CN116534066A - Variable frequency air conditioner for rubber wheel train - Google Patents

Abstract

The invention provides a variable frequency air conditioner for a rubber-tyred train, which comprises an air conditioning unit, wherein the air conditioning unit is connected with a train body; the air conditioning unit comprises a compressor, a condensing unit, a power supply unit, a PTC heater, an evaporating unit and a control system; the power supply group is configured to supply power to each component; the control system comprises a variable frequency unit which is integrated with a compressor variable frequency output module, a fan speed regulation output module, a PTC electric heating output module and an interaction module; the compressor variable frequency output module is configured to be connected with the compressor and used for controlling the frequency of the compressor; the fan speed regulation output module is configured to be connected with the condensing unit and the evaporating unit so as to control the speeds of the condensing unit and the evaporating unit; the PTC electric heating output module is configured to be connected with the PTC heater to control the on-off of the PTC heater. The three-in-one variable frequency unit is adopted to realize the control of the compressor, the condensing unit and the evaporating unit; the user can adjust the air parameters in the vehicle according to the requirements, thereby creating a sanitary and comfortable environment.

Description

An inverter air conditioner for rubber-tyred trains

technical field

The invention relates to the technical field of air conditioners, in particular to an inverter air conditioner for rubber-tyred trains.

Background technique

At present, my country's rail transit industry is developing rapidly, and many places are preparing to build subways and light rails. However, compared with rubber-tyred trains, it has disadvantages such as high cost and cumbersome approval procedures. Therefore, rubber-tyred trains are a good choice. At present, many vehicle factories in China are planning to develop corresponding vehicles. Compared with subways and light rails, rubber-tyred trains have the following characteristics: (1) The construction cost per kilometer is about 150 million yuan, which is about 1/5 of the subway construction cost (2) The entire project period is about 1-2 years, and the subway is 3-5 years; (3) The overall operating cost is about 1/3-1/2 of other rail transit; (4) It is easy to disassemble and move after the line is completed , while subways and light rails are generally difficult to divert; (5) high degree of automation, high positioning accuracy for entering and exiting stations; (6) less operating noise and pollution, less environmental interference, and strong ride comfort.

Rubber-tyred trains run on regular roads in the form of tires, reducing the investment in infrastructure facilities. It is a very flexible means of transportation. The fixed-frequency air conditioner design with high energy consumption and heavy weight in the early stage can no longer meet the high requirements of customers. Therefore, it is necessary to develop inverter air-conditioning units with superior performance and good reliability, which integrates the advantages of rail transit and bus air-conditioning, and realizes energy saving and emission reduction in the transportation field, which is a major problem that needs to be solved urgently. The frequency conversion lightweight air conditioner is one of the important means to solve this problem, and the industrialization of this project can also promote the technological progress and development of the industry.

Therefore, in view of the problems existing in the prior art, it is particularly important to provide an inverter air-conditioning technology with simple structure and good performance for rubber-tyred trains.

Contents of the invention

The purpose of the present invention is to provide a frequency conversion air conditioner for rubber-tired trains, which uses a three-in-one frequency conversion unit to realize the control of the compressor, condensation unit, and evaporation unit; the user can adjust the air parameters in the car according to the needs , Create a hygienic and comfortable environment in the car.

In order to achieve the above object, the present invention adopts the following technical solutions:

A frequency conversion air conditioner for rubber-tyred trains, comprising an air-conditioning unit fixedly connected to the vehicle body; the air-conditioning unit includes a compressor, a condensing unit, a power pack, a PTC heater, an evaporation unit and a control system; The power pack is configured to supply power to the components;

The control system is configured to receive signals from an external network or external equipment, and perform data interaction; the control system includes a frequency conversion unit; the frequency conversion unit integrates a compressor frequency conversion output module, a fan speed control output module, a PTC electric heating output module and interactive module;

The compressor frequency conversion output module is configured to be connected to the compressor to control the frequency of the compressor; the fan speed regulation output module is configured to be connected to the condensing unit and the evaporating unit to control the speed of the condensing unit and the evaporating unit; The PTC electric heating output module is configured to be connected to the PTC heater to control the on-off of the PTC heater;

The interactive module includes an analog input circuit, a CAN interface communication circuit, a digital input circuit, a digital output circuit and an operation panel; the analog input circuit is configured to be connected to a low-voltage sensor and a high-voltage sensor, and the CAN interface communication circuit It is configured to be connected with the control unit of the car body for data interaction; the digital input circuit is configured to be connected to a compressor, a condensing unit, a PTC heater, and an evaporating unit, and is used to obtain The data of the unit; the digital output circuit is configured to be connected to the fresh air valve and the four-way reversing valve; the operation panel is configured to be connected to the input port of the CAN interface communication circuit.

