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This article exhibits an output voltage-derivative observer-based output voltage-tracking technique for dc/dc boost converters without current feedback, taking the model-plant mismatches (caused by parameter and load variations) and model nonlinearity into consideration. In contrast to extant passivity-based approaches, the proposed solution includes observers to estimate the output voltage derivative and does not require exact model information, which offers a few features: converter parameter information-free output voltage-derivative observers including the modified disturbance observation algorithm for improving the high-frequency disturbance rejection capability as a replacement of the estimation error integral actions, and the observer-based output voltage and its derivative error stabilizer with a damping adaptation mechanism assigning the desired energy function to the closed-loop system. Experimental verification is provided to demonstrate the practical advantages of the proposed solution using a 3-kW bidirectional converter. [ABSTRACT FROM AUTHOR]

A torque ripple reduction technique of direct torque control (DTC) for high power induction motors driven by three-level inverters with the inverter switching frequency limited around 0.5-1 kHz level is presented. It is noted that conventional two-level DTC algorithms to reduce torque ripple are devised for applications with relatively high switching frequency above 2-3 kHz and cannot accomplish satisfactory torque ripple reduction for three-level inverter systems with such lower switching frequencies. A new DTC algorithm, especially for low switching frequency inverter system, illustrates quite reduced torque ripple characteristics all over the operating speed region. Simulation and experimental results show effectiveness of the proposed control algorithm. Index Terms--Direct torque control, induction motor, three-level inverters, torque ripple reduction.

The emerging switched-capacitor-based multilevel inverters offer interesting merits such as self-balancing of capacitor voltages and boosting of voltage gain. While the switched capacitors (SCs) in these topologies are charged in parallel with the dc source, severe current spikes issue is inevitable, rendering them impractical at high power. This article proposes a novel switched-capacitor-based T-type inverter that mitigates the current spikes by enabling soft charging for its integrated SCs, where both SC in the topological structure charges through a dedicated circuit comprises of an inductor and two switches. The proposed topology is capable of five-level ac voltage generation and when compared to a classical T-type/ANPC (active neutral-point-clamped) inverter, it achieves higher dc-link voltage utilization since its maximum attainable voltage gain is doubled. Theoretical findings of the proposed topology are validated by both the simulation and experimental results. [ABSTRACT FROM AUTHOR]

Open- and short-circuit faults are the most severe issues that affect the stability and reliability of power conversion systems. The space vector modulation (SVM) technique is widely used to control power converters. However, conventional SVM is incapable of controlling the system effectively when such faults occur. Considering these, this article proposes a modified SVM that is capable of tolerating the extreme cases of faults (including multi open-/short-circuit faults) simultaneously. An innovative fault tolerance method is proposed to tolerate multifaults in hybrid active neutral point converters (HANPCs). Furthermore, new voltage reference signals are created in addition to calculating voltage offset and inserting modified switching sequences. A descriptive performance analysis of the modified SVM technique is applied under healthy and faulty conditions. Correspondingly, the effects of the total harmonic distortion of the system performance are also highlighted and explained. The results reveal that the proposed control strategy can effectively maintain healthy and safe operation under faulty conditions without the need for additional parts or alteration of the topology configuration. In addition, the proposed method can be applied to HANPCs without special requirements to withstand high voltage levels. The effectiveness of the proposed method is verified by simulation and experimental results. [ABSTRACT FROM AUTHOR]

Three-level neutral-point-clamped (3L-NPC) voltage source inverters are widely used in many low- and medium-power applications. However, the 3L-NPC inverter has an inheritance issue of the neutral-point (NP) voltage unbalancing due to the deviation of dc-link capacitor voltages causing distortions for the output waveform quality. Generally, discontinuous pulsewidth modulation (DPWM) is used to diminish the stress on power transistors and prolong their lifespan, however; it is not capable of solving the issue of NP voltage unbalancing. Therefore, this article proposes a simple voltage balancing control based on DPWM with a hysteresis NP voltage band. The balancing control method is only activated once the capacitance voltage error exceeds the hysteresis band by generating a momentary offset on the opposite direction of the DPWM offset. In this way, both top and bottom capacitance voltages will converge within a predefined error band. Various hysteresis error bands are investigated by analyzing the power losses, total harmonic distortions, and common mode voltage. The advantages of this proposed method are its simplicity and ease of control while maintaining the features of DPWM. The effectiveness of the proposed method is validated using simulation and experimental results. [ABSTRACT FROM AUTHOR]

