Abstract: A method for monitoring a fan comprises measuring power usage of the fan, determining a derivative of the measured fan power usage, tracking the derivative over time, and predicting impending fan failure based on the tracked fan power usage derivative.

Abstract: An improved air pulse generator produces high frequency chest wall oscillations (HFCWO) and includes means for internal heat dissipation. Internal heat generated by an internal diaphragm motor is dissipated by having a portion of the air chamber associated with the diaphragm motor being comprised of metal, by shaping a support associated with the diaphragm motor to allow increased air circulation around the diaphragm motor and positioning a vent in the housing of the air pulse generator that maximizes the release of heat from the diaphragm motor. Internal heat generated by internal electronic circuitry on a control board is dissipated by a heatsink attached to the control board.

Abstract: A method and a system for detecting the speed of a pump motor of a hydraulic pump system are provided, in which pump system a pump is driven by a pump motor to deliver hydraulic fluid into a pump reservoir. In accordance with the present invention, a pressure signal representing the fluid-delivery activity of the pump is detected, and the pressure peaks within this pressure signal identified. The speed of the pump motor is determined on the basis of the frequency or the time intervals of these pressure peaks.

Abstract: A method and apparatus are provided for controlling the operation of a pump, such as a centrifugal pump, featuring steps of either adjusting the operation of the pump, or issues a warning to a user of the pump of an undesirable operating condition, or both, based on a comparison of an actual torque value and a corrected torque value either alone or in combination with a further step of compensating the corrected torque value based on a mechanical power offset correction. The corrected torque value may include a Best Efficiency Point (BEP) torque value and may also be compensated for based on at least the current operating speed of the pump. The pump has a controller for performing the steps of the method. The controller can compensate the corrected torque value based on the square of the speed change of the pump. The comparison may include a ratio of the actual torque value to the corrected torque value.

Abstract: A system and method for calibrating fluid detects an actual fluid dispensing characteristic, such as dispensing speed, and automatically adjusts the dispensing characteristic to match an ideal dispensing characteristic. The adjustment is conducted by a controller that controls fluid dispensing based on a function that correlates dispensing speed, a dispensed volume, and a dispensing time. The function allows calibration to occur automatically by converging system operation to the ideal dispensing characteristic, without requiring a user to calibrate the system through manual iterative methods.

Abstract: A hybrid compressor system affords maximum cooling capability by making full use of an additional motor to improve the fuel consumption efficiency of a vehicle while ensuring passenger compartment cooling when the engine is stopped. The hybrid compressor system includes a compression unit for compressing a refrigerant, a motor for driving the compression unit, and disconnection means for disconnecting the drive force of a vehicle engine. In the hybrid compressor system, when the thermal load of the refrigeration cycle system lies within a predetermined range in a higher load region, the control means connects the disconnection means to allow the vehicle engine to drive the compression unit. When the thermal load of the refrigeration cycle system lies within a lower load region of the predetermined range, the control means disconnects the disconnection means to allow the motor to drive the compression unit even while the vehicle engine is running.

Abstract: A method and apparatus for monitoring operating characteristics and/or control signals of a system comprising a variable speed vacuum pump. Operating characteristics and/or control signals of the system may be monitored, and the pumping speed of the variable speed vacuum pump may be altered responsive to the monitored operating characteristics and/or control signals.

Abstract: A dynamotor capable of operating as either a motor or a generator is used with both the armature portion and the field portion thereof capable of being rotated. In the case where a pulley operatively interlocked with the output shaft of the prime mover is mounted on the rotary shaft of the armature portion, the drive shaft of the compressor is mounted on the rotating field portion. Once the dynamotor is operated in motor mode, the rotational speed of the compressor is increased to the sum of the input rotational speed and the rotational speed of the dynamotor. The compressor is stopped by disconnecting a power feed circuit. When the input rotational speed is too high, the dynamotor is operated in generator mode. In this way, the rotational speed is reduced in accordance with the generated electric energy.

Abstract: A method, system and apparatus for performing peritoneal dialysis are provided. To this end, in part, a method of controlling pressure in a medical fluid pump is provided. The method includes the steps of controlling a pump member acceleration during a first portion of a pump stroke and adaptively changing the pump member velocity during a second portion of the pump stroke.

