![ACEEE International Journal on Electrical and Power Engineering, Vol. 1, No. 2, July 2010
Open Loop Control Of Series Parallel Resonant
Converter
Dr. S. Muralidharan and S. Aparna (PG Student)
Department of Electrical and Electronics Engineering
Mepco Schlenk Engineering College
Sivakasi, India
yes_murali@yahoo.com and s.aparna87@gmail.com
Abstract— Resonant converters are desirable for power output voltage against load and line variations. This
conversion due to their comparatively smaller size and makes it difficult to filter EMI and effectively utilize
lower power losses resulting from high-frequency magnetic components. As a remedy for these problems,
operation and inherent soft switching. Among all the full bridge topologies of phase-controlled resonant
topologies of the resonant converters, the series–parallel inverters and converters have been proposed
resonant converter (SPRC) is known to have the
Resonant converters are desirable for power
combined merits of the series resonant converter and
parallel resonant converter. The converter can regulate conversion due to their comparatively smaller size and
the output voltage at a constant switching frequency even lower power losses resulting from high-frequency
for a change in load resistance from full load resistance to operation and inherent soft switching. Among all the
infinity while maintaining good part load efficiency. The topologies of the resonant converters, the series–
purpose of this project is to design a closed loop parallel resonant converter (SPRC) shares the
controller for the phase-controlled series parallel advantages of both the pure series converter and pure
resonant converter (PC SPRC). The open loop analysis parallel converter [1]. To regulate the output of an
and closed loop control has been provided in this paper. SPRC, frequency control or phase control are usually
Index Terms—Digital control, modeling, phase-shift
used. The frequency control can be used in a half-
control and resonant power conversion. bridge configuration. The phase control requires a full-
bridge circuit. It allows, however, for a constant
frequency operation. Some of the phase-controlled
I. INTRODUCTION converters, for example, the phase-controlled SPRC
(PC SPRC) introduced in [2], are capable of providing
Power electronic systems are widely used today to inductive loads for the switching devices in both legs
provide power processing for applications ranging of the inverter bridge. Thus, the reverse recovery
from computing and communications to medical currents through the antiparallel diodes in the switches
electronics, appliance control, transportation, and high- are minimized, and the power losses are reduced.
power transmission. The associated power The main advantage of series resonant converter is
l0.00cmevels range from milliwatts to megawatts. that the series resonant capacitors act as a dc blocking
These systems typically involve switching circuits capacitor. Because of this fact this converter is used in
composed of semiconductor switches such as full bridge arrangements without any additional control
thyristors, MOSFETs, and diodes, along with passive to control unbalance in the power FET switching times
elements such as inductors, capacitors, and resistors, and forward voltage drops. The main advantage of
and integrated circuits for control.To reduce the size of parallel resonant converter is that it is extremely
power supplies intended for use in modem computing desirable for applications with short circuit proof. Also
systems, it is desirable to raise the operating frequency in this converter, the current carried by the power
to reduce the size of reactive components. To reduce FET’s and resonant components is relatively
the higher switching losses resulting from higher independent of load. The series parallel resonant
frequency operation, resonant power conversion is converter combines the above said advantages.
receiving renewed interest.
Resonant power conversion technology offers many II. PROPOSED CIRCUIT DIAGRAM
advantages in comparison with PWM one. Among
them are low electromagnetic interference (EMI), low The PC SPRC consists of two identical series–
switching losses, small volume and weight of parallel inverters. Each inverter is composed of
components due to high operating frequency, high two switches with their anti parallel diodes and a
efficiency, and low reverse-recovery losses in diodes series–parallel resonant circuit with a shared
because of low di/dt at turn-off. However, most parallel-connected capacitor 2Cp. These two
frequency-controlled resonant converters, suffer from a resonant circuits form an overall resonant tank,
wide range of frequencies which is required to regulate which is symmetrical with respect to 2Cp. The dc
61
© 2010 ACEEE
DOI: 01.ijepe.01.02.12](https://image.slidesharecdn.com/12-120921231255-phpapp01/85/Open-Loop-Control-Of-Series-Parallel-Resonant-Converter-1-320.jpg)
![ACEEE International Journal on Electrical and Power Engineering, Vol. 1, No. 2, July 2010
the step changes in load resistance from 200 Ω to 50 Ω implement a control algorithm that generates the
is shown in Fig.7. The output voltage and current control signals to the converter based on measured
responses for step change in resistance from 150 Ω to output or state signals from converter as in [4]-[7]. The
100 Ω is shown in Fig.8. It can be seen Fig.9. that the controller must generate these control signals fast
rectifier output voltage is maintained constant at 65 V enough to retain control of the plant. Therefore, speed
using PI controller. can be a severe limitation on the controller for systems
with dynamics at high frequency. The use of
microprocessors as a replacement for conventional
analog controllers to implement discrete controllers,
therefore, has advantages and limitations. The
advantages are flexibility, programmability, and the
ability to handle other supplementary functions like
start up and protection. On the other hand, since the
controller must operate in real time, there is a speed
limitation when controlling a very high speed system.
Fig.8. Rectifier Output for variable load REFERENCES
[1] R. L. Steigerwald, “A comparison of half-bridge
resonant converter topologies,” IEEE Trans. Power
Electron., vol. 3, no. 2, pp. 174–182, Apr. 1988.
[2] D. Czarkowski andM. K. Kazimierczuk, “Phase-
controlled series-parallel resonant converter,” IEEE
Trans. Power Electron., vol. 8, no. 3, pp. 309– 319, Jul.
1993.
[3] M. K. Kazimierczuk and D. Czarkowski, Resonant
Power Converters. Hoboken, NJ: Wiley, 1995, ch. 15–
21.
[4] M. E. Elbuluk