Induction Motor Phase-Shift Oscillator for Higher Power-to-Weight
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Solution Overview
Problem
Induction machines have a low power-to-weight ratio, particularly in single-phase machines, which are hindered by the need for large capacitors and winding ratios, making them impractical for aircraft propulsion.
Innovation Solution
Implementing a phase-shift oscillator with transistors and RC-based phase-shift networks to generate a rotating magnetic field without series capacitors, utilizing dual pole windings and higher frequency switching with GaN-based HEMTs to enhance power-to-weight ratio and torque production.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If large capacitors are used in single-phase induction machines to achieve large power outputs, then the power output is improved, but the weight increases and power-to-weight ratio deteriorates
Solution Approach 1:
The patent removes the large series capacitor from the circuit by replacing it with a phase-shift oscillator circuit comprising transistors and RC networks. This extraction of the problematic capacitor component directly addresses the weight issue while maintaining the necessary phase shift functionality for single-phase to polyphase conversion.
Solution Approach 2:
The patent replaces the passive capacitor-based phase shifting mechanism with an active electronic phase-shift oscillator using transistors and RC networks. This substitution enables dynamic phase control and eliminates the need for bulky capacitors, thereby improving the power-to-weight ratio.
2Power
If large winding ratios are used to achieve large power outputs, then the power output is improved, but the device complexity and size increase
Solution Approach 1:
The patent changes the operating frequency parameter by using higher frequency switching with GaN-based HEMTs. This frequency parameter change allows for reduced winding ratios while maintaining power output, as higher frequencies enable more efficient magnetic coupling and energy transfer with fewer turns.
3Device complexity
If conventional capacitor-based phase shifting is used, then the machine structure is simple, but the weight and size increase due to large capacitors
Solution Approach 1:
The patent extracts and removes the large series capacitor from the traditional single-phase induction machine circuit, replacing its phase-shifting function with an active electronic oscillator circuit that uses transistors and small RC components, thereby eliminating the weight penalty.
Solution Approach 2:
The phase-shift oscillator circuit acts as an intermediary device that converts single-phase input to polyphase output signals. This intermediary circuitry using transistors and RC networks provides the necessary phase shift without requiring large capacitors, bridging the gap between simple structure and low weight.
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 enables smaller, more compact induction motors with improved power-to-weight ratio, suitable for aircraft propulsion systems, enhancing battery longevity and aircraft performance.
Implementation Method 1
electric currents are induced in the rotor from the alternating magnetic fields of the stator windings
Implementation Method 2
The phase-shift oscillator is configured to provide a first phase electric signal at the first node and a second phase electric signal at the second node. A difference between the first and second phase corresponds to the first angle.
Implementation Method 3
the induced currents produce counteracting magnetic fields and creates torque, causing the rotor to rotate
Implementation Method 4
the induced currents produce counteracting magnetic fields and creates torque
Data Source
AI summary
There is provided an induction machine (100) comprising a rotor (120); a stator (140); and a phase-shift oscillator (160). The stator comprises: a first winding (141); and a second winding (142), arranged at a first angle (101) relative to said first winding. The phase-shift oscillator comprises: a transistor (170), the transistor (170) being a high-electron mobility transistor, HEMT; and a phase-shift network (180). The first winding is connected to a first node (181) of the phase-shift network and wherein the second winding is connected to a second node (182) of the phase-shift network, wherein the phase-shift oscillator is configured to provide a first phase electric signal at the first node and a second phase electric signal at the second node, wherein a difference between the first and second phase corresponds to the first angle. There is also provided an electric aircraft propulsion system comprising the induction machine.