Abstract: A high performance PWM algorithm with reduced common mode voltage (CMV) and satisfactory overall performance is proposed for three-phase PWM inverter drives. The algorithm combines the near state PWM (NSPWM) method which has superior overall performance characteristics at high modulation index and MAZSPWM, a modified form of the active zero state PWM method (AZSPWM1), which is suitable for low modulation index range of operation. Since AZSPWM1 has line-to-line voltage pulse reversals with small zero-voltage time intervals, in its naive form it causes overvoltages, in particular in long cable motor drive applications. Obtained by re-organizing the duty cycles of the utilized voltage vectors of AZSPWM1, MAZSPWM has sufficiently long zero-voltage time intervals between pulse reversals such that overvoltages are avoided. The combined algorithm performs satisfactorily throughout the inverter operating range and the transition from NSPWM to MAZSPWM and vice versa is seamless. The performance of the proposed algorithm is proven by theory, computer simulations, and detailed laboratory experiments. The paper also shows that the proposed reduced CMV PWM algorithm is effective in reducing the motor leakage current and it is most beneficial when a small common mode inductor is included in the drive.

Abstract: This paper proposes a trinary hybrid 81-level multilevel inverter for motor drive. Benefiting from the trinary hybrid topology of the inverter, 81-level voltages per phase can be synthesized with the fewest components. Bidirectional DC-DC converters are used not only to inject power to the DC links of the inverter but also to absorb power from some DC links in cases with a lower modulation index. The higher bandwidth of DC-DC converters alleviates the ripples of DC-link voltages caused by the load current. The space vector modulation used here, which selects voltage vectors that generate a zero common-mode voltage in the load, works at a low switching frequency. With up to 81-level voltages per phase, the total harmonic distortion is small, and the relationship between the fundamental load voltage and the modulation index is precisely linear. A vector controller is used to control an induction motor, which results in a high dynamic response for speeds or torques. The performance of the proposed inverter for the motor drive is confirmed by simulation and experiment.

Abstract: We comprehensively investigate three modulation techniques for the generation of millimeter-wave (mm-wave) using optical frequency quadrupling with a dual–electrode Mach-Zehnder modulator (MZM), i.e. Technique-A, Technique-B and Technique-C. For Technique-A, an RF signal drives the two electrodes of the MZM with maximum transmission bias, and this MZM is used for both the mm-wave generation and signal modulation. Technique-B is the same as Technique-A, but 180° phase shift between the two electrodes is applied. Technique-C is the same as Technique-B, but the MZM is only used for the mm-wave generation without signal modulation. It is found that Technique-B and Technique-C are better for frequency quadrupling than frequency doubling, tripling and sextupling. Both theoretical analysis and simulation show that the generated mm-wave suffers from constructive/destructive interaction due to fiber chromatic dispersion in Technique-A. However, the generated mm-wave is almost robust to fiber chromatic dispersion in Technique-B and Technique- C. It is found that Technique-C is the best in the quality of the generated mm-wave, especially when poor optical filtering is used. In addition, we develop a theory for calculation of Q-factor in an mm-wave over fiber system using the three modulation techniques for mm-wave generation. We consider an RF at 7.5 GHz and obtain an mm-wave at 30 GHz as an example, i.e. a frequency quadrupler. We evaluate the generation and distribution in terms of system Q-factor. The impact of RF modulation index, chromatic dispersion, MZM extinction ratio and optical filtering on Q-factor are investigated.

Abstract: In this letter, we analyze the transmitter design for coherent optical orthogonal frequency-division multiplexing (CO-OFDM) employing predistortion. Digital clipping and digital predistortion processes are introduced to the radio frequency OFDM transmitter to compensate the nonlinearity effect introduced by the optical in-phase/quadrature modulator. We first provide a detailed description of signal processing involved in digital clipping and predistortion. We then carry out a numerical simulation to identify the performance dependence on clipping ratio, digital-to-analog converter (DAC) resolution, and modulation index. We find that for quadrature phase-shift keying modulation, 4-bit DAC resolution is sufficient for the CO-OFDM transmitter to incur only 0.3-dB penalty while maintaining the excess modulation insertion loss less than 6.0 dB. The performance improvement of the predistorted transmitter over nonpredistorted one is also discussed.

