Electric Motor Control Switching for Stable Open- to Closed-Loop Transition
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Solution Overview
Problem
Existing motor control systems face issues with operation stability and start-up reliability due to large angle differences between open-loop and calculated position angles, leading to motor speed vibrations and instability during transitions from open-loop to closed-loop operation.
Innovation Solution
A method and system that control a motor by switching from open-loop to closed-loop operation based on angle and current thresholds, using determination modules to manage rotational speed, angle differences, and open-loop current adjustments to stabilize motor operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the motor is controlled to switch from open-loop to closed-loop operation, then the control precision is improved, but the operation stability deteriorates due to large angle differences causing motor speed vibrations
Solution Approach 1:
The patent applies preliminary action by checking whether the open-loop current is less than or equal to a minimum current value before switching to closed-loop control. This preliminary check ensures that the motor is in a suitable state for transition, preventing speed vibrations and instability that would occur with large angle differences. The current threshold verification is performed in advance to guarantee stable operation during the control mode transition.
2Stability of the object's composition
If the open-loop current is reduced to prevent angle difference issues, then the operation stability is improved, but the productivity decreases due to current limitations
Solution Approach 1:
The patent applies dynamics by making the open-loop current adaptive rather than fixed. The current threshold for switching to closed-loop control is dynamically adjusted based on motor parameters and operating conditions. This dynamic current management allows the system to maintain stability while optimizing productivity, as the current limit is not rigid but adapted to actual motor needs during different operational phases.
Data Source
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AI summary
Provided are a method and system for controlling an electric motor, and a controller. The method comprises: controlling an electric motor to operate in an open-loop manner; determining whether a rotational speed of the electric motor reaches a preset rotational speed; if so, determining whether the absolute value of an angle difference between an open-loop angle and a calculated position angle of the electric motor is greater than a preset angle; and if the absolute value of the angle difference is less than or equal to the preset angle, controlling the electric motor to operate in a closed-loop manner so as to avoid the situation where the electric motor cannot operate stably due to problems such as electric motor speed vibration caused by too large an angle difference between the open-loop angle and the position angle.