Online converter parameter identification method based on observer

Abstract

The invention provides an online converter parameter identification method based on an observer. An inductive current and output voltage of a converter are subjected to synchronous sampling, a converter discrete model is established, and the converter discrete model is subjected to online parameter identification through the observer. The observer principle is adopted for the online converter parameter identification method based on the observer, main circuit parameters of the converter are subjected to non-invasive online identification, an accurate parameter identification result can be obtained without affecting normal work of the converter, and multiple parameters including the filtering inductance value, the inductance equivalent series resistance value, the filtering capacitance value, the filtering capacitance equivalent series resistance value, the load resistance value and the like can be identified accurately on line according to the output voltage sampling value, the inductive current sampling value and the controller output of the converter. The online converter parameter identification method is easy to implement, simple in analysis process and wide in application range.

Description

technical field [0001] The invention relates to the field of electric power, in particular to an observer-based method for on-line identification of converter parameters. Background technique [0002] In recent decades, power electronics technology has developed rapidly, and power converters are more and more widely used in modern industries such as wind power generation, solar power generation, electric vehicles, and electronic lighting. As the power converter plays an increasingly important role, the economic loss caused by the failure of components in the power converter is also increasing. Therefore, the reliability, stability and dynamic performance of the converter system have been recognized by the industry. The widespread attention of the converter parameter online identification method has a strong practical significance. [0003] During the operation of the power converter, the device will gradually age. As the device ages, the reliability of the converter will co...

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Problems solved by technology

[0005] In the prior art, there are many identification methods. For example, by establishing a hybrid system of converters, according to the input voltage, switching signal, output voltage, and inductor current sampling obtained from the experimental test, the filter inductance value is identified according to the least square method, and the filter capacitor capacitance C And its equivalent series resistance, and for example, taking into account the continuous conduction and discontinuous operation modes of the inductor current on this basis, this method can achieve better identification results, but requires a higher sampling frequency and uses a more complex model , the calculation amount of the algorithm is large, and the stability of the algorithm is difficult to guarantee. For example, by establishing the input-output transfer function model of the Buck circuit filter network, according to the input and output of the converter, the genetic algorithm is used to identify the filter inductance value, the filter capacitor value C and its equivalent Series resistors and load resistors, but this method also requires a higher sampling frequency and the algorithm design is complex and the amount of calculation is large

[0006] Since the capacitor is one of the weakest links in the converter, more converter parameter online identification focuses on the monitoring of the capacitor, such as injecting low-frequency AC components on the DC bus through the three-phase AC / DC / AC converter current loop, Calculate the capacitor value by using the bus voltage change rate and capacitor current sampling; another example is to inject the AC component through the voltage loop, use the input and output unbalanced power as the input, and the capacitor value C as the output to train the support vector machine for parameter estimation. This injection disturbance The method can measure the capacitance value when the converter is working normally, but the injection of the AC component will affect the operation of the converter, and some applications may not allow such an AC component to be injected into the DC bus voltage; there is another one in the prior art It is proposed to suspend the closed-loop control of the DC / DC converter during operation, and change the duty cycle to generate a step response for analyzing the change of the capacitance parameter. This method also affects the output voltage of the converter, which is not allowed in some applications. In addition, the closed-loop control is suspended It may endanger the stable operation of the converter; and the method of directly measuring the capacitor voltage and capacitor current is used to estimate the capacitor parameters according to the capacitor loss power or frequency characteristics, but this method needs to introduce a capacitor current sensor, and the capacitor current sensor will be introduced on the bus The equivalent series inductance ESL affects the operation of the power circuit or increases unnecessary costs; more monitoring methods are to indirectly measure the capacitor current according to Kirchhoff's current law, for example, by analyzing the mathematical model of the capacitor differential equation to obtain the capacitor voltage and current and its The relationship between the derivative and the capacitance parameter, the capacitance current is measured indirectly, and the obtained capacitance voltage and current data are polynomially fitted and then derived for the calculation of the capacitance parameter. This method requires a high sampling rate to obtain enough sampling points. Polynomial fitting; another example is the indirect measurement of capacitor current proposed by Karim Abdennadher, and the establishment of a Kalman filter to estimate capacitor ESR and C, but this method also requires a higher sampling rate; and through indirect measurement of capacitor switch ripple current, according to Calculate the capacitance of metallized polypropylene film capacitors (MPPF-Caps) based on the change of capacitor voltage and charge and discharge charge. This method is only suitable for MPPF capacitors with small ESR; Kai Yao et al. analyzed the steady-state switching ripple and Boost PFC converter steady-state twice power frequency ripple, using two specific points of the voltage ripple to calculate C and ESR, this method does not require a current sensor, easy to implement, but the analysis process is complicated, and not all converters can pass It is not easy to popularize and use such a parameter estimation method in other converters.

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