Abstract: A motor control chip (62) for asserting the control signals used to regulate the energization of the windings of a DC motor. The motor control chip includes a tachometer (94) that receives pulsed signals that vary with the rotation of the motor rotor and that produces a pulse width modulated tachometer signal as a function of the motor speed. A pulse width modulator (90) receives the tachometer signal and an analog signal representative of the user-selected motor speed. Based on the received input signals, the pulse width modulator produces a variable speed control signal. A forward/reverse oscillator (92) receives user-set signals indicating if the motor should be run in the forward or reverse directions or in an oscillatory pattern. Based on the received signals, the forward/reverse oscillator asserts a forward/reverse signal having an appropriate signal state or cycle. A motor decoder (98) receives the signals produced by the pulse width oscillator and the forward/reverse oscillator.

Abstract: To improve the detection reliability in the detection of sticking of a foreign matter and minimize a sticking load, a power window is provided with a window frame sensor disposed along the inner peripheral edge of a window frame and a drive motor for advancing and retreating a window glass in accordance with an external signal. A control circuit makes a duty control for a transistor to decrease the operating speed of the window glass when the pressure detected by the window frame sensor becomes larger than a predetermined value during a closing operation of the window glass. Thereafter, when the drive load of the drive motor exceeds a predetermined value, a relay is switched over to operate the window glass reverse in the opening direction.

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: A speed regulating circuit for a motor of a power coping saw includes a DC voltage circuit, a manual speed regulating circuit, a feedback controlling circuit and a motor driving circuit. The DC voltage circuit includes a diode, a resistor, a capacitor, and a Zener diode. The manual controlling circuit includes a Zener diode and a resistance. The feedback controlling circuit includes an amplifier, a transistor, a pulse transformer. The motor driving circuit includes an SCR and a diode. The manual controlling circuit may first be set with a reference voltage signal corresponding to the intended rotational speed of the motor. The reference voltage signal is sent to the feedback controlling circuit to get a rotational speed controlling signal of a motor with respect to the variation of loads. A DC current is then supplied to the motor driving circuit for constantly rotating the DC motor despite the variation of the load.

Abstract: An electric power generating installation has a plurality of generator/motor units, each of which has a motor for converting kinetic energy into turning torque, a generator connected mechanically to the motor and connected electrically to an electric power system for converting turning torque into electric energy. A control system is provided for controlling the motor and the generator in such a way that they can be operated stably and continuously. The control system controls the different generator/motor units in different control modes so as to minimize cross current and resonance or beat phenomena.

Abstract: In a power window apparatus, an external force which develops at the time of catching foreign objects in a window is detected directly by a window frame sensor and indirectly by a motor load detection circuit. Automatic window closing operation is disabled when the external force exceeds a first and a second predetermined levels of the window frame sensor and the motor load detection circuit, respectively. When the window frame sensor fails, the window closing operation is disabled and a warning is provided at the time the external force detected by the load detection circuit reaches a third predetermined level. Alternatively, the automatic window closing operation is disabled when the external force exceeds the first or the second predetermined levels of the window frame sensor or the motor load detection circuit, respectively. When the window frame sensor fails, the window closing operation is disabled and the warning is provided at the time the external force reaches the second predetermined level.

Abstract: To improve the detection reliability in the detection of sticking of a foreign matter and minimize a sticking load, a power window is provided with a window frame sensor disposed along the inner peripheral edge of a window frame and a drive motor for advancing and retreating a window glass in accordance with an external signal. A control circuit makes a duty control for a transistor to decrease the operating speed of the window glass when the pressure detected by the window frame sensor becomes larger than a predetermined value during a closing operation of the window glass. Thereafter, when the drive load of the drive motor exceeds a predetermined value, a relay is switched over to operate the window glass reverse in the opening direction.

Abstract: An arrangement for driving a power control element of a drive unit of a motor vehicle is proposed and the arrangement has a full-bridge output stage. A direct-current motor is arranged in the bridge diagonal and the current through the direct-current motor is limited to at least one preadjusted value in that the clocked drive signals are interrupted when the preadjusted value is exceeded.

