Abstract: An object is to provide a duplex power supply for auxiliary machines. A power supply device includes a switching section that is connected to a direct-current link between a generator-side inverter and a grid-side inverter via an auxiliary machine power inverter for converting direct-current power supplied from the direct-current link into alternating-current power to form a first path, that is connected somewhere between a power-converting section and a utility grid to form a second path, and that is connected to auxiliary machines to form a third path, and the switching section switches between connection of the third path to the first path and connection of the third path to the second path.

Abstract: An uninterruptible power supply device connects a battery for power-outage backup to the output side of an AC/DC converter. An input monitoring circuit monitors alternating current input of the AC/DC converter and outputs an alternating current input monitor signal E1. An output monitoring circuit monitors the direct current output of the AC/DC converter and outputs a direct current output monitor signal E2. A reactivation circuit outputs a reset signal to and reactivates protection circuits of the AC/DC converter when the state that alternating current input is provided and direct current output is not provided is determined based on the alternating current input monitor signal E1 and the direct current output monitor signal E2 upon turn-on of alternating current power.

Abstract: Distributed generation systems incorporate a distribution network and typically a number of distributed generators. It is possible that power islands may be created in substations incorporating a generator when that substation and generator is isolated from the distribution network by a circuit breaker. A problem arises when the power island is re-connected to the distribution network when the phase of electrical power supply in the previous power island is not synchronized with the power supply on the distribution network. Identifying such an out of phase nature is achieved utilizing application of test reactances, both capacitative and inductive, across the whole distribution network such that such test reactances are substantially unbalanced within a particular substation and in particular a distribution path for a generator so that there is a test reactance load imbalance which will identify out of phase operation and therefore control activation of the circuit breaker.

Abstract: An energy transfer circuit for connecting a load to multiple energy sources that can have different voltages. The energy transfer circuit connects the load and at least two energy sources, and has a control unit. The energy transfer circuit can transfer energy from at least one energy source to the load in response to the load's power demand; transfer energy from the load to at least one energy source in response to the load's charging current, and transfer energy between the energy sources. The energy transfer circuit also includes a first capacitor in parallel with the primary source and the load; a second capacitor in parallel with the secondary source, an inductor, a first switch between the inductor and the first capacitor, a second switch between the inductor and the second capacitor. The control unit opens and closes the first and second switches in response to the load and sources.

Abstract: A power supply selection/detection circuit to select one main power supply from a plurality of external power supplies includes a resistance element with one end connected to an external power supply and another end connected to the main power supply, a first voltage detector to receive a voltage of the external power supply and detect a voltage of the external power supply, a second voltage detector to detect a voltage between the ends of the resistance element, and a switch connected between the external power supply and a ground to short-circuit or open-circuit between the external power supply and the ground according to an output of the second voltage detector. The resistance element and the first voltage detector are disposed for each of the plurality of external power supplies, and the second voltage detector and the switch are disposed for at least one of the plurality of external power supplies.

Abstract: A system and method that offers the provision too rapidly and safely connect electrical generation sources, including inverters used by solar collecting panels, or wind turbines, and backup hydrocarbon fueled generators or any other supplemental power sources including storage batteries, fuel cells and future electric automobiles. Thus enabling the feeding of power to all circuits in the home or small business, not just isolated circuits in a structure. The system is compliant with electric codes, requires no costly rewiring inside the structure or in the electrical circuit panel and can be accomplished entirely from the outside of the home or small business adjacent to the electric service meter for the home or small business structure.

Abstract: A variable frequency transformer including: a first parallel circuit including at least two of the rotary transformers arranged in parallel and having an isolating circuit breaker connected to a rotor winding of each of the rotary transformers, and a separate synchronizing circuit breaker connected to a stator winding in each of the rotary transformers in the first parallel circuit; a first main transformer having a first winding connectable to a first power grid and a secondary winding connectable to the isolating circuit breaker in the first parallel circuit; a second main transformer having a first winding connectable to a second power grid and a secondary winding connectable to each of the synchronizing circuit breakers in the first parallel circuit, and a control system operatively connected to each of the synchronizing circuit breakers, the isolating circuit breakers and the drive motors for each of the rotary transformers.

