* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Download Paper Title (use style: paper title)
Spark-gap transmitter wikipedia , lookup
Josephson voltage standard wikipedia , lookup
Analog-to-digital converter wikipedia , lookup
Transistor–transistor logic wikipedia , lookup
Television standards conversion wikipedia , lookup
Crossbar switch wikipedia , lookup
Index of electronics articles wikipedia , lookup
Radio transmitter design wikipedia , lookup
Resistive opto-isolator wikipedia , lookup
Valve RF amplifier wikipedia , lookup
Operational amplifier wikipedia , lookup
Schmitt trigger wikipedia , lookup
Current source wikipedia , lookup
Integrating ADC wikipedia , lookup
Voltage regulator wikipedia , lookup
Power MOSFET wikipedia , lookup
Surge protector wikipedia , lookup
Current mirror wikipedia , lookup
Opto-isolator wikipedia , lookup
Power electronics wikipedia , lookup
International Journal of Enhanced Research in Science, Technology & Engineering ISSN: 2319-7463, Vol. 5 Issue 1, January-2016 A Novel Loaded-Resonant Converter for the Application of DC-to-DC Energy Conversions Lakshminarayana Gaddam1, Naga Bhanu Uddanti2, SivaSankar Gonuguntla3 1,2,3 Assistant Professor, EEE, VLITS, AP, INDIA ABSTRACT Among the many advantages that resonant power conversion has over conventionally adopted pulse-width modulation include a low electromagnetic interference, low switching losses, small volume, and light weight of components due to a high switching frequency, high efficiency, and low reverse recovery losses in diodes owing to a low di/dt at switching instant. This work presents a novel loaded-resonant converter for direct current (dc)-to-dc energy conversion applications. The proposed topology comprises a half-bridge inductor-capacitor inductor (L-C-L) resonant inverter and a bridge rectifier. Output stage of the proposed loaded-resonant converter is filtered by a low-pass filter. A prototype dc-to-dc energy converter circuit with the novel loaded-resonant converter designed for a load is developed and tested to verify its analytical predictions. The measured energy conversion efficiency of the proposed novel loadedresonant topology reaches up to 88.3%. Moreover, test results demonstrate a satisfactory performance of the proposed topology. Furthermore, the proposed topology is highly promising for applications of power electronic productions such as switching power supplies, battery chargers, uninterruptible power systems, renewable energy generation systems, and telecom power supplies. Keywords Electro Magnetic Interference (EMI), Pulse-width modulation (PWM), zero-current-switching (ZCS), zerovoltage-switching (ZVS) 1. INTRODUCTION Use of semiconductor power switches in power electronic technology has led to rapid development of this technology in recent years. The switching power converter plays a significant role in the power energy conversion applications. In particular, direct current (dc)-to-dc converters are extensively adopted in industrial, commercial, and residential equipment. These converters are power electronics circuits that convert a dc voltage into a different level, often providing a regulated output. Power semiconductor switches are the major conversion component of power energy systems. . Pulse-width modulation (PWM) is the simplest way to control power semiconductor switches. The PWM approach controls power flow by interrupting current or voltage through means of switch action with control of duty cycles. In practice, a situation in which the voltage across or current through the semiconductor switch is abruptly interrupted is referred to as a hard-switched PWM. Because of its simplicity and ease in control, hard switched PWM schemes have been largely adopted in modern power energy conversion applications. Modern dc-to-dc power converters must be small sized and light weight, as well as have a high energy conversion efficiency. A higher switching frequency implies smaller and lighter inductors, capacitors, as well as filter components of these converters. However, electromagnetic interference (EMI) and switching losses increase with an increasing Page | 1 International Journal of Enhanced Research in Science, Technology & Engineering ISSN: 2319-7463, Vol. 