The matching of the frequency conversion control of the low temperature chiller and the dynamic response speed of the load is the key to achieving efficient and energy-saving operation. Through variable frequency control technology, the chiller can dynamically adjust the speed of the compressor according to the actual load changes, thereby achieving a precise match between the cooling capacity and the demand, and avoiding the high energy consumption and equipment wear problems caused by frequent starts and stops in the traditional fixed-frequency control method. The following will conduct a detailed analysis from aspects such as the working principle of variable frequency control, energy-saving effect, dynamic response speed, and matching strategies in practical applications.

I. Working Principle and Energy-saving Mechanism of Variable Frequency Control

Variable frequency control technology controls the rotational speed of the compressor by converting fixed-frequency alternating current into variable-frequency alternating current. When the cooling load decreases, the frequency converter will correspondingly reduce the compressor speed and decrease the refrigerant circulation volume. Conversely, when the load increases, the speed of the compressor rises to ensure that the cooling capacity matches the demand. This dynamic regulation method contrasts sharply with the fixed-frequency start-stop mode of traditional water chillers, which regulate temperature through frequent starts and stops. This not only consumes a lot of energy but also causes mechanical shock to the equipment.

The energy-saving mechanism of frequency conversion control is mainly reflected in the following aspects:

1. Avoid ineffective energy consumption: When traditional water chillers are operating at partial load, the compressor still works at a fixed speed and meets the demand by adjusting the valve opening, resulting in a large amount of energy waste. Variable frequency technology directly reduces the rotational speed, precisely matching the cooling capacity with the actual demand and avoiding unnecessary energy consumption.

2. Reduce start-stop losses: The current of a fixed-frequency compressor can reach 3 to 5 times the rated value each time it starts. Frequent start-stop not only consumes electricity but also shortens the service life of the equipment. Variable frequency technology, through soft start and continuous operation, keeps the starting current at a low level, significantly reducing impact losses.

3. Optimize system coordination: Variable frequency technology can be combined with other energy-saving measures, such as variable frequency water pumps and cooling tower fans, to achieve coordinated optimization of the entire refrigeration system. For instance, during low-load periods, the flow rate of the water pump and the rotational speed of the fan are simultaneously reduced to further decrease the energy consumption of auxiliary equipment.

Ii. Matching of variable Frequency Control and Dynamic Response speed of Load

The core advantage of variable frequency control lies in its precise response and efficient regulation to dynamic loads. In a low temperature chiller, the load variation is usually jointly determined by multiple factors such as the external ambient temperature, the quantity and type of goods, and the operating frequency. Under the traditional constant frequency control mode, the equipment always operates at a fixed power output, making it difficult to adjust the cooling capacity according to the actual load demand. This leads to "over-cooling" of the equipment under low load conditions, thereby increasing unnecessary energy consumption. Variable frequency regulation technology enables the compressor and fan to precisely match the actual refrigeration demand by dynamically adjusting the operating frequency of the equipment, thereby achieving efficient and energy-saving operation.

In practical applications, the matching of variable frequency control and the dynamic response speed of the load is mainly reflected in the following aspects:

Dynamic load matching: Variable frequency regulation technology precisely ADAPTS to the actual load requirements by dynamically adjusting the power supply frequency. This not only reduces energy waste but also significantly enhances the stability of temperature control and the operational lifespan of equipment. The core advantage of this technology lies in its precise response and efficient regulation of dynamic loads, providing a feasible solution for the green transformation of the cold chain industry.

2. Low-load operation optimization: Under low-load conditions, variable frequency technology can reduce the operating frequency of the compressor to 50% to 70% of the rated frequency, effectively reducing the output of cooling capacity and significantly lowering energy consumption. Research shows that the power consumption of equipment has a nonlinear relationship with the operating frequency. When the operating frequency drops to 80%, the power consumption can be reduced to about 50% of the rated power.