Abstract: A novel motor belt drive mechanism which rotates a mouse or other toys to amuse, occupy, and entertain pets. The device is battery powered with a switch which can be turned on and off to attract a cat or other pet. The device has a low profile, thereby making it difficult to tip over. The device is battery operated and has no exposed dangerous voltage wires for pets to chew on. The device may be mounted in virtually any plane and in rotation may be allowed to animate other suspended devices for further variation. The rotating toy device may be locally or remotely manually oscillated to cause an erratic changing field of direction and at the same time allowing direct inter-action pet entertainment for elderly, disabled and persons with impaired senses.

Abstract: An electronic control system and apparatus is provided for controlling the operation of an industrial machine, such as a sewing machine. A body actuated apparatus is mounted in a spaced apart relationship from ground level and in approximate adjacency to the sewing machine. The body actuated apparatus has an elongated control bar pivotally mounted to the body actuated apparatus along a longitudinal axis of the elongated control bar for actuation of a force sensor when a body of an operator pressingly engages the elongated control bar in a direction towards the sewing machine. Electronic means for controlling the speed of a motor of the sewing machine is provided which includes monitoring means for monitoring sensor input produced by the force sensor, and controlling means responsive to the monitoring means for varying the speed of the motor of the industrial machine by outputting control signals to the motor.

Abstract: A semiconductive power unit for controlling drive motor speed by controlling the power applied to the motor through a variable or switchable semiconductive control element, such as a Darlington transistor. Electrical power is supplied from a power supply to the variable speed drive motor via the controllable semiconductive device connected to provide a variable impedance branch path between the power supply and the variable speed drive motor. A power dissipation characteristic for the variable impedance branch path is established, wherein current flow therethrough decreases monotonically with increasing voltage across the variable impedance branch path. The circuit establishing the characteristic also provides a feedback signal to the controllable semiconductive device to maintain its operation at the established power dissipation characteristic.

Abstract: An impact wrench having a speed limiting control circuit to allow an operator of the wrench to controllably limit the maximum speed of the wrench to a predetermined value when a trigger thereof is fully engaged. The impact wrench includes a manually adjustable speed limiting control protruding from an outer surface of the impact wrench which is conveniently manually adjustable. The speed limiting control is coupled to the wiper arm of a speed limiting potentiometer which is electrically coupled to a speed control circuit within the impact wrench. The speed limiting potentiometer limits the maximum speed of the motor of the impact wrench (and thus the maximum torque which can be generated by the impact wrench 10) to an operator selected percentage of the maximum motor speed which would otherwise be produced when the trigger is fully engaged.

Abstract: A drive motor for a motor vehicle screen wiping apparatus operates with repeated reversals of its direction of rotation, and is controlled by a control circuit which is connected to a transistor arranged in the power supply path for the motor, in series with it. The transistor is put into conduction at a time, and in a manner, such as to reduce the audible noise caused by the repeated reversals.

Abstract: The invention is directed to a domestic appliance for processing foods, with a basic device (1) accommodating an electric switch (6) and an electric motor (5), as well as electrical connecting means (4) for connection to an electrical power supply. The basic device (1) includes an electric accumulator (7) for operation independently of the line.

Abstract: Process for stopping a record-shaped, rotating information medium, for example, a CD. CD-players, for example, are provided with a loading and unloading mechanism for the information medium, the CD. However, before a CD can be automatically unloaded by the CD-player after reproduction or activation of a STOP-key, the rotation of the CD must be stopped in order to avoid damages of its sensitive surface. Because the moment of inertia and the diameter of records (CDs) are varied, and because a small mini-CD exists, it may occur that the CD is still rotating during the unloading process. To stop the record (CD) safely independently of its moment of inertia and its size, a first applied braking pulse (B1) causes the record (CD) to be braked to full stop and subsequently to be accelerated in the opposite direction.

Abstract: A control circuit for a model railroad utilizes a digital counter to control the modes of motor operation. To select a mode of operation a switch is used to repeatedly ground the base of a transistor circuit, causing pulses to be sent to a counter. By using the switch to hold the base of the transistor to ground, the counter sequencing is locked and prevented from further sequencing until the track power is turned off for a defined minimum amount of time. Release of this switched ground places the circuit under track control where short power interrupts cause the counter to sequence to the next count and therefore to sequence the modes of motor operation.

