— Renewable energies have advantages of zero fuel cost and reduced environmental impacts. This pa... more — Renewable energies have advantages of zero fuel cost and reduced environmental impacts. This paper proposes an Asymmetrical Thirteen level H-Bridge inverter circuit. Two inputs from solar PV panels are given to the converter and maximum power is extracted by using maximum power point tracking method. Integrated converter is DC to DC Boost converter. The output is given to H-inverter which converts dc to ac and the thirteen level output voltage is applied to the load. Operational analysis and simulation results are given for the proposed circuit. Keywords-Dc-Dc Boost converter, FPGA controller, H-Bridge inverter with bi-directional switch circuit, Total harmonic distortion (THD). I. INTRODUCTION With increasing concern in renewable energy systems with various sources becomes greater than before. Renewable energy sources such as photovoltaic (PV) and wind energy can be used to enhance the safety, Reliability and sustainability of a power system. Renewable energy resources will increasingly an important part of power generation in the new millennium. There is an enormous need for integrated power converters that are capable of interfacing and controlling several power terminals with low cost and compact structure. The utilization of natural energy is recognized as a new energy source which will eventually replace conventional energy sources. Renewable energy sources do not have the high external cost and social issues. Renewable energy sources such as wind, solar, fuel cell holds more potential to meet our energy demands. This proposal focuses on control of one major renewable-energy source PV and the output of the PV panel is converted to AC by using the thirteen level asymmetrical H-bridge Inverter configurations. II. MULTILEVEL INVERTER Multilevel inverter is the generation of high voltage using lower voltage rating devices connected in series. Also it has the potential to get a high quality output voltage by producing multi output voltage levels. However it increases the number of switching devices and other components, which result in an increase of complexity problems and systems cost. Many multilevel inverter configurations have been researched to get sinusoidal like output voltage wave with minimum circuit components. A Multilevel inverter has several advantages over a conventional two level converter that uses high switching frequency pulse width modulation (PWM). The attractive features of a multi level inverter can be briefly summarized as follows. Staircase waveform quality: Multilevel inverters not only can generate the output voltages with low distortion, but also can reduce the dv/dt stresses; therefore electromagnetic compatibility (EMC) problems can be reduced. Common mode voltage: Multilevel inverters produce small CM voltage, therefore the stress in the bearings of a motor connected to a multilevel motor drive can be reduced. Furthermore CM voltages can be eliminated by using advanced modulation technique. Input current: Multilevel inverters can draw input current with low distortion. Switching frequency: Multilevel inverters can operate at both fundamental frequency and high switching frequency PWM. It should be noted that lower switching frequency means lower switching loss and higher efficiency. There are several multilevel converters are commercialized for high power applications such as Flexible AC transmission systems (FACTS)
— This paper is devoted to the Quasi Z source network based DC Drive. The cascaded (two-stage) Qu... more — This paper is devoted to the Quasi Z source network based DC Drive. The cascaded (two-stage) Quasi Z Source network could be derived by the adding of one diode, one inductor, and two capacitors to the traditional quasi-Z-source inverter The proposed cascaded qZSI inherits all the advantages of the traditional solution (voltage boost and buck functions in a single stage, continuous input current, and improved reliability). Moreover, as compared to the conventional qZSI, the proposed solution reduces the shoot-through duty cycle by over 30% at the same voltage boost factor. Theoretical analysis of the two-stage qZSI in the shoot-through and non-shoot-through operating modes is described. The proposed and traditional qZSI-networks are compared. A prototype of a Quasi Z Source network based DC Drive was built to verify the theoretical assumptions. The experimental results are presented and analyzed. I. INTRODUCTION The voltage-fed quasi-Z-source inverter has been reported to be suitable for different renewable power applications fuel cells, solar panels, wind power generators, etc, because of its unique capability of voltage boost and buck functions in a single stage. If necessary, the qZSI can boost the input voltage by introducing a special shoot-through switching state, which is the simultaneous conduction (cross conduction) of both switches of the same inverter's phase leg. This switching state is forbidden for the traditional voltage-source inverters because it causes the short circuit of the dc-link capacitors. In the qZSI, the shoot-hence through states are used to boost the magnetic energy stored in the dc-side inductors L1 and L2 without short circuiting the dc capacitors C1 and C2. This increase in magnetic energy, in turn, provides the boost of the voltage seen on the inverter output during traditional operating states. If the input voltage is high enough, the shoot-through states are eliminated, and the qZSI begins to operate as a traditional VSI. This paper discusses a method of performance improvement for the voltage-fed qZSI with continuous input current gained by the introduction of the cascaded quasi-Z-source network. The cascaded (two-stage) qZSI-network is derived by the adding of one diode (D2), one inductor (L3), and two capacitors (C3 and C4) to the traditional qZSI, as shown in Fig. 1. The proposed cascaded qZSI-network enables the duty cycle of the shoot-through state to be sufficiently decreased at the same voltage boost factor and component stresses as those of the traditional qZSI.Due to the decreased shoot through duty cycle, the values of the inductors and capacitors of the qZSI-network could also be decreased. On the other hand, for the same component ratings and voltage and current stresses, the qZSI with the proposed cascaded qZSI-network will ensure a higher voltage boost factor than with traditional solutions.
