Motor Controller Speed State Detection via Sensorless and Proximity Fusion
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Solution Overview
Problem
In motor controllers performing speed sensorless control, the detection accuracy of the speed attainment state and speed zero state is compromised due to limitations in control performance, leading to discrepancies between estimated and actual rotation speeds.
Innovation Solution
A motor controller that includes a rotation speed estimating unit based on current and primary frequency information, a proximity switch for ON/OFF signal output, and a state determining unit that computes rotation speed using these signals to enhance detection accuracy of speed attainment and zero states by comparing estimated and computed values against reference values.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If speed sensorless control is used to reduce cost and size, then the motor controller does not require a speed sensor or wiring, but the detection accuracy of speed attainment state and speed zero state decreases due to discrepancies between estimated and actual rotation speeds
Solution Approach 1:
The patent combines two rotation speed detection methods: the rotation speed estimation value from speed sensorless control and the rotation speed computation value from proximity switch signals. By merging these two complementary approaches, the system maintains the simplicity of sensorless control while achieving accurate speed state detection through the combined information from both methods.
Solution Approach 2:
The proximity switch serves as an intermediary element that provides additional speed information without requiring a full speed sensor. The proximity switch detects rotational position indirectly, and this intermediate measurement is processed into a rotation speed computation value that complements the estimation from control parameters, enabling accurate speed state detection.
2Adaptability or versatility
If rotation speed estimation is used for state detection, then the system operates without speed sensors, but the rotation speed estimation value may differ greatly from actual speed due to control performance limitations
Solution Approach 1:
The system implements feedback by continuously comparing the rotation speed estimation value with the rotation speed computation value derived from proximity switch signals. This feedback mechanism allows the controller to verify the accuracy of speed sensorless control and reliably determine speed attainment and speed zero states through the concordance or discrepancy between the two speed values.
Data Source
AI summary
A motor controller includes: a rotation speed estimating unit that estimates a rotation speed of a motor on the basis of current information and primary frequency information of the motor; a proximity switch that outputs an ON signal when a portion of a rotating body of the motor is in proximity and outputs an OFF signal when a portion of the rotating body of the motor is not in proximity; a rotation speed computing unit that computes a rotation speed of the motor on the basis of the ON signal and the OFF signal; and a state determining unit that determines whether a present state is a speed attainment state and whether a present state is a speed zero state on the basis of a rotation speed estimation value estimated by the rotation speed estimating unit and a rotation speed computation value computed by the rotation speed computing unit.