Abstract: The present techniques include methods and systems for detecting the grounding condition of an electrical system to automatically determine a suitable electrical drive configuration. The drive includes a test resistor which may be connected or disconnected from the drive to measure different drive voltages. The measured drive voltages are analyzed to determine a type of grounding configuration of the electrical system in which the drive is to be installed. Embodiments also include determining ground resistance condition such as a high resistance ground (HRG) fault or a ground resistance fault when the drive is in operation.

Abstract: A motor drive system provides for analysis of current flow in the DC bus to identify ground faults and their locations. Low-frequency positive polarity and negative polarity current differences indicate ground faults from the positive DC bus and negative DC bus respectively. High-frequency signals indicate ground faults in the motor windings and connecting leads.

Abstract: A three-phase power converter includes a converter configured to convert a three phase AC power input to a DC power output, the DC power output being provided to high and low sides of a DC bus, and an inverter coupled to the DC bus and configured to convert the DC power to a three phase AC output. The inverter comprises three legs and each leg comprises a pair of solid state switches and a respective output therebetween. The power converter further includes a common mode voltage control filter comprising three filter inputs and two filter outputs, each filter input coupled to an output of a respective leg of the inverter and each filter output coupled to a respective side of the DC bus.

Abstract: A transformer for converting 3 phase AC to 9 phase AC power is provided. The transformer includes first, second and third coils, each coil having a plurality of serial windings coupled together to form a polygon. The transformer further includes first, second and third input terminals each linked to a respective winding of the first, second and third coils. The input terminals are configured to receive a first, second and third phases of input AC power and at least one selected input terminal of the first, second and third input terminals is adjustable to alter a number of turns of the respective winding of the corresponding first, second or third coil on either side of the selected input terminal. The transformer further includes first through ninth output terminals linkable to first through ninth output power lines.

Abstract: Electrical power quality test circuitry for testing response of an electrical device to input power disturbances is provided. The test circuitry includes a power structure having a rectifier configured to convert incoming AC voltage to DC voltage on a DC bus, and a power inverter configured to convert DC voltage from the bus to three-phase output AC voltage applied to the electrical device. The test circuitry also includes a control circuit configured to apply control signals to at least the power inverter to emulate at least one of a change in the amplitude of at least one phase of the output AC voltage at least one phase angle of at least one phase of the output AC voltage, and a frequency change for all phases of the output AC voltage.

Abstract: Embodiments of the present invention provide novel techniques for using multiple 18-pulse rectifier circuits in parallel. In particular, each rectifier circuit may include an autotransformer having 15 inductors coupled in series, joined by 15 nodes interposed between pairs of the inductors. The inductors may be represented as a hexagon in which alternating sides of the hexagon have two and three inductors, respectively. Each rectifier circuit may also include three inputs for three-phase AC power coupled to alternating vertices of the hexagonal representation and nine outputs for AC power coupled between each node that is not a vertex of the hexagonal representation and a respective diode bridge. Outputs of the diode bridges for the rectifier circuits may be coupled to a DC bus. In addition, a means for reducing circulating current between the parallel rectifier circuits and for promoting load sharing between the parallel rectifier circuits is also provided.

Abstract: Power conversion systems and methods are provided for driving a plurality of motor loads, in which an autotransformer receives AC input currents and provides a plurality of multiphase outputs at a non-zero phase angle relative to one another, and the individual multiphase outputs are provided to corresponding motor drives with rectifiers to convert the multiphase outputs to DC electrical power, and inverters to convert the DC power to AC to drive corresponding motor loads.

Abstract: The present techniques include methods and systems for detecting the grounding condition of an electrical system to automatically determine a suitable electrical drive configuration. The drive includes a test resistor which may be connected or disconnected from the drive to measure different drive voltages. The measured drive voltages are analyzed to determine a type of grounding configuration of the electrical system in which the drive is to be installed. Embodiments also include determining ground resistance condition such as a high resistance ground (HRG) fault or a ground resistance fault when the drive is in operation.

Abstract: Techniques for using multiple 18-pulse rectifier circuits in parallel are described herein. In particular, each rectifier circuit may include an autotransformer having 15 inductors coupled in series, joined by 15 nodes interposed between pairs of the inductors. The inductors may be represented as a hexagon in which alternating sides of the hexagon have two and three inductors, respectively. Each rectifier circuit may also include three inputs for three-phase AC power coupled to alternating vertices of the hexagonal representation and nine outputs for AC power coupled between each node that is not a vertex of the hexagonal representation and a respective diode bridge. Outputs of the diode bridges for the rectifier circuits may be coupled to a DC bus. In addition, a means for reducing circulating current between the parallel rectifier circuits and for promoting load sharing between the parallel rectifier circuits is also provided.

Abstract: The present invention relates to a protective circuit to provide over voltage protection for an ASD. The protective circuit provides the benefits of fewer components with lower power ratings than existing protective circuits. The protective circuit may be incorporated directly in the ASD for continuous protection or mounted externally and connected to the ASD under operating conditions that require the circuit. This flexibility for mounting the protective circuit allows the capacitor of the protective circuit to be sized either in relation to capacitive elements on the DC bus within the ASD or according to external capacitance observed at the output of the ASD. In addition, the circuit is only operative during an overvoltage condition allowing for power ratings lower than would be required for continuous operation.

