Showing papers in "Iet Power Electronics in 2009"
TL;DR: The Fast Acting Static Synchronous Compensator (STATCOM) as discussed by the authors is a representative of FACTS family and is extensively used as the state-of-theart dynamic shunt compensator for reactive power control in transmission and distribution system.
Abstract: Fast acting static synchronous compensator (STATCOM), a representative of FACTS family, is a promising technology being extensively used as the state-of-the-art dynamic shunt compensator for reactive power control in transmission and distribution system. Over the last couple of decades, researchers and engineers have made path-breaking research on this technology and by virtue of which, many STATCOM controllers based on the self-commutating solid-state voltage-source converter (VSC) have been developed and commercially put in operation to control system dynamics under stressed conditions. Because of its many attributes, STATCOM has emerged as a qualitatively superior controller relative to the line commutating static VAR compensator (SVC). This controller is called with different terminologies as STATic COMpensator advanced static VAR compensator, advanced static VAR generator or static VAR generator, STATic CONdenser, synchronous solid-state VAR compensator, VSC-based SVC or self-commutated SVC or static synchronous compensator (SSC or S2C). The development of STATCOM controller employing various solid-state converter topologies, magnetics configurations, control algorithms, switching techniques and so on, has been well reported in literature with its versatile applications in power system. A review on the state-of-the-art STATCOM technology and further research potential are presented classifying more than 300 research publications.
368 citations
TL;DR: In this article, a generalised single-phase p-q theory for active power filtering under the condition of distorted utility voltage is proposed. But the authors focus on the case of single phase loads.
Abstract: The single-phase p-q theory for the purpose of active power filtering in the case of single-phase loads is dealt with here. A simple modification is proposed to develop a generalised single-phase p-q theory that can be utilised under the condition of distorted utility voltage. A systematic study is presented by realising both direct and indirect current control techniques. The simulation as well as the digital signal processor (DSP) (DS1104 of dSPACE) based experimental results are discussed. The developed single-phase shunt active power filter (APF) prototype is tested under different operating conditions with different loads to evaluate the full capabilities of the proposed generalised theory for practical uses. The shunt APF reduces the source current total harmonics distortion (THD) from 27.2 to 3.4% under a distorted supply voltage with a THD of 16.2%.
205 citations
TL;DR: In this paper, a controller design methodology for a quadratic boost converter with a single active switch is developed, where the first inductor current and the output capacitor voltage are selected for feedback purposes.
Abstract: A controller design methodology for a quadratic boost converter with a single active switch is developed. This converter has two LC filters; thus, it will exhibit fourth-order characteristic dynamics. However, only the first inductor current and the output capacitor voltage are selected for feedback purposes. This current can also be used for one-cycle overload protection; therefore, the full benefits of current-mode control are maintained. Average current-mode control is selected over peak current-mode control because this strategy provides a faster transient response and better noise immunity. The high-gain compensator of the current loop helps tracking the current programme with a high degree of accuracy. The robustness of the proposed controller is tested under changes in the input voltage, output load and reference signal.
166 citations
TL;DR: In this article, the authors describe a DC-DC converter concept which is capable of achieving very high step-up gains with megawatt (MW) level power transfers, based on two four-switch bridges around a LC circuit and does not utilize iron core transformers.
Abstract: This study describes a novel DC-DC converter concept which is capable of achieving very high step-up gains with megawatt (MW) level power transfers. The converter is based on two four-switch bridges around a LC circuit and does not utilise iron core transformers. The converter topology is simple and utilises thyristors as switches, with potentially soft switching operation. The high-voltage circuit does not suffer from excessive switch stresses or reverse recovery problems. The analytical modelling indicates that loading, and not the voltage gain, determines the converter size and the control input magnitude. For a given converter, the gain and either loading or operating frequency can be arbitrary selected. The converter shows good controllability with a linear characteristic if the operating frequency is used as the control input. The detailed digital simulation on PSCAD platform confirms conclusions from theoretical analysis on a 5 MW test system, which connects 4 kV source to 80 kV high voltage DC grid. The simulation studies of loses, with realistic internal resistances, indicate that efficiencies of around 95% could be expected.