Abstract: A zoom lens camera including a zoom taking lens having a zooming function, a motor for driving the zoom taking lens, a telephoto switch which is actuated to effect the motor to drive the zoom taking lens in a manner that increases the focal length thereof, a wide angle switch which is actuated to effect the motor to drive the zoom taking lens in a manner that decreases the focal length thereof, and a zooming speed controller for varying the zooming speed of the zoom taking lens when a predetermined condition is satisfied during the zooming operation when one of the telephoto switch or wide angle switch is actuated.

Abstract: A revolutions per minute (RPM) control device for hand-held electric tools, such as drilling tools and hammer drills, has a RPM sensor in a separate housing or container from the control device housing. The sensor is connected to the control device by a flexible cable. The sensor extends through an opening in the drive motor housing of the electric tool. The RPM control device can be used for a plurality of similar types of tools.

Abstract: An apparatus for controlling an elevator door comprises a motor for opening and closing an elevator door, an inverter unit for controlling the driving of the motor, a door position detecting unit for detecting the position of the door, first and second sensors for respectively detecting that the door passes through a terminal reference point on the opening side and a terminal reference point on the closing side, a speed command generating unit for generating a speed command on the basis of a distance between the door position detected by the door position detecting unit to a stop target on the opening side or the closing side when the first and second sensors respectively detect the passage of the door, and a control unit for controlling the inverter unit on the basis of the speed command output from the speed command generating unit.

Abstract: According to this invention, there is provided a drive circuit for a multi-phase brushless DC motor comprising a rotational position detector for detecting a rotational position of a rotor of the motor, a commutation control device for selecting a drive coil to be conducted from the plurality of drive coils, a drive output circuit for supplying a drive current to the drive coil selected by the commutation control devices, a DC servo control loop for detecting a motor speed on the basis of a counter electromotive voltage by rotating the motor and by supplying the drive current from the drive output circuit to the motor, and generating a comparison output in accordance with a difference between the motor speed detection output level and the reference voltage to output the comparison output to the drive output circuit through the commutation control device, and a control device for detecting whether the drive current of the drive output circuit is a predetermined value or more and for weakening a control force o

Abstract: The present invention is directed to an electric-car controller comprising a chopper for controlling the speed of a DC motor, a by-pass contactor for applying a DC source voltage directly to the DC motor, means for detecting that an acceleration command has reached a certain specified value or above, means for detecting that the acceleration of the car has dropped to a certain specified value or below, and means for turning on the by-pass contactor when the acceleration command has reached the certain specified value or above and the acceleration of the car has dropped to the certain specified value or below.

Abstract: A reversible control apparatus for controlling a motor is provided which is highly durable, weather proof, simple in structure and inexpensive to manufacture. The motor is controllably driven by a motor driver. A target rotational speed determiner determines a target rotational speed for the motor and generates a corresponding output signal. A rotational speed sensor senses the rotational speed of the motor and generates a corresponding output signal having no polarity which indicates the direction of rotation of the motor. A motor controller controls the motor driver. A polarity applying means applies a polarity to the output signal of the rotational speed sensor on the basis of the output signal of the target rotational speed signal and the output signal of the motor controller.

Abstract: A novel electric, gear driven, frequency controlled oscillating device that oscillates a toy mouse or other toys to amuse, occupy, and entertain pets. Because this unit is gear driven, it provides enough torque to insure self restarting after being stopped by a playful cat. The device has a low profile, thereby making it difficult to tip over. The cat toy operates in a very low variable voltage range, 6 volts DC, for maximum safety. The device is battery operated and has no exposed wires for pets to chew on. Device may be mounted in virtually any plane for further variation.

Abstract: A method and device for controlling a motor in a powered seat, wherein, in an automatic control mode, a rated voltage is applied to the motor, thereby causing a constant high rotation of the motor, and in a manual control mode, firstly the rated voltage is applied to the motor and secondly after a given time, the voltage is changed into a low voltage, causing the motor to be driven at a low rotation rate. Thus, the movable parts of seating posture adjustment device in the seat are moved rapidly in the automatic mode, while in the manual mode, they are firstly moved rapidly and then slowly for permitting an accurate adjustment of position thereof.

