Method for operating a multi-phase modular multi-level power converter

• US 9,621,072 B2
• Filed: 01/22/2013
• Issued: 04/11/2017
• Est. Priority Date: 02/14/2012
• Status: Active Grant

• Current Assignee: Innomotics GmbH
• Original Assignee: Siemens AG
• Inventors: Bernet, Steffen, Brnklau, Hans, Gensior, Albrecht, Rohner, Steffen
• Primary Examiner(s): Dole, Timothy J
• Assistant Examiner(s): AHMED, YUSEF A
• Application Number:
  US14/378,545
• Publication Number:
  US 20150049532A1
• Time in Patent Office: 1,540 Days
• CPC Class Codes: H02M 7/483 Converters with outputs that each can have more than two voltages levels
• CPC Class Codes: H02M 7/4835 comprising two or more cells, each including a switchable capacitor, the capacitors having a nominal charge voltage which corresponds to a given fraction of the input voltage, and the capacitors being selectively connected in series to determine the instantaneous output voltage
• CPC Class Codes: H02M 7/5387 in a bridge configuration

Abstract

A method for operating a multi-phase modular power inverter having DC input terminals and AC phase voltage output terminals connected to a load, phase modules connected between the DC input terminals, with each phase module composed of valve arms connected in series at a connection point forming an AC phase voltage output terminal which is connected to a load, each valve arm having a plurality of power inverter cells with turn-off semiconductor switches and a choke connected in series, includes controlling, with a control device, the turn-off semiconductor switches of each power inverter cell as a function of a plurality of setpoint values, wherein the setpoint values are generated such that a time-averaged energy value stored in a capacitor of a corresponding power inverter cells is predetermined by an operating point of the load and-or an operating mode of the modular multi-level power inverter.

Claims

1. A method for operating a multi-phase modular multi-level power inverter having two DC voltage input terminals and AC phase voltage output terminals connected to a load, a plurality of phase modules connected between the DC voltage input terminals, each phase module composed of valve arms connected in series at a connection point forming an AC phase voltage output terminal which is connected to a load, each valve arm having a plurality of power inverter cells comprising turn-off semiconductor switches and a choke connected in series, the method comprising:

controlling, with a control device, the turn-off semiconductor switches of each power inverter cell as a function of a plurality of setpoint values, wherein the setpoint values are generated such that a time-averaged energy value stored in a capacitor of the corresponding power inverter cells is predetermined by at least one of an operating point of the load and an operating mode of the modular multi-level power inverter, said time-averaged stored energy value determined for at least one of an operating point of the load and an operating mode of the modular multi-level power inverter stored in a table in a storage unit.

2. The method of claim 1, wherein a time-averaged stored energy value associated with the stored energy is predetermined as a function of the operating point.

3. The method of claim 1, wherein a time-averaged stored energy value associated with the stored energy is predetermined as a function of the operating mode of the modular multi-level power inverter.

4. The method of claim 1, wherein the time-averaged stored energy value is calculated offline.

5. The method of claim 1, wherein the time-averaged stored energy value is calculated online.

6. The method of claim 1, wherein setpoint values of the time-averaged stored energy values are predetermined for all power inverter cells of the multi-phase modular multi-level power inverter.

7. The method of claim 1, wherein setpoint values of the time-averaged stored energy values are predetermined for all power inverter cells of a valve arm of the multi-phase modular multi-level power inverter.

8. The method of claim 1, wherein the operating point of the load is determined from measured values of the load.

9. The method of claim 8, wherein the measured values of the load comprise load currents and power inverter phase output voltages.