Distributed Propulsion Inverter Topology for High-Frequency Motor Start
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Solution Overview
Problem
High frequency, high speed AC electric motors in hybrid propulsion systems face challenges in efficient starting due to mismatched frequency and reactive power, and AC bus wires are heavier and more lossy compared to DC bus wires.
Innovation Solution
A hybrid propulsion system utilizing a configurable converter (inverter-converter-inverter combination) to start high frequency AC electric motors by converting and matching the starting power to the main power frequency, and injecting reactive power to optimize motor operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Weight of moving object
If DC power distribution system is used with AC electric motors, then wiring weight is reduced, but full size power inverters are required at each motor which adds weight and reduces efficiency
Solution Approach 1:
The patent combines multiple power inversion functions into a single centralized inverter unit. Instead of having full-size inverters at each motor location, one inverter serves multiple AC electric motors, reducing the total number of inverters and their individual sizes while maintaining the ability to provide DC power to multiple motors through the DC bus wires.
Solution Approach 2:
The single inverter unit is designed to serve multiple functions by powering multiple different AC electric motors throughout the aircraft. This multi-functional approach allows one inverter to replace what would traditionally require multiple separate inverter units, reducing overall system weight and complexity.
2Ease of operation
If AC power distribution system is used, then direct power delivery to AC motors is possible, but AC bus wires are heavier and more lossy compared to DC bus wires
Solution Approach 1:
The patent introduces a DC bus wire system as an intermediary between the inverter and multiple AC motors. The single inverter converts AC to DC and delivers power through lightweight DC bus wires to various motors, which then use local rectifier-inverter units to convert the DC power back to AC. This intermediary DC distribution system replaces heavy AC bus wires with lighter DC wires.
3Device complexity
If high frequency AC electric motors are started directly from AC power source, then simple connection is possible, but frequency and reactive power mismatch prevents efficient motor start
Solution Approach 1:
The patent changes the electrical parameters (frequency and power factor) of the power supplied to the motor during starting. The local rectifier-inverter unit at each motor converts DC bus power to AC with controlled frequency and reactive power characteristics that match the motor's starting requirements, enabling efficient starting of high-frequency motors without complex external starting equipment.
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
Enables efficient starting and operation of high speed, high power density AC electric motors with reduced system weight and cost, while maintaining high efficiency and stability.
Implementation Method 1
controllably providing a first power to a first bus and a first inverter, electrically coupling a first motor with a second inverter by way of a second bus, operably converting, by the second inverter, the first power received by the first inverter to a starting power adapted for starting the first motor
Data Source
AI summary
A method and system for operating a hybrid propulsion system, includes controllably providing a first power to a first bus and a first inverter, electrically coupling a first motor with a second inverter by way of a second bus, operably converting, by the second inverter, the first power received by the first inverter to a starting power adapted for starting the first motor, and increasing, by the second inverter, the starting power to match the first power received.