Abstract: A method and apparatus for controlling a fan is disclosed. In one embodiment, a method for controlling a fan includes applying power to the fan at startup. The fan may be supplied a predetermined amount of current, which may break the inertia of the fan propeller and begin its rotation. As the propeller begins rotating, the speed at which it rotates may be monitored. The fan startup routine may continue until the fan reaches or exceeds a minimum fan speed threshold. Once the fan has at least reached the minimum speed, the amount of current supplied to the fan may be reduced such that the fan rotates at minimum speed, and an automatic fan control algorithm may begin executing. By reducing the current such that the fan operates at a minimum speed, the amount of audible noise generated by the fan during startup may be kept to a minimum level.

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: The present invention encompasses a high efficiency pulse width modulator comprising: a variable duty cycle oscillator for receiving an input signal and providing a low level switching signal; a source voltage differentiation dependant positive switching signal circuit for receiving the low level switching signal, a stable reference signal, a sample of a positive supply voltage signal, and an error signal and the providing a positive supply switching signal and a reference signal; a positive supply switching circuit for receiving the positive supply switching signal and providing an output signal to an inductive load; an output voltage dependant negative supply switching signal circuit for receiving the output signal and a negative supply voltage signal and providing a negative supply switching signal; a negative supply switching circuit for receiving the negative supply switching signal and providing clamping of the inductive load to the negative supply, an output sourced charge pump for receiving the output

Abstract: In order to design as inexpensively as possible a control device for DC motors which are provided with a commutator for feeding their motor windings which has at least four sliding contacts, this device comprising a modulation stage which generates at least one control signal modulated as to pulse width with a clock frequency substantially above the motor speed and a control circuit which is controlled by the at least one control signal and has at least one load branch which feeds the commutator and is provided with an electronic switch controlled by the control signal modulated as to pulse width, it is suggested that the sliding contacts be combined to form at least two control groups, that the sliding contacts be combined within each control group to form pairs of sliding contacts and that each control group have its own load branch associated with it.

Abstract: A method is disclosed for controlling the commutation in an electronically commutated motor (20) which comprises a stator having at least one phase (24, 26), and a permanent-magnet rotor (22), and with which a current limiter (36, 58) and a controller (18) for regulating a motor variable are associated. The current limiter (36, 58) serves to limit the current (I) in the at least one phase (24, 26) to a setpoint value. The regulation by means of the controller (18) is accomplished by modifying the distance in time (W) between switching on (t1) and switching off (t2) of the current (i1, i2) in the at least one phase. In this method, the setpoint value to which the current limiter limits the current (i1, i2) in the relevant phase is modifiable.

Abstract: A control system for an electric machine having a rotor position sensor that generates a rotor position signal, a velocity module that generates an electric angular velocity value based on the rotor position signal, a random pulse width modulation module that generates a switching period and a delay for a current cycle, and a phase angle compensation module that sums a sample rate, one half of the switching period, and the delay of a previous cycle and that outputs a delay time. The phase angle compensation module further multiplies the delay time and the electric angular velocity value and generates a compensating angle.

Abstract: A drive current or a drive voltage is controlled corresponding to change of load by sampling the drive current or drive voltage of a motor to move an optical pickup and then detecting change of the sampling signal as change of the optical pickup when it is moved. Moreover, change of the sampling signal is obtained from a difference of the sampling signals by comparing these sampling signals at the first and second points. Comparison of these sampling signals is conducted in unit of drive pulse.

Abstract: A commutation and velocity control system of a brushless DC motor receives a velocity command signal and provides command signals to drive the brushless DC motor. The system includes a summer that receives the velocity command signal and a velocity feedback signal and provides a velocity error signal indicative of the difference. A velocity loop compensator receives said velocity error signal and provides a compensated velocity error signal. A magnitude sensing circuit senses the magnitude of said compensated velocity error signal and provides a velocity magnitude signal indicative thereof. A polarity sensing circuit senses the polarity of the said compensated velocity error signal and provides a velocity polarity signal indicative thereof.

