Soft Switching Technologies Corporation

Rockwell Automation Technologies Incorporated

Tsi Power Corp.

Rockwell Automation, Inc.

Robert S Schneider

Deepakraj M Divan

William E Brumsickle

Pallab Midya

Peter Nystrom

William R Kranz

Christopher J Liegel

Glen Luckjiff

Joshua D Kagerbauer

Donald G Rosene

A device includes a three phase supply input including a first phase input, a second phase input, and a third phase input. The device further includes a three phase supply output including a first phase output, a second phase output, and a third phase output. The device further includes a three-phase wye-connected auto-transformer having windings including a first winding, a second winding, and a third winding. At least one of the windings is rated for at least a maximum line to line voltage of the three phase supply input. The other two windings are rated for at least a maximum line to neutral voltage of the three phase supply input. One or more of the windings of the three-phase wye-connected auto-transformer are configured to be tapped to generate a voltage sag output as the three phase supply output.

Methods and systems for using a tapped transformer to generate voltage sags

A device includes a first silicon-controlled rectifier (SCR), a second SCR connected in anti-parallel with the first SCR, and a commutation module. The commutation module is configured to apply a reverse bias voltage to the first SCR or the second SCR to turn off the first SCR or the second SCR. The device further includes a voltage clamp configured to dissipate energy when the first SCR or the second SCR are turned off. The voltage clamp is charged as one of the first SCR or the second SCR are powered on.

Auxiliary commutated silicon-controlled rectifier circuit methods and systems

An illustrative device includes a first silicon-controlled rectifier (SCR) and a second silicon-controlled rectifier (SCR) connected in anti-parallel and a first commutation module, which includes a first voltage source, a first diode, and a first self-commutating semiconductor switch. The device also includes a second commutation module including a second voltage source, a second diode, and a second self-commutating semiconductor switch. The first voltage source, the first diode, and the first self-commutating semiconductor switch of the first commutation module are connected in series. The second voltage source, the second diode, and the second self-commutating semiconductor switch of the second commutation module are connected in series. The first SCR, the second SCR, the first commutation module, and the second commutation module are connected in parallel. The commutation modules are configured to apply reverse bias voltages to the first and second SCRs to turn off the SCRs.

An AC power converter converts power from an AC power source to an AC load. A DC power holding source is coupled to an input half-bridge switch, a common half-bridge switch and an output half-bridge switch. A controller is coupled to at least two of the input half-bridge switch, the common half-bridge switch, and an output half-bridge switch. The controller switches the input half bridge at the first switching frequency in boost mode and at the line frequency in buck mode. The controller also switches the output half bridge switch at the first switching frequency in buck mode and at the line frequency in boost mode. Input and output low pass filters can eliminate switching frequency energy from entering the AC source and load. The converter maintains a DC power holding source voltage slightly above peak AC input voltage and significantly less than twice the peak AC input voltage.

Power converter for AC mains

An AC power converter converts power from an AC power source to an AC load. A DC power holding source is coupled to an input half-bridge switch, a common half-bridge switch and an output half-bridge switch. A controller is coupled to the input half-bridge switch, the common half-bridge switch, and an output half-bridge switch to generate at least two control signals at a common switching frequency, wherein the controller generates the at least two control signals with a phase difference there between chosen to cause a ripple frequency in both the input low pass filter and the output low pass filter to be double the common switching frequency. An input low pass filter can eliminate switching frequency energy from entering the AC power source. An output low pass filter can eliminate switching frequency energy from entering the AC load.

Multibridge power converter for AC mains

A voltage sag correction device includes an input terminal adapted to receive a first operating signal having a line-to-neutral voltage. The first operating signal is provided to a load through an output terminal. A regulator module includes a rectifying device adapted to rectify a line-to-line input signal, a storage unit adapted to store energy corresponding to the rectified line-to-line input signal, and an inverter switching device adapted to use the stored energy to generate a correction signal during at least a portion of a voltage sag. An injection transformer in electrical communication with the regulator module is adapted to reduce a voltage of the correction signal. A bypass switch is in a closed position during a normal operating condition such that the injection transformer is bypassed. The bypass switch is in an open position during at least a portion of the voltage sag such that the injection transformer is energized.

