Patent ID: 8493756

Claim:
A switching control method of a transformer coupled booster, wherein the transformer coupled booster comprises a primary inverter, a secondary inverter and a transformer, the primary inverter including four IGBTs bridging-connected to a primary coil of the transformer, and diodes each connected in parallel to respective one of the IGBTs with polarity thereof being opposite to that of the IGBTs, and being constituted by a first arm that turns ON/OFF two of the IGBTs simultaneously, and a second arm that turns ON/OFF other two of the IGBTs simultaneously, the first arm and the second arm being turned ON/OFF alternately, the secondary inverter including four IGBTs bridging-connected to a secondary coil of the transformer; and diodes each connected in parallel to respective one of the IGBTs with polarity thereof being opposite to that of the IGBTs, and being constituted by a third arm that turns ON/OFF two of the IGBTs simultaneously, and a fourth arm that turns ON/OFF other two of the IGBTs simultaneously, the third arm and the fourth arm being turned ON/OFF alternately, the primary inverter being connected in series to the secondary inverter in such a manner that a positive terminal of the primary inverter and a negative terminal of the secondary inverter constitute additive polarity, and the primary inverter being linked to the secondary inverter by the transformer, the method comprising: detecting a primary coil current flowing through the primary coil of the transformer and a secondary coil current flowing through the secondary coil of the transformer, respectively; obtaining a peak value of a current difference between the detected primary coil current and the detected secondary coil current; and changing ON period and OFF period of the four arms according to a result of comparison between the obtained peak value of the current difference and a predetermined threshold value, wherein the ON period and the OFF period for each of the arms are changed so that the ON period of the first arm and the third arm decreases when the current difference is larger than a preset threshold current value (Ac), the ON period and the OFF period for each of the arms are changed so that the ON period of the first arm and the third arm increases when the current difference is smaller than a negative value of the threshold current value (−Ac), and the ON period of the first arm and the third arm is maintained when the current difference falls within a range between the negative value of the threshold current value (−Ac) and the threshold current value (Ac).