Abstract: Method for testing software configured to display a plurality of digital images includes receiving a digital record, the digital record comprising a plurality of digital images having an order, each of the digital images having a visual marker to indicate a respective location within the order; providing instructions to display the digital images, the instructions including an expected sequence; running the software to display the digital images in accordance with the expected sequence; detecting an actual sequence by detecting each visual marker of a respective digital image to identify when each digital image is displayed; and comparing the actual sequence and the expected sequence to quantify the effectiveness of the software at displaying the digital record.

Abstract: The invention provides a marking and/or coding apparatus which allows print resolution to be adjusted by multiplying or dividing encoder inputs generated from a conveyor on which goods to be coded or marked are transported to a marking station.

Abstract: A fan controlling circuit is provided. The fan controlling circuit includes an integral unit, an operational amplifier, a PMOS transistor, and an NMOS transistor. The integral unit transforms pulse width modulation (PWM) signals to voltages, and transmits the voltages to positive and negative input terminals of the operational amplifier. The PMOS transistor is coupled between a first PWM signal and an output terminal, and a gate of the PMOS transistor is coupled to an output of the operational amplifier. The NMOS transistor is coupled between a second PWM signal and the output terminal, and a gate of the NMOS transistor is coupled to the output of the operational amplifier. The fan controlling circuit may be formed by discrete elements and use a same voltage source as fans, so that the design cost and complexity are reduced.

Abstract: A fan controlling circuit is provided. The fan controlling circuit includes an integral unit, an operational amplifier, and an output unit. The integral unit transforms pulse width modulation signals to voltages, and then the output unit outputs one of the pulse width modulation signals having a higher operation frequency according to the comparison result between the voltages. As the fan controlling circuit may be constituted with discrete elements and use a same voltage source as fans, the design cost and complexity are reduced.

Abstract: Apparatus to exercise electrical motor drivers by electrically simulating a geared electric or electrical motor by providing an electronic load for the power signals that are applied to it. Current levels in the load are monitored in real-time using gate array logic and digital signal processing (DSP) algorithms to determine torque, acceleration, velocity and/or position data of the motor and gear train. Motor and gear train positional signals are generated and fed back to the motor driver device to close the servo loop. Control algorithms within the gate array and DSP accurately simulate the motor inertia and act to simulate a physical motor under varying load conditions. A control interface modifies critical motor parameters such as inertia, losses, gear ratio, and loading.

Abstract: An angle computing section determines an angle of a rotor, and an angular velocity computing section determines angular velocity of the rotor. A command current computing section determines, from a steering torque and vehicle velocity, command currents and taken along d-q axes. An open loop control section determines, from command currents and angular velocity, command voltages taken along the d-q axes in accordance with motor circuit equations. A d-q axis/three-phase conversion section converts the command voltages into command voltages of three phases. A ? computing section determines the number of armature winding flux linkages included in a motor circuit equation from a q-axis command voltage, the current value detected by a current sensor, and the angular velocity. Circuit resistance including armature winding resistance R included in the motor circuit equation may also be determined by means of the same configuration.

Abstract: A motor control apparatus provided with an inverter for successively commutating the current to a motor using a PWM signal; a PWM signal generating device for generating the PWM signal using a carrier signal; a rotational state quantity sensor for detecting a rotational state quantity; a phase difference detecting device for detecting the phase difference between the carrier signal and the rotational period based on the rotational state quantity; a frequency setting device for setting a frequency of the carrier signal to a value in accordance with a multiplier for one period in terms of electrical angle of the rotational period of the motor, when the rotational frequency is equal to or greater than a specified frequency and the phase difference is equal to or less than a specified value; and a synchronizing device for synchronizing a control period of the carrier signal to the rotational period.

Abstract: A drive system for an electrical machine is provided. The system includes a control unit and a monitoring unit, which is independent of the control unit. The control unit includes a device that converts one or more incoming operating parameters of the electrical machine to an output value. The monitoring unit includes a device that converts the operating parameters to a comparison value, with the conversion being carried out more quickly in the control unit than in the monitoring unit. A comparator compares the output value or an intermediate value of the output value with the comparison value of the output value or of the intermediate value.

