Dc Bus Voltage Of Inverter Research Articles

Ultra-Voltage Gain Step-Up DC-DC Converter for Renewable Energy Micro-Source Applications

In renewable energy micro-source applications, a wide range of voltage conversion of the step-up converter is an essential part to equalize the typical low voltage of micro-source with DC-bus voltage of Inverter or motor drives. In order to meet this purpose, an ultra-voltage gain step-up DC-DC converter is proposed in this paper. The proposed converter has made an arrangement of the regenerative-boost fed switched inductor and capacitor configurations. Thereby, due to such an organization of structure, the proposed converter can develop an extremely high voltage-gain even at lower duty ratios. In addition, it has the advantage of lower switching stress across all power semi-conductive diodes. Furthermore, this paper describes the steady-state analysis and comparative features of the converter with existing recent literature. Finally, to validate theoretical analysis and test the feasibility and suitability of the proposed ultra-gain converter, the experimental results were observed by a 500 W fabricated prototype.

A New Approach of BLDC Motor Using Fuzzy Fractional Order PID

In order to manage the speed of brushless DC (BLDC) motors, this research presents a novel hybrid control method that simultaneously regulates the DC bus voltage of the inverter and the BLDC motor reference current. A fractional-order PID (FOPID) controller manages the BLDC motor reference current, and a fuzzy logic controller manages the inverter DC bus voltage. A modified harmony search (HS) metaheuristic technique is developed for adjusting the FOPID controller parameters. Three separate working scenarios—no load, varying load, and varying speed—are used to test the motor's capabilities. Run the proposed controller at a high speed to verify its efficacy. The suggested hybrid control method has also been put to the test. weighed against FOPID and fuzzy-based speed control techniques The outcomes demonstrate the effectiveness of the suggested control. approach enables more accurate speed control over a wide region.

Nonlinear control of active power filter connected to photovoltaic system

The paper presents a nonlinear control of shunt active power filter operating in presence of nonlinear loads. The said filter is connected to PV system in order to deliver the active power to load. The main control objectives are: (i) compensation of harmonic currents and the reactive power caused by the nonlinear load; (ii) regulation the DC bus voltage of inverter. The control problem is dealt with a nonlinear controller that is developed by using the Lyapunov technique to cope with the harmonic’s issue. The outer-loop regulates the DC bus voltage of the static converter. The controller performances are validated by simulation in MATLAB\\Simulink.

Sampled‐data adaptive nonlinear control of shunt power filters

AbstractThis study is on the control of shunt power filters associated with nonlinear loads. Specifically, The focus is made on single‐phase half‐bridge filters and the aim is to design a controller meeting two requirements: (1) the effect of current harmonics and reactive power is compensated for so that a power factor close to unity is achieved at the point of common coupling (PCC); (2) the inverter DC bus voltage is satisfactorily regulated. To meet these requirements, we propose a (two‐loop) cascade adaptive controller that is designed on the basis of the system nonlinear model, using Lyapunov stability tools. Compared to existing controllers, the present controller has three major features. It is adaptive compensating for parameter uncertainty. It is output feedback in the sense that it involves an observer estimating online the inaccessible signals. It is sampled‐data and so is immediately implementable using digital means. In addition to theoretical analysis, the performances of the proposed controller are evaluated by simulation using MATLAB/Simulink.

Hybrid Fuzzy Fractional-Order PID-Based Speed Control for Brushless DC Motor

This article presents a novel hybrid control scheme for speed control of Brushless DC (BLDC) motor by simultaneously controlling BLDC motor reference current and inverter DC bus voltage. A fractional-order PID (FOPID) controller is employed to control BLDC motor reference current while a fuzzy logic controller manipulates the inverter DC bus voltage. A modified harmony search (HS) metaheuristic technique is developed for FOPID controller parameters tuning. Three different operating conditions are applied to test the motor, including no-load operation, varying load operation, and varying speed operation to verify the proposed controller’s effectiveness. Furthermore, the proposed hybrid control strategy has been compared to Fuzzy-based and FOPID-based speed control schemes. The obtained results confirm that the proposed control scheme provides better and accurate speed control over a wide range of speeds. Also, the proposed controller decreases the torque ripples under different operating conditions.