Abstract: In the fields of wireless bioelectronics implants and sensor network systems, amplitude shift keying (ASK) is one of the most commonly used schemes employed to modulate the baseband signal with reference to the intermediate or even the carrier frequency. In this study, a demodulator architecture capable of dealing with most of the previous limitations in an ASK-utilized medical implant, especially in want of being powered through wireless delivering, is proposed. It features the abilities of working on a very small modulation index and being provided without any R/C component(s) inside by means of a self-sampling scheme. The design has been implemented in an 18-mum CMOS process. The demodulator circuit occupies a die size of merely 32.3 times 14.5 mu m2. Analytic results from both simulated gradation and fabricated chips show that the proposed circuit can operate at a carrier of 2 MHz and achieve a modulation rate of up to 50%. The results also demonstrate that the presented work can still perform a proper demodulation even with a modulation index beneath 5.5%. An average power of approximately 336 muW was confirmed in return for the remarkable advantages. All aspects regarding the design, including a review of the prior arts, system consideration, circuit description, and analyses from simulation phase to actual measurement, are presented in detail.

Abstract: A video encoding apparatus includes a predictor to perform prediction for an input image signal to generate a prediction image signal, a subtractor to calculate a difference between the input image signal and the prediction image signal to generate a prediction residual signal, a transformer to transform the prediction residual signal to generate a transform coefficient, a modulating unit to perform modulation on a quantization matrix to obtain a modulated quantization matrix, a quantizer to quantize the transform coefficient using the modulated quantization matrix to generate a quantized transform coefficient, and an encoder to encode the quantized transform coefficient and a modulation index to generate encoded data.

Abstract: In this paper, a loss reduction and DC link current minimization strategy for a high power current source inverter (CSI) fed drive is proposed. The proposed strategy consists of an inverter maximum modulation index control scheme and a flux optimization algorithm. Specifically, in the inverter modulation index control, the CSI modulation index is kept at the maximum value while the current source rectifier (CSR) is used to regulate a reduced variable DC link current and therefore to control the motor current magnitude. This control scheme can effectively reduce the dc link current and at the same time improve the line side and motor side harmonics. On the other hand, for the optimized flux control, the relationship between the rotor flux and the dc link current is first thoroughly investigated. Based on this analysis, the DC link current from the maximum inverter modulation index control can be further minimized by optimizing the rotor flux according to system variables such as the motor speed, the applied torque and the motor side capacitor size. With the proposed dc current minimization strategy, the drive current rating, semiconductor device losses and the drivepsilas DC link losses can be reduced. Both simulation and experimental results on a 4.16 kV 600 hp CSI fed drive system are obtained to verify the effectiveness of the proposed strategy.

Abstract: This paper presents a complete analysis studying the impact of interleaving on harmonic current in DC passive components for paralleled three-phase voltage-source converters (VSCs). The analysis performed considers the effects of modulation index, displacement angle, and the interleaving angle. The results show that the harmonic current in DC capacitor depends strongly on displacement angle, and to minimize the harmonic current interleaving angle should vary from pi/2 to pi as the displacement angle varies from zero (unity power factor) to pi/2 (zero power factor). The modulation index can also affect the impact much. Because of the limit of the pages, the impact of interleaving on harmonic current in AC boost inductor is only shown in principle. All the analysis is based on an example system containing two VSCs. However the proposed analysis method in frequency domain is easily expandable for multiple paralleled VSCs. Experimental results have verified the analysis results.