— Brushless dc motor still suffers from commutation torque ripple, which mainly depends on speed ... more — Brushless dc motor still suffers from commutation torque ripple, which mainly depends on speed and transient line current in the commutation interval. This paper presents a novel circuit topology and a dc link voltage control strategy to keep incoming and outgoing phase currents changing at the same rate during commutation. A dc–dc single-ended primary inductor converter (SEPIC) and a switch selection circuit are employed in front of the inverter. The desired commutation voltage is accomplished by the SEPIC converter. The dc link voltage control strategy is carried out by the switch selection circuit to separate two procedures, adjusting the SEPIC converter and regulating speed. The cause of commutation ripple is analyzed, and the way to obtain the desired dc link voltage is introduced in detail. Finally, simulation and experimental results show that, compared with the dc–dc converter, the proposed method can obtain the desired voltage much faster and minimize commutation torque ripple more efficiently at both high and low speeds and the closed loop control is achieved by Fuzzy logic control. Keywords-Brushless dc motor (BLDCM), commutation, dc link voltage control, single-ended primary inductor converter (SEPIC), torque ripple, PI control. I. INTRODUCTION The BRUSHLESS DC MOTOR (BLDCM) has been widely used in industrial fields that require high reliability and precise control due to its simple structure, high power density, and extended speeding range. The performance of such motors has been significantly improved due to the great development of power electronics, microelectronics, and magnetic performance of magnets, and motion control technology in recent years. However, commutation torque ripple, which usually occurs due to the loss of exact phase current control, has always been one major factor in preventing BLDCM from achieving high performance. So far, many studies have been performed to reduce commutation torque ripple. An original analytical study on commutation torque ripple is presented in, from which a conclusion has been drawn that relative torque ripple is independent of current and varies with speed. A similar analysis is presented in, and the strategy of changing the input voltage to reduce commutation torque ripple is proposed. Both papers are based on some necessary assumptions such as ideal trapezoidal back electromotive force (EMF), very small current hysteresis or pulse width modulation (PWM) cycle, and constant back EMF during commutation, and no implementation of voltage adjustment is demonstrated in them. It is proposed in that a single dc current sensor and a current deadbeat control scheme should be used to keep incoming and outgoing phase currents changing at the same rate during commutation, hence effectively suppressing commutation torque ripple at both high and low speeds. It is an effective method to introduce some special topology of a circuit to BLDCM drives to control its input voltage, as shown by some researchers presented in. In, a buck converter is used, and commutation torque ripple is then greatly reduced at low speed. In, a superlight Luo converter is placed at the entrance of the inverter to produce desired dc link voltage, and the structure is more competent under the high-speed work
— Renewable energy sources have become a popular alternative electrical energy source where power... more — Renewable energy sources have become a popular alternative electrical energy source where power generation in conventional ways is not practical. In the last few years the photovoltaic and wind power generation have been increased significantly. In this study, we proposed a hybrid energy system which combines both solar panel and wind turbine generator as an alternative for conventional source of electrical energy like thermal and hydro power generation. A simple control technique which is also cost effective has been proposed to track the operating point at which maximum power can be coerced from the PV system and wind turbine generator system under continuously changing environmental conditions. The entire hybrid system is described given along with comprehensive simulation results that discover the feasibility of the system. A software simulation model is developed in Matlab/Simulink and the proto type is implemented by using DSPIC30f4011 controller. I. INTRODUCTION Recent developments and trends in the electric power consumption indicate an increasing use of renewable energy. Virtually all regions of the world have renewable resources of one type or another. By this point of view studies on renewable energies focuses more and more attention. Solar energy and wind energy are the two renewable energy sources most common in use. Wind energy has become the least expensive renewable energy technology in existence and has peaked the interest of scientists and educators over the world. Photovoltaic cells convert the energy from sunlight into DC electricity. PVs offer added advantages over other renewable energy sources in that they give off no noise and require practically no maintenance. Hybridizing solar and wind power sources provide a realistic form of power generation. Many studies have been carried out on the use of renewable energy sources for power generation and many projects were presented earlier. The wind and solar energy systems are highly unreliable due to their unpredictable nature. In a PV panel was incorporated with a diesel electric power system to analyze