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

Abstract: A brushless, synchronous direct current motor is operated by supplying a direct current voltage as an input voltage for commutating the motor phase windings. The speed of the synchronous motor is modified or varied in two speed ranges. In the first speed range, a linear change of the input voltage is carried out up to a speed threshold value. In the second speed range with higher speeds than in the first speed range, a vector modification of the input voltage is carried out, for example for controlling the speed of a fan motor.

Abstract: Control of a motor in a device in which a mechanism is driven using the motor as the power source is achieved by providing velocity servo-control means for outputting first command information regarding the motor based upon a preset velocity profile and information relating to velocity of the mechanism, and position servo-control means for outputting second command information regarding the motor based upon a preset position profile and information relating to position of the mechanism. A motor driving signal is generated, based upon the first and second command information, in a region in which the mechanism is to be accelerated in the velocity profile. As a result, target-velocity attainment time is shortened and velocity fluctuation after attainment of the target velocity is reduced.

Abstract: In controlling a motor in a device which drives a mechanism using the motor as a power source, pre-driving of giving a predetermined driving parameter to the motor and driving the mechanism is executed. During the pre-driving, movement of the mechanism is monitored, and a command value to the motor, which is necessary for starting the mechanism, is obtained. Driving of the motor is controlled using feedback using the command value as the initial value of the driving parameter. High-speed accurate position control can be achieved independently of the individual difference in an object to be controlled and the frictional force of the mechanical portion or the difference in use environment.

Abstract: The invention concerns an arrangement for powering a load (12) that has non-continuous power consumption from a DC power supply (UB). The arrangement has a DC link circuit (14, 22) to which said load (12) can be connected and with which is associated a capacitor (21) that is suitable for briefly supplying energy to the load. A current regulator (24, 30) is provided for connecting the DC link circuit (14, 22) to the DC power supply (UB) in order to deliver a substantially constant current (i) to said capacitor (21) and to a load (12) connected to the link circuit. The target value of said current regulator (30) is adjusted adaptively, by means of a second regulator (34), to the instantaneous power demand of the load (12). An arrangement of this kind can also be referred to as an active filter that is particularly suitable for electronically commutated motors and for motors with a PWM current controller.

Abstract: A process and a circuit (2) for regulating the speed of an electric motor (1) having a high speed (N1) to at least one additional lower speed (N2, N3, N4), whereby, in a first prioritized step, depending on a preselected speed (N1, N2), the regulation of the speed to a lower effective motor voltage (Ueff) has an upper limit, and in a second step, depending on the torque (M) needed for the regulation to this preselected speed (N1, N2), the effective motor voltage (Ueff) is regulated within the limited range.

Abstract: Practically ideal electrical resonance is employed to soley provide armature power, and stator power if desired, to run DC motors. A practically ideal parallel resonant tank circuit (PIPRC) is used wherein the quotient of the “tank current” divided by the “line current” (called the “quality” or “Q” of the tank) is (1) greater than one, (2) large enough to allow the percent efficiency of the electric motor to be equal to or greater than 95%, and (3) removes enough back emf or enough of the influence thereof so that criteria (1) and (2) can be realized throughout the entire operating range of the motor. Only one PIPRC is needed for a DC motor. Recontrolling and/or redesigning is done for two reasons.

Abstract: In a motor driving apparatus, a driving circuit drives a plurality of loads contained in a plurality of motors, and a control circuit controls the driving circuit to sequentially drive the motors. The driving circuit is provided with at least n+1 number of output terminals in order to connect thereto n number of loads, each of the output terminals being led out from a node of a PNP type transistor and an NPN type transistor connected in series through the node in such a configuration that each pair of the output terminals adjacent to one another constitute a bridge circuit assigned to drive one load. The control circuit turns on and off the PNP and NPN type transistors of the bridge circuit to thereby energize the load in either of a normal direction and a reverse direction.

Abstract: DC motor rotation speed alarm circuitry includes an input node, a connection node, a ground node, a comparison circuit and a signal generator. When the rotation speed of the DC motor changes during operation, floating voltage is generated between the driving circuit and the ground node. If the floating voltage is less than a preset voltage of the comparison circuit, the alarm signal outputted by the signal generator indicates that the DC motor is operating normally. If the floating voltage is greater than the preset voltage of the comparison circuit, the alarm signal outputted by the signal generator indicates that the DC motor is operating abnormally.

