Fractional Turn Motor Winding for Torque and Voltage Control
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Solution Overview
Problem
The existing motor winding configurations are limited to integer values of turns, which restrict the motor's capability to achieve optimal output due to the voltage exceeding allowable values at high rotational speeds when the number of turns is increased to meet torque specifications.
Innovation Solution
A motor design where the overall parallel winding is divided into partial parallel windings with varying sub-coils of different turns, allowing for a fractional number of turns to be selected, enabling the motor to operate within voltage limits across different rotational speeds.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If the number of turns is increased to meet torque specifications, then the generated torque is increased, but the voltage generated in the winding exceeds the allowable value at high rotational speeds
Solution Approach 1:
The patent divides the winding into multiple parallel circuits with different numbers of turns. Specifically, it uses a first winding with a first number of turns and a second winding with a second number of turns, where the ratio between them is a rational number. This segmentation allows the motor to achieve the desired torque while keeping the generated voltage within allowable limits by distributing the turns across multiple parallel paths.
Solution Approach 2:
The patent applies different numbers of turns to different local regions (parallel circuits) of the winding. By creating local variations in turn numbers within the overall winding structure, the motor can optimize torque generation in certain areas while controlling voltage generation in others, resolving the contradiction between torque and voltage constraints.
2Ease of manufacture
If the number of turns is set to an integer value, then the winding structure is simplified, but the motor cannot achieve optimal output due to voltage limits at high rotational speeds
Solution Approach 1:
The patent segments the winding into parallel circuits with different integer turn values. This maintains the simplicity of integer-based winding construction while achieving the functional equivalent of fractional turns through the parallel configuration, thereby preserving ease of manufacture while enabling optimal motor output.
Solution Approach 2:
The patent makes the winding structure multi-functional by having different parallel circuits serve different purposes: some circuits with more turns contribute more to torque generation, while others with fewer turns help control the overall voltage. This universal structure can adapt to both torque requirements and voltage constraints simultaneously.
3Loss of energy
If the number of parallels is adjusted to maximize winding thickness, then the resistance value is reduced and heat generation is minimized, but the lamination factor is constrained by the slot shape
Solution Approach 1:
The patent applies different numbers of parallels to different parallel circuits, allowing local optimization of current distribution. This enables the winding structure to maximize thickness and minimize resistance in specific areas while adapting to the slot shape constraints, thereby reducing heat generation without compromising lamination factor flexibility.
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 allows the motor to fully utilize its capability by enabling the selection of a fractional number of turns, thereby optimizing output and maintaining voltage within allowable limits across varying rotational speeds.
Implementation Method 1
a voltage generated in a winding in a rotor is known to be proportional to the number of turns of the winding and an amount of change, with respect to time, of a magnetic flux crossing the winding
Implementation Method 2
an electric current is applied to the winding to generate a torque and rotate the rotor
Data Source
AI summary
A motor is provided. When m is half of a number of slots of one phase and n is a divisor of m, the overall parallel winding of a total number of parallels p is equally divided n-fold into partial parallel windings Ni, having a number of parallels p/n, each partial parallel winding Ni comprises m sub-coils, the m sub-coils including n types of m/n sub-coils having a number of turns tj, at least one of the sub-coils differing in number of turns from the other sub-coils, and, for each pair of the slots in the stator, one sub-coil of each partial parallel winding Ni is wound around the pair of slots, and n sub-coils wound around the pair of the slots include every one of the n types of the sub-coils of the numbers of tj.