Short-Pitch Motor Winding Layout for Common-Mode Harmonic Cancellation
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Solution Overview
Problem
In high-performance motor driving systems for electric vehicles, the existing motor winding patterns fail to effectively cancel common mode harmonics, leading to increased noise, vibration, and harshness (NVH) as well as efficiency losses due to uncancelled common mode currents.
Innovation Solution
A motor winding pattern is implemented where coils with alternating current phases are wound in a short-pitch manner with a 60-degree electric angle difference, allowing harmonics generated in the basic and short-pitch parts to cancel each other out, and a motor driving system with a switch to control inverter connections based on driving modes to optimize efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If a conventional winding pattern is used in a two-inverter motor driving system, then the motor can operate in high-performance modes, but common mode currents are generated causing increased noise, vibration, and harshness (NVH)
Solution Approach 1:
The patent changes the winding parameters by implementing a short-pitch winding pattern where coils are wound with a pitch less than the pole pitch. Specifically, the winding pattern is designed so that harmonics generated in different coil groups have phase differences that cause them to cancel each other out, thereby eliminating common mode currents while maintaining high power output capability
Solution Approach 2:
The patent converts the harmful common mode currents into beneficial canceling harmonics. By carefully designing the winding pattern with specific pitch angles and coil arrangements, the harmonics that would normally cause NVH problems are made to oppose and cancel each other, transforming a harmful effect into a beneficial cancellation mechanism
2Ease of manufacture
If a conventional winding pattern is used, then the motor structure is simple, but harmonics cannot be cancelled leading to increased loss and reduced efficiency
Solution Approach 1:
The patent modifies the winding parameters including pitch angle, coil distribution, and phase arrangements to create a pattern where harmonics naturally cancel. This parameter optimization achieves harmonic cancellation without requiring complex additional components or structures, maintaining ease of manufacture while reducing energy loss from harmonics
3Use of energy by moving object
If two inverters are connected to the motor, then high efficiency can be achieved in different driving modes, but harmonics are generated that increase NVH and loss
Solution Approach 1:
The patent optimizes the winding parameters including pitch, distribution, and phase connections to ensure that when two inverters are connected, the harmonic voltages generated by each inverter path are equal in magnitude but opposite in phase, causing them to cancel each other out. This allows efficient operation in different driving modes without the harmful effects of harmonics
Data Source
AI summary
A motor winding pattern is provided. In a driving system in which a first inverter and a second inverter are connected to a drive motor, and one end of a stator winding through which a three phase currents flow is connected to an output line of the first inverter, and the other end of the stator winding is connected to an output line of the second inverter, coils to which three phase currents are applied are wound on slots defined in a stator of the drive motor, and coils to which alternating current phases different from each other are applied are wound inside and outside each of all the slots defined in the stator on the basis of direction toward a rotation axis of the drive motor.