Abstract: A power supply system comprises an alternating-current sweep unit that outputs alternating-current power from a U-phase battery string, a V-phase battery string, and a W-phase battery string that are Y-connected, a first power supply circuit that converts output of a direct-current sweep unit to alternating-current power using an inverter and outputs the alternating-current power, the direct-current sweep unit including a first battery string; and a control device. An energy density of a battery included in the U-phase battery string, the V-phase battery string, and the W-phase battery string is higher than an energy density of a battery included in the first battery string.

Abstract: A circuit for driving the voltage of a capacitive element between two voltage levels has at least one driver cell with a first pair of switches connected in series between a first terminal of a voltage source and the capacitive element, and a second pair of switches connected in series between a second terminal of the voltage source and the capacitive element. A plurality of non-dissipative elements may be connected in parallel or in series between the first pair of switches and the second pair of switches. Combinations of switches from the driver cells may be activated and deactivated in a defined sequence to provide step-wise transfer of energy to the capacitive element. The defined sequence may have a switching pattern with a voltage change portion arranged to cause a change in an output voltage of the capacitive element driver during application thereof on the capacitive element driver.

Abstract: In a power supply system, a control device is configured to select one or more target batteries that are to perform requested energy management from a plurality of batteries included in an alternating-current battery string and a direct-current battery string, and perform the requested energy management using the one or more target batteries with the batteries other than the one or more target batteries being disconnected from a circuit.

Abstract: This application is directed to an apparatus for providing electrical charge to a vehicle. The apparatus can comprise a generator, a hardware controller, a capacitor, and a battery. The controller can control whether the capacitor is electrically coupled with the battery based on one or more conditions. The controller can control whether the generator is electrically coupled with the capacitor and/or the battery.

Abstract: A multi-cell rechargeable energy storage system (RESS) includes a plurality of battery cells organized into battery modules and a first enclosure configured to house the battery modules. The RESS also includes a first vent arranged on the first enclosure and configured to direct air from inside the first enclosure to an environment external to the first enclosure. The RESS additionally includes a second vent arranged on the first enclosure and configured to direct air into the first enclosure from the environment external to the first enclosure. The RESS further includes a phase-change material (PCM) device arranged on the second vent and configured to melt in response to at least one of the battery modules experiencing a thermal runaway event. In combination with the first vent, the PCM generates crossflow ventilation through the first enclosure to cool the battery modules therein and mitigate thermal runaway.

Abstract: Disclosed herein is add-on electronic circuit structures and methods for providing protection against reverse-electrical-current failures and for enabling comprehensive electrical (current-voltage sweep) and electro-optical (electroluminescence or EL using reserve current flow) testing of solar photovoltaic cells and modules having at least one multi-modal maximum-power-point tracking (MPPT) power optimizer integrated circuit chip to increase electrical energy generation yield of the modules. Such multi-modal MPPT power optimizer chips are used for distributed solar electric power generation enhancement in solar photovoltaic cells, modules, and systems under realistic operating conditions with non-ideal manufacturing and environmental variations (e.g., variable and/or non-uniform sunlight or daylight, mismatched cells, etc.).

Abstract: Systems for a current limiting circuit are provided. Aspects include a first set of batteries coupled to a battery terminal, a power converter coupled to a power converter terminal, wherein the battery terminal is coupled to the power converter terminal, a first current limiting circuit in series with the first set of batteries, wherein the current limiting circuit comprises a first circuit comprising a first transistor in series with a first diode, a second circuit comprising a second transistor in series with a second diode, a first RL circuit, wherein the first RL circuit, the first circuit, and the second circuit are arranged in parallel, a controller configured to operate the first current limiter in a plurality of modes including a battery discharge mode including the controller operating the first transistor in an off state, and operating the second transistor in a switching state.

Abstract: According to embodiments described herein a Modular Multilevel Converter (MMC) is pre-charged by: driving a bypass current from an auxiliary power source through a plurality of bypass switches included in a corresponding plurality of cells; in response to a summed voltage across a plurality of cell capacitors included in the plurality of cells satisfying a drive threshold, driving an insert current through a plurality of insert switches included in the plurality of cells; and in response to a voltage across a Direct Current (DC) link capacitor satisfying a pre-charge threshold when driving the insert current, opening a circuit breaker connecting the auxiliary power source with the plurality of cells and connecting a generator with external power line rails between which the DC link capacitor is connected.