Abstract: A system for maintaining constant pressure, such as at a mosquito fogging nozzle, by electronically controlling the speed of an engine that is coupled to a blower. A pressure sensor measures the pressure provided by the blower and provides a pressure signal to the electronic engine controller. The engine controller is of the proportional-integral (PI) type and utilizes pulse-width modulation (PWM) techniques to control an electromechanical actuator attached to the throttle of the engine to vary the engine speed. Constant pressure is maintained despite changes in the ambient temperature, humidity and barometric pressure. A safety circuit prevents engine over-speed if the pressure signal is lost. An over-speed circuit monitors and controls the engine speed at higher RPMs.

Abstract: A pumpjack speed control system includes a user interface, a controller and a variable speed drive. The user interface includes a mathematical representation of the pumpjack geometry which permits the conversion of rod speed profiles to crank speed profiles.

Abstract: When an electric compressor is activated, initial current data is selected by a selector, and a motor is driven with the torque corresponding to the initial current data. When the motor is driven by a ½ turn, the selector selects current difference data. The current difference data corresponds to an instructed speed. After the switch of the selector, the motor is driven to rotate at the instructed speed.

Abstract: The invention provides a variable speed hydraulic pump designed to operate at a maximum horsepower throughout its pressure range by adjusting motor speed according to motor load parameters. In particular, the variable speed hydraulic pump includes a hydraulic pump unit coupled to a variable speed electric motor by a drive unit and to a hydraulic fluid tank for pressurizing and pumping hydraulic fluid when operated by the motor. A motor controller is electrically connected to the motor to supply drive signals to the motor based on electrical characteristics of the drive signals which are dependent on the load exerted on the motor. Suction from the load is provided by both the main pump and a bidirectional supercharging pump by reversing the direction of the motor and shifting a 4/3 valve to connect the main pump inlet to the load and its outlet to tank.

Abstract: A fan control system. The fan control system has a programmable microcontroller to receive an input signal and a rotation speed signal corresponding to the actual rotation speed of the fan motor, determining an output signal according to the input signal and the rotation speed signal, and outputting the output signal; and a fan-driving unit to receive the output signal and adjusting the rotation speed for driving the fan motor according to the output signal. The rotation speed is in a relation of a multi-stage function to the input signal.

Abstract: A fan control system uses a closed loop system to adjust the actual operating speed of a fan or fans to a desired operating speed. The desired speed and actual speed are compared in a high gain amplifier to generate a control signal to adjust the actual operating speed of the fan given the feedback.

Abstract: A multifan-equipped apparatus in which a plurality of objects mounted are controllably cooled by blowing air using a fan-unit assembly composed of a plurality of fan units. The plural fan units are divided into a plurality of groups; the fan units in the same group are arranged in a queue. And one of the fan units of each group is a master fan unit that is autonomically adjustable in revolutions per minute (rpm) in accordance with a current apparatus-environment temperature and serves to make a tuning control on the rpm of at least one of the remaining fan units in the same group so as to adjust the rpm to a first estimated value corresponding to the autonomic-adjusted rpm of the master fan unit.

Abstract: A fluid discharge pumping apparatus includes: a drive mechanism; a cylinder; an outflow valve mechanism and an inflow valve mechanism coupled to the cylinder; a piston member inside the cylinder; and a piston-supporting member attached to the piston member driven by the drive mechanism to move the piston member. The inflow valve mechanism opens when the interior of the cylinder is depressurized, whereas the outflow valve mechanism opens when the interior of the cylinder is pressurized.

Abstract: A compressed air system and method of operating the system wherein the slip between the compressor motor and its powering alternator is used as an indication of whether the compressor is running in a loaded or unloaded mode. A slip parameter such as % Slip is determined and compared to an allowable value in real time. If the compressor is determined to be erroneously in a loaded mode, a corrective action may be taken to reduce the probability that the motor is later started with the compressor still in the loaded mode.

Abstract: A fan control system. The fan motor is operated normally at not greater than a preset maximum rotation speed. The fan control system has a programmable microcontroller to receive an input voltage and a rotation speed signal corresponding to the actual rotation speed of the fan motor, determining an output signal according to the input voltage and the rotation speed signal, and outputting the output signal; and a fan-driving unit to receive the output signal and adjusting the rotation speed for driving the fan motor according to the output signal. When the rotation speed is lower than a predetermined rotation speed, the rotation speed is in a relation of a first function to the input voltage; when the rotation speed is greater than the predetermined rotation speed, the rotation speed is in a relation of a second function to the input voltage.

