Abstract: A transformer for converting 3 phase AC to 9 phase AC power is provided. The transformer comprising a laminated core, first, second and third coils constructed on the laminated core, each coil including several windings. Cooling ducts are provided in each coil, wherein at least one cooling duct is disposed between the laminated core and an adjacent winding of the respective coil. The transformer further includes first, second and third input terminals each linked to the first, second and third coils, and configured to receive a first, second and third phases of input AC power and first through ninth output terminals linkable to first through ninth output power lines.

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 method is provided for detection of a ground fault in a high resistance network in a voltage source power conversion circuit comprising a power converter that converts incoming AC power to DC power applied to a DC bus and an inverter that converts DC power from the DC bus to output AC power. The method includes detecting a midpoint-to-ground voltage between a low side of the DC bus and a ground potential and detecting the presence of a ground fault in a high resistance network based upon the detected midpoint-to-ground voltage.

Abstract: A power electronics device with an improved IGBT protection mechanism is provided. More specifically, systems and methods are provided for reducing the switching frequency of an inverter module based on the junction temperature variation of the IGBT.

Abstract: An improved choke assembly for a power electronics device is provided. More specifically, a choke assembly with improved protection from environmental conditions such as dirt and water is provided. An improved choke assembly may include an insulative housing for an inductor coil that seals the inductor coil from the environment.

Abstract: A method and apparatus for predicting junction device temperature of at least a first switching device in a power conversion module that includes the first switching device and at least a second switching device, the method comprising the steps of identifying a cross thermal impedance value indicative of how the temperature of the second switching device effects the first switching device temperature and using the cross thermal impedance value to predict the temperature of the at least a first switching device.

Abstract: A method and apparatus for predicting junction device temperature of at least a first switching device in a power conversion module that includes a plurality of switching devices, the method comprising the steps of, during switching activity, identifying at least one operating characteristic of the first switching device and solving an equation that uses the identified operating characteristic to predict the temperature of the first switching device where the equation solved is a function of the location of the first switching device with respect to the other switching devices in the plurality.

Abstract: The present techniques include methods and systems for operating converter to maintain a lifespan of the converter. In some embodiments, the operating frequency of the converter may be increased such that stress may be reduced on the bond wires of the converter. More specifically, embodiments involve calculating the aging parameters for certain operating conditions of the converter operating in a maximum power point tracking (MPPT) mode and determining whether the MPPT operation results in aging the converter to a point which reduces the converter lifespan below a desired lifespan. If the MPPT operation reduces the converter lifespan below the desired lifespan, the frequency of the converter may be increased such that the converter may be controlled to operate at a percentage of MPPT. Thus, in some embodiments, power output may be optimized with respect to maintaining a desired lifespan of the converter.

Abstract: The present techniques include methods and systems for operating a wind power system to maintain a lifespan of the rotor side converter. In some embodiments, the current of the rotor side converter may be minimized to reduce the stress and/or junction temperature variation in the switching transistors and bond wires of the converter. More specifically, embodiments involve using a minimal current in the rotor side converter based on the rotor side and grid side reactive powers. If the grid side reactive power is greater than a maximum grid side reactive power, the grid side reactive power may be reduced. Further, if the total reactive power does not meet the grid reactive power requirements, the minimal current in the rotor side converter may be adjusted such that the system may sufficiently power the grid.

Abstract: The present techniques include methods and systems for operating an inverter to maintain a lifespan of the inverter. In some embodiments, the switching frequency and/or the output current of the inverter may be changed such that stress may be reduced on the inverter bond wires of the inverter. More specifically, embodiments involve calculating the aging parameters for certain operating conditions of the inverter and determining whether the operating conditions result in aging the inverter to a point which reduces the inverter lifespan below a desired lifespan. If the operating conditions reduce the inverter lifespan below the desired lifespan, the switching frequency may be reduced to a lower or minimum switching frequency of the inverter and/or the output current of the inverter may be reduced to a maximum output current at the minimum switching frequency.

Abstract: A ground fault detection system is provided. The ground fault detection system includes a magnetic core having first and second primary legs and a secondary leg disposed between the first and second primary legs. The ground fault detection system also includes first and second primary windings disposed around the first and second primary legs respectively and configured to introduce current in the first and second primary legs. Further, the ground fault detection system includes first and second secondary windings disposed around the first and second primary legs respectively and configured to detect a ground fault based upon a magnetic flux generated in response to the introduced current.

Abstract: Embodiments of the present invention provide novel techniques for using a switched converter to provide for three-phase alternating current (AC) rectification, regenerative braking, and direct current (DC) voltage boosting. In particular, one of the three legs of the switched converter is controlled with a set of pulse width modulation (PWM) control signals so that the input AC phase having the highest voltage is rectified and one of the switches in the two other legs is turned on to allow for added voltage. This switching activity allows for voltage from multiple AC line mains to be combined, resulting in an overall boost of the DC voltage of the rectifier. The DC voltage boost can then be applied to the common DC bus in order to ameliorate voltage sags, help with motor starts, and increase the ride-through capability of the motor.

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: A dynamic braking circuit for an electronic motor drive shunts the DC link of the drive with a resistor using two control strategies. The first control strategy used for lower levels of braking employs a pulse width modulated signal and the second control strategy used for higher levels of braking uses a hysteretic signal significantly reducing switching losses in the semiconductor devices controlling the dynamic braking resistor allowing higher braking capacity.

Abstract: A power electronics device with an improved pre-charge circuit configuration is provided. More specifically, the input of the motor drive module may accept an AC or DC source voltage. In this way, the pre-charge circuit of the motor drive module may be utilized whether the motor drive is coupled to an AC or DC source.

Abstract: A system and method for estimating a condition of a power module is provided. In accordance with an embodiment, a motor controller may be maintained by tracking a total proportion of power module life expended by a power module in a variable frequency motor controller based on a minimum junction temperature or a mean junction temperature and a junction temperature change, and indicating when the power module is estimated to fail.

Abstract: Provided is a motor controller and method of controlling a motor with an improved maximum junction temperature rating. In accordance with one aspect of the present invention, a motor is controlled by varying a common mode voltage duty ratio for a plurality of solid state switching devices in a power inverter, generating drive signals for the solid state switching devices based at least in part upon the common mode voltage duty ratio, and changing states of the solid state switching devices based upon the drive signals.

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 is disclosed that includes a power input configured to receive alternating current (AC) power and a rectifier having a switching frequency selected to convert the AC power to direct current (DC) power. The motor drive unit also includes an input filter circuit connected between the power input and the rectifier and configured to suppress frequency harmonics across a range of harmonics. Additionally, the motor drive unit includes a block filter circuit connected between the power input and the rectifier and configured to substantially block frequency harmonics associated with the switching frequency of the rectifier. Furthermore, the motor drive unit includes an inverter configured to receive the DC power from the rectifier and convert the DC power to a series of pulses configured to drive a motor.