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.

Abstract: A permanent magnet assisted synchronous reluctance machine includes a stator that includes a plurality of electrical conductors radially disposed on the stator. The permanent magnet assisted synchronous reluctance machine also includes a rotor that includes a body having an outer diameter corresponding to an inner diameter of the stator and a plurality of recesses disposed on a surface of the rotor. The permanent magnet assisted synchronous reluctance machine also includes at least one ferrite magnet disposed in a corresponding recess of the rotor.

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: 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 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: An LLC power converter comprises a switching stage and a resonant tank, the switching stage configured to switch an input power at a switching frequency to apply a switched power to the resonant tank, and the resonant tank includes a resonant inductor, a resonant capacitor, and a parallel inductance. A transformer has a primary winding connected to the resonant tank and a secondary winding. A synchronous rectifier (SR) switch is configured to selectively switch current from the secondary winding to supply a rectified current to a load. An RC filter includes a filter capacitor and a filter resistor connected across the SR switch, with the filter capacitor defining a filter capacitor voltage thereacross. A rectifier driver is configured to drive the SR switch to a conductive state in response to the filter capacitor voltage being less than a threshold value.

Abstract: An inductor-inductor-capacitor (EEC) power converter with high efficiency for Electric Vehicle (EV) on-board low voltage DC-DC chargers (LDC) is disclosed. The converter includes a switching bridge with a plurality of bridge switches and configured to generate an output from a direct current input voltage. An EEC tank circuit is coupled to the switching bridge and includes a resonant inductor and a resonant capacitor and a parallel inductor connected between the resonant inductor and the resonant capacitor. The tank circuit is configured to output a resonant sinusoidal current from the output of the switching bridge. At least one transformer has at least one primary winding in parallel with the parallel inductor of the inductor-inductor-capacitor tank circuit and at least one secondary winding. At least one rectifier is coupled to the at least one secondary winding and is configured to output a rectified alternating current.

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 coldplate for removing heat from one or more heat sources, such as power electronics devices, includes a baseplate including a first surface in thermally-conductive communication with the heat sources. The baseplate includes a second surface opposite the first surface to transfer heat into a cooling fluid in contact therewith. The second surface includes a peripheral flange surrounding a central region having a plurality of parallel ribs, which increase the surface area to improve heat transfer from the baseplate and into the fluid. A housing abuts the peripheral flange of the baseplate to define a cooling passage for circulation of the cooling fluid. A jet-array plate subdivides the cooling passage into a supply header and a main channel and defines a plurality of orifices to convey the fluid into the main channel and to direct the fluid toward predetermined zones on the baseplate.

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 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.