Abstract: A method of constant airflow control includes various controls to accomplish a substantially constant airflow rate over a significant change of the static pressure in a ventilation duct. One control is a constant I·RPM control, which is primarily used in a low static pressure range. Another control is a constant RPM control, which is primarily used in a high static pressure range. These controls requires neither a static pressure sensor nor an airflow rate sensor to accomplish substantially constant airflow rate while static pressure changes. Also, the method improves the accuracy of the control by correcting certain deviations that are caused by the motor's current-RPM characteristics. To compensate the deviation, the method adopts a test operation in a minimum static pressure condition. Also disclosed is an apparatus for conducting these control methods.

Abstract: A method of constant airflow control includes various controls to accomplish a substantially constant airflow rate over a significant change of the static pressure in a ventilation duct. One control is a constant I·RPM control, which is primarily used in a low static pressure range. Another control is a constant RPM control, which is primarily used in a high static pressure range. These controls requires neither a static pressure sensor nor an airflow rate sensor to accomplish substantially constant airflow rate while static pressure changes. Also, the method improves the accuracy of the control by correcting certain deviations that are caused by the motor's current-RPM characteristics. To compensate the deviation, the method adopts a test operation in a minimum static pressure condition. Also disclosed is an apparatus for conducting these control methods.

Abstract: The present invention can include an automated method controlling the fan speed of computer system cooling fans with altitude and/or fluid density data from a centralized sensor. Such a method can utilize a centralized sensor to determine the altitude/fluid density within an enclosed area. The centralized sensor can be positioned so as to be unaffected by extraneous activities within the enclosed area. The determined altitude/fluid density can be conveyed to a computer system containing one or more cooling fans. The computer system can be located within the enclosed area. Then, the computer system can determine the need for adjusting the speed of the cooling fans based on the altitude/fluid density. When the need for adjustment exists, the speed of the cooling fans can be adjusted in accordance with the altitude/fluid density.

Abstract: A method and apparatus for controlling the output function of a permanent magnet brushless DC motor (20), by sensing an input current to the motor (20), by computing an output torque generated by the motor (20) as a function of the input current to the motor (20), by computing an output pressure for a pump (22) in response to the output torque, by reading a set point pressure, and by comparing the set point pressure to the output pressure, and in response thereto controlling on-off operation of the motor (20). The apparatus includes a sensing circuit (28) and a microelectronic processor (30) for performing these functions.

Abstract: A method and apparatus for achieving constant air flow rate economically utilizes an induction blower motor with control settings determining the motor excitation voltage. A memory stores, for a variety of motor speeds, a graph of the speeds plotted against a proportionality constant of flow rate to fan speed for the selected motor system on one axis and motor control settings on the other axis. The only monitoring necessary to achieve the constant flow rate is thus the sensing of fan rotational speed. The measured fan speed is compared against the proportionality constant needed for the selected constant air flow rate and a motor excitation voltage is derived to achieve that proportionality constant. When the system load changes significantly, thereby causing significant fan speed change, a cascaded control loop is used whereby the speed changed induced by each control voltage adjustment is monitored until the desired constant flow rate is again attained at the new load level.

Abstract: The system comprises a pressure sensor for providing a signal indicative of the pressure of the refrigerant fluid of the air-conditioning system at the output or delivery of the compressor of the system, a sensor for detecting the temperature of the liquid flowing through the engine-cooling system (R), an activation sensor for providing a signal when the air-conditioning system is activated, a sensor for detecting the speed of forward movement of the motor vehicle, and a control and operating unit connected to the sensors and to the electric motor and arranged for: determining a first speed for the electric motor in accordance with a function of the pressure of the refrigerant fluid of the air-conditioning system and of the speed of the vehicle, determining a second speed for the electric motor in accordance with a function of the temperature of the engine-coolant liquid and of the speed of forward movement of the vehicle, and sending to the electric motor control signals to bring its speed of rotation to

Abstract: An apparatus and method for rotatably positioning a machine housing is disclosed. A pump produces pressurized fluid to a motor that responsively rotates the machine housing. A control valve regulates fluid flow from the pump to the motor. A position sensor detects the rotational position of the housing and responsively produces an actual position signal. A device produces a signal indicative of a desired rotational position of the housing. A controller compares the desired and actual position signals, responsively produces an error signal, multiplies the error signal by a variable gain value representative of the housing acceleration and delivers a control signal to the control valve to rotate the housing to the desired position.

Abstract: A one-phase electromagnetic motor drive controller includes a one-phase electromagnetic motor, a position detection mechanism for detecting a rotational position of the motor and a control mechanism for controlling the drive of the one-phase electromagnetic motor from the detected rotational position. When the torque constant of the motor is used as a parameter of a control calculation, the torque constant parameter is corrected by the relationship between it and the rotational position of the electromagnetic motor.

Abstract: 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.

Abstract: Draft inducer systems and methods for use with a furnace. A motor drives a fan in response to a motor control signal for inducing a draft which is a function of motor speed and motor torque. A processor defines a speed/torque operating curve having a minimum desired speed and a maximum desired speed between which the speed/torque operating curve is coincident with a pressure curve corresponding to a desired pressure drop across the furnace heat exchanger assembly caused by the draft induced by the fan. The speed/torque operating curve, for a given speed above the maximum desired speed, defines a torque less than the torque defined by the pressure curve for the given speed.

Abstract: A hydraulic pump (16) is driven by an induction motor (14) from a source of multiphase alternating current (10) of either fixed or variable frequency. The pressure is applied to a hydraulic load, which may vary, and change the pressure. A pressure sensor coupled to the pump produces pressure signals. The motor includes plural windings, typically three, associated with a number of poles. Each motor winding is driven by a different phase of controlled alternating current. A rectifier (46) coupled to the multiphase AC source generates direct current, which is filtered to minimize DC ripple voltage. A controllable multiphase inverter (54) is coupled to the rectifier and to the motor windings, for converting the direct voltage into multiphase alternating motor drive voltages of controllable amplitude and frequency.

Abstract: Air handling apparatus (10) for delivering 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 voltage supplied to the motor, 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 voltage (V), current (I), and 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.

Abstract: A method and apparatus for positioning a housing of an excavator housing. A motor receives pressurized fluid to cause rotation of the excavator housing. A motor position sensor determines the rotational position of the housing and responsively produces a housing position signal. A pressure sensor determines the fluid pressure supplied to the motor and responsively produces a pressure signal. A microprocessor produces a signal indicative of a desired rotational position of the housing. The microprocessor receives the position and pressure signals, and responsively controls fluid to the motor in order to rotate the housing to the desired position.

Abstract: A blower motor drive control circuit is configured to maintain a fixed value of motor driving current to maintain a constant amount of air supply from an air conditioner regardless of changes in the amount of intake air.