Dynamic performance comparison involving grid‐connected PV systems operating with active power‐line conditioning and subjected to sudden solar irradiation changes

This study presents a comparative performance analysis involving single- and double-stage photovoltaic (PV) systems, which are connected to a three-phase four-wire electrical system by means of a four-leg inverter topology. The double-stage PV system is composed of a step-up DC/DC converter and a four-leg grid-connected inverter, while in the single-stage PV system the PV array is directly connected to the inverter DC bus. In addition to the active power injection into the grid, both PV systems have two attractive features, described as follows: (i) power quality improvement due to their capability to perform active power-line conditioning, such as load harmonic current suppression, reactive power compensation, and load unbalance compensation; (ii) dynamic improvement in the occurrence of abrupt solar irradiation variations, which is achieved through the implementation of a feed-forward control loop (FFCL) acting directly in the inverter DC-bus voltage control loop, resulting in speeding up of the dynamics of both the DC-bus voltage and the injected grid-inverter currents. The referred comparative analysis addresses the static and dynamic performances considering the PV systems operating under the action of the FFCL, as well as performing active power-line conditioning. Simulation and experimental results are presented to evaluate and validate the proposed study.

A Fast On-Line Diagnostic Method for Open-Circuit Switch Faults in SiC-MOSFET-Based T-Type Multilevel Inverters

On-line condition monitoring is of paramount importance for multilevel power converters used in safety-critical applications. A novel on-line nonintrusive diagnostic method for detecting open-circuit switch faults in silicon carbide (SiC) metal-oxide-semiconductor field-effect transistors (MOSFETs)-based T-type multilevel converters is introduced in this paper. The principle of this method is based on monitoring the abnormal variations of the dc-bus neutral-point current in combination with the existing information on instantaneous switching states and phase currents. Advantages of this method include faster detection speed and simpler implementation compared to other existing diagnostic methods in the literature. Moreover, this diagnostic method is immune to the disturbances of inverter's dc-bus voltage unbalance and load unbalance. In this method, only one additional current sensor is required for measuring the dc-bus neutral-point current; therefore, the implementation cost is low. Simulation and experimental results based on a lab-scale 20 kVA adjustable speed drive with a three-level SiC T-type inverter validate the effectiveness and robustness of this novel diagnostic method.

Impact of the Inverter DC Bus Voltage on the Iron Losses of a Permanent Magnet Synchronous Motor at Constant Speed

Impact of the Inverter DC Bus Voltage on the Iron Losses of a Permanent Magnet Synchronous Motor at Constant Speed

Sensorless control of inverter dc-bus voltage combined with modified PQ control using extended Kalman filter in a photovoltaic system

this paper presents a sensorless control approach of inverter dc-bus voltage using extended Kalman Filter (EKF). A positive sequence detection of grid voltage and load current is also proposed. The dc-bus voltage estimated by EKF is combined with the modified instantaneous power (p–q) control technique for photovoltaic system application to improve electrical energy quality at the grid under photovoltaic (PV) varying temperature and radiation and also distorted grid voltage ensuring at the same time the supply of unbalanced nonlinear load. The ac grid receives the required active power from the PV cells through boost converter, dc-bus and inverter. It supplies the energy to unbalanced nonlinear load in case of absence of PV energy. The boost converter control extracts the maximum power point from PV cells by Disturb and Observe (P&O) algorithm. Mathematical relationships of different parts of PV system are described and studied. The control system is simulated using the SimPower blockset of Matlab/Simulink. Simulation results have showed that the proposed methodology is an efficient solution to PV control system.

DC-Bus Voltage Range Extension in 1500 V Photovoltaic Inverters

Solar plants based on single-stage conversion photovoltaic (PV) inverters (no dc–dc boost stage) have gained popularity due to their simplicity, high efficiency, and cost effectiveness. Existing PV plants mostly operate under 1000 V and are subject to wide dc-bus voltage variations due to the effect of PV cell temperature and the voltage of the maximum power point (well below the open-circuit voltage). In particular, attractive locations, such as U.S.–Canada mountain and central regions, are subject to extreme PV surface temperatures, making the dc-bus voltage variation a challenge for single-stage solar inverters. This paper investigates 1500 V solar inverters with a focus on dc-bus voltage range extension capabilities through novel modulation and power devices utilization. A comparative analysis with the existing 1000 V solar inverters is presented to illustrate the significant advantages of the wide dc-bus range in 1500 V systems. A lower voltage limit in the dc-bus is achieved by employing a novel voltage reactive power dc-bus control strategy and modified modulation. A higher dc-bus peak voltage is obtained by maximizing the use of power switches. As a result, the 1500 V inverter dc-bus voltage is significantly extended to capture energy under extreme PV surface temperatures, greatly improving the limited range of traditional 1000 V inverters. Simulations and experimental results using a three-phase three-level neutral point-clamped inverter level are presented to validate the proposed dc-bus extension range, control strategy, and modulation scheme.

