Self-Powered FET Controller for Reverse Current Protection
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Solution Overview
Problem
In high-power systems, series diodes cause excessive power dissipation due to voltage drop, while FETs with controllers consume additional power for reverse current protection, necessitating a more efficient solution for regulating voltage drops.
Innovation Solution
A circuit using a transistor with a controller that powers itself from the voltage across its terminals, employing a voltage converter and control circuit to regulate the transistor's voltage, allowing self-sustaining operation and minimal power consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a series diode is used for reverse battery protection, then reverse current protection is provided, but excessive power dissipation occurs due to voltage drop in high-power systems
Solution Approach 1:
The patent changes the electrical parameters by replacing the diode's fixed voltage drop characteristic with a FET's variable resistance characteristic, allowing the resistance to be dynamically adjusted to minimize power dissipation while maintaining protection functionality
Solution Approach 2:
The system transitions from a static diode protection circuit to a dynamic FET-based system where the controller continuously adjusts the FET's gate voltage to optimize the on-resistance, enabling adaptive power loss minimization under varying load conditions
2Loss of energy
If a FET is used for reverse current protection, then power dissipation is minimized due to low resistance, but additional power is consumed by the controller
Solution Approach 1:
The controller is designed to harvest its operating power from the voltage drop across the FET itself, creating a self-sustaining system where the protection circuit's own operational losses power the control electronics, eliminating the need for external power supply for the controller
Solution Approach 2:
The power management circuit acts as an intermediary that captures the voltage drop across the FET and converts it into usable power for the controller, transforming what would be wasted energy into a useful resource for system operation
3Reliability
If a controller is added to regulate FET voltage, then voltage regulation is achieved, but device complexity increases
Solution Approach 1:
The controller is designed to perform multiple functions simultaneously: regulating FET voltage, harvesting power from the voltage drop, and providing reverse current protection, thereby reducing the need for separate dedicated components for each function
Solution Approach 2:
The patent merges the power management functionality with the voltage regulation control circuitry into a single integrated controller, consolidating what could be separate components into one unified device that reduces overall system complexity
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 effectively regulates voltage across the transistor with minimal power consumption, reducing power dissipation and enabling efficient reverse current protection in high-power systems.
Implementation Method 1
The voltage converter receives a voltage existing across the second and third terminals of the transistor and converts that voltage to a power supply voltage that is a higher voltage than the received voltage
Implementation Method 2
The transistor has first, second and third terminals, wherein a voltage level at said first terminal controls in part a current flow from said second terminal to said third terminal
Data Source
AI summary
Circuits and methods for controlling a transistor that has first, second and third terminals, wherein a voltage level at said first terminal controls in part a current flow from said second terminal to said third terminal. A controller receives an voltage existing across the second and third terminals of the transistor, generates an isolated voltage and uses that voltage to power components of the controller. The controller provides a voltage to the first terminal of the transistor, whereby the controller regulates the voltage across the second and third terminals of the transistor by regulating the voltage provided to the first terminal.