The difference between vector inverter and general-purpose inverter - Schneider

There are two main differences between vector inverters and general-purpose inverters. One is high control accuracy, and the other is high output torque at low speed.

The difference between vector inverter and general-purpose inverter - Schneider

The difference between vector inverter and general-purpose inverter - Schneider

Vector special inverter:

The operating principle of the vector special inverter is to invert after rectification, and get the desired frequency and voltage after inversion.

The vector control technology transforms the three-phase system into an M-T two-phase system through coordinate transformation, and decomposes the stator current vector of the communication motor into two DC weights (i.e., flux weight and torque weight), and then achieves the purpose of controlling the flux and torque of the communication motor respectively, and then achieves the same control function as the DC speed regulation system.

Vector manipulation, also known as velocity manipulation, can literally see some differences.

V/F control method: When driving, the accelerator opening on the foot remains the same, and the speed of the car will definitely change! The car is not going on a flat road, the road resistance is changing, the speed will be slower when going uphill and faster when going downhill. As for the inverter, the frequency setting value of the inverter is equal to the throttle opening on your foot when driving, and the throttle opening is fixed when V/F is controlled.

Vector control method: In the case of changes in road conditions, resistance, uphill, downhill, etc., try to adhere to the speed of the vehicle and improve the speed control accuracy.

Universal inverters:

The frequency converters for all loads are universal frequency converters. However, if there is a special type of inverter, it is recommended to use a special type inverter, which is optimized according to the characteristics of the load, and has the characteristics of simple parameter setting, speed regulation and better energy saving.

Choosing the right drive control system is critical to proper operation. When we select an inverter, it is necessary to fully understand the load characteristics of the inverter drive. In practice, there are three types of machinery: constant moment load, constant power load, blower and pump load.

Constant Moment Load:

Although there is no correlation between load torque TL and speed N, TL insists on a certain or fundamental approach at any speed. For example, conflict loads such as conveyor belts, mixers, extruders, cranes, cranes, etc., are constant moment loads.

When the inverter drags the load of constant moment nature, it is necessary to meet the large torque at low speed and have the ability to meet the overload. If you need to run stably at low speed, you should consider the heat dissipation ability of the standard asynchronous motor to prevent the temperature of the motor from rising too high.

Stable Power Load:

The torque required for the spindle of the machine tool and the coiler and coiler of the rolling mill, paper machine, and plastic film production line is roughly inversely proportional to the rotational speed, which is the so-called constant power load. The stable power nature of the load should be within the scale of a certain speed change. At low speeds, TL cannot increase indefinitely due to the constraints of mechanical strength, so it becomes a constant moment property at low speeds. The constant power of the load and the size of the constant torque zone have a great influence on the choice of the drive scheme. When the motor is regulated by constant magnetic flux, the maximum promised output torque remains unchanged, and when it is attributed to the weak magnetic speed regulation of constant torque speed regulation, the maximum promised output torque is inversely proportional to the speed and attributed to the constant power speed regulation. If the constant torque and constant force speed regulation scale of the motor are consistent with the constant torque and constant force scale of the load, that is, the so-called matching, the capacity of the motor and the capacity of the inverter are the smallest.

Blower, pump load:

In various fans, pumps, and oil pumps, the resistance of air and liquid within a certain velocity scale is proportional to the second power of velocity n with the rotation of the impeller. With the reduction of the rotational speed, the rotational speed is reduced twice the rotational speed. What is required for such a load is that the power is proportional to the speed. However, when the required air volume and flow rate are reduced, the inverter can adjust the air volume and flow rate through speed regulation, which greatly saves electricity. At high speeds, the required power increases too quickly with the rotational speed, and usually must not exceed the operating frequency of the blower and pump load.

With the continuous progress of industrial automation, frequency converters have been widely used. For example, air conditioning loads, crusher loads, large kiln calciner loads, compressor loads, rolling mill loads, converter loads, winch loads, roller loads and so on.

The difference between vector inverter and general-purpose inverter - Schneider

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