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Voltage source inverters operated by predictive control methods generally lead to a variable switching frequency, because predictive control methods generate switching operation based on an optimal voltage state selected at every sampling period. Varying switching frequencies make it difficult to design output filters of voltage source inverters. This paper proposes a predictive control algorithm with a constant switching frequency for the load current control of single-phase voltage source inverters. This method selects two future optimal voltage states used in the subsequent sampling period, which are a zero-voltage state and a future optimal voltage state, based on the slope of the reference current at each sampling period. After selecting the two future voltages, the proposed method distributes them to produce a constant switching frequency and symmetric switching pattern. The performance of the proposed method is validated with both simulation and experimental results for single-phase voltage source inverters. [ABSTRACT FROM AUTHOR]

A model predictive current control (MPCC) method that does not employ a cost function is proposed. The MPCC method can decrease common-mode voltages in loads fed by three-phase voltage-source inverters. Only non-zero-voltage vectors are considered as finite control elements to regulate load currents and decrease common-mode voltages. Furthermore, the three-phase future reference voltage vector is calculated on the basis of an inverse dynamics model, and the location of the one-step future voltage vector is determined at every sampling period. Given this location, a non-zero optimal future voltage vector is directly determined without repeatedly calculating the cost values obtained by each voltage vector through a cost function. Without utilizing the zero-voltage vectors, the proposed MPCC method can restrict the common-mode voltage within ± Vdc/6, whereas the common-mode voltages of the conventional MPCC method vary within ± Vdc/2. The performance of the proposed method with the reduced common-mode voltage and no cost function is evaluated in terms of the total harmonic distortions and current errors of the load currents. Simulation and experimental results are presented to verify the effectiveness of the proposed method operated without a cost function, which can reduce the common-mode voltage. [ABSTRACT FROM AUTHOR]

This paper proposes a predictive control method with zero-sequence voltage injection to efficiently reduce the switching losses of three-phase voltage source inverters (VSIs). In the proposed predictive control method, three-phase future voltage references modified by a zero-sequence voltage injection are generated to clamp one of the three legs with the largest load current. Furthermore, the future zero-sequence voltage, which is produced online with the future voltage and current references in every sampling period, optimally adjusts the clamping duration on each leg, depending on the load angle. In addition, the proposed method selects the zero vector on the basis of the polarity of the future zero-sequence voltage to reduce the switching losses. Using a predefined cost function, the proposed predictive control scheme chooses one optimal voltage state closest to the future voltage references modified by the zero-sequence voltage injection. Therefore, the proposed predictive control method can perform load current control and minimize the switching losses of the VSI under any load condition regardless of the load angle. [ABSTRACT FROM AUTHOR]

This paper proposes predictive-control-based direct power control (DPC) with an adaptive online parameter identification technique for ac-dc active front ends (AFEs) to overcome model mismatch and parameter uncertainty. Based on least-squares estimation, the input inductance and input resistance of the AFE are calculated every sampling period using sampled input currents and input voltages. Because the online-tuned input inductance and resistance are updated for the controller, the proposed predictive-control-based DPC with the adaptive parameter identification technique can mitigate performance degradation resulting from the model uncertainty of the model predictive controller without any additional sensors. Therefore, the AFE generates sinusoidal input currents with a unity power factor despite parameter uncertainty. [ABSTRACT FROM AUTHOR]

This paper proposes the switching strategy based on finite control set model predictive control (FCS-MPC) method, to reduce switching losses and obtain balanced loss distribution of the voltage-source inverters (VSIs). Unlike the conventional FCS-MPC method with no explicit information of the reference voltage, the developed voltage-based FCS-MPC scheme produces the future reference voltage vector with the Lyapunov function every sampling period. With information of both the future reference voltage and the future load current vectors, the proposed switching strategy instantaneously determines one optimum clamped phase among the three legs in the VSI every sampling period. By optimally determining the clamping phase and its duration on the basis of every sampling period, the proposed switching strategy can successfully reduce the VSI switching losses. In addition, the proposed switching method can yield a balanced loss distribution among the switches in the VSI, contrary to the conventional FCS-MPC. The balanced loss generation as well as the switching loss reduction by the proposed method, which is optimal at the sampling period scale, is directly incorporated with the platform of the FCS-MPC algorithm, since the FCS-MPC operates on the basis of the sampling period. Thus, the proposed switching operation based on the voltage-based FCS-MPC algorithm enables the future VSI output currents to track the future reference current vector, as well as results in the reduced switching losses and the balanced loss performance. [ABSTRACT FROM AUTHOR]

