Control method for electrical converter with LC filter
View Patent ↗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.
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.