5 Issue 1, January-2016 switching frequency, ultimately decreasing the efficiency and performance of dc-to-dc power converters. To solve this problem, some soft switching approaches must operate under a high switching frequency. Zero voltage switched and zero current switched schemes are two commonly used soft switching methods, in which either the voltage or current is zero during switching transitions, which largely reduce the switching losses, EMI, and increase the reliability of the power converters. Fig .1 the proposed loaded-resonant converter. A soft switching dc-to-dc converter is constructed by cascading a resonant dc-to-ac inverter and a rectifier . dc input power is first converted into ac power by the resonant inverter; the ac power is then converted back into dc power by the rectifier. Among the existing soft switching converters, loaded-resonant converters are the most popular type owing to its simplicity of circuit configuration, easy realization of control scheme, low switching losses, and high flexibility for energy conversion applications. Depending on how energy is extracted from a resonant tank, loadedresonant converters can be classified into series resonant, parallel resonant, and series-parallel resonant converters. The series resonant charger is normally formed by an inductor, capacitor, and bridge rectifier. The ac through the resonant tank is rectified at the output terminals, making it possible to obtain the output dc. 1.1 Resonant Switch: Prior to the availability of fully controllable power switches, thyristors were the major power devices used in power electronic circuits. Each thyristor requires a commutation circuit, which usually consists of a LC resonant circuit, for forcing the current to zero in the turn-off process. This mechanism is in fact a type of zero-current turn-off process. With the recent advancement in semiconductor technology, In many high power applications, controllable switches such as GTOs and IGBTs have replaced thyristors. However, the use of resonant circuit for achieving zerocurrent-switching (ZCS) and/or zero-voltage-switching (ZVS) has also emerged as a new technology for power converters. A resonant switch is a sub-circuit comprising a semiconductor switch S and resonant elements, Lr and Cr. The switch S can be implemented by a unidirectional or bidirectional switch, which determines the operation mode of the resonant switch. Two types of resonant switches, including zero-current (ZC) resonant switch and zero-voltage (ZV) resonant switches, are shown in Fig.2(a) 3(b) and Fig.3(a),4(b), respectively. Page | 2 International Journal of Enhanced Research in Science, Technology & Engineering ISSN: 2319-7463, Vol. 5 Issue 1, January-2016 Lr Lr Cr S S Cr (a) (b) Fig .2 (a) (b) Zero-current (ZC) resonant switch. Lr Lr Cr S S (a) Cr (b) Fig.3 (a) (b) Zero-voltage (ZV) resonant switch. 1.2 Comparisons between ZCS and ZVS: ZCS can eliminate the switching losses at turn-off and reduce the switching losses at turn-on. As a relatively large capacitor is connected across the output diode during resonance, the converter operation becomes insensitive to the diode’s junction capacitance. The major limitations associated with ZCS when power Mosfets are used capacitive turn-on losses. Thus, the switching loss is proportional to the switching frequency. During turn-on, considerable rate of change of voltage can be coupled to the gate drive circuit through the Miller capacitor, thus increasing switching loss and noise It is suitable for high-frequency operation. For single-ended configuration, the switches could suffer from excessive voltage stress, which is proportional to the load. The maximum voltage across switches in half-bridge and full-bridge configurations is clamped to the input voltage.For both ZCS and ZVS, output regulation of the resonant converters can be achieved by variable frequency control. ZCS operates with constant on-time control, while ZVS operates with constant off-time control. 