Abstract: A method for determining whether a centrifugal pump is operating within its normal flow operating range includes the steps: of determining a motor torque/TDH relationship over a range of speeds for a minimum flow rate in order to obtain a minimum flow operating range for the centrifugal pump; determining a motor torque/TDH relationship over a range of speeds for a maximum flow rate in order to obtain a maximum flow operating range for the centrifugal pump; determining the actual operating motor torque and TDH of the centrifugal pump at a given operating point; and determining whether the actual operating motor torque and TDH of the centrifugal pump fall within the minimum flow and maximum flow operating ranges of the centrifugal pump.

Abstract: Pumping requirements for chromatograph applications are for constant flow at high and variable pressures and for accurate programmable control of liquid composition. A two-cylinder pump, pumping system, and associated controls provide an accurate, fixed flow rate. A low pressure gradient former controls composition. During the initial portion of the pumping stroke of a first piston in which fluid is being compressed due to its finite bulk modulus of elasticity its check valve remains closed, a second piston provides all the flow required at a fixed rotational speed. Then, once the first piston has reached its bottom dead center, the control system switches to a constant-pressure control mode, thereby maintaining the flow rate at a fixed value. Constant-pressure control is again switched off either when the second piston's discharge check valve closes, or when the second piston's inlet check valve opens, and pump control returns to fixed rotational speed.

Abstract: A fuel metering pump (1) has a solenoid coil (2), an armature (3), a delivery piston (4) and spring-loaded valves. The spring-loaded valves are embodied as an electrically controlled suction valve (5) and an electrically controlled pressure valve (6). A solenoid coil (2) is provided for the armature (3) of the delivery piston (4), the armature (7) of the suction valve (5) and the armature of the pressure valve (6). The masses, springs and hydraulic cross-sections of the component parts are configured in such a way that the valves switch more quickly than the delivery piston moves.

Abstract: A multi-stage screw compressor includes at least two stages of compression, each compressor stage including a pair of rotors driven to effect gas compression. Each compression stage is provided with independent variable speed drive means and a control unit for controlling the speeds of the independent drive means. The control unit includes processing means for processing signals generated by a plurality of devices monitoring operating parameters of the compressor, and adjusting the speed of the drive means to provide a required gas flow delivery rate and pressure, at least one of the monitoring devices monitoring the torque and at least one of the monitoring devices monitoring the speed of each drive means.

Abstract: A constant flow of air through a personal air sampler is provided regardless of changes in the air flow path, by altering the pump speed as a function of the power taken by the pump. The characteristics of the pump are precalibrated to provide a constant used together with the square of the voltage appearing across the motor armature coils (applied voltage minus back Emf), which reflects the power currently used, to adjust the motor speed and thus provide a constant flow of air under changing conditions of resistance.

Abstract: A system for maintaining constant pressure, such as at a mosquito fogging nozzle, by electronically controlling the speed of an engine that is coupled to a blower. A pressure sensor measures the pressure provided by the blower and provides a pressure signal to the electronic engine controller. The engine controller is of the proportional-integral (PI) type and utilizes pulse-width modulation (PWM) techniques to control an electromechanical actuator attached to the throttle of the engine to vary the engine speed. Constant pressure is maintained despite changes in the ambient temperature, humidity and barometric pressure. A safety circuit prevents engine over-speed if the pressure signal is lost. An over-speed circuit monitors and controls the engine speed at higher RPMs.

Abstract: A dynamotor capable of operating as either a motor or a generator is used with both the armature portion and the field portion thereof capable of being rotated. In the case where a pulley operatively interlocked with the output shaft of the prime mover is mounted on the rotary shaft of the armature portion, the drive shaft of the compressor is mounted on the rotating field portion. Once the dynamotor is operated in motor mode, the rotational speed of the compressor is increased to the sum of the input rotational speed and the rotational speed of the dynamotor. The compressor is stopped by disconnecting a power feed circuit. When the input rotational speed is too high, the dynamotor is operated in generator mode. In this way, the rotational speed is reduced in accordance with the generated electric energy.

