Abstract: A passively clamped quasi-resonant DC link ("PCQRL") converter includes an output inverter having a plurality of switches, and a DC link between a DC power source and the output inverter. The DC link is realized by a clamp transformer having a clamp factor not higher than 1.1-1.3 and a small auxiliary inductance which is switched by a pair of auxiliary switches (driven by the same gating signal) and a pair of diodes. When the auxiliary switches are turned "ON", the DC link voltage drops to zero; and the switches of the output inverter then can be switched under zero voltage condition with no switching losses. Most of the modulation schemes, including PWM, are applicable to the DC link design.

Abstract: A new class of doubly-salient motors which incorporate a specific stator/rotor pole arrangement and stationary permanent magnets mounted in the stator to provide a linearly increasing flux linkage over the entire area of pole overlap. The new motors provide greater output torque, higher efficiency, quicker response, and a simpler structure in comparison to conventional reluctance motors.

Abstract: A permanent magnet machine combines both principles of variable reluctance machines and permanent magnets, and comprises a rotor with salient rotor poles and a stator with salient stator poles. A pair of ferrite arched permanent magnets are embedded in the stator yoke beneath respective stator poles and are arranged symmetrically around the central axis of the machine. A field winding for boosting or weakening the primary flux generated by the permanent magnets is wound in a special arrangement.

Abstract: A new class of doubly-salient machines which incorporates a specific stator/rotor pole arrangement to provide a linearly increasing flux linkage over the entire area of pole overlap, and either (1) stationary permanent magnets mounted in the stator, or (2) one or more auxiliary field windings coiled about the stator or (3) a combination of stationary permanent magnets and auxiliary field windings. In each of the three cases, the permanent magnets or auxiliary winding(s) generate the primary flux and block and thereby limit flux in the ordinary path of the secondary flux (due to the stator windings) through the stator. The altered magnetic structure utilizing four stator and six rotor poles increases efficiency when operated as a generator, and provides greater output torque when operated as a motor.

Abstract: This invention provides cost-effective suppressing conducted radio-noise emissions from industrial inverter-motor drives whose EMI performance is able to meet the CISPR or FCC limits on conducted emissions. The invention includes some small size L,C filtering elements built inside the inverter, e.g., two grounding capacitance connected from both side of DC link to grounding heat sink of devices, a line capacitance across a DC link, three line capacitances across phase leads in AC input side of the diode rectifier, a zero sequence inductance both in each phase input and in each phase output lead of the inverter. Optionally, an extra secondary winding of the zero sequence inductor is connected to main circuit of inverter via a L, R, C network.

Abstract: A four pole induction machine with an extended speed range includes a stator with six independent stator coil groups (a pair of said coil groups constitutes a stator phase winding) and two current regulated inverters. Each of the inverters supplies currents to three said stator coil groups belonging to three different phases. The induction machine is operated in two operation modes: as a four pole machine, when both inverters supply currents of identical polarity, and as a two pole machine, when the polarity of currents supplied by one inverter is reversed in respect to the polarity of currents supplied by another inverter. The switching from the four pole operation mode to the two pole operation mode takes place during a constant power operation of the induction machine.

Abstract: An inverter-driven induction motor system having input lines (12,14,16) for receiving a three-phase ac input signal which is converted into a dc signal and transmitted on dc bus lines (24,26) before gated into a three-phase alternating current output signal transmitted to the motor on output lines (34,36,38). A four winding common mode inductance (L1) is connected on the output side with an inductance connected to the motor ground wire (42). A ground wire choke (Lg) is also added to further reduce conducted emitted radio frequency noise or interference. A third order filter and grounding capacitance (C14,C15,C16) are further added to the ac input side to improve EMI performance.

Abstract: Methods and apparatus are provided wherein air gap fundamental flux magnitude and relative position are determined from stator voltage third harmonic components and stator current in operating alternating current machines having a stator, a rotor and an air gap therebetween. Such determinations have various uses, such as for efficiency control.

Abstract: A variable reluctance drive system including a motor and corresponding converter for improved current commutation is described. The motor incorporates a salient pole rotor and a salient pole stator having one or more full pitch windings which operate by mutual inductance to transfer the current from the active short pitch winding following phase alignment. This increases output torque and/or speed and permits a number of simple and economical converter circuits.

Abstract: A device for field weakening in a doubly-salient variable reluctance motor having permanent magnets in the stator. The field weakening increases the constant power range of the motor and is accomplished by controlled movement of steel insets toward and away from the sides of the stator proximate the permanent magnets to provide a controllable by-pass flux path thereabout. Alternatively, the field weakening may be accomplished by a flux by-pass collar which may be angularly positioned around the stator to bridge the permanent magnets of the motor with discrete magnetic sections, thereby providing an alternate by-pass flux path around the permanent magnets in addition to the main air gap flux path. A third alternative means for maintaining a constant power range is accomplished by controlled axial sliding of the permanent magnets themselves into and out from the stator.

