Control circuit for electric power converter

A control circuit for an electric power converter, the electric power converter including a plurality of switch pairs each consisting of an upper-arm switch and a lower-arm switch that are electrically connected in series with each other, each of the switch pairs having a corresponding one of a plurality of phase windings of a multi-phase rotating electric machine electrically connected to a node between the upper-arm and lower-arm switches of the switch pair, each of the upper-arm and lower-arm switches having a diode electrically connected in antiparallel thereto, the switch pairs having a DC power source electrically connected in parallel thereto, all of the upper-arm switches of the switch pairs together constituting an upper-arm switch group and all of the lower-arm switches of the switch pairs together constituting a lower-arm switch group, the control circuit comprising:

• an abnormality determiner configured to determine whether an abnormality has occurred in at least one of the electric power converter and the rotating electric machine;
• a voltage determiner configured to determine whether a line-to-line voltage between the phase windings of the rotating electric machine when a counterelectromotive force is generated in the phase windings is higher than a voltage of the DC power source;
• and
• an abnormality-handling controller configured to perform, when both a first condition and a second condition are met, an all-phase short circuit control of turning on all of the switches of one of the upper-arm switch group and the lower-arm switch group and turning off all of the switches of the other of the upper-arm switch group and the lower-arm switch group, thereby inhibiting regeneration from being performed in a system which includes the rotating electric machine, the electric power converter and the DC power source,
• the first condition being that it is determined by the abnormality determiner that an abnormality has occurred in at least one of the electric power converter and the rotating electric machine, and
• the second condition being that it is determined by the voltage determiner that the line-to-line voltage is higher than the voltage of the DC power source.