Abstract: A synchronous motor control apparatus includes a polyphase synchronous motor, a frequency adjusting circuit responsive to the closing of a power supply switch to generate a frequency control signal for commanding to linearly increase an oscillation frequency from zero up to a given high frequency, a polyphase rectangular oscillation circuit whose oscillation frequency for polyphase rectangular waves is controlled in accordance with the frequency control signal, an energization phase adjusting circuit for generating a phase control signal in accordance with a signal related to the frequency control signal from the frequency adjusting circuit, an energization phase calculating circuit for controlling the phases of the polyphase rectangular oscillation frequency of the polyphase oscillation circuit, and a drive circuit for amplifying output polyphase rectangular signals of the energization phase calculating circuit and applying the same to a field winding of the motor.

Abstract: A solid state starting and control circuit for AC motors employing a single phase power source is disclosed in which the normal motor starting capacitor and speed responsive switch or similar means for energizing and deenergizing the start winding are eliminated by use of an all electronic, sparkless circuit which provides phase displaced current to excite the motor starting winding and in which there is time regulated gradual decreasing of the starting current pulse width to deenergize the start winding.

Abstract: When induction motors are lightly loaded their power factors and efficiency are poor but in the present invention power factor is controlled regardless of load. An induction motor is connected by way of a triac to a supply. The voltage across the triac is monitored by a comparator for voltage steps which correspond to current turn-off and a signal is developed at the output of an amplifier which represents error from required phase lag. A further comparator and a trigger pulse generator trigger the triac in accordance with the error. An override circuit overrides the control system during starting. A number of further induction motors may be connected in parallel with the motor. Additional circuits deal with problems arising when a three-phase induction motor is connected by three wires only.

Abstract: A three-phase induction motor control method according to the present invention subjects a three-phase induction motor to vector control by an output from an inverter which is supplied with a direct current obtained by conversion from an AC input. The method includes sensing a DC-converted voltage at a DC link section, varying a flux command in dependence upon the sensed DC voltage, and controlling the motor to obtain a constant output irrespective of a fluctuation in power supply voltage.

Abstract: The invention relates to a control unit to control a continuous cycloconverter of the non-circulating current type which performs frequency conversion of an AC power source using a semiconductor element a to perform commutation by the AC power source and variable speed operation of an AC motor.

Abstract: A motor current flowing through an inverter-driven induction motor is detected when voltage is applied to the induction motor by the inverter operated under a certain condition on the basis of the vector control. The detected current is converted to two components of a current vector in a d-q coordinate system. Motor constants are calculated on the basis of a component in the d-coordinate axis of a voltage reference set for creating the certain condition and the two converted components of the motor current detected at that time, and control constants in a vector control apparatus for the inverter-driven induction motor are set or adjusted in accordance with the calculated motor constants. According to this invention, the control constants in the vector control apparatus can be easily set or adjusted.

Abstract: A variable speed 3-phase a-c motor is connected to a 3-phase source of alternating voltage via a plurality of controllable solid state electric valves which are so arranged and controlled that motor speed can be reduced by skipping selected cycles of the source voltage. For half speed operation 12 valves are arranged to interconnect the source and motor phases, and over two consecutive periods of the source voltage six separate, uniformly spaced "firing windows" are selected during which the conducting states of different pairs of these valves are initiated in a predetermined pattern that results, in each phase of the motor, in a double-pulse current waveform having one-half the fundamental frequency of the source voltage.

Abstract: A method of forming the amplitude of the reference voltage of a three-phase inverter supplying a squirrel cage motor requires no current measuring elements. In this method, the amplitude is formed by finding in predetermined constant flux curves which represent the squirrel cage motor in question, and in which the motor rotor current frequency appears as parameter, a curve from which is obtained the amplitude of the motor stator voltage, i.e. of the inverter reference voltage, corresponding to the frequency of the motor's stator voltage, i.e. of the inverter reference voltage, so that the magnetic flux in the stator will be constant.

Abstract: A motor starting circuit (10) is provided for disconnecting the start winding (14) of a single phase AC induction motor from an AC source (18) after a time delay. A start switch (22) in series with the start winding (14) controls energization and disconnection of the start winding (14). Turn-on of the start switch (22) is controlled by a turn-on switch 28 connected in parallel across the start switch (22) and not across the start winding (14). Turn-off of the start switch (22) is controlled by a cut-out switch (50) which in turn is controlled by an RC timing circuit (58, 60) connected across the AC source (14). A restart switch (64) may be added without changing the remaining circuitry. The restart switch (64) controls charging of the timing capacitor (60) and causes reconnection of the start winding (14) to the AC source (18) when motor speed drops below a given cut-in speed.

