Self-Driven Active Rectification Using Low-Side Feedback Control
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Solution Overview
Problem
Existing AC rectification methods, such as diode bridge rectifiers, suffer from significant conduction losses due to high forward voltage drops, while active rectifiers with MOSFETs require complex control systems, increasing costs and complexity.
Innovation Solution
A self-driven active rectification system using MOSFETs with a low-side feedback control loop and shunt resistor, which measures voltage across the shunt resistor to generate control signals for the MOSFETs, reducing conduction losses without the need for a high-side gate driver.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If diode bridge rectification is used, then circuit topology is simple, but conduction losses are high
Solution Approach 1:
The patent implements self-driven active rectification where the rectifier circuit controls its own switching elements without requiring external microcontrollers or complex control systems. The circuit uses inherent voltage feedback and simple control logic to automatically regulate MOSFET switching, achieving self-service operation that reduces conduction losses while maintaining cost-effectiveness
Solution Approach 2:
The patent changes the operating parameters of the rectifier by replacing diodes with MOSFETs and operating them in active switching mode rather than passive conduction mode. This parameter change enables controlled on-resistance and reduced voltage drop, thereby reducing conduction losses while using streamlined control methods
2Loss of energy
If active rectification with MOSFETs is used, then conduction losses are reduced, but control system complexity increases
Solution Approach 1:
The rectifier circuit controls its own MOSFET switching elements through inherent voltage feedback and simple control logic, eliminating the need for external microcontrollers or complex control systems. This self-service approach reduces control system complexity while maintaining the low conduction losses of active rectification
Solution Approach 2:
The patent extracts and removes the complex control elements (microcontrollers, complex control loops) from the active rectifier system, retaining only the essential MOSFET switching control functionality. This extraction simplifies the control system while preserving the low conduction loss benefits
3Loss of energy
If active rectification with microcontrollers is used, then conduction losses are reduced, but cost increases
Solution Approach 1:
The circuit achieves self-driven operation with streamlined control logic that eliminates expensive microcontrollers, reducing manufacturing cost while maintaining low conduction losses through efficient MOSFET control
Solution Approach 2:
The patent replaces expensive microcontrollers with simpler, more cost-effective control circuitry that uses basic voltage feedback and control logic to drive MOSFETs, achieving cost-effective active rectification
Data Source
AI summary
Systems and methods for providing self-driven active AC rectification are provided. In particular, a power conversion system for providing self-driven active AC rectification can be provided. The system can include an input for receiving AC power, a first capacitor and a second capacitor electrically connected in series. The first and second capacitors can also be electrically connected in parallel with a rectifier's load. The system can include a low-side switching element and a shunt resistor electrically connected between the rectifier's load and a system ground. The power conversion system can also include a low-side feedback control loop configured to obtain a low-side feedback signal based on a voltage across the shunt resistor and the low-side feedback control loop can be further configured to control the low-side switching element based, at least in part, on the low-side feedback signal.