1.3 Switched Converter Topologies Overview 1.3.1 Buck Converter: The buck converter is used for step down operation. When the transistor Q1 is on and Q2 is off, the input voltage appears across the inductor and current in inductor increases linearly. In the same cycle the capacitor is charged. When the transistor Q2 is on and Q1 is off, the voltage across the inductor is reversed. However, current in the inductor cannot change instantaneously and the current starts decreasing linearly. In this cycle also the capacitor is also charged with the energy stored in the inductor. Figure 4: Buck Converter. Page | 3 International Journal of Enhanced Research in Science, Technology & Engineering ISSN: 2319-7463, Vol. 5 Issue 1, January-2016 There is the possibility of two modes of operation namely continuous and discontinuous mode. In continuous mode, the inductor current never reaches zero and in discontinuous mode the inductor current reaches zero in one switching cycle. At lighter load currents the converter operates in discontinuous mode. 1.3.2 Boost converter: The boost converter is capable of producing a dc output voltage greater in magnitude than the dc input voltage. The circuit topology for a boost converter. Figure 5: Boost Converter When the transistor Q1 is on the current in inductor L, rises linearly and at this time capacitor C, supplies the load current, and it is partially discharged. During the second interval when transistor Q1 is off, the diode D1, is on and the inductor L, supplies the load and, additionally, recharges the capacitor C. Using the inductor volt balance principle to get the steady state output voltage equation yields, Vg*Ton+(Vg-Vo)*Toff=0, 𝑉𝑜 𝑇𝑠𝑤 1 = = 1−𝐷 𝑉𝑔 𝑇𝑜𝑓𝑓 Since the converter output voltage is greater than the input voltage, the input current which is also the inductor current is greater than output current. In practice the inductor current flowing through, semiconductors Q1 and D1, the inductor winding resistance becomes very large and with the result being that component non-idealities may lead to large power loss. As the duty cycle approaches one, the inductor current becomes very large and this component no idealities lead to large power losses. 1.3.5 Cuk converter: Cuk converters are derived from the cascading of buck and boost converters. The buck, boost and buck-boost converter all transfer energy between input and output using the inductor and analysis is based on voltage balance across the inductor. The Cuk converter utilizes capacitive energy transfer and analysis is based on current balance of the capacitor. Figure 6: Cuk Converter When the diode is on, the capacitor is connected to input through L1 and source energy is stored in capacitor. During this cycle the current in C1 is IIN. When transistor Q1 is on, the energy stored in the capacitor is transferred to the load through inductor L2.During this cycle the current in C1 is IOUT. The capacitive charge balance principle is used to obtain steady state solution. IG.TOFF + ( -I0 ).TON = 0 I0/ IG = (1-D)/D Page | 4 International Journal of Enhanced Research in Science, Technology & Engineering ISSN: 2319-7463, Vol. 5 Issue 1, January-2016 2.CIRCUIT DESCRIPTION AND OPERATING PRINCIPLES A.Circuit Description Fig. 1 shows the proposed loaded-resonant converter for application of the dc-to-dc energy conversion system. The two capacitors, C1 and C2, on the input are large and split the voltage of the input dc source. The elements Lr1, Lr2, and Cr form the resonant tank. The load resistance R is connected across a bridge rectifier via a low-pass filter capacitor Co. For analysis, the power switching devices are assumed here to be represented by a pair of bidirectional switches operating at a 50% duty ratio over a switching period T. For the half-bridge topology, each bidirectional power switch has an active power switch and an antiparallel diode. The active power switches are driven by nonoverlapping rectangular-wave trigger signals vGS1 and vGS2 with dead time. Thus, we may represent the effect of the power switches by means of an equivalent squarewave voltage source with an amplitude equal to •±Vs/2. Resonant inductor current iLr2 is rectified to obtain a dc bus. The dc bus voltage can be varied and closely regulated by controlling the switching frequency Fig. 7Simplified equivalent circuit of the proposed loaded-resonant converter. The following analysis assumes that the converter operates in the continuous conduction mode, displays