The structure of the air-conditioning unit is set as a roof unit type, and is installed on the top of the vehicle body.

Specifically, in the above technical solution, the air-conditioning unit adopts an integrated structure, which makes the equipment layout simple, easy to install, and safe to operate. And the power distribution is simple, and the electrical connection with the car body is only 3 aviation plugs, which saves wiring costs and vehicle space. The frequency conversion unit adopts a three-in-one frequency converter, which is installed in the air-conditioning unit and powered by DC 600V. It is connected to the vehicle control unit in the driver's cab through the CAN interface communication circuit, and receives commands from the driver's cab panel to control the air conditioner. Load operation to achieve the purpose of temperature regulation. Wherein, the frequency conversion unit is connected with the compressor to control the frequency of the compressor. The frequency conversion unit controls the speed of the ventilator and condensing fan. When the frequency conversion unit is in the heating working condition, it can drive the action of the four-way reversing valve, so that the air conditioning unit works in the heat pump working condition, and also has the function of defrosting. When the fresh air is greater than 5 degrees, the PTC heater and compressor are allowed to be turned on at the same time.

Specifically, the frequency conversion unit integrates a compressor, a controller and a fan power supply, and has a CAN communication function. The air conditioning unit is controlled by an all-in-one frequency conversion unit, which can realize automatic control of ventilation, cooling and heating. The control system is connected with the external MVB network and hard-wired signals, the controller receives the signal from the passenger room, and also feeds back the status to the passenger room. The fresh air enters the unit from the side of the unit through the steam-water separator and the fresh air duct, and the fresh air and return air are mixed in front of the evaporator. The unit adopts a mechanical and electrical integration design, which can automatically adjust the frequency state according to the needs of the passenger room, realize the adjustment of cooling capacity, and ensure the best cooling capacity output of the air conditioning unit under any working conditions.

Specifically, the structural type of the air-conditioning unit is a roof unit type, which is installed on the roof of the vehicle. The unit supplies air from the front and rear sides of the bottom of the box, returns air from the bottom left and right, and fresh air is introduced from both sides of the box. The air supplied by the air-conditioning unit is evenly introduced into the car through the upper air duct of the passenger car, and the electrical control system matched with the air-conditioning unit is integrated in the air-conditioning unit.

Specifically, the refrigeration circuit of the air-conditioning unit is composed of compressors, condensers, expansion valves, evaporators and other main components, which are brazed and connected by copper tubes to form a closed refrigeration system. When the air conditioner unit is cooling, in the refrigeration circuit, the compressor compresses the low-temperature and low-pressure gaseous refrigerant into high-temperature and high-pressure superheated gas into the condenser, and the external air and the condenser are forced to exchange heat through the condensing fan to condense into liquid. The liquid in the condenser enters the evaporator through the throttling and reducing pressure of the expansion valve, and the mixed air composed of the passenger room and the outside fresh air is forced to exchange heat with the heat exchanger through the fan, and the liquid in the evaporator evaporates into a low-pressure gas, and then Inhaled by the compressor to complete a refrigeration cycle. The compressor works continuously to achieve the effect of continuous refrigeration. The air in the car is inhaled by the ventilator from the air return port and mixed with the fresh air, then passes through the evaporator to dehumidify and cool down, and is blown out from the air outlet to provide cooling capacity to the car. It automatically controls the temperature inside the car, and the temperature inside the car can be adjusted within the set temperature range. When the air conditioner unit is heating, the superheated gaseous refrigerant discharged from the compressor enters the indoor heat exchanger through the four-way valve. The circulating air heated by the heater is sent to the car); through the throttling of the electronic expansion valve, the liquid refrigerant enters the outdoor heat exchanger to evaporate and absorb heat, and becomes a low-temperature and low-pressure gaseous refrigerant and returns to the compressor to complete the heating process.

As mentioned above, the frequency conversion unit is configured to receive the pressure switch signal and adjust the frequency of the compressor, so as to protect the compressor.

Specifically, the frequency conversion unit receives the signal of the pressure switch, thereby protecting the compressor.

