The frequency converter is an important part of the carpenter engraving machine. The common sense of the inverter is briefly introduced below.
The frequency converter is a power control device that converts the power frequency power source into another frequency by using the on-off effect of the power semiconductor device.
The main circuit of the inverter can be roughly divided into two categories: 1 voltage type inverter, this type is to convert the DC of the voltage source into a communication inverter, the DC circuit filter is a capacitor; 2 current type inverter, the type is Convert the DC of the current source into a communication inverter, and its DC loop filter stone inductance.
The inverter is selected for operation. As the motor speeds up and the corresponding frequency and voltage are increased, the starting current is constrained to less than 150% of the rated current (125% to 200% depending on the model). When starting directly with the commercial frequency power supply, the starting current is 6 to 7 times, so mechanical and electrical impact will occur. The inverter drive can be started smoothly (the starting time becomes longer). The starting current is 1.2~1.5 times of the rated current, and the starting torque is 70%~120% of rated torque. For the inverter with active torque boosting function, the starting torque is more than 100%, which can start at full load.
The voltage and current of the inverter are changed in proportion. The torque of the asynchronous motor occurs when the magnetic flux of the motor and the current flowing through the rotor interact. At the rated frequency, if the voltage is constant and only the frequency is decreased, the magnetic flux is too large, and the magnetic circuit is saturated. The motor will be burned. Therefore, the frequency and voltage should be changed in proportion, that is, the frequency of the inverter is manipulated together to control the output voltage of the inverter, so that the magnetic flux of the motor is maintained to prevent the occurrence of weak magnetic and magnetic saturation. This control method is mostly used for energy-saving inverters such as fans and pumps.
