Abstract: When an absolute value of a rotation speed change rate of a motor is equal to or less than a threshold and an absolute value of a torque command change rate of the motor is equal to or less than a threshold, a switching angle is changed by cyclically changing a pulse type or the number of pulses as change in a pulse pattern. With this, respective order components of harmonics are dispersed, whereby it is possible to reduce the degree of prominence of a specific order component in harmonics relative to other order components.

Abstract: An elevator system includes a battery; a machine having a motor to impart motion to an elevator car; an inverter having a plurality of switches to convert DC power from the battery to AC power for the machine in a motoring mode; a speed sensor coupled to the machine, the speed sensor to generate a speed signal indicative of machine speed; and a controller to apply braking signals to a group of the switches in a braking mode, the braking signals having a duty cycle in response to the speed signal.

Abstract: A rotary electric machine control system includes a rotary electric machine (second motor generator), a number-of-revolutions sensor that measures the number of revolutions per predetermined time period of the rotary electric machine, and a controller. The controller has a threshold changing unit for changing a control switching phase that is a control switching threshold to be used for switching the control mode of the rotary electric machine, according to a measurement result of the number of revolutions.

Abstract: A method of braking a washing machine from an operational speed to a zero speed is provided (as well as a washing machine incorporating the method) for a washing machine driven by one of a synchronous or asynchronous motor. Upon receipt of a stop signal, collapsing the motor rotating magnetic fields are collapsed for a predefined time period. After the predefined time period, DC braking voltage is applied to the motor stator windings at a controlled ramp-up rate to a fixed amplitude to generate a controlled ramped braking torque on the motor. The braking torque is applied until the motor is stopped.

Abstract: In a washing machine, a power management apparatus and a method of controlling the same, washing operation and drying operation commands are input by a user, power rate information for each time period is received from an EMS, a drying operation execution time is confirmed, and power rates corresponding to the drying operation execution time are determined based on the power rate information for each time period. Then, the power rates corresponding to the drying operation execution time are compared with the standard power rates to determine whether the power rates corresponding to the drying operation execution time are higher than the standard power rates, and an algorithm of a final spinning mode in the washing operation is adjusted if the power rates corresponding to the drying operation execution time are higher than the standard power rates.

Abstract: An apparatus includes an inverter including a high-side switch coupled to a low-side switch, the inverter generating a time-varying drive current from a plurality of drive control signals, a positive rail voltage, and a negative rail voltage wherein controlling the switches to generate the time-varying drive current produces a potential transitory overshoot condition for one of the switches of the inverter; a drive control, coupled to the inverter, to generate the drive control signals and to set a level of each of the rail voltages responsive to a plurality of controller signals; and a controller monitoring one or more parameters indicative of the potential transitory voltage overshoot condition, the controller dynamically adjusting, responsive to the monitored parameters, the controller signals to reduce a risk of occurrence of the potential transitory voltage overshoot condition.

Abstract: In an abnormality diagnosing system for first and second current sensors for measuring a current, an obtaining unit obtains at least one pair of measured values of the first and second current sensors. The at least one pair of measured values is measured by the first and second current sensors at a substantially same timing. A diagnosing unit diagnoses whether there is an abnormality in at least one of the first and second current sensors based on a function defining a relationship between the at least one pair of measured values of the first and second current sensors.

Abstract: A method of braking a washing machine from an operational speed to a reduced non-zero speed is provided (as well as a washing machine incorporating the method) for a washing machine driven by one of a synchronous or asynchronous motor. Upon receipt of a speed reduction signal, the motor rotating magnetic fields are collapsed for a defined time period. After the defined time period, DC braking voltage is applied to the motor stator windings at a controlled ramp-up rate to an amplitude to generate a controlled ramped braking torque on the motor until the motor has slowed to a defined reduced speed. Thereafter, the amplitude of the DC braking voltage is set to 0V and the motor is soft started to an amplitude and reduced frequency needed to maintain the defined reduced speed.