Abstract: A fan motor driving circuit of the present invention comprises a device for detecting a power source voltage and outputting a voltage in proportion to a difference between the power source voltage and a predetermined rated voltage when the power source voltage is greater than the rated voltage. The driving circuit also includes a device for controlling a rotary speed of a fan motor to a predetermined value by automatically varying a first signal input to a conducting current generating circuit for determining the rotary speed of the fan motor according to an output voltage of the power source voltage detecting means when the power source voltage is greater than a predetermined value.

Abstract: The invention relates to a method for regulating an electrical machine (1) with an excitation winding (2) and a stator winding (3). The stator winding (3) is connected at its output terminals (10) to a converter bridge (5). The electrical machine (1) can be operated in the regulation ranges of field-oriented regulation (11), field-weakening operation (12), and diode operation (13). The transition from one of the regulation ranges (11, 12, 13) to a respective adjacent regulation range (11, 12, 13) is achieved through an overmodulation of the pulse-to-width modulation (26) and a limitation of the outputs from current regulators (34, 35) of the stator winding (3) of the electrical machine (1).

Abstract: Disclosed is control circuitry for providing controlling a motor responsive to feedback signals. The control circuit includes a velocity sensor for coupling with the motor for providing a velocity feedback signal responsive to the velocity of the motor, and circuitry for providing a feedback signal responsive to a voltage associated with the motor, such as the back emf of a coil associated with the motor. The control circuitry can be used enhance the Z-axis control of a tool of a work apparatus for performing work operations on a work material, such as a cutting apparatus for cutting a sheet of vinyl having a releasable backing for generating graphic products.

Abstract: A system and method determine the parameters of a field of a DC motor. The method comprises obtaining parameters of the DC motor; and performing an iterative processing loop, the iterative processing loop being performed n times. The iterative processing loop includes regulating field current based on the parameters of the DC motor, and calculating a field resistance from a field voltage and the field current measured during the regulating of the field current; operating in a closed loop mode to determine a first field firing angle and a second field firing angle; operating in an open loop mode to determine a first time constant and a second time constant based on applying the first field firing angle and the second field firing angle; and determining at least one parameter of the field of the DC motor based on the first time constant, the second time constant, and the calculated field resistance.

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

Abstract: In separately excited DC brush motors ML and MR, an armature current control circuit for feeding power to armatures 61 and a field current control circuit for feeding power to a field system 62 form separate systems and are independently controllable except that both the control circuits share a battery B2 between them. When the overrotation of the motors ML and MR is detected from the backflow of an armature current and a rise in the voltage of the battery B2 or when the reverse rotation of the motors ML and MR is detected from an increase in the armature current and a decrease in PWM for the armature current, the generation of counter electromotive force is restrained by reducing the field current of the motors ML and MR so as to prevent the armature current control circuit from being damaged.

Abstract: A motor controller for regulating the speed and limiting the input current to a dc motor is disclosed. The motor controller includes an electronic control unit, a current sensor and a speed sensor. The motor controller provides control of the dc motor by applying a varying voltage to maintain a motor speed in the presence of a varying load. The motor controller also monitors the input current to the dc motor to predict an input current to the dc motor. The ECU compares the predicted input current to a input current limit range and switches to a current-limiting mode when it determines that an overcurrent condition is reached based on the comparison. The motor controller modifies the control signal by a first control decay factor when the predicted input current exceeds the input current limit range. The motor controller modifies the control signal by a second control decay factor when the predicted input current is within the input current limit range level.

Abstract: The invention relates to a method and system for linear speed control for electric direct current motors, in which a digital to analog converter means is used for converting an 8-bit digital signal to an analog voltage for setting voltage across a motor, a digital state machine means is used for converting the duty cycle of an input signal for output to the digital to analog converter means, and a closed loop feedback means is used for monitoring and setting the voltage across the motor. An over-current sense circuit can be used for monitoring the current across or passing through the electric motor. An over/under voltage sense circuit can be used for monitoring voltage of the electric motor. The resulting 8-bit digital control signal is converted to an analog voltage for the electric motor.