Abstract: A rod pump control system includes a parameter estimator that determines from motor data parameters relating to operation of the rod pump and/or downhole dynamometer card without the need for external instrumentation, such as down hole sensors, rod load sensors, flow sensors, acoustic fluid level sensors, etc. In one embodiment, instantaneous motor current and voltage together with pump parameters are used in determining rod position and load. The rod position and load are used to control the operation of the rod pump to optimize the operation of the pump. Also disclosed in a pump stroke amplifier that is capable of increasing pump stroke without changing the overall pumping speed, or in the alternative, maintaining the well output with decreased overall pumping speed.

Abstract: A control system for the operation of a progressing cavity pump which may be used for production of gas and/or oil from a well. The control system includes vector feedback model to derive values of torque and speed from signals indicative of instantaneous current and voltage drawn by the pump motor, a pump model which derives values of the fluid flow rate and the head pressure for the pump from torque and speed inputs, a pumping system model that derives from the estimated values of the pump operating parameters an estimated value of a pumping system parameter and controllers responsive to the estimated values of the pumping system parameters to control the pump to maintain fluid level at the pump input near an optimum level.

Abstract: A brushless direct current magnetic pump includes a drive shaft that passes through and that is coupled to a magnet carrier. The magnet carrier with an annular sleeve with at least six outer ribs that define at least six slots that extend axially along the sleeve. The at least six slots accommodate at least six bar magnets and at least six sensor magnets. A Hall effect sensor is included in the motor assembly to provide positional information of the sensor magnets to a controller for improved speed control.

Abstract: An air conditioning system for a vehicle that is driven by a vehicular power source. The system has a compressor selectively operable by the vehicular power source and an electric motor. The electric motor is used as a drive force of the compressor when the vehicular power source is in a non-operative state. The compressor compresses refrigerant gas introduced into a suction chamber from an external refrigerant circuit. A displacement of the compressor is variable, based on a differential pressure. The compressor has a control valve that is disposed on a refrigerant passage communicating with the crank chamber. The control valve has a valve plunger for changing an opening size of the control valve to adjust pressure in the crank chamber. The air conditioning system comprises pressure sensing member, actuator, and controller. The pressure sensing member is disposed in the control valve and applies biasing force to the plunger based on pressure in the external circuit.

Abstract: An industrial robot including a manipulator having a control system. The manipulator includes a common gear housing having first and second inner compartments connected with a passage channel. First and second gears are arranged in the first and second inner compartments and are adapted to move the manipulator. A cooling and lubricant medium is disposed in the common gear housing and circulates between the first and second inner compartments through the passage channel.

Abstract: An apparatus and method for operational control of a reciprocating motor compressor, includes performing an operation of the reciprocating motor compressor precisely and accurately. In addition, with the above apparatus and method, the phase difference between a first speed value of the motor (or first TDC value) and current applied to the motor is detected, the second speed value of the motor at the inflection point of the detected phase value (or second TDC value) is detected and stored as a reference value, and the speed of the motor is controlled on the basis of the reference value and the first speed value of the motor (or the first TDC value).

Abstract: A method and apparatus for monitoring operating characteristics and/or control signals of a system comprising a variable speed vacuum pump. Operating characteristics and/or control signals of the system may be monitored, and the pumping speed of the variable speed vacuum pump may be altered responsive to the monitored operating characteristics and/or control signals.

Abstract: An air-conditioning system for a vehicle, including a refrigerant circuit and an engine, has a battery, a compressor, an electric motor and a load torque control mechanism. The battery supplies electric power. The compressor is operative to compress refrigerant gas for the air-conditioning system. The electric motor is electrically connected to the battery. The motor is driven due to the electric power, and is operatively coupled to drive the compressor when the motor is energized. The load torque control mechanism responsive to the operating condition of the engine to control the load torque of the compressor below a predetermined value during times when the motor is driving the compressor.

Abstract: A constant-pressure pump controller system for maintaining a substantially uniform discharge pressure of liquid output from a pump operated by an electric motor and where liquid is delivered to a plurality of simultaneously-operating downstream outlets. The system provides a pressure transducer for sensing discharge pressure from the pump, and includes a piston bearing a magnet for Hall effect interaction. To accomplish Hall effect sensing, an electric current carrier is situated to interact with the magnet for production of Hall voltage which is monitored by a voltage sensor in communication with a controller that regulates motor speed in accord with Hall-effect sensed need through pulse width modulation in response to the voltage value according to proportional integral derivative methodology. Finally, a pump input voltage sensor and regulator maintain a constant voltage output to the pump should voltage input be variable.

