Abstract: A computer-implemented method for estimating a rotor speed of an alternating current (AC) machine is provided. The method includes determining a stator flux signal based on signals of voltage and current inputs to the AC machine, and determining a rotor flux signal of the AC machine based on the determined stator flux signal. The method includes determining an electrical angle signal based on the determined rotor flux signal, and deriving an electrical frequency signal from the determined electrical angle signal. Subsequently, the method includes sampling the derived electrical frequency signal at a predetermined sampling rate, and storing a predetermined number of sample values. The method further includes evaluating a median value of the predetermined set of electrical frequency sample values, determining a slip frequency value of the AC machine, and determining the rotor speed of the AC machine by subtracting the slip frequency value from the electrical frequency median value.

Abstract: An apparatus and method for controlling the delivery of power from a DC source to an AC grid includes an inverter configured to deliver power from the unipolar input source to the AC grid and an inverter controller. The inverter includes an input converter, an active filter, and an output converter. The inverter controller includes an input converter controller, an active filter controller and an output converter controller. The input converter controller is configured to control a current delivered by the input converter to a galvanically isolated unipolar bus of the inverter. The output converter is configured to control the output converter to deliver power to the AC grid. Additionally, the active filter controller is configured to control the active filter to supply substantially all the power that is deliver by the output controller to the AC grid at a grid frequency.

Abstract: A system and method includes a circuit for protecting a photovoltaic string. A bypass switch connects in parallel to the photovoltaic string and a hot spot protection switch connects in series with the photovoltaic string. A first control signal controls opening and closing of the bypass switch and a second control signal controls opening and closing of the hot spot protection switch. Upon detection of a hot spot condition the first control signal closes the bypass switch and after the bypass switch is closed the second control signal opens the hot spot protection switch.

Abstract: An inverter for converting an input direct current (DC) waveform from a DC source to an output alternating current (AC) waveform for delivery to an AC grid includes an input converter, an output converter, and an active filter, each of which is electrically coupled to a bus. The bus may be a DC bus or an AC bus. The input converter is configured to convert the input DC waveform to a DC or AC bus waveform. The output converter is configured to convert the bus waveform to the output AC waveform at a grid frequency. The active filter is configured to reduce a double-frequency ripple power of the bus waveform by supplying power to and absorbing power from the power bus.

Abstract: An apparatus and method for controlling the delivery of power from a DC source to an AC grid includes an inverter configured to deliver power from the unipolar input source to the AC grid and an inverter controller. The inverter includes an input converter, an active filter, and an output converter. The inverter controller includes an input converter controller, an active filter controller and an output converter controller. The input converter controller is configured to control a current delivered by the input converter to a galvanically isolated unipolar bus of the inverter. The output converter is configured to control the output converter to deliver power to the AC grid. Additionally, the active filter controller is configured to control the active filter to supply substantially all the power that is deliver by the output controller to the AC grid at a grid frequency.

Abstract: An apparatus and method for controlling the delivery of power from a DC source to an AC grid includes an inverter configured to deliver power from the unipolar input source to the AC grid and an inverter controller. The inverter includes an input converter, an active filter, and an output converter. The inverter controller includes an input converter controller, an active filter controller and an output converter controller. The input converter controller is configured to control a current delivered by the input converter to a galvanically isolated unipolar bus of the inverter. The output converter is configured to control the output converter to deliver power to the AC grid. Additionally, the active filter controller is configured to control the active filter to supply substantially all the power that is deliver by the output controller to the AC grid at a grid frequency.

Abstract: An inverter for converting an input direct current (DC) waveform from a DC source to an output alternating current (AC) waveform for delivery to an AC grid includes an input converter, an output converter, and an active filter, each of which is electrically coupled to a bus. The bus may be a DC bus or an AC bus. The input converter is configured to convert the input DC waveform to a DC or AC bus waveform. The output converter is configured to convert the bus waveform to the output AC waveform at a grid frequency. The active filter is configured to reduce a double-frequency ripple power of the bus waveform by supplying power to and absorbing power from the power bus.

Abstract: Microinverters useable in association with photovoltaic modules are described. A three phase-microinverter receives direct current output generated by a microsystems-enabled photovoltaic cell and converts such direct current output into three-phase alternating current out. The three-phase microinverter is interleaved with other three-phase-microinverters, wherein such microinverters are integrated in a photovoltaic module with the microsystems-enabled photovoltaic cell.

Abstract: A system includes a circuit having a plurality of electronic function blocks interconnected in series, a power source unit coupled to the circuit, for supplying power to the plurality of electronic function blocks, and a control unit coupled to each of the plurality of the electronic function blocks and to the power source unit. The control unit is configured to monitor activity levels of each of the electronic function blocks, and adjusts the activity level of each of the plurality of electronic function blocks. The control unit determines a voltage level suitable for the corresponding adjusted activity level, and adjusts the power supplied to each of the plurality of electronic function blocks in order to achieve the corresponding determined voltage level at each of the plurality of electronic function blocks.

Abstract: An inverter for converting an input direct current (DC) waveform from a DC source to an output alternating current (AC) waveform for delivery to an AC grid includes an input converter, an output converter, and an active filter, each of which is electrically coupled to a bus. The bus may be a DC bus or an AC bus. The input converter is configured to convert the input DC waveform to a DC or AC bus waveform. The output converter is configured to convert the bus waveform to the output AC waveform at a grid frequency. The active filter is configured to reduce a double-frequency ripple power of the bus waveform by supplying power to and absorbing power from the power bus.

