US 10,386,808 B2Granted

System parameter identificatino method based on rate-limited relay with hysteresis and sinusoidal injection

AssigneeDanfoss Power Electronics A/S

InventorsGang Tian, Adam Reynolds

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Abstract

A system parameter identification system uses a combination of relay control and sinusoidal injection to derive accurate estimates of system parameters of a controlled system or process while satisfying the rate-limit associated with some control applications. The system uses rate-limited relay control with hysteresis to place the system in oscillation. The system then switches the control signal from relay-based control to open-loop sinusoidal control using oscillation frequency, amplitude, and phase information obtained during the relay control stage. During the sinusoidal control phase, the plant output passes through a bandpass filter at the oscillation frequency to get a clean sinusoidal signal. The phase difference between the input and output signals and the output/input amplitude ratio are then obtained and used to calculate of the system parameters.

Claims20

Dependent claims

A parameter identification system, comprising:

a memory;
and
a processor configured to execute components stored on the memory, the components comprising:
a control signal generator configured to generate a control signal directed to a controlled system;
an output monitoring component configured to monitor an output signal of the controlled system, the output signal representing a variable of the controlled system controlled by the control signal;
a relay control and measurement component configured to output the control signal in accordance with rate-limited relay-based control of the controlled system, wherein the rate-limited relay-based control causes the control signal to oscillate at a first phase;
a sinusoidal control and measurement component configured to, in response to a determination that the output signal is in oscillation during the rate-limited relay-based control, stop the rate-limited relay-based control and initiate open-loop sinusoidal signal injection control of the controlled system, whereby the control signal is a sinusoidal signal having a second phase that is substantially aligned with the first phase;
and
a system parameter determination component configured to determine one or more system parameters of the controlled system based on a data set obtained via measurement of the control signal and the output signal during the rate-limited relay based control and the open-loop sinusoidal signal injection control.

6 more elements

A method, comprising:

outputting, by a system comprising at least one processor as a first stage of a parameter identification sequence, a control signal to a controlled system as a rate-limited relay-based control output, wherein the outputting produces an oscillation of an output signal of the controlled system at a first phase;
in response to a determination that the output signal is in oscillation during the relay-based control stage, outputting, by the system as a second stage of the parameter identification sequence, the control signal to the controlled system as an open-loop sinusoidal control output having a second phase that is substantially aligned with the first phase;
and
determining, by the system, one or more system parameters of the controlled system based on a data set obtained via measurement of the control signal and the output signal during the first stage and the second stage.

1 more element

Dependencies are inferred from the claim text.