Creep Torque Control for Electric Vehicle Roll-Back Prevention
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Solution Overview
Problem
Electric vehicles face challenges in preventing rolling back on upward slopes due to the lack of idle torque, leading to inefficient creep control methods that often result in frequent backward movement or sudden acceleration, with limited sensitivity and no effective countermeasure for sensor malfunctions.
Innovation Solution
A system and method that calculates real-time road gradient using a G-sensor and vehicle acceleration to determine maximum creep torque, adjusting torque output based on vehicle speed and acceleration, and includes a fault detection mechanism to prevent excessive creep torque generation when the G-sensor fails.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If creep control is implemented in electric vehicles by increasing motor torque on upward slopes, then rolling-back is prevented, but the vehicle frequently moves back or suddenly rushes forward due to insufficient sensitivity and lack of sensor malfunction countermeasures
Solution Approach 1:
The controller pre-calculates the maximum creep torque required to prevent rolling-back by considering the gradient of the road and vehicle information before the vehicle actually rolls back. This preliminary determination of torque requirements allows the system to apply appropriate creep torque in advance, preventing the vehicle from moving backward or rushing forward suddenly.
Solution Approach 2:
The system determines a maximum creep torque value that acts as a cushion or limit to prevent excessive torque application. By establishing this predetermined torque ceiling based on road gradient and vehicle conditions, the system avoids sudden rushes forward while still preventing rolling-back, thus cushioning against unstable vehicle behavior.
2Ease of operation
If creep torque control is activated when brake pedal is released, then normal driving state is achieved, but the system lacks sensitivity to detect upward slope conditions
Solution Approach 1:
The controller pre-calculates the maximum creep torque required to prevent rolling-back by considering the gradient of the road and vehicle information before the vehicle actually rolls back. This preliminary determination of torque requirements allows the system to activate creep control in advance when transitioning from brake to acceleration, improving sensitivity to upward slope conditions.
Data Source
AI summary
The present invention provides a technique for controlling creep torque to prevent a vehicle from rolling backward on an upward slope. In particular, a gradient of a road is calculated in real time from a detection value of a sensor and vehicle acceleration. A maximum creep torque for preventing roll-back caused by gravity according to the gradient is calculated using the gradient and vehicle information. A first creep torque reference is calculated based on the maximum creep torque and the vehicle speed. A second creep torque reference is calculated based on the maximum creep torque and the vehicle acceleration. A torque command value according to an operation state of a brake is calculated based on the first creep torque reference value and the second creep torque reference value and the gradient. In response, a torque output of a driving motor is controlled according to the calculated torque command value.