Principle of vector transducer

Vector converter technology is based on dq axis theory. Its basic idea is to decompose the motor current into d-axis current and q-axis current. D-axis current is excitation current and q-axis current is torque current. In this way, the excitation current and torque current of AC motor can be controlled separately, so that AC motor has similar control characteristics as DC motor, It is an ideal control theory designed for AC motor, which greatly improves the control characteristics of AC motor. However, this control theory is not only applied to AC asynchronous motor, but also widely used in BLDC (permanent magnet synchronous motor).

Vector and vector are a method or concept of vector (vector) analysis in mathematics. They are the same concept, but they are called differently. The simple definition refers to the quantity with both size and direction.

Vector is our (mainland) view. Vector is generally used in the literature of Hong Kong and Taiwan. The meaning is roughly the same as that of “Bush” and “Bush”. Vector control is mainly a concept of motor model decoupling.

In the electrical field, it is mainly used to analyze AC power, such as motor analysis, etc. the application in frequency converter is based on the theory of motor analysis, which is called vector control frequency converter. The realization method is not unique, but the mathematical model is basically consistent.

The difference between vector transducer and common transducer

There are two kinds of frequency converters: general frequency converter and vector frequency converter. Although these two kinds of frequency converters can be used, there are still differences between these two kinds of frequency converters. After reading the following analysis, we can see why the price of vector frequency converter is higher than that of general frequency converter.

There are two main differences between vector frequency converter and ordinary frequency converter: one is high control precision, the other is low speed and large output torque. It can output 150% – 200% of the rated torque. Because vector frequency conversion decomposes motor current into d-axis current and q-axis current, where d-axis current is excitation current and q-axis current is torque current. By controlling D and Q separately, the motor can get more starting torque. It is generally used in heavy load starting situation. Such as high-power long belt, and hoist and so on. At this time, the common frequency converter is selected. Because of the heavy load and insufficient output torque, the motor can not be started, and the motor stalling or inverter over-current fault will be reported.

For the control of ordinary water pump, select the fan and water pump special type or general type, there is no need to choose vector, the price is high. The parameter settings are similar. There’s no major difference.

Take driving as an example. As we all know, vector control is also called “speed control”. We can see some differences literally.

V / F control mode: just like when driving, the throttle opening on your foot is kept unchanged, while the speed of the car must be changing! Because the road is uneven and the road resistance is changing, the speed will slow down when going uphill and speed up when going downhill. For the inverter, your frequency setting value is equivalent to the throttle opening of your foot when you drive. The throttle opening is fixed when you control V / F.

Vector control mode: it can control the car to keep the speed as constant as possible under the change of road conditions, resistance, uphill, downhill and other changes, so as to improve the speed control accuracy. Then, in order to keep the speed stable no matter when the uphill, downhill or road resistance changes, the throttle opening must be adjusted at any time.

Editor in charge: yyx

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