Abstract: A load driving circuit that generates a desired voltage waveform to drive a load includes a target voltage waveform output section that outputs a target voltage waveform to be applied to the load. Power supply sections generate electrical power with voltage values different from each other. Negative feedback control sections between the power supply sections and the load supply electrical power from the corresponding power supply sections to the load and execute negative feedback control of a value of a voltage applied to the load for matching the voltage value and the target voltage waveform. A power supply connection section selects one of the power supply sections based on the value of the voltage applied to the load or the voltage value of the target voltage waveform and connects the selected power supply section to the load and disconnects the rest of the power supply sections from the load.

Abstract: A method is disclosed for producing electrical current by a fuel cell device, which inputs electrical current to an electrical network. A fuel cell device can be arranged to be parallel connected to the electrical network. A phase reference signal can be utilized in the inputting of the electrical current, and electrical current inputted to electrical network can be current controlled by a power transformer having a power stage. The fuel cell device can be switched off from the electrical network when a malfunction occurs in the electrical network. The fuel cell device can be changed, using the phase reference signal, to the switched off operation mode for performing voltage controlled operation of the power transformer. A controllable load can be used for maintaining a power stability between the voltage controlled power transformer and other parts of the fuel cell device.

Abstract: A selectable backup power supply device for providing power to a real time clock (RTC) and a memory unit is disclosed. The device includes a backup battery, a first power outputting unit and a second power outputting unit, wherein the backup battery outputs a backup voltage, the first power outputting unit is connected to the backup battery and the RTC for receiving the backup voltage and outputting a first supply voltage to the RTC, and the second power outputting unit is connected to the backup battery and the memory unit, for receiving the backup voltage and, in accordance with a selection signal, outputting a second supply voltage to the memory unit or stopping the output of the second supply voltage.

Abstract: Featured are methods for regulating the AC frequency of the electrical power be supplied on an electrical distribution system or grid. Such a method includes electrically coupling an energy storage sub-system to the electrical distribution network, where the energy storage sub-system includes one or more flywheel energy storage systems. Also featured as devices, systems and apparatuses embodying such methodologies or for use in implementing such methodologies of the present invention.

Abstract: A vehicle power supply apparatus includes a battery that is the main power storage device, a power feed line through which power is supplied to an inverter that drives a motor generator, a boost converter provided between the battery and power feed line to convert voltage, batteries that are a plurality of subpower storage devices provided parallel to each other, and a boost converter provided between the plurality of subpower storage devices and power feed line to convert voltage. The boost converter is selectively connected to any one of the plurality of subpower storage devices to convert voltage.

Abstract: An underwater substation pod (USP) adapted to collect and process the electrical outputs of an array of offshore power generating devices includes a voltage boosting transformer for combining and transmitting with increased efficiency an amplified version of the collected electrical outputs to an on shore facility. Combining the outputs and transmitting at a higher voltage reduces transmission losses and the number of cables required to transmit the electrical outputs. The USP is mounted on the seabed but operated at atmospheric pressure to accommodate standard components. The pod may be designed to include remotely controlled operation and to have a long service life since few, if any, moving parts are used. Also, the equipment may be designed to have a high degree of redundancy to provide greater reliability.

Abstract: A fuel cell power management system and an anti-islanding method using the power management system. The power management system includes a fuel cell to generate direct current (DC) power, a power conditioning system (PCS) to generate alternating current (AC) power from the DC power generated by the fuel cell, a power grid that is connected to the PCS, a detector to detect a change in the AC power flowing from an output line of the PCS, and a controller to control the connection between the PCS and the power grid, according to the result of the detection.

Abstract: A transfer switch assembly is disclosed that includes a power switch device with a number engagement landings and a printed circuit board defining an opening bordered by a number of tabs. The tabs engage the landings as the switch device extends through the openings, and can be fastened together.

Abstract: A power distribution system is provided for supplying power to a variable speed motor for rotating a shaft. The system comprises a variable speed prime mover adapted to generate an A/C output having a variable frequency corresponding to the speed of the prime mover, a power switch, a power distribution bus connected to the A/C output of the prime mover and connected, via the switch, to the motor such that the motor's speed is varied relative to the frequency of the A/C output, and a variable frequency drive operatively connected to the A/C output of the prime mover via the bus and effective to provide an alternate A/C output to the motor after the motor is disconnected from the bus. The switch is adapted to disconnect the motor from the bus when the prime mover's speed is equal to or within a predetermined range of the prime mover's speed limit.

