An Improved Voltage Following PFCCukAC/DC Converter

zbz0529

An Improved Voltage Following PFCCukAC/DC Converter [Copy link]

An Improved Voltage Following PFCCukAC/DC Converter

With the development of semiconductor devices and the extensive application of power electronic devices, a large amount of harmonic current has flowed into the power grid, polluting the power grid. This problem has attracted the attention of various countries. In order to limit the total harmonic content (THD) and improve the power factor, many standards have been formulated, such as IEC1000-3-2. In recent years, how to improve the power factor has become a hot topic in the field of power electronics research, and many active PFC circuits have been proposed [1]~[3]. There are two power factor correction schemes. One is to control the input current to make it close to sinusoidal. In this scheme, the circuit works in continuous conduction mode (CCM), which usually requires dual closed-loop control. Due to the sampling of input current, voltage and output voltage, this scheme is relatively complex and costly, which limits the use of this method [4]~[5]. Another scheme is to use the voltage follower method [6]. The circuit usually works in discontinuous conduction mode (DCM), and the switch is controlled by the output voltage error signal. This PFC scheme only requires a voltage control loop. This scheme is relatively simple and has attracted widespread attention from researchers [6]~[8].

This paper analyzes the power factor correction capability of the ordinary Cuk converter working in DCM, and provides a solution to improve its power factor correction capability, while reducing the device stress. In the traditional CukDC/DC converter, there is a dependency between the two inductors, that is, they enter DCM or CCM at the same time. By adding a diode in the circuit, the dependency between them is changed, so that they can work independently in different conduction modes. Therefore, when using the voltage follower method for power factor correction, the output inductor works in CCM, and the input inductor works in DCM, thereby reducing the output voltage ripple and improving the efficiency of the converter.