the reduction in the fuel consumed. It was seen that the incorporation of an additional renewable source can further reduce the fuel consumption. When a source is unavailable or insufficient in meeting the load demands, the other energy source can compensate for the difference. Several hybrid wind/PV power systems with Maximum Power Point Tracking (MPPT) control have been proposed earlier. They used a separate DC/DC buck and buck-boost converter connected in fusion in the rectifier stage to perform the MPPT control for each of the renewable energy power sources. These systems have a problem that, due to the environmental factors influencing the wind turbine generator, high frequency current harmonics are injected into it. Buck and buck-boost converters do not have the capability to eliminate these harmonics. So the system requires passive input filters to remove it, making the system more bulky and expensive. In this project, a new converter topology for hybridizing the wind and solar energy sources has been proposed. In this topology, both wind and solar energy sources are incorporated together using a combination of two modified SEPIC converters, so that if one of
— Renewable energies have advantages of zero fuel cost and reduced environmental impacts. This pa... more — Renewable energies have advantages of zero fuel cost and reduced environmental impacts. This paper proposes an Asymmetrical Thirteen level H-Bridge inverter circuit. Two inputs from solar PV panels are given to the converter and maximum power is extracted by using maximum power point tracking method. Integrated converter is DC to DC Boost converter. The output is given to H-inverter which converts dc to ac and the thirteen level output voltage is applied to the load. Operational analysis and simulation results are given for the proposed circuit. Keywords-Dc-Dc Boost converter, FPGA controller, H-Bridge inverter with bi-directional switch circuit, Total harmonic distortion (THD). I. INTRODUCTION With increasing concern in renewable energy systems with various sources becomes greater than before. Renewable energy sources such as photovoltaic (PV) and wind energy can be used to enhance the safety, Reliability and sustainability of a power system. Renewable energy resources will increasingly an important part of power generation in the new millennium. There is an enormous need for integrated power converters that are capable of interfacing and controlling several power terminals with low cost and compact structure. The utilization of natural energy is recognized as a new energy source which will eventually replace conventional energy sources. Renewable energy sources do not have the high external cost and social issues. Renewable energy sources such as wind, solar, fuel cell holds more potential to meet our energy demands. This proposal focuses on control of one major renewable-energy source PV and the output of the PV panel is converted to AC by using the thirteen level asymmetrical H-bridge Inverter configurations. II. MULTILEVEL INVERTER Multilevel inverter is the generation of high voltage using lower voltage rating devices connected in series. Also it has the potential to get a high quality output voltage by producing multi output voltage levels. However it increases the number of switching devices and other components, which result in an increase of complexity problems and systems cost. Many multilevel inverter configurations have been researched to get sinusoidal like output voltage wave with minimum circuit components. A Multilevel inverter has several advantages over a conventional two level converter that uses high switching frequency pulse width modulation (PWM). The attractive features of a multi level inverter can be briefly summarized as follows. Staircase waveform quality: Multilevel inverters not only can generate the output voltages with low distortion, but also can reduce the dv/dt stresses; therefore electromagnetic compatibility (EMC) problems can be reduced. Common mode voltage: Multilevel inverters produce small CM voltage, therefore the stress in the bearings of a motor connected to a multilevel motor drive can be reduced. Furthermore CM voltages can be eliminated by using advanced modulation technique. Input current: Multilevel inverters can draw input current with low distortion. Switching frequency: Multilevel inverters can operate at both fundamental frequency and high switching frequency PWM. It should be noted that lower switching frequency means lower switching loss and higher efficiency. There are several multilevel converters are commercialized for high power applications such as Flexible AC transmission systems (FACTS)
— Renewable energies have advantages of zero fuel cost and reduced environmental impacts. This pa... more — Renewable energies have advantages of zero fuel cost and reduced environmental impacts. This paper proposes an Asymmetrical Thirteen level H-Bridge inverter circuit. Two inputs from solar PV panels are given to the converter and maximum power is extracted by using maximum power point tracking method. Integrated converter is DC to DC Boost converter. The output is given to H-inverter which converts dc to ac and the thirteen level output voltage is applied to the load. Operational analysis and simulation results are given for the proposed circuit. Keywords-Dc-Dc Boost converter, FPGA controller, H-Bridge inverter with bi-directional switch circuit, Total harmonic distortion (THD). I. INTRODUCTION With increasing concern in renewable energy systems with various sources becomes greater than