Abstract: A discrete position sensor elimination technique for a sinusoidally wound synchronous reluctance motor drive uses induced voltage, phase currents, and excitation frequency to estimate rotor position at all speeds, including zero speed.

Abstract: A variable reluctance drive system including a motor and corresponding converter for improved current commutation is described. The motor incorporates a salient pole rotor and a salient pole stator having one or more full pitch windings which operate by mutual inductance to transfer the current from the active short pitch winding following phase alignment. This increases output torque and/or speed and permits a number of simple and economical converter circuits.

Abstract: A method and apparatus for controlling torque by correcting slip gain error in an operating induction motor is provided. This is accomplished by measuring the amplitude and position of a flux in the motor such as rotor flux. Rotor flux position and amplitude can be estimated from the air gap flux. The slip gain can then be corrected in a single step or a few steps to provide a deadbeat control.

Abstract: A new class of doubly-salient variable reluctance motors which provides greater output torque, higher efficiency, quicker response, and a simple structure in comparison to conventional reluctance motors by utilizing a specific stator/rotor pole arrangement and by altering the magnetic structure of the motor by using permanent magnets to provide a linearly increasing flux linkage over the entire area of pole overlap.

Abstract: Methods and apparatus are provided wherein air gap flux magnitude and relative position are determined from stator voltage harmonic components and stator current in operating alternating current machines having a stator, a rotor and an air gap therebetween. Such determinations have various uses, such as for efficiency control. Various new and improved efficiency controllers are provided which utilize these measurements.

Abstract: A high power density reluctance motor which is adapted to be supplied with unidirectional power from a converter has a multiphase stator with concentrated full pitch windings and multiple poles. The rotor has segments which constitute flux guides which serve to bend the flux produced by current flowing in a coil winding in a slot of the stator around the slot and back toward the periphery of the rotor, providing maximum inductance when a flux guide of the rotor is aligned with each such slot. Minimum inductance occurs when the flux guides are out of alignment with the slot conducting current and aligned with an adjacent slot, with a substantially linear change in inductance occuring with rotor displacment.

Abstract: A high efficiency power converter is achieved which eliminates the needs for self-commutated devices and requires only twelve thyristors for full double bridge AC/AC power conversion. The system utilizes a series resonant DC link between the AC/DC and DC/AC converters. The DC resonant circuit functions as a commutating circuit which ensures turn off of all twelve thyristors by providing the necessary zero current instants. A significantly improved sinusoidal current waveform can be obtained on both the input and the output compared to conventional high power converters by the use of high frequency pulse density modulation.

Abstract: To determine the flux in the air gap of an electrical machine having distributed stator windings, the voltages across two coils of a phase belt in certain phases of the stator are measured and the voltage across one coil in each phase belt is subtracted from the voltage in the other coil. The voltage differences are integrated to provide a measure of the air gap flux. Measurement of the entire air gap flux about the machine can be obtained utilizing two coils in a phase belt per phase of the machine. The instantaneous electromagnetic torque in the machine can be calculated directly as a function of the calculated air gap flux and of the currents in the stator windings. Such flux and torque measurements are obtained utilizing electrical connections to the existing coils of the machine, without the need to modify the machine by adding further windings or sensors. The flux and torque signals so obtained may be utilized in motor controllers, and are particularly useful for control of AC induction motors.

Abstract: An electrical machine is disclosed, capable of functioning as either a motor or generator, which has a salient pole rotor (23) and a stator having multiple phase windings (21) each comprising a concentrated, full pitch winding with one stator slot per pole per phase. The pole faces (27) of the salient poles of the rotor may be tapered to produce an air gap which increases from the front to the back of the pole face to counter the effect of armature reaction MMF. The taper of the pole faces is selected such that the resultant total flux density in the air gap from field and armature currents is quasi-rectangular. The quasi-rectangular flux densities rotating in the air gap produce quasi-rectangular phase voltages and currents when the machine is operated as a generator, and, when operated as a motor, the machine is adapted to accept quasi-rectangular supply currents or voltages of the type readily produced by variable frequency converter power supplies.

Abstract: A drive system for a polyphase induction motor for extending the range of high frequency operation has two current source inverters connected to the polyphase motor to supply power to the motor. Motor speed and motor load are sensed and a circuit responsive to increasing motor speed and decreasing motor loads advances the firing pulses of one inverter while delaying the firing pulses of the other inverter. The advance in firing of one inverter and the delay in firing the other, reduces the effective current supplied to the motor while not decreasing the current available in each inverter for commutation.