132 citations
TL;DR: In this paper, a structured neural network system has been designed, developed and trained to detect and isolate the most common types of faults: single switch open circuit faults, post short-circuits, short circuits and unknown faults.
Abstract: This study presents a machine learning technique for fault diagnostics in induction motor drives. A normal model and an extensive range of faulted models for the inverter-motor combination were developed and implemented using a generic commercial simulation tool to generate voltages and current signals at a broad range of operating points selected by a machine learning algorithm. A structured neural network system has been designed, developed and trained to detect and isolate the most common types of faults: single switch open circuit faults, post short-circuits, short circuits and the unknown faults. Extensive simulation experiments were conducted to test the system with added noise, and the results show that the structured neural network system which was trained by using the proposed machine learning approach gives high accuracy in detecting whether a faulty condition has occurred, thus isolating and pin-pointing to the type of faulty conditions occurring in power electronics inverter-based electrical drives. Finally, the authors show that the proposed structured neural network system has the capability of real-time detection of any of the faulty conditions mentioned above within 20 ms or less.
104 citations
TL;DR: As the proposed hysteresis current controller has a capability to ensure equal switching frequencies among the switching devices, the capability of inverter switching devices can be fully utilised to improve the output current waveform.
Abstract: A new hysteresis current controller for single-phase full-bridge inverters is proposed here. The proposed hysteresis current controller combines the advantages of both symmetrical unipolar PWM and hysteresis techniques. As the proposed hysteresis current controller has a capability to ensure equal switching frequencies among the switching devices, the capability of inverter switching devices can be fully utilised to improve the output current waveform. The proposed hysteresis current controller is compared with conventional single-band and double-band hysteresis current controllers. Simulated and experimental results are included to show the effectiveness of the proposed current controller.
100 citations
TL;DR: In this article, a high-efficient current-fed push-pull converter is proposed for high output voltage applications supplied by lowvoltage and high-current sources such as fuel cells and solar cells.
Abstract: A high-efficient current-fed push-pull converter is proposed for high output voltage applications supplied by low-voltage and high-current sources such as fuel cells and solar cells. The proposed converter conserves inherent advantages of a conventional current-fed push-pull converter such as low input current stress and high-voltage conversion ratio. The converter employs a voltage-doubler rectifier in order to remove the reverse-recovery problem of the output rectifying diodes and to provide much higher voltage conversion ratio. Additionally, by allowing the duty ratio < 0.5, the converter operates in wider input voltage range, and the ripple current of a boost inductor is reduced, compared with the conventional one. Moreover, as the duty ratio approaches 0.5, the ripple of the inductor current moves in close to zero. The operation of the proposed converter is analysed and experimental results obtained from a prototype verify the analysis. The prototype was implemented for an application requiring a 1.5 kW output power, input voltage range varying from 35 to 60 V, and 350 V output voltage. Experiment results show that minimum efficiency at full load is about 95.5%.
88 citations
TL;DR: In this paper, a method is presented to compute the switching angles for selected harmonic elimination (SHE) in a multilevel inverter using the particle swarm optimisation technique.
Abstract: A method is presented to compute the switching angles for selected harmonic elimination (SHE) in a multilevel inverter using the particle swarm optimisation technique. For a desired fundamental voltage, the switching angles are computed by the developed algorithm while eliminating the lower-order harmonics. Also, the selected higher-order harmonics are eliminated by additional switching to contribute minimum total harmonic distortion (THD) for the output voltage. The switching angles computed for optimum THD at varying modulation index are stored as a look-up table in digital signal processor (DSP) memory for online application, thus reducing the online computational burden of solving the non-linear equations of SHE problem. Direct solution of non-linear transcendental equations of SHE problem can lead to discontinuity at certain modulation indices. Here the switching angles are computed offline considering optimum voltage THD whereas selected harmonics are eliminated at all possible modulation indices including the point of discontinuity. The computed angles are used in an experimental setup to validate the simulated results.