Abstract: This paper presents a comprehensive analysis studying the impact of interleaving on harmonic currents and voltages on AC side of parallel three-phase voltage source converters (VSCs). The analysis performed considers the effects of modulation index and the interleaving angle. Based on the analysis, the impact of interleaving on the design of AC passive components such as AC line inductor and EMI filter are discussed. The results show that interleaving has the potential benefit to reduce AC passive components. To maximize such benefit, the interleaving angle should be optimized according to the system requirements including THD limit, ripple limit or EMI standards in different operation conditions such as modulation index and PWM strategy. All the analysis is based on an example system containing two two-level VSCs. However the proposed analysis method in frequency domain can be easily extended to multiple VSCs systems with other topologies. Experimental results have verified the analysis results.

Abstract: Large-signal analog intensity modulation of semiconductor lasers (SLs) is characterized based on numerical integration of the rate equations. The modulation dynamics are classified into seven types with regular and irregular signals. The classification is made in terms of the time trajectory of the laser intensity, phase portrait, and fast Fourier transform (FFT) spectrum. The operating region of each type is defined in a diagram of the modulation index versus modulation frequency. The accuracy of applying the approximate small-signal analysis to study analog modulation is assessed. The validity of identifying the dynamic types by the large-signal modulation response is examined. The laser emits continuous and regular signals under weak modulation. When the modulation index exceeds one half, the laser emits picosecond-pulses. Under strong modulation with frequencies around the relaxation frequency, both continuous and pulsed signals exhibit period-doubling.

Abstract: This paper searches for the best possible switching sequence in a multilevel multi-phase inverter that gives the lowest amount of voltage harmonics. A modified discrete particle swarm (MDPSO) algorithm is used in an attempt to find the optimal space vector modulation switching sequence that results in the lowest voltage THD. As with typical PSO cognitive and social parameters are used to guide the search, but an additional mutation term is added to broaden the amount of area searched. The search space is the feasible solutions for the predetermined vectors at a given modulation index. Comparison of the MDPSO algorithm to an integer particle swarm optimization (IPSO) is presented for all three modulation indices tested. The resulting switching sequences found show that the MDPSO algorithm is capable of finding a minimal THD solution for all modulations indices tested. The MDPSO algorithm performed better overall than the IPSO in terms of converging to the best solution with significantly lower iterations.

Abstract: This investigation presents the measurement results of acoustic noise and vibration of a model three-phase three-limb transformer core under sinusoidal and PWM voltage excitation for assigned value of modulation index with switching frequency from 1 kHz to 3 kHz at no-load condition. Results show that the acoustic noise decreased around 2 (dBA) with increasing switching frequency. However, magneto-mechanical resonance phenomenon was observed at 3 kHz vibration frequency, which could cause excess acoustic noise under some excited conditions.

Abstract: A class-B microwave-photonic link using optical frequency modulation (FM) and fiber-Bragg gratings (FBGs) is analyzed and results verified with measurements. Input voltage is converted linearly to FM, and this FM is converted by each FBG to intensity modulation. For small FM index beta, the signal increases as beta3, becoming linear in beta with a frequency offset or carrier leakage, and third-order distortion resulting from the detection process is shown to be worse than that obtained using a Mach-Zehnder intensity modulator at the same modulation index. For large beta( > 10), third-order distortion approaches zero and ideal class-B operation is predicted, and the only shot noise and relative intensity noise (RIN) added is that which arises from the detected signal power.

Abstract: An image encoding device includes: a predictor which predicts an input image signal and generates a predicted image signal; a subtractor which calculates a difference between the input image signal and the predicted image signal to generate a predicted residual signal; a converter which converts the predicted residual signal to generate a conversion coefficient; a modulation unit which modulates a quantization matrix to obtain a modulated quantization matrix; a quantizer which quantizes the conversion coefficient by using the modulated quantization matrix to generate a quantized conversion coefficient; and an encoder which encodes the quantized conversion coefficient and the modulation index to generate encoded data.