Contributions to the Design of Derivative Hybrid Filters: Modeling and Analysis in Distorted Voltage Grids

Hybrid Filters (HF) are chosen as a solution to mitigate line harmonic currents mainly due to their characteristic of merging the active and passive filter advantages in a single structure. Consequentially, the processed power is shared between these parts. There are different sorts of HF. The Derivative Hybrid Filter (DHF) consists in connecting an Active Filter (AF) in derivation to a Tuned Passive Filter (TPF). This paper presents contributions to the design of DHF. A small-signal model is obtained taking into account both the AF and the TPF dynamic behavior. The small-signal model represents the relationship between the line current and the AF inverter duty cycle. The relationship between the inverter DC Bus voltage and the line current is also described by a small-signal model. Once with the obtained small-signal models, stability analysis and controller design process will be described. Additionally, the paper presents a methodology to obtain the minimum required inverter DC Bus voltage for the DHF considering the existence of harmonic distortion in the voltage grid. Experimental results show the efficacy of the covered contributions.

Proposed Inverter DC Bus Voltage Control Method and Capacitance Reduction Method for Mass Motor Drive

In this study, a new control method for the power supply of a mass motor is proposed. The reference voltage of the power supply is calculated digitally according to the energy conservation law. Specifically, this method takes into account a servo motor's rotational energy to control the output voltage by inputting an angular velocity to the digital controller. With this method, the voltage ripple of the power supply output is calculated to be reduced by about 40% compared conventional method. This also facilitates the reduction of the output capacitance and peak current and extension of the operating life.

PERFORMANCE OF CASCADED H-BRIDGE INVERTER INTEGRATED WITH HFT FOR PV SYSTEM APPLICATIONS

This paper presents a photovoltaic system as a standalone system. The proposed systemconsists of photovoltaic (PV) module, battery energy storage system (BESS), high frequencytransformer, and multilevel inverter (MLI). The MLI consists of two H-bridge single phase inverterper arm (phase) with unequal dc voltages which needs 6 isolated de sources for the conventionalMLI. The relative values between the upper (auxiliary) inverter dc voltage and the lower H-bridge(main) inverter is 1/3 resulting in 9 levels MLI. Each isolated dc source comes from a PV moduleaccompany with a BESS. A high frequency transformer (HFT) is proposed in this paper to generatethe dc bus voltage of the auxiliary inverter from the main inverter dc bus voltage. As a result of thatthe number of isolated dc bus voltages required is reduced by half which is reflected in reducing thenumber of PV required and thus reducing the cost of the overall system. In addition, a naturalbalancing between the main and auxiliary inverters dc bus voltages of each arm will be attained dueto the HFT turns ratio which result in simplifying the overall control of the whole system. In order toreduce the size of the HFT a judicious modulation index (MI) will be chosen. The proposed systemhas been simulated using static inductive load. Analyses and simulation have been proposed tovalidate the proposed control scheme.

Novel Field-Weakening Control Scheme for Permanent-Magnet Synchronous Machines Based on Voltage Angle Control

This paper presents a novel voltage-angle-based field-weakening control scheme appropriate for the operation of permanent-magnet synchronous machines over a wide range of speed. At high rotational speed, the stator voltage is limited by the inverter dc bus voltage. To control the machine torque above the base speed, the proposed method controls the angle of the limited stator voltage by the integration of gain-scheduled q-axis current error. The stability of the drive is increased by a feedback loop, which compensates dynamic disturbances and smoothes the transition into field weakening. The proposed method can fully utilize the available dc bus voltage. Due to its simplicity, it is robust to the variation of machine parameters. Excellent performance of the proposed method is demonstrated through the experiments performed with and without speed and position sensors.

Characteristics of Partial Discharge Pulse Count Rate and Surge Voltage at Motor Terminal under Inverter Drives

In inverter-fed motor systems, output voltage of the inverter has a rectangular waveform with rise time of a few tens of nanoseconds, and consequently a motor suffers from repetitive surge pulses which may have adverse effect on motor insulation. Therefore it is very important to know partial discharge (PD) characteristics during inverter operation especially if there were insulation defects. We have investigated the PD characteristics under inverter surge during actual motor operation, especially about the dependence of PD pulse count rate on inverter DC bus voltage when PD defect exists at phase-phase or phase-ground at motor terminal. As a result, we found that the characteristics of PD pulse count rate depend on DC bus voltage considerably and differs whether the PD defect is at phase-phase or phase-ground. When PD defect is at phase-phase, the PD pulse count rate reaches immediately twice of the power frequency above the PD inception voltage and become constant even if the DC bus voltage is increase, and when the DC bus voltage is further increased, PD pulse count rate starts to increase again. On the other hand, when PD defect is at phase-ground, the PD pulse count rate has increased monotonously with the DC bus voltage until PD pulse count rate has reached twice of carrier frequency. This difference is caused by the difference of the voltage waveform between phase-phase voltage and phase-ground voltage under inverter drives. Therefore, we concluded that it is possible to distinguish whether the PD source is at phase-phase or phase-ground by the dependence of PD pulse count rate on the DC bus voltage.