Abstract: An adaptive electrical power distribution panel receives electrical power from at least an alternative power source other than a utility electric grid, and selectively outputs power to a plurality of branch circuits, appliances, or devices. An internal or remote controller monitors conditions. In response to the monitored conditions, the controller algorithmically divides the plurality of branch circuits, appliances, or devices into a first group to receive power from the alternative power source and a second group to not receive power from the alternative power source, and breaks electrical connections between the alternative power source and the second group. The monitored conditions may include operating parameters the grid; an instantaneous or average individual current flow; and a charge state of storage batteries. The division into groups may also be in response to stored information, such as a priority of, or history of current usage by, each branch circuit, appliance, or device.

Abstract: A DC to AC converter system for solar energy installations reduces cost by eliminating low-frequency power transformers. One DC input polarity is selectively switched to an output terminal when the instantaneous AC output from a second output terminal is desired to be of the opposite polarity, while the other DC input polarity is used to form an approximation to a segment of a sine wave of the desired polarity at the second output terminal. Switching transistors in H-bridge circuits, with a reservoir capacitor across each H-bridge circuit, may be equivalently configured into a first and second bank of series-connected transistors connected across the DC source, with the reservoir capacitors connected in a nested fashion. The DC to AC converter approximates a sine wave by summing integer multiples of a voltage step size at different times, or may output a desired voltage value by jittering between higher and lower voltage values.

Abstract: A single- or multi-phase DC to AC converter system suited for solar energy installations achieves cost reduction by eliminating low-frequency power transformers. One DC input polarity is selectively switched to an output terminal when the instantaneous AC output from a second output terminal is desired to be of the opposite polarity, while the other DC input polarity is used to form an approximation to a segment of a sine wave of the desired polarity at the second output terminal. The approximation for each phase is built in a multilevel fashion by outputting, at different times, voltage levels that differ by an integer multiple of a predetermined voltage step size, to the respective live AC output terminal through an associated low pass filter. A common-mode AC signal is thereby created on the balanced DC input lines at a frequency which is the AC output frequency times the number of phases, and which is useful for detecting ground faults in the DC circuit.

Abstract: An electrical measurement device for monitoring the current and power taken by a plurality of electrical loads that may be powered by a selected one of multiple AC power sources comprises sampling the voltage of said sources and the current taken by said loads at a integral number of samples per cycle at sample times determined by an independent processor clock. The integral number of samples of each measured parameter for each cycle are processed to determine a complex number for each parameter representative of the amplitude and the phase relative to the independent processor clock. The phase drift of the substantially constant source voltages may be determined as a measure of frequency of the sources, and may be used to cancel drift of the current measurement to enable averaging.

Abstract: An electrical installation having a first source of power, such as the utility grid, and a second source of power from an electronic DC-to-AC converter, comprises a smart load center for selecting the source of power independently for each of a number of branch circuits protected by circuit breakers to be the first source or the second source. The smart load center comprises a software-controlled processor for operating the transfer relays that select the first or second source of power for each branch circuit. In the event that a current overload on a branch circuit connected to the DC-to-AC converter causes it to trip before the branch circuit breaker clears the overload, all circuits are transferred to the first power source to trip the fault breaker and then the microprocessor enters a restart sequence to verify that the fault is cleared or else to take other action.

Abstract: A method, circuit and system arrangement is described for providing rapid de-energization for safety reasons of conductors having a DC power source at both ends. The invention is particularly envisaged for use in solar energy systems in which a battery is charged by solar power from a photovoltaic array, the invention comprising controlling the array to interrupt charge current flow and then isolating the battery from the conductors to be de-energized in a fail-safe manner.

Abstract: A fast-operating AC fault current limiter, to limit the fault current let through to downstream equipment during short circuit or low-impedance faults, comprises a series inductor to limit current rise time, a current sensor to sense the instantaneous current, a series AC semiconductor switch to interrupt current flow when it exceeds the maximum desired fault current, and a shunt AC semiconductor switch to catch inductor flyback voltage when the series semiconductor switch is opened. Each of the series and the shunt AC switches comprises two back-to-back MOSFETs. Inventive control of timing of the individual MOSFETs obviates the need for exact simultaneous timing of opening the series switch and closing the shunt switch, which is otherwise required to avoid short circuits.

Abstract: A DC to AC converter is configured to convert DC power from a floating DC power source to AC power having a desired voltage and waveform. A plurality of capacitors is charged to discrete voltages from the DC power. A switching network selectively connects the capacitors in series to an AC output node. For selected capacitors, either the associated voltage or the inverse of the associated voltage is summed together (non-selected capacitors contribute zero volts to the sum). The sum voltage is output to the AC output node at two values, and the voltage is jittered between these two values at a high frequency in order to approximate intermediate values. The two values jittered between, and the values and timing of the intermediate values, are controlled to construct a desired waveform, such as an approximation to a sine wave.

