Motor Control Stabilizing Rotation Frequency via Electrical Angle Estimation
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Solution Overview
Problem
Existing motor control methods experience instability in rotation frequency due to variations in position detection sensor mounting, particularly at high rotation frequencies, leading to uneven operation currents in three-phase motors.
Innovation Solution
A motor control method that estimates the electrical angle at predetermined positions and updates this estimate based on time elapsed and rotor rotation frequency, computing the voltage vector to stabilize frequency and reduce detection errors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If position detection sensor is used to detect rotor position at high rotation frequency, then rotor position detection is achieved, but rotation frequency becomes unstable due to detection errors
Solution Approach 1:
The patent introduces an intermediary estimation mechanism that uses voltage vectors and current detection as mediators to indirectly determine rotor position. Instead of directly relying on the position detection sensor which causes instability at high speeds, the system uses the relationship between applied voltage vectors and resulting currents to estimate the electrical angle, thereby stabilizing rotation frequency while maintaining accurate position control
Solution Approach 2:
The patent replaces the mechanical position detection sensor system with an electrical estimation system. By substituting the direct mechanical/electrical position sensing with an electrical angle estimation based on voltage-current relationships, the system eliminates the detection errors inherent in sensor-based approaches at high rotation frequencies
2Ease of manufacture
If position detection sensor mounting variation occurs, then sensor installation is simplified, but detection accuracy deteriorates causing uneven operation currents
Solution Approach 1:
The patent uses voltage vectors and current detection as intermediary measurements to indirectly determine rotor position. This intermediary approach eliminates the need for precise sensor mounting since the electrical angle is estimated through the electrical characteristics (voltage-current relationships) rather than direct mechanical position sensing, thereby maintaining detection accuracy regardless of mounting variations
Solution Approach 2:
The patent extracts the position detection function from the mechanical sensor domain and relocates it to the electrical domain. By taking out the position detection dependency from the physical sensor mounting and implementing it through electrical angle estimation based on voltage and current measurements, the system achieves position detection accuracy independent of mechanical mounting precision
3Productivity
If voltage vector is updated frequently based on position detection, then control responsiveness is improved, but detection errors are amplified at high rotation frequencies
Solution Approach 1:
The patent uses electrical angle estimation as an intermediary control mechanism that provides smooth, continuous updates without the discrete detection errors of sensor-based systems. By estimating the electrical angle through voltage-current relationships rather than relying on periodic sensor detections, the system maintains high control responsiveness while avoiding the amplification of detection errors that occurs with frequent sensor-based updates at high rotation frequencies
Data Source
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AI summary
A motor control device capable of stabilizing a rotation frequency. Triggered by a position detection sensor detecting that a rotor (3b) is positioned at any one of K predetermined electrical angles, for example, 60°, 180°, and 300°, a voltage vector to be given to a motor (3) is updated. When, for example, the rotation frequency is equal to or higher than a specified value, the predetermined electrical angles is changed into M, for example, into one angle of 60°.