Emerson Electric Company

Pradeep K Sood

Douglas M Petty

James L Skinner

Benjamin Bowsky

Jerry D Lloyd

Bernard T Brown

John S Thorn

Marco Venturini

Craig J Nordby

Ciaran O'Breartuin

A dynamoelectric machine, for example, a brushless permanent magnet motor (M) has a plurality of stator windings (S) and a rotor (T) which rotates with respect to the windings. Apparatus (10) is provided for controlling winding commutation with respect to the rotor. A DC bus (14) supplies current to the windings. The current waveshape has characteristics which are a function of the commutation angle with respect to the windings. Current magnitude and waveshape are sensed by a sensing unit (22) and the sensed waveshape is sampled to obtain commutation information. An inverter (20) successively energizes and de-energizes the respective stator windings. A controller (26) obtains samples of the waveshape, and processes the information obtained by the sampling to control winding commutation. The controller controls the inverter operation to provide a commutation angle which optimizes motor performance and efficiency for a particular set of motor operating conditions. To do this, the processor evaluates slope and amplitude information from the sampled DC bus current waveshape, determines if the waveshape corresponds to a desired waveshape representing a desired commutation angle, and adjusts the commutation frequency produced by the inverter, if necessary, to obtain the desired waveshape.

Method and apparatus of operating a dynamoelectric machine using DC bus

A drive system for a household appliance incorporates an electric motor. A control panel allows the user of the appliance to select from among various performance options which the appliance is able to perform. A microprocessor, functioning as a first control unit, is responsive to the selections and to various appliance sensors monitoring operational status of the appliance to control the operation of various components within the appliance by which the selected options are performed. An AC-DC converter and inverter supply electrical power to the motor. A second control unit, operating at a relatively faster rate of speed than the microprocessor, controls the supplying of power to the electric motor to achieve proper operation thereof.

Drive system for household appliances

A high power-factor converter (50) for use with motor drives and power supplies. A first and 'buck'-type converter section (62) is connected to an a.c. voltage source. This section provides an output voltage having preselected voltage characteristics. This section is operational during that portion of an input voltage cycle in which the input voltage level exceeds that of the output voltage level. A second and 'boost'-type converter section (70) is also connected to the voltage source. This second section also provides the output voltage, and is operational during that portion of the input voltage cycle in which the output voltage level exceeds that of the input voltage level. A control circuit (66) is responsive to the relative levels of the input and output voltages to operate the first and second converter sections on a time sharing basis in which converter operation is switched between the two converter sections as a function of the sensed actual output voltage characteristics compared to the preselected characteristics. This permits the converter to maintain a nearly full conduction angle, and therefore a high power factor, for any level of output voltage in a range from zero volts to voltage levels higher than the peak input voltage level.

High power-factor converter for motor drives and power supplies

A field installable device for a conventional heating and air conditioning system (HVAC) is provided which operates a blower fan in conjunction with a standard thermostat. Presently, HVAC systems operate in four modes: heating, cooling, off and fan 'on'. The device includes a multi-pole, multi-speed motor and a control operatively connected between the thermostat and the motor. With the fan switch in the 'on' position and heating or cooling called for, the control causes the blower to operate at a high speed, which may be different for heating or cooling. When the pre-selected temperature is reached the particular thermal operation (i.e., heating or cooling) is stopped. The control switches the motor to a speed substantially slower than the operating condition speed to provide continuing air circulation until the thermostat again calls for thermal operation. With the switch in 'auto' position, the blower operates similarly to present systems.

HVAC low power usage circulation blower

Power conversion apparatus (10) for an n-winding switched reluctance motor (M). A rectifier circuit (12) rectifies line voltage supplied to the motor. A switching circuit (14) supplies, at any one time, electrical energy to the motor winding most capable of converting it to mechanical work. A storage capacitor (C1) stores any unconverted portion of the energy and returns it to the winding during subsequent cycles. The switching circuit provides a substantially long conduction period 2 (.theta.) for supplying electrical energy to the motor during each line voltage cycle. This permits use of a substantially smaller energy storage capacitor and results in a higher input power factor for circuit operation. Circuits for precharging the storage capacitor are eliminated. The switching circuit is capable of more modes of operation than previous circuits, while using fewer components, and therefore provides a lower cost design.

Power converter for a switched reluctance motor

Load unbalance in an inverter driven washing machine is detected by examining the ripple in the DC inverter bus current. Ripple above a predetermined level is indicative of load unbalance. If the ripple indicates the load is unbalanced, the distribution cycle of the washing machine is attempted again in an attempt to more nearly balance the clothes. After a certain number of tries, if the load is still unbalanced the spin cycle is aborted. If the ripple falls below a predetermined level before the maximum number of tries is reached, the spin cycle is started. The frequency of operation is checked during the spin cycle to adjust the cycle time to the particular degree of load balance achieved.

Unbalanced load detection system and method for a household appliance

A washing machine has a rotatable drum for holding items being washed and water for washing the items. The number of items in the drum and the amount of water in the drum may vary. Power is supplied from an inverter to a motor which rotates the rotatable drum. A speed control responsive to the inverter current regulates the drum rotating speed within a selected range.

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St. Louis, MO, United States of America

Pradeep K Sood