Control device for electric compressor, electric compressor, air conditioning device for moving object, and method for controlling electric compressor
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Solution Overview
Problem
The electric compressor in car air conditioners does not always stop through the standard process, leading to potential abnormal current flow and damage to electronic components when the key is turned off, especially when the compressor is suddenly stopped without going through the predetermined stop process.
Innovation Solution
A control device with a stop request detector and operation stop control unit that decelerates the electric compressor based on detected speed ranges and deceleration rates, followed by a standby period before stopping, to manage forced stop requests differently from normal stop processes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If the electric compressor is suddenly stopped when the key is turned off, then the power supply is stopped quickly, but abnormal current may flow through the control circuit and damage electronic components
Solution Approach 1:
The control device performs preliminary deceleration of the electric compressor before complete shutdown. When a forced stop request is detected, the controller first decelerates the compressor motor from its current speed to a predetermined low speed, then stops the motor. This preliminary deceleration action prevents sudden stopping that would cause abnormal current flow and protects electronic components from damage.
Solution Approach 2:
The control device provides beforehand cushioning by implementing a deceleration phase before the forced stop. The controller reduces the motor speed gradually using a predetermined deceleration rate before cutting off power, cushioning the abrupt stop that would otherwise generate harmful currents and protect the control circuit from voltage spikes.
2Reliability
If the electric compressor goes through a normal stop process with stepwise speed setting, then electronic components are protected, but the stopping time is extended
Solution Approach 1:
The control device applies dynamics by adjusting the deceleration strategy based on operating conditions. For forced stops, it uses a predetermined deceleration rate that is faster than normal operation but still protective. The controller dynamically determines the deceleration profile based on the current speed and operational state, optimizing the balance between protection and speed.
3Loss of time
If the electric compressor is decelerated at a high rate during forced stop, then the stopping time is reduced, but the risk of abnormal current increases
Solution Approach 1:
The control device uses parameter changes by implementing a two-stage deceleration process. First, the motor is decelerated at a predetermined high deceleration rate from operating speed to a low speed threshold. Second, when the speed reaches the threshold, the controller maintains the low speed for a predetermined time before complete shutdown. This parameter change strategy allows fast stopping while avoiding the harmful effects of abrupt cessation.
Data Source
AI summary
A control device for a compressor includes an operation stop control unit that stops the compressor in a procedure different from a normal stop request signal when a signal different from the normal stop request signal that requests the compressor to stop in a predetermined procedure and a forced stop request signal from a device including the compressor is detected. The operation stop control unit stops the compressor in the different procedure according to a speed of the compressor when the forced stop request signal is detected.