Abstract: A DC motor controller for use with a battery powered DC motor operatively positioned in a vehicle is disclosed. A power source-watch dog circuit 2 monitors a micro computer 8 and decreases the battery supplied voltage to below a predetermined voltage. A key switch input circuit 3 receives a switch-on signal generated by a key switch and outputs a signal to the power source-watch dog circuit 2 to initiate electrical power output from the battery 1 to the micro computer 8. A pedal input circuit 4, which includes a pedal for varying electrical resistance, converts the varied resistance into an analog signal and outputs the analog signal to the micro computer 8. The micro computer converts the analog signal to a digital signal and outputs the digital signal. A D/A converter converts the digital signal outputted by the micro computer into an analog signal and outputs the analog signal. A pulsewidth modulator 10 modulates the analog signal and outputs the modulated signal.

Abstract: A solid state DC power control circuit to efficiently use DC battery power without the normally associated energy waste which includes an input control signal, amplifying and conditioning circuit (133), a triangular waveform generator circuit (131), a comparator circuit (135), an inverting MOSFET (metal oxide semiconductor field effect transistor) circuit (137), and a plurality of power MOSFET devices (42), which together combine to translate a typical variable resistance control input into a voltage level and condition it suitably to be compared with a known triangular waveform thereby creating a pulse width modulated signal whose pulse widths correspond in duration to the relative percent "on" or "off" of the control input signal and which regulates a plurality of parallel MOSFET devices (42) which together share the load of an external DC power drain circuit (143).

Abstract: A control system controls a motor so that a controlled speed is maintained at an object value supplied from an external unit. The control system includes: an operation block for obtaining a difference between the object value and the controlled speed; an integrating block for integrating the difference obtained by the operation block and for outputting an integrated value; a limiting block for outputting a limited value when the integrated value obtained by the integrating block is equal to or greater than the limited value and for outputting the integrated value from the integrating block as it is when the integrated value is less than the limited value; and a control block for maintaining the controlled speed of the motor at the object value based on the integrated value or the limited value output from the limiting unit.

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: There are provided a position and velocity control system for producing a velocity command signal in response to a position command signal and a signal representing a current position and velocity of a servo motor, a current control system for supplying a drive current to the servo motor in response to the velocity command signal, and a communication system for transmitting data between the two systems by means of a bilateral communication line. A servo control system is thereby separated between the current control system and the position and velocity control system and connected to each other through the communication system.

Abstract: In an inverter control apparatus including a pulse width modulation inverter supplied with power from a d.c. power source to generate an a.c. output, a frequency control unit controlling the output frequency of the inverter, and a voltage control unit controlling the output voltage of the inverter, a frequency adjusting unit is provided to adjust the operating frequency of the inverter so that the product of voltage and time in each positive half cycle of the output voltage of the inverter becomes equal to that in the next adjacent negative half cycle of the output voltage of the inverter.

Abstract: A motor speed controller, for example for accurate linear control of DC motors, includes an error amplifier, such as an integrating error amplifier, for providing a variable controlled voltage to a motor in response to an input to the amplifier, the input comprising a combination of a demand signal representative of a desired speed of the motor and a feedback signal representative of an actual speed of the motor. An electronic switch, such as a transconductance amplifier, has a first input responsive to an electrical signal representative of the actual speed of the motor and a second input responsive to the polarity of the output of the amplifier so as to provide the feedback signal, the value of the feedback signal being dependent on the value of the signal representative of the actual speed of the motor and the polarity of the signal being dependent on the polarity of the output of the amplifier.

Abstract: An x-ray tube (10) of a CT scanner has a rotating anode and rotor combination which is propelled by AC currents applied to run and phase windings (42, 46) by a starter (22). A monitor (24) includes Hall effect current detectors (40, 44) which detect the actual current flowing through the run and phase windings. The detected analog current values, voltage values, and the like are multiplexed (132) and digitized in a preselected order by an analog to digital converter (60) and stored in that order in a FIFO memory (62). A microprocessor (64) performs a Fourier transform (94, 96) to convert the digital run and phase signals into frequency spectra. The run and phase frequency spectra are compared (100, 102, 104, 106) with frequency spectra indicative of rotor speed, bearing wear, anode vibration, failure of the anode to rotate, and other conditions, analyzed for symmetry or other characteristics, or the like (FIG. 5 ) to generate digital run and phase reference signals.

