EV Motion Control Using Energy-Loss Torque and Speed Profiles
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Solution Overview
Problem
Electric vehicles (EVs) face inefficiencies in energy usage due to losses in electric motor operations, particularly when using continuously variable transmissions (CVT), which impact the overall energy efficiency and range of EVs.
Innovation Solution
A method and system utilizing an energy-loss function, derived from efficiency maps of electric motors, to optimize torque and rotational speed, incorporating pseudo-convex loss functions and gradient-descent methods to minimize energy dissipation, and a Kalman filter for probabilistic control, to determine optimal velocity and torque profiles for efficient EV motion control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a continuously variable transmission (CVT) is used to convert power from electric motors to drive wheels, then the EV can operate across a wider speed range, but energy efficiency decreases due to transmission losses during gear conversion
Solution Approach 1:
The patent extracts the CVT transmission component from the powertrain system to analyze its energy loss characteristics separately. By isolating the transmission's impact on efficiency, the system can optimize motor control strategies to compensate for transmission losses and minimize overall energy waste while maintaining the speed adaptability benefits of the CVT.
2Adaptability or versatility
If multiple electric motors with different power levels are used to meet varying torque demands, then the EV can handle different loading conditions, but energy efficiency varies significantly between motors
Solution Approach 1:
The patent merges the control strategies of multiple electric motors with different power levels into a unified energy-efficient control framework. By coordinating the operation of high-power and low-power motors based on real-time torque demands and efficiency maps, the system optimizes the combination of motor outputs to minimize total energy loss while maintaining the ability to handle varying torque requirements.
3Ease of operation
If the CVT changes gear seamlessly regardless of EV speed, then the transmission can adapt to any driving condition, but the efficiency of electric motors is reduced due to energy loss during conversion
Solution Approach 1:
The patent implements a feedback-based control system that continuously monitors the efficiency of electric motors and adjusts CVT gear ratio changes accordingly. By using real-time efficiency data from motor maps and actual operating conditions, the system optimizes the timing and magnitude of gear transitions to minimize energy loss during conversion while maintaining seamless adaptability to different driving conditions.
Data Source
AI summary
Embodiments of the present disclosure disclose a method and a system for controlling a motion of an electric vehicle (EV). The method includes determining a velocity profile moving the EV from an initial velocity over a period of time by minimizing the energy dissipation according to an energy-loss function. The energy-loss function maps values of acceleration and velocity of the EV to energy dissipation of the EV resulting from controlling one or multiple electric motors of the EV to move the EV at corresponding acceleration and velocity values. The velocity profile is a function of time. The method further includes controlling the one or multiple electric motors of the EV to generate a torque for moving the EV according to the velocity profile.