Abstract: In order to improve a control device for operating a load circuit having at least one electric motor, this control device comprising a control stage which generates a pulse width modulated control signal, a power stage supplying the load circuit and having an electronic switch activated by the pulse width modulated control signal, a freewheeling element connected in parallel to the load circuit and a blocking monitoring means which generates a measurement switch-off interval by suppressing at least one switch-on interval of the pulse width modulated control signal, monitors the voltage in the load circuit during the measurement switch-off interval, compares it to a limit value and generates a blocking state signal in accordance with the comparison, in such a manner that a differentiated analysis of the voltages occurring in the measurement switch-off interval is possible it is suggested that for monitoring at least two electric motors connected in parallel in the load circuit the blocking monitoring means car

Abstract: There is provided a brushless DC fan motor which can eliminate an oscillator for PWM, control the motor speed at a low cost with high accuracy, and efficiently adjust the temperature in a housing for electronic appliances when radiating the heat in the housing. The brushless DC fan motor with the rotational speed thereof controlled by controlling the voltage of a control input terminal of a drive circuit comprises a differential amplifier in which the voltage signal for controlling the speed is inputted in a first input terminal and the reference voltage signal is inputted in a second input terminal. The differential amplifier is linear in the input-output characteristic, and can set the rise characteristic of a desired gradient, and control the motor speed with high accuracy without using the PWM signal for the input signal. The voltage signal from the output terminal of the differential amplifier is given to the control input terminal of the drive circuit.

Abstract: A device for driving electric motors includes a power stage with a variable duty-cycle coupled to a supply voltage. The power stage is suitable for driving an electric motor. The driving device includes a circuit that is capable of raising the value of the input voltage of the power stage above the induced counter electromotive voltage of the motor in certain periods of time and a control device capable of activating the circuit in reply to values of the induced counter electromotive voltage being greater than or comparable with the supply voltage.

Abstract: A power tool such as an electric drill typically contains a gear train that couples the output spindle of the motor to the tool bit-receiving chuck. The control circuit for the power tool is operable in a ratcheting or pulse mode that causes the output spindle to rotate in discrete incremental amounts. Corresponding methods for controlling the operation of the electric motor of a power tool are also disclosed.

Abstract: An electronically commutated direct current machine comprising a rotor and a stator has a stator winding arrangement that can be supplied, via a full bridge circuit (78), with current from a direct current source (73, 74). A commutation arrangement (49, 50, 52, 54) is provided for commutating the semiconductor switches (1) (80 through 85) and is embodied in order, as a function of at least the position of the rotor (110), in a first bridge arm to switch on only one semiconductor switch in each case, and in a second bridge arm, controlled by a switching signal (PWM2), alternatingly to switch on and off a semiconductor switch associated with the switched-on semiconductor switch of the first bridge arm. Also provided is an arrangement for generating a switching definition signal (PWM1) which, by way of its magnitude, controls the pulse duty factor for the alternating switching on and off of the semiconductor switch associated with the first bridge arm.

Abstract: In a method for commutating an electronically commutated motor, a predictive calculation is made of a first time span that the rotor will need in order to pass through a specified rotation angle that lies between a first rotational position (∂0) and a later second rotational position (∂1) at which a switching operation is to be effected in the motor. Upon actual passage through the first rotational position, a reference time is identified and stored. The time difference between the present time and the stored reference time is then monitored repeatedly and compared to the first time span; and when a specified relationship exists between the time difference and the first time span, the switching operation is performed.

Abstract: An apparatus for controlling a rotational speed of a motor, coupled to a sensing unit capable of outputting a sensing signal. The apparatus includes a controlling unit, coupled to the sensing unit, for outputting a controlling signal according to the sensing signal and independently of the rotational speed of the motor. The controlling signal is a square wave and has a duty ratio that is determined by the sensing signal. The apparatus also includes a driving unit, coupled to the controlling unit, for outputting a driving signal to a motor rotor according to the duty ratio of the controlling signal. The driving signal also is a square wave. The rotational speed of the motor rotor is determined by the duty ratio of the driving signal.

Abstract: A laser level with a sensorless DC motor controller having a feedback sampling circuit connected in parallel with the coil to sense back EMF. An integrator provides a feedback signal from the sensed back EMF, which the amplified difference from a reference level is used as a pulse width control signal. A pulse width modulation generator uses the control signal to generate variable “on” time pulse widths for each motor drive pulse such that high resolution is provided to the DC motor, permitting accurate rotor position at low rotational speeds. It is emphasized that this abstract is provided to comply with the rules requiring an abstract to allow a searcher or other reader to quickly ascertain the subject matter of the technical disclosure. It is submitted with the understanding that is will not be used to interpret or limit the scope or meaning of the claims.

