Pulse-width modulated (PWM) DC/DC power converters operating at a high switching frequency are a class of systems having cyclically varying structures. Such systems are inherently nonlinear as the control function involves varying the relative durations of the constituent structures [1]. Existing design practice employs predominantly voltage mode and current-mode control strategies that are based on linear small-signal techniques, and the resulting performances in terms of output regulation, transient response, and stability are therefore adequate only if the converters operate within a narrow range of parameter variation [2]. For applications involving power sources and loads that are nonlinear and more widely varied, the use of linear controllers is expected to produce sub-optimal control performances and may even fail to meet the desired specifications when the condition of operation deviates significantly from the usual small-signal condition [3]. Sliding mode (SM) control is a nonlinear control method that is particularly well suited for DC/DC power converters working with power sources and loads that vary widely and nonlinearly [4], [5]. The inherent operation of SM control is a natural strategy for controlling systems having a discontinuous switching characteristic. When applied to DC/DC power converters, highly robust and versatile SM systems that give fast and consistently stable control performance will be resulted [6], [7]. Furthermore, among all available nonlinear control techniques, the SM control is arguably by far most practical for power converters, due to its simple implementation, ease of design, and low cost. In particular, fixed-frequency PWM-based SM controllers, which are quasisliding mode (QSM) controllers that work with close operational resemblance to ideal SM controllers but without the complexity of using variable switching frequency, are found to be most suited for practical applications [7]. Specifically, operating power converters at a constant frequency achieves simpler filter design and keeps the power converter size small. Furthermore, fixed-frequency PWM-based SM controllers can be easily implemented in either digital form by using low-end inexpensive microcontrollers (MCU), digital signal processors (DSP) or field-programmable gate arrays (FPGA), or in analogue form using a few simple discrete components. Nevertheless, the implementation of SM control in analogue form does present a few advantages over the digital form in terms of its ability to achieve a faster transient response especially for converters switch at very high frequency and the absence of issues related to discretization. For commercial applications, the PWM-based SM controllers can be fabricated as analogue integrated circuit (IC) controller chips at a very competitive cost relative to existing PWM controllers. We will begin this chapter with a brief account of the principle of SM control and PWM-based SM control for the DC/DC converters. The key idea of connecting the duty ratio control in conventional PWM control with an equivalent SM control will be covered. Then, the derivation of PWM-based SM control schemes for DC/DC converters will be illustrated. The mathematics behind the modelling and the inherent control features will be discussed. A detailed exposition of how such kind of controllers can be practically engineered to suit specific purposes in controlling power converters will be provided. The practical aspects of the implementation are also described.

Modern converters have non-ideal ripple in inductor current and output voltage for ideal hysteretic controller implementation. This chapter explains various methods to generate synthetic ripple from converter operating waveforms using analogue blocks. As this ripple is near ideal, they lead to proper hysteretic controller operation. Either active or passive networks can be used to implement a ripple generator. Various methods to generate synthetic ripple are explained in this chapter. Their analogue implementations are explained. Models of the synthetic ripple modulator are derived, which can be used in feedback design.

One Cycle control is a technique matching many features that are typical of the linear control methods with some others that characterise high performances non-linear control approaches. Indeed, it ensures a constant switching frequency with a high promptness and noise rejection. The One Cycle control technique has recently found applications in many fields related to the renewable energies and to the power factor control, so that the customers' interest is increasing. In this chapter the basic elements of the One Cycle control technique are reviewed and some issues related to its wide applications are discussed. A special emphasis is given to the DC/AC single-phase conversion.

This chapter covers a basic overview of both system-level design and implementation issues of digital controllers for high-frequency switched-mode power converters. The discussion revolves around a specific case study of great practical relevance, namely a voltage-mode-controlled point-of-load (POL) regulator based on an interleaved multiphase Buck topology. Design and simulation results are presented alongside the exposition.

This chapter deals with the use of digital control applied to discharge lamp electronic ballasts with a special focus on high-intensity discharge (HID) lamp ballasts. HID lamp ballasts is one of the power electronics fields in which digital control is well justified. HID lamps require a complicated process of ignition, warming-up, and lamp current and power regulation. Each of these operating stages requires a precise timing during which the measurement of lamp parameters results critical to take the correct decision for a proper operation of the ballast. In addition, HID lamp ballasts deal with very high voltages, which can reach up to tens of kilovolts for hot re-ignition. These high voltages, along with the fact that HID lamps operate at high temperature and pressure, makes safety one of the important issues in HID lamp supply. In this context, microcontroller-based electronic ballasts are an excellent option to achieve all these stringent requirements.

Having in mind the need to show the reported FPGA advantages, the authors present in this chapter the FPGA implementation of a direct sliding mode control for both single-phase and three-phase PWM rectifiers. The choice of the sliding mode theory was motivated by the fact that it offers a powerful analysis tool, which is well adapted for direct control of power converters. So, by means of this theory, the authors attempt to synthesize the current control loop for PWM rectifiers control algorithms. Also, the FPGA implementation of the synthesized algorithms is discussed.

This chapter starts with an overview of the available digital signal processor (DSP) boards suitable for power converters control, indicating the main features for each case, such as analogue to digital conversion, communication channels, timers, PWM outputs, interruptions, among others. The second topic of this chapter consists in a review of the main topologies used for three-phase unity-power-factor (UPF) rectifiers, where classic six-switches topologies will be presented (Voltage and Current Source Converters), as well as novel configurations as Y- or Δ-switch rectifiers and VIENNA rectifier. As a third subject, the implementation of PhaseLocked Loop (PLL) algorithms will be analyzed in this chapter, remarking the importance of this stage to achieve the UPF operation of the rectifiers. The presented PLL algorithms will be classified as Fixed or Varying Sampling Time implementation. Finally, a couple of control algorithms will be shown, with special emphasis on dq frame-based controllers, p-q theory-based controllers and predictive control. The focus in this last part will lie in how to cope with some practical issues in the implementation of the aforementioned control strategies.

