Abstract: In a motor drive circuit, the collector-emitter paths of two npn-type transistors are connected in series between a power line and ground, and the junction between the two transistors is connected to a motor coil. A control circuit feeds a control current to the base of the transistor connected to the power line so that this transistor supplies a drive current to the motor coil. A current mirror circuit is provided which is constituted of two pnp-type transistors whose emitters are connected to the power line, and the base and collector of the input-side transistor is connected to the control circuit through a diode. The base of another pnp-type transistor is connected to the cathode of the diode, and the emitter of this transistor is connected to the collector of the output-side transistor of the current mirror circuit and to the base of the transistor connected to the power line.

Abstract: A control system (100) for a five-phase brushless DC motor (102) including a stator having five windings and a rotor (116) mounted for rotation relative to the windings (114). The windings (114) are adapted to be electronically commutated in response to the rotary position of the rotor (116). The control system (100) includes a sensing circuit (106) to sense the rotary position of the rotor (116) using an optical or magnetic sensor or the back electromotive force voltages in the windings (114). Electronic switches (112) control the flow of current through the windings (114) in response to control signals generated by a control circuit (110) in response to the rotary position of the rotor (116). The control circuit (110) includes start-up logic to start the motor (102).

Abstract: A control apparatus for conducting a variable speed control of an AC motor by controlling an M-axis component and a T-axis component of a current flowing through the AC motor.

Abstract: An improved apparatus for generating a magnetic flux of an induction motor, which is capable of more accurately generating a magnetic flux by operating a rotational coordinate system-based current and a phase of a magnetic flux for generating a reference magnetic flux, compensating a magnetic error value which is referred to a difference value between a reference magnetic flux and a really generated magnetic flux, which includes a stator magnetic flux generator for outputting a stator magnetic flux by operating a current of an inputted static coordinate system, a voltage of a static coordinate system, and a compensation voltage; a rotor magnetic flux generator for outputting a rotor magnetic flux by operating a current of a static coordinate system inputted to the stator magnetic flux generator and a stator magnetic flux outputted to the stator magnetic flux generator; a reference magnetic flux generator for outputting a reference magnetic flux by operating a current of an inputted rotational coordinate syste

Abstract: An asynchronous motor is supplied with power from an AC line voltage via a variable speed drive including a rectifier bridge connected to the AC line voltage, a DC voltage intermediate circuit including a capacitor and an inverter including switches and connected to the phase windings of the motor. A system for controlling the power supply to the motor includes a device for controlled resumption of motor speed after supply of power to the motor is interrupted.

Abstract: An apparatus for driving an AC motor at variable speeds facilitates arbitrary setting or adjustment of equivalent primary resistance of an AC motor. In one embodiment of the present invention, a reference AC voltage generator outputs reference AC voltage values for each phase of the AC motor, and signals derived from the reference voltage values are in turn used by a power converter to supply the AC motor with variable voltage and frequency. In this embodiment, two or more phase currents are fed back to, and subtracted from, the reference voltage values via a regulator. In another embodiment, an angular-frequency/biaxial-reference-voltage value generator generates a reference primary angular frequency value and biaxial reference voltage values of the AC motor in a rotating orthogonal coordinate system. In this embodiment, two or more of the AC motor's phase currents are fed back to, and subtracted from, the biaxial reference voltage values via a vector transformer and a regulator.

Abstract: Power is provided to the stator windings of an AC induction machine which includes a component at the fundamental drive frequency for the machine and a superimposed signal component which is at a substantially higher frequency than the drive power. The fundamental drive power is provided at a level which results in saturation in the stator which follows the magnetic flux vector. The stator response at the signal frequency is then detected to provide a correlation between the response at the signal frequency and the magnetic flux vector position. The detection of the response at the signal frequency is preferably carried out by a heterodyne detection process, by mixing signals at the signal frequency with the measured stator currents, and filtering the mixed signals to isolate the signal indicative of the flux vector position.

Abstract: The invention relates to a method for braking an alternating-current motor when the alternating-current motor (1) is supplied by a frequency converter (4) comprising an intermediate circuit (2). In accordance with the invention, when the voltage (uc) of the intermediate circuit (4) reaches a predetermined value during braking, the magnetization of the motor (1) is increased to increase the thermal losses of the motor, and, once the voltage (uc) of the intermediate circuit drops below said predetermined value, the increased magnetization is removed.

Abstract: A variable speed control for induction motors with a primary angular frequency operating circuit has a multiplier that multiplies the output of a first regulator by a variable responsive to magnetic flux intensity. This first regulator holds the M axis induced voltage at zero. The primary angular frequency operating circuit corrects the primary angular frequency command value based on the output of the multiplier. An adder adds the output of a second regulator circuit and the output of the primary angular frequency operating circuit. The second regulator regulates (by proportional or proportional-integral control) the deviation between the command value of the torque current, or the torque and an actual value, to zero. In another embodiment, the magnetic flux operating circuit calculates a first value and a second value.

Abstract: The invention relates to a method of determining rotational speed, size and instantaneous direction of a residual flux of an inverter-supplied squirrel cage induction machine, to be used for starting the squirrel cage induction machine when there is a rotating residual flux (.PSI..sub.s) in the machine (1) and a total leakage inductance (.sigma.L.sub.s) of the machine is known. According to the invention measures are taken, comprising steps of short-circuiting stator windings; measuring a first stator current vector (i.sub.s1) and switching off the stator circuit at the end of a first time period (T.sub.1); short-circuiting the stator windings once more after a second time period (T.sub.2) from the end of the first time period (T.sub.1); measuring a second stator current vector (i.sub.s2) and switching off the stator circuit after a time identical with the first time period (T.sub.1) from the second short-circuiting; determining the frequency (.PSI..sub.s) of the residual flux (.omega..sub.

Abstract: A vector controlling method and apparatus for an induction motor is disclosed in which a rotator magnetic flux is reliably obtained by using a newly deduced equation. The apparatus includes a rotator magnetic calculator and does not require a tachogenerator so that the rotator magnetic flux can be obtained by calculation.

Abstract: A vector control unit that has an inverter connected with an induction motor which is not only electrically driven but is also being operated in a regenerative condition. The vector control unit comprises a detection circuit for detecting that the induction motor is being operated at a low speed and for detecting that signs of a rotor electrical angular velocity command and a slip angular velocity command differ from each other, and a control circuit for performing control such that the slip angular velocity command is not included in the angular velocity command when the induction motor is being operated at low speed and the signs of the rotor electrical angular velocity command and the slip angular velocity command differ from each other.

Abstract: The control for an AC inverter includes a low voltage microcontroller referenced to ground potential and a waveform generator coupled to the microcontroller through a serial data link including optical isolation devices. The waveform generator floats at the negative bus potential of the DC source for the inverter. The waveform generator produces switching signals for the inverter under control of the microcomputer. The waveform generator, serial communications circuitry and other support circuits are all part of a single application specific integrated circuit.

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.