Abstract: A method for increasing the control response of a drive train of a machine tool or production machine with backlash and/or elasticity is described. A combined signal comprised of the motor speed measured on the motor and the load speed measured near the load of the drive train is supplied to a controller. The combined signal can generated in one of two ways: (1) by weighting the measured motor speed with a first multiplication factor (&agr;), by weighting the measured load speed with a second multiplication factor (1−&agr;), and by subsequently adding the weighted motor speed to the weighted load speed; or (2) by first subtracting the measured load speed from the measured motor speed, then weighting the resulting difference by a multiplication factor &agr;, and finally adding the load speed to the weighted difference.

Abstract: A multiphase motor has a plurality of ferromagnetically isolated stator electromagnets distributed about an axis of rotation. Successive ranges of speed during which the motor can be expected to operate are defined. A specific subset of the electromagnets is associated for each speed range, each specific subset comprising a different combination of electromagnets. Respective voltage magnitudes to be applied to each phase winding for each defined speed range are predefined. The motor speed is sensed throughout motor operation. In each defined speed range, only the electromagnets of the associated subset are energized, each of the energized electromagnets having applied thereto a different predefined voltage magnitude.

Abstract: A method for controlling speed in a pulse-width-modulation-controlled motor powered by a load voltage source is provided. The method includes the steps of measuring the motor load voltage, and setting a pulse-width-modulation duty cycle based on the measured voltage.

Abstract: A ventilator having a muting device includes a central processing unit, and a fan motor. The fan motor is connected to a start capacitor which is electrically connected to a temperature sensing circuit which is electrically connected to the central processing unit, so that the start capacitor can indicate a signal on a panel of the ventilator, so as to control a rotational speed of the fan motor. Thus, the operation state of each part of the ventilator is indicated on the panel of the ventilator clearly to facilitate inspection of the user, so that the user can control the rotational speed of the fan motor to a proper value, thereby reducing the noise during operation, so as to achieve a muting effect.

Abstract: A ventilator having an abnormal operation indication device includes a power supply circuit, a central processing unit, a fan motor, and a load sensing circuit. Thus, the load sensing circuit detects the abnormal operation signals through the sensor, so that the abnormal operation indication lamp on the panel of the ventilator lights, so as to indicate that the part of the ventilator is disposed at an abnormal operation state and needs to be inspected and amended, thereby facilitating inspection and maintenance of the parts of the ventilator.

Abstract: Systems and methods are described for improving the performance of electric motors which employ commutators and brushes. A method includes improving the performance of an electric motor that employs a commutator and brushes comprising: sending power to the motor, reading a set of data from the motor using an analog to digital converter and a microcontroller configured to execute digital signal processing software, setting a speed for the motor, and maintaining the speed for the motor based on the set of data as analyzed by the microcontroller.

Abstract: A windowlift control system 10 is provided for controlling movement of a window of a vehicle. The system 10 includes a DC bush motor 12 constructed and arranged to cause movement of the window up and down, and electronics 14 integral with the motor for controlling the motor to selectively move the window up and down. The electronics includes analog obstruction signal inputs 18, 20 for receiving analog obstruction signals from an obstruction sensor 16, associated with the window, that directly senses an obstruction in a travel path of the window. The electronics includes digital obstruction signal inputs 22, 24 for receiving digital obstruction signals from an obstruction sensor 16′, associated with the window, that directly senses an obstruction in a travel path of the window. The electronics also includes switch decoding inputs 23, 25, 27 for signaling a manual or one-touch up mode of operation of the motor to move the window in an upward direction.

Abstract: A rotational speed controller maintains a constant low speed during idling, a constant high speed when a load is applied and controls motor rotational speed in the range between low and high speed to ensure safe operation when used in an electrically powered tool. When the current detection signal output from a current detection circuit is lower than a first predetermined value (during idling), a rotational speed setting circuit outputs a rotational speed setting signal indicating a first rotational speed to drive the motor at a constant low speed. When the current detection signal exceeds a second predetermined value (when a load is applied), the rotational speed setting circuit outputs a rotational speed setting signal indicating the second rotational speed to drive the motor at a constant high speed.

