Inverter in the application of air conditioning system - Power Circuit - Circuit Diagram

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Industrial Router Crystal 3.2*2.5mm 3225 26M (26.000MHZ) 12PF 10PPM 20PPM 30PPM

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I. Introduction

In the control system without load follow-up regulation characteristics, no matter how the season, day and night and user load change, each air-conditioner motor is fixed at full speed in the power frequency state for a long time, resulting in a huge waste of energy. In recent years, due to the rising price of electricity, the operating cost of central air-conditioning systems has risen sharply, which has led to an increasing proportion of the operating costs of the entire building. The control of power costs has clearly become a concern of business managers. According to statistics, the power consumption of central air conditioners accounts for more than 70% of the total electricity consumption of various buildings. The power consumption of central air-conditioning pumps accounts for about 20% to 40% of the total air-conditioning system power consumption, so when low load is saved. The energy consumed by the compressor system and the water system is of great importance.

The central air conditioning system generally consists of a refrigeration compressor system, a refrigerant (refrigeration and hot and cold) circulating water system, a cooling circulating water system, a coil fan system, and a cooling tower fan system.

HVAC concepts include heating, Ventilation, and Air Condition, and thus have a broader concept than central air conditioning. HVAC is an important environment and guarantee technology that has been formed by the long-term development of the contradiction between people and the environment. The HVAC definition is shown in Figure 1.

Figure 1: HVAC Definition

(1) Heating

1) System components: heat source, heat dissipation equipment, heat transfer pipeline, control components, etc.

2) Technical function: input thermal energy to space, compensate for its heat loss, and reach the indoor temperature requirement.

(2) Ventilation (Ventilation)

1) System components: ventilator, inlet or outlet, purification device, air duct and control components.

2) Technical functions: ventilation and ventilation, heatstroke prevention and cooling, improvement of indoor environment, prevention of internal and external environmental pollution.

(3) Air Conditioning

1) System components: cold and heat source, air outlet equipment and terminal devices, fans, pumps, pipes, tuyères, control components, etc.

2) Technical function: relying on air conditioning medium and controlled environment space that have been comprehensively processed and suitable parameters and good quality for energy and quality

Transfer and exchange to achieve on-demand regulation of indoor air temperature, humidity, speed, cleanliness and other parameters.

3) System classification: one return air, two return air, new wind.

After years of development, the application of HVAC has penetrated into various sectors of the national economy, playing an important role in promoting economic development and improving people's living standards, and sometimes even a key guarantee.

The concept of energy conservation in HVAC is not to reduce energy or reduce energy demand in exchange for energy conservation, but to improve the energy efficiency of buildings through the application of Integrated Resource Planning (IRP) method and Energy Demand Side Management (DSM) technology. Resources and minimal energy consumption costs maximize social and economic efficiency to meet growing environmental needs.

Application of two frequency converters in central air conditioning

At the same time, it has the characteristics of precise control and large energy saving, so it has become the standard control method for central air conditioning systems and HVAC.

The problems to be considered when installing a frequency converter in a central air-conditioning system are completely different from industrial applications. Generally speaking, large-scale electronic sensitive equipment such as computer systems, television receiving systems and telecommunication networks are available in high-end public facilities equipped with central air conditioners. system. This requires special requirements for the variable frequency drive that do not need to be considered in the industrial environment, namely electromagnetic compatibility.

The central air-conditioning green intelligent control system consisting mainly of frequency converters can realize centralized control of various parameters such as temperature, temperature difference, pressure, differential pressure, humidity, flow rate, etc. The comprehensive section of the HVAC system can be realized by automatic energy optimization software. The electric rate is about 50%. At the same time, due to good electromagnetic compatibility, it can reduce interference to peripheral circuit instruments and reduce noise, and its built-in DC reactor can effectively suppress harmonics and improve power factor.

In the central air conditioning system, when the flow rate (air volume) control is performed by the inverter, a large amount of electric energy can be saved. The central air-conditioning system is designed according to the maximum amount of cold demand in the field. The cooling pump and the refrigerating pump are also considered according to the maximum working condition of the single equipment. In actual use, there are more than 90% of the time, the cooling pump The refrigeration pump works under non-full load conditions. If valve and automatic valve adjustment are used, not only will the system throttling loss be increased, but the adjustment will be phased, which will cause the entire air conditioning system to work in a fluctuating state. By installing a frequency converter on the cooling pump and the refrigerating pump, it can be done once and for all. To solve this problem, automatic control can also be realized, and the investment can be recovered through frequency conversion energy saving. At the same time, the soft start function and smooth speed regulation of the inverter can achieve smooth adjustment of the system, stabilize the working state of the system, and prolong the service life of the unit and the network management.