Abstract: The drive circuit operates a shaded pole motor having in the disclosed embodiment three windings of turns N, N/2 and N/2. The control is basically two-speed control with the lower speed operation being adjustable by means of the drive circuit and with the high speed operation being directly from the AC line. The drive circuit includes a clock, frequency adjustment means, power inverters and unilateral means for limiting power consumption.

Abstract: Equipment for the electronic speed control of an induction-type motor such as the drive motor for a tape recorder, comprises a tachogenerator fixed to the shaft of the motor and operating a pulse generator that has two outputs. A saw-tooth generator has two inputs and one output, one of the inputs of the saw-tooth generator being a start input and the other being a control input. The start input is coupled to the pulse generator, as is also the control input. The latter output of the pulse generator is connected to the control input of the saw-tooth generator and also to the control input of at least one sampling stage. The output of the saw-tooth generator is connected to a dc amplifier, which is in turn connected to the signal input of the sampling stage. The output of the sampling stage is connected to a grounded capacitor and also the the control input of the driver stage.

Abstract: The rotor speed of a three phase induction motor is detected by a two channel pulse tachometer, which generates per revolution of the rotor 384 signals that are summed with a slip rate command signal in the first of two successive digital counters. The counters divide the 384 signals/revolutions by 192, thereby producing a four bit counter output which cycles twice per revolution of the rotor. The four bit output is decoded by a read-only memory which produces six output signals each half revolution of the rotor. The read-only output signals are applied to an inverter circuit which controls the gating of the SCR's in the lines of the stator winding of the motor. Gating circuits associated with the counters prevent undesirable simultaneous triggering of count up and down terminals, respectively, on the counters. Also balanced choke coils are employed in two of the stator winding leads between the inverter and the rectifier which supplies DC current to the inverter-controlled SCR's.

Abstract: A variable speed ac motor drive such as a controlled current inverter drive with load angle control generates an inverter frequency command signal which at low speed has a large ripple component and a small dc component representing the desired frequency. A variable frequency oscillator is responsive only to the dc component and supplies timing pulses to a ring counter which generates thyristor gating signals in the forward and reverse phase sequence. Smooth reversing over a wide range of torque is realized, and multipulse operation is inherent at low speeds to modulate the inverter output and minimize cogging torque.

Abstract: In a control system of an alternating current motor energized by serially connected rectifier and inverter wherein the output DC voltage of the rectifier is controlled by a phase controller which is controlled by a phase control signal and the output frequency of the inverter is controlled by a speed reference signal there is provided a power factor detector which differentiates the phase control signal or the DC voltage and the output of the phase detector is added to the speed reference signal so as to suppress low frequency oscillations of the torque of the motor.

Abstract: A motor drive apparatus has G groups (G.gtoreq.2) of m-phases inverter units and G groups (G.gtoreq.2) of m-phases AC windings for feeding through the m-phases inverter units to the m-phases AC windings and G groups (G.gtoreq.2) of DC power sources which are connected to G groups of the inverter units so as to form alternative series closed loops on the DC circuit.

Abstract: The invention relates to a DC control circuit for controlling the speed and rotary direction of a three-phase asynchronous motor. The circuit has an inverter section having three branches with a pair of switch elements in series in each of the branches. The inverter section has a common extinguishing switch element in shunt with the three branches. A speed determining frequency generator is responsive to the voltage of the DC supply and an ignition signal generator for operating the inverter switch elements is driven by the frequency generator. An extinction signal generator for operating the common extinguishing switch element is also driven by the frequency generator. A reversing circuit section between the ignition signal generator and the inverter branches has two states for exchanging the control lines of the inverter switch elements in at least two of the branches.

Abstract: A system for driving an inductor type synchronous motor for minute control includes an inductor type synchronous motor having first means for driving m numbers of phases and a group of first magnetic teeth, second means equipped with a group of second magnetic teeth; and power feed equipment for feeding power to the driving windings of the individual phases; wherein the minute control characterized by the electrical resolution number R per electrical angle 2m (2m being one fundamental cycle) of the power feed equipment is larger than 3 m points (R.sub.2 3 m) or is stepless; and the power feed equipment feeds electric-waves of current or voltage to the driving windings, the electric-waves being trigonometric functional patterns formed by a control means of the power feed equipment.

Abstract: Two transistors each have their emitter-collector circuits coupled in series between one end of a motor field winding and the opposite terminals of a D.C. voltage source to switch current flow in either direction through the winding. Two current sensors are provided, one coupled in series with each emitter-collector circuit. The voltage developed across each current sensor is applied through a driver circuit to the base of the other transistor so as to cut one transistor off when the other is conducting and vice versa, thereby eliminating the possibility of having both transistors conduct simultaneously which would short out the voltage source and burn out one or both transistors.