85 citations
TL;DR: In this paper, a module-integrated, photovoltaic (PV) power conditioning system with a high-efficiency, high step-up DC-DC converter is proposed.
Abstract: A module-integrated, photovoltaic (PV) power conditioning system with a high-efficiency, high step-up DC-DC converter is proposed. The step-up DC-DC converter employs an active-clamp circuit for soft switching of the power semiconductor switches. Also, a dual series-resonant rectifier is employed in order to remove the reverse-recovery problem of the output-rectifying diodes and to provide a much higher voltage conversion ratio. The PV current is estimated without using a DC current sensor, and the PV current ripple reduction technique is suggested to reduce the current ripple without an external component. A 1 kW prototype for the PV voltage range of 30-60 V is implemented, and all algorithms and controllers are implemented on a single-chip microcontroller. Experimental results show that the power efficiency is 92.5-94% and the ripple current is 3.5% of the rated input current.
83 citations
TL;DR: In this article, a series of negative output dc-dc converters (voltage-lift-type Cu-k converters) applying series voltage lift (VL) implementing VL techniques is introduced.
Abstract: The voltage-lift (VL) technique is an effective method that could be applied in electronic circuit design. A series of negative output dc-dc converters (voltage-lift-type Cu-k converters) applying series Cu-k implementing VL techniques is introduced. Compared with the Cu-k converter prototype, these converters can perform positive to negative dc-dc voltage increasing conversion with higher voltage transfer gains. They are different from other existing dc-dc step-up converters and possess several advantages, mainly including fewer switches, clear conversion processes and a high output voltage with the small ripple. Since the proposed converters avoid using transformers and cascade connection, the relative simple structures are beneficial to potential practical applications in future. A detailed theoretical analysis for continuous and discontinuous conduction modes is given. Both simulation and experimental results are provided to verify the main characteristics.
79 citations
TL;DR: In this article, the authors proposed a fault detection method using a field programmable gate array (FPGA) and experimentally validated for a three-phase VSI used in shunt active filter case.
Abstract: The design, implementation, experimental validation and performances of a fully digital fast power switch failure detection and compensation for fault-tolerant voltage source inverters (VSIs) are discussed. The approach introduced minimises the time interval between the fault occurrence and its diagnosis. The possibility to detect a faulty switch or driver of the VSI in less than 10 µs by using simultaneously a ‘time criterion’ and a ‘voltage criterion’ is demonstrated. In order to attain this short detection time a field programmable gate array (FPGA) is used. The studied fault detection method is implemented using a FPGA and experimentally validated for a three-phase VSI used in shunt active filter case. The proposed method tested first by ‘FPGA in the loop’ prototyping has been also validated through a fully experimental active power filter which confirms the satisfactory performances of the proposed approach. Moreover, the other feature introduced in this approach is that the control scheme and the fault-tolerant scheme are both programmed in only one FPGA.
TL;DR: In this paper, a 5kW multilevel modular capacitor-clamped dc-dc converter (MMCCC) with bi-directional power management and real-time fault bypassing capability is presented.
Abstract: A 5-kW multilevel modular capacitor-clamped dc–dc converter (MMCCC) with bi-directional power management and real-time fault bypassing capability will be presented in this study. The modular structure of the MMCCC topology was utilised to build this 5-kW converter with necessary redundancy and hot swap feature for industrial and automotive applications including a future plug-in hybrid or fuel-cell powered all electric vehicles. Moreover, the circuit has flexible conversion ratio that leads to establish bi-directional power management for automotive applications mitigating the boost voltage for the fuel-cell or dual battery architecture. In addition, the MMCCC exhibits better component utilisation compared to many capacitor-clamped or classical dc–dc converters based on inductive energy transfer mechanism. Thus, the MMCCC circuit can be made more compact and reliable compared to many other dc–dc converters for high-power applications.