Abstract: A system and method of controlling an electronically commutated motor (ECM) driving a blower to maintain the mass flow rate of the blower at a desired value. A microprocessor-based controller unit derives a motor control signal from just two inputs, namely the desired mass flow rate and a speed feedback signal representing the actual shaft speed of the ECM.

Abstract: A pulse width modulation (PWM) control system for rotating a spindle motor and a rotatable recording medium at a constant speed.

Abstract: A solid state DC power control circuit to efficiently use DC battery power without the normally associated energy waste which includes an input control signal filtering, amplifying, and conditioning circuit (133), a triangular waveform generator circuit (131), a comparator circuit (135), an inverting MOSFET (metal oxide semiconductor field effect transistor) circuit (137), and a plurality of power MOSFET devices (42), which together combine to translate a typical variable resistance control input into a voltage level and condition it suitably to be compared with a known triangular waveform thereby creating a pulse width modulated signal whose pulse widths correspond in duration to the relative percent "on" or "off" of the control input signal and which regulates a plurality of parallel MOSFET devices (42) which together share the load of an external DC power drain circuit (143).

Abstract: A method and apparatus for controlling single or polyphase a.c. power controllers when controlling a.c. power controllers by means of phase angle control of semiconductor switches, the firing signals on the one hand must be long enough to guarantee a reliable firing and, on the other hand, be short enough to prevent an overloading of ignition amplifiers. According to the invention, therefore the use of firing signals with variable temporal lengths is provided, which end at least approximately at the reestablishment of the current flowing in the phase that has been fired. Moreover, devices for implementing the method are specified.

Abstract: A method of operating a brushless motor having a stationary assembly with at least two different energizable windings for producing spaced apart magnetic fields in time sequence, and a rotor adapted to rotate in response to the magnetic fields. The method includes the steps of simulating rotor position in accordance with the back emf condition of at least one winding, energizing a selected one of the windings in accordance with the simulated rotor position, sensing an underspeed condition when the motor speed is less than a minimum value for a length of time, and preventing energization of any of the windings when the motor speed is less than the minimum value for the length of time. An electrically commutated motor controller apparatus controls the speed of a variable speed motor compressor driven by an electrically commutated motor. A controller circuit includes a circuit for producing feedback signals representative of a back emf of the motor.

Abstract: A compressor drive system that includes a thermostat producing a signal indicating the measured air temperature, a modulation control circuit connected to the thermostat to produce a motor drive signal from the temperature signal and which is output to a motor drive switching bridge circuit. The motor drive switching bridge circuit is connected to a rectifier that converts single phase alternating current to direct current. The switching bridge uses the motor drive signal from the modulation control circuit and the rectifier output to produce multiphase power including a speed control signal imposed on the power for regulating speed. A motor connected to drive a compressor is included. The motor is powered by the motor drive switching bridge circuit multiphase power output. The speed of the motor is controlled as a function of the temperature signal.

Abstract: A motor control system is disclosed which includes an encoder for generating pulses in proportion to the rotational amount of the motor. A speed instructing unit provides a speed instruction for the desired rotational speed of the motor. A speed control unit calculates (1) the actual rotational speed of the motor based on the pulse signal from the encoder and (2) a voltage to be applied to the motor and outputs a PWM signal which represents the actual motor speed. The PWM signal is identical with the voltage to be applied to the motor. This arrangement ensures that the motor speed will follow the speed instruction. A driver unit supplies electric power to the motor by amplifying the PWM signal.

Abstract: A motor speed control device for use in an image forming apparatus with a differential phase detection circuit for outputting differential phase data between the clock pulse and a frequency proportional signal representative of the motor speed and a differential speed detecting circuit for outputting differential speed data between the length of the clock signal and the length of the speed signal. A pulse width modulated signal obtained from the two signals controls the speed of the motor.

Abstract: A control circuit for alternating current motors comprises a bidrectional controlled diode (TRIAC) connected in series to the motor and with its own control terminal connected to a fixed-phase actuating network in order to supply partial power to the motor. The control terminal is also connected to a switching device, piloted by a control signal to supply it, when closed, with a bias current which causes the continuous operation of the TRIAC, so as to supply full power to the motor. The control circuit can be used in conjunction with circuits which measure the current absorbed by the motor and give said control signal to make it switch from the full power condition to the partial power condition and vice versa whenever said current reaches pre-established thresholds. One of these circuits supplies partial power to the motor whenever the current it absorbs is too high, which indicates a mechanical overload.

