A three-phase UPS control method and apparatus, and a three-phase uninterruptible power supply resolve a problem that after a zero wire is lost, when a current control method is applied to a three-phase UPS using a three-level topology, a 0-axis direct-current modulated wave results in that positive and negative buses are unbalanced. The method includes: determining that a zero wire of a three-phase uninterruptible power supply is lost; using an alternating current whose frequency is a harmonic frequency of mains as a 0-axis reference current; and generating a 0-axis modulated wave according to a difference between the 0-axis reference current and a 0-axis sampling current, to control a rectifier in the three-phase uninterruptible power supply to convert a received alternating current to a direct current.

A power supply apparatus includes converters connected in parallel to a three-phase alternating-current power supply, input current detectors that detect current flowing through the respective three phases of the three-phase alternating-current power supply, and load current detectors that detect load current of the converters. Each of the converters includes AC-DC converters inputs of connected to two of the three phases. The AC-DC converters are connected in parallel to each other using a common output. The AC-DC converters that are driven maintain balance of output current. A controller determines whether switching between a driven state and a stopped state of the respective AC-DC converters is performed based on detection results from the load current detectors and switches between the driven state and the stopped state of the respective multiple AC-DC converters based on detection results by the input current detectors.

A method for operating a charging device for a battery of a motor vehicle. The charging device converts electric power obtained from a motor vehicle-external, three-phase energy system supplying other consumers in an infrastructure unit, in particular a house, by a converter device into an electric current that is suitable for charging the battery, and supplies electric energy of the battery by the converter device into the energy system. The charging device receives in an operating phase phase-resolved power data, which is fed to the energy system and measured by a measuring device, and determines phase-specified target power while using phase-related power data outputs for each phase. The target power that is determined for each phase is retrieved from each phase.

The present invention provides an improved method of identifying which electrical conductor is supplying a signaling-point that is located on that conductor, in the electrical grid. The present invention makes the identification by measuring currents flowing into and out of a common connection-point, such as a power bus, and analyzing concurrent portions of these currents to determine whether they are ingress-current or egress-current over the analysis-intervals, and by a subsequent intra-bus and inter-bus analysis of the ingress/egress patterns. This is in contrast to prior art systems that rely on the measurement of signal strength, an approach that does not take best advantage of information in the signal because it fails to consider polarity of instantaneous voltages, reflective of the direction of current flow, or the intra-bus and inter-bus ingress/egress current-relationships.

A method for operating an unbalanced load manager for a three-phase induction motor or heater, includes receiving, by a load manager, values representative of current flow sensed by current sensors and voltages sensed by voltage taps corresponding to phases of a three-phase power system providing power to the motor or heater. The method includes detecting, by the load manager, a transition from positive or negative to zero current, to measure a phase shift between line-to-line and current. The method further includes synchronizing, by the load manager, firing from line-to-line signal to line-to-neutral signal of phases of the three-phase power system, using the measured phase shift between line-to-line and current.

A converter arrangement has a converter which can be switched between an AC network and a DC voltage circuit and which has power semiconductor valves that extend between AC voltage connections and DC voltage connections. Each power semiconductor valve has a series connection of bipolar submodules that in turn include power semiconductor devices. The arrangement further includes a star point reactor which is arranged on the AC voltage side of the converter and has impedance coils that are connected to a grounded neutral point. In order to better balance the voltages in the DC circuit, the impedance coils have a common coil core.

Systems and methods are provided for a three-phase compensation system, whereby an electric circuit is configured to be connected with three input phases of a power source and to supply three respective output phases, said electric circuit further configured to compensate for one or two malfunctioning input phases of said three input phases by supplying current from a functioning input phase of said three input phases to replace a malfunctioning input phase.

This patent discloses an active impedance-injection module for dynamic line balancing of a high-voltage (HV) transmission line. The impedance-injection module comprises a plurality of transformers each having a primary winding in series with a HV transmission line. Each transformer also has secondary windings, each connected to an individual electronic converter. The plurality of secondary windings are electrically isolated from the associated primary winding and extract power from the HV transmission line for operation of the converters and other circuits connected to the secondary windings. The active impedance-injection module is enabled to generate a controlled impedance, inductive or capacitive, to be impressed on the HV transmission line. A plurality of active impedance-injection modules spatially distributed on a HV transmission line are enabled to inject a controlled cumulative impedance on a HV transmission line while limiting the capacity of individual converters to that achievable with practical electronic components.

A multi-phase DC-to-DC buck converter for receiving an input voltage and delivering an output voltage to a load by splitting the load current between a plurality of DC-to-DC buck converter cells. The converter includes a plurality of current sense circuits for sensing current in a respective converter cell, each of the current sense circuits configured to generate a respective current sense signal, an averaging circuit for receiving each of the respective current sense signals and generating an average signal, a plurality of imbalance detector circuits for comparing a respective current sense signal with the average signal and generating a respective current imbalance signal, and a plurality of ON time generators for activating a converter cell for a predetermined time interval and altering the predetermined time interval in accordance with a time integral of a respective current imbalance signal.

According to one aspect, embodiments of the invention provide a PDU comprising an input configured to receive 3-phase power from a power source, a plurality of phase lines, each phase line configured to carry one phase of the 3-phase power, at least one outlet, at least one switch circuit configured to selectively couple the at least one outlet to the plurality of phase lines, a data connection, and a controller, wherein the controller is configured to monitor current from the plurality of phase lines to the at least one outlet, receive, via the data connection, phase loading information related to 3-phase power of at least one external device coupled to the power source, and operate the at least one switch circuit to selectively couple the at least one outlet to at least one of the plurality of phase lines based on the current and the received phase loading information.