This article proposes a method to eliminate abnormal output voltages generated in three-level hybrid active neutral-point clamped (ANPC) inverters. The hybrid ANPC inverter is a topology in which silicon (Si) devices are replaced with silicon-carbide (SiC) devices in part from the conventional ANPC topology. The hybrid ANPC inverters have the advantages of high switching frequency and low power switching loss due to the SiC devices. In this hybrid ANPC inverter, abnormal output voltages occur when the polarity of the output pole voltage is changed from positive to negative. The cause of the abnormal voltages is the switching time difference between the Si and SiC devices, and it is various from a few nanoseconds to a few microseconds. These abnormal output voltages need to be eliminated as it leads to degraded output power quality in the hybrid ANPC inverters. The proposed switching method effectively eliminates the abnormal output voltages and reduces output current distortion. The performance of the proposed method is verified using a prototype of the new three-level hybrid ANPC inverter type through both simulations and experiments. [ABSTRACT FROM AUTHOR]

This article presents a dc-link capacitor lifetime improvement method for three-level photovoltaic hybrid active neutral-point clamped inverters in full modulation index range. The capacitors are one of the components with vulnerable reliability in a power conversion system. The dc-link capacitor current ripples lead to temperature rise and wear-out failure of the capacitors. The accumulated thermo-mechanical damages from the temperature rise reduce the capacitor lifetime and reliability of the system. The proposed modulation method suppresses effectively the dc-link capacitor current ripple to improve the capacitor lifetime. In this article, the proposed method is discussed via a comparison with conventional space-vector pulsewidth modulation in full modulation index range. The modulation index range is divided into two regions, namely medium-vector modulation and hybrid modulation region. The capacitor lifetime is evaluated by the capacitor lifetime model according to the modulation methods and modulation regions. The effectiveness of the proposed modulation method is verified through simulation and experimental results. [ABSTRACT FROM AUTHOR]

This article proposes a harmonic voltage injection pulsewidth modulation (PWM) method for a Vienna rectifier with an LCL filter. Existing PWM methods for Vienna rectifiers with full power factor can lead to resonance problems. It generates current oscillation at the resonant frequency. It is analyzed that why the resonance problem occurs in Vienna rectifier with the existing PWM methods. To solve these resonance problems, the proposed method injects a sinusoidal harmonic voltage into the sinusoidal reference voltage. The magnitude and phase of the injection voltage are determined by the power factor of the rectifier-side. Compared to other PWM methods, the proposed PWM method eliminates the possibility of resonant problems. Considering the operation characteristics of the proposed PWM method, this article suggests a design process for an LCL filter. The effectiveness and performance of the proposed PWM method and the design process for an LCL filter are verified by simulation and experiment. [ABSTRACT FROM AUTHOR]

The switched-capacitor-based cascaded multilevel inverters (CMI) have been emerging due to their voltage boosting capability. Unfortunately, they suffer from impulse charging current and nonuniform operation. This article presents a topology termed as dual-T-type five-level CMI to resolve these problems without compromising the desirable voltage boosting characteristic. The main idea is to integrate a half bridge and an inductor to soft charge a capacitor that is connected in series with the dc source. The capacitor enables the voltage gain boosted to two, while the control of eight power switches that constitutes a dual-T structure enables five voltage levels generation. In addition, uniform operation is achieved for cascaded extensions. The operating principle of the proposed topology is analyzed and elaborated. For validation, simulation, and experimental results of a prototype are presented. [ABSTRACT FROM AUTHOR]

