D-C Regulator circuit

In a d-c regulator circuit for supplying power from a power supply to a load, said regulator having first and second supply terminals for connecting to the power supply and first and second load terminals for connecting to the load, a line coupling the second load terminal to the second supply terminal, comprising:

• a controlled main valve coupling the first supply terminal and the first load terminal;
• a quenching branch coupled between said first supply terminal and first load terminal in parallel with said main valve and including a controlled commutating valve poled to conduct current in the same direction as said controlled main valve, and a commutating capacitor in series with the commutating valve having a lead coupled to said first load terminal;
• a reversing branch coupled in series with said commutating valve and in parallel with said commutating cpacitor and including a controlled reversing valve poled in the forward direction of said commutating valve, and a reversing choke in series with said reversing valve;
• a swingbck branch also coupled in series with said commutating valve and in parallel with said commutating capacitor and including a swingback valve poled in opposition to the forward direction of the commutating valve, and a swingback choke in series therewith;
• and
• a first bypass valve coupled across said first and second terminals for conducting load current when the main valve is nonconductive, the improvement comprising;
• a further choke coupled in series between said commutating capacitor and said first load terminal and within the part of the quenching branch which is parallel to the swingback branch;
• and
• a second bypass valve coupling the line which couples the second supply terminal to the second load terminal to the terminal of the commutating capacitor coupled to said first load terminal, said second bypass valve being poled parallel to said first bypass valve.