Abstract: The present invention provides a method for shifting the instant of commutation for a sensorless and brushless direct-current motor (1), whose stator windings are fed by a multi-phase converter connection. The converter connection includes an output stage control (2), a commutation logic (3), a phase selector (4), and phase discriminator (5). A commutation detection (6) is supplied at one input (46) with the instantaneous value of the voltage induced in a phase, the instantaneous value being determined by the phase selector, and at a second input (47), with a reference voltage (Uref) for comparison. The reference voltage (Uref) can be changed by a commutation shift (7) in correspondence with a specific characteristic curve (71). A manipulated variable (Ust) is supplied by a manipulated-variable calculation (8) to the commutation shift (7) as a function of the setpoint speed (Nsetpoint) of the motor. The commutation shift takes place in an advantageous manner in a parabola shape.

Abstract: Disclosed is a circuit for regulating a power supply. In one embodiment, the circuit includes a signal generator for generating a square wave signal that varies in magnitude between a first voltage and a second voltage, and a voltage regulation circuit. A duty cycle of the square wave generated by the signal generator varies according to a signal provided to the signal generator. The voltage regulation circuit, coupled to the signal generator, outputs a DC voltage in response to the circuit receiving the square wave signal. The magnitude of the DC voltage varies between the first voltage and a third voltage, wherein the third voltage is greater than the second voltage, and wherein the magnitude of the DC voltage varies directly with the duty cycle of the square wave signal.

Abstract: A method for maintaining a target speed of a DC motor includes the steps of obtaining a feedback signal from the motor corresponding to motor speed, measuring an actual time for a predetermined number of feedback pulses to be received, comparing the actual measured time with an expected time for the feedback pulses to be received when the rotor shaft is operating at the target speed, and adjusting the controller pulse-width variable signal in response to the compared actual time to the expected time. The drive signal is generated and adjusted by a microprocessor in response to the feedback pulses generated by a feedback element coupled to the motor.

Abstract: The invention relates to a method for control of the speed of rotation of a separately excited direct current motor for model vehicles, the speed of rotation of the motor being controlled by means of a pulse sequence, the motor being alternately supplied with a supply voltage during a switch-on period and disconnected from the supply voltage during a switch-off period, the duration of the switch-off period being dependent on the deviation of an actual value from a set value for the speed of rotation of the motor. In order to further develop the method in such a way that the separately excited motor has a low noise output and stable control is possible over a wide range of speed of rotation, it is proposed that a pulse width modulated signal is provided, the pulse width of which is dependent on the average torque loading of the motor, and that the pulse width modulated signal is combined with the pulse sequence by an AND-operation.

Abstract: The speed of a fan motor is controlled by varying a DC voltage to the fan motor. A series pass transistor is used to vary the DC voltage to the fan motor. A power management controller sets the fan motor speed by outputting pulses to a pulse-to-DC voltage converter that changes the pulses to a proportional DC control voltage for controlling the series pass transistor. A tachometer output amplifier circuit is used to remove DC components and amplify to useful logic levels a low level tachometer output signal from the fan motor. The amplified tachometer signal is used by the power management controller in controlling the rotational speed of the fan motor.

Abstract: A method of controlling a DC servomotor for driving a driven member coupled by a wire to an operation member of a valve, wherein, at the start of a control, the motor is driven first to rotate the operation shaft of the valve to a limit position after the motor stops, a driving current of the motor is gradually reduced to return slowly the driven member by a tension of the wire, and a position of the driven member when the driving current of the motor becomes zero is stored as a final stop position, thereafter, a rotational range of the driven member is limited to the range between these final stop positions when the position of the driven member is controlled to coincide with a target position.

Abstract: A system and method of advancing the commutation sequence of a brushless DC motor is provided. The motor having a plurality of coils, each of the coils coupled together at one end to a common center tap and coupled at an opposite end, through a respective coil tap, to both a source voltage and ground via selectively actuateable switches having diodes coupled in parallel therewith. The motor operates in a pulse width modulation (PWM) mode having PWM-on states and PWM-off states. During PWM-off states, a coil tap voltage from the coil tap of a floating phase is provided to a preconditioning circuit. The preconditioning circuit adjusts the floating phase coil tap voltage to compensate for an amount of voltage substantially equal to an amount of voltage by which a voltage at the center tap deviates from zero. The preconditioning circuit further includes sharpening circuitry for amplifying the adjusted floating phase coil tap voltage.

