Dynamic braking control

Claim 2

A control system for controlling dynamic braking of a dc motor, comprising, in combination, a dc motor including an armature and a field winding, excitation means for separately exciting said field winding of the dc motor, first sensor means for sensing a current flowing through said field winding to derive a first electrical quantity representative of the sensed magnitude of the current, second sensor means for sensing a voltage induced across said armature to derive a second electrical quantity representative of the sensed magnitude of the voltage, a adder means connected to said first and second sensor means to form the sum of said first and second electrical quantities, field regulator means electrically coupled to said adder means to control said excitation means to regulate the current flowing through said field winding to maintain the sum of said first and second electrical quantities from said adder means constant, and said second sensor means comprising means to derive an electrical quantity representative of a sensed magnitude of a rotational speed of the dc motor.

Claim 3

A control circuit for controlling dynamic braking of a dc motor comprising, means connected in use to a dc motor for operating in a dynamic braking mode, means to develop a signal proportional to field winding current of the dc motor, means to develop a signal proportional to an armature current of the dc motor, means to add the two signals comprator means to compare the added two signals with a reference signal and develop a deviation signal corresponding to the difference between the reference signal and the two added signals, excitation means, a field regulator connected to said excitation means receptive of the deviation signal varying the field current to maintain the sum of the added signals equal to the reference signal thereby to maintain the dynamic braking force constant as the speed of the armature reduces by maintaining the armature current from reducing as the speed reduces.

Claim 4

A control circuit for controlling dynamic braking of a dc motor comprising, means connected in use to a dc motor for operating in a dynamic braking mode, means to develop a signal proportional to field winding current of the dc motor, means to develop a signal proportional to an armature current of the dc motor, means to add the two signals comprator means to compare the added two signals with a reference signal and develop a deviation signal corresponding to the difference between the reference signal and the two added signals, excitation means, a field regulator connected to said excitation means receptive of the deviation signal varying the field current to maintain the sum of the added signals equal to the reference signal thereby to maintain the dynamic braking force constant as the speed of the armature reduces by maintaining the armature current from reducing as the speed reduces.

Claim 5

A control circuit according to claim 2, in which said excitation means comprises means to increase the field current as the revolutions per unit time of the armature decrease thereby to maintain the braking force constant.

Claim 6

A control circuit according to claim 3, in which the last mentioned means comprises thyristors connected in operation to the field winding of the motor, said excitation means including a power source connected to the thyristors, and said field regulator connected to control the conduction period of said thyristors for controlling energization to the field winding as a function of the difference between the deviation signal and reference signal.

Claim 7

A control circuIt according to claim 4, including thyristor means for controlling armature current to increase it when a decrease of the speed of rotation of the armature occurs.

Claim 8

A control system for controlling dynamic braking of a dc motor, comprising, in combination, a dc motor including an armature and a field winding, excitation means for separately exciting said field winding of the dc motor, first sensor means for sensing a current flowing through said field winding to derive a first electrical quantity representative of the sensed magnitude of the current, second sensor means for sensing a voltage induced across said armature to derive a second electrical quantity representative of the sensed magnitude of the voltage, an adder means connected to said first and second sensor means to form the sum of said first and second electrical quantities, field regulator means electrically coupled to said adder means to control said excitation means to regulate the current flowing through said first and second electrical quantities from said adder means constant, said second sensor means comprising means to derive electrical quantity representative of a sensed magnitude of an armature current, a resistor and a thyristor connected in a circuit with said armature, said resistor limiting the armature current, said thyristor being responsive to a deviation of the output from said adder means from a reference magnitude therefor to be conducting to shortcircuit said resistor.

Claim 9

A control system for controlling dynamic braking of a dc motor, comprising, in combination, a dc motor including an armature and a field winding, excitation means for separately exciting said field winding of the dc motor, first sensor means for sensing a current flowing through said field winding to derive a first electrical quantity representative of the sensed magnitude of the current, second sensor means for sensing a voltage induced across said armature to derive a second electrical quantity representative of the sensed magnitude of the voltage, an adder means connected to said first and second sensor means to form the sum of said first and second electrical quantities, field regulator means electrically coupled to said adder means to control said excitation means to regulate the current flowing through said first and second electrical quantities from said adder means constant, said second sensor means comprising means to derive electrical quantity representative of a sensed magnitude of an armature current, a resistor and a thyristor connected in a circuit with said armature, said resistor limiting the armature current, said thyristor being responsive to a deviation of the output from said adder means from a reference magnitude therefor to be conducting to shortcircuit said resistor.