Inverter Compressor Control for Stable Heat Source Operation
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Solution Overview
Problem
The existing heat source apparatuses with inverter-driven electric compressors experience unexpected and uncontrolled stoppages due to overcurrent protection, leading to unstable operation and potential device issues, which can disrupt cold or heat output demands.
Innovation Solution
Incorporating an inverter-protective-function estimating unit within the control device to predict and manage inverter stoppages by reducing load through capacity control, limiting refrigerant intake, and using a hot-gas bypass valve, allowing for controlled operation and delayed stoppages to prevent sudden failures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the inverter device is provided with overcurrent protection that stops the inverter device when overcurrent flows, then the power device is protected from damage, but the heat source apparatus experiences unexpected stoppages that disrupt cold or heat output demands
Solution Approach 1:
The control device performs preliminary actions by detecting overcurrent conditions before they cause inverter stoppage, and proactively reduces the operation capacity of the electric compressor. This prevents the inverter from tripping by addressing the root cause (excessive current) before the protective function activates, thereby maintaining continuous operation while still protecting the power device.
Solution Approach 2:
The control device continuously monitors the operation state of the inverter and detects overcurrent conditions. Based on this feedback, it dynamically adjusts the electric compressor's operation capacity to maintain current within safe limits, creating a closed-loop control system that balances protection with continuous operation.
2Reliability
If the inverter control portion independently stops the inverter device based on its own protective function determination, then the power device is protected, but the control device of the heat source apparatus cannot perform predetermined sequence stopping operations
Solution Approach 1:
The control device receives feedback signals from the inverter control portion indicating when protective functions are activated. This allows the control device to synchronize its stopping operations with the inverter's protective actions, enabling coordinated shutdown sequences while maintaining power device protection.
Solution Approach 2:
The control device merges its control functions with the inverter control portion's protective functions by integrating the detection and response mechanisms. This unified approach allows both the control device and inverter control portion to work together, combining independent protection capabilities with coordinated system-wide control for orderly shutdown procedures.
3Duration of action of stationary object
If the operation capacity of the electric compressor is reduced to prevent inverter stoppage, then stable operation time is extended, but the cold or heat output capacity is reduced
Solution Approach 1:
The control device applies partial action by reducing the electric compressor's operation capacity only to the extent necessary to prevent inverter overcurrent, rather than completely shutting down the system. This partial reduction maintains stable operation while preserving sufficient cooling or heating capacity to meet demand, avoiding excessive capacity reduction.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This solution enables the heat source apparatus to anticipate and manage inverter stoppages, ensuring stable operation, extending the system's operational time and preventing unexpected shutdowns, thus maintaining consistent cold or heat output.
Implementation Method 1
a condenser (13) that condenses the refrigerant compressed by the electric compressor (5)
Implementation Method 2
an evaporator (8) that evaporates the refrigerant expanded by the expansion valve (30)
Implementation Method 3
controlling the degree of opening of a hot-gas bypass valve (14)
Data Source
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.