Abstract: A liquid dispensing system increases the precision, reliability, and safety of dispensing medications and other liquids. An electronic brake grounds a power terminal of a pump motor to absorb the kinetic energy of the motor and other mechanically coupled components. The electronic brake reduces overage and overage variation in the dispensing of liquids at very little cost or complexity. A watchdog circuit monitors a controller heartbeat signal and disables the motor in the absence of a regular beat. The watchdog circuit along with redundant power switches greatly reduce the possibility of motor runaway in the event of component failure. A controller begins or ends each dispensing cycle with a diagnostic which determines whether the liquid dispensing system is fully operational. If not, the controller may disable the motor, emit an alarm tone, and display an alarm message.

Abstract: A motor-driven compressor includes a motor and a compression portion for compressing a refrigerant. The motor-driven compressor comprises an input terminal for the motor and a drive circuit for controlling a rotation speed of the motor. The input terminal of the motor passes through an opening formed through a wall of a refrigerant suction route, whereby the input terminal is secured to the wall, and extends beyond the wall. The drive circuit controls the rotation speed of the motor and has an output connector. The output connector of the drive circuit is connected directly to the input terminal to secure the drive circuit to the wall. The direct connection eliminates a need for a wire connection between the output connector and the input terminal. Moreover, methods of assembling motor-driven compressors are disclosed.

Abstract: The present invention involves a dynamic brake for use in a peristaltic (i.e., roller) pump. The dynamic brake avoids backlash, due to counter rotation. In addition, it does not preclude the option of hand operating the roller pump. This is achieved by initiating the braking operation after the roller pump set-point has been set to zero and only after the roller pump has decelerated below a predefined speed (e.g., 20 rpm). In addition, the braking operation is activated for only a very brief period of time (i.e., a period of time required for the pressure in the roller pump fluid conduit to subside).

Abstract: A centrifugal fluid pump apparatus includes a control mechanism; and a body 5 including a pump section having an impeller rotating inside a housing; a rotor having an impeller attraction magnet; a motor for rotating the rotor; an impeller attraction electromagnet for attracting the impeller thereto; an impeller-position detection sensor; and a groove for hydrodynamic bearing provided on an inner surface of the housing. The control mechanism has a position sensor output monitoring function or an electromagnet current monitoring function, a motor current monitoring function; and an emergency impeller rotation function. The impeller rotation function operates when the sensors or the electromagnet has a failure by using the position sensor output monitoring function or the electromagnet current monitoring function to rotate the impeller by utilizing the groove for hydrodynamic bearing.

Abstract: The invention concerns a blood pump, in particular a ventricular cardiac support pump, with formed in a pump housing a blood chamber which is designed to hold a rotor rotatable about a rotor axis and at opposite ends in sections forms an inlet connectable with an inlet cannula, where an outlet from the blood chamber connectable with an outlet cannula extends in a direction perpendicular to the rotor axis, and where the rotor axis at its ends is mounted rotatably in mechanically active bearings provided in the area of the inlet concerned and connected with the pump housing.

Abstract: A pump off control method comprises detecting the speed of the induction motor and an instantaneous value of secondary current of the induction motor. Down stroke time in every cycle of the pump jack is detected. An average value of instantaneous values of the secondary current of the induction motor in the down stroke time in said every cycle is calculated. An average value reference of the secondary current of the induction motor to be compared with calculated average value of the instantaneous values of the secondary current of the induction motor is set. The calculated average value of the instantaneous values of the secondary current is compared with the average value reference after the down stroke end in each cycle. An occurence of pump off is detected if the calculated average value of the instantaneous values is greater than the average value reference.

Abstract: A wastewater pumping system includes a centrifugal pump operatively connected to an electric motor via a coupling. The speed of the electric motor is automatically varied responsive to the head or load realized by the pump of the system as it varies with the composition of the slurry mixture. A variable frequency drive is operatively connected to the motor and the electrical power supply that affects a shift or change in electrical frequency delivered to the electrical motor so that the speed of the motor and consequently the pump is varied. This allows the electrical power deliver to the system to remain substantially unchanged for varying loads realized by the pump.