As mentioned above, the frequency conversion unit is configured to receive the temperature sensor signal to realize the control of the air conditioner state.

As above, the condensing units are connected in parallel.

Specifically, the use of parallel condensing units greatly improves the utilization rate of condensing units (ie, condensers, etc.), and the condensing temperature at half-load is lower than that of conventional designs, thereby improving the energy efficiency ratio of air-conditioning units.

As above, the compressor is a horizontal scroll variable frequency compressor.

Specifically, the compressor adopts a mature and stable horizontal scroll inverter compressor with low noise, high efficiency and good reliability. Due to the use of frequency conversion compressors, the cooling capacity can be adjusted in a large range and has energy-saving effects. Its heating is in the form of a heat pump, which switches the functions of the indoor and outdoor heat exchangers in winter, saving conventional electric heating, and has the advantages of environmental protection, energy saving and emission reduction.

As mentioned above, the air conditioner unit includes a box, and the compressor, condensing unit, power pack, PTC heater, and evaporation unit are arranged in the box; the front and rear sides of the bottom of the box are provided with air outlets, and the left and right sides There is a return air outlet.

Specifically, the air conditioning unit adopts the mechanical structure of bottom air supply and bottom return air, and the box body is made of aluminum alloy; the box body structure is fixed by welding and riveting, and a large number of riveting is used to simplify sheet metal processing and assembly to achieve light weight design.

As above, the air conditioning unit is also provided with a heat exchanger.

Preferably, the heat exchanger adopts a copper tube coil with a diameter of 7 mm and a small pitch.

Specifically, a small-diameter heat exchanger is used to replace the conventionally used 9.52mm diameter and standard pitch copper tube coil, which has the advantage of heat transfer coefficient and weight reduction; the heat exchanger adopts supercooling technology, and the heat transfer capacity is improved About 3-5%.

As mentioned above, the air conditioner shock absorber connected with the box body is provided on the peripheral side of the box body, and the installation place of the air conditioner shock absorber is made of rubber.

As above, the box is provided with an upper chamber and a lower chamber; wherein, the compressor and the condensing unit are arranged in the upper chamber; the power pack, the PTC heater, and the evaporation unit are arranged in the lower chamber, and the lower chamber The inner walls on both sides of the body are also provided with a mixed air filter and an electric air valve.

As mentioned above, the condensing unit includes a condenser and a condensing fan; the evaporating unit includes an evaporator and an evaporating fan.

As mentioned above, the outer wall of the box body is also provided with a fresh air filter and a steam-water separator.

In the above, the frequency conversion unit is a frequency converter, and its power supply is 600V DC.

As mentioned above, the frequency converter controls the operating speeds of the condensing unit and the evaporating unit through pulse width modulation.

As mentioned above, the frequency conversion unit is configured to drive the PTC heater and the compressor to start synchronously when the fresh air is higher than the preset temperature.

Beneficial effects of the present invention:

The invention provides a frequency conversion air conditioner for rubber-tyred trains, which adopts a three-in-one frequency conversion unit to realize the control of a compressor, a condensation unit, and an evaporation unit; Create a hygienic and comfortable environment inside the car. Its air-conditioning unit has the characteristics of safe and reliable performance, easy repair and maintenance; and adopts the structural design of mechanical and electrical integration, and the heat pump unit has the advantages of energy saving, comfort and environmental protection. In addition, the air conditioner unit uses an environmentally friendly refrigerant, which has the advantages of light weight, vibration resistance, and impact resistance.

Description of drawings

Fig. 1 is the principle diagram of refrigeration and heating of the frequency conversion air conditioner provided by the present invention;

Fig. 2 is the circuit schematic diagram of the frequency converter of the air conditioning unit of the frequency conversion air conditioner provided by the present invention;

Fig. 3 is the circuit connection schematic diagram of the frequency converter of the air conditioning unit of the frequency conversion air conditioner provided by the present invention;

Fig. 4 is a schematic diagram of the interaction module of the frequency converter of the air conditioning unit of the frequency conversion air conditioner provided by the present invention;

Fig. 5 is a schematic diagram of the circuit connection of the interactive module of the frequency converter of the air conditioning unit of the frequency conversion air conditioner provided by the present invention;

Fig. 6 is a schematic diagram of the box structure of the air conditioner unit of the inverter air conditioner provided by the present invention;

Fig. 7 is a schematic diagram of the internal structure of the box body of the air conditioner unit of the inverter air conditioner provided by the present invention.