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: PWM controlling means (4) for inputting PWM signals corresponding to PWM target values to electric power supplier (3) in order to servo-controlling DC motor (2) comprises synchronizing control part (41), PWM computing part (50), selecting part of PWM target value (45) and PWM commanding part (46). The synchronizing control part (41) instructs the commencement of the PWM computation, selection of PWM target value and PWM command allotted to some of the infinitesimal intervals obtained by dividing processing term, on which PWM signals regulating the electric power supplied to the motor (2) are allotted, into n equal parts, and terminates one cycle for a series of the process and/or computation predetermined within one processing term. PWM target values corresponding to plural control target values (DP0, DV0, DT0) are computed in parallel so that the servo-control of motor can be operated in quick response to the change of control mode.

Abstract: An electronically switched motor includes a stator-rotor assembly fitted with three-phase driving windings, a series of switches for powering the windings, and a control circuit suitable for regulating a speed of the motor as a function of a reference speed and a measured speed. The control circuit includes switch control elements to cause each switch to switch on and off in compliance with a repeated sequence selected to power the driving windings as a function of the reference speed and the measured speed. The sequence includes a succession of on/off pulses with a duty ratio. The control circuit is suitable for generating a first switch control mode for controlling the switches so that the switches are in an ON state or receive a succession of ON pulses over a first activation period and a second switch control mode for controlling the switches so that the switches are in an ON state or receive a succession of ON pulses over a second activation period larger than the first activation period.

Abstract: A method for reducing a torque ripple of a Switched Reluctance Motor for detecting a position of the rotor using a position detection sensor, designing a pulse width if a position detection signal as an optimum one and decreasing a torque ripple of the motor by adjusting a duty rate of the pulse width modulation signal comprises the steps of setting a pulse width of a position detection signal in accordance with a position detection result of a motor rotor, outputting a signal for controlling of each phase in synchronization with a rising and falling edge of the position detection signal, and varying and outputting a duty rate of a pulse width modulation signal from the moment that a falling edge of the position detection signal is detected thus to have advantage of decreasing more than fifty percents of the torque ripple.

Abstract: A motor rotational pulse generating circuit for a motor is provided which generates a correct pulse signal even at an initial turning-on stage of the motor, by adjusting a filter cutoff frequency in response to motor rotational condition. The motor rotational pulse generating circuit includes a rotational pulse generation circuit 20 which generates ripple pulses based on a signal being inputted from the DC motor 1, in which a ripple is superposed whose frequency is in proportion to a rotation number of the DC motor 1. A filter 3 makes a cutoff frequency variable on the basis of a clock signal issued from a PLL circuit 6. An oscillation frequency at an oscillator VCO10 is determined by the ripple pulses and a motor rotation condition signal inputted by way of circuits 12 to 16 inclusive. A microcomputer 20 operates, when the motor is turned on, to cause the oscillator VCO10 to issue a preliminary clock signal.

Abstract: A motor driving system is disclosed. The circuit includes a power converter for supplying a brushless motor having a permanent magnetic rotor with pulse-width modulation controlled driving power, a magnetic-pole position detector for detecting a magnetic-pole position of the motor rotor, a speed detector for detecting a rotational speed of the motor according to an output signal of the magnetic-pole position detector, a speed controller for outputting a deviation of an output signal of the rotational speed detector from a speed instruction, an instruction signal generating circuit for generating a plurality of instruction signals in response to an output signal of the speed controller, a circuit for generating modulated waves by selecting one of the plurality of instruction signals according to the magnetic-pole position of the motor, and a driving ct for controlling the power converter by means of pulse width modulation according to the modulated waves.

Abstract: A motor controller for a three-phase spindle motor used in the hard disc drive provides pulse width modulated (PWM) signals used to drive the motor. The PWM signals have duty cycles which are a function of rotational position of the motor, a magnitude control signal, a stored set of main waveform coefficients, a stored set of modifier coefficients, and a modifier signal. By varying the modifier signal, the duty cycle of the PWM signals can be varied to adjust the shape of the motor current waveform to match the torque profile of the motor.

Abstract: A method of measuring impedance is based on carrier function Laplace transform. The measurement includes detecting a response signal from a device under test, to which signal an excitation such as a pulse, interrupt or constant load is applied. Resulting data is fitted to a carrier function, selected so as to be capable of providing a good fit and for which an analytical Laplace transform is known, in order to obtain parameters of such function providing best fit. Obtained parameters are further substituted into the analytical expression of Laplace transform of carrier function which is used to calculate a frequency dependent impedance function in the Laplace domain. The resulting impedance function is used for calculating the impedance spectrum in a frequency domain and for calculating the measurement error of the frequency domain impedance spectrum using the standard deviations of the parameters, obtained during fitting of time-domain data.

