Method for operating a multilevel converter

Patent metadata

Field	Value
Publication number	US-2022407408-A1
Application number	US-202217843038-A
Country	US
Kind code	A1
Filing date	Jun 17, 2022
Priority date	Jun 18, 2021
Publication date	Dec 22, 2022
Grant date	—

Abstract

A method for operating a multilevel converter in flycap topology, in which the multilevel converter has at least two semiconductor switches controlled by control pulses of variable pulse durations within a control period that recurs at a control frequency to selectively interconnect a voltage source connected to an input of the multilevel converter, an output of the multilevel converter, and at least one auxiliary capacitor arranged between the input and the output, for generating an output voltage. The method includes using at least one oscillation parameter that describes the oscillation behavior of at least one harmonic of an electrical measured variable, at least one correction pulse duration is determined for a future control pulse to reduce the amplitude of the at least one harmonic and at least one semiconductor switch is controlled with a control pulse of the determined correction pulse duration.

First claim

What is claimed:

1 . A method for operating a multilevel converter in flycap topology, the multilevel converter having at least two semiconductor switches controlled by control pulses of variable pulse durations within a control period that recurs at a control frequency to selectively interconnect a voltage source connected to an input of the multilevel converter, an output of the multilevel converter, and at least one auxiliary capacitor arranged between the input and the output of the multilevel converter, for generating an output voltage of the multilevel converter, such that an auxiliary voltage is formed on the at least one auxiliary capacitor and at least one electrical voltage or at least one electrical current is measured as an electrical measured variable at a point that is electrically connected to the output of the multilevel converter, the method comprising:
using at least one oscillation parameter derived from the electrical measured variable, the oscillation parameter describing oscillation behavior of at least one harmonic of the electrical measured variable and a frequency of the harmonic corresponding to an integral multiple of the control frequency; determining at least one correction pulse duration for a future control pulse to reduce an amplitude of the at least one harmonic, and controlling at least one of the semiconductor switches with a control pulse of the determined correction pulse duration.

2 . The method according to claim 1 , wherein, to determine the at least one correction pulse duration from the at least one oscillation parameter, the method further comprises determining at least one estimated value of an auxiliary voltage dropping across the at least one auxiliary capacitor is determined; determining a deviation between the at least one estimated value and a target value that is specified for the auxiliary voltage described by the at least one estimated value; and
wherein the determined deviation is used to determine the at least one correction pulse duration.

3 . The method according to claim 2 , wherein the at least one estimated value of the auxiliary voltage dropping across at least one auxiliary capacitor is determined by solving a system of equations, in which the at least one oscillation parameter is taken into account as a known variable.

4 . The method according to claim 2 , wherein the determination of the at least one correction pulse duration based on the deviation between the at least one estimated value and the target value that is specified for the auxiliary voltage described by at least the one estimated value takes place by a control operator that maps the determined deviation to a controller output variable,
wherein at least one correction pulse duration is determined from the controller output variable, where duration is assigned to at least one semiconductor switch provided in the multilevel converter, and wherein the correction pulse duration determined is subsequently used in order to control the at least one semiconductor switch.

5 . The method according to claim 1 , wherein the at least one correction pulse duration is determined from the electrical measured variable using a convolution operation in which the electrical measured variable is convolved with an impulse response derived from the at least one oscillation parameter.

6 . The method according to claim 1 , wherein at least one of a frequency, an amplitude or a phase position of the at least one harmonic of the electrical measured variable is determined as an oscillation parameter to describe the oscillation behavior of the at least one harmonic of the electrical measured variable.

7 . The method according to claim 6 , wherein the phase position of the at least one harmonic describes a time shift of the at least one harmonic to a beginning of a control period.

8 . The method according to claim 1 , wherein a frequency and/or, in accordance with an IQ method, two amplitudes of two signal components, which are phase-shifted by 90 degrees with respect to one another, of the at least one harmonic of the electrical measured variable are determined as an oscillation parameter to describe the used behavior of the at least one harmonic of the electrical measured variable.

9 . A multilevel converter in flycap topology having an input and an output, the multilevel converter comprising:
at least two semiconductor switches, which are controllable by control pulses of variable pulse durations within a control period that recurs at a control frequency; at least one auxiliary capacitor selectively interconnected between the input and the output via the at least two semiconductor switches; a voltage source connected to the input, the output and the at least one auxiliary capacitor for generating an output voltage, wherein an auxiliary voltage is formed at the at least one auxiliary capacitor, and wherein at least one electrical voltage or at least one electrical current as an electrical measured variable at a point which is electrically connected to the output is detectable, wherein at least one oscillation parameter derived from the electrical measured variable, the at least one oscillation parameter describing an oscillation behavior of at least one harmonic of the electrical measured variable, where the frequency of the harmonic corresponds to an integral multiple of the control frequency, is used to determine at least one correction pulse duration for a subsequent control pulse to reduce an amplitude of the at least one harmonic and to control at least one of the semiconductor switches with the at least one control pulse with the determined correction pulse duration.

10 . A multilevel converter in flycap topology according to claim 8 , wherein a control unit is coupled to use the at least one oscillation parameter derived from the electrical measured variable to determine the at least one correction pulse duration for the future control pulse to reduce the amplitude of the at least one harmonic and to control the at least one of the semiconductor switches with the at least one control pulse with the determined correction pulse duration.

Assignees

• B & R Ind Automation Gmbh

Inventors

• Höller Florian
• Maislinger Franz
• Wyss Jonas
• Steinhauser Armin

Classifications

• H02M7/4837 Primary

  Flying capacitor converters · CPC title

• H02M1/12 Primary

  Arrangements for reducing harmonics from AC input or output · CPC title

• H02M7/4833

  Capacitor voltage balancing · CPC title

• H02M3/158

  including plural semiconductor devices as final control devices for a single load · CPC title

• H02M1/0095

  Hybrid converter topologies, e.g. NPC mixed with flying capacitor, thyristor converter mixed with MMC or charge pump mixed with buck · CPC title