Abstract: A method and circuit enabling off-the-shelf controllers designed for use with a two-level AC drive inverter bridge (1920) to drive inverter bridges with three-or-more levels. Signals from an ordinary induction motor controller or a two-level induction motor controller (2200) are used to drive the twelve-or-more switches of a three-or-more level inverter bridge (1920), as are used in medium-and-high voltage applications. The proper sequence and timing of switching for the three-or-more-level inverter bridge is based in-part upon either the output of the six pulse-width modulators, or the output of the flux and torque control device, or the voltage control device (2210), of the two-level controller (2200).

Abstract: A microcomputer (an electric current command value calculating section) carries out field weakening control in which a d-axis electric current command value Id* is set to a negative value in correspondence with rotation angular velocity ? of a motor. The microcomputer determines whether an anomaly has occurred in an EPS. If it is determined that an anomaly is in a power supply system (step 202: YES), the microcomputer determines whether the anomaly in the power supply system is failure of electric current flow in any phase (step 203). If it is determined that electric current flow has failed in a certain phase, the microcomputer prohibits the field weakening control and outputs a motor control signal instructing to use two other phases free from the failure of electric current flow as electric current flowing phases (two phase drive mode, step 204).

Abstract: A delta type inverter is used in conjunction with a closed-loop motor controller to provide a control device for driving a three phase brushless direct current motor. The delta inverter has one-half of the solid state switching devices and diodes required by conventional bridge type inventers, thereby improved reliability, and enabling the motor control device to have reduced size, cost and weight. The closed-loop motor controller may include a torque loop for reducing torque ripple during operation of the motor.

Abstract: A controller of a brushless DC electric machine having a rotor and at least a stator winding powered by a driving voltage is provided. The controller includes a position sensor, an advance angle control circuit, and a driving circuit. The position sensor is moved along a reverse rotating direction of the rotor by a prepositioned angle for outputting a position signal. The advance angle control circuit receives the position signal and a driving voltage reproduction signal reproduced from the driving voltage and outputs a commutation control signal lagging the position signal by a first delay time. The driving circuit receives the commutation control signal for outputting a driving signal for controlling a commutation of the brushless DC electric machine.

Abstract: A motor control device for controlling rotation of a motor by controlling a driving voltage applied to the motor is provided. The device includes a driving voltage control unit configured to control the driving voltage, and a detecting unit configured to detect rotation of the motor. The motor has operating characteristics indicative of relationship between the driving voltage and a rotation speed of the motor, where the operating characteristics have a specific dead-band range of driving voltages wherein the rotation speed of the motor is zero regardless of changes in the driving voltage. The driving voltage control unit performs a low rotation control operation including at least one alternating repetition of a first control operation and a second control operation.

Abstract: Methods and apparatus to lock a phase lock loop to a spindle motor are disclosed. An example controller comprises a counter to determine a period of an operating signal received from a motor, an oscillator to generate a control signal based on an input signal, and an initializer to generate the input value based on the period, wherein the input value causes the oscillator to generate the control signal having the same phase as the operating signal.

Abstract: A method of interfacing an electromagnetic sensor with a controller in a motor control system, the method including: applying an excitation signal to the electromagnetic sensor; receiving a first electromagnetic sensor output signal based on the excitation signal, the first electromagnetic sensor signal comprising an amplitude modulated signal corresponding to a position of a rotor of the electromagnetic sensor; and receiving a second electromagnetic sensor output signal based on the excitation signal, the second electromagnetic sensor signal comprising another amplitude modulated signal corresponding to the position of the rotor of the electromagnetic sensor.

Abstract: The present invention relates to an actuator current control method. The method of the present invention comprising the steps of measuring a feedback current passing through an actuator, determining PWM duty according to an error component between a target current produced based on an input signal and the feedback current to generate a PWM signal, controlling a current supplied to the actuator based on the PWM signal, and monitoring the feedback current at a time difference of a half period in every period of the PWM signal to estimate an average current and then determining based on the estimated average current whether or not the control of the supplied current has failed. According to the present invention, an algorithm for monitoring a feedback current at a time difference of a half period in every period of the PWM signal to estimate an average current when measuring the average current of the actuator feedback current can be employed.

