This paper examines the practical design issues of sliding-mode (SM) controllers as applied to the control of dc-dc converters. A comprehensive review of the relevant literature is first provided. Major problems that prevent the use of SM control in dc-dc converters for industrial and commercial applications are investigated. Possible solutions are derived, and practical design procedures are outlined. The performance of SM control is compared with that of conventional linear control in terms of transient characteristics. It has been shown that the use of SM control can lead to an improved robustness in providing consistent transient responses over a wide range of operating conditions.

The electrolytic capacitor is the key component that limits the operating lifetime of LED drivers. If an ac-dc LED driver with power factor correction (PFC) control is allowed to output a pulsating current for driving the LEDs, the electrolytic capacitor will no longer be required. However, this pulsating current will introduce light flicker that varies at twice the power line frequency. In this paper, a configuration of flicker-free electrolytic capacitor-less single-phase ac-dc driver for LED lighting is proposed. The configuration comprises an electrolytic capacitor-less PFC converter and a bidirectional converter, which serves to absorb the ac component of the pulsating current of the PFC converter, leaving only a dc component to drive the LEDs. The output filter capacitor of the bidirectional converter is intentionally designed to have a large voltage ripple, thus its capacitance can be greatly reduced. Consequently, film capacitors can be used instead of electrolytic capacitors, leading to the realization of a flicker-free ac-dc LED driver that has a long lifetime. The proposed solution is generally applicable to all single-phase PFC converters. A prototype with 48-V, 0.7-A output is constructed and tested. Experimental results are presented to verify the effectiveness of the flick-free electrolytic capacitor-less ac-dc LED driver.

This paper presents a simple and systematic approach to the design of a practical sliding mode voltage controller for buck converters operating in continuous conduction mode. Various aspects of the design, including the associated practical problems and the proposed solutions, are detailed. A simple and easy-to-follow design procedure is also described. Experimental results are presented to illustrate the design procedure.

This paper presents a simple unified approach to the design of fixed-frequency pulsewidth-modulation-based sliding-mode controllers for dc-dc converters operating in the continuous conduction mode. The design methodology is illustrated on the three primary dc-dc converters: buck, boost, and buck-boost converters. To illustrate the feasibility of the scheme, an experimental prototype of the derived boost controller/converter system is developed. Several tests are performed to validate the functionalities of the system

This paper discusses the basic family of three-level (TL) dc-dc converters. The origin of TL converters and their basic topological variations are described. Systematic procedures leading to improved and simplified circuit topologies are discussed. A feedforward control scheme that ensures the proper functioning of these converters is proposed. Moreover, the virtues and drawbacks of these converters as compared to conventional converters are highlighted. In particular, the advantages of TL converters include reduced voltage stress of the switches, reduced filter size, and improved dynamic response. It is shown that TL converters are highly suitable for high input/output voltage and medium-to-high-power dc-dc power conversions.

This paper provides a general analysis on the steady-state behavior and control principles of a recently proposed concept of “electric springs” that can be integrated into electrical appliances to become a new generation of smart loads. The discussion here is focused on how different real and/or reactive load powers can be canceled or altered using the electric springs. Mathematical derivations supporting the theoretical framework of the concept are detailed in the paper. Experimental results validate the theoretical discussions and solutions proposed. It is demonstrated that the electric spring is capable of providing different types of power/voltage compensations to the load and the source.