Abstract: A single phase permanent magnet motor includes a rotor, a stator, and a quadrature axis winding positioned out-of-phase from a main winding of the stator for generating an output signal representative of rotor angular position. An integrator can be coupled to the quadrature axis winding for phase retarding the output signal, and a comparator can be coupled to the integrator for detecting zero crossings of the phase retarded output signal to provide a commutation signal. The quadrature axis winding can be positioned about ninety electrical degrees out-of-phase from the main winding of the stator, and the integrator can be adapted to phase retard the output signal by a number of degrees which decreases as a speed of the motor increases. At low speeds the phase retard is preferably at about ninety degrees so that the phase retarded signal becomes in-phase with the main stator winding back EMF voltage.

Abstract: A capacitively powered motor having a power switching circuit adapted to be connected between a power source and its winding for selectively energizing the winding to generate a magnetic field which causes a rotating assembly to rotate. A position sensing circuit provides a position signal representative of the position of the rotating assembly and a commutating circuit controls the power switching circuit to commutate the power switching circuit at a commutating angle and at a substantially constant duty cycle to achieve a desired rotating speed of the rotating assembly. The commutating circuit varies the commutating angle in response to the position signal to maintain the substantially constant rotating speed of the rotating assembly. As result, the efficiency of the motor is varied to maintain the substantially constant rotating speed.

Abstract: A motor having a power switching circuit adapted to be connected between a power source and its winding for selectively energizing the winding to generate a magnetic field which causes a rotating assembly to rotate. A position sensing circuit provides a position signal representative of the position of the rotating assembly and a commutating circuit controls the power switching circuit to commutate the power switching circuit at a commutating angle to achieve a desired rotating speed of the rotating assembly. The commutating circuit varies the commutating angle in response to the position signal to maintain the substantially constant rotating speed of the rotating assembly. As result, the efficiency of the motor is varied to maintain the substantially constant rotating speed.

Abstract: A single phase permanent magnet motor includes a rotor, a stator, and a quadrature axis winding positioned out-of-phase from a main winding of the stator for generating an output signal representative of rotor angular position. An integrator can be coupled to the quadrature axis winding for phase retarding the output signal, and a comparator can be coupled to the integrator for detecting zero crossings of the phase retarded output signal to provide a commutation signal. The quadrature axis winding can be positioned about ninety electrical degrees out-of-phase from the main winding of the stator, and the integrator can be adapted to phase retard the output signal by a number of degrees which decreases as a speed of the motor increases. At low speeds the phase retard is preferably at about ninety degrees so that the phase retarded signal becomes in-phase with the main stator winding back EMF voltage.

Abstract: A motor includes a stationary assembly and a rotatable assembly in magnetic coupling relation thereto. The stationary assembly includes a winding, the rotation of the rotatable assembly inducing a back EMF in the winding. A power supply for supplying a voltage across the winding drives a current through the winding. A back EMF sensor connected to the winding generates a back EMF signal representative of the back EMF induced in the winding during periods of time when the voltage is being supplied across the winding. An inverter connected between the power supply and the winding commutates the winding as a function of the back EMF signal, whereby the rotatable assembly rotates. A method of operating the motor and a control circuit for the motor employ the back emf induced in the winding during periods when the voltage is being applied to the winding by the power supply.

Abstract: An apparatus for driving a fan as part of a refrigerator is disclosed. The refrigerator has a compartment, a compressor, an evaporator and a condenser. A temperature sensor is positioned in association with the compartment and outputs a sensed temperature signal as a function of the temperature in the compartment. The apparatus includes a reference circuit which provides a desired temperature signal representative of a desired temperature. A comparator compares the desired temperature signal and the sensed temperature signal and generates a cool signal when the compartment temperature is above the desired temperature. A timer times out an elapsed period of time commencing when the cool signal is generated. A motor includes a rotatable assembly in driving relation to the fan. A control circuit controls operation of the motor as a function of the sensed temperature signal and the elapsed period. Related apparatus and methods are also disclosed.

