Abstract: The invention relates to a method for enhancing the dosing precision of a dosing pump which is driven by an asynchronous motor via an eccentric gear. The supply of the motor is cut off approximately half a cycle time before a desired dosing pause period or stoppage. The motor freewheels afterwards for part of the cycle time, before a direct voltage is applied to it for approximately a quarter cycle time, such that an eddy current is induced in the rotor, which produces an antipolarized magnetic field which brakes the rotor.

Abstract: A double pole, double throw switching arrangement for effecting dynamic rotor braking of user controlled operation of a reversible direct current servo motor. Two columns of stationary center and oppositely disposed side contacts are disposed in spaced parallel arrangement on the switch base. One side contact in one column is connected to the opposite side contact in the other column and to the B+ supply. The remaining side contacts in each column are connected to a ground strap having a portion disposed for wiping contact. A pair of commonly user actuated moveable contact members are disposed for sliding contact with each column of contacts. The center contact in each column is connected to one end of a separate forward and reverse motor coil. In the neutral position both motor coil contacts are grounded. User movement of the common actuator in one direction simultaneously causes the moveable contact members to keep one motor coil grounded and connect the other motor coil to B+.

Abstract: A method of stopping an electric motor-driven balancing machine main shaft after an unbalance measuring run in a specific rotary angle stoppage position corresponding to a desired balancing rotary angle position provides that in the course of retardation of the main shaft, a timer is switched on at a short angular spacing of for example 3.degree. before the main shaft reaches the desired rotary angle stoppage position. The timer predetermines a time interval which is determined from the rotary speed and the rotary angle position of the main shaft at the time of the timer being switched on, with the retardation operation being stopped at the end of that time interval, with the main shaft stationary. The retardation operation can be effected by torque reversal of the motor.

Abstract: A motor control device that can control the rotational direction of a rotor with polarity in an initial position detection. The motor control device includes first metering voltage signal generating system for sequentially creating 2N-phase signals to an N-phase motor, current metering system for measuring stator winding current, and first rotational position arithmetic system for detecting an absolute rotational position corresponding to an electrical angle of 180.degree. based on the measured current.

Abstract: An electric machine includes a rotor and a stator, a rotor position transducer being provided to detect the position of the rotor relative to the stator. Phase windings are sequentially energizable to drive the rotor. The rotor position transducer is powered by the energization of one or more windings thus removing the need for an additional power supply for the rotor position transducer.

Abstract: A control circuit (10) is provided for an electric motor brake (12) having an electromagnetic brake coil (14) energizable to actuate the brake to a released condition permitting rotation of an electric motor (16), and de-energizable to enable actuation of the brake setting the brake to a braking condition stopping rotation of the motor. The control circuit includes a switch (102) having an on state energizing the brake coil, and an off state de-energizing the brake coil.

Abstract: A method of smoothly stopping pump drives without pressure surges is provided. To accomplish this, the phase control angle between the motor current and the motor voltage is increased according to a linear ramp starting from 0.degree. with the help of an a.c. power controller, where the phase angle decreases and reaches a turning point. If the turning point is detected by observing the phase angle, the phase control is based on this by means of a controller with a predefined linear phase angle reference curve as a function of time. Then the motor rpm does not change abruptly because a rapid change in phase angle is prevented.

Abstract: A drive circuit for a switched reluctance motor has phase circuits connected to a common dump capacitor which receives residual magnetic energy from each phase coil when it is switched off. One or more recovering phase circuits are connected to the dump capacitor and comprise a controlled switch and diode whereby energy stored in the dump capacitor is returned to a recovering phase coil in sequence.

Abstract: A motor drive particularly suited for decelerating an AC motor includes a signal converting circuit, a monitoring circuit and a control circuit. The signal converting circuit is coupled to a source of DC power via a DC bus and a capacitive circuit is coupled across the DC bus to store energy produced by the motor during deceleration of a primarily inertial load. The signal converting circuit produces and applies drive signals to the motor based on control signals from the control circuit. The control circuit produces control signals for generating an output waveform duty cycle for the drive signals suitable for maintaining a predetermined voltage-to-frequency relationship. The frequency of the output signals is selectable to control the output speed of the motor. During deceleration, the monitoring circuit detects rises in the DC bus voltage, indicating that the motor is tending to slow at a rate less than the desired deceleration rate.

