Asynchronous Machine Loss Redistribution via Pole Pair Geometry
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Solution Overview
Problem
Asynchronous machines used in electric vehicles face high electrical losses and temperature issues due to high rotor currents, limiting torque output and mechanical stability, as conventional cooling methods are inefficient and costly.
Innovation Solution
The asynchronous machine is redesigned with a pole pair number of 3, increasing the rotor outer diameter and rotor tooth height, while reducing the stator yoke height, to shift electromagnetic losses from the rotor to the stator, where they can be more efficiently cooled, thereby reducing rotor losses by up to 40% and maintaining torque density.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If high rotor currents are used to provide high torque density, then torque output is improved, but electrical losses and temperature increase in the rotor worsen
Solution Approach 1:
The patent changes key geometric parameters of the asynchronous machine: increasing the rotor outer diameter to rotor-stator diameter ratio to between 0.7 and 0.9 (preferably 0.75 to 0.85), and adjusting the stator tooth height to rotor tooth height ratio to between 0.3 and 0.6 (preferably 0.35 to 0.5). These parameter changes redistribute the electromagnetic losses from the rotor to the stator, reducing rotor electrical losses by up to 40% while maintaining torque density.
2Power
If high rotor currents are used to provide high torque density, then torque output is improved, but temperature and mechanical stability in the rotor worsen
Solution Approach 1:
The patent changes key geometric parameters of the asynchronous machine: increasing the rotor outer diameter to rotor-stator diameter ratio to between 0.7 and 0.9 (preferably 0.75 to 0.85), and adjusting the stator tooth height to rotor tooth height ratio to between 0.3 and 0.6 (preferably 0.35 to 0.5). These parameter changes redistribute the electromagnetic losses from the rotor to the stator, reducing rotor electrical losses by up to 40% while maintaining torque density.
3Temperature
If conventional cooling methods are used for the rotor, then temperature control is improved, but device complexity and cost worsen
Solution Approach 1:
The patent extracts the cooling requirement from the rotor by redistributing electromagnetic losses to the stator. The stator, which has better access for cooling arrangements, absorbs the heat generation, eliminating the need for complex active cooling systems in the rotor. This simplifies the overall cooling system while maintaining effective temperature control.
4Loss of energy
If rotor outer diameter is increased to reduce electrical losses, then loss distribution is improved, but machine size worsens
Solution Approach 1:
The patent optimizes the rotor outer diameter to rotor-stator diameter ratio to a specific range of 0.7 to 0.9 (preferably 0.75 to 0.85). This controlled increase in rotor diameter redistributes electromagnetic losses effectively while limiting the overall machine size growth. The simultaneous adjustment of tooth height ratios further optimizes the loss distribution without proportionally increasing the machine volume.
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 higher continuous torque output while ensuring mechanical stability by efficiently dissipating heat through simpler stator cooling, reducing the need for active rotor cooling and minimizing the risk of component damage.
Implementation Method 1
one or multiple windings is/are housed in the stator with the aid of which it is possible to generate a rotating magnetic field in the stator. As soon as the mechanical rotational speed of the rotor differs from the synchronous rotational speed, the rotor experiences a change in the magnetic flux. As a consequence, currents are induced in the short-circuited rotor conductors. A torque occurring between the stator and the rotor is produced by means of an interaction between the rotating magnetic field of the stator and the rotor currents.
Data Source
AI summary
The invention relates to an asynchronous machine (1) as can be used particularly in electric vehicles or hybrid vehicles. The asynchronous machine (1) has a rotor (5) and a stator (3). The asynchronous machine is designed and controlled in such a manner that it has a pole pair number p of p=3. Because of the reduced yoke saturation that can consequently be achieved, the stator yoke (9) can be designed with a lesser height hy1, such that a ratio of the outer rotor diameter D2a to the outer stator diameter D1a can assume values between 0.7 and 0.8. As a result, enlarged rotor teeth (19) and correspondingly enlarged rotor grooves (21) can be formed in the rotor (5), such that electrical losses in the material in the rotor grooves (21) acting as the rotor coil element (23) are smaller in comparison to conventional asynchronous machines. The electrical losses occurring to a greater extent in the stator (3) compensating for this lead to a lesser warming of the stator (3) than would be the case with the rotor (5) as the stator (3) can be cooled by simple means. Overall, a higher continuous torque can thus be achieved with the asynchronous machine (1) according to the invention.