Abstract: A brushless DC motor modifies motor commutation events to reduce noise by providing overlapping activation of the switch being deactivated with the switch being newly activated so that three switches are temporarily activated. The newly activated switch is pulse width modulated with a motor torque controlling duty cycle, and the switch being deactivated is pulse width modulated synchronously with the newly activated switch but with a duty cycle decreasing from the torque controlling duty cycle. The decreasing modulation of the switch being deactivated allows a slower current decrease in the phase turning off to reduce or eliminate the disturbances, and thus the noise. The decreasing modulation is preferably exponential in manner, with a time constant varying inversely with motor speed so that the duty cycle reaches a predetermined minimum in a predetermined maximum number of motor electrical degrees.

Abstract: A method for braking a washing machine in accordance with the present invention comprising the steps of: setting up an initial data of a duty ratio corresponding to a detected speed and a rotating position; discharging a voltage of the capacitor filter during a duty-on cycle according to the duty ratio set up in the preceding step; and charging a voltage to the capacitor filter during duty-off cycle when the duty-on cycle of the preceding step is finished. As described above, the dynamic braking resistor is not used in the method for braking the washing machine according to the present invention so that the size and the production cost are reduced.

Abstract: A pulse width modulation circuit (10) for a motor controller is operated by generating an offset voltage and adding the offset voltage to a carrier timing signal to form an offset carrier timing signal. The operation of each of the phases of the motor is controlled as a function of the offset carrier signal.

Abstract: A speed control device particularly adapted for use with electrical motor-driven hand tools has digital operator input controls. A semiconductor switching device controls a percentage of ON time for the electric motor in the hand tool. Discrete and repeatable settings are selectable to a user through digital input switches.

Abstract: A power tool such as an electric drill typically contains a gear train that couples the output spindle of the motor to the tool bit-receiving chuck and has associated therewith a degree of looseness which must be taken up before torque from the motor is applied to the tool bit. The control circuit for the power tool increases the effective torque output of the tool after a predetermined torque level is attained, by alternately turning the motor on and off, with the duration of the off-time sufficient to permit the gear train to relax, thus giving the motor a “running start” when power is reapplied. Various alternative schemes for transitioning to this ratcheting mode of operation are disclosed including the sensing of a predetermined threshold current, a predetermined increase in motor current, and a predetermined rate of deceleration in motor speed.

Abstract: The invention relates to an electric drive device with a DC motor (2) comprising a control circuit with an electronic commutator (3). The invention is characterized in that a derivation of a control signal (V_i_ref) is obtained from an induced motor voltage (E_sample) detected by a measuring device and from a reference value (V_i_av) which serves to regulate the speed of the DC motor (2), and in that the derived control signal (V_i_ref) serves to achieve a substantially constant torque of the DC motor (2) through adjustment of the motor currents (ia, ib, ic).

Abstract: A fan motor whose speed is controlled by an operating period of pulse waves includes first and second rectifying circuits, a voltage comparison circuit, and a differential amplifier. A pulse wave is inputted into the first rectifying circuit, an actual speed signal detected from the fan is inputted into the second rectifying circuit, and the pulse wave and the speed signal are compared in the voltage comparison circuit. After comparison, a comparison voltage is outputted to a negative terminal of the differential amplifier. A partial voltage from a source voltage is connected to a positive terminal of the differential amplifier. The differential amplifier outputs a drive voltage after calculating a voltage difference between the comparison voltage and the partial voltage. Speed of the fan is changed in response to a change in the value of the drive voltage.

Abstract: There is provided a DC motor control system and method which is capable of carrying out an accurate rotation control of a DC motor even when the power supply voltage thereof is reduced. A detection signal indicative of a detected number of rotations of the DC motor is delivered. Stop control is carried out for stopping the DC motor by braking rotation of the DC motor when the number of rotations of the DC motor indicated by the detection signal has reached a predetermined number of rotations.

Abstract: A battery pack includes a plurality of electrochemical cells and a control circuit. The battery pack provides power to a tool in the form of a pulse width modulated waveform. The plurality of electrochemical cells provide a total output voltage. The control circuit is coupled to the plurality of electrochemical cells and receives a trigger signal from the tool. In response to the trigger signal, the control circuit determines whether a pulse width of the pulse width modulated waveform requires adjustment. Additionally, the control circuit can be configured to receive an indication of the total output voltage. In this case, the control circuit determines whether the pulse width of the pulse width modulated waveform requires adjustment based on the level of the total output voltage.

Abstract: A brushless DC motor system in which PWM current control is performed by chopping the high-side driver during one half of a single cycle, and chopping the low-side driver during one half of a single cycle.

