Abstract: A method of controlling an electric motor assembly includes receiving sensor feedback that is based at least in part on electrical properties of a variable frequency power signal provided to the electric motor assembly. The method also includes adjusting the phase angle of the variable frequency power signal provided to the electric motor assembly based at least in part on the sensor feedback. The method also includes determining an operational status of the electric motor assembly that receives the variable frequency power signal based at least in part on the sensor feedback.

Abstract: Systems and methods are disclosed for determining an operating point for controlling an electric motor. An exemplary system may include a voltage monitor configured to determine a voltage applied to the electric motor. The system may also include a controller configured to determine the operating point based on the voltage. The controller may include a comparator configured to determine a difference between the voltage and a reference voltage. The controller may also include a regulator configured to generate a correction signal for reducing the difference. The controller may be configured to determine the operating point when the difference is below a predetermined threshold.

Abstract: Systems and methods are described for controlling an electric motor. An exemplary system may include a torque detector configured to detect an output torque of the electric motor. The system may also include a controller configured to control a voltage source to apply a predetermined voltage to drive the electric motor and determine an operating table containing a plurality of operating points. The controller may select an operating current value and generate a plurality of current commands. The controller may also apply each of the plurality of current commands to drive the electric motor and determine an output torque generated by the electric motor. The controller may further determine a target current command that generates a maximum output torque. In addition, the controller may determine an operating point of the operating table based on the target current command. Moreover, the controller may control the electric motor using the operating table.

Abstract: A switched capacitive device includes a stationary portion including a plurality of first electrodes extending at least partially in a longitudinal dimension. Each first electrode has a first substantially active electrode volume. The device also includes a translatable portion including a plurality of second electrodes proximate the plurality of first electrodes. Each second electrode has a second substantially active electrode volume. The first active electrode volume is greater than the second active electrode volume. The second electrodes are translatable with respect to the first electrodes. The second electrodes extend at least partially in the longitudinal dimension. The first electrodes are configured to induce substantially linear motion of the second electrodes in the longitudinal dimension through the use of an electric field induced by at least a portion of the first electrodes.

Abstract: The present disclosure is directed to a system and method for detecting damage of a pitch bearing of a wind turbine. The pitch bearing is part of a pitch drive system having a plurality of pitch drive motors. The method includes measuring at least one electrical signal of the pitch drive system. The method also includes processing the electrical signal(s) of the pitch drive system and comparing the electrical signals of the pitch drive system with a baseline threshold. Thus, the method also includes determining whether damage is present in the pitch bearing based, at least in part, on the comparison, wherein the electrical signal(s) exceeding the baseline threshold is indicative of damage in the pitch bearing.

Abstract: A fault detection system for a wind turbine includes a doubly-fed induction generator (DFIG). The DFIG includes a wye-ring configured for at least three electrical phases. The fault detection system includes a data acquisition system including at least three sensors. Each sensor of said at least three sensors is configured to electrically couple with and measure a respective voltage of each phase of the at least three electrical phases of the wye-ring. The fault detection system further includes an alert system coupled to said data acquisition system. The alert system is configured to apply a Fourier transform to the respective measured voltages of each phase of the at least three electrical phases of the wye-ring. The alert system is further configured to provide an indication of a condition of the wye-ring based upon the transformed measured voltages.

Abstract: A system for controlling an electric motor is disclosed. The system includes a position sensor configured to measure a physical position of a rotor of the electric motor; and a position estimator. The position estimator is configured to: inject a voltage signal having a predetermined frequency into the electric motor, generate an estimated position of a rotor flux based on a feedback current signal in response to the injected voltage signal, and compensate for an offset between the physical position measured by the position sensor and an actual position of the rotor flux based on the estimated position.

Abstract: A method of controlling an electric motor assembly includes receiving sensor feedback that is based at least in part on electrical properties of a variable frequency power signal provided to the electric motor assembly. The method also includes adjusting the phase angle of the variable frequency power signal provided to the electric motor assembly based at least in part on the sensor feedback. The method also includes determining an operational status of the electric motor assembly that receives the variable frequency power signal based at least in part on the sensor feedback.

Abstract: A system for controlling an electric motor is disclosed. The system includes a position sensor configured to measure a physical position of a rotor of the electric motor; and a position estimator. The position estimator is configured to: inject a voltage signal having a predetermined frequency into the electric motor, generate an estimated position of a rotor flux based on a feedback current signal in response to the injected voltage signal, and compensate for an offset between the physical position measured by the position sensor and an actual position of the rotor flux based on the estimated position.

Abstract: Circuits, methods, and systems for driving a load are described. An exemplary driving circuit may include a plurality of switching devices and a controller electrically connected to the switching devices. The controller may be configured to receive a reference voltage signal indicating a target voltage for the driving circuit to generate to drive the load. The reference voltage signal may correspond to a reference space vector in a reference frame. The controller may also be configured to determine that the reference space vector falls within a holding region in which the reference voltage signal is subject to over-modulation. The controller may then generate an adjusted reference voltage signal by adjusting the reference space vector to match a predetermined space vector associated with the holding region. In addition, the controller may be configured to provide the adjusted reference voltage signal to the plurality of switching devices to drive the load.

Abstract: Circuits, methods, and systems for driving a load are described. An exemplary driving circuit may include a plurality of switching devices and a controller electrically connected to the switching devices. The controller may be configured to receive a reference voltage signal indicating a target voltage for the driving circuit to generate to drive the load. The reference voltage signal may correspond to a reference space vector in a reference frame. The controller may also be configured to determine that the reference space vector falls within a holding region in which the reference voltage signal is subject to over-modulation. The controller may then generate an adjusted reference voltage signal by adjusting the reference space vector to match a predetermined space vector associated with the holding region. In addition, the controller may be configured to provide the adjusted reference voltage signal to the plurality of switching devices to drive the load.

