Hybrid Active Filter Matlab

Abstract

A novel hybrid active power filter (NHAPF) that can be adopted in high-voltage systems is proposed in this paper. The topological structure and filtering principle of the compensating system is provided and analyzed, respectively. Different controlling strategies are also presented to select the suitable strategy for the compensation system. Based on the selected strategy, the harmonic suppression function is used to analyze the influence of system parameters on the compensating system with MATLAB. Moreover, parameters in the injection branch are designed and analyzed. The performance of the proposed NHAPF in harmonic suppression and reactive power compensation is simulated with PSim. Thereafter, the overall control method is proposed. Simulation analysis and real experiments show that the proposed NHAPF exhibits good harmonic suppression and reactive power compensation. The proposed compensated system is based on the three-phase four-switch inverter, which is inexpensive, and the control method is verified for validity and effectiveness.

Key words: Harmonics suppression, reactive power compensation, active power filter, passive filter

I. Introduction

Nonlinear loads and equipment in the consumer side, such as adjustable speed drives, arc furnaces, and controlled and uncontrolled rectifiers, cause problems in electrical systems

– By Polluting The Power Distribution System With

harmonics. Utilities frequently encounter harmonic-related problems, such as harmonic interactions between utility and loads, reduced safety operating margins, reactive power, harmonic resonance, higher transformer and line losses, and capacitor failure caused by overloading –.

Frequently used harmonic suppression equipment includes passive power filters (PPFs), active power filters (APFs), and

Hybrid Apfs (Hapfs). Ppf Is Used To Eliminate The

designated order of harmonic currents and compensate reactive power. However, PPFs have many disadvantages in practical applications, such as bulky and heavy devices and harmonic amplification caused by resonances –. APFs have been developed to overcome such problems –.

Or

medium-voltage situations because they lack high-capacity

Semiconductor Components. By Contrast, Hapfs Can

eliminate harmonic currents in high- or medium-voltage

Situations

–.

Are

composed of active and passive components in series and/or

In

parallel.

The

compensation characteristics of PPFs and reduce the voltage and/or current ratings (costs) of APFs. A novel hybrid APF (NHAPF) with a high-voltage rank is proposed in this paper. The active section of the NHAPF has insignificant fundamental voltages with such structure. This paper is organized as follows. Section II introduces the system structure of the NHAPF, as well as the filtering principle. Section III analyzes three controlling strategies.

One of these strategies is selected to be the optimum controlling strategy. Section IV evaluates the NHAPF performance. The harmonic magnification characteristic and injection branch are analyzed in detail by using MATLAB.

The Harmonic Suppression Performance Of Nhapf Is

analyzed under different conditions, such as the influence of the controlling magnification factor and grid inductor and PPF out of resonance. Section V analyzes the simulation and experiment results to verify the feasibility and validity of the proposed NHAPF and the controlling strategy. Finally, Section VI concludes.

Manuscript received Nov. 26, 2012; revised May 7, 2013 Recommended for publication by Associate Editor Sung-Yeul Park. *School of Information Science and Engineering, Central South Fig.1. Topology structure of NHAPF.

Principle

A simple-structured NHAPF that exhibits both harmonic suppression and reactive power compensation in a large

Power System Is Proposed In This Paper. The Nhapf

structure is shown in Fig. 1. The active section exhibits low fundamental voltages because the seventh PPF is connected to the active section. Thus, the requisite inverter capacity is also low. Parallel inductor L is connected to the second side of transformer T in parallel. Thus, the active section has a light lash, and the system can maintain stable when the system is power on or sudden change occurs in the grid voltage.

PPFs compose of the 5th, 7th, and 11th passive power filters. L0 is the output filtering inductor for the active section. The APF connects the second side of the transformer after connecting to the output filter L0 in series. Parallel inductor L is parallel to the second side of the transformer. The reactive power is compensated by the passive section, and the harmonic is suppressed by the active and passive sections.

That is, the 5th and 11th harmonics are suppressed by the passive section, whereas the other harmonics are suppressed by the active section. The 7th PPF is the injection branch.

The 7th PPF and inductor L share a grid voltage, thus enabling the active section to support low voltages and decreasing APF capacity. The compensation equipment can be used in a 10 KV grid.

The single-phase electrical model of the NHAPF in the harmonic field is shown in Fig. 2. The grid impedance is ZSh. The nonlinear load is considered the harmonic current source ILh. The active section is controlled as an ideal harmonic voltage source UC. ISh, IPh, and IFh are the grid, PPF, and injection branch currents, respectively. ZSh, ZPh, Z7h, ZLh, and ZL0h are the impedance of the grid, 5th and 11th PPFs, 7th PPF, parallel inductor L, and output filter, inverter, and transformer, respectively. ZLh and ZL0h are the equivalents in the first side of the transformer.

