Motor Control Noise Detection via Phase Current Comparison
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Solution Overview
Problem
Sensorless DC brushless motors used in image forming apparatuses face errors in rotor position estimation due to noise interference in current detection, affecting motor control accuracy.
Innovation Solution
A motor control apparatus that includes an exciting unit, a current measurement unit, and a determination unit to measure and compare currents across multiple phases, determining if noise is present and correcting for it to improve rotor position estimation accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If sensorless DC brushless motor is used without rotor position sensor, then device complexity is reduced and cost is lowered, but measurement precision of rotor position deteriorates due to noise in current detection
Solution Approach 1:
The patent implements a feedback mechanism where the measured currents from multiple phases are continuously monitored, compared, and used to detect noise conditions. The system feeds back the comparison results to determine whether noise is superimposed on the detection voltages, and accordingly adjusts the rotor position estimation process to avoid using noisy data, thereby maintaining measurement precision without adding physical sensors
Solution Approach 2:
The patent introduces an intermediary noise determination process that acts as a mediator between the current detection unit and the rotor position estimation unit. This intermediary compares measurement values from multiple phases to detect noise conditions, and based on this detection, selectively determines whether to proceed with rotor position estimation, thus preventing noise from directly degrading measurement precision
2Measurement precision
If current detection voltage is used for rotor position estimation, then measurement capability is improved, but noise interference causes errors in detection voltage leading to estimation errors
Solution Approach 1:
The system continuously monitors detection voltages from multiple phases and feeds back comparison results to determine noise conditions. When noise is detected through the feedback mechanism, the system adjusts the estimation process by excluding noisy measurement data, thereby maintaining reliability while preserving the measurement capability of the current detection system
Solution Approach 2:
The patent converts the harmful effect of noise into a detectable signal by comparing measurement values from multiple phases. The noise, which initially degrades reliability, becomes identifiable through the comparison process, allowing the system to selectively exclude only the noisy measurements while utilizing clean measurements for accurate rotor position estimation, thus transforming the harmful noise into a useful diagnostic indicator
Data Source
AI summary
In a motor control apparatus, an exciting unit excites a plurality of excitation phases of a motor. A current measurement unit measures exciting currents flowing through coils of respective phases of the motor, and generates measurement data including measurement values of the exciting currents. A determination unit determines whether or not noise is superimposed on a measurement value included in the measurement data by comparing, with respect to each of the plurality of excitation phases, the measurement data regarding a first phase coil that constitutes that excitation phase with the measurement data regarding a second phase coil that constitutes that excitation phase.