Redundant Power Supply Inrush Protection via DC Link Precharge
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Solution Overview
Problem
Aircraft systems with redundant power supplies experience significant inrush currents when electric motors are energized, which can damage components, and existing methods to limit these currents are inefficient or require additional components like inrush resistors.
Innovation Solution
The system employs a power control circuit with redundant power channels, using both high-voltage and low-voltage power supplies to charge DC link capacitors, where one channel includes an inrush resistor and the other does not, and utilizes power converters to generate backup power signals, eliminating the need for inrush resistors in certain scenarios.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If inrush resistors are used to limit inrush current, then component damage is prevented, but device complexity and power loss increase
Solution Approach 1:
The patent charges the DC link capacitor before energizing the motor to prevent inrush current. The controller monitors capacitor voltage and only allows motor energization after the capacitor is sufficiently charged, eliminating the need for inrush resistors while preventing the harmful inrush current effect.
Solution Approach 2:
The patent removes the inrush resistor from the circuit by using a different approach - pre-charging the DC link capacitor. This extracts the harmful inrush current limitation function from the traditional resistor-based solution and implements it through control logic and capacitor pre-charge, reducing device complexity.
2Object-affected harmful factors
If inrush resistors are used to limit inrush current, then component damage is prevented, but energy efficiency decreases
Solution Approach 1:
The capacitor is charged in advance before motor operation begins. By storing energy in the DC link capacitor beforehand, the system eliminates the need for energy-dissipating inrush resistors during motor startup, significantly reducing power loss while still preventing inrush current damage.
3Reliability
If redundant high-voltage power supplies are implemented, then system reliability improves, but inrush current management becomes more complex
Solution Approach 1:
The controller monitors the voltage of each DC link capacitor and ensures they are charged before allowing their respective motors to be energized. This preliminary charging action simplifies the management of redundant power supplies by providing a clear control sequence that prevents inrush current without requiring complex protection circuitry for each redundant channel.
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 approach effectively limits inrush currents in redundant power supplies, ensuring stable power delivery to electric motors by charging capacitors before applying high-voltage signals, thereby preventing component damage and ensuring continuous operation.
Implementation Method 1
The aircraft power system may charge a DC link capacitor assembly by delivering a high-voltage power signal to the DC link capacitor assembly via an inrush resistor that limits inrush current
Implementation Method 2
DC link capacitors may be important for smoothing voltage and current variations and limiting inrush current
Implementation Method 3
In some cases, the aircraft power system boosts a low-voltage power signal to a higher voltage and delivers a boosted power signal to charge a DC link capacitor assembly
Data Source
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AI summary
A power control circuit is configured to perform one or both of: receive a first power signal comprising a first voltage and receive a second power signal comprising the first voltage. The power control circuit is also configured to perform one or both of receive a third power signal comprising a second voltage; and generate, using a power converter based on the first power signal, a fourth power signal comprising the second voltage. Additionally, the power control circuit is also configured to charge, using the first power signal, a first capacitor assembly to prevent a magnitude of a first inrush current from exceeding a threshold inrush current magnitude and charge, using one or both of the third power signal and the fourth power signal, a second capacitor assembly to prevent a magnitude of a second inrush current from exceeding the threshold inrush current magnitude.