the idealized steady state voltage and current waveforms in the proposed novel loaded-resonant converter for a switching frequency fs that exceeds resonant frequency fo. Operating above resonance is preferred because the power switches turn on at zero current and zero voltage; thus, the freewheeling diodes do not need to have very fast reverse-recovery characteristics. During the positive half-cycle of the current through the resonant inductor Lr2, the power is supplied to the load resistor R through diodes DR1 and DR2. During the negative half-cycle of the current through the resonant inductor Lr2, the power is fed to the load resistor R through diodes DR3 and DR4. Fig. 8. Equivalent circuit of Mode I. Fig. 9. Equivalent circuit of Mode II. Steady-state operations of the novel loaded-resonant converter in a switching period can be divided into four modes. Mode I—(Between ωot0 and ωot1): Periodic switching of the resonant energy tank voltage between +Vs/2 and −Vs/2 generates a square-wave voltage across the input terminal. Since the output voltage is assumed to be a constant voltage Vo, the input voltage to the full-bridge rectifier is Vo when iLr2 (t) is positive and is −Vo when iLr2 (t) is negative. Hence, Fig. 8 displays the equivalent circuit of the proposed novel loadedresonant converter for the application of dc-to-dc energy conversion in Fig. 1. This time interval ends when iLr2 (t) reaches zero at ωot1. Before ωot0, active power switch S2 is excited and conducts a current that equals resonant tank current iLr1 . The active power switch S1 is turned on at ωot0. However, resonant tank current iLr1 is negative and flows through freewheeling diode D1. At instant ωot1, resonant tank current iLr1 reverses and naturally commutates from freewheeling diode D1 to power switch S1. In this mode, the power switches are turned on naturally at zero voltage and at zero Page | 5 International Journal of Enhanced Research in Science, Technology & Engineering ISSN: 2319-7463, Vol. 5 Issue 1, January-2016 current. Therefore, the current through the active power switch is negative after turning on and positive before turning off. Although the current in the switches is turned on at zero voltage and zero current to eliminate turn-on losses, the switches are forced to turn off a finite current, thus allowing turn-off losses exit. Fortunately, small capacitors can be placed across the switches to function as snubbers in order to eliminate turnoff losses. Mode II—(Between ωot1 and ωot2): The cycle starts at ωot1 when the current iLr1 resonant tank resonates from negative values to zero. At ωot2, before the half-cycle of resonant current iLr1 oscillation ends, switch S1 is forced to turn off, forcing the positive current to flow through bottom freewheeling diode D2. Fig. 8 shows the equivalent circuit. The positive dc input voltage applied across the resonant tank causes the resonant current that flows through the power switch to go quickly to zero. Mode III—(Between ωot3 and ωot4): A turn-off trigger signal is applied to the gate of the active power switch S1. The inductor current then naturally commutates from active power switch S1 to freewheeling diode D2. Mode III begins at ωot3, when diode D2 is turned on, subsequently producing a resonant stage between inductors Lr1, Lr2 and capacitor Cr. Inductors Lr1, Lr2, and capacitor Cr resonate. Before ωot4, trigger signal vgs2 excites active power switch S2. This time interval ends when iLr1 (t) reaches zero at ωot4. Fig. 9 shows the equivalent circuit. Mode IV—(Between ωot4 and ωot5): When capacitor voltage iLr2 is positive, rectifier diodes DR1 and DR2 are turned on with zero-voltage condition at instant ωot4. Fig. 10 shows the equivalent circuit. When inductor current iLr2 changes direction, rectifier diodes DR1 and DR2 are turned off at instant ωot5, and Mode IV ends. When driving signal Vgs1 again excites active power switch S1, this mode ends and the operation returns to mode I in the subsequent cycle. During the positive half-cycle of the inductor current iLr2 , the power is supplied to the load through bridge rectifier diodes DR1 and DR2. During the negative half-cycle of the inductor current, the power is supplied to the load through bridge