Resonant Converter Secondary Control for Wide Voltage Boosting
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Solution Overview
Problem
Existing resonant converters struggle to achieve wide-range voltage boosting efficiently due to increased turn-off losses and unbalanced losses in secondary-side switches, which affect reliability and efficiency.
Innovation Solution
A method for controlling a resonant converter with diagonally arranged secondary half-bridges, alternating duty ratios of controllable switches in adjacent or spaced switching periods to form short-circuited loops, and using a controller to adjust duty ratios based on output voltage for symmetrical operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If secondary-side phase-shifting control is used to boost voltage, then voltage boosting capability is improved, but turn-off loss of secondary-side switches increases
Solution Approach 1:
The patent divides the secondary-side control into two independent half-bridges (first and second secondary half-bridges) with diagonally arranged controllable switches. Each half-bridge can be controlled independently with different duty ratios, allowing voltage boosting while distributing and balancing the switching losses across multiple switches rather than concentrating them in a single switch.
2Adaptability or versatility
If PWM control with asymmetric duty ratios is used at secondary side, then voltage boosting is achieved, but loss balance between switches deteriorates
Solution Approach 1:
The patent intentionally uses asymmetric duty ratios for the first and second controllable switches in different switching periods to achieve voltage boosting. The first controllable switch operates with a first duty ratio in a first switching period, while the second controllable switch operates with a second duty ratio in a second switching period. This asymmetric control strategy enables flexible voltage regulation while the diagonal arrangement ensures loss balancing over complete cycles.
Solution Approach 2:
The patent employs periodic switching control where the first and second controllable switches are alternately controlled in different switching periods. The duty ratios are modulated periodically to achieve voltage boosting, and the alternating operation pattern ensures that losses are distributed evenly across switches over time, improving reliability.
3Device complexity
If frequency modulation only is used in resonant converter, then simplicity is maintained, but voltage range capability is limited
Solution Approach 1:
The patent introduces dynamic duty ratio modulation for the secondary-side controllable switches while maintaining resonant operation. The duty ratios of the first and second controllable switches are dynamically adjusted based on voltage requirements, adding a degree of freedom to the control system. This enables wide voltage range capability (200V-1000V) while building upon the existing resonant converter structure, achieving enhanced functionality without complete redesign.
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
This approach reduces switching losses, equalizes switch operation, and enhances reliability by allowing wide-range voltage boosting with balanced losses and improved efficiency.
Implementation Method 1
a transformer having a primary winding and a secondary winding, a primary circuit electrically connected to the primary winding and receiving an input voltage, and a secondary circuit electrically connected to the secondary winding and outputting an output voltage
Implementation Method 2
An isolated resonant converter may be applied to a solid state transformer (SST)
Data Source
AI summary
The present disclosure discloses a resonant converter, and a controlling method thereof. The resonant converter includes a transformer including a primary winding and a secondary winding, a primary circuit electrically connected to the primary winding and receiving an input voltage, and a secondary circuit electrically connected to the secondary winding and outputting an output voltage. The secondary circuit includes a first secondary half-bridge including a first controllable switch and a second secondary half-bridge including a second controllable switch connected in parallel. The first and second controllable switches are arranged diagonally. The method includes: controlling a duty ratio of one of the first controllable switch and the second controllable switch in a first switching period to form a first short-circuited loop during a first interval during; and controlling a duty ratio of the other one in a second switching period to form a second short-circuited loop during a second interval.