MOSFET Rectifier Bridge with Comparator Control
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Solution Overview
Problem
Existing AC to DC conversion technologies, such as rectifier bridges using ordinary diodes, suffer from inefficiencies due to high voltage drops and power dissipation, resulting in lower conversion efficiency compared to the proposed solution.
Innovation Solution
The use of MOSFET transistors with internal body diodes and comparators to selectively turn on the MOSFETs, reducing power dissipation and increasing efficiency by allowing current flow through the MOSFETs instead of the diodes, thereby forming a high-efficiency rectifier bridge.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If ordinary diodes are used in a rectifier bridge, then the device complexity is low, but the power dissipation is high and efficiency is low
Solution Approach 1:
The patent changes the fundamental parameter of the rectifying element from diode to MOSFET transistor. This parameter change enables the rectifier to operate with much lower voltage drop (RDS(on) of MOSFET vs. forward voltage of diode), thereby reducing power dissipation from 2% to 0.4% efficiency loss while accepting increased device complexity through the addition of gate control circuitry.
2Productivity
If MOSFET transistors with comparators are used in the rectifier bridge, then the efficiency increases significantly, but the device complexity increases
Solution Approach 1:
The patent implements feedback control by coupling comparators to each MOSFET in the rectifier bridge. The comparators continuously monitor the voltage across each MOSFET and provide feedback to the gate control circuitry, enabling the system to dynamically determine when to turn on MOSFETs during AC cycles. This feedback mechanism optimizes the switching timing to minimize power dissipation while managing the increased device complexity through intelligent control.
3Loss of energy
If MOSFETs are turned on during conduction, then the voltage drop decreases and efficiency increases, but the control complexity increases
Solution Approach 1:
The patent applies preliminary action by proactively turning on MOSFETs before they would naturally conduct during AC cycles. The gate control circuitry, informed by comparator feedback, anticipates the conduction phase and activates MOSFETs in advance, ensuring they are fully on when current begins to flow. This preliminary action minimizes the transition period where voltage drop occurs, reducing energy loss while managing control complexity through predictive switching.
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 configuration significantly reduces power dissipation and increases efficiency, achieving a five-fold improvement in efficiency loss from 2% to 0.4%, making the conversion process more efficient than traditional rectifier bridges.
Implementation Method 1
When the transistor is turned on and conducting the electrical current in the first direction, it may have a second efficiency. The second efficiency of the transistor may be greater than the first efficiency.
Implementation Method 2
If the FET gate is not energized or connected to its source, the path may allow electrical current to flow in only a first direction through the body diode of the FET when the transistor is in a first direction, and block the current path in a second direction.
Implementation Method 3
A comparator may be coupled across the gate-source of each FET transistor, turning on the transistors when the current flows through its body diode when the input supply is operating
Data Source
AI summary
A system for converting alternating electrical current to direct electrical current may include an input supply for supplying alternating electrical current. The input supply may be connected to a rectifier. The rectifier may be configured as a body diode. A comparator may be coupled to the rectifier. The comparator may apply a voltage to the rectifier when the input supply is operating.