Abstract: The present disclosure is directed to a system and method for detecting damage of a pitch bearing of a wind turbine. The pitch bearing is part of a pitch drive system having a plurality of pitch drive motors. The method includes measuring at least one electrical signal of the pitch drive system. The method also includes processing the electrical signal(s) of the pitch drive system and comparing the electrical signals of the pitch drive system with a baseline threshold. Thus, the method also includes determining whether damage is present in the pitch bearing based, at least in part, on the comparison, wherein the electrical signal(s) exceeding the baseline threshold is indicative of damage in the pitch bearing.

Abstract: Systems and methods are disclosed for determining an operating point for controlling an electric motor. An exemplary system may include a voltage monitor configured to determine a voltage applied to the electric motor. The system may also include a controller configured to determine the operating point based on the voltage. The controller may include a comparator configured to determine a difference between the voltage and a reference voltage. The controller may also include a regulator configured to generate a correction signal for reducing the difference. The controller may be configured to determine the operating point when the difference is below a predetermined threshold.

Abstract: Systems and methods are described for controlling an electric motor. An exemplary system may include a torque detector configured to detect an output torque of the electric motor. The system may also include a controller configured to control a voltage source to apply a predetermined voltage to drive the electric motor and determine an operating table containing a plurality of operating points. The controller may select an operating current value and generate a plurality of current commands. The controller may also apply each of the plurality of current commands to drive the electric motor and determine an output torque generated by the electric motor. The controller may further determine a target current command that generates a maximum output torque. In addition, the controller may determine an operating point of the operating table based on the target current command. Moreover, the controller may control the electric motor using the operating table.

Abstract: A dielectric fluid includes a first liquid having first dielectric constant and conductivity values. The dielectric fluid also includes a second liquid having second dielectric constant and conductivity values. The first dielectric constant value is greater than the second dielectric constant value and the second electrical conductivity value is less than the first electrical conductivity value. The first and second liquids form an immiscible mixture that has third dielectric constant and conductivity values between the first and second dielectric constant values and the first and second electrical conductivity values, respectively. The first liquid forms a high conductivity phase representative of the first conductivity value, and the second liquid forms a low conductivity phase representative of the second conductivity value.

Abstract: A switched capacitive device includes a stationary portion including first circuit boards. The device also includes a translatable portion including second circuit boards proximate to, and interdigitated with, the first circuit boards. The second circuit boards are translatable with respect to the first circuit boards. The first circuit boards induce substantially linear motion of the second circuit boards through the use of an electric field induced by the first circuit boards. The device further includes a control system including switching devices and a controller coupled to the switching devices. The switching devices are coupled to at least a portion of at least one first circuit board. The switching device is configured to intermittently energize and de-energize the first circuit board for predetermined periods of time. The controller alternatingly opens and closes the switching devices through transmitted gating commands as a function of a determined load on the switched capacitive device.

Abstract: A fault detection system for a wind turbine includes a doubly-fed induction generator (DFIG). The DFIG includes a wye-ring configured for at least three electrical phases. The fault detection system includes a data acquisition system including at least three sensors. Each sensor of said at least three sensors is configured to electrically couple with and measure a respective voltage of each phase of the at least three electrical phases of the wye-ring. The fault detection system further includes an alert system coupled to said data acquisition system. The alert system is configured to apply a Fourier transform to the respective measured voltages of each phase of the at least three electrical phases of the wye-ring. The alert system is further configured to provide an indication of a condition of the wye-ring based upon the transformed measured voltages.

Abstract: A switched capacitive device includes a stationary portion including first circuit boards. The device also includes a translatable portion including second circuit boards proximate to, and interdigitated with, the first circuit boards. The second circuit boards are translatable with respect to the first circuit boards. The first circuit boards induce substantially linear motion of the second circuit boards through the use of an electric field induced by the first circuit boards. The device further includes a control system including switching devices and a controller coupled to the switching devices. The switching devices are coupled to at least a portion of at least one first circuit board. The switching device is configured to intermittently energize and de-energize the first circuit board for predetermined periods of time. The controller alternatingly opens and closes the switching devices through transmitted gating commands as a function of a determined load on the switched capacitive device.

Abstract: A switched capacitive device includes a stationary portion including a plurality of first electrodes extending at least partially in a longitudinal dimension. Each first electrode has a first substantially active electrode volume. The device also includes a translatable portion including a plurality of second electrodes proximate the plurality of first electrodes. Each second electrode has a second substantially active electrode volume. The first active electrode volume is greater than the second active electrode volume. The second electrodes are translatable with respect to the first electrodes. The second electrodes extend at least partially in the longitudinal dimension. The first electrodes are configured to induce substantially linear motion of the second electrodes in the longitudinal dimension through the use of an electric field induced by at least a portion of the first electrodes.

Abstract: A dielectric fluid includes a first liquid having first dielectric constant and conductivity values. The dielectric fluid also includes a second liquid having second dielectric constant and conductivity values. The first dielectric constant value is greater than the second dielectric constant value and the second electrical conductivity value is less than the first electrical conductivity value. The first and second liquids form an immiscible mixture that has third dielectric constant and conductivity values between the first and second dielectric constant values and the first and second electrical conductivity values, respectively. The first liquid forms a high conductivity phase representative of the first conductivity value, and the second liquid forms a low conductivity phase representative of the second conductivity value.