The working principle of a three-phase inverter is to convert a DC power supply into a three-phase AC power supply. Specifically, it results in a three-phase AC output by dividing the DC power supply into three equal sections and converting them into three AC power sources with a phase difference of 120 degrees using six power switching devices (usually IGBTs or MOSFETs).
In a three-phase inverter, each power switching device is connected between the positive and negative poles of a DC power supply, and the power conversion is achieved by controlling their turn-on and cut-off. Specifically, when the switching device is turned on, the DC power supply provides current to the corresponding AC output through the device; When the switching device is cut off, the current at this output is cut off.
In order to obtain a smooth three-phase AC output, three-phase inverters typically use PWM (Pulse Width Modulation) technology to control the on-on and cut-off times of the switching device. By adjusting the duty cycle of the PWM signal, precise control of the output voltage and current can be achieved.
In addition, the three-phase inverter also needs to carry out closed-loop control of current and voltage to ensure the stability and accuracy of the output. Specifically, the inverter monitors the output current and voltage in real time and compares it with a set reference value. If the actual value deviates from the reference value, the inverter automatically adjusts the on-on and cut-off times of the switching device to bring the output back to the set value.
Both three-phase motors and single-phase motors are a type of electric motors, and their main differences are in terms of power supply mode, structure, performance, and usage scenarios.
First of all, the power supply is different. Three-phase motors need to be powered by a three-phase power supply, while single-phase motors can only be powered by a single-phase power supply. This is one of their most essential differences.
Secondly, they also differ in structure. Three-phase motors usually use a rotating magnetic field generated by a three-phase AC power supply to drive the rotor to rotate, while single-phase motors use the alternating current of a single-phase power supply to generate a one-way rotating magnetic field. Therefore, the structure of a three-phase motor is comparatively more complex, while the structure of a single-phase motor is relatively simple.
In addition, their performance varies. The three-phase motor has the advantages of high power, high speed, low vibration and large starting torque, and is suitable for occasions that require high power and stable operation, such as machine tools, fans, pumps and other equipment in industrial production. Single-phase motors have the advantages of simple structure, small size and light weight, but relatively speaking, their power, efficiency and reliability are slightly inferior to three-phase motors, so they are more suitable for household appliances or light industrial fields with small power needs, such as electric fans, air conditioners, washing machines, etc.
Finally, they are also used in different scenarios. Since three-phase motors require three-phase power supply, they are more widely used in industrial production. Single-phase motors, on the other hand, are more commonly used in small-scale occasions such as homes, schools, and offices.
To sum up, three-phase motors and single-phase motors have their own characteristics and usage scenarios, and they need to be selected according to actual needs. In practical applications, it is necessary to select the most suitable motor type according to the load characteristics, power supply conditions, use environment and other factors.
In short, the three-phase inverter converts the DC power supply into a three-phase AC power supply by controlling the conduction and cut-off time of the power switching device, and ensures the stability and accuracy of the output through closed-loop control. It has a wide range of applications in many fields, such as solar power generation, wind power generation, electric vehicles, etc.