Aircraft SSPC Isolation Circuit for Overvoltage-Safe Switching
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Solution Overview
Problem
Existing aircraft solid state power controllers face challenges in controlling electric power supply with an electric control signal that is galvanically isolated from the power source, while preventing damage from overvoltages and negative voltages exceeding the specifications of the isolated gate driver.
Innovation Solution
The aircraft solid state power controller employs a solid state switch and an isolated gate driver with a galvanic isolation mechanism, coupled with a voltage regulator and a delay circuit to manage control signals and supply voltages, ensuring safe and reliable operation by limiting voltages and preventing leak currents.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If galvanic isolation is implemented between control signal and power source, then control signal safety is improved, but voltage regulation complexity increases
Solution Approach 1:
An isolated gate driver is introduced as an intermediary device between the control signal and the solid state switch. This gate driver provides galvanic isolation while receiving control signals on its input side and driving the solid state switch on its output side, thereby protecting the control circuit from high voltage while maintaining control functionality
Solution Approach 2:
The patent applies voltage regulation by limiting the isolated gate driver supply voltage to a maximum of 20V using a voltage regulator. This parameter change ensures that the gate driver operates within safe voltage limits while still providing sufficient drive capability for the solid state switch, resolving the contradiction between isolation safety and regulation complexity
2Reliability
If isolated gate driver supply voltage is increased to ensure proper switching, then switching reliability is improved, but risk of overvoltage damage increases
Solution Approach 1:
A voltage regulator is implemented to beforehand limit the isolated gate driver supply voltage to a maximum of 20V. This preventive measure ensures that even under varying operating conditions, the voltage never exceeds the gate driver's maximum rating, cushioning against potential overvoltage damage while maintaining sufficient voltage for reliable switching
Solution Approach 2:
The patent specifies that the isolated gate driver supply voltage shall be limited to a maximum of 20V, which is a parameter change that balances the need for sufficient switching drive capability with the protection of the gate driver from overvoltage damage. This parameter optimization resolves the contradiction between switching reliability and overvoltage risk
3Manufacturing precision
If solid state switch is used for power control, then control precision is improved, but sensitivity to voltage transients increases
Solution Approach 1:
The isolated gate driver serves as a protective intermediary between the control circuit and the solid state switch. It provides galvanic isolation that protects the precision control circuit from voltage transients and noise, while still enabling precise control of the solid state switch through regulated drive signals
Solution Approach 2:
The patent replaces traditional mechanical switching with a solid state switch controlled by an isolated gate driver. This substitution provides precise electronic control while the gate driver's isolation barrier protects the control circuit from voltage transients that would otherwise affect the sensitive solid state device
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 allows for safe and reliable switching of electric power to aircraft loads, preventing damage to the isolated gate driver and ensuring operational reliability by isolating control signals and managing voltage levels within specified ranges.
Implementation Method 1
The output side of the isolated gate driver is galvanically isolated from the input side of the isolated gate driver
Data Source
AI summary
An aircraft solid state power controller (SSPC) includes a solid state switch arranged between and electrically connected to a power supply line and an output terminal. The switch is configured to selectively supply or interrupt supply of electric power having a first voltage to an electric load in response to a control signal provided at a control terminal. The control signal has a second voltage with reference to the power supply line. The aircraft SSPC is configured to apply the second voltage as an additional voltage on top of the first voltage with respect to a ground potential. The aircraft SSPC also includes an isolated gate driver having an input side and an output side galvanically isolated from the input side. The isolated gate driver is configured to receive the control signal on the input side and to supply a drive signal to the switch on the output side.