Abstract: A device and control method to produce braking torque counter to motor rotation. A converter supplies multiple frequency AC power to the motor. A first frequency is supplied at the normal operating frequency/speed. A second frequency, different from the normal operating frequency, is supplied to produce braking torque. The level of braking can be controlled to generally consume some or all of the braking in the device or motor. More than one braking frequency may be utilized. In addition, the relationship between the normal and braking frequency(s) can be maintained to limit motor pulsation.

Abstract: A transformer outputs different (high or low) secondary voltages. A switch outputs high or low secondary voltage according to a mode signal. An electric power converter including a rectifying circuit and a switching circuit either charges a smoothing capacitor with an output of the switch or discharges the smoothing capacitor to supply a regenerative current toward the transformer with a power fact improved. An phase signal generation circuit generates PWM or PAM phase signals in accordance with the mode signal. An inverter circuit generates driving signals supplied to the motor in response to the phase signals from power from the smoothing capacitor. A mode determining circuit determines one of modes to generate the mode signal in accordance with a speed command signal and acceleration/deceleration which is indicated by the rotating speed signal and the rotating speed command signal.

Abstract: A brake mechanism includes a reduction gear train, a motor structure, and a braking means. The reduction gear train transmits at least a rotation force in a first rotational direction supplied from a drive source. The reduction gear train is imparted with a returning tendency in a second rotational direction opposite to the first rotational direction. The motor structure has an output shaft rotatably connected to the reduction gear train. The braking means has field magnets, an armature coil, a braking circuit, and either one of a fixed resistor, a variable resistor, a rectifying diode, a Zener diode, a varister, a constant-current diode, a light-emitting diode, and a lamp bulb.

Abstract: A circuit and method for braking a disk drive when a power fault occurs has a circuit (10) for producing an output signal (28) indicating that the motor of the disk drive has slowed at least to a predetermined rotational speed after the occurrence of the power fault. The components of the circuit (10) may be integrated onto the same integrated circuit as the motor driving circuitry or head retract circuitry. During the time between the occurrence of the power fault and the time the disk drive has slowed to the predetermined rotational speed, the read/write head mechanism (17) is retracted. A braking circuit then brakes the disk drive when the output signal (28) indicates that the motor has slowed, at least to the predetermined rotational speed. The circuit for producing an output signal indicating that the motor has slowed at least to the predetermined rotational speed is actuated by the back-emf (14) generated by the motor failing below a predetermined level.

Abstract: In controller for diesel electric locomotive, after output from an alternating current generator driven by a diesel engine is rectified into direct current power, the direct current power is inverted into alternating current power by an inverter to thereby carry out a power run control of an induction motor, and energy generated by the induction motor is consumed at a brake resistor by moving a brake chopper when the brake is applied. When a revolving speed of said induction motor exceeds a predetermined value at the time of power run, an slip control unit detects slip of wheels and outputs an output reduction signal for the induction motor in correspondence to a level of slip. An output torque of the induction motor is reduced with the output reduction signal. Further, a reduced amount of the output torque of the induction motor is consumed at a brake resistor through a conduction ratio control of the brake chopper.

Abstract: A motor driver has a braking control circuit. The braking control circuit shuts off the supply of an electric current to the coils included in the motor when a motor control signal shifts to a predetermined level and, after a predetermined length of time secured in accordance with an index signal, starts application of braking to the rotation of the motor by the use of a braking circuit. The index signal is obtained from the signal that indicates the rotational position of the motor. The motor control signal is fed from a control signal generating circuit to the braking control circuit.

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 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 braking circuit for braking an electric motor having an armature and run and brake windings, which includes a switching circuit disposed between a source of electrical power and the run winding, this circuit being operable to disconnect the run winding from the source of electrical power. The braking circuit further includes a switching mechanism operable to connect the brake winding in order to brake the electric motor. The switching mechanism preferably connects the brake winding after a predetermined period of time has elapsed from the disconnection of the run winding. This braking circuit can be used in a saw for braking the saw's blade.