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 method for controlling driving of a Switched Reluctance Motor (SRM) is capable of operating the SRM normally according to a phase under the normal state in case a noise is inputted to a position sensor in the SRM. In order to achieve the advantage, the method for controlling driving of a three phase SRM using a position sensor having a rate of a rotor and a stator is 6/4 or 12/8 includes the steps of generating a sensor signal according to the position of a rotor in the SRM and operating the SRM by turning on respective phases in the SRM at the point of detecting a rising edge of the sensor signal and turning off the phase at the point of detecting a falling edge of the next sensor signal.

Abstract: Disclosed is a three phase BLDC motor driving circuit which makes a BEMF voltage generated in a motor lower than a voltage source and makes a difference between the BEMF voltage and the voltage source greater than a saturation voltage of a transistor. An emitter is coupled to the voltage source and a collector is coupled to a three phase coil so that the voltage between the emitter and collector of the transistor supplying a current to the three phase coil attenuates to a first level so as not to saturate the transistor.

Abstract: The invention relates to a control system for a commutator motor which is operated by phase-fired control. Allocation of a first and second control device in a single operating state without transition makes it possible to obtain constant jolting rotation of said motor by continuously varied cutting of the half-waves into first and second area sections (8,7) of an alternative current voltage. The inventive type of control system can be used advantageously in electric screwing or drilling tools.

Abstract: A circuit and method for controlling a rotating machine (11) in the constant horsepower range above base speed uses an inverter (15) having SCR's (T1-T6) connected in series with the primary commutation switches (Q1-Q6) to control turn off of the primary commutation switches and to protect the primary commutation switches from faults. The primary commutation switches (Q1-Q6) are controlled by a controller (14), to fire in advance or after a time when the back emf equals the applied voltage, and then to turn off after a precise dwell time, such that suitable power is developed at speeds up to at least six times base speed.

Abstract: A high voltage, single-stage variable speed motor power supply utilizes direct AC-to-AC converters that do not have any intermediate DC link, along with a multi-level, multi-phase, multi-circuit variable speed motor drive and a motor in which a stator is wound with a number of multi-phase circuits. Each multi-phase circuit includes semiconductor switches arranged in drive switch pairs which are operated to produce an effective DC supply with the switches being controlled so that the most positive line-to-line source voltage is utilized for the inversion process.

Abstract: The synchronizing circuit of a digital drive system of an electric motor is configured to function in a closed loop or in an open loop mode by adding a minimum number of elements to the normal scheme of a closed loop synchronizing circuit. In practice, by adding only one programmable register and a pair of two-input de-multiplexers, the system is able to automatically switch from one mode of operation to the other mode. The programmable open loop mode permits compensating for the phase angle between the current flowing through the windings and the drive voltage applied thereto, as in case of a voltage mode driving.

Abstract: The motor speed control device of the present invention is provided with an FG sensor and a waveform shaping circuit for obtaining N pulse signals (N.gtoreq.1 where N is an integer) in one rotation of a motor so as to control the rotation speed of the motor in accordance with period information of the FG pulse signal outputted from the waveform shaping circuit. The motor speed control device is further provided with an FG nonuniformity correcting circuit for correcting, by using respective period information of a rising edge-falling edge period and a falling edge-rising edge period, periodic nonuniformity of each period. The motor speed control device controls the motor in response to an actual speed error signal whose nonuniformity such as a duty error and a phase error has been corrected by the FG nonuniformity correcting circuit.

Abstract: A position control and monitoring circuitry is provided for an electric motor having a plurality of coils and a movable element. A drive circuit generates a square wave drive signal of variable mark/space ratio to drive the coils to position the movable element. A monitoring circuit modulates square wave transitions at a sub-harmnonic of the drive signal frequency and generates a monitoring signal for injection into the coils. A sensor senses the monitoring signal from the coils to determine the position of the movable element. A difference circuit drives the drive circuit with a difference between an input signal and an output signal of the sensor.

Abstract: A speed control system is disclosed wherein a brushless DC motor and a magneto resistive encoder are able to rotate a motor at arbitrarily low speeds. The motor is able to rotate at low speeds by having a filtered signal generated by an encoder applied to its inputs. The encoder is coupled to a series of filters which remove DC level and harmonic distortions from the resulting encoder signal. These filtered signals are then applied to the motor to control motor rotation speed.

