T-Type Buck-Boost PFC Rectifier for Wide Output Voltage Range
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Solution Overview
Problem
Existing rectifiers for lower voltage loads often require additional conversion stages, leading to increased cost, volume, weight, and reduced efficiency, as they struggle to maintain power factor correction and harmonic elimination across varying grid voltages.
Innovation Solution
A T-type buck-boost power factor correction (PFC) rectifier is developed, utilizing a power inductor, storage capacitors, and bi-directional switches to achieve a tri-level output voltage, operating in both continuous and discontinuous conduction modes, thus eliminating the need for additional conversion stages.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If a Boost-type converter topology is used for rectification, then power factor correction is achieved, but additional voltage conversion stages are required for lower voltage loads
Solution Approach 1:
The T-type buck-boost rectifier is designed to perform multiple functions: it acts as both a PFC rectifier and a voltage converter in a single stage. The circuit can operate in boost mode to step up voltage when grid voltage is low, and in buck mode to step down voltage when grid voltage is high, eliminating the need for separate conversion stages while maintaining power factor correction
2Loss of energy
If a Buck converter topology is used for rectification, then voltage step-down is achieved, but input current cannot be sustained throughout the entire line cycle
Solution Approach 1:
The T-type buck-boost rectifier combines both buck and boost functionalities in a single unified circuit topology. The circuit can seamlessly switch between buck operation (when Vin > Vout) and boost operation (when Vin < Vout), ensuring continuous input current throughout the entire line cycle while providing both step-up and step-down voltage conversion capabilities
3Loss of energy
If a Vienna rectifier is used, then three-phase rectification with reduced voltage drop is achieved, but output voltage is double the standard boost PFC rectifier
Solution Approach 1:
The T-type buck-boost rectifier employs dynamic operation where the circuit topology and switching patterns adapt in real-time based on the relationship between input grid voltage and output voltage requirements. The controller dynamically adjusts the duty cycles of the switches to achieve the desired output voltage, allowing the rectifier to operate efficiently across a wide voltage range (50V-800V) rather than being fixed at a specific voltage level
4Adaptability or versatility
If additional conversion stages are added to existing rectifiers, then voltage matching for lower voltage loads is achieved, but cost, volume, and weight increase
Solution Approach 1:
The invention merges the PFC rectification function and the voltage conversion function into a single integrated T-type buck-boost rectifier circuit. By combining these functions that were previously performed by separate stages, the design achieves voltage matching for various loads while reducing the overall weight, volume, and cost compared to multi-stage converter systems
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 proposed rectifier effectively maintains a power factor close to unity, provides a wide output voltage range of 50-430 VDC without harmonics, and reduces the volume and weight of the rectifier, making it suitable for a variety of low-power applications.
Implementation Method 1
a power inductor; first, second and third bi-directional switches, the first bidirectional switch connecting a power supply input to a first end of said power inductor
Implementation Method 2
first and second storage capacitors; said second end of said first capacitor, said second end of said second capacitor and said second end of said power inductor being connected to a common node
Data Source
AI summary
A T-type buck-boost power factor correction (PFC) rectifier (TBPR) comprises a power inductor, first and second storage capacitors, and first, second and third bi-directional switches. The first bidirectional switch connects a power supply input to a first end of the power inductor, the second bidirectional switch connects the first end of the power inductor to a first end of the first capacitor and the third bidirectional switch connects the first end of the power inductor to a first end of the second capacitor. At the same time, the second end of the first capacitor, the second end of the second capacitor and the second end of the power inductor are connected to a common node.