Abstract: A system in a vehicle includes a first winding section including first two or more windings and a second winding section including second two or more windings. Each of the second two or more windings corresponds to one of the first two or more windings of the first winding section. The system also includes an inverter including a high side switch and a low side switch corresponding to each of the first two or more windings. The inverter is coupled to a battery of the vehicle and boosts a voltage of a direct current (DC) charger during charging of the battery with the DC charger, converts alternating current (AC) from an AC grid to DC during charging of the battery with the AC grid, and converts DC to AC during supply of the AC grid by the battery.

Abstract: The present invention relates to an apparatus for maximizing the power of a multi module solar string power generation system, comprising an Injection Circuit (IC), connected to a DC bus and to a string of solar panels, wherein the IC is also connected to at least one separated solar panel of the string. The IC regulates the power production of the connected string and utilizes the excess power to the solar inverter. The IC comprises: (i) a first MPPT mechanism, for finding the MPP of the string; (ii) a second MPPT mechanism, for finding the MPP of the separated panel; (iii) a first DC/DC converter, for converting some of the power, from the separated panel, to regulating power for the connected string; and (iv) a second DC/DC converter, for converting and utilizing, the excess power from the separated panel, to the solar inverter using the DC bus.

Abstract: A modular motor system and methods wherein at least two dual radial gap motors with attachment points may be joined together in a modular manner for the purpose of providing the capability of incrementally increasing or decreasing the total power output of the modular.

Abstract: Provided is a bridge cascade system, which includes at least one phase unit and a driving unit for the phase unit. The phase unit includes N bridge topologies cascaded on alternating current AC sides. The driving unit includes one driving power supply circuit, multiple bootstrap power supply circuits and 2N driving circuits. In the phase unit, the driving circuits are powered by the driving power supply circuit directly or through corresponding bootstrap power supply circuits. The driving circuits are configured to provide driving signals for corresponding switch transistors in the phase unit. In this way, one driving power supply is matched with multiple bootstrap power supply circuits, realizing power supply to the driving circuits corresponding to the switch transistors of all bridge topologies, which reduces the difficulty in designing the driving power supply for the bridge cascade system and reduces cost for the system.

Abstract: Provided is a power supply apparatus that supplies power received from an external power supply to a load, the power supply apparatus comprising: a plurality of power supply circuitries, each of which has switching elements, that are allowed to supply power to the load separately; and a processor that controls a number of the power supply circuitries supplying power to the load according to a required power level of the load.

Abstract: A system includes a plurality of power modules connected in series between two input terminals of an inverter, a plurality of local controllers coupled to their respective power modules, wherein a first local controller of the plurality of local controllers is coupled to a first power module comprising a first solar panel, a first capacitor and a first power optimizer, and wherein the first local controller is configured to enable the first power optimizer to switch among a buck mode, a boost mode and a pass-through mode based upon a maximum power point tracking (MPPT) current of the first solar panel, and a central controller coupled to the inverter, wherein the central controller is configured to regulate an input voltage of the inverter.

Abstract: An apparatus may determine a parameter related to a voltage value at a midpoint terminal of a system power device, and may adjust a voltage applied to a second terminal of the system power device based on the parameter and a reference value. The second terminal may be different from the midpoint terminal.

Abstract: Provided is a wireless battery control system, a method and a battery pack. The system includes a master, and a plurality of slaves sequentially positioned at different distances from the master. The master wirelessly transmit a preparation signal when entering an ID assignment mode. Each slave wirelessly transmits Received Signal Strength Indicator (RSSI) of the preparation signal to the master when wirelessly receiving the preparation signal from the master or other slave during operation in a standby mode. The master wirelessly transmits an ID associated with the operation count to a slave having wirelessly transmitted a maximum RSSI among the RSSIs of the preparation signal, and increases the operation count by 1.

Abstract: An electric power supply system includes an alternating current electric power supply circuit that converts direct current electric power of a first direct current sweep unit including a battery string into alternating current electric power using a first inverter and outputs it, and an alternating current sweep unit that includes a U-phase battery string, a V-phase battery string, and a W-phase battery string that are Y-connected. Output densities of batteries of the battery string are higher than output densities of batteries of the alternating current sweep unit. Alternating current electric power is output from the alternating current sweep unit and the alternating current electric power supply circuit, and after a predetermined period elapses, the output of the alternating current electric power from the alternating current electric power supply circuit is stopped.

Abstract: In a power supply system, a control device is configured to adjust a state of charge of each of an alternating-current battery string and a direct-current battery string by power transfer between the alternating-current battery string and the direct-current battery string before performing requested energy management.

