System Block Diagram Description

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System detailed description:

As shown in Figure 1-1, the air first passes through the intake valve to the first-stage compressor head, 

and the outlet of the first-stage compressor head has a first-stage pressure sensor and a first-stage temperature sensor. 

After the first-stage compressed gas is separated by water and gas, the gas passes through the radiator for heat dissipation 

and then directly reaches the head of the second-stage compressor, and the water is stored in the lower part of the water-gas separation device. 

When the water cut-off valve of the first-stage machine head is opened, the inside of the first-stage machine head will use negative pressure to fill in water, 

thereby lubricating the first-stage compressor head. When the primary replenishment valve is opened, the system will use negative pressure to replenish water 

from the secondary to the primary. When the primary drain valve is opened, 

the lubricating water from the primary will be discharged to the outside through the drain valve.

The gas compressed in the first stage passes through the radiator and directly reaches the head of the second stage compressor. 

There are two stage pressure sensors and two stage temperature sensors at the outlet of the stage two compressor head. 

There is an unloading valve between the secondary gas and the secondary water-gas separation device. When the unloading valve is opened, 

the gas is directly discharged to the outside. After the two-stage compressed gas is separated from water and gas, the gas is directly output after being dissipated by the radiator. 

The output end can be connected to the gas storage tank, or directly connected to the pneumatic pipeline of the factory. 

Moisture is stored in the lower part of the moisture separator. 

When the water shut-off valve of the secondary machine head is opened, the inside of the secondary machine head will use the negative pressure to fill in the water, 

thereby lubricating the secondary compressor head. When the secondary replenishment valve is opened, the system will replenish the water from the external pump 

to the secondary. 

When the secondary drain valve is opened, the lubricating water of the secondary will be discharged to the outside through the drain valve.

(1) Pressure control:

2.1.1 Description of pressure control process

Pressure control is achieved by adjusting the speed and closing of the intake valve. When the intake valve is open, the higher the speed, the higher the pressure; 

the lower the speed, the lower the pressure. When the intake valve is closed, the pressure decreases regardless of the rpm. 

The pressure is divided into lower limit pressure, upper limit pressure and alarm pressure.

Under normal control conditions, the alarm pressure will generally not be exceeded. When the system is abnormal, such as the intake valve cannot be closed, etc., 

and the alarm pressure is exceeded, the equipment will stop running and a system failure alarm will be issued.

The pressure is regulated by PID closed-loop. When the pressure exceeds the upper limit pressure, the air compressor is unloaded, that is, 

the intake valve is closed, the host inverter enters unloading operation, the PID stops computing, and the system operates at the unloading frequency; 

if the pressure is lower than the lower limit pressure, it automatically Load, the pressure PID recalculation, keep the output pressure constant. 

When the system is unloaded and running, it will start timing. If the pressure is always higher than the lower limit pressure during the unloaded running time, 

the system will enter long-term empty parking. When the pressure is lower than the lower limit pressure and the start-up delay time is obtained, it will automatically run. 

After parking for a long time, it needs to pass the start delay time before restarting.

2.1.2 Detailed description of PID control:

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The pressure control adopts PID closed-loop control, and the given pressure is the expected output pressure set by the operator through the touch screen. 

The feedback pressure is the measured pressure fed back by the pressure sensor, and its output signal range is 4~20mA. In order to control the pressure more accurately and quickly, 

the PID parameters are separately adjusted in 3 stages according to the deviation e. In order to increase the quick response of the system, 

the output upper and lower limits of the PID parameters correspond to the upper and lower limit frequencies of the inverter respectively.

◆ Water supplement function and water change function module:

The water replenishment function has a first-level ultra-low water level, a first-level low water level, a first-level medium water level, 

a first-level high water level, a second-level ultra-low water level, a second-level low water level, and a second-level high water level. 

During operation, if the primary water level is at the low water level, the primary replenishment valve must be opened; 

if the primary water level is at the high water level, the primary drain valve must be opened; if it is at the middle water level, 

both the primary drain valve and the replenishment valve will no action. When the primary water level lasts for a period of time at the ultra-low water level, 

the equipment will fail and shut down after a period of time, and report an ultra-low water level fault. 

The secondary water level control is similar to the primary level, but there is no secondary water level.

The function of water change means that after the machine has been running for a period of time, in order to remove impurities in the lubricating water, 

the machine will change the water at one time according to the set times. When changing the water, start from the stage to change the water. 

The process of changing the water in the stage is to make up the water to the high water level first, then drain the water to the middle water level, 

and then cycle the set number of times. After the first stage water change is completed, the second stage water change is carried out. 

The water change process is similar to that of the first stage.

◆ Maintenance function module:

The system is set with air filter time and water filter time. When the water filter and air filter use time is up, 

the system will give a warning to remind the user to replace the air filter and water filter.

◆ Fault function module:

The system includes fault handling functions such as inverter, water level, temperature, high pressure and emergency stop. 

When the above faults occur, the system will stop immediately and the HMI will display fault information. If the fault cannot be rectified, 

the device cannot be switched on again

※ Compared with other similar products, our company's A90E air compressor dedicated inverter is small in size and occupies less space in the electrical cabinet.

※ Compatible with various permanent magnet synchronous motors used in air compressors, and supports vector control of synchronous motors without speed feedback.

※ Excellent synchronous motor vector algorithm ensures smooth start, no reverse, no vibration.