Abstract: The invention is for the electronic control of the sway of a suspended load from a crane. The natural frequency .omega..sub.n of a simple pendulum is used to estimate the velocity and displacement of the suspended load, and a signal representative of measured load displacement is used to drive the estimated load displacement to the measured load displacement and modify the estimated velocity.

Abstract: A method for developing current control signals from motor terminal voltage in the control of alternating current electric motors which utilize electric current control signals oriented to the phase of a flux component in a rotating field for applying current so as to control the flux and torque in the motor. The method includes developing flux signals from measurement of motor terminal voltage and integrating those signals to develop corresponding flux signals. In one form, the method eliminates DC components occuring in the resultant flux signals by locating local maxima and minima of the resultant flux signal and correcting the value of the flux integrator so as to provide maxima and minima flux signals having equal absolute values. The method also includes establishing an initial flux in the motor prior to startup which is oriented in a predetermined manner such that initial current applied to the motor can be applied so as to immediately develop torque, if required.

Abstract: A method for supplying the excitation to a four quadrant drive DC electric motor having a forward and reverse controllable bridge rectifier power regulators for controlling the direction of motor rotation. The motor control system is capable of operating in a continuous and discontinuous current mode of operation and includes an electronic control circuit for calculating a firing angle from desired and measured system parameters.The electronic control system includes a reversing controller for developing a current command for generating firing pulses to fire selected switching elements in the power regulators for controlling the magnitude and polarity of the excitation, and a current sensor for sensing motor current. The method provides a smooth, continuous transitioning between the forward and reverse bridge in response to a sensed requirement for reversing excitation to the motor.

Abstract: An automated SCR cell test exercises each of the twelve SCRs in a dual, 3 phase, full wave SCR rectifier bridge singly to detect shorted SCRs and in pairs to detect open SCRs or faulty gate circuits.

Abstract: A variable speed a-c drive motor is controlled by a current feedback pulse width modulation scheme which effectively isolates the controlled motor current from variations in the input d-c voltage. An additional control loop is provided to superimpose a control signal on the amplitude command input circuit of the pulse width modulation control scheme. The additional loop responds to line current and particularly line current resonance between the input d-c filter and the line inductance. Instantaneous line current is then maintained at the minimum required to support instantaneous power flow to the a-c motor so that resonance current is suppressed.

Abstract: A motor control system including sequencing circuitry for governing the mode of operation of an electric motor in accordance with feedback signals representing selected motor operating parameters further includes modifying circuitry to selectively effect a change in the mode of motor operation in response to an external signal.

Abstract: A circuit for detecting the conductive state of a semiconductor device (e.g., a thyristor) which exhibits a substantial terminal to terminal voltage difference between its conducting and nonconducting states and which utilizes a gating signal to render the device conductive includes a bistable circuit (e.g., a flip-flop) which is placed into a first stable state with the occurrence of the gating signal. A voltage sensing circuit disposed across the semiconductor device is utilized to develop an additional signal which is applied to the bistable circuit to thereby place that latter circuit into its second stable state. The state of the bistable circuit is representative of the conductive state of the semiconductor device.

Abstract: A motor drive system having a direct current, shunt motor utilized in a web coiling operation and operated in a tension control mode includes circuitry to automatically provide compensation for inertial effects of the drive and the web coil during periods of acceleration and deceleration.