Electric Traction Motor Torque Estimation via Acceleration Rates
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Solution Overview
Problem
There is a need for a diagnostic method to estimate the power output performance of an electric traction motor in electric vehicles, as existing methods used in combustion engine vehicles are not applicable.
Innovation Solution
A system and method that involves a vehicle with an electric motor, a power source, sensors to detect motor speed, and controllers to calculate torque output by observing acceleration and deceleration rates, determining loss torque, and calculating actual torque output based on observed torque and loss torque.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a stall test is performed to estimate power output in combustion engine vehicles, then the power output can be diagnosed, but this method is not applicable to electric vehicles with traction motors
Solution Approach 1:
The patent changes the diagnostic parameters from combustion engine-specific measurements (engine speed during stall) to electric motor-specific measurements (acceleration rate and deceleration rate). By measuring the acceleration rate during motor operation and the deceleration rate during coasting, the system adapts the diagnostic approach to electric vehicles while maintaining diagnostic accuracy for power output assessment.
Solution Approach 2:
Instead of measuring power output directly during active motor operation (as in combustion engine stall tests), the patent inverts the approach by measuring the deceleration rate during coasting when the motor is not actively driving. This inverted measurement during deceleration provides information about motor performance and losses that can be used to diagnose power output capability.
2Measurement precision
If torque is observed based on acceleration rate and loss torque is determined based on deceleration rate, then actual torque output can be calculated, but multiple measurements and calculations are required
Solution Approach 1:
The diagnostic system uses the vehicle's own operational characteristics (acceleration and deceleration behavior) to perform self-diagnosis. By measuring how the vehicle accelerates under motor power and how it decelerates during coasting, the system extracts torque information without requiring external testing equipment or complex diagnostic tools, enabling the vehicle to assess its own motor performance.
Solution Approach 2:
The system uses feedback from speed sensors to continuously monitor motor speed during acceleration and deceleration phases. This speed feedback is processed to calculate acceleration rate and deceleration rate, which are then used to determine torque output and loss torque. The feedback loop enables real-time calculation of actual torque output based on observed vehicle behavior.
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 accurate diagnosis of motor performance by determining torque output within specified tolerance ranges, ensuring the motor operates within design specifications.
Implementation Method 1
a sensor configured to detect a speed of the electric motor
Implementation Method 2
determine a loss torque of the motor based on a deceleration rate of the motor
Implementation Method 3
determine a torque output of the motor based on an acceleration rate of the motor and the loss torque of the motor
Data Source
AI summary
A vehicle is provided having an electric motor and a controller configured to control the electric motor. The controller may calculate the torque output of the motor based on the acceleration and deceleration rates of the motor. Moments of inertia for components rotationally coupled to the motor may be employed in the torque calculation.