Abstract: A motor control apparatus composed of a first pulse multiplier circuit for multiplying command pulses by a first factor, encoder circuit for detecting a position of a motor-driven object, a second pulse multiplier circuit for multiplying a detection pulse from the encoder circuit by a second factor, a deviation counter circuit for detecting a difference between output pulses of the first and second multipliers, a divider circuit for dividing an output signal of the deviation counter by the second factor, and driving source driven by the control apparatus in accordance with an output of the divider.

Abstract: A battery powered traction vehicle propulsion system uses an alternating current (AC) adjustable speed electric traction motor to propel the vehicle. The motor is connected to a source of controllable AC power that is responsive to a control signal for setting the value of power applied to the motor. A function generator produces the control signal in response to a command signal and limits the rate of change of the control signal and its minimum and maximum values. The minimum and maximum values are varied in response to preselected operating characteristics of the propulsion system, such as, for example, battery voltage, motor temperature, motor and vehicle speed and control system temperature.

Abstract: A motor speed controlling device controls the rotational speed of a motor by feeding back an actual rotational speed detected by a photocoupler. An encoder disk formed with equi-pitch slits in the periphery thereof is attached to the drive shaft of the motor, and a photocoupler is provided in association with the encoder disk. CPU computes ON duration Ton and OFF duration Toff of pulse trains produced from the photocoupler when the motor is rotating at a constant speed. If the ON duration Ton and OFF duration Toff are unequal, ON correction factor and OFF correction factor are computed based on the measured ON and OFF durations, whereas if the ON duration and OFF duration are equal to each other, the ON and OFF correction factors are set to one (1). The CPU corrects the ON and OFF durations Ton and Toff based on the ON and OFF correction factors.

Abstract: A apparatus is provided for estimating the position of a rotor of a commutated brushless motor operating without a shaft position sensor. The apparatus includes a tank circuit that incorporates a phase winding of the motor. A low-power signal of a frequency F.sub.1 is injected into the tank circuit. The frequency F.sub.1 is much greater than the switching frequency F.sub.s of the phase winding. Because the effective inductance (L) of the phase winding incorporated into the tank circuit changes in a cyclic manner in response to changes in the mechanical angle .THETA. of the rotor, the characteristic resonant frequency F.sub.0 of the tank circuit varies between maximum and minimum values. The effect of the variation of the resonant frequency F.sub.0 on the output characteristics of the tank circuit are used by a detection circuit to resolve the mechanical angle .THETA. of the rotor and, thereby, control the timing of the phase firing sequence.

Abstract: A motor control device carries cut feedback control of a motor such that the rotational speed of the motor is equal to the command speed. A control voltage is first calculated as the sum of a first constant times the difference between the command speed and the actual rotational speed, a second constant times the actual rotational speed and a predetermined offset value. The calculated control voltage is corrected on the basis of the phase difference between the command speed and the actual rotational speed and a voltage after the correction is outputted as a motor control voltage. The rotational speed of the motor can be caused to rapidly follow the target speed by adjusting the first and second constants and the offset value whether the command speed is relatively low or high, thereby to make it possible to control the motor at a constant speed.

Abstract: In the regulation of the torque response of multiphase electronically commutated electric motors, in particular synchronous motors, a constant moment of rotation response is achieved by forming the nominal current values for the phases to be regulated depending on a torque-regulating variable and the rotor position. A current regulator is assigned to each current phase to be regulated. The method makes it possible to preset a nominal current value for each phase to be regulated for any adjustable torque as a function of the particular rotor position. The separate regulation of the nominal current values ensures that the up-commutating current is alternating exactly with the down-commutating current and hence no system-caused torque transients occur.

