Abstract: A reversible variable-speed two-phase motor is disclosed. The motor comprises two sets of stator coils of equal impedance displaced in space by 90 degrees and transistor inverters to provide exciting current to the stator coils. The current supplied to one of the sets of stator coils is 90 degrees out of phase with the current supplied to the other set of stator coils, and the direction of the current in each set of stator coils reverses every 180 degrees so that a smoothly rotating magnetic field is produced. The motor can be operated as an induction motor or as a synchronous motor or as a direct current brake.

Abstract: A speed control system for an a.c. electric motor (1) comprises a microcomputer (6) having an interrupt signal input (INT/TO) to which is coupled the outputs of a detector (10) for detecting zero-crossings of the a.c. supply voltage and a tachogenerator (11) driven by the motor. The microcomputer supplies firing pulses to a triac (2), connected in series with the motor, in response to an overflow of a clocked counter (CT). This counter is suitably preloaded at each zero-crossing. The counter is read each time a tachogenerator pulse occurs and the time which this reading indicates has elapsed since the immediately preceding zero-crossing is stored. A record is also kept in a register (ZCSLTA) of how many zero-crossings occur between each tachogenerator pulse and the next and from this, and the stored times relating to the relevant pulses, the period of the tachogenerator pulses and hence the actual speed of the motor is calculated.

Abstract: In a microcomputer-based multi-function thyristor-controlled AC induction motor drive, the microcomputer effectuates the several control functions of the motor drive during respective time intervals corresponding to the sequence of firing of the thyristors, and upon each new time interval, depending upon the required delay angle, firing is effected as a function of a residual angle in terms of a multiple of said time intervals, and the firing sequence is shifted by an amount of time intervals in relation to the integer number of such time intervals within such delay angle. As a result, firing of the thyristor is performed by the microcomputer without impeding control function determination and with improved response to change in the delay angle.

Abstract: A control system for controlling a PWM inverter so that the inverter drives an induction motor at a variable voltage and a variable frequency while keeping constant a ratio of the output voltage of the inverter to the output frequency thereof, is disclosed which includes current component detecting means for detecting an effective current corresponding to a load, from the input current of the induction motor, frequency setting means for setting the output frequency of the PWM inverter, flux setting means for setting the amount of magnetic flux generated in the induction motor, correcting-frequency calculating means for calculating a frequency correcting quantity proportional to the effective current, and correcting-flux calculating means for calculating a flux correcting quantity proportional to the effective current.

Abstract: Many induction motor controllers employ a reference angle relative to the supply voltage which is a target for the phase lag of current behind voltage but the choice of the optimum reference angle for energy saving varies from motor to motor. In the present invention firing signals for thyristors connected between a supply and a motor to be controlled are generated by firing circuits under the control of a microprocessor 18. The firing angle for the thyristors is continuously adjusted according to the phase lag as indicated by supply voltage zero crossings and current sensing circuits, load on the motor, and a signal indicating the tendency of the motor to stall obtained from the back e.m.f. of the motor. Using the said signal can be regarded as equivalent to adjusting the reference angle for the optimum value mentioned above. A procedure for starting a motor and setting the initial value of the reference angle is also described.

Abstract: An induction generator/motor system has an induction machine connected at its secondary side to a cyclo-converter. An induced voltage develops when the cyclo-converter pauses during a transient phenomenon occurring in the system. When the induced voltage exceeds a predetermined voltage range which covers the maximum output voltage derivable from the cyclo-converter, the polarity of thyristor converters of the cyclo-converter is switched such that the induced voltage is applied to a thyristor converter to be rendered conductive next in forward relationship therewith, thereby preventing occurrence of an overvoltage.

Abstract: A method for providing a smooth transition to powered operation in a motor control system in which a variable voltage inverter regulates power to the motor on a volts per Hertz basis. The method is particularly applicable to systems for energizing and rapidly gaining control of a motor driving a load in which the motor armature is turning at the time that power is supplied from the variable voltage converter. The method is implemented by sweeping the frequency of the excitation applied to an alternating current motor while holding the magnitude of the excitation at a level sufficient to prevent over current excitation of the motor.

Abstract: In the field-oriented control of an asynchronous machine, the flux angle of which is calculated by a flux computer from the current and the voltage as the integral of the EMF, the correct flux vector must be available already at the start-up of the machine. For this purpose, one axis (M.phi.1) of a model coordinate system as well as the components (iO*, iM*=0), referred to the model coordinate system, of a vector parallel to this axis is determined at an input device (E1, E2) by a constant, given starting angle (.phi.MO*). This vector is transformed by means of the field angle (.phi.s) calculated by the flux computer for forming the converter control variables into the stator coordinate system while the machine is excited but standing still. The angle deviation (.phi.MO*-.phi.s) of the calculated field angle from the starting angle is used by a controller (CR) for correcting the calculated field angle.

Abstract: A circuit is provided for controlling energization of the start winding of an alternating current motor whose shaft is divided into a number of angular segments equal to the number of poles of the motor. A shaft pulse is generated each time one of the angular segments rotates past a predetermined point. A line pulse is generated for each half cycle of line voltage. The shaft pulses are multiplied by the denominator of a selected trip-out ratio while the line pulses are multiplied by the numerator of the trip-out ratio. The multiplied shaft and line pulses are provided to an up/down counter which counts the shaft pulses down and the line pulses up. During the counter overflow condition, the circuit connects the start winding to the line voltage source. During the counter underflow condition, the circuit disconnects the start winding from the line voltage source.

