Three-Phase Boost Rectifier Topology for Low-Distortion PFC
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Solution Overview
Problem
Existing three-phase AC-to-DC converters for applications like electric vehicle charging and MRI systems face challenges in achieving low current distortions, independent control of sinusoidal currents, and efficient power factor correction with a neutral current return, while being cost-effective and simple to design.
Innovation Solution
The electrical converter design incorporates a three-phase bridge rectifier with boost inductors and semiconductor switches controlled via pulse width modulation, allowing for pulsed voltage generation and independent current control, with a distributed boost circuit and reduced energy storage elements to minimize hardware and switching losses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional six-switch boost-type PFC rectifier or VIENNA rectifier is used for three-phase AC to high voltage DC conversion, then power factor correction and low current distortion are achieved, but device complexity and cost increase
Solution Approach 1:
The converter is divided into three independent single-phase half-bridge circuits, each handling one phase. Each half-bridge circuit includes its own switch, diode, and capacitor, allowing independent control of each phase current while simplifying the overall topology compared to conventional six-switch or VIENNA rectifiers
Solution Approach 2:
The three single-phase half-bridge circuits work together to achieve three-phase PFC functionality. The same basic circuit structure is reused for each phase, providing universal design that reduces complexity while maintaining power factor correction and low current distortion capabilities
2Adaptability or versatility
If independent control of phase currents is required for electric vehicle charging, then adaptability improves, but device complexity increases due to need for neutral conductor connection
Solution Approach 1:
Each phase is controlled independently through its own half-bridge circuit, enabling separate amplitude control of each phase current. This segmentation allows the converter to adapt to different charging scenarios, such as unbalanced loading or neutral current injection requirements for EV charging applications
Solution Approach 2:
The converter dynamically adjusts the amplitude and phase of each phase current through independent PWM control of each half-bridge circuit. This dynamic control capability enables adaptation to varying load conditions and neutral current requirements without requiring physical reconfiguration
3Device complexity
If distributed boost circuit with reduced energy storage elements is used, then device complexity and cost decrease, but maintaining low current distortion becomes challenging
Solution Approach 1:
The boost function is distributed across three independent half-bridge circuits, each with its own energy storage capacitor. This distributed architecture eliminates the need for a single large boost inductor and complex six-switch topology, reducing device complexity while maintaining effective PFC through coordinated control of all three circuits
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 achieves low input current distortions, efficient power factor correction, and independent control of currents, enabling cost-effective and efficient three-phase AC-to-DC conversion with reduced hardware complexity and improved efficiency.
Implementation Method 1
The at least one second semiconductor switch is connected across the upper intermediate node and the lower intermediate node. The controller is configured to control the at least one second semiconductor switch via pulse width modulation allowing for obtaining a pulsed intermediate voltage
Implementation Method 2
a boost circuit comprising boost inductors, at least one second semiconductor switch that is actively switchable and at least one third semiconductor switch
Data Source
Figure 1
Figure 2A~2D
Figure 3
AI summary
Electrical converter (10) for converting a three-phase AC input into a DC output, comprising three phase input terminals (a, b, c) and two output terminals (p, n), a three phase bridge rectifier (11) having an input connected to the phase input terminals and an output connected to an upper intermediate node (I) and a lower intermediate node (II), a boost circuit (12) comprising at least one second semiconductor switch (III) and at least one third semiconductor switch (IV) connected in series across the output terminals (p, n), and boost inductors (La, Lb, Lc), an output filter (14) comprising a filter capacitor (Cpm, Cmn, Cpn) connected between the boost circuit and the output terminals, and a controller (40) operably connected to the first semiconductor switches and to the at least one second semiconductor switch. The boost inductors (La, Lb, Lc) are connected between the phase terminals and the three phase bridge rectifier. The at least one second semiconductor switch (III) is connected across the upper intermediate node (I) and the lower intermediate node (II). The controller (40) is configured to control the at least one second semiconductor switch via pulse width modulation allowing for obtaining a pulsed intermediate voltage between the upper intermediate node and the lower intermediate node having a modulated pulse width and to control switching of the first semiconductor switches according to a switching pattern wherein the phase input terminal having an intermediate voltage between a highest voltage and a lowest voltage is alternatingly connected to the upper intermediate output node (I) and the lower intermediate output node (II).