Abstract: A pulse-width modulated (PWM) circuit applies a voltage across a load in accordance with a PWM command signal. The command signal is converted into first and second trains of pulses, by electronically comparing the command signal with a triangular dither signal and also with the dither signal whcih has been shifted by half its period. These two pulse trains, and two more pulse trains obtained by taking the complements of the original pulse trains, are applied to a pair of bridge circuits. The load is connected to both bridge circuits. Both bridge circuits include electronic switching devices actuated by the pulses. The bridge circuits are configured such that when a pulse is present, from either the first or the second pulse train, no net voltage appears across the load. At all other times, substantially the entire power supply voltage is applied across the load. In another embodiment, one or more additional pairs of bridge circuits are connected across the load.

Abstract: A motor stop control device for stopping a motor rapidly. The motor control includes a pulse generator for generating a pulse signal having a pulse width which is in relation to the speed of the motor, a CPU, and a drive for driving the motor. When a motor stop command signal is produced when the motor being rotated forward, CPU operates the drive to produce a counter drive torque, and, at the same time, CPU starts to compare the pulse width of the present pulse signal with that of the previous pulse signal, and produces a signal when the pulse width of the present pulse signal becomes shorter than that of the previous cycle. When the signal is produced, the drive stops to produces the counter drive torque.

Abstract: A pulse-width modulated circuit applies a voltage across a load in accordance with a command signal. The command signal is converted into first and second trains of pulses, by electronically comparing the command signal, and its inverse, with a triangular dither signal. These two pulse trains, and two pulse trains obtained by taking the complements of the original pulse trains, are applied to a pair of bridge circuits. The load is connected to both bridge circuits. Both bridge circuits include electronic switching devices actuated by the pulses. The bridge circuits are configured such that when a pulse is present, from either the first or the second pulse train, no net voltage appears across the load. At all other times, substantially the entire power supply voltage is applied across the load.

Abstract: A pulse-width modulation-type inverter operable at a variable frequency and amplitude and having the ability to modify carrier frequency on the basis of changes in temperature, output current and output frequency levels. The inverter operates in a high carrier frequency range which reduces the audio noise.

Abstract: A motor rotation speed control circuit fabricated in an LSI, a first counter which, after being reset by each rotation of the motor, begins counting clock pulses. Bit-outputs of the first counter are led out of the LSI package of the LSI, and are selectively connected to external input lead terminals of a plurality of gate circuits, each of which detects when the first counter has counted a number determined by sum of the input bit-outputs. One gate circuit detects a first reference count-number N.sub.a, which is smaller than a probable least count-number corresponding to, for example, a lower limit of tolerance of the motor speed, considering future possible changes of the motor speed. After being reset by a reset signal corresponding to the first refernece number N.sub.a input thereto, a second counter, preset with a second reference count-number N.sub.b, starts to count the clock pulses. The second reference count-number N.sub.b is chosen so that N.sub.a +N.sub.b =N.sub.0, N.sub.

Abstract: An error signal detection circuit in a servo control device comprises a reference signal generation circuit for selectively generating reference signals of different periods, each having a slope which changes from a reference value at a substantially constant gradient, an error detection timing generation circuit for generating timing of detection of an error signal of an object of control, an error signal detection circuit for generating an error signal by detecting the value of a reference signal generated by the reference signal generation circuit at a timing provided by the error detection timing generation circuit, and a slope varying circuit for varying the slope of the reference signal in accordance with the period of the reference signal.

Abstract: A circuit for generating a pulse-like timing signal driving a stepping motor which is used to drive for example a magnetic tape to run in an audio tape or video tape recording and reproducing apparatus. A rewritable memory stores output pattern data and time information for generating the timing signal. This timing signal generating circuit comprises a rewrite control circuit responsive to an operation mode instructing signal, for performing a predetermined operational processing on basic pattern data and basic time information and storing the resulting output pattern data and uniquely related time information in the rewritable memory.

Abstract: In a power supply apparatus for driving a DC motor of a car cassette player, there is provided a switching regulator circuit for regulating a DC (direct current) input voltage to produce a desired DC output voltage; a motor driving circuit for driving a motor by receiving the DC output voltage of the switching regulator circuit; a sensor element for sensing a speed of the motor to output a sensor signal; a motor speed judging circuit for comprising a sensor signal from the sensor element with a reference signal to produce a judgement signal; and, a control voltage generating circuit for producing a control voltage based upon the judgement signal of the motor speed judgement circuit, whereby the DC output voltage of the switching regulator circuit is controlled in response to the control voltage.