Abstract: A pulse generation circuit for outputting a pulse with a predetermined waveform to an output terminal in response to a start signal includes a circuit adapted to generate a plurality of signals {Di|i denotes an integer in a predetermined range}, which has predetermined amounts of time differences from the start signal, based on the start signal, a plurality of power supplies {Ej|j denotes an integer} adopted to supply electric energy of a predetermined electric quantity, and a switching circuit adapted to sequentially switch the power supplies {Ej} in a predetermined order in accordance with logical function values of at least a part of the signals {Di} to connect the power supplies {Ej} to the output terminal.

Abstract: A circuit arrangement and method for redundantly supplying current to a downstream load are provided. The circuit arrangement includes a first current path including a first switch element to which a first voltage is applied on the input side, a second current path including a second switch element to which a second input voltage is applied on the input side, a first control device which is connected to the first current path and used to control the first switch element, a second control device which is connected to the second current path and used to control the second switch element, and a common output terminal of the first and second current paths, from which a load supply voltage is emitted.

Abstract: The system allows the generation and distribution of energy on board a motor vehicle provided with a propulsion unit, a tank for fuel at least one distribution network or line for electric energy, electrical energy generation devices connected to the at least one distribution network or line, and a plurality of selectively activatable electrical utilizer devices or apparatus connected or connectable to the at least one distribution network or line. The electrical energy generator devices includes (at least) a microcombustor electricity generator matrix or battery connected to the fuel tank, and a supervision and control unit associated with this generator matrix or battery and coupled to the distribution network or line and arranged to control the operation of the generator matrix or battery in a predetermined manner as a function of the electrical power required or consumed by the network or line.

Abstract: A device which can dynamically configure an array of power supply cells such as photovoltaic (PV) solar cells to provide power to a load device based on the power requirements of the load device. By selectively configuring the array of power supply cells according to one of a number of available series/parallel connection schemes, the supplied power can be more closely tailored by a controller to the requirements of the load device.

Abstract: A power allocating apparatus has a plurality of power supply modules coupled to a plurality of loads via a plurality of power lines, respectively. The power allocating apparatus includes a first switch element and a control device. The first switch element has a first connecting terminal and a second connecting terminal coupled to an output terminal of a power supply module with a relatively high power conversion rate and an output terminal of a power supply module with a second power conversion rate, respectively, and selectively allocates a power generated by the power supply module with the relatively high power conversion rate to a predetermined number of loadings simultaneously according to on or off states of the first switch element. The control device is coupled to the first switch element to control the first switch element to enter an on state or an off state.

Abstract: A universal system used to monitor external conditions, particularly including environmental conditions, to preemptively activate secondary power sources and isolate electric loads from a main power source such as an electric utility's power grid for the purpose of protecting the load from dangerous power conditions brought about by the external condition. The system includes a universal control module capable of communicating with a variety of external stimuli sensors and automatic transfer switches that switch a load's power source from one source to another upon activation, which results in the isolation of the load from the main (or another) power source.

Abstract: A voltage switching circuit selects a voltage from among a plurality of input voltages in response to a selection signal and outputs the selected voltage from an output terminal. The voltage switching circuit includes a first PMOS transistor that outputs a power supply voltage for operating a logic circuit of an output terminal. A second PMOS transistor outputs a first voltage higher than the power supply voltage to the output terminal. A third PMOS transistor outputs a second voltage lower than the power supply voltage to the output terminal. A well potential control section controls well voltages of the first and third transistors to be the power supply voltage where the power supply voltage and the second voltage are output to the output terminal, and controls the well voltages of the first and third transistors to be the first voltage where the first voltage is output to the output terminal.

Abstract: A load module determines that a load of an electronic device is operating at a power level below a predetermined power threshold. The electronic device is configured to receive power simultaneously from two or more redundant power supplies. Each redundant power supply configured to receive input power from one or more power sources and configured to provide regulated output power to the load of the electronic device. A disconnection module disconnects at least one of the two or more redundant power supplies from the one or more power sources in response to the load module determining that the load of the electronic device is operating at a power level below the predetermined power threshold.

