Four switch Three-Level Soft Switched Converter

IJSRD - International Journal for Scientific Research & Development| Vol. 3, Issue 11, 2016 | ISSN (online): 2321-0613

Four Switch Three-Level Soft Switched Converter Vijay Dubey1 C. S. Sharma2 M.E (EMD) 2Associate Professor 1,2 Department of Electrical Engineering 1,2 SATI Vidisha (M.P) 1

Abstract— A Three-level, constant-frequency, isolated converter which employs a coupled in conductor to achieve zero-voltage switching. Three level DC converter has been introduced hare. This converter consists of four switches, which give the two levels of the DC output i.e. 200V each. It will also give another level of DC output at inductor side which is 45V DC. We take the input 750V and it split three different levels of DC output. The entire model simulated using power system block set in MATLAB 2013.

Key words: power factor correction, boost rectifier, ZVS,ZCS Abbreviations: Cc-Coupling capacitor, Ia, Ib and Ic are inductor currents,I1, I2 and I3 are input currents I. INTRODUCTION In this paper introduce SIMULINK model design, different elements specification like capacitors, inductors, transformer, and diode specifications switches etc.

In this paper, a new three-level ZVS converter is introduced.

Proposed 3-level ZVS converter apply a coupled inductor on primary side to achieve ZVS in entire line and load range.

Since this coupled inductor does not appear as a series inductance in load current path, it does not cause a loss of duty cycle or severe voltage ringing across output diode.

As a result, proposed circuit exhibits an increased conversion efficiency. Performance of proposed three-level converter circuit was experimentally verified on a 1-kW prototype circuit that was designed to operate from a 750V input and deliver 48V output voltage.

II. PROPOSED CIRCUIT Fig. 1 shows a circuit diagram of proposed three-level softswitched dc-dc converter that employs a coupled inductor on primary side to extend ZVS range of primary switches with a minimum circulation energy and conduction loss. to center-tapped secondary of transformer.

Three-level converter in Fig (1) consists of a series connection of four primary switches through, rail-splitting capacitors and, “flying capacitors” and isolation transformer TR, and coupled inductor. In this circuit, load is coupled to converter through a full-wave rectifier connected In addition, clamping diodes and are used to clamp voltage of outer switches and, respectively, to after switches are turned off.

Fig. 1: Three Switch Boost Power Converter The clamping diodes are different from rectifier diode. Now very high snubber resistance is use in these diodes. Diode DC1 and DC2 are use as clamping diode in this circuit. It can be seen that diodes DC1, DC2 should have a voltage blocking capability of 750V, and should be able to conduct a peak current of 250V. Similarly mosfets should be able conduct a peak current of with voltage blocking capability of 75V. The metal-oxide semiconductor field-effect transistor (MOSFET) is a semiconductor device controllable by gate signal (g > 0). The MOSFET device is connected in parallel with an internal diode that turns on when MOSFET device is reverse biased (Vds < 0) and no gate signal is applied (g=0). The model is simulated by an ideal switch controlled by a logical signal (g greater then 0 or g = 0), with a diode connected in parallel.

The MOSFET device turn on when a positive signal is applied at gate input (g > 0) whether drainsource voltage is positive or negative. If no signal is applied at gate input (g=0), only internal diode conduct when voltage exceeds its forward voltage Vf with a positive or negative current flowing through device, MOSFET turn off when gate input becomes 0. If current I is negative and flowing in internal diode (no gate signal or g = 0), switch turns off when current I becomes 0.

The on state voltage Vds varies 1) Vds = Ron*I when a positive signal is applied at gate input.

2) Vds = Rd*I-Vf +Lon*dI/dt when anti parallel diode is conducting (no gate signal).

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Four Switch Three-Level Soft Switched Converter (IJSRD/Vol. 3/Issue 11/2016/003)

III. THREE SWITCH BOOST POWER A. Converter Modal and Analysis Earlier ZVS boost converter is introduced that gives idea to design Simulink model. For achieving high voltage performance by rectifier is not easily done, but analyzing SIMULINK model, gave performance same by using soft switching.

The three phase three level converter SIMULINK modal shows in figure 2. In this model three capacitors connected in Y (star connection) and this connection create a neutral point.

