The Commerce Department said yesterday that a major Swedish company has agreed to the second-largest civil penalty ever assessed in an export-control case for illegally taking part in a deal that sent nine sophisticated American computers to the Soviet Union and Czechoslovakia.

The company, ASEA, AB , was described by Commerce officials as one of the largest manufacturers of robots in the world.

Assistant Secretary Paul Freedenberg said the illegal diversion of U.S. high technology to the Soviet bloc took place because people "inside of ASEA and outside of ASEA" cooperated to move the computers from Sweden to Eastern Europe.

He acknowledged that some of the sales started as legal transactions until President Carter slapped foreign policy export controls on shipments of high technology to Soviet bloc nations after the Russian invasion of Afghanistan in December 1979. But, Freedenberg added, the company knew when the new controls were imposed and should not have allowed the sales to go through.

He said Bertram Brinkeborn, a high-level ASEA employe who no longer is with the company, worked with an outsider, Sven Olof Hakansson, to make the shipment. Hakansson has been charged in Sweden, which this year agreed to cooperate on controlling high-technology exports to the Soviet bloc.

ASEA was fined because Commerce considered it responsible for Brinkeborn's alleged actions.

The ASEA case was one of three major illegal-export operations uncovered by Commerce investigators during the past 10 days, Freedenberg said. They include an indictment Wednesday in U.S. District Court in Alexandria of an Austrian company and two employes accused of illegally exporting $6.5 million in semiconductor manufacturing equipment to the Soviet bloc.

Commerce said its investigators earlier seized $233,000 worth of strategic electronic manufacturing equipment to prevent its export to France and possible diversion to the Soviet Union. Deputy Assistant Secretary Theodore W. Wu said the equipment, seized in Burlingame, Calif., is vital for making semiconductors for civilian and military use. Freedenberg said the Soviet Union has placed priority on obtaining semiconductor manufacturing capability.