Digital control of isolated Cuk power factor correction converter under wide range of load variation

Abstract

This study presents a novel digital double-loop control method, that is, inner current loop and outer voltage loop, for a single-stage isolated Cuk power factor correction (PFC) converter in continuous conduction mode (CCM). First, control law of current loop, consisting of a current term and a voltage term, is derived. Considering that inductance value of inductors varies with load change, an adaptive gain scheduling method is applied to change the current term. Second, control law of voltage loop is derived based on proportional-integral control with introducing linearisation and feedforward compensation. Meanwhile, a moving average filter is utilised to decrease ripple effect of output voltage, and thus smoother input signal for current loop and fast dynamic response for voltage loop are guaranteed. A 1600 W one-phase isolated Cuk PFC converter controlled by a digital signal processor is developed and achieves power factor higher than 0.99, total harmonic distortion of input current lower than 8.5% with load varying from 25 to 100% and fast dynamic response performance. Finally, a 4800 W three-phase AC-DC converter based on the above PFC converter is implemented and its performance additionally indicate that current sharing issue can be easy to deal with by using the proposed control method.

Bidirectional Quasi-Cuk DC/DC Converter with Reduced Voltage Stress on Capacitor and Capability of Changing the Output Polarity

“…First operating mode: In this operating mode and in the steady-state, 1 S 2 S and 2 D are off, thus, the sum of the currents through 1 L and 2 L flows through the 1 D . Given to the fact that in this operating mode voltage across 1 L is negative and constant, therefore, current through inductor decreases linearly from its maximum value ( …”

“…Given to the fact that in this operating mode voltage across 1 L is negative and constant, therefore, current through inductor decreases linearly from its maximum value ( …”

“…Second operating mode: At 1 τ , first operating mode ends and second operating mode starts. Owing to the fact that the sum of inductors current is negative, thus, 1 D is off and 1 S is on. At the start of the second operating mode, voltage and current of 1 S is zero, thus, this switch turns on with ZVS and zero current switching (ZCS).…”

“…The common types of dc/dc converters are buck, boost, buck-boost, Cuk [1], Sepic [2], and Zeta [3]. In spite of the many applications of the presented conventional converters in [1][2][3], these converters are not suitable for applications that bidirectional power flow management is needed.…”

“…In spite of the many applications of the presented conventional converters in [1][2][3], these converters are not suitable for applications that bidirectional power flow management is needed. A kind of bidirectional topologies is bidirectional Cuk converter.…”