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This paper presents a cascaded H-bridge multilevel inverter (CHMI) and proper switching method for increasing output voltage levels. In recent year, CHMI have presented an attractive topology for high power and mediumvoltage applications for increasing voltage levels. In proposed scheme, each output terminals of H-bridge modules are connected with transformer and the secondary side of each transformer...
In recent years, fault tolerance has become one of the most interesting topics because the open-switch faults rise to unbalance of the AC input currents and unable to control DC-link voltage that can cause serious damage to the connected application. This paper proposes a model predictive direct power control (MPDPC) method to tolerance control using a neutralpoint clamped (NPC) topology in a switch...
This paper proposes a three-phase input indirect matrix converter topology for a dual ac-drive system with modified switch control schemes, along with addition of a leg. This topology is developed based on a very sparse matrix converter with addition of a leg in the inverter stage, which can reduce the amount of power transistors compared to the conventional dual matrix converter system and; therefore,...
This paper presents a detecting method for an open-switch fault in cascaded H-bridge multilevel inverters. Recently, cascaded multilevel inverters are widely used in high voltage and power systems. Therefore, the reliability of this topology has become an important factor. To improve the reliability, detecting methods for an open-switch fault are required. The proposed method is based on the current...
This paper proposes a power predictive control (PPC) method of three-phase pulse width modulated (PWM) rectifiers without a proportional-integral (PI) controller. The proposed PPC method calculates the optimized voltage vector by analyzing the relationship between virtual flux (VF), active power, converter voltage, and filter parameter. Thus the overshoot does not occur and the fast and accurate power...
This paper proposes an improved discontinuous PWM (DPWM) algorithm. The modulation signal of the conventional DPWM changes discontinuously and has many harmonic components. If these harmonics components and the resonant frequency band by a grid-connected LCL-filter are overlapped, the grid current oscillates. To solve this problem, the proposed method uses the 6-th harmonic injection technique to...
The purpose of neutral-point voltage balancing algorithms in a 3L-NPC topology is to eliminate the DC and AC voltage unbalance of top- and bottom-side dc-link voltages. The DC unbalance problem can cause the output current distortion; therefore, this problem has to be solved. The AC unbalance problem means the ripple component of top- and bottom-side dc-link voltages exists. In applications using...
This paper presents a simple fault detection method and fault-tolerant strategy based on the model predictive control theory. The proposed fault detection method can detect and locate a failed switch with current error signals dedicated to each switch, based on the position of space vectors. Following the fault detection, the proposed fault-tolerant control strategies are developed to produce three-phase...
This paper proposes a hybrid parallel three-level converter topology for large wind turbine generation (WTG) systems and its control method. The proposed topology focuses on a machine side of a back-to-back converter. It consists of one conventional three-level neutral-point clamp (NPC) converter and numerous reduced-part converters, which are connected in parallel depending on rated power of a WTG...
In this paper, a controller design is introduced for a interleaved dc-dc converter with an LCLC-filter. In order to design an accurate controller of the bidirectional converter, a new model is proposed. First, it introduces the bidirectional converter small-signal model using a state-space averaging method and derives the required transfer functions. Second, transfer functions of the bidirectional...
This paper proposes a current sensorless maximum power point tracking (MPPT) control strategy for a dual-mode photovoltaic (PV) module-type interleaved flyback inverter (ILFI). A flyback inverter, which is one of many transformer topologies, is generally used because of its simplicity and low cost. The topology used in this paper is the interleaved topology; therefore, the secondary ripple current...
This paper proposes a CLC filter design of a flyback-inverter for photovoltaic systems. This applied system is small power system; therefore, the capacity and size of the entire system are critical factor. The proposed CLC filter consists of a conventional CL filter and an additional capacitor. The CLC filter, which guarantees the same performance about the current ripple reduction as that of the...
This paper proposes an output current ripple reduction algorithm using model-based predictive control (MPC) for an energy storage system (ESS). In single-phase systems, the DC/AC inverter has a second-order harmonic at twice the grid frequency of a DC-link voltage caused by pulsation of the DC-link voltage. The output current of a DC/DC converter has a ripple component because of the ripple of the...
Multi-level rectifier topologies are widely used in applications of the wide-power range. T-type topology, which is one of many three-level topologies, has an advantage in terms of an efficiency compared to a neutral-point clamped (NPC)-type. In applications using T-type rectifier topology, the interest in reliability has been increased recently. Therefore, a tolerance control for T-type rectifiers...
To improve the efficiency of the photovoltaic (PV) system, the centralized topology using three-level inverters are widely used. In this system, PV modules are separately connected to the split DC-links. This causes a decrease of maximum power point tracking (MPPT) efficiency under the partial shading condition. This paper proposes an independent control of two DC-link voltages for separate MPPT of...
This paper presents a simple algorithm for estimation of the rotor position. The injected high frequency voltage is a sinusoidal voltage and is injected into the stator of a motor. An interior permanent magnet synchronous motor (IPMSM) has spatial saliency because d-axis inductance and q-axis inductance are different from each other. The injected high frequency voltage is influenced by saliency. Therefore,...
This paper proposes a model predictive control space vector modulation (MPC-SVM) method for the torque and flux controls of an induction motor. The method to synthesize the reference voltage vectors according to pulse width modulation strategy and the model predictive control method that directly uses the space vector modulation method of the conventional matrix converter are described. Hence, the...
In this paper, the observer based on the flux estimation method is presented. There are reduced-order and full-order types in flux observers based on the flux estimation. Reduced-order flux observers have a simple structure and short calculation time. However, they have drawbacks which comes from noise and disturbance. Therefore, full-order flux observers are used in this paper. Conventional full-order...
This paper proposes an improved model predictive control (MPC) algorithm for the direct torque and flux control of induction motors (IMs) using the three- level inverter. To reduce the calculation amount, which is the drawback of MPC, first the reference value and the state of the motor are analyzed to preselect the calculation region for the cost function; by only subdividing the voltage vectors...
This paper proposes a fault diagnosis and tolerant method for switched reluctance motor (SRM) drives. In many industrial applications, the reliability of the power transistor of the power converter is the main problem. In this paper, two types of faults (short and open) are analyzed through the current pattern of the power converter for SRM drives. The fault is detected when the measured amplitude...
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