General Electric Company

George S Chambers

Carter Sinclair

Lawrence J Lane

L Jubin Lane

In association with a polyphase hybrid rectifying bridge having controlled rectifiers, there is employed, in addition to the normal means for controlling the firing time of the controlled rectifiers, additional circuitry for preventing or at least reducing the probability of the occurrence of a commutation fault. This is achieved by first producing a timing signal which is representative of the time intervals during which a voltage exists across a load being supplied by the bridge and by then combining the timing signal with a basic reference signal representing a minimum time period during which this voltage should exist to guard against a commutation failure of the controlled rectifiers. When a prescribed relationship exists between the timing signal and the basic reference signal, the normal control means is overridden and the firing angle of the controlled rectifiers is advanced to a point which will guarantee commutation. In addition, there is further provided an optional feature which facilitates recovery of the bridge in the event a commutation failure does occur. This feature takes the form of a recovery circuit which, in response to a sensing of an unbalance in the alternating voltage supplying the bridge, outputs a signal which also causes an advance in the firing angle of the controlled rectifiers.

Polyphase hybrid rectifying bridge with commutation fault protection

In association with a polyphase rectifying bridge having controlled rectifiers there is employed, in addition to the normal means for controlling the firing time of the controlled rectifiers, additional circuitry for preventing the occurrence of a commutation fault. This is achieved by first producing a timing signal representative of the time intervals during which a commutation between successively fired controlled rectifiers of the bridge actually exist. This timing signal, after being properly shaped is combined with a basic reference signal representative of a predetermined value to which the rectifiers may be phased back in their firing angle without resulting in a commutation failure. Stated in another way, the width of the existing commutation period serves to set a minimum to which the next commutation period must conform. When the prescribed relationships exist between the timing signal and the basic reference signal, the normal control means is overriden and the firing angle of the controlled rectifier is advanced to a point which will insure commutation.

Polyphase rectifying bridge with commutation fault protection

An electronic filter circuit comprised of summing circuits and integrating circuits is interconnected such that the filter may use the same components to serve either as a band-reject or a band-pass filter having the same natural frequency. Changing of the filter operation between the two modes is accomplished simply by the interchange of two component values.

Active filter with inverse option

In a power system, control signals derived from a measurement of dynamoelectric machine output voltage and current are selectively applied to an exciter to control the current in a field winding of the machine to control the machine reactive volt-amperes and output voltage.

Regulator for controlling synchronous dynamoelectric machines

A generating system employing a generator having a self-excited field winding the excitation of which is achieved by supplying a bridge circuit with signals which are, respectively, proportional to the generator terminal voltage and the load current further includes means to selectively short-circuit the field winding during each cycle of normal generator operation. The system further includes a feedback path or loop for controlling the time during which the field winding is short-circuited which feedback path develops a control signal by comparing a signal representing the voltage supplied to the bridge circuit with a reference signal to develop an error signal which is then modified by a further signal proportional to the Thevenin equivalent voltage of the bridge circuit to thus linearize the feedback loop.

Generator control system

An adaptive filter circuit using a time modulated dead band for suppressing the effects of spurious noise associated with an error signal used in controlling a position drive motor associated with process controlling elements. The circuit includes means for restricting all signals, including both control signals and spurious noise, to a positioning motor during those periods of operation when little positioning is required. However, in those instances where a relatively large amount of repositioning is required, the system provides means for switching to a nonrestrictive mode of filtering which thereby permits maximum control over motor operation.

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Waynesboro, VA, United States of America

George S Chambers