Abstract: A power supply system that outputs AC power to an object to which power is to be supplied includes: a first power supply circuit including a DC battery string and an inverter and configured to output first AC power; a second power supply circuit including an AC battery string and configured to output second AC power; and a control device. In the first mode, power is transferred between the object and the second power supply circuit. In the second mode, power is transferred between the object and each of the first and second power supply circuits. The control device starts supplying the second AC power to the object in the first mode, and when a power supply current becomes larger than a first threshold, supply the first and second AC power to the object in the second mode.

Abstract: An isolated communications apparatus applied to a transformer. The transformer includes N first rectifier units and a second rectifier unit, and the isolated communications apparatus includes N first control units, a second control unit, and a signal convergence unit. The first control units are connected to the first rectifier units in a one-to-one correspondence. Each first control unit is connected to the signal convergence unit, and the signal convergence unit and the second control unit are connected through an optical fiber. The signal convergence unit is configured to: receive first data packets from the N first control units, send the first data packets to the second control unit, receive at least one second data packet from the second control unit, determine a first control unit corresponding to each second data packet, and send each second data packet to a corresponding first control unit.

Abstract: Enhancing operation of powered tools is provided. Access permissions for tools and access devices are stored to in vehicle memory. Presence of a tool within proximity to the vehicle is detected. Presence of access devices configured to provide access to the vehicle are detected utilizing passive access functionality of the vehicle. Access to an auxiliary power source of the vehicle is allowed for powering the tool responsive to the access permissions granting access due to the presence of the access devices.

Abstract: Controlling a power converter circuit for a direct current (DC) power source is disclosed. The power converter may be operative to convert input power received from the DC power source to an output power and to perform maximum power point tracking of the power source. The power converter is adapted to provide the output power to a load that also performs maximum power point tracking.

Abstract: An energy blending device has a first input for alternating current, a second input for connection to a solar array, and an output, the energy blending device receiving energy from the first input, both inputs coupled to power an energy blending node. The device is in a configuration either with the solar array matching a voltage of the energy blending node, the blending node providing power through a DC-DC converter to a load interface device, and the solar array coupled through a DC-DC converter to the energy blending node, the energy blending node providing power to a load interface device. A microcontroller controls the DC-DC converter and a load interface device. The energy blending device has an energy storage system having a battery coupled either directly to the energy blending node or through a bidirectional energy storage interface to the energy blending node.

Abstract: A voltage converter powers a load. The voltage converter includes a first power converter and a second power converter. The first power converter produces an intermediate voltage and a first output current derived from an input voltage. The first power converter supplies the intermediate voltage to the second power converter. The second power converter produces a second output current based on the intermediate voltage received from the first power converter. An output node of the voltage converter outputs a sum of the first output current and the second output current to produce an output voltage.

Abstract: A battery pack is provided that can better manage peak current of in a converged portable radio. The battery pack comprises an internal Li-Ion cell stack characterized by a linear output voltage curve. A DC-DC converter converts the internal cell stack voltage to a desired DC-DC converter output voltage. The output voltage and current sourcing capability of the battery pack remain constant over the full cell discharge curve. The battery pack optimizes cell utilization, without the use of any internal microprocessor, thereby supporting the operation of simultaneous high peak current application features associated with LMR and LTE.

Abstract: The present disclosure relates to a day-night photovoltaic system. More specifically, power supplied to a solar panel from a DC power supply part is output as a final output power PV together with power produced by the solar panel during the daytime, and is output as the final output power together with an ultra-high frequency wavelength generated by the sun explosion and induced to the solar panel during the night time. This provides the effects of stably supplying the power not only during the daytime but also during the night time.

Abstract: A fuel-cell system at 540 VDC for powering an electrical load of a rotorcraft with a first fuel cell and a second fuel cell. Each fuel cell is configured identically and features a positive electrical node and a negative electrical node. Each fuel cell is configured to provide one half of the electrical load of the rotorcraft and one half of the voltage of the electrical load.

Abstract: Disclosed herein are methods, systems, and devices for supporting the transition to lithium-ion batteries and leveraging the value that lithium-ion batteries offer in double conversion uninterruptible power supply (UPS) applications. According to one embodiment, a UPS system includes an alternating current (AC) to direct current (DC) rectifier configured to be electrically coupled with an AC source, a DC to AC inverter configured to be electrically coupled with an AC load, a DC bus electrically coupled between the AC to DC rectifier and the DC to AC inverter. The UPS system also includes a diode electrically coupled between the DC bus and a first battery cell of a plurality of battery cells, and a by-pass relay having a first terminal electrically coupled with an anode of the diode and a second terminal electrically coupled with a cathode of the diode.

