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: In two embodiments of the present invention, the speed of a DC motor is determined by examining the signal at the negative terminal of the motor. The signal is high-pass-filtered to extract the AC component of the signal. The frequency of this signal is, in almost all cases, proportional to the speed of the motor. This signal is then fed into a comparator, which converts the signal into a square wave, which is then input into a microprocessor. The microprocessor determines the frequency of the square wave. If the frequency of the square wave is below a threshold of acceptable motor speed, the microprocessor can turn off the motor and provide a malfunction indication. If the frequency of the square wave is above a second threshold of acceptable motor speed, the microprocessor can likewise turn off the motor and provide a malfunction indication.

Abstract: A low noise loading motor drive circuit for a camera-integrated camcorder includes a rotation velocity detecting circuit for detecting a rotation number proportional to a velocity signal generated from the loading motor, a velocity signal strengthening amplifying unit for amplifying and strengthening the output signal from the rotation velocity detecting unit, and a velocity to voltage converting unit for converting the output signal from the velocity signal strengthening unit into a voltage inversely proportional to the velocity of loading motor. The circuit also includes a voltage limiting circuit for setting a rotation velocity range limited between a predetermined maximum rotation velocity and a predetermined minimum rotation velocity of loading motor, in a normal rotation made of loading motor. The voltage from velocity to voltage converting unit and the voltage limited output signal from voltage limiting circuit are summed by an adder.

Abstract: A solid state, electric motor control circuit is provided in conjunction with a solid state throttle and vehicle sensor circuit that together incorporate; a Hall Effect throttle position sensor circuit, a throttle position signal amplifier circuit, a vehicle reverse condition circuit, a vehicle operation inhibit circuit, a pulse width modulation circuit, and inverting MOSFET driver circuit, a plurality of power MOSFET devices, a voltage regulator circuit, and a current delivery circuit associated with an external DC electric motor. These circuit elements combine to translate a mechanical throttle position into a voltage level signal that can be converted by pulse width modulation circuitry into a pulsed wave form signal that suitably drives a bank of MOSFET, solid state switches so as to control the flow of current through a DC electric motor.

Abstract: The pulse width modulated DC motor speed control circuit indirectly senses motor current using sense MOSFETs and a peak detector circuit with storage capacitor for deriving an average motor current signal. The average motor current signal is used both in the feedback loop of the pulse width modulated speed control circuit and also in the motor shutoff or clutch circuit. The clutch circuit shuts off power to the motor when a user-settable torque is reached. The motor speed control circuit is therefore adapted for use in hand-held DC power tools such as screwdrivers and nutdrivers which stop rotation at a predefined torque.

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 speed controller for a DC motor minimizes speed droop and load droop through pulse width or frequency modulation. The controller provides an extra power increase upon engine starting or whenever a heavier load is temporarily encountered. The control circuit also has a current limiter, overload indicators, and a battery recharger. The controller is very inexpensive, primarily because all of the timing components are contained on a single integrated circuit timer chip such as a 556 timer. The controller contains other features, including a circuit for limiting the pulse width of the control signal from the pulse width modulator.

Abstract: A control system having proportional and integral functions for controlling the rotational speed of a motor. The system includes a self-limiting integrator for avoiding or limiting integral wrapup, a problem commonly associated with integral control. The self-limiting integrator includes an integrator, limit comparator, OR gate, delay circuit, and sign reversal circuitry. The integrator reverses direction of integration when an error limit is realized. The error limit, a preestablished and adjustable value, can be used to determine the rise and settle time of the speed of the motor independently of the gain.

Abstract: An electric motor control system has a motor driver comprising a bridge of switching elements, a pair of failure detectors, and a microcomputer. The motor driver is connected between a battery and an electric motor that is connected between the switching elements. The switching elements are turned on and off according to drive pulse signals supplied from the microcomputer for supplying a pulsed current to the electric motor. The failure detectors monitor the electric energy supplied to the electric motor to detect a period of time in which the supplied electric energy is free of pulses, and supply a signal indicative of the detected period of time to the microcomputer. Based on the signal from the failure detectors, the microcomputer detects a failure when the detected period of time exceeds a predetermined period of time.

Abstract: A motor controller is programmed for detecting motor-stall condition of a dc motor under the control of a motor control system. The motor control system includes a programmable microcontroller in connection with the motor controller and a motor driver. The motor driver communicates with a dc motor. The dc motor is coupled to a position encoder which encoder is in communication with the microcontroller. The method comprises the steps of providing an average stall threshold value ASV and providing the motor controller with a time counter for counting each time interval T to a maximum count N. The motor controller is programmed to issue a motor command representing the position error between the desired motor position and the actual motor position for some time interval T. During each time interval T, the motor command is compared to the average threshold value ASV, if the motor command is greater than the ASV then the count in the time counter is compared with the maximum count N.