3. Multi-technology combined regulation: In some high-end water chillers, variable frequency control and guide vane control methods are organically combined, fully leveraging the advantages of both control methods to achieve stepless regulation of cooling capacity from 10% to 100%, which is perfectly matched with the actual load. For instance, Midea's magnetic levitation variable frequency centrifugal chiller adopts multi-technology combined regulation to ensure the optimal efficiency while expanding the operating range of the unit. It can achieve a single compressor refrigeration load as low as less than 10% and ensure the normal operation of the unit when the cooling water temperature drops to 12℃.

Iii. Performance of Variable Frequency Control in Practical Applications

In practical applications, variable frequency control technology has been widely used in various water chillers and air conditioning systems, achieving remarkable energy-saving effects and improvements in operational efficiency. For example:

1. Data centers and industrial applications: In environments with extremely high requirements for temperature and humidity, such as data centers, variable frequency control technology is employed to optimize the operational efficiency of cooling systems. By adjusting the speed of the cooling tower fan and the condensate pump to respond to the load conditions of the chiller, this system can increase the COP (energy Efficiency ratio) of the chiller, thereby reducing the overall energy consumption.

2. Commercial and industrial buildings: In commercial and industrial buildings, variable frequency control technology is used to optimize the operation of central air conditioning systems. For instance, research by Shenzhen Tongli Mechanical and Electrical Engineering Co., Ltd. indicates that by adopting feedback, feedforward and adaptive control strategies, water chillers can better adapt to changes in external loads, enhancing overall operational efficiency and energy-saving effects.

3. Cold chain industry: In the cold chain industry, variable frequency control technology is used to optimize the operation of cold storage facilities. By dynamically adjusting the operating frequencies of the compressor and fan, the cold storage can more precisely control the temperature, thereby reducing energy waste and equipment wear and tear.

Iv. Matching Strategies for Variable Frequency Control and Dynamic Response Speed of Load

In order to achieve the optimal match between variable frequency control and the dynamic response speed of the load, optimization needs to be carried out from the following aspects:

Control strategy optimization: By adopting advanced control strategies such as feedforward control and adaptive control, the response speed of the chiller to dynamic load changes can be enhanced. For instance, research by Shenzhen Tongli Electromechanical Engineering Co., Ltd. indicates that through feedforward control, the chiller can adjust the load in real time, thereby enhancing the dynamic response speed of the system.

2. Multi-technology combined regulation: In some high-end water chillers, variable frequency control and guide vane control methods are organically combined, fully leveraging the advantages of both control methods to achieve stepless regulation of cooling capacity from 10% to 100%, which is perfectly matched with the actual load. For instance, Midea's magnetic levitation variable frequency centrifugal chiller adopts multi-technology combined regulation to ensure the optimal efficiency while expanding the operating range of the unit. It can achieve a single compressor refrigeration load as low as less than 10% and ensure the normal operation of the unit when the cooling water temperature drops to 12℃.

3. System integration and collaborative optimization: Variable frequency control technology can be combined with other energy-saving measures, such as variable frequency water pumps and cooling tower fans, to achieve collaborative optimization of the entire refrigeration system. For instance, during low-load periods, the flow rate of the water pump and the rotational speed of the fan are simultaneously reduced to further decrease the energy consumption of auxiliary equipment.

V. Conclusion

The matching of the frequency conversion control of the low temperature chiller and the dynamic response speed of the load is the key to achieving efficient and energy-saving operation. Through variable frequency control technology, the chiller can dynamically adjust the speed of the compressor according to the actual load changes, thereby achieving a precise match between the cooling capacity and the demand, and avoiding the high energy consumption and equipment wear problems caused by frequent starts and stops in the traditional fixed-frequency control method. In practical applications, variable frequency control technology has been widely used in various water chillers and air conditioning systems, achieving remarkable energy-saving effects and improvements in operational efficiency. By optimizing the control strategy, joint regulation of multiple technologies, and system integration and collaborative optimization, the matching effect between variable frequency control and the dynamic response speed of the load can be further improved, thereby achieving efficient and energy-saving operation of the low temperature chiller.