Interlaced hysteresis loop tracking and compensating current generator and control method thereof

Abstract

The invention relates to an interlaced hysteresis loop tracking and compensating current generator and a control method thereof. The invention adopts two inverse bridges to work in parallel, the two inverse bridges are driven by a hysteresis loop tracking and controlling method, and comparing units of two corresponding sets of hysteresis loops track the same command signal, however, the phases of output driving impulses are mutually intersected at 180 degrees. In the compensating current which is outputted by the two inverse bridges through an inductor, the effective compensating current components which correspond to the command signal are the same and are mutually overlapped after parallel connection, and output total electric current is twice as much as the output electric current of the single inverse bridge; and in the compensating current which is outputted by the two inverse bridges through an inductor, the high-frequency ripple current components generated by the tracking and the modulating of the hysteresis loop are approximately to have the same amplitude, are inverse, and can be mutually offset, thereby obviously reducing the ripple components in the output total electric current. The invention also can reduce the effective value of the ripple current in a direct current circuit to be at about 46% of the common technique, and synthetically improves the indexes of the electric current tracking speed, the output ripple current, the loss, the efficiency and the cost, etc.

Description

Technical field [0001] The present invention involves a stagnant -loop tracking compensation current generator and its control method, especially a kind of inactivation of compensation current generators and its harmonious stagnation circulation of harmonic and non -exercise currents in the power system and itsControl Method. Background technique [0002] The use of modern power electronic technology to actively compensate the harmonic and non-power current in the power system, which is an important content in the development of flexible transmission technology (FACTS) and user power technology (D-Facts) developed in recent years.For example, active electric filter (APF) and static synchronization compensator (STATCOM) are compensated current generators made of modern power electronic technology. [0003] In order to obtain high -efficiency and high -speed effects, such compensation current generators often use stagnation tracking methods or PWM modulation methods to generate hig...

AI Technical Summary

Problems solved by technology

[0005] 1) The compensation current generated by the known hysteresis tracking compensation current generator contains a relatively high intensity ripple current, which causes electromagnetic interference

To reduce the ripple current level, you need to use a smaller δ value, but this will increase the switching frequency of the inverter bridge, resulting in increased losses, and the switching frequency is limited by the switching speed of semiconductor power devices, it is impossible to increase too much; if Using an output inductor with a large inductance can reduce the switching frequency of the inverter bridge, but it will limit the maximum change rate of the output current, affect the speed and effect of tracking compensation, and increase the volume, weight and cost of the inductor

A trade-off between several limiting factors is therefore required, resulting in limitations on the technical performance of the compensation current generator

[0006] 2) When the compensation current generator is working, there is also a large ripple current in the DC circuit of its inverter bridge, resulting in fluctuations in the DC bus voltage and large losses in the DC bus capacitor

In order to ensure the normal operation of the device, a large DC bus capacitor is required, which increases the volume, weight and cost of the device

[0007] 3) The interleaved driving method of two inverter bridges can effectively reduce the output ripple current and the ripple current in the DC circuit, but the known interleaved driving method is only suitable for PWM modulation with a fixed switching frequency of the inverter bridge, and for Ring tracking compensation current generator, because the switching frequency and phase of the inverter bridge are constantly changing, it is impossible to use the known technology to realize the interleaved drive of the two inverter bridges

However, the method disclosed in the patent application 200910019887 cannot be applied to the hysteresis tracking modulation mode in which the switching frequency is constantly changing, which restricts the further improvement of the technical performance of the compensation current generator adopting the hysteresis tracking modulation mode

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