Abstract: In a flow rate estimation device of a blood pump, a general flow rate estimation formula which includes a correction term is formed based on a plurality of blood pumps. Measured data obtained from an objective blood pump implanted inside a patient is substituted into the correction term, thus forming a flow rate estimation formula of the objective blood pump. The flow rate Q of the objective blood pump is estimated based on the flow rate estimation formula and the values of the rotational speed N and the consumption current I of the motor of the objective blood pump, and the attribute data Z of the blood of the patient.

Abstract: A control circuit for controlling the rotational speed of a fan may include a memory element to store operating data corresponding to an operational profile of the fan defined by RPM (revolutions per minute) versus temperature, with the operating data comprising a respective temperature value and a respective RPM value for each respective operating point representing a change in slope of a function that corresponds to the operational profile of the fan. A processing unit may operate to receive a present temperature value, retrieve the operating data from the storage unit, and identify a pair of consecutive operating points such that the present temperature value is greater than a lower respective temperature value of the pair of consecutive operating points, and lower than a higher respective temperature value of the pair of consecutive operating points.

Abstract: A dual-speed single-phase AC motor, including: a stator, including a stator core, and a coil winding, including a starting winding, a first main winding, and a second main winding, a rotor, and a starting circuit, including a rectifying and voltage-stabilizing circuit, a detecting circuit, a voltage comparison circuit, a first switching circuit, a second switching circuit, and a third switching circuit. The number of poles of the starting winding is the same as that of the first main winding. The number of poles of the first main winding is less than that of the second main winding.

Abstract: An apparatus for supplementing a brake vacuum pressure, may include an engine control unit (ECU) that generates a vacuum pressure control signal for supplementing the brake vacuum pressure in accordance with the result of determining whether the brake vacuum pressure is included in a reference vacuum pressure range after a vehicle implements an ISG process, a sub-oil pump that is operated in accordance with a control signal from the ECU to supply hydraulic pressure to the inside of an automatic transmission after the vehicle implements the ISG process, a vacuum pump that generates and supplies the brake vacuum pressure to a brake system, and an electronic clutch that selectively couples the sub-oil pump and the vacuum pump to allow driving force of the sub-oil pump to be transmitted to the vacuum pump or to be cut, in accordance with whether the vacuum pressure control signal is sent thereto.

Abstract: A rotating speed adjustment circuit for a heat dissipation fan includes a first node, a second node, a reception end for receiving a first control signal, a first resistor coupled to a voltage source and the first node, a second resistor coupled to the first node and the second node, a third resistor coupled to the second node and a ground end, a capacitor coupled to the first node and the ground end, a transistor coupled to the reception end, the second node and the ground end, an oscillator for generating an oscillating signal, and a comparator for comparing a signal of the first node and the oscillating signal, so as to output a second control signal to control a rotating speed of the heat dissipation fan.

Abstract: A method for operation of a compressor supplied by a power converter having an operating condition (BV) for the compressor (12) supplied by a power converter, generated from a measured actual rotational speed (n) of the compressor and a given effective current component (iW) of a measured power converter output current (I) using a stored speed-dependent pump characteristic curve (SG) monitored for validity such that on determining invalidity, as per a stored speed-dependent instantaneous curve, a control signal (SSG) for reducing a torque (M) is generated. A method for operation of a compressor supplied by a power converter is then achieved with which the duration and the intensity of surge conditions is significantly reduced.

Abstract: A pumping system in which a pump (5) is controlled by a programmed controller (22) in response to input signals from an inlet pressure transducer (3) and an outlet pressure transducer (15) and in certain circumstances inputs from various flow sensors (4,19). The controller (22) can be programmed to allow the pump (5) to prematurely operate before an outlet pressure reaches a low pressure threshold, when usage of the liquid is high. The controller (22) can be programmed to detect a lack of prime of the pump (5), to restore prime once the pump (5) has lost prime, and to prevent successive on/off pump cycles when the outlet flow is continuous and at a moderate or low level.

Abstract: A variable speed pumping system and an associated method for moving water of an aquatic application. The variable speed pumping system includes a water pump for moving water in connection with performance of an operation upon the water. A variable speed motor is operatively connected to drive the pump. A sensor senses a parameter of the operation performed upon the water. A controller controls speed of the motor in response to the sensed parameter of operation.

