An uninterruptible power supply (UPS) is provided that includes a split direct current (DC) link having a first capacitor coupled between a positive DC link terminal and a first node, and a second capacitor coupled between the first node and a negative DC link terminal. The UPS also includes a rectifier coupled to an input of the split DC link and a controller coupled to the rectifier. The rectifier includes first, second, and third legs, wherein each leg is configured to convert a first alternating current (AC) voltage received from an AC source into a DC voltage to be provided to the split DC link, and a fourth leg configured to balance DC link voltages of the first and second capacitors. The controller is configured to maintain functionality of the rectifier during at least one of a partial utility power outage, a full utility outage, and a failure of at least one of the first, second, third, and fourth legs.

An Uninterruptible Power Supply (UPS) system, the UPS system comprising an input configured to receive input AC power having an input voltage level and an input frequency, an output configured to provide output AC power to a load, the output power having an output voltage level and an output frequency, a converter coupled to the input and configured to convert the input AC power into DC power, an inverter coupled to the output and configured to convert the DC power into the output AC power and provide the output AC power to the output, a DC bus coupled between the converter and the inverter including a first capacitive element and a second capacitive element, the first capacitive element being coupled to a first output and a second output of the converter and the second capacitive element being coupled to a first input and a second input of the inverter, a de-coupler circuit coupled between the first and second capacitive elements and configured to selectively decouple the inverter from the converter, and a controller configured to operate the converter, the inverter, and the de-coupler circuit in a first mode of operation such that the output voltage level and output frequency of the output AC power are the same as the input voltage level and input frequency of the input AC power and a second mode of operation such that at least one of the output voltage level or output frequency of the output AC power differs from the input voltage level and input frequency of the input AC power.

In an uninterruptible power supply apparatus, in a power failure of a commercial AC power supply, a switch is turned off to electrically cut off the commercial AC power supply from an AC input filter, and a DC voltage converter is controlled such that a DC voltage that is the difference between terminal-to-terminal voltages of first and second capacitors is eliminated, and when the DC voltage exceeds a threshold voltage, a converter is controlled to reduce the DC voltage.

A method for operating a power factor correction (PFC) circuit of an uninterruptible power supply (UPS) apparatus is provided. The PFC circuit includes two T-type converters, and each of the T-type converters includes four switching tubes. The method includes: converting AC input voltage into a positive bus voltage across a first capacitor and a negative bus voltage across a second capacitor that is connected in series with the first capacitor when the UPS apparatus is operated under a normal supply mode; and controlling conduction states of the switching tubes of the T-type converters to balance the positive bus voltage and the negative bus voltage when the UPS apparatus is operated under a battery supply mode.

The present disclosure provides a high-power-density power converter topology with a common neutral between its input and output AC ports while having a single DC bus. The topology may also be embodied as an online uninterruptible power supply (UPS). The presently-disclosed topology enables high power density by utilizing half-bridge switch structures suitable for MHz-frequency operation.

A circuit includes an emergency lighting system and an AC/DC converter. An output terminal of the emergency lighting system is electrically connected to a LED load, and the other output terminal LED_ON of the emergency lighting system is electrically connected to a switch S2. The switch S2 is controlled by the emergency lighting system. The emergency lighting system includes an AC input detection module, a switching time detection module and a lithium battery. The AC input detection module is electrically connected to a neutral wire VN and a live wire VL. The switching time detection module is electrically connected between an output terminal of the AC input detection module and the LED_ON terminal. An output terminal of the AC/DC converter is electrically connected to a positive electrode of the lithium battery, and the other output terminal of the AC/DC converter is electrically connected to the LED load.

Systems and methods of controlling uninterruptible power supplies of electrical power systems are described. According to one aspect, an electrical power system can include a generator having a stator and a rotor, a power converter coupled to a rotor bus of the rotor, and a control system comprising one or more control devices, the one or more control devices configured to operate the power converter to provide an AC signal for a rotor bus. The system can also include an uninterruptible power supply (UPS). The UPS can include a power storage element configured to receive and store electrical power, and configured to power the control system during a power failure, and, a health check circuit configured to verify a health status of the power storage element, and including a health check disable component configured to disable the health check circuit during the power failure.

An uninterruptible power supply adapted to be connected between an AC line and a load, comprising a battery system, an inverter, and a transformer, and a controller. The battery system stores battery power. The inverter is operatively connected to the battery system. The transformer is operatively connected to the AC line, the load, and an inverter winding operatively connected to the inverter. The controller controls the inverter to supply power to the primary winding using battery power stored in the battery system based on a cost value indicative of reduction of life of the battery system.

An uninterruptible power supply (UPS) is provided that includes a split direct current (DC) link having a first capacitor coupled between a positive DC link terminal and a first node, and a second capacitor coupled between the first node and a negative DC link terminal. The UPS also includes a rectifier coupled to an input of the split DC link and a controller coupled to the rectifier. The rectifier includes first, second, and third legs, wherein each leg is configured to convert a first alternating current (AC) voltage received from an AC source into a DC voltage to be provided to the split DC link, and a fourth leg configured to balance DC link voltages of the first and second capacitors. The controller is configured to maintain functionality of the rectifier during at least one of a partial utility power outage, a full utility outage, and a failure of at least one of the first, second, third, and fourth legs.

A circuit for selecting between a primary power source and a back-up power source is provided in one embodiment. The circuit includes a first port configured to be coupled to a primary power source, a second port configured to be coupled to a back-up power source, a third port configured to be coupled to provide power to a load. The circuit also includes first and second power field effect transistors (FET) coupled between the second port and the third port, a third power FET coupled between the first port and the third port, and a dual ideal diode-OR controller coupled between the second and third power FETs to selectively turn on and off the second and third power FETs. The circuit further includes an opto-isolator coupled to a control input of the first power FET and a controller, coupled to the opto-isolator, that selectively turns on and off the opto-isolator.