Conventional active-neutral-point-clamped (ANPC) inverters exhibit low voltage gain that inherently leads to a high dc-link voltage requirement. An improved ANPC inverter that is capable of generating five voltage levels has recently reduced the dc-link voltage twofold to achieve unity gain. This led to the development of a single-stage dc–ac power converter with no frontend boost dc–dc converter. This article proposes novel ANPC inverters capable of unity or boosted voltage gain while generating higher voltage levels. The first topology can provide a voltage gain of 1.5 and extends the number of levels to seven by incorporating only one additional switch. The topology can also be extended by adding three switches and one floating capacitor to generate nine levels with unity voltage gain, or 11 levels with a voltage gain of 2.5. The proposed ANPC inverters and their operations are comprehensively discussed. Experimental results are provided to validate the feasibility of the proposed ANPC inverters. [ABSTRACT FROM AUTHOR]

In this article, a simple overmodulation method is proposed for achieving fast direct torque control with a constant torque-switching controller (CTSR-DTC) in induction machines. The conventional overmodulation method applied to CTSR-DTC focuses on attaining and maintaining the voltage vector with the largest tangential component to the locus of the stator flux. The selected voltage vector is held during the transient state and fed into the switching table. Nevertheless, unlike a classical DTC, the CTSR activates both zero- and active-voltage vectors owing to the nature of its operation. As a result, the optimized active voltage during an overmodulation cannot be maintained throughout the complete torque transient owing to an interruption by the zero-voltage vectors. To overcome this problem, the proposed method modifies the CTSR output to eliminate the zero-voltage vectors only during a transient state. Consequently, a full exploitation of the overmodulation is achieved, and hence an excellent torque dynamic response can be obtained when torque is demanded. Simulation and experimental results are provided to validate the effectiveness of the proposed overmodulation strategy. [ABSTRACT FROM AUTHOR]

This paper proposes the predictive control with the discrete space-vector modulation (DSVM) for Vienna rectifier connecting to the permanent magnet synchronous generator (PMSG) of the wind turbine system (WTS). Since Vienna rectifier has the special operation principle, Vienna rectifier generates only the feasible eight voltage vectors, which can be a candidate vector for the predictive control, depending on the sign of the input currents. In the proposed predictive control, the feasible voltage vectors are extended from 8 to 19 consisting the 8 original voltage vectors and 11 virtual voltage vectors by using the DSVM for improving the current quality related to the torque ripple, vibration, and noise, and the neutral-point voltage balance with low voltage ripple is guaranteed by using the offset value calculated based on the model of two dc-link capacitors in Vienna rectifier. The scheme for reducing calculation burden is applied in selecting the candidate vector. In addition, the limited operation range for the maximum torque per ampere control of PMSG connected to Vienna rectifier is analyzed. The performance of the proposed predictive control with DSVM for Vienna rectifier with PMSGs is verified in simulation and experiment. [ABSTRACT FROM AUTHOR]

In this paper, two simple control methods are proposed for improving direct torque control (DTC) with a constant frequency torque controller (CFTC-DTC) in induction machines. The CFTC-DTC was initially introduced to reduce torque ripple and achieve constant switching frequency in inverters. However, when compared to the original DTC, the CFTC-DTC algorithm suffers from slow torque dynamic response owing to the selection of zero-voltage vectors during torque transient. In addition, when the motor operates at low speed, flux droop occurs at sector transitions, which leads to undesirable current distortions. The problem of flux droop occurs because of short-duty voltage cycles and small radial voltage components at low speeds. This paper has two main contributions—to eliminate zero-voltage vectors during torque dynamics in order to establish a fast torque response in the transient state, and to minimize the flux droop at the sector transitions by applying another triangular carrier and modifying the torque output in order to increase the duty voltage cycles at low motor speeds. A detailed analysis of the problems and proposed methods is presented. Experimental results are provided to validate the effectiveness of both proposed methods. [ABSTRACT FROM AUTHOR]

