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 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 an electronically commutated DC motor (10) having a multiphase stator winding (11) which has an even number m of winding phases (111-114) which are each connected in series with a controllable semiconductor switch (12), parallel to one another, in which in a lower power output range of the DC motor (10) the semiconductor switches (12) are cycled using a pulse control factor which is predefinable as a function of the rpm within the consecutive periods when the individual winding phases (111-114) are energized.

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: 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 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 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 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: 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: The pulse duration of voltage pulses for the control of a motor winding through power transistors is effected by writing data from a microprocessor or CPU to a module having intermediate register into which that data is written, the module then reading the data and effecting the modulation in a pulse by pulse manner.

Abstract: The invention relates to a method for adjusting a real value (actual value) of a physical quantity to a preset value (target value) with the following steps:(a) the difference between the target value and the actual value (referred to below as the control deviation) and its sign (referred to below as the control sign) is determined repeatedly at interval; (b) the control deviation is converted into at least one electrical signal during or after each measurement, and the duration thereof (referred to below as the control deviation duration) is proportional to the absolute value of the control deviation at least in the range of the target value, and the value thereof is a function of the control sign; (c) the charge of an analog electrical memory arrangement is affected by this at least one electrical signal during the control deviation duration; (d) depending on the value of the charge of the memory arrangement, the physical quantity is directly or indirectly affected to keep it in the range of the target valu

Abstract: A PWM DC motor control circuit having improved current sensing. A power switching device controls the DC motor in a common drain connection, whereby armature current sensing is achieved at the negative side of the power switching device. The control for the power switching device and the PWM control circuit are both referenced to the negative rail, and thus do not float or move up and down with the motor modulation. An RC combination is controllably and synchronously switched across the current sense resistor to produce a voltage Ve across the RC combination when the motor power switch is on. This RC combination provides an average voltage of Ve to the PWM control that provides a waveform that replicates very nearly the armature motor current. The DC motor control current has improved immunity to noise generated by the PWM control and other ambient noise.

Abstract: A method of breaking a motor includes the step of applying a pulse width modulated signal to the winding of the motor. A switching voltage is used to intermittently reverse the poles of the motor for selected time periods. The time periods are separated by pauses the duration of which is dependent upon the breaking force needed to stop the motor.

Abstract: A motor control method and apparatus for spindle motor control and for voice coil motor (VCM) control in a direct access storage device (DASD). Characteristics of the pulse width modulation (PWM) waveform are adapted to allow tradeoffs to be made between lower noise emission, greater power efficiency, and current ripple in the motor in order to optimize the driver operation. The transition rate of the PWM waveform is modified by changing the "off-time", which is maintained as a constant in a control register, in response to a change in the condition or mode of operation of the DASD. The "slew rate" of the PWM waveform is also controlled by a changing the value of a constant stored within the control register and can be modified in response to changes in the condition or operational mode of the DASD.

Abstract: An electric motor (12) is supplied with current (i.sub.mot) via a semiconductor switch (14). During operation, the semiconductor switch (14) is driven by a Pulse Width Modulation (PWM) unit 15 using a pulse-formed signal (32). For regulation of the duty ratio of this pulse-formed signal, a first analog signal, which is a function of at least a first motor parameter, is fed to the PWM unit. Further, a second analog signal (STBGR), which is a function of at least a second motor parameter, is fed to the PWM unit for regulation of the duty ratio. As long as the second motor parameter does not exceed a predetermined value, the duty ratio is predominantly controlled by the value of the first analog signal. When the second motor parameter exceeds the predetermined value, the duty ratio is at least predominantly controlled by the value of the second motor parameter, in order to control this second motor parameter through the PWM unit.

Abstract: The method for controlling a motor driving a load holds the speed of the output shaft of the motor substantially constant as the torque imposed upon the shaft by the load varies, then regulates the rate of change of the output torque delivered by the motor's output shaft as the motor's speed decreases.

Abstract: Masking of switching noise is implemented in the driving system of an "H" bridge stage by exploiting the periodic signal generated by a PWM control circuit (normally present in the control system for controlling the "H" bridge in an open-loop mode) for masking the decay time of the disturbances caused by the switching from off-to-on of a first pair of switches of the bridge that drive a current in a certain direction through the load. This is implemented by keeping high for a preset period of time the periodic signal generated by the PWM circuit and varying the duty-cycle of the signal for regulating the mask time in function of the load characteristics.