Abstract: A control apparatus for an induction motor comprises a variable voltage, variable frequency inverter feeding the motor, which is controlled by the PWM control. A secondary current component and an exciting current component of the motor are obtained by the calculation on the basis of a motor current and an actual slip frequency of the motor. From the thus obtained secondary current component, an actual torque produced by the motor is calculated. A frequency reference for the PWM control is obtained by the comparison result of the actual torque and a torque reference. A modulation factor reference for the PWM control is obtained by the comparison of the exciting current component and an exciting current reference. According to this control apparatus, the torque of the induction motor can be controlled to follow the torque reference with a high accuracy.

Abstract: A control system for an M-phase a.c. machine which measures the currents in at least (M-N) phases, where N=2 if M is even and N=1 if M is uneven, measures the instantaneous values of the voltages in (M-N) phases and obtains control signals for alteration of the input voltage and/or current to the motor to maintain the motor in an efficient running condition.

Abstract: An electronic control for a motor drives the motor with pulses of current, and protects the motor from extreme values of line voltage and motor current. A current sensor, connected in series with a conductor which supplies current to the motor windings, develops a monitoring signal that is sensed for the purpose of shutting down the motor when the monitoring signal indicates that the motor current is excessive. A power supply in the control isolates the control from the AC line voltage, provides regulated DC voltages to power various portions of the control, and provides an unregulated DC sense voltage which indicates when the AC line voltage is too high or too low so that the motor can be shut down.

Abstract: A drilling machine comprises an electric drill having a drill motor for rotating an annular drilling tool and a feed control motor for moving the annular drilling tool forward and backward with respect to a workpiece, both connected to an AC power source, and an electromagnetic base for fixing the electric drill on an object to be drilled.

Abstract: In a control system for a power converter for driving induction motors, the control system separately controlling an exciting current component of the primary current of the induction motors contributing to generation of a magnetic flux and a torque current component of the primary current contributing to generation of a torque, a voltage detecting device detects the output voltage of the power converter, and a correcting device responds to the voltage detecting device for determining a current correction for correcting at least one of the exciting current component and the torque current component to reduce the difference of the detected voltage from a reference value of the output voltage.

Abstract: A control system for an induction motor includes a power presumption circuit for presuming an electric energy F.sub.o, which is associated with a reactive power generated in the induction motor, on the basis of the numerical constants including the secondary winding resistance, the actual primary current and the actual rotation speed or angle of the induction motor. The electric energy F.sub.o is used to compensate for the change of the numerical constants of the induction motor, which is caused by the change in temperature.

Abstract: A variable speed motor control system includes a power control circuit and a forced commutation control circuit for controlling the torque and rotational speed respectively of an induction motor. The power control circuit and the forced commutation control circuit are independently controlled by signals from a speed control circuit. An overcurrent sensor monitors the motor current and, if excessive current is detected, a speed and power monitor limits the response of the power control circuit and forced commutation control circuit to the speed command. The forced commutation control circuit and power drive circuit contain silicon-controlled rectifiers both for controlling the amount of power fed to the induction motor as well as for controlling the switching of power between combinations of motor windings.

Abstract: A method for reducing the instantaneous voltage ripple of an electrical drive which is fed by a current intermediary circuit frequency converter with phase sequence quenching. During pulsed operation of asynchronous rotating machinery, driven by a current intermediary circuit frequency converter with phase sequence quenching, an interfering instantaneous voltage ripple occurs due to the inverter minimum time required for the completion of a complete commutation. The operating capacity of the inverter is not imparied, even if the switch-on time of individual thyristors falls below the minimum time. Depending on the degree of incomplete commutation occurring in the process, a difference is made beween one of a "first kind" and one of the "second kind" and, in the case of the second kind, the duration of the actual switch-on pulses for maintaining a linear relationship between the current time area and the nominal pulse duration is advantageously adapted through a correction 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 reduced-order, discrete-time rotor flux estimator for use in a field-oriented induction motor control system utilizing rotor speed as an input.

Abstract: The disclosure is related to a driving arrangement for a drive motor which is provided with an electronic power stage (9) which is controlled by a current controller (13). During the commutation phase, a breakdown of the torque occurs in such drive motors due to the shape of the B-field current, so that the torque has a wavy shape. The torque breakdown can be counteracted by raising the load current in the commutation region. This raising of the load current during the commutation phase is achieved by the provision that the current reference value of the current controller (13) is increased correspondingly by means of an auxiliary voltage at the respective commutation instant.