Abstract: Apparatuses and methods to firewall distributed energy sources. In one aspect, an apparatus includes: a first connector configured to interface with a distributed energy source; a second connector configured to interface with a connection point of an electric power system; at least one switch coupled between the first connector and the second connector; at least one sensor coupled with the switch; and a controller coupled with the at least one switch, the controller to use the at least one switch to selectively connect or disconnect an electric path between the first connector and the second connector based on signals from the at least one sensor.

Abstract: Disclosed herein are systems and methods for converting data samples representing alternating electric currents. The data samples may be obtained by sampling a first alternating electric current having a first frequency at a sampling frequency, sampling a second alternating electric current having a second frequency at the sampling frequency, and converting the data samples using a conversion algorithm to compensate for any discrepancy caused by the difference between the first frequency and the second frequency. The corrected data samples may be utilized to determine various characteristics of the alternating electric current, such as voltage magnitude, voltage phase angle, current magnitude, current phase angle, and other related attributes. In one application, the systems and methods disclosed herein may be utilized in connection with an intelligent electronic device used to couple a first electrical system, such as a power generator, to a second electrical system, such as a utility intertie.

Abstract: A capacitive load driving circuit that drives an electrical load having a capacitive component, includes: a first power supply generating a first voltage; a second power supply generating a second voltage different from the first voltage; a plurality of charge storage elements charged by the first power supply; a first connection unit that connects the plurality of charge storage elements to the electrical load by switching connections among the charge storage elements; and a second connection unit that connects the second power supply to the electrical load.

Abstract: The present invention discloses a multi-input power-switching circuit, which comprises: more than one power input terminal, more than one detection/evaluation circuit, and a switching/controlling unit. A switch is arranged in the path via which the input power is received by the power input terminal and then transferred to the power conversion unit. Each detection/evaluation circuit receives a partial voltage signal from one input power and generates a detection signal according to the partial voltage signal. The switching/controlling unit receives the detection signals from the detection/evaluation circuits, determines which power input terminal has a higher voltage level according to the detection signals, and generates a turn-on signal to turn on the switch connected with the power input terminal having a higher voltage level. Thereby, the power conversion unit can acquire a higher voltage input power and provide a stable driving power for a load.

Abstract: A power management system includes a power management unit (PMU) and a current sensor. The PMU is operable for controlling a first power source and a second power source. The second power source is operable for being charged by the first power source via a charging path. The current sensor has a first terminal coupled to the first power source and the second power source and has a second terminal coupled to the second power source via the charging path. The current sensor is operable for sensing a first current flowing from the first power source through the current sensor and for sensing a second current flowing from the second power source through the current sensor.

Abstract: Power over Ethernet (PoE) communication systems provide power and data communications over the same communications link, where a power source device (PSE) provides DC power (for example, 48 volts DC) to a powered device (PD). The DC power is transmitted simultaneously over the same communications medium with the high speed data from one node to the other node. The PSE typically includes a controller that controls the DC power provided to the PD at the second node of the communications link. The PSE controller measures the voltage, current, and temperature of the outgoing and incoming DC supply lines to characterize the power requirements of the PD. In addition, the PSE controller may detect and validate a compatible PD, determine a power classification signature for the validated PD, supply power to the PD, monitor the power, and reduce or remove the power from the PD when the power is no longer requested or required. The PSE controller also monitors for a Maintain Power Signature (MPS).

Abstract: A system and method for pre-detection in a power over Ethernet (PoE) system. A power sourcing equipment (PSE) is designed to measure a port voltage upon application of a small current source. A microcontroller controls the current source based on a comparison of the measured port voltage to a threshold voltage.

Abstract: Circuits and methods of providing power to an electric load are disclosed. The method includes the steps of, for example, generating power via at least first and second parallel power supplies, in response to the first power supply exhibiting an over-voltage, disabling a reverse current threshold on the second power supply, turning off the first power supply when the over-voltage exceeds a threshold value, and continuing to generate power via the second power supply.

Abstract: A threshold detection circuit includes, in one embodiment, a comparator having a first input connection for receiving a backup voltage from a backup power source, a second input connection for receiving a primary voltage from a primary power source, and an output connection for providing an output voltage; a first resistor and a first capacitor that are coupled in series between the first input connection and the output connection; and a second resistor that is coupled between the first input connection and the output connection, and that is coupled in parallel to the series of first resistor and the first capacitor.

