An active power filter and its peak current limiting method

Abstract

The invention discloses an active power filter and its peak current limiting method. The active power filter of the invention includes a power unit, a current transformer, a Hall sensor, a controller and a peak limit circuit; The transformer is connected to the Hall sensor, and the harmonic current that needs to be compensated is calculated according to the current of the nonlinear load. Closed-loop adjustment, and finally according to the harmonic current that needs to be compensated, generate a corresponding PWM drive signal; the PWM drive signal is transmitted to the power unit after passing through the peak limit circuit, so that the drive power unit generates a corresponding output current, and the peak limit circuit is based on Hall The feedback current of the sensor limits the pulse width of the passing PWM drive signal. Even when the peak value is overcurrent, the invention does not stop the protection, does not cause device damage and can ensure maximum compensation of harmonic current.

Description

Technical field [0001] The present invention relates to the technical field of active power filters, in particular to an active power filter and a peak current limiting method thereof. Background technique [0002] The active filter is mainly used to compensate the harmonic current of the system. When the harmonic current capacity of the system is large but the capacity of the active filter is insufficient, the compensation capacity will reach the maximum capacity of the active filter. The proportion of high-order harmonics in the current system is also large, resulting in the capacity that needs to be compensated not only for the effective capacity, but also for the instantaneous capacity. In particular, the instantaneous current spike can easily cause the system to exceed the capacity and protect itself. [0003] At present, most self-protection methods are to perform peak over-current shutdown protection on the output current of the active power filter power output unit to avoid...

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Problems solved by technology

[0004] The purpose of the present invention is to overcome the above-mentioned deficiencies in the prior art, aiming to solve the problem that the harmonic current of the system cannot be compensated normally when the output current of the power output unit of the active power filter is protected by peak overcurrent shutdown Problems that cause greater losses to users

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