Abstract: A smart load center panel (10) accepts two hot legs from each of two power sources, and selectively connects each of a plurality of breakers to one of the two power sources under processor control. A dielectric chassis (12) provides structural support and electrical isolation for a plurality of individual circuit boards (28), each including a pair of breaker stabs (26) and a relay (24) operative to selectively connect each breaker stab (26) to a different power source. A bus bar assembly (20) comprises two bus bars for the hot legs of each of two power sources, and insulates the bus bars from each other and from inadvertent contact. A master printed circuit board (40) comprises slits (43, 45) defining the individual circuit board (28) except at the edges. After mounting and soldering, the edges are cut away, yielding a plurality of individual circuit boards (28). Neutral and ground bus bars (46, 52) are mounted to the side of the panel housing (12), behind a flange of a front opening.

Abstract: In an electrical distribution system for a facility served by two power sources, ground currents on neutral conductors are avoided by utilizing a common neutral conductor in distributing power from both power sources to one or more transfer switches. In at least one single cable or conduit run, either between transfer switches or between both power sources and a transfer switch, line conductors carry power from each power source to the transfer switch(es), and a common neutral conductor carries return current for both power sources. The neutral terminals of both power sources are connected together (in part via the common neutral conductor in the single cable or conduit run), and the common neutral is grounded at only one place.

Abstract: A DC to AC converter is described in which DC power presented as a set of relatively floating DC power sources of differing DC voltage values is converted to a desired AC power waveform by combining the DC voltage values with sequential sets of associated ternary-valued multiplicative weights of +1, ?1, or 0, and summing the weighted voltage values, so as to produce voltage points on the desired waveform at appropriate time instants.

Abstract: A safety shut-down system for a solar energy installation includes a DC to AC inverter converting DC power from a photovoltaic solar array to AC power and generating remote control signals to enable or disable the flow of DC power from each individual photovoltaic panel or string of panels to a photovoltaic output circuit. One or more manual switches, one of which may be at a service entrance for electrical power to the installation, are operative to cause the DC to AC inverter to disable all DC power from the photovoltaic solar array; this also occurs when the DC to AC inverter is shut off. A storage battery may selectively receive DC power from one or more photovoltaic panels or strings of panels for charging. The DC to AC inverter may generate AC power from the battery when the photovoltaic solar array is disabled.

Abstract: A communications system is described providing the ability to intelligently deliver electrical power from a first power source or from a second power source to a branch circuit in a facility, such as a home. Communications between a Smart Load Center (SLC) controller and the appliances is provided via a combination of signals sent over the electrical wiring and signals sent over the air. In particular, the signals over the electrical wiring serve to identify to which branch circuit the appliance is connected. The signals over the air support the communications between the appliances and the SLC controller, and may be part of a larger Internet-of-Things ecosystem dedicated to facilities automation services.

Abstract: A transformerless DC to AC inverter providing an AC output at a power line voltage and at a power line frequency suitable for driving AC loads or appliances and having DC bias measurement circuitry for continuously assessing the magnitude of any DC bias component on the AC output, such as due to fault conditions or non-linear loads, and operative to eliminate or reduce any unwanted DC bias component from the AC output.

Abstract: Sharing of load current in desired ratios between multiple electrical voltage sources is achieved without coupling between the sources by controlling a selection switch to select each voltage source for a proportion of the time at a high rate, the switching rate components being prevented from being seen by either the load or the sources through use of low-pass filters.

Abstract: A remote-controlled photovoltaic string combiner is described that selects strings to be combined to a first photovoltaic output circuit or to a second photovoltaic output for the purpose of either controlling the charging of a battery connected to the first photovoltaic output circuit or for diverting current to a diversion load such as a grid-tie inverter. Strings are selected by energizing relays from one or other inverter such that when neither inverter is operating, all strings are deselected and both photovoltaic output circuits are de-energized.

Abstract: A number of DC-AC microinverters driven by separate photovoltaic sub-arrays are physically combined to use common components such as a common, common-mode choke. Each microinverter is controlled by a common switching controller to produce a portion of the desired output such that ripple on the combined output is minimized, and each microinverter produces a common mode signal on its associated sub-array equal in frequency to the desired AC output frequency.

Abstract: An improved residential electrical energy system is described based on the use of a smart load center or power distribution panel configured to select the use of utility power or power derived from storage batteries independently for each of a number of load circuits based on availability of utility power and battery charge state information.

Abstract: A method and circuit arrangement is described for start-up and shut-down of high power DC to AC inverters which limits inrush current for capacitor charging, reduces input and output relay contact stress and discharges internal capacitors upon shut down. A preferred inrush limiting component has a higher resistance when hot than when cold, such as an incandescent filament lamp.

Abstract: Transformerless bimodal inverters provide grid-tie outputs for back-feeding solar-originated power from a battery to a utility power grid in a grid-tied mode, simultaneously or alternatively with providing a constant-voltage AC output for powering AC appliances or loads directly in a standalone mode. The inverters continue to operate in the standalone mode without interruption should the grid-tied mode cease, e.g., due to anti-islanding during a grid outage or other fault condition not affecting the standalone mode. Conversely, the inverters continue to operate in the grid-tied mode should the standalone mode trip out, e.g., due to a current overload or other condition not affecting the grid-tied mode.