Abstract: This paper proposes a hybrid selective harmonic elimination pulsewidth modulation (SHEPWM) scheme for common-mode voltage reduction in three-level neutral-point-clamped inverter-based induction motor drives. The scheme uses the conventional SHEPWM (C-SHEPWM) to control the inverter at high frequency (≥ 0.9 motor rated frequency) and uses the modified SHEPWM (M-SHEPWM) to control the inverter at low frequency. It also uses a scheme to ensure the smooth transition between the two SHEPWM schemes. As a result, at high frequency, the C-SHEPWM provides the required high modulation index for the motor, while at low frequency, when a passive filter is less effective for common-mode voltage reduction, the M-SHEPWM is used to suppress the common-mode voltage. Experimental results show that the proposed hybrid SHEPWM scheme could meet the modulation index need of the motor and reduce the common-mode voltage in the drive, and the two SHEPWM schemes could transition smoothly.

Abstract: This paper presents a new type of three-phase voltage source inverter (VSI), called three-phase dual-buck inverter. The proposed inverter does not need dead time, and thus avoids the shoot-through problems of traditional VSIs, and leads to greatly enhanced system reliability. Though it is still a hard-switching inverter, the topology allows the use of power MOSFETs as the active devices instead of IGBTs typically employed by traditional hard-switching VSIs. As a result, the inverter has the benefit of lower switching loss, and it can be designed at higher switching frequency to reduce current ripple and the size of passive components. A unified pulsewidth modulation (PWM) is introduced to reduce computational burden in real-time implementation. Different PWM methods were applied to a three-phase dual-buck inverter, including sinusoidal PWM (SPWM), space vector PWM (SVPWM) and discontinuous space vector PWM (DSVPWM). A 2.5 kW prototype of a three-phase dual-buck inverter and its control system has been designed and tested under different dc bus voltage and modulation index conditions to verify the feasibility of the circuit, the effectiveness of the controller, and to compare the features of different PWMs. Efficiency measurement of different PWMs has been conducted, and the inverter sees peak efficiency of 98.8% with DSVPWM.

Abstract: A new quasi-Z-source inverter called switched-inductor quasi-Z-source inverter was presented which employs a switched-inductor impedance network to couple power source and the invert main circuitCompared with the traditional quasi-Z-source inverter,the switched-inductor quasi-Z-source inverter increases the voltage conversion rations,has an obvious voltage boost ability,and for a given voltage conversion ration,a higher modulation index can be used to ensure a good output power qualityTheoretical analysis,the experimental and simulative results based on the simple boost control strategy and the third harmonic injection control strategy verify the superiority and rationality of the new quasi-Z-source inverter and demonstrate the features of the third harmonic injection control strategy

Abstract: This paper presents a five-level diode-clamped pulse width-modulated (PWM) inverter intended for a medium-voltage motor drive with a constant-torque load but no regenerative braking. It is applicable to drilling rigs, extruders, and rubber mixers. The power conversion system consists of a three-phase six-pulse diode rectifier, a five-level diode-clamped PWM inverter, and a dc- voltage-balancing circuit including a single coupled inductor. The five-level inverter is characterized by injecting a common ninth-harmonic zero-sequence voltage on each of the three-phase reference voltages in a low-modulation-index region. This injection contributes not only to mitigating magnetic-flux fluctuation of the coupled inductor but also to making uniform the power losses produced by eight insulated-gate bipolar transistor modules per leg. In addition, the dc-voltage-balancing circuit introduces a control method capable of reducing an amplitude of magnetic flux of the coupled inductor. The combination of this control method and the ninth-harmonic zero-sequence voltage injection keeps the peak value of the magnetic flux within its designed value.