Abstract: A power fan speed controller is capable of adjusting a fan speed synchronously along with the variation of a load power so as to solve the shortcomings of a conventional, unsteady, not precise enough and temperature-controlled fan speed controller. The structure of the present invention detects a power signal at the power source end and converts the power signal into a voltage signal in direct ratio to the power; the voltage signal is transmitted into a comparator to compare with a reference voltage thereby controlling a transistor connected with the fan.

Abstract: A method and an apparatus for precisely controlling the rotation speed of a spindle motor in an optical system according to a given condition are provided. The method involves counting in response to a clock signal widths of first and second logic states of an input signal, which varies with rotation speed of the spindle motor, when an operation control command is issued, comparing a predetermined reference value with a count value for one check cycle, and outputting the comparison result; and controlling the constant linear velocity of the spindle motor in response to the comparison result.

Abstract: An electric motor position control apparatus in accordance with the present invention has a plurality of sets of control parameters including at least the proportional gain of a position control section and the proportional gain of a speed control section beforehand, wherein set selection and the measurement of the response state of an electric motor to a position command at the time when the electric motor is controlled by using the control parameters of the selected set are carried out sequentially, one preferable set is selected depending on the measured response state, the control parameters of the selected set are set, and the control parameters are changed as a set.

Abstract: A conveyor system for transported goods which are transported with a preset transport speed and method for operating the conveyor system are described. The individual conveyers of the system are driven by asynchronous motors. Sensors associated with the conveyors measure the actual transport speed of the transported goods on conveyors to determine the dependence of the actual transport speed on the load, such as the weight of the transported goods. A controller adjusts the speed of the conveyors based on the signals received from the sensors.

Abstract: A non-linear, semi-parametric neural network-based adaptive filter is utilized to determine the dynamic speed of a rotating rotor within an induction motor, without the explicit use of a speed sensor, such as a tachometer, is disclosed. The neural network-based filter is developed using actual motor current measurements, voltage measurements, and nameplate information. The neural network-based adaptive filter is trained using an estimated speed calculator derived from the actual current and voltage measurements. The neural network-based adaptive filter uses voltage and current measurements to determine the instantaneous speed of a rotating rotor. The neural network-based adaptive filter also includes an on-line adaptation scheme that permits the filter to be readily adapted for new operating conditions during operations.

Abstract: An electronically commutatable motor, whose excitation windings are controllable via semiconductor output stages by an electronic control unit with the aid of PWM control signals, a setpoint value being specifiable to the control unit, and the control unit emitting corresponding PWM control signals to the semiconductor output stages; a motor characteristic curve, from which an assigned nominal operating speed is derivable for the setpoint value being stored in the control unit, and the derived nominal operating speed being able to be compared to the actual speed of the motor. It a predefinable or predefined speed difference between the nominal operating speed and the actual speed is exceeded, the control unit and/or the semiconductor output stages can be switched off. The derivation of the nominal operating speed for the predefined setpoint value is facilitated by a three-dimensional characteristics field determined by four coordinate points.

Abstract: An electronically commutatable motor, in particular for a fluid pump, includes excitation windings that may be connected to and disconnected from a DC supply voltage via semiconductor switches that are controlled by control signals of a commutation device. Additional closed- and/or open-loop control of the output of the motor, is obtained with a temperature protection system in that the control signals of the commutation device are clocked by pulse width modulatable output signals of a PWM generator and in that the pulse width ratio of the output signals of the PWM generator may additionally be modified as a function of the output signal of the temperature sensor.

Abstract: PWM AC power is supplied to an induction motor or other AC load. The frequency and magnitude of the waveforms is controlled by detecting the peak voltage or width of the reverse EMF pulses at the commencement of the power waveform applied to the load, and then adjusting the applied AC power based on the detected peak voltage or width. Alternatively, the depth of width of a notch that follows the reverse EMF pulse can be detected and used to control the applied AC power.

Abstract: Temperature-based cooling fan control structure mainly including a thermistor for measuring ambient temperature, a voltage amplification system to indicate voltage needed for the cooling fan to rotate under the measured temperature, a magnetic induction system, a rotating speed control system for adjusting the fan rotating speed, a timing trigger capacitor periodically actuating the cooling fan to rotate when the fan is temporarily stopped under an external force, a rectification system protecting all elements in the control structure against damage due to extreme changes in voltage and current, and a voltage-stabilizing control system reducing electromagnetic noise produced in the magnetic induction system.