Abstract: A control circuit for controlling a linearly variable speed cooling D.C. fan includes a stator including at least two pairs of main poles, two pairs of auxiliary poles and a Hall effect element provided at either of auxiliary poles. The control circuit also includes a rotor which as a casing, at least two pairs of N and S poles and a plurality of blades. Further, the control circuit includes a driving IC including an amplifier and two switching transistors, a temperature sensor detachable to a connector means, for determining a revolution speed of the D.C. fan that matches to the detected temperature, and a breakdown protection unit provided between said driving IC and said temperature sensor.

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 load of an electronic sewing machine is self-diagonosed by a control system to cause a DC motor to be operated under control to drive upper and lower shafts of the sewing machine. The control system includes an evaluating device to which a voltage value applied to the DC motor and a rotating speed of the DC motor, both detected, are inputted for determining a current value supplied to the DC motor and a power loss of the DC motor. These data are supplied to a fuzzy inference unit for inferring an optimum rotating speed of the DC motor. A control command signal representing an excessive degree of the actual power loss in reference to the rated power loss is outputted from the fuzzy inference unit to the DC motor for the control of the electric power to be supplied thereto.

Abstract: A method of operating bridge circuit for control of an inductive load is disclosed. The bridge circuit has a pair of input terminals for connection across a power source and a pair of output terminals for connection across the inductive load. Each arm of the bridge includes a transistor switch connecting an input terminal with an output terminal. Clamp circuits are connected to each pair of input and output terminals, taking inputs therefrom and responding to a transition through a predetermined voltage differential between the terminals for driving the transistor switch connecting the output terminal to the remaining input terminal, thereby limiting the output terminal to a predetermined voltage level.

Abstract: In a preferred embodiment, a high-frequency, pulse-width-modulated, power-transistor, DC motor speed controller having current limiting in both drive and regenerative modes, essentially constant ramping rates regardless of whether or not the operator switches to neutral before changing direction, a simple sequencer which controls the timing of four functions--both drive and regenerative current measuring circuits and both drive and regenerative transistors, a highly effective transistor filter capacitor arrangement, and circuitry in which the level of regenerative current is used as an input to control the current under which the direction relays switch.

Abstract: An apparatus and method for controlling a motor used for rotating a drill stem is disclosed. Silicon control rectifier based system regulates the power to the motor. A control unit coupled to the SCR regulator and the motor monitors the motor input current, voltage and speed levels. If during operation the motor current exceeds a predetermined value and at the same time the motor voltage or speed falls below a predetermined value, the control unit activates an alarm condition and causes the SCR regulator to controllably ramp down the current supply to the motor and then reduces the motor speed reference.

Abstract: A power loss protection system for use in a system having a spinning momentum wheel and connected to a power bus. The inventive system (10) isolates a protected circuit from the power bus (11) in the event of a system power loss and converts and regulates power taken from the kinetic energy stored in the spinning momentum wheel to a voltage sufficient to maintain operation of the protected circuit. In a most general sense, the inventive system includes a power loss detector (21) for detecting a power loss in the system bus and providing a first signal in response thereto and a regulator (26) for regulating the voltage derived from the momentum wheel energy to the protected circuit in response to the first signal.

Abstract: In a power supply circuit for a motor in which a power source line can be opened and closed by a first opening-closing device, a construction is adopted which has a electrically controllable second opening-closing device connected in parallel to the first opening-closing device, a comparator for comparing the voltage of the motor load side with a predetermined value, a controller for controlling the opening and closing of the second opening-closing device on the basis of a signal from the comparator, and a current limiter device provided in parallel to the second opening-closing device, whereby a rush current when the first opening-closing device is closed can be suppressed to thereby prevent the fluctuation of the source voltage and the deterioration of the contacts of the first opening-closing device.

Abstract: A traction motor drive protection circuit which provides the inverter protection capability of a conventional commutation arrangement, but which limits or eliminates fault currents that stress the internal elements of the alternator and traction machines. A series protection thyristor is connected between a commutation thyristor and the inverter circuit to block motor fault currents, and RC elements are connected in series with the commutation thyristor to limit alternator fault currents. Normal inverter gating is continued in the presence of a fault, to circulate the stored inductive energy and discharge the filter capacitor, providing a "ride-through" operation which is substantially transparent to the traction motor. The RC elements in the commutation circuit not only limit the alternator faul current, and hence the stress on the eommutation thyristor, but also commutate the commutation thyristor to provide automatic reset capability.

