Electric Compressor Ripple Voltage Detection for Resonance Protection
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Solution Overview
Problem
Existing electric compressor systems in vehicle air conditioners face issues with detecting excessive current due to resonance caused by large ripple voltages, which can lead to damage if not properly managed.
Innovation Solution
A control device that samples the input voltage of an electric compressor at unequal intervals and calculates the waveform of the ripple component, allowing for the detection of abnormal ripple voltages and implementation of resonance protection control by adjusting the motor's rotation speed.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If equal interval sampling is used for voltage detection, then the detection system is simple and easy to implement, but it cannot accurately detect ripple voltage waveforms of varying frequencies
Solution Approach 1:
The patent applies dynamic sampling by varying the sampling interval based on the detected ripple voltage frequency. The control device adjusts the sampling interval to be inversely proportional to the ripple frequency, allowing accurate waveform capture across different operating conditions while maintaining system simplicity.
Solution Approach 2:
The sampling interval parameter is dynamically changed based on the detected ripple frequency. By making the sampling interval variable rather than fixed, the system can accurately detect ripple waveforms of varying frequencies without increasing overall system complexity.
2Ease of operation
If the sampling interval is fixed, then the detection method is simple, but it fails to adapt to frequency variations in ripple voltage
Solution Approach 1:
The system transitions from static to dynamic sampling by continuously adjusting the sampling interval based on real-time ripple frequency detection. This allows the simple detection method to adapt to varying frequencies without complicating the overall operation.
Solution Approach 2:
The control device uses feedback from ripple frequency detection to adjust the sampling interval. The detected frequency information feeds back to modify the sampling parameters, enabling automatic adaptation to frequency variations while keeping the detection method straightforward.
3Measurement precision
If unequal interval sampling is implemented, then ripple voltage detection accuracy improves, but the detection system becomes more complex
Solution Approach 1:
The patent implements dynamic sampling where the interval between samples varies based on the detected ripple frequency. This approach captures the ripple waveform accurately at different frequencies without requiring complex hardware modifications, as the complexity is managed through adaptive control logic.
Solution Approach 2:
The sampling interval parameter is dynamically adjusted based on detected frequency conditions. By changing this single parameter adaptively, the system achieves high detection accuracy without proportionally increasing overall system complexity.
4Reliability
If resonance protection control is added to adjust motor speed, then compressor protection from excessive current is improved, but the control system complexity increases
Solution Approach 1:
The control device detects ripple voltage and proactively adjusts motor speed before excessive current and damage can occur. By taking preliminary protective action based on ripple detection, the system prevents resonance-related failures without requiring complex post-failure protection mechanisms.
Solution Approach 2:
The resonance protection control uses feedback from ripple voltage detection to adjust motor speed. The detected ripple information feeds back to the control device, which automatically modifies operating parameters to prevent excessive current, creating a simple yet effective protection loop.
Data Source
AI summary
Provided is a method for detecting a ripple voltage. A control device is provided with: an acquiring unit which acquires the voltage value of an input voltage of a battery-driven electric compressor at irregular intervals; and a waveform computing unit which computes the waveform of a ripple component of the input voltage on the basis of the acquired voltage value.