Multi-Phase Converter Duty Cycle Limiting for Current Balance
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Solution Overview
Problem
Multi-phase interleaved bidirectional converters face issues with duty cycle limitations, where duty cycles less than 0.5 in boost mode and greater than 0.5 in buck mode lead to unbalanced inductor currents and deteriorated voltage gain, resulting in insufficient inductor energy.
Innovation Solution
A novel power supply apparatus incorporating a microcontroller and voltage converters that limit duty cycles to 0.5 when necessary, ensuring balanced inductor currents and sufficient energy, thereby maintaining voltage gain without duty cycle constraints.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the duty cycles of the low-side transistor switches are less than 0.5 in boost mode, then the control flexibility is improved, but the inductor energy becomes insufficient causing inductor currents to be unbalanced and voltage gain to deteriorate
Solution Approach 1:
The controller monitors the duty cycle values and automatically adjusts them to maintain the 0.5 threshold when operating in boost mode. This feedback mechanism ensures that the inductor currents remain balanced and voltage gain is maintained, while still allowing flexible control within the valid operating range.
Solution Approach 2:
The system dynamically changes the duty cycle parameter based on operating conditions. When the calculated duty cycle falls below 0.5 in boost mode, the controller modifies it to exactly 0.5, ensuring sufficient inductor energy and current balance while maintaining control adaptability within physical constraints.
2Adaptability or versatility
If the duty cycles of the high-side transistor switches are greater than 0.5 in buck mode, then the control flexibility is improved, but the inductor energy becomes insufficient causing inductor currents to be unbalanced and voltage gain to deteriorate
Solution Approach 1:
The controller continuously monitors duty cycle values in buck mode and applies feedback control to prevent the duty cycle from exceeding 0.5. This ensures that inductor currents remain balanced and voltage gain is maintained, while preserving control flexibility within the valid operating range.
Solution Approach 2:
The system dynamically adjusts the duty cycle parameter based on operating mode and calculated values. In buck mode, when the calculated duty cycle exceeds 0.5, the controller modifies it to exactly 0.5, ensuring sufficient inductor energy and current balance while maintaining adaptability.
3Reliability
If the duty cycles are constrained to 0.5 threshold, then the inductor energy sufficiency is improved, but the control range is reduced
Solution Approach 1:
The duty cycle constraint is applied dynamically based on operating mode (boost or buck) rather than being a fixed limitation. The controller calculates the optimal duty cycle and applies the 0.5 threshold only when necessary to maintain inductor energy sufficiency, allowing maximum control range within physical constraints.
Solution Approach 2:
The system changes the duty cycle parameter adaptively: using calculated values when they satisfy the 0.5 threshold, and switching to the threshold value when energy sufficiency requires it. This maintains inductor energy sufficiency while preserving control flexibility within valid operating ranges.
Data Source
AI summary
A novel power supply apparatus (10) includes a microcontroller (102) and a plurality of voltage converters (104). If the voltage converters (104) are in a boost mode and a plurality of duty cycles of the voltage converters (104) calculated by the microcontroller (102) are less than 0.5, the microcontroller (102) is configured to limit at least one of the duty cycles of the voltage converters (104) to 0.5. If the voltage converters (104) are in a buck mode and the duty cycles of the voltage converters (104) calculated by the microcontroller (102) are greater than 0.5, the microcontroller (102) is configured to limit at least one of the duty cycles of the voltage converters (104) to 0.5.