Half-Bridge PFC Circuit for Step-Up and Step-Down DC Conversion
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Solution Overview
Problem
Existing network circuits require multiple components and complex control systems to both step-up and step-down AC power supply voltages, leading to inefficiencies and increased costs, as they typically necessitate separate downstream converter circuits for power factor correction (PFC) standards.
Innovation Solution
A PFC network circuit with a half-bridge configuration that uses three phases, transistors, star capacitors, storage chokes, and a control unit to directly convert AC power supply voltage into both higher and lower DC output voltages, eliminating the need for downstream converters and simplifying control to meet PFC standards.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If separate downstream converter circuits are used to step-up and step-down AC power supply voltage, then voltage conversion capability is improved, but device complexity and component count increase
Solution Approach 1:
The patent combines the step-up and step-down converter functions into a single integrated network circuit. The circuit uses a single set of power electronic switches (IGBTs and diodes) and energy storage elements (inductors and capacitors) to perform both voltage elevation and reduction operations, eliminating the need for separate downstream converter circuits and reducing overall system complexity.
Solution Approach 2:
The network circuit is designed with multi-functionality to handle both step-up and step-down voltage conversion using the same hardware components. By controlling the switching sequence and timing of the power electronic devices, the circuit can operate in different modes (step-up, step-down, or unity power factor correction) without requiring dedicated circuits for each function.
2Reliability
If multiple converter circuits are used for PFC compliance, then power factor correction performance is improved, but energy efficiency deteriorates due to multiple conversion stages
Solution Approach 1:
The patent merges the PFC function with the voltage conversion function in a single stage. The network circuit directly processes the AC input voltage to produce the desired DC output voltage while maintaining sinusoidal input currents and achieving unity power factor, eliminating the energy losses associated with multiple sequential conversion stages.
3Quantity of substance
If simple bridge rectifiers are used, then component count is reduced, but harmonic currents and reactive power consumption increase
Solution Approach 1:
The patent replaces the passive simple bridge rectifier with an active network circuit using controllable power electronic switches. This active circuitry enables precise control of the input current waveform to maintain sinusoidal shape and unity power factor, eliminating harmonic currents and reactive power consumption while using only one rectifier bridge instead of multiple converters.
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 solution enhances energy efficiency, reduces component count and costs, and improves electromagnetic compatibility by allowing sinusoidal current extraction while maintaining PFC compliance without additional converter topologies.
Implementation Method 1
The capacitor (CS) is configured to serve as an adjustable voltage source by selectively charging and discharging by controlling the first and second transistors and to adjust a voltage difference across the three storage chokes
Implementation Method 2
an output capacitor, an output coil, a diode and a string capacitor, wherein the output capacitor, the output coil, the diode and the string capacitor are provided at an output region of the network circuit
Data Source
AI summary
A PFC network circuit with a half-bridge and a method for converting an AC power supply voltage to both a lower and a higher DC output voltage in compliance with PFC standards, the PFC network circuit comprising three phases, a rectifier comprising three inputs, a first and a second transistor controlled by a control unit, a midpoint arranged between the first and second transistors, a star point comprising three star capacitors and a capacitor connected to the midpoint and a reference potential, which can be either the zero potential of the network circuit or the star point of the star capacitors. The network circuit further comprises an output capacitor, an output coil, a diode and a string capacitor, wherein the output capacitor, the output coil, the diode and the string capacitor are provided at an output region of the network circuit.