Abstract: A control apparatus by which a duty ratio in consideration of how energy stored in storage cells is consumed is set to ensure a steady traveling feeling, a regeneration brake which can produce stable braking forces regardless of how storage cells are consumed, and a protective device by which a plurality of operation stop levels are set to be able to cancel the stop operation effected for the first time and to ensure reliable alarming, are provided. In the first and second embodiments, a chopper duty ratio is compensated depending on how storage cells are consumed, to provide a steady agreeable traveling feeling. In the third embodiment, regenerated electric power is consumed by a motor driving circuit to stabilize operation of a regeneration brake regardless of how storage cells are consumed, and improve performance thereof.

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 process and a device for monitoring and/or controlling the speed of rotation of an electric drive having an asynchronous motor equipped with a braking device (11) and connected via a frequency adapter (13) to an alternating current system (12), e.g. three-phase system, to provide safe lifting and lowering of a load. The maximum torque (16) produced by the drive for lifting the load is set to be smaller than a holding torque (17) needed by the braking device (11) to hold the load in a stationary position.

Abstract: A circuit for controlling a motor having an armature and a series-wound, series-connected field coil that can be separately controlled during regenerative braking. The circuit includes a main switching circuit, an armature circuit, and a field circuit. The main switching circuit includes a first switch and a first diode parallel-connected to the first switch. The armature circuit includes a second switch parallel-connected to the armature and series-connected to the main switching circuit, and includes a second diode parallel-connected to the second switch. The field circuit includes a third diode parallel-connected to the field coil and series-connected to the armature circuit.

Abstract: A power control apparatus for controlling power supplied to an electric motor rotating a rotor employed in a centrifuge is provided. The power control apparatus includes first and second inverters and a smoothing capacitor disposed between the first and second inverters. In a motor power mode, the first inverter charges the smoothing capacitor with power supplied by an AC power supply, while the second inverter charges, in a motor braking mode, the smoothing capacitor with power regenerated by the motor during a braking operation for returning the regenerated power back to the AC power supply through the first inverter. An reactor is arranged between the AC power supply and the first inverter for reducing harmonic components contained in the current supplied from or back to the AC power supply.

Abstract: A series motor for an appliance or tool, such as a circular saw, includes a regenerative braking circuit having brake windings in addition to the run windings. One of the brushholder assemblies includes a push-away feature for separating one of the brushes from the commutator prior to the time the brush could wear to an extent that direct current reversal might not be available to achieve the desired braking action.

Abstract: A device for controlling an electric vehicle motor that optimally discharges a smoothing capacitor, connected to the input terminals of an inverter in accordance with the condition of an electric vehicle. The device includes a motor drive means, the smoothing capacitor connected in parallel with the motor drive means, switching means operating in connection with an operation switch operated by the vehicle operator, discharging means for discharging the smoothing capacitor, draw detecting means, and discharge restricting means. The system opens the switching means to shut off output from the battery and to discharge the smoothing capacitor when the switching means is open, but restricts discharging during a towing or drawing condition of the electric vehicle.

Abstract: A power control apparatus for controlling power supplied to an electric motor rotating a rotor employed in a centrifuge is provided. The power control apparatus includes first and second inverters and a smoothing capacitor disposed between the first and second inverters. In a motor power mode, the first inverter charges the smoothing capacitor with power supplied by an AC power supply, while the second inverter charges, in a motor braking mode, the smoothing capacitor with power regenerated by the motor during a braking operation for returning the regenerated power back to the AC power supply through the first inverter. An reactor is arranged between the AC power supply and the first inverter for reducing harmonic components contained in the current supplied from or back to the AC power supply.

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: A method for dynamically braking a motor, the motor having a plurality of terminals and receiving an input alternating current voltage waveform, by detecting the zero crossing of the input alternating current voltage waveform and for a plurality of position of the input alternating current waveform: sampling a voltage waveform appearing at a terminal of the motor to develop a sampled value for the position, comparing the sampled value for the position to a reference value for the position and setting a flag if the reference value for the position matches the sampled value for the position, introducing a delay period and generating a gating pulse to fire a silicon controlled rectifier to provide a pulse of braking current to the alternating current motor and then halting the braking of the motor if the flags for each of the plurality of positions are set. Also an electronic dynamic brake assembly operable in a SLAVE mode, a PRE-STOP mode, a HOLDING mode and a MASTER mode.