Abstract: This paper explores control methods for the current-fed Z-source inverter and their relationships of current boost versus modulation index. A maximum boost control is presented to produce the maximum current boost (or current gain) under a given modulation index. The control method, relationships of current gain versus modulation index and current stress versus current gain are analyzed in detail and verified by simulation.

Abstract: Delta modulation (DM) is simple and has characteristics advantageous to the operation of cyclo-inverter. Analysis and implementation of delta modulated switching is presented in this paper both for cyclo-inverter as well as for cyclo-converter. Simulation results are shown for single-phase to single-phase centre tapped transformer configuration using SIMULINK software. This confirms a validity of the delta modulation technique for step up as well as step down operation. It has been found that total harmonic distortion (THD) is low for modulation index lying from 0.75 to 1.5. Any further increase or decrease in modulation index increases the harmonics in the converter. The output improves with increasing sampling frequency above 2 KHz where THD has been found to be as low as 4% for cyclo-inverter and 2% for cycloconverter.

Abstract: We discuss a new method to design traveling-wave electrooptic modulators with controlled frequency responses using nonperiodically polarization-reversed structure. Using our method, the frequency responses of both magnitude and phase of modulation index are controllable. Several electrooptic modulators for advanced modulation formats such as duobinary modulation and wideband single-sideband modulation are proposed.

Abstract: Existing space-time codes have focused on multiple- antenna systems with linear modulation schemes such as phase- shift keying and quadrature amplitude modulation. Continuous phase modulation (CPM) is an attractive scheme for digital transmission because of its constant envelope which is needed for power efficient transmitters. Recent research has shown that space-time coded CPM can achieve transmit diversity to improve performance while maintaining the compact spectrum of CPM signals. However, these efforts mainly combine space- time coding (STC) with CPM to achieve spatial diversity at the cost of a high decoding complexity. In this paper, we design space-time block codes (STBC) for binary CPM with modulation index h = 1/2 and derive low-complexity receivers for these systems. The proposed scheme has a much lower decoding complexity than STC CPM with the Viterbi decoder and still achieves near-optimum error performances.

Abstract: Systems, methods, and computer program products for automatically adjusting the modulation index of a wireless smart device reader are disclosed. According to one aspect, the subject matter described herein includes a method (performed at a wireless smart device reader) that includes receiving a signal from a wireless smart device. A parameter of the signal is determined. The method also includes determining at least one transmission parameter using the parameter of the signal. The transmission parameter(s) is applied to a transmitter of the wireless smart device reader in order to adjust the modulation index of the transmitter.

Abstract: This paper proposes a novel scheme using a superconducting magnetic energy-storage (SMES) unit to simultaneously perform both power-flow control and transient stability improvement of a large-scale wind power generation system (WPGS) subject to severe wind fluctuations. A complete system model based on a synchronously rotating reference frame for the studied WPGS combined with the proposed SMES unit is derived and established. The output of the proposed SMES unit is properly controlled by adjusting both modulation index and phase angle of a bi-directional power converter to achieve the required simultaneous P-Q control. For demonstrating the effectiveness of the proposed SMES unit on performance of the studied WPGS, calculated operating conditions under different values of modulation index and phase angle as well as time-domain nonlinear-model transient simulations under disturbance conditions are both performed. It can be concluded from the simulation results that the proposed SMES unit can effectively control the desired power-flow conditions and render better damping characteristics to enhance transient stability of the studied WPGS under various wind fluctuations.

Abstract: In this paper, a novel voltage balance control scheme with carrier-based implementation is proposed for the non-regenerative three-level boost (or Vienna type) rectifier. The dc-link voltage balance mechanism for the non-regenerative three-level boost rectifier is first studied from the space vector standpoint and then an optimal zero sequence component is found to guarantee zero neutral point current injection. Based on this analysis the voltage balance control is designed with the combination of a feed forward component and a feedback loop, which can be easily incorporated into the conventional multi-loop d-q controller and then implemented by carrier-based modulation. The impact of the optimal zero sequence on the feasible modulation index is also analyzed. The proposed approach features great simplicity and good dc link voltage balance regulation. Both simulations and experiments are carried out and the results verify the feasibility of this proposed control algorithm.