This paper designs a suboptimal speed controller as well as a suboptimal load torque observer based on state-dependent Riccati equation (SDRE) approach for interior permanent-magnet synchronous motor (IPMSM) servo systems. First, dynamic equations of the IPMSMs are transformed to a suitable form that makes an SDRE-based control technique applicable. Moreover, the maximum torque per ampere (MTPA) control is incorporated to improve the torque generation in the constant torque region. The asymptotic stabilities of the proposed controller and load torque observer are fully guaranteed through an extended linear quadratic regulator (LQR) theory. This proposed method is simple to implement because the SDRE solutions are approximated off-line. The proposed observer-based suboptimal control scheme can ensure faster dynamic response, smaller steady-state error, and more robust response than the LQR and proportional-integral (PI) controller under the system parameter variations and load torque disturbances. The effectiveness of the proposed control strategy is verified via experiment. [ABSTRACT FROM AUTHOR]

Hybrid electric vehicle (HEV) technology has numerous advantages over conventional vehicles, from standpoints of fuel economy, energy independence, and environmental concerns. Effective solutions for HEVs have been expanding their applications over highway vehicles, such as sedans and sport utility vehicles, into a variety of traditional vehicles. HEV systems applied to off-highway heavy-duty vehicles, which are operated by an engine, a generator, and traction motors, are investigated in this paper. This paper explores the use of a direct ac/ac converter for off-highway heavy-duty HEVs, which can directly drive traction motors from the generator with no intermediate dc conversion. In addition, a phase-redundant matrix converter structure with a backup leg and a control scheme is proposed to guarantee reliable and safe vehicle operations by providing continuous disturbance-free operations against converter faults. Fault-diagnosis techniques using line-to-line and phase voltages are presented not only to detect system malfunctions but to locate a failed switching device among 18 switching components as well. Appropriate reconfiguration structure and control actions with accurate knowledge about fault occurrence can avoid propagation of fault, which may lead to a catastrophic system failure. [ABSTRACT FROM AUTHOR]

This paper proposes a fault-tolerant matrix converter with reconfigurable structure and modified switch control schemes, along with a fault diagnosis technique for open-circuited switch failures. The proposed fault recognition method can detect and locate a failed bidirectional switch with voltage error signals dedicated to each switch, based on a direct comparison of the input and the output voltages. Following the fault detection, the designed converter architecture isolates the faulty parts and bypasses the remaining load phase, resulting in a 3 x 2 matrix configuration with six bidirectional switches. Based on the reconfigured hardware topology, novel fault-tolerant modulation strategies are developed to produce three-phase balanced sinusoidal output voltages/ currents with only six bidirectional switches, but at a reduced output voltage magnitude as compared with the normal matrix converter. Thus, the developed switching function matrices for the reconfigurable converter structure, containing an appropriate positive- and negative-sequence set of matrices with input voltage vector, can preserve continuous operation even after switch failures and improve reliability of the drives. [ABSTRACT FROM AUTHOR]

A simple and cost-effective sustain circuit with energy recovery and injection function is proposed based on reduced number of circuit components and fast energy transfer speed for plasma display panels (PDPs). The proposed driver configures the sustain circuit and the resonant circuit in such a way that the resonant network is energized by the sustain voltage level and the ground level in charging and discharging the panel capacitor, respectively. Due to this structure, the energy transfer through the panel is twice as fast as the conventional drivers biased by half sustain voltage level. This faster energy transfer speed can lead to the increased number of sustain pulses or the increased address lines, which can improve image brightness or display resolution, respectively. Moreover, the over-excited resonant network enables the panel voltage to fully rise up to the sustain voltage and fall down to the ground, despite of unavoidable parasitic resistance on the circuits. This operation insures zero-voltage turn-on switching for all the sustain switches, which yields reduced switching losses in the driver. Furthermore, the resonant circuit of the proposed driver is installed to function for the energy recovery/injection operation at both the Y and the X electrodes. Due to the semiconductor devices shared in common as well as simplified arrangement, the developed structure can be designed with fewer devices than the conventional approaches. As a result, the PDP driver presented in this paper can feature reduced number of switching devices, faster sustain voltage transition, higher brightness, and smaller size. [ABSTRACT FROM AUTHOR]

Intensive industrial and academic researches have, in the last thirty years, matured plasma display panels to the successful display product for commercial flat screen television sets. Along with development of panel manufacturing technology, recent advances in the development of electronics circuitry drivers have paved the way for achieving better performance, higher efficiency, simpler structure, and lower cost. A substantial number of notable plasma driving circuits have been developed in various parts of the driver, however, most of which have been focused on their own structures and operational principles without giving overall impressions related with other approaches. This paper is an attempt to provide insights into these diverse drivers of the plasma display panels by presenting an overview of the driver structures. The developed driving schemes focused on different sections, including the reset circuits, the path switches, the sustain circuits, and the address circuits, are covered in this paper. Selected drivers in each class are analyzed and key structural characteristics are identified. Issues related to the practical implementation are also discussed. [ABSTRACT FROM AUTHOR]

