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Power Factor Correction (PFC) circuits are widely used in single-phase rectifiers in order to emulate a linear resistive behavior. Several PFC topologies were introduced in the last thirty years, depending on the required source-load characteristics and system performance. The Boost PFC is still the most popular configuration due to its simplicity, but it suffers from high voltage stresses across the power electronic devices. To overcome this drawback, Buck-Boost structures such as the Cuk, SEPIC and Sheppard-Taylor topologies were designed and found quickly great interest among power electronics researchers. The complete analysis of these converters along with the Boost PFC was traditionally elaborated independently, each study being only valid to a specific topology. In this paper, a unified approach allowing the design and analysis of any PFC converter in a common framework is proposed. The mathematical developments concern a general-case topology that could represent any of the above mentioned converters. The obtained theoretical results are then verified through comparison with the already known equations specified for each topology.

This paper presents a new study of a modified Sheppard-Taylor-based Power Factor Correction (PFC) circuit used for single-phase low-voltage high-current applications. The proposed converter is designed to operate in Continuous Inductor Current Mode and Discontinuous Capacitor Voltage Mode (CICM/DCVM). In this mode of operation, the PFC provides zero-voltage turn-off switching, as well as natural input power factor correction over a wide range of input voltage. Due to the simplified control circuit and reduced switch current stress that it yields, this mode of operation offers better efficiency and higher reliability than the CICM/CCVM previously reported in the literature. The theoretical analysis of the proposed PFC is presented and verified through digital simulations. It is shown that this rectifier exhibits high input power factor and low line current distortion at low output voltage level.

This paper presents the H ∞ robust control law elaborated on the basis of a state-space averaged model of the Vienna rectifier, expressed in the synchronous rotating frame. A control scheme is designed by using the steady-state and dynamic models of the Vienna rectifier that are derived by means of a local linearization around the nominal operating point. The proposed robust control law is then verified numerically through a digital implementation of the converter in the Matlab/Simulink framework, using the switching function approach. Simulation experiments are finally carried out in order to test and verify the tracking and regulation performance of the H ∞ control law, as well as its robustness towards load or mains source disturbance. For the same operating conditions, the performance of the robust control law is analyzed in terms of line currents Total Harmonic Distortion (THD) and DC voltage regulation.

This paper proposes a new three-phase power factor correction rectifier using current injection technique. This topology uses two active networks: an injection network composed by three bidirectional switches operating at low frequency and a current shaping network consisting of two high frequency switches and only one inductance. An input current total harmonic distortion (THD) of 8.6% and a high power factor were obtained at a load of 61 Ohms. Simulation results will consolidate the proposed circuit study.

In this paper, a new single-phase Power Factor Corrector (PFC) based on the Sheppard-Taylor topology is studied. Compared to conventional buck, boost or buck-boost PFCs, this topology allows a better current tracking at the AC side, with a relatively reduced voltage at the DC side. Consequently, the high frequency AC filters required by the buck PFCs are avoided, and the voltage stresses on the boost switches are significantly reduced. Furthermore, the control detuning phenomenon, from which suffer most of the conventional PFCs, especially at very low input voltage, is avoided. This yields major improvements in the source current waveform. Compared to the conventional Sheppard-Taylor converter, this new topology allows lower voltage stresses across the capacitors and larger output voltage range for the same operating area. The converter is integrated as a PFC at the DC-end of a single-phase diode bridge. Pulse-Width-Modulated (PWM) multi-loops control schemes are proposed and developed in order to ensure a unity power factor at the AC-source side and a regulated voltage at the DC-load side. The first one uses the simple and robust hysteretic-based controller, the second one employs a conventional PI regulator, whereas the third one is based on the model nonlinearity compensation approach. The design of the last two control methods is based on the state-space averaged model of the converter. The performance of the different control strategies is evaluated through simulation experiments carried out on a numerical version of the converter. The implemented model of the converter is obtained by using the switching function technique. The control system is tested under both rated and disturbed operating conditions. The system performance is evaluated in terms of source current Total Harmonic Distortion (THD), input power factor, DC voltage stabilization, and regulation following load variations.

In this paper, the small-signal averaged model of a new Sheppard-Taylor-based DC-DC converter, used in single-phase power factor correction (PFC) applications, is derived. Compared to the conventional Sheppard-Taylor converter, this topology allows lower voltage stresses across the capacitors and larger output voltage range for the same operating area. Based on the proposed model, a carrier-based Pulse-Width-Modulation (PWM) linear control system is developed in order to ensure a unity power factor at the rectifier AC-side and a regulated voltage at the rectifier DC-side. Both current and voltage regulators are PI-type. The performance of the proposed control scheme is tested through simulations. The system performance is evaluated in terms of source current total harmonic distortion (THD), input power factor and DC-voltage regulation.