TL;DR: In this paper, an improved scheme of hysteresis current control for a three-level distribution static compensator (DSTATCOM) application is proposed, which results in reduced stress and losses of the inverter switches with a limited range of switching frequency as well as a low tracking error.
Abstract: This study proposes an improved scheme of hysteresis current control for a three-level distribution static compensator (DSTATCOM) application. The conventional two-level hysteresis controller offers advantages including ease of implementation and good dynamic performance, but the switching frequency is subjected to wide variation. Also, the maximum frequency may exceed tolerable limits, as the width of the current band becomes narrower. The basic three-level switching scheme overcomes the above drawback and results in a reduced switching frequency and lower switching losses but the actual current tracks the reference current either in the upper band or in the lower band, resulting in an increased tracking error. However, the suggested scheme results in reduced stress and losses of the inverter switches with a limited range of switching frequency as well as a low tracking error. A digital simulation of a three-phase, four-wire compensated system is carried out through MATLAB to verify the effectiveness of the suggested scheme and an experimental prototype is also built to validate the same.
TL;DR: In this article, an interleaved boost converter is proposed to extend the voltage gain and to reduce the switch voltage stress compared with the conventional interleaving boost converter in high step-up applications, where only one set of active clamp circuit is necessary for the interleaves two phases to recycle the leakage energy and to absorb the voltage spikes caused by the leakage inductance of the winding-coupled inductors.
Abstract: An interleaved boost converter is proposed to extend the voltage gain and to reduce the switch voltage stress compared with the conventional interleaved boost converter in high step-up applications. With the topology variation, only one set of active clamp circuit is necessary for the interleaved two phases to recycle the leakage energy and to absorb the voltage spikes caused by the leakage inductance of the winding-coupled inductors. Both the main switches and the clamp switch of the proposed converter are ZVT soft switching performances during the whole switching transition, which minimises the switching losses. The output diode turn-off current falling rate is controlled by the leakage inductance, which alleviates the output diode reverse-recovery problem and reduces the relative reverse-recovery losses. The experimental results based on a 40-380-V DC/DC prototype verify the effectiveness of the theoretical analysis.
TL;DR: In this paper, a space vector modulation (SVM)-based switching strategy for a five-level diode-clamped converter that is adapted as a static compensator (STATCOM) is presented.
Abstract: A space vector modulation (SVM)-based switching strategy for a five-level diode-clamped converter that is adapted as a static compensator (STATCOM) is presented. The main feature of the proposed SVM switching strategy is that it enables voltage-balancing of the DC capacitors, under steady-state and transient conditions, with no requirements for additional control actions or auxiliary devices. A dynamic model of the five-level STATCOM for power system studies is also developed. On the basis of the developed model, a voltage controller to regulate the DC-side voltage and a decoupled current controller to control the AC-side real and reactive power are designed. Performance of the STATCOM and the corresponding controllers are evaluated on the basis of digital time-domain simulation studies in the PSCAD/EMTDC environment. The studies demonstrate capabilities of the proposed space vector modulation (SVM) strategy to maintain voltage balance of the DC capacitors and control the STATCOM reactive power exchange for various operating conditions.
TL;DR: In this article, an AC/DC converter with auxiliary circuits and power factor correction (PFC)-OFF control was designed and implemented to meet the standby power specification. But, the work in this paper is limited to the case where the auxiliary circuits do not need any current sensor and hysteresis circuit to detect the load condition, which can reduce the cost and avoid false activation.
Abstract: The objective of this study is to design and implement an AC/DC converter in order to meet the standby power specification. The design of auxiliary circuit (including start-up circuit) and power factor correction (PFC)-OFF control which significantly reduces the standby power to meet the energy code under standby condition will be presented. Moreover, it will be shown that these circuits do not need any current sensor and hysteresis circuit to detect the load condition, which can reduce the cost and avoid false activation caused by current noise. The specifications of the converter are as follows: universal input voltage: 90-265 V
AC
, 50-60 Hz; output voltage: 19 V
DC
; output power: 250 W; standby power: input power 1 W at 265 V
AC
input. Experimental results have demonstrated that the input power factor is greater than 98% in the whole voltage range and full load condition. The power consumption under standby condition is less than the specified value, 1 W, confirming the design and implementation.
