A method comprises, at a power balancing circuit for three-phase AC power: feeding three power phases to respective loads; measuring power drain on the three power phases by the respective loads; based on measuring, detecting an unbalanced power drain across the three power phases due to a relatively light power drain on one or more lightly loaded power phases and a relatively high power drain on one or more heavily loaded power phases; computing an amount of power to be drained from the one or more lightly loaded power phases and to be fed to the one or more heavily loaded power phases to balance the power drain across the three power phases; and transferring the amount of power from the one or more lightly loaded power phases to the one or more heavily loaded power phases to balance the power drain across the three power phases.

A method comprises, at a power balancing circuit for three-phase AC power: feeding three power phases to respective loads; measuring power drain on the three power phases by the respective loads; based on measuring, detecting an unbalanced power drain across the three power phases due to a relatively light power drain on one or more lightly loaded power phases and a relatively high power drain on one or more heavily loaded power phases; computing an amount of power to be drained from the one or more lightly loaded power phases and to be fed to the one or more heavily loaded power phases to balance the power drain across the three power phases; and transferring the amount of power from the one or more lightly loaded power phases to the one or more heavily loaded power phases to balance the power drain across the three power phases.

A system and method of a multi-channel, multi-mode electric vehicle (EV) AC to DC charger has power channels, each power channel contains an AC/DC converter and corresponding DC/DC regulator. Each channel is configured to supply DC power to a channel-connected EV. The charger also has a controllable bridging switch, connected in parallel between the power channels and disposed before or after the DC/DC regulators, and provides an intermediary path between the power channels. It also contains controllable series switches, after the DC/DC regulators to provide a break in a power channel output path. A controller controls the AC/DC converters, DC/DC regulators, bridging and series switches. The charger is multi-mode capable, enabling (a) charging an EV, (b) directing power from one channel's connected end device to another channel's connected end device, (c) injecting real or reactive power back to an AC power source, (d) active AC filtering, and (d) phase balancing.

A housing and/or installation frameworks for a modular multi-level energy system includes a set of similar cabinets configured for orthogonal (e.g., vertical and horizontal) alignment of the modules. The cabinets are configured so modules of a particular phase are oriented along an axis parallel to a reference plane. Modules of the same level of the multi-level arrangement but of different phases are mounted in each cabinet, arranged such that a module for each phase is a defined distance from the reference plane. The cabinets are arranged equidistant and orthogonal to the reference plane, minimizing distance for connections between modules of the same phase across multiple cabinets, and facilitating convenient addition or removal of levels. The framework also facilitates data and reference signal connections between local control devices of the modules, and between the local control devices and a master control device for the system.

Disclosed is a method for operating a three-phase inverter on a three-phase load. The three-phase inverter has a direct voltage intermediate circuit, at least one three-phase bridge circuit, and at least one control unit for controlling the bridge circuit. In the at least one bridge circuit, at least two power switches per phase are provided, which are connected in series parallel to the direct voltage intermediate circuit. Depending on predefined target voltage values of the three phases of the inverter, the power switches of each individual phase are actuated via the control unit such that a three-phase alternating voltage is generated on the three-phase load via switching operations of the power switches. Very good dynamic control behaviour can be achieved despite cost-effective dimensioning of the IGBT power switches of the three-phase bridge circuit.

A transport refrigeration unit is configured to provide conditioned air to a refrigerated cargo space and includes: an AC battery pack configured to store and convert DC electricity to AC electricity and provide the AC electricity to power the transport refrigeration unit as three phase electrical power, the AC battery pack includes: a first phase group including a first plurality of battery modules, the first phase group being configured to provide the AC electricity in a first phase; a second phase group including a second plurality of battery modules, the second phase group being configured to provide the AC electricity in a second phase; and a third phase group including a third plurality of battery modules, the third phase group being configured to provide the AC electricity in a third phase. The first phase, the second phase, and the third phase are each shaped as a stair step sine wave.

A method for stabilising a power grid by at least one backup battery of a network element for use in a communications network. The method comprises determining (402) future power consumption of the network element, determining (404) a required backup energy level of said at least one backup battery based on said determined future power consumption for operation of the network element for a defined period and providing (406) a fraction of capacity of said at least one backup battery to stabilise a power grid.

A device, for a low-voltage circuit, includes a four-pole input connection for a three-phase AC circuit having a neutral conductor, including a first, second and third input phase pole, and an input neutral conductor pole; a two-pole output connection; a first connection between the between the input and output neutral conductor pole; a first, second and third electronic switch unit to carry out opening and closing of an electrical connection; a voltage sensor for determining the voltage level of the input phase poles; and a controller connected to the voltage sensor and the electronic switch units, designed such that, depending on the voltage level of the input phase poles, the first, second or third input phase pole is connected to the first output phase pole via the respective electronic switch unit, the first output phase pole being connected to the respective input phase pole having the highest voltage level.

A device, for a low-voltage circuit, includes a four-pole input connection for a three-phase AC circuit having a neutral conductor, including a first, second and third input phase pole, and an input neutral conductor pole; a two-pole output connection; a first connection between the between the input and output neutral conductor pole; a first, second and third electronic switch unit to carry out opening and closing of an electrical connection; a voltage sensor for determining the voltage level of the input phase poles; and a controller connected to the voltage sensor and the electronic switch units, designed such that, depending on the voltage level of the input phase poles, the first, second or third input phase pole is connected to the first output phase pole via the respective electronic switch unit, the first output phase pole being connected to the respective input phase pole having the highest voltage level.

A power conversion device includes a power conversion circuit and a power conversion control circuit. The power conversion control circuit is configured to calculate a positive-phase sequence current command signal based on a positive-phase sequence voltage of the three-phase AC output voltage and a positive-phase sequence current of the three-phase AC output current, calculate a negative-phase sequence current command signal based on the first axis negative-phase sequence current command value, the second axis negative-phase sequence current command value, the first axis negative-phase sequence current value, and the second axis negative-phase sequence current value, and generate the switching control signal based on the positive-phase sequence current command signal and the negative-phase sequence current command signal.