Stacked DC-DC Resonant Converter for Capacitor Voltage Balancing
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Solution Overview
Problem
Conventional resonant converters face challenges in high-power, high-voltage applications due to voltage imbalance and bidirectional operation issues, particularly in multi-phase multi-level LLC resonant converters, where voltage bias and voltage imbalance in stacked capacitors are not adequately addressed.
Innovation Solution
A DC-DC resonant converter design featuring a stacked structure of half-bridge inverter cells with active switches and input capacitors, connected in a serial stack configuration, along with control circuitry that adjusts duty cycles and phase shift angles to balance capacitor voltages and regulate switching frequency, enabling efficient operation across a wide voltage range.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If conventional resonant converters are used in high-power, high-voltage applications, then voltage bias and voltage imbalance occur in stacked capacitors, but the converter can still operate
Solution Approach 1:
The converter is divided into multiple half-bridge inverter cells stacked in series, with each cell containing its own capacitors. This segmentation allows independent control and voltage balancing of each cell, resolving the voltage imbalance issue while maintaining high-power capability through the stacked configuration.
Solution Approach 2:
The patent implements dynamic voltage balancing control that continuously monitors and adjusts the voltage across stacked capacitors. By making the system dynamic and adaptive rather than static, the converter maintains voltage balance across all capacitor stacks during operation, preventing voltage bias accumulation.
2Adaptability or versatility
If variable switching frequency control is used to regulate output voltage, then operating range is extended, but efficiency diminishes when switching frequency moves away from resonant frequency
Solution Approach 1:
The control system dynamically adjusts switching frequency based on the desired output voltage and load conditions. By implementing intelligent frequency control that considers the resonant characteristics of the tank circuit, the system maintains high efficiency while achieving wide operating voltage range through coordinated frequency and duty cycle adjustments.
Solution Approach 2:
The patent employs parameter optimization where switching frequency, duty cycle, and phase shift angles are adjusted as a coordinated set of parameters. By changing these parameters together rather than independently, the converter achieves wide voltage regulation range while minimizing deviation from resonant frequency operation, thus reducing switching losses.
3Stress or pressure
If stacked structure with multiple half-bridge inverter cells is used, then voltage handling capability is improved, but device complexity increases
Solution Approach 1:
Multiple half-bridge inverter cells are merged in a stacked configuration where they share common circuit elements such as the resonant tank and transformer. This merging approach distributes voltage stress across multiple cells while reducing overall component count and complexity compared to using separate converters for each voltage level.
Solution Approach 2:
The stacked half-bridge cells serve multiple functions: they provide voltage multiplication, enable bidirectional power flow, and facilitate independent voltage balancing control. By making each cell multi-functional, the design achieves high voltage handling capability without proportionally increasing complexity, as the same structural elements perform multiple roles.
4Stability of the object's composition
If duty cycle and phase shift control are implemented for voltage balancing, then capacitor voltage balance is improved, but control complexity increases
Solution Approach 1:
The control system implements feedback mechanisms that monitor capacitor voltages and automatically adjust duty cycles and phase shift angles to maintain balance. This closed-loop feedback control achieves voltage balancing without requiring complex open-loop control algorithms, as the system self-corrects based on real-time voltage measurements.
Solution Approach 2:
The control parameters (duty cycle and phase shift angle) are made dynamic rather than fixed, allowing automatic adaptation to changing operating conditions. This dynamic control approach simplifies the overall control strategy by using continuous adjustment of two parameters rather than complex discrete control logic, achieving voltage balance through natural system response.
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 solution provides improved efficiency and voltage balancing in high-power, high-voltage applications by minimizing voltage bias and ensuring stable operation across a wide input and output voltage range, enhancing the converter's performance and reliability.
Implementation Method 1
The resonant converter, which employ a resonant-tank circuit to shape the switch voltage and/or current waveforms to minimize switching losses and allow high-frequency operation
Implementation Method 2
a transformer TR, and a resonant tank circuit electrically connected between the primary side and the transformer
Implementation Method 3
a secondary side including at least two sets of rectifier circuit elements each coupled to a secondary side winding wound on a transformer core
Data Source
AI summary
The present disclosure provides a series resonant converter and its corresponding control method. In one aspect, the series resonant converter includes m (m=1,2,3, . . . ) sets of primary side stages in parallel, wherein each primary side stage is identical and includes n (n=2,3, . . . ) stacked element circuits, where the primary side stages receive an input voltage; n×m resonant networks coupled to the primary side stages; n×m transformers having n×m primary side windings and n×m secondary side windings, where the primary side windings are coupled to the n×m resonant networks; p (p=1,2,3, . . . ) sets of secondary side stages in parallel, wherein each secondary side stage is identical and includes q (q=n×m/p) stacked element circuits, where the secondary side stages are coupled to n×m secondary side windings; and a control block controlling the primary side switches according to the output voltage, input voltage and input capacitor voltages.