Abstract: The matrix converter is a single-stage ac-ac power conversion device without dc-link energy storage elements. Any disturbance in the input voltages will be immediately reflected to the output voltages. In this paper, a modified space vector modulation strategy for matrix converter has been presented under the abnormal input-voltage conditions, in terms of unbalance, nonsinusoid, and surge (sudden rising or sudden dropping). By using the instantaneous magnitude and phase of input-voltage vector to calculate the voltage modulation index and input-current phase angle, this modified modulation strategy can eliminate the influence of the abnormal input voltages on output side without an additional control circuit, and three-phase sinusoidal symmetrical voltages or currents can be obtained under normal and abnormal input-voltage conditions. The performance of the input currents is analyzed when the matrix converter uses different modulation strategies. Some numerical simulations are presented to confirm the analytical results. Tests are carried out on a 5.5-kW matrix converter prototype. Experimental results verify the validity of the proposed strategy.

Abstract: Recovering even a small amount of information from a broadband radio frequency (RF) environment using conventional analog-to-digital converter (ADC) technology is computationally complex and presents significant challenges. For sparse or compressible RF environments, an alternate approach to conventional sampling is analog-to-information (A2I) to enable sub-Nyquist rate sampling based on compressive sensing (CS) principles. This paper presents the Nyquist Folding Receiver (NYFR), an efficient A2I architecture that folds the broadband RF input prior to digitization by a narrowband ADC. The folding is achieved by undersampling the RF spectrum with a stream of short pulses that have a phase modulated sampling period. The undersampled signals then fold down into a low pass interpolation filter. The pulse sample time modulation induces a corresponding phase modulation on the received signals that is scaled by an integer modulation index that varies with the Nyquist zone (i.e., fold number), allowing the signals to be separated based on the measured modulation index. Unlike many schemes motivated by CS that randomize the RF prior to digitization, the NYFR substantially preserves signal structure. This enables information recovery with very low computational complexity algorithms in addition to traditional CS reconstruction techniques. The paper includes a comparison of seven other A2I architectures with the NYFR.

Abstract: This paper presents a new fixed-carrier-frequency random pulsewidth modulation method, where a new type of carrier wave is proposed for modulation. Based on simulations and experimental measurements, it is shown that the spread effect of the discrete components from the motor current spectra and acoustic spectra is very effective and is independent from the modulation index. The flat motor current spectrum generates an acoustical noise close to the white noise, which improves the acoustical performance of the drive. The new carrier wave is easy to implement digitally, without employing any external circuits. The modulation method can be used in both open- and closed-loop motor control applications.

Abstract: We propose and analyze a photonic-assisted periodic triangular-shaped pulses generator, in which a continuous wave (CW) laser is connected to a dual electrode Mach-Zehnder modulator (De-MZM), and then the De-MZM is connected with a normal dispersion fiber or element. A radio frequency (RF) sinusoid directly drives the De-MZM to obtain optical subcarrier modulation with optical carrier suppression. By carefully setting the physical parameters, the generated harmonics of optical intensity can be corresponding to the Fourier components of typical periodic triangular pulses. Numerical simulations reveal that modulation index must be set to 2.305 and bias voltage drift must be within a range from from the minimum transmission of the De-MZM. In addition, the dispersion must be set correctly to suppress the primary distortion of 4th order harmonics.

Abstract: In the standard selective harmonic elimination (SHE)-pulse-width modulation (PWM) technique for multilevel converters, in order to eliminate N 2 1 non-triplen odd harmonics of the ac-side voltage and to regulate the output voltage amplitude, N switching angles need to be determined. Therefore a set of N non-linear transcendental equations must be solved to find the desired switching angles for any value of the modulation index. However, solutions to the non-linear equations are not feasible for the entire range of modulation region. This study proposes a modified SHE-PWM technique that extends the standard modulation region and generates a stepped voltage waveform within a wide range of modulation indices. As compared with the standard SHE-PWM technique, the constraint associated with elimination of the harmonic with the highest order is relaxed and the corresponding equation is disregarded. Consequently, a reduced number of transcendental equations are employed to find the N desired switching angles. Since the switching frequency remains constant, converter's efficiency does not change. However, in order to produce a pure sinusoidal waveform, a higher order filter is required. A genetic algorithm is used to solve the equations and to determine the switching angles. The proposed technique can generate stepped voltage waveforms with a wide range of modulation indices. Performance of the proposed SHE-PWM technique for a seven-level cascaded H-bridge converter, based on simulation studies, is evaluated and experimentally verified.