Abstract: In a motor speed controller for controlling an AC motor to be driven at a variable speed, a signal proportional to a load torque and a signal proportional to an output torque of the AC motor are found by current detecting means for detecting the primary current of the AC motor, and integrated over the speed changing period, and the integrated values are divided by the values corresponding to the amounts of speed change during the speed changing period so that the moment of inertia can be computed. In addition, there is provided means for changing the rate of output frequency change caused by the output frequency command into a value according to the calculated moment of inertia. Moreover, there is provided a circuit for detecting a sudden change of the calculated moment of inertia, so that when a sudden change occurs, an abnormality signal is generated.

Abstract: A control for a clothes dryer with an induction drive motor and an electric resistance heater element. A single sense winding is threaded through sensors monitoring drive motor current and heater current, generating an output voltage each time the alternating motor or heater current passes through a zero-crossing. The control monitors the ON/OFF condition of the heater and samples the lagging phase angle of the motor current, to provide an improved means of detecting when the clothes load is dry by measuring variation in motor torque due to minute differences in the way that the clothes load is tumbling from one drum revolution to the next revolution, ignoring cyclical, repetitive variation due to uneven drum rotational friction. The control provides a clothes cooldown period with controlled moisture regain as per the user dryness selection.

Abstract: A motor speed control system takes one approach to establish dummy load models having characteristics equivalent to an electric motor to be controlled. One of the dummy load models is established for feedback controlling the electric motor on the basis of the speed of the dummy model. The dummy model is divided into first and second models. The first model is designed to have equivalent characteristics to output a first motor speed representative data. The current to supply to the first model is so adjusted as to reduce a difference between the motor speed representative data and a desired motor speed data to zero. A frequency signal is added to the current applied to the first model and supplied to the electric motor to drive the latter. The second model receives the frequency signal to output a frequency signal dependent second motor speed representative value.

Abstract: An apparatus and method for controlling the velocity of a motor controls the motor by fuzzy inferential reasoning in a transitional period when the motor is started, changed in speed, reversed or stopped. Such fuzzy control eliminates an increase in the length of the transitional period caused by a limitation in supply current under conventional PLL control and makes possible a rapid transition to a target velocity. A plurality of fuzzy rules are provided and one of these fuzzy rules is selected in accordance with the length of the previous transitional period, thereby suppressing the effects of load fluctuation and the influence of a fluctuation in torque caused by a rise in temperature. Therefore, the length for transitional control of a motor can be shortened and the apparatus can be reduced in size.

Abstract: An alternating current motor control method capable of preventing or reducing variations in motor output torque in a low speed motor operation.During a low speed operation of a motor (6), a combination of a second pulse coder (PC2) for detecting the rotational position of a motor (6) with high resolution and a second table (T2) storing therein current command determining sinusoidal data with high resolution is selected by a processor, serving as selection means (20) and switches (SW1, SW.sub.2), so that sinusoidal data of respective phases are read out from the second table in accordance with a primary phase angle (.theta.) of the motor, which is determined by an actual motor rotational speed detected in dependence on the number (FP2) of pulses supplied from the second pulse coder, and the drive of the motor is controlled in accordance with current commands of respective phases derived with high resolution on the basis of the sinusoidal data, thereby preventing variations in the motor output torque.

Abstract: A motor control system is disclosed which includes an encoder for generating pulses in proportion to the rotational amount of the motor. A speed instructing unit provides a speed instruction for the desired rotational speed of the motor. A speed control unit calculates (1) the actual rotational speed of the motor based on the pulse signal from the encoder and (2) a voltage to be applied to the motor and outputs a PWM signal which represents the actual motor speed. The PWM signal is identical with the voltage to be applied to the motor. This arrangement ensures that the motor speed will follow the speed instruction. A driver unit supplies electric power to the motor by amplifying the PWM signal.

Abstract: A method and an electronic device for determining the optimal excitation value (stator current, magnetic flux, magnetic induction) which minimizes the electromagnetic (copper and iron) losses of DC and vector-controlled AC machines. The invention provides the command to the excitation control loop of these electric machines, characterized by the multiplication or amplitude-modulation (1) of a periodic signal of angular frequency proportional to the speed of the electric machine, a first-order low-pass filter (2), an amplifier (3) and a peak detector (4). The output of the peak detector (4) provides the optimal command to the excitation control loop of the electric machine by a signal of amplitude proportional to the rotor current, i.sub.a.