Abstract: An apparatus for controlling a driving speed of a motor comprises a motor controller provided in the motor controlling apparatus detecting the motor driving speed in response to pulses outputted from an encoder. The motor controller adjusts a detection period for the pulses according to the motor driving speed, thereby measuring the motor driving speed. The motor controller sets the detection period so that a number of four-multiplied pulses can be a multiple of four. Although a phase difference between pulses outputted from an encoder is not constant, the motor controlling apparatus can obtain a desired response characteristic by excluding effects of a phase error between the pulses.

Abstract: An electronically commutatable motor, whose excitation windings are controllable via semiconductor output stages by an electronic control unit with the aid of PWM control signals, a setpoint value being specifiable to the control unit, and the control unit emitting corresponding PWM control signals to the semiconductor output stages. The start-up of the motor is monitored in a simple manner and an overloading is prevented in that, with the input of the setpoint value and/or the switching on of the control unit and/or the semiconductor output stages, after a predefined or predefinable starting time has expired, a monitoring device monitors the speed of the motor to check whether a minimum speed has been reached, and if the minimum speed is not reached, the control unit and/or the semiconductor output stages is/are disconnectible.

Abstract: The system is operable to control a robotized gearbox which includes control levers which can be displaced along at least one working line along which a plurality of nominal operating positions are defined which correspond to the speed ratios or gears and to a neutral position.

Abstract: The present invention discloses devices and methods for improved starting and stopping of rotary motors. A rotary electrical machine (3) is supplied with a voltage from a voltage supply (10). The magnitude of a phase current is measured. The measured cuurent value (IM) and applied voltage (U) is compared with what is expected for a predetermined target slip (ST), by means of a relation between phase current, applied voltage and slip. The comparison gives a discrepancy value, which is used to create a regulation signal (&Dgr;U) to the voltage supply (10). To start and stop the machine, the target slip is increased and decreased, respectively, in a predetermined manner. The means for regulation may be provided as a separate add-on unit to existing soft starter equipment.

Abstract: In a motor rotation rate detecting circuit incorporating a conventional differentiating circuit, raising the upper limit of the differentiating operation frequency of the differentiating circuit to cope with an increased range of the motor rotation rate causes the differentiating circuit to amplify high-frequency noise when the motor is rotating at a low rate. To solve this problem, a motor rotation rate detecting circuit embodying the invention incorporates a differentiating circuit that produces a rotation rate detection signal by differentiating a plurality of alternating signals having different phases that are output according to the rotation position of the motor, and the frequency response of the differentiating operation of the differentiating circuit is switchable according to the voltage of the rotation rate detection signal.

Abstract: A vehicle seat includes a seat movable along a path a motor for driving the seat on the path, a sensor generating a signal indicating movement of the seat on the path, and a controller operating the motor to move said seat along the path. The sensor is preferably a Hall-effect device or a potentiometer. The controller is in communication with the sensor to receive the signal and form a feed-back control loop. The controller accelerates the seat at a controlled rate of acceleration to a controlled constant speed and decelerates the seat from the constant speed at a controlled rate of deceleration. The controller controls the rate of acceleration of the seat at a stored predetermined rate of acceleration by adjusting operation of the motor to maintain the predetermined rate of acceleration.

Abstract: A printer and a method of driving a cooling fan of the printer include a storage unit temporarily stores printing option data and image data, and a control unit controls an operation of a printing unit in one of a warming-up mode, a standby mode, a printing mode and a sleep mode based on the printing option data and the image data as inputted into the control unit. The control unit outputs a control signal variably controlling an RPM (Rotation Per Minute) of the cooling fan based on the operation mode and a printing speed of the printing unit. A cooling fan driving unit drives the cooling fan at a different RPM based on the control signal input from the control unit. Accordingly, the printer and the method of driving the cooling fan of the printer are capable of shortening the warming-up time to increase an initial printing speed, preventing the printing unit from being overheated, extending a lifespan of the cooling fan, and reducing a power consumption.

Abstract: A cooling fan includes a fan, a motor a motor coupled to the fan to drive the fan and a microcontroller. The microcontroller is connected to the motor and is capable of detecting a speed of the fan in real time and maintaining a constant speed of the fan regardless of changes in input voltage.

Abstract: A cooling fan includes a fan module, a microcontroller, and a bus interface. The microcontroller is in communication with the fan module and stores data regarding the cooling fan including at least one of a part number, a fan manufacturer, and a manufacturing date. The bus interface is in communication with the microcontroller to output the data regarding the cooling fan.

