Active discharge of the DC link capacitor of a three-phase inverter by way of rotating half-bridge short-circuits
View Patent ↗A control device for a three-phase inverter of a vehicle prime mover is configured to activate active discharge of a DC link of the inverter and at the same time to switch on the lower half-bridge switches of the inverter during the active discharge, and to switch on an upper half-bridge switch of the inverter. The three-phase inverter has three half-bridges, each having an upper half-bridge switch and a lower half-bridge switch.
1 . A control apparatus for a three-phase inverter of a vehicle prime mover, wherein the control apparatus is configured:
to actuate an active discharge of a DC link of the three-phase inverter,
to simultaneously switch on each lower half-bridge switch of the three-phase inverter during an active discharge, and
while each lower half-bridge switch is switched on, to switch on upper half-bridge switches of the three-phase inverter one at a time in an alternating manner.
2 . The control apparatus according to claim 1 , wherein the control apparatus is further configured:
to switch on an upper half-bridge switch of a further phase in conjunction with, or further to, a switch-off of the previously switched-on upper half-bridge switch.
3 . The control apparatus according to claim 1 , wherein the control apparatus is further configured:
to switch on an upper half-bridge switch of a further phase in conjunction with, or further to, an intervention of short-circuit detection on the previously switched-on upper half-bridge switch.
4 . The control apparatus according to claim 1 , wherein the control apparatus is further configured:
to switch a next upper half-bridge switch which is to be switched on, at latest, with a predefined temporal offset with effect from commencement of switching of the previous upper half-bridge switch.
5 . A three-phase inverter for a vehicle prime mover, the three-phase inverter comprising:
three half-bridges, each having an upper half-bridge switch and a lower half-bridge switch, and
the control apparatus according to claim 1 .
6 . The three-phase inverter according to claim 5 , wherein:
the half-bridge switches are configured in a form of IGBTs, and a temporal offset between sequential switch-on of two upper half-bridge switches does not exceed 10 microseconds.
7 . The three-phase inverter according to claim 5 , wherein:
the half-bridge switches are configured in a form of SiC MOSFETs, and a temporal offset between sequential switch-on of two upper half-bridge switches does not exceed 3 microseconds.
8 . A method for active discharge of a DC link of a three-phase inverter of a vehicle prime mover, the method comprising:
isolating a drive battery from the DC link of the three-phase inverter,
simultaneously performing switch-on of each lower half-bridge switch of the three-phase inverter, and
while each lower half-bridge switch is switched on, performing switch-on of upper half-bridge switches of the three-phase inverter one at a time in an alternating manner.
9 . The method according to claim 8 , wherein:
the switched-on upper half-bridge switches are alternated until such time as a voltage present on the DC link falls below a limiting value.