Induction Motor Slope Hold Torque Control
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Solution Overview
Problem
Hill starting in electric vehicles using mechanical brakes is challenging due to difficulties in cooperative control between mechanical brakes and motors, leading to potential vehicle rollback and excessive brake wear, which increases maintenance costs.
Innovation Solution
An electric drive vehicle system that employs an induction motor and motor controller to generate torque using DC or AC voltage in a specific frequency range, allowing the vehicle to start and stop on sloped roads without mechanical brakes, thereby eliminating the need for cooperative control and reducing brake wear.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If mechanical brakes are released before sufficient motor torque is generated, then the vehicle can start smoothly, but the vehicle rolls backwards
Solution Approach 1:
The motor generates required torque before the mechanical brakes are released. The control unit calculates the torque needed to counteract gravity on the slope and commands the motor to produce this torque in advance, ensuring the vehicle remains stationary until sufficient motor torque is available, preventing rollback during brake release
Solution Approach 2:
The control unit continuously monitors motor torque output and brake status to determine the optimal timing for brake release. By feedback control, the system ensures motor torque reaches the required level before releasing brakes, balancing smooth starting with position stability
2Reliability
If mechanical brakes are released immediately after sufficient torque is generated, then the vehicle starts without rollback, but the vehicle starts abruptly
Solution Approach 1:
The brake release process is made dynamic and gradual rather than instantaneous. The control unit gradually reduces brake torque over a predetermined time period after motor torque becomes sufficient, allowing smooth transition from brake-supported to motor-supported state, eliminating abrupt starting while maintaining position stability
3Reliability
If mechanical brakes are operated while motor torque is increased, then the vehicle can be held on slope, but the mechanical brakes are subject to abrasion
Solution Approach 1:
The function of holding the vehicle on the slope is extracted from the mechanical brakes and transferred to the motor. The motor generates torque to counteract gravity, completely replacing the brakes' holding function, which eliminates brake abrasion while maintaining position stability on slopes
Solution Approach 2:
The mechanical brake system is replaced by an electromagnetic torque generation system for the holding function. The motor's electromagnetic torque substitutes the mechanical friction force, achieving the same vehicle holding effect without mechanical contact and abrasion
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 electric vehicle to start and stop on sloped roads without rolling backward and minimizes mechanical brake wear, reducing maintenance costs and improving operational efficiency.
Implementation Method 1
the motor controller applies DC voltage or AC voltage in a frequency range of −1 Hz to +1 Hz to the stator of the induction motor to make the induction motor generate torque
Data Source
AI summary
An electric drive vehicle having an induction motor for braking or driving wheels, a motor controller for controlling the induction motor, and mechanical brakes for braking the wheels, wherein while the vehicle is in halt in a state that the mechanical breaks are not operating, the motor controller applies DC voltage or AC voltage in a frequency range of −1 Hz to +1 Hz to the stator of the induction motor to make the induction motor generate torque for stopping the vehicle and maintain the vehicle in a halt state.