Three-Phase Half-Bridge Converter for PFC Without Bulky DC Link
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Solution Overview
Problem
Conventional three-phase PFC rectifiers with galvanic isolation require bulky and heavy inductors and DC link capacitors, taking up to 50% of the overall size, and lack a simplified control scheme.
Innovation Solution
A power converter using a three-phase half-bridge switching circuit with a control circuit that generates an unregulated AC output, and a method to control the power factor by controlling the waveform of the alternating voltage based on input voltage and current signals without feedback, utilizing bidirectional blocking switches and a simplified control scheme.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional three-phase PFC rectifier with galvanic isolation is used, then galvanic isolation between input and output is achieved, but the device becomes bulky and heavy due to inductors and DC link capacitors taking up to 50% of the overall size
Solution Approach 1:
The patent extracts and eliminates the bulky inductors and DC link capacitors from the conventional two-stage PFC rectifier architecture. By using a single-stage circuit with direct AC-to-DC conversion, the design removes the intermediate DC link stage that requires these large energy storage components, thereby achieving galvanic isolation without the weight penalty of traditional inductors and capacitors.
Solution Approach 2:
The switching circuit in the patent performs multiple functions simultaneously: it provides galvanic isolation, achieves power factor correction, and generates the output voltage without requiring separate dedicated components for each function. This multi-functionality is achieved through the integrated single-stage architecture where the switching network handles both isolation and PFC operations that traditionally required separate stages and components.
2Reliability
If a conventional two-stage PFC rectifier with inductors and DC link capacitor is used, then galvanic isolation is provided, but the device complexity increases and components take up to 50% of the overall size
Solution Approach 1:
The patent merges the galvanic isolation function and power factor correction function into a single integrated stage rather than using separate two-stage architecture. The switching circuit combines the roles of the traditional rectifier stage and PFC stage, eliminating the need for separate control circuits and reducing overall device complexity while maintaining galvanic isolation through the transformer coupling.
3Ease of operation
If traditional PFC control methods are used, then power factor control is achieved, but the control scheme becomes complex requiring feedback mechanisms
Solution Approach 1:
The control circuit in the patent employs a self-service mechanism where it automatically adjusts the switching signals based on the inherent relationship between input voltage and current waveforms. The controller monitors the input voltage waveform and generates corresponding switching patterns that naturally achieve unity power factor without requiring complex feedback loops or additional sensing components, thereby simplifying the control scheme while maintaining effective power factor control.
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
Achieves high power factor control with reduced components, enabling efficient and compact design, and allows for galvanic isolation, reducing the complexity and cost of the system.
Implementation Method 1
generating the alternating voltage in an unregulated fashion by a switching circuit including a three-phase half-bridge
Implementation Method 2
controlling a waveform of the alternating voltage dependent on signal levels of the input voltages
Data Source
AI summary
A method for operating a power converter and a power converter are disclosed. The method includes generating an alternating voltage (Vmn) based on three alternating input voltages (Va, Vb, Vc) received at an input (a, b, c) of a power converter. Generating the alternating voltage (Vmn) includes: generating the alternating voltage (Vmn) in an unregulated fashion by a switching circuit (1) comprising a three-phase half-bridge, controlling a waveform of the alternating voltage (Vmn) dependent on signal levels of the input voltages (Va, Vb, Vc), and controlling a power factor of power received at the input (a, b, c).