Abstract: An electric drive system is connected to power batteries and includes a bus, a three-level inverter circuit, a direct current (DC)-DC conversion circuit, and a controller. The bus includes a positive bus and a negative bus. The three-level inverter circuit includes a first bus capacitor and a second bus capacitor. The first bus capacitor is connected between the positive bus and a bus neutral point, and the second bus capacitor is connected between the negative bus and the bus neutral point. The DC-DC conversion circuit includes a first conversion circuit and a second conversion circuit, an input terminal of the first conversion circuit is connected in parallel to the first bus capacitor, and an input terminal of the second conversion circuit is connected in parallel to the second bus capacitor.

Abstract: Provided is a power conversion device capable of continuing the transmission of power even in the event of failure of a DC-to-DC converter cell. The power conversion device according to the present invention includes: a unit having a plurality of DC-to-DC converter cells; a short-circuit device that short-circuits a failed cell; and a control circuit that controls the plurality of DC-to-DC converter cells. The control circuit controls the voltage of a second cell terminal of a healthy cell included in a unit that includes the failed cell, based on a failed cell count m, so that the power of a first cell terminal and the power of the second cell terminal are matched.

Abstract: The invention is a method to optimize solar photovoltaic power plant repowering by making use of the smart predictive and preventive maintenance which detects failures in modules or in cells within modules, i.e., aerial inspections by infrared thermography and/or electroluminescence. In the method object of the invention, the detected failed modules are separated in different types of failures: A—irreversible; B—reversible and C—partly reusable. Repowering consists on substituting modules of type A for new, more powerful ones, and re-group them series-connected within the same strings (1). Modules with type B failures are repaired and installed back in their original place, and modules C are either re-grouped in series-strings, or substituted by new, more powerful modules, also series connected in strings (1).

Abstract: A vehicle control apparatus includes a controller that switches a vehicle between an HEV traveling mode and an EV traveling mode. When the output current of a DC-to-DC converter becomes equal to or higher than a threshold, the controller decreases the output current by decreasing the output voltage of the DC-to-DC converter through output regulation control. The controller makes switching between a normal setting in which the threshold for the output regulation control is set to a reference threshold and a boost setting in which the threshold is set to a boost threshold higher than the reference threshold. The controller prohibits the boost setting when a power margin for boosting becomes equal to or lower than a first power margin value in the HEV traveling mode and when the power margin for the boosting becomes equal to or lower than a second power margin value in the EV traveling mode.

Abstract: An integrated circuit includes a multiplexer circuit configured to provide an output signal on a conductive line, a programmable gain amplifier having a non-inverting input connected to the conductive line to receive the output signal from the multiplexer, a slew rate adjust circuit connected at a first node on the conductive line between the multiplexer circuit and the programmable gain amplifier, a first switch including a first terminal connected to the first node and a second terminal connected to the input of the programmable gain amplifier, and a low pass filter connected between the first and second terminals of the first switch.

Abstract: A rapid shutdown device and a photovoltaic system are provided. The photovoltaic system includes an inverter and multiple serially-connected photovoltaic elements. The rapid shutdown device includes a switching circuit, a control circuit, a communication circuit and an auxiliary power circuit. The switching circuit includes a first switch and a second switch. A first terminal of the first switch is electrically connected with the positive terminal of a first photovoltaic element. A second terminal of the first switch is electrically connected with the negative terminal of a second photovoltaic element. A first terminal of the second switch is electrically connected with the negative terminal of the first photovoltaic element. The communication circuit receives a command signal from the inverter and transmits it to the control circuit. The control circuit controls the first switch and the second switch to turn on or turn off according to the command signal.

Abstract: An inverter in a power generation system converts a direct current that is input from a direct-current-side device into an alternating current for power supply. The inverter includes a control apparatus and a communications apparatus. The control apparatus controls the inverter to convert the direct current that is input from the direct-current-side device into an alternating current for power supply. The communications apparatus is coupled to the control apparatus, and sends a networking information request signal used to request networking information to the direct-current-side device in the power generation system through a direct-current power line, where a frequency of the networking information request signal is within a first frequency band. The communications apparatus also receives the networking information from the direct-current-side device; and sends a control signal to the direct-current-side device, where a frequency of the control signal is within a second frequency band.

