Variable ring width hysteresis current control method based on timer

Abstract

The invention provides a variable ring width hysteresis current control method based on a timer and a circuit for realizing the method. A standard ring width option list and a standard ring width real-time adjustment form are stored, the optimal standard ring width is chosen from the stored forms according to the relation of an actual measurement current deviation, actual currents and system rated currents, PWM signal output is generated according to the current deviation on the basis of the optimal standard ring width, and switching-on and switching-off of an IGBT power tube are controlled. The variable ring width hysteresis current control method based on the timer has the obvious advantages of lowering switching loss, increasing the current tracing speed and improving current quality.

Description

technical field [0001] The invention relates to a variable-width hysteresis-loop current control method based on a timer, and belongs to the technical field of power supply. Background technique [0002] In the field of traditional power electronics, current tracking control technology plays an important role, especially for systems with high real-time requirements. This is because the current tracking control technology itself has the characteristics of fast response, high control precision, and strong adaptability. The more important point is that this direct current tracking control technology belongs to ping-pang control, and the response speed is relatively fast. Its wide-scale use has laid the foundation and has been widely used. [0003] Commonly used current tracking methods mainly include triangular wave comparison method and hysteresis comparison method. The switching frequency of the triangular wave comparison mode is fixed, which can realize tracking without st...

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Problems solved by technology

The switching frequency of the triangular wave comparison method is fixed, which can realize tracking without static error, but due to the fixed frequency control, it will cause a large tracking error, and the output waveform will appear harmonics of a specific frequency

The disadvantage is that because the width of the hysteresis is fixed, the switching frequency of the power device changes with the change of the instantaneous value of the current, which brings difficulties to the design of the output filter, and the filter parameters can only be designed according to the lowest harmonic frequency. It will inevitably lead to the reduction of output power quality

When the hysteresis loop width is large, the switching frequency is low at this time, and the requirements for switching devices are not high, but the following error will increase accordingly; on the contrary, when the hysteresis loop width is small, although the following error decreases significantly , but at the same time, the fixed hysteresis width may make the switching frequency too high, and in severe cases, it may even exceed the maximum operating frequency allowed by the switching device and damage it

The advantage of this method: the frequency is fixed, and it is easy to realize the filter design; the disadvantage is that the switching frequency is too high or the situation of continuous non-action occurs at the voltage zero crossing point and the voltage peak value, and the current tracking effect is not very ideal

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