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The focus of this paper is the control of a reusable launch vehicle at exoatmospheric flight conditions, in the presence of actuator effectiveness uncertainty. Since during exoatmospheric flight, dynamic pressure is nonexistent, aerodynamic control surfaces cannot be used. Under these conditions, reaction control jet actuators can provide the necessary thrust to control the vehicle. Reaction control jets have only 2 states, namely, on and off, and continuous control inputs can be implemented with the help of pulse width modulation, which is also employed in this paper. A continuous controller is designed in the outer loop and a control allocator is used to distribute the total control input among redundant actuators, whose effectiveness are assumed to be unknown. The unknown actuator effectiveness is addressed with the help of an adaptive control allocator. A representative model of a reusable launch vehicle equipped with reaction control jets is used to demonstrate the effectiveness of the overall control scheme. [ABSTRACT FROM AUTHOR]

In many studies in the literature, various topologies with reduced switch count are proposed. With the use of these topologies, a lower number of semiconductor switches are required to produce a desired set of voltage. This in turn reduces the size and cost of the inverter. This paper proposes a new reduced switch count topology named "fifteenswitch inverter (FSI)", which is experimentally verified. The FSI has five switches in one leg and have three legs for three phases. It is capable of controlling four three-phase ac loads. In this proposed inverter topology, fifteen switches are used against the twenty four switches in conventional two-level inverter to control four ac loads. The proposed control is implemented using modified sinusoidal and space vector pulse width modulation techniques. A comparative performance of FSI with conventional sinusoidal pulse width modulation and space vector pulse width modulation are presented in linear operating region. The structure and the principle of operation of the proposed inverter are introduced and verified using simulation. The inverter prototype was built and the proposed inverter has been verified experimentally using digital signal controller. The experimental results verify the applicability of the proposed inverter and the employed pulse generation technique. [ABSTRACT FROM AUTHOR]

This paper presents the application of a newly developed 21-level hybrid multilevel inverter. A high frequency modulation technique known as sinusoidal pulse width modulation (SPWM) is applied to the hybrid inverter. This modulation methodology operates the switching sequences of the multilevel inverter to produce the desired 21-level output voltage. To validate the proper application of this inverter, it is further utilized to maintain the speed of a single phase induction motor. The velocity control of the motor is established on the principle of V/f control technique. The speed control strategy along with the compatibility of the SPWM modulation technique were verified by means of simulation and experimental results. [ABSTRACT FROM AUTHOR]

This paper proposes an optimized synchronous PWM method for harmonic elimination in a quasi square wave inverter. The synchronized PWM method enables online harmonic computation and PWM pulse generation in a multitasking digital controller to eliminate lower order harmonics. The multitasking digital controller reduces the look-up table requirement and helps in realizing efficient implementation to eliminate dominant harmonics. This method offers a simple scalable solution for combined fifth and seventh harmonic elimination using two low-cost eight-bit PIC microcontrollers (PIC18F4550, PIC18F452). Experimental results are demonstrated for a single-phase three-level inverter. The proposed method achieves 90% reduction of fifth and seventh harmonic components from a quasi square wave inverter output. [ABSTRACT FROM AUTHOR]

This paper presents a modified sinusoidal pulse width modulation (SPWM) switching method for one-phase and investigated two-phase impedance-source inverter structures. The proposed structure generates pulses for a quasi-Z-source converter and this block produces a unilateral voltage sine wave in the block's output. This signal is applied to the inverter as its input wave. For this purpose, the novel SPWM method is proposed for power switches while being switched complementarily. Two power switches are used in the structure to generate the pure sinusoidal output voltage and to minimize total harmonic distortion (THD), which is an essential parameter in inverter design. The results show that the proposed method generates the pure sinusoidal voltage and current signals for resistive and inductive loads and pure voltage and improved current waves for capacitive loads in comparison with existing techniques, since the THD of the output voltage and current signals is strongly affected by the dynamic loads. This method leads to final cost improvement and reduction of the size of the system with fewer number of components, which are essential parameters for renewable energy resource applications. A mathematical model is validated with the 2017a version of MATLAB/Simulink and 1.51% and 1.33% THD values are reported for low and high power loads, respectively, in the one-phase structure and 0.95% and 0.87% in the two-phase system. Finally, a 120 W prototype has been implemented and tested. A sine-wave with 620 Vac peak to peak amplitude and 50 Hz frequency has been gained in the inverter's output and the quality of the voltage and current waveforms has been evaluated for different two 1.8 kΩ and 600 Ω resistive loads in the one-phase structure. Experimental results confirm all mathematical and simulation results. [ABSTRACT FROM AUTHOR]