This paper proposes a new family of multilevel inverter topology that is able to generate seven voltage levels by utilizing one or two floating capacitors and 10 power switches. This novel boost switched-capacitor seven-level inverter possesses voltage boosting capability with an achievable maximum voltage level 1.5 times the input direct current (dc) voltage. The generation of higher output voltage does not incur high-voltage stress on any power switch in this topology, as the peak inverse voltages of all power switches do not exceed the input source voltage. In addition, capacitor voltage balancing is not essential since the floating capacitors are effectively balanced during the charging and discharging processes. Furthermore, the proposed topology eliminates the need for multiple isolated dc sources, and a single dc source is sufficient in both its single-phase and three-phase topologies. The operating principle and steady-state analysis of the proposed topology are elaborated. Experimental results from a single-phase prototype are then presented to verify the validity of the proposed topology. [ABSTRACT FROM AUTHOR]

The conventional three-level active-neutral-point-clamped (ANPC) inverter requires high dc-link voltage at least twice the peak of ac output. To reduce the dc-link voltage, a recent topology that enhanced the voltage gain from half to unity has been presented. In this letter, an alternative ANPC topology is established by using two T-type inverters. Two floating capacitors with self-voltage balancing capability are integrated to achieve a voltage-boosting gain of 1.5. In addition, the proposed topology is capable of generating seven voltage levels. Its operation is validated through circuit analysis followed by experimental results of a prototype. [ABSTRACT FROM AUTHOR]

A modular multilevel converter (MMC) is regarded as a promising topology in high-voltage direct current systems. However, the MMC consists of numerous submodules (SMs) and switching devices, which lead to a considerable switching loss, and increased cost and size of the heat sink. To mitigate these issues, this paper presents a novel modulation method composed of fundamental frequency modulation (FFM) and multicarrier-based sinusoidal pulsewidth modulation schemes. The main purpose of this modulation method is the reduction of switching loss while maintaining good harmonic performance. However, the FFM scheme leads to the unbalanced capacitor voltage of each SM in the MMC. Accordingly, this paper additionally proposes the rotation method and selective voltage balancing control for SMs to ensure effective performance of the method. Simulation and experimental results verify the effectiveness and performance of the proposed modulation scheme through switching loss and spectral analyses. [ABSTRACT FROM AUTHOR]

This paper proposes the new clamping angle control (CAC) pulse width modulation (PWM) method to restore its maximum linear modulation range of voltage source inverters (VSIs) reduced by the duty ratio limitation in hardware implementation, which makes the VSIs to operate nonlinearly in the high modulation range. The deadtime and the bootstrap gate driver circuit mainly cause this duty ratio limitation in practice. In particular, the bootstrap gate driver circuit is used in many industrial applications by avoiding the additional power supply to apply the gate-source voltage of power switches, and therefore making the VSIs to be small size with the low cost. First, the proposed CACPWM method is theoretically analyzed. Then, it is applied in the high modulation range to overcome the limitation of the duty ratio due to the use of the bootstrap gate driver circuit. Thereafter, its practical effectiveness is verified by both simulation and experimental tests. Also, the resulting harmonic distortions are compared with those by the conventional PWM methods. [ABSTRACT FROM AUTHOR]

This paper proposes a novel discontinuous pulse-width modulation (DPWM) method to reduce the current harmonics and improve the system efficiency for a single-phase three-level neutral-point clamped inverter. In single-phase inverters, the unipolar pulse-width modulation (UP-PWM) method is commonly used. However, this method has the disadvantage of power losses due to numerous switching operations. Conventional DPWM methods reduce the power losses and improve efficiency but increase the current total harmonic distortion (THD). To overcome these weaknesses, this paper proposes a hybrid DPWM switching method combining two PWM methods: the UP-PWM method and the conventional DPWM method called one-pole clamped PWM method. Since the proposed DPWM method offers all the advantages of both PWM methods, the optimal performance—with regard to the power losses and current THD—is obtained. The combination of two PWM methods is investigated by analyzing the power losses and current THD. Based on the analysis, the process determining the optimal operating condition is introduced. The effectiveness of the proposed DPWM method is demonstrated through simulations and experiments. [ABSTRACT FROM AUTHOR]

