Equilibrium voltage generator and method to generate an equilibrium voltage of a three-phase inverter

摘要

Balance voltage generator (402) in a three-phase inverter, the three-phase inverter that operates in a continuous modulation mode or in a discontinuous modulation mode, comprising the balance voltage generator (402): a first limiter (502 (a )) configured to compare a first phase voltage signal (V * as) with a maximum limit value (Vdc / 2) and a minimum limit value (-Vdc / 2) to emit a first limit voltage signal (Vas); a second limiter (502 (b)) configured to compare a second phase voltage signal (V * bs) with the maximum limit value (Vdc / 2) and the minimum limit value (-Vdc / 2) to emit a second signal voltage limit (Vbs); a third limiter (502 (c)) configured to compare a third phase voltage signal (V * cs) with the maximum limit value (Vdc / 2) and the minimum limit value (-Vdc / 2) to emit a third signal voltage limit (Vcs); and an adder (504) configured to add a difference between the first phase voltage signal (V * as) and the first limit voltage signal (Vas), a difference between the second phase voltage signal (V * bs) and the second limit voltage signal (Vbs), and a difference between the third phase voltage signal (V * cs) and the third limit voltage signal (Vcs), to emit an equilibrium voltage (V * sn), in which the maximum limit value (Vdc / 2) and the minimum limit value (-Vdc / 2) are determined by a DC link voltage (Vdc / 2) of the three-phase inverter, and in which the adder (504) emits a different equilibrium voltage depending on a modulation index (MI) determined by the DC link voltage (Vdc / 2) of the three-phase inverter to switch between the continuous modulation mode and the discontinuous modulation mode of the uncalculated three-phase inverter additionally another equilibrium tension.