Inverter Compressor Boot Capacitor Charging for Lower Leakage Current
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Solution Overview
Problem
The leakage current during boot capacitor charging operations in inverter compressors is significantly higher than during other operations, potentially triggering leakage breakers and affecting compressor performance.
Innovation Solution
The boot capacitor charging operation is performed at a carrier frequency lower than the normal operation frequency, with a preparatory operation conducted at a similar or lower frequency, and the carrier frequency is gradually increased to the normal operation frequency during the transition to normal operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If boot capacitor charging operation is performed at normal carrier frequency, then charging speed is improved, but leakage current increases
Solution Approach 1:
The patent applies dynamics by making the carrier frequency adjustable rather than fixed. The control device dynamically changes the carrier frequency based on the operation phase: using a first (lower) frequency during boot capacitor charging to reduce leakage current, and a second (higher) frequency during normal operation to improve charging speed and performance.
Solution Approach 2:
The patent applies parameter changes by modifying the carrier frequency parameter according to different operational requirements. The control device changes the frequency parameter from a first value during preparatory charging operations to a second value during normal operations, optimizing both leakage current reduction and charging efficiency.
2Object-generated harmful factors
If carrier frequency is reduced for boot capacitor charging, then leakage current is reduced, but preparatory time increases
Solution Approach 1:
The patent uses dynamic frequency adjustment to resolve this contradiction. By switching to a lower carrier frequency only during the specific phase of boot capacitor charging and then transitioning to a higher frequency for normal operation, the system minimizes leakage current during the critical charging phase while recovering performance during operational phases.
Solution Approach 2:
The patent applies periodic action by using different carrier frequencies for different operational periods. The control device periodically switches between a first carrier frequency for preparatory operations and a second carrier frequency for normal operations, optimizing performance for each phase.
3Stability of the object's composition
If carrier frequency is gradually increased during transition, then operational stability is improved, but transition time increases
Solution Approach 1:
The patent applies dynamics by implementing a dynamic frequency transition mechanism. The control device gradually increases the carrier frequency from the first value to the second value during the transition from preparatory to normal operation, preventing abrupt changes that could cause operational instability while managing the transition efficiently.
Data Source
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AI summary
The present invention provides an inverter compressor operating method and a compressor driving device with reduced leakage current. A boot capacitor (407) that functions as an operating power supply for a high-arm-side transistor (401) provided in an inverter (4) has to be charged prior to normal operation of a motor (M1). This operation of charging the boot capacitor (407) is performed at a carrier frequency (f2) that is lower than a carrier frequency (f1) for the normal operation. This reduces the leakage current occurring during the boot capacitor charging operation.