Multi-Phase Resonant Converter With Duty-Cycle Control for Isolated OBCs
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Solution Overview
Problem
Existing Electric Vehicle On-Board Chargers (OBCs) face challenges in achieving efficient power conversion with galvanic isolation, wide voltage range support, and high power density, particularly in single-phase operation, as current two-stage systems are inefficient and require separate design for each stage.
Innovation Solution
A multi-phase resonant power converter with an AC stage and transformer, featuring primary and secondary bridge converter legs, and control circuitry that dynamically adjusts duty cycles based on input and output voltage ratios to support both buck and boost modes, enabling efficient power conversion and isolation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a two-stage system with PFC rectifier and isolated DC/DC converter is used, then galvanic isolation and power conversion are achieved, but the system complexity and number of converter stages increase
Solution Approach 1:
The patent combines the PFC rectifier and isolated DC/DC converter into a single integrated AC/DC converter stage. The high-frequency isolated single-stage topology merges functions that were previously separated into two distinct stages, reducing overall system complexity while maintaining galvanic isolation through the transformer.
Solution Approach 2:
The single-stage converter is designed to perform multiple functions simultaneously: power factor correction, galvanic isolation, and DC voltage regulation. This multi-functional approach eliminates the need for separate dedicated stages for each function, reducing device complexity.
2Device complexity
If a single-stage isolated AC/AC converter is used, then converter complexity is reduced, but limited output power and single-phase operation capability are achieved
Solution Approach 1:
The patent employs dynamic duty cycle control of the primary and secondary bridge converter legs to adapt the converter's output power and voltage. This dynamic control mechanism enables the single-stage converter to handle a wide range of output powers and accommodate both single-phase and three-phase operations, overcoming the limitations of fixed single-stage designs.
3Productivity
If duty cycle variation is implemented, then power conversion efficiency and voltage ratio adaptation are improved, but control complexity increases
Solution Approach 1:
The control circuitry implements feedback control by monitoring the AC input voltage and DC output voltage, then dynamically adjusting the duty cycles of primary and secondary switches accordingly. This feedback mechanism optimizes power conversion efficiency and maintains stable operation across varying voltage conditions.
Solution Approach 2:
The patent changes the operating parameters (duty cycles) of the primary and secondary bridge converter legs based on the voltage ratio between AC input and DC output. By dynamically adjusting these parameters, the converter adapts to different operating conditions while maintaining efficiency.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The proposed converter achieves efficient power conversion, supports single-phase and three-phase operations, provides galvanic isolation, and reduces complexity by integrating power factor correction and transformer into a single stage, enhancing operational flexibility and efficiency.
Implementation Method 1
a transformer having a respective primary side winding for each primary bridge converter leg of the AC stage. The transformer also has a respective secondary side winding for each primary side winding
Data Source
AI summary
Provided is a multi-phase resonant power converter circuit (100), comprising an AC stage (110). The AC stage (110) comprises a plurality of primary bridge converter legs (112), each configured to receive an AC input voltage and implement a separate phase of the multi-phase resonant power converter circuit (100). The multi-phase resonant power converter circuit (100) comprises a transformer (120) having a primary side winding (122) for each primary bridge converter leg (112) of the AC stage (110), and a secondary side winding (124) for each primary side winding. The multi-phase resonant power converter circuit comprises a DC stage. The DC stage comprises a plurality of secondary bridge converter legs, each electrically connected to a respective secondary side winding of the transformer. The multi-phase resonant power converter circuit comprises control circuitry configured to vary a duty cycle of switches of the primary and/or the secondary bridge converter legs.