The magnitude of hysteresis torque band has a considerable effect on the performance of two-level direct torque control (DTC) of induction machines. The conventional DTC fails at low speed due to the poor flux regulation. In this paper, two dynamic hysteresis torque band (DHTB) strategies for the conventional DTC are proposed to solve this problem by dynamically altering the amplitude of hysteresis torque band based on a flux error range. In this way, the simplicity of DTC algorithm is retained since it only requires a minor modification on its structure. The paper also presents further analysis on flux degradation, particularly the droop in between the flux sectors. In addition, the switching frequency effect of reverse voltage vectors for both DHTB schemes is investigated on the performance of the speed-sensorless DTC drive. The effectiveness of the proposed schemes is confirmed by simulation and experimental validation. Results show a significant enhancement in the flux regulation and dynamic torque response from zero motor speed. [ABSTRACT FROM AUTHOR]

This paper proposes a simple control method of induction motors (IMs) with improved dynamic response and steady-state performance by using a model-based predictive control algorithm. The predictive torque control (PTC) method analyzes the relationship between the electrical torque and stator voltage of IMs by using the stator voltage vector magnitude to obtain the reference voltage vector angle and accurately control the electrical torque. However, the conventional PTC method has a fixed reference voltage vector magnitude and thus has a large torque ripple in the steady state and slow dynamics in the transient state. The proposed PTC method is based on mathematical equations, which allow minimization of torque error and calculation of a relevant reference voltage to establish a better dynamic response in the transient state and accurate control performance in the steady state. Excellent steady-state performance and a quick dynamic response of the proposed method are proved by the simulation and experimental results. [ABSTRACT FROM PUBLISHER]

This paper presents a self-tuning speed control scheme for the surface-mounted permanent magnet synchronous motor (SPMSM) against parameter variations with the traditional vector control strategy. The proposed control strategy has three novelties; the first one is to design the inner- and outer-loop controllers to stabilize the current and speed dynamics with the self-tuning algorithm for a better transient performance, the second one is to give a systematic way to constitute a robust optimal control gain by solving an optimization problem, and the third one is to show that the proposed inner-loop controller also stabilizes the closed-loop system, including the first-order internal dynamics caused by the SPMSM speed. The efficacy of the proposed method was verified through experiments using a 3-kW SPMSM. [ABSTRACT FROM PUBLISHER]

This paper presents an open-circuit fault detection method for a grid-connected neutral-point clamped (NPC) inverter system. Further, a fault-tolerant control method under an open-circuit fault in clamping diodes is proposed. Under the grid-connected condition, it is impossible to identify the location of a faulty switch by the conventional methods which usually use the distortion of outputs because the distortion of the outputs is the same in some fault cases. The proposed fault detection method identifies the location of the faulty switch and the faulty clamping diode of the NPC inverter without any additional hardware or complex calculations. In the case of the clamping diode faults, the NPC inverter can transfer full rated power with sinusoidal currents by the proposed fault-tolerant control. The feasibility of the proposed fault detection and the fault-tolerant control methods for the grid-connected NPC inverter are verified by simulation and experimental results. [ABSTRACT FROM AUTHOR]

This paper proposes a speed-control law for a parametrically uncertain surface-mounted permanent magnet synchronous motor (SPMSM) using a multivariable approach, which robustly and optimally stabilizes the tracking error dynamics using only the lower and upper bounds of the SPMSM parameters. The contributions of this article are twofold. First, both the inner- and outer-loop controllers are designed using a multivariable approach; the back-stepping controller design method ensures stability and the offset-free property. Second, it is shown that it is possible to systematically assign the robust global stabilizing control gains by solving an optimization problem. The efficacy of the proposed method is experimentally verified using a 3-\textkW SPMSM. [ABSTRACT FROM AUTHOR]