In this paper, a nonlinearity- compensation control scheme is used in combination with an Extended Kalman Filter estimation algorithm, in order to ensure AC current shaping and DC voltages regulation for a three-phase three-wire Vienna converter. This approach aims to reduce the high number of sensors, needed by the traditional nonlinear control approach, thus reducing realization costs and improving circuit reliability. For this aim, source and DC loads voltages are numerically reconstructed by an extended Kalman filter, based on the converter averaged model. Consequently, only two current sensors may be used in the circuit, versus 10 sensors for the conventional method. A multi-loop nonlinear control technique is, then, applied to the rectifier, using the estimated voltages instead of the measured ones. The measured currents and the estimated partial DC bus voltages are controlled via inner loops. The total output DC bus voltage is regulated in an outer loop, based on power balance consideration. The proposed method is experimentally verified on a 1.5 kVA prototype of the rectifier, using the DS1104 controller board of dSPACE and real-time workshop of Matlab. It is proved that the implemented nonlinear observer exhibits high estimation precision within acceptable response time, thus ensuring very satisfactory operation of the converter in steady state.

In this paper, a new nonlinearity compensation control is developed and applied for a single-phase Power Factor Corrector (PFC) based on the combination of the Sheppard-Taylor and SEPIC topologies. Compared to conventional buck, boost or buck-boost PFCs, this topology allows a better current tracking at the AC side, with a relatively reduced voltage at the DC side. Based on the exact linearization of the converterpsilas averaged model, and on the use of a fixed-frequency carrier to generate the Pulse-Width-Modulated (PWM) gate signal, the control system is designed to ensure unity power factor at the rectifier AC-side and regulated voltage at the rectifier DC-side. The performance of the proposed control scheme is tested through simulations, and evaluated in terms of source current Total Harmonic Distortion (THD), input power factor and DC-voltage regulation.

This paper deals with the application of a sliding mode strategy to control a three-phase shunt active power filter (APF). The APF consists of four-leg voltage source inverter (VSI) bridge. The APF ensures full compensation for harmonic phase currents, harmonic neutral current, and reactive and unbalanced nonlinear load currents. It also regulates its self- sustaining dc bus voltage. The reference currents are obtained from the nonlinear load currents. To control the APF, the selection of the sliding mode switching functions is based on the multivariable state space model in the synchronous dq0 reference frame. The control law has a switching component forcing the system's trajectory to the sliding surface and a continuous component valid on the sliding surface. The stability of the closed loop system is proved by means of Lyapunov stability criterion. The robustness over a wide range of operation is another property of the control. Simulations are conducted to verify the analytical analysis of the control.

In this paper, three modeling techniques that are conventionally used in the derivation of mathematical models for switch-mode DC-DC converters are presented and studied. The state-models obtained by applying these general-case approaches are valid under both continuous and discontinuous operating modes. The first two methods use averaging process and allow only a low-frequency representation of the converter, whereas the third one, which is based on the using of the switching function concept, gives a mathematical model that is valid in the entire frequency range and has thus more accuracy in computer implementations. For illustration purpose, and in order to show the extendibility of all three modeling approaches to other families of switch-mode converters, a boost-type single-phase full-bridge rectifier is considered. The most-general switching-function-based model is highly suitable for real-time simulations.

The presence of current harmonics in the grid causes major problems such as overheating and electromagnetic emissions. Active Power Filters (APF) have been presented as alternative to reduce such harmonics. In this paper, a new constant-frequency control scheme based on the linear decoupling principle is proposed for a shunt three-phase fourwire APF. The APF is used to compensate the current distortion and the reactive power created by a typical industrial load. The elaboration of the control law is based on a small-signal averaged model of the converter, computed in the (d,q,0) synchronous frame. The control scheme consists of multiple-loops regulators that ensure voltage regulation at the DC side of the filter, and current wave shaping at the AC side. The control system is implemented numerically using Matlab/Simulink tool. The performance of the proposed control approach is finally discussed through the obtained simulation results.

Current harmonics, which are injected in the utility by nonlinear loads, cause major problems that tend to deteriorate the power quality at the mains. To reduce such harmonics, active power filters (APF) are commonly employed. Challenges in improving the performance of such systems by designing sophisticated control algorithms occupy actually a major field of interest for power electronics researchers. In this paper, a new frequency-domain small- signal model of a shunt three-phase four-wire APF is presented for linear control purpose. The model calculation is based on a state-space averaged model of the filter, computed in the (d,q,0) synchronous frame. The obtained transfer functions offer new simple, systematic and straightforward alternatives for the design of linear control schemes that would ensure suitable performance for the filters.

