Refrigerator having variable speed compressor and control method thereof
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Solution Overview
Problem
Conventional refrigerators with constant-speed compressors face challenges in minimizing size and material costs, energy efficiency, and reducing vibrations and noise, as they require complex sensor systems for temperature control.
Innovation Solution
A refrigerator control system that uses a thermostat and an inverter controller with a BLDC compressor, estimating internal and external temperatures based on compressor operation information to adjust compressor speed without the need for sensors, thereby minimizing system complexity and costs while improving energy efficiency and reducing noise and vibrations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a sensor system is used to control internal temperature, then temperature control precision is improved, but device complexity and material cost increase
Solution Approach 1:
The compressor serves dual functions: both cooling and temperature sensing. The inverter controller monitors the compressor's operating parameters (current, voltage, running time) to infer internal temperature conditions, eliminating the need for separate temperature sensors. This self-service approach allows the compressor to provide both cooling and sensing functions through its own operational data.
Solution Approach 2:
The patent replaces the mechanical sensor-based temperature detection system with an electronic control system that calculates temperature based on electrical parameters. The inverter controller uses current, voltage, and running time data to compute internal temperature, substituting physical sensors with computational methods that reduce hardware complexity.
2Device complexity
If a constant-speed compressor is used, then device complexity is reduced, but energy efficiency deteriorates
Solution Approach 1:
The patent transitions from a static constant-speed compressor to a dynamic variable-speed compressor controlled by an inverter. The compressor speed varies continuously based on real-time calculations of internal temperature and cooling load, allowing the system to match energy input with actual cooling demand and eliminate the energy waste associated with constant high-speed operation.
Solution Approach 2:
The inverter controller dynamically changes the compressor's operating parameters (speed, power input) based on calculated temperature and load conditions. By adjusting these parameters in response to actual cooling needs, the system achieves high energy efficiency while maintaining simple control logic that avoids complex sensor systems.
3Device complexity
If a constant-speed compressor is used, then device complexity is minimized, but vibrations and noise increase
Solution Approach 1:
The variable-speed compressor operates dynamically at optimized speeds rather than constant high speed. The inverter controller adjusts the compressor speed to match cooling demand, enabling the system to operate at lower, quieter speeds during light load conditions while maintaining adequate cooling performance, thereby reducing vibrations and noise without requiring complex mechanical damping systems.
4Ease of manufacture
If material cost is minimized, then manufacturing cost is reduced, but temperature control capability deteriorates
Solution Approach 1:
The inverter controller performs multiple functions using the same hardware: it controls compressor speed, monitors electrical parameters, calculates internal temperature, determines cooling load, and manages energy efficiency. This multi-functional approach eliminates the need for separate temperature sensors and control systems, achieving sophisticated temperature control capability while using minimal additional materials beyond the inverter itself.
Data Source
AI summary
A refrigerator and a method for controlling the same are disclosed. The refrigerator may minimize the size and material cost of the control system by controlling the internal temperature and the speed of a compressor using a thermostat used in the conventional low-capacity/low-cost refrigerator without using a system controller equipped with various sensors (internal sensors and/or external sensors) capable of controlling the internal temperature. In addition, since an inverter controller capable of controlling a BLDC compressor estimates the internal/external temperature based on operation information of the compressor, and determines the internal load, it may save energy and reduce vibrations and noise, which are the largest disadvantages of a constant-speed compressor, thereby improving satisfaction of the consumer. In addition, the BLDC compressor may be started and operated stably by applying a differentiated algorithm of the inverter controller.