Refrigeration cycle apparatus
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Solution Overview
Problem
The control apparatus for refrigeration cycle apparatuses does not account for changes in ambient conditions and device performance variations, leading to potential failures and capacity deterioration due to inaccuracies in calculating the upper limit speed of inverter motors.
Innovation Solution
A refrigeration cycle apparatus with a variable compressor rotation number and a control system that includes a capacity controller and a protection controller to calculate and select a rotation number command, ensuring optimal capacity and protection targets are met.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the upper limit speed is calculated using fixed PI control without considering environmental changes and device aging, then the control method is simple, but the reliability deteriorates due to potential failures from inaccurate speed commands
Solution Approach 1:
The control system is segmented into three independent controllers: a capacity controller for optimizing performance, a protection controller for preventing failures, and a rotation number selection unit for coordinating them. This segmentation allows each controller to focus on specific functions, improving overall reliability while maintaining manageable complexity through modular design.
Solution Approach 2:
The system dynamically adjusts the compressor's rotation number command by continuously comparing outputs from the capacity controller and protection controller. The rotation number selection unit selects the appropriate command based on real-time system conditions, enabling the system to adapt to environmental changes and device aging, thereby improving reliability without requiring complete system redesign.
2Manufacturing precision
If the upper limit speed command is calculated without considering moment-to-moment changes in ambient environment and device performance, then the control algorithm is simple, but the manufacturing precision deteriorates as the calculated speed deviates from the original upper limit speed
Solution Approach 1:
The protection controller continuously monitors system parameters and compares the calculated rotation number against safe operating limits. This feedback mechanism ensures that the rotation number command remains accurate and within acceptable ranges, compensating for environmental changes and device performance variations without requiring complex recalibration procedures.
Solution Approach 2:
The system changes operational parameters dynamically by adjusting the rotation number command based on real-time conditions. The capacity controller and protection controller work together to modify speed commands according to ambient environment changes and device aging, maintaining manufacturing precision through adaptive parameter adjustment rather than fixed thresholds.
3Productivity
If the calculated upper limit speed exceeds the original upper limit speed, then the capacity increases, but the reliability deteriorates due to increased likelihood of device failures
Solution Approach 1:
The protection controller performs preliminary anti-action by preemptively limiting the rotation number command before excessive speeds can cause device failures. It calculates safe operating boundaries and prevents the capacity controller from commanding speeds that would exceed original upper limits, thereby protecting devices while allowing maximum safe capacity operation.
Solution Approach 2:
The system takes preliminary action by establishing protection targets and rotation number limits in advance through the protection controller. These pre-established boundaries ensure that even when capacity optimization suggests higher speeds, the system remains within safe operating parameters, preventing failures before they occur.
4Reliability
If the calculated upper limit speed falls below the original upper limit speed, then the device protection is improved, but the productivity deteriorates due to reduced refrigeration capacity
Solution Approach 1:
The rotation number selection unit acts as an intermediary between the capacity controller and the compressor motor. It receives rotation number commands from both the capacity controller (which may suggest higher speeds for maximum capacity) and the protection controller (which sets safe operating limits), and selects the appropriate command. This intermediary function ensures that device protection is maintained while maximizing refrigeration capacity within safe boundaries, preventing unnecessary capacity reduction.
Data Source
AI summary
The present invention has an object to provide a refrigeration cycle apparatus. A refrigeration cycle apparatus according to the present invention includes: a compressor; and a control apparatus configured to calculate a rotation number command of the compressor. The control apparatus includes a capacity controller configured to calculate the rotation number of the compressor as a capacity rotation number, a protection controller configured to calculate the rotation number of the compressor as a protection rotation number and a rotation number selection unit configured to select any one of the capacity rotation number and the protection rotation number as the rotation number command of the compressor. The rotation number command of the compressor is calculated so that at least any one of causing the current capacity value to approach the capacity target value and causing the protection variable to approach the protection target value is satisfied.