In this paper, a new hybrid pulse width modulation technique is proposed to enhance the performance of output voltage from a ternary progression based multilevel inverter. For high power applications, the multilevel inverter can appropriately replace the traditional converter without a transformer and the separate DC sources will be indispensable for various renewable energy sources. The classy split switching technique for the multicarrier pulse width modulation technique is adopted and the concept about new topology is presented in this paper. An arm controller has been chosen to implement the modulation due to its superior features, easy software, and hardware design. Simulation and experimental results are also presented. [ABSTRACT FROM AUTHOR]

In this study, the aim is to evaluate three-phase (3 ϕ ) AC/DC neutral point-clamped (NPC) power factor- corrected (PFC) multilevel converter performance for electric vehicle (EV) fast chargers. Power factor correction for EV fast chargers is very important in terms of efficient power usage and charger compatibility with the grid. Multilevel converters improve charging efficiency, reduce voltage stresses on components, minimize electromagnetic interference, and support high power capabilities. For this reason, multilevel converters with the PFC feature contribute to the reliable and effective operation of the fast-charging infrastructure. Rectifier analysis is tested with extensive simulations using a new modified carrier-based level-shifted pulse-width modulation (PWM) technique. The results obtained are in accordance with international standards. The proposed PWM technique provides low voltage regulation, low total harmonic distortion input current, unit input power factor, and a well-regulated DC bus voltage for the NPC rectifier in fast charging systems, and the system has high efficiency. In addition, the modulation method eliminates the need for an additional PFC circuit. The system demonstrates remarkable success in addressing critical parameters such as capacitor voltage balance. This modified carrier-based PWM is highly successful for NPC rectifiers designed for DC fast chargers, rated for power up to 300 kW. The simulation results of the DC fast charger system demonstrate the validity and flexibility of the proposed carrier-based level-shifted PWM method. [ABSTRACT FROM AUTHOR]

This paper presents a deadbeat-based proportional-integral (PI) controller for a stand-alone single-phase voltage source inverter using a battery cell as the primary energy source. The inverter system is simulated in MATLAB/ Simulink. It consists of a lead acid battery, third-order Butterworth low-pass DC filter and AC filter, H-bridge inverter, step-up transformer, and a variety of loads, as well as its sinusoidal pulse-width modulation (SPWM) deadbeat-based PI controller. In this paper, 2 simulation case studies are carried out, which are the abrupt load changes from a 400 W resistive load to a 500 W resistive load, and from a 400 W resistive load to an inductive load of 500 W 0.85 power factor lagging. From the simulation results for both cases, the state-of-charge of the battery decreases due to supplying power to the loads, yet the battery voltage remains constant at about 36 V and the battery current exhibits a smooth ripple despite the current spikes produced by the H-bridge inverter, which will prolong the lifespan of the battery. This shows that the DC filter performs satisfactorily to isolate the current spikes generated by the SPWM controller and H-bridge inverter. Moreover, even though the load varies for both cases, the sinusoidal inverter output voltage can be tracked and maintained at 230 Vrms with a 50 Hz frequency within a few cycles from the instant that the load is changed, as well as a low total harmonic distortion voltage (THDv) content of 1.53% and 2.78%, respectively. This indicates that the controller proves its robustness and stiffness characteristics in maintaining the output load voltage at the desired value to supply the power for a variety of loads with a minimum THDv. [ABSTRACT FROM AUTHOR]