Abstract: A system and method includes a circuit for protecting a photovoltaic string. A bypass switch connects in parallel to the photovoltaic string and a hot spot protection switch connects in series with the photovoltaic string. A first control signal controls opening and closing of the bypass switch and a second control signal controls opening and closing of the hot spot protection switch. Upon detection of a hot spot condition the first control signal closes the bypass switch and after the bypass switch is closed the second control signal opens the hot spot protection switch.

Abstract: A method for minimizing power losses in an alternating current (AC) machine is provided. The method includes determining a first rotor flux signal based on signals of voltage and current inputs to the AC machine, and extracting a ripple component of the rotor flux signal. The method further includes determining a power compensating value that corresponds to a stored energy value of the AC machine, determining a second rotor flux signal that serves to minimize power losses, and providing the second rotor flux signal to a power inverting unit that adjust accordingly the voltage and current input signals provided to the AC machine.

Abstract: A method and apparatus for controlling an inverter includes operating the inverter in a one of a normal run mode or a pulse mode depending on one or more criteria. When operating in the pulse mode, the inverter generates a sinusoidal output pulse waveform including a plurality of pulses having a determined pulse width. The pulse width is less than a half-wave period of a full-cycle sinusoidal waveform and may be determined as function of, for example, the output power of the inverter, a grid voltage, and/or other criteria.

Abstract: An apparatus and method for controlling the delivery of power from a DC source to an AC grid includes an inverter configured to deliver power from the unipolar input source to the AC grid and an inverter controller. The inverter includes an input converter, an active filter, and an output converter. The inverter controller includes an input converter controller, an active filter controller and an output converter controller. The input converter controller is configured to control a current delivered by the input converter to a galvanically isolated unipolar bus of the inverter. The output converter is configured to control the output converter to deliver power to the AC grid. Additionally, the active filter controller is configured to control the active filter to supply substantially all the power that is deliver by the output controller to the AC grid at a grid frequency.

Abstract: A computer-implemented method for estimating a rotor speed of an alternating current (AC) machine is provided. The method includes determining a stator flux signal based on signals of voltage and current inputs to the AC machine, and determining a rotor flux signal of the AC machine based on the determined stator flux signal. The method includes determining an electrical angle signal based on the determined rotor flux signal, and deriving an electrical frequency signal from the determined electrical angle signal. Subsequently, the method includes sampling the derived electrical frequency signal at a predetermined sampling rate, and storing a predetermined number of sample values. The method further includes evaluating a median value of the predetermined set of electrical frequency sample values, determining a slip frequency value of the AC machine, and determining the rotor speed of the AC machine by subtracting the slip frequency value from the electrical frequency median value.

Abstract: A solar power system is provided for maximizing solar power conversion. The solar power system includes n power units connected in series and n-1 DC-DC converting units, and each of the n-1 DC-DC converting units is coupled to at least one of n solar power units. Each of the n-1 DC-DC converting units is configured to control the correspondingly connected solar power units to operate at a target current generation. The solar power system further includes a controlling unit coupled to the n-1 DC-DC converting units. The controlling unit monitors and compares the n currents generated by the n solar power units. Based on the current comparison, the controlling unit determines a series current and controls the n solar power units so that each of the generated photovoltaic currents is substantially equal to the determined series current.

Abstract: An apparatus and method for controlling the delivery of power from a DC source to an AC grid includes an inverter configured to deliver power from the unipolar input source to the AC grid and an inverter controller. The inverter includes an input converter, an active filter, and an output converter. The inverter controller includes an input converter controller, an active filter controller and an output converter controller. The input converter controller is configured to control a current delivered by the input converter to a galvanically isolated unipolar bus of the inverter. The output converter is configured to control the output converter to deliver power to the AC grid. Additionally, the active filter controller is configured to control the active filter to supply substantially all the power that is deliver by the output controller to the AC grid at a grid frequency.

Abstract: A method and apparatus for controlling an inverter includes operating the inverter in a one of a normal run mode or a pulse mode depending on one or more criteria. When operating in the pulse mode, the inverter generates a sinusoidal output pulse waveform including a plurality of pulses having a determined pulse width. The pulse width is less than a half-wave period of a full-cycle sinusoidal waveform and may be determined as function of, for example, the output power of the inverter, a grid voltage, and/or other criteria.

Abstract: A method is provided for preventing islanding of a power source connected to an electric AC grid via an interface. The method senses an output voltage waveform of the interface, controls an output current waveform of the interface to track a reference current waveform having a mathematical relationship with the sensed output voltage waveform, and discontinues the output current waveform when the output voltage waveform is sensed to be outside a predetermined waveform range.

Abstract: An inverter for converting an input direct current (DC) waveform from a DC source to an output alternating current (AC) waveform for delivery to an AC grid includes an input converter, an output converter, and an active filter, each of which is electrically coupled to a bus. The bus may be a DC bus or an AC bus. The input converter is configured to convert the input DC waveform to a DC or AC bus waveform. The output converter is configured to convert the bus waveform to the output AC waveform at a grid frequency. The active filter is configured to reduce a double-frequency ripple power of the bus waveform by supplying power to and absorbing power from the power bus.