A sustain circuit with energy recovery and injection circuit is proposed based on reduced number of low-cost and low-rating devices for plasma display panels (PDPs). The proposed driver configures the sustain circuit and the resonant network in such a way that some of circuit components can function for both sustain and energy recovery/injection operations. Due to the semiconductor devices shared in common as well as simplified arrangement, the developed structure can be designed with fewer devices than the conventional approaches with all devices operated individually. Moreover, since the proposed driver is designed with low voltage-rating devices compared with the conventional 2 and 3 level based driver, it can take advantages of semiconductor devices with lower conduction and switching losses as well as cheaper costs. The proposed driver generates such five-level sustain voltage waveforms as a cascaded Weber-type driver, which results in reduced rms values of panel displacement currents and lowered power losses. As a result, the PDP driver presented in this paper can feature reduced number of low voltage rating devices, smaller size, and high efficiency. [ABSTRACT FROM AUTHOR]

An integrated current source converter system is presented based on an assembly of a thyristor-based current source inverter (CSI) in parallel with an insulated-gate-bipolar-transistor- based voltage source inverter (VSI) along with passive capacitors for high-power induction motor drive applications. The proposed configuration installs the VSI and the capacitor in such a way that both provide reactive power for generating the leading power factor required to accomplish natural commutations of the CSI. Based on the collaborative operation of the VS! and the parallel capacitor, the proposed system can be designed with a compromise between the VSI power capacity and the capacitor size. In addition, the VSI compensates harmonic current components from the thyristor-based CSI, while the capacitor filters out the voltage spikes during commutation of the thyristors. As a result, sinusoidal motor currents with improved harmonic spectrum can be drawn from this system. The proposed system utilizes the high-power capability of the thyristor-based CSI to supply high real power, while the VSI with easy controllability regulates the induction motor. Theoretical analyses based on mathematical modeling are presented in detail for the relationship between the inverter rating and the capacitor size, design considerations of the capacitor size, and the loss performances. [ABSTRACT FROM AUTHOR]

A multilevel power-converter topology based on two types of current-source inverters (CSIs) has been proposed for large induction motor drives. The topology utilizes the combination of the load-commutated inverter (LCI) using thyristors and the CSI using gate turn-off thyristors (GTOs). As a result, the multilevel-inverter operation takes advantage of a soft switching of the LCI and hard switching of the CSI. The output capacitor is required to generate the leading power factor for load commutation of the LCI. It is shown that the proposed multilevel operation contributes to the leading-power-factor generation by providing the effective phase shift. Thus, the leading power factor required for the load commutation of the LCI is obtained with significantly smaller capacitors at the inverter's output terminals. As a result, the proposed approach can employ the LCI and utilize its soft-switching operation, yielding a cost-effective solution compared with the conventional multilevel CSI using two GTO CSIs. The switching losses are curtailed due to the natural commutation of the LCI and the six-step operation of the GTO CSI. Therefore, the proposed multilevel inverter can both increase the output power level and decrease the output capacitor size for LCI. The simulation and experimental results have been shown to verify the feasibility of the proposed multilevel topology and its operation. [ABSTRACT FROM AUTHOR]

A thyristor-based current-source inverter (CSI) is proposed, employing a standalone voltage-source inverter (VSI) with a small power rating. The VSI, as an external circuit of the CSI, performs three tasks: 1) turning off of thyristors; 2) transfer of reactive load energy; and 3) clamping peak voltages across the load and thyristors. In comparison with conventional thyristor-based CSIs requiring large ac commutation capacitors as well as individual energy recovery and voltage clamping circuits, the proposed CSI system can replace all the complicated auxiliary circuits and bulky ac capacitors with the small VSI. Furthermore, the proposed CSI ensures simple and easy control of the commutation process due to the simple switching operation of the VSI. The VSI operates only during the commutation periods of the load currents and stops working in the noncommutation periods. Thus, the VSI with small power rating can be used for the proposed CSI system. The feasibility of the proposed CSI system is verified by simulation and experimental results. [ABSTRACT FROM AUTHOR]

From economical aspects, the multidrive systems are a promising application area for the converters, where the cost and size of the converters are shared by multiple inverter-motors. Given terminal constraints of unity power factor in grid line and independent multiple motor controls in output ports, two multidrive topologies are possible: one with single PWM-VSR feeding inverters through the common dc bus, and the other using a diode rectifier and an active power filter with its own load. Despite several publications for two systems, the features and advantages of the two systems have not been clearly explained. This paper, in detail, presents the theoretical analyses and systematic comparisons of the two multidrive topologies, from converter kilovolt-ampere ratings, dc-link voltage requirements, switch ratings, semiconductor losses, and reactive component designs point of views. [ABSTRACT FROM AUTHOR]