The purpose of this paper is to develop a control and regulation method for the input DC voltages of a 5-level neutral point clamping (NPC) active power filter (APF). This APF is applied for the enhancement of medium-voltage network power quality by compensation of harmonic currents produced by an induction motor speed variator. In the first part, the authors present a topology of a 5-level NPC voltage source inverter and its simplified space vector pulse width modulation (SVPWM) control strategy. In the second part, the control strategy of the 5-level pulse width modulation current rectifier is presented. In the third part, to remedy to instability problem of the input DC voltages of the APF, the authors propose the feedback control of the 5-level rectifier associated with a simplified SVPWM with the redundant vectors method for the 5-level APF. After that, the sliding mode regulator used to control the APF is developed. The application of the proposed control algorithm offers the possibility of stabilizing the DC voltages of the APF. The stable DC bus supply associated with the sliding regulator of the APF allows the obtainment of low-harmonic content network currents with unity power factor. The instability problem associated with the use of the multilevel APF is solved. The obtained results are full of promise for the use of the multilevel APF in medium-voltage and high-power applications. [ABSTRACT FROM AUTHOR]

Direct torque control (DTC) is known to produce fast responses and robust control in AC adjustable-speed drives. However, in the steady-state operation, notable torque, flux, and current pulsations occur. In this paper, nonlinear DTC of induction motor drives is presented based on a space vector pulse-width modulation scheme combined with the input-output feedback linearization technique. The variation of stator and rotor resistance due to changes in temperature or frequency deteriorates the performance of the DTC controller by introducing errors in the estimated flux linkage and the electromagnetic torque. This approach will not be suitable for high power drives such as those used in tractions, as they require good torque control performance at a considerably lower frequency. Finally, extensive simulation results are presented to validate the proposed technique. The system is tested at different speeds and a very satisfactory performance is achieved. [ABSTRACT FROM AUTHOR]

The Field Programmable Gate Array (FPGA) is an on field programmable device which can be designed for different applications. Various types of software are available for its synthesis. The cell placement depends upon the designing and programming languages used for FPGA. In this paper cell placement technique of FPGA architecture is analyzed for the application of Space Vector Pulse Width Modulation (SVPWM) technique used in speed control of an induction motor. The modulation pulses are produced due to the various components activated and their interconnection in Configurable Logic Blocks (CLBs). Few of its components are so analyzed to find out the reason for their desired output response. This survey has also been conducted to find the correlation of LUTs and formulation of output. [ABSTRACT FROM AUTHOR]

This paper presents a derived SEPIC/ZETA bidirectional converter (BDC) with reduced ripple in the noninverted output voltage. This converter is obtained by the fusion of unidirectional SEPIC and ZETA converters that ensures reduced ripple in the inductor currents. The optimal selection of duty ratio enables the proposed converter to operate either in SEPIC or ZETA mode under forward and reverse power ow. The presence of auxiliary circuit not only reduces the voltage stress on the switches by operating under zero voltage switching condition but also provides isolation between the input and the output ports. The operational principle and the stability of the proposed SEPIC/ZETA BDC have been analyzed under different modes of operation. To validate the performance of the proposed converter, the implementation is carried out using a field programmable gate array (FPGA)-based digital controlled prototype model. [ABSTRACT FROM AUTHOR]

