Abstract: An uninterruptible power supply (UPS) system includes a first port configured to be coupled to an AC power source and a second port configured to be coupled to a load. The system also includes a UPS circuit including a first converter circuit coupled to the first port, a second converter circuit coupled to the second port and a DC bus coupling the first converter circuit to the second converter circuit and configured to be coupled to an auxiliary power source and a third converter circuit coupled to the second port and configured to receive power from a variably available power source. The system further includes a control circuit operatively associated with the UPS circuit and the third converter circuit and configured to cooperatively control the UPS circuit and the third converter circuit to selectively transfer power to the load from the AC power source and the variably available power source and from the variably available power source to the AC power source.

Abstract: An uninterruptible power supply (UPS) system includes a first port configured to be coupled to an AC power source and a second port configured to be coupled to a load. The system also includes a UPS circuit including a first converter circuit coupled to the first port, a second converter circuit coupled to the second port and a DC bus coupling the first converter circuit to the second converter circuit and configured to be coupled to an auxiliary power source and a third converter circuit coupled to the second port and configured to receive power from a variably available power source. The system further includes a control circuit operatively associated with the UPS circuit and the third converter circuit and configured to cooperatively control the UPS circuit and the third converter circuit to selectively transfer power to the load from the AC power source and the variably available power source and from the variably available power source to the AC power source.

Abstract: An uninterruptible power supply (UPS) system includes a first port configured to be coupled to an AC power source and a second port configured to be coupled to a load. The system also includes a UPS circuit including a first converter circuit coupled to the first port, a second converter circuit coupled to the second port and a DC bus coupling the first converter circuit to the second converter circuit and configured to be coupled to an auxiliary power source and a third converter circuit coupled to the second port and configured to receive power from a variably available power source. The system further includes a control circuit operatively associated with the UPS circuit and the third converter circuit and configured to cooperatively control the UPS circuit and the third converter circuit to selectively transfer power to the load from the AC power source and the variably available power source and from the variably available power source to the AC power source.

Abstract: An uninterruptible power supply (UPS) system includes a first port configured to be coupled to an AC power source and a second port configured to be coupled to a load. The system also includes a UPS circuit including a first converter circuit coupled to the first port, a second converter circuit coupled to the second port and a DC bus coupling the first converter circuit to the second converter circuit and configured to be coupled to an auxiliary power source and a third converter circuit coupled to the second port and configured to receive power from a variably available power source. The system further includes a control circuit operatively associated with the UPS circuit and the third converter circuit and configured to cooperatively control the UPS circuit and the third converter circuit to selectively transfer power to the load from the AC power source and the variably available power source and from the variably available power source to the AC power source.

Abstract: A fault in a DC power source, such as a battery string or a string of photovoltaic cells, is identified by detecting a change in an AC component of a residual current of the DC power source. In some embodiments, the DC power source is coupled to at least one DC bus and the methods further include generating an AC voltage on the at least one DC bus. For example, the DC power source may be coupled to a modulated DC bus of an uninterruptible power supply (UPS) system comprising an inverter having an input coupled to the DC bus. The inverter may be configured to generate an AC output voltage and the AC component has a frequency that is a harmonic of a fundamental frequency of the AC output voltage, such as a third harmonic of the fundamental frequency of the AC output voltage.

Abstract: A fault in a DC power source, such as a battery string or a string of photovoltaic cells, is identified by detecting a change in an AC component of a residual current of the DC power source. In some embodiments, the DC power source is coupled to at least one DC bus and he methods further include generating an AC voltage on the at least one DC bus. For example, the DC power source may be coupled to a modulated DC bus of an uninterruptible power supply (UPS) system comprising an inverter having an input coupled to the DC bus. The inverter may be configured to generate an AC output voltage and the AC component has a frequency that is a harmonic of a fundamental frequency of the AC output voltage, such as a third harmonic of the fundamental frequency of the AC output voltage.

Abstract: An uninterruptible power supply (UPS) system includes a first port configured to be coupled to an AC power source and a second port configured to be coupled to a load. The system also includes a UPS circuit including a first converter circuit coupled to the first port, a second converter circuit coupled to the second port and a DC bus coupling the first converter circuit to the second converter circuit and configured to be coupled to an auxiliary power source and a third converter circuit coupled to the second port and configured to receive power from a variably available power source. A control circuit is configured to cooperatively control the UPS circuit and the third converter circuit.

Abstract: A value of an AC reference waveform is obtained and converted to a d-q reference frame value. A phase estimate is generated responsive to the d-q reference frame value. An AC output of the power supply apparatus is controlled responsive to an output current of the power supply apparatus and the phase estimate. For example, an output current value may be obtained and converted to a d-q reference frame current value responsive to the phase estimate, and the AC output may be controlled responsive to the d-q reference frame current value.

Abstract: A value of an AC reference waveform is obtained and converted to a d-q reference frame value. A phase estimate is generated responsive to the d-q reference frame value. An AC output of the power supply apparatus is controlled responsive to an output current of the power supply apparatus and the phase estimate. For example, an output current value may be obtained and converted to a d-q reference frame current value responsive to the phase estimate, and the AC output may be controlled responsive to the d-q reference frame current value.

Abstract: A power conversion apparatus, such as a UPS, includes a first waveform reference signal generator circuit operative to generate a first waveform reference signal responsive to an AC bus, and a second waveform reference signal generator circuit operative to generate a second waveform reference signal, e.g., a more consistently sinusoidal signal produced by another source. The apparatus further includes a control circuit that selectively generates a third waveform reference signal from the first and second waveform reference signals, and a power converter circuit (e.g., a rectifier and/or inverter) coupled to the AC bus and operative to transfer power to and/or from the AC bus responsive to the third waveform reference signal. In particular, the control circuit may be operative to weightedly combine the first and second waveform reference signals to generate the third waveform reference signal.

Abstract: A power supply apparatus, such as an uninterruptible power supply, includes an AC input configured to be coupled to an AC power source and an AC output. The apparatus also includes an AC/DC converter circuit, e.g., a boost rectifier circuit, with an input coupled to the AC input. The apparatus further includes a DC/AC converter circuit, e.g., an inverter circuit, configured to be coupled between an output of the AC/DC converter circuit and the AC output. A bypass circuit is operative to establish a coupling between the AC input to the AC output in a first (e.g., bypassed) state and to interrupt the coupling in a second (e.g., “on line”) state. The AC/DC converter circuit is operative to control current at the AC input when the bypass circuit is in the first state. For example, the AC/DC converter circuit may be operative to control current at the AC input to correct a power factor at the AC input port when bypassed, such that the AC/DC converter circuit may act as a line conditioner in the bypassed state.

Abstract: A power supply apparatus, such as an uninterruptible power supply, includes an AC input configured to be coupled to an AC power source and an AC output. The apparatus also includes an AC/DC converter circuit, e.g., a boost rectifier circuit, with an input coupled to the AC input. The apparatus further includes a DC/AC converter circuit, e.g., an inverter circuit, configured to be coupled between an output of the AC/DC converter circuit and the AC output. A bypass circuit is operative to establish a coupling between the AC input to the AC output in a first (e.g., bypassed) state and to interrupt the coupling in a second (e.g., “on line”) state. The AC/DC converter circuit is operative to control current at the AC input when the bypass circuit is in the first state.