Control method for electrical converter with LC filter

Patent metadata

Field	Value
Publication number	US-9831760-B2
Application number	US-201615097209-A
Country	US
Kind code	B2
Filing date	Apr 12, 2016
Priority date	Oct 18, 2013
Publication date	Nov 28, 2017
Grant date	Nov 28, 2017

Abstract

An electrical converter is interconnected via a filter with an electrical load or an electrical power source. A method for controlling the converter comprises the steps of: receiving a reference flux (ψ* i ) for the electrical converter; determining output signals (y) comprising currents and/or voltages measured in the filter; determining an estimated flux (ψ i ) from the output signals (y); determining a corrective flux (ψ i,damp ) from the output signals (y) based on a mathematical model of the filter and a quadratic cost function; determining control input signals (u) for the electrical converter based on a sum of the estimated flux (ψ i ) and the corrective flux (ψ i,damp ); controlling the converter with the control input signals (u); and algorithmic filtering of at least one of the output signals (y) by applying a signal filter to the at least one output signal, which is designed for amplifying the at least one output signal at a resonance frequency of the filter, whereby the corrective flux (ψ i,damp ) is determined from the filtered output signals.

First claim

The invention claimed is:

1. A method for controlling an electrical converter interconnected via a filter with an electrical load or electrical power source, the method comprising the steps of:
determining output signals comprising currents and/or voltages measured in the filter;
determining an estimated flux from the output signals;
determining a corrective flux from the output signals based on a mathematical model of the filter and a quadratic cost function;
determining control input signals for the electrical converter based on a sum of the estimated flux and the corrective flux;
controlling the converter with the control input signals;
algorithmic filtering of at least one of the output signals by applying a signal filter to the at least one output signal, which is designed for amplifying the at least one output signal at a resonance frequency of the filter, whereby the corrective flux is determined from the filtered output signals.

2. The method of claim 1 ,
receiving a reference flux for the electrical converter;
setting a flux error to a difference between the reference flux and the sum of the estimated flux and the corrective flux;
determining control input signals for the electrical converter based on the flux error.

3. The method of claim 2 ,
wherein the mathematical model is based on differential equations modelling the behaviour of the filter.

4. The method of claim 2 ,
wherein the mathematical model of the filter is solved offline and the corrective flux is determined by integrating a filter voltage calculated via the minimization of the quadratic cost function subject to the mathematical model, with the result being a linear equation from the output signals.

5. The method of claim 2 , wherein the output signals at least comprise one of:
a converter current between the converter and the filter,
a load current between the filter and the load or power source,
a converter side filter voltage across the filter on the converter side, and
a load side filter voltage across the filter on the load side or power source side.

6. The method of claim 2 ,
wherein the filter comprises an inductor connecting the converter and the load or power source and a capacitor connected to the load or power source and the converter.

7. The method of claim 2 ,
wherein the control input signals are determined by a model predictive control method and a second cost function;
wherein the second cost function penalizes the flux error.

8. The method of claim 1 ,
wherein the mathematical model is based on differential equations modelling the behaviour of the filter; and
wherein the cost function is not quadratic in the corrective flux.

9. The method of claim 1 ,
wherein the mathematical model of the filter is solved offline and the corrective flux is determined by integrating a filter voltage calculated via the minimization of the quadratic cost function subject to the mathematical model, with the result being a linear equation from the output signals.

10. The method of claim 1 , wherein the output signals at least comprise one of:
a converter current between the converter and the filter,
a load current between the filter and the load or power source,
a converter side filter voltage across the filter on the converter side, and
a load side filter voltage across the filter on the load side or power source side.

11. The method of claim 1 ,
wherein the filter comprises an inductor connecting the converter and the load or power source and a capacitor connected to the load or power source and the converter.

12. The method of claim 1 ,
wherein the signal filter is designed for different phase shifting of at least one output signal at frequencies different from the resonance frequency.

13. The method of claim 1 ,
wherein the control input signals are determined by a model predictive control method and a second cost function;
wherein the second cost function penalizes the flux error.

14. The method of claim 13 ,
wherein the control input signals are determined by modifying switching time instants of a selected pulse pattern for the converter such that the second cost function is minimized.

15. The method of claim 1 ,
wherein the control input signals comprise switching states of the converter.

16. A controller for controlling an electrical converter interconnected via a filter with an electrical load or electrical power source, comprising:
the controller structured to determine output signals comprising currents and/or voltages measured in the filter;
the controller structured to determine an estimated flux from the output signals;
the controller structured to determine a corrective flux from the output signals based on a mathematical model of the filter and a quadratic cost function;
the controller structured to determine control input signals for the electrical converter based on a sum of the estimated flux and the corrective flux;
the controller structured to control the converter with the control input signals; and
the controller structured to perform algorithmic filtering of at least one of the output signals by applying a signal filter to the at least one output signal, which is designed for amplifying the at least one output signal at a resonance frequency of the filter, wherein the corrective flux is determined from the filtered output signals.

17. A converter system, comprising:
an electrical converter for transforming a first electrical current into a second electrical current;
a filter connected with the converter; and
a controller for cant rolling the converter, the controller structured to determine output signals comprising currents and/or voltages measured in the filter;
the controller structured to determine an estimated flux from the output signals;
the controller structured to determine a corrective flux from the output signals based on a mathematical model of the filter and a quadratic cost function;
the controller structured to determine control input signals for the electrical converter based on a sum of the estimated flux and the corrective flux;
the controller structured to control the converter with the control input signals; and
the controller structured to perform algorithmic filtering of at least one of the output signals by applying a signal filter to the at least one output signal, which is designed for amplifying the at least one output signal at a resonance frequency of the filter, wherein the corrective flux is determined from the filtered output signals.

18. The converter system of claim 17 ,
wherein the electrical converter comprises at least one inverter and at least one active rectifier.

19. The converter system of claim 18 ,
wherein the converter is connected to a load and/or a power source via the filter.

20. The converter system of claim 17 ,
wherein the converter is connected to a load and/or a power source via the filter.

Assignees

• Abb Schweiz Ag

Inventors

• Al-Hokayem Peter
• Geyer Tobias
• Oikonomou Nikolaos

Classifications

• H02P23/30

  Direct torque control [DTC] or field acceleration method [FAM] · CPC title

• H02P23/14

  Estimation or adaptation of motor parameters, e.g. rotor time constant, flux, speed, current or voltage · CPC title

• G05B2219/41406

  LQR linear quadratic regulator to calculate gain for several known variables · CPC title

• H02M7/53875

  with analogue control of three-phase output · CPC title

• H02M2001/0003

  Electricity · mapped topic