Abstract: A motor speed control system for a vehicle is provided. The control system includes an electric motor connected to a power coupling element for delivering electrical energy to the motor in response to a control signal. A sensor produces a current signal in response to the magnitude of the current flowing through the motor. An accelerator pedal produces a command signal in response to a desired vehicle speed. A microprocessor receives the command signal and responsively delivers a pulse width modulated control signal to the power coupling element. The control signal has a duty cycle in a range between a minimum and predefined value. Additionally, the microprocessor receives the current signal and increases the duty cycle of the control signal by a predetermined amount beyond the predefined value in response to the received current signal.

Abstract: A device for the electrical excitation of the coil or coils of an electromagnetic actuator, especially that of a linear motor, the coil of which has a low self-inductance. This coil is supplied by a bridge of transistors. The error between a reference voltage and a voltage proportional to the current in this coil is used to turn off a pair of transistors of the bridge, and simultaneously saturate a transistor of the other pair and make the other transistor work in linear mode. Two electronic switches and one sign discriminator are used to this end.

Abstract: A washing machine has a rotatable drum for holding items being washed and water for washing the items. The number of items in the drum and the amount of water in the drum may vary. Power is supplied from an inverter to a motor which rotates the rotatable drum. A speed control responsive to the inverter current regulates the drum rotating speed within a selected range.

Abstract: A motor control devise including an auxiliary resistor in series with the motor, a relay, including a coil for activation thereof for shorting the resistor, voltage terminals for determining the current in the auxiliary resistor and the voltage in the supply line, a microprocessor programmed to calculate the sum of the resistance of the supply line and the internal motor resistance, a time delay in energizing the relay for shorting the resistor immediately after the calculation of the resistances, and wherein the microprocessor is programmed to calculate instantaneous values of speed and torque of the motor.

Abstract: A variable speed control is provided for controlling a reversing permanent split capacitor motor in an automatic washer. The operation of the motor is controlled such that the motor will accelerate for a first predetermined time period and then coast with no power applied for a second predetermined time period. This generalized operation of the motor occurs in the spin cycle. In the agitate cycle, a logic decoding circuit uses a tach pulse signal indicative of the speed of the motor to provide a time for the motor to be on, and utilizes an AC line current zero crossing signal from a zero crossing detector to establish a time during which the motor is off, the motor on plus off time establishing a stroke rate for the agitate cycle.

Abstract: Drive apparatus, particularly for a twin polygon thermal scanner, utilizes a stepper motor driven by pulses of variable width timed, relative to the rotational position of the motor, so that the pulses are substantially centred on the maximum torque position of the motor. This minimizes power consumption. The control circuitry for the motor performs a start sequence, which is aborted and reinitiated in the event that the motor fails properly to start and in which the frequency of the pulses applied to the stopper motor is increased as the motor accelerates. Any excessive increase in the rate of increase of frequency of the pulses is detected and corrected. When the motor is running up to speed, the power applied to the motor is controlled by a phase detector which detects variations in phase between a referenced pulse train and a pulse train generated by the rotation of the motor.

Abstract: A power window switch for an automobile having a switching mechanism which includes a fixed contact plate and a circuit board secured within the inside of a resinous casing, the casing including a port. Positioned above the port is a button which includes a sloped elastic portion having its outer edge secured to the casing around the port. Compression of the button's sloped elastic portion places a conductive rubber contact attached to the bottom surface of the button into contact with a fixed contact on the fixed contact plate. The circuit board includes a switching circuitry which is responsive to variations in position of the button and attached conductive rubber contact.

Abstract: To control a reversible element (E), such as a motor and especially a motor operating a tape recorder tape transport, actual operating level input signals in form of timed pulses, depending on speed, and operating sign input signals are applied to a controller (8) through a frequency measuring circuit (5). The controller (8) compares the command level input signal and the actual input signal and provides corresponding error or control output signals. In accordance with the invention, a switch or gate (6) is interposed between the actual operating level input and a frequency measuring circuit (5) which, in turn, controls the controller, the gate or switch being conductive if and only if the sign of the actual operating signal and the sign of the command signal agree, as determined by an antivalence or AND-function gate (7). Upon disagreement of the sign signals, the gate is opened.

Abstract: A pulse-width modulation drive circuit for a load such as a motor, particularly, a motor used in a compact disc player or the like, in which losses in diodes used to absorb reverse EMF are substantially eliminated. For this purpose, the pulse widths of pulse signals used to on-off control drive current flow through the load are controlled so as to eliminate the diode losses. The circuits of the various embodiments of the invention are designed so as to be easily implemented in integrated circuit form.

