Motor Controller Hold Control for Heat Reduction
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Solution Overview
Problem
Existing motor control methods for brushless motors in image forming apparatuses face challenges in suppressing heat generation during motor stoppage and preventing unnecessary rotation due to disturbance torque, leading to potential degradation and operational issues.
Innovation Solution
A motor controller that performs hold control with a fixed excitation current to maintain the rotor's position, enhances the magnetic field with a timing signal during the stop period, and initiates rotational excitation control when the rotation start timing arrives, thereby minimizing heat generation and preventing unwanted rotation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If a fixed excitation current is continuously caused to flow through the winding to hold the rotor in position during stop, then the rotor position stability is improved, but the heat generation of the winding increases
Solution Approach 1:
The patent applies periodic action by switching between two hold control modes: first hold control with a first fixed excitation current for normal position holding, and second hold control with a second fixed excitation current (smaller than the first) when disturbance torque is detected. This periodic switching between different current levels reduces overall heat generation while maintaining rotor stability during stoppages.
Solution Approach 2:
The patent changes the parameter of excitation current magnitude based on operational conditions. By detecting disturbance torque and switching between a first current value (higher) and a second current value (lower), the system optimizes the balance between holding force and heat generation, preventing thermal degradation while ensuring rotor stability.
2Force
If a large fixed excitation current is increased to enhance holding force against disturbance torque, then the rotor position stability is improved, but the heat generation increases and may cause degradation or breakage of coating material
Solution Approach 1:
The system periodically switches between high holding force mode (first fixed excitation current) and energy-saving mode (second fixed excitation current). When disturbance torque is detected, the system activates the first hold control to provide strong holding force, then switches to the second hold control with reduced current, preventing thermal degradation while maintaining reliability.
Solution Approach 2:
The patent implements preliminary action by detecting disturbance torque in advance and proactively switching to the appropriate hold control mode. The disturbance torque detection unit identifies external forces before they cause rotor displacement, allowing the control unit to pre-adjust the excitation current level to prevent both insufficient holding and excessive heat generation.
3Measurement precision
If initial position estimation is performed every time the motor is started to detect magnetic pole position, then the accuracy of forced commutation is improved, but the rotation start is delayed and productivity decreases
Solution Approach 1:
The patent applies preliminary action by performing position estimation in advance during the stop period before forced commutation begins. The control unit estimates the rotor position using the fixed excitation current already flowing through the winding, so when rotation starts, the accurate position information is already available, eliminating the need for delayed estimation during startup.
Solution Approach 2:
The system maintains continuity of useful action by utilizing the fixed excitation current that is already flowing for hold control to perform position estimation. This eliminates the need to stop current flow or add separate estimation sequences, allowing continuous operation and faster rotation startup while maintaining measurement precision.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach effectively reduces motor heat generation during stoppages and prevents unnecessary rotation, enhancing the reliability and productivity of image forming processes by shortening the First Print Output Time (FPOT) and extending the motor's operational lifespan.
Implementation Method 1
performs hold control that continuously causes a fixed excitation current to flow through the winding to cause a fixed magnetic field for suppressing rotation of the rotor to be generated
Implementation Method 2
performs hold enhancement control that enhances the fixed magnetic field with input of a timing signal defined in advance as a trigger
Implementation Method 3
starts rotational excitation control that generates the rotating magnetic field when a rotation start timing arrives
Data Source
AI summary
A motor controller that controls a motor in which a rotor using a permanent magnet is rotated by a rotating magnetic field due to a current flowing through a winding: performs hold control that continuously causes a fixed excitation current to flow through the winding to cause a fixed magnetic field for suppressing rotation of the rotor to be generated in a suspension period in which the motor is stopped; performs hold enhancement control that enhances the fixed magnetic field with input of a timing signal defined in advance as a trigger, in the suspension period; and starts rotational excitation control that generates the rotating magnetic field when a rotation start timing arrives.