Abstract: A method and apparatus to be used with a motor controller for determining the speed of the motor rotor using current zero crossing times of the stator winding currents. An error signal set, consisting of phase angle errors between consecutive zero crossings over a sampling period, is generated and analyzed in a region of interest in either the time or frequency domain, producing a signal frequency, the signal frequency being the frequency of the motor rotor.

Abstract: The invention relates to a method for braking an alternating-current motor when the alternating-current motor (1) is supplied by a frequency converter (4) comprising an intermediate circuit (2). In accordance with the invention, when the voltage (uc) of the intermediate circuit (4) reaches a predetermined value during braking, the magnetization of the motor (1) is increased to increase the thermal losses of the motor, and, once the voltage (uc) of the intermediate circuit drops below said predetermined value, the increased magnetization is removed.

Abstract: The present invention relates to a power source regenerative apparatus which prevents distortion of a voltage regenerating in the power source from being caused. An inverter transforms induction electromotive force caused in regenerating the power source, namely in decelerating the motor, into a direct current. A timing adjusting device outputs a regenerative signal ST at a predetermined timing before the potential of one phase indicative of the maximum potential in three-phase supply voltages becomes the same potential as that of another phase. Based on the regenerative signal ST, a converter converts the transformed direct current into an alternating current, and regenerates it to the power source.

Abstract: A braking circuit for an electric motor includes a braking device for being connected in a circuit for braking the electric motor, a braking switch including first and second changeover switches for switching between a motor mode and a braking mode, and a control device. Switching contacts of the first and second changeover switches are switched between a first position for contacting, respectively, first stationary contacts of the first and second changeover switches in the motor mode, and a second position for contacting, respectively, second stationary contacts of the first and second changeover switches in the braking mode.

Abstract: A recording medium library system retaining up to a predetermined number of cartridge type recording media for recording/reproducing data on the recording medium is disclosed. The recording media are stored in a plurality of cells provided in a cell drum. The cell drum is rotatably driven such that a desired cell is brought to a target position. In the driving, an accelerating current, a braking current, and a positioning current are supplied to the motor in order of mention. At least the braking current is determined according to an input value of the inertia of the cell drum.

Abstract: A motor drive includes an invertor (5) with which a motor (6) is rotated at a variable speed. To suppress noises caused by ripple components contained in currents flowing in phase coils of the motor, the invertor (5) is controlled so as to direct a commuting current flowing from the phase coils to a d.c. power source (1) and at a time when the motor is decelerating to circulate in a path including the phase coils and the switching transistors of the invertor (5). This control is performed when the commuting currents fall below a predetermined level.

Abstract: An apparatus for braking a rotary component of a fiber processing machine includes an asynchronous motor having a stator winding and an output shaft connected to the rotary component; a direct current generating device having an output connectable to the stator winding for applying an electric braking torque to the motor; and a switching arrangement for selectively connecting the stator winding to an alternating current source for normally driving the motor or to the output of the direct current generating device for electrically braking the motor.

Abstract: In an AC inverter drive connected to an AC induction motor on a material handling machine, the motor (which has a load holding brake and a pulse-emitting shaft encoder) moves a load in hoisting or lowering directions. A method for checking brake load-holding torque including the steps of decelerating the motor toward zero speed, setting the brake, applying "float" load-holding electrical power to the motor, changing the current flowing to the motor and checking for motor rotation by pulse-counting. Motor power is blocked if the number of counted pulses is less than a predetermined number or is increased if the number of counted pulses is greater than a predetermined number, the latter indicating that the brake is incapable of holding the load.

