Heat Pump Compressor Motor Temperature Control to Prevent Overheating
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Solution Overview
Problem
The heat pump systems in electric vehicles face frequent motor unit damage and high maintenance costs due to difficulty in directly cooling the compressor, leading to overheating and potential failure.
Innovation Solution
A control method that monitors the compressor's motor unit temperature, adjusts refrigerant flow rates, and stops compressor operation when necessary to prevent overheating, using existing sensors to measure current and voltage and calculate coil temperature without additional temperature sensors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If the compressor operates continuously to cool or heat the vehicle interior, then the air conditioning function is maintained, but the motor unit temperature increases leading to overheating and potential failure
Solution Approach 1:
The control method performs preliminary cooling action by increasing refrigerant flow rate to the compressor before the motor unit temperature reaches dangerous levels. The system monitors temperature continuously and proactively adjusts refrigerant flow to prevent overheating, rather than waiting for failure conditions to develop
Solution Approach 2:
The system implements feedback control by continuously monitoring the motor unit temperature through resistance measurements and adjusting the refrigerant flow rate accordingly. When temperature exceeds a predetermined threshold, the system increases cooling capacity; when temperature decreases below the threshold, it reduces cooling capacity, creating a closed-loop temperature control system
2Measurement precision
If additional temperature sensors are installed to monitor compressor temperature, then temperature monitoring precision improves, but device complexity and manufacturing cost increase
Solution Approach 1:
The motor unit's existing electrical components (windings and power supply circuit) serve dual purposes: they drive the compressor and simultaneously function as temperature sensors. By measuring the electrical resistance of the motor windings, the system derives temperature information without requiring separate sensing elements, making the existing components serve themselves for multiple functions
Solution Approach 2:
The electrical resistance measurement system performs multiple functions: it monitors motor unit temperature, detects compressor operation status, and provides data for control decisions. This multi-functional approach eliminates the need for dedicated temperature sensors while maintaining comprehensive monitoring capability
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 method effectively prevents motor unit damage, reduces maintenance costs, and enhances compressor durability by directly cooling the compressor, thereby extending its lifespan and preventing failures.
Implementation Method 1
a resistance of the motor unit is calculated using the current and voltage of the motor unit measured in the initial state measurement step and a temperature of the motor unit is measured
Implementation Method 2
directly cooling the compressor by controlling a flow rate of a refrigerant
Data Source
AI summary
A heat pump system control method for a vehicle includes a process (A) of operating a compressor of an air conditioner to cool or heat an interior of the vehicle while the vehicle is driving, measuring by a controller initial states of the compressor and a refrigerant based on data detected from a data detector, and monitoring the compressor, a process (B) of determining by the controller whether a current coil temperature of a motor unit provided in the compressor is higher than a coil specification temperature through the process (A) and operating a protection mode; and a process (C) of, when the process (B) is completed, calculating by the controller a slope of a coil temperature of the motor unit over time, determining whether the temperature slope is greater than zero (0) three times consecutively to stop the operation of the compressor, and terminating control.