Solid-State Bidirectional Switch for In-Wall Socket Integration
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Solution Overview
Problem
Conventional switches, including mechanical and electronic ones, face limitations in controlling loads in electrical grids due to noise generation, power losses, size constraints, and vulnerability to over-currents and over-voltages, making them unsuitable for in-wall installations and home appliance control.
Innovation Solution
A solid-state bidirectional switch using two power field-effect transistors connected anti-serially with a common source or drain node, along with a controller and non-linear voltage limiting elements, to efficiently control AC voltages and currents while reducing on-state resistance and thermal losses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If conventional MOS-FETs or FETs using compensation structures are used to achieve low on-state resistance, then the on-state resistance is reduced, but the chip area becomes too large for integrating on mounting rails or into in-wall sockets
Solution Approach 1:
The patent changes the doping concentration parameter in the drift region, using a first doping concentration in the body region and a second, lower doping concentration in the drift region. This parameter optimization allows achieving low on-state resistance (8 mΩ for 16 A rated current) while reducing the required chip area to a size suitable for in-wall socket integration
Solution Approach 2:
The patent applies different doping concentrations to different regions of the FET structure. The body region has a higher doping concentration (1e16 to 1e18 atoms/cm³) while the drift region has a lower doping concentration (1e15 to 1e17 atoms/cm³), creating local quality variations that optimize both resistance and area characteristics
2Ease of operation
If electronic switches using bipolar devices are used to achieve switching functionality, then switching is enabled, but power losses occur due to the pn-junction voltage drop requiring thermal dissipation means
Solution Approach 1:
The patent replaces bipolar devices with field-effect transistors, substituting the pn-junction-based switching mechanism with a field-effect-based mechanism. This eliminates the inherent 0.7 V voltage drop of pn-junctions, reducing power losses and eliminating the need for extensive thermal dissipation means while maintaining switching functionality
3Ease of operation
If mechanical switches are used to achieve switching operation, then switching is enabled, but noise is generated making them unsuitable as in-wall power sockets
Solution Approach 1:
The patent replaces mechanical switches with solid-state field-effect transistors, substituting mechanical moving parts with solid-state semiconductor devices. This eliminates mechanical noise generation while maintaining switching operation capability, making the device suitable for in-wall power socket applications
4Ease of operation
If mechanical switches are used to achieve switching functionality, then switching is enabled, but the total cycle of operation is limited and they are prone to vibrations
Solution Approach 1:
The patent replaces mechanical switches with solid-state field-effect transistors, eliminating mechanical moving parts that have limited lifecycles and are susceptible to vibrations. Solid-state FETs provide unlimited switching cycles and vibration resistance while maintaining switching functionality, significantly improving reliability
5Ease of operation
If semiconductor switches are used to achieve switching capability, then switching is enabled, but they are prone to over-currents and over-voltages from lightning strikes
Solution Approach 1:
The patent incorporates protective structures including snubber circuits and varistors connected in parallel with the FETs to provide beforehand cushioning against over-voltages and over-currents from lightning strikes. These protective elements limit voltage spikes and absorb energy surges, protecting the semiconductor switches from damage
Solution Approach 2:
The patent applies preliminary anti-action by implementing current limiting resistors and protective diodes that preemptively counteract harmful over-currents and over-voltages before they can damage the FETs. The anti-serial connection configuration also provides inherent protection by blocking reverse polarity surges
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 enables reliable switching of AC voltages and currents with reduced thermal losses and smaller device sizes, enhancing safety and flexibility in controlling home appliances and electrical grids by minimizing fire risks and integrating into in-wall sockets.
Implementation Method 1
a drift control region adjacent to the accumulation channel region, wherein the accumulation channel region is controllable through the drift control region
Implementation Method 2
a body region forming a pn-junction with the source region and having an inversion channel region
Implementation Method 3
a first non-linear voltage limiting element connecting the drain terminal of the first power field-effect transistor with the first input terminal of the controller; and a second non-linear voltage limiting element connecting the drain terminal of the second power field-effect transistor with the second input terminal of the controller
Data Source
AI summary
According to an embodiment, a solid-state bidirectional switch includes a first and a second power field-effect transistor electrically connected anti-serial with each other. Each of the first and second power field-effect transistors includes a source region, a drain region, a body region forming a pn-junction with the source region and having an inversion channel region, a gate terminal, a drift region between the body region and the drain region and having an accumulation channel region, and a drift control region adjacent to the accumulation channel region. The accumulation channel region is controllable through the drift control region. The solid-state bidirectional switch further includes a controller connected with the gate terminals of the first and second power field-effect transistors.