Hybrid filter for an alternating current network

• US 6,385,063 B1
• Filed: 12/22/2000
• Issued: 05/07/2002
• Est. Priority Date: 06/23/1998
• Status: Expired due to Fees

• Current Assignee: Siemens AG
• Original Assignee: Siemens AG
• Inventors: Sadek, Kadry, Pereira, Marcos
• Primary Examiner(s): Patel, Rajnikant B.
• Application Number:
  US09/720,337
• Time in Patent Office: 501 Days
• Field of Search: 363/39, 363/37, 363/38, 363/40, 363/41, 363/44, 363/45, 363/48, 307/105, 307/107, 323/207, 323/210
• US Class Current: 363/39
• CPC Class Codes: H02J 3/01 Arrangements for reducing harmonics or ripples
• CPC Class Codes: Y02E 40/40 Arrangements for reducing harmonics

Abstract

The invention relates to a hybrid for an AC mains system, with the hybrid filter having a passive and an active filter which are electrically connected in series, and with the active filter having a voltage source. According to the invention, a tuned filter, which is tuned to the rated frequency of the AC mains system, is electrically connected in parallel with the active filter. This results in a hybrid filter for an AC mains system, whose active filter is not loaded by the fundamental current component.

Claims

1. A hybrid filter for an AC mains system, the hybrid filter having a passive and an active filter which are electrically connected in series, and the active filter having a voltage source, wherein a tuned filter, which is tuned to the rated frequency of the AC mains system, is electrically connected in parallel with the active filter.

2. The hybrid filter as claimed in claim 1, wherein a regulator arrangement, is connected on the input side to two current transformers and is connected on the output side by means of an adder to a control input of the voltage source of the active filter, with one of the two current transformers being associated with the active filter, and with the other being associated with the passive filter.

3. The hybrid filter as claimed in claim 1, wherein a double filter is provided as the passive filter.

4. The hybrid filter as claimed in claim 1, wherein the active filter has a pulse-width-modulated pulsed-current converter, which is linked on the DC side to a capacitor bank and is linked on the AC side to a transformer, and has a regulating device which is connected on the output side to a control input of the pulsed-current converter.

5. The hybrid filter as claimed in claim 2, wherein the regulator arrangement has a reference oscillator, a demodulator, a low-pass filter, a regulator and a modulator, and the demodulator is linked on the input side to an output of the current transformer of the active filter, and the reference oscillator is linked on the input side to an output of the current transformer of the passive filter, and a first output of the reference oscillator is connected to a further input of the demodulator, and a second output of the reference oscillator is connected to a further input of the modulator, and one output of the demodulator is linked by means of the low-pass filter to one input of the regulator, which is connected on the output side to one input of the modulator.