Abstract: An apparatus comprising, in combination, an AC motor, a solid state switch controlling the AC motor, the solid state switch switchable between an on state in which an electric current flows through the solid state switch and an off state in which electric current does not flow through the solid state switch, the solid state switch characterized by a turn off time such that, when the solid state switch is switched between the on state and the off state, at least a portion of the electric current flows through the solid state switch during the turn off time, a first switch circuit for switching off the solid state switch to prevent the electric current from flowing to the AC motor, a diode bridge coupled across the AC motor, a second switch circuit for controllably switching the diode bridge between an active state in which electric current may flow through the diode bridge and an inactive state in which electric current may not flow through the diode bridge, a control circuit for controlling the second switch

Abstract: A universal electric motor having an arbor mounted on a rotating armature with a run winding for generating a magnetic field having a polarity relative to the armature and for rotating the arbor, a first switch for connecting the run winding to a power source, and a brake winding for generating a counter magnetic field opposed with respect to the armature winding to that generated by the run winding.

Abstract: In this invention, a provision is made for a means for detecting the voltage or current of a dynamic brake regenerative (DBR) circuit for determining whether the DBR circuit is properly functioning in an elevator system in which a DBR circuit for controlling the regenerative electrical power is connected between the input terminals of an inverter working as an electrical power source for an alternating current electric motor for driving an elevator car, so that the operation of the DBR circuit is automatically checked immediately before operating an elevator, preventing the occurrence of an abnormal situation caused by unabsorbed regenerative electrical power.

Abstract: An AC electric motor can be braked by applying current pulses to the motor when the polarity of the supply voltage is opposed to the polarity of the back electromotive force (emf) voltage across a stator coil of the motor. This current application continues until the motor has stopped. The stoppage is detected by sensing when the current is being applied during every cycle of the supply voltage. Thereafter, the polarity pattern of back emf voltage induced across each of the motor stator coils is sensed. The occurrence of a back emf voltage polarity pattern that remains unchanged for a given number of cycles is detected. Thereafter, a change in this pattern is sensed and the braking current application either ceases or continues for an additional predetermined interval.

Abstract: A control apparatus for a motor including m number of stator windings and a relay having m-1 contacts, thereby allowing the control apparatus to be simplified in its structure so that the control apparatus can be constructed at a low cost.

Abstract: The present invention relates to a motor control apparatus having a discharge circuit 7 for reducing a voltage which is regenerated from motor 5 to the driving circuit 4 in the braking of an AC servomotor or the like, a protection circuit 8 for protecting the discharge circuit 7, and a voltage-drop detection circuit 20 for making the driving circuit stop after an activation of the protection circuit 8. The motor control apparatus contains a detection circuit 16, which detects a voltage of the smoothing capacitor 3 which is connected to the input terminal of the driving circuit 4 via the protection circuit 8 which is connected in series to the discharge circuit 7, and a voltage-drop detection circuit 20 which stops the driving circuit 4 after activation of the protection circuit 8.

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 power supply regenerating circuit according to the present invention is used in an inductor motor drive circuit which performs motor drive control and regenerative control. The induction motor drive circuit has a parallel circuit including a reverse connected diode (D10) and a resistor (R1) connected between a circuit (C2), which rectifies and then smoothes the induced electromotive force of an induction motor (M) during deceleration, and a bridge circuit (Tr1-Tr6) which effects a conversion into AC power. Regenerative power blocked by the diode (D10) is supplied to the bridge circuit (Tr1-Tr6) as a current limited by the resistor (R1), and the regenerative power is regenerated only during a predetermined interval of a three-phase period.

Abstract: For connecting the d-c terminals of a voltage-source inverter to a direct current (d-c) power source, a d-c link capacitor is connected directly between the d-c terminals, a line capacitor is connected in parallel with the d-c link capacitor, and a series inductor is connected between the line capacitor and the source. A dynamic brake resistor and an electric power chopper are connected in series with one another across the line capacitor. Between the two capacitors, no inductance is provided but a resistor is inserted in the braking current path during electrical braking operation of the inverter.