Dynamic voltage sag correction

In dynamic voltage sag correctors and other power conversion equipment having a DC bus that is subject to over-voltage conditions due to power being fed back by a regenerative load, a bus discharge switching device and a discharge resistor are connected in series across the DC bus lines. The discharge switching devices are switched on to discharge the energy storage device connected to the bus, or to separately discharge the two capacitors of a split capacitor DC bus, to eliminate the over-voltage conditions. The discharge switching devices may be switched on and off periodically with a selected duty cycle to discharge energy from the energy storage capacitor or other energy storage device through the discharge resistor at a rate which does not exceed the power rating of the discharge resistor. The discharge switching device may be switched with a fixed duty cycle or with a variable duty cycle that is based on the dynamic power dissipation characteristics of the discharge resistor.

Power conversion and voltage sag correction with regenerative loads

Dual feed power supply system provides high reliability of a dual utility feed, with minimal interruptions in power supplied to critical loads during switching, and compensation for voltage sags occurring on the primary power feed. AC input buses are connected through a transfer switching apparatus to phase lines of a distribution bus. The transfer switching apparatus has a first input terminal connected to one of the phase lines of the first input bus and a second input terminal connected to one of the phase lines of the second input bus, and an output terminal connected to one of the phase lines of the distribution bus. Input switches allow switching from one or the other of the AC input buses to the distribution bus, with a fast transfer switch used to interrupt the supply of power from the input buses to the distribution bus during switching of the input switches.

Dual feed power supply systems with enhanced power quality

Floating electrically isolated active impedance modules are formed to attach to power transmission lines without breaking the lines such that the power line forms a secondary of the main transformer of the module. Each module includes an electrical energy storage device and a switching circuit, such as a single phase inverter, connected to the storage device and to the main transformer primary winding. The inverter can be controlled to couple a selected voltage to the transmission line through the main transformer primary winding which can provide effective positive impedance, negative impedance, or a voltage at or near phase quadrature with the line current. Many active impedance modules may be distributed over a power system grid to allow control of the impedance of the power lines in the grid and to steer power through the grid, with each module electrically isolated from ground and from other phase lines of the transmission system.

Distributed floating series active impendances for power transmission systems

A low cost, small size, light weight, and highly effective system and method for providing dynamic power line voltage sag correction is provided. A dynamic voltage sag corrector includes a static bypass switch and a regulator/storage module connected together in parallel between input terminals and output terminals. Under normal operating conditions, the static bypass switch is closed, and a normal line voltage level is provided directly from the input terminals to the output terminals via the static bypass switch. When a voltage sag condition is indicated, the static bypass switch is opened, and the regulator/storage module is controlled to provide a near normal output voltage signal to the output terminals. The regulator/storage module includes a power conversion circuit which is controlled to provide the desired output voltage signal by adding a voltage level on storage capacitors to the available input line voltage signal. The components of the dynamic voltage sag corrector are selected to provide voltage sag correction for a duration sufficient to provide correction of 90-95% of voltage sag/drop conditions which are likely to be encountered. The size, cost, and weight of the dynamic voltage sag corrector is thereby reduced. The dynamic voltage sag corrector may also provide surge condition correction, may be configured to provide extended duration voltage sag correction to a priority portion of a load, may provide support to a load even if there is a complete break in an input power line, and may be employed in single or multi-phase applications.

A converter for providing three phase power to a three phase load from a single phase supply includes an inverter connected to single phase input power lines and a bi-directional switch connected in series with one of the input power lines. The converter has three output lines, one connected to the inverter output, another connected to an input power line between the bi-directional switch and the inverter, and the third connected directly to the other input power line. The inverter switching devices are controlled to provide a signal on the output of the inverter to provide balanced three phase power on the converter output lines. This is preferably accomplished by pulse width modulation of an inverter output voltage reference signal derived by phase shifting the single phase input voltage signal by 60.degree.. The inverter is preferably also controlled to phase shift the inverter output signal when necessary to ensure that the net power flow into the inverter is zero under light load conditions. During load start-up, the bi-directional switch is phase controlled to adjust the amplitude of the converter output current to thereby adjust the load current to limit inrush current levels and provide a soft starter by ramping up the current in the load.

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Middleton, WI, United States of America

Robert S Schneider