Abstract: A rotation position detecting circuit for a sensor-less motor and a motor device include a motor (1) which is rotated and driven by adding a sensor signal having a high frequency to a sine wave drive signal and cosine wave drive signal through adders (5S) and (5C), respectively. Further, a sensor signal is extracted and demodulated from a signal flowing in the motor (1) by a band pass filer (9), and this is defined as a rotation position detection signal. In the sensor signal from the band pass filter (9), its current value is changed corresponding to a change of an impedance resulting from a rotation of a magnet of the motor. As a result, it is possible to detect the rotation position of a rotor magnet by detecting the change of the current value.

Abstract: A PWM controlled multiphase DC motor apparatus has a multiphase DC motor, a current sensor, and a PWM controller. The DC motor has multiple windings which turn on and off during commutation at a commutation frequency. The current sensor is coupled to sense power supply current flowing in all windings of the DC motor. The PWM controller is coupled to control the DC motor using a PWM signal at selected PWM frequency with variable duty cycle. Using the feedback from the current sensor, the PWM controller maintains approximately constant torque in the DC motor by adjusting the duty cycle of the PWM signal. The PWM controller includes a soft switching circuit which manipulates a voltage used to generate the controlling PWM signal in a manner which causes linear stewing of currents in the windings during commutation. The linear current stewing occurs at a slew rate that is slow relative to the PWM frequency to thereby reduce torque ripple during commutation.

Abstract: The invention relates to an X-ray apparatus, comprising a rotary-anode X-ray tube, a device for monitoring the rotational speed of a rotary-anode drive motor of the X-ray tube, a sensor circuit for determining an angle signal which is dependent on the phase angle between a reference voltage and a current associated with the motor, a comparator circuit for detecting the angle signal variation which serves as a criterion for the rotational speed of the motor, and also comprising a frequency changer. Thanks to the fact that there is provided a device for forming a brief keying signal so as to trigger a reduction of the frequency of the rotary-anode drive motor, the device is also suitable for induction motors in which only a small phase angle variation is measured between standstill and the operating rotational speed.

Abstract: An inverter control apparatus and method for a motor driven by an inverter circuit. The primary current of the motor is detected by a detector circuit and is used in combination with a primary current command value to provide pulse-width modulation of the inverter circuit. The inverter is controlled by a switching circuit that can change the PWM frequency based on any one or more factors, including motor speed, motor speed or position control mode, equivalent load factor and detected temperature.

Abstract: An integral information and energy storage system is disclosed comprising a disk drive having a housing, a shaft rotatably mounted therein, and a disk platter coupled to the shaft. A flywheel is also coupled to the shaft and includes, embedded in the flywheel, magnets having magnetic fields emanating therefrom. Electrical coils are positioned in the housing for receiving electrical energy from a power supply line and generating an electromagnetic field effective for selectively repulsing or attracting the magnets to thereby rotate the flywheel and convert electrical energy in the coils into kinetic energy in the flywheel. Alternatively, if power is not available on the power supply line, the coils generate electrical energy as the magnetic field is caused from rotation of the flywheel and the magnet embedded therein to move across the coil, thereby converting kinetic energy in the flywheel back into electrical energy in the coil and to the power supply line.

Abstract: A circuit for controlling a rotating member is provided with an input capture register which reads out the value of a free running counter at a timing of an FG (frequency generated) pulse generated in accordance with a rotation of a rotating member. A central processing unit performs an interrupt operation based on a PG (phase generated) pulse generated in accordance with a rotation of the rotating member and an interrupt operation based on the FG pulse. A pulse width modulation circuit rotates the rotating member by use of a speed error signal and a phase error signal which are obtained by the interrupt operations of the central processing unit. A rotating member driver is also provided. The central processing unit calculates the phase error signal from an output of the input capture register based on an FG pulse generated after the generation of the PG pulse.

Abstract: A drive system for a brushless DC motor uses pulse width modulation, and phase timing advancement to maintain a constant power output during high speed use. The arrangement is well suited for driving a brushless motor in an electric vehicle and the like.

Abstract: A speed control system is disclosed wherein a brushless DC motor and a magneto resistive encoder are able to rotate a motor at arbitrarily low speeds. The motor is able to rotate at low speeds by having a filtered signal generated by an encoder applied to its inputs. The encoder is coupled to a series of filters which remove DC level and harmonic distortions from the resulting encoder signal. These filtered signals are then applied to the motor to control motor rotation speed.

