Galvanically Isolated Switch Circuit Using Series Low-Voltage FETs
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Solution Overview
Problem
High voltage field effect transistors used in resonant systems are complex and costly due to the need for high voltage control blocks and level shifters, which increase system complexity and cost.
Innovation Solution
A galvanically isolated switch system using lower voltage transistors with a bleed circuit and passive components, allowing for series connection and isolation of control inputs from DC voltages, reducing system complexity and cost while maintaining performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If high voltage field effect transistors are used to implement switches in resonant systems, then the system can handle high voltages, but the system complexity and cost increase due to control blocks and level shifters
Solution Approach 1:
A galvanic isolation circuit is introduced as an intermediary between the control input and the high voltage switch. This isolation circuit transfers control signals across galvanic isolation barriers using magnetic coupling or capacitive coupling, eliminating the need for high voltage control blocks and level shifters on the high voltage side while maintaining the ability to control high voltage switches.
Solution Approach 2:
The system is divided into two electrically isolated domains: a low voltage control domain and a high voltage power domain. The galvanic isolation creates separate ground references and voltage domains, allowing each domain to be optimized independently - low voltage components for control and high voltage components for power handling, without requiring complex high voltage control circuitry.
2Strength
If high voltage field effect transistors with control blocks and level shifters are used, then high voltage switching is achieved, but the system cost increases
Solution Approach 1:
The galvanic isolation circuit serves as a cost-effective intermediary that replaces expensive high voltage control blocks and level shifters. By using standard low voltage logic to control high voltage switches through the isolation barrier, the system eliminates costly high voltage control circuitry while maintaining full switching capability.
Solution Approach 2:
The invention uses standard, inexpensive low voltage logic components and passive isolation elements (transformers, capacitors) to control high voltage switches, replacing the need for expensive high voltage control circuitry. The isolation circuit uses commodity components rather than specialized high voltage control devices.
3Device complexity
If galvanic isolation is implemented using the disclosed system, then lower voltage transistors can be used, but additional passive components are required
Solution Approach 1:
The galvanic isolation circuit performs multiple functions simultaneously: it provides electrical isolation between control and power domains, transfers control signals, blocks high voltage from reaching low voltage components, and provides galvanic isolation for ground references. This multi-functionality consolidates what would otherwise require multiple separate components into a single integrated solution.
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 a lower cost, higher performance switch system by utilizing lower voltage transistors and passive components, simplifying the system architecture and reducing the need for high voltage components, thereby lowering overall system complexity and cost.
Implementation Method 1
at least one passive component is connected across the plurality of switches
Data Source
AI summary
A galvanically isolated switch system and method comprising a plurality of switches having at least one terminal in series electrical connection, at least one control input electrically connected to at least one of the plurality of switches, wherein the at least one control input is isolated from direct current voltages and at least one passive component connected across the plurality of switches.