before. Renewable energy sources such as photovoltaic (PV) and wind energy can be used to enhance the safety, Reliability and sustainability of a power system. Renewable energy resources will increasingly an important part of power generation in the new millennium. There is an enormous need for integrated power converters that are capable of interfacing and controlling several power terminals with low cost and compact structure. The utilization of natural energy is recognized as a new energy source which will eventually replace conventional energy sources. Renewable energy sources do not have the high external cost and social issues. Renewable energy sources such as wind, solar, fuel cell holds more potential to meet our energy demands. This proposal focuses on control of one major renewable-energy source PV and the output of the PV panel is converted to AC by using the thirteen level asymmetrical H-bridge Inverter configurations. II. MULTILEVEL INVERTER Multilevel inverter is the generation of high voltage using lower voltage rating devices connected in series. Also it has the potential to get a high quality output voltage by producing multi output voltage levels. However it increases the number of switching devices and other components, which result in an increase of complexity problems and systems cost. Many multilevel inverter configurations have been researched to get sinusoidal like output voltage wave with minimum circuit components. A Multilevel inverter has several advantages over a conventional two level converter that uses high switching frequency pulse width modulation (PWM). The attractive features of a multi level inverter can be briefly summarized as follows. Staircase waveform quality: Multilevel inverters not only can generate the output voltages with low distortion, but also can reduce the dv/dt stresses; therefore electromagnetic compatibility (EMC) problems can be reduced. Common mode voltage: Multilevel inverters produce small CM voltage, therefore the stress in the bearings of a motor connected to a multilevel motor drive can be reduced. Furthermore CM voltages can be eliminated by using advanced modulation technique. Input current: Multilevel inverters can draw input current with low distortion. Switching frequency: Multilevel inverters can operate at both fundamental frequency and high switching frequency PWM. It should be noted that lower switching frequency means lower switching loss and higher efficiency. There are several multilevel converters are commercialized for high power applications such as Flexible AC transmission systems (FACTS)
— This paper is devoted to the Quasi Z source network based DC Drive. The cascaded (two-stage) Qu... more — This paper is devoted to the Quasi Z source network based DC Drive. The cascaded (two-stage) Quasi Z Source network could be derived by the adding of one diode, one inductor, and two capacitors to the traditional quasi-Z-source inverter The proposed cascaded qZSI inherits all the advantages of the traditional solution (voltage boost and buck functions in a single stage, continuous input current, and improved reliability). Moreover, as compared to the conventional qZSI, the proposed solution reduces the shoot-through duty cycle by over 30% at the same voltage boost factor. Theoretical analysis of the two-stage qZSI in the shoot-through and non-shoot-through operating modes is described. The proposed and traditional qZSI-networks are compared. A prototype of a Quasi Z Source network based DC Drive was built to verify the theoretical assumptions. The experimental results are presented and analyzed. I. INTRODUCTION The voltage-fed quasi-Z-source inverter has been reported to be suitable for different renewable power applications fuel cells, solar panels, wind power generators, etc, because of its unique capability of voltage boost and buck functions in a single stage. If necessary, the qZSI can boost the input voltage by introducing a special shoot-through switching state, which is the simultaneous conduction (cross conduction) of both switches of the same inverter's phase leg. This switching state is forbidden for the traditional voltage-source inverters because it causes the short circuit of the dc-link capacitors. In the qZSI, the shoot-hence through states are used to boost the magnetic energy stored in the dc-side inductors L1 and L2 without short circuiting the dc capacitors C1 and C2. This increase in magnetic energy, in turn, provides the boost of the voltage seen on the inverter output during traditional operating states. If the input voltage is high enough, the shoot-through states are eliminated, and the qZSI begins to operate as a traditional VSI. This paper discusses a method of performance improvement for the voltage-fed qZSI with continuous input current gained by the introduction of the cascaded quasi-Z-source network. The cascaded (two-stage) qZSI-network is derived by the adding of one diode (D2), one inductor (L3), and two capacitors (C3 and C4) to the traditional qZSI, as shown in Fig. 1. The proposed cascaded qZSI-network enables the duty cycle of the shoot-through state to be sufficiently decreased at the same voltage boost factor and component stresses as those of the traditional qZSI.Due to the decreased shoot through duty cycle, the values of the inductors and capacitors of the qZSI-network could also be decreased. On the other hand, for the same component ratings and voltage and current stresses, the qZSI with the proposed cascaded qZSI-network will ensure a higher voltage boost factor than with traditional solutions.