Explanation of reference signs

1 Compressor, 2 Power pack, 3 PTC heater, 4 Condenser, 5 Condensing fan, 6 Evaporator, 7 Evaporating fan, 8 Inverter, 9 Hybrid air filter, 10 Electric air valve, 11 Fresh air filter, 12 Soda water Separator, 13 air conditioner shock absorber, 14 main circuit connector, 15 control connector, 16 network connector.

Detailed ways

The specific embodiments of the present invention will be further described below in conjunction with the accompanying drawings.

As shown in Figures 1 to 7, this embodiment provides an inverter air conditioner for rubber-tyred trains, including an air conditioning unit fixedly connected to the car body; the air conditioning unit includes a compressor 1, a condensing unit, A power supply group 2, a PTC heater 3, an evaporation unit, and a control system; the power supply group 2 is configured to supply power to each component;

In this embodiment, the condensing unit includes a condenser 4 and a condensing fan 5 ; the evaporating unit includes an evaporator 6 and an evaporating fan 7 .

The control system is configured to receive signals from an external network or external equipment, and perform data interaction; the control system includes a frequency converter 8; the frequency converter 8 is integrated with a compressor frequency conversion output module, a fan speed regulation output module, and a PTC electric heating output modules and interactive modules;

The compressor frequency conversion output module is configured to be connected to the compressor 1 for controlling the frequency of the compressor 1; the fan speed regulation output module is configured to be connected to the condensing unit and the evaporating unit to control the speed of the condensing unit and the evaporating unit ; The PTC electric heating output module is configured to be connected to the PTC heater 3 to control the on-off of the PTC heater 3;

The interactive module includes an analog input circuit, a CAN interface communication circuit, a digital input circuit, a digital output circuit and an operation panel; the analog input circuit is configured to be connected to a low-voltage sensor and a high-voltage sensor, and the CAN interface communication circuit It is configured to be connected with the control unit of the car body for data interaction; the digital input circuit is configured to be connected to the compressor 1, the condensing unit, the PTC heater 3, and the evaporation unit, and is used to obtain the compressor 1, the condensing unit, and the PTC heating 3, the data of the evaporation unit; the digital output circuit is configured to be connected to the fresh air valve and the four-way reversing valve; the operation panel is configured to be connected to the input port of the CAN interface communication circuit.

The structure of the air-conditioning unit is set as a roof unit type, and is installed on the top of the vehicle body.

Specifically, in the above technical solution, the air-conditioning unit adopts an integrated structure, which makes the equipment layout simple, easy to install, and safe to operate. And the power distribution is simple, and the electrical connection with the car body is only 3 aviation plugs, which saves wiring costs and vehicle space. The frequency converter 8 adopts a three-in-one frequency converter. The frequency converter 8 is installed in the air-conditioning unit and powered by DC 600V. Control the load operation of the air conditioner to achieve the purpose of adjusting the temperature. Wherein, the frequency converter 8 is connected with the compressor 1 to control the frequency of the compressor 1 . The frequency converter 8 controls the speed of the ventilator and the condensation fan 5 . When the frequency converter 8 is in the heating working condition, it can drive the action of the four-way reversing valve, so that the air conditioning unit works in the heat pump working condition, and also has the function of defrosting. When the fresh air is greater than 5 degrees, the PTC heater 3 and the compressor 1 are allowed to be turned on simultaneously.

Specifically, the frequency converter 8 integrates the compressor 1, the controller and the fan power supply, and has a CAN communication function. The air conditioning unit is controlled by an all-in-one frequency converter 8, which can realize automatic control of ventilation, cooling and heating. The control system is connected with the external MVB network and hard-wired signals, the controller receives the signal from the passenger room, and also feeds back the status to the passenger room. The fresh air enters the unit from the side end of the unit through the steam-water separator and the fresh air duct, and the fresh air and return air are mixed in front of the evaporator 6 . The unit adopts a mechanical and electrical integration design, which can automatically adjust the frequency state according to the needs of the passenger room, realize the adjustment of cooling capacity, and ensure the best cooling capacity output of the air conditioning unit under any working conditions. The structural type of the air conditioning unit is the roof unit type, which is installed on the roof of the vehicle. The unit supplies air from the front and rear sides of the bottom of the box, returns air from the bottom left and right, and fresh air is introduced from both sides of the box. The air supplied by the air-conditioning unit is evenly introduced into the car through the upper air duct of the passenger car, and the electrical control system matched with the air-conditioning unit is integrated in the air-conditioning unit.