Abstract: A system and method for controlling the speed of a progressing cavity liquid well pump to increase liquid production from a well while avoiding operation of the well in a pumped-off state. A controller controls a variable speed drive to drive a progressing cavity liquid well pump at a set pump speed while measuring well and system parameters indicative of pumping performance and/or liquid production from the well. The set speed of the pump is changed in steps either increasingly or decreasingly by the controller, acting through the variable speed drive, in response to the measured well and system parameters. The controller, responsive to the measured well and system parameters, challenges the set pump speed by varying the set pump speed so as to increase the production from the well while avoiding pump and well operation in a pumped-off state.

Abstract: A system for cancelling or attenuating noise in at least two positive displacement compressors proximately located from each other for use with a heating or cooling system. A lead compressor and a lag compressor have a controllable rotational speed and phase of operation. A controller selectably controls the rotational speed and the phase of operation of each of the compressors. The controller controls the rotational speed of the compressors at substantially the same speed for each compressor, with a phase-lock loop and a comparator circuit for each compressor. The controller controls the phase of operation of the compressors through an oscillator so that the lead and lag compressor pressure pulses are spaced between successive outlet pressure pulses to effectively double the combined pulsation frequency for noise attenuation.

Abstract: The present invention provides a liquid delivery device for liquid chromatographs which, by performing liquid delivery at an accurate flow rate with limited pulsation, gives accurate results of analyses. The present invention, with a view to preventing erroneous operation due to errors in measurements at the time of judgment of completion of compression of liquid, establishes the judgment point before the pressure measured by a cylinder pressure detector agrees with the pressure measured by a discharge pressure detector and also calculates the point of completion of compression. Control in this manner prevents pressure fluctuation. It also calculates for control the point of completion of compression from the history of compression performed previously.

Abstract: A pumping system for moving water of a swimming pool includes a water pump and a variable speed motor. The pumping system further includes means for determining a first motor speed of the motor, means for determining first and second performance values of the pumping system, and means for comparing the first and second performance values. The pumping system further includes means for determining an adjustment value based upon the comparison, means for determining a second motor speed based upon the adjustment value, and means for controlling the motor in response to the second motor speed. In one example, the pumping system includes means for determining a value indicative of a flow rate of water moved by the pump. In addition or alternatively, the pumping system includes a filter arrangement. A method of controlling the pumping system for moving the water of the swimming pool is also disclosed.

Abstract: A method of monitoring a pump which operates to pump sewage from a wet well in which the current drawn by the pump is detected along with the speed of operation of the pump and the wet well level. The detected values are compared with stored values in a look up table to determine whether the pump is blocked.

Abstract: A motor control device includes a recording module and a controlling module. The recording module has a revolution speed table recording a plurality of predetermined revolution speed values. The controlling module receives a reference revolution speed control signal and measures the reference revolution speed control signal to correspondingly generate a reference measuring value. The recording module records the reference measuring value corresponding to one of the predetermined revolution speed values in the revolution speed table.

Abstract: A pump control mechanism includes a pump unit for feeding liquid to container, a position detector for detecting the position in the reciprocating motion of the pump member, a control table having control information of many time zone sections, an information memory for storing target information corresponding to a target driving speed, a driving information calculator for calculating driving information of a motor on the basis of the reciprocating position detection, a correcting information calculator for calculating correction information for reducing the difference between the driving information and the target information, and a corrector for correcting the control table.

Abstract: Rod Float Mitigation (RFM) methods for rod-pumped oil wells having a variable frequency drive which controls the speed of the motor for the pump. Each method monitors rod loads or a similar condition and takes action only when rod load drops below a predefined minimum load. A first method reduces the speed of the motor to a preset level. A second method fixes the torque level on the pump downstroke by adjusting motor speed based on a calculated gearbox torque compared to a programmed fixed limit. Another method includes a program in the variable frequency drive which includes a preferred RFM Torque Curve for the pump to follow on its downstroke. When rod float occurs, the program monitors gearbox torque and adjusts the speed to follow the predetermined RFM Torque Curve thereby mitigating rod float with minimum decrease in production.

Abstract: A control apparatus of a construction machine includes a hydraulic pump driven by a prime mover, a hydraulic actuator, and a rotation speed detection device for detecting an actual rotation speed of the prime mover. The control apparatus includes a prime mover control device for controlling a rotation speed of the prime mover, and an input torque control device for adjusting an input torque for the hydraulic pump based on a deviation between the actual rotation speed detected by the rotation speed detection device and a control rotation speed set through an operation of the operating device, and the input torque control device executes control to decrease the input torque if the control rotation speed is greater than the actual rotation speed and the deviation calculated by subtracting the control rotation speed from the actual rotation speed is smaller than a predetermined negative value.

