Multilevel PFC Resonant Converter Layout for Lower EMI
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Solution Overview
Problem
The existing two-stage circuit architecture for high-power applications in switching power supplies, comprising a power factor correction circuit and an isolated DC-DC circuit with resonant conversion topology, faces inefficiencies and power density limitations due to the use of high-voltage devices, which hinders further increases in switching frequency and worsens heat and EMI characteristics.
Innovation Solution
A power conversion device incorporating a multi-level power factor correction circuit, multiple input and output capacitors, and resonant conversion circuits connected in specific parallel and series configurations to reduce switching losses, common mode noise, and electromagnetic interference, while improving EMI characteristics and power density.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If high-voltage devices are used in the two-stage circuit architecture, then the power conversion device can handle high-power applications, but the switching frequency cannot be further increased and EMI characteristics deteriorate
Solution Approach 1:
The patent divides the single high-voltage power conversion stage into two separate low-voltage stages: a first resonant conversion circuit handling input voltage and a second resonant conversion circuit handling output voltage. Each stage operates at low voltage independently, avoiding the EMI issues associated with high-voltage switching while maintaining high-power capability through the series connection of input capacitors and parallel connection of output capacitors.
2Power
If high-voltage devices are used in the two-stage circuit architecture, then the power conversion device can handle high-power applications, but the switching frequency cannot be further increased
Solution Approach 1:
The patent segments the power conversion process into two independent low-voltage stages, each capable of operating at high switching frequencies. By avoiding high-voltage devices, each stage can use faster switching components, thereby increasing the overall switching frequency and improving power density while maintaining high-power handling capability.
3Ease of operation
If a conventional two-stage circuit architecture is used, then input current shaping and output voltage adjustment can be achieved, but efficiency and power density are unsatisfactory
Solution Approach 1:
The patent changes the voltage parameters of the circuit stages from high-voltage to low-voltage operation. By operating both resonant conversion circuits at low voltage, switching losses are reduced, thereby improving efficiency while maintaining the ability to shape input current and adjust output voltage through resonant control.
Solution Approach 2:
The patent segments the power conversion into two independent low-voltage resonant stages, each optimized for high efficiency. The first stage converts input voltage to an intermediate voltage, and the second stage converts it to the final output voltage. This segmentation allows each stage to operate efficiently at low voltage, improving overall system efficiency while maintaining power density.
Data Source
AI summary
The present disclosure provides a power conversion device. The power conversion device includes the multi-level power factor correction circuit, the at least one output capacitor, the at least one input capacitor group, the first resonant conversion circuit and the second resonant conversion circuit. The at least one input capacitor group includes the first input capacitor and the second input capacitor. The at least one output capacitor is connected to an output part of the multi-level power factor correction circuit. The at least one input capacitor group is connected to the at least one output capacitor in parallel. The second input capacitor is connected to the first input capacitor in series. The input part of the first resonant conversion circuit is connected to first input capacitor in parallel. The input part of the second resonant conversion circuit is connected to the second input capacitor in parallel.