Abstract: A control circuit for an electric motor is proposed, whose rate of rotation and rotational direction depends on a control signal (Ue) at the input terminal (10). The rotational direction is given by means of a determined control signal level being exceeded or fallen short of. The rate of rotation is controlled by means of a pulse width modulation of the control signal (Ue). There is a nonlinear relationship between the change in the pulse duty factor of the pulse width modulation and the control signal. The mean adjusting speed of an actuating motor accordingly adapts to the control deviation signal of an actuating control.

Abstract: A controller for controlling the movement of a member such as a sliding door driven by a motor. The door is controlled by the use of a motion detector coupled with the door. Pulses from the motion detector are counted by control circuitry, and the door is moved at a reduced speed in the region of its limits of travel. The limits are defined by the number of pulses from the motion detector equalling a predetermined value. The motor is de-energized if a stationary state of the door is detected in the low speed region, and reversed if a stationary condition is detected in the remainder of its movement.

Abstract: For the purpose of giving the user of an electric control of a venetian blind in a window the possibility of adjusting the angular position of the slats independently of raising or lowering the venetian blind by utilizing an electric motor, spring clutches, and corresponding lift cords, the electric control includes a control circuit with a three position switch controlled by the user. The control circuit is arranged so as to drive the motor at a low speed during a first predetermined time interval for adjusting the angle of the slats and thereafter to drive the motor at an increased speed for raising or lowering the venetian blind.

Abstract: A monocular and binocular spinning optics device for use by doctors, researchers, etc., that creates a specific visual phenomenon in front of one or both eyes of the person wearing the device wherein the lenses are constructed by cutting out and affixing stick-on type lens material, such as fresnel prisms, polarizing material, colored filters, cylinder prisms, reflective material, etc., to a plano-plastic disc. A drive motor rotates the rotating lens, which is held in registry with a stationary, non-spinning lens by spectacle frames. The direction and speed of the motor and therefore the rotating lens, along with any pauses or repetitions, are controlled by a digital computer containing the visual training program, and the visual training program, as well as the construction of the lenses, can be devised by the orthoptic practitioner.

Abstract: A control device for a reversible D.C. electric motor to protect it against damage upon reversal has a input switch circuit for reversing the flow of current through the motor's armature for reversing the direction of rotation of the motor, a first control circuit for preventing flow of current via the input switch circuit to the armature initially upon current reversing and a second control circuit for periodically interrupting the flow of current while the motor gains rotational speed after being reversed in relation to the magnitude of the flow of current through the armature. The first control circuit includes a detector circuit for determining the voltage drop existing across the armature and an automatic switch unit for (1) blocking flow of current from the input switch means to the armature until the voltage drop is determined by the detector circuit to be in a predetermined range and (2) allowing flow of the current while the voltage drop is determined to be within the range.

Abstract: A method for supplying the excitation to a four quadrant drive DC electric motor having a forward and reverse controllable bridge rectifier power regulators for controlling the direction of motor rotation. The motor control system is capable of operating in a continuous and discontinuous current mode of operation and includes an electronic control circuit for calculating a firing angle from desired and measured system parameters.The electronic control system includes a reversing controller for developing a current command for generating firing pulses to fire selected switching elements in the power regulators for controlling the magnitude and polarity of the excitation, and a current sensor for sensing motor current. The method provides a smooth, continuous transitioning between the forward and reverse bridge in response to a sensed requirement for reversing excitation to the motor.

Abstract: A drive circuit for servomotors that eliminates the need for microswitches to protect the motor when the system is driven to its limits of travel. The circuit monitors the current to the motor, identifies overload currents and terminates current flow to the motor when an overload occurs. The current flow is restored only when a reverse rotation command signal is received by the drive circuit.

Abstract: A driving circuit for a DC motor in which the accuracy of the voltage applied to the motor when it is driven with a fixed voltage is improved and the fixed voltage is continuously applied for fixed-speed rotation control. The emitter of a motor driving transistor is connected to the first terminal of the DC motor, the other terminal of which serves as a reference terminal. A voltage is supplied between the collector of the transistor and the reference terminal of the motor, and a bias current is supplied to the base of the transistor. A voltage source produces a voltage which is at a fixed level with respect to the potential of the reference terminal of the motor. A diode arrangement, preferably composed of serially connected transistors each of which has its collector and base connected together, passes current between the voltage source and the base of the driving transistor.