Abstract: A current component, in which a phase angle is different by a predetermined reference angle from a magnetic flux occurring in an inductive load, is brought to a q-axis current. The q-axis current is computed on the basis of phase current. A phase angle of the magnetic flux is detected. A q-axis-current control phase and a reference potential phase are determined on the basis of the result of pulse-width-modulation computation and the phase angle. The q-axis-current control phase is controlled in a pulse-width-modulation manner. A potential of the remaining reference potential phase if fixed to a reference potential. Thus, interference among the phases is prevented to reduce current ripple.

Abstract: An electronic control for a motor which eliminates the motor centrifugal switch and more particularly a control for a domestic refuse compactor which permits the user to control the approximate full trash bag weight and obtain more compaction from a split phase induction drive motor. A ferrite core sensor on the main winding of the drive motor samples the lagging phase angle of the motor main winding current during a compaction stroke. A low force cycle is achieved by terminating the stroke as soon as phase samples fall below a threshold defined at the start of each cycle by a locked motor main winding phase sample acquired prior to starting the motor. A medium force cycle terminates the stroke when compaction forces exceed the main winding breakdown torque.

Abstract: An electrically powered suspension for a vehicle including a roadwheel and tire assembly, an electrically powered suspension unit having one end attached to the roadwheel and tire assembly and the other end attached to the chassis of the vehicle, with the suspension unit including an electric motor for positioning the roadwheel with respect to the chassis, and a controller for operating the electric motor so as to control the vertical movement of the wheel and tire assembly with respect to the vehicle's chassis. The electric motor may include either a linear or rotating electric motor, acting either alone or in parallel with a static load carrying device such as a fluid or coil spring.

Abstract: The load torque of a compressor for circulating refrigerant in a refrigerating cycle changes with the rotational position of the shaft of the compressor, and the phase difference between the primary current and voltage of an induction motor for driving the compressor changes with the load torque. Taking the above facts into consideration, in turning off the compressor driven by the induction motor, which is powered by a fixed frequency AC power source, the shaft position of the compressor is detected in accordance with the phase difference, and the current of the motor is turned off at the timing of a particular phase difference when the load torque becomes minimum, thus reducing vibration when the compressor is stopped.

Abstract: A control for a clothes dryer with an induction drive motor and an electric resistance heater element. A single sense winding is threaded through sensors monitoring drive motor current and heater current, generating an output voltage each time the alternating motor or heater current passes through a zero-crossing. The control monitors the ON/OFF condition of the heater and samples the lagging phase angle of the motor current, to provide an improved means of detecting when the clothes load is dry by measuring variation in motor torque due to minute differences in the way that the clothes load is tumbling from one drum revolution to the next revolution, ignoring cyclical, repetitive variation due to uneven drum rotational friction. The control provides a clothes cooldown period with controlled moisture regain as per the user dryness selection.

Abstract: The invention comprises a DC link resonant converter for controlling the speed of AC machines. Switch and power supply means is provided to establish a bi-directional initial current in the resonant circuit. By selecting the plurality and magnitude of the initial current, the peak voltage of the resonant link is controlled, and reliable zero crossing of the resonant voltage is assured. Current technology permits resonant frequencies in the range of 50-100 kilohertz to be utilized.

Abstract: An electronically controlled sewing machine, comprises a current detecting device for detecting a value of current flowing through a stepping motor that drives a machine part and current setting means for setting a value of current to be applied to the stepping motor. The sewing machine further includes a control device (CPU) for storing a plurality of different values of currents to be applied to the stepping motor and driving the stepping motor until the stepping motor passes through an initial position thereof. The control device stops the stepping motor at a predetermined angular position thereof spaced from the initial position. The control device supplies the different values of currents to the stepping motor in a predetermined sequence from a smallest value to a larger value of current under a predetermined program to drive the stepping motor until the stepping motor reaches the initial position thereof.