TL;DR: Practical results confirm the integrity of the proposed Converters as a new family of soft-switching DC-DC converters and their theoretical analysis.
Abstract: Switched resonator converters as a new family of soft-switching DC-DC converters are presented. A unified comprehensive study is performed, topologies are categorised, essential and general equations are presented, the control mechanism is discussed and a useful comparison is provided. Practical results confirm the integrity of the proposed converters and their theoretical analysis.
TL;DR: In this article, a three-phase four-wire active power filter (APF) based on a threelevel neutral-point-clamped (NPC) inverter is presented.
Abstract: The three-phase four-wire active power filter (APF) based on a three-level neutral-point-clamped (NPC) inverter is presented. The proposed APF and controller eliminate harmonics in all three phases as well as the neutral current. The existing NPC inverter for a three-phase three-wire system is used for the three-phase four-wire system since the split DC capacitors provide a neutral connection. To regulate and balance the split DC-capacitor voltages, the new control using the sign cubical hysteresis controller is proposed. The control method discerns the harmonic currents by fast Fourier transform choosing switching states from a switching table based on the hysteresis control. The simulation and experimental results verify the feasibility of the three-phase four-wire APF.
TL;DR: In this article, a CL-resonant push-pull DC-DC converter is proposed for unregulated lowvoltage to high-voltage power conversion with low ripple input current and the resonant frequency of both capacitor and inductor is operated at approximately twice the main switching frequency.
Abstract: A current-fed zero-voltage-switching (ZVS) and zero-current-switching (ZCS) CL-resonant push-pull DC-DC converter is presented in this paper. The proposed push-pull converter topology is suitable for unregulated low-voltage to high-voltage power conversion with low ripple input current. The resonant frequency of both capacitor and inductor is operated at approximately twice the main switching frequency. In this topology, the main switch is operated under ZVS because of the commutation of the transformer magnetising current and the parasitic drain-source capacitance. Because of the leakage inductance of the transformer and the resonant capacitance from the resonant circuit, both the main switch and output rectifier are operated by implementing ZCS. The operation and performance of the proposed converter has been verified on a 400-W prototype.
TL;DR: In this paper, an efficient, compact method for deriving the approximate, linear, average model of 6- and 12-pulse rectifiers, based on the assumption of a small duration of the overlap angle is presented.
Abstract: To carry out stability and voltage regulation studies on more electric aircraft systems in which there is a preponderance of multi-pulse, rectifier-fed motor-drive equipment, average dynamic models of the rectifier converters are required. Existing methods are difficult to apply to anything other than single converters with a low pulse number. Therefore an efficient, compact method for deriving the approximate, linear, average model of 6- and 12-pulse rectifiers, based on the assumption of a small duration of the overlap angle is presented. The models are validated against detailed simulations and laboratory prototypes.
TL;DR: In this paper, a new space vector (SV) current control scheme for shunt active power filters (APFs) is introduced first, with a three-level neutral point-clamped voltage source inverter (VSI) as well as a standard two-level VSI.
Abstract: A new space vector (SV) current control scheme for shunt active power filters (APFs) is introduced first, with a three-level neutral point-clamped voltage source inverter (VSI) as well as a standard two-level VSI. Then, the proposed control is compared with the other SV current control method to evaluate inherent advantages and drawbacks of the control schemes. The proposed control can selectively choose harmonic current components by using a real-time fast Fourier transform to generate the compensation current. The proposed current control utilises a rotating coordinate system, processing the information of the actual position of the grid-voltage SV, which is remarkably important in APF applications, and chooses switching states from the switching table implemented in a field programmable gate array. With the proposed control, the total harmonic distortion (THD) of the compensated grid current, the average switching frequency and switching power loss are significantly reduced. Different SV control strategies, including the proposed method, are compared via simulation and experiment, based on three-level and two-level VSIs.
