Vehicle Drive Motor Pulsation for Driver State Recognition
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Solution Overview
Problem
In electric vehicles, the lack of engine vibration makes it difficult for drivers accustomed to internal combustion engines to recognize the vehicle's operation state, leading to a sense of discomfort.
Innovation Solution
A vehicle drive system with a cylindrical stator and rotor that generates pulsation by varying the number of poles in the stator through an asynchronous operation mode, using a control section to adjust the current flow in primary conductors, allowing drivers to recognize operation states through motor vibration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a motor is used as a drive source instead of an internal combustion engine, then vibration is reduced and less vibration is transmitted to the cabin, but the driver cannot recognize the operation state from the vibration
Solution Approach 1:
The patent applies mechanical vibration by intentionally generating pulsation in the motor during asynchronous operation. The control section creates a rotating magnetic field that interacts with the permanent magnets to produce vibration at specific frequencies (e.g., twice the power supply frequency), making the motor vibration perceptible to the driver while maintaining low overall vibration levels during normal operation.
Solution Approach 2:
The patent changes the operational parameters of the motor by switching between synchronous and asynchronous operation modes. In asynchronous mode, the motor operates with a speed difference between the rotating magnetic field and the rotor, generating pulsation that provides tactile feedback to the driver, while in synchronous mode, the motor operates efficiently with minimal vibration.
2Loss of information
If the number of poles of the stator is made different from the number of poles of the permanent magnet in asynchronous operation mode, then pulsation is generated to allow driver recognition, but the motor structure becomes more complex
Solution Approach 1:
The patent makes the motor multi-functional by equipping it with both permanent magnets for synchronous operation and secondary conductors for asynchronous operation. This allows the same motor structure to provide both efficient propulsion and tactile feedback without requiring separate systems, reducing overall device complexity while achieving the desired pulsation effect.
Solution Approach 2:
The patent employs dynamic control by switching between synchronous and asynchronous operation modes based on driving conditions. The control section adjusts the operational mode in real-time, enabling the motor to generate pulsation only when needed for driver feedback while maintaining efficient synchronous operation during normal driving, thus avoiding continuous complexity.
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 drivers to recognize acceleration and changes in travel environment by feeling motor vibrations, providing a sense of familiarity and control similar to internal combustion engine vehicles.
Implementation Method 1
a control section capable of generating a rotating magnetic field in the stator through a current supply to the primary conductor and setting a drive mode of the motor to an asynchronous operation mode in which the rotor is rotated by using an induced current generated in the secondary conductor
Implementation Method 2
The rotor has: plural secondary conductors that extend in the axial direction and are aligned in the circumferential direction in a radially outer portion; and plural permanent magnets that extend in the axial direction and are aligned in the circumferential direction in a portion on a radially inner side of these plural secondary conductors
Data Source
Figure 1
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Figure 3(a)~3(b)
AI summary
[Task] To provide a vehicle drive system capable of allowing a driver to recognize an operation state from vibration of a motor 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 and drives a drive wheel of the vehicle. The stator has plural primary conductors that are aligned in a circumferential direction. The rotor has: plural secondary conductors that are aligned in the circumferential direction in a radially outer portion; and plural permanent magnets that are aligned in the circumferential direction in a radially inner portion. An ECU and the like are further provided to generate a rotating magnetic field in the stator through a current supply to the primary conductor and to set a drive mode of the motor to an asynchronous operation mode in which the rotor is rotated by using an induced current generated in the secondary conductor. In the asynchronous operation mode (S8), the ECU and the like are configured to cause the motor to generate pulsation by making a number of poles of the stator different from a number of poles of the permanent magnet (S10).