Abstract: A digital current control arrangement for optimizing the transport time delay of a thyristor power supply used as a source of armature current for a DC motor utilizes a coarse gate angle interrupt subroutine to perform a preliminary calculation of the gate firing angle for the next thyristor to be fired. The coarse gate angle calculation is performed at a predetermined time following the firing of a previous thyristor. A finite gate angle interrupt subroutine is also provided for recalculating the gate firing angle at a second predetermined time just prior to the firing of the thyristor. The finite and coarse gate angle interrupt subroutines both perform their respective calculations using the common parameters. A flag passing arrangement is also included in the current control arrangement and is effective to insure that the finite gate firing angle is the preferred calculation used in the firing of the next thyristor.

Abstract: An AC-excited generator/motor apparatus comprising; an AC-excited generator/motor having an armature mounting thereon; an armature winding connected to an AC power system and a rotor mounting thereon; and an exciting winding excited by an AC current. An exciting device for supplying a controlled AC exciting current to the exciting winding comprises; a device for calculating a real slip frequency based on a difference between the phase of an armature voltage appearing on the armature winding and the rotational phase of the rotor; and a device for controlling the exciting current supplied to the exciting winding from the exciting means in response to a deviation of the real slip frequency from a predetermined allowable range of slip frequencies so as to restore the real slip frequency within the allowable range of slip frequencies.

Abstract: A motor control circuit measures the motor voltage to determine actual motor speed. This speed voltage is the sum of the back emf and armature loses. The control circuit receives a reference voltage proportional to the desired motor speed and a further signal voltage indicative of the motor armature losses. These three voltages are combined to provide a first error signal representing the difference between the reference voltage and the motor back emf. This error signal is substractively combined with a signal representative of the motor power to produce a control signal for a modulator circuit which in turn controls a semiconductor switch in series with the motor.

Abstract: A speed control circuit (50) for a single phase AC induction motor (12) includes a phase control circuit (10) for connecting a main winding (16) to an AC source (18) at a variable time delay phase angle during the half cycle of the AC source, and a boost circuit (52) including a motor speed sensor (54, 56) sensing motor speed and altering the delay interval phase angle in response thereto. The boost circuit shortens the delay interval in response to decreasing motor speed, and lengthens the delay interval in response to increasing motor speed, such that almost full voltage is applied during starting of the motor, which voltage is reduced as the motor begins running.

Abstract: A polyphase AC motor drive system comprises an electric power inverter and control means which enables operation in, and allows smooth transition between, a current controlled PWM mode and a quasi-square wave mode of operation. At low motor speeds, the system operates in PWM mode. At higher speeds, above the corner point speed of the motor, the system operates in a quasi-square wave mode. Smooth transitions between modes of operation are controlled by a microcomputer which counts the number of current chops made by a switching device in a preselected phase leg of the inverter over a time interval that varies with the desired fundamental period of the motor current. As speed increases and approaches the corner point, the number of chops decreases below a first predetermined number, and the system transitions from PWM to quasi-square wave mode. As speed decreases, the number of chops increases above a second predetermined number (larger than the first), and the system transitions back to PWM mode.

Abstract: An electric power converter, in which a plurality of converters convert a first electric power having a first frequency into a second electric power having a second frequency, and the second electric power is supplied to a load such as an electric motor, and in which a correction controller changes a reference voltage to generate reference voltage signals to be supplied to the converters in order to shift firing phase angles of the converters, thereby preventing a generation of higher harmonics of integer orders of the first electric power.