Abstract: A vehicle control apparatus includes an input member; a driving force transmission mechanism that transmits a rotational driving force of the input member to an output member; a mechanical pump that operates by using the rotational driving force of the input member; an electric pump that operates when a rotational speed of the mechanical pump is less than a predetermined operation threshold; an oil pressure control apparatus that performs control operations for the driving force transmission mechanism by supplying operating oil, which is supplied from the mechanical pump and the electric pump, to the driving force transmission mechanism; and a controller that detects a state of the electric pump.

Abstract: Improvements to a compressor which consists in that, as soon as the measured outlet temperature (TO) reaches a certain hysteresis upper temperature limit (HMAX), the actual rotational speed of the compressor element is either lowered with a speed jump (DS) when the measured rotational speed is situated in the higher speed range close to the maximum rotational speed (SMAX), or is increased with a speed jump (DS) when the measured rotational speed is situated in the lower speed range close to the minimum rotational speed (SMIN).

Abstract: A compressor for a turbo chiller that can stably and efficiently operate in various operating states is provided. An aerodynamic feature map showing a rotating stall line at which rotating stall occurs is provided on a map represented by a flow parameter reflecting the volume flow based on the output thermal capacity of the chiller and by a pressure parameter reflecting the head based on the evaporator pressure and the condenser pressure. A minimum rotation speed obtaining unit obtains a minimum rotation speed from the pressure parameter and the rotating stall line on the aerodynamic feature map in the current operating state, and a rotation speed greater than or equal to the minimum rotation speed thus obtained is designated to the inverter.

Abstract: An adjustable frequency pump control system (10) that is primarily designed for use in commercial pool filtration systems. The system (10) automatically selects one of three operating speeds that control the speed of a motor that operates a circulation pump (62). The system (10) includes a programmed logic control (PLC) (42) that is activated upon the application of select mode signal (31), a mode timing signal (35), a line pressure signal (37), a circulation pump-run signal (39) and a backwash signal (41). The output of the PLC (42) is a frequency set signal (17) that is applied to an adjustable frequency drive (AFD) (18). From the output of the AFD (18) a motor speed control signal is produced that is applied to the motor that operates the circulation pump (62). The speed of the circulation pump (12) is governed by the frequency of the motor speed control signal, wherein the frequency is determined by the motor speed that is applicable to a particular design point of the pump's filtration cycle.

Abstract: A system is provided for attenuating noise in at least two positive displacement compressors proximately located from each other for use with at least one heating or cooling system. A lead compressor and a lag compressor have a selectably controllable rotational speed and a selectably controllable phase of operation. A controller selectably controls the rotational speed and the phase of operation of each of the compressors. The controller controls the rotational speed of the compressors at a predetermined rotational speed that is substantially the same for each of the compressors. The controller controls the phase of operation of the compressors by shifting the phase of operation of the lag compressor so that an outlet pressure pulse operatively produced by the lag compressor is substantially evenly spaced between successive outlet pressure pulses operatively produced by the reference compressor.

Abstract: A device for adjusting the armature stroke in a reversible linear drive unit comprising an excitation coil and an armature displaceable in the magnetic field of the excitation coil according to a linear oscillating motion at a predefined armature stroke. The device comprising systems for detecting the current armature position, systems for measuring the actual excitation coil current and systems for adjusting the excitation coil current in such a way that the armature is exactly supplied with electric energy for obtaining the aptitude of oscillations of the armature stroke during each half-wave of the armature motion.

Abstract: Each of controllers includes: a transistor; a data processor for executing predetermined data processing and turning the transistor on or off in accordance with the data processing result; a pull-up resistor connected to an output terminal of the transistor; and a level separating resistor connected to the output terminal of the transistor, and the data processor of each controller detects a signal level of a control signal output from the output terminal of the transistor and judges whether or not any defect has occurred in its own controller, based on the detection result.

Abstract: A water pump for bodies of water such as ponds, aquariums, or fountains containing suspended particles has a housing with a pump housing part provided with an intake opening and an exit opening, in which housing part an impeller with a shaft is rotatably supported, and a motor housing part in which an electric motor is received. As an improvement, an electronically commutated motor is used and the pump has a power input as well as power and control electronics for the motor having an operating state detection device with speed detection, processor and data storage device. The processor can control an interrupt switch between the power input and the motor. In the data storage device certain characteristic lines in regard to normal operating states can be stored.

