Rectifier Circuit Using MOS Transistors for Low Forward Voltage
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Solution Overview
Problem
Conventional rectifier bridges using silicon PN diodes experience significant power losses and heat dissipation due to high forward voltages, especially when rectifying low AC voltages, leading to increased fuel consumption and cooling requirements in motor vehicles.
Innovation Solution
The use of rectifier circuits comprising MOS transistors, capacitors, and differential amplifiers in place of silicon PN diodes, which reduce forward voltages to approximately 25 mV, minimizing power losses and cooling needs without requiring separate power supplies or signal inputs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If silicon PN diodes are used in rectifier bridges, then the rectification function is achieved, but high forward voltages cause significant power losses and heat dissipation
Solution Approach 1:
The patent changes the fundamental parameter of forward voltage by replacing silicon PN diodes with MOS transistors. MOS transistors exhibit different electrical characteristics with much lower forward voltage drops (typically < 1V compared to 0.7-2V for silicon diodes), directly addressing the power loss issue while reducing heat generation as a consequence
2Loss of energy
If silicon PN diodes are used in rectifier bridges, then the rectification function is achieved, but complex cooling elements are required to remove power dissipation
Solution Approach 1:
By changing the rectifying element from silicon PN diode to MOS transistor, the forward voltage parameter is fundamentally altered. This parameter change reduces power dissipation to such an extent that complex cooling systems become unnecessary, simplifying the overall device structure
Solution Approach 2:
The invention converts the typically harmful effect of forward voltage drop into a benefit by using MOS transistors whose operating characteristics naturally exhibit lower voltage drops. The structure that would normally cause power loss in diodes becomes advantageous when using field-effect transistors, turning a disadvantage into an advantage
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 significantly reduces power losses and cooling efforts by lowering forward voltages, enhancing efficiency and reducing costs associated with cooling systems in motor vehicle rectification processes.
Implementation Method 1
If the electrical potential at the cathode terminal K1 of the rectifier circuit is more negative than the electrical potential at the anode terminal A1, then the gate-source voltage of the MOS transistor T1 is positive and higher than its threshold voltage. Under these conditions, the MOS transistor T1 conducts
Implementation Method 2
the MOS transistor T1 and the inverse diode D6 are connected in parallel and, due to technological constraints, together form a single microelectronic component
Implementation Method 3
The Zener diode D5 acts as a protection element for transistor T1 and protects its gate from overvoltages
Implementation Method 4
A first input of this differential amplifier is connected via diode D1 to the cathode terminal K1 and the drain terminal of MOS transistor T1. A second input of this differential amplifier is connected via diode D2 to the anode terminal A1. This differential amplifier amplifies the potential difference between the cathode terminal K1 and the anode terminal A1
Data Source
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AI summary
The invention relates to rectifier circuits, which can be utilized instead of diodes for the rectification of alternating currents, and which, like diodes, form two-terminal networks having a cathode connection and an anode connection. The power loss of said rectifier circuits is significantly less than the power loss of silicon PN diodes. Said rectifier circuits further comprise voltage terminal functions.