Synchronous Motor Magnetic Pole Position Detection
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Solution Overview
Problem
The existing direct-current excitation method for detecting the magnetic pole initial position in synchronous motors is time-consuming, especially for high-performance motors with low friction, requiring several minutes to acquire the initial position.
Innovation Solution
A magnetic pole initial position detection device that generates a constant excitation current with a fixed phase, determines when the torque generated is zero, and acquires the initial position based on the rotor's actual position at this point, reducing the time required for detection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the direct-current excitation method is used to detect the magnetic pole initial position, then the magnetic pole initial position can be detected, but the detection time is very long (several minutes for high-performance motors)
Solution Approach 1:
The patent applies periodic action by alternating the excitation current direction between positive and negative. The system detects torque signs during each excitation phase and uses this periodic alternation to determine the magnetic pole initial position more quickly, reducing detection time from several minutes to a much shorter duration while maintaining detection accuracy.
2Speed
If the synchronous motor has high acceleration performance with very little friction, then the motor performance is improved, but the magnetic pole initial position detection time becomes even longer
Solution Approach 1:
The patent uses feedback by continuously monitoring the torque sign during excitation and using this information to determine when the rotor has reached the magnetic pole initial position. The control unit adjusts the excitation current based on the detected torque feedback, enabling faster and more accurate position detection that works effectively even for high-performance motors with minimal friction.
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 significantly shortens the time to acquire the magnetic pole initial position, enabling faster motor initialization and control.
Implementation Method 1
an energizing unit configured to apply an excitation current to a drive coil to generate a rotating magnetic field in a stator; a rotor including a permanent magnet rotated by the rotating magnetic field
Implementation Method 2
a constant excitation current with a fixed current phase is continuously applied to the synchronous motor
Data Source
AI summary
A magnetic pole initial position detection device includes: a direct-current excitation command generation section configured to generate a first command for causing a constant excitation current with a current phase fixed to a first phase to flow through the synchronous motor; a torque-zero determination section configured to determine whether a torque generated in the rotor of the synchronous motor is zero when the excitation current based on the first command flows through the synchronous motor; and a magnetic pole initial position acquisition section configured to acquire the magnetic pole initial position of the rotor of the synchronous motor on a basis of a rotor actual position at or near a point in time when the torque-zero determination section determines that the torque is zero; a number of pole pairs of the synchronous motor; and an excitation phase during direct-current excitation under the first command.