Abstract: A drill motor control for periodically varying the rotational speed of a drill to increase the cutting efficiency of the drill bit is disclosed. The speed of the drill is made to vary according to a predetermined cycle such that the drill bit is permitted to bite into the material being drilled at lower speeds, and then the speed is increased to a point where maximum cutting efficiency is achieved. The drill motor control may either be a stand alone apparatus into which a conventional drill is plugged or alternatively may be incorporated into the drill itself. A closed loop control system which senses drill motor current may be utilized to cause the drill motor to slow down as current to the motor decreases when the drill bit ceases its cutting action such as when glazing occurs or when the drill bit has cut completely through the material being drilled. The drill motor control is also useful when the drill is being used as an electric screwdriver.

Abstract: A method of synchesizing a system which effectively forces finite value of an impedance to zero comprising a most inner positive voltage feedback loop and an inner negative voltage feedback loop and an outer negative voltage feedback loop, whereby a voltage difference between the most inner positive feedback loop and the inner negative feedback loop is fed back to compensate for the voltage drop across the impedance of interest in both steady state and transient and whereby no current through the impedance is sensed and no parameters of the impedance including parameters of the plant under the control 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: A solid state DC power control circuit to efficiently use DC battery power without the normally associated energy waste which includes an input control signal filtering, amplifying, and conditioning circuit, a triangular waveform generator circuit, a comparator circuit, an inverting MOSFET (metal oxide semiconductor field effect transistor) circuit, and a plurality of power MOSFET devices, which together combine to translate a typical variable resistance control input into a voltage level and condition it suitably to be compared with a known triangular waveform thereby creating a pulse width modulated signal whose pulse widths correspond in duration to the relative percent "on" or "off" of the control input signal and which regulates a plurality of parallel MdOSFET device which together share the load of an external DC motor circuit.

Abstract: In order to provide a speed control apparatus for a movable equipment having small torque ripples and speed variation, the present invention has a speed control means which comprises a driver for providing a current or a voltage having a magnitude corresponding to the instructed speed, a speed detection circuit for detecting a speed on the basis of a signal from the speed detector and a microcomputer for driving the driver by comparing the speed instruction signal with a speed signal obtained from the speed detection circuit. The microcomputer includes a harmonic wave component detecting means for detecting a harmonic wave component contained in a speed variation mode which is obtained from the speed detection circuit and has a function of making the gain of a speed control system variable by the harmonic wave component detected by the harmonic wave component detecting means.

Abstract: A method of synthesizing load invariant dc drive system comprising positive armature current feedback of exactly specified nature and value of its transfer function. The system transfer function independent of load is realized while stability and dynamics of the system are controlled by additional voltage loop.

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: The problem of reducing harmonic content of AC bus voltage in a power system (10) is minimized using a controller (30) for a PWM inverter (38). The controller (30) develops a duty cycle command on a line (40) for controlling operation of the PWM inverter (38). The controller (30) develops the duty cycle command to maintain the PWM inverter output voltage at a desired level. This duty cycle command is modulated in accordance with the harmonic content evident on a DC bus (34) which supplies power to the PWM inverter (38).

Abstract: A method of synthesizing a system which forces finite value of an impedance to zero comprising positive current feedback of exactly specified nature and value of its transfer function. The stability and dynamics of the system are controlled by additional voltage loop. The zero-impedance converter is used to synthesize load-independent systems including switch-mode power converters and pulse width modulated electric motor drive systems incorporating any kind of motor.

Abstract: A method of synthesizing a system which forces a finite value of an impedance to zero comprising positive current feedback of exactly specified nature and value of its transfer function and an internal negative voltage feedback ensuring inherent stability of the system. The converter is used to synthesize electric motor drive systems, incorporating any kind of motor, of infinite disturbance rejection ratio and zero-order dynamics and without position and velocity feedback.

Abstract: The inverter includes a low voltage microcontroller referenced to ground potential and a waveform generator coupled to the microcontroller through a serial data link including optical isolation devices. The waveform generator floats at the negative bus potential of the DC source for the inverter. The waveform generator produces switching signals for the inverter under control of the microcomputer. The waveform generator, serial communications circuitry and other support circuits are all part of a single application specific integrated circuit. Registers store control parameters from the microcontroller, and counters, a look up table and a state machine derive pulse width modulated switching commands to achieve motor control for a 60.degree. sector of motor field rotation and repeat the derivation of similar switching commands for each subsequent sector. A pulse director applies the pulses to the correct motor phases for a given sector.