Abstract: In this paper, an input power factor compensation method is proposed for a high-power pulse-width-modulated current-source-converter (CSC)-fed permanent magnet synchronous motor (PMSM) drive system. The proposed method is based on controlling the d-axis stator current component in the field-oriented control (FOC) scheme of the drive system. The CSC-fed PMSM drive system and its FOC scheme are first introduced. Then, the relationships between the machine side, dc-link, and the line side are investigated. Based on the analysis, a new d-axis stator current control scheme that can ensure unity input power factor for the operating speed range is proposed. The main feature of the proposed scheme is to compensate the line-side power factor without the need for modulation index control in either the rectifier or the inverter. Therefore, offline Selective Harmonic Elimination (SHE) modulation schemes can be implemented on both line- and machine-side converters to minimize the total harmonic distortion. This results in reduced switching frequency and reduced switching losses. Simulation results for a 2.44 MW medium-voltage system and experimental results from a low-voltage 6.5 kW IPM motor drive are provided to verify the effectiveness of the proposed compensation method.

Abstract: A new hybrid five-level inverter topology with common-mode voltage (CMV) elimination for induction motor drive is proposed in this paper. This topology has only one dc source, and different voltage levels are generated by using this voltage source along with floating capacitors charged to asymmetrical voltage levels. The pulsewidth modulation (PWM) scheme employed in this topology balances the capacitor voltages at the required levels at any power factor and modulation index while eliminating the CMV. This inverter has good fault-tolerant capability as it can be operated in three- or two-level mode with CMV elimination, in case of any failure in the H-bridges. More voltage levels with CMV elimination can be realized from this topology but only in a limited range of modulation index and power factor. Extensive simulation is done to validate the PWM technique for CMV elimination and balancing of the capacitor voltages. The experimental verification of the proposed inverter-fed induction motor is carried out in the linear modulation and overmodulation regions. The steady-state and transient operations of the drive are verified. The dynamics of the capacitor voltage balancing is also tested. The experimental results demonstrate that the proposed topology can be considered for industrial drive applications.

Abstract: This paper presents a dc-link voltage ripple compensation method for flying-capacitor (FC)-based active neutral-point-clamped multilevel converters operating under selective harmonic elimination pulsewidth modulation. The method is based on feedforward modification of the modulation index according to the ripple on the dc-link voltage, effectively altering the switching control functions. The low-order harmonics in the output due to the presence of the dc-link ripple are eliminated. In addition, a control strategy that actively regulates the flying capacitor voltages of each phase to the reference value and controls the neutral point voltage deviation is implemented. The performance of the dc ripple harmonic compensation method and regulation strategies are evaluated through simulation and experimental results from a three-phase, five-level laboratory prototype.

Abstract: This paper presents an improved asymmetric space vector modulation (ASVM) for two-level voltage source converters (VSCs) when the switching frequency is as low as nine times of line frequency. By adding two pulses in each line cycle when the fundamental voltage crosses zero, the total harmonic distortion (THD) of output current can be reduced significantly. The penalty of additional switching loss is very limited for high power factor operation. The applications of the improved ASVM in a single VSC or in two interleaved VSCs are shown, respectively. With the optimization of the duration and position of the additional pulses, the ac current THD can be reduced to as low as 50% for single VSC and even lower to less than 25% for interleaved VSCs systems. Such THD reduction has close relationship with space vectors' position, modulation index, and interleaving angle. Improved ASVM can also reduce the amplitude of circulating current in the interleaved VSCs, leading to smaller interphase inductors. Finally, the weights of total inductors needed to meet the same THD requirement are compared to demonstrate the benefits of improved ASVM when different pulsewidth modulation schemes are used. The analysis results are verified by experiments on a demo system.