Equations Are Derived:

Fig. 2. Single-phase electrical model of the NHAPF in the harmonic field.

. Equation (2) Shows

that the grid harmonic current can be suppressed by controlling the voltage source UC of the inverter.

Iii. Controlling Strategy Analysis

The working performance of the compensating equipment varies with different controlling strategies. The active section of the NHAPF can be controlled as a harmonic voltage source or current source. The active section is equivalent to the short circuit for the fundamental voltage if the active section is controlled as a harmonic voltage source. Even if the

Is Small,

the fundamental currents will still flow into the active section through the 7th PPF. However, if the equivalent fundamental

Z 0 Is Significantly Greater

than the fundamental impedance of the parallel inductor

Through The 7Th

PPF. The harmonic impedance of the active section ZL0h

Z 0 . Thereafter, Zl0H Shares More

harmonic voltage, thus decreasing the harmonic suppression capability of the compensating equipment. That is, a contradiction exists between improving the harmonic suppression capability and decreasing the fundamental current in the active section if the active section is controlled as a harmonic voltage source.

If the active section of the NHAPF is controlled as a harmonic current source, the output current will contain insignificant values of the fundamental current component

Will Flow Into The

parallel inductor (Fig. 3). Thus, the fundamental voltage on the active section is

(3)

If the active section is controlled as the harmonic current

Z 0 And Its Harmonic Impedance Will Be Small. The

active section only has a small harmonic voltage, and the capacity of the active section is decreased.

Z 0 Will Not

affect the harmonic current from the active section, and the harmonic suppressing capability of the compensating equipment will not be affected.

Thus, the active section of the compensating equipment is controlled as the harmonic current source in this paper. Three

0 Is Ignored

because of its insignificant value. Equation (2) can be

. (4)

The controlling strategy of the NHAPF can be designated by

Analyzing Different Controlling Strategies:

(1) The active section is controlled as the grid harmonic

, Where K Is The Controlling Magnification

factor. Thereafter, the harmonic suppressing function is

,

Fig. 5. Single-phase equivalent circuit of f2.

. (6)

The single-phase equivalent circuit of the NHAPF (Fig. 4) is obtained according to Equation (6). This controlling strategy can increase the adjustable

Harmonic Impedance In The Grid. The Grid Harmonic

impedance can then be enlarged by controlling the APF, which allows the load harmonic currents to flow into the filtering branches instead of the grid.

(2) The active section is controlled as the load harmonic

. (8)

The single-phase equivalent circuit of the NHAPF (Fig. 5) is obtained according to Equation (8).

The Controlling Strategy Improves The Harmonic

impedance characteristic of the PPF and increases the grid harmonic impedance by controlling the APF, thus enhancing the filtering effect.

(3) The active section is controlled as the load harmonic

The Single-Phase Equivalent Circuit Of The Nhapf

(Fig. 6) is obtained according to Equation (10) .

The Controlling Strategy Improves The Harmonic

impedance characteristic of the PPF by controlling the APF.

The Load Harmonic Currents Can Then Be Eliminated

theoretically. However, difficulty arises when the grid contains high harmonic voltages. Fig. 3. Fundamental single-phase equivalent circuit that controls the active section as a harmonic current source.

Fig. 4. Single-phase equivalent circuit of f1. 6. Single-phase equivalent circuit of f3.

A. Harmonic Magnification Characteristic

The active section improves the PPF performance even though the NHAPF contains capacitors and inductors. The levels of improvement vary with different controlling strategies. The harmonic current magnification factor is defined as the ratio of the grid harmonic current and load harmonic current. Three harmonic current magnification factors that correspond to the three controlling strategies are obtained according to Equation (2).

, The

harmonic current magnification factor is expressed as

, The

harmonic current magnification factor is defined as the

. (13)

Equations (11), (12), and (13) are simulated by using MATLAB. The simulation parameters of NHAPF are shown in Table 1.

=

. The simulation results are shown in Fig. 7. Coordinates Z, X, and Y represent the magnification factor, harmonic order n, and controlling magnification factor K, respectively.

The probability of resonance caused by the PPF and the grid can be decreased when the active section is controlled as

=

(Fig. 7). The other two controlling strategies can cause resonance in the system.

