Active Rectifier MOSFET Current Control Hall-Effect Switch
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Solution Overview
Problem
Conventional AC to DC rectifying circuits using diodes suffer from significant power loss and reduced reliability due to heat generated at high currents, especially in applications like automobile alternators, where diode voltage drop and heat dissipation impair efficiency and reliability.
Innovation Solution
An active switching rectifier circuit employing MOSFETs with current-based control, utilizing a ferromagnetic core and Hall-effect switch to detect current and generate switching control signals for MOSFETs, allowing efficient on/off control and minimizing power loss by using MOSFETs' low on-resistance during high current periods.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If diodes are used in high current rectifier applications, then the rectification function is achieved, but significant power loss and heat generation occur
Solution Approach 1:
The patent changes the key parameter from diode voltage drop (0.7V-1.0V+) to MOSFET on-resistance (milliohms range). By using MOSFETs instead of diodes and controlling their resistance parameter through gate voltage, the power loss is dramatically reduced while maintaining rectification functionality.
Solution Approach 2:
The patent replaces the passive diode rectification mechanism with an active MOSFET switching mechanism controlled by a microcontroller and sensor feedback system. This substitution enables dynamic control of the rectification process, optimizing performance and reducing losses.
2Loss of energy
If MOSFETs are used with voltage detection control, then rectification efficiency improves, but circuit complexity increases and voltage detection becomes unreliable with dynamic loads
Solution Approach 1:
The patent introduces a current sensor as an intermediary between the MOSFET and microcontroller. This sensor provides accurate current feedback that mediates the control process, enabling reliable detection of load conditions and dynamic adjustment of MOSFET switching without complex voltage detection circuits.
Solution Approach 2:
The patent implements a feedback control system where the microcontroller continuously monitors current through the sensor and adjusts MOSFET gate voltage accordingly. This closed-loop feedback enables adaptive control that maintains optimal efficiency under varying load conditions while simplifying the overall control architecture.
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 solution significantly reduces power loss and enhances reliability by efficiently managing high currents through MOSFETs, maintaining high efficiency and reducing heat generation, thus improving the rectification process in high-current applications.
Implementation Method 1
a Hall-effect switch disposed inside the gap, wherein the Hall-effect switch generates an ON and OFF signal during a half cycle of an AC or half wave current passing through the conductor
Implementation Method 2
the core generates a magnetic field within the gap when a current flows through the conductor
Data Source
AI summary
An active switching rectifier circuit uses a MOSFET and applies a current based control to turn the MOSFET on and off. The MOSFET has its source and drain connected between an AC phase or neutral line and the DC output. A current detection and control circuit has an input current conductor coupled in series with the source-drain current of the MOSFET; it outputs a switching control signal based on the current in its input conductor and applies the signal to the gate of the MOSFET for on/off control. A Hall-effect switch may be used in the current detection and control circuit. The rectifier may also include a voltage supply circuit for supplying a DC voltage to the current detection and control circuit. The rectifier circuit can be adapted for various configurations including single-phase half-wave, center-tap dual-phase full-wave, single-phase full-wave, and three-phase full-wave.