Dual-Winding EV Motor Layout for PWM Harmonic Isolation
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Solution Overview
Problem
Dual-winding three-phase electric machines in electric vehicles experience severe circulating current and current harmonics during interleaved pulse-width-modulation (PWM) control, undermining controllability, efficiency, and noise, vibration, and harshness (NVH) of the electric drive system due to strong electromagnetic coupling between their windings.
Innovation Solution
The electric motor incorporates a dual-winding configuration with spatially separated and electromagnetically isolated stator windings, where each set of windings is supplied with a differently phased PWM signal, and operates using PWM interleaving to inhibit circulating current and harmonics, enhancing controllability and efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If dual-winding configuration with strong electromagnetic coupling is used, then power density and efficiency are improved, but circulating current and current harmonics increase severely
Solution Approach 1:
The stator windings are segmented into two spatially separated sets: a first set wound about first portions of stator teeth and a second set wound about second portions of stator teeth. This segmentation physically divides the winding system into distinct spatial zones, reducing electromagnetic coupling between windings while maintaining the dual-winding configuration's power density benefits.
Solution Approach 2:
Different regions of the stator are assigned different winding characteristics. The first set of windings is localized to specific portions of stator teeth, while the second set is localized to other portions. This local differentiation allows each winding set to operate with optimized characteristics while minimizing interference between them.
2Ease of operation
If PWM interleaving control is applied, then controllability and efficiency are improved, but circulating current and harmonics are generated due to strong coupling
Solution Approach 1:
The control system segments the PWM signaling into separate control channels for each winding set. By controlling the first and second sets of windings independently through spatial separation, the system maintains PWM interleaving's controllability advantages while preventing the circulating current issues that arise from coupled windings.
3Productivity
If windings are closely coupled for high power density, then efficiency improves, but noise, vibration and harshness (NVH) deteriorate
Solution Approach 1:
The stator windings are segmented into spatially separated first and second sets, which reduces electromagnetic coupling and thereby reduces the electromagnetic forces that generate noise, vibration, and harshness. This segmentation allows the motor to maintain efficiency while significantly improving NVH performance.
Solution Approach 2:
Different spatial regions of the stator are assigned different winding sets with optimized local characteristics. This local differentiation reduces unwanted electromagnetic interactions and vibrations while maintaining overall motor efficiency.
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 reduces current ripple, torque ripple, and capacitor current, improves efficiency, and minimizes noise, vibration, and harshness (NVH), while eliminating the need for onboard power transfer modules, thereby reducing costs and improving fault tolerance.
Implementation Method 1
a control module is configured to supply a first pulse-width-modulation (PWM) signal to the first set of stator windings and a second PWM signal to the second set of stator windings
Implementation Method 2
a first set of stator windings wound in a first portion of the multiple slots about a first portion of the multiple teeth
Implementation Method 3
the first set of stator windings is electromagnetically isolated from the second set of stator windings to inhibit circulating current and current harmonics due to the PWM interleaving
Data Source
AI summary
A dual-winding electric motor for an electric vehicle includes a stator core including multiple teeth, multiple slots defined between the multiple teeth, a first set of stator windings wound in a first portion of the multiple slots, a second set of stator windings wound in a second portion of the multiple slots, and a control module is configured to supply a first pulse-width-modulation (PWM) signal to the first set of stator windings and a second PWM signal to the second set of stator windings. The first PWM signal has a different phase than the second PWM signal and the dual-winding electric motor operates according to PWM interleaving, and the first portion of the multiple teeth having the first set of stator windings is spatially separated from the second portion of the multiple teeth having the second set of stator windings.