TL;DR: In this paper, a single-phase power factor corrector (PFC) based on the Sheppard-Taylor topology is studied, which facilitates a better input current tracking, lower voltage stresses across the devices and larger output voltage range for the same operating area.
Abstract: A new single-phase power factor corrector (PFC) based on the Sheppard-Taylor topology is studied. Compared with conventional PFCs, this topology facilitates a better input current tracking, lower voltage stresses across the devices 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 control method uses the simple and robust hysteretic-based controller; the second employs a conventional PI regulator; and the third is based on the model nonlinearity compensation approach. The design of the last two control methods is based on the knowledge of a mathematical model that would accurately represent the converter. This model is developed in this paper using the state-space averaging technique, and then the small-signal transfer functions of the converter are derived for linear control design purpose. 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.
TL;DR: In this article, a fast response low harmonic distortion control scheme is proposed that combines the useful features of the sliding mode control and the repetitive control to achieve excellent transient and steady-state system performances in voltage source inverters.
Abstract: A fast response low harmonic distortion control scheme is proposed that combines the useful features of the sliding mode control and the repetitive control to achieve excellent transient and steady-state system performances in voltage source inverters. The principle of s domain equivalent control is adopted to integrate the two methodologies and to facilitate the design and analysis of the proposed scheme. An optional specific low-pass filter can be introduced into the system to improve the transient response of the regulation. Experimental results show that fast dynamic responses are achieved through the sliding mode control, whereas low harmonic distortions are achieved through the repetitive control.
TL;DR: The instantaneous reactive power theory has been the most used in nonlinear load compensation with active power filters (APF) as mentioned in this paper, and its application to APF control allows constant source power to be obtained after compensation in a simple way.
Abstract: The instantaneous reactive power theory has been the most used in nonlinear load compensation with active power filters (APF). Its application to APF control allows constant source power to be obtained after compensation in a simple way. It works optimally with balanced and sinusoidal source voltage, but not so good with unbalanced or non-sinusoidal source voltage. Although the p–q theory obtains constant source power in all the cases, in the second one the source current obtained is not balanced and sinusoidal. On the other hand, some researches argue that it is not a complete power theory because it does not assign a physical meaning to the power terms. Necessary modifications in the original formulation to treat compensation under any condition of voltage supply are discussed. Moreover, here, it is reformulated in phase coordinates, which allows a simpler treatment for analysing the different compensation strategies. On the other hand, from the power point of view, it is proved that the introduction of instantaneous imaginary power makes p–q formulation a formal theory of electric power in three-phase system. Finally, compensation strategies are applied to a practical power system and the results are presented.
TL;DR: The proposed SRFC and SRFSMC systems can automatically regulate the fuzzy rules to achieve satisfactory performance and make the computation easy and, hence, they are suitable for real-time control.
Abstract: A self-regulating fuzzy control (SRFC) design method is proposed; this control system uses a gradient rule modification method to regulate the fuzzy rules. Moreover, to reduce the number of fuzzy rules and to strengthen the robustness of SRFC, a self-regulating fuzzy sliding-mode control (SRFSMC) design method is also developed. Both the SRFC and SRFSMC systems contain two sets of fuzzy inference logic, one being the control regulator and the other the rule modifier. The proposed SRFC and SRFSMC systems can automatically regulate the fuzzy rules to achieve satisfactory performance and make the computation easy and, hence, they are suitable for real-time control. Finally, the proposed SRFC and SRFSMC systems are applied to control a forward DC-DC converter to illustrate their effectiveness. A microcontroller-based experimental system is implemented. Experimental results show that the proposed SRFC and SRFSMC systems are robust with regard to different input voltages and load resistance variations for the forward DC-DC converter.
TL;DR: In this paper, a new digital current control technique for DC-DC switching converters operating indistinctly in continuous (CCM) or in discontinuous (DCM) conduction mode is reported.
