Compressor Speed Control to Reduce HVAC Start-Stop Cycling
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Solution Overview
Problem
Existing air conditioning systems face challenges in reducing the frequency of compressor start/stop cycles and preventing excess air conditioning capacity, leading to increased power consumption and reduced efficiency.
Innovation Solution
Implementing a controller that adjusts the compressor's rotation speed based on request values from indoor units, prioritizing decrease in air conditioning capacity when indoor temperatures are within a threshold range of the target temperature, and switching to normal rotation speed control when temperatures deviate from the threshold.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If a time in which stopping of the compressor is prohibited is set, then the frequency of thermo-start/stop can be reduced, but air conditioning operations in a state of excess air conditioning capacity may continue
Solution Approach 1:
The patent applies dynamics by making the compressor rotation speed adjustable and variable rather than fixed. The controller dynamically changes the rotation speed based on real-time temperature deviations and request values from indoor units, allowing the system to adapt to changing conditions and avoid both excessive start/stop cycles and prolonged excess capacity operation.
Solution Approach 2:
The patent changes the parameter of compressor rotation speed from a fixed value to a variable parameter that can be adjusted based on operating conditions. By modifying the rotation speed parameter in response to temperature deviations and capacity requests, the system resolves the contradiction between reducing start/stop frequency and avoiding excess capacity operation.
2Reliability
If the prohibiting time is increased, then the occurrence of outdoor thermo-off is suppressed, but the compressor might not be stopped even when air conditioning capacity requested by each indoor unit decreases
Solution Approach 1:
The patent implements feedback by continuously monitoring temperature deviations at indoor units and request values for air conditioning capacity changes. The controller uses this feedback information to dynamically adjust the compressor rotation speed, ensuring reliable suppression of unnecessary outdoor thermo-off while maintaining the ability to adjust capacity in response to actual system needs.
Solution Approach 2:
The patent applies preliminary action by proactively adjusting the compressor rotation speed before outdoor thermo-off occurs. When temperature deviations are within a threshold range and capacity reduction is requested, the controller preemptively reduces rotation speed or prevents outdoor thermo-off, avoiding the need for subsequent corrective actions.
3Productivity
If the prohibiting time is set short, then it is possible to suppress the occurrence of outdoor thermo-off, but it might not be possible to sufficiently reduce the frequency of thermo-start/stop
Solution Approach 1:
The patent uses dynamics to enable real-time adjustment of compressor rotation speed based on actual system conditions. This dynamic control allows the system to extend the prohibiting time when appropriate without causing excessive start/stop cycles, as the rotation speed can be adjusted to match actual capacity needs rather than relying on fixed timing.
Solution Approach 2:
The patent changes the approach from fixed time-based control to parameter-based control, where the compressor rotation speed parameter is adjusted according to temperature deviations and capacity requests. This allows flexible extension of prohibiting time when conditions warrant it, sufficiently reducing thermo-start/stop frequency while maintaining capacity adjustment capability.
Data Source
AI summary
A controller of an air conditioning apparatus performs a start/stop frequency-reducing rotation speed control in which the rotation speed of a compressor is controlled based on request values from indoor units requesting a decrease in air conditioning capacity, disregarding request values from indoor units requesting an increase in air conditioning capacity, when each indoor temperature at all indoor units performing air conditioning operation is within a scope of a prescribed threshold temperature range surrounding a target indoor temperature at each indoor unit performing air conditioning operation.