Abstract: A motor control system for controlling operation of an electric motor associated with a motor-operated vent in a vehicle. The system monitors and stores data relating to the operating current and detects occurrences of abnormal loads applied to the vent by determining whether the monitored operating current exceeds one of several predetermined thresholds. The predetermined thresholds are dynamically modified in accordance with monitored condition variations of the operating current. The dynamically modified thresholds are initially based on either a value associated with the stall current of the vent motor or the start spike current of the vent motor. In addition, an embodiment is provided for monitoring and storing data relating to ripple current waves associated with the operating current, so that occurrences of abnormal loads may be detected by determining whether the frequency of the monitored ripple current waves is less than a predetermined value.

Abstract: A motor control system accurately and reliably controls the speed of a motor so that the motor operates in accordance with a predetermined motor speed profile, and therefore does not exceed a predetermined safe speed, decelerates at a controlled rate, maintains a safe minimum speed, and does not turn in reverse. If the motor operates out of these limits, a malfunction is indicated and the control system halts operation of the motor. The motor speed is determined using an electronic tachometer that analyzes the current in at least two phases of the motor to provide extremely precise and reliable velocity information for the motor.

Abstract: A memory mirror system having a mirror 19, two constant speed motors 16,18 each controlling an axis of mirror movement, position feedback signals 26,28 from each motor, switch inputs 12, a diagnostic push button 40, and an electronic controller 10, is provided with a diagnostic procedure after a self-test push button 40 has been depressed by automatically driving the mirror to the center of movement when manual movement is not requested, thereby allowing system level failures, such as position feedback sensor failures, to be detected quickly by visual inspection of mirror movement as the mirror attemps to return to the origin, without altering existing memory settings or disconnecting the controller 10 from the system. When manual movement is not requested for a predetermined period of time, the diagnostic procedure is prevented from running.

Abstract: In a circuit arrangement for the timed control of semiconductor switches (1-4) to each of which a freerunning diode (D1-D4) is connected in parallel and which are arranged in branches of a bridge, an ohmic-inductive load (5) of low loss power which lies in the diagonals of the bridge is to be acted on by a controlled average current value. For this purpose two semiconductor switches (for instance 1, 4) lying diagonally opposite each other in the bridge are closed in a current-application phase while in the following freerunning phase a freerunning current flows through the load. For the reduction of the loss power, at the start of the freerunning phase only one (1) of the two diagonally opposite semiconductors (1,4) is opened and a semiconductor switch (3) which lies in the bridge alongside the conductive semiconductor switch (4) is then closed.

Abstract: The invention provides a speed controller which detects the period of an AC signal containing information of the rotational speed of a motor and controls the rotational speed based on the detected period value and a reference speed value. More particularly, the speed controller computes the amount of the deviation of the AC signal based on continuously detected period values and the reference speed value, and then stores the computed deviation amount in a memory as a correction value. Using the correction value stored in the memory, the speed controller corrects the deviation of the period, and thus, the speed of the rotation of the motor can be controlled with extremely high precision.

Abstract: The speed of a DC motor is stabilized to correspond to a reference speed by a motor driving control that is instantaneously responsive to the interval between reference pulses corresponding to the reference speed and actual observed pulses corresponding to the actual motor speed.

Abstract: A circuit for speed monitoring, particularly for fan drives. A detection device for producing an input signal sequence is provided which has a speed-dependent repetition frequency. The circuit also has a signal converter for converting the input signal sequence into an output signal whose amplitude is a function of the repetition frequency of the input signal sequence. There is also an evaluation circuit, having at least one threshold value element responsive to the output signal of the signal converter and which responds if the output signal amplitude reaches a value corresponding to a drop below a predetermined minimum speed or a rise above a predetermined maximum speed.