Industrial Consultancy & Sponsored Research (IC&SR) , IIT Madras
A Split-tapped Topology Of Interior Permanent Magnet Synchronous Machine For Electric Vehicles
Technology Category/Market
Category- Automobile & Transportation
Industry Classification:
Electric Vehicles; Powertrain Systems; Power Electronics
Applications:
Transmission for Electric Vehicles; Hybrid Electric Systems; Low-Voltage EV Systems
Market report:
The global electric vehicle (EV) transmission market size was valued at USD 11.32 billion in 2024 is projected to grow to USD 28.99 billion by 2032 exhibiting a CAGR of 12.2%
Problem Statement
- Multi-speed transmission technology for electric vehicles (EVs) enhances efficiency, and optimizes performance across varying speed modes.
- Conventional EVs use either mechanical gearboxes or single-inverter systems to manage speed, torque, and performance adjustments. However, these systems are bulky, complex and require higher battery voltage, leading to inefficiencies, increased costs, and reduced reliability.
- There is a need for an improved system that offers better torque-speed control, lower voltage requirements, and enhanced reliability over traditional methods
Technology
- The Split-Tapped Interior Permanent Magnet Synchronous Motor (ST-IPMSM) offers a 3-speed transmission system for electric vehicles, utilizing split winding configurations and two voltage source inverters for precise torque-speed control and enhanced efficiency.
- Split ratio and tap ratio define winding configurations, with tested values of 0.75 and 0.667, respectively. The motor operates with a common DC bus voltage of 320V, reducing voltage requirements by up to 26%.
- Achieves higher power factor and efficiency in the field-weakening region, ensuring optimal energy usage across speed stages. The system supports flexible torque ratio based on application requirement.
- Two independent inverters allow uninterrupted power during stage transitions, enabling reliable operation and fault tolerance. Smooth winding change-over ensures continuous operation even under demanding conditions.
- Reduces mechanical complexity, operational costs, and energy consumption. Supports diverse EV applications with customizable torque-speed profiles, providing superior adaptability, scalability, and significant long-term cost savings for manufacturers.
Key Features/Value Proposition
- The ST-IPMSM achieves higher efficiency, especially in the field-weakening region, by leveraging split winding configurations and dual inverters, reducing energy losses compared to conventional single-inverter or mechanical transmission systems.
- The system reduces DC bus voltage by up to 26%, lowering battery and inverter specifications. This minimizes costs and enhances compatibility with lower voltage systems compared to conventional tapped winding or multi-phase topologies.
- Dual inverters provide redundancy, enabling uninterrupted operation during faults or stage transitions. Conventional systems lack this feature, making them less reliable in real-world applications.
- The invention supports precise torque-speed ratios tailored to specific vehicle requirements, unlike traditional systems that lack flexibility or require oversizing motors for broad application ranges.
- By eliminating mechanical gearboxes and utilizing efficient winding reconfiguration, the ST-IPMSM reduces mechanical complexity, maintenance needs, and manufacturing costs compared to gear-based or complex inverter-driven systems.
Questions about this Technology?
Contact for Licensing
Research Lab
Prof. Kamalesh Hatua
Department of Electrical Engineering
Intellectual Property
- IITM IDF Ref 2935
- IN 202441037588 Patent Application
Technology Readiness Level
TRL 4
Technology Validated in Lab