Electric Vehicle Motor Control Using Speed-Based Operating Point Correction
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Solution Overview
Problem
Existing motor control methods for electric vehicles, such as MTPA control, fail to accurately represent motor nonlinearity, leading to distorted output results and increased system complexity, which results in higher fuel consumption and manufacturing costs due to incorrect measuring factors.
Innovation Solution
A control method that calculates a motor voltage using detected motor current and generates an operating point correcting function based on motor speed, allowing for optimal current command calculation and minimizing necessary measuring factors, thereby simplifying the motor control system and reducing fuel consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a motor control method uses multiple measuring factors (motor torque, motor current, motor voltage, power factor, DC voltage, DC current) to calculate operating points, then the control accuracy may improve, but the system complexity and manufacturing cost increase
Solution Approach 1:
The patent extracts and eliminates unnecessary measuring factors from the control system. Instead of using multiple measuring factors (motor torque, motor current, motor voltage, power factor, DC voltage, DC current), the invention reduces the system to use only motor current and motor speed, which are readily available from the motor controller, thereby simplifying the system while maintaining control accuracy
Solution Approach 2:
The patent makes the motor controller perform multiple functions: it not only controls the motor but also serves as the measuring system by directly providing motor current and speed data. This eliminates the need for separate complex measuring systems while maintaining the necessary measurement capabilities for accurate control
2Measurement precision
If a motor control method uses multiple measuring factors to calculate operating points, then the control precision may improve, but the fuel consumption increases due to system inefficiency
Solution Approach 1:
The patent removes unnecessary measuring components and processing steps that consume energy. By using only motor current and speed from the existing motor controller, the system eliminates energy-wasting operations associated with multiple measuring factors and complex calculations, thereby reducing overall system energy consumption and improving fuel efficiency
Solution Approach 2:
The motor controller serves itself by providing the necessary measurement data (motor current and speed) that it already possesses during normal operation. This self-service approach eliminates the need for additional energy-consuming measurement systems and processing, allowing the system to maintain precise control while minimizing energy consumption
3Ease of manufacture
If mathematical modeling is used for MTPA control, then the control method can be implemented, but the nonlinearity of the motor cannot be accurately represented
Solution Approach 1:
The patent replaces complex mathematical models with simple lookup tables containing pre-calculated optimal current values. These tables are generated offline and stored in the controller memory, providing accurate motor control without requiring complex real-time mathematical computations. This approach sacrifices the theoretical elegance of mathematical modeling for practical accuracy and ease of implementation
Solution Approach 2:
The patent changes the control approach from continuous mathematical modeling to discrete lookup table-based control. By pre-calculating optimal operating points and storing them in tables indexed by motor speed and torque, the system achieves accurate representation of motor nonlinearity while maintaining simple and efficient real-time control implementation
Data Source
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AI summary
A system for controlling an electric vehicle and method thereof are provided. The control method of electric vehicle includes operating a battery and a motor, detecting a torque command, a motor speed, and a motor current, calculating a motor voltage from the motor current, and determining when voltage utilization ,based on a speed range of the motor, is greater than a predetermined value. Further, the method includes generating an operating point correcting function, based on the motor speed, when the voltage utilization is less than the predetermined value and calculating a current command, according to the motor speed, from the operating point correcting function. Furthermore, the method also includes outputting the calculated current command.