Abstract: An induction motor control method includes producing a primary current as a current command which takes all constants of an induction motor (d) into consideration. An output torque is obtained which is linear with respect to a torque command (Tm), a voltage at a DC link portion is detected, and an excitation flux command is varied by this DC voltage (V). This enables constant-output control to be performed irrespective of fluctuations in power supply voltage. Further, a power-factor adjusting circuit (q) is provided for adjusting the phase between voltage on the AC power supply side and current at the time of regenerative braking, so that reactive power is reduced.

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: An AC induction motor is energized by a voltage fed inverter coupled with a DC power source and is controlled in response to a torque request signal that is provided to accelerate or decelerate the motor as desired to maintain a desired torque output. The motor is operated to have each of a power and brake operation below the base speed of the motor and to have each of a power and brake operation above the base speed of the motor.

Abstract: A control device for supplying current to electrical appliances and particularly appliances having single phase capacitor start motors wherein the control device includes a changeover switch which is mounted between a source of power and the appliance motor and which changeover switch includes selectively operated components for controlling the power supply to the appliance motor or to terminate the power supply thereto. In one embodiment of the invention, a second circuit is provided intermediate the power source and the appliance motor for detecting the amount of current flowing in the circuits so as to insure connection of the starting capacitor of the motor, braking of the single phase motor when power is terminated and to provide an indication of overcurrent in the motor.

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: An apparatus for controlling an A-C powered induction motor for an elevator cage, said apparatus comprising a rectifier for converting 3-phase A-C power into D-C electric power, an inverter connected to the rectifier for converting the D-C power into A-C power of variable voltage and variable frequency, a current detector connected to detect input current of the inverter, a power detector for detecting power supplied to the inverter based upon an output of the current detector, a control unit for generating a command signal to control the inverter in accordance with slip of the induction motor as determined by the power supplied to the inverter, and a correcting unit operable responsive to the power detected by the power detector for correcting the slip of the motor to maintain the power supplied to the inverter at predetermined values.

Abstract: In an elevator driven by an induction motor and having a slip control device for generating a slip frequency command signal on the basis of an error between a speed command value and a running speed value of the induction motor so as to control a VVVF type inverter which in turn provides a corresponding alternating current of variable voltage and frequency, the inverter having a smoothing capacitor on a D-C side thereof, a control apparatus for stabilizing torque of the induction motor by smoothly changing operation of the induction motor from a powering mode to a regenerative mode, the control apparatus comprising a current detector for detecting charging current of the smoothing capacitor having a portion for detecting polarity of the slip frequency command signal and a unit responsive to the charging current detected by the current detector and the slip frequency command signal generated by the slip control device for changing operation of the induction motor from the powering mode to the regenerative mode

Abstract: A positioning-indexing device for an inverter apparatus provided with an indexing command control circuit for making positioning and indexing control of an inverter apparatus with an induction motor connected thereto as a load adapted, upon receipt of an indexing command after the rotation of the motor has been stopped at a specific position, to read a new command for stopping at any other specific position and to allow the spindle of the motor to stop at the aimed stop position with its rigidity maintained, within one rotation thereof, and without presenting such phenomena as damped oscillation about the aimed stop position.

Abstract: The voltage in a converter 20 is compared with a reference voltage to detect an input power failure, in response to which a motor driven by the converter is automatically decelerated in accordance with a stored signal pattern/speed reduction curve such that the energy regenerated by the motor is equal to its power consumption. The DC bus voltage of the converter is thus maintained substantially constant during the regenerative braking of the motor, and it is promptly halted without resort to any mechanical braking unit.

Abstract: In a case where a braking torque is required as in the slowdown mode of the cage of an elevator, regenerative power within a range within which the generation of heat by a motor is permissible is consumed in the motor, and excess regenerative power is consumed by a regeneration resistor, so that a control apparatus can be made smaller in size.A braking torque is controlled in such a way that when a braking torque command is not greater than a predetermined value, only the magnitude of current is controlled with a slip fixed, and that when the braking torque command has exceeded the predetermined value, the slip is decreased without increasing the magnitude of the current.Regenerative power is partly fed back to a D-C side. Since, however, the current is suppressed within a predetermined value, so that the current capacity of an inverter can be restrained and that the resistor for consuming the regenerative power on the D-C side does not increase considerably.