Abstract: The detection issues of ultrawideband (UWB) signals depend on the type of modulation scheme that is used during the transmission. Cross-modulation interference (CMI) is a problem that is specific to UWB pulse-position-modulation (PPM) signaling. In this paper, the effects of CMI on the performance of noncoherent UWB receivers are analyzed. The probabilities of error for transmitted-reference (TR) and energy detector (ED) receivers in the presence and absence of CMI are derived. Optimal and suboptimal CMI avoidance algorithms, which are based on novel acquisition techniques, are proposed for Rake receivers. The results show that the performance degradation in both receivers, which is due to the CMI effects, can be significant, depending on the modulation index. TR receivers still can be functional in the presence of CMI, and the target performance level determines the modulation index to be used. It is unlikely that effects of CMI on the performance of ED receivers in the presence of CMI are more severe relative to TR receivers, and the performance level is not acceptable. As a result, PPM signaling is not an appropriate modulation technique for ED receivers that are operating in the CMI region, unless CMI mitigation algorithms can be developed. Furthermore, the proposed optimal and suboptimal algorithms are two promising schemes for avoiding the CMI effects and, consequently, for improving the performance of Rake receivers operating in the CMI region.

Abstract: High power current source converters (CSC) are usually implemented with GTOs which present a maximum switching frequency of a few kHz. Space vector modulation (SVM) offers a very elegant way of generating CSC gating signals on-line with increased gain and reduced switching frequency. However, for very low frequency, as required by GTOs, SVM results in non-characteristics low order (5th and 7th ) harmonics. The reduction of the magnitude of these harmonics has been sought mostly through new sequences of space vectors (states), which present better performance for different ranges of modulation index and power factor. Moderate improvement can be obtained by calculating the states on times at once in the middle of a cycle. This paper shows that larger reductions can be achieved by calculating the states on times at different moments, as the states are used. The effectiveness of the proposed technique for different states sequences is demonstrated by means of simulations.

Abstract: Techniques for the generation of bandlimited signals for applica-tion to digital implementations of subtractive synthesis have been researched by a number of authors. This paper hopes to contrib-ute to the variety of approaches by proposing a technique based on Frequency Modulation (FM) synthesis. This paper presents and explains the equations required for bandlimited pulse genera-tion using modified FM synthesis. It then investigates the rela-tionships between the modulation index and the quality of the reproduction in terms of authenticity and aliasing for a sawtooth wave. To determine the performance of this technique in com-parison to others two sets of simulation results are offered: the first computes the relative power of the non-harmonic compo-nents, and the second uses the Perceptual Evaluation of Audio Quality (PEAQ) algorithm. It is shown that this technique com-pares well with the alternatives. The paper concludes with sug-gestions for the direction of future improvements to the method.

Abstract: A contactless IC device including a detection circuit configured to detect a carrier wave that has been amplitude shift-keying (ASK) modulated with digital data and a shunt circuit configured to regulate the carrier wave to a predetermined voltage level.

Abstract: Because of the unbalanced construction, the conventional three-phase three-leg inverters produce huge amount of common-mode (CM) voltage. This paper proposes a novel sinusoidal pulse width modulation (SPWM) control strategy based on three-phase four-leg structure. This strategy is an improved method on the basis of the SPWM carrier phase-shifting control technology. In the new method, the state of one of the first three legs is exchanged with the latter state of the same leg when zero-state appears. It can ensure the output balance of four legs in inverter under any conditions, and thus reduces the generation of CM voltage. Compared with the previous SPWM control strategies in three-phase four-leg inverter, the state exchange method breaks through the limitation of SPWM modulation index which must be less than 0.666 to avoid the extremely low utilization ratio of direct current (DC) voltage, and reduces the total harmonic distortion factor (THD) of the output voltage. The effectiveness of the control strategy is proved by simulation and experiment results.