Abstract: The operation of this invention is such that a rotational quantity of a motor is determined in accordance with a rotation indicating command of a motor, rotation actuating control of the motor is changed according to the determined rotational quantity of the motor, and a magnetization maintaining time of a magnetization phase of the motor is varied based on the rotation actuating control of the motor.

Abstract: In a circuit arrangement for influencing the start-up and/or braking behavior of three-phase a.c. non-synchronous motors having phase windings (5, 6, 7), which are connected in star for continuous operation and have terminals for the phase conductors (1, 2, 3) and for a neutral conductor (4) the phase terminal of one phase winding (6, 7) is connected by a change-over switch (9, 11) to the neutral conductor (4) for start-up and/or braking. A corresponding circuit arrangement is disclosed also for three-phase a.c. non-synchronous machines in which the phase windings (5, 6, 7) have terminals for the phase conductors (1, 2, 3) and for a neutral conductor (4).

Abstract: A circuit for operating a polyphase dc motor includes first circuitry for determining when the back emf of the floating driving coils crosses zero. A first counter counts a time period between a first set of zero crossings, and a second counter is loaded with the count reached by the first counter. The second counter counts a time period between a subsequently occurring set of zero crossings. If the second counter reaches zero before the occurrence of a third zero crossing, a warning signal is generated. A method for determining if a deceleration rate of a polyphase dc motor exceeds a predetermined threshold includes measuring a first period between a first set of zero crossings of the back emf of the floating driving coils, and comparing the measurement of the first period with a subsequent period between a subsequent set of zero crossings. If the subsequent period is larger than the first period by a predetermined amount a warning signal is produced.

Abstract: The current an inverter is used as a power source for a brake circuit. The brake circuit includes a current detector, a comparator for comparing the detected value with a dictated brake current pattern, and a switch which switches the brake current in accordance with the magnitude of the difference between the detected current value and the dictated value. The brake current is selected to smoothly increase and decrease the brake current to prevent vibration and noise.

Abstract: To control the speed of an alternating-current drive capacitor motor of a centrifuge, the motor is connected to the bridge arm of a single-phase inverter. The bridge arm is connected at each of its ends to the midpoints of a series circuit of two capacitors and two field-effect transistors, these series circuits being connected in parallel with one another and connected to the output of a rectifier operated by the a.c. voltage supply. During operation, the capacitors are discharged by means of triggering the field-effect transistors alternately via the capacitor motor, the triggering being performed via a microprocessor serving as a pulse generator.

Abstract: A three-phase motor controller includes a bidirectional thyristor switch to couple each phase of an electrical supply to a motor. The motor is started by rendering the thyristors conductive during successively greater portions of each cycle of AC electricity from the supply. In order to reduce the cooling requirements of the controller, a contactor is connected in parallel with the thyristors to provide apply electricity to the motor once it reaches full speed. When the controller receives a signal to stop the motor, the contactor is deactivated and the controller goes through a sequence to synchronize the thyristor triggering to the AC electricity. The synchronizing process provides a smooth transition from contractor control back to thyristor control of the application of electricity to the motor. Once thyristor control resumes, the controller executes a triggering routine which decreases the voltage applied to the motor and produces a braking effect.

Abstract: The speed of an induction motor is reduced by initially using dynamic electrical braking to slow the motor to a speed at which it will not remain synchronized to the A.C. supply frequency. At this point, A.C. cycle skipping is employed to apply current to the motor at an effective frequency which is a fundamental frequency component of the A.C. supply line frequency. The motor becomes synchronized at this fundamental frequency component. If desired, the motor can be brought to a complete stop by discontinuing the cycle skipping and using the dynamic braking again for a given period of time. This technique provides a very controlled stopping of the motor enabling equipment driven by the motor to be accurately positioned.

Abstract: The drive arrangement suitable especially for a hoist mechanism comprises a pole-changing two-speed three-phase motor which is united into one construction unit with a friction brake which can be released by an electromagnet. The two three-phase field windings dimensioned for different pole numbers are connected in star circuit arrangement and have star points conducted out at the motor terminal box of the three-phase motor. The electromagnet of the friction brake is connected through a rectifier circuit arrangement to the star points and when the three-phase motor is switched on is energized by the differential voltage then occurring between the two star points for the release of the friction brake.

