BIDIRECTIONAL STEP-DOWN DC VOLTAGE CONVERTER Russian patent published in 2010 - IPC H02M3/07 

FIELD: electric engineering.

SUBSTANCE: bidirectional step-down DC voltage converter (BSVC) may be used as high-voltage dc-dc converter of medium capacity in systems of DC electric equipment, for instance for DC electric locomotives with voltage 3(1.5) kV for supply from contact network with increased voltage of (12(6) kV, 18(9) kV etc.). Proposed BSVC with ratio of high voltage value to amplitude of low voltage pulses equal to K, where K is even number, higher than two, comprises 3-K+5 keys formed by opposite connection of valve with full control and diode, and K capacitors used at single polarity of voltage. Structure of this BSVC includes two key modules (M1 and M2), K-2 additional key modules (AM), three additional keys (AK) and capacitors. Modules M1 and M2 consist each of four keys, serially connected with identical terminals, and middle points of these points serve as low voltage terminals. Each of AM modules consists of three keys, which are serially connected by opposite terminals. Two of AK keys are connected one by one between the first points of M1 and M2 module keys connection, which are counted from terminals of low voltage to the left and right. AM modules are connected in a cascade to modules of M1 and M2 symmetrically relative to them to the left and to the right. K capacitors are connected one by one between points of connection of according terminal outputs of modules M1 and M2 with modules AM, between connection points of neighbouring modules AM and between terminal outputs of terminal modules AM. One of two high voltage terminals is connected to according output terminal of according terminal AM directly, and the second one - via the third AK key connected either by cathode of diode to positive output of high voltage, or by anode of diode to negative output of high voltage.

EFFECT: reduced losses of active power in capacitors, due to use of capacitors with limit values of voltage, which do not exceed amplitude of voltage pulses at low voltage outputs of converter.

5 dwg