Multi-phase Resonant Power Converter Ripple Reduction
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Solution Overview
Problem
Existing multi-phase resonant power conversion circuits face challenges in reducing output voltage ripple and input/output current ripple without increasing component count or volume, especially at high power levels, due to component tolerances leading to inefficiencies and potential component failure.
Innovation Solution
A multi-phase switching power conversion circuit with a resonant network arranged in a symmetrical configuration, including multiple transformers and output rectifier circuits, where the phase branches are connected in a star connection, and a control circuit adjusts switching frequencies to manage output voltage, reducing ripple currents and enhancing current-sharing efficacy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the switching frequency is increased to reduce power supply size, then the size is reduced, but the switching loss is increased
Solution Approach 1:
The patent employs resonant mode power conversion which utilizes the resonant frequency of the LC circuit to achieve soft switching conditions. By operating at or near the resonant frequency, the circuit transitions into a state where voltage or current naturally reaches zero during switching transitions, enabling zero-voltage switching (ZVS) or zero-current switching (ZCS). This phase transition in operating mode allows high-frequency operation without the typical switching loss penalty, thus reducing power supply size while maintaining efficiency.
Solution Approach 2:
The patent utilizes resonant oscillation in the power conversion circuit by incorporating resonant inductors and capacitors that create a natural resonant frequency. The circuit is designed to operate at this resonant frequency, creating a vibratory energy transfer mechanism between the input and output. This resonant vibration allows energy to be transferred efficiently at high frequencies without requiring hard switching, thereby reducing the power supply size while avoiding increased switching losses.
2Power
If the output current is increased to meet higher power demands, then the power level is increased, but the ripple current of output filter increases significantly
Solution Approach 1:
The patent employs multi-phase parallel resonant power conversion circuits instead of a single-phase circuit. By segmenting the power conversion into multiple phases (e.g., three-phase configuration), each phase handles a portion of the total power. The ripple currents from different phases are phase-shifted relative to each other, and when combined at the output, they cancel out portions of each other's ripple. This segmentation approach allows higher total power output while maintaining lower overall ripple current compared to a single-phase design.
3Ease of manufacture
If component tolerances are large to reduce manufacturing cost, then the manufacturing cost is reduced, but the current-sharing efficacy deteriorates
Solution Approach 1:
The patent incorporates control circuits that monitor the operating conditions of each parallel phase and provide feedback signals. Based on this feedback, the control circuit adjusts the switching parameters (such as duty cycle or switching frequency) of individual phases to maintain balanced current sharing. This closed-loop feedback mechanism compensates for component tolerance variations, ensuring reliable current sharing even when components have large manufacturing tolerances, thus maintaining both low cost and high reliability.
Solution Approach 2:
The patent intentionally introduces asymmetric control parameters for different parallel phases to compensate for symmetric component tolerances. By applying slightly different switching frequencies, duty cycles, or phase shifts to each phase based on their actual measured characteristics, the system achieves symmetric current sharing at the output. This controlled asymmetry in control parameters counteracts the random asymmetry introduced by component tolerances, maintaining current-sharing efficacy without requiring tight manufacturing tolerances.
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 effectively reduces output voltage and input/output current ripples, improves current-sharing, and increases operating efficiency by maintaining symmetrical current values across phases, even with large component parameter tolerances, thus reducing power loss and component stress.
Implementation Method 1
the resonant power conversion circuit may have higher conduction losses of switch when compared with the power conversion circuit in the PWM mode... the resonant mode power conversion circuit is an important solution to achieve high frequency, high power density and high efficiency
Implementation Method 2
The high-frequency pulse voltage is applied on the resonant network A2 which comprises a resonant inductor Lr and a resonant capacitor Cr. As such, the AC voltage across the primary winding of the transformer Tr transfer the electrical energy to the filtering and rectifying output circuit A3 through the secondary winding of the transformer Tr
Data Source
AI summary
A multi-phase switching power conversion circuit has at least three phases and includes a plurality of switching circuits, a plurality of transformers, a plurality of output rectifier circuits, a resonant network and a control circuit. The resonant network includes a plurality of symmetrical terminals and a plurality of phase branches, which are connected in a multi-phase symmetrical relationship. Each of the symmetrical terminals is connected to the output side of respective switching circuits. The phase branches are connected to a resonant common terminal such that the phase branches are in a star connection. The resonant common terminal is different from the positive terminal and the first reference terminal of the input voltage source. The control circuit is connected to an output terminal of the multi-phase switching power conversion circuit and a plurality of the control terminals of the plurality of switching circuits. The switching circuits are conducted or shut off according to the output voltage under control of the control circuit, so that the electrical energy of the input voltage source is selectively transmitted to the resonant network.