Abstract: Control circuitry for a multi-speed, rotational, direct current motor can include a means to select one of a plurality of discrete circuits to select a desired speed of the motor, each circuit being activated by a separate analog switch which can complete the circuit to select a potentiometer voltage which then becomes a speed reference voltage output; a motor encoder which generates a pulse train proportional to motor speed and is converted to a proportional voltage by means of a frequency-to-voltage converter; an error amplifier, connected to the outputs of the speed reference voltage and the motor speed voltage such that when the speed reference voltage differs from the motor speed voltage, an error signal is produced; a pulse width modifier circuit which is driven by the error signal and which adjusts motor logic outputs so as to adjust the speed of the motor to produce an essentially zero error; a power supply circuit to feed voltage to the controlling circuitry and motor.

Abstract: A power supply circuit for a control circuit of a motor having an armature, includes a first power supply branch having a series combination of a first resistor, a first diode and a Zener diode connected between a supply of power and a reference potential, with a first junction between the first diode and the Zener diode constituting an output of the first power supply branch which supplies a fixed first current; and a power supply second branch having a series combination of a second resistor, a second diode and a capacitive element connected between the armature of the motor and the reference potential, such that a variable second current in correspondence with current provided by the armature of the motor is provided at a second junction between the second diode and the capacitive circuit, and combined with the first current thereof for supply to the control circuit.

Abstract: A power steering motor control unit for driving a motor in a PWM mode with feedback motor current control reduces fluctuations in the output torque of the motor caused by switching among a plurality of motor driving modes or a change in the duty value of the PWM signal. The control unit as a switching device driving circuit for driving the motor in the PWM mode and a plurality of motor driving modes for the driving control system of a motor, Q/D switching circuitry 14 for switching the motor driving mode, and detected current correcting circuitry 16 for correcting at least one input signal of an input signal comparing circuit provided in a feedback control loop in accordance with the motor driving mode. When the motor driving mode is switched, the correction value given by the detected current correcting circuitry is changed.

Abstract: A motor control circuit comprises a current command circuit generates a current command signal proportional to a selected motor speed. A comparator generates a comparator output signal proportional to the difference between the current command signal and a signal proportional to current flow in the motor. An output terminal of the comparator is operatively connected to a logic circuit which generates a control signal having a duty cycle that varies proportional to the comparator output signal. A drive circuit has an input terminal to which the control signal is applied and an output terminal connected to the motor. The drive circuit generates a motor drive signal proportional to the control signal for driving said motor. A current command control circuit has an input terminal to which the current control signal is applied and an output terminal to which the current command signal is applied.

Abstract: A power steering apparatus for use in association with an electric motor, includes a switch circuit driven by a PWM wave signal which switches between one polarity and the other of the voltage developed across a motor-driving current detecting resistance synchronously with the PWM wave signal so as to detect the magnitude and direction of the motor-driving current, thereby controlling a duty cycle of the PWM wave signal in accordance with the detected motor-driving current. Thus, the motor steering touch and feeling is enhanced.

Abstract: An apparatus and a method for loading a cassette tape in a video equipment, in which driving of a DC motor can be controlled according to an amount of load which is applied to the DC motor when the cassette tape is loaded.

Abstract: A method for regulating a motor current in phase windings of a brushless d.c. motor, wherein current is applied to the phase windings individually via an electronically controllable, d.c.-voltage intermediate-circuit converter with switchable semiconductor valves and respective freewheeling diodes connected in parallel with each thereof in individual bridge arms, and an actual value of the motor current is measured exclusively in the d.c.-voltage intermediate circuit, includes switching off, in a motor mode of operation, only one switchable semiconductor valve of the energized bridge arms for a period of time dependent upon the rotational speed of the motor when a reference value of the motor current is reached.

Abstract: A windshield wiper system (10) which includes an electrical drive motor (12) that makes available a driving moment for at least one windshield wiper (16) performing a back and forth movement on a pane to be cleaned. A signal processing arrangement (20) is provided which, by way of an electrical switching stage (18), controls or regulates the rotation rate of the drive motor (12) to a constant value.

Abstract: A speed control device for a DC motor includes a voltage maintaining circuit connected between the DC motor and a comparator circuit for maintaining the voltage corresponding to an electromotive force when a pulse wave outputted from a pulse-width extension circuit is at a level for off-operation of a switch element. Additionally, an average voltage maintaining circuit is connected between the DC motor and the comparator circuit and maintains in average the voltage corresponding to the back electromotive force produced in the DC motor during the time when the control pulse signal outputted from the control pulse signal output circuit is not at a level for on-operation of the switch element.

Abstract: In order to drive the stepper motor of a floppy disk drive with practically constant current in the face of fluctuations in supply voltage fed from a host system, a power control pulse generator circuit is provided which produces a series of power control pulses having a duty ratio dependent upon fluctuating supply voltage. The power control pulses are used for interrupting the excitation of the stepper motor windings during track seek operation. The power control pulses are generated by first repeatedly counting clock pulses from the host system to a predetermined number to provide periodically varying digital data, then translating the digital data into a triangular wave having an amplitude dependent upon the supply voltage, and then comparing the triangular wave with a reference voltage.