Abstract: An energy harvesting system and method having improved efficiency. A primary energy harvesting device is used to generate a first electrical output signal. The first electrical output signal is applied to a first switching circuit. A secondary energy harvesting device is used to generate a second electrical output signal that is used to power a second switching circuit. The second switching circuit generates the switching drive signal for the first switching circuit, which in turn generates a final output signal. By using a second energy harvesting circuit operating in connection with a different structure, and a secondary switching circuit, less power from the signal generated by the primary energy harvesting device is needed to power the first switching circuit. This results in a greater percentage of the output power of the first signal being usable by an external device.

Abstract: A universal power distribution system is provided for routing electrical circuits within a building structure to comprehensively provide electrical power to the building in ceiling configurations, wall-mounted configurations, raised floor configurations and in office furniture configurations. The system components for all of these configurations have common plug connectors that are engagable with each other so as to be readily usable in a wide variety of applications. The system is readily adaptable to form virtually any conventional circuit configuration found within conventional hard-wired systems yet is formed simply through the routing of the cables through the building cavities and interconnection is accomplished merely by plugging components together rather than through labor-intensive manual wiring.

Abstract: A method includes operating a microsource in a grid mode in which the microsource is connected to a utility grid. The microsource is located in a microgrid and is configured to deliver a power P1 at a frequency ?1. During operation in the grid mode ?1 is a first frequency and P1 is a first power. The first frequency is an operating frequency of the utility grid. The microsource is transferred from the grid mode to an island mode, causing a frequency change such that ?1 changes to a second frequency and a power change such that P1 changes to a second power. The frequency change occurs at a first rate with respect to the power change while ?1 is less than a slope switch frequency. The frequency change occurs at a second rate with respect to the power change while ?1 is greater than the slope switch frequency.

Abstract: A system and method use magnetic field sensing to detect underground objects for strike avoidance. The system detects magnetic field components for both passive distortions in the magnetic field indicative of a ferromagnetic object and active magnetic fields that are impressed on an object by a signal generator. A detection module has a magnetic sensor assembly that detects the magnetic field components. The magnetic field component data is transferred through a multiplexer to an analog/digital converter to a processor. Pitch angle data from a pitch sensor and roll angle data from a roll sensor also may be transferred to the processor. The data is processed by the processor to determine the orientation of the detection module with respect to the object. The detection module may be installed in an underground boring tool or a trenching assembly.

Abstract: A method and circuit to output adaptive drive voltages within information handling systems is disclosed. According to one aspect of the disclosure, a method of outputting power within an information handling system can include sensing a load current of a power output stage operable to employ more than one drive voltage level. The method can also include comparing the load current to a threshold current setting, and selecting a first output drive voltage from a plurality of input drive voltages in response to comparing the load current to the threshold current setting. The method can also include coupling the first output drive voltage to the power output stage.

Abstract: A system and method for preventing over voltages in a power system coupled to an electric machine are disclosed. Briefly described, one embodiment is a method comprising detecting an operating voltage on a high voltage direct current (HVDC) bus, determining if at least one component of the power system is operational, communicating a signal to a power converter of the power system when the detected operating voltage is greater than a threshold voltage and when the component is not operational, and shorting together a plurality of terminals of the electric machine.

Abstract: A method for determining/dimensioning measures for restoring an electrical power system, which experiences or is heading for a voltage instability, to a steady-state condition, wherein there is no immediate risk of instability. An actual voltage/phase angle in the electrical power system is determined. The power unbalance within at least one sub-area in the electrical power system is determined. Suitable power-balancing measures are determined. The extent of the respective measures is determined. The power-balancing measures are carried out. Also, a device for carrying out the method.

Abstract: An electrical circuit and method for switching an input voltage onto a load by way of an AC control voltage is provided. A voltage magnitude reduction circuit is configured to be driven by the AC control voltage. A rectifier circuit is operably coupled with the voltage magnitude reduction circuit. Also, a voltage limiter circuit is operably coupled with the rectifier circuit, and an energy storage circuit is operably coupled with the voltage limiter circuit. The voltage magnitude reduction circuit, the rectifier circuit, the energy storage circuit and the voltage limiter circuit cooperatively generate a switch control voltage. An electronic switching unit is then configured to switch the input voltage across the load when the switch control voltage is active. In one embodiment, the input voltage is a DC voltage generated by an AC-to-DC voltage converter circuit configured to convert an AC supply voltage to the DC voltage.