Abstract: A method of synthesizing drive systems, including dc, synchronous and asynchronous ac, and step motor drive systems, of instantaneous response and zero error in both transient and steady state with respect to an input command and of infinite disturbance rejection ratio with respect to a load torque changes, comprising an inner positive current feedback of exactly specified nature and value of its transfer function forcing the motor impedance to zero for load independence, and further comprising control functions in a direct path with respect to both position and velocity feedback loop and in a feedforward path of exactly specified values which, together with the inner positive current feedback loop, provide for the zero-dynamics system transfer function with respect to the command with an associated instantaneous response.

Abstract: An AC motor control based on an iterative computation of the motor load and method of accurately determining motor load. At the initiation of motor operation, the load term (%LOAD) is initialized to zero, and the motor is energized in accordance with a predetermined voltage and frequency schedule for producing motor rotation. During the starting interval the power loss term LOSSES and the load term (%LOAD) are iteratively computed as a function of the input voltage and current (V.sub.bus, I.sub.bus) and the motor inverter frequency (IF). When a predetermined motor speed has been achieved, the run mode is initiated. At this point, the load is known based on the iterative load calculations performed during starting, and the motor voltage and inverter frequency are scheduled as a function of motor speed and load. The iterative computation of losses and load continue during the run mode so that changes in the motor load are taken into account.

Abstract: A circuit for controlling the speed of a magnetic tape reel motor of an audio signal recording/playing mechanism. The circuit is based on the fact that the reel revolution period varies at a constant rate per revolution. The circuit measures the frequency generating value of the tape reel motor running at the normal speed to generate the ideal pulse value of the normally running motor as the initial reference value. Then the tape reel motor is run at the speed of N times the normal speed. The output of constant value means is added to the initial reference value to obtain the ideal pulse value. The present frequency generating value measured is compared with the ideal pulse value, which result is used to increase or decrease the applied voltage of the tape reel motor.

Abstract: A sewing machine having a wireless controller is disclosed, wherein the sewing machine substantially comprising a drive motor for driving the sewing machine, a separate controller adjustably operated to produce a variable set voltage for controlling the rotation speed of the drive motor, a converter for converting the set voltage to a corresponding digital value and producing a series of data on the basis of the digital value, a device for producing carrier waves, modulator for modulating the series of data by way of the carrier waves and producing modulated waves, transmitter means responsive to the modulated waves to produce a corresponding light signal, means for receiving the light signal, demodulator for demodulating the received light signal, and a device responsive to the demodulated light to control the rotation speed of said drive motor.

Abstract: A method of synthesizing a system which forces finite value of an impedance to zero comprising a positive current feedback of a prescribed functionalism and a negative voltage feedback to ensure stability of the system. The prescribed functionalism of the current loop uses arithmetic elements as well as voltage and current measurements to provide for a parameter-free synthesis of the converter whereby the converter operates in the measurement-based mode, the measured variables being the voltage and the current associated with the impedance of interest, without a need to supply values of both resistive and reactive components of the impedance of interest. The converter is used in synthesizing electric motor drive systems, incorporating any kind of motor, of infinite disturbance rejection ratio and zero-order dynamics and without specifying the resistive and the inductive values of the motor impedance.

Abstract: A method of synthesizing load invariant ac synchronous and asynchronous motor drive systems comprising positive stator current feedback of exactly specified nature and value of its transfer functions. The system transfer function independent of load is realized while stability and dynamics of the system are controlled by additional voltage loop.

Abstract: The inventive system for controlling a working shaft includes a layout for the time to number conversion, wherein a divider is provided to divide with use of a pulse rate outputted from the memory storage, and the shaft driver is operated by output from such a divider and is thereby controlled with use of the data stored in the memory storage. Concurrently, by introducing the counter outputs indicating the time scaling into the addresses of a memory sector, the memory sector is arranged to output varying speed data corespondent to the time scaling data. Thereby trailing actions of the working shaft to trace a given locus are determined by data stored in the memory storage, which enables a complex real time control to be feasible by the inventive simple control system, wherein, as required, a change in the control specification is simply made by a change of data in the memory storage.