Abstract: A new digital current control technique for DC–DC switching converters operating indistinctly in continuous (CCM) or in discontinuous (DCM) conduction mode is reported. The control method consists in predicting the switching instant at which the current inductor reaches a reference by taking two samples of this current and computing the equation of a straight line. The resulting predictive digital interpolation current control (PDICC) does not require the previous knowledge of converter parameters, it is based on the same principles than the classical analogue current control methods and maintains similar dynamic characteristics.
TL;DR: The need for an isolation transformer is eliminated, the size, weight and cost of the system are significantly reduced and new control algorithms of the rectifier, the charger/discharger and the inverter are proposed.
Abstract: A transformerless three-phase on-line uninterruptible power supply (UPS) is proposed. The proposed UPS is composed of a rectifier, an inverter and a battery charger/discharger. The rectifier regulates a DC-link voltage and performs power factor correction. On the other hand, the inverter provides a regulated sinusoidal output voltage and has the current-limiting capability for an impulsive load. The battery charger/discharger reduces the number of battery and supplies the power demanded by the load in the event of the input power failure or abrupt decrease of the input voltage. Since both neutral lines of the input and output voltages are connected at the centre of the DC-link, the need for an isolation transformer is eliminated and the size, weight and cost of the system are significantly reduced. Additionally, new control algorithms of the rectifier, the charger/discharger and the inverter are proposed.
TL;DR: In this article, a Lyapunov-based current control method for active power filter (APF) system is proposed, which is derived from directly applying the stability theory to the integral controller, so that the closed-loop systems possess better harmonic current elimination.
Abstract: To reduce harmonic distortion in the power lines and to improve the system power quality, the applications of active power filter (APF) has attracted a lot of attentions. A Lyapunov-based current control method for APF system is proposed. The control law is derived from directly applying the Lyapunov stability theory to the integral controller, so that the closed-loop systems possess the better harmonic current elimination. The control strategy based on Lyapunov candidate is discussed in detail and it is shown that the proposed control method provides a general design framework for the model-based harmonic current elimination and reactive power compensation. The main advantage of this approach is that Lyapunov stability analysis can be used to obtain a set of proper parameters for the integral controller. The proposed controller is validated by carrying out some experiments. Computer simulations are presented to confirm the effectiveness of the proposed control strategy and the validity of the simulation technique. Experimental results are also presented to verify the theoretical and simulation studies.
TL;DR: In this article, the authors classified the fundamental principles of generation of the reference signal for shunt switching compensator (SSC) control with the Currents' Physical Components (CPC) power theory.
Abstract: Compensation objectives in three-phase asymmetrical systems with non-sinusoidal voltages and currents, from the perspective of the loading and/or supply quality improvement, are discussed and classified Fundamentals of generation of the reference signal for shunt switching compensator (SSC) control with the Currents' Physical Components (CPC) power theory are also presented The CPC enables to fit the control algorithms to various objectives of Compensation and to the load properties This is because the CPC power theory, being founded on power phenomena in electrical systems, provides clear insight into power properties of electrical loads In spite of the fact that the CPC power theory represents a frequency-domain approach to the identification of the power properties, the CPC-based algorithms are not very computationally demanding and make a quasi-instantaneous control of switching compensators possible
TL;DR: The authors propose a novel dc voltage charge balance control for cascaded inverters that can self-adjust to achieve balance charge control without a complex circuit.
Abstract: The authors propose a novel dc voltage charge balance control for cascaded inverters. The proposed controller has two auxiliary control signal features: (1) a balanced discharging of isolated input dc voltages and (2) good flexibility and suitability for the applications when the number of H-bridge inverter modules is changed. When compared with the conventional cascaded inverters, the proposed control can self-adjust to achieve balance charge control without a complex circuit. The system does not require a new design of controller if a new H-bridge inverter module is added to the system for increasing the power capacity, or an H-bridge inverter module is disconnected from the system owing to its failure. The design of the auxiliary control signals is described in detail and implemented in software. Finally, a 7-level cascaded inverter with three dc-ac converter modules was constructed and tested. Analysis, simulations and experimental results are presented to demonstrate the superiority of the proposed system.