A power conversion system, comprising: a DC bus circuit comprising first and second DC bus terminals (90a, 90b); a rectifier including a plurality of multilevel rectifier converter stages (100a, 100b, 100c), individual ones of the multilevel rectifier converter stages (100a, 100b, 100c) comprising an AC input terminal adapted to receive AC input power from a corresponding one of a plurality of AC input phases, a pair of DC output terminals (101, 102) individually coupled to a corresponding one of the first and second DC bus terminals (90a, 90b) of the DC bus circuit, and a multilevel rectifier circuit (S1-S6, D1, D2, C1, C2) operable according to a corresponding set of rectifier switching control signals to convert AC input power to provide a DC output voltage at the DC output terminals (101, 102); an inverter including a plurality of multilevel inverter stages (100r, 100s, 100t), individual ones of the multilevel inverter stages (100r, 100s, 100t) comprising a pair of DC input terminals (101, 102) individually coupled to a corresponding one of the first and second DC bus terminals (90a, 90b) of the DC bus circuit, an AC output terminal adapted to provide AC output power directly or indirectly to a corresponding one of a plurality of AC output phases to drive a load, and a multilevel inverter circuit (S1-S6, D1, D2, C1, C2) operable according to a corresponding set of inverter switching control signals to convert DC input power from the DC bus circuit to provide an AC output voltage at the AC output terminal, wherein the individual multilevel converter stages of the rectifier and of the inverter are configured to provide an integer number N AC voltage levels, where N is an even number greater than or equal to 4; and characterised in that it further comprises a controller providing the rectifier and inverter switching control signals to facilitate offsetting of common mode voltage contributions of the rectifier and the inverter, wherein the controller provides the rectifier and inverter switching control signals via space vector modulation according to corresponding rectifier and inverter reference vectors (Vref) using a corresponding subset of possible switching states with minimal absolute common mode voltages, such that the inverter common mode contribution completely or at least partially offsets or cancels the common mode voltage contribution associated with the rectifier. a DC bus circuit comprising first and second DC bus terminals (90a, 90b); a rectifier including a plurality of multilevel rectifier converter stages (100a, 100b, 100c), individual ones of the multilevel rectifier converter stages (100a, 100b, 100c) comprising an AC input terminal adapted to receive AC input power from a corresponding one of a plurality of AC input phases, a pair of DC output terminals (101, 102) individually coupled to a corresponding one of the first and second DC bus terminals (90a, 90b) of the DC bus circuit, and a multilevel rectifier circuit (S1-S6, D1, D2, C1, C2) operable according to a corresponding set of rectifier switching control signals to convert AC input power to provide a DC output voltage at the DC output terminals (101, 102); an inverter including a plurality of multilevel inverter stages (100r, 100s, 100t), individual ones of the multilevel inverter stages (100r, 100s, 100t) comprising a pair of DC input terminals (101, 102) individually coupled to a corresponding one of the first and second DC bus terminals (90a, 90b) of the DC bus circuit, an AC output terminal adapted to provide AC output power directly or indirectly to a corresponding one of a plurality of AC output phases to drive a load, and a multilevel inverter circuit (S1-S6, D1, D2, C1, C2) operable according to a corresponding set of inverter switching control signals to convert DC input power from the DC bus circuit to provide an AC output voltage at the AC output terminal, wherein the individual multilevel converter stages of the rectifier and of the inverter are configured to provide an integer number N AC voltage levels, where N is an even number greater than or equal to 4; and characterised in that it further comprises a controller providing the rectifier and inverter switching control signals to facilitate offsetting of common mode voltage contributions of the rectifier and the inverter, wherein the controller provides the rectifier and inverter switching control signals via space vector modulation according to corresponding rectifier and inverter reference vectors (Vref) using a corresponding subset of possible switching states with minimal absolute common mode voltages, such that the inverter common mode contribution completely or at least partially offsets or cancels the common mode voltage contribution associated with the rectifier.