A study of switching function approach is presented for remedial control techniques against open-switch and open-phase failures occurring in ac-ac converters. Switching function matrices, containing symmetric and antisymmetric mode matrices with appropriate sequences of input voltages, are developed to synthesize redefined output waveforms under the faults. [ABSTRACT FROM AUTHOR]

A simple energy recovery and commutation circuit is proposed to operate a six-step current-fed inverter based on thyristors. The circuit topology and operational principle are presented. Experimental results are also shown to verify the proposed scheme. [ABSTRACT FROM AUTHOR]

Finite control set model predictive control (MPC) method needs calculations corresponding to the total number of voltage vectors made by power converters. This operating principle of the MPC leads to an increase in the computational load and number of calculations, which dramatically increase proportional to the increase in the level of cascaded H-bridge (CHB) inverters. However, it is difficult to consider all voltage vectors to find the optimal vector for high-level CHB inverters because of the short sampling time. This study proposes a new MPC algorithm to reduce the number of calculations for multi-level CHB inverters, in which only three voltage vectors are considered as optimal vectors regardless of the level of CHB inverters. Consequently, compared with the conventional MPC method for CHB inverters, the proposed MPC method requires fewer calculations and reduces the computational load without affecting the system performance and dynamic response. [ABSTRACT FROM AUTHOR]

A simplified model predictive control method is presented in this paper. This method is based on a future reference voltage vector for a three-phase four-leg voltage source inverter (VSI). Compared with the three-leg VSIs, the four-leg VSI increases the possible switching states from 8 to 16 owing to a fourth leg. Among the possible states, this should be considered in the model predictive control method for selecting an optimal state. The increased number of candidate switching states and the corresponding voltage vectors increase the calculation burden. The proposed technique can preselect 5 among the 16 possible voltage vectors produced by the three-phase four-leg voltage source inverters, based on the position of the future reference voltage vector. The discrete-time model of the future reference voltage vector is built to predict the future movement of the load currents, and its position is used to choose five preselected vectors at every sampling period. As a result, the proposed method can reduce calculation load by decreasing the candidate voltage vectors used in the cost function for the four-leg VSIs, while exhibiting the same performance as the conventional method. The effectiveness of the proposed method is demonstrated with simulation and experiment results. [ABSTRACT FROM AUTHOR]

This paper presents a new approach to analyze the stator inter-turn fault of a brushless dc motor. It is essential to analyze the behavior of the machine under internal faults and design appropriate protection systems to avoid expensive failures that might occur to the machine in the near future. The winding functions and inductance change of stator windings under internal faults are explained in detail, and the informative simulation results, based on the winding function theory, are provided to analyze a current's abnormalities and torque pulsation under turn-to-turn faults. To verify the proposed analysis, the stator current, back-electromotive force, and resultant torque waveforms for both healthy and faulty machines are presented, utilizing both the finite-element method (FEM) and computer simulation based on dynamic equations. Finally, experimental results present the actual behavior under the stator faults. The detailed simulation and experimental results will be the guideline for early detection of internal failures in brushless dc motors. [ABSTRACT FROM AUTHOR]

In this paper, a predictive direct power control (DPC) method based on a Kalman filter is presented for three-phase pulse-width modulation (PWM) rectifiers to improve the performance of rectifiers with source voltages that are distorted with harmonic components. This method can eliminate the most significant harmonic components of the source voltage using a Kalman filter algorithm. In the process of predicting the future real and reactive power to select an optimal voltage vector in the predictive DPC, the proposed method utilizes source voltages filtered by a Kalman filter, which can mitigate the adverse effects of distorted source voltages on control performance. As a result, the quality of the source currents synthesized using the PWM rectifier is improved, and the total harmonic distortion (THD) values are reduced, even under distorted source voltages. [ABSTRACT FROM AUTHOR]

This paper presents a predictive control-based fuel-cell hybrid electric vehicle system. Employing hybrid power sources, an ultracapacitor (UC), and a battery, the hybrid system maximizes the energy efficiency and protects the battery while achieving faster torque response based on predictive controllers residing in the boost converter, UC manager, and motor drive. The predictive controller implemented in the brushless dc (BLDC) motor drive improves the motor current response. Overall, the proposed hybrid system improves the dc-bus current response, and, hence, motor torque response, compared with a conventional proportional-integral (PI) controller-based system. The effectiveness of the proposed system has been verified through simulation and experiment. [ABSTRACT FROM PUBLISHER]