Deep well pump is a water lift tool for the motor and water pump to dive into the water, it is suitable for extraction of groundwater from deep wells and also for water extraction projects such as rivers, reservoirs and canals. It is mainly used for the irrigation of farmland and the water used in the mountainous areas of the plateau. It can also be used for drainage in cities, factories, railways, mines and construction sites. Because the deep well pump is the motor and water pump body to dive directly into the water, its safety and reliability will directly affect the use and efficiency of the deep well pump. Therefore, the safe and reliable performance of the deep well pump is also the first choice.

In the underground water source heat pump air conditioning system, the water supply of a deep well pump can meet the requirements of two or more heat pump units. However, in the actual operation, the heat pump unit has been operating at some load for most of the time, and the deep well pump has been running at full load, resulting in a large increase in electricity and water bills.

In recent years, the frequency control technology has been applied more and more widely in air conditioning system with its obvious energy saving effect and reliable control mode, and its technology is relatively mature. But in underground water source heat pump air conditioning system, the application of deep well pump water supply is still very rare, but quite necessary. The pilot survey of underground water source heat pump in Shenyang area has found that in the underground water source heat pump air conditioning system, when the heat pump capacity is small, the water supply of a deep well pump can meet the requirements of two or more heat pump units. In the actual operation, the heat pump unit has been operating at some load for most of the time, and the deep well pump has been running at full load, resulting in a large increase in electricity and water bills. Therefore, the application of variable frequency speed regulating water supply technology in underground water source heat pump system has great energy saving potential.

The deep well pump adopts temperature difference control method. Due to the heat pump unit under the heating conditions, it is necessary to ensure that the evaporator's water temperature cannot be too low, so the temperature sensor is set on the backwater pipe of the deep well pump, setting the temperature as TJH. When the water backwater temperature of the well is greater than the TJH value, the deep well pump controller sends down the current frequency signal to the frequency converter. The inverter reduces the frequency of input power, and the number of pumps of the deep well pump decreases, and the water pump water supply, the shaft power and the input power of the motor are reduced, thus achieving the purpose of energy conservation. When the backwater temperature of water source is lower than the TJH value, the increase frequency is adjusted.