Vehicle Motor Torque Modulation for Low-Load Efficiency
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Solution Overview
Problem
Electric motor control systems in electric and hybrid vehicles face inefficiencies at low torque conditions, which affect vehicle range and fuel economy, as existing methodologies fail to optimize motor efficiency under these conditions.
Innovation Solution
A method and system for dynamically modulating drive signals between a higher and lower torque value to increase motor efficiency, where the modulation is based on vehicle speed and torque command thresholds, using pulse width modulation to maintain average torque within a selected range, thereby enhancing efficiency without affecting driving speed or smoothness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the electric motor operates at low commanded torque conditions, then the vehicle can maintain smooth operation and meet low load requirements, but the motor efficiency deteriorates significantly
Solution Approach 1:
The patent applies periodic action by modulating the drive signal frequency to vary the motor torque periodically between a higher torque value and a lower torque value. This periodic modulation allows the motor to operate in higher efficiency regions more frequently, improving overall energy efficiency while maintaining smooth vehicle operation through careful control of the modulation frequency and amplitude.
Solution Approach 2:
The patent implements dynamics by dynamically adjusting the drive signal frequency based on operating conditions. The controller monitors motor efficiency conditions and adaptively modulates the torque output, transitioning from static torque control to dynamic torque modulation. This allows the system to optimize efficiency in real-time while responding to changing vehicle load requirements.
2Loss of energy
If the drive signal frequency is increased to improve motor efficiency, then the motor operates in higher efficiency regions, but the complexity of the control system increases
Solution Approach 1:
The patent applies parameter changes by modifying the drive signal frequency as a control parameter to optimize motor efficiency. Instead of changing the physical structure or adding complex hardware, the system achieves efficiency improvements through software-based frequency modulation of the existing drive signal, keeping the control system relatively simple while effectively reducing drive system losses.
3Loss of energy
If torque modulation is applied to increase efficiency, then energy loss is reduced, but the precision of torque control deteriorates
Solution Approach 1:
The patent implements feedback by continuously monitoring motor efficiency conditions and using this information to adjust the torque modulation strategy. The controller measures actual motor performance and adapts the modulation parameters accordingly, ensuring that torque control precision is maintained while achieving efficiency improvements. This closed-loop approach allows the system to compensate for any torque ripple introduced by modulation.
Data Source
AI summary
A method of controlling an electric motor of a vehicle includes monitoring torque command signals from a vehicle system to the electric motor, each torque command signal configured to cause the electric motor to output a commanded torque, and monitoring a speed of the vehicle and an output torque of the electric motor, the output torque responsive to a drive signal generated based on the torque command signals. The method also includes, based on the output torque and the vehicle speed indicating a low motor efficiency condition, modulating the drive signal between a first torque value and a second torque value that is less than the first torque value, the first torque value greater than the commanded torque and selected to increase an efficiency of the electric motor.