Abstract: Systems, methods, and apparatus, consistent with principles of the present invention, allow an unmodified device, for example, a dc starter motor, that normally operates at a first voltage to function in an electrical system providing a second voltage, which is different from the first voltage, and received from the power source. A device actuator, such as a solenoid, is controlled using the second voltage. The first voltage is produced and supplied to the device in response to a first action of the actuator, for example, upon solenoid depression. This voltage is then inhibited from being provided to the device in response to a second action of the actuator, for example, upon solenoid retraction after engine cranking.

Abstract: A motor controller for regulating the speed and limiting the input current to a dc motor is disclosed. The motor controller includes an electronic control unit, a current sensor and a speed sensor. The motor controller provides control of the dc motor by applying a varying voltage to maintain a motor speed in the presence of a varying load. The motor controller also monitors the input current to the dc motor to predict an input current to the de motor. The ECU compares the predicted input current to a input current limit range and switches to a current-limiting mode when it determines that an overcurrent condition is reached based on the comparison. The motor controller modifies the control signal by a first control decay factor when the predicted input current exceeds the input current limit range. The motor controller modifies the control signal by a second control decay factor when the predicted input current is within the input current limit range level.

Abstract: A variable speed power tool may include a speed adjusting device and/or a maximum speed adjusting device for adjusting the operating speed, and a fixed operating speed switch. An operator adjustable speed adjusting device having a position maintaining mechanism also may be utilized. When manipulated by the operator, the fixed operating speed switch gives priority to the adjusted position of the speed adjusting device and adjusts the operating speed to a preset operating speed. In the alternative, a switching device and an internal integrated circuit may be utilized to adjust the operating speed to a target speed using feedback control. The switching device preferably selects a voltage corresponding to the target speed from either a voltage representative of the position of the speed adjusting device or a predetermined voltage representative of the present operating speed.

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

Abstract: A power supply for DC motors, in particular for actuators for use in the adjustment of tables, beds and the like, comprises a transformer (T1) with a rectifier (D1-D4); and a buffer capacitor. The power supply comprises voltage limiting unit (Z1) coupled in parallel with the motor and connected to switch unit (Q1) so that the motor is connected on a first part of the sine half-waves, but is disconnected when the voltage determined for the voltage limiter is reached. This ensures a good mean voltage, and the voltage does not exceed an upper permissible value. This also means that the motor speed is more independent of the load, which is an advantage e.g. in case of height-adjustable tables. In an embodiment, the power supply comprises additional means for measuring the current power in the motor, and this measurement is used as a feedback for controlling the motor speed to keep the speed of the motor.

Abstract: A pulse generating circuit for motor rotation of a direct current motor which is capable of pulse generation following the variation of the motor rotation condition and of stable ripple pulse generation. The pulse generating circuit for motor rotation includes a filter for varying a cut-off frequency fc by the signal from outside and for removing the noise based on the input signal from the direct current motor, a pulse forming circuit for forming the ripple pulse in accordance with the motor rotation of the direct current motor based on the output from the filter, a clock generating circuit for varying the cut-off frequency fc of the filter by providing the clock signal fCLK which is generated based on the rotational condition signal of the ripple pulse and the direct current motor to the filter, and a pulse correction circuit for generating the corrected ripple pulse when the frequency ratio between the ripple pulse and the clock signal fCLK is deviated.

Abstract: A motor controller utilizes sensors to detect the rotational speed and relative position of the motor rotor and generates a voltage vector to maintain the motor current in phase with the EMF before a voltage limit is reached. The approximate actual speed is calculated and position signals are generated by the calculator. The actual speed is compared with a command speed signal and any difference gives rise to an error signal. A proportional integrator receives the error signal and produces a correction signal for a vector rotator corresponding to the desired vertical voltage component necessary to achieve the command speed. After the voltage limit is reached, any further speed increase desired is achieved by rotation of the voltage vector with it's amplitude unchanged.

Abstract: An apparatus (10) for controlling an electric motor (36) having a plurality of motor phases includes a motor controller (32) that controls energization of each phase of the plurality of motor phases. A compensation circuit (56, 84, 104) is associated with each phase of the plurality of motor phases. The compensation circuit (56, 84) of one phase of the plurality of motor phases adjusts a control parameter of another phase of the plurality of motor phases an amount functionally related to an electrical characteristic of the one phase in response to determining a diminished operating characteristic of the one phase.

