Electric Compressor Start Control Under Power Transistor Heat Limits
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Solution Overview
Problem
Electric compressors in air conditioners face challenges in starting smoothly at high temperatures due to the temperature characteristics of power transistors, which limit current capacity and trigger protection circuits, preventing startup.
Innovation Solution
A control device that detects the temperature of the power transistor and adjusts the motor's rotational speed or acceleration rate based on a predetermined correlation, allowing gradual startup at low speeds or accelerations when temperatures are high, and repeatedly updates these settings as the compressor starts and cools.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the protection circuit of the power transistor is operated at high temperature, then the electric compressor is prevented from starting under unsafe conditions, but the startup time is significantly extended and manual intervention is required
Solution Approach 1:
The control device dynamically adjusts the motor's acceleration rate based on the power transistor's temperature. When the temperature is high, the acceleration rate is reduced to allow gradual cooling during startup. As the temperature decreases, the acceleration rate is increased. This dynamic adjustment resolves the contradiction by enabling automatic startup without manual intervention while preventing overheating damage.
Solution Approach 2:
The invention changes the operational parameters (rotational speed and acceleration rate) according to the temperature condition of the power transistor. By establishing a correlation between temperature and acceleration rate, the system automatically adapts its startup characteristics to the thermal state, eliminating the need for manual speed adjustment and reducing startup time while maintaining reliability.
2Productivity
If the motor is started at high rotational speed when the power transistor is hot, then the startup is faster, but the power transistor may be damaged due to excessive current
Solution Approach 1:
The control device continuously monitors the temperature of the power transistor and uses this feedback to adjust the motor's acceleration rate in real-time. This closed-loop control ensures that the acceleration rate is always appropriate for the current thermal state, preventing excessive current that could damage the power transistor while maximizing the startup speed under given conditions.
Solution Approach 2:
Before the motor reaches full speed, the system preliminarily limits the acceleration rate when the power transistor temperature is high. This preliminary action prevents the power transistor from being subjected to excessive current stress during the critical startup phase, ensuring its safety before gradually allowing higher speeds as cooling occurs.
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
Enables smooth and reliable startup of electric compressors even at high temperatures by gradually increasing rotational speed or acceleration as the power transistor cools, facilitating quicker startup and efficient operation.
Implementation Method 1
a temperature sensor that detects a temperature of the power transistor
Implementation Method 2
when the motor is started to cause a refrigerant to flow in the electric compressor and the refrigerant cools the power transistor
Data Source
AI summary
Control device for an electric compressor and a start control method of an electric compressor that can smoothly and reliably start the electric compressor even at high temperature. Even in a high temperature state of a power transistor, a rotational speed or an acceleration rate of a motor according to the temperature is set to gradually start the electric compressor. After the commencement of the start, the temperature of the power transistor is repeatedly checked for every predetermined time to update the rotational speed or the acceleration rate of the motor, and the rotational speed or the acceleration rate of the motor is increased according to the temperature of the power transistor, thereby allowing quick start.