Method and apparatus for DC bus capacitor pre-charge

摘要

A method and apparatus for converting three phase AC voltages (V R ,V S ,V T ) on first (20), second (22) and third (24) input lines to DC voltage across positive (26) and negative (28) DC buses, the apparatus comprising a rectifier (16) including first (30,36), second (32,38) and third (34,40) rectifier legs, each leg including a switch (30,32,34) and a diode (36,38,40) wherein the switch is linked between the positive DC bus (26) and an cathode of the diode, an anode of the diode is linked to the negative DC rail (28) and the first, second and third diode cathodes are linked to the first, second and third input lines, respectively, a DC bus voltage sensor (80) linked to the positive DC bus (26) and measuring the DC bus voltage to generate a measured DC bus voltage (V DC ) and a rectifier controller (74) that receives the measured DC bus voltage (V DC ), a reference voltage value (V r ) and the three phase AC voltages (V R ,V S ,V T ) wherein, when the measured DC bus voltage (V DC ) is at least equal to the reference voltage value (V r ), the controller turns on the switches in the first, second and third rectifier legs when the voltages on the first, second and third input lines are positive, respectively.