Full-Bridge Resonant Converter Control Using Primary-Side Charge Sensing
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Solution Overview
Problem
Conventional dual-loop control methods for full-bridge series resonant converters result in limited bandwidth and poor dynamic response, and the use of a Rogowski coil on the secondary side for current sensing limits the dynamic response and fails to eliminate output voltage and current ripples.
Innovation Solution
A resonant converter design that utilizes a current sensor on the primary side to acquire an electric charge signal through double integration, controlling the operation of primary switches based on this signal, input, and output voltages to improve dynamic response and eliminate ripples.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If dual-loop control with variable-frequency modulation is used, then voltage and current control is achieved, but bandwidth is limited and dynamic response is poor
Solution Approach 1:
The patent changes the control parameter from voltage/frequency to electric charge. By measuring the electric charge directly through a current sensor and double integration, the control system achieves a tenfold increase in bandwidth while maintaining reliable voltage and current control through the charge-based feedback mechanism
2Measurement precision
If Rogowski coil is disposed on the secondary side for current sensing, then current differential signal is obtained, but dynamic response is limited and output ripples cannot be eliminated
Solution Approach 1:
Instead of sensing current on the secondary side as in conventional approaches, the patent inverts the sensing location to the primary side. By placing the current sensor on the primary side and measuring the resonant current directly, the system achieves both precise measurement and fast dynamic response, effectively eliminating output ripples
Data Source
AI summary
A resonant converter including a full-bridge switch circuit, a resonant circuit, a transformer, a rectifier circuit, a current sensor and a controller is provided. The full-bridge switch circuit includes switches. The resonant circuit is electrically connected to the full-bridge switch circuit and includes a resonant inductor. The transformer includes primary and secondary windings, and the primary winding is electrically connected to the resonant circuit. The rectifier circuit is electrically connected to the secondary winding. The current sensor is electrically connected to the resonant circuit. When a current flowing through the resonant inductor passes through the current sensor, the current sensor generates a current differential signal correspondingly. The controller performs double integration on the current differential signal to acquire an electric charge signal and controls operation of the switches of the full-bridge switch circuit according to the electric charge signal and the input and output voltages of the resonant converter.