Abstract: A low voltage circuit is used to control a high voltage transistor which operates a high voltage motor. A blocking diode and a bootstrap capacitor are used to shift the voltage of the circuit between two levels. The circuit is enabled by inducing a current flow through an input terminal. The current is amplified and applied to a high voltage transistor. The circuit is disabled by termination of the current flow through the input terminal which causes the circuit to rapidly disable current flow through the high voltage transistor. The circuit also disables current flow through the high voltage transistor during voltage transients to prevent erroneous operation during the transients.

Abstract: An electrical stepper motor system is provided in which a microcomputer controlled driver monitors the real time operating parameters of the stepper motor. The driver is controlled by the microcomputer to keep the real time operating parameters of the motor in a range that is governed by limiting parameters. The limiting parameters are determined by the microcomputer on a moment by moment basis in response to changes in certain conditions occurring within the stepper motor, as well as in the outside operating environment. The microcomputer compares the microcomputer determined safe operating parameters with any user stipulated operating parameters, stored in the storage means of the microcomputer, to determine limiting parameters on a moment by moment basis. An encoder senses the position and velocity of the motor and provides appropriate status signals to enable the driver to compensate for position and velocity errors of the stepper motor.

Abstract: A control circuit for connecting a load to a voltage source includes an electronic holding circuit having latched and unlatched states. When latched, the electronic holding circuit connects the load to the voltage source. A thermal device responsive to excessive current demand by the load automatically places the holding circuit in its unlatched state, and disconnects the load from the voltage source.

Abstract: A device and associated method to control the electromechanical energy conversion process of a variable speed drive utilizing a doubly fed machine, which provides the mechanical energy as demanded by some mechanical load. Alternatively, a device and associated method is provided for a synchronous motor. The terminals of either the stator or rotor winding of the doubly fed machine are directly connected to a polyphase AC power grid of a certain grid frequency. The device establishes through electronic control a stable operation of the drive at a desired power factor at the terminals of these windings, irrespective of varying load conditions. This capability is provided without the need for computing or sensing this desired power factor and the subsequent feedback of its deviation from the desired value through a properly designed regulator.

Abstract: An adjustable frequency motor drive system for a hoist is disclosed in which the frequency of the power supply to the motor can be selectively varied and the speed of the motor will follow the varying frequency at a slip speed relative to the frequency. The slip speed of the motor may not exceed a value beyond which the motor can control the hoist load. Accordingly, a frequency value based on the frequency of the power supply to the motor is selected as the frequency which is not to be exceeded by the motor speed expressed as a frequency. Signals representative of the actual motor speed and the selected frequency value are compared and, if the signal representative of the motor speed exceeds the signal representative of the frequency value which is not to be exceeded, an output signal is produced which may be used to apply a brake which stops and holds the motor and hoist and thereby maintains the load suspended.

Abstract: An A.C. solid state power controller for controlling the current through a load from an alternating current source, including a diode bridge rectifier with its direct current output connected to a solid state switch, such as a MOSFET or a bipolar transistor, that is gate controlled by gate signals synchronized to the A.C. source. The gate signals are provided from an optocoupler to control the solid state switch and the load current. Overload, short circuit, and low A.C. line voltage conditions are sensed by protection circuits which signal the optocoupler to turn off the solid state switch and, thus, the load current. A fast turn off time, in the range of a few microseconds, is achieved which, together with the rectifier and solid state switch configuration, provides a power controller which is resistant to short circuit and overload destruction present in conventional A.C. solid state circuit breakers and power control devices.

Abstract: A pulse width modulation control circuit includes a pulse width modulator which supplies a signal to a power switch tying together a d.c. signal generator and a motor and various sensing circuit including a control voltage disabler circuit, a motor voltage and current feedback circuit, and a low control voltage disabler circuit. All of the sensing circuits are appropriately designed to ensure that the various components of the circuit are not damaged under abnormal conditions whether due to motor loads heavier than rated or undesired changes in a.c. current input or control voltages.

Abstract: A controller for a batter-drive DC motor controls the average motor current by switching a series-connected FET on and off with a pulse-width-modulated gate signal. Motor speed is changed by chaning the duty cycle of the signl, which is generated by an oscillator. An undervoltage protection circuit senses the battery voltage and compares it with a reference system that has hysteresis. An overload protection circuit senses the motor current, integrates the sensed signal, and comprares the result with a Zener reference diode that is connected in an amplifier circuit for positive feedback. The oscillators's pulse-width-modulated output, the undervoltage protection circuits's output, and the overload protection circuit's output are input to a "NOR" Logic gate, whose output drives the gate of the FET.

