Three-Phase Rectifier Topology for Lower Pulsating Current
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Solution Overview
Problem
Conventional rectifiers for high-frequency semiconductor components in power electronics have high costs due to stringent requirements for voltage withstand and maximum pulsating current, limiting efficiency and increasing costs in applications like uninterruptible power supplies, wind power generation, and electric vehicles.
Innovation Solution
A rectifier design incorporating a three-phase AC/DC conversion circuit and a power factor correction (PFC) circuit, where the AC/DC conversion circuit converts two phases of alternating current voltages into a single direct current voltage, and the PFC circuit converts the third phase, reducing the amplitude of pulsating current through switching transistors and allowing the use of lower-cost transistors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a high-frequency semiconductor component is used as a switching component in a rectifier to improve power density, then conversion efficiency is improved, but costs increase due to stringent requirements for voltage withstand and maximum pulsating current
Solution Approach 1:
The rectifier is divided into multiple parallel circuits (first rectifier circuit, second rectifier circuit, third rectifier circuit), each handling a portion of the total current. This segmentation allows each switching transistor to operate at lower current levels, reducing the maximum pulsating current requirement and enabling use of lower-cost components while maintaining overall high conversion efficiency.
2Reliability
If switching transistors with high voltage withstand level and high maximum pulsating current capability are used, then reliability is improved, but costs increase
Solution Approach 1:
By dividing the total current into multiple parallel paths with separate switching transistors, each transistor experiences reduced current stress. This allows selection of transistors with adequate but not excessive current ratings, optimizing the balance between reliability and cost.
Solution Approach 2:
The invention changes the operating parameters of the switching transistors by distributing the current load across multiple devices. This parameter change (from high single-transistor current to lower multi-transistor current) enables cost optimization while maintaining system reliability.
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 design reduces the cost of switching transistors while maintaining high-efficiency conversion, achieving cost-effective and efficient power conversion in rectifiers.
Implementation Method 1
The AC/DC conversion circuit includes diodes, a three-phase alternating current side that is of the AC/DC conversion circuit and that is used to receive a three-phase alternating current voltage is connected to an alternating current side of the PFC circuit
Data Source
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AI summary
Embodiments of this application disclose a rectifier, a charging system, and an electric vehicle, to reduce costs of the rectifier while implementing high-efficiency conversion. The rectifier includes an alternating current (AC)-direct current (DC) conversion circuit and a power factor correction (PFC) circuit. The AC-DC conversion circuit includes diodes, a three-phase alternating current side that is of the AC-DC conversion circuit and that is used to receive a three-phase alternating current voltage is connected to an alternating current side of the PFC circuit, and a direct current side of the AC-DC conversion circuit is connected to a direct current side of the PFC circuit. The AC-DC conversion circuit is configured to: when an absolute value of a difference between a voltage value of a first-phase alternating current voltage in the three-phase alternating current voltage and a voltage value of a second-phase alternating current voltage in the three-phase alternating current voltage is greater than a voltage value of a third-phase alternating current voltage, convert the first-phase alternating current voltage and the second-phase alternating current voltage into a first direct current voltage. The PFC circuit is configured to convert the third-phase alternating current voltage into a second direct current voltage.