Abstract: A DC braking system for an inverter-driven induction motor, (e.g., three-phase). When a braking command occurs, the normal gating sequence of the inverter stops. Mode 1 of the braking procedure starts. In Mode 1, two semiconductor phase switches of the group connected with one of the DC buses and the semiconductor switch of the third phase that is connected with the other DC bus are latched in a conducting state. The motor essentially receives DC current, which increases until it actuates a current limit device, clearing the latch. Then all six switches are turned off. That drives the motor current through the back-biased parallel diodes. The negative DC bus voltage is available to suppress motor current despite large motor speed voltages. The apparatus repeats the Mode 1 procedure for a predetermined time interval, after which Mode 2 of the braking procedure starts. In Mode 2, just as in Mode 1, two switches of one bus and one switch of another bus conduct until an overcurrent limit is reached.

Abstract: The electromagnetic braking arrangement comprises an exciting winding which is supplied from a generator winding which on the one hand excites the generator winding and on the other hand induces a braking torque in a short-circuited winding moved with the generator winding. The excitation current of the exciting winding is controlled by a transistor of a current-regulating circuit which holds the excitation current and thus the braking torque at a level adjustable at a reference voltage source. The iron circuit of the exciting winding has residual magnetic properties which ensure an initial self-excitation. The components of the control circuit are supplied with operating voltage from the generator winding via a rectifier circuit. A resistor, which is directly connected to the rectifier circuit, controls the transistor in the conductive state even when the operating voltage is insufficient for proper operation of the control circuit.

Abstract: An electric motor is braked by applying pulses of current to a winding of the motor creating a negative torque which slows the motor. In order to detect when the motor has stopped and as a consequence, when to discontinue applying the current pulses, a periodic determination is performed as to whether the back emf voltage induced in a winding of the motor is within a range of defined values, such as between a positive reference voltage level and a negative reference voltage level. The application of pulses of current is terminated a given interval from when a predetermined number of consecutive determinations all indicate that the back emf voltage is within the range. The length of the given interval is derived from the amount of time between when the electricity began to be applied to brake the motor and the occurrence of the predetermined number of consecutive determinations.

Abstract: An electric motor is braked by sensing the polarity of voltage of the alternating electricity for powering the motor and sensing the polarity of the voltage induced in the motor by the back electromotive force. When these polarities are opposite the electricity is applied to the motor to generate a braking torque. The application of the electricity is stopped a given interval after it begins to be applied during consecutive voltage cycles. This interval is derived from the time period between when braking commenced to when the electricity was applied during consecutive cycle.

Abstract: A D.C. solenoid control circuit for use in mechanisms driven by an A.C. motor. A rectifier converts A.C. current to D.C. current and provides an A.C. current flow path and a D.C. current flow path. Only the motor is connected in the A.C. current flow path to an output electrical power source. The D.C. solenoid is connected through the rectifier in the D.C. current flow path. The D.C. solenoid winding drives an actuator within the solenoid the activate the separate mechanism. In-rush current drawn by the motor upon start-up is converted to a high current level by the rectifier and input to the winding of the solenoid causing its immediate energization and, upon de-activation, its fast release.

Abstract: An electric motor is coupled to the power lines by thyristors. The motor is braked by triggering the thyristors at the proper times to produce a electro-magnetic field within the motor which opposes the residual magnetic field of the rotor. The proper time to trigger the thyristors is determined by comparing the polarity of the voltage across the power lines to the back emf voltage from the motor. The thyristors are triggered when these two voltages have opposite polarities. The braking circuit also regulates the duty cycle of the thyristors to control the magnitude of the current applied to brake the motor.

Abstract: In a converter for a switched reluctance motor, a dump capacitor receives freewheeling current from each phase and resupplies the charge to the dc supply. In this manner, residual magnetic energy is recovered and phase current quickly reduced while the converter requires only one main switching device and one freewheeling device per phase and the converter allows a unipolar source to be used.

