DC Motor Temperature Estimation via Shunt Resistance Voltage
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Solution Overview
Problem
Image forming apparatuses face challenges in maintaining stable operation and image quality due to temperature variations, as existing systems rely on temperature sensors for motor control, which can lead to unnecessary stress modes and reduced performance without additional cost-effective solutions.
Innovation Solution
The image forming apparatus calculates the temperature of a DC motor using the voltage value of a shunt resistance, allowing it to control operations and adjust print conditions without a dedicated temperature sensor, thereby preventing unnecessary stress modes and maintaining stable performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a dedicated temperature sensor is used for motor control, then temperature measurement precision is improved, but device complexity and cost increase
Solution Approach 1:
The shunt resistance, originally designed solely for current sensing in the motor driving circuit, is repurposed to also serve as a temperature sensing element. By measuring the voltage across the shunt resistance and using the known relationship between shunt resistance voltage and motor temperature, the system achieves temperature measurement without adding dedicated temperature sensors, thereby reducing device complexity while maintaining measurement capability
Solution Approach 2:
The existing shunt resistance component performs dual functions: current sensing and temperature sensing. The system leverages the inherent electrical characteristics of the shunt resistance (its voltage drop and temperature-dependent behavior) to provide temperature information that would otherwise require separate sensing hardware, making the existing component serve multiple purposes
2Device complexity
If temperature sensing is implemented without additional hardware, then device complexity is reduced, but measurement precision deteriorates
Solution Approach 1:
The system continuously monitors the voltage across the shunt resistance and uses this feedback information to determine motor temperature. The controller processes the shunt voltage signal and applies correction algorithms to compensate for measurement variations, ensuring accurate temperature detection despite using a non-dedicated sensing element
Solution Approach 2:
The system exploits the temperature-dependent electrical parameters of the shunt resistance (specifically how its voltage drop changes with temperature) to infer motor temperature. By monitoring changes in the shunt resistance voltage under known current conditions, the system converts electrical parameter variations into temperature information
3Productivity
If motor operation continues without temperature-based adjustments, then productivity is maintained, but motor reliability deteriorates due to torque deterioration from temperature extremes
Solution Approach 1:
The system dynamically adjusts motor operating parameters based on real-time temperature conditions detected through shunt resistance monitoring. When the motor temperature exceeds predetermined thresholds, the controller automatically modifies operation modes (such as reducing duty cycles or adjusting driving waveforms) to prevent thermal damage, thereby maintaining reliability without significantly impacting productivity
Solution Approach 2:
The system proactively monitors motor temperature through the shunt resistance and takes preventive action before thermal damage occurs. By detecting temperature trends early and adjusting operating conditions in advance, the system prevents torque deterioration and reliability issues before they manifest, ensuring continuous safe operation
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 enables stable and high-quality printing by dynamically adjusting print conditions based on sensed temperatures, improving performance without the need for additional hardware or cost, and preventing motor torque deterioration from temperature extremes.
Implementation Method 1
FIG. 5 is a graph illustrating a relationship between a temperature and a coil resistance in an example direct current (DC) motor
Implementation Method 2
The image forming apparatus calculates the temperature of a DC motor using the voltage value of a shunt resistance
Data Source
AI summary
An image forming apparatus includes a print engine, a DC motor, a driving circuit, and a processor. The print engine forms an image. The DC motor drives the print engine. The driving circuit provides a current to the DC motor, and senses a variation of the current provided to the DC motor. The processor calculates a temperature of the DC motor based on the variation of the current flowing through the DC motor, and controls an operation of the image forming apparatus based on the calculated temperature.