Abstract: A method and system for online monitoring and compensation of inter-turn short circuit faults (ISF) in windings of electric machines, such as permanent magnet synchronous motors is provided. A method for characterizing an ISF in a winding of an electric machine comprises: measuring phase voltages and currents; calculating sequence components of the electric machine based on the phase voltages and currents; determining a ratio between a percentage of shorted turns in the winding and a fault loop resistance based on the sequence components of the electric machine; and estimating characteristics of the inter-turn short circuit fault using an unscented Kalman filter. The characteristics include at least one of: a fault current, the percentage of shorted turns, or the fault loop resistance. A method for compensation an ISF in a winding of an electric machine comprises compensating the fault current based on the compensation current estimated from an unscented Kalman filter.

Abstract: An electromagnetic machine includes a stator that includes a back plate and a plurality of electrical conductors radially disposed on the back plate. The electromagnetic machine also includes a rotor that includes a body having an outer diameter corresponding to an inner diameter of the stator and at least one magnet having a first end disposed proximate the stator and a second end disposed opposite the first end. The electromagnetic machine also includes an engaging member disposed on a shaft that extends axially relative to the rotor, the engaging member being configured to engage at least one recessed portion of the rotor.

Abstract: A method for state-of-health monitoring of a powertrain component in an electric vehicle system includes: determining an equivalent circuit model of the powertrain component; modeling heat losses in the powertrain component considering both transient and steady-state conditions; modeling heat flow through the powertrain component based on one or more material properties of the powertrain component; determining a temperature of a particular structure within the powertrain component; and determining, using a Rainflow algorithm, a number of temperature cycles until failure of the particular structure based on the temperature of the particular structure.

Abstract: An impingement cooling system includes a porous heat spreader and a nozzle configured to direct a fluid as a jet and/or as a spray impinging upon the porous heat spreader. The porous heat spreader is made of a thermally-conductive material such as a metal, metal alloy, carbon/graphite, or ceramic, and is in thermal contact with a heat source. The nozzle may be configured to direct the fluid as a jet comprising a single component liquid or gas (including air) or a liquid mixture such as water-glycol or other coolants. The nozzle may be configured to direct the fluid as a spray comprising a single component liquid or gas (including air) or a liquid mixture such as water-glycol or other coolants. The cooling system may include one or more nozzles, which may direct the cooling fluid orthogonally or at an oblique angle to an impingement plate.

Abstract: An electromagnetic machine includes a stator that includes a back plate and a plurality of electrical conductors radially disposed on the back plate. The electromagnetic machine also includes a rotor that includes a body having an outer diameter corresponding to an inner diameter of the stator and at least one magnet having a first end disposed proximate the stator and a second end disposed opposite the first end. The electromagnetic machine also includes an engaging member disposed on a shaft that extends axially relative to the rotor, the engaging member being configured to engage at least one recessed portion of the rotor.

Abstract: An impingement cooling system includes a porous heat spreader and a nozzle configured to direct a fluid as a jet and/or as a spray impinging upon the porous heat spreader. The porous heat spreader is made of a thermally-conductive material such as a metal, metal alloy, carbon/graphite, or ceramic, and is in thermal contact with a heat source. The nozzle may be configured to direct the fluid as a jet comprising a single component liquid or gas (including air) or a liquid mixture such as water-glycol or other coolants. The nozzle may be configured to direct the fluid as a spray comprising a single component liquid or gas (including air) or a liquid mixture such as water-glycol or other coolants. The cooling system may include one or more nozzles, which may direct the cooling fluid orthogonally or at an oblique angle to an impingement plate.

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: An electric machine includes a stator, a rotor configured to rotate about an axis, and a housing surrounding the rotor and the stator. The housing includes an end cap at an axial end of the electric machine. The housing encloses an end space between the rotor and the end cap. The electric machine also includes a nozzle disposed within the end space and configured to discharge a cooling fluid into the end space in a direction tangential to the rotation of the rotor. The cooling fluid may include liquid, such as oil. The electric machine may be an induction machine or a synchronous machine. The nozzle may include an inlet tube that extends through the end cap. The electric machine may include two end spaces on opposite ends of the rotor, with one or more nozzles located in each of the two end spaces.

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 multi-phase LLC power converter comprises a plurality of LLC phases each including a resonant tank and a switching stage. The resonant tank includes a resonant inductor, a resonant capacitor, and a parallel inductance. The switching stage switches an input power at an operating frequency to apply a switched power to the resonant tank, with the switched power approximating an alternating current (AC) waveform having a switching frequency. A secondary-side controller varies the switching frequency to control an output voltage of the multi-phase LLC power converter. A primary-side controller measures primary-side currents, calculates an initial switch-controlled capacitor (SCC) conduction phase angle for each of the LLC phases, and operates an SCC switch in accordance with an SCC conduction phase angle to adjust the capacitance of the resonant capacitor of an LLC phase to cause each of the LLC phases to have equal resonant frequencies.

Abstract: A rotor for a wound-field synchronous machine (WFSM) comprises a core having a base with a ring-shaped cross-section extending between an outside surface and an inside surface defining a bore. The rotor also comprises a plurality of field windings spaced apart from one another at regular angular intervals and each extending around the base of the core, adjacent the outside surface and through the bore. Rotor field windings having radial, or spoke configurations are provided. Rotor field windings having V-shaped arrangements, in which two field windings each contribute to the production of each pole, are also provided. Rotors having permanent magnets in addition to field windings are also provided.