This paper introduces a new reaching law in sliding mode control that reduces chattering in steady state, without affecting the robustness or the tracking performance of the controller. The proposed reaching law contains an exponential term that dynamically adapts to the variations of the switching function, thus improving the robustness of the control law and keeping the tracking performance unaffected. The proposed approach is then applied in real time to a 3 DOF modular robot arm. Experimental results are compared to conventional sliding mode approach, from which we conclude the superiority of the proposed approach, especially concerning chattering reduction on control input.

In this paper, the small-signal averaged model of a Sheppard-Taylor DC-DC converter, used in single-phase Power Factor Correction (PFC) applications, is derived. Compared to conventional buck, boost or buck-boost PFCs, this topology allows a better current tracking at the AC side, with a relatively reduced voltage at the DC side. Based on this model, a carrier- based Pulse-Width-Modulation (PWM) linear control system is developed in order to ensure a unity power factor at the rectifier AC-side and a regulated voltage at the rectifier DC-side. Both current and voltage regulators are Pi-type. The performance of the proposed control scheme is tested through simulations. The system performance is evaluated in terms of source current Total Harmonic Distortion (THD), input power factor and DC-voltage regulation.

Current harmonics caused by nonlinear loads yield major power quality related problems in the utility. Such harmonics are commonly reduced by employing static compensators known as active power filters (APF). APF topologies are of various types, depending on technical and economical requirements; and their performance is intimately related to the applied control algorithm. In this paper, a new constant-frequency linear control scheme is proposed for a shunt three-phase four-leg APF. The APF is used to compensate the current distortion and the reactive power created by a typical industrial load. The elaboration of the control law is based on a small-signal averaged model of the converter, computed in the (d,q,0) synchronous frame. The control scheme consists of multiple-loops PI controllers that ensure voltage regulation at the DC side of the filter, and current wave shaping at the AC side. The control system is implemented numerically using the Matlab/Simulink tool. The performance of the proposed control approach is finally discussed through the obtained simulation results.

In this paper, a comparative evaluation of two control strategies applied on the single-phase Sheppard-Taylor power factor corrector (PFC) is proposed. Both control laws generate fixed-frequency carrier-based pulse-width-modulation (PWM) gate signals, and are designed on the basis of the nonlinear averaged model of the converter, which is established using the well-known state-space averaging technique. The first control approach employs linear PI regulators for both input current wave-shaping and output voltage regulation. For this purpose, the derivation of the converter's small-signal transfer functions was required. The second control uses the input-output feedback linearization strategy in order to compensate the system's nonlinearity and simply, thus, the controllers design. The performance of both control schemes is tested through simulations. The comparison is conducted in terms of source current total harmonic distortion (THD), input power factor and DC-voltage regulation.

In this paper, a nonlinearity compensation control is developed and applied for the single-phase Sheppard-Taylor power factor corrector (PFC). Compared to conventional buck, boost or buck-boost PFCs, this topology allows a better current tracking at the AC side, with a relatively reduced voltage at the DC side. Based on the exact linearization of the converter's averaged model, and on the use of a fixed-frequency carrier to generate the Pulse-Width-Modulated (PWM) gate signal, the control system is designed to ensure unity power factor at the rectifier AC-side and regulated voltage at the rectifier DC-side. The performance of the proposed control scheme is tested through simulations, and evaluated in terms of source current total harmonic distortion (THD), input power factor and DC-voltage regulation.

Current harmonics caused by nonlinear loads yield major power quality related problems in the utility. Such harmonics are commonly reduced by employing static compensators known as active power filters (APF). APF topologies are of various types, depending on technical and economical requirements; and their performance is intimately related to the applied control algorithm. In this paper, a new constant-frequency linear decoupling control scheme is proposed for a shunt three-phase four-leg APF. The APF is used to compensate the current distortion and the reactive power created by a typical industrial load. The elaboration of the control law is based on a small-signal averaged model of the converter, computed in the (d,q,0) synchronous frame. The control scheme consists of embedded current and voltage loops that ensure respectively current wave shaping at the AC side of the filter, and voltage regulation at the DC side. The control system is implemented numerically using the Matlab/Simulink tool. The performance of the proposed control approach is finally discussed through the obtained simulation results.

