Solid-State Relay Isolator Circuit Prevents Ground Current Activation
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Solution Overview
Problem
Multi-channel solid-state relay circuits face issues with unintended activation due to current flow through a common ground, leading to inefficient design with multiple isolated gate drive power supplies, which increases circuit area and cost.
Innovation Solution
A multi-channel solid-state relay circuit using a single isolated power supply and a multi-channel isolator circuit, with diodes to block current flow from ground into MOSFETs, and a high-impedance voltage translation circuit to prevent leakage current, reducing the risk of unintended activation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If multiple isolated gate drive power supplies are used for each channel, then reliability is improved by preventing unintended activation, but device complexity and cost increase
Solution Approach 1:
The patent combines multiple isolated power supplies into a single isolated power supply that serves all channels. The isolator circuit provides galvanic isolation between the control circuit and power circuit, while a single power supply voltage is distributed to multiple channels through this isolated interface, eliminating the need for multiple separate isolated power supplies and reducing overall system complexity
Solution Approach 2:
The single isolated power supply is designed to serve multiple channels universally. The isolator circuit acts as a multi-functional component that simultaneously provides galvanic isolation, voltage distribution, and control signal transmission to multiple channels, replacing what would traditionally require multiple dedicated power supplies
2Reliability
If multiple isolated gate drive power supplies are used for each channel, then reliability is improved by preventing unintended activation, but circuit area and cost increase
Solution Approach 1:
The patent merges multiple power supply circuits into a single isolated power supply unit. By consolidating the power distribution function into one isolated interface, the total circuit board area required is significantly reduced compared to having separate isolated power supplies for each channel
3Reliability
If diodes are added to block current flow from ground, then reliability is improved by preventing unintended MOSFET activation, but device complexity increases
Solution Approach 1:
The patent addresses the harmful effect of ground current by using diodes to block unwanted current flow. The diodes are strategically placed to prevent ground current from activating MOSFETs unintentionally, while the isolator circuit's high-impedance output further enhances this protective effect by minimizing leakage current paths
4Reliability
If high-impedance voltage translation circuit is used, then reliability is improved by preventing leakage current, but device complexity increases
Solution Approach 1:
The isolator circuit acts as an intermediary between the control circuit and power circuit. Its high-impedance output stage serves as a mediator that blocks leakage current paths while still enabling proper voltage translation and MOSFET gate drive, thus improving reliability without requiring additional complex protective circuits
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 effectively reduces circuit area and cost while preventing unintended activation of solid-state relays, enhancing reliability and efficiency by using a single isolated power supply to drive multiple channels with improved isolation and impedance management.
Implementation Method 1
The diode is coupled to the first transistor, the second transistor, and ground, and is configured to block current flow from ground to the first transistor and the second transistor
Implementation Method 2
an isolator circuit coupled to the output switch and configured to activate the first transistor and the second transistor
Data Source
AI summary
A solid-state relay circuit includes an isolator circuit, a first output terminal, a second output terminal, and an output switch. The output switch is coupled to the isolator circuit, and includes a first transistor, a second transistor, and a diode. The first transistor is coupled to the first output terminal. The second transistor is coupled to the first transistor and the second output terminal. The diode is coupled to the first transistor, the second transistor, and ground, and is configured to block current flow from ground to the first transistor and the second transistor. The isolator circuit is coupled to the output switch and is configured to activate the first transistor and the second transistor.