Series Active Filters — Spice Simulation

Balázs Tóth, Zoltán Puklus Széchenyi István University, H-9026 Győr Hungary, Egyetem tér 1

puklus@sze.hu

Abstract - Active filters are known as the best tools for harmonic mitigation as well as reactive power compensation, load balancing, voltage regulation, and voltage flicker regulation on the power lines. To introduce the operation of active filters in education, it is a good method to use a software, named SPICE. It is a good choice, because it has a high level of objects for simulation, and good presentation objects for visualizing the results. Students can easily change the parameters of the operation, and can see the its result instead of using real power electronics circuits. In this paper we would like to use a series active filter as the power factor corrector for a “capacitive input” circuit.

Keywords: Series active filters, SPICE, power factor corrector

I INTRODUCTION It is a basic power electronics circuit (Fig. 1). There is a

single-phase rectifier with a capacitive load. There is a “capacitive input” circuit. Using SPICE, we can visualize the input current and voltage and output voltage waveforms (Fig. 2.). Because the form of the source current is far-off the sinusoidal shape (Fig.2), this current has a lot of harmonics (Fig. 3)

Fig. 1

The rectifier circuit with capacitive load.

Fig. 2

Input and output voltage and input current waveforms (SPICE)

Fig. 3

Harmonics of input voltages and currents (V2, I1)

For the compensation of a capacitive input circuit, which has harmonics of input current the power factor corrector techniques named PFC techniques was developed. We would like to demonstrate that using the series active filter technique for compensation the result will be same.

An other method for AC/DC rectifier compensation, is to use a controlled rectifier, witch is based on the theory of circulation ac power between two ac sources.

In this paper we would like to demonstrate that using a series active filter, we can obtain he same result.

Our students can realize that various methods allow for the same results.

II ACTIVE FILTERS We can observe that in many cases the form of the

currents and the voltages are very different from the optimal sinusoidal forms.

Linear and nonlinear loads can draw no sinusoidal current. The rectifier, with a capacitive load, composes a nonlinear load. The nonlinearity increases, it the rectifier is of a controlled type.

Active filters are applicable to compensate current-based distortions such as current harmonics, reactive power, and neutral current. They are also used for voltage-based distortions such as voltage harmonics, voltage flickers, voltage sags, and voltage unbalances.

We remark that based on topology, there are two kinds of active filters: current source and voltage source active filters. If the DC energy storage devise is an inductor it is the current source active filter. In voltage source active filters a capacitor acts as the energy storage element.

From the point of view of energy transfer between the active filters and compensated circuit there are two categories: shunt active filters and series active filters. We use a series active filter (Fig. 4),

CINTI 2010 • 11th IEEE International Symposium on Computational Intelligence and Informatics • 18–20 November, 2010 • Budapest, Hungary

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noted VF . The compensation current (voltage) will be introduced in the circuit with a transformer.

Fig. 4 Single phase series source active filter ( AF )

III SIMULATION CIRCUIT We will use a half bridge converter to create the VF

(Fig. 5). For the introduction of VF voltage, there is the transformer 65/100. The bloc named “calculation of the compensation signal” can analyze the current of the source, and has to determine the structure and magnitude of the compensation voltage in the pulse with modulation (pwm) format. The half bridge converter will generate the compensation tension VF.

Fig. 5

Single phase rectifier with active filter

IV SIMULATON RESULTS

Using Spice simulation for voltage and current of the

source and the output voltage can be seen in Fig. 6, 7, 8.

Fig. 6

Results of SPICE simulation I

Fig. 7

Results of SPICE simulation II.(valtages)

Fig. 9

Results of SPICE simulation III.(harmonics)

Using the S, P and Q meters in SPICE program, obtained values for this power (Tab. 1.)

Tab. 1

Results of powers measurements S1 2739 VA Q1 -849 VAr P1 2587 W S2 2871 VA Q2 -195 VAr P2 2575 W S3 1327 VA Q3 -654 VAr P3 12,8 W

Fig. 10

Vector forms of powers

Fig. 11 (Real) Circulation of powers

B. Tóth and Z. Puklus • Series Active Filters — Spice Simulation

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V OBSERVATIONS-CONCLUSIONS - When we changed the DC (500 VDC) source with a

condenser in the output of the half bridge converter, the simulation the program terminated normally; the signal form remained the same.

- Tested circuit (the rectifier with active filter) is a little capacitive (see Tab.1)!

- Harmonics from the input current I1 (comp Fig. 3. ↔ 9.) disappeared nearly 100% (DPF1 = 0.94, DPF2 = 0,99, DPF3 = -0.04)

REFERENCES [1] Ali Emandi, Abdolhosein Nasiri, Stoyan B. Bekiarov;

Uninterruptuble Power Supplies and Active Filters; CRC Press; Boca Raton, London, New York, Washington, D.C.

[2] A. Fehér, Dr. Z. Puklus; Definition and the measurement of power factor; International Symposium of Hungarian Researchers on COMPUTATIONAL INTELLIGENCE and INFORMATICS CINTI’2007, pages 623-632, Budapest, Hungary, 2007.

[3] Agilent Technologies VEE program http://www.agilent.com/find/VEE

[4] SPICE simulation program 8.05 [5] B. Tóth, Dr. Z. Puklus, Dr. L. Hodossy: Introduction in the Spice

Simulation - Active Filters 5th International Conference on Interdisciplinary in Education June 17-19, 2010 Tallinn, Estonia

CINTI 2010 • 11th IEEE International Symposium on Computational Intelligence and Informatics • 18–20 November, 2010 • Budapest, Hungary

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B. Tóth and Z. Puklus • Series Active Filters — Spice Simulation

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