Modern inverter compressors operate across frequencies from 20 Hz to 120 Hz, managing varying thermal loads while maintaining coefficient of performance (COP) values above 3.0. However, these systems face challenges with resonance points, thermal stress during transitions, and efficiency losses at certain operating frequencies—issues that directly impact both performance and component longevity.

The fundamental engineering trade-off lies in balancing rapid response to thermal demands against mechanical stress, energy efficiency, and acoustic performance across the operating envelope.

This page brings together solutions from recent research—including multi-stage frequency ramping techniques, dual winding mode switching for stability, temperature-based speed optimization, and predictive maintenance through integrated sensing. These and other approaches focus on achieving reliable, efficient operation while extending component life and maintaining optimal thermal control.

1. Air Compression System with Integrated Sensors for Real-Time Monitoring and Predictive Maintenance

GUANGDONG ZHONGTE GROUP CO LTD, 2025

High-efficiency air compression energy-saving device and system that enables real-time monitoring and predictive maintenance of air compressors. The system comprises integrated temperature, pressure, and flow sensors that provide continuous monitoring of compressor performance. This data is transmitted to a cloud-based platform for real-time analysis and alerts, enabling proactive maintenance and predictive maintenance. The system also includes a remote monitoring module that enables remote access to the compressor's operating parameters and enables remote diagnosis and repair.

2. Refrigeration System with Variable Frequency Compressor and Integrated Environmental Temperature Sensor

LIXIN TECHNOLOGY CO LTD, 2024

A refrigeration system that dynamically adjusts compressor speed based on environmental temperature conditions. The system employs a variable frequency compressor with a built-in temperature sensor to monitor environmental temperature. When the temperature exceeds a predetermined threshold, the compressor automatically switches to a higher speed mode. The system also includes a control unit that periodically checks for temperature deviations and initiates speed changes when necessary. This adaptive control enables precise temperature regulation and energy efficiency, particularly in environments with significant temperature fluctuations.

3. Integrated Frequency Conversion Device with Automatic Control for Screw Compressors in Central Air Conditioning Systems

SHANGHAI HAYE REFRIGERATION MACHINERY CO LTD, Shanghai Hanbell Precise Machinery Co., Ltd., 2024

A frequency conversion device for screw compressors in central air conditioning systems that eliminates the need for manual frequency adjustment. The device integrates a frequency converter with the control module and an indoor temperature sensor, allowing the compressor to operate within a predetermined frequency range automatically. The sensor continuously monitors the compressor's operation and adjusts the frequency converter accordingly, eliminating the need for manual frequency control.

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4. Inverter Temperature Control with Dynamic Switching Frequency Regulation Based on Device Temperature Monitoring

CARRIER CORP, 2023

Temperature control of a drive in air conditioning systems enables continuous operation by dynamically regulating the switching frequency of power electronic devices in the inverter. The temperature sensor monitors device temperatures, and when exceeding a threshold, the controller reduces switching frequency to prevent device damage. This approach eliminates the need for frequent system shutdowns, maintaining continuous operation while ensuring device reliability.

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5. Multi-Compressor Control Method with Dynamic Operation Balancing for Air Conditioning Systems

Qingdao Hisense Electronic Equipment Co., Ltd., QINGDAO HISENSE ELECTRONIC EQUIPMENT CO LTD, 2023

A multi-compressor control method for air conditioning systems that optimizes compressor operation and energy efficiency. The method employs a dynamic control strategy that balances compressor start-stop cycles with continuous operation, enabling more efficient operation under partial load conditions. The control system monitors system performance, identifies compressor operating states, and dynamically adjusts compressor operating quantities based on real-time demand and system conditions. This approach eliminates the need for traditional start-stop control and enables continuous operation, while maintaining optimal compressor performance.

CN112984713B-patent-drawing

6. Compressor Frequency Adjustment System with Real-Time Temperature Averaging and Outlier Elimination

QINGDAO HAIER AIR CONDITIONER ELECTRIC CO LTD, 2023

Air conditioner compressor operating frequency adjustment method and system to dynamically regulate compressor operation frequency by controlling compressor switching between different operating frequencies based on real-time temperature comparisons. The method involves collecting multiple temperature measurements, eliminating outliers, and calculating the average temperature to determine the optimal operating frequency. The system then continuously monitors temperature differences between the indoor and set temperatures and adjusts the compressor frequency accordingly. This approach eliminates the frequent compressor start-stop cycles while maintaining rapid temperature regulation capabilities.