Current harmonics caused by nonlinear loads yield major power quality related problems in the utility. Such harmonics are commonly reduced by employing static compensators known as Active Power Filters (APF). APF topologies are of various types, depending on technical and economical requirements. In this paper, a new constant-frequency nonlinear control scheme for a shunt three-phase four-leg APF is proposed. The APF is used to compensate the current distortion and the reactive power created by a typical industrial load. The elaboration of the control law is based on the state-space averaged model of the converter, computed in the (d,q,0) synchronous frame. The multiple-loop control scheme consists, first, of inner controllers that ensures current shaping and reactive power compensation, and second, an outer loop to allow voltage regulation at the DC side of the filter. In addition, a nonlinearity compensation block is integrated in the inner sub-controller in order to ensure perfect cross-decoupling and linearity between the inner inputs and outputs. The control system is implemented numerically using Matlab/Simulink tool. The performance of the proposed control approach is finally discussed through the obtained simulation results.

In this paper, a new single-phase power factor corrector (PFC) based on the Sheppard-Taylor topology is proposed. Compared to conventional buck, boost or buck-boost PFCs, this topology allows a better current tracking at the AC side, with a relatively reduced voltage at the DC side. Consequently, the high frequency AC filters required by the buck PFCs are avoided, and the voltage stresses on the boost switches are significantly reduced. Furthermore, the control detuning phenomenon, from which suffer most of the conventional PFCs, especially at very low input voltage, is avoided. This yields major improvements in the source current waveform. The proposed converter is integrated as a PFC at the DC-end of a single-phase diode bridge. A pulse-width-modulated (PWM) control is developed in order to ensure a unity power factor at the AC-source side and a regulated voltage at the DC-load side. In order to verify the performance of the proposed control scheme, simulation experiments are carried out on a numerical version of the converter with its control circuit. The implemented model of the converter is obtained by using the switching function technique. The control system is tested under both rated and disturbed operating conditions. The system performance is evaluated in terms of source current total harmonic distortion (THD), voltage regulation, robustness and dynamic time response to a set point offset.

In this paper, design and implementation of a new MIMO linear control technique based on theoretically established and experimentally validated small signal model for the three-phase three-level boost-type AC/DC Vienna converter is presented. The resulted transfer functions are discretized for sake of digital controllers design. Multiple-loop control strategy is adopted and consists of inner current feedback loops, based on the straightforward looping technique that neglects interactions between the dq components of respectively control inputs and currents, and of an outer voltage loop, designed to ensure DC voltage regulation by adjusting the magnitude of the references for the inner current loops. The proposed control approach IS first simulated, using SIMULINK of Matlab, and then validated on a 1.5 kW laboratory prototype supported by the DS 1104 digital real-time controller board of dSPACE. The obtained results prove that a judicious choice of controller parameters, as well as an adequate rating of boost inductors allow meeting the IEEE standards requirements in terms of AC line current Total Harmonic Distortion (THD) and Power Factor (PF). The efficiency of the proposed control technique is maintained in case of disturbances occurring on both source and load sides.

This paper presents an experimental evaluation of two pulse-width-modulation (PWM) control techniques applied to a single phase shunt active power filter (SPSAPF). A direct current control strategy is implemented using a standard PWM (S-PWM) and a modified PWM (M-PWM) in order to compensate the current harmonics and the reactive power generated by a nonlinear load. The M-PWM control technique is based on two comparisons of a triangular high frequency carrier signal with a low frequency modulating signal (that represents the load current harmonics) and its opposite. The M-PWM shifts the first significant harmonics rays towards twice the switching frequency, and eliminates the spectral rays that are centered on the odd multiples of the switching frequency. Furthermore, it is shown that, for a M-PWM, the losses of the active filter are four times smaller than when using a S-PWM. Simulation and experimental results are presented to verify the better performance of the M-PWM over the S-PWM in terms of the total harmonic distortion (THD) of the source current and the reactive power compensation

In this paper, a new multiple-loops nonlinear control scheme, based on the input/output feedback linearization method, is proposed for a DC-to-DC single ended primary inductance converter (SEPIC). Compared to conventional buck or boost converters, this topology allows a low current ripple at the input for a relatively low level of the DC-bus voltage. Consequently, the high frequency filter needed at the AC-side of a buck converter is avoided, and the high voltage stresses applied on the switches are significantly reduced with respect to the boost converter. The converter is integrated as a power factor correction circuit at the DC-end of a single-phase diode bridge. Based on the averaged model of the converter, a pulse-width-modulated (PWM) control algorithm is developed in order to ensure a unity power factor at the AC-source side and a regulated voltage at the DC-load side. In order to verify the performance of the proposed control scheme, numerical simulations are carried out on a switching-functions-based model of the converter, which is implemented using Matlab/Simulink. The proposed model of the converter is valid in the continuous current mode (CCM) and the discontinuous current mode (DCM). The control system is tested under both rated and disturbed operating conditions. The system performance is evaluated in terms of source current total harmonic distortion (THD), input power factor, DC voltage regulation and robustness toward a load disturbance

