Optically Powered Drive Circuit for Semiconductor Switch EMI Reduction
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Solution Overview
Problem
Electrical gate drives for semiconductor switches are prone to performance degradation due to electromagnetic interference (EMI), leading to unintentional turn-on or turn-off and electromagnetic radiation from high-frequency currents in conductors.
Innovation Solution
An optically powered drive circuit using a photovoltaic cell to convert light signals from fiber optic cables into electrical energy, which is stored and used to control semiconductor switches, reducing the reliance on electrical conductors and thus minimizing EMI effects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If electrical conductors are used to power and control the gate drive, then electrical energy can be transmitted to the semiconductor switch, but electromagnetic interference degrades operational performance by inducing undesired voltages and currents
Solution Approach 1:
The patent replaces electrical conductors with optical fibers to transmit control signals and power to the gate drive circuit. Light signals carry both control information and energy through the optical fiber, eliminating the electrical conductors that cause EMI. This substitution of electrical transmission with optical transmission resolves the contradiction by maintaining energy transmission capability while eliminating electromagnetic interference.
Solution Approach 2:
The patent introduces an optical-to-electrical conversion interface as an intermediary between the optical fiber and the gate drive circuit. Photodetectors or photovoltaic cells convert the optical signals back to electrical signals and power at the gate drive, enabling electrical operation while isolating the sensitive circuitry from EMI-prone electrical conductors. This intermediary conversion process allows the system to benefit from both optical transmission (EMI-free) and electrical operation (compatible with semiconductor switches).
2Ease of operation
If electrical conductors are used for gate drive control, then the semiconductor switch can be controlled, but high frequency currents cause electromagnetic radiation
Solution Approach 1:
The patent substitutes electrical signal transmission through conductors with optical signal transmission through fibers for controlling the semiconductor switch. The gate drive circuit converts these optical signals to electrical signals locally, eliminating high-frequency currents in long electrical conductors that generate electromagnetic radiation. This maintains switch control functionality while eliminating the harmful electromagnetic radiation.
3Reliability
If optical fibers are used to power and control the gate drive, then electromagnetic interference is eliminated, but optical-to-electrical conversion components are required
Solution Approach 1:
The patent merges the optical-to-electrical conversion function with the existing gate drive circuitry by integrating photodetectors or photovoltaic cells directly into the gate drive module. This integration consolidates multiple functions (optical reception, power generation, signal conversion, and switch control) into a single compact unit, reducing overall system complexity despite adding conversion capability. The merged design eliminates the need for separate conversion components while maintaining EMI-free operation.
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 optically powered drive circuit effectively controls semiconductor switches while mitigating EMI issues, enhancing operational reliability and reducing electromagnetic radiation.
Implementation Method 1
a photovoltaic cell configured to receive a first light signal from a fiber optic cable and to output a first voltage in response to the first light signal
Data Source
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AI summary
An optically powered drive circuit (40) and a method for controlling a first semiconductor switch (52) are provided. The optically powered drive circuit (40) includes a photovoltaic cell (100) configured to receive a first light signal from a fiber optic cable (14) and to output a first voltage in response to the first light signal. The optically powered drive circuit (40) further includes an energy storage device (102) electrically coupled to the photovoltaic cell (100) configured to store electrical energy received from the first voltage and to output a second voltage. The optically powered drive circuit (40) further includes an electrical circuit electrically coupled to both the photovoltaic cell (100) and the energy storage device (102). The electrical circuit is energized by the second voltage. The electrical circuit is configured to receive the first voltage and to output a third voltage in response to the first voltage for controlling operation of the first semiconductor switch (52).