Electric Motor Stator Field Control for Power Shaft Rotation
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Solution Overview
Problem
Conventional vehicles experience shock and torque issues when shifting from parking to running position due to unnecessary rotation of the power shaft, which can be detrimental to the vehicle's mechanical components.
Innovation Solution
A vehicle system comprising a mechanical power source, an electric motor with a rotor connected to a power shaft, an accumulator for power exchange, and a control module that fixes the magnetic field direction of the electric motor's stator based on the mechanical power source's drive state to limit rotor rotation when the shift lever is in the parking position, preventing power shaft rotation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the electric motor is allowed to rotate freely when the shift lever is in the parking position, then the motor can operate normally for power output, but the power shaft rotates unnecessarily causing shock and torque transmission when shifting from parking to running position
Solution Approach 1:
The control module changes the magnetic field parameters of the electric motor by fixing the stator magnetic field direction when the shift lever is in the parking position. This parameter change causes the motor to generate braking torque that prevents power shaft rotation, resolving the contradiction between allowing motor operation and preventing unnecessary shaft rotation that causes shock during shifting.
Solution Approach 2:
Instead of using a mechanical locking mechanism to prevent power shaft rotation, the invention substitutes a magnetic field control system. The control module uses electromagnetic principles to fix the stator magnetic field direction, creating an electromagnetic braking effect that replaces what would traditionally require mechanical constraints, thereby preventing shock and torque transmission during shifting.
2Reliability
If the stator magnetic field direction is fixed to limit rotor rotation, then power shaft rotation is prevented reducing shock, but the control system becomes more complex
Solution Approach 1:
The control module performs multiple functions: it normally controls motor operation for power output and simultaneously fixes the stator magnetic field direction to prevent power shaft rotation when the shift lever is in the parking position. By making the control module multi-functional, the invention avoids adding separate mechanical locking mechanisms, thereby managing control system complexity while achieving shock prevention.
Solution Approach 2:
The electric motor's own magnetic field system is used to prevent its own unwanted rotation. The control module fixes the stator magnetic field direction, and the motor's electromagnetic characteristics naturally produce the braking effect needed to limit rotor and power shaft rotation. This self-service approach eliminates the need for external mechanical braking or locking systems.
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 solution effectively minimizes power shaft rotation during shifts, reducing shock and torque transmission, thereby enhancing mechanical component durability and efficiency.
Implementation Method 1
an electric motor which has a rotor connected to the power shaft, and causes the rotor to rotate with a rotating magnetic field of a stator to input and output the mechanical power to and from the power shaft
Implementation Method 2
the magnetic field direction of the stator is fixed based on a drive state of the mechanical power source to limit the rotation of the rotor
Data Source
AI summary
When a shift lever is in a parking position, a rotation restriction index Jm2 is set based on a drive state of an engine or a first motor (S130, S160, S240, and S290). A current value based on the rotation restriction index Jm2 is set to a current command of the d axis in an electric angle when motoring of the engine in a stop state is started and a second motor is controlled such that the magnetic field direction of a stator of the second motor is fixed. This method can appropriately prevent a power shaft from rotating.