Specifically, the refrigeration circuit of the air-conditioning unit is composed of compressor 1, condenser 4, expansion valve, evaporator 6 and other main components, which are brazed and connected by copper tubes to form a closed refrigeration system. When the air conditioner unit is cooling, in the refrigeration circuit, the compressor 1 compresses the low-temperature and low-pressure gaseous refrigerant into high-temperature and high-pressure superheated gas and enters the condenser 4, and the external air and the condenser 4 are forced to exchange heat through the condensing fan 5, and condensed into liquid. The liquid in the condenser 4 enters the evaporator 6 through throttling and reducing the pressure through the expansion valve, and the mixed air composed of the passenger room and the outside fresh air is forced to exchange heat with the heat exchanger through the fan, and the liquid in the evaporator 6 evaporates into a low pressure The gas is then sucked by compressor 1 to complete a refrigeration cycle. The compressor 1 works continuously to achieve the effect of continuous refrigeration. The air in the car is sucked in by the ventilator from the air return port and mixed with the fresh air, then passes through the evaporator 6 to dehumidify and cool down, and is blown out from the air outlet to provide cooling capacity to the car. The unit itself automatically controls the temperature inside the vehicle, and the temperature inside the vehicle can be adjusted within the set temperature range. When the air conditioner unit is heating, the superheated gaseous refrigerant discharged from compressor 1 enters the indoor heat exchanger through the four-way valve. In the indoor heat exchanger, the indoor side fan is used to cool down, and the supercooled liquid refrigerant flows out (the indoor side fan will pass through the indoor side fan). The circulating air heated by the heat exchanger is sent to the car); through the throttling of the electronic expansion valve, the liquid refrigerant enters the outdoor heat exchanger to evaporate and absorb heat, and becomes a low-temperature and low-pressure gaseous refrigerant and returns to the compressor 1 to complete the heating process.

In this embodiment, the frequency converter 8 is configured to receive a pressure switch signal and adjust the frequency of the compressor 1 so as to protect the compressor 1 . The frequency converter 8 is configured to receive the temperature sensor signal to realize the control of the air conditioner state.

In this embodiment, the condensing units are connected in parallel. The use of parallel condensing units greatly improves the utilization rate of the condensing units (that is, condenser 4, etc.), and the condensing temperature at half-load is lower than that of conventional designs, thereby improving the energy efficiency ratio of the air conditioning unit.

In this embodiment, the compressor 1 is a horizontal scroll variable frequency compressor 1 . The compressor 1 adopts a mature and stable horizontal scroll variable frequency compressor 1 with low noise, high efficiency and good reliability. Due to the use of the frequency conversion compressor 1, the cooling capacity can be adjusted in a large range and has an energy-saving effect. Its heating is in the form of a heat pump, which switches the functions of the indoor and outdoor heat exchangers in winter, saving conventional electric heating, and has the advantages of environmental protection, energy saving and emission reduction.

In this embodiment, the air conditioner unit includes a box, and the compressor 1, the condensing unit, the power pack 2, the PTC heater 3, and the evaporation unit are arranged in the box; the front and rear sides of the bottom of the box are provided with There is an air supply port and a return air port on the left and right sides. The air conditioning unit adopts the mechanical structure of bottom air supply and bottom return air, and the box is made of aluminum alloy; the box structure is fixed by welding and riveting, and a large number of riveting is used to simplify sheet metal processing and assembly, and realize lightweight design.

In this embodiment, the air conditioning unit is further provided with a heat exchanger. The heat exchanger adopts a copper tube coil with a diameter of 7mm and a small pitch. Using a heat exchanger with a small diameter to replace the conventional copper tube coil with a diameter of 9.52mm and a standard pitch has the advantage of heat transfer coefficient and weight reduction; the heat exchanger adopts supercooling technology, and the heat transfer capacity is increased by about 3- 5%.

In this embodiment, an air-conditioning shock absorber 13 connected with the box is provided on the peripheral side of the box, and the installation place of the air-conditioning shock absorber 13 is made of rubber.

In this embodiment, a main circuit connector 14 , a control connector 15 and a network connector 16 are also provided on the peripheral side of the box.