Abstract: A method of braking a washing machine from an operational speed to a zero speed is provided (as well as a washing machine incorporating the method) for a washing machine driven by one of a synchronous or asynchronous motor. Upon receipt of a stop signal, collapsing the motor rotating magnetic fields are collapsed for a predefined time period. After the predefined time period, DC braking voltage is applied to the motor stator windings at a controlled ramp-up rate to a fixed amplitude to generate a controlled ramped braking torque on the motor. The braking torque is applied until the motor is stopped.

Abstract: A boost converter boosts a DC voltage of a DC power supply. An inverter converts the output voltage of the boost converter into an AC voltage. A control device that controls the boost converter reduces an output voltage instruction value of the boost converter when the rotation speed of the AC motor decreases and an absolute value of a variation rate of the rotation speed is not less than a predetermined value. The inverter is controlled in the control mode selected from a plurality of control modes including three modes of a sine wave PWM control mode, an overmodulation PWM control mode and a rectangular wave control mode. The control device of the boost converter reduces the output voltage instruction value of the boost converter only when the control mode of the inverter is the rectangular wave control mode or the overmodulation control mode.

Abstract: A generator is connectable to a turbine for generating electric power or a motor. An electric power generator system or a motor comprises an asynchronous short-circuited rotor generator or motor comprising a stator, a rotor, and a transformer having a first winding and a second winding, the first winding having a first end and a second end. The stator and the transformer are connectable in series with an electric power distribution grid.

Abstract: A boost converter boosts a DC voltage of a DC power supply. An inverter converts the output voltage of the boost converter into an AC voltage. An AC motor is driven by the output voltage of the inverter. A control device which controls the boost converter reduces an output voltage instruction value of the boost converter in the case where the rotation speed of the AC motor is decreased and an absolute value of a variation rate of the rotation speed is not less than a predetermined value. The inverter is controlled in the control mode selected from a plurality of control modes including three modes of a sine wave PWM control mode, an overmodulation PWM control mode and a rectangular wave control mode. The control device of the boost converter reduces the output voltage instruction value of the boost converter only in the case where the control mode of the inverter is the rectangular wave control mode or the overmodulation control mode.

Abstract: A method and apparatus for stopping an AC motor that is controlling a load while detecting mechanical brake slippage of a mechanical brake for holding the load against movement includes a controller for decreasing torque-producing current commands from the drive while a speed regulator is commanding zero speed, sensing movement of the load while the speed regulator is commanding zero speed, detecting movement of the load past a pre-determined distance limit, and increasing torque to support the load and prevent further movement of the load. The controller will again decrease torque-producing current commands from the drive, and again checking for movement of the load, and upon sensing no load movement upon reaching zero torque, then shutting off the motor.

Abstract: A controller includes a power source unit, a drive circuit, and a state control circuit. The drive circuit is coupled to the power source unit, and includes a drive coil and a switching transistor unit. The switching transistor unit is operable in one of a circuit-making state for making an electrical circuit between the drive coil and the power source unit so as to enable the drive coil to drive rotation of a rotor of a brushless direct current motor, and a circuit-breaking state for breaking the electrical circuit between the drive coil and the power source unit. The state control circuit is coupled to the power source unit, and includes a pulse width modulator, a sensing coil, and a control transistor coupled electrically in series. The state control circuit controls operation of the switching transistor unit according to magnetic position of the rotor relative to the sensing coil.

Abstract: A method and apparatus for braking an AC motor in the higher portion of its speed range includes substantially reducing flux before applying reverse torque commands to brake the motor. A DC link bus regulator is employed to prevent increases in bus voltage and frequency.

Abstract: A dynamic braking system for a motorized lifting mechanism such as a crane, hoist or the like allows the load to be lowered at a controlled rate during a power failure. An auxiliary power source is activated to apply an excitation current to the stator windings, creating a static magnetic field. When the brake is released the rotor rotates in the static magnetic field, generating an A.C. voltage that is rectified and applied to the stator, thereby increasing the strength of the static magnetic field. An equilibrium is reached, and the load is lowered at a controlled rate. In the preferred embodiment the A.C. voltage is supplied through an adjustable resistor, allowing the lowering rate to be selectively controlled.