— Brushless dc motor still suffers from commutation torque ripple, which mainly depends on speed ... more — Brushless dc motor still suffers from commutation torque ripple, which mainly depends on speed and transient line current in the commutation interval. This paper presents a novel circuit topology and a dc link voltage control strategy to keep incoming and outgoing phase currents changing at the same rate during commutation. A dc–dc single-ended primary inductor converter (SEPIC) and a switch selection circuit are employed in front of the inverter. The desired commutation voltage is accomplished by the SEPIC converter. The dc link voltage control strategy is carried out by the switch selection circuit to separate two procedures, adjusting the SEPIC converter and regulating speed. The cause of commutation ripple is analyzed, and the way to obtain the desired dc link voltage is introduced in detail. Finally, simulation and experimental results show that, compared with the dc–dc converter, the proposed method can obtain the desired voltage much faster and minimize commutation torque ripple more efficiently at both high and low speeds and the closed loop control is achieved by Fuzzy logic control. Keywords-Brushless dc motor (BLDCM), commutation, dc link voltage control, single-ended primary inductor converter (SEPIC), torque ripple, PI control. I. INTRODUCTION The BRUSHLESS DC MOTOR (BLDCM) has been widely used in industrial fields that require high reliability and precise control due to its simple structure, high power density, and extended speeding range. The performance of such motors has been significantly improved due to the great development of power electronics, microelectronics, and magnetic performance of magnets, and motion control technology in recent years. However, commutation torque ripple, which usually occurs due to the loss of exact phase current control, has always been one major factor in preventing BLDCM from achieving high performance. So far, many studies have been performed to reduce commutation torque ripple. An original analytical study on commutation torque ripple is presented in, from which a conclusion has been drawn that relative torque ripple is independent of current and varies with speed. A similar analysis is presented in, and the strategy of changing the input voltage to reduce commutation torque ripple is proposed. Both papers are based on some necessary assumptions such as ideal trapezoidal back electromotive force (EMF), very small current hysteresis or pulse width modulation (PWM) cycle, and constant back EMF during commutation, and no implementation of voltage adjustment is demonstrated in them. It is proposed in that a single dc current sensor and a current deadbeat control scheme should be used to keep incoming and outgoing phase currents changing at the same rate during commutation, hence effectively suppressing commutation torque ripple at both high and low speeds. It is an effective method to introduce some special topology of a circuit to BLDCM drives to control its input voltage, as shown by some researchers presented in. In, a buck converter is used, and commutation torque ripple is then greatly reduced at low speed. In, a superlight Luo converter is placed at the entrance of the inverter to produce desired dc link voltage, and the structure is more competent under the high-speed work
— Renewable energy sources have become a popular alternative electrical energy source where power... more — Renewable energy sources have become a popular alternative electrical energy source where power generation in conventional ways is not practical. In the last few years the photovoltaic and wind power generation have been increased significantly. In this study, we proposed a hybrid energy system which combines both solar panel and wind turbine generator as an alternative for conventional source of electrical energy like thermal and hydro power generation. A simple control technique which is also cost effective has been proposed to track the operating point at which maximum power can be coerced from the PV system and wind turbine generator system under continuously changing environmental conditions. The entire hybrid system is described given along with comprehensive simulation results that discover the feasibility of the system. A software simulation model is developed in Matlab/Simulink and the proto type is implemented by using DSPIC30f4011 controller. I. INTRODUCTION Recent developments and trends in the electric power consumption indicate an increasing use of renewable energy. Virtually all regions of the world have renewable resources of one type or another. By this point of view studies on renewable energies focuses more and more attention. Solar energy and wind energy are the two renewable energy sources most common in use. Wind energy has become the least expensive renewable energy technology in existence and has peaked the interest of scientists and educators over the world. Photovoltaic cells convert the energy from sunlight into DC electricity. PVs offer added advantages over other renewable energy sources in that they give off no noise and