In this paper, direct and indirect current control strategies are applied to a single-phase shunt hybrid power filter (SPSHPF). They are implemented with a modified pulse width modulation (M-PWM) in order to compensate the harmonics and reactive power generated by non-linear loads and the high frequency harmonics generated by the switching process. Contrarily to the existing methods, the proposed indirect current control eliminates switching spikes in the supply current and appears to be more suitable than the direct current control method, especially when compensation is required. Furthermore, the M-PWM technique ensures the elimination of all groups of harmonics that are centered on the odd multiples of the switching frequency. It requires a relatively reduced input filter. In addition, it attenuates the rays that are located around twice the switching frequency four times less than the S-PWM. The measured power losses of the M-PWM hybrid filter are also four times lower compared to the standard PWM control. Experiment results obtained from a 1 kVA laboratory system and simulations carried on using the power system blockset (PSB) toolbox of Matlab verify the effectiveness of the SPSHPF adopting the indirect current control with the modified PWM technique

In this paper, a two-stage DC-DC converter for high current applications is studied. The converter consists of two three-phase full-bridge inverters connected through three AC inductors. First, a switching-functions based model of the converter is establishes, and then a control scheme is designed for both inverters in order to ensure a high power factor at the AC stage, and a regulated voltage at the DC load. The performance of the proposed control system is verified through numerical simulations.

This paper proposes a new instantaneous model of a single-phase shunt hybrid power filter. The proposed model is derived using the switching-function approach. The existence of such model allows, first, a real-time simulation and analysis of the performance of the filter for several operating conditions and, secondly, a systematic design of the suitable controllers that ensure a high power quality at the mains and a voltage regulation at the DC-side of the filter. In order to illustrate the utility of the proposed model, a design of simple linear current and voltage regulators, based on an averaged version of the model, is also presented. The control system is implemented numerically using the Simulink tool of Matlab. Simulations are carried out and the obtained results are proven to be satisfactory. Finally, experimental results obtained from a laboratory prototype of the filter are included in order to validate the theoretical considerations used both in the development of the mathematical model of the filter and the design of the appropriate control system.

In this paper, practical considerations concerning the design and implementation of a single ended primary inductance converter (SEPIC) pre-regulator are addressed. Compared to conventional buck or boost converters, this topology allows a low current ripple at the input for a relatively low level of the DC-bus voltage. Consequently, the high frequency filter needed at the AC- side of a buck converter is avoided, and the high voltage stresses applied on the switches are significantly reduced with respect to the boost converter. The converter is integrated as a power factor correction circuit at the DC-end of a single-phase diode bridge. A pulse-width-modulated (PWM) control scheme is developed and applied to 1 kW laboratory prototype of the converter in order to ensure a unity power factor at the AC-source side and a regulated voltage at the DC-load side. The experimental setup is tested under both rated and disturbed operating conditions. The system performance is evaluated in terms of source current total harmonic distortion (THD), voltage regulation, robustness and dynamic time response to a set point offset.

The proposed paper aims to analyse the control saturation phenomenon and its influence on the steady state converter performance. This analysis is performed for two main targets: 1) Rating AC line inductors, while fulfilling the compromise between a minimal value required to limit main currents ripple at used switching frequency, and a maximal value that maintains the current modulation capability and consequently limits the control saturation phenomenon, 2) Tuning the digital controllers parameters, in order to reduce control saturation on the one hand, and ensure low Total Harmonic Distortion (THD), unity Power Factor (PF) and regulated split DC bus voltages on the other hand. The obtained results clearly show a fundamental dependency between the saturation angle, voltage unbalance controller parameters, and both line inductors size and required output load power.

This paper introduces a new approach based on the use of nonlinear switching functions in sliding mode control. These nonlinear functions are used to eliminate transient constraints on the control input and therefore to increase the speed performance of the controller without having a negative effect on the control input. This approach is brought up in a general perspective to nth order single input systems. In order to validate the superiority of this novel approach over the conventional sliding mode control, simulation results of a current-controlled magnetic levitation system are compared for both the conventional and the new techniques.