Abstract: A semiconductor switching arrangement contains at least two half-bridge modules that each have an AC voltage connection, a positive DC voltage busbar, a negative DC voltage busbar, and at least one AC voltage busbar. The AC voltage connections are electrically interconnected by the AC voltage busbar. The aim is to improve the current distribution to the half-bridge modules arranged electrically in parallel. To this end, at least in the region of the AC voltage connections, the positive DC voltage busbar and the negative DC voltage busbar extend over an area containing the AC voltage busbar. Two of the at least two half-bridge modules are arranged adjacently such that the AC voltage surfaces of the two of the at least two half-bridge modules are adjacently arranged in relation to each other. Ideally a converter can contain at least one such semiconductor switching arrangement.

Abstract: Provided is a power line communication device for use in an electric power generation system. The power line communication device is provided with: a positive input terminal connected to a positive pole of an electric generator; a negative input terminal connected to a negative pole of the electric generator; a positive output terminal connected to the downstream side of a power line for transmitting electric power generated by the electric generator; a negative output terminal connected to the upstream side of the power line; a current pulse generator which is connected between the negative input terminal and the positive output terminal and generates a current pulse in the power line; and a controllable unidirectional device which is connected between the positive input terminal and the positive output terminal and is capable of performing impedance control.

Abstract: An energy storage system has a battery device, a first terminal, a second terminal, a capacitor device and a DC/DC converter. The first and second terminals are respectively connected two electrodes of the battery device, and the two electrodes have opposite polarities. The capacitor device is electrically connected to the first and second terminals in parallel. The DC/DC converter is electrically connected between the first terminal and the capacitor device. The battery device composed of at least one secondary battery and the capacitor device composed of at least one capacitor are electrically connected to each other in parallel, and by combining with the DC/DC converter, configuring the relation between the equivalent series resistor of the capacitor device and the internal resistor of the battery device, and/or configuring the upper current limit of the rated current of range the DC/DC converter, the battery cycle life is increased.

Abstract: A single-phase hybrid multilevel inverter capable of producing a higher number of output voltage levels using fewer power switches and DC voltage sources compared to existing multilevel inverters. The levels are synthesized by switching the DC voltage sources in series/parallel combinations. An auxiliary circuit is introduced to double the number of levels by creating an intermediate step in between two levels. In addition, a zero level is introduced to overcome the inherent absence of this level in the original circuit. To improve the total harmonic distortion, a hybrid modulation technique is utilized. A 300 W, a thirteen level multilevel inverter (including the zero level) was designed and constructed. The circuit was tested with a no-load, resistive load and resistive-inductive load. The experimental results closely match simulated and mathematical analyses.

Abstract: A photovoltaic power system includes a DC/AC inverter circuit, N DC/DC converter circuits that are located at a previous stage of the DC/AC inverter circuit and that are respectively connected to photovoltaic strings, and a controller connected to the DC/AC inverter circuit and the N DC/DC converter circuits. The controller is configured to: perform MPPT control on n DC/DC converter circuits, and perform CPG control on (N?n) DC/DC converter circuits. In the two control manners, a fast and accurate power reserve or limit of a photovoltaic string inverter with any illumination intensity and ambient temperature can be implemented, and fluctuation of a DC bus voltage and AC output power of the photovoltaic string inverter can be eliminated. Control on a virtual synchronous generator of the photovoltaic string inverter is implemented, and a lifespan of the photovoltaic string inverter is prolonged, without a need to add an energy storage element.

Abstract: A DC/DC power converter comprises three or more capacitors connected in series between an output terminal and a ground terminal, the three or more capacitors being connected in series by means of two or more capacitor connection points, and an input voltage switching unit configured to connect an input terminal to one of a group of switching connection points, the group of switching connection points comprising the two or more capacitor connection points and the output terminal. With such a DC/DC power converter it is possible, for example, to convert a variable DC voltage at the input into a variable DC voltage at the output, wherein the voltage range of the output voltage is smaller than the voltage range of the input voltage.

Abstract: A bidirectional two-phase chopper circuit boosts a voltage of direct-current power converted by an AC/DC converter to output it to a high-voltage battery and steps down a voltage of direct-current power being supplied to a low-voltage load unit from the high-voltage battery. A connector is connected to a quick charger supplying direct-current power. A connector is connected to a superquick charger supplying direct-current power having a higher voltage than that of the quick charger.