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

Abstract: The invention relates to A method for determining a rotational velocity of a transducerless polyphase machine that is operated in a field-oriented manner, a stator-current model space vector and a conjugate complex reference space vector being calculated using a complete machine model, and the torques-active and dummy variables being measured from these model space vectors and from the measured stator-current actual space vector, from which active and dummy variables, in each case, a system deviation is determined. These measured system deviations are weighted and finally totaled, this total system deviation being used for adjusting the model rotor angular velocity such that the total system deviation becomes zero. Thus a method for determining the rotational velocity of a transducerless polyphase machine that is operated in a field-oriented manner is possible, breakdown protection being assured.

Abstract: In a closed loop control system that governs the movement of an actuator a filter is provided that attenuates the oscillations generated by the actuator when the actuator is at a resonant frequency. The filter is preferably coded into the control system and includes the following steps. Sensing the position of the actuator with an LVDT and sensing the motor position where motor drives the actuator through a gear train. When the actuator is at a resonant frequency, a lag is applied to the LVDT signal and then combined with the motor position signal to form a combined signal in which the oscillation generated by the actuator are attenuated. The control system then controls ion this combined signal. This arrangement prevents the amplified resonance present on the LVDT signal, from causing control instability, while retaining the steady state accuracy associated with the LVDT signal.

Abstract: The present invention provides a multistage rotating speed control circuit which is connected to a positive DC supply voltage and controls the rotating speed of the DC motor. The multistage rotating speed control circuit comprises a digital control circuit and a driving circuit. Besides, it comprises an input voltage modifying circuit which delivers an input voltage; a reference voltage generating circuit which provides a fixed number of reference voltage; and a comparing circuit consisting of the fixed number of comparators, each of which receiving the aforementioned input voltage at its positive end and a different reference voltage generated by the reference voltage generating circuit at its negative end, delivering an output digital signal based on the comparison result of the two input signals, these output digital signals collectively making up an input digital signal set for the digital control circuit.

Abstract: An apparatus for controlling an actuator in response to a target speed voltage signal, the actuator having a moveable member and having a coil that influences movement of the member. A first summing node is provided having a control output voltage, for summing or subtracting voltages applied thereto, as the case may be and receiving the target speed voltage signal at a first, summing input thereto. A proportional compensation unit is provided, receiving the control output voltage and providing as an output a proportionally compensated output signal. An integral compensation unit is provided, receiving the control output voltage and providing as an output an integrally compensated output signal. An inverse compensation unit is provided, receiving the target speed voltage signal as an input and providing an inversely compensated output signal having a voltage corresponding to the voltage of the target speed voltage signal multiplied by the inverse of a predetermined amplification factor.

Abstract: A DC motor driven power steering system for a motor vehicle includes a motor current detection circuit for detecting a motor current flowing through the DC motor, a power supply voltage detection circuit for detecting a power supply voltage applied to the bridge commutation circuit, a motor voltage estimating unit for estimating a voltage applied across the DC motor on the basis of the power supply voltage applied to the bridge commutation circuit and the pulse-width modulated control signals used for controlling the bridge commutation circuit, and a motor rotation detecting means for detecting the rotation state of the DC motor on the basis of the motor current and the estimated motor voltage applied to the DC motor. High reliability can be ensured for detection of the rotation state of the DC motor.

Abstract: An integrated transmission is effectively achieved within a series-excited motor by varying the number of winding turns in the field coil in relation to the speed-torque demand on the motor. At low motor speed, all of the field winding is engaged to produce the maximum available electromagnetic field, thereby increasing the motor's available torque and efficiency. When there is a high torque demand at high speed, only a portion of the field winding is engaged so that a reduced electromagnetic field is produced, thereby allowing a higher current in the motor, thereby allowing a higher torque to be produced. Thus the series motor with integrated transmission will have the same speed-torque characteristics as a system with a series motor and a conventional transmission. The integrated transmission can be implemented with relatively inexpensive relays and, if desired, by adding additional winding turns in the series field.

