A control apparatus for an electric railcar that provides control so that
when rotational speed of a motor decreases below a required value, torque
of the motor will decrease at a required rate of change, a current
limiter for limiting a torque current command "(A)Iqp" output from a
current command arithmetic unit is provided to ensure that when the
rotational speed of the motor decreases below the required value, the
torque current command will be limited to a command value "(B)Iqp"
smaller than that command value, and to ensure that a carrier frequency
at which PWM signals are created when switching elements of the electric
power converter are controlled by carrier generator is controlled to
become lower than a carrier frequency existing when the rotational speed
of the motor decreases below the required value.