Three-phase buck rectifier for power supplies

Abstract

A three-phase alternating current (AC) to direct current (DC) converter may include a three-phase AC filter receiving a three-phase AC power supply, a plurality of three-phase current source rectifiers (CSR) connected in parallel with each other and connected to a three-phase AC filter, and an output filter connected to the CSR's to generate a DC output. Each of the CSRs may include six switches and a free-wheeling diode. Each of the three filtered AC inputs from the three-phase AC filter may be connected via a switch of the six switches to selectably send current into a positive line, and each of three filtered AC inputs from the three-phase AC filter may be connected via another switch of the six switches to selectably receive current from a negative line. The free-wheeling diode may have a cathode connected to the positive line and an anode connected to the negative line.

1 . A three-phase alternating current (AC) to direct current (DC) converter comprising:
 a three-phase AC filter receiving a three-phase AC power supply;   a plurality of three-phase current source rectifiers (CSRs) connected in parallel with each other and connected to the three-phase AC filter; and   an output filter connected to the plurality of three-phase CSRs to generate a DC output,
 wherein each of the plurality of three-phase CSRs comprises:
 six switches; and 
 a free-wheeling diode, 
 
 wherein each of three filtered AC inputs from the three-phase AC filter is connected via a switch of the six switches to selectably send current into a positive line, and each of three filtered AC inputs from the three-phase AC filter is connected via another switch of the six switches to selectably receive current from a negative line, 
 wherein the free-wheeling diode has a cathode connected to the positive line and an anode connected to the negative line. 
   
     
     
         2 . The converter of  claim 1 , wherein each of the six switches includes a MOSFET and a diode connected in series. 
     
     
         3 . The converter of  claim 1 , wherein the plurality of three-phase CSRs are controlled by a controller. 
     
     
         4 . The converter of  claim 3 , wherein the controller determines a present phase sector from a plurality of phase sectors of the three filtered AC inputs. 
     
     
         5 . The converter of  claim 4 , wherein a sensor measures a voltage of the DC output and currents through the positive line and the negative line of each of the plurality of three-phase CSRs. 
     
     
         6 - 20 . (canceled) 
     
     
         21 . A method of controlling a three-phase alternating current (AC) to direct current (DC) converter comprising:
 filtering, by a three-phase AC filter, a three-phase AC power supply into three filtered AC inputs;   providing the three filtered AC inputs to a plurality of three-phase current source rectifiers (CSRs) connected in parallel with each other;   determining, by a controller, a present phase sector from a plurality of phase sectors of the three filtered AC inputs;   generating, by the controller, control signal sequences to selectably turn on switches of each of the plurality of three-phase CSRs to have one zero-state in each of a plurality of a switching period within the present phase sector; and   generating, by an output filter connected to the plurality of three-phase CSRs, a DC output.   
     
     
         22 . The method of  claim 21 , wherein each of the plurality of three-phase CSRs includes six switches and a free-wheeling diode. 
     
     
         23 . The method of  claim 22 , wherein each of the six switches includes a MOSFET and a diode connected in series. 
     
     
         24 . The method of  claim 23 , wherein at least one of the MOSFETs, the diodes, and the free-wheeling diode is a Silicon Carbide based device. 
     
     
         25 . The method of  claim 23 , wherein at least one of the diodes and the free-wheeling diode is a Schottky diode. 
     
     
         26 . The method of  claim 22 , further comprising:
 connecting each of the three filtered AC inputs via a switch of the six switches to selectably send current into a positive line; and   connecting each of the three filtered AC inputs via another switch of the six switches to selectably receive current into a positive line.   
     
     
         27 . The method of  claim 26 , wherein the free-wheeling diode has a cathode connected to the positive line and an anode connected to the negative line. 
     
     
         28 . The method of  claim 21 , further comprising measuring, by a sensor, a voltage of the DC output and currents through a positive line and a negative line of each of a plurality of three-phase CSRs. 
     
     
         29 . The method of  claim 28 , further comprising adjusting, by the controller, a duration of the zero-state of the control signal sequences of at least one of the plurality of three-phase CSRs to compensate for a current flowing between the plurality of three-phase CSRs. 
     
     
         30 . The method of  claim 29 , further comprising controlling, by the controller, the duration of the zero-state of the control signal sequences based upon the voltage of the DC output and the currents through the positive line and the negative line of each of the plurality of three-phase CSRs. 
     
     
         31 . A non-transitory computer readable medium storing computer instructions executable by a controller controlling a three-phase alternating current (AC) to direct current (DC) converter to perform operations comprising:
 filtering, by a three-phase AC filter, a three-phase AC power supply into three filtered AC inputs;   providing the three filtered AC inputs to a plurality of three-phase current source rectifiers (CSRs) connected in parallel with each other, wherein each of the plurality of three-phase CSRs includes six switches and a free-wheeling diode;   determining, by a controller, a present phase sector from a plurality of phase sectors of the three filtered AC inputs;   generating, by the controller, control signal sequences to selectably turn on switches of each of the plurality of three-phase CSRs to have one zero-state in each of a plurality of a switching period within the present phase sector; and   generating, by an output filter connected to the plurality of three-phase CSRs, a DC output.   
     
     
         32 . The non-transitory computer readable medium of  claim 31 , further comprising:
 connecting each of the three filtered AC inputs via a switch of the six switches to selectably send current into a positive line; and   connecting each of the three filtered AC inputs via another switch of the six switches to selectably receive current into a positive line.   
     
     
         33 . The non-transitory computer readable medium of  claim 31 , further comprising measuring, by a sensor, a voltage of the DC output and currents through a positive line and a negative line of each of a plurality of three-phase CSRs. 
     
     
         34 . The non-transitory computer readable medium of  claim 33 , further comprising adjusting, by the controller, a duration of the zero-state of the control signal sequences of at least one of the plurality of three-phase CSRs to compensate for a current flowing between the plurality of three-phase CSRs. 
     
     
         35 . The non-transitory computer readable medium of  claim 34 , further comprising controlling, by the controller, the duration of the zero-state of the control signal sequences based upon the voltage of the DC output and the currents through the positive line and the negative line of each of the plurality of three-phase CSRs.