Magnetic Flux Error Correction for Motor Drive Positioning
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Solution Overview
Problem
In motor drive apparatus with high density mounting, magnetic flux generated by main circuit wiring near magnetic sensors causes disturbance, leading to inaccurate rotor position detection and unstable motor control, especially when one inverter fails.
Innovation Solution
A motor drive apparatus with a controller that includes a magnetic flux error correction unit to calculate and correct the magnetic flux component generated by the main circuit wiring, allowing for accurate rotor position detection and stable motor control, even with a single three-phase bridge circuit operating.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If main circuit wiring is disposed near magnetic sensor to achieve high density mounting, then productivity is improved, but measurement precision deteriorates due to magnetic flux disturbance
Solution Approach 1:
The patent introduces a magnetic flux error correction unit as an intermediary computational element that processes the magnetic sensor output. This unit calculates the disturbance magnetic flux generated by main circuit wiring and subtracts it from the raw sensor signal, thereby eliminating the harmful magnetic interference while maintaining the high-density mounting configuration.
Solution Approach 2:
The patent changes the parameter processing approach by transforming the raw magnetic sensor signal through mathematical correction. The magnetic flux error correction unit applies parameter transformation by calculating the difference between the detected magnetic flux and the estimated disturbance flux, thereby converting an inaccurate measurement into an accurate rotor position signal.
2Device complexity
If main circuit wiring is disposed near magnetic sensor, then device complexity is reduced, but reliability deteriorates due to magnetic flux disturbance affecting position detection
Solution Approach 1:
The magnetic flux error correction unit serves as a computational intermediary that isolates the control system from magnetic interference. By introducing this correction layer, the system maintains simple physical wiring layout while ensuring reliable motor control through software-based disturbance compensation.
Solution Approach 2:
The patent implements a feedback mechanism where the magnetic flux error correction unit continuously monitors the magnetic sensor output, calculates the disturbance component, and applies real-time correction. This closed-loop feedback approach ensures reliable motor control by dynamically compensating for magnetic flux disturbances caused by main circuit wiring.
3Measurement precision
If magnetic flux error correction is implemented, then measurement precision is improved, but device complexity increases due to additional correction unit
Solution Approach 1:
The magnetic flux error correction unit is designed with multi-functionality, serving both as a disturbance compensator and as part of the overall control algorithm. By integrating this correction function into the existing controller architecture, the patent achieves high measurement precision without proportionally increasing device complexity, as the correction unit shares computational resources with other control functions.
4Reliability
If magnetic flux error correction is implemented, then reliability is improved, but device complexity increases due to additional correction unit
Solution Approach 1:
The magnetic flux error correction unit is designed to perform multiple functions: it compensates for magnetic disturbance, processes sensor signals, and integrates with the existing control algorithm. This multi-functionality allows the system to achieve improved reliability through disturbance compensation without proportionally increasing device complexity, as the correction unit leverages existing computational infrastructure.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution reduces the influence of disturbance magnetic flux on position detection, enabling high accuracy rotor position sensing and stable motor control, facilitating continuous operation even if one three-phase bridge circuit fails.
Implementation Method 1
a magnetic sensor that detects a magnetic flux change of a sensor magnet attached to a rotor of the motor
Implementation Method 2
magnetic flux generated by main circuit wiring near magnetic sensors causes disturbance
Data Source
AI summary
Magnetic flux generated when a current flows through a main circuit wiring serves as disturbance of a magnetic sensor, and accurate rotor position information is obtained. A motor drive apparatus controls an operation of a power conversion device outputting a current to an AC motor on the basis of a desired torque command value, and includes a main circuit wiring that is electrically connected to a switching element forming the power conversion device, and through which a DC current or an AC current is transmitted thereto, a magnetic sensor that detects a magnetic flux change of a sensor magnet attached to a rotor of the AC motor, and a controller that calculates a current command value which is output from the power conversion device to the motor on the basis of position information of the rotor detected by the magnetic sensor, in which the controller includes a magnetic flux error correction unit that detects or calculates a magnetic flux component generated by a current flowing through the main circuit wiring.