Abstract: A circuit for controlling the speed of a subfractional horsepower DC motor has a driver stage with a switch that interrupts the motor current in repeated succession so that a pulse-like current is provided, and the motor EMF is sampled synchronously with the motor current interruption, with the sampled value being supplied to a comparator wherein it is compared to a rated value. The output of the comparator is used to control the driver stage which includes the switch. Two pulse duration modulators are provided which respectively independently control the motor current and voltage. The pulse duration modulator which controls the current generates pulse pauses which are always sufficiently long to permit the EMF measurement to be completed. The pulse duration modulator operates at a frequency above the audible frequency range so that its pulse pauses are short enough to prevent the motor current from noticeably failing or being completely interrupted.

Abstract: A controller for a battery-driven DC motor controls the average motor current by switching a series-connected FET on and off with a pulse-width-modulated gate signal. Motor speed is changed by changing the duty cycle of the signal, which is generated by an oscillator. An undervoltage protection circuit senses the battery voltage and compares it with a reference system that has hysteresis. An overload protection circuit senses the motor current, integrates the sensed signal, and compares the result with a Zener reference diode that is connected in an amplifier circuit for positive feedback. The oscillator's pulse-width-modulated output, the undervoltage protection circuit's output, and the overload protection circuit's output are input to a "NOR" logic gate, whose output drives the gate of the FET.

Abstract: The method uses at least one power switch having "on" and "off" states for providing, respectively, low and high impedance paths between an inductive load and a source of power and thereby controls current flow through the inductive load during a sequence of regular reoccurring time periods. The at least one power switch is switched, if in the "off" state, to the "on" state substantially at the beginning of at least some of the time periods. The method is operative during any one of a plurality of the "on" duty periods and switches the at least one power switch from the "on" state to the "off" state when a predetermined level of current flow has been reached in one of the inductive load and the at least on power switch, and switches the at least one power switch back to the "on" state independent of the occurrence of the beginning of a time period.

Abstract: A current limiting control circuit for a d.c. motor, wherein compensation is provided for the inherent voltage drop across the armature of the d.c. motor with a first dedicated amplifier, while a second dedicated amplifier provides current limit control. In providing a separate and dedicated amplifier for the current limiting function, the limitations inherent in the current/resistance compensation circuit, such as lag in response time, are avoided.

Abstract: An electronic control for regulating the operation of a two-speed motor in a heat transfer system such as a heat pump or air conditioner. The control receives high and low demand signals from a thermostat and a motor unit operates at high and low speeds in response to, respectively, high and low speed signals. The control includes an initial timer, high and low speed operators, and a speed change delay. The initial timer detects the occurrence of a demand signal from the thermostat, counts a predetermined period of time, and responsively issues an initial timing completion signal. The high and low speed operators detect the timing completion signal as well as either a high or low thermostat demand signal. One of the operators then responsively issues either a high or low speed signal to the motor unit. The motor unit accordingly operates at a high or low speed. The speed change delay detects the change in a thermostat demand signal from a high to a low state or a low to a high state.

Abstract: There is provided a continuous flow type homogenizer. The homogenizer comprises, a tubular container having at upper end thereof an inlet for introducing tissue to be homogenized and at lower end thereof an outlet for discharging the homogenized tissue, a pestle disposed freely rotatable in the tubular container with a clearance defined between the inner surface of the tubular container and the peripheral surface of the pestle, a rotation shaft driving means connected to a rotation shaft of the pestle, a speed setting means for setting the rotation speed of the pestle, and a speed controlling means for controlling the speed of the rotation shaft with a predetermined speed gradient with respect to a speed value set by the speed setting means.

Abstract: A control circuit for adjusting current to a direct current motor that has a free wheeling diode connected in parallel with the armature winding includes a controllable switching element connected in series with the armature winding, a comparator that has a control voltage corresponding to a desired rotational speed of the motor applied to one input of the comparator and an integrating circuit connected to the other input of the comparator. An electronic switch is connected across the integrating circuit, and the output of the comparator controls the controllable switching element and the electronic switch.

Abstract: A digital servo system comprising source means of a clock signal, counter means, latch means which latches a predetermined lower bits of the output of the counter means, means for obtaining a servo control output in response to the latch means, and sequencer means which is applied with a digital data of which the pulse interval or the phase is processed, and controls passing or nonpassing of the clock signal to the counter means in response to the digital data and obtains a latch pulse for the latch device.

Abstract: An apparatus and method of protecting a centrifuge from rotor overspeed and resultant mishap by computation of the rotor moment of inertia is disclosed. In the preferred embodiment, a centrifuge is driven by a rotor mounted on a shaft which shaft is in turn driven by a constant current motor. A tachometer for detecting angular velocity of the drive shaft is used. A desired and ultimate centrifuge operating speed is selected by the operator. The times at which the rotor passes through discrete speeds are recorded and from the time difference the moment of inertia is computed. The moment of inertia can thereafter be utilized to discretely identify or "finger print" rotors to disqualify certain rotors from use in particular centrifuge protocols and establish gross limits of centrifuge operating speed.