Abstract: A DC power supply for a DC motor is controlled by a drive transistor. An "ON" state of the drive transistor is maintained by a comparator which compares a terminal voltage at a point between the DC motor and the drive transistor with a reference voltage supplied from the power supply. A clock pulse is applied to the drive transistor to make it periodically turn off in order to detect an induced voltage depending upon the rotation rate of the DC motor. The drive transistor returns to turn off upon stopping the rotating DC motor by force.A regulator is provided between the power supply and the reference voltage. A restraint torque and a rotation rate control means are also provided.Alternatively, a pulsating power supply is provided instead of the DC power supply and the clock.

Abstract: A motor control for a multi-phase compressor motor. The control responds to a speed control signal to cause the motor speed to track the speed control signal without changing the motor torque. This is accomplished by pulse width modulating motor speed signals in a sinusoidal manner to maintain the volts/hertz applied to the motor constant regardless of motor speed.

Abstract: A motor control circuit for controlling supply of electric power from a power source to an electric motor, in particular for use in electric power tools, comprising: an output power device for controlling supply of current to the motor according to a duty ratio of a control input signal supplied thereto; current detecting means for detecting an amplitude of an electric current supplied to the electric motor; and feedback means for supplying the control input signal to the output power device, the duty ratio of the input control signal being increased with an increase in the electric current supplied to the electric motor as detected by the current detecting means. Since the torque otuput of the motor is increased when such a need arises, the need for more a complex and expensive continually variable speed control system is eliminated.

Abstract: The invention provides a cushioning control circuit which restricts the initial flow of current to a D.C. permanent magnet motor by providing a neon control lamp in series with a pair of triac control circuits which drops the initial voltage imposed on the motor windings.

Abstract: A control system for controlling a direct current powered motor in which the direct current voltage, which may not be constant, is reversibly commutated across the coil or winding of the motor during the predetermined commutation time intervals and chopped at high frequency during each commutation time interval by a variable duty cycle, pulse width modulated voltage, in which the width of each voltage pulse, determined by a reference voltage, is varied as an inverse function of the magnitude of the direct current voltage which exists during each voltage pulse interval.

Abstract: A method of synthesizing a system which forces finite value of an impedance to zero comprising a positive voltage feedback of a prescribed amount of voltage feed back and a negative voltage feedback to ensure stability of the system, whereby no current through the impedance is sensed and no parameters of the impedance are required to be known implying minimization of measurement noise and adaptive/self-tuning operation, respectively, in applications in which the method is used to synthesize load independent switch mode power converters and electric motor drive systems, incorporating any kind of motor, of infinite disturbance rejection ratio and zero order dynamics.

Abstract: The invention relates to a method and apparatus for making low inertia motors useful under circumstances where the load exerting drag on the motor during start-up acceleration may be different from time to time. A ramped drive current as opposed to a conventional constant current limit signal is applied to the motor. The invention is particularly useful, for example, in magnetic tape drives which must adapt to variations in drag between one tape cassette or cartridge and another.

Abstract: A pulse width modulation control circuit includes a pulse width modulator which supplies a signal to a power switch tying together a d.c. signal generator and a motor and various sensing circuit including a control voltage disabler circuit, a motor voltage and current feedback circuit, and a low control voltage disabler circuit. All of the sensing circuits are appropriately designed to ensure that the various components of the circuit are not damaged under abnormal conditions whether due to motor loads heavier than rated or undesired changes in a.c. current input or control voltages.

Abstract: A pulsating D.C. voltage is developed by a rectifier 86 and is filtered by a capacitor 100 to facilitate application of a relatively smooth, enhanced D.C. voltage to a motor 106.The charged voltage of capacitor 100 is applied across a series circuit which includes a rheostat 118, a resistor 126 and motor 106. When the CEMF of motor 106 drops as a result of a decrease in motor speed, a disc 122 is biased through the voltage appearing across rheostat 118 and resistor 126 to cause an SCR 116 to fire. When SCR 116 fires, the voltage of capacitor 100 supplies a boost of power to motor 106 to overcome the decrease in motor speed.A circuit 212 prevents an overspeed of motor 106 from occurring while braking circuits 264, 266 and 268 provide for a dynamic braking effect when the motor is a universal motor.

Abstract: Drive control for a drilling device including a universal motor is arranged so that the total available mains voltage is applied when a fraction of the motor torque, available for the full work range of the device, is reached. If a higher torque is desired, the motor torque/rotational speed curve follows the natural characteristic line until a load point is reached where current limitation occurs. Accordingly, as the motor speed decreases as the normal work range is exceeded, the operator of the drilling device is signaled concerning the load state due to the noise developed in the drilling device.