Emerson Electric Company

Emerson Motor Co.

J Stephen Thorn

Joseph Gerald Marcinkiewicz

Bret S Clark

Gregory M Levine

Darko Marcetic

Vinod Sadasivam

James L Skinner

Arthur E Woodward

Ralph D Furmanek

Craig J Nordby

David E Gee

A system and method of determining the temperature of a rotating electromagnetic machine, such as an electric motor or generator. A temperature calibration parameter is calculated based on the temperature of an object situated close to the motor, such as a motor drive connected to the motor, and a first resistance value of the winding. In exemplary embodiments, the motor drive and first resistance value are determined only after the motor has been idle for some predetermined time period. Once the calibration parameter is calculated, the processor uses it along with subsequent resistance measurements to calculate the temperature of the motor.

Device and method of sensing temperature of a rotating electromagnetic machine

Device and method for sensing temperature of a rotating electromagnetic machine

A motor control system creates a rounding effect on square wave phase currents which results in reduced acoustic noise. The control system includes a voltage source for providing a DC bus current, and an inverter. The inverter has a switching circuit for regulating the DC bus current to a fixed level. The switching circuit also forces consecutive phases of the motor to share the bus current at commutation. Forcing consecutive phases of the motor to share a desired amount of the DC bus current creates a &ldquo;rounding&rdquo; effect on the phase currents, which results in reduced acoustic noise. The preferred inverter has a plurality of transistors, and a control module. The control module selectively engages the transistors such that each phase of the motor has a phase turn-on point that occurs before a phase turn-off point of a preceding phase. The control module also pulse width modulates the transistors such that the DC bus current is regulated to the fixed level. The result is a motor control system and method that is less expensive and produces less acoustic noise than conventional noise.

BLDC motor noise reduction using constant bus current control commutation

A method and device for driving a clothes washing machine motor at a predetermined speed is presented. The washing machine motor, which may be an AC induction motor, is powered by a DC to AC inverter that includes a DC bus. The DC bus current is measured and the inverter output frequency is adjusted in response to the DC bus current measurement. In exemplary embodiments, measuring the DC bus current includes measuring the voltage drop across a resistor coupled to the DC bus. The frequency adjustment may be calculated by multiplying the DC bus current by a compensation factor to calculate a frequency adjustment value. Alternatively, frequency adjustment values may be stored in a look-up table, and the measured DC bus current is used to index the look-up table.

Washing machine motor control device and method

A device and method for providing three-phase pulse-width modulated sine waves includes an inverter including first, second and third legs, and first and second PWM generators, the first PWM generator is coupled to selectively provide an output to the first inverter leg or the third inverter leg, and the second PWM generator is coupled to selectively provide an output to the second inverter leg or the third inverter leg. The first PWM generator provides an output to the first inverter leg during first and second 120.degree. segments of a 360.degree. electrical cycle, and the first PWM generator provides an output to the third inverter leg during a third 120.degree. segment. The second PWM generator provides an output to the third inverter leg during the first 120.degree. segment, and the second PWM generator provides an output to the second inverter leg during the second and third 120.degree. segments, thus providing generation of three-phase pulse-width modulated sine waves using fewer than three pulse-width modulators.

Device and method for generating three-phase sine waves using two

Air handling apparatus (10) delivers a volume of air at a generally constant flow rate regardless of changes in the operating conditions of a system with which the apparatus is used. A blower (12) pushes air from one point to another. The blower is operated by a blower motor (14). A switch (16) controls application of power to the motor. Sensors (20) are used to sense the current drawn by the motor and the motor's operating speed. A flow controller (22) establishes a desired air flow rate to be provided by the blower. A processor (18) is responsive to the sensed current (I), motor speed (S), an input (C) from the flow controller, and constants (K1-K4) related to performance characteristics of the blower to determine a torque required by the motor to produce a predetermined air flow rate. The torque value is determined as a function of the combined motor speed input from the sensor and an input from the flow controller. The processor is responsive to the calculated torque value for the motor to supply a control signal to the switch to control application of a voltage to the motor. This voltage is sufficient for the motor to produce the calculated torque. The processor includes signal logic (28) by which the control signal can be modified first in response to the sensed current drawn by the motor.

Constant air flow control apparatus and method

A BPM or SRM electric motor (M) is supplied bus current. A PWM inverter (I) uses bus current to commutate the motor by Systematically energizing and de-energizing the motor's windings (W) with the current. The resultant bus current waveshape has characteristics that are a function of a commutation angle between a rotor (T) of the machine and its windings. The waveshape includes the effects of bus ripple or transients. A commutation controller (10) samples the waveshape during each commutation interval to obtain commutation angle information. The controller provides control inputs to an inverter (I) to control commutation angle in response to the sample information. Commutation angle control includes calculating a control variable (I.sub.curve) which is a function of commutation angle. This variable is comprised of sampled data values which are additively combined according to a prescribed formula and which provide a high degree of linearity over a wide range of commutation angles. The controller is further responsive to the motor's impulse response (H.sub.motor (t)) to reject bus ripple effects on the waveshape samples. By employing the control variable and impulse response, the controller provides appropriate frequency (f.sub.out) and voltage (V.sub. out corrected) inputs to the inverter to achieve an optimum commutation angle relationship between the rotor and windings.

Sensorless commutation controller for a poly-phase dynamoelectric machine

A control system for a multi-phase brushless permanent magnet motor has circuitry for periodically generating signals representing the relative position of the rotor with respect to the stator, circuitry for decoding the periodically generated signals to determine the presence of the rotor at one of a plurality of predetermined rotary positions with respect to the stator, and circuitry for generating an interrupt signal in response to the presence of the rotor at one of the plurality of predetermined rotary positions with respect to the stator. Electrically controllable switches are connected to the phase windings to control the flow of current therethrough. A microprocessor is responsive to the interrupt signal for controlling in a closed loop manner the switches to commutate the phase windings of the motor a predetermined time after receipt of the interrupt signal. The microprocessor is also responsive to the speed of the motor to start the motor in a open loop mode and to shift commutation to the closed loop mode once the motor reaches a predetermined speed.

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Florissant, MO, United States of America

J Stephen Thorn