Abstract ▼ AI-Helper

In AC motor drive inverter systems using a single phase power supply, a DC-link capacitor is used as a large capacity electrolytic capacitor. However, the electrolytic capacitor has a high failure rate and short lifetime due to the characteristics of the device, which in turn lowers the reliability ...

In AC motor drive inverter systems using a single phase power supply, a DC-link capacitor is used as a large capacity electrolytic capacitor. However, the electrolytic capacitor has a high failure rate and short lifetime due to the characteristics of the device, which in turn lowers the reliability of the entire drive system. In addition, the harmonics of the input current of the entire system has poor grid power factor because of big constant DC-link voltage. So it is not possible to satisfy the regulation of IEC61000-3-2. In order to solve this problem, an additional circuit such as the PFC(Power Factor Correction) is required, which increases the volume and cost of the drive system.
To solve these problems, the inverter system with a small DC-link capacitance is in research. In this case, a capacitor that has a longer lifetime can be used, and this can reduce the harmonic content of the input current due to be increased non-conduction. For these reasons, it doesn’t need additional circuit which results in reduction of the entire system volume and cost. The input current harmonics issue is solved by capacitor replacement but Only changing the capacitor cannot solve the harmonics of the input current, needed a new control method to suppress the input current harmonics.
This paper proposes a new control method, which eliminates current controller and has only one power controller to control instantaneous active and reactive powers. Here, the instantaneous reactive power has the concept of freedom. The proposed method requires a voltage command, which is generated by the intersection of the instantaneous active and reactive powers. This results a simple control system without a complex current reference of a current controller. Eventually the entire system can be simple.
This control method can be implemented in AC motor, interior permanent magnet synchronous motor and induction motor drives. To verity, computer simulations and experiments are performed to AC motors.