The nongenerative-boost type rectifier, which is called the Vienna rectifier, is advantageous in terms of efficiency and current total harmonic distortion. Therefore, the Vienna rectifier is used in grid-connected applications such as telecommunication systems and wind turbine systems. Owing to the structural characteristics of the Vienna rectifier, various switching methods exist. Among these methods, a carrier-based discontinuous pulse-width modulation (CB-DPWM) method guarantees high efficiency compared to continuous pulse-width modulation methods; moreover, it is simple compared to a DPWM method based on space vectors. In this paper, the performance of the CB-DPWM method, its applicable region depending on the power factor and modulation index (Ma ), and its efficiency are analyzed in detail. Then, based on the analysis, a neutral-point voltage balancing method for the CB-DPWM method is proposed. The effectiveness and performance of the proposed neutral-point voltage balancing method are verified by simulation and experiment. [ABSTRACT FROM AUTHOR]

A three-level converter is used as the power converters of wind turbine systems because of their advantages such as low-current total harmonic distortion, high efficiency, and low collector–emitter voltage. Interior permanent magnet synchronous generators (IPMSGs) have been chosen as the generator in wind turbine systems owing to their advantages of size and efficiency. In wind turbine systems consisting of the three-level converter and the IPMSG, fault-tolerant controls for an open-circuit fault of switches should be implemented to improve reliability. This paper focuses on the open-circuit fault of outer switches (Sx1 and Sx4) in three-level rectifiers (both neutral-point clamped and T-type) that are connected to the IPMSG. In addition, the effects of Sx1 and Sx4 open-circuit faults are analyzed, and based on this analysis, a tolerant control is proposed. The proposed tolerant control maintains normal operation with sinusoidal currents under the open-circuit fault of outer switches by adding a compensation value to the reference voltages. The effectiveness and performance of the proposed tolerant control are verified by simulation and experiment. [ABSTRACT FROM AUTHOR]

This paper proposes a power predictive control (PPC) method for three-phase pulse width modulated rectifiers without a proportional-integral controller. The proposed PPC method calculates the optimized voltage vector by analyzing the relationship between the virtual flux, active power, converter voltage, and filter parameters. Thus, an overshoot does not occur and the fast and accurate power control becomes possible. The predictive algorithm computes the power error that would be produced by applying each vector and selects the one that contributes the minimum error. The simulation and experimental results prove that the proposed method provides an excellent steady-state performance and quick dynamic response. [ABSTRACT FROM PUBLISHER]

The purpose of neutral-point voltage balancing algorithms in the three-level neutral-point clamped (3L-NPC) topology is to eliminate the voltage unbalance of top- and bottom-side dc-link voltages (neutral-point voltage). These algorithms are divided into dc unbalance and ac unbalance compensation methods. The dc unbalance causes distortion of output currents; therefore, this problem has to be solved. The ac unbalance implies that there is an ac ripple in the top- and bottom-side dc-link voltages. In applications using 3L-NPC topology, a large dc-link capacitor value is required to mitigate this ac unbalance problem. As a result, the size and the cost of applications become large and expensive. In this paper, a compensation method for mitigating the ac unbalance of the neutral-point voltage is proposed, which causes the dc-link capacitor value to be small, when a carrier-based pulse width modulation method is applied. The proposed method compensates the ac unbalance of the neutral-point voltage by adding an optimal compensation value to the reference duty signals. This compensation value is calculated simply by currents and reference duty signals. The calculation process of the optimal compensation value is discussed, and the effectiveness of the proposed method is verified with simulations and experiments. [ABSTRACT FROM PUBLISHER]