Abstract: A detailed analysis of a seven-level selective harmonic elimination pulse-width modulation method suitable for multilevel DC-AC converters is presented in this study. Solution trajectories that cover the normal range of modulation indices typical for the operation of multilevel inverters are documented. The properties and characteristics of these solutions with regard to the distribution of switching instants (angles) to the levels of the waveform are also reported. Selected simulation and experimental results are included for both steady state operation and under dynamic changes of the modulation index and the output frequency. The results confirm the effectiveness of the method.

Abstract: Spread-spectrum continuous-phase-modulated (SS-CPM) signals are investigated with application to satellite navigation. In particular, focus is devoted to the special subclasses of SS-CPM with semi-integer modulation index h greater than one. This constitutes a novelty with respect to traditional navigation signal design on one hand (which is based on direct-sequence spread-spectrum (DS-SS) signals with rectangular pulse) and with traditional communication SS-CPM with h>;1 on the other. Main output is that setting the modulation index h<;1 to semi-integer values allows the SS-CPM signals to behave like having subcarriers, exactly in the same way as it happens for the binary offset carrier (BOC) modulation. The main advantage is that CPM ensures a constant envelope at the transmission side, thus being appealing when these features are required at the system level. After a description of signal properties, focus is devoted to ranging code synchronization, by exploitation of the theory on time-delay estimation (TDE). A few delay-lock loop schemes are also presented, based on an offset quadrature phase-shift keying (OQPSK) approximation of the signal at the receiver side, achieved by Laurent's decomposition at the receiver side. Proposed loops performance are analyzed in terms of Cramer-Rao bound (CRB), rms tracking error, and multipath robustness. An application of SS-CPM for a two-rate-service scheme is proposed.

Abstract: The pulse width modulation (PWM) inverter is widely used for the control of motors. We showed that the iron loss under PWM inverter excitation is affected by the impedance of the excitation circuit. The dc voltage of PWM inverter, which is widely used, is constant and the control of motor is carried out by changing the modulation index. Therefore, the evaluation of iron loss under PWM excitation with constant dc voltage is necessary in order to investigate the behavior of iron loss in an actual motor. In this paper, we measured iron losses of non-oriented electrical steel sheets under the shingle-phase full-bridge PWM inverter excitation and examined the influence of modulation index m, carrier frequency fc and dc voltage Vdc on the iron losses. It is shown that the iron loss under PWM inverter excitation can be reduced when dc voltage Vdc is reduced and modulation index m is increased.

Abstract: This paper describes a two-phase separately randomized pulse position pulsewidth modulation scheme that can obtain the randomization effect on the switching noise spectra over the entire modulation index ( M) range. In the proposed scheme, the zero vector is selected as V(1 1 1) when M ≥ 0.7 and as V(0 0 0) when M <; 0.7. For the validity of the proposed method, a 16-bit microcontroller SAB-C167 was used and the experiments were performed on a 1.5-kW three-phase induction motor which is coupled an eddy current brake load. The switching noise was measured in the anechoic room using a RION SA-01. Experiment results were measured at a distance of 0.15 m away from the side of induction motor. The experimental results show that the harmonic spectra spread over a wideband area, and the switching noise for all the M is reduced by the proposed method.

Abstract: Multilevel drive supply can be realised in two different ways, by using either a conventional multilevel single-sided supply configuration or with a dual-inverter supply topology. The second structure is simpler for practical realisation, since the problem of capacitor voltage balancing does not arise. This paper develops a space vector PWM (SVPWM) algorithm for the dual-inverter six-phase supply, based on two two-level six-phase voltage source inverters (VSIs), feeding a symmetrical six-phase load. In the algorithm, each inverter is controlled using SVPWM technique that was previously developed for a single-sided supply configuration. A multilevel output voltage is produced for a certain range of modulation index. The performance of the algorithm is verified through simulations and experiments.

