Abstract: Systems and methods are provided for controlling an uninterruptible power supply (UPS) to transition between three- or higher-level operation and two-level operation in a neutral-point-clamped (NPC) inverter. In an example, a UPS system includes an NPC inverter and a controller. The NPC inverter may supply power to a load. The controller may control the inverter to operate in a three-level mode or higher when the load is substantially balanced and to operate in a two-level mode when the load is substantially unbalanced.

Abstract: Systems and methods are provided for controlling an uninterruptible power supply (UPS) to transition between three- or higher-level operation and two-level operation in a neutral-point-clamped (NPC) inverter. In an example, a UPS system includes an NPC inverter and a controller. The NPC inverter may supply power to a load. The controller may control the inverter to operate in a three-level mode or higher when the load is substantially balanced and to operate in a two-level mode when the load is substantially unbalanced.

Abstract: Systems and methods for balancing current from an AC source. The method includes determining a difference between a DC voltage output by a rectifier in an uninterruptible power supply (UPS) to a DC reference voltage. The method also includes determining an error between the DC voltage and the DC reference voltage based at least in part on the difference. After determining the error, the method includes filtering a second order harmonic from the error thereby generating a filtered error. The method may then include determining one or more switching signals for one or more switching components in the rectifier based at least in part on the filtered error and sending the switching signals to the rectifier.

Abstract: A method and system for managing a dual rectifier uninterruptable power supply, comprising activating each of said rectifiers to provide an output DC voltage, monitoring a level of operation of the uninterruptable power supply and deactivating a selected one of said dual rectifiers when a level of operation of said two activate rectifiers is less than a first predetermined level of operation.

Abstract: A method and system for managing a dual rectifier uninterruptable power supply, comprising activating each of said rectifiers to provide an output DC voltage, monitoring a level of operation of the uninterruptable power supply and deactivating a selected one of said dual rectifiers when a level of operation of said two activate rectifiers is less than a first predetermined level of operation.

Abstract: An apparatus having a rectifier topology for use on a three-phase electrical system is disclosed. The apparatus includes an input filter at each phase, a rectifier set at each phase in power communication with and downstream of each respective input filter, and a separate and independent booster section at each phase in power communication with and downstream of each respective rectifier set. Each booster section comprises two switches, thereby providing a six-switch three-level discontinuous conduction mode (DCM) boost rectifier.

Abstract: A control system for an uninterruptible power supply (UPS) for servicing a load is disclosed. The UPS includes a first feed path and a second feed path, where the first feed path is operable in parallel with the second feed path. The first feed path is engagable via a first switch to deliver a bypass current to the load. The second feed path includes a rectifier, an inverter responsive to a control signal and in electrical communication with the rectifier, and an output transformer in electrical communication with the inverter. The second feed path is engagable via a second switch to deliver an inverter current to the load. The control system is configured for facilitating magnetization of the transformer via a back-feed from the first feed path in response to the load being fed by the first feed path, the rectifier being off, and the inverter being off.

Abstract: A control system for an uninterruptible power supply (UPS) for servicing a load is disclosed. The UPS includes a first feed path and a second feed path, where the first feed path is operable in parallel with the second feed path. The first feed path is engagable via a first switch to deliver a bypass current to the load. The second feed path includes a rectifier, an inverter responsive to a control signal and in electrical communication with the rectifier, and an output transformer in electrical communication with the inverter. The second feed path is engagable via a second switch to deliver an inverter current to the load. The control system is configured for facilitating magnetization of the transformer via a back-feed from the first feed path in response to the load being fed by the first feed path, the rectifier being off, and the inverter being off.

Abstract: An apparatus having a rectifier topology for use on a three-phase electrical system is disclosed. The apparatus includes an input filter at each phase, a rectifier set at each phase in power communication with and downstream of each respective input filter, and a separate and independent booster section at each phase in power communication with and downstream of each respective rectifier set. Each booster section comprises two switches, thereby providing a six-switch three-level discontinuous conduction mode (DCM) boost rectifier.