Abstract: The present invention generally provides apparatus and methods of operating a pumping system. The pump control apparatus includes a first sensor for measuring strain on a structure of the well pumping system and a second sensor for measuring a position of the structure. The apparatus also has a controller configured to control the well unit by receiving output signals from the first and second sensors and generating control signals according to a motor control sequence. This controller may be mounted to the structure of the pumping system to measure the strain experienced by the structure. The control signals may be transmitted to a motor control panel using a cable-less communications system. Preferably, the first sensor, the second sensor, and the controller are integrated into a single unit. In another embodiment, the pump control apparatus may be self-powered.

Abstract: A pump control system (20) for a pump (21) in a gas turbine engine (10) is described. The pump control system (20) comprises demand means (22) for providing a demand signal (23) relating to a required rate of fluid flow and/or pressure from the pump (21). The system also comprises sensing means (26) to sense at least one parameter of fluid downstream of the pump (21) and to provide at least one feedback signal (28) relating to the, or each, respective parameter. Comparator means (30) is provided for comparing the demand signal (23) with the, or at least one, feedback signal to provide a control signal (33) for controlling the pump.

Abstract: An apparatus, method and system for applying a biologically active or chemical substance to a relatively large volume harvested or pre-harvested crop includes relatively small container of a mixture biologically active or chemical substance and water in fluid communication with fluid conduit. A pump moves mixture from the bottle through the conduit. A source of pressurized air is in fluid communication with the conduit to aerate the mixture. The aerated mixture is expelled through a nozzle at distal end of the conduit. In one aspect, the controller can monitor speed of the pump by monitoring operating voltage of the pump. Speed of the pump can be adjusted to adjust application rate. In one aspect, a process combines a flow of air through an orifice with the metering of a low volume of additive, such as an aid to preservation, to a crop as it is being cut or harvested to provide for even distribution of the additive to the crop.

Abstract: A controller for controlling the pump unit of an oil well includes a sensor having a first and second probe for placement in the flow of oil from the well bore. Each of the probes contains a heater. A constant power source is selectively connected to one of the heaters. Each of the probes also include a linear RTD at each of their tips respectively for generating a signal indicative of the temperature measured at each of the first and second probes. A control unit receives signals from the RTD's and determines a flow rate therefrom. A pump control signal is generated in response to the flow rate, wherein pump control signal continuously varies a predetermined parameter of a pumping unit during operation of the pumping unit.

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 centrifugal fluid pump assembly includes a body section and a control mechanism 6. The body section includes a housing, an impeller rotatable within the housing, and a motor for rotating the impeller. The pump assembly includes a motor current flow rate-related data storage section for storing, for a plurality of different predetermined viscosities, predetermined viscosity-related flow rate data formed from a plurality of motor current flow rate relation data at a plurality of different impeller rotational speeds at predetermined fluid viscosity, a fluid measurement data inputting section, an impeller rotational speed measurement function, a motor current measurement function, and a flow rate calculating section 58 for using a fluid viscosity value, an impeller rotational speed value, a measured motor current and data stored in the motor current flow rate-related data storage section to calculate a fluid flow rate.

Abstract: The present invention generally provides apparatus and methods of operating a pumping system. The pump control apparatus includes a first sensor for measuring strain on a structure of the well pumping system and a second sensor for measuring a position of the structure. The apparatus also has a controller configured to control the well unit by receiving output signals from the first and second sensors and generating control signals according to a motor control sequence. This controller may be mounted to the structure of the pumping system to measure the strain experienced by the structure. The control signals may be transmitted to a motor control panel using a cable-less communications system. Preferably, the first sensor, the second sensor, and the controller are integrated into a single unit. In another embodiment, the pump control apparatus may be self-powered.

Abstract: Pumping for chromatograph applications calls for constant flow at high pressures and for accurate control of liquid composition. A two-cylinder pump, and associated controls provide an accurate, fixed flow rate. During the initial portion of the pumping stroke of a first piston, while its check valve remains closed, a second piston provides all the flow required at a fixed rotational speed. Once the pressure inside the first piston's cylinder has reached that of the discharge and its discharge check valve opens, the control system switches to a constant-pressure control mode, to maintain a fixed flow rate. Constant-pressure control is switched off when the second piston's discharge check valve closes, and pump control returns to fixed rotational speed. Determining the angular displacement at which to effect these control-mode switches is carried out by monitoring changes in the discharge pressure.

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: Provided is a liquid chromatograph pump system which sucks eluent from an eluent reserving container, and which feeds pressurized high pressure eluent into a column, wherein a plunger reciprocating in a cylinder is formed on its outer peripheral surface with a stepped part along the sliding diretion of the plunger in the cylinder so as to define a working chamber between the stepper part and the inner wall surface of the cylinder, the flow rate of the liquid chromatograph pump being determined by the volume of the working chamber and the traveling speed of the plunger, thereby it is possible to stably feed a liquid at an extremely low flow rate, and to satisfactorily expel air bubbles upon a start of the liquid chromatograph pump system.