In this paper, a new DC-link balancing method for a 7-level inverter fed by a photovoltaic system is proposed. The proposed redundant state technique is associated with selective harmonics elimination (SHE)-PWM instead of space vector (SV)-PWM. The switching angles related to the SHE are computed via the resultant theory method. Moreover, the study of this inverter is carried out on its equivalent matrix model. On the basis of this model, the link between the capacitor voltage, switching states, and load current is established. This allows understanding the switching redundancies' effect on the DC capacitor voltage balance. An algorithm is then developed to select the appropriate switching state, since there are 300 switching states and 720 unbalanced cases of the voltage capacitor. The proposed balancing method is tested in the case where the input DC inverter is provided by a photovoltaic generator (PVG) system and feeding an induction motor. The obtained results show that the 6 DC PVG capacitor voltages are kept balanced while cancelling the most undesirable harmonics row (5th, 7th, and 11th) in the inverter output voltage. Thus, using this cascade, photovoltaic supplying DC power can be amplified into high quality AC power. [ABSTRACT FROM AUTHOR]

This paper proposes a new space vector pulse width modulation (SVPWM) algorithm for multilevel inverters that achieves a minimum number of switch state changes in one sampling cycle in order to reduce switching losses. The algorithm can be implemented with minimum computational burden and it does not require any look-up tables. The essence of the technique is to exploit the redundancy of switching functions in the implementation of the voltage vectors and dividing the entire vector space into three sectors in which switching functions have some common features. Careful observations showed that these common features lend themselves to be expressed as closed form analytical equations that can be readily implemented in an embedded digital platform. The concepts are developed using a three-level inverter. However, generalized equations are given so that the proposed technique can be applied to inverters with an arbitrary number of levels. [ABSTRACT FROM AUTHOR]

The objective of this study is twofold: to approximate a model of a blimp, and to use this model to develop a setup to track a target with the blimp that is outfitted with a wireless camera and radio-controlled propellers. This article presents a powerful method to track any moving or stationary target with an unmanned aerial vehicle by combining the advantages of the proportional derivative (PD) controller, continuously adaptive mean shift (Camshift) algorithm, and pulse width modulation (PWM) method. As a result, it is demonstrated that a decent approximation of blimp behavior is sufficient when using a mathematical model that contains saturation in velocity and actuation. Additionally, a code for the proposed algorithm is developed to capture every frame sample with a frame grabber as a sensor in real time. Once the previously chosen object is tracked, the coordinate data (location information) are transferred to the controller to apply required pulses to DC motors on the blimp. In this paper, the proposed controller is outlined in two steps. Initially, one calculates a PD controller that fulfills the specifications of the mathematical model without saturation. Secondly, PWM is utilized to address the impact of nonlinearities. [ABSTRACT FROM AUTHOR]

This paper presents a three-dimensional (3-D) space vector pulse width modulation (SVPWM) technique via a 4 x 4 orthonormal transformation matrix that has been used as a new approach in controlling a three-phase four-leg voltage source inverter (VSI). A fully optimal digital control scheme for the closed-loop regulation of the three-phase four-leg VSI has been used to synthesize a sinusoidal waveform with the help of the proposed method. Discrete-time modelling of each phase has been obtained independently in abc reference frame, and its optimal controller has been designed using a predefined performance index. A DSP-based controlled three-phase four-leg prototype VSI has been designed to verify the proposed discrete time modelling and the control scheme. The simulations and the real-time experiments show that satisfactory results have been obtained for the modelling of the three-phase four-leg VSI in abc reference frame and the 3-D SVPWM technique via 4 x 4 orthonormal transformation matrix at 20 kHz switching frequency. [ABSTRACT FROM AUTHOR]

This paper presents a single-phase, cascaded half-full-bridge PWM multilevel inverter topology. It is made up of a main inverting H-bridge legs and level-clamping half-bridge circuits, each having its own dc source. The singlecarrier, multilevel PWM scheme is employed to generate gating signals for the power switches. The modulation scheme is hybridized to enable the output voltage of the proposed inverter configuration to inherit the features of switchingloss reduction from fundamental PWM and good harmonic performance from multiple sinusoidal PWM. Moreover, a simple base PWM circulation scheme is also introduced in this work to obtain a resultant sequential switching hybrid PWM (SSHPWM) circulation that balances power dissipation among the four power switches of the main H-bridge module. Operational principles with switching functions are given. For a modulation index of 0.9, the proposed inverter configuration was subjected to an R-L load and the respective numbers of output voltage level were synthesized. FFT analyses of the output voltage waveforms were carried out and the corresponding THD value of 13.16% was obtained. To verify the performance of the proposed inverter architecture, simulations and experiments were carried out on a 2.95 kW rated prototype of the proposed inverter for an R-L load and adequate results were obtained. [ABSTRACT FROM AUTHOR]