Abstract: A power converter includes an integrated multi-layer cooling structure. The power converter includes a plurality of printed circuit boards (PCBs) stacked together in a generally vertical arrangement. A liquid cooling mechanism is attached to a lower-most PCB, and high loss circuitry components are attached to an opposite side of the lower-most PCB. Low loss circuitry components are attached to further PCBs. Magnetic components may be attached to the further PCBs. The high loss components are actively cooled by the liquid cooling mechanism and the low loss components and magnetic components are passively cooled. The liquid cooling mechanism may be a cold plate heatsink. The power converter may include intermediate PCBs disposed between the upper-most PCB and the lower-most PCB, with low loss circuitry components attached to the intermediate PCBs.

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 method and system for online monitoring and compensation of inter-turn short circuit faults (ISF) in windings of electric machines, such as permanent magnet synchronous motors is provided. A method for characterizing an ISF in a winding of an electric machine comprises: measuring phase voltages and currents; calculating sequence components of the electric machine based on the phase voltages and currents; determining a ratio between a percentage of shorted turns in the winding and a fault loop resistance based on the sequence components of the electric machine; and estimating characteristics of the inter-turn short circuit fault using an unscented Kalman filter. The characteristics include at least one of: a fault current, the percentage of shorted turns, or the fault loop resistance. A method for compensation an ISF in a winding of an electric machine comprises compensating the fault current based on the compensation current estimated from an unscented Kalman filter.

Abstract: Permanent magnet (PM) flux strength in a permanent magnet synchronous machine (PMSM) can be affected by operating conditions including thermal, mechanical, environmental and electrical stresses. Reduced flux strength, also called demagnetization, can lead to the degradation of the efficiency, performance and reliability of the machine and the drive system. A reliable PM strength, PM flux linkage, PM SOH, PM demagnetization detection method using the same inverter (i.e. motor drive) used to operate the PMSM is provided. The method comprises applying phase voltages to each of a plurality of motor leads of the PMSM with the PMSM at a stand-still condition; measuring current in each of the plurality of motor leads of the PMSM while applying the phase voltages thereto; and determining at least one of flux linkage, PM strength, PM SoH, or PM demagnetization based on a value of the current in at least one of the motor leads.

Abstract: A cooling jacket for an electric motor comprises a fluid passage disposed adjacent to a stator and configured to convey a cooling fluid. The cooling jacket includes a flow mixing enhancer within the fluid passage adjacent an axial end of the stator. The flow mixing enhancer includes baffles, a porous fibrous structure, and/or an open-cell foam to provide greater thermal conductance at a region adjacent to the axial ends than it provides to a central region therebetween. A flow bridge directs the cooling fluid through circumferential flow paths adjacent to both of the axial ends before the cooling fluid is circulated in a central flow path around the central region of the stator. One or more nozzles direct a jet of cooling fluid upon the stator end winding, a rotor end winding, and/or printed circuit board. A ring-shaped coolant header may supply the cooling fluid to the nozzles.

Abstract: A system and method for integrated charging a vehicle includes a hybrid excitation machine, operable as a traction motor and including a rotor separated by an air gap from a stator with AC windings. An AC utility line power supply is connected to the AC windings providing an electrical current to the vehicle and inducing a magnetic flux across the air gap and in the rotor. A short circuit, an open circuit, or a DC voltage may be applied to a DC winding in the stator to reduce the magnetic flux into the rotor. A field coil in the rotor may be excited with a DC voltage using a secondary coil on the rotor in a traction mode. The secondary coil is excited by the stator windings using field-oriented control in a “self-excited machine” embodiment, and is directly excited by a separate primary coil in an “externally-excited machine” embodiment.

Abstract: An impingement cooling system includes a porous heat spreader and a nozzle configured to direct a fluid as a jet and/or as a spray impinging upon the porous heat spreader. The porous heat spreader is made of a thermally-conductive material such as a metal, metal alloy, carbon/graphite, or ceramic, and is in thermal contact with a heat source. The nozzle may be configured to direct the fluid as a jet comprising a single component liquid or gas (including air) or a liquid mixture such as water-glycol or other coolants. The nozzle may be configured to direct the fluid as a spray comprising a single component liquid or gas (including air) or a liquid mixture such as water-glycol or other coolants. The cooling system may include one or more nozzles, which may direct the cooling fluid orthogonally or at an oblique angle to an impingement plate.

Abstract: A battery charger for an electric vehicle supplies DC output power to an output bus for supplying power to a battery. The battery charger includes an AC/DC converter using switches to convert AC power from an AC source to a DC link voltage upon a DC link bus. A DC link capacitor allows a ripple in the DC link voltage that is greater than in conventional charger designs. A DC/DC stage includes a DC/AC converter including one or more switches to selectively conduct current from the DC link bus to supply an AC power to a transformer. The switches of the DC/AC converter are mounted to an insulated metal substrate that is in thermal contact with a transformer housing for dissipating heat therefrom. A controller controls one or more switches of the DC/AC converter and varies a switching frequency responsive to the ripple of the DC link voltage.

Abstract: A power electronic converter supplies DC output power to an output bus for supplying a load, such as a battery. The power electronic converter includes a DC link capacitor configured to provide a DC link voltage with a ripple of 80 V peak-to-peak. The power electronic converter also includes a DC/DC stage having a DC/AC converter that includes one or more switches to selectively conduct current from the DC link bus to supply an AC power to a transformer. The switches of the DC/AC converter are mounted to an insulated metal substrate that is in thermal contact with a transformer housing for dissipating heat therefrom. A controller controls one or more switches of the DC/AC converter and varies a switching frequency responsive to the ripple of the DC link voltage.