Generally speaking, after the compressor uses the inverter compressor, it can be called the frequency conversion product, and the fan motor and the water pump also use the frequency conversion product, which can be called the full DC frequency conversion product.

DC inverter compressors and variable frequency drives are essential. The DC inverter compressor is equivalent to a person's heart, and the variable frequency drive is equivalent to the human brain. A variable frequency heat pump device has these two cores to form the most basic frequency conversion function. The inverter compressor provides power and the variable frequency drive provides the correct command. The variable frequency drive supplies the inverter with corresponding current and voltage at each instant of each cycle of different operating frequencies. If the current and voltage given by the variable frequency drive are not accurate, the compressor will run poorly, the efficiency will be reduced, and even the compressor will burn out.

Inverter fans and variable frequency pumps are optional, non-critical components, when using inverter fans and variable frequency pumps can play a icing on the cake.

When the frequency conversion unit is used together with the electronic expansion valve, the energy efficiency brought by the frequency conversion can be truly raised to the highest level. The fixed frequency machine mostly uses the thermal expansion valve, and the effective adjustment range of the thermal expansion valve is generally between 50% and 100%. The temperature control fluctuates greatly under the load of less than 50%, and the electronic expansion valve can be 10 ~100% load zone control can even reach 5%, so if the throttle valve does not use electronic expansion valve, energy efficiency will be greatly affected.

When selecting a variable frequency drive, you cannot directly confirm the number of compressors, but also the maximum electric power and the highest frequency that can be operated. Some customers only ask for the number of horses and the price, but they do not know the number of horses are the same. The actual output power can differ by more than 30%. Insufficient electric power, can not run high frequency, some inverter units can only run about 70HZ, the advantages of frequency conversion are not reflected.

In the design process, attention should be paid to the selection of variable frequency drive. The active PFC of 180 °C is better than the passive PFC. The DC bus voltage is increased. When necessary, the compressor can run at a high frequency and give full play to the large heat of the inverter system. The potential, system efficiency, low noise, and security.

In the design process, we must pay attention to the optimization of the control logic scheme of the unit controller, that is, the optimization design of the control software. For example, the same brain and heart, the effect of an expert and an illiterate person is not the same.

The main control part should also be matched according to the frequency conversion system, and the compressor frequency and fan speed in different working conditions should be adjusted accordingly to achieve the high efficiency, energy saving and safety status of the unit under various working conditions.

There are also some differences in the selection of the four-way valve. In the low-frequency mode, the flow through the four-way valve is very small, and the pressure difference between the high and low pressures is as small as about 1 bar. The four-way valve should be reversed at such a low differential pressure. There must be a certain commutation flow guarantee, but if the leakage of the four-way valve during the commutation process (high and low pressure bypass) is too large, the commutation flow will be insufficient, and the four-way valve slider will be stuck in the middle position. In response to this feature, Sanhua specially designed a special four-way valve for frequency conversion to ensure reliable commutation under low pressure difference.

System matching can not be ignored

Since the application of frequency conversion technology on heat pump units has only just begun in recent years, some end users, including some heat pump manufacturers, have doubts about variable frequency heat pumps. They do not understand the advantages of frequency conversion technology in heat pump applications, and believe that frequency conversion will only increase costs. There are still many manufacturers lacking experience in design and development of variable frequency heat pumps. In fact, the frequency conversion technology has a higher cost performance than the fixed frequency.

Frequency conversion technology is a powerful weapon to solve the problem of insufficient heat and heat efficiency of heat pump heating. At present, the technology of jet boosting can greatly improve the efficiency of the unit in low temperature environment. When the inverter unit runs at high frequency, it can increase the heating capacity by more than 40% under the premise of the same number of horses. If combined with the jet-enhanced compressor, it can increase the heating capacity by 70%-100% and has a higher energy efficiency ratio. . Some manufacturers have proposed that 'non-frequency conversion, no heating' is scientifically based.

In addition, we must pay attention to the matching of the system when designing the product. For the heating unit, we must pay special attention to the performance under low temperature environment, and still meet the heating needs of users in the low temperature environment.