Heat Source Inverter Load Control for Predictable Shutdowns
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Solution Overview
Problem
The sudden and unexpected stoppages of inverter devices in heat source apparatuses, such as turbo chillers, due to overcurrent protection mechanisms can lead to unstable operation and undesirable shutdowns, affecting the demand for cold or heat output and potentially causing issues in the chiller's devices.
Innovation Solution
An inverter-protective-function estimating unit is introduced to predict stoppages by calculating the protective function of the inverter control portion, allowing for controlled reduction of the load on the inverter device through capacity control, such as limiting the inlet vane opening, reducing rotation speed, and using a hot-gas bypass valve, thereby delaying the stopping operation and ensuring a stable sequence.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If overcurrent protection is provided in the inverter device to protect the power device, then the power device is protected from damage, but the inverter device stops suddenly and unexpectedly causing unstable operation of the heat source apparatus
Solution Approach 1:
The control device performs preliminary actions by estimating the protective function calculation results before the inverter device actually stops. When the integrated value approaches the upper limit, the control device proactively reduces the load on the inverter device, preventing sudden stoppages and ensuring stable operation while maintaining power device protection.
2Reliability
If the inverter control portion stops the inverter device independently based on its own determination, then the power device is protected, but the control device of the heat source apparatus cannot ascertain the stoppage and cannot perform predetermined shutdown sequence
Solution Approach 1:
The control device receives feedback by estimating the protective function calculation results (integrated value) from the inverter control portion. This feedback mechanism allows the control device to ascertain the stoppage timing and perform predetermined shutdown sequences, while the inverter device maintains its independent protection capability.
3Duration of action of stationary object
If load reduction control is performed when integrated value approaches upper limit, then stable operating time is extended, but additional control complexity is introduced
Solution Approach 1:
The load reduction control is merged with the existing protective function estimation process. The control device uses the same estimation mechanism to both monitor protection status and trigger load reduction, avoiding additional complex control systems while extending stable operating time.
Data Source
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AI summary
A heat source apparatus in which a control device of the heat source apparatus can ascertain a stoppage of an inverter device and in which a stable operating time of the heat source apparatus can be extended is provided. The heat source apparatus includes an electric compressor that is driven by an inverter device and that compresses a refrigerant, the inverter device having a protective function that performs stoppage for device protection on the basis of a predetermined calculation by an inverter control portion, and a control device that controls cold output and/or heat output. The control device includes an inverter-protective-function estimating unit that estimates a calculation result of the protective function of the inverter control portion.