Abstract: Power consumed by an ordinary a.c. induction motor is reduced by having two parallel sets of separately excited RUN windings. When the motor is lightly loaded, a.c. power feeds only one of the two RUN windings, thereby reducing the flux density in the motor stator and as a result reducing eddy current losses and copper losses. Whe the load increases, a.c. power is immediately fed to the other RUN winding thereby increasing the magnetic flux density and the motor power. The a.c. power fed to the second winding is variably controlled by a thyristor, and the amount of thyristor coupled power may be determined from sensing changes in the speed slip of the induction motor wrought by load changes. Through having the one RUN winding permanently connected with the power source, while the other RUN winding power is modulated by the phawe controlled gating action of the thyristor, less a.c.

Abstract: A method for controlling a rotating-field machine supplied from an inverter, the output voltage system of the inverter being variable with respect to amplitude, phase and frequency includes supplying amplitudes of stator flux components formed from measured stator current components and stator voltage components as actual value of a flux control loop, and changing the phase and frequency of the inverter output voltage system with a flux control as a function of a predetermined stator flux reference value by directly setting-in the switching state of the inverter and an apparatus for carrying out the method.

Abstract: The device comprises a variable frequency AC generator with means of exitation supplied by means for controlling exitation current, means for regulation of the frequency of the generator as a function of an index value, means for measuring actual speed of the mobile portion of the motor, and means for comparing actual speed with the index value. According to the invention, the means for controlling the exitation current are connected to the means for comparing actual speed with the index value, and the generator has a high internal reactance.

Abstract: A pulse encoder (2) is provided for generating a position code IP corresponding to the rotational position of a rotor of a motor (1), as well as rotation pulses AP, BP each of which is produced whenever the rotor rotates by a predetermined amount. The rotation pulses AP, BP are applied to a counter (32) via quadrupling pulse generating circuit (30). A leading edge/trailing edge sensing circuit (31) is provided for sensing a transition point of the position code, with the counter (32) being preset by an output from the circuit (32). Thus, the position of the rotor is capable of being indicated precisely based on the position code and the value counted by the counter.

Abstract: A machine for floor maintenance comprising an electric motor in which armature coils are included in a stator and permanent magnets are included in a rotor. The armature coils are disposed substantially radial to the axis of the stator with the axial extent of each coil lesser than the radial extent of each coil, and the permanent magnets of the rotor are disposed substantially radially to the axis of rotation of the rotor with the axial extent of each permanent magnet lesser than the radial extent of each permanent magnet. A three phase switching circuit excites the armature coils in impart rotation to the rotor. As a consequence thereof, the motor has a configuration conforming substantially to the pad or brush of the machine. The pad is attached to the rotor by a pad holder which is formed with a convex surface for engaging the pad.

Abstract: A microcomputer-based motor control system provides overload protection by incrementing a register whenever a full power condition exists and decrementing the register when less than a full power condition exists. When the register reaches a predetermined value, this indicates an overload condition.

Abstract: A motor control system in which an actual torque indication is derived from the motor and compared with a reference, or demand, torque. From the difference signal is derived a stator M.M.F. in magnitude and position relative to a reference frame locked to the rotor. Orthogonal components of this stator M.M.F. are derived and transformed to stator phase winding drive signals.

Abstract: A control system for eddy current coupling drive for armoured face conveyors wherein the systems controls a number of eddy current drives via a pair of power supply lines and a single pilot line. A main contactor controlled by a relay is held closed by contact of a pilot relay which is energized only if relay contacts in individual control units for each drive remain closed. These last mentioned contacts open if certain operating conditions are not met.

Abstract: A scalar control supplemented by a decoupler transfer function control is provided to develop frequency and current commands for a current controlled inverter driving an induction machine. The machine torque is controlled by the slip and corresponding torque producing component of stator current. The rotor flux is maintained constant by the flux component of stator current. The total stator current is controlled to hold rotor flux constant with desired torque during steady state conditions and the decoupler compensator varies stator current to maintain rotor flux constant during transient conditions.