Abstract: An inverter control circuit adapted, in the process to slow down and stop an induction motor, such that supply of the clock for combining voltage patterns is cut off by a control signal from its central processing unit and simultaneously voltage patterns dedicated for stopping which are stored in its storage device in addition to fundamental voltage patterns may be selected, whereby a stationary magnetic field is formed for the induction motor and optimum braking action corresponding to the condition of the load is provided.

Abstract: An AC elevator control system has a converter for converting a three-phase AC power to a direct current, an inverter for inverting the direct current to a three-phase AC power with a variable voltage at a variable frequency, and a three-phase induction motor for receiving the last-mentioned AC power to operate an elevator car connected to a counterweight through a traction rope trained over a sheave. A battery connected across the DC side of the inverter is enabled upon the occurrence of a power failure or a fault. A command emergency frequency generator responds to the occurrence of an emergency such as a power failure to deliver to the inverter a low frequency emergency frequency as determined by the relationship between a difference in weight between the elevator car and the counterweight and various losses of a motor driving system so as to cause the induction motor not to generate regenerative power.

Abstract: A thyristor (TR) is used to switch over between traction and braking states. Rather than supply a special extinction circuit for the switch-over thyristor, it is connected to make use of the extinction circuit already provided in the chopper circuit (H).

Abstract: An apparatus for processing the energy regenerated by an AC motor, which comprises a regeneration detection logic circuit (7) that produces a regeneration detection signal when the AC motor driving semiconductor switches are nonconductive and when the direction of the current flowing through the AC motor is opposite to that of the current when the AC motor is driven and a regeneration drive circuit 8 which drives the regenerated energy processing semiconductor switches responsive to the regeneration detection signal. The apparatus renders the regenerated energy processing semiconductor switches conductive so that the regenerated energy is returned to the AC power source only when the AC motor is in a regenerative condition. Therefore, electric power need be consumed in only small amounts by the resistors that protect the semiconductor switches for processing the regenerated energy, and the apparatus can be constructed so that it is small in size.

Abstract: In a method and apparatus for regulating the rotational speed of a motor having a rotor with magnetic poles and a stator with at least two coils, wherein during a first operational mode the sinusoidal voltage included in a first of the coils is digitized to produce first and second streams of rectangular pulses, the first pulse stream being compared with a reference frequency pulse signal as regards width and phase to generate accelerating or braking driving pulses supplied to the second coil, the second pulse stream being monitored to determine the rotational speed of the rotor and a second operational mode being instituted whenever the rotor speed falls below a predetermined value, in said second operational mode the rotor speed being accelerated through the application of driving pulses alternately to the first and second coils, the improvement wherein, following the switchover from the self starting mode to the nominial running mode of operation, during a transitional period for a specified time interval,

Abstract: Described is a control device for an a.c. elevator wherein the a.c. voltage from the commercial a.c. source is rectified by a rectifier device, the thus rectified voltage is converted by an inverter into an a.c. power of variable frequency and variable phase order, and an a.c. motor is driven by this a.c. power for driving the elevator car, characterized in that electrical contacts are inserted between said a.c. source and said rectifier so as to be closed and opened at the time of start and stop of the elevator car, respectively.

Abstract: An induction type positioning system which accurately stops a movable part without a contact and holds it in the stopped position without depending on the friction force of mechanical contact is disclosed. A primary core consisting of a main pole, an auxiliary pole, and a single phase AC magnetic field generation coil, and a conductive plate which moves relative to this primary core, generate a holding force for suppressing the relative movement between the primary core and the conductive plate by use of the eddy current which is induced on the conductive plate by the field generated by the main pole at the position where the conductive plate is placed on the auxiliary pole and simultaneously the edge of the conductive plate is placed on the main pole, and by use of the eddy current which is induced on the conductive plate by the field generated from the auxiliary pole.