Abstract: A method and apparatus for slowing back spin of a rod string of a progressing cavity pump powered by an electric motor when power is lost. Pulse direct current voltage into the windings of the electric motor powering the progressing cavity pump to magnetize a stator of the electric motor thereby reducing the rotational speed of a rotor of the electric motor and consequently the rotational speed of the back spinning rod string of the progressing cavity pump.

Abstract: A device for precisely stopping an induction motor includes a current transformer for sampling a power level of an alternating current power source driving the motor during run time and an AC-DC converter/sample-and-hold circuit for generating a sampling voltage signal according to the sampling. Also included is circuitry responsive to the sampling voltage signal for determining an amount of direct current necessary to induce a static magnetic field to produce a torque within a stator winding of the motor sufficient to precisely stop the motor. A silicon controlled rectifier generates the determined amount of direct current and control circuitry causes the generated current to be injected into the stator winding. The induced static magnetic field static magnetic field is sufficient to precisely stop the motor regardless of the size of the load the motor is driving because it follows the sampling voltage signal.

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: A closure lock which utilizes the operating motor for moving of the closure as the locking mechanism. A shorting circuit is applied across the motor when the closure is in an at-rest position. Any attempt at manually moving of the closure between the closed position of the closure and the open position of the closure will require the rotor of the motor to be rotated relative to the stator of the motor. This requires a significant amount of motor drag to be overcome which is difficult and thereby functions as a locking mechanism preventing operating of the closure. This closure lock can be bypassed by an authorized person by the opening of a manually operated switch which will permit the closure to be easily moved between its open and closed position.

Abstract: During the deceleration portion of a seek operation, the current level provided to the actuator motor of a disk drive is based on a desired linear deceleration versus time profile that has been temporally advanced by half of a servo data position sampling interval. At each position sampling interval, a new current level is determined and maintained for the interval between samples. The actual deceleration current follows a staircase curve centered on the desired profile so as to be self-synchronizing. The current level is also adjusted to compensate for the delay between obtaining a new servo data position sample and applying a new current level to the motor.

Abstract: A procedure and apparatus are provided for braking a squirrelcage elevator motor fed by a frequency convertor in fault situations using a direct current supplied from a d.c. voltage source. In the procedure of the invention, the current in at least one of the motor phases and the rotational speed of the motor are measured. When the elevator speed exceeds the value corresponding to the nominal slip and the motor current is less than the nominal magnetizing current, a switching device is caused to connect a direct current from a d.c. voltage source to the motor, thereby providing a magnetizing current and allowing the motor to act as an eddy current brake.

Abstract: A device for closing swinging doors of the type utilizing a rotating member to compress a spring during door opening to store energy in the spring to effect a closing of the door is provided with a driving connection to a d.c motor/generator effective to cause rotation of the motor during a closing movement of the door. The motor/generator acts as a generator during the closing with the generated electrical energy fed back to the motor/generator to retard rotation of the rotor, providing a brake on the closing movement of the door. The feedback circuitry includes a switch disabling or diminishing the braking during the final degrees of closing movement as well as a variable setting device allowing control of braking force.

Abstract: A device for controlling swinging doors utilizing an externally powered motor to compress a spring during door opening to store energy in the spring. The motor is not used to open the door, but only to compress the spring, thereby utilizing a minimum amount of electrical energy and allowing for a very easy opening of the door. The motor acts as a generator during the closing of the door with generated electrical energy fed back to the motor to retard rotation of the rotor, providing a brake on the closing movement of the door. The feedback circuitry includes a switch for varying the braking during the final degrees of closing movement as well as a variable setting device allowing control of braking force.