Abstract: Disclosed is a control apparatus for an AC motor which is driven by a power converter constituted by switching elements. A current control circuit turns on/off the switching elements in accordance with a current pattern signal in the form of an AC signal to thereby control the motor current. The current pattern signal is obtained by a current pattern calculating circuit based on a current command signal and a sinusoidal signal which determines the current phase. A current correction signal proportional to the deviation of the motor current from the current command signal is obtained by a current correction control circuit and added to the current command signal to be applied to the current pattern calculating circuit.

Abstract: An electronically controlled rotating synchronous machine having armature and field windings on the same magnetically-permeable core. The rotor of the machine is an open tooth structure. The self inductance of the armature and field windings is substantially independent of relative position between the rotor and stator but mutual inductance between the armature and field windings varies with relative position. A rotor position detector senses the voltage in one of the machine windings and relates that voltage to said relative position. Switches are provided to control electric current flow in the armature winding on the basis of the voltage sensed by the detector.

Abstract: A method for optimizing the power input to a plurality of parallel connected hysteresis motors wherein a three phase alternating voltage source jointly supplies the motors with an adjustable operating voltage. The method includes measuring, during the operation of each motor, the phase angle difference between motor voltage and motor current and determining the power factor therefrom for each motor. The effective current value of each motor is measured during operation and is combined with the power factor to obtain the active current for each motor. An active current limit value at which each motor transitions from synchronous to asynchronous operation is measured once and stored for each motor prior to commencement of continuous synchronous operation.

Abstract: A machine for floor maintenance comprising an electric motor in which armature coils are included in a stator and pemanent magnets are included in a rotor. The armature coils are disposed substantially radial to the axis of the stator with the axial extent of each coil lesser than the radial extent of each coil, and the permanent magnets of the rotor are disposed substantially radially to the axis of rotation of the rotor with the axial extent of each permanent magnet lesser than the radial extent of each permanent magnet. A three phase switching circuit excites the armature coils to impart rotation to the rotor. As a consequence thereof, the motor has a configuration conforming substantially to the pad or brush of the machine. The pad is attached to the rotor by a pad holder which is formed with a convex surface for engaging the pad.

Abstract: Electric motor starter circuits for operating motors which cannot be restarted under load, but which maintain sufficient momentum during merely momentary interruptions of AC power to continue normal operation upon power restoration. Conventional motor starter circuits drop the motor off line, even in the event of momentary interruptions. The starters disclosed herein prevent unintended and unnecessary equipment down time as a result of AC motor starters dropping out during mere momentary power interruptions through the provision of a delayed drop out circuit including a DC voltage storage capacitor connected to the coil of the motor starter relay subsequent to the initiation of normal AC energization. In one embodiment, actual motor rotation is sensed to determine when to allow the motor starter relay to drop out.

Abstract: A trigger control circuit is provided for producing firing pulses for the thyristor of thyristor control system such as a power factor controller. The control circuit overcomes thyristor triggering problems involved with the current lag associated with controlling inductive loads and utilizes a phase difference signal, already present in the power factor controller, in deriving a signal for inhibiting generation of a firing pulse until no load current is flowing from the preceding half cycle and thereby ensuring that the thyristor is triggered on during each half cycle.

Abstract: The present method and circuit arrangement control the r.p.m. of a three-phase motor connected in a star or Y-circuit by sensing current variations in the star point of the motor windings. These current variations are converted into voltage variations which represent the current input of the motor windings. These voltage variations are used to control the duration of the application of the operating voltage to the motor windings for varying the motor r.p.m. The circuit for this purpose includes a controlled diode circuit arrangement connecting the motor windings to the star point and a control or drive circuit for controlling the diode circuit arrangement The drive circuit makes the diode circuit arrangement conductive for predetermined time durations which depend on the voltage variations. These time durations are also manually adjustable in an open loop control, whereby a closed loop control is provided in combination with an open loop control.