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 drive arrangement for a conveying device for the conveying of a flowing medium is described, particularly for the conveying of air or fluid. The drive arrangement contains a drive engine whose rotational speed can be varied, an auxiliary motor that can be continuously controlled and a summing gearbox. The summing gearbox is connected on its output side with the conveying device and on its input side with the drive engine and the auxiliary motor. Furthermore, the drive arrangement contains a control unit that controls the auxiliary motor. In order to make possible an improved control or regulation of the conveying performance compared to linear, rigidly driven conveying devices, it is proposed that at least one magnitude of the condition of the flowing medium be detected by at least one sensor and to control or regulate the auxiliary motor of the drive arrangement by the control unit as a function of at least one magnitude of the condition of the medium.

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: In the process according to the invention for determining a nominal values curve of an installation (Hinstallation(Q), Pinstallation(Q)) for controlling the pump capacity of a pump (6) driven by an electric motor (10) with speed control in a closed system with variable capacity requirement, first all consumers in the installation are closed, one consumer operation parameter is determined at a consumer (4-n) arranged at a distance from the pump, the pump capacity is varied until the consumer operation parameter has reached a predetermined value, and, once this value has been reached, a pair of pump parameters representative for the instantaneous pump capacity is determined and stored in the controller. This measurement is repeated with different consumers being open, and from the stored values of the pairs of pump parameters the curve of nominal values (Hinstallation(Q), Pinstallation(Q)) of the installation is calculated by way of a mathematical process for establishing a curve.

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: The invention relates to the use of variable speed control of the cooling fan on a variable speed oil-injected screw compressor. A screw compressor (11) comprises at least one stage of compression, each with a pair of rotors, variable speed compressor drive means (12), an oil reclaimer (13) from the compressed air and cooling apparatus (17) for cooling the oil extracted from the compressed air. The cooling apparatus comprises a heat exchange device and a fan (18) driven by a motor (19) which can be run at different speeds.

Abstract: The invention relates to a method for controlled driving of the cast axle (8) of pressure die casting machines, comprising a drive piston (15), wherein the forward and return motion of the piston (15) is carried out in a controlled manner. The invention is characterized in that the oil flow or oil pressure on the piston rod side is controlled/regulated by a pump (30) and additionally by a throttle valve (103) working in parallel at least during the filling phase, especially during the fast forward motion part.

Abstract: In an operation control apparatus of a compressor, a current, a voltage an d a TDC, etc. applied to a compressor are detected, a speed and a TDC are constantly controlled so as to place an operation point of the compressor within a high efficiency operation region by using a phase difference between each detected values (for example, a phase difference between the current and the voltage), and an operation frequency is varied according to a load variation, accordingly an operation efficiency of the compressor can be improved.

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: There is disclosed a pump and pumping system for pumping dense phase gases, specifically for injecting carbon dioxide into an oil or gas reservoir that includes a pump, a motor, and a casing in which the pump and motor reside. There is also disclosed a pump and pumping system for injecting dense phase greenhouse gases into a reservoir or underwater. The pump may include a downhole electric submersible pump. A method of controlling the pump and pumping system is also described involving the use of a variable speed drive in conjunction with an on-line gas chromatograph to maintain a constant carbon dioxide injection rate.

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 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: 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: A fluid dispense system having a computer control system that operatively controls a stepper motor driving a pump. The stepper motor actuates the pump piston through partial revolutions. The computer control system determines the number of stepper motor steps required to pump a desired amount of fluid by the pump by rotating the piston through segments which are less than a full revolution. Further, the controller varies the speed of the stepper motor to avoid splashing of the dispense fluid and motor stalling.

Abstract: A tan having a fan wheel and an electric motor driving it, and a control unit for controlling the motor output as a function of fan-specific parameters. An actual-value signal corresponding to an actual rotational speed of the fan is measured and compared with a control signal corresponding to a required speed, and the actual speed is adjusted to the required speed by means of the control unit, wherefore the actual speed and the actual motor current or supply current are measured and conducted to a microcontroller as input signal variables, whereby the fan-specific data such as wheel diameter, density of the conveying medium, fan coefficients, motor coefficients, and a preset artificial characteristic curve ps=ƒ({dot over (V)}s ) are stored in the microcontroller as default values.