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: A method and device are disclosed for braking a squirrel-cage motor in which the motor is controlled in a manner known per se by means of a voltage converter and a control circuit which switches off the main current to the motor in a braking situation, whereupon a direct current is supplied to the motor windings. To achieve a simple and inexpensive braking control system, the direct current fed into the motor windings is obtained from a rectifier bridge formed in the braking situation via electrical control from certain semiconductor components of the voltage converter.

Abstract: The subject invention is an electric motor brake which uses a simplified circuit enabling a timed injection of DC voltage into the motor windings of an induction motor. This DC voltage acts as a dynamic braking force and will bring the rotor, and whatever is connected to it, to a stop in a rapid fashion. An additional advantage of the invention is that it may be constructed and used as a stand alone device which may be attached to any electrical induction motor to achieve the desired braking effect. A further feature of the invention is the provision of a timing circuit that it is designed to be user adjusted to achieve the maximum possible effect rather than using a fixed design which would result in a compromise in order to be suited for wide usage.

Abstract: A capacitive breaking circuit for a single phase induction motor using a double throw power switch which in the off position, connects a series string, consisting of a charging rectifier diode, a current limiting resistor, a centrifugal switch and a braking capacitor, to the two power input terminals of a small single phase induction motor. With this circuit, while the motor is running, when the power switch of the motor is turned ON, DC current also charges the braking capacitor. When the power switch of the motor is turned to OFF, the braking capacitor discharges through the motor winding via the power switch to produce the braking function.

Abstract: A dynamic brake control system for an alternating current motor powered by a variable voltage, variable frequency inverter which regulates the speed of the motor. An AC to DC converter converts AC line power to DC power with the DC power being transferred to the inverter via a DC link. During electrical dynamic braking, the inverter functions to transfer power from the motor to the DC link. The torque available to the motor during braking is a function of the receptivity of the DC link. Link receptivity controlled by a resistance connected to the link in which the resistance is modulated at a frequency dependent upon the incoming AC line frequency at the converter. The modulation is binarily controlled so as to minimize ripple current on the DC link without the necessity of providing high frequency control of the modulating electronics.

Abstract: The invention relates to a method of and a device for braking an asynchronous motor by applying a direct current to the field windings thereof. According to the invention, an AC voltage appearing at the outer terminals (4,6) of two mutually series-connected field windings (1,2) of the asynchronous motor acting as a generator is rectified and connected to a coil (19) of a braking current relay (28) immediately after the operating current of the motor has been switched out, whereby said braking current relay (28) picks up and a terminal (R) of a braking current source (R, N) is connected by contacts (20,21,22) of said braking current relay (28) through a semi-conductor (24) to an outer terminal (6) of said field windings (1,2) and through another semi-conductor (25) to another outer terminal (4) of said field windings (1,2), a terminal (5) common to said field windings (1,2) being connected through a braking current adjuster (26) to another terminal (N) of the braking current source (R, N).

Abstract: An electric motor run and brake control circuit for controlling alternating current to a three-phase motor in which the circuit is operated by a single logic level input signal. When the input signal is low, a run relay is closed and AC power is applied to the motor. When the input signal goes high, the run relay is opened and the motor is braked for a fast stop. A brake capacitor and charge resistor limit both the time during which braking current is applied and the repetition rate of braking cycles.

Abstract: An AC induction motor brake control apparatus and method are provided for energizing the motor with an inverter supplied first voltage and an additional brake circuit supplied second voltage in phase with and additive to the first voltage as required to determine a desired brake torque above base speed operation.

Abstract: A braking direct current (d.c.) (u.sub.g) is injected by way of a diode into at least one of the motor windings at a make time (T.sub.1) which occurs after the tripping of the motor. The make time lies between, at the earliest, a first reference time (T.sub.r1) and, at the latest, a second reference time (T.sub.r2), the braking d.c. voltage (u.sub.g) being substantially equal to a back-voltage (u.sub.r) of the motor winding at the first reference time. The second reference time leads, by 5% of the full periodicity of the network voltage, the first peak in time of the back voltage to occur after the first reference time. The polarity of the braking d.c. voltage (u.sub.g) at the make time (T.sub.1) is opposite to the polarity towards which the back-voltage (u.sub.r) is tending at the first reference time.The braking accuracy of d.c. braked asynchronous motors is improved without increased loading of the motor by relatively heavy currents.

