Abstract: A converter includes a DC split link with a positive line, a floating midpoint, and a negative DC line, a first DC capacitance arranged between the positive line and the floating midpoint, a second DC capacitance arranged between the negative line and the floating midpoint, a first resistor arranged in parallel to the first DC capacitance, a second resistor is arranged in parallel to the second DC capacitance. The first and the second resistors are configured to be engaged during a pre-charge phase of the converter.

Abstract: An uninterruptible power supply (UPS) converter circuit includes a controlled switching element, a filter capacitor, and a split DC capacitor comprising a plus DC capacitor and a minus DC capacitor split at a DC-link mid-point, connected to each other at the DC-link mid-point on a respective first side. A second side of the input filter capacitor at an AC point is coupled via an inductor element to a second side of the controlled switching element, the second side of the controlled switching element being coupled to the second side of the plus DC capacitor and the minus capacitor. The controlled switching element operates is configured to be controlled such that a current from the AC point via the inductor element flows alternatingly to either the plus DC output capacitor or the minus DC capacitor, and to the DC-link mid-point, respectively, thereby discharging the input filter capacitor.

Abstract: 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.

Abstract: A voltage balancing circuit for a double-boost DC/DC converter includes a split DC-link having a first midpoint, outer directional devices and inner switches parallel-connected to the DC-link, wherein the outer directional devices are connected to capacitors of the split DC-link and to the inner switches. The inner switches are connected to each other at a second midpoint. A DC source terminal, to which a DC source is connectable in parallel over inductances to the inner switches, is included. An inductance is connected to the midpoint of the DC link and to the midpoint of the inner switches.

Abstract: A converter includes a DC split link with a positive line, a floating midpoint, and a negative DC line, a first DC capacitance arranged between the positive line and the floating midpoint, a second DC capacitance arranged between the negative line and the floating midpoint, a first resistor arranged in parallel to the first DC capacitance, a second resistor is arranged in parallel to the second DC capacitance. The first and the second resistors are configured to be engaged during a pre-charge phase of the converter.

Abstract: An uninterruptible power supply (UPS) system is provided. The UPS system includes a plurality of UPSs, a ring bus coupled to the UPSs, a plurality of chokes, and at least one static switch coupled between an associated UPS of the UPSs and the ring bus. Each choke electrically couples an associated UPS to the ring bus. The static switch is switchable to selectively bypass at least one choke.

Abstract: A multi-mode uninterruptible power supply (UPS) is provided. The multi-mode UPS includes a first path including a rectifier and an inverter, and a second path in parallel with the first path, wherein the multi-mode UPS is operable in an economy mode in which power flows from a utility to a load through the second path while at least one of the rectifier and the inverter is activated, the at least one of the rectifier and the inverter operable to perform at least one of DC voltage regulation, reactive power compensation, and active damping.

Abstract: Current source rectifier (CSR) systems and methods for a power source including three phase lines are disclosed. One illustrative CSR system includes a rectifier operable to receive an AC input voltage and provide a DC output voltage and a controller communicatively coupled to the rectifier. The rectifier comprises first, second, and third phase legs including a plurality of switches with each switch coupled to an associated phase line of the three phase lines. The controller is operable to (i) control operation of the plurality of switches in accordance with a first switching sequence when measured input voltages on at least two phase lines of the three phase lines are outside of the predetermined voltage range and (ii) control operation of the plurality of switches in accordance with a second switching sequence when the measured input voltages on the at least two phase lines are within the predetermined voltage range.

Abstract: 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.

Abstract: In at least one embodiment, a system may include a plurality of uninterruptible power supplies (UPSs), a ring bus, a plurality of chokes, with each choke of the plurality of chokes electrically coupling an associated UPS of the plurality of UPSs to the ring bus, and at least one switch electrically coupled between at least one UPS of the plurality of UPSs and the ring bus, with the at least one switch having an opening time of less than 10 milliseconds.

Abstract: 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.

Abstract: A control system and methods for a multilevel power converter are provided. The converter includes a rectifier coupled to a DC link having a midpoint coupled to electrical ground that divides the DC link into two halves. The control system is configured to generate a reference current command for controlling an output of the rectifier, the reference current command generated based on a difference between a desired and measured DC link voltage value. The system is also configured to determine a zero-sequence current component of input current supplied to the multilevel power converter, wherein the zero-sequence current component is associated with non-linearities in said multilevel power converter that cause ground current injection into the input current by the rectifier. The system is further configured to subtract the determined zero-sequence current component from the reference current command to reduce the ground current injected into the input current by the rectifier.

