Ideal Diode Reverse Voltage Protection Circuit
Solution Overview
Problem
Conventional diodes in power systems experience power dissipation due to voltage drops in the forward direction, leading to heat issues and reduced service life, while 'ideal diode' circuits fail to prevent reverse currents effectively.
Innovation Solution
A reverse current inhibitor is developed, comprising a diode bridged by a variable resistance element and a sensing circuit with a current-voltage converter that switches the resistance from high to low in response to forward current and back to high when a reverse current is detected, using simple and inexpensive analog components for fast reaction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional diode is used to prevent reverse current, then reverse current protection is achieved, but power dissipation increases due to voltage drop in forward direction
Solution Approach 1:
The patent employs a dynamic resistance element (MOSFET) that changes its resistance state based on current direction. During forward current flow, the MOSFET is turned on to provide a low-resistance path, minimizing voltage drop and power dissipation. When reverse current is detected by the sensing circuit, the MOSFET is turned off to block the reverse current. This dynamic switching between resistance states resolves the contradiction by adapting the circuit behavior to the instantaneous current direction.
Solution Approach 2:
The patent introduces an intermediary sensing circuit that monitors current direction and controls the MOSFET switching. The sensing circuit acts as a mediator between the current flow and the resistance element, detecting forward current through a sensing resistor and triggering the MOSFET to switch states. This intermediary mechanism enables the system to achieve both low power dissipation during forward conduction and effective reverse current blocking.
2Loss of energy
If an ideal diode circuit with variable resistance element is used to eliminate voltage drop, then power dissipation is reduced, but reverse current protection is lost
Solution Approach 1:
The patent implements a feedback mechanism where the sensing circuit continuously monitors the current direction through the sensing resistor and provides control signals to the MOSFET gate. When forward current flows through the sensing resistor, the sensing circuit detects this and turns on the MOSFET to minimize power dissipation. When reverse current is detected, the sensing circuit turns off the MOSFET to block the reverse current. This feedback loop enables the circuit to maintain both low power dissipation during normal operation and reverse current protection when needed.
3Reliability
If a sensing circuit with current-voltage converter is added to detect reverse current, then reverse current protection is restored, but device complexity increases
Solution Approach 1:
The patent extracts the reverse current detection function into a separate, dedicated sensing circuit that uses simple analog components. The sensing circuit includes a sensing resistor for current detection and a current-voltage converter that generates control signals for the MOSFET. By separating the detection and control functions into distinct circuit blocks, the patent achieves reverse current protection without significantly increasing overall system complexity, as each component performs a specific, well-defined function.
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 minimizes power dissipation and effectively blocks reverse currents, providing rapid protection against equipment damage by amplifying the voltage drop for forward currents only and switching the resistance accordingly, thus extending the service life of components.
Implementation Method 1
a current-voltage converter that includes a sensing resistor and is configured to amplify a voltage drop over the sensing resistor for one sign of the voltage drop only
Implementation Method 2
a first switching device configured to switch the first variable resistance element from a first higher resistance to a second lower resistance in response to a forward current
Data Source
AI summary
A reverse current inhibitor includes: at least one diode that is bridged by a first variable resistance element; a sensing circuit; a first switching device for switching the first variable resistance element from a first higher resistance to a second lower resistance in response to a forward current that has passed the diode in its forward direction; and a second switching device for switching the first variable resistance element to a higher resistance in response to the sensing circuit detecting a reverse current corresponding to the reverse direction of the diode. The sensing circuit includes a current-voltage converter that includes a sensing resistor and amplifies a voltage drop over the sensing resistor for one sign of the voltage drop only.