Abstract: A control circuit for connecting and disconnecting an electronic motor brake with an AC motor and a source of AC power over electromechanical relay contacts wherein opto-coupled circuits operatively control energization and de-energization of a braking circuit with minimal time delay and provide operational response of the relay contacts in a substantially sparkless manner to promote contact life.

Abstract: An induction motor is coupled to a movable load to be positioned. The induction motor has two or more stator windings. Alternating current power is connected to the stator windings to energize the motor. A transducer senses the position of the load. Responsive to the transducer, the alternating current power is disconnected from the stator windings as the motor approaches a predetermined load position. Also responsive to the transducer, a direct current energy storage device is connected to the motor as the motor approaches more closely to the predetermined load position to apply direct current to the stator windings and to stop the motor at the predetermined load position. Preferably, the storage device comprises a capacitor connected in series with a rectifier across two input terminals of the motor and the storage device is connected to the motor by a relay coupled from the junction of the rectifier and capacitor to one of the input terminals of the motor.

Abstract: A strand-advancing system, particularly for a drawing frame, has an asynchronous electric motor powered from an alternating-current source and having a plurality of separate windings forming separate poles. This motor has a rotary output speed directly related to the advance speed of the filament. During normal operation the motor is driven at a relatively high nominal speed by connecting a relatively small group of its poles to the alternating-current source. The strand advance is stopped by first simultaneously disconnecting the relatively small group of poles from the alternating-current source and connecting a relatively large group of the poles to the source to operate the motor hypersynchronously generator-fashion for a relatively short time. Then the relatively large group is disconnected from the alternating-current source and the small group is energized with direct-current voltage until the motor and strand stop.

Abstract: A two-stage electrical braking system for a variable speed alternating current induction motor powered from a variable frequency, variable voltage power source utilizes capacitance connected across a primary winding of the motor in a first stage of braking and short-circuits the primary winding in a second braking stage. The system is arranged such that the control of the two braking stages is independent of the motor terminal voltage and braking can be initiated by either a braking command or automatically upon interruption of power to the system. The control system uses a fixed time delay to initiate the second stage of braking a predetermined time interval after the first stage is initiated.

Abstract: An SCR bridge of an elevator speed control apparatus is connected between an induction motor 5 and two (R, S) of the three-phase power supply terminals. Two diagonally opposite legs of the bridge comprise single SCR's 25, 26, and the other two legs each comprise a pair of parallel, reverse polarity SCR's 21, 22; 23, 24. The third power supply terminal is connected directly to the motor through a single switch contact 8. By appropriately controlling the switch contact and the SCR.varies.s in accordance with the difference between the actual and commanded elevator speeds, the bridge can be configured to implement three phase running during acceleration and constant speed modes, single phase running during a transitional slow down mode, and D.C. braking during a deceleration mode.

Abstract: A method for D.C. braking a three-phase asynchronous machine and a circuit arrangement useful in implementing the method. For braking, the first and third stator windings are separated from their phases and a pulsating direct current is caused to flow from the second phase to the first phase via a closed second switch and a diode. The third winding is short-circuited by a third switch which is connected in a loop with a current transformer; the loop carries a current induced by the turning rotor. A signal from the current transformer flows, via a limit indicator, to a digital logic member (OR). When the motor stops, short-circuit current flow is no longer detected, the second switch is opened and the circuit for producing direct current is automatically disconnected.

Abstract: The braking of an a.c. motor is accomplished by sequence controlled outputs of a shift register circuit which sequentially disconnects the main a.c. electrical excitation from the a.c. motor, connects a full wave rectifier circuit to the a.c. motor and then applies the a.c. electrical excitation to the full wave rectifier circuit resulting in a braking current being supplied to the a.c. motor.