Abstract
In this paper, a linearized discrete charge balance (LDCB) control strategy is proposed for buck converter operating in discontinuous conduction mode (DCM). For DC-DC power converters, discrete charge balance (DCB) control is an attractive approach to improve the output voltage transient response. However, as a non-linear control strategy, the algorithm is complex, which is difficult for implementation. To reduce the complexity, this paper proposes the LDCB control strategy that is derived through linearizing conventional DCB controller. By deriving the differential functions of the DCB control algorithm, the small signal relationship between the input and output of DCB controller is explored. Furthermore, based on the relationship, the LDCB controller is formed through three parallel feed loops to the duty ratio. As a linear control approach, the achieved LDCB controller is greatly simplified for implementation. This not only saves the hardware cost, but also reduces the calculation lag, which provides potential to improve the switching frequency. Besides, since the LDCB controller shares the same small signal model as that of DCB controller, it achieves similar control loop bandwidth and transient performance. Effectiveness of the proposed LDCB control is verified by zero/pole plots, transient analyses and experimental results.
Highlights
In portable and processor applications, there is a continuous demand for a fast output voltage transient response
All results prove that linearized discrete charge balance (LDCB) control is capable to maintain the transient performance with inductance deviation of ± 20%, which is an adequate margin for most inductors
This paper presents a LDCB control strategy for discontinuous conduction mode (DCM) buck converter
Summary
In portable and processor applications, there is a continuous demand for a fast output voltage transient response. Various methods are proposed to carry out the control with digital circuits [23,24,25,26] These control strategies induce a variable switching frequency, which challenges the converter modeling and EMI suppression [27,28]. Since the relationship between the input and output is explicitly revealed, all loops can be carried out in parallel Both the simplified algorithm and the parallelism help to save the hardware cost, reduce the calculation lag, and provide potential to improve the switching frequency. Since the LDCB controller shares the same small signal model as that of DCB controller, it achieves similar control loop bandwidth and transient performance.
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