Abstract: Apparatus for controlling the speed of a motor which includes a switch connected in series with the motor for controllably conducting an A.C. signal to the motor and means for controlling the switch which includes first means for generating a series of pulses at a frequency which may be varied according to an input signal, second means for generating a pulse once per cycle at a zero crossing of the A.C. signal, third means for generating a pulse at said A.C. signal zero crossing if a pulse was produced by the first generating means during the A.C. cycle immediately preceding said zero crossing, and fourth means responsive to the output of the third generating means for generating a pulse which is supplied to and renders conductive said switch for one complete A.C. cycle.

Abstract: A starting control circuit is provided for an alternating current motor having a run winding and a start winding and a mechanical rotational output. The motor is powered by an alternating current source. A reference oscillator produces pulses having a reference frequency. A first control circuit is provided for counting the number of reference pulses produced during a predetermined number of cycles of the alternating current source. A sensor is provided for sensing a predetermined amount of rotational movement of the mechanical rotational output of the motor and producing a sensor pulse indicative thereof. A second control circuit is provided for counting the number of reference pulses produced during the time between a predetermined number of sensor pulses and for comparing the counts on the first and second control circuits. The second control circuit assumes first and second output states dependent on the relationship between the first and second output counts.

Abstract: A multiple speed control means for a variable speed motor system used for driving a hoist including multiple fixed speeds and a low speed range which is incrementally variable throughout the range. The control means provides distinct voltage levels which correspond to fixed motor speeds, the highest voltage corresponding to the maximum or full speed of the motor. Manual switch means switch into these fixed speeds or into the variable low speed range when the system is either in the hoist or lowering mode for respectively lifting or lowering a load in place.A quick response circuit is connected into the system for a predetermined time duration after the system is switched into any of the speed positions except the maximum speed position.

Abstract: A digital self-calibrating power factor controller for an AC induction motor. During start-up a first number corresponding to the actual phase angle between motor voltage and current is determined and compared with a second number corresponding to a desired delay in energizing the motor. The second number is varied until both numbers are approximately equal. A third number corresponding to a desired phase angle is determined and stored and the system switches from start-up to run. The first number corresponding to the actual phase angle is now compared with the third number corresponding to the desired phase angle. The second number corresponding to a desired delay is now varied with motor load so as to keep the actual phase angle equal to the desired phase angle.

Abstract: A plurality of controlled current inverter circuits each including a plurality of electrical current conducting legs having controlled rectifiers and associated commutating capacitors are connected in parallel and individually controlled to collectively supply an alternating current motor load with electrical power. At high speed, low required torque conditions, less than the total number of inverter circuits are maintained operative to thereby maintain sufficient current within the effective inverter circuit or circuits to sustain effective inverter commutation.

Abstract: Electric motor control apparatus includes a variable-frequency oscillator 10, a counter 11 clocked by the oscillator, and signal generating means 12 arranged to generate two sinusoidal voltages in quadrature with one another. The two voltages are applied through separate amplifiers 22, 23 to separate stator windings 24, 26, of the motor, the stator windings being 90.degree. apart. Control means includes a bistable circuit 28 producing a signal lagging 45.degree. behind one sinusoidal voltage, and a phase sensitive detector 29 arranged to vary the frequency of the oscillator 10 to maintain a constant phase difference.

Abstract: A control system for an electric car driven by an induction motor which is supplied with electric power of a variable frequency and a variable voltage from an inverter comprises means for detecting the car speed, means for setting a slip frequency of the motor, a frequency command generator, control means for controlling the output frequency of the power converter in accordance with the frequency command and controlling the output voltage of the power converter, a current command generator, and a voltage command generator. The output voltage of the power converter is controlled in accordance with selected one of the current command and the voltage command while being limited by the other command.

Abstract: A digital control loop is provided in which analog signals supplied by a tachometer, driven by an electric motor, are digitally evaluated, that is are compared with a reference value existing in digital form, and a deviation from the reference is employed for controlling the adjustment of an element, a thyristor preferably a triac, by way of an adjusting value generator which is likewise designed as a digital circuit. The speed control regulator can be designed both with an integral control behavior, and a differential control behavior, as well as being designed with a proportional control behavior and combinations thereof.