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 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 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: A variable-voltage variable-frequency elevator control apparatus is disclosed in which a circuit for the consumption of regenerated power produced during regenerative braking is provided on the DC side of the apparatus rather than on the AC side. During regenerative braking with an emergency generating unit in operation, regenerated power is consumed by the consumption circuit on the DC side of the circuit and is prevented from being returned to the emergency generating unit. This prevents the production of voltage notches commonly produced during regenerative braking by thyristor commutation in conventional circuits. Because no voltage notches are produced, a reduction in the size of the emergency generating unit can be achieved. In addition, since it consumes DC power rather than 3-phase AC power, the consumption circuit requires fewer elements than in conventional control apparatuses.

Abstract: An elevator speed control system permitting rotation of the motor with short-circuited rotor at full speed, wherein the thyristors controlling said motor permit the motor to rotate at full speed and when the elevator is running in the lighter direction, operation of the motor as generator at an over-synchronous speed. The system comprises a control unit assembled of components known in themselves in the art by which the instruction value is increased considerably past the actual value, whereby the motor with short-circuited rotor is left to rotate at full speed, and that on commencing retardation the instruction value is dropped directly to be consistent with the actual value.

Abstract: The invention relates to a circuit for controllably driving an A.C. motor which includes a voltage supply with a pulse modulation regulator followed by an intermediate smoothing circuit and an inverse rectifier. Each phase of the inverse rectifier has two controllable load switching elements in series between two supply lines with each element being bridged by a recovery diode. The voltage of the intermediate circuit is adjustable by a desired value generator and the frequency of the inverse rectifier is adapted to follow the existing value of the voltage of the intermediate circuit. At least one phase of the inverse rectifier is associated with a braking circuit having a brake resistor between one phase connection and a brake connection which is disposed between two series connected brake switching elements disposed between the supply lines.

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 polyphase induction motor propels an elevator car. The motor is powered by a multiphase inverter which receives power from a battery. The inverter is controlled in such a way as to control the frequency and amplitude of the power supplied to the motor in order to control the motor's speed, acceleration, and slip. That inverter control is accomplished by sensing the motor's speed and in response providing predetermined slip and torque signals. The slip can be controlled over a range which can provide negative slip, by which power is regenerated into the battery, which is thereby charged, and positive slip for motoring torque. A charger also charges the battery. The motor and its controls are thereby ostensibly isolated from the power system that supplies power to the charger, the battery handling the peak power requirements. Thus, little noise is injected into the power system. Speed loop gain is adjusted depending upon whether the motor is motoring or regenerating.

Abstract: A control circuit for a three phase induction motor includes a voltage controller having a silicon controlled rectifier in each of a first, second and third supply line connected to the motor. The control circuit further includes a first, second and third phase control means for controlling the firing angles of the respective silicon controlled rectifiers, a circuit for providing a positive ramp signal, and a circuit for providing a constant level signal. A starter circuit includes a "run" push button and a "brake" push button. The depressing of the "run" push button connects a three phase power supply to the supply lines of the voltage controller and causes the positive ramp signal to be applied to the first, second and third control means to control the firing angles of the silicon controlled rectifiers to provide a soft start for the motor.

Abstract: An AC elevator control system which includes an inverter for inverting a DC voltage to an AC power having a variable voltage and a variable frequency under the control of a command voltage signal and a command frequency signal, and an induction motor which is driven with the AC power to operate an elevator car. With the induction motor operated in the regenerative braking mode, a switching device responds to the actual speed of the car exceeding its command speed to decrease the command frequency signal to such a magnitude that the induction motor has a slip equal to a predetermined one through a first gain regulator connected between a command speed generator and a command frequency generator. Simultaneously a second gain regulator is enabled to equal the command voltage signal to a difference between the actual and command speed signal.