This paper proposes a new 3-phase multilevel inverter that is able to generate 7 levels in line-to-line voltage with only 11 switches. The inverter is formed from the 6-switch conventional full-bridge topology with the addition of 5 bidirectional switches in which 2 of them are shared among the three phases. By doing so, the number of power switches can be minimized, thus reducing the complexity in generating and controlling PWM signals. A novel voltage control scheme based on space vector modulation is developed by introducing a virtual vector in every sector of the vector hexagon. This is to overcome the difficulty in decomposing the reference vector in some parts of each sector. To evaluate the performance of the inverter and the effectiveness of the modulation technique in real time, a hardware prototype is constructed and the algorithm is implemented on a TMS320F2812 DSP. From the experimental results the optimum operating range of the inverter is determined to achieve the best output voltage possible with respect to quality and amplitude. [ABSTRACT FROM AUTHOR]

In this paper, a circuit topology for a synchronously rectified boost converter aimed to act as a power supply for a Class D H-bridge that would deliver up to 7 W peak power into an 8 Ω speaker is presented. The design is implemented in a submicron BCD process technology. Some of the challenges in this design are as follows. The first challenge was to optimise the design such that it would not cause on-chip power dissipation levels that would go beyond acceptable levels for Wafer Level Chip Scale Package (WLCSP), which is a commonly used package for space constrained applications in portable spaces. To address this issue, a Class G mode of operation to deliver multiple boost voltage levels has been proposed. Second, due to the chosen submicron BCD process lacking some devices such as zener diodes to clamp maximum voltages that active device gate-source and/or drain-source terminals in case of transient or normal operating conditions of the circuit, new ways of circuit implementation techniques have been come up with to prevent active devices from being damaged. One more important issue for handheld applications is that it is imperative to choose a small form factor (height and footprint) external inductor, which can also stand up to 4 A for this particular design. The new trend in small footprint power inductors is to use an iron powder core to keep the inductance constant. This creates a new problem with these types of inductors, whereby the series resistance of the inductor would increase with the frequency, which will increase the inductor AC core losses at switching frequencies of the switching converter. Trade-offs between total harmonic distortion plus noise and boosted voltage levels are also studied. [ABSTRACT FROM AUTHOR]

Maximum power point tracking (MPPT) algorithms are used to force photovoltaic (PV) modules to operate at their maximum power points for all environmental conditions. In artificial neural network (ANN)-based algorithms, the maximum power points are acquired by designing ANN models for PV modules. However, the parameters of PV modules are not always provided by the manufacturer and cannot be obtained readily by the user. Experimental measurements implemented in the overall PV system may be used to obtain the ANN dataset. One drawback of this method is that the generalization ability of the neural network usually degrades and some data reducing the effectiveness of the network may exist. A genetic algorithm can be used to automatically select the important data among all the inputs, resulting in a smaller and more effective dataset. In our study, a genetic algorithm is used to improve the MPPT efficiency of a PV system with induction motor drive by optimizing the input dataset for an ANN model of PV modules. A variable frequency volts-per-Hertz (V/f) control method is applied for speed control of the induction motor, and a space-vector pulse-width modulation (SV-PWM) method is used to operate a 3-phase inverter. Both simulation and experimental results are presented to demonstrate the validation of the method. [ABSTRACT FROM AUTHOR]

Presents an approach to demagnetization process of a pulse-width modulation forward converter (FC). Details on the resonant demagnetization forward converter (RDFC); Comparison of RDFC and FC; Conclusions.