Vehicle Motor Control Using Battery Voltage Feedback
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Solution Overview
Problem
Existing motor control systems for electric vehicles, particularly those using high-voltage batteries, struggle with accurately reflecting battery voltage fluctuations, leading to deviations in motor torque and reduced controllability, which affects fuel efficiency evaluations.
Innovation Solution
A system that includes a magnetic flux estimation module to determine reverse magnetic flux based on motor speed and voltage, a torque instruction generation module to generate torque instructions based on this flux and motor torque, and an inverter to control the motor, ensuring accurate motor control even with changing battery voltage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If torque instruction is generated based on motor speed, then motor control convenience is improved, but motor controllability deteriorates due to unreflected battery voltage fluctuations
Solution Approach 1:
The patent changes the control parameter from torque instruction (which does not reflect voltage fluctuations) to current instruction (which directly responds to voltage changes). By generating current instruction based on both motor speed and battery voltage, the system adapts to voltage fluctuations while maintaining control accuracy, thus improving motor controllability without sacrificing convenience
Solution Approach 2:
The patent introduces battery voltage as a feedback parameter in the control system. The current instruction is generated by considering both motor speed and battery voltage, creating a closed-loop control mechanism that continuously adjusts to voltage fluctuations. This feedback mechanism ensures that motor controllability is maintained even as battery voltage changes during operation
2Power
If battery voltage increases to 800 V level, then power output is improved, but voltage fluctuation increases causing torque deviation
Solution Approach 1:
The patent addresses the torque deviation caused by high-voltage fluctuations by changing the control approach from torque-based to current-based control. The current instruction generation module uses both motor speed and battery voltage as inputs, allowing the system to compensate for voltage-induced torque deviations. This parameter change enables accurate motor control at 800 V battery levels while maintaining torque accuracy
Solution Approach 2:
The system implements voltage feedback by continuously monitoring battery voltage and using it to adjust the current instruction. This feedback mechanism allows the control system to respond to voltage fluctuations in real-time, compensating for their effect on motor torque and maintaining accurate torque control despite high-voltage operation
3Productivity
If zero torque control is performed in coast down mode, then fuel efficiency measurement is enabled, but measurement reliability deteriorates due to inaccurate zero torque output
Solution Approach 1:
The patent improves zero torque control accuracy by changing from torque instruction to current instruction generation. The current instruction is calculated based on motor speed and battery voltage, ensuring that the motor truly outputs zero torque during coast down mode measurements. This parameter change eliminates torque deviations that would otherwise contaminate the traveling resistance measurement, thereby improving measurement precision
Solution Approach 2:
The system uses battery voltage feedback to ensure accurate zero torque output during coast down mode. By continuously adjusting the current instruction based on voltage fluctuations, the system maintains precise zero torque control, enabling reliable measurement of traveling resistance and accurate fuel efficiency evaluation without torque measurement errors
Data Source
AI summary
The present disclosure relates to a system for controlling a motor of a vehicle for increasing control accuracy of the motor for driving the vehicle, and an object of the present disclosure is to provide a system for controlling a motor of a vehicle, which may accurately perform a motor control even when a battery voltage (i.e., motor voltage) applied to the motor upon the driving control of the motor is changed.