rectifier diodes DR3 and DR4. Fig. 10. Equivalent circuit of Mode III. Fig. 11. Equivalent circuit of Mode IV CIRCUIT PARAMETERS S.NO 1 2 3 4 5 6 7 8 9 PARAMETER NAME INPUT VOLTAGE VS RESONANT INDUCTOR LR1 RESONANT INDUCTOR LR2 RESONANT CAPACITOR CR RESONANT FREQUENCY F0 SWITCHING FREQUENCY FS OUTPUT VOLTAGE V0 FILTER CAPACITOR C0 OUTPUT RESISTOR R RATING 24 V 8 µH 3.5µH 0.5µF 80k Hz 81k Hz 12 V 100µF 6Ω Page | 6 International Journal of Enhanced Research in Science, Technology & Engineering ISSN: 2319-7463, Vol. 5 Issue 1, January-2016 1.Simulation Model and Results Vdr1 Vgs1 NOT + v - Is1 Il r1 g S m Dis cre te , T s = 1e -008 s . i + - i - D + Vgs2 Idr1 Io Vs1 i - + Il r2 + i - + v - i + - + i - <MOSFET v oltage> Vo Icr g D m S i + - + v - Va + v Vcr + v - Vs2 <MOSFET v oltage> Vb Is2 Vgs1 Vs1 Va Va Vb Vo Vcr Vgs2 Is1 Il r1 Vb Il r2 Io Icr Vdr1 Idr1 Fi g.12. Simulation model for proposed circuit Fig.13.Triggering pulses for MOSFET Fig.14.Voltage Across MOSFET(Vs1), Current flowing through MOSFET (Is1) Fig.15. Input Voltage (Va) and Current (Ilr1) Fig.17. Output voltage (Vb) and output current of resonant tank (ILr2) Fig.19 Resonant capacitor voltage (Vcr) and current (Icr) Fig.16.Input (Va) and output voltage (Vb) of resonant tank Fig .18. Load voltage (V0) and load current (I0) Fig.20. Voltage (Vdr1) and current (Idr1) of rectifier diode. Page | 7 International Journal of Enhanced Research in Science, Technology & Engineering ISSN: 2319-7463, Vol. 5 Issue 1, January-2016 1.CONCLUSION This work developed a novel loaded-resonant converter with a bridge rectifier for the application of dc-to-dc energy conversion. The circuit structure is simpler and less expensive than other control mechanisms, which require many components. The developed topology is characterized by zerovoltage switching, reduced switching losses, and increased energy conversion efficiency. The output voltage/current can be determined from the characteristic impedance of the resonant tank by the adjustable switching frequency of the converter, whereas the proposed loadedresonant converter is applied to a load in order to yield the required output conditions. Experimental results demonstrate the effectiveness of the proposed converter. The energy conversion efficiency is 88.3%, which is quite satisfactory when the proposed loaded-resonant circuit operating above resonance is applied to a dc-to-dc converter. In contrast with the conventional parallel-loaded-resonant converter, energy conversion efficiency can be improved using the novel loaded-resonant converter with a full-bridge rectifier topology. An excellent performance is achieved at a lower cost and with fewer circuit components than with the conventional converter REFERENCES [1] W. Wongsaichua, W. J. Lee, S. Oraintara, C. Kwan, and F. Zhang, “In-tegrated high-speed intelligent utility tie unit for disbursed/renewable generation facilities,” IEEE Trans. Ind. Appl., vol. 41, no. 2, pp. 507–513, [2] Z. Liang, R. Guo, J. Li, and A. Q. Huang, “A high-efficiency PV module-integrated DC/DC converter for PV energy harvest in FREEDM systems,” IEEE Trans. Power Electron., vol. 26, no. 3, pp. 897–909, Mar. 2011. [3] A. M. Rahimi and A. Emadi, “Discontinuous-conduction mode DC/DCconverters feeding constant-power loads,” IEEE Trans. Ind. Electron.,vol. 57, no. 4, pp. 1318–1329, Apr. 2010. [4] R. Morrison and M. G. Egan, “A new power-factor-corrected single-transformer UPS design,” IEEE Trans. Ind. Appl., vol. 36, no. 1, pp. 171– [5] Y. M. Lai, S.-C. Tan, and Y. M. Tsang, “Wireless control of load currentinformation for parallel-connected DC/DC power converters,”IET Power Electron., vol. 2, no. 1, pp. 14–21, Jan. 2009. [6] S. M. Lukic, J. Cao, R. C. Bansal, F. Rodriguez, and A. Emadi, “Energystorage systems for automotive applications,” IEEE Trans. Ind. Electron.,vol. 55, no. 6, pp. 2258–2267, Jun. 2008. [7] F. Liu, J. Yan, and X. Ruan, “Zero-voltage and zero-current-switchingPWM combined three-level DC/DC converter,” IEEE Trans. Ind.Electron., vol. 57, no. 5, pp. 1644–1654, May 2010. [8] Y. M. Chen, Y. C. Liu, and S. H. Lin, “Double-input PWM DC/DC con-verter for high-/low-voltage sources,” IEEE Trans. Ind. Electron., vol. 53,no. 5, pp. 1538–1545, Oct. 2006. Page | 8