Motor Control Device Rotor Angle Correction via Current Detection
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Solution Overview
Problem
Existing motor control systems for permanent-magnet synchronous motors face challenges in accurately correcting rotor angle detection due to fitting errors and temporal changes, which can lead to unintended torque generation and reduced efficiency, especially in high-torque motors with multiple pole pairs.
Innovation Solution
A motor control device that includes an angle detector, current detector, and angle corrector, which uses the detected current to correct the rotor angle without additional hardware, thereby simplifying configuration and processing, and an abnormality discriminator to detect abnormalities in angle detection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If back electromotive voltage measurement method is used to correct detected angle, then angle detection accuracy is improved, but device complexity increases due to additional hardware requirements
Solution Approach 1:
The patent extracts the angle correction function from separate hardware measurement systems and integrates it into the existing current detection system. By utilizing the already-present current detector to measure DC power source current, the system achieves angle correction without requiring additional back electromotive voltage measurement hardware, thus resolving the contradiction between measurement precision and device complexity
Solution Approach 2:
The current detector is given a dual function: it continues to perform its original role of monitoring armature current while simultaneously measuring the DC power source current to derive angle correction information. This multi-functionality eliminates the need for separate angle measurement hardware while maintaining correction accuracy
2Device complexity
If vector control with specified voltage values is used for angle correction, then hardware complexity is reduced, but measurement precision deteriorates due to motor parameter errors
Solution Approach 1:
The patent implements a feedback mechanism where the actual DC power source current is measured and compared against the theoretical current value calculated from motor parameters. The difference between measured and calculated current provides feedback information used to determine the angle correction amount, thereby compensating for motor parameter errors and improving measurement precision while maintaining simple hardware configuration
Solution Approach 2:
The patent replaces the traditional mechanical approach of relying on calculated voltage values based on motor parameters with an electrical measurement approach using actual current sensing. By substituting voltage-based calculation with current-based measurement, the system achieves higher precision angle correction without increasing hardware complexity
3Measurement precision
If input electric power multiplication processing is used for angle correction, then angle correction can be achieved, but processing complexity increases and loss map requirements add device complexity
Solution Approach 1:
The patent replaces the expensive and complex loss map data structure with a simpler, more direct current measurement approach. By using the readily available DC power source current signal directly for angle correction calculations, the system eliminates the need for pre-stored loss maps and complex multiplication processing, thereby reducing processing complexity while maintaining angle correction capability
Data Source
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AI summary
A motor control device that controls the driving of a motor having a permanent magnet provided at a rotor has: an angle detector that detects the angle of the rotor by use of an angle sensor; a current detector that detects, as a detected current, the outflow current from or inflow current to a direct-current power source serving as the source for driving the motor; and an angle corrector that corrects the detected angle based on the detected current. The driving of the motor is controlled by use of a corrected angle obtained through the correction by the angle corrector.