Resonant DC/DC Converter Phase Shift Current Balancing
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Solution Overview
Problem
Resonant DC/DC power converters face challenges in achieving current balance by adjusting signal frequencies, leading to inefficiencies and increased component volumes due to higher current stress on output capacitors, particularly in low voltage high current applications.
Innovation Solution
A method and circuit design that controls resonant DC/DC power converters by outputting driving control signals with preset phase shifts to balance currents between parallel converters, allowing them to operate at the same frequency and reduce output currents when imbalances occur, thereby achieving current balance without frequency adjustments.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stress or pressure
If resonant converters are connected in parallel to reduce current stress on output capacitors, then the current stress on individual capacitors is reduced, but the device complexity increases due to multiple converters and control circuits
Solution Approach 1:
The system divides the single converter into N parallel resonant converters, with each converter having its own output capacitor. This segmentation reduces the current stress on each individual capacitor while maintaining the overall system functionality through parallel operation of multiple converter units
Solution Approach 2:
Multiple resonant converters are combined in parallel configuration to share the total output current. The converters operate simultaneously with phase shifts, merging their outputs to achieve the desired current distribution and reduce stress on individual capacitors
2Object-affected harmful factors
If N resonant converters are connected in parallel to reduce electromagnetic interference, then the overall current ripples and voltage ripples are reduced, but the device complexity increases due to multiple inductors and capacitors
Solution Approach 1:
The system segments the power conversion function across N independent resonant converter modules, each with its own passive components. This segmentation reduces the ripple current and voltage across each module, thereby reducing electromagnetic interference while distributing the passive component requirements across multiple smaller units
Solution Approach 2:
The resonant converters operate at resonant frequencies with controlled phase shifts between them. This creates a vibration-based cancellation effect where the ripple currents and voltages from different converters interfere destructively, reducing overall electromagnetic interference and ripple in the combined output
3Stability of the object's composition
If resonant converters operate at different switching frequencies to achieve current balance, then the current balance between parallel converters is improved, but the control complexity increases due to frequency adjustment requirements
Solution Approach 1:
The system changes the phase angle parameter of the driving signals instead of adjusting switching frequencies. By varying the phase difference between driving signals of parallel converters, the output currents are balanced while maintaining a fixed switching frequency, simplifying the control system
Solution Approach 2:
The control system monitors the output currents of parallel converters and adjusts the phase angles of driving signals accordingly. This feedback mechanism automatically balances the current distribution among converters by detecting current imbalances and correcting them through phase angle adjustments
4Ease of operation
If resonant converters use fixed switching frequency like PWM converters, then the ease of operation is improved through simple duty ratio adjustment, but the ability to achieve current balance is worsened due to lack of frequency adjustment capability
Solution Approach 1:
The system uses phase angle as the control parameter instead of frequency. By changing the phase angle of driving signals while maintaining fixed switching frequency, the system achieves both ease of operation (simple parameter adjustment) and current balance capability (adaptive control through phase variation)
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 effectively balances currents between parallel resonant converters, reducing electromagnetic interference, component volumes, and improving efficiency by adjusting phase angles of driving signals, thus overcoming the limitations of traditional frequency-based balancing methods.
Implementation Method 1
since the resonant converters can achieve zero voltage switching (ZVS) and zero current switching (ZCS), devices are allowed to operate at a low turn-off current and high frequency
Data Source
AI summary
A method for controlling a resonant DC/DC power converting circuit is provided. The resonant DC/DC power converting circuit having a converter output and a converter input comprises at least two converters having similar structures and outputs connected in parallel as said converter output, and a controller. Each converter comprises a full-bridge inverter unit and a resonant unit. The full-bridge inverter unit is configured with at least four switches. The resonant unit is coupled with said full-bridge inverter unit. The controller outputs two groups of driving control signals to drive four switches in said two converters respectively. The method comprises: making said two converters operate at the same frequency and interleave with preset phase shift; and making two of driving control signals in one group interleave with preset angle to reduce output current of said converter corresponding controlled thereby, when output currents of said two converters are not approximately equal.