7. Compressor Motor Control with Dual Winding Mode Switching for Frequency Stabilization

青岛海尔空调器有限总公司, HAIER SMART HOME CO LTD, Haier Smart Home Co., Ltd., 2022

Stabilizing compressor operation in variable frequency air conditioners to improve reliability and reduce noise. The method involves switching between two winding modes in the compressor motor to prevent instability when accelerating to target frequencies. If the target frequency is below a dividing point, the compressor operates in one winding mode. But if the target frequency is above the dividing point, the compressor first switches to the other winding mode, then accelerates to the target frequency. This prevents resonance and stress issues in the motor and pipes at certain frequencies.

CN111854102B-patent-drawing

8. Variable Frequency Air Conditioner Compressor Control with Multi-Stage Frequency Ramping and Winding Mode Switching

Qingdao Haier Air Conditioner Co., Ltd., HAIER SMART HOME CO LTD, Haier Smart Home Co., Ltd., 2022

Stable and reliable operation of variable frequency air conditioners to prevent compressor instability and noise during frequency transitions. The method involves gradually ramping up the compressor frequency using multiple pause platforms instead of directly reaching the target frequency. It switches between winding modes of the motor to optimize stability during frequency transitions. The compressor operates at a lower frequency pause platform, then the winding mode changes and it ramps up to the higher frequency pause platform before finally reaching the target frequency. This controlled ramping helps prevent resonance and instability issues during frequency transitions.

9. Control Method and Device for Variable Frequency Air Conditioners with Gradual Compressor Frequency Ramp-Up and Stability Monitoring

Qingdao Haier Air Conditioner General Corporation, HAIER SMART HOME CO LTD, Haier Smart Home Co., Ltd., 2022

A control method and device for variable frequency air conditioners that stabilizes compressor operation and reduces noise and stress. The method involves starting the compressor at a low frequency, gradually increasing it, and monitoring compressor parameters during the ramp-up. If stability or limits are exceeded, the frequency is reduced and ramping paused. This prevents compressor instability and noise issues that can occur during fast startup.

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10. Variable Frequency Compressor Control with Temperature-Based Speed Adjustment for Refrigeration Systems

JIANGSU TUOMILUO ENVIRONMENTAL TEST DEVICE CO LTD, 江苏拓米洛环境试验设备有限公司, 2022

Variable frequency compressor control for refrigeration systems that improves energy efficiency by dynamically matching compressor speed with load conditions. The control method employs a temperature-based approach to determine compressor speed adjustments, where compressor speed is controlled based on temperature differences between compartments and heater outputs. The control logic monitors temperature deviations between compartments and heater outputs, and adjusts compressor speed accordingly to maintain optimal performance. This approach enables precise control of compressor speed to match actual load conditions, thereby reducing energy consumption compared to traditional fixed-speed control.

11. Refrigeration System with Dynamic Compressor Power Control and Integrated Auxiliary Heat Exchanger Operation

CAREL IND SPA, 2022

Optimizing energy consumption in refrigeration systems through selective operation of auxiliary heat exchangers. The method involves dynamically controlling the compressor's operating power based on the specific cooling requirements of the system, rather than relying solely on the compressor's maximum capacity. This approach enables precise control of heat transfer fluid flow rates while maintaining compressor efficiency, thereby reducing overall energy consumption. The method specifically addresses the conventional approach of using compressor power to supplement heat exchanger operation, rather than integrating auxiliary heat exchangers into the compressor's operation.

12. Computer Room Air Conditioner with Dual-Frequency Compression and Integrated Air Supply Control

YMK TECHNOLOGY GROUP CO LTD, 2021

A computer room air conditioner with integrated air supply control that achieves high efficiency through dual-frequency compression. The system employs two variable-frequency compressors, one for the compressor and one for the outdoor unit, connected through a common system connection pipeline. The compressor's frequency is controlled by a frequency change model, while the outdoor unit's compressor operates at a fixed frequency. The system maintains optimal compressor performance while dynamically adjusting fan speed based on supply air temperature, ensuring efficient energy consumption and precise indoor air quality.

13. Dual Frequency Conversion Architecture for Inverter-Driven Compressors with Simultaneous 50 Hz and 60 Hz Operation

GUANGDONG HAIWAVE TECHNOLOGY CO LTD, Guangdong Hiwo Technology Co., Ltd., 2021

Dual frequency conversion system and its compressor control method for inverter-driven compressors in air conditioning systems. The system employs a dual-frequency conversion architecture to optimize compressor performance, particularly for compressors with long running times. The control method enables the compressor to operate at both 50 Hz and 60 Hz frequencies simultaneously, thereby achieving improved efficiency and reduced energy consumption.

