Motor-Inverter Layout for Equal Inductance in Vehicle Drive Units
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Solution Overview
Problem
Existing vehicle drive units face challenges in reducing the size and weight of inverters while maintaining high power transmission efficiency, leading to increased heat generation, noise, vibration, and electromagnetic interference due to large electrical connection members and uneven inductances between phase power modules and motor coils.
Innovation Solution
The drive unit design includes adjacent placement of a motor and inverter with parallel-connected power modules, where each power module group is connected to corresponding coil groups, reducing axial length and equalizing inductances between phases by optimizing the placement and configuration of power modules and coils.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If the inverter is made large and heavy to handle high electric power, then the power transmission capability is improved, but the device size and weight increase, making it difficult to dispose in a car
Solution Approach 1:
The inverter is integrated with the motor by disposing the power modules on the motor housing, merging two previously separate components into a combined unit. This eliminates the need for a separate inverter housing and reduces overall system weight while maintaining high power transmission capability.
Solution Approach 2:
The power modules are arranged in a multi-dimensional configuration on the motor housing surface, utilizing the available space in radial and axial directions. This optimized spatial arrangement reduces the overall footprint and weight of the inverter system while preserving electrical performance.
2Ease of operation
If the wiring length of the electrical connection member increases to connect power modules and coils, then the electrical resistance increases, causing copper loss and heat generation
Solution Approach 1:
The electrical connection system is segmented into multiple short connection paths by connecting each power module directly to its corresponding phase coil group. This segmentation eliminates the need for long centralized wiring, reducing cumulative electrical resistance and copper losses.
Solution Approach 2:
The motor housing serves as an intermediary structure that provides both mechanical support and electrical connection pathways. By utilizing the housing as a mounting platform and electrical conduit, the design minimizes external wiring length while maintaining connectability.
3Volume of stationary object
If the inverter is integrated with the motor to reduce size, then the device size is reduced, but the inductances of electrical paths may become uneven, affecting motor control
Solution Approach 1:
The electrical connection configuration is optimized locally at each phase by positioning power modules and connection members to achieve equal inductance values for U, V, and W phases. This local optimization ensures balanced motor control performance while maintaining compact integrated dimensions.
Solution Approach 2:
The power modules are asymmetrically positioned on the motor housing to compensate for variations in electrical path lengths and geometries. By introducing asymmetric adjustments in positioning and connection routing, the design achieves symmetric electrical characteristics (equal inductances) despite the asymmetric physical layout.
4Length of stationary object
If power modules are placed adjacent to each other on a placement surface, then the axial length is reduced, but the electrical connection paths may become complex
Solution Approach 1:
The motor housing serves multiple functions: it provides mechanical support for the motor, serves as a mounting platform for power modules, and acts as an electrical connection conduit. This multi-functionality simplifies the overall electrical connection architecture by eliminating the need for separate connection components.
Solution Approach 2:
The electrical connection design ensures that all power modules and their corresponding coils are positioned to achieve equal inductance values, creating equipotential conditions for balanced three-phase operation. This approach simplifies control by eliminating the need for complex compensation algorithms.
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 increases motor output, reduces and equalizes inductances of electrical paths, minimizing size and weight while reducing noise and energy losses, thus enhancing the overall performance and efficiency of the drive unit.
Implementation Method 1
A drive unit that drives a motor by converting direct current from a battery into alternating current by an inverter
Implementation Method 2
Each phase power module of the inverter is connected to a corresponding one of the phase coils of the motor via an electrical connection member
Implementation Method 3
since the large current is turned on and off at a high speed by switching control, a large change in magnetic field occurs in the electrical connection member. Therefore, when the inverter operates, noise, vibration, electromagnetic interference, and the like occur at the electrical connection member due to the changing magnetic field
Data Source
AI summary
In a drive unit, a motor and an inverter having power modules are disposed adjacent in an axial direction of the motor. In the motor, first and second coil groups, each including one U-phase coil, one V-phase coil, and one W-phase coil, are provided. The power modules constitute first and second power module groups that are connected in parallel. The first and second power module groups each include one U-phase power module, one V-phase power module, and one W-phase power module. A distance between the U-phase power module of the first power module group and the U-phase coil of the first coil group, a distance between the V-phase power module of the first power module group and the V-phase coil of the first coil group, and a distance between the W-phase power module of the first power module group and the W-phase coil of the first coil group are equal.