Abstract: A scheme for determining the stator resistance of an alternating current motor includes the determination of the actual flux of the motor through the sensing of motor voltage and motor current. The motor current is also utilized to develop a signal representing the anticipated motor flux which will result from that current. These two flux signals are combined to develop a flux error signal, the polarity of which is determined by whether the motor is in the motoring or regenerative mode of operation, which in turn is integrated to give the signal representing the motor stator resistance. Additionally, when the motor changes mode of operation, there is provided a step function which assures a motor stator resistance value being used which insures control stability.

Abstract: A missing pulse detector circuit is disclosed which includes a variable frequency VCO and a digital phase comparator. The phase comparator compares the phase of the VCO reference and the phase of a driving signal that drives a synchronous motor drive package. The output of the phase comparator is input to a loop filter to provide an error signal that controls the VCO frequency and phase. A second output on the phase comparator translates a phase difference into a pulse width. The pulse width is then input to an integrator circuit to delay the leading edge thereof. This delayed pulse is then input to a Schmidt trigger which provides a switching threshold. The output of the Schmidt trigger is utilized to inhibit the operation of a synchronous motor in the motor drive package. The missing pulse detector is operable to detect rapid increases in acceleration of the driving frequency and added or deleted pulses therein.

Abstract: A control circuit for driving an induction motor wherein an AC voltage is converted into a direct current by a rectifying circuit and the direct current is converted into a signal having a variable voltage and frequency by a transistor inverter connected in parallel with a smoothing capacitor, and a regenerative circuit is connected in parallel with the inverter, and a circuit is provided for comparing the terminal voltage V.sub.C of the smoothing capacitor and a reference voltage V.sub.r when braking is to take place is disclosed. When condition V.sub.C .gtoreq.V.sub.r exists, the transistor inverter is disabled but the regenerative circuit is allowed to operate; when the condition V.sub.C <V.sub.r exists, the transistor inverter is operated in the regenerative braking mode.

Abstract: A regenerative braking system for a linear induction motor includes a control device to increase the frequency slip in a braking mode and reduce the regenerative capacity of the motor. The control device is regulated by sensing means which monitor the voltage of the external power conductor and increase the slip if the voltage exceeds a predetermined value. This reduces the power regenerated by the motor and prevents excessive voltages in the conductor. A latch prevents cycling between the full and reduced regenerative braking to prevent oscillation of the braking force and is reset upon selection of a motoring condition for the motor.

Abstract: An electronic system for controlling the speed of a shaded-pole single-phase induction motor provides increased power during speed increase and automatic braking during slowdown by regulation of half-wave D.C. braking current applied to the motor.Speed control during normal operation, and braking control during slowdown and stopping, are implemented by means of dual feedback loops interactively connected to the gate electrode of a triac in the A.C. current line of the motor. The speed control loop utilizes a frequency/phase detector to adjust the time delay of triac gating relative to the zero crossing points of each half-cycle of A.C. voltage until the tachometer-sensed speed of the motor corresponds to a desired speed set by a voltage controlled oscillator. The braking control loop adjusts the time delay of the triac gating relative to the zero crossing points of every alternate half-cycle of A.C. power thus decelerating the motor by an impressed half-wave pulsed D.C. current.

Abstract: A three-phase electric motor is partially braked as a result of self-excitation when the power supply is disconnected and a capacitor is connected across one of the windings. The motor is then rapidly brought to a standstill by applying a short-circuit (or connecting a relatively low impedance) across one or both of the other windings, and essential condition being that the short-circuit is initiated within a predetermined range of values of phase angle in a waveform of the self-excitation. Preferred ranges of phase angle are established for selected configurations of mechanical and electronic short-circuiting switches.

Abstract: A regenerative braking system for a linear induction motor includes a control device to increase the frequency slip in a braking mode and reduce the regenerative capacity of the motor. The control device is regulated by sensing means which monitor the voltage of the external power conductor and increase the slip if the voltage exceeds a predetermined value. This reduces the power regenerated by the motor and prevents excessive voltages in the conductor. A latch prevents cycling between the full and reduced regenerative braking to prevent oscillation of the braking force and is reset upon selection of a motoring condition for the motor.