In this embodiment, the box is provided with an upper chamber and a lower chamber; wherein, the compressor 1 and the condensing unit are arranged in the upper chamber; the power pack 2, the PTC heater 3, and the evaporation unit are arranged in the lower chamber. Inside the cavity, and the inner walls on both sides of the lower cavity are also provided with a mixing air filter 9 and an electric air valve 10 . A fresh air filter 11 and a steam-water separator 12 are also arranged on the outer wall of the box body.

In this embodiment, the frequency converter 8 controls the operating speeds of the condensing unit and the evaporating unit through pulse width modulation.

In this embodiment, the frequency converter 8 is configured to drive the PTC heater 3 and the compressor 1 to start synchronously when the fresh air is higher than a preset temperature.

According to the disclosure and teaching of the above-mentioned specification, those skilled in the art to which the present invention belongs can also make changes and modifications to the above-mentioned embodiment. Therefore, the present invention is not limited to the specific embodiments disclosed and described above, and some modifications and changes to the invention should also fall within the protection scope of the claims of the present invention. In addition, although some specific terms are used in this specification, these terms are only for convenience of description and do not constitute any limitation to the present invention.

Claims (10)

1. A frequency conversion air conditioner for rubber-tyred trains, comprising an air-conditioning unit, characterized in that, the air-conditioning unit is fixedly connected with the car body; the air-conditioning unit includes a compressor, a condensation unit, a power pack, a PTC heater, an evaporation a unit and a control system; the power pack is configured to supply power to each component; The control system is configured to receive signals from an external network or external equipment, and perform data interaction; the control system includes a frequency conversion unit; the frequency conversion unit integrates a compressor frequency conversion output module, a fan speed control output module, a PTC electric heating output module and interactive module; The compressor frequency conversion output module is configured to be connected to the compressor to control the frequency of the compressor; the fan speed regulation output module is configured to be connected to the condensing unit and the evaporating unit to control the speed of the condensing unit and the evaporating unit; The PTC electric heating output module is configured to be connected to the PTC heater to control the on-off of the PTC heater; The interactive module includes an analog input circuit, a CAN interface communication circuit, a digital input circuit, a digital output circuit and an operation panel; the analog input circuit is configured to be connected to a low-voltage sensor and a high-voltage sensor, and the CAN interface communication circuit It is configured to be connected with the control unit of the car body for data interaction; the digital input circuit is configured to be connected to a compressor, a condensing unit, a PTC heater, and an evaporating unit, and is used to obtain The data of the unit; the digital output circuit is configured to be connected to the fresh air valve and the four-way reversing valve; the operation panel is configured to be connected to the input port of the CAN interface communication circuit. 2. The frequency conversion air conditioner according to claim 1, characterized in that, the structure of the air conditioner unit is configured as a roof unit and installed on the top of the vehicle body. 3. The frequency conversion air conditioner according to claim 1, characterized in that, the air conditioner unit comprises a casing, and the compressor, condensing unit, power pack, PTC heater, and evaporation unit are arranged in the casing; the casing There are air supply outlets on the front and rear sides of the bottom, and air return outlets on the left and right sides. 4. The frequency conversion air conditioner according to claim 3, characterized in that an air conditioner shock absorber connected with the box is provided on the peripheral side of the box, and the installation place of the air conditioner shock absorber is made of rubber. 5. The frequency conversion air conditioner according to claim 3, wherein an upper chamber and a lower chamber are arranged in the box; wherein, the compressor and the condensing unit are arranged in the upper chamber; the power pack and the PTC heating The device and the evaporating unit are arranged in the lower cavity, and the inner walls on both sides of the lower cavity are also equipped with a mixing air filter and an electric air valve. 6. The inverter air conditioner according to claim 1, wherein the condensing unit includes a condenser and a condensing fan; the evaporating unit includes an evaporator and an evaporating fan. 7. The inverter air conditioner according to claim 3, characterized in that, a fresh air filter and a steam-water separator are also provided on the outer wall of the box. 8. The frequency conversion air conditioner according to claim 1, wherein the frequency conversion unit is a frequency converter, and its power supply is 600V DC. 9. The frequency conversion air conditioner according to claim 8, wherein the frequency converter controls the operating speeds of the condensing unit and the evaporating unit through pulse width modulation. 10. The inverter air conditioner according to claim 1, wherein the inverter unit is configured to drive the PTC heater and the compressor to start synchronously when the fresh air is greater than a preset temperature.