Variable frequency drive apparatuses, systems, and methods and controls for same
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
HVAC systems face challenges in detecting reverse rotation of refrigerant compressors, leading to friction, heat generation, and potential damage, as existing methods often fail to detect this condition in time to prevent damage to compressor and system components.
Innovation Solution
A detection technique that involves monitoring the compressor's dome temperature, refrigerant pressure at the inlet, and frequency of pressure oscillations to determine if the compressor is rotating in reverse, with a controller analyzing waveforms of motor current, motor torque, or refrigerant pressure to take corrective actions such as slowing or shutting down the compressor.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If reverse rotation detection is performed using existing methods, then some detection capability is provided, but detection timing is too late to prevent compressor damage
Solution Approach 1:
The patent performs preliminary detection of reverse rotation conditions by monitoring dome temperature rise rate and pressure differential during the startup phase, before significant frictional heating occurs. This early detection allows the control system to terminate startup and prevent damage before it occurs, rather than waiting for temperature thresholds to be exceeded after damage has already begun
Solution Approach 2:
The patent implements continuous feedback monitoring of dome temperature, refrigerant pressure, and temperature rise rate during compressor startup. The control system compares real-time measurements against expected values and adjusts startup termination timing based on this feedback, enabling precise detection of reverse rotation conditions at the optimal moment to prevent damage
2Measurement precision
If multiple detection parameters are monitored to improve detection accuracy, then detection reliability increases, but system complexity increases
Solution Approach 1:
The patent uses the dome temperature sensor to serve multiple functions: monitoring absolute temperature, calculating temperature rise rate, and determining when to terminate startup. The same sensor and control logic handle both normal startup monitoring and reverse rotation detection, eliminating the need for separate detection hardware and reducing overall system complexity
Solution Approach 2:
The patent combines reverse rotation detection functionality with the existing compressor control and protection system. The same microcontroller that manages normal compressor operation also performs reverse rotation detection by analyzing temperature and pressure data already being collected for other control functions, thereby avoiding additional dedicated detection hardware
Data Source
AI summary
Detection of reverse rotation or operation of a refrigerant compressor is provided. In one aspect, a detection technique includes starting the compressor and determining the compressor is rotating in a reverse direction if a dome temperature of the compressor fails to exceed a first predetermined threshold at or before expiration of a first predetermined period of time following starting, the refrigerant pressure at a refrigerant inlet of the compressor remains constant for a second predetermined period of time following starting, and/or the frequency of pressure oscillations of the refrigerant at the refrigerant inlet exceeds a second predetermined threshold. Another technique for determining the compressor is rotating in the reverse direction involves analyzing a waveform associated with motor current, motor torque, or refrigerant pressure. Further embodiments, forms, features, and aspects shall become apparent from the description and drawings.