Abstract: A motor having a differential phase back EMF sensing circuit for sensing rotor position includes a stationary assembly with at least three windings. The rotation of the rotor induces a back EMF in the windings. A control circuit energizes each of the windings with a current according to a preselected sequence. A switch network is coupled to the windings and provides two back EMF signals as a function of the back EMF induced in two of the windings when the control circuit is energizing the third winding. A signal processor is coupled to the switch network and produces a difference signal representative of a difference between the two back EMF signals. An integrator integrates the difference signal to produce an integrated difference signal. The motor includes a reference signal generator which produces a reference signal and a comparator which produces a trigger signal when the integrated difference signal exceeds the reference signal.

Abstract: A method of operating a brushless motor having a stationary assembly with at least two different energizable windings for producing spaced apart magnetic fields in time sequence, and a rotor adapted to rotate in response to the magnetic fields. The method includes the steps of simulating rotor position in accordance with the back emf condition of at least one winding, energizing a selected one of the windings in accordance with the simulated rotor position, sensing an underspeed condition when the motor speed is less than a minimum value for a length of time, and preventing energization of any of the windings when the motor speed is less than the minimum value for the length of time. An electrically commutated motor controller apparatus controls and speed of a variable speed motor compressor driven by an electrically commutated motor. A controller circuit includes a circuit for producing feedback signals representative of a back emf of the motor.

Abstract: A method of operating a brushless motor having a stationary assembly with at least two different energizable windings for producing spaced apart magnetic fields in time sequence, and a rotor adapted to rotate in response to the magnetic fields. The method includes the steps of simulating rotor position in accordance with the back emf condition of at least one winding, energizing a selected one of the windings in accordance with the simulated rotor position, sensing an underspeed condition when the motor speed is less than a minimum value for a length of time, and preventing energization of any of the windings when the motor speed is less than the minimum value for the length of time. An electrically commutated motor controller apparatus controls the speed of a variable speed motor compressor driven by an electrically commutated motor. A controller circuit includes a circuit for producing feedback signals representative of a back emf of the motor.

Abstract: A method of operating a brushless motor having a stationary assembly with at least two different energizable windings for producing spaced apart magnetic fields in time sequence, and a rotor adapted to rotate in response to the magnetic fields. The method includes the steps of simulating rotor position in accordance with the back emf condition of at least one winding, energizing a selected one of the windings in accordance with the simulated rotor position, sensing an underspeed condition when the motor speed is less than a minimum value for a length of time, and preventing energization of any of the windings when the motor speed is less than the minimum value for the length of time. An electrically commutated motor controller apparatus controls the speed of a variable speed motor compressor driven by an electrically commutated motor. A controller circuit includes a circuit for producing feedback signals representative of a back emf of the motor.

Abstract: A control system and method for an electronically commutated motor having a stationary assembly with a plurality of winding stages for carrying a motor current in response to application of a voltage having a magnitude subject to variations, the motor further having a rotatable assembly. The control system is adapted to receive control pulses having a duty cycle which is a function of a desired operating torque or speed for the motor. The control system and method are responsive to the motor current for generating a pluse width modulated (PWM) series of pulses having a pulse repetition rate having a duty cycle which is a function of the duty cycle of the control pulses. The PWM series of pulses are supplied to the commutating circuit as a pulsed signal whereby the operating torque or speed of the motor is a function of the duty cycle of the control pulses and is substantially independent of variations in the magnitude of the applied voltage.

Abstract: A suspension system for controlling the relative position of a vehicle and a wheel assembly supporting the vehicle for travel over a surface of terrain. The system includes a member for resiliently connecting the vehicle and the wheel assembly to establish an equilibrium position therebetween in which the vehicle is supported in a predetermined position with respect to the surface of the terrain. The system further includes a dynamoelectric machine comprising a stationary assembly and a rotatable assembly magnetically coupled thereto, the stationary assembly having a plurality of winding stages adapted to be electrically energized to apply an electromagnetic field to said rotatable assembly thereby to rotatably drive the rotatable assembly about an axis. A ball screw translates rotation of the rotatable assembly driven by the stationary assembly into linear motion between the wheel assembly and the vehicle.

Abstract: Control circuit for an electronically commutated motor which has a rotatable assembly and further has a stationary assembly with a plurality of winding stages having terminals for energization, and switches for applying a voltage to one or more of the terminals of the winding stages at a time and commutating the winding stages in a preselected sequence to rotate the rotatable assembly. A preselected sequence of winding stages are left correspondingly unpowered so that a plurality of the winding stages are unpowered at some time. The winding stages generate back emf signals and also couple electrical signals from each energized winding stage to the unpowered winding stages which signals can interfere with detection of back emf for position sensing purposes. The control circuit includes a first circuit for selecting at least two of the unpowered winding stages which have electrical signals coupled to them that have a predetermined relationship in polarity and magnitude.