CN111397167B-patent-drawing

14. Multi-Inverter Compressor System with Cycle-Based Temperature-Driven Energy Adjustment Mechanism

GUANGZHOU WIDE INDUSTRIAL CO LTD, 2021

Energy adjustment method, device, and unit for a multi-inverter compressor system. The method determines operating conditions based on temperature and cycle time data, rather than relying on fixed operating frequencies. It analyzes temperature changes over multiple cycles to determine optimal operating conditions for each compressor, then adjusts compressor operation based on the number of compressors and their operating cycles. This approach maximizes overall system efficiency while optimizing energy consumption.

15. DC Variable Speed Air Conditioner Control System with Dynamic Compressor Speed Adjustment Based on Temperature Profiles and Integrated Weather Forecasting

ECOER INC, 2020

A DC variable speed air conditioner control system that optimizes energy consumption by dynamically adjusting compressor speed based on temperature profiles. The system employs a speed control calculation unit to determine optimal compressor speed for each temperature curve, while a data storage unit stores historical temperature data for reference. The system integrates weather forecasting capabilities through a network communication module, which generates temperature profiles for the environment. The control system then uses this data to determine the optimal compressor speed for each temperature profile, enabling energy-efficient operation during peak periods.

16. Compressor Startup Control Method with Frequency-Based Winding Mode Switching in Variable Frequency Air Conditioners

QINGDAO HAIER CO LTD, 2020

Stable and reliable operation of variable frequency air conditioners by controlling the compressor startup sequence. The method involves judging if the target frequency is above a dividing point frequency, and if so, first running the compressor in one winding mode, then switching to the other winding mode. This allows the compressor to stabilize on each platform frequency before reaching the target. The platform frequencies are controlled based on coil pipe temperature. This prevents resonance and stress issues during compressor startup.

17. Variable Frequency Air Conditioner Compressor Control with Dual Winding Modes and Gradual Frequency Transition

QINGDAO HAIER AIR CONDITIONER, 2020

Stable and reliable operation of variable frequency air conditioners to prevent compressor instability and noise during startup. The method involves using two winding modes on the motor to smoothly ramp the compressor frequency to the target value. If the target frequency is greater than a dividing point, the first winding mode is used. The compressor runs at a pause platform frequency for a preset time, then switches to the dividing point frequency. After another pause, it reaches the target frequency. This gradual transition prevents resonance and stabilizes operation.

18. Inverter Air Conditioner Control System with Real-Time Compressor Speed Adjustment Based on Variable Operating Conditions

QINGDAO HAIER AIR CONDITIONER, 2020

Control method and device for inverter air conditioners to improve compressor performance and reliability in variable operating conditions. The method enables the air conditioner to maintain stable compressor operation during temperature and humidity changes by dynamically adjusting compressor speed. The control system monitors and adjusts compressor speed based on real-time system conditions, ensuring optimal operation and reducing stress on the compressor and associated components. This approach enables the air conditioner to maintain reliable compressor operation even in non-standard operating conditions.

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19. Control Method for Air Conditioners with Dynamic Compressor Frequency Adjustment and Parallel Heat Exchanger Configuration

Qingdao Haier Air Conditioner General Corporation, QINGDAO HAIER AIR-CONDITIONER CO LTD, 2019

Energy-saving control method for air conditioners that enables more precise and efficient temperature management through dynamic compressor frequency adjustment. The method employs a parallel heat exchanger configuration with fans integrated into each unit, where the compressor operates in response to temperature deviations between the indoor setpoint and ambient conditions. When temperature deviations exceed predetermined thresholds, the control system automatically adjusts compressor frequency, compressor, fan, and outdoor fan settings to maintain optimal operation while optimizing compressor performance. This approach enables continuous temperature regulation while maintaining compressor efficiency and reducing energy consumption.

20. Variable Speed Air Conditioner System with Self-Learning Indoor Load Adaptation Using Dynamic Lookup Table

ECOER INC, 2019

A variable speed air conditioner system that achieves precise compressor speed matching through self-learning indoor load adaptation. The system employs a dynamic lookup table to store and update indoor load coefficients based on accumulated data from previous intervals. This enables continuous adaptation of the indoor load coefficient to match the system's operating conditions, eliminating the need for external temperature and setpoint inputs. The system also continuously estimates the AC output between intervals, ensuring accurate compressor speed control.

