A method of operating a multi-phase electric machine includes operating a six-phase machine with six phases that are configured into a first group having a first neutral connection and a second group having a second neutral connection. The method also includes determining whether at least one of the six phases is experiencing a fault. In response to the determining, the method includes combining the first and second neutral connections to form a common neutral connection to continue operating the six-phase machine by using the remaining phase not experiencing the fault.

A motor control device includes a power converter that supplies a three-phase voltage to two motors being connected in parallel, a three-phase power line that connects between one of the two motors and the power converter, a branch three-phase power line that connects between the other of the two motors and the power converter, a switching device having two switches that are provided on the branch three-phase power line, a current detection device that detects three-phase currents flowing in the two motors, and a controller. The controller performs a failure determination of the switching device by identifying a phase of a power line in which no current flows in the three-phase power line and the branch three-phase power line, and, when a failure is detected in one of the two switches in the failure determination, controls to change a state of the other switch, which operates normally, to coincide with a state of the failed switch.

A power converter converts power from a power source into power to be supplied to a motor having n-phase (n is an integer of 3 or larger) windings. The power converter includes an inverter including switches connected to the windings, a controller to control operation of each of the switches, and a failure detector to detect a sign of failure in a drive system ranging from the power source to the motor. When a sign of failure is detected by the failure detector, the controller is configured or programmed to check presence or absence of a failure in the drive system while supplying power to the motor by causing the inverter to perform a failure operation.

A power conversion device of an embodiment includes a rectifier that full-wave rectifies alternating current of a plurality of phases supplied from a power supply side, a capacitor that smoothes an output voltage of the rectifier, a voltage detection unit that detects the smoothed voltage, and an open phase detection unit that detects that an open phase has occurred in the alternating current of the plurality of phases based on a component having a frequency that is twice as high as a fundamental frequency of the alternating current of the plurality of phases included in frequency components of the smoothed voltage.

A system for controlling a synchronous motor drive may be configured to receive a command voltage signal and to identify, in the synchronous motor drive, a resistance imbalance signature from the command voltage signal. The system may determine, based on the resistance imbalance signature, respective phase resistances that correspond to phases of a synchronous motor of the synchronous motor drive. Each respective phase resistance may include a phase transistor resistance and a phase winding resistance. The system may identify, based on the phase resistances and an estimated average resistance between the phases of the synchronous motor, one or more phases of the synchronous motor that correspond to one or more phase resistances representing a resistance imbalance.

A method for operating a processing system to identify faults in an electric machine system including a multiphase machine having plurality of sets of windings; comprising: receiving parameter information representative of electrical operating parameters of the multiple phases of each of the multiple winding sets of the multiphase machine; determining symmetrical components based on the parameter information; comparing the symmetrical components to fault information defining faults of the multiple phases of the multiple winding sets with respect to symmetrical component fault values; identifying faults in one or more of the multiple phases of the multiple winding sets based on the comparison.

A method of operating a multi-phase electric machine includes operating a six-phase machine with six phases that are configured into a first group having a first neutral connection and a second group having a second neutral connection. The method also includes determining whether at least one of the six phases is experiencing a fault. In response to the determining, the method includes combining the first and second neutral connections to form a common neutral connection to continue operating the six-phase machine by using the remaining phase not experiencing the fault.

A motor driving device and an air conditioner having the same of the present disclosure limits the switching of a winding switching device when there is a possibility that the winding switching device is deteriorated, in order to increase the life of winding switching device of a motor and prevent malfunction.

The present invention provides an adaptively modulated multi-state inverter system, comprising: a split capacitor, four bridge arms and an isolation switch group, on each of the four bridge arms a pair of complementary power switch groups is arranged; the isolation switch group comprises four fuses and six bidirectional thyristors. The output branches of the first bridge arm, the second bridge arm and the third bridge arm are respectively connected in series with a fuse to output a three-phase voltage, and at three-phase output voltage side two shared auxiliary branches are arranged, one auxiliary branch starts from the fourth bridge arm output branch on which a fuse is connected in series and is then connected to the output terminal of the three-phase voltage via three bidirectional thyristors. The other auxiliary branch starts from the DC side feed branch from the midpoint of the split capacitor, and is connected with the output terminal of the three-phase voltage via three bidirectional thyristors respectively. The invention also provides a modulating method of the multi-state inverter system. The use of the adaptive modulating technology enables the multi-state inverter to have the functions of overcurrent protection, isolation of faulty bridge arms and fault-tolerant control on any single and double bridges.

Systems and methods for extracting motor operational state parameters from an electric motor for improved motor control and motor fault or failure detection are discussed. An exemplary system includes an excitation circuit to apply a drive voltage to an electric motor, and a processor circuit to measure a resulting winding current, extract a current waveform by oversampling the winding current in an entire PWM frame at a sampling rate higher than the PWM frequency, and fit the current waveform in the PWM period to a parametric model. The processor circuit can determine a motor operational state parameter using one or more of the applied drive voltage or the parametric model of the winding current.