Abstract: A motor drive system and method for determining an optimized efficiency of the motor drive system are provided. The motor drive system includes a system controller, a motor drive having includes an inverter configured to generate the AC power upon one or more motor leads, and an electric motor, which is to convert the AC power from the motor leads to rotational energy. A dynamometer may include a load coupled to the shaft and sensors to measure to measure operating characteristics such as torque and speed of the electric motor. The system controller is configured to generate a lookup table, with an entry describing an output current command for operating the inverter and the motor at a maximum system efficiency for a given combination rotational speed and output torque. Motor temperature may also be measured and used as an additional index into the lookup table.

Abstract: A motor drive system for an electrified vehicle includes a DC source, such as a battery, and an inverter, which includes one or more phase drivers, each configured to switch current from the DC source to generate AC power upon one or more output terminals using a hybrid of two or more different solid-state switches, each having a corresponding voltage rating. A nine-switch inverter includes three phase drivers, each including high, low, and middle solid-state switches, with Si-MOSFET high and low switches having a first voltage rating of half of the rated voltage of the system, and with Gallium Nitride (GaN) transistors rated to block a full rated voltage of the system used for the middle switches. A delay driver synchronizes timing between two different solid-state switches by energizing control terminals at different rates. The inverter can be operated using near-state pulse-width modulation (NSPWM) to reduce switching losses.

Abstract: A method and system for characterizing a state of health of a winding of an electric machine are provided. The winding may include one or more stator windings in an electric machine, for example, a permanent magnet synchronous machine (PMSM). The method comprises: applying a voltage pulse to the winding; measuring a phase current signal of a current supplied to the winding; determining a high-frequency transient current based on the phase current signal. The state of health of the winding may be calculated as a function of change in frequency spectrum of the high-frequency transient current. The method may include calculating a plurality of packets using a wavelet packet decomposition of the high-frequency transient current; and determining one or both of: the state of health or a classification of degradation, using an indicator based upon at least one packet of the plurality of packets.

Abstract: A motor drive system and method for determining an optimized efficiency of the motor drive system are provided. The motor drive system includes a system controller, a motor drive having includes an inverter configured to generate the AC power upon one or more motor leads, and an electric motor, which is to convert the AC power from the motor leads to rotational energy. A dynamometer may include a load coupled to the shaft and sensors to measure to measure operating characteristics such as torque and speed of the electric motor. The system controller is configured to generate a lookup table, with an entry describing an output current command for operating the inverter and the motor at a maximum system efficiency for a given combination rotational speed and output torque. Motor temperature may also be measured and used as an additional index into the lookup table.

Abstract: A motor drive system for an electrified vehicle includes a DC source, such as a battery, and an inverter, which includes one or more phase drivers, each configured to switch current from the DC source to generate AC power upon one or more output terminals using a hybrid of two or more different solid-state switches, each having a corresponding voltage rating. A nine-switch inverter includes three phase drivers, each including high, low, and middle solid-state switches, with Si-MOSFET high and low switches having a first voltage rating of half of the rated voltage of the system, and with Gallium Nitride (GaN) transistors rated to block a full rated voltage of the system used for the middle switches. A delay driver synchronizes timing between two different solid-state switches by energizing control terminals at different rates. The inverter can be operated using near-state pulse-width modulation (NSPWM) to reduce switching losses.

Abstract: A multilevel power converter, or inverter, for converting a direct current electrical power to an alternating current electrical power includes one or more 2-level converters each including gallium nitride (GaN) transistors configured to switch two input lines to a three-phase output line. The multilevel power converter may be used in a motor drive circuit, which may provide a 3-phase AC supply. Two power converters, which may be 2-level or 3-level power converters, may be alternately switched to provide the AC power to an AC motor by an output stage including bi-directional switching transistors configured to switch a corresponding three-phase output lines from the multilevel power converters. The multilevel power converters switch input lines from a neutral-point clamped input stage including capacitors connected in series across input terminals having a DC voltage therebetween to energize a midpoint terminal with an intermediate voltage half of the voltage between the input terminals.

Abstract: A motor drive for providing AC power to an electric motor includes a DC bus and three output terminals for connection to the electric motor. A positive switch selectively connects a positive conductor of the DC bus with each of the output terminals and a negative switch selectively connects a negative conductor of the DC bus with each of the output terminals. Each of the switches are Gallium Nitride (GaN) power switches. A controller commands each of the switches at a high switching speed between 10 kHz and 100 kHz using pulse width modulation to approximate an AC waveform on each of the output terminals. A dead time between activation of corresponding two of the switches conn to be selected to minimize a fifth-order harmonic distortion current.

Abstract: A seamless power transfer apparatus comprising a solar grid and a utility power grid. The apparatus comprises a smart switch electrically connected to the solar grid and to the utility grid. The smart switch does not allow the solar grid to supply power to the utility power grid at any time.