This paper presents an adaptive speed tracking control scheme for an uncertain surface-mounted permanent magnet synchronous motor (SPMSM) without any knowledge of the SPMSM parameters and the singularity problem; further, even the upper and lower bounds of the parameters are not necessary. The contribution of this study is twofold. The first one is to introduce a coordinate transformation so that the resulting controller does not suffer from a singularity problem caused by the denominator including the parameter estimates. Besides, although the number of the unknown parameters is increased by two times, the number of estimators is the same as the previous result. The second one is to prove that the slightly modified parameter adaptation law contributes in enhancing the closed-loop robustness against the disturbance caused by the time-varying component of the load torque. The effectiveness of the closed-loop performance is shown by performing the experiment using the 3-kW SPMSM without any SPMSM parameter knowledge. [ABSTRACT FROM PUBLISHER]

Multilevel rectifier topologies are commonly used in wide-power range applications. The T-type rectifier topology, which is a three-level topology, has an advantage in terms of efficiency compared to a neutral-point clamped (NPC)-type topology. In applications using the T-type rectifier topology, improving reliability has gained increased attention recently. A tolerance control for T-type rectifiers is necessary to improve the reliability of applications. When an open fault of switches connected to the neutral-point occurs, the NPC-type rectifier cannot restore distorted input currents, on the other hand, the T-type rectifier can eliminate the input current distortion completely. In this paper, we report two studies: 1) a three-level switching-oriented tolerance control, which is advantageous in terms of efficiency, for the Sx2 and Sx3 open-switch faults of the T-type rectifier and 2) comparison of the proposed tolerance control with two existing tolerance controls. In particular, the current total harmonic distortion, dc-link voltage ripple, and switch losses of these tolerance controls are analyzed by using simulation and experimental results. [ABSTRACT FROM AUTHOR]

This paper proposes a simple and effective method to reduce torque ripples for the torque predictive control (TPC) of permanent-magnet synchronous motors (PMSMs). The conventional TPC analyzes the relationship among the electrical torque, stator flux, and stator voltage using the magnitude of the stator voltage vector of PMSMs to obtain the angle of the reference voltage vector and accurately control the torque. In addition, the stator-flux control uses the hysteresis method. However, the voltage vector that can be chosen in an inverter is limited because the conventional TPC fixes the magnitude of the reference voltage vector, and thus, a large torque ripple is generated in the low-speed region. The proposed TPC does not fix but varies the magnitude of the reference voltage vector using both the torque and flux error information. Therefore, it not only has the fast dynamic of a direct torque control but also can reduce effectively the torque ripple. The proposed method is proven by the simulation and experimental results, and the proposed algorithm provides an excellent steady-state response and fast dynamics. [ABSTRACT FROM AUTHOR]

This paper proposes a generalized scheme of new soft-switching interleaved boost converters that is suitable for high step-up and high-power applications. The proposed converter is configured with proper numbers of series and parallel connected basic cells in order to fulfill the required output voltage and power levels, respectively. This leads to flexibility in device selection resulting in high component availability and easy thermal distribution. Design examples of determining the optimum circuit configuration for given output voltage and power level are presented. Experimental results from a 1.5-kW prototype are provided to validate the proposed concept. [ABSTRACT FROM AUTHOR]

In the above titled paper (ibid., vol. 26, no. 11, pp. 3377-3385, Nov. 2011), one of the author's names was spelled incorrectly, and should be Kyo-Beum Lee. Also, the affiliation of S. Choi was incorrect and should read, "S. Choi is with the Department of Control and Instrumentation Engineering, Seoul National University of Science and Technology." The bio photo of W. Choi was also left out and is presented here. [ABSTRACT FROM AUTHOR]

In the production of the above titled paper (ibid., vol. 26, no. 10, pp. 2906-2914, Oct. 2011), a typographical error occurred in the acknowledgement of the first footnote and should read, "This work has been supported by KESRI(20101020300260), which is funded by MKE(Ministry of Knowledge Economy)." Additionally, the author biographies were left out of the paper and are presented here. [ABSTRACT FROM AUTHOR]