Compressor Motor Protection Module for Overcurrent Prevention
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Solution Overview
Problem
Existing electric motor control systems for refrigerant compressors lack effective mechanisms to dynamically manage maximum continuous current (MCC) and motor temperature, leading to potential overheating and current overload issues.
Innovation Solution
A motor protection module that integrates a digitally programmable potentiometer for MCC devices, which measures and compares current and temperature, controlling a switching device to prevent excessive current flow and temperature, using multiple MCC devices to set a predetermined MCC based on resistance ranges and remote communication for optimal protection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional line break protectors or PTC/NTC devices are used for motor protection, then motor temperature and current can be monitored, but the system complexity increases and response time is delayed due to thermal contact requirements
Solution Approach 1:
The patent combines the MCC device, current sensing, temperature monitoring, and control functions into an integrated motor protection module. This consolidation eliminates the need for separate thermal contact devices like PTC/NTC sensors and line break protectors, reducing overall system complexity while maintaining comprehensive protection capabilities through direct integration with the motor control circuitry
Solution Approach 2:
The patent replaces thermal contact-based protection mechanisms (mechanical/thermal systems) with electronic current sensing and digital processing. The MCC device uses electronic current measurement and digital comparison against preset limits, eliminating the need for thermal contact and mechanical trip mechanisms, thereby reducing system complexity and improving response time
2Reliability
If fixed MCC devices are used, then motor protection is provided, but the system cannot adapt to different motor specifications and operating conditions
Solution Approach 1:
The patent implements a programmable MCC device where the maximum continuous current threshold can be dynamically adjusted based on motor specifications, operating conditions, and load requirements. The control module allows programming of different MCC values to match specific motor ratings and operating scenarios, enabling the protection system to adapt to various motor types and conditions rather than using a fixed threshold
Solution Approach 2:
The patent changes the MCC parameter from a fixed value to a programmable variable. The system allows different MCC values to be programmed based on motor power ratings, thermal characteristics, and operating conditions. This parameter flexibility enables the same protection module to safely protect different motor specifications while maintaining optimal protection reliability for each specific application
3Reliability
If multiple MCC devices are used for comprehensive protection, then motor protection coverage is improved, but the device complexity and cost increase
Solution Approach 1:
The patent designs the motor protection module to perform multiple protection functions simultaneously: overcurrent protection, temperature monitoring, thermal protection, and MCC enforcement. This multi-functional integration means a single device provides comprehensive protection that previously required multiple separate components, reducing both device complexity and cost while maintaining or improving protection coverage
Solution Approach 2:
The patent merges current sensing, temperature sensing, comparison logic, and control output functions into a single integrated motor protection module. By combining these previously separate protection mechanisms into one unified device, the system achieves comprehensive protection coverage without increasing the number of discrete components, thereby reducing overall system complexity and cost
4Reliability
If larger electrical components are used to handle maximum current, then system reliability is improved, but the cost and size of the system increase
Solution Approach 1:
The patent implements preliminary current monitoring and control by continuously measuring motor current and comparing it against the programmed MCC threshold before overload damage can occur. The system takes preventive action by triggering protection mechanisms when approaching MCC limits, allowing the use of appropriately sized electrical components rather than oversized components designed for worst-case scenarios, thereby reducing cost while maintaining reliability
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
Effectively prevents motor overheating and current overload by dynamically adjusting MCC settings, ensuring safe operation and reducing electrical component sizes for cost savings while maintaining system reliability.
Implementation Method 1
an MCC device that generates an output that corresponds to a maximum continuous current (MCC) for the motor. The output of the MCC device may include, but is not limited to, a voltage across a resistance.
Implementation Method 2
A system including the motor may also include a temperature sensor that measures a temperature of the motor.
Implementation Method 3
A motor protection module may control a switching device that enables and disables current flow to the motor.
Data Source
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AI summary
A system includes a refrigerant compressor including an electric motor, a current sensor that measures current flow to the electric motor, a switching device configured to close and open to allow and prevent current flow to the electric motor, respectively, a maximum continuous current (MCC) device that includes a resistance corresponding to a maximum continuous current for the electric motor, and a motor protection module. The motor protection module communicates with the MCC device, the current sensor, and the switching device and determines a first MCC value for the electric motor as a function of the resistance of the MCC device. The motor protection module also selectively sets a predetermined MCC to the first MCC and controls the switching device based on a comparison of the current flow to the electric motor and the predetermined MCC.