Abstract: A controller K calculates a command torque by correcting the required torque w1 with a correction based on a motor rotation speed Nm, and controls an electric motor based on the command torque T. The command torque w1 is regarded as one content of an outside input W to the controller K. A difference between the rotation speed of the electric motor outputted by the actual model describing an actual response of the electric motor and another rotation speed of the electric motor outputted by a reference model describing ideal performance and vibration reduction is regarded as one content Z1 of controlled output Z from the controller K. Moreover, a characteristic variation depending on vehicle types and so on, a torque ripple, and a sensor noise are described by weight functions wm1, wm2 and wn. Then a pertubative output w2 and a sensor noise w3 are regarded as the remaining contents of the input W. An output of the weight function wm2 is regarded as the controlled output Z.

Abstract: A self-diagnosis device is provided with a fan motor having a stator on which a stator coil is mounted, a rotor having a permanent magnet and a fan, a Hall device for detecting magnetic pole position of the permanent magnet and a current control device for controlling rotation of the rotor by controlling current fed to the stator coil. The self-diagnosis device judges if the fan motor has exceeded its service life. Further, the self-diagnosis device interrupts the current fed to the stator coil when the rotational speed is higher than an allowable value, and restarts the current automatically to return the fan motor into normal operation when the rotational speed is not higher than the allowable value.

Abstract: A DC electric motor includes an internal programmable element that permits it to be synchronized to an external reference signal. To that end, the motor includes a rotor capable of rotating at a rotational speed, rotor circuitry that controls the rotational speed of the rotor, and an input to receive the noted external reference signal, which indicates a preset speed. In addition, the motor also includes the noted programmable element, which is operatively coupled with the input and the rotor circuitry within the motor. The programmable element is capable of comparing the external reference signal with the rotational speed of the rotor and, consequently, controls the rotor circuitry based upon the comparison of the external reference signal and the rotational speed of the rotor.

Abstract: A method for controlling heat dissipation of an electronic device, such as a central processing unit, by controlling rotational speed of a fan and supplying a clock signal with slower clock frequency to the electronic device is disclosed. The fan rotates at a speed in proportion to the temperature of the electronic device when the temperature of the electronic device is below a maximum reference temperature. The fan rotates at a maximum rotational speed when the temperature of the electronic device is beyond the maximum reference temperature. The fan rotates at a maximum rotational speed and a clock signal with slower clock frequency is supplied to the electronic device when the temperature of the electronic device is beyond both the maximum reference temperature and a slowing-clock starting reference temperature, until the temperature of the electronic device drops below a slowing-clock ending reference temperature.

Abstract: The method of electronically monitoring and controlling a process for moving and/or positioning at least one window and/or sunroof of a motor vehicle to provide protection from pinching includes supplying an input variable, for example drive voltage, and an output variable, for example window position, to a detection device; storing a model in the form of a differential equation describing the process for moving and/or positioning the window and/or sunroof in terms of process parameters in the detection device; optimizing the process parameters of the model according to the input and output variables and storing values of the optimized process parameters in the detection device for the purpose of monitoring; continually evaluating current values of the process parameters obtained by the optimizing by comparing the current values with the stored values; calculating a process correcting quantity in the detection device for adjusting the window and/or sunroof according to the comparing and influencing the proces

Abstract: A rotary electric machine having a plurality of rotors is driven by a compound current. A voltage to be applied to a stator of the rotary electric machine is in the form of a compound rectangular or stepwise voltage composed of a plurality of superposed components each of which is a rectangular or stepwise wave having a frequency corresponding to the revolution speed of a unique one of the rotors.

Abstract: A fan rotation rate control device and the method thereof for controlling the rotation rate of the fan are provided. The fan outputs actual rotation rates and the control device includes a fan, a control unit, a processing unit and a thermal sensing unit. The thermal sensing unit is used to sense the temperature inside the heat generating device or the temperature of the heat source therein and outputs thermal sensing signals accordingly; the processing unit is coupled to the thermal sensing unit and receives the thermal sensing signal on which the determination of the preset rotation rate is based. Of which, the control unit which is coupled to the processing unit and the fan receives the preset and the actual rotation rates, while the control unit outputs modulation signals to the fan according to the difference between the actual and the preset rotation rates to achieve a precise control of the fan.