Abstract: This study presents space vector-based quasi-two-level operation of a diode-clamped multilevel inverter which improves dc link utilisation and output voltage quality, and avoids the dc link capacitor voltage balancing problem experienced with standard multilevel operation. Beside a review of quasi-two-level operation and the capacitor voltage balancing method, the study presents a detailed discussion on the implementation of space vector modulation and the selection of switching sequence for a five-level inverter. Additionally, the condition for maximum theoretical modulation index for space vector modulation is established. A prototype five-level diode-clamped inverter is to experimentally validate the approach. Also this study extends the concept of quasi-two-level-to-three-level operation of the diode-clamped multilevel inverter in order to address the shortcomings experienced with quasi-two-level operation, such as low waveform quality and high switching losses. The validity of three-level inverter operation is confirmed experimentally on a prototype of a five-level diode-clamped inverter. The study also highlights the limitations of three-level operation of a diode-clamped multilevel inverter.

Abstract: In this paper, a new interface configuration is proposed for connecting a microsource to a weak utility. The proposed configuration simultaneously conditions the quality of the power supplied to the microgrid loads. This system employs a recently introduced reduced switch count dual-output inverter in a so-called equal frequency mode which offers its best operation features such as maximum dc bus voltage utilization and minimum device ratings. Compared to the counterpart system, the proposed configuration enjoys an integrated structure and uses less number of semiconductor switches. Moreover, it retains the desirable features of the conventional system such as ability to compensate unbalanced/sagged utility and to supply three-phase unbalanced loads with balanced and ceaseless voltage. The proposed system is introduced and its carrier-based modulation scheme is elaborated. Subsequently, a detailed study on the maximum achievable modulation index under different working conditions is carried out. The report concludes with a discussion on control of the system and its controller design. The validity of operation of the proposed system is verified through simulation.

Abstract: This paper presents a new variation of the selective harmonic elimination pulse width modulation (SHE-PWM) technique applied to cascaded multilevel converter based STATCOM system. The DC voltage levels of the cascaded H-bridge converter are assumed variables, hence increasing the degrees of freedom in the formulation of the problem. This approach allows additional harmonics to be controlled when compared to the existing family of SHE-based multilevel control for the same converter configuration. The proposed modulation method also shows an interesting feature of fixed switching angles across the entire range of the modulation index, which alleviates the problem of online implementation. The proposed method solely relies on the availability of the variable DC voltage levels, which can be obtained by different topologies. For simplicity, a DC/DC buck converter is utilized in this paper to provide a variable DC voltage levels required by the H-bridges of the five-level converter. The STATCOM system is integrated with a current controller along with a voltage control loop for the buck converter to meet the reactive power demand of different loading conditions. The method is further compared with the conventional carrier-based pulse width modulation (CB-PWM) to show its improved characteristics. The effectiveness and the theoretical analysis of the proposed approach and validated through simulation studies.

Abstract: In recent years, Z-source inverters (ZSI) have been proposed as an replacement power conversion concept which it has both voltage buck and boost abilities. In addition, ZSI doesn’t require dead-time to protection short circuit at two switches any of the same phase leg in the inverter bridge and to achieve optimal harmonic of current, voltage. This paper presents two different control methods (CM) for ZSI. The aim of this study to compare between two modulation methods, there are modi?ed space vector pulse width modulation method (MSVM) and the simple boost control (SBC) about the unique harmonic performance features, the total average and peak switching device power of the inverter system. In addition, this paper also analyzes about the ability exceed modulation index in linear region of two CM using MATLAB/Simulink.

Abstract: A novel scheme to generate coherent and frequency-lock optical subcarriers is proposed and experimentally demonstrated. 53 subcarriers with 12.5 GHz spacing and less than 10 dB power fluctuation are generated by cascading two stages of phase modulators, which are driven by 25 and 12.5 GHz clock sources at different modulation depths, respectively. The modulation index and phase difference of two stage phase modulation are theoretically and experimentally investigated. The flattening spectrum of the optical subcarriers is achieved by optimizing the clock phase relationship among the RF driving sources at both stages.

