Dual-Motor Propulsion Torque Band Switching to Cut Field Weakening Losses
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Solution Overview
Problem
Conventional electric propulsion systems in vehicles face inefficiencies due to field weakening losses and under-utilized motor power, especially when operating outside optimal torque ranges, leading to suboptimal performance in varying driving conditions.
Innovation Solution
A dual electric machine propulsion system with distinct sets of machine windings for different torque bands, allowing a controller to selectively engage the appropriate electric machine based on the vehicle's operating state, optimizing performance for both low-power commuter and high-power driving states by adjusting the number of series turns per phase.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single electric motor is used to cover all operating conditions, then the device complexity is reduced, but the motor operates inefficiently outside optimal torque ranges causing field weakening losses and under-utilized motor power
Solution Approach 1:
The propulsion system is segmented into multiple electric motors, each optimized for specific torque bands. The first electric motor has machine windings configured for low-power operating states, while the second electric motor has machine windings configured for high-power operating states. This segmentation allows each motor to operate within its optimal efficiency range, eliminating field weakening losses that occur when a single motor operates outside its optimal torque range.
2Device complexity
If a single electric motor is used to cover all operating conditions, then the device complexity is reduced, but the motor power is under-utilized in varying driving conditions
Solution Approach 1:
The system divides the power delivery function across multiple motors with different power characteristics. The first electric motor delivers optimal power for low-power driving states, while the second electric motor delivers optimal power for high-power driving states. This ensures that motor power is fully utilized in each operating condition without under-utilization.
Solution Approach 2:
The system changes the operating parameters by selecting different motors based on the required power level. The controller monitors driving conditions and switches between the first and second electric motors to match the power demand, ensuring optimal power utilization across the entire operating range from low-power commuter driving to high-power performance driving.
3Loss of energy
If multiple electric motors with different winding configurations are used, then performance is optimized across different torque bands, but the device complexity increases
Solution Approach 1:
The propulsion system is divided into multiple specialized motors, each with machine windings optimized for specific torque bands. This segmentation minimizes power and torque losses by ensuring each motor operates within its optimal efficiency range, accepting the increased device complexity as a trade-off for energy efficiency.
Solution Approach 2:
The propulsion system achieves multi-functionality by incorporating motors that can handle different operating states. The first electric motor handles low-power states while the second electric motor handles high-power states, creating a universal system that efficiently covers the entire operating range despite the increased number of components.
4Ease of manufacture
If a single motor configuration is used, then the manufacturing and control are simpler, but the system cannot efficiently handle varying driving conditions from low-power to high-power states
Solution Approach 1:
The system uses multiple motor configurations with different machine winding parameters to address varying driving conditions. The first electric motor is manufactured with windings optimized for low-power states, while the second electric motor has windings optimized for high-power states. This segmentation improves adaptability across driving conditions while maintaining standardized manufacturing processes for each motor type.
Solution Approach 2:
The system employs different motor configurations with varying machine winding parameters (number of series turns per phase) to optimize performance for different driving conditions. The controller selects the appropriate motor configuration based on the required power level, enabling the system to efficiently handle the full range from low-power commuter driving to high-power performance driving while maintaining manufacturability through standardized motor designs.
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 enhances vehicle performance by minimizing power and torque losses across different driving conditions, ensuring efficient energy use and optimal propulsion whether in low-power or high-power modes.
Implementation Method 1
a first electric machine including a first set of machine windings that are configured to cause a rotor to rotate about an axis to selectively drive a transmission during a first vehicle operating state and a second electric machine including a second set of machine windings that are configured to cause a rotor to rotate about an axis selectively drive the transmission during at least one of the first vehicle operating state or a second vehicle operating state
Data Source
AI summary
The present disclosure discloses a vehicle propulsion system. The vehicle propulsion system includes a first electric machine including a first set of machine windings that are configured to cause a rotor to rotate about an axis to selectively drive a transmission during a first vehicle operating state and a second electric machine including a second set of machine windings that are configured to cause a rotor to rotate about an axis selectively drive the transmission during at least one of the first vehicle operating state or a second vehicle operating state. The second vehicle operating state different from the first operating state, and a number of series turns per phase for the first set of machine windings is different from a number of series turns per phase for the second set of machine windings.