Thyristor power control circuit with damping circuit maintaining thyristor holding current

A thyristor power control circuit, comprising:

• a thyristor operable to receive an input AC voltage, the thyristor responsive to a gate pulse generating a modified AC voltage;
• a rectifier operable to receive the modified AC voltage and generate a rectified DC voltage between a first output node and a second output node;
• a power converter operable to receive the rectified DC voltage and generate a controlled output current, the power converter having a first input node and a second input node;
• and
• a damping circuit coupled between the first and second output nodes and the first and second input nodes, the damping circuit having a damping resistor operable to maintain a holding current in the thyristor during an ON period of the thyristor, wherein the resistor is directly connected between the first output node and the first input node, and further including a direct connection between the second output node and the second input node, and still further including a capacitor directly connected between the first input node and second input node.

A thyristor power control circuit, comprising:

• a thyristor operable to receive an input AC voltage, the thyristor responsive to a gate pulse generating a modified AC voltage;
• a rectifier operable to receive the modified AC voltage and generate a rectified DC voltage;
• a power converter operable to receive the rectified DC voltage and generate a controlled output current;
• an input filter coupled to the thyristor, the input filter having a common mode choke with first and second windings, the input filter configured to prevent electromagnetic interference (EMI) from leaving the power converter;
• and
• a first damping resistor coupled in parallel to the first winding and a second damping resistor coupled in parallel to the second winding, the first and second damping resistors being configured to maintain holding current in the thyristor.

A thyristor power control circuit, comprising:

• a thyristor operable to receive an input AC voltage, the thyristor responsive to a gate pulse generating a modified AC voltage;
• a rectifier operable to receive the modified AC voltage and generate a rectified DC voltage;
• a power converter operable to receive the rectified DC voltage and generate a controlled output current;
• and
• a damping circuit coupled to an output of the rectifier, the damping circuit having a damping resistor and a first capacitor connected in series, the damping circuit having a diode connected in parallel to the damping resistor to enable the first capacitor to discharge without power loss at the damping resistor, the damping circuit configured to maintain a holding current in the thryristor during an ON period of the thyristor.