Electric Vehicle Torque Control for Overvoltage Prevention
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing electric vehicle control technologies do not effectively prevent overvoltage when torque is rapidly limited during slipping, leading to inefficient power management and potential voltage imbalances.
Innovation Solution
A control apparatus and method for electric vehicles that includes a road surface condition detection system, slip determination, torque reduction, and voltage control, using a boost converter and converter control to reduce voltage input and torque gradually when slipping is detected, and increasing power generation or auxiliary machine load to maintain power balance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the torque output to the drive shaft is rapidly limited when the vehicle slips, then the vehicle slip is corrected quickly, but an overvoltage occurs due to sharp reduction in electric power consumption
Solution Approach 1:
The control device predicts the occurrence of overvoltage based on the rate of torque reduction and takes preliminary action by controlling the boost converter to prevent overvoltage before it occurs. This resolves the contradiction by anticipating the harmful effect (overvoltage) caused by rapid torque limitation and counteracting it in advance.
Solution Approach 2:
The control device calculates the rate of change of torque output and uses this feedback to dynamically adjust the boost converter control. When the torque reduction rate exceeds a threshold, the system responds by adjusting the boost converter to maintain voltage stability, thus preventing overvoltage while allowing effective slip correction.
2Reliability
If the torque of the motor is limited to reduce vehicle slip, then the drive force is reduced to prevent slipping, but the electric power consumption is sharply reduced causing voltage increase
Solution Approach 1:
The boost converter acts as an intermediary between the battery and the motor drive device. It mediates the power flow by adjusting its conversion ratio based on the torque reduction rate, thereby stabilizing the voltage despite changes in motor power consumption caused by torque limitation for slip prevention.
3Speed
If the torque reduction rate is increased to quickly stop vehicle slip, then the slip correction speed is improved, but the voltage stability deteriorates due to rapid power consumption change
Solution Approach 1:
The control system dynamically adjusts the boost converter operation based on the real-time torque reduction rate. When high-speed slip correction is needed with rapid torque reduction, the system activates overvoltage prevention control. When slip correction is gradual, normal operation continues, allowing the system to adapt its behavior to maintain voltage stability across different correction speeds.
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 prevents excessive voltage input to the drive device, maintains power balance, and reduces the risk of overvoltage by gradually reducing torque and adjusting voltage and power generation in response to slipping conditions.
Implementation Method 1
a boost converter that boosts a voltage output from a battery
Data Source
AI summary
A control apparatus for an electric vehicle includes a road surface condition detection portion, a slip determination portion, a torque reduction device, and a voltage control device. The electric vehicle includes a motor that generates drive power for the electric vehicle, and a drive device that drives the motor. The road surface condition detection portion detects the condition of a road surface on which the electric vehicle is driven. The slip determination portion determines whether the electric vehicle is slipping. The torque reduction device reduces the torque of the motor when the slip determination portion determines that the electric vehicle is slipping. The voltage control device controls a voltage input to the drive device to reduce the voltage when the road surface condition detection portion determines that the road surface has a friction coefficient lower than a predetermined value.