require practically no maintenance. Hybridizing solar and wind power sources provide a realistic form of power generation. Many studies have been carried out on the use of renewable energy sources for power generation and many projects were presented earlier. The wind and solar energy systems are highly unreliable due to their unpredictable nature. In a PV panel was incorporated with a diesel electric power system to analyze the reduction in the fuel consumed. It was seen that the incorporation of an additional renewable source can further reduce the fuel consumption. When a source is unavailable or insufficient in meeting the load demands, the other energy source can compensate for the difference. Several hybrid wind/PV power systems with Maximum Power Point Tracking (MPPT) control have been proposed earlier. They used a separate DC/DC buck and buck-boost converter connected in fusion in the rectifier stage to perform the MPPT control for each of the renewable energy power sources. These systems have a problem that, due to the environmental factors influencing the wind turbine generator, high frequency current harmonics are injected into it. Buck and buck-boost converters do not have the capability to eliminate these harmonics. So the system requires passive input filters to remove it, making the system more bulky and expensive. In this project, a new converter topology for hybridizing the wind and solar energy sources has been proposed. In this topology, both wind and solar energy sources are incorporated together using a combination of two modified SEPIC converters, so that if one of
— Renewable energies have advantages of zero fuel cost and reduced environmental impacts. This pa... more — Renewable energies have advantages of zero fuel cost and reduced environmental impacts. This paper proposes an Asymmetrical Thirteen level H-Bridge inverter circuit. Two inputs from solar PV panels are given to the converter and maximum power is extracted by using maximum power point tracking method. Integrated converter is DC to DC Boost converter. The output is given to H-inverter which converts dc to ac and the thirteen level output voltage is applied to the load. Operational analysis and simulation results are given for the proposed circuit. Keywords-Dc-Dc Boost converter, FPGA controller, H-Bridge inverter with bi-directional switch circuit, Total harmonic distortion (THD). I. INTRODUCTION With increasing concern in renewable energy systems with various sources becomes greater than before. Renewable energy sources such as photovoltaic (PV) and wind energy can be used to enhance the safety, Reliability and sustainability of a power system. Renewable energy resources will increasingly an important part of power generation in the new millennium. There is an enormous need for integrated power converters that are capable of interfacing and controlling several power terminals with low cost and compact structure. The utilization of natural energy is recognized as a new energy source which will eventually replace conventional energy sources. Renewable energy sources do not have the high external cost and social issues. Renewable energy sources such as wind, solar, fuel cell holds more potential to meet our energy demands. This proposal focuses on control of one major renewable-energy source PV and the output of the PV panel is converted to AC by using the thirteen level asymmetrical H-bridge Inverter configurations. II. MULTILEVEL INVERTER Multilevel inverter is the generation of high voltage using lower voltage rating devices connected in series. Also it has the potential to get a high quality output voltage by producing multi output voltage levels. However it increases the number of switching devices and other components, which result in an increase of complexity problems and systems cost. Many multilevel inverter configurations have been researched to get sinusoidal like output voltage wave with minimum circuit components. A Multilevel inverter has several advantages over a conventional two level converter that uses high switching frequency pulse width modulation (PWM). The attractive features of a multi level inverter can be briefly summarized as follows. Staircase waveform quality: Multilevel inverters not only can generate the output voltages with low distortion, but also can reduce the dv/dt stresses; therefore electromagnetic compatibility (EMC) problems can be reduced. Common mode voltage: Multilevel inverters produce small CM voltage, therefore the stress in the bearings of a motor connected to a multilevel motor drive can be reduced. Furthermore CM voltages can be eliminated by using advanced modulation technique. Input current: Multilevel inverters can draw input current with low distortion. Switching frequency: Multilevel inverters can operate at both fundamental frequency and high switching frequency PWM. It should be noted that lower switching frequency means lower switching loss and higher efficiency. There are several multilevel converters are commercialized for high power applications such as Flexible AC transmission systems (FACTS)
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