Variable frequency drive system and motor thereof

Abstract

The invention relates to a variable frequency driving system, where the power supply of a power grid is converted into the variable frequency power supply so as to drive a three-phase motor; the converted variable frequency power supply is a two-phase power supply which has a public end, time lag of 1 / 6 period and the same amplitudes; the two-phase power supply is connected with a three-phase terminal of the three-phase motor in the following way: the public end is connected with a phase terminal and two output terminals of the two-phase power supply are connected with another two phase terminals of the motor; and the three-phase motor has such three-phase impedance: the two-phase impedance of the two output terminals which are connected with the two-phase power supply is equal and higher than the one-phase impedance which is connected with the public end. The impedance of the two output terminals of the two-phase power supply which is connected with motor is as 1.5 times to 4.5 times as the one-phase impedance which is connected with the public end. The design can achieve the effect of improving the asymmetry of the system, thus improving the efficiency and reducing the noise of the vibration.

Description

technical field [0001] The invention relates to a variable frequency drive system and its motor. In the International Patent Classification Table, the functional classification can belong to H02P7 / 00. Background technique [0002] The three-phase inverter drive three-phase motor system has been widely used in industrial equipment, but it is used for electric appliances powered by single-phase power supply with relatively small power. The inverter circuit appears to have too many units and insufficient component capacity. Complicated circuits have also become the weak link of the system. Usually, it is necessary to select better unit components or set up more complex protection circuits and control programs, and even use relatively expensive intelligent power modules (IPM) and 16-bit single-chip microcomputers, etc., which obviously affect the cost. . For this reason, the designer of the present invention proposes to drive a two-phase motor or a three-phase motor with a two-...

AI Technical Summary

Problems solved by technology

[0002] The three-phase inverter drive three-phase motor system has been widely used in industrial equipment, but it is used for electric appliances powered by single-phase power supply with relatively small power. The inverter circuit appears to have too many units and insufficient component capacity.

But when the actual circuit is running, the test result of the effective value of the voltage on the three input terminals of the motor is that the voltage U of the two-phase inverter output terminals A and B to the common terminal C CA and U CB Roughly equal, but lower than the fundamental voltage U between the two output terminals AB Small; the test result of the effective value of the current entering the three input terminals of the motor is that the output current I of the two-phase inverter output terminals (controlled terminals) A and B A and I B Roughly equal, but higher than the current I of the common terminal (non-controlled terminal) sub-C C The ratio is larger, which means that it is still undersymmetrical, which has an impact on efficiency and vibration and noise levels

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