Abstract: A drive system for a laundry machine utilizing a switched reluctance motor of three or more phases and with stator/rotor pole ratios selected from the ratios of 6:4 and 8:6 with the actual number of poles being a multiple of 2 or more times those numbers. A stator/rotor gap of 10-20 mils is maintained in large diameter motors and cooling for the coils and electronic components positioned within the motor is provided.

Abstract: A fan motor assembly provides axial air flow. A rotatable assembly including a substantially cylindric central portion supported for rotation about an axis coaxial with said central portion. The central portion has at least one permanent magnet element which rotates about the axis as the central portion rotates. The rotatable assembly further includes fan blades on an annular wall of the central portion and extending radially outwardly from the central portion. The annular wall and the central portion form an annular channel. The blades axially move air which is located about the outer periphery of the rotatable assembly as the rotatable assembly rotates. A stationary assembly includes a support for an annular core having a central opening to receive the central portion and having winding stages thereon in magnetic coupling relation with the permanent magnet element and electrically energized to generate an electromagnetic field, the core received within the annular channel of the rotatable assembly.

Abstract: Control system for an electronically commutated motor having a stationary assembly with a plurality of winding stages and further having a rotatable assembly. The control system is adapted to be supplied with an externally derived first pulse width modulated series of pulses having a first duty cycle which is subject to sudden changes which would cause a substantial inrush current to the motor if used directly for control purposes. The control system includes circuitry for generating a second series of pulses and modulating their width in response to the first series of pulses to produce a second pulse width modulated series of pulses that has a second duty cycle which varies less rapidly over time than the first duty cycle varies when the first duty cycle changes suddenly.

Abstract: A control system for an electronically commutated DC motor having a rotatable assembly and a stationary assembly with a plurality of winding stages. The application of a DC voltage to the winding stages is controlled to provide an effective voltage thereto by commutating the winding stages to apply the DC voltage thereto in sequence to cause rotation of the rotatable assembly. A neutral conductor voltage of the motor is approximated and compared with the back emf of one of the winding stages to obtain an output representing the angular position of the rotatable assembly. The winding stages are commutated in response to this output when a predetermined angular position is reached. The DC voltage applied to the winding stages is pulse width modulated by alternately pulse width modulating first and second drive circuits.

Abstract: A method of determining torque of an electronically commutated motor arranged to drive a blower means for flowing air through a contained space with the electronically controlled motor and the blower means having a combined predetermined inertia. In practicing this method, power is applied to the electronically commutated motor, and the blower means is thereby accelerated to a predetermined speed. The power is then removed from the electronically commutated motor, and thereby the blower means is decelerated. The deceleration of the blower means is measured, and the torque of the electronically commutated motor is computed from the measured deceleration.A method of establishing a preferred rate of air flow and apparatus are also disclosed.

Abstract: A circuit for controlling the energization of an electrical load from an AC source. The circuit has a pair of DC lines, and means is provided for rectifying the AC output of the source to apply a DC voltage across the DC lines in the form of a full wave rectified sinusoidal signal. Signal switching means for connection between the DC lines and the load establishes a conductive path therebetween during a variable time interval when the voltage applied by the full wave rectified sinusoidal signal exceeds the voltage across the load, and means including the switching means is provided for chopping the full wave rectified sinusoidal signal to apply pulses to the load during the variable time interval at a frequency which is high with respect to the frequency of the signal.

Abstract: A control system and method for an electronically commutated motor having a stationary assembly with a plurality of winding stages for carrying a motor current in response to application of a voltage having a magnitude subject to variations, the motor further having a rotatable assembly. The control system is adapted to receive control pulses having a duty cycle which is a function of a desired operating torque or speed for the motor. The control system and method are responsive to the motor current for generating a pluse width modulated (PWM) series of pulses having a pulse repetition rate having a duty cycle which is a function of the duty cycle of the control pulses. The PWM series of pulses are supplied to the commutating circuit as a pulsed signal whereby the operating torque or speed of the motor is a function of the duty cycle of the control pulses and is substantially independent of variations in the magnitude of the applied voltage.