This paper presents a detailed study of a Series Hybrid Power Filter (SHPF). The system consists of a small-rated series active power filter and a series tuned passive filter. This combination is suitable for compensating voltage type harmonics-producing load. The hybrid control approach adopted is based on detecting both source current and load voltage harmonics. This technique enhances the compensation characteristics of the proposed system. A low-frequency mathematical model of the series hybrid filter is established. The elaboration of the control law is based on a small-signal averaged model of the converter, computed in the (d,q) synchronous frame. Then, suitable multiple-loops PI controllers are designed on the basis of the system's transfer functions and the use of the linear feedback control. Simulation results are shown in an attempt to verify the mathematical model of the filter and the effectiveness of the hybrid control approach for voltage harmonics compensation.

Current harmonics, which are injected in the utility by nonlinear loads, cause major problems that tend to deteriorate the power quality at the mains. To reduce such harmonics, active power filters (APF) are commonly employed. In this paper, two multiple-loops control schemes for a shunt three-phase four-wire APF are considered. The APF is used to compensate the current distortion and the reactive power created by a typical 60 kW industrial load. The first control scheme is based on the use of hysteresis current controllers for the current wave shaping, whereas the second one employs linear PI regulators designed on the basis of a small-signal averaged model of the converter. Both control schemes are designed to ensure voltage regulation at the DC side of the filter, and current wave shaping at the AC side. The control systems are implemented numerically using Matlab/Simulink tool. The performance of the both control approaches are finally evaluated and compared through the obtained simulation results

In this paper, new mathematical models of DC-DC switch-mode converters, which are valid under both continuous and discontinuous operating modes, are presented. The modeling technique is based on the switching functions concept. The obtained models are represented by time-variant state equations, which offer high simplicity for computer implementation. For illustration purpose, the proposed modeling approach is applied to the conventional buck and Cuk converters. The obtained models are then tested through computer implementation using the Simulink tool of Matlab.

In this paper, a single-phase power factor corrector (PFC) based on the Sheppard-Taylor topology is presented. Compared to conventional buck, boost or buck-boost PFCs, this topology allows a better current tracking at the AC side, with a relatively reduced voltage at the DC side. Consequently, the high frequency AC filters required by the buck PFCs are avoided, and the voltage stresses on the boost switches are significantly reduced. Furthermore, the control detuning phenomenon from which suffer most of the conventional PFCs, especially at very low input voltage, is avoided. This yields major improvements in the source current waveform. The proposed converter is integrated as a PFC at the DC-end of a single-phase diode bridge. A pulse-width-modulated (PWM) control is developed in order to ensure a unity power factor at the AC-source side and a regulated voltage at the DC-load side. In order to verify the performance of the proposed control scheme, simulation experiments are carried out on a numerical version of the converter with its control circuit. The implemented model of the converter is obtained by using the switching function technique. The control system is tested under both rated and disturbed operating conditions. The system performance is evaluated in terms of source current total harmonic distortion (THD), voltage regulation, robustness and dynamic time response to a set point offset.

current harmonics, which are injected in the utility by nonlinear loads, cause major problems that tend to deteriorate the power quality at the mains. To reduce such harmonics, active power filters (APF) are commonly employed. In this paper, a new constant-frequency control scheme for a shunt three-phase four-wire APF is proposed. The APF is used to compensate the current distortion and the reactive power created by a typical industrial load. The elaboration of the control law is based on a small-signal averaged model of the converter, computed in the (d,q,0) synchronous frame. The control scheme consists of multiple-loops PI controllers that ensure voltage regulation at the DC side of the filter, and current wave shaping at the AC side. The control system is implemented numerically using Matlab/Simulink tool. The performance of the proposed control approach is finally discussed through the obtained simulation results.

In this paper, a new mathematical model of a three-phase, three-switch, three-level rectifier is presented. The model is valid under both continuous and discontinuous operating modes. The applied modeling technique is based on the switching functions concept. The obtained model is represented by time-variant state equations, which offer high simplicity for computer implementation. The proposed model is suitable for real-time applications like the hardware-in-the-loop testing

This paper presents an experimental realization of a current-controlled magnetic levitation system (MLS). MLS are nonlinear systems and are unstable in open loop, which makes the control aspect very challenging. It is therefore essential to design robust controllers to solve the problem. Nonetheless, as far as mathematical model and control design are concerned, current-controlled MLS are less complex than the conventional voltage-controlled systems widely discussed in literature. In this paper, a sliding mode regulator is experimentally implemented on a MLS. The nonlinear regulator is designed using the Matlab/Simulink and is run in real time using the RTW of Matlab. Experimental results show the effectiveness of the robust nonlinear controller