This chapter deals with the DSP control of three-phase voltage source inverters. A study on a 10-kW grid-connected photovoltaic inverter with two control options, namely, the α-β stationary reference frame and the d-q rotating reference frame, is shown. Experimental results are provided in order to validate the performance and limitations of the control strategies under study.

Solar energy is the main source of renewable energy. As the cost ofphotovoltaic (PV) panels continues to reduce, PV-based power generation becomes popular across the world and they can be either grid-connected or stand-alone systems. Currently, the global installation is over 40GW and has been growing at 50% per year since 2005 [1]. Unfortunately, the output voltage of the single PV cell is quite low (about 0.7 V) and thus the output voltage of the PV module is limited to usually 35 V. In order to connect to the power grid, the PV bus voltage should be higher than 350 V for a 220V/50Hz AC grid. Therefore, a high-voltage gain is needed to convert the low PV cell voltage into high voltage for grid connection.

This chapter has introduced the main multilevel converter topologies, i.e. the DCC, the FC, and the CHB converters, as well as the MMC, which is a recent topology that is expected to be widely applied in HVDC transmission systems. After classifying the modulation techniques, the basics of SVM and CB-PWM for multilevel converters have been presented. In the case of SVM, a modulation algorithm prone to be implemented in a digital processor has been applied to the three-level DCC (or NPC converter) and described in detail. A capacitor voltage balancing strategy based on selecting proper redundant vectors has also been embedded in the modulation. In the case of implementing a CB-PWM, several carrier signals are required for multilevel converters. Different carrier dispositions have been shown, including PS-PWM and LS-PWM. CB-PWM is especially interesting for modular converter topologies, such as the CHB converter and the MMC.

Power semiconductors are the most important and enabling components in power converters, similar to the “muscle”in a living body. However, they are controlled by the central control unit, which is similar to the “brain”in a living body. Power semiconductors in power electronic systems process and control power flow. Largely different from their electronic counterpart used in signal processing, power semiconductor devices handle much higher voltages and currents for power flow control. In order to improve the system efficiency, power semiconductor devices are operated in a switching mode (On/Off).

Driven by the emerging applications such as wireless sensors and self-powered biomedical implants, monolithic SC power converters have become a very attractive solution for on-chip power supplies. In this chapter, Section 12.1 first addresses the design challenges. To prepare the readers to fully understand the control and operation methods of these SC power converters, in Section 12.2, key design parameters and causing mechanisms of potential power losses are introduced. In Section 12.3, major control schemes for SC power converters are discussed. Focusing on reliability and inrush current issues, two-stage cascaded topologies are first explained. In order to adapt to variable input and output operation conditions, reconfigurable SC power converters are introduced. PFM and AG-AP control are then discussed to provide different regulation solutions at a wide range of load. To further suppress the ripples, improve the transient response and robustness, examples of interleaving regulations are provided. Many control schemes in the chapter can jointly operate to achieve optimal performance of an SC power converter.

Traditionally, digital signal processor (DSP) control algorithms for three-phase power converters are designed in rotating or stationary reference frames. These approaches require the use of rotation matrices and employ linear controllers such as proportional integral (PI) and proportional resonant. This chapter presents an alternative control solution developed in the natural reference frame and applied to a three-phase unity power factor rectifier (UPFR). This solution requires no transformation matrices, and by harnessing all computation capabilities of the modern DSPs, nonlinear techniques, such as sliding-mode control (SMC) [1, 2] and Kalman filter (KF) [3], can be employed. The main features, along with the advantages and the limitations, of this approach will be discussed in detail throughout the chapter.

The deregulation of the electric market and the increasing number of renewable energy sources connected to the public grid are gradually attracting more attention to the concept of AC microgrids. These power networks are active electricity distribution systems with the capacity to operate as controlled electrical islands [1]. These systems integrate distributed energy sources (including photovoltaic, wind power, mini hydro, gas turbine, etc.) and energy storage devices (such as batteries, ultra-capacitors, flywheels) into the main power system. AC microgrids can meet electrical requirements locally, supply uninterruptible power, improve power quality, reduce power losses and provide voltage support [2]. Furthermore, these systems can reduce environmental pollution and global warming by using lowcarbon technology.

This chapter presents a decoupled optimization technique of designing switching regulators by genetic algorithm (GA) and ant colony optimization (ACO). The mechanisms of the two popular computational intelligence (CI) techniques are briefly described. This chapter also emphasizes implementation issues, as GA is popularly chosen for optimization in continuous domain and ACO is more preferable to discrete domain. The optimization process selects component values in a switching regulator in order to meet both static and dynamic requirements. Although the methods inherit some characteristics of evolutionary computations, they do not optimize the circuit as a whole. Instead, the regulator is decoupled into two parts: the power conversion stage (PCS) and the feedback network (FN). The PCS is optimized for static criteria and then the FN is optimized with the required static and dynamic behaviors of the whole system. Thus, intensive computations usually found in stochastic optimization techniques can be alleviated. The optimization procedures are described systematically and the techniques are illustrated with the design of a buck converter with overcurrent protection.