B. Injection Branch Analysis

The selection of the 7th PPF as the injection branch is first analyzed with the harmonic current magnification factor.

Equation (11) Is Selected As The Harmonic Current

magnification factor according to the above analysis. The 5th, 7th, and 11th PPFs act as the injection branch, and the corresponding harmonic suppression functions are simulated.

The controlling magnification factor is set to 10.

=

.

Z11 Denote The Equivalent

harmonic impedances of the 5th , 7th, and 11th PPFs, respectively. The baud corresponding to the harmonic current magnification factor is shown in Fig. 8.

. The Baud Corresponding To The

harmonic current magnification factor is shown in Fig. 9.

. The Baud Corresponding To The Harmonic

current magnification factor is shown in Fig. 10. The simulation results show that all order harmonics are suppressed well, particularly the high-order harmonics, when the injection branch is the 5th or 7th PPF. The 7th harmonic is magnified when the injection branch is the 11th PPF.

Considering that the 7th harmonic component is lower than the 5th harmonic component, the 7th PPF is selected as the injection branch. Comparisons of the NHAPF structure with the injection branch by using the 5th PPF show that the NHAPF structure requires fewer capacities than the APF. In the NHAPF structure, the 5th and 11th harmonic currents are suppressed by the PPFs, and the 7th and higher harmonic currents are suppressed by the APF.

The single-phase equivalent circuit corresponding to the capacitive reactive compensating branch that uses the 7th PPF is shown in Fig. 11 when the grid voltages show an abnormal phenomenon.

In Fig. 11, L1 is the equivalent first-side inductor of parallel inductor L connected to the second side of the transformer. u(t) is the abnormal voltage (e.g., voltage drop).

If the grid voltage decreases, the decreasing voltage has the same frequency and opposite phase as the grid voltage. The frequency and phase of the decreasing voltage is added to the grid voltage. The decreasing voltage can be expressed as

, (14)

where A denotes the level of voltage drop in the grid. U and

0

w indicate the effective value and frequency of the grid voltage, respectively. Based on Fig. 11, the following

. (15)

Fig. 8. Harmonic suppression performance when the injection branch is the fifth PPF. 9. Harmonic suppression performance when the injection branch is the seventh PPF.

Fig. 10. Harmonic suppression performance when the injection branch is the seventh PPF. 11. Single-phase equivalent circuit corresponding to the capacitive reactive compensating branch.

Deployment In Out-Of-Position Situations

D. Bendjaballah1, A. Bouchoucha1, M. L. Sahli1,2* and J-C. Gelin2

Abstract

Side-impact collisions represent the second greatest cause of fatality in motor vehicle accidents. Side-impact airbags have been installed in recent model year vehicle due to its effectiveness in reducing passengers’ injuries and fatality rates. In meeting these requirements, simulations of folding and deploying airbags are very useful and are widely used. The paper presents a simulation method for the deploying airbags using three materials in different working conditions. Finite element analysis is primarily used to evaluate this concept. In these simulations, the gas flow is described by the conservation laws of mass, momentum, and energy. The numerical results indicate that the FE method in this paper is capable of capturing airbag deploying process accurately.

Keywords: Airbag simulations, Out-of-position, Crash, Modeling, Out-of-position

Background

The passive safety of cars has become a very high prior- ity issue for the automotive industry. Today, there are not only one or two airbags in a car; certain models have ten times more than that. With the increasing usage of airbags, the number of accidents where the airbag itself can cause an injury to the occupant also increases

(Augenstein Et Al. 2003; Gabauer And Gabler 2010;

Audrey et al. 2011). As is well known, safety belts are also now devices designed to provide protection to the users of vehicles during crash events, minimizing the loads necessary to adapt their movement to the move- ment of the car (Freesmeier and Butler 1999; Schmitt et al. 1997). In general, the seat belt is designed to restrain the occupant in the vehicle and prevent the

Occupant From Having Harsh Contacts With Interior

surfaces of the vehicles. The airbag acts to cushion any impact with vehicle structure and has positive internal pressure, which can exert distributed restraining forces over the head and face. As a safety component of auto- mobile, an airbag decreases occupants’ injury likelihood effectively in case of an accident (Ruff et al. 2007). These safety elements can reduce the death rates on the roads, and its protection effects have been widely approved (Crandall et al. 2001; Teru and Ishikawa 2003). With computational tools such as finite element methods designed for dynamic contact problems, crashworthiness simulations can now be used with reliable accuracy to evaluate occupant protection in various collision condi- tions with safety metric/parameters such as acceleration, head injury criteria, intrusion distance, intrusion vel- ocity, and neck forces (neck injury risk or whiplash).

