Abstract: A method and controller to automatically determine a grounding condition of a motor drive, in which an inverter is operated at a predetermined frequency while a load resistor is connected between a single phase of a motor drive inverter output and a reference node, a leakage flux linkage value is computed according to a neutral-ground voltage of the motor drive, and a processor determines whether the motor drive is solid grounded, high-resistance grounded, or floating according to the leakage flux linkage value. In certain examples, the processor automatically turns the inverter off while the load resistor is connected between the single phase of the inverter output and the reference node, and automatically determines whether the motor drive is delta corner grounded according to the neutral-ground voltage.

Abstract: A method and controller to automatically determine a grounding condition of a motor drive, in which an inverter is operated at a predetermined frequency while a load resistor is connected between a single phase of a motor drive inverter output and a reference node, a leakage flux linkage value is computed according to a neutral-ground voltage of the motor drive, and a processor determines whether the motor drive is solid grounded, high-resistance grounded, or floating according to the leakage flux linkage value. In certain examples, the processor automatically turns the inverter off while the load resistor is connected between the single phase of the inverter output and the reference node, and automatically determines whether the motor drive is delta corner grounded according to the neutral-ground voltage.

Abstract: Power conversion systems, disclosed examples include power conversion systems, ground fault detection apparatus and methods to detect and identify ground faults in a power conversion system using AC coupling to sense a system voltage to determine a leakage flux linkage, and to identify a faulted converter phase based on a phase shift angle of the leakage flux linkage.

Abstract: A PLC or other industrial controller programmed to locate ground faults in a networked high resistance grounded multi-drive system through network communications messaging to automatically place networked motor drives in various operational states to isolate individual drives for ground fault identification testing and selectively identify individual drives as suspected ground fault locations.

Abstract: Power conversion systems, disclosed examples include power conversion systems, ground fault detection apparatus and methods to detect and identify ground faults in a power conversion system using AC coupling to sense a system voltage to determine a leakage flux linkage, and to identify a faulted converter phase based on a phase shift angle of the leakage flux linkage.

Abstract: Methods an apparatus are presented for identifying ground fault locations in multi-drive systems in which individual drives perform self-diagnosis for detected faults based on an identified fault signal frequency while the system drives continue operation, and a ground fault location system identifies suspected drives and individually confirms or exonerates individual drives by selective command speed adjustment while the drives remain operational within system tolerance ranges.

Abstract: A HRG ground fault detector and method for detecting a ground fault in a High Resistance Ground (HRG) system are provided. The HRG ground fault detector in one example embodiment includes a first input A coupled to a first phase PHA of the HRG system, a second input B coupled to a second phase PHB, and a third input C coupled to a third phase PHC, with the HRG ground fault detector generating a simulated neutral voltage VN? from the first phase PHA, the second phase PHB, and the third phase PHC. The simulated neutral voltage VN? has a zero voltage potential when the first phase PHA, the second phase PHB, and the third phase PHC are equal. The HRG ground fault detector further compares the simulated neutral voltage VN? to a predetermined fault voltage threshold, and detects a HRG ground fault if the simulated neutral voltage VN? exceeds the threshold.

Abstract: Methods, control apparatus and computer readable mediums are presented for controlling a switching inverter in which a controller selectively suspends PWM carrier signals to provide inverter switching control signals using zero vectors in response to a maximal pulse width value for a present PWM half cycle being greater than a threshold value, and accumulates a present output control value for individual output phases for use in a subsequent PWM half cycle for selective effective reduction in switching frequency for low-speed operation while maintaining high frequency control loop sampling.

Abstract: Methods, control apparatus and computer readable mediums are presented for controlling a switching inverter in which a controller selectively suspends PWM carrier signals to provide inverter switching control signals using zero vectors in response to a maximal pulse width value for a present PWM half cycle being greater than a threshold value, and accumulates a present output control value for individual output phases for use in a subsequent PWM half cycle for selective effective reduction in switching frequency for low-speed operation while maintaining high frequency control loop sampling.

Abstract: Methods, apparatus and computer readable mediums are presented for controlling a multiphase inverter in which third harmonic injection pulse width modulation (THIPWM) is used for generating inverter switching control signals at or above a non-zero threshold inverter output frequency, and high frequency injection discontinuous pulse width modulation (HFIDPWM) is used for inverter output frequencies below the threshold, where the threshold frequency corresponds to a threshold period less than or equal to the thermal impedance time constant of the inverter switching devices, and the injected high frequency component for HFIDPWM corresponds to a common mode period less than the thermal impedance time constant to mitigate thermal stress on the inverter switches and low speed inverter output derating.

Abstract: Methods, apparatus and computer readable mediums are presented for controlling a multiphase inverter in which third harmonic injection pulse width modulation (THIPWM) is used for generating inverter switching control signals at or above a non-zero threshold inverter output frequency, and high frequency injection discontinuous pulse width modulation (HFIDPWM) is used for inverter output frequencies below the threshold, where the threshold frequency corresponds to a threshold period less than or equal to the thermal impedance time constant of the inverter switching devices, and the injected high frequency component for HFIDPWM corresponds to a common mode period less than the thermal impedance time constant to mitigate thermal stress on the inverter switches and low speed inverter output derating.

Abstract: Methods an apparatus are presented for identifying ground fault locations in multi-drive systems in which individual drives perform self-diagnosis for detected faults based on an identified fault signal frequency while the system drives continue operation, and a ground fault location system identifies suspected drives and individually confirms or exonerates individual drives by selective command speed adjustment while the drives remain operational within system tolerance ranges.

Abstract: A PLC or other industrial controller programmed to locate ground faults in a networked high resistance grounded multi-drive system through network communications messaging to automatically place networked motor drives in various operational states to isolate individual drives for ground fault identification testing and selectively identify individual drives as suspected ground fault locations.

Abstract: A HRG ground fault detector and method for detecting a ground fault in a High Resistance Ground (HRG) system are provided. The HRG ground fault detector in one example embodiment includes a first input A coupled to a first phase PHA of the HRG system, a second input B coupled to a second phase PHB, and a third input C coupled to a third phase PHC, with the HRG ground fault detector generating a simulated neutral voltage VN? from the first phase PHA, the second phase PHB, and the third phase PHC, wherein the simulated neutral voltage VN? comprises a zero voltage potential when the first phase PHA, the second phase PHB, and the third phase PHC are equal, comparing the simulated neutral voltage VN? to a predetermined fault voltage threshold, and detecting a HRG ground fault if the simulated neutral voltage VN? exceeds the threshold.

Abstract: A method for diagnosing the linkages of an inverter including a controller connected to switching devices that are between a DC input and a multi-phase output. The inverter can be diagnosed to determine whether the control signals provided to the switching devices are being properly provided to the inverter and whether the inverter is operating properly. Diagnosis of the inverter is advisable upon commissioning or after completion of a repair. The controller can provide at least one signal to the switching devices and the signal can be monitored adjacent to the switching devices to ensure that the switching devices are receiving the correct signals from the controller. The controller can provide at least one signal to the switching devices and the output of the inverter can be monitored to determine whether the inverter operates in accordance with the provided signal.