Abstract: A motor speed control device includes a frequency signal generating circuit for generating a frequency signal proportional to a rotation frequency of a motor, a frequency measuring circuit for measuring a frequency of the frequency signal, a speed error signal extracting circuit for extracting a speed error signal by operation comparing the frequency of the frequency signal with a predetermined control target period, a filter circuit for eliminating rotation frequency components of the motor contained in the frequency signal or the speed error signal and harmonic components thereof to output another speed error signal, and a speed error signal feedback circuit for feeding-back negatively the other speed error signal from the filter circuit to the motor, in which owing to the fact that the filter circuit has predetermined transfer functions, it suppresses non-uniform components contained in the speed error signal and the phase error signal due to the frequency signal (DFG signal) proportional to the rotation s

Abstract: An electric motor (10) particularly a low-voltage collectorless dc motor, has a microprocessor (18, 40) with a reset input (24). Further, it has a device (26) which, during the running of the motor, generates signals (R) which depend upon the rotational position of the rotor (14) of the motor (30). These signals are applied to the reset input (24) and have the effect that the microprocessor is reset to predefined starting states or conditions, at times controlled by the turning of the rotor (14).

Abstract: An apparatus for driving an electric motor according to a given control target, including a control circuit which generates a control command signal corresponding to the control target, a chopping signal generator which generates a chopping signal based on the control command signal generated by the control circuit, a full-wave rectifier which rectifies an alternating current supplied from an alternating-current power supply, and supplies a full-wave rectified current to the motor, and a chopper which is connected in series to a series circuit including the motor and the full-wave rectifier and which chops the full-wave rectified current supplied to the motor according to the chopping signal generated by the chopping signal generator.

Abstract: A control system for energizing a direct current (DC) motor with alternating current (AC) power includes a first voltage sensor for a peak voltage of AC power; a second voltage sensor for a counter electromotive force (EMF) of the motor; a current sensor for an armature current of the motor; a digital processor having a first current controller responding to sensed armature current and a current reference, a cooperating second current controller responding to sensed peak voltage, sensed counter EMF and the current reference signal, and a gating circuit responding to the controllers; and a thyristor converter circuit sequentially gating portions of half cycles of AC power to the motor in response to firing signals from the gating circuit. The controllers may control a gate angle of the firing signals, the control system may include a third voltage sensor for a terminal voltage of the motor, and the armature current may have discontinuous and continuous waveforms.

Abstract: A carriage motor control device that uses speed determination means (3) for determining a set speed value (SN12) to be set on the basis of an aimed angle value (SN13A) indicative of an aimed rotation angle, an aimed speed value (SN13B) indicative of an aimed rotation speed and the rotation angle value, speed control means (4) for generating a speed control value (SN7) for making the rotation speed value closer to the set speed value on the basis of a difference between the rotation speed value and the set speed value, angle control means (5) for generating an angle control value (SN8) for making the rotation angle value closer to the aimed angle value on the basis of a difference between the aimed angle value and the rotation angle value, selection means (8) for selecting the speed control value as a motor drive control value when the rotation speed value is larger than a first speed value and selecting the angle control value as the motor drive control value when the rotation speed value is smaller than the

Abstract: An apparatus for stabilizing the speed of a motor has a phase comparator that identifies a phase difference between a reference signal and a speed signal. The apparatus acquires the speed of the motor and generates an output signal proportional to the identified phase difference. A controller receives the output signal. A control circuit for the motor is connected to the controller. The phase comparator comprises a sample-and-hold element, a sampling pulse shaper that is connected thereto and is input with the speed signal, a pulse shaper input with the reference signal, and a signal generator connected to the output of the pulse shaper and to the input of the sample-and-hold element.

Abstract: A torque oscillation compensation system and circuit that uses motor speed to compensate for electrical motor torque pulsations. An input source provides a torque/current command input signal that drives the motor by way of a controller, and a summing device has one input coupled to receive the torque/current command input signal. A controller is coupled to power switching circuitry that is coupled between the power source and the electric motor. A speed sensor is coupled to the motor and is adapted to provide a motor speed output signal. An oscillation compensation circuit is coupled between a speed sensor and the summing device that generates a compensation signal in response to the motor speed output signal that is combined with the torque input signal and compensates for output shaft oscillations.

