Pyramid-type multilevel converter topology

Abstract

A pyramid-type multilevel converter for converting DC voltage to AC voltage waveforms, and vice versa. An example device can use modular building blocks to form a selector stage, a converter stage, and at least one intermediate stage if the number of converters within the converter stage is greater than or equal to 3, with the converter stage switching at high-frequency PWM to chop the DC voltages. The modular building blocks are connected in a symmetric or asymmetric pyramid configuration having a base of using the converter stage and an apex of the selector stage.

We claim: 
     
         1 . A pyramid-type multilevel converter, comprising:
 a selector stage;   a converter stage; and   at least one intermediate stage between said selector stage and said converter stage,   wherein:
 said selector stage and said at least one intermediate stage are made of a plurality of modular building blocks; 
 said converter stage comprises a plurality of n converter circuits to output phase voltage references; and 
 said selector stage, said converter stage, and said at least one intermediate stage are electrically connected in a pyramid formation having a base of said converter stage and an apex of said selector stage. 
   
     
     
         2 . The pyramid-type multilevel converter of  claim 1 , wherein each respective modular building block in said plurality of modular building blocks comprises:
 an upper switch;   a lower switch; and   a midpoint,   wherein:
 said upper switch has a first connection to one of: 1) the midpoint of a first upper modular building block in an adjacent layer within the intermediate stage, or 2) an output terminal of a first upper converter in an adjacent converter stage, and a second connection to said midpoint; and 
 said lower switch has a third connection to one of: 1) the midpoint of a second lower modular building block in the adjacent layer within the intermediate stage, or 2) an output terminal of a second lower converter in an adjacent converter stage, and a fourth connection to said midpoint. 
   
     
     
         3 . The pyramid-type multilevel converter of  claim 2 , wherein said upper switch and said lower switch are soft-switching low-frequency Pulse-Width-Modulation (PWM) or line-frequency switches. 
     
     
         4 . The pyramid-type multilevel converter of  claim 3 , wherein said plurality of n converter circuits comprise Pulse-Width-Modulation (PWM) high-frequency converters. 
     
     
         5 . The pyramid-type multilevel converter of  claim 1 , wherein said plurality of modular building blocks of the same intermediate stage lack electrical connection to each other. 
     
     
         6 . The pyramid-type multilevel converter of  claim 1 ,
 said selector stage switched at line-frequency; and   said at least one intermediate stage switched at low-frequency PWM; and   said converter stage switched at high-frequency PWM scheme.   
     
     
         7 . The pyramid-type multilevel converter of  claim 1 , wherein said plurality of n converter circuits comprise two-level converters, said two-level converters being at least one of a half-bridge circuit and a multilevel converter. 
     
     
         8 . The pyramid-type multilevel converter of  claim 7 , wherein the at least one of said half-bridge circuit and said multilevel converter comprises at least one half-bridge topology from the list of Diode Clamped, A-NPC (Active Neutral Point Clamped), NPP (Neutral-Point-Piloted), FCM (Flying-Capacitor Multilevel), and MMC (Modular Multilevel Converter). 
     
     
         9 . The pyramid-type multilevel converter of  claim 1 , wherein said pyramid formation electrically connecting said selector stage, said converter stage, and said at least one intermediate stage is a symmetric pyramid formation. 
     
     
         10 . The pyramid-type multilevel converter of  claim 1 , wherein said pyramid formation electrically connecting said selector stage, said converter stage, and said at least one intermediate stage is an asymmetric pyramid formation. 
     
     
         11 . An integrated circuit for generating an Alternating Current (AC) voltage waveform, comprising:
 a selector stage;   a converter stage; and   at least one intermediate stage between said selector stage and said converter stage,   wherein:
 said selector stage and said at least one intermediate stage are made of a plurality of modular building blocks; 
 said converter stage comprises a plurality of n converter circuits to output phase voltage references; and 
 said selector stage, said converter stage, and said at least one intermediate stage are electrically connected in a pyramid formation having a base of said converter stage and an apex of said selector stage. 
   
     
     
         12 . The integrated circuit of  claim 11 , wherein each respective modular building block in said plurality of modular building blocks comprises:
 an upper switch;   a lower switch; and   a midpoint,   wherein:
 said upper switch has a first connection to one of: 1) the midpoint of a first upper modular building block in an adjacent layer within the intermediate stage or, 2) an output terminal of a first upper converter in an adjacent converter stage, and a second connection to said midpoint; and 
 said lower switch has a third connection to one of: 1) the midpoint of a second lower modular building block in the adjacent layer within the intermediate stage or, 2) an output terminal of a second lower converter in an adjacent converter stage, and a fourth connection to said midpoint. 
   
     
     
         13 . The integrated circuit of  claim 12 , wherein said upper switch and said lower switch are soft-switching low-frequency or line-frequency semiconductor switches. 
     
     
         14 . The integrated circuit of  claim 13 , wherein said plurality of n converter circuits comprise high-frequency Pulse-Width-Modulation (PWM) converters. 
     
     
         15 . The integrated circuit of  claim 11 , wherein said plurality of modular building blocks of the same layer/column within said intermediate stage lacks electrical connection to each other. 
     
     
         16 . The integrated circuit of  claim 11 , wherein:
 said selector stage is switched at line-frequency;   said intermediate stage is switched at low-frequency PWM; and   said converter stage is switched at high-frequency PWM scheme.   
     
     
         17 . The integrated circuit of  claim 11 , wherein said plurality of n converter circuits comprise two-level converters, said two-level converters being at least one of a half-bridge circuit and a multilevel converter. 
     
     
         18 . The integrated circuit of  claim 17 , wherein the at least one of said half-bridge circuit and said multilevel converter comprises at least one half-bridge topology from the list of Diode Clamped A-NPC (Active Neutral Point Clamped), NPP (Neutral-Point-Piloted), FCM (Flying-Capacitor Multilevel), and MMC (Modular Multilevel Converter). 
     
     
         19 . The integrated circuit of  claim 11 , wherein said pyramid formation electrically connecting said selector stage, said converter stage, and said at least one intermediate stage is a symmetric pyramid formation. 
     
     
         20 . The integrated circuit of  claim 11 , wherein said pyramid formation electrically connecting said selector stage, said converter stage, and said at least one intermediate stage is an asymmetric pyramid formation.