Abstract: A cooling system for a vehicle includes a shroud attachable to a fixed portion of the vehicle. A stator assembly for a brushless DC ring motor is attached to at least one mounting support of the shroud. A cooling fan is piloted on the stator assembly, and includes a ring supporting a plurality of fan blades for sweeping an area inside the shroud. A rotor assembly for the brushless DC ring motor is attached to the ring of the cooling fan. The rotor assembly confronts the stator assembly around an outer diameter of the stator assembly. The cooling system is controlled by an electronic controller to rotate the cooling fan to provide appropriate cooling for the vehicle.

Abstract: According to the present invention, in a water supply apparatus which converts output power of a solar cell with an inverter to drive a motor pump for pumping up water, a DC brushless motor having no sensor for detecting a position of a rotatable shaft is used as a motor for driving the pump.

Abstract: A motor speed control having synchronous PWM signals has a synchronous phase detecting unit and a PWM control unit. The synchronous phase detecting unit detects the phase variation of a Hall signal, which represents the phase change of the motor, and outputs a digital value to the PWM control unit. The PWM control unit compares the digital value with a speed control command so as to obtain a PWM signal, wherein the PWM signal is synchronized with the Hall signal. Since the PWM signal is synchronized with the Hall signal, the motor is operated smoothly even in the low speed rotation, and audible noises are effectively reduced.

Abstract: A DC brushless motor operation speed control method is disclosed. First, a linearly voltage dependent current source is used to charge a capacitor and the terminal voltage of the capacitor is coupled to a linearly voltage dependent base frequency level detector. When the output voltage of the capacitor reaches the base frequency reference voltage, the signal output from the base frequency level detector will make the capacitor discharge, outputting a series of base frequency triangular waves. Under different supply voltages, all the generated base frequency triangular waves have the same cycle time. The base frequency triangular waves are transmitted to a speed control comparator. Through pulse width modulation, the speed control reference voltage adjusts the output pulse width of the comparator and thereby controls the speed of the motor.

Abstract: A method and apparatus for improving the speed measurement quality in systems having multi-pole machines is taught. The method compensates for pole misalignment by moving average techniques.

Abstract: A blender base that may be used with a food processor container, a blender container, and a single use beverage container. The blender container includes a novel blade unit having a food processor-style blade and blender type blades. Programs with preprogrammed motor commands for desired operations are stored in memory and may be selected by a user on a user interface. The user interface may include a liquid crystal display, or function switches and light emitting diodes. Upon selection of a particular pre-defined function, the microcontroller retrieves the appropriate program from the read only memory and specifies the preprogrammed motor commands to accomplish the selected function.

Abstract: When a switch between sine wave voltage drive and rectangular wave voltage drive is effected based upon the motor rotation speed and a motor torque command value, an AC voltage forming an intermediate wave is generated by combining the sine wave and the rectangular wave and is applied to the motor.

Abstract: Apparatus and method for providing digital signal processing method for controlling the speed and phase of a motor involves inputting a reference signal having a frequency and relative phase indicative of a time based signal; modifying the reference signal to introduce a slew-rate limited portion of each cycle of the reference signal; inputting a feedback signal having a frequency and relative phase indicative of the operation of said motor; modifying the feedback signal to introduce a slew-rate limited portion of each cycle of the feedback signal; analyzing the modified reference signal and the modified feedback signal to determine the frequency of the modified reference signal and of the modified feedback signal and said relative phase between said modified reference signal and said modified feedback signal; and outputting control signals to the motor for adjusting said speed and phase of the motor based on the frequency determination and determination of the relative phase.

Abstract: A motor control method and apparatus for stopping an object moved by a motor accurately at a predefined target position, shortening the time period required in stop control, in which the motor is driven at a first (high) speed up to a distance from the target position adequate for stop control and then is sequentially braked to a predetermined speed lower than the first speed, driven at a second (low) speed up to a distance from the target position equal to the stopping distance, and braked to a stop. The method and apparatus are used in a time recorder. An impact printing apparatus is also disclosed with printing pin actuation timing correction dependent upon scanning speed or platen shape, striking duration timing dependent upon scanning rate, or printing pin actuation timing dependent upon stored shift amounts.