Abstract: A rotation drive device for driving a rotator is disclosed, comprising an electric motor for driving the rotator, a phase detecting circuit for detecting the phase of rotation of the rotator, a reference signal source for forming a reference signal of a constant period, a phase control circuit for controlling the motor in such a manner that the phase difference between the output of the reference signal source and the output of the phase detecting circuit becomes a constant value, a detecting circuit for detecting a fact that the reading-out of the phase difference is not completed in the time interval between the successive two outputs of the phase detecting circuit, a control circuit for varying the number of cycles of phase difference computing operation of the phase control circuit depending on the time interval between the successive two outputs of the phase detecting circuit, another detecting circuit for detecting a fact that the phase detecting circuit has produced no output in one period of the refer

Abstract: A control device for a moving body such as a focusing lens or the like is arranged to vary time intervals at which a speed control action is performed on a motor according to a driving amount required for moving the moving body to a target position by means of the motor. The arrangement enables the device to prevent an adverse effect of vibrations, etc. and to accurately accomplish position control.

Abstract: A method of controlling the rotational speeds and phases of drum and capstan motors forming part of a servo system in a VCR by detecting signals that correspond to current rotational speeds and phases of the motors, and controlling the rotational speeds and phases of the motors by using the detected signals in rotational speed control and phase control routines. The speed control routine applys the steps of: inputting current rotational speed signals; producing rotational speed control signals corresponding to a rotational speed error signal; applying the produced rotational speed control signals to the drum and capstan motors to control their rotational speeds, performing a compensating operation necessary to the servo system, and then completing the rotational speed control routine.

Abstract: A method and apparatus for accurately controlling a hysteresis synchronous motor velocity eliminate low frequency hunting, which is characteristic of the motor. A nominal input phase current is modified by providing feedback information, thereby enabling a microprocessor control system to modify the phase of quadrature input current signal to the motor and thereby eliminating hunting of the motor. Accordingly, in a high resolution scanning application, speed variations which could cause disturbing artifacts to appear in an output image are eliminated.

Abstract: A motor speed controller implements a speed control to phase control switch over. When the switch over occurs on initial offset between the reference speed signal phase and the current motor position phase is determined. The reference speed signal is then offset by this phase difference thereby achieving a quicker servo lock.

Abstract: A capstan servo device comprising a frequency generator for detecting the rotation rate of a capstan motor and generating two-phase FG signals mutually having a 90.degree. phase difference; a selector for selecting one of input four-phase signals produced from the two-phase FG signals and mutually having a 90.degree. phase difference; and a sync signal generator including an N-bit counter (where N.gtoreq.2) to receive a reference frequency signal inputted thereto and generating a sync signal by phase-comparing the two high-order bits of the frequency-divided output of the counter with the two-phase FG signals. In this device, the rotation speed of the capstan motor is controlled in accordance with an error voltage signal selected by the selector in response to the sync signal.

Abstract: It is foreseen to measure the rotational speed (V) of a motor (4) by measuring the electromotive force (e.m.f.) This e.m.f. is calculated as the difference between the terminal voltage (Va) and the voltage drop at a reference resistor (S), through which the armature current flows, then this value is used as a velocity feedback signal for motor regulation. Particularly, the terminal voltage (Va) is cyclically measured at two successive close instants (t1, t2), during which the armature resistance (Ri) and the motor e.m.f. can be considered constant; these terminal voltage values (V.sub.at1, V.sub.at2) are stored, then elaborated to perform the actual armature resistance (Ri) during that interval (t1-t2), then this value is multiplied for the instant current (I). The result is then substracted from the terminal voltage (Va) and only at that time the resulting e.m.f. is used as a velocity feedback signal for the velocity feedback circuit. The apparatus for carrying out this process is also disclosed.

Abstract: An output circuit having a fail-safe function with: a control signal generating circuit which generates a control signal to control the current of a load and includes an operational amplifier which amplifies a difference between a control value and a feedback value to produce the control signal; a drive circuit which drives a load according to the control signal from the operational amplifier; an output current detecting circuit for detecting a current in a load solenoid and adding an offset current to the detected current, with the output of the output current detecting circuit being fed back to the control voltage generating circuit as the feedback value.

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.