Abstract: A control for controlling the operation of a direct current motor by select application of a three phase alternating current line input of given frequency to the armature thereof through solid-state forward and reverse designated switches which are gated by select enable inputs.

Abstract: An apparatus for driving a turntable of a disc player system including a first drive voltage source for supplying a first driving voltage driving a spindle motor in a normal direction, a second drive voltage source for generating a second drive voltage for driving the spindle motor in a reverse direction, a voltage supply control circuit means for selectively supplying one of first and second drive voltages in accordance with a play command signal and a stop command signal, and a detection means for detecting the rotation of a rotor of the spindle motor in the reverse direction. When the stop command signal is supplied, the second drive voltage is supplied to the spindle motor for applying a driving torque of reverse direction to the rotor of the spindle motor and the supply of the second drive voltage is stopped immediately when the reverse direction rotation of the rotor is detected by the detection means. Thus, a very quick and accurate control of the stoppage of the spindle motor is realized.

Abstract: A new method and apparatus for controlling the conversion of AC electrical energy into DC electrical energy. A microprocessor control system is operatively connected to an AC source and to a motor/regenerative switching bridge network. A control signal is operatively coupled to the microprocessor to selectively adjust the DC output voltage. The microprocessor monitors the control voltage, calculates the timing of gating signals and generates gating pulses to the bridge networks. The microprocessor also senses the phase rotation and the line frequency of the AC source and factors those parameters into account when determining gate pulse output pattern and timing.

Abstract: A PWM controller for an electrical utilizes a dual differential input topology comprising two input comparators deriving a proportional reference from two potentiometers for providing a variable pulse width modulated output. The pulse width modulation controller of the present invention does not require scaling and may be utilized in appliances, robotics, toys and in conjunction with other electromechanical and electrical loads.

Abstract: An improved arrangement for controlling the speed and direction of rotation of a DC motor responds to a variable bipolar input signal. A bipolar threshold detector coupled to the motor is used for the selective triggering of a triac during the appropriate half wave polarity of an AC source. Triac failure is prevented by a protection circuit. The arrangement incorporates a speed servo and senses the voltage across the triac to detect the speed of the motor.

Abstract: A traction elevator system having an elevator car driven by a dual converter bank, solid state motor drive. The solid state motor drive includes bank selection circuits, which select the operative converter bank at any instant, and firing circuits for providing firing pulses for the selected converter bank. The energization and deenergization of the bank selection circuits and firing circuits are controlled such that the bank selection circuits are energized before the firing circuits, and, upon loss of power, the bank selection circuits are deenergized after the firing circuits.

Abstract: A chopper controller for a D.C. motor controls currents flowing in an armature winding and a field winding of the D.C. motor by controlling an armature chopper and a field chopper in accordance with a command from a command generator such as an accelerator pedal. The armature chopper and the field chopper are controlled by chopper control signals from an armature chopper control circuit and a field chopper control circuit, respectively. Those chopper control signals are in a predetermined phase relationship and an interruption request signal is issued in phase-synchronism with one of the chopper control signals. In response to the interruption request signal, computing means computes an armature chopper duty factor and a field chopper duty factor in accordance with the command from the command generator and supplies them to the chopper control circuits.

Abstract: The direct-current motor comprises at least one field winding supplied intermittently with direct-current voltage in order to produce a driving torque by interaction with permanent-magnetic poles which rotate with respect to the winding. The electromotive force of induction produced in the winding by the relative rotation of the permanent-magnetic poles is detected by means of a voltage measurement during the time intervals which elapse when the winding is not energized. A low-speed signal is produced when the electromotive force is below a pre-established threshold in correlation with the desired speed-threshold value.

Abstract: In a firing angle control system for a converting device for an AC electric motor-vehicle fed with AC electric power and having, as its main electric motor, a DC electric motor, the converting device including a main rectifier connected to the armature and a field rectifier connected to the field winding, an abrupt change in the AC voltage of the converting device is detected and, upon such detection, a main rectifier voltage target signal is corrected to compensate for a difference in the rate of change between the armature current and the field current which would occur if the correction were not made.