Abstract: A motor which has a first motor winding that provides a motor back EMF during operation of the motor, and which is operable by a supply current to develop, at a predetermined nominal rotational speed, a predetermined nominal torque corresponding to a predetermined operating current and a predetermined nominal back EMF, is calibrated by applying a supply current to the motor such that the motor operates at a known rotational speed, disconnecting the supply current from the motor such that the motor decelerates from the known rotational speed, and obtaining an EMF indication of motor back EMF. The EMF indication is compared with the predetermined nominal back EMF, and a supply current adjustment that provides for compensation of the supply current based on the EMF indication and the predetermined nominal back EMF is developed, such that the motor produces the predetermined nominal amount of torque when operated at the predetermined nominal rotational speed.

Abstract: The motor control system is operable with multi-phase bipolar parallel winding brushless DC motor. The motor control system includes multi-phase bipolar H-bridge circuits which change current flow direction as the output signal from motor encoder changes. The motor control system is responsive to the speed control circuit to control speed and to the fault detection circuit to give maximum safety and control. The motor control system provides controlled phase signal to individually enable each phase of the stator windings to selectively control the speed of the motor. The motor control system also has a conventional pulse width modulation driver for providing power to the motor. The motor control system of the present invention utilizes both modes to fully utilize the motor's capabilities and at the same time saves power and reduces loading in each of the H-bridges driving stator windings.

Abstract: The DC electrical motor system includes a motor having an armature DC transducer coupled to an armature current controller by a sensor/detector arrangement to control the armature current. A field DC transducer coupled to a field current controller by another sensor/detector arrangement facilitates the control of the field current. An armature-field comparator is coupled to the field current controller to help control the field current when the motor armature windings are short-circuited through windings in the armature field comparator.

Abstract: An electric current control method for a servomotor in which a reactive current is lowered in a region where a voltage saturation does not occur, to suppress generation of heat caused by the reactive current and achieve a stable rotation up to a high-speed region. In the current control of the servomotor using a DQ conversion, an electric current is not supplied to d-phase and supplied only to q-phase when a rotational speed of the servomotor is not high, and the reactive current is supplied to the d-phase only when the rotational speed of the servomotor is high, to thereby lower the terminal voltage of the servomotor by the reactive current. Thus, the reactive current is reduced in the region where the voltage saturation does not occur, to thereby suppress the generation of heat due to the reactive current, and also achieve the stable rotation even in the high-speed region.

Abstract: A memory device, e.g. a capacitor, is provided for a collectorless DC motor. This component is charged whenever a particular rotor position is reached. In so doing, a voltage value or quantity on this memory device is changed. This quantity is compared to another quantity, which is dependent on a desired parameter, e.g. ambient temperature or gas or dust concentration. A reference signal is produced when a particular reference criterion is satisfied. The difference between the beginning of this reference signal and a second predetermined rotor position, which follows the initial predetermined rotor position with respect to time, is measured, and on the basis of this measurement, the current flow of the collectorless DC motor is influenced or regulated. In particular, the current can be toggled on and off as the rotor passes certain predetermined positions.

Abstract: A DC motor driven power steering system for a motor vehicle includes a motor current detection circuit for detecting a motor current flowing through the DC motor, a power supply voltage detection circuit for detecting a power supply voltage applied to the bridge commutation circuit, a motor voltage estimating unit for estimating a voltage applied across the DC motor on the basis of the power supply voltage applied to the bridge commutation circuit and the pulse-width modulated control signals used for controlling the bridge commutation circuit, and a motor rotation detecting means for detecting the rotation state of the DC motor on the basis of the motor current and the estimated motor voltage applied to the DC motor. High reliability can be ensured for detection of the rotation state of the DC motor.

Abstract: An electric motor control for a series-wound DC motor for providing speed control and also for controlling regenerative braking. The regenerative braking is energized either when the accelerator pedal is released and/or when a brake pedal is depressed. In addition, the control circuit limits the total vehicle speed and brakes the vehicle if it is stopped and begins to roll due to gravity.

Abstract: A delay signal rising after the passage of a predetermined time from the rising or falling of a position signal is formed by means of a delay circuit. While an offset circuit is used for sequentially monitoring the size relation between an induced electromotive voltage and a coil neutral point voltage, an offset is applied to the induced electromotive voltage when a regular speed detection signal is output from a comparator at the time the induced electromotive voltage and the coil neutral point voltage cross each other so as to raise the induced electromotive voltage up to the vicinity of a supply voltage Vcc or otherwise lower the induced electromotive voltage up to the vicinity of the ground potential.

