PURPOSE: To shorten the rise-up time of an AC regenerative brake by suitably controlling the triggering angles of thyristors in response to the speed of an electric car.

CONSTITUTION: When a command is issued so as to brake at a specified speed V2 on notch curves, the first step signal B5 is given to a reversible counter 15 from a logic circuit 18, and step-up is started. As a result, the signals from a memory circuit 16 are output to phase-circuits 17-1 and 17-2 for thyristor rectifiers of inverters in the order of B5→B6→B7.... Thus, the inverter voltage corresponding to the speed of an electric car is controlled, and the rise-up of a motor-current-limiting value, in other words, a specified braking force becomes fast. The stable control of an AC regenerative brake can be accomplished by the use of a notchcode converter 11 which commands the last step of the regenerative brake, a comparator 12 which generates the command signals for stepping up and stepping down the regenerative- brake steps, a current-limiting-value comparator 13 which outputs the signal that steps up the regenerative brake when a specified requirements are satisfied, a judging device 14, and the like.