Thus, new types of airbag products are being developed to handle different collision scenarios.

Become Standard Equipment On Most New Passenger

vehicles (Braver and Kyrychenko 2004; Teng et al. 2007; Yoganandan et al. 2007). The airbag cushion is com- posed of a woven fabric which is rapidly inflated during a car crash. The airbag dissipates the passenger’s kinetic energy thereby reducing injury through biaxial stretching of the fabric bag and escaping gas through vents. There- fore, the performance of the airbag is greatly influenced by the mechanical properties of the fabric. Generally, air bags are designed to deploy in a crash that is equivalent to a vehicle crashing into a solid wall at 8 to 14 mph.

Air bags most often deploy when a vehicle collides with another vehicle or with a solid object like a tree. There are various types of airbags: frontal, side-impact, and curtain airbags. In general, the passenger side airbags are usually larger than the driver airbags (see Fig. 1).

Besançon, France

© The Author(s). 2017 Open Access This article is distributed under the terms of the Creative Commons Attribution 4.0 International License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made.

Bendjaballah et al. International Journal of Mechanical

Doi 10.1186/S40712-016-0070-2

Extensive studies have shown that the airbag deploy- ment in load cases consists of two occupant loading phases: a punch-out effect where the airbag bursts out of its container with the airbag and airbag module cover accelerating towards the occupant and a second loading phase during which the airbag is taking on its deployed shape and volume (membrane-loading effect). Bankdak et al. (2002) developed an experimental airbag test system to study airbag-occupant interactions during close proximity deployment. The results provided insight for simulating the effect of inflation energy and mass flow on target response. Bedard et al. (2002) found that while left-side (driver-side) impacts accounted for only 13.5% of all crashes, the fatality rate among these

Crashes Was 68.3% In Comparison To Front Impact

(48.3%), right-side impact (31.3%), and rear impact (38.4%). These studies underscore the importance of oc- cupant safety during side-impact collisions. In the last years, the current market requested to reduce the time and cost airbag development. In order to achieve this result, virtual simulations play an important role since they allow to minimize the number of experimental tests (Pei et al. 2013; Cao et al. 2014). Several simulation models of airbag were established (Wang et al. 2007). It is feasible to optimize the parameters of airbag deploy- ment using simulation technology. Experimental and numerical studies have quantified injury risks to close- proximity occupants from deploying side airbags. These studies have focused on the prevention of the most ad- verse effects of airbag deployment (Duma et al. 2003).

Other studies have proposed airbag characteristics to minimize particular biomechanical responses (Haland and Pipkorn 1996). In a more recent study, Marklund and Nilsson (2003) compared deformation patterns with experimental data as well as the computational costs associated with three different airbag deployment simu- lation methods; they concluded that the SPH method is relatively inexpensive and produces incremental deform- ation patterns that compare most closely to the experi- mental results. The process of inflation of an airbag is one of the determining factors in saving lives. The duration from the initial impact of the crash to the full inflation of an airbag is about 40 ms, and during this time, the airbag goes from being in a folded state to a fully inflated state, with a high internal pressure. After achieving this state, the airbag begins to deflate, thus providing a nice cushion for the body impacting it.

Ideally, the person in the crash should come into contact with the airbag at this time. In the present study, a large volume passenger side airbag model is developed to handle different collision scenarios. The main aim is evaluate the performance of deploying of passenger side airbag using finite element methods (FEM).

Materials

The tensile specimens were made in different airbags (P: Peugeot, R: Renault, and VW: Volkswagen) with a length of 200 mm long and a width of 40 mm. Table 1 shows the mechanical properties of the airbag.

Tensile Tests

To determine the mechanical properties of the material of airbag used in the test pieces, tensile tests were performed on Lloyd EZ20 universal testing machine in Constantine. These tests were conducted using rect- angular samples. The axial force and axial displacement acquired during a test are converted into stress and the strain in order to be used for the fabric material model.

The continuous recording of the stress-strain data was performed during both the load and unload phases. A minimum of five samples were made in order to check the repeatability of the measurements. All the data was collected by using a PC-based data acquisition system and analyzed by commercial software. The picture frame test device that is made for this study is shown in Fig. 2.