Abstract: In a power supply system for a variable reluctance motor, each phase winding of the motor is connectible across a pair of supply rails by first and second switch means located respectively between the first supply rail and the winding and between the winding and the second supply rail. The first switch means is a fast switch-off device such as a gate turn-off thyristor or a transistor, while the second switch means is a slow turn-off device, such as a thyristor suitable for application to a line-commutation situation. In a two-phase configuration, where the second switch means is a thyristor, force-commutation of the second switch means may be achieved by means of a suitable capacitor interconnection between the thyristors switching the respective phases.

Abstract: A variable frequency AC induction motor servo control system wherein slip is momentarily increased in response to error signal transients. In a preferred embodiment, a phase shift is introduced in the energizing stator current as the servo velocity error signal increases over at least the lower portion of the error signal range, the maximum phase shift being between 45.degree. and 90.degree..

Abstract: For establishing the field direction without mechanical pickup upon startup of a rotating field machine, e.g., in permanent excitation, a high-frequency component (iz*) is impressed on the stator current or on the stator voltage. Thereby high-frequency voltage components (or current components) are coupled into the stator windings, the envelope curves of which are correlated to the position of the field axis of rotor axis. Preferably the components of a model vector (FM) which also contain high-frequency components are calculated by a flux computer (60). The high frequency components isolated in a filter (61) are correlated in a means value former (62) to the components of the direction vector (fx). Thereby a field-oriented operation of a synchronous machine is possible.

Abstract: This invention relates to a motor controller which is so arranged that voltage to be applied to drive windings of a synchronous motor (1) is switched by a plurality of switching elements of a power inverter circuit (4), while the current supply amount to the switching elements is controlled based on pulse width-modulated signals, and which is provided, at a distributing section for selecting energization of said switching elements, with a first logic circuit for applying the pulse width modulation only to the predetermined switching selected from among the switching elements selected during forward rotation of the motor, and a second logic circuit for applying the pulse width modulation to all of the switching elements selected during the reverse rotation of the motor, so as to thereby effect the reduction of electro-magnetic noise during the forward rotation, and to effect the suppression of current during the reverse rotation.

Abstract: An induction machine having a stator carrying phase coils divided into at least two independently fed sets of coils, with a rotor or armature carrying one or more loop members, each of which is a short-circuited, continuous isolated loop conductor member having elements thereof positioned and received within the slots of the armature in a generally serpentine configuration forming at least two open loop portions, each loop portion being in a spatially related position to a corresponding coil of the stator structure, with each conductor element within a slot phasing or linking the fluxes of one stator pole. The machine may be single phase or polyphase. At least one stator phase coil of a set includes a controllable device in circuit relation therewith to enable control of one stator coil relative to the other, either in current magnitude or in current phase shift, the controllable device being either a silicon controlled rectifier or a triac.

Abstract: An electric motor operating on the reluctance principle employs spaced rotor discs presenting rings of inwardly fcing poles of alternating polarity, typically by means of permanent magnets, and an annular stator between the discs consisting of a ring of H shaped cores, with the stems of the H's extending peripherally. Two sets of windings on these cores are energized alternately so as to provide alternating polarization of pole pieces presented by the cores to the rotor discs, with a timing such as to produce continuous rotation at a controlled rate, of the discs as their magnets seek a minimum reluctance position.

Abstract: A motor starting circuit in which a triac connected in series with the starting winding of the motor is gated into conduction for only a preselected time period following motor start-up. A switching circuit, in parallel with the serially connected triac and starting winding, includes an SCR which provides a low resistance signal path to the gate of the triac at such time that the SCR is in a conducting state. The SCR is gated by a resistance network and the time period is established by an RC circuit which gates a switch at the end of the selected time period to short out the portion of the resistance net work to which the gate of the SCR is connected so as to turn off the SCR and leave a high resistance path through the switching circuit to the gate of the triac.

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: A three-phase induction motor control apparatus resorting to a slip frequency control type vector control system having three-phase sine wave generating device, first operation device, second operation device, and vector operation device; whereby a current command value and a frequency command value are determined in accordance with a difference between a set velocity and a real velocity to determined a control current value. The three-phase sine wave generating device generates a three-phase sine wave having a frequency according to the frequency command value. The first operation device multiplies one of outputs, which are outputted from the three-phase sine wave generating device and mutually have a phase difference of 120.degree., and a preset value to determine one current component value.

Abstract: Low cost, low part content motor control circuitry is provided, including blanking interval circuitry (42, 25) for preventing immediate connection of the start capacitor (5) of a single phase AC induction motor to the AC source (4) upon energization of the motor, to protect the start capacitor (5) and the start switch (6) against an overcurrent condition if the motor is de-energized while in the running mode and then re-energized while still coasting above a given speed, and to particularly prevent burn-out of the start capacitor (5) and/or start switch (6) upon reapplication of electrical power after a momentary power outage. Differently sized capacitors (42, 24) provide an early cross-over of auxiliary winding voltage relative to main winding voltage at the input of a quad comparator chip (31-34) to disable a turn-on signal for the start switch (6).

Abstract: Blanking interval circuitry (106, 108, 110, 104) is disclosed for preventing immediate connection of the start capacitor (5) of an AC motor to the AC source (4) upon energization of the motor, to protect the motor against an overcurrent condition if the motor is de-energized while in the running mode and then re-energized while still coasting above a given speed, and to particularly prevent burn out of the start capacitor (5) and/or start switch (10) upon reapplication of electrical power after a momentary power outage. The start capacitor (5) is disconnected from the AC source (4) during a time delay blanking interval regardless of whether auxiliary winding voltage is above or below a given cut-in value relative to main winding voltage as a function of motor speed corresponding to a given cut-in speed.