This paper presents a unified method for developing power stage transfer functions of paralleled DC/DC converters employing automatic load sharing control. The proposed technique uses large signal averaged models to derive the steady-state and small signal transfer functions, instead of employing small signal modeling technique used widely in literatures. The proposed approach is general and can be applied to any number of paralleled modules. For illustration purpose, this modeling method is applied to two paralleled buck converters with automatic load sharing control, and the corresponding large signal characteristics are analyzed. Moreover, a design methodology for the current share (CS) compensator based on the current share loop gain has been presented. Stability and dynamic performance of the CS control are studied. Simulation results of three paralleled buck converter converting the input DC voltage of 12 V, to 5 V DC at 3times20 A are presented in order to verify the theoretical approach reported in the paper

A new state-space modeling of a three-phase AC/AC matrix converter is presented. The main objective of this paper is the design of a sliding mode controller for both controlling the output voltage and input current. The sliding mode strategy is based on the determination of the sliding surfaces and switching laws allowing to choose an appropriate space vector pattern. Robustness regarding line voltage and load parameters variations of this control technique has been recorded by using simulation results on matlab.

This paper presents a new small-signal model of a three-phase three-switch three-level boost-type rectifier operating with a fixed switching frequency. The proposed model is obtained by linearizing the (d,q)-averaged representation of the converter in the neighborhood of a desired unity-power-factor operating point. The linearized model is expressed both in the time domain, using the state representation, and the frequency domain by computing the corresponding transfer functions. These latter are then used into the design of linear-control-based regulators in order to ensure the convergence and stability of the system around the desired set point. The control system is implemented numerically using Matlab/Simulink, and simulation experiments are carried out in order to test and verify its tracking and regulation performance, as well as its robustness towards load or mains source disturbance.

This paper presents an indirect current control technique applied to a single-phase shunt active power filter (SPSAPF) implemented with pulse width modulation (PWM) to compensate harmonics and reactive power of non-linear loads. This method uses a residual signal constructed from the comparison between the supply current and its desired value. The PWM control technique adopted is based on two comparisons of a triangular high frequency carrier signal and the source fundamental active current. This error signal namely +/spl beta/ and its opposite value -/spl beta/ are both used, at the same instant, to generate the gate signals for the semi-conductor devices. The PWM technique eliminates the group of harmonics that are centred on the odd multiples of the switching frequency. It is requires a relatively reduced L/sub c/C/sub c/ input filter. The use of the averaging technique with this modified PWM control has allowed considering that the active filter transfer function may be modeled by a pure gain. This enables us to easily design the two control loops and choose the regulator parameters. This control technique has been implemented on a single phase laboratory prototype using analog devices. Experimental and simulation results show the performance of the control algorithm for SPSAPF. These presented results highlight the performance of the SPSAPF to compensate harmonics and reactive power.

In this paper, a new observer-based method, which generates the current reference for a three-phase shunt active power filter (SAPF), is presented. This technique is useful for active power filters and capable to eliminate harmonics and compensate reactive power simultaneously. First, the fundamental active current to identify is modeled in the form of a generating process. The other harmonic components appearing in the load current, as well as the basic noises inherent with the signal measurements, are all considered as noises for the observer. The goal of the extraction consists in filtering the noise in order to recover the active fundamental current. The filtering is carried out using an observer on the generating model. The dynamics of the extraction will depend on the speed of convergence of the observer. Simulation results are presented, showing that the method is feasible and the results are acceptable.

In this paper, a comparative analysis of two nonlinear control schemes proposed for a single ended primary inductance converter (SEPIC) power factor corrector (PFC) is presented. The SEPIC converter, compared to conventional buck or boost ones, allows a low current ripple at the input for a relatively low level of the DC-bus voltage. Consequently, the high frequency filter needed at the AC-side of a buck converter is avoided, and the high voltage stresses applied on the switches are significantly reduced with respect to the boost converter. The converter is integrated at the DC-end of a single-phase diode bridge. In order to ensure a unity power factor at the AC-source side and a regulated voltage at the DC-load side, a multiple-loops feedback control scheme has to be developed. Two control strategies are considered in this paper. The first one uses a robust hysteresis current controller, whereas the other method is based on the application of the input/output feedback linearization technique on a state-space averaged model of the converter. In order to verify and compare the performance of both control schemes, numerical simulations are carried out on a switching-functions-based model of the converter, which is implemented using Matlab/Simulink. The proposed model of the converter is valid in the continuous current mode (CCM) and the discontinuous current mode (DCM). The control systems are tested under both rated and disturbed operating conditions. The systems performance is evaluated in terms of source current total harmonic distortion (THD), input power factor, DC voltage regulation and robustness toward a load disturbance

This paper presents the performances of a linear control technique implemented on a two-stage boost rectifier using dSPACE along with the Matlab/Simulink tool. A linear control scheme is applied to a small signal model of the boost topology and is then downloaded to dSPACE through Simulink. The experimental results are analyzed and compared to the simulation ones. The characteristics of the proposed control scheme are discussed and evaluated in both steady state and transient regimes (load and voltage disturbance).