Fig. 1 a Frontal and side airbags. b Oblique view of facet occupant model in sitting posture following airbag deployment (Lim et al. 2014)

0.150

Bendjaballah et al. International Journal of Mechanical and Materials Engineering (2017) 12:12

Page 2 Of 9

Figure 3 shows the stress-strain relationship of the airbag sample under axial tensile loads. The results are showing a linear increase in extension with the increas- ing stresses. This is an expected output and it confirms with the theoretical behavior of a sample subjected to tensile stress. The rupture strain values for different airbags (R/P/VW) were 0.322, 0.441, and 0.472, respect- ively. The measured elastic parameters (i.e., Young’s modulus E and initial yield strength) and Poisson’s ratio are summarized in Table 2. The tensile tests of the woven fabrics can show differences on mechanical prop- erties because woven fabrics can resist in-plane shear loads once the yarn lock-up angle has been reached. The differences of material property on material direction can affect the shape of fully deployed bag (see Fig. 3b).

Theoretical Background

Numerical simulations of airbags use very complex and techniques such as an orthotropic model to identify the mechanical behaviors during the airbag inflation and the fluid mechanics (gas flow) to describe the inflator gas flow (pressure gradient) and improve the representation of the pressures within the airbag. To model the airbag as an orthotropic model, three material constants have to be provided. Assuming a plane stress condition, the

Ð1Þ

where σ is the normal stress and τ is the shear stress, the subscript refers to the principal material directions, i.e., the fill and warp directions. Also, ε and γ are the strain components. The material elastic constants Qij are

Ð2Þ

where E1 and E2 are the Young’s modulus in the fill and wrap directions and G12 is the shear modulus of the fabric material. νij is the Poisson ratio of the material.

The gas exerts a pressure load on the airbag causing it to expand. This expansion puts the airbag under tensile stress lowering the expansion rate. In this study, heat conduction and heat transfer is not taken into account.

Fig. 2 A photograph of Lloyd EZ20 universal testing Fig. 3 Stress versus strain using Lloyd EZ20 machine for a three different airbags at 0° and 90° and b VW airbag test specimens at

Different Angles

Table 2 Physical and mechanical properties of the airbag

Page 3 Of 9

In the deployment of an airbag, an inflator supplies high velocity gas into an airbag causing it to expand rapidly. The gas inside the airbag is assumed to be ideal, to be of constant entropy, and to satisfy the equation of state:

Ð3Þ

Here p, ρ, and e are respectively the pressure, density, and specific internal energy, and γ is the ratio of the heat capacities of the gas. The gas flow is described by the conservation laws for mass, momentum, and energy that

Ð4Þ

here, V is a volume, A is the boundary of this volume,

N Is The Normal Vector Along The Surface A, And U

denotes the velocity vector in the volume. Applying Bernoulli’s equation in the case of an ideal gas with

Ð5Þ

Here, the subscript ex denotes quantities at the throat of the tube. Furthermore u, p, and ρ denote the quan- tities inside that part of the tube that is supplying mass.

Materials And Boundary Conditions

The airbag system mainly consists of three parts: the airbag itself, the inflator unit, and the crash sensor or diagnostic unit. Thus, to study the behavior of the airbag using FE simulations, we need to have an FE model of the airbag in the folded position. A FE model of the airbag was used to simulate the test condition as shown in Fig. 5. LS-DYNA® material model FABRIC (MAT_34) is used to simulate the airbag material. It is a variation of the layered orthotropic material model. Additionally, in the LS-DYNA® material model, fabric leakage can be accounted for. However, for this CAB material, the leak- age is almost negligible and therefore no leakage is specified. The mechanical properties can be determined from the physical test. Typical material properties for airbag fabrics are taken as given in Chawla et al. (2004a) (Table 3). These properties are used to simulate inflation process of airbag (see Table 1). The car dashboard is modeled as the rectangular thin plate using a MAT_RI-

Gid Material, And The Degrees Of Freedom Are Con-

strained in all the directions. The similar properties of thermoplastic polymer are assigned for contact purposes. The porosity of the fabric is assumed zero. The nitro- gen gas is taken for inflating the airbag. Properties of nitrogen gas and initial bag conditions are shown in Table 4. The example on which we perform the study is a typical passenger side airbag. The geometric de- tails have been measured from a commercially avail- able airbag. The initial state of the airbag is a closed rectangular whose sides are to be finished to 482 × 635 mm2 and is shown in Fig. 4.

Table 3 Material properties of airbag and rigid plate used in FE

–

Table 4 Initial values used for FE simulation of the swelling of

3.33 × 10−4

Fig. 4 The initial airbag geometry in the form of a rectangular Bendjaballah et al. International Journal of Mechanical and Materials Engineering (2017) 12:12

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