Abstract: A power backup system includes a temporary power supply system and a power source switch unit. The power backup system is connected to at least one regular power supply system. In the event that output power of the regular power supply system is abnormal the power source switch unit is connected to the temporary power supply system and output of the regular power supply system. When the regular power supply system is in normal operation it is selected to provide power to drive loads. In the event of power interruption, unstable voltage or abnormal operating condition of the regular power supply system an action to switch power supply system takes places to select the temporary power supply system to maintain power supply and keep the loads to function for a selected time period.

Abstract: Novel system for supplying power from multiple power sources to a powered device has first and second input power supplies for respectively providing power from first and second power sources. An input selector circuit is responsive to the first and second input power supplies for producing an input power supply signal provided to a power regulator, such as a DC-DC converter, for generating a regulated output power supply signal. The power regulator includes a first transistor device controlled to support conversion of the input power supply signal into the output power supply signal if the input power supply signal is provided by the first input power supply, and a second transistor device controlled to support conversion of the input power supply signal into the output power supply signal if the input power supply signal is provided by the second input power supply.

Abstract: The grid interconnection device connected to the bank where alternating-current power is transmitted and to the power supply device provided to a customer includes: a detector detecting start of the alternating-current power transmission based on a state of the alternating-current power; a receiver receiving a grid interconnection start instruction for starting grid interconnection between the bank and the power supply device; and a grid interconnection controller controlling the bank and the power supply device to be interconnected or separated, in which the grid interconnection controller starts grid interconnection between the bank and the power supply device upon receipt of the grid interconnection start instruction in a state where the start of the alternating-current power transmission is detected.

Abstract: An underwater substation pod (USP) adapted to collect and process the electrical outputs of an array of offshore power generating devices includes a voltage boosting transformer for combining and transmitting with increased efficiency an amplified version of the collected electrical outputs to an on shore facility. Combining the outputs and transmitting at a higher voltage reduces transmission losses and the number of cables required to transmit the electrical outputs. The USP is mounted on the seabed but operated at atmospheric pressure to accommodate standard components. The pod may be designed to include remotely controlled operation and to have a long service life since few, if any, moving parts are used. Also, the equipment may be designed to have a high degree of redundancy to provide greater reliability.

Abstract: Power supply devices for vehicle electrical systems in particular, including two voltage systems, i.e., vehicle electrical systems, each having its own generator. The first generator and the battery belong to the same voltage system, and the second generator belongs to the second voltage system. If the two voltage systems were decoupled, the second generator would not have the excitation current required for starting, so means are consequently provided here to connect the second generator to a charge storage device after actuation of the ignition switch, thereby generating an excitation current; this charge storage device may also be the battery of the first voltage system and the connection is kept conductive until the second generator starts and is generating an output voltage.

Abstract: A power generation and control system is easily installed in a consumer household, a business, or an end-user establishment for generating power and preventing power from flowing to a power grid from a consumer circuit during a power outage A communications transceiver is adapted to transmit a permission signal for allowing power generation only after the control system has been installed. The control system can be adapted to replace an existing circuit breaker in a household circuit breaker box and prevents power from traveling from consumer power generators to the grid during a power outage. In the same manner that end-users can add appliances to existing circuits, end-users can easily add additional power generation devices without hiring a professional electrician and without worrying about causing harm to utility workman during power outages.

Abstract: A method and apparatus for detecting the presence of a specified voltage source and automatically switching off a second voltage source regardless of voltage source potential of the two voltage sources are disclosed. The present invention uses pinch-off of a JFET, controlled by an inverter, to control a backup power supply based on the availability of the main supply.

Abstract: A method of controlling an electric power source apparatus, which comprises supplying electric power to an electronic device on which a secondary battery is mounted from a power source apparatus having a fuel cell and an auxiliary power source. Electric power is supplied intermittently to a charging terminal of the electronic device by means of a switch for controlling conduction and interruption of an output terminal of the power source apparatus.

Abstract: Control modes for operating multiple power sources include energy storage systems and applicable to large systems such as locomotives. Selectable operating modes are provided for different locomotive speed ranges and work loads. A common DC bus electrical architecture is used so that prime power sources need not be synchronized. Multiple-engine locomotives have the engine systems that may be electrically connected in parallel or in series or in combinations of parallel and series to a DC bus.