Abstract: The wiper control device comprises a wiper motor 52 for moving a wiper, a switch 53 for outputting a signal which inverts at each single sweep of the wiper, a wiper switch circuit 51 of a combination switch which instructs movement of the wiper, a first solid state switching element FET-b which drives the wiper motor, a controller 55 which turns the first solid state switching element on and off intermittently on the basis of the signal from the switch in a case in which intermittent wiper movement is instructed by the combination switch, a second solid state switching element FET-a2 which is connected in series to the first solid state switching element and is turned on by power source voltage, and a third solid state switching element FET-a1 which is connected in series to the second solid state switching element and is for braking the wiper motor.

Abstract: Systems and methods are described for improving the performance of electric motors which employ commutators and brushes. A method includes improving the performance of an electric motor that employs a commutator and brushes comprising: sending power to the motor, reading a set of data from the motor using an analog to digital converter and a microcontroller configured to execute digital signal processing software, setting a speed for the motor, and maintaining the speed for the motor based on the set of data as analyzed by the microcontroller.

Abstract: Method and apparatus for controlling a moving speed of a moving body, wherein at least one transient target speed value in addition to a final target speed value is used to control the moving speed in an accelerating period between a moment of initiation of a movement of the moving body and a moment at which the moving speed should coincide with the final target speed value. The transient target speed is updated at a predetermined timing, or changed to the final target speed value, or from one transient value to another transient value before it is changed to the final target speed value, so that the moving speed is smoothly increased to the final target speed value, without an overshoot beyond the final target speed value.

Abstract: An electric motor drive controller for an electric vehicle driven by a motor with permanent excitation and powered by an energy source comprises: a power control stage coupleable to the motor for generating a drive signal at a voltage to control the motor at a desired speed; a voltage control circuit connectable between the energy source and the power control stage for controlling the voltage of the drive signal at a first voltage potential in one operating mode and at a voltage potential greater than the first voltage potential in another operating mode; and a mode controller for controlling the operating modes of the voltage control circuit based on properties of the drive signal.

Abstract: In a PWM-controlled motor driving device, a phase current is prevented from undergoing an abrupt transition at phase current switching points, thereby reducing vibrations and noise of the motor. A PWM control section produces two independent PWM control pulse signals P1 and P2. Two energized phases, which are determined by an energization switching section, are energized with PWM control in parallel according to the PWM control pulse signals P1 and P2. A comparison section compares a current detection signal DS, which indicates the level of the current flowing through a motor coil, with various torque command signals TQ1, TQ2 and TQ3, which are produced by a torque command signal generation section. A masking section masks comparison results CR1 and CR2 as necessary. Thus, an ON period of the PWM control pulse signal P1 and that of the PWM control pulse signal P2 are determined.

Abstract: A synchronous resolver has: a stator including a plurality of stator poles disposed at regular intervals along the circumferential direction of a ring-shaped stator base portion, the stator poles comprise a plurality of phases; coil bobbins former-wounded stator coils therearound are respectively fitted with and mounted on their associated ones of the stator poles; and, a rotor shiftable in angle with respect to the stator to thereby vary a reluctance component in a gap existing between the stator and the rotor, wherein the coil bobbins are set the positions of the stator coils freely in such a manner that the resolver signals of the respective phases balance well.

Abstract: A motor speed control having synchronous PWM signals has a synchronous phase detecting unit and a PWM control unit. The synchronous phase detecting unit detects the phase variation of a Hall signal, which represents the phase change of the motor, and outputs a digital value to the PWM control unit. The PWM control unit compares the digital value with a speed control command so as to obtain a PWM signal, wherein the PWM signal is synchronized with the Hall signal. Since the PWM signal is synchronized with the Hall signal, the motor is operated smoothly even in the low speed rotation, and audible noises are effectively reduced.

Abstract: The invention relates to a process and device for feedback-controlling the speed of an electric motor (10) driving a rotary machine (6), in particular a pump or fan, according to the capacity requirement at the rotary machine, which is variable with time on the consumer side (4, 8) thereof, using a feedback controller (16) the output of which determines the speed of the electric motor (10). The process according to the invention is characterized in that the electrical power (P) actually taken up by the electric motor (10) is measured and in that a signal representing the electrical power measured is produced and supplied as input to the feedback controller (16), where it is converted into the desired output according to a predetermined or right then calculated characteristic curve (Pinstall(Q)).