A Power Converter Current Detection Method Based on Non-smooth Observation Technology

Abstract

The invention discloses a current detection method for a power converter based on the non-smooth observation technology. The method comprises the steps: firstly sampling an output voltage v0 of a circuit, and building a mathematic model of an inductance current iL and the output voltage v0 according to a main circuit loop; secondly constructing a current observer based on the mathematic model through employing the non-smooth technology, and guaranteeing the convergence of a current observation error, thereby finally achieving the observation of the inductance current in a Buck converter; finally implementing the method based on a DSP platform through digitalization. Because of fractional power items in the non-smooth observer, the method can effectively improve convergence and anti-disturbance performances of an observation system, and further can achieve the high-speed and precise real-time observation of a current signal. A current observer is simple in structure, is easy to implement, and solves inaccurate, oscillation and interference fragility problems of a conventional current observer.

Description

technical field [0001] The invention relates to a current detection technology in a power converter, in particular, it uses a non-smooth observation method and a discretization technology to realize fast and high-precision estimation of the current. Background technique [0002] With the development of microelectronics technology, among various power electronic devices, low-voltage devices are more and more widely used, and the requirements for the output current of buck converters are also getting higher and higher. A buck converter is a power converter that provides a stable DC voltage to the load by converting high-voltage direct current into low-voltage direct current. [0003] According to the technical field of the power converter mentioned above, it is of great practical and engineering significance to design a method capable of accurately detecting current. At present, the current detection methods in the power converter are as follows: a. The current detection of t...

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Problems solved by technology

At present, the current detection methods in the power converter are as follows: a. The current detection of the current flowing through the small resistance is realized by detecting the voltage difference between the two ends of the small resistance by passing the small resistance by the inductance. Although this method is simple in circuit but The disadvantage is that the voltage generated on the detection resistor will cause errors in the calculation of the circuit and it is difficult to integrate into the chip; b. Based on the circuit characteristics of the operational amplifier, that is, virtual short and virtual break are applied to the detection current, the advantage is that the current detection accuracy is high, However, there are limitations in bandwidth and slow response speed; c. filter detection technology, which measures the average current, cannot realize real-time monitoring of the inductor current, and does not have the function of overcurrent protection

d. Using a small-range Hall current sensor, although the circuit is relatively simple, there are disadvantages such as high cost, the main control circuit needs to be isolated, and it is easy to be interfered by external circuits to generate errors; e. Using a current mutual inductance circuit, although the cost is low, the circuit is simple , but the disadvantage is that the main control circuit needs to be isolated and the detection result is inaccurate

[0004] Compared with the above situation, each detection method has its own advantages and disadvantages, and in practical applications, the circuit will be in different interference environments

At this time, these methods are difficult to achieve the ideal real-time detection effect

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