Abstract: A motor drive system provides for analysis of current flow in the DC bus to identify ground faults and their locations. Low-frequency positive polarity and negative polarity current differences indicate ground faults from the positive DC bus and negative DC bus respectively. High-frequency signals indicate ground faults in the motor windings and connecting leads.

Abstract: A filter device reduces reflections on power lines from the motor drive to AC motors by providing a differential mode choke in series with a common mode choke both shunted by resistances tailored to the characteristic impedance of the power cable for differential mode and common mode reflections respectively. By treating both common mode based and differential mode based reflections, superior transient control and motor drive performance may be obtained.

Abstract: A transformer for converting 3 phase AC to 9 phase AC power is provided. The transformer includes first, second and third coils, each coil having a plurality of serial windings coupled together to form a polygon. The transformer further includes first, second and third input terminals each linked to a respective winding of the first, second and third coils. The input terminals are configured to receive a first, second and third phases of input AC power and at least one selected input terminal of the first, second and third input terminals is adjustable to alter a number of turns of the respective winding of the corresponding first, second or third coil on either side of the selected input terminal. The transformer further includes first through ninth output terminals linkable to first through ninth output power lines.

Abstract: A three-phase power converter includes a converter configured to convert a three phase AC power input to a DC power output, the DC power output being provided to high and low sides of a DC bus, and an inverter coupled to the DC bus and configured to convert the DC power to a three phase AC output. The inverter comprises three legs and each leg comprises a pair of solid state switches and a respective output therebetween. The power converter further includes a common mode voltage control filter comprising three filter inputs and two filter outputs, each filter input coupled to an output of a respective leg of the inverter and each filter output coupled to a respective side of the DC bus.

Abstract: Embodiments of the present invention provide novel techniques for using multiple 18-pulse rectifier circuits in parallel. In particular, each rectifier circuit may include an autotransformer having 15 inductors coupled in series, joined by 15 nodes interposed between pairs of the inductors. The inductors may be represented as a hexagon in which alternating sides of the hexagon have two and three inductors, respectively. Each rectifier circuit may also include three inputs for three-phase AC power coupled to alternating vertices of the hexagonal representation and nine outputs for AC power coupled between each node that is not a vertex of the hexagonal representation and a respective diode bridge. Outputs of the diode bridges for the rectifier circuits may be coupled to a DC bus. In addition, a means for reducing circulating current between the parallel rectifier circuits and for promoting load sharing between the parallel rectifier circuits is also provided.

Abstract: Embodiments of the present invention provide novel techniques for using multiple 18-pulse rectifier circuits in parallel. In particular, each rectifier circuit may include an autotransformer having 15 inductors coupled in series, joined by 15 nodes interposed between pairs of the inductors. The inductors may be represented as a hexagon in which alternating sides of the hexagon have two and three inductors, respectively. Each rectifier circuit may also include three inputs for three-phase AC power coupled to alternating vertices of the hexagonal representation and nine outputs for AC power coupled between each node that is not a vertex of the hexagonal representation and a respective diode bridge. Outputs of the diode bridges for the rectifier circuits may be coupled to a DC bus. In addition, a means for reducing circulating current between the parallel rectifier circuits and for promoting load sharing between the parallel rectifier circuits is also provided.

Abstract: Electrical power quality test circuitry for testing response of an electrical device to input power disturbances is provided. The test circuitry includes a power structure having a rectifier configured to convert incoming AC voltage to DC voltage on a DC bus, and a power inverter configured to convert DC voltage from the bus to three-phase output AC voltage applied to the electrical device. The test circuitry also includes a control circuit configured to apply control signals to at least the power inverter to emulate at least one of a change in the amplitude of at least one phase of the output AC voltage at least one phase angle of at least one phase of the output AC voltage, and a frequency change for all phases of the output AC voltage.

Abstract: A terminator reduces reflections on power lines connecting an inverter to an AC motor by providing a differential-mode reflection damping element and at least one common-mode reflection damping element, the latter including a series capacitance to substantially reduce power dissipation in the resistance of the damping elements.

Abstract: The present invention relates to a protective circuit to provide over voltage protection for an ASD. The protective circuit provides the benefits of fewer components with lower power ratings than existing protective circuits. The protective circuit may be incorporated directly in the ASD for continuous protection or mounted externally and connected to the ASD under operating conditions that require the circuit. This flexibility for mounting the protective circuit allows the capacitor of the protective circuit to be sized either in relation to capacitive elements on the DC bus within the ASD or according to external capacitance observed at the output of the ASD. In addition, the circuit is only operative during an overvoltage condition allowing for power ratings lower than would be required for continuous operation.

Abstract: Power conversion systems and methods are provided for driving a plurality of motor loads, in which an autotransformer receives AC input currents and provides a plurality of multiphase outputs at a non-zero phase angle relative to one another, and the individual multiphase outputs are provided to corresponding motor drives with rectifiers to convert the multiphase outputs to DC electrical power, and inverters to convert the DC power to AC to drive corresponding motor loads.