VAN − (1 − 2D)Vo1 TS 2L1 When the diodes DC2 and DC3 are forward biased than the current iL2 and iL3 are simultaneously increases linearly. −VAN + (1 − 2D)Vo2 iL2 = TS 2L2 iL1 =

IV. RESULTS

Fig. 3: Switching pulses for the MOSFET switches

Fig. 2: Proposed system for model on MATLAB The three phase three level thd zvs pfc boost rectifier SIMULINK model shows in figure 3 . In this model C1,C2 and C3 are the three capacitors connected in Y (star connection) and this connection create a neutral point . The virtual connection also connected with middle of pairs of switches and middle of output capacitors, which helps the balancing the output voltage.

By connecting the neutral point to the middle of the pair of switches, directly achieves the three input. Clamping capacitor Cc connected across the switch. CO1 And Co2 the output capacitors. For clamped inductor take two winding linear transformer CR capacitor use for reset the inductor current connected serially with pair of switches.

By figure 4(a) and (b) saw when the switch S1 and S2 on inductor current iL1 flows from inductor L1 , S1 and S2 the io1 flows through Vo1 and switches capacitor Vcc will charged. After some time switch S2 will turned off then than the Vcc going to discharged and current flows from S 2, S3. the measured current peak of iL1 is equal to VAN/L1.

After some time the switch S1 also off. After some delay the switch S3 and S4 are on fig 4(c) and (d). This phenomenon actually for the negative half cycle for the rectifier. At this time current iL2 and iL3 flows through to the inductor L2 and L3 and also the current going to the Vo2side.

When the diode DC1 is forward biased than the current iL1 decreases linearly then the current calculated by equation,

Fig. 4: (a)

Fig. 4: (b) Fig. 4: analysis of the model fig-4(a) and 4(b) for the switch operation of S1, S2, S3 and S4

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Four Switch Three-Level Soft Switched Converter (IJSRD/Vol. 3/Issue 11/2016/003)

Figure 3 shows the switching for Mosfets switches.

Hare three switches use, S1, S2, S3 and S4. Figure 4 shows the operation of these switches. After some delay the S4 switch will ON and at this time S3 will ON for some instantaneous of time and then it will be OFF.

Figure-6 shows the output power at full load in voltage 40VL-L. having 96% of efficiency.

V. CONCLUSION A new isolated, constant-frequency, three-level ZVS converter which employs a coupled inductor on primary side to achieve ZVS in a wide range of load current and input voltage with reduced circulating energy and conduction losses has been described.

Since this coupled inductor does not appear as a series inductance in load current path, it does not cause a loss of duty cycle or severe voltage ringing across output rectifiers.

The operation and performance of proposed circuit was verified by MATLAB simulation The total performance done by MATLAB simulink at 340 line to line voltage .Achieved 96% efficiency with full load.

REFERENCES

Fig. 5(a): output voltage waveforms at half of full load 220VL-L The results of the matlab simulink model was evaluated on 40VL-L voltage where the C1,C2 and C3 are 2.2µF.D1-D6 taking the simple ratings and the diodes D7 and D8 having high snubber value.

Fig. 5(b) :output voltage waveforms at half of full load 220VL-L Figure-5 shows the output voltage waveforms at two half of full load 220VL-L

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Fig. 6: Measured DC output at 40VL-L input voltage

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Four Switch Three-Level Soft Switched Converter (IJSRD/Vol. 3/Issue 11/2016/003)

[12] J.W. Kolar, H. Ertl and F.C. Zach, “A Comprehensive Design Approach for a Three-Phase High-Frequency Single-Switch Discontinuous-Mode Boost Power Factor Corrector Based on Analytically Derived Normalized Converter Component Ratings,” in IEEE Transactions on Industry Applications, Vol. 31, No. 3, May/June 1995, pp. 569-582. References 225 [13] J.W. Kolar, H. Ertl and F.C. Zach “Space Vector-Based Analytical Analysis of the Input Current Distortion of a Three-Phase Discontinuous-Mode Boost Rectifier System,” in PESC 1993, pp. 696-703.

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