Motor Exciting Device for Accurate Magnetic Pole Position Determination
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Solution Overview
Problem
In permanent magnet synchronous motors with a large reluctance torque proportion, the existing methods for determining the magnetic pole position are ineffective due to multiple stable stopping points, making it difficult to accurately determine the magnetic pole position.
Innovation Solution
A motor exciting device and method that sums the reluctance torques generated by the windings of multiple axes to zero, ensuring only one stable stopping point, allowing for accurate calculation of the magnetic pole position based on this point, and controlling the motor like a general PMSM by detecting and correcting the stable stopping point.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the known DC excitation method is applied to motors with large reluctance torque proportion, then the motor can be excited, but multiple stable stopping points occur making magnetic pole position determination impossible
Solution Approach 1:
The patent changes the excitation parameters by applying DC currents with specific phase relationships across multiple winding sets. By controlling the phase angles and current magnitudes of the excitation currents, the patent creates a unique stable stopping point that allows accurate magnetic pole position determination even in motors with large reluctance torque proportion.
Solution Approach 2:
The patent divides the motor windings into multiple independent sets (first-axis, second-axis, etc.) and applies DC excitation to each set separately with controlled phase relationships. This segmentation allows precise control over the torque characteristics and enables the creation of a unique stable stopping point by managing the contribution of reluctance torque from each winding set.
2Ease of operation
If multiple stable stopping points occur, then the motor can stop at various positions, but the magnetic pole position cannot be accurately determined
Solution Approach 1:
The patent employs feedback by detecting the actual stopping position of the motor and comparing it with the expected position based on the applied DC excitation. This feedback mechanism allows the system to identify the unique stable stopping point and accurately determine the magnetic pole position, eliminating the ambiguity caused by multiple possible stopping points.
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
This approach allows for precise determination of the magnetic pole position with high accuracy and stability, even in motors with a large reluctance torque proportion, by ensuring a single stable stopping point and minimizing vibratory torques.
Implementation Method 1
a first-axis winding set, a second-axis winding set, and Nth-axis winding set (N≥2) of the motor are excited by DC currents which are shifted in phase from one another by π/N each and which have equal magnetomotive forces, so that the sum of reluctance torques generated by the windings of the respective axes becomes zero
Implementation Method 2
DC currents which are shifted in phase from one another by π/N each and which have equal magnetomotive forces
Data Source
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AI summary
A motor control device which can determine a magnetic pole position for a magnetic pole position detector included in a permanent magnet motor (11) in which the reluctance torque proportion is larger than the magnet torque proportion is provided. In a permanent magnet synchronous motor (11) having multi-phase windings (111, 112,..., 11K) of N axes (N ≥ 2), the windings of optionally selected K axes (K ≤ N) are DC excited using corresponding independent power supplies. Namely, to determine the magnetic pole position of the motor (11), the first-axis windings (111) are DC excited by a first-axis exciting device (211); the second-axis windings (112) are DC excited by a second-axis exciting device (212) so as to generate a magnetomotive force equal in magnitude to and shifted in electrical phase by π/N from the magnetomotive force generated by the first-axis windings (111); - - -; and the Kth-axis windings (11K) are DC excited by a Kth-axis exciting device (21K) so as to generate a magnetomotive force equal in magnitude to and shifted in electrical phase by (K - 1)π/K from the magnetomotive force generated by the first-axis windings (111).