Dual-Mode Vehicle Motor Rotor for Torque and High-Speed Output
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Solution Overview
Problem
Conventional electric vehicle motors struggle to provide a wide range of output due to limitations in both synchronous and asynchronous operations, particularly at high speeds, making it difficult to meet driver preferences and maintain comfortable vibration levels.
Innovation Solution
A vehicle drive system with a motor that switches between synchronous and asynchronous operation modes based on required output, using a cylindrical stator and rotor with permanent magnets and secondary conductors, and a control section to manage the mode switching, which also cancels out torque pulsation by superimposing opposing currents in the asynchronous mode.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If a PM motor is used to achieve maximum torque in low-speed range, then torque performance is improved, but output is reduced in high-speed range due to large back electromotive force
Solution Approach 1:
The motor dynamically switches between synchronous operation mode (using permanent magnet magnetic force) for high torque in low-speed range and asynchronous operation mode (using induced current in cage-shaped rotor) for high output in high-speed range, adapting the drive mode according to the vehicle's required output at different operating conditions
Solution Approach 2:
The control section changes the operational parameters of the motor by switching between synchronous and asynchronous operation modes based on the rotation speed and required output, thereby optimizing the balance between torque and power across the entire speed range
2Power
If a motor with cage-shaped rotor is used to achieve wide range output, then high-speed output is improved, but it is difficult to generate required output in wide range according to driver preference
Solution Approach 1:
The motor is designed with dual functionality, incorporating both permanent magnets for synchronous operation and cage-shaped rotor conductors for asynchronous operation, enabling it to perform both high-torque low-speed operation and high-power high-speed operation, thereby achieving wide-range adaptability to driver preferences
3Force
If synchronous operation mode is used, then torque is improved, but vibration is increased which causes discomfort
Solution Approach 1:
The control section detects torque pulsation in synchronous operation mode and switches to asynchronous operation mode when torque exceeds a predetermined threshold, thereby converting the harmful vibration effect into a trigger for mode switching that eliminates the vibration while maintaining high torque output
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
Enables the generation of a wide range of output according to driver preference while minimizing unpleasant vibrations, allowing drivers to recognize vehicle operation states through controlled torque pulsation.
Implementation Method 1
a synchronous operation mode in which the rotor is rotated by using a magnetic force of the permanent magnet
Implementation Method 2
an asynchronous operation mode in which the rotor is rotated by using an induced current generated in the secondary conductor
Data Source
Figure 1
Figure 2
Figure 3(a)~3(b)
AI summary
[Task] To provide a vehicle drive system capable of changing a characteristic of a motor according to a wide range of required output in a vehicle that uses the motor as a traveling drive source. [Solution] The vehicle drive system includes a motor that has a stator and a rotor provided in the stator and that drives a drive wheel of a vehicle by rotation of the rotor. The rotor has: plural secondary conductors that are aligned in a circumferential direction in a radially outer portion; and plural permanent magnets that are aligned in the circumferential direction in a portion on a radially inner side of these plural secondary conductors. An ECU and a motor ECU capable of switching a drive mode of the motor between a synchronous operation mode and an asynchronous operation mode are further provided. Based on required output for the motor (S4), the ECU and the motor ECU are configured to switch the drive mode of the motor from the synchronous operation mode to the asynchronous operation mode (S7).