Harmonic Current Limiting to Prevent Air Conditioner Overcurrent Stops
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional harmonic current compensators can cause air-conditioning apparatuses to stop operation due to instantaneous overcurrents when system power supply voltages are unbalanced or have large voltage distortions, leading to repeated start-stop cycles and reduced capacity.
Innovation Solution
A harmonic current compensator with a limiter that detects load and compensation currents, computes control amounts, and limits the upper limit of the compensation current to prevent overcurrents, ensuring continuous operation of air-conditioning apparatuses even under conditions of significant load current changes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the harmonic current compensator increases the compensation current to cope with large load current changes, then the harmonic compensation performance is improved, but the compensation current reaches the overcurrent level and causes the air-conditioning apparatus to stop operation
Solution Approach 1:
The limiter computes a limited compensation current by limiting the control amount of the compensation current in advance before the compensation current reaches the overcurrent level. This prevents the compensation current from instantaneously reaching the overcurrent level that would cause the air-conditioning apparatus to stop operation, while still providing effective harmonic compensation.
Solution Approach 2:
The limiter changes the parameter of the control amount of the compensation current by imposing a limit on it. This parameter change ensures that the compensation current remains within safe operational limits while still effectively compensating for harmonic components in the load current.
2Reliability
If the conventional harmonic current compensator limits the compensation current to prevent overcurrent, then the air-conditioning apparatus continues operation, but the harmonic compensation effectiveness is reduced
Solution Approach 1:
The limiter computes a limited compensation current by limiting the control amount before the compensation current reaches the overcurrent level. This advance limitation prevents overcurrent while maintaining effective harmonic compensation, as the limiter still provides substantial compensation current within safe limits.
Solution Approach 2:
The limiter optimizes the parameter of the control amount by imposing a strategic limit that balances harmonic compensation effectiveness with operational safety. The limited control amount maintains sufficient compensation capability while preventing harmful overcurrent conditions.
Data Source
Figure 1
Figure 2(a)~2(e)
Figure 3
AI summary
A harmonic current compensator 15 is connected in parallel with a load 13 to a system power supply 11 and supplies a compensation current la to limit a harmonic component contained in a load current IL to be input from the system power supply 11 to the harmonic generating load 13. The harmonic current compensator 15 includes: a load current detector 31 that detects the load current IL; a compensation current detector 33 that detects the supplied compensation current la; a control amount computing portion 47 that computes a control amount of the compensation current la based on the harmonic component contained in the load current IL detected by the load current detector 31 and the compensation current la detected by the compensation current detector 33; and a limiter 49 that limits an upper limit of the compensation current Ia.