to achieve the purpose of reducing the size of the device.

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