Analysis of High-Power Switched-Capacitor Converter Regulation Based on Charge-Balance Transient-Calculation Method

Abstract

Switched Capacitor (SC) Converters were initially introduced for low power applications and monolithic integration. In recent years, SC converter has found high power applications. However, voltage regulation remains an issue. This paper addresses regulation challenges for high power SC converters, based on Charge-balance Transient-calculation (CT) modeling method and peak current stress estimation. With the help of CT model, due to its accuracy and comprehensive relationship, circuit and control parameters' impacts on regulation become straightforward and concerns on components stresses can be addressed quantitatively. The suitability of CT method for regulation analysis is confirmed by comparison with traditional modeling methods. The CT method is used in a 1kW 3X Two-switch Boosting Switched-capacitor Converter (TBSC) circuit for steady state analysis and current stress estimation. The soft rising input current and nature interleaving properties of 3X TBSC make it well-suited for high power application. Finally, the small signal model of the 3X TBSC is developed and a closed loop operation is achieved under 1kW power rating.Index Terms-CT modeling, switched capacitor, voltage regulation, peak current stress, TBSC I. 0885-8993 (c)

Implementation of One-Cycle Control for Switched Capacitor Converters

“…It is only necessary to consider the charging and discharging operations of the flying capacitor . Based on the charge balance of the flying capacitor [24], the increase in the voltage of during the charging period is equal to the negative voltage drop of during the discharging period, i.e. : ∆ ∆ (1) For State 1 in Fig.2, during the charging period, the instantaneous charging current of the flying capacitors can be expressed as: (2) Where is the input voltage, is the instantaneous voltages of the flying capacitor during the charging operation, and is equivalent resistance in the charging loop, i.e., .…”

An Analytical Approach for Design of a Cross-Connected Fibonacci Switched Capacitor Converter

“…From Equation 4, the output voltage can be approximately rewritten as Equation 5, where V C x,min and V C x,max (x = 1, 2, b) are the minimum and maximum voltages of the capacitors. If this approximation is not conducted, all of the minimum and maximum voltages of the capacitors should be derived such as in the method in [32][33][34].…”

“…The CCFSCC in [26,27] was analyzed based on a four-terminal equivalent circuit model [28], in which the analysis neglects circuit parameters such as its operation frequency and capacitances of capacitors. Some analysis methods consider these parameters, e.g., slow and fast switching limit model [29][30][31] and charge-balance transient method [32][33][34]. In [29][30][31], a target circuit is modeled with an assumption of its 50% duty ratio.…”

“…In addition, this method neglects analysis parameters such as on-resistors of switches and variation in voltages of capacitors. In [32][33][34], an SCC is examined based on the fundamental circuit laws such as Kirchhoff's voltage law (KVL), Kirchhoff's current law (KCL), and RC network solving methods. This analysis method can accurately model the SCCs compared with their simulations.…”

“…This analysis method can accurately model the SCCs compared with their simulations. However, the method in [32][33][34] calls for complex calculations as circuit components increase because all of capacitors' voltages must be derived.…”