Method for suppressing bias current of magnetic element of dual active bridge converter

Abstract

The invention relates to the DC conversion technology and aims to provide a method for suppressing the bias current of a magnetic element of a dual active bridge converter. The method is characterizedin that at least one of a steady state current controller or a transient current controller is added to a control circuit of the dual active bridge converter, the steady state current controller canmake difference between an average value of the transformer current and zero, a switch tube driving duty ratio compensation signal is generated by a compensator and is used for superimposing with an original 50% driving duty ratio to generate a final PWM signal, the transient current controller is used for performing threshold comparison, pulse signal generation and logic operation, and a drivingsignal generated by the transformer can reverse a voltage of a primary or secondary side of the transformer in advance to suppress the instantaneous current amplitude. The method is advantaged in thatthe method can simultaneously suppress the steady and transient bias current in the magnetic element of the DAB converter, reduces switching and conduction loss caused by the bias current, improves reliability of the DAB converter, removes a traditional DC blocking capacitor used to suppress the bias current and significantly reduces the size of the DAB converter.

Description

technical field [0001] The invention relates to a DC conversion technology in the technical field of power electronics, in particular to a method for suppressing the bias current of a magnetic element of a dual active bridge converter. Background technique [0002] Dual Active Bridge (DAB) DC-DC converter has the advantages of wide voltage operating range, automatic bidirectional flow of energy, and easy realization of soft switching. Good application prospects. However, due to the asymmetry of the control sequence and circuit parameters of DAB, DC bias current will appear in the high-frequency transformer and inductor. Bias currents can cause power devices to lose soft switching, increase switching and conduction losses, and reduce efficiency. Excessive bias currents can also cause magnetic components to saturate and eventually burn out the circuit. The traditional bias current suppression method is to connect DC blocking capacitors in series, which will significantly inc...

AI Technical Summary

Problems solved by technology

However, due to the asymmetry of the control sequence and circuit parameters of DAB, there will be DC bias current in the high-frequency transformer and inductor

Bias current can cause power devices to lose soft switching, increase switching and conduction losses, reduce efficiency, excessive bias current can also cause magnetic components to saturate, and eventually burn out the circuit

The traditional bias current suppression method is to connect DC blocking capacitors in series, which will significantly increase the size and cost of the converter

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