Abstract: A device includes an FET 206 interposed between one end of a motor 201 and a positive electrode of a battery EB; a diode 203 for circulating an electric current so as to flow through the motor 201 after the switching means is turned off, the electric current is the same as that which has flown through the motor 201 before the switch 220 is turned off; a shunt 203a, differential amplifier 203b, and a low-pass filter 203c as means for detecting a value of an electric current flowing to the motor 210; and a controller 250 for turning on and off the switching means by the PWM control, so that the value of the electric current detected by the current detection means coincides with a target value. The controller 250 sets a very small value as the target value when the motor is rotated by inertia thereof, and supplying the electric current of the small target value to the motor 201.

Abstract: A device for the optimizing of the speed control of an electric subfractional horsepower motor for dental instruments is provided wherein it is possible to operate the motor in any desired speed range. The device contains a first module for regulating the speed by voltage measurement, a second module for regulating the speed by current-load compensation, and means for deciding which of the two modules and in what proportion they assume speed regulation of the motor.

Abstract: A system for controlling a separately excited dc motor, where control is achieved through a microprocessor-based independent PWM control of a chopper (armature) and an H-bridge (field), and where mechanical speed sensors are not used. Connected to the armature is an armature voltage amplifier for varying the applied armature voltage. A field current amplifier is also provided for determining the direction of motor rotation and varying the voltage applied to the field winding. A decoupling controller adjusts the armature voltage and the field current.

Abstract: A method of controlling the commutation of power to an electric motor back EMF sensing or Hall effect sensors is disclosed. At least part of the current waveform is sensed in at least one motor winding and is used to establish information relating to the appropriate commutation pattern required to commutate power to the motor and control motor parameters e.g. motor speed.

Abstract: A direct current (DC) electrical motor system includes a DC electrical motor having energy conversion armature windings conducting a first electric current, and an electromagnetic field windings conducting a second electric current. The system also includes means to maintain the magnitude of the second electric current in the electromagnetic field windings at a substantially constant ratio of the magnitude of the first electric current in the energy conversion armature windings. Thus, the magnitude of the ampere-turn strength of the electromagnetic field of the motor is substantially always a ratio of the magnitude of the electric current in the energy conversion armature winding circuit of the motor, and the DC electrical motor of this invention performs substantially the same as a conventional series wound DC electrical motor.

Abstract: A motor controller for brushless motors operates an inverter in a current-controlled mode for low motor speeds and in a voltage-controlled mode for high motor speeds. By switching from the current-controlled mode to the voltage-controlled mode at higher speeds, the motor can be designed at maximum efficiency, and minimum weight, cost and volume.

Abstract: A multiple output stepped compound voltage supply includes a field intensity control which enables a DC motor control circuit to provide continuous linear or pulse modulation control among the stepped voltages in relation to the voltage output.

Abstract: A method and system for sensing the rotor speed of a brushless permanent magnet motor wherein a signal containing isolated third harmonic components of the flux density is acquired, and the absolute values of the maximas of the signal are measured, the last measured absolute maxima representing the current rotor speed of the motor.

Abstract: A closed-loop feedback control system is disclosed for controlling an operation of a load. An actual operation signal is subtracted from a reference operation signal to produce a resultant signal which is used to control the operation of the load. A filter unit, such as a notch filter, operates to suppress any machine resonance frequencies found in the operation signal due to load fluctuations, machine variations, operating environment changes, deterioration with age, etc. A filter coefficient of the filter unit is adjusted so that any fluctuation in the resonance frequency can be suppressed effectively.

Abstract: A brake lathe for truing brake rotors includes a tool holder driven by a direct current motor to move a cutting tool radially with respect to the rotor axis in direct proportion to the number of turns of the drive shaft of the direct current motor. A tool feed power control circuit maintains the direct current motor at constant speed regardless of radial forces acting upon the cutting tool and includes a converter/filter circuit, a regulator circuit, a sensing circuit, and a speed control circuit. A speed selection control includes a rheostat for providing a reference voltage corresponding to a select speed. The sensing circuit compares a voltage drop across the direct current motor to the reference voltage and produces an error voltage. The speed control circuit provides a direct current power voltage to the direct current motor in accordance with the error voltage output of the sensing circuit to maintain operation of the motor at constant speed.