In this paper, a small-signal modeling of a single-phase AC-DC dual boost power factor correction (PFC) pre-regulator is presented. The circuit consists of two interleaved boost converters. A high rated main boost, used for current wave-shaping and energy control, operates at low frequency; whereas an auxiliary boost uses a low rated device operating at high frequency and is controlled to compensate the low frequency ripple generated by the main boost. The control scheme proposed for the dual PFC is based on a small-signal model, which is developed using the average modeling technique along with the small-signal linearization process. The linear controllers are designed in the frequency domain, and are adjusted in order to ensure high dynamic performance of the PFC. Experimental results based on a laboratory 1 kW prototype validate the proposed control approach.

In this paper, a comparative analysis of feedback duty-cycle-based control laws applied to three-phase current injection rectifiers is proposed. The study concerns mainly the fixed-frequency carrier-based pulse-width-modulated (PWM) controllers. The superiority of the fixed-frequency controllers over the hysteresis-based ones is briefly emphasized. The design and performance evaluation of the considered control systems are based on a mathematical model of the converter, obtained by applying the state-space-averaging modeling technique. The performance of the controllers is analyzed through numerical results. Advantages and drawbacks of each proposed control law are discussed, and a comparative performance status in terms of input current total harmonic distortion (THD), DC voltage regulation and dynamic characteristics is established.

This work presents a comparative evaluation of two a major drawback, namely a time-varying switching frequency, multiple-loops duty-cycle-based control schemes applied to a which may reduce, in the one hand, the reliability of the three-phase three-switch three-level boost-type rectifier. The control laws are both elaborated on the basis of a state-space averaged model of the converter, expressed in the synchronous rotating frame. On the one hand, a control scheme that uses linear regulators is designed by using the small-signal transfer functions of the converter's model, which was linearized on the neighborhood of a suitable steady-state operating point. On the other hand, a nonlinear control scheme that uses the input-output feedback linearization approach is also designed in order to satisfy same requirements as for the linear control system. For comparison purpose, both control schemes are implemented numerically using the Simulink tool of Matlab, and simulation experiments are carried out in order to test and verify the tracking and regulation performance of each control law, as well as their robustness towards load or mains source disturbance. For the same operating conditions, the performance of the two control laws are analyzed and compared in terms of line currents total harmonic distortion (THD) and DC voltage regulation.

In this paper, the operation of a three-phase current injection rectifier under severe conditions - heavily varying load and/or disturbed and unbalanced mains voltage - is investigated. The converter is controlled by a fixed frequency PWM multiple-loops controller. The inner current regulators and outer voltage regulator are designed by applying the input/output feedback linearizing control technique on the averaged state model of the converter. The elaboration of the state model is based on the well-known averaging technique commonly used in the modeling of high switching frequency DC-DC converters. The performance of the converter under the proposed operating conditions is evaluated by simulation using the tools of Matlab/Simulink.

Voltage and current harmonics, which are injected in the utility by nonlinear loads, cause major problems that tend to deteriorate the power quality at the mains. To reduce such harmonics, active power filters (APF) are commonly employed. Whereas shunt APFs are used for current-type load, series APFs are applied to voltage-type load and allow both voltage and current harmonic compensation. In this paper, a new constant-frequency control scheme for a series APF is designed. The elaboration of the control law is based on a small-signal averaged model of the converter, computed in the (d,q) synchronous frame. The control scheme consists of multiple-loops PI controllers that ensure voltage regulation at the DC side of the filter, and voltage harmonic compensation at the AC side. The control system is implemented numerically using Matlab/Simulink tool. The performance of the proposed control approach is finally discussed through the obtained simulation results.

In this paper, we present a unified approach in path generation for a mobile robot. We use a memory neuron network to control a mobile robot along a trajectory while avoiding obstacles. We briefly show the robot's features in order to introduce the neural network used to control it. Some simulation results are discussed.