Abstract: A method of calculating the position of the rotor of a motor (1) in for example an electrical power assisted steering assembly is disclosed. The method comprises the steps of measuring the output shaft (2) (i.e. steering column) position, and scaling the measured value to produce an estimated motor rotor position value. This estimated value will be relative to an arbitrary datum point, and so the method further includes steps of adding an offset value derived from low resolution measurements of rotor position obtained using Hall effect sensors provided on the motor. Offsets for compensating for backlash and (in a second embodiment) compliance can also be included. Thus, the method allows high resolution information from an output shaft sensor (e.g. a torque sensor with a position dependent output) to be combined with the low resolution output from the Hall effect sensors to produce a high resolution rotor position signal.

Abstract: A control system for a vacuum pump used for removing liquid from a suction washer of a pulp mill includes a pump with adjustable rotation speed and means for defining the operating point of the vacuum pump and a control/central unit wherein the performance chart of the vacuum pump is recorded and wherein the defining data of the vacuum pump operating point is fed. The control system further includes a resistance function on the suction side of the vacuum pump which depicts the suction resistance formed of at least the suction object in the suction side. The resistance function is determined by changing the rotational speed of the vacuum pump and recording the operating points in the control/central unit at various rotational speeds.

Abstract: A fan control system. The fan motor is operated normally at not greater than a preset maximum rotation speed. The fan control system has a programmable microcontroller to receive an input voltage and a rotation speed signal obtained by detecting the actual rotation speed of the fan motor, determining an output signal according to the input voltage and the rotation speed signal, and outputting the output signal; and a fan-driving unit to receive the output signal and adjusting the rotation speed for driving the fan motor according to the output signal.

Abstract: There is provided an autonomous inverter-driven hydraulic unit in which a command pressure and command flow rate do not need to be inputted from outside and a pressure and flow rate can be autonomously controlled without requiring any input signal wire. A target horsepower calculation unit 25 of a controller 11 judges which of a plurality of regions a point representing a present operating state belongs to and calculates a target horsepower represented by a point on a target pressure-flow rate characteristic line based on the present pressure and present flow rate. A comparison unit 28 calculates a deviation of this target horsepower and a present horsepower received from a present horsepower calculation unit 26, inputs a control signal representing this deviation to the inverter 3 and controls a rotational number of a variable-speed motor 2 so that the present horsepower coincides with the target horsepower.

Abstract: A brushless direct current magnetic pump includes a drive shaft that passes through and that is coupled to a magnet carrier. The magnet carrier with an annular sleeve with at least six outer ribs that define at least six slots that extend axially along the sleeve. The at least six slots accommodate at least six bar magnets and at least six sensor magnets. A Hall effect sensor is included in the motor assembly to provide positional information of the sensor magnets to a controller for improved speed control.

Abstract: Motor speed, motor amps, float position and elapsed run time are monitored to determine whether a sump pump is in a normal condition, a jammed condition, an inadequate pumping rate condition, a dry running condition or a stuck float condition. A processor is configured to increase the motor speed in response to an inadequate pumping rate condition, and to rapidly energize the motor clockwise and counterclockwise in response to a jammed condition or a stuck float condition. The processor provides signals to a display for displaying information about the condition that the pump is in. The pump is set up to receive power from either an AC power source or a battery power source. Availability of the AC power source is monitored and the pump is switched to operate from the battery power source when AC power is unavailable.

Abstract: A method is provided to determine an rpm profile for a turbine pump from pulse train data obtained from a sensor at the pump. The method eliminates ramp-up spikes from the pulse train by comparing the spike pulse count to the surrounding pulse counts and replacing data points responsible for abnormal pulse count increases/decreases between data points with interpolated values. The method similarly replaces data points that lie outside statistically acceptable pulse rate variations. A rough rpm plot is then generated, which must be smoothed to obtain the final rpm profile. Data points are infused between sensor data points to achieve an acquisition rate of approximately 1000 points per second. The infusion is accomplished by interpolating between sensor data points and equally spacing the infused data points along the interpolated curve. A smoothing function is then applied to the infused data set.

Abstract: A reciprocating motor compressor and particularly, to an apparatus and method for operation control of a reciprocating motor compressor, for performing operation of the reciprocating motor compressor precisely and accurately. In addition, with the above apparatus and method, phase difference between a first speed value of the motor (or first TDC value) and current applied to the motor is detected, the second speed value of the motor at the inflection point of the detected phase value (or second TDC value) is detected and stored as a reference value, and the speed of the motor is controlled on the basis of the reference value and the first speed value of the motor (or the first TDC value).