Synchronous Motor Control System for Magnetic Pole Position Correction
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional control systems for synchronous electric motors face challenges in accurately determining the magnetic pole position, leading to reduced torque generation due to friction and errors in detection, which affects both forward and reverse rotations.
Innovation Solution
A control system that includes a position detecting section, torque command generating section, current command generating section, and current feedback section, along with acceleration computing, added torque generating, initial correction, and regular correction sections, to accurately shift the current phase to where maximum torque can be generated, overcoming friction and ensuring precise detection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If torque is detected while changing the phase angle to determine magnetic pole position, then the magnetic pole position can be detected without rotating the rotor, but the rotor stops when torque becomes smaller than friction torque, causing detection error
Solution Approach 1:
The system applies preliminary action by adding a predetermined correction value to the basic correction value before final determination. This preliminary correction anticipates the friction torque effect and compensates for it in advance, allowing the rotor to overcome friction and reach the correct magnetic pole position without stopping prematurely
Solution Approach 2:
The system changes parameters by introducing a correction value that is added to the basic correction value. This parameter change allows the system to adjust for friction torque effects dynamically, ensuring accurate magnetic pole position detection even when torque is small
2Stability of the object's composition
If the rotor is greatly moved to the mechanically stable point for initial operation, then the rotor can be brought to a standstill at a stable point, but the rotor has to be moved greatly which is inefficient
Solution Approach 1:
The system replaces the mechanical approach of physically moving the rotor to a stable point with an electrical control approach. By using phase angle adjustment and correction value addition, the system achieves rotor positioning without requiring great mechanical movement, significantly reducing initial operation time
3Device complexity
If magnetic pole position detection is performed without correction, then the detection process is simple, but the phase of current deviates from maximum torque phase, reducing motor torque
Solution Approach 1:
The system performs preliminary action by calculating and adding a correction value to the basic correction value before final current phase determination. This preliminary correction ensures that the current phase aligns with the maximum torque phase, maximizing motor power output while maintaining relatively simple detection system complexity
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 system effectively corrects the phase of the current to achieve high-accuracy maximum torque generation, reducing the impact of friction and ensuring consistent torque output in both directions.
Implementation Method 1
a rotational magnetic field formed by a stator
Implementation Method 2
a stator having a plurality of stator magnetic poles each polarized when a current is flown through armature winding
Data Source
AI summary
A control system for a synchronous electric motor controls the synchronous motor so that the phase of a current determined based on a magnetic pole position of a moving element of the motor may shift to a phase where maximum torque may be obtained. A magnetic pole position correcting section determines a magnetic pole position correction to be added to a relative magnetic pole position. In connection with a polarity change determining section which determines whether or not a polarity of an acceleration difference changes, a basic correction adjusting section switches computation between an incremental operation of incrementing a basic correction and a decremental operation of decrementing the basic correction by a correction increment/decrement. When the correction increment/decrement becomes a predetermined lower limit value B or less, the basic correction adjusting section stops the computation. The basic correction at that point is determined as a finally-determined magnetic pole position correction.