Abstract: A brushless repulsion motor which includes a stator and rotor rotatably mounted on the stator is provided. The stator and rotor are contained within a first housing, the stator having at least one pair of poles, a field winding on the stator for producing a field on the stator, and a plurality of coils on the rotor adapted to electromagnetically interact with the field of the stator winding. Switches are located on the rotor shaft outside the first housing to selectively short successive ones of the coils when the coils are in a preferred angular position relative to the stator poles. Thus, the stator field is effective to induce a current in the rotor and produce a resultant relative rotation between the rotor and the stator which can be controlled by non-contact signaling means which activate the switches.

Abstract: To keep low the cross frequency of current feedback control and provide a good steering feeling, a first operation expression is selected when a difference &xgr; between a current instruction value computed based on a steering state of a steering wheel and a traveling state of a vehicle and a motor drive current value supplied from a battery to a motor for providing assist force to a system for transmitting power from the steering wheel to the wheels is larger than a predetermined value Th1, a second operation expression is selected when the difference &xgr; is smaller than the predetermined value Th1, and the difference &xgr; is corrected using the selected operation expression.

Abstract: A method and circuit for operating a polyphase dc motor in which discontinuous sinusoidal drive voltages are applied to the windings of the motor in predetermined phases. The discontinuous portion of the sinusoid is timed with the bemf zero crossings. Bemf zero crossings are detected, and phases of the drive voltages are adjusted to have zero crossings substantially in the discontinuities of the drive voltages. The method and circuit result in motor operation with significantly reduced acoustic motor noise.

Abstract: An electric circuit for determining the load current of a clocked load having at least one inductive component and being assigned a free-wheeling circuit has a shunt whose voltage drop is used to determine the current. The shunt is arranged in the free-wheeling circuit to determine the free-wheeling current which is used as a measure for determining the load current (motor current). Furthermore, according to another embodiments the shunt is in series with the load and the free-wheeling circuit is arranged in parallel to the series connection of load and shunt.

Abstract: A speed control device for an electric motor fed by a direct voltage source, the device comprising a controlled switch by which the motor voltage is alternately switched on and off under the control of a modulated switching pulse sequence. The switching frequency is higher than the frequency corresponding to the time constant of the electric motor. The switched motor voltage is regulated to a voltage set value corresponding to a desired motor speed by influencing the modulated switching pulse sequence.

Abstract: The process makes it possible to detect the speed of rotation of a DC electric motor comprised of at least one winding connectable to a DC voltage supply source via an electronic switch with which there is associated a control circuit operable to provide a pulse width modulated square-wave control signal. The process comprises the operation of interrupting the application of the said control system to the electronic switch for a time period of pre-determined duration, acquiring during this time period a signal correlated to the voltage on the said winding and detecting at least one pre-determined characteristic of this signal in dependence on the speed of rotation of the motor.

Abstract: A load control system includes a driving circuit for electrically controlling a blower motor, and a control circuit for generating a control signal for the motor. The driving circuit is directly connected to an electrical power source, and the control signal from the control circuit is input into the driving circuit through a signal input line. The control signal from the control circuit is a duty signal in which a duty ratio becomes 100% when the signal input line is ground short-circuited. In the load control system, a comparison circuit determines a ground short-circuited state of the signal input line when the duty ratio is increased to a value proximate to 100%, and the motor is automatically stopped based on output from the comparison circuit when the signal input line is ground short-circuited. Thus, the load control system can prevent full-load operation of the motor due to the ground short-circuit of the signal input line, even the driving circuit is directly connected to the electrical power source.

Abstract: A control circuit for regulating the rotational speed of a DC brushless motor includes an electrical conduction switch having an input, an output and a control terminal for passing a motor supply signal to a DC brushless motor. A voltage averaging circuit generates an averaged signal indicative of the average voltage level being supplied to the motor. The averaging circuit informs an error amplifier to modulate the motor supply signal to compensate for changes in the voltage level of the motor supply signal in order to maintain the rotational speed of the motor at a generally constant rpm. The control circuit takes advantage of the motor windings and rotor mass as a filter circuit to smooth changes in current drawn by the motor, and to further maintain the rotational speed of the motor.

Abstract: Apparatus providing a control and protection arrangement for walking/running exercise machines which is effective to provide protection against malfunction conditions which may be experienced by the exercise machines, to thereby protect users of the exercise machine against injuries. The present invention provides an efficient response time to motor speed variations to provide greater user safety.