Method and device for controlling peak power output of power supplier

Abstract

The invention discloses a method for controlling peak power output of power supplier. The power supplier determines the working period of a power switch by comparing a current sensing signal and a dynamically adjustable current limiting threshold, the current sensing signal represents the magnitude of current in the power switch. The invention is characterized in that the method comprises the following steps: A. supplying the present current limiting threshold; and B. estimating the next current limiting threshold according to the present current limiting threshold and the current sensing signal. The method and device for controlling peak power output of power supplier in the invention have the advantage of narrowing error range of output power of power supplier.

Description

technical field [0001] The present invention relates to a power supply, in particular to a control method and device for the power supply. Background technique [0002] A flyback power supply is a buck / boost converter that uses a two-winding inductor to provide electrical isolation and non-inverting output. Its energy storage and conversion is through the The charging and discharging of the secondary coil inductance. For a universal input (universal input) flyback converter, it usually operates in continuous conduction mode (CCM) at low input voltage (low line), and operates at high input voltage (high line) In discontinuous conduction mode (discontinuous conduction mode; DCM), to obtain better efficiency. However, the propagation delay of the flyback power supply causes the maximum output power of the power supply to vary with the magnitude of the input voltage (line voltage). Propagation delay is the cumulative result from the current-limit comparator, to the pulse-widt...

AI Technical Summary

Problems solved by technology

Although this method is simple and direct, it also has the following disadvantages: (1) Although this control is a single method to apply to all applications (one size fits all), the built-in waveform is based on a set of most commonly used power supply range determined by system parameter calculations

Although the system designer can obtain better output power convergence (convergence) by fine-tuning the parameters to conform to the built-in waveform, however, some parameters such as performance, electromagnetic interference (EMI), heat, etc. must be compromised, These parameters will affect the primary inductor, current sense resistor, gate driver resistor, etc., and the output power will usually deviate from the original design, which forces the system designer to spend more time or add additional components to solve the problem

In addition, it is often found in practice that some system designs achieve better output power convergence when using controllers from certain vendors, but worse when replacing them with other controllers

(2) Another disadvantage of this method is more serious

Sometimes the system design requires a larger primary side inductance, and its current slope is smaller or slightly higher than the slope of the current limit value at low input voltage, which will cause the current sensing waveform to fail to touch the current limit value waveform before reaching the maximum cycle, and finally , the output voltage cannot be adjusted and the output power limit is lost

(3) Due to the time-varying waveform of individual cycles, it is difficult to establish a quick test in mass production, so it is difficult to define its waveform error range in the product data (datasheet), and the waveform error range is very important for predicting the output power error range important

[0007] Therefore, there are above-mentioned inconveniences and problems in the known power supply

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