Abstract: An A.C. solid state power controller for controlling the current through a load from an alternating current source, including a diode bridge rectifier with its direct current output connected to a solid state switch, such as a MOSFET or a bipolar transistor, that is gate controlled by gate signals synchronized to the A.C. source. The gate signals are provided from an optocoupler to control the solid state switch and the load current. Overload, short circuit, and low A.C. line voltage conditions are sensed by protection circuits which signal the optocoupler to turn off the solid state switch and, thus, the load current. A fast turn off time, in the range of a few microseconds, is achieved which, together with the rectifier and solid state switch configuration, provides a power controller which is resistant to short circuit and overload destruction present in conventional A.C. solid state circuit breakers and power control devices.

Abstract: A manual power assist control employs a magnetic encoder which is mounted to a shaft of the door operator. The encoder generates pulse trains which are indicative of an attempt to open the door in a given direction. The pulses are processed to generate a signal for opening the doors in the event a manual attempt to open the doors is detected.

Abstract: A constant speed driving apparatus comprises a starting means for starting a control unit, the first pulse-generating means for generating the first pulse signal with a predetermined frequency, a driving mechanism for driving a load, the second pulse-generating means for generating the second pulse signal corresponding to driving speed of the driving mechanism, and the control unit for controlling the driving mechanism on the basis of the first and second pulse signals.

Abstract: A PWM circuit for generating a PWM wave which is pulse-width modulated in response to binary information and is used for a signal such as a motor driving signal in an R-DAT (rotary head type digital audio tape recorder) comprises a circuit for dividing binary information such as a motor speed error signal provided for generating a PWM wave into plural bit groups and generates PWM waves corresponding to numerical values of these plural bit groups, and a circuit for weighting the generated PWM waves in an analog manner at a ratio corresponding to orders of the respective bit groups and adding the weighted PWM waves. Since binary information is divided into plural bit groups, the bit number of each bit group is small so that the period of PWM wave can be shortened without reducing the quantization bit number of the binary information or shortening reference clock period whereby accuracy of an error signal can be improved when the invention is applied to, e.g., a motor drive device.

Abstract: In a circuit arrangement for the timed control of semiconductor switches (1-4) to each of which a freerunning diode (D1-D4) is connected in parallel and which are arranged in branches of a bridge, an ohmic-inductive load (5) of low loss power which lies in the diagonals of the bridge is to be acted on by a controlled average current value. For this purpose two semiconductor switches (for instance 1, 4) lying diagonally opposite each other in the bridge are closed in a current-application phase while in the following freerunning phase a freerunning current flows through the load. For the reduction of the loss power, at the start of the freerunning phase only one (1) of the two diagonally opposite semiconductors (1,4) is opened and a semiconductor switch (3) which lies in the bridge alongside the conductive semiconductor switch (4) is then closed.

Abstract: There is provided a motor control device comprising a motor; an apparatus for entering the number of revolutions of the motor; a detector that detects the number of revolutions of the motor; and a microcomputer for entering the output from the detector and a controlling the motor according to predetermined programs, wherein the microcomputer comprises a counter to which a count value is set according to a circuit from the input to form a reference frequency signal and a circuit for forming a phase error signal according to the reference frequency signal and the output of the detector and outputs a signal for driving the motor based on the phase error signal.

Abstract: A method and apparatus prevents the overheating of a line feed motor used in a printer. First and second timers are respectively provided to measure first and second time intervals. The second time interval includes a cessation period in which the line feed motor is not driven to allow for heat dissipation of the line feed motor. At the end of the first time interval, a determination is made as to whether the number of line feed pulses during the first time interval exceeds a predetermined limit. If the number of line feed pulses does not exceed the predetermined limit, the first time is reactivated. If the number of line feed pulses does exceed the predetermined limit, then the second timer is activated to allow for heat dissipation of the line feed motor.

Abstract: A circuit for controlling the speed of a subfractional horsepower DC motor has a driver stage with a switch that interrupts the motor current in repeated succession so that a pulse-like current is provided, and the motor EMF is sampled synchronously with the motor current interruption, with the sampled value being supplied to a comparator wherein it is compared to a rated value. The output of the comparator is used to control the driver stage which includes the switch. Two pulse duration modulators are provided which respectively independently control the motor current and voltage. The pulse duration modulator which controls the current generates pulse pauses which are always sufficiently long to permit the EMF measurement to be completed. The pulse duration modulator operates at a frequency above the audible frequency range so that its pulse pauses are short enough to prevent the motor current from noticeably failing or being completely interrupted.