A Resonant Converter Current Detection and Control Method

Abstract

The invention discloses a current detection and control method of a resonant converter. The current of the controlled branch is converted into a positive polarity induction signal through a current sampling circuit, and the induction signal is integrated through a resettable integration circuit and then output to a digital controller. The ADC module performs sampling, and the current operation unit calculates the average current information of the controlled branch in the integration time period according to the sampling value. After the operation of the current regulator, the PWM module and the drive amplifier unit output the drive signal, and the converter switch bridge arm Take control and reset the resettable integrating circuit. The invention can rapidly detect and control the current of the resonant converter, and improves the dynamic performance of the converter.

Description

technical field [0001] The invention discloses a current detection and control method for a resonant converter, which belongs to the technical field of power electronic converters. Background technique [0002] The resonant converter refers to the use of the characteristics of the current and voltage periodic zero-crossing of the resonant elements such as inductors and capacitors in the circuit when resonance occurs, so that the switching device can realize zero-voltage (ZVS) or zero-current (ZCS) switching, that is, soft switching. The switching power supply tends to be high frequency and miniaturized, so it has been widely used in high frequency switching power supply occasions. The working principle of the commonly used DC-DC resonant converter is that the DC input voltage generates a square wave voltage after passing through the switching bridge arm, which is applied to both ends of the resonant cavity to resonate the resonant circuit, and the resonant voltage or resonan...

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Problems solved by technology

[0004] Although the application of the current loop improves the performance of the LLC resonant converter, it is well known that the current waveform of the resonant converter is not regular and changes with the change of operating conditions, so it cannot be obtained by simply detecting the peak or instantaneous value. The average current of the resonant converter, so the low-pass filter is mostly used in the prior art to filter the induced voltage signal generated by the irregular current signal to obtain the average value information, as described in the US invention patent with the announcement number US8541997B2

The low-pass filter used in this case usually has a very low cut-off frequency. If a low-pass filter is used in the added current loop to obtain the average current information of the resonant converter, the bandwidth of the current loop is limited, and the current control effect is poor. When the dynamic process is severe, the converter may still have a large inrush current in the resonant cavity, which reduces the dynamic performance of the converter

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