Motor Inverter Voltage Switching for High-Altitude Reliability
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Solution Overview
Problem
Motor control devices used in high-altitude applications face increased failure rates due to cosmic rays, particularly neutron beams, which reduce reliability and efficiency, as high DC-link voltages exacerbate single event effects on semiconductor elements.
Innovation Solution
A motor control device that includes a step-down device to reduce DC power from a DC distribution network to a lower voltage, a power supply device to convert the power to AC, and a control device to switch between two operation modes based on flight information and environmental factors, specifically reducing the DC-link voltage during high-altitude operations to mitigate cosmic ray exposure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Weight of stationary object
If high DC-link voltage is used in the inverter, then current is reduced and wiring weight is decreased, but cosmic ray resistance is reduced and single event failures become more likely
Solution Approach 1:
The patent implements dynamic voltage adjustment by switching between two operation modes: a first mode with higher DC-link voltage for ground/low-altitude operation, and a second mode with lower DC-link voltage for high-altitude operation where cosmic ray exposure is significant. This dynamic adaptation allows the system to optimize both wiring weight and cosmic ray resistance based on operational conditions.
Solution Approach 2:
The patent changes the DC-link voltage parameter based on operational conditions. By detecting flight information and environmental factors, the control device adjusts the DC-link voltage level, switching between high voltage (for weight reduction) and low voltage (for cosmic ray resistance), thereby resolving the contradiction between these two parameters.
2Productivity
If DC-link voltage is constantly set in high-voltage state, then power transmission efficiency is improved, but failure rate due to single event increases at high altitude
Solution Approach 1:
The system dynamically adjusts the DC-link voltage based on altitude and environmental conditions. During high-altitude flight where cosmic ray exposure is high, the system switches to lower voltage operation to reduce single event failures. During ground operation or low-altitude flight, the system operates at higher voltage to maximize power transmission efficiency.
Solution Approach 2:
The patent implements parameter changes by adjusting the DC-link voltage level according to operational context. The control device monitors flight information and environmental factors, then switches between high-voltage mode (for efficiency) and low-voltage mode (for reliability at high altitude), resolving the contradiction between productivity and reliability.
3Reliability
If voltage is reduced to mitigate cosmic ray effects, then reliability is improved, but power transmission capability is reduced
Solution Approach 1:
The system dynamically adjusts voltage based on operational needs. When operating at high altitude where cosmic ray exposure is significant, the system reduces voltage to improve reliability. When operating at ground level or low altitude where cosmic ray effects are minimal, the system increases voltage to maximize power transmission capability.
Solution Approach 2:
The patent implements parameter changes by adjusting DC-link voltage according to environmental conditions. The control device switches between high-voltage operation (for power transmission capability) and low-voltage operation (for reliability at high altitude), thereby resolving the contradiction between these two parameters based on operational context.
Data Source
AI summary
A motor control device includes: a step-down device including a DC-output power conversion device having a first mode for outputting first voltage and a second mode for outputting second voltage lower than the first voltage; a power supply device; and a control device, and controls a motor. When a flying object takes off, the control device controls the power conversion device in the first mode. When the control device judges that flight information which is one or both of information of a motor parameter obtained along with control for the motor and information of an environmental factor relevant to the flight altitude of satisfies a predetermined condition, or when the control device has received an mode signal for which the second mode is selected on the basis of the flight information during control for the motor, the control device controls the power conversion device in the second mode.