Electric Compressor Inverter Logic Error Detection
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Solution Overview
Problem
Conventional electric compressors for vehicular air-conditioners face issues with malfunction detection at low temperatures, leading to potential overheating and inefficient heating due to reliance on external control units, which can result in incorrect drive signal application to switching devices, causing malfunctions.
Innovation Solution
Incorporating a logic error detector within the inverter device to compare computed drive signals with actual signals, cutting off input to the switching circuit when errors are detected, and utilizing a comparator to ensure matching drive signals and computed values, thereby preventing incorrect operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the electric compressor relies on external control units for drive signal control, then the device complexity is reduced, but the reliability deteriorates due to potential malfunction detection failures at low temperatures
Solution Approach 1:
The patent merges the malfunction detection function into the inverter device by integrating a logic error detector that compares computed drive signals with actual signals applied to switching devices. This combines the control unit's signal generation function with the inverter's signal execution function, creating a unified system that can detect errors locally without requiring separate external monitoring systems.
Solution Approach 2:
The patent implements feedback by having the logic error detector continuously monitor the correspondence between computed drive signals from the control unit and actual signals applied to the switching circuit. When a discrepancy is detected, the system provides feedback by cutting off the drive signal input, creating a closed-loop control system that automatically corrects errors.
2Reliability
If the inverter device includes logic error detector and comparator circuits, then the reliability improves through accurate malfunction detection, but the device complexity increases
Solution Approach 1:
The patent applies preliminary action by performing logic error detection before the malfunction can cause damage. The logic error detector proactively compares computed signals with actual applied signals and cuts off the drive signal input preemptively when errors are detected, preventing overheating and component failure before they occur.
Solution Approach 2:
The patent introduces an intermediary element - the logic error detector - that mediates between the control unit and the switching circuit. This intermediary component receives computed drive signals, compares them with actual signals, and controls the cutoff of drive signal input, acting as a buffer that protects the system without requiring fundamental changes to the control unit or switching circuit.
3Reliability
If drive signals are cut off immediately when logic errors are detected, then the reliability improves by preventing malfunctions, but the productivity decreases due to reduced operational time
Solution Approach 1:
The patent applies preliminary anti-action by cutting off the drive signal input preemptively when logic errors are detected, preventing the harmful effects of malfunction before they can occur. This protective measure prioritizes system safety over continuous operation, stopping the compressor only when necessary to prevent damage.
Data Source
AI summary
An electric compressor, wherein an inverter device, which controls the operation of an electric motor by commands from an external control unit, is provided with a drive IC which computes drive signals of the electric motor based on the same, a switching circuit which converts the drive signals to rotation control signals of the electric motor, and an output signal control IC which cuts off input of the drive signals to the switching circuit at the time of an abnormality and wherein, furthermore, the drive IC is provided with a comparator which compares drive signals which are input to the switching circuit and computed values of the drive signals at a control unit inside the drive IC and, when the drive signals and the computed values do not match, the comparator makes the output signal control IC cut off input of the drive signals to the switching circuit.