Abstract: We performed an experimental investigation on a Q-switched, mode-locked laser based on the combination of passive Q switching and active mode locking. This study was carried out using an erbium fiber ring laser incorporating an active mode locker employing a fast Si-based variable optical attenuator and a passive Q switch based on a carbon nanotube saturable absorber. It was found that stable Q-switched, mode-locked pulses can be readily generated when using a particular cavity modulation index and pump power. It was also found that our scheme can easily alter the operating regime among the Q switching, Q-switched mode locking, and mode locking by simply controlling the cavity modulation index and/or the pump power. For this particular laser configuration, the cavity modulation index and pump power operating conditions have been experimentally analyzed for three laser operating regimes.

Abstract: This work presents a new power decoupling technique for grid-tied current-source inverter (CSI), in grid-connected photovoltaic (PV) systems. Single-phase converters have low-frequency power ripple in the dc-link. The proposed topology is intended to reduce the low frequency power ripple by using an active power filter (APF) on the dc-link, based on a bidirectional buck-boost converter, which provides compensating voltage in a very simple but effective way. The advantages of this configuration are: a) dc-link ripple minimization, b) passive components size reduction, c) improvement of maximum power point tracking (MPPT) performance; and d) compatibility with full range of CSI modulation index (0∼1).

Abstract: This paper proposes a three-phase quasi-Z-source matrix converter based induction motor adjustable-speed drives The quasi-Z-source unique impedance network is utilized to overcome the limitation of the voltage gain of traditional matrix converter The quasi-Z-source matrix converter can provide buck-boost function by controlling shoot-through duty ratio and modulation index Analysis base on state-space equation shows the relationship among the shoot-through duty ratio and boost factor as well as voltage gain Also, the proposed speed control method is able to change the motor speed from zero to the rated speed with the full load torque The operating principle and system analysis are presented in detail The simulation results validate the proposed quasi-Z-source matrix converter based adjustable speed drives

Abstract: The paper proposes a new modulation technique which can reduce the current distortion and extend the current reconstruction range for three-phase inverter using only DC-link sensor. The proposed PWM technique is a hybrid method which consists of space vector modulation method and the PWM method without using null switching states. The former provides low current distortion, however it is with narrower current reconstruction range. In contrast, the later extends the current reconstruction range at the cost of higher current distortion. For the proposed method, in the measurable region of space vector modulation method, space vector modulation is used to reduce the current distortion. Moreover, as the modulation range is out of that measurable region, the PWM method without using null switching states is applied to extend the current re-construction range. Furthermore, the current reconstruction limitation using only DC-link sensor is analyzed. The analysis shows that reduction of PWM switching frequency and acquisition time can extend the current re-construction range. Comparison of experimental results derived from an FPGA-based controlled inverter is included. It will be demonstrated that using the proposed hybrid PWM technique the three-phase current signals of inverter can be reconstructed even under very low modulation index range while providing low current harmonic distortion of inverter output.

Abstract: This paper presents a fully integrated system for implanted micro-system devices with e±cient power and data transfer based on amplitude shift keying (ASK) modulation techniques. A proposed e±cient class-E power amplier is presented. The design presents a full transcutaneous inductive powering system to transfer power and data from an outside human body to implanted devices such as implanted microsystems to stimulate and monitor the nerves and muscles with low band frequency of 13.56MHz according to the industrialscienticmedical (ISM) band to avoid the tissue damage. A novel ASK demodulator powered with 1.9V is proposed with a power recovery system. The modulation index is 13% and the modulation rate 7.3% with data rate 1Mbit/s, and with power e±ciency 66%. The system has been designed using 0.35-� m fabricated CMOS technology. The mathematical model is given and the design is simulated using OrCAD PSpice 16.2 software tool and for real-time simulation, the electronic workbench MULISIM 11 has been used to simulate the class-E power amplier.