Abstract: A circuit for providing a current through a load includes a first bridge circuit connectable to the load. The first bridge circuit selectively applies a voltage across the load. A second bridge circuit is connected to the first bridge circuit and is connectable to a power supply. The second bridge circuit selectively applies voltage to terminals of the first bridge circuit.

Abstract: A system and method for controlling energization of an electric motor (rotating or linear). The system and method includes producing a pulse-width modulated command signal to control switching devices that connect the motor to an energization source. A pulse-width modulated duty cycle value is formed as a function of the pulse-width modulated command signal. A leading current with respect to the phase angle of the back EMF is provided to the motor as a function comparing the pulse-width modulated duty cycle value with a selected threshold.

Abstract: A high-speed constant-horsepower motor includes a rotor and a stator having a plurality of groups of windings which are separately driven. In one mode of operation, the polarity of the voltage applied to each winding is such that the windings behave as distinct electromagnets, each defining a separate magnetic pole. In another mode of operation, the polarity of voltage applied to some of the windings is reversed, such that pairs of adjacent windings behave as single electromagnets. In the latter mode, the effective number of magnetic poles is reduced by a factor of two. Thus, the effective number of magnetic poles of the motor can be varied electronically, even while the motor is operating. The invention makes it possible, in one example, to operate the motor as an eight-pole motor at low speeds, and as a four-pole motor at high speeds. The effective motor constants are changed appropriately from eight-pole to four-pole modes.

Abstract: Windings for an electric motor are formed by depositing successive layers of conductive material and etching into the conductive material with a precisely-controlled high-energy beam. A computer stores information on the exact structure of the monolith of windings to be built, in the form of a series of successive planar cross-sections of the monolith. In making the monolith, one deposits a layer of conductive material onto a workpiece, bonds the conductive material to the workpiece, and cuts a pattern into the layer, using a high-energy beam in the presence of an oxidizing atmosphere. The beam causes the formation of electrically-insulating oxides which separate the layer into distinct conductive regions, according to a pattern defined by one of the stored cross-sections. In an alternative, one can also inject additional insulating material into the cuts formed by the beam. The monolith is thus built up, layer by layer, in a series of iterations.

Abstract: A pulse-width modulated (PWM) circuit alternately applies voltage from a power supply across a load, and alternately establishes one or more non-powered, closed paths for freewheeling current. The circuit includes pairs of switches connected to the load and also connected to the power supply. PWM signals derived from a command signal drive the switches in such a manner as to create the freewheeling current paths in a desired pattern and sequence. The circuit effectively reduces ripple current in the load while also substantially reducing the amount of current flowing through the power supply filter capacitor. Thus, the size and rating of the power supply can be reduced. One can use the invention to drive a load in a multiple-phase environment, and also in the context of a three-phase trapezoidal drive.

Abstract: A pulse-width modulated (PWM) circuit provides current through a load by opening and closing main electronic switches which connect the load to a power supply. Each main electronic switch connects with an auxiliary switch, connected in series with a diode, the auxiliary switch and diode being called "recovery paths". The recovery paths provide a path between the load and the associated main switch, on one side, and the power supply on the other. A first train of pulses, derived from a command signal, drives the main switches, and a second train of pulses, derived from the first pulse train, controls the switches in the recovery paths. One arranges the second train such that the recovery paths carry current only while the main switches change from on to off, or from off to on. In this way, the recovery paths carry part of the current that would otherwise flow transiently through the main switches, due to the inherent inefficiencies in semiconductor switching.

Abstract: A pulse-width modulated (PWM) circuit provides current through a load by opening and closing main electronic switches which connect the load to a power supply. Each main electronic switch connects with an auxiliary switch, connected in series with a diode, the auxiliary switch and diode being called "recovery paths". The recovery paths provide a path between the load and the associated main switch, on one side, and the power supply on the other. A first train of pulses, derived from a command signal, drives the main switches, and a second train of pulses, derived from the first pulse train, controls the switches in the recovery paths. One arranges the second train such that the recovery paths carry current only while the main switches change from on to off, or from off to on. In this way, the recovery paths carry part of the current that would otherwise flow transiently through the main switches, due to the inherent inefficiencies in semiconductor switching.

Abstract: A pulse-width modulated (PWM) circuit alternately applies voltage from a power supply across a load, and alternately establishes one or more non-powered, closed paths for freewheeling current. The circuit includes pairs of switches connected to the load and also connected to the power supply. PWM signals derived from a command signal drive the switches in such a manner as to create the freewheeling current paths in a desired pattern and sequence. The circuit effectively reduces ripple current in the load while also substantially reducing the amount of current flowing through the power supply filter capacitor. Thus, the size and rating of the power supply can be reduced. One can use the invention to drive a load in a multiple-phase environment, and also in the context of a three-phase trapezoidal drive.

Abstract: A pulse-width modulated (PWM) circuit applies a voltage across a load in accordance with a PWM command signal. The command signal is converted into first and second trains of pulses, by electronically comparing the command signal with a triangular dither signal and also with the dither signal whcih has been shifted by half its period. These two pulse trains, and two more pulse trains obtained by taking the complements of the original pulse trains, are applied to a pair of bridge circuits. The load is connected to both bridge circuits. Both bridge circuits include electronic switching devices actuated by the pulses. The bridge circuits are configured such that when a pulse is present, from either the first or the second pulse train, no net voltage appears across the load. At all other times, substantially the entire power supply voltage is applied across the load. In another embodiment, one or more additional pairs of bridge circuits are connected across the load.

Abstract: A pulse-width modulated circuit applies a voltage across a load in accordance with a command signal. The command signal is converted into first and second trains of pulses, by electronically comparing the command signal, and its inverse, with a triangular dither signal. These two pulse trains, and two pulse trains obtained by taking the complements of the original pulse trains, are applied to a pair of bridge circuits. The load is connected to both bridge circuits. Both bridge circuits include electronic switching devices actuated by the pulses. The bridge circuits are configured such that when a pulse is present, from either the first or the second pulse train, no net voltage appears across the load. At all other times, substantially the entire power supply voltage is applied across the load.

Abstract: The invention provides a method and apparatus for determining the angular displacement of a rotating shaft, and for commutation of a brushless motor. At least two analog sensors, mounted near the shaft, generate phase-displaced analog signals responsive to the angular position of the shaft. A logic circuit produces a digital code indicating the region of the cycle in which the shaft is instantaneously located. An analog multiplexor selects a unique pair of analog signals from the group of the original analog signals and their analog complements, according to the value of the digital code. An analog to digital converter then generates a digital signal proportional to the quotient of the analog signals produced by the multiplexor, and this digital signal, together with the digital code, is used to activate an address in a memory device. The memory device, such as an EPROM, is programmed with a large number of binary digits, which define a train of pulses.

Abstract: An apparatus for use with an amplifier regulates the current through a load according to a drive signal having first and second states and comprises switchless sensing means and polarity correction means. The switchless sensing means provides a sense signal continuously representative of the magnitude of the current through the load without the use of switching circuitry. The polarity correction means is directly coupled to the sensing means and receives the sense signal and is responsive to the status of the drive signal for providing an analog signal continuously representative of both the instantaneous magnitude and polarity of the current through the load.