Study of pulse-blocking for the AC drive system running through neutral section under coasting condition

Pulse-blocking is a special working condition when a AC drive system runs through neutral section under coasting condition. In traditional operation mode, the shock of torque and current will be big and the DC link voltage becomes instable at the moment of blocking or unblocking pulses. These will affect the system´s comfort and reliability. In this paper, the maximal pump-up voltage of the traction converter´s DC-link is calculated and its change trend is analysised during the pulse-blocking. Then a new solution is presented, in which the control system makes the torque component of voltage drop at a certain slope and the shock of the system could be well avoided. At last, performance of the proposed solution is verified by simulation.