Motor Controller Hold State Detection via Signal Polarity Reversal
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Solution Overview
Problem
Existing motor control systems for brushless DC motors in image processing apparatuses struggle to accurately distinguish between the position hold state and the locked state, leading to erroneous recognition and improper motor control, which affects document and sheet transportation accuracy.
Innovation Solution
A motor controller with a rotary detector and drive controller that periodically reverses the control signal polarity for a predetermined reverse time period, allowing the system to differentiate between the hold and locked states by blocking power supply when the reverse cycle is not detected for a certain lock detection time period.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the driver blocks output of driving current/voltage when control signal is not changed for predetermined time, then the motor enters locked state to prevent idle running, but the position hold state is erroneously recognized as locked state causing improper motor control
Solution Approach 1:
The drive controller outputs a control signal with periodic polarity reversal at a predetermined reverse cycle during position hold state. This periodic action creates a distinctive signal pattern that prevents the driver from erroneously recognizing the hold state as a locked state, while still allowing the driver to detect true idle states when no control signal is received for the lock detection time period.
Solution Approach 2:
The system uses feedback from the control signal detection mechanism to distinguish between position hold state and locked state. The driver monitors the control signal from the drive controller and uses the presence of periodic polarity reversal as feedback to maintain position hold state, while the absence of any control signal for lock detection time period Tr triggers the locked state.
2Measurement precision
If the driver continuously monitors control signal to distinguish hold state from locked state, then accurate state recognition is achieved, but the system complexity increases
Solution Approach 1:
The drive controller generates the periodic polarity reversal control signal automatically during position hold state without requiring external intervention or complex additional circuitry. This self-service approach allows the system to maintain accurate state detection while minimizing added complexity, as the control signal serves dual purposes of motor control and state identification.
Data Source
AI summary
A motor controller, operatively connected to a motor having an output shaft, includes a rotary detector to detect a rotation direction and a rotation amount of the output shaft of the motor to generate an actual rotary signal, a drive controller to generate a control signal based on the actual rotary signal and a target rotary signal indicating a target rotary direction and a target rotary amount, and a driver to supply a driving power to the motor based on the control signal. When the motor is in a hold state, the control signal is reversed periodically for a predetermined reverse time period T2 per a predetermined one reverse cycle T1. When the control signal is not reversed for a certain lock detection time period Tr that is longer than the revere cycle T1 of the control signal, supply of the driving power to the motor is blocked.