Abstract: A distributed power supply system includes a plurality of power supply groups having at least one wind turbine generator; and a rectifier which is provided corresponding to each of the power supply groups, and configured to rectify AC power to DC power, so that the DC power rectified by the rectifier is collected to transmit electric power. A control device for the distributed power supply system comprises a grouping section configured to group the power supply groups into at least two groups; a phase command generation section configured to generate phase commands different from one another for each group to output to the power supply groups belonging to the respective groups, and generate the same phase command to output to the wind turbine generators belonging to the same group; and a transmission section configured to transmit the same phase command to the wind turbine generators.

Abstract: Current source rectifier (CSR) systems and methods for a power source including three phase lines are disclosed. One illustrative CSR system includes a rectifier operable to receive an AC input voltage and provide a DC output voltage and a controller communicatively coupled to the rectifier. The rectifier comprises first, second, and third phase legs including a plurality of switches with each switch coupled to an associated phase line of the three phase lines. The controller is operable to (i) control operation of the plurality of switches in accordance with a first switching sequence when measured input voltages on at least two phase lines of the three phase lines are outside of the predetermined voltage range and (ii) control operation of the plurality of switches in accordance with a second switching sequence when the measured input voltages on the at least two phase lines are within the predetermined voltage range.

Abstract: A multilevel inverter includes an inner DC source group circuit that generates a plurality of voltage levels, and an outer DC source group circuit that generates a substantially sinusoidal output voltage. The substantially sinusoidal output voltage is generated using, at least in part, the plurality of voltage levels generated by the inner DC source group circuit. An H-bridge circuit supplies the substantially sinusoidal output voltage at alternating polarities to a load.

Abstract: A fully integrated triboelectric energy harvesting system can comprise a triboelectric generator, an electrical energy harvesting system, and a power amalgamation circuit. The triboelectric generator can comprise triboelectric materials, conductive contacts, and a mechanical motion transformer.

Abstract: Disclosed examples relate to a power conversion system configured to provide a power output from an arrangement of direct current (DC) power sources. One example power conversion system includes multiple power sources PV(n), n=1 to x, connected in a series. For each power source PV(n) for n=1 to x?1, the power conversion system includes an intermediate bidirectional voltage converter VC(n) connected to a first terminal of the power source PV(n), a first terminal of power source PV(x), and a second terminal of power source PV(1). Each intermediate bidirectional voltage converter VC(n) includes a first switch operable in a pulsed mode to boost a power output by power source PV(n) and a second switch operable in a pulsed mode to reduce a power output by power source PV(n). The power conversion system also includes a balancer VC(x) connected to the first terminal of PV(x) and to a load.

Abstract: A controllable system for shutting down the connection between photovoltaic panels is provided. A connector with the function described in the present invention is arranged on a current transmission line between two photovoltaic panels adjacent to each other. A signal processing system, a power supply system, a control circuit, and an electronic switch element are arranged in the connector. The signal generator inputs a signal into the current transmission line, and the signal processing system separates the signal. A part of the signal continues to be transmitted along the current transmission line to other connectors on the current transmission line, and the other part of the signal is divided into a control signal and a power supply signal. The control signal passes through the control circuit and controls the electronic switch element to be turned on or off.

Abstract: A single-phase hybrid multilevel inverter capable of producing a higher number of output voltage levels using fewer power switches and DC voltage sources compared to existing multilevel inverters. The levels are synthesized by switching the DC voltage sources in series/parallel combinations. An auxiliary circuit is introduced to double the number of levels by creating an intermediate step in between two levels. In addition, a zero level is introduced to overcome the inherent absence of this level in the original circuit. To improve the total harmonic distortion, a hybrid modulation technique is utilized. A 300 W, a thirteen level multilevel inverter (including the zero level) was designed and constructed. The circuit was tested with a no-load, resistive load and resistive-inductive load. The experimental results closely match simulated and mathematical analyses.

Abstract: In large PV power plants, grounding of individual PV modules may lead to problems. The present invention overcomes such problems. The basis for the invention is a PV power plant comprising one or more PV generators, each comprising a PV string and an inverter with a DC input and an AC output. The PV string comprises at least one PV module and is electrically connected to the DC input of the inverter. The inverter comprises means for controlling the DC potential at the DC input depending on the DC potential at the AC output. The AC outputs of the inverters are coupled in parallel. The novel feature of the invention is that the PV power plant further comprises an offset voltage source, which controls the DC potential at the AC outputs. Thereby, the DC potential at the DC input will be indirectly controlled, and it is thus possible to ensure that the potentials with respect to ground at the terminals of the PV modules are all non-negative or all non-positive without grounding the PV modules.