Abstract: Current source rectifier (CSR) systems and methods for a power source including three phase lines are disclosed. One illustrative CSR system includes a rectifier operable to receive an AC input voltage and provide a DC output voltage and a controller communicatively coupled to the rectifier. The rectifier comprises first, second, and third phase legs including a plurality of switches with each switch coupled to an associated phase line of the three phase lines. The controller is operable to (i) control operation of the plurality of switches in accordance with a first switching sequence when measured input voltages on at least two phase lines of the three phase lines are outside of the predetermined voltage range and (ii) control operation of the plurality of switches in accordance with a second switching sequence when the measured input voltages on the at least two phase lines are within the predetermined voltage range.

Abstract: Current source rectifiers (CSR) and methods for a power source including three phase lines are provided herein. The CSR includes a rectifier having a plurality of switches, each switch of the plurality of switches coupled to an associated phase line of the three phase lines. The rectifier operable to receive an alternating current (AC) input voltage and provide a direct current (DC) output voltage. The CSR also includes a controller configured to control operation of the switches in accordance with a first switching sequence when measured input voltages on at least two phase lines of the three phase lines are outside of a predetermined voltage range, and control operation of the switches in accordance with a second switching sequence when the measured input voltages on the at least two phase lines are within the predetermined voltage range.

Abstract: A control system and methods for a multilevel power converter are provided. The converter includes a rectifier coupled to a DC link having a midpoint coupled to electrical ground that divides the DC link into two halves. The control system is configured to generate a reference current command for controlling an output of the rectifier, the reference current command generated based on a difference between a desired and measured DC link voltage value. The system is also configured to determine a zero-sequence current component of input current supplied to the multilevel power converter, wherein the zero-sequence current component is associated with non-linearities in said multilevel power converter that cause ground current injection into the input current by the rectifier. The system is further configured to subtract the determined zero-sequence current component from the reference current command to reduce the ground current injected into the input current by the rectifier.

Abstract: Current source rectifiers (CSR) and methods for a power source including three phase lines are provided herein. The CSR includes a rectifier having a plurality of switches, each switch of the plurality of switches coupled to an associated phase line of the three phase lines. The rectifier operable to receive an alternating current (AC) input voltage and provide a direct current (DC) output voltage. The CSR also includes a controller configured to control operation of the switches in accordance with a first switching sequence when measured input voltages on at least two phase lines of the three phase lines are outside of a predetermined voltage range, and control operation of the switches in accordance with a second switching sequence when the measured input voltages on the at least two phase lines are within the predetermined voltage range.

Abstract: In at least one embodiment, a system may include a plurality of uninterruptible power supplies (UPSs), a ring bus, a plurality of chokes, with each choke of the plurality of chokes electrically coupling an associated UPS of the plurality of UPSs to the ring bus, and at least one switch electrically coupled between at least one UPS of the plurality of UPSs and the ring bus, with the at least one switch having an opening time of less than 10 milliseconds.

Abstract: An uninterruptible power supply (UPS) system is provided. The UPS system includes a plurality of UPSs, a ring bus coupled to the UPSs, a plurality of chokes, and at least one static switch coupled between an associated UPS of the UPSs and the ring bus. Each choke electrically couples an associated UPS to the ring bus. The static switch is switchable to selectively bypass at least one choke.

Abstract: An uninterruptible power supply (UPS) system is provided. The UPS system includes a plurality of UPSs, a ring bus that electrically couples the UPSs together, a static switch coupled between an associated UPS of the UPSs and the ring bus, and a controller. The controller receives current data representative of an inverter current and a load current associated with the associated UPS. An output capacitor of the associated UPS is coupled to a node that conducts the inverter current and the load current. The controller further calculates a measured current based on the received current data, determines a voltage of said output capacitor, generates a derived current based on the determined voltage and a predetermined capacitance of said output capacitor, compares the measured current and the derived current to identify a fault location, and controls said static switch based on the identified fault location.

Abstract: A system is provided. The system includes a plurality of uninterruptible power supplies (UPSs), a ring bus, a plurality of chokes, each choke of the plurality of chokes electrically coupling an associated UPS of the plurality of UPSs to the ring bus, and at least one switch electrically coupled between at least one UPS of the plurality of UPSs and the ring bus, the at least one switch having an opening time of less than 10 milliseconds.