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21. Compressor System with Mode-Switching Based on Demand and Temperature Data

EMERSON CLIMATE TECHNOLOGIES INC, 2019

Variable-capacity compressor system for climate control systems that optimizes energy efficiency and performance based on demand and outdoor conditions. The system employs a variable-capacity compressor that switches between lower-capacity and higher-capacity modes, controlled by a demand-sensing thermostat and temperature data. The compressor's runtime is compared to predetermined thresholds, allowing it to transition seamlessly between modes based on system requirements. This approach enables optimal performance across varying temperatures and system capacities.

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22. Variable Frequency Air Conditioning System with Self-Learning Adaptive Compressor Control Algorithm

ECOER INC, 2019

A variable frequency air conditioning system that optimizes compressor operation based on ambient temperature changes through self-learning. The system employs an adaptive control algorithm that continuously monitors compressor performance metrics such as current value δI, pressure changes δPc and δPe, start-up time, and target frequency. When the system's output exceeds its capacity requirements, it adjusts compressor operation parameters to maintain optimal performance while preventing excessive energy consumption. This adaptive control enables the system to dynamically adjust compressor frequency based on real-time temperature conditions, ensuring both comfort and energy efficiency.

23. Air Conditioning System with Dynamic Compressor Output Frequency Control Based on Indoor Temperature Differential

三菱电机株式会社, MITSUBISHI ELECTRIC CORP, 2019

Air conditioning system that optimizes compressor operation by dynamically controlling the compressor's output frequency based on the temperature difference between the indoor set point and the actual indoor temperature. The system monitors the temperature difference and adjusts the compressor's operation frequency to maintain the set temperature while minimizing energy consumption. This approach eliminates the repetitive on/off cycles typically associated with traditional temperature control methods, resulting in improved comfort and reduced energy waste.

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24. Inverter Air Conditioner Frequency Control System with Single-Point Infrared Temperature Monitoring and Remote Heat Source Adaptation

QINGDAO HAIER AIR-CONDITIONER CO LTD, Qingdao Haier Air Conditioner General Corporation, 2019

Frequency control system for inverter air conditioners that enables precise temperature regulation while minimizing energy consumption. The system employs a single-point infrared sensor to monitor temperature across the entire space, eliminating the need for multiple sensors. By selectively controlling the compressor operation based on the target temperature, the system achieves efficient temperature control while maintaining comfortable indoor air quality. The system's remote heat source location ensures that the air conditioner maintains a comfortable temperature even when the heat source is far from the air handler.

CN105928158B-patent-drawing

25. Air Conditioner Compressor System with Switching Element-Based AC Drive and Integrated Fan Speed and Temperature Sensors

MITSUBISHI ELECTRIC CORP, 2018

Outdoor air conditioner with advanced control of compressor operation through a novel switching element-based AC drive system. The system employs multiple switching elements to convert DC power from the compressor into pseudo three-phase AC, while incorporating fan speed detection and temperature sensing for precise control of compressor operation.

26. Compressor Frequency Conversion Control System with Integrated Monitoring Modules for Dynamic Parameter Adjustment

YULING YANG, 2017

A compressor intelligent frequency conversion control system for industrial applications that optimizes compressor performance through advanced frequency control. The system integrates multiple monitoring modules to track compressor performance parameters, including vibration, displacement, pressure differences, and pressure levels. The control module processes this data to dynamically adjust compressor operation parameters, enabling more precise control of compressor performance. The system's intelligent architecture enables real-time monitoring and predictive maintenance capabilities, allowing operators to optimize compressor operation while reducing energy consumption.

CN107490988A-patent-drawing

27. Inverter Air Conditioner Control Method with Temperature-Responsive Frequency Switching and Fan Speed Adjustment

GD MIDEA AIR-CONDITIONING EQUIPMENT CO LTD, MIDEA GROUP CO LTD, Midea Group Co., Ltd., 2017

Inverter air conditioner control method that enables precise frequency switching and optimal energy efficiency. The method detects temperature differences between indoor and outdoor environments, compares them to setpoint temperatures, and adjusts fan speeds based on the temperature difference. It then determines the optimal switching frequency between single and double rotor operation modes based on the temperature difference. This enables accurate frequency switching and optimal energy efficiency by dynamically adjusting fan speeds to match temperature conditions.

28. Multivariable Frequency Conversion Control System with Integrated Component Regulation for Air Conditioning Units

RAC ELECTRIC VEHICLES INC, 2017

A multivariable frequency conversion control system for air conditioning systems in buses and electric vehicles that improves overall system efficiency. The system enables precise control of multiple critical components, including compressor, condenser, evaporator, and expansion valve, through a single control unit and multiple frequency converters. The control unit receives temperature feedback from the space environment and generates variable frequency control signals to the frequency converters, allowing optimized operation of these components to achieve improved performance.

29. Compressor Motor Voltage Control System with Dynamic Voltage Adjustment Based on Calculated Optimal Current-Voltage Ratio

JOHNSON CONTROLS TECHNOLOGY CO, 江森自控科技公司, 2017

Controlling compressor motor voltage in HVAC systems to optimize motor efficiency through dynamic voltage adjustment. The method calculates optimal motor current based on the compressor's operating frequency and voltage/frequency ratio, then compares this to the actual measured current. When the measured current deviates from the calculated optimal, the control system adjusts the variable speed drive voltage to match the optimal current-voltage ratio, ensuring optimal motor performance and efficiency.

CN104052371B-patent-drawing

30. Integrated Thermal Frequency Conversion Control System with Temperature-Sensing Microcontroller for Air Conditioning Motors

GUANGDONG PHNIX ENERGY SAVING EQUIPMENT CO LTD, Guangdong Phnix Eco-Energy Solutions Ltd., 2016

Thermal frequency conversion control system and method that enables efficient and reliable frequency conversion of air conditioning motors. The system employs a temperature-sensing microcontroller to monitor the air temperature and control the frequency converter's output frequency based on temperature deviations. This approach eliminates the need for separate variable frequency control circuits and inverter development, while maintaining the benefits of frequency conversion. The system also integrates the compressor and frequency converter into a single control unit, simplifying system design and implementation.

31. Inverter Air Conditioner Control System with Dynamic Energy Management for Compressor Operation

TECO Technology (Hangzhou) Co., Ltd., TECO GROUP SCIENCE-TECHNOLOGY (HANGZHOU) CO., LTD., 2016

Energy-efficient operation control for inverter air conditioners that maximizes energy efficiency while maintaining user comfort. The control method employs a dynamic energy management strategy that optimizes compressor operation based on real-time system conditions, enabling significant energy savings while maintaining cooling performance.

CN104019528B-patent-drawing

32. Inverter Compressor Control Device with Integrated Power Factor Correction Circuit

NORTHEAST PETROLEUM UNIVERSITY, Northeast Petroleum University, 2016

Inverter air conditioner compressor control device that improves efficiency by enabling power factor correction (PFC) in the compressor control system. The device incorporates a power factor correction circuit that enables the compressor to operate within the optimal power factor range, thereby reducing energy losses. The circuit is integrated with an inverter compressor control system, where the power factor correction capability is utilized to optimize the compressor's performance.

33. Dynamic Load Matching Control for Multiple Inverter Compressors with Optimal Speed Assignment

BLUE STAR LTD, 2016

Controlling multiple inverter compressors in a refrigerant system to achieve higher efficiency through dynamic load matching. The system determines the required load based on temperature setpoints and operating conditions, then assigns compressors to operate at peak efficiency to deliver the required load. The compressors are controlled to run at specific rotational speeds, with each compressor operating at its optimal speed to maximize efficiency. This approach ensures optimal performance across the entire load range while maintaining peak efficiency in each compressor.

34. Frequency Energy Control Cabinet with Integrated Pressure Regulation for Industrial Compressors

SHANGHAI SAIREN ELECTRIC TECHNOLOGY CO LTD, 上海赛人电气科技有限公司, 2015

A frequency energy control cabinet for industrial compressors that optimizes compressor operation through precise pressure regulation. The control system integrates pressure sensors, analog-to-digital converters, a programmable logic controller (PLC), and an inverter to monitor compressor pressure and control the compressor's operation. The system dynamically adjusts compressor speed to maintain optimal pressure levels during both loading and unloading phases, reducing energy waste and improving product quality.

35. Air Compressor Control System with Dynamic Mode Switching and Intelligent Flow Regulation

厦门能控自动化科技有限公司, XIAMEN NENGKONG AUTOMATION TECHNOLOGY CO LTD, 2015

Control system for air compressors that optimizes energy efficiency while maintaining product quality. The system enables precise control of air pressure by dynamically switching between multiple compressor modes, with advanced features like automatic pressure regulation and intelligent flow control. This approach eliminates the traditional pressure adjustment method, where compressor operation is directly controlled based on pressure levels. The system achieves energy savings through optimized compressor operation modes, while maintaining reliable quality.

CN204493160U-patent-drawing

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