Motor Drive Device Leakage Current Reduction via Self-Energization
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Motor drive devices with DC link capacitors experience increased leakage current over long periods of non-energization, leading to reduced reliability and requiring time-consuming capacitor replacement and voltage application.
Innovation Solution
A motor drive device with a voltage detection and control system that uses deceleration energy to raise the DC link capacitor voltage to a threshold, reducing leakage current by applying the rated voltage, thereby minimizing the need for capacitor removal and replacement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the DC link capacitor is not energized for a long period, then the leakage current increases, but manual replacement and voltage application procedures are required
Solution Approach 1:
The control unit automatically detects the non-energized period of the DC link capacitor and applies voltage through the forward converter when the period exceeds a threshold, enabling the system to self-repair the capacitor without manual intervention. This eliminates the need for operators to manually replace or apply voltage to the capacitor.
Solution Approach 2:
The system performs preliminary voltage application to the DC link capacitor by controlling the forward converter before the capacitor is actually needed for operation. The control unit detects the non-energized period in advance and applies voltage proactively to prevent leakage current increase, rather than waiting for the capacitor to fail.
2Reliability
If the DC link capacitor is not energized for a long period, then the leakage current increases, but frequent manual intervention is required
Solution Approach 1:
The control unit automatically monitors the energization period and performs voltage application without requiring operator intervention. This self-service mechanism eliminates the time operators would spend on manual capacitor maintenance and reduces downtime.
Solution Approach 2:
The system continuously monitors the energization period of the DC link capacitor and maintains continuous protection against leakage current increase. The forward converter is controlled to apply voltage continuously when needed, ensuring the capacitor remains in optimal condition without interruption to system operation.
3Reliability
If the forward converter is controlled to apply voltage to the DC link capacitor, then the leakage current decreases, but the converter must be activated
Solution Approach 1:
The forward converter is controlled to apply voltage only partially or excessively when needed, rather than operating continuously. The control unit activates the converter only when the non-energized period exceeds a threshold, applying just enough voltage to repair the capacitor and reduce leakage current, thereby minimizing energy consumption.
Solution Approach 2:
The forward converter operates periodically based on the detected non-energized period of the DC link capacitor. Instead of continuous operation, the converter is activated only at intervals when the capacitor requires voltage application, reducing overall energy consumption while maintaining capacitor reliability.
Data Source
AI summary
A motor drive device includes a forward converter, reverse converter, DC link capacitor, voltage detection part, first storage part storing a threshold for the non-energized period in which the leakage current of the capacitor increases and a threshold for the applied voltage for reducing the leakage current of the capacitor, a second storage part that records a previous energization period of the capacitor, and a control part, in which the control part obtains the non-energized period of the capacitor based on the previous energization period recorded, during activation of the motor drive device, and in a case of the non-energized period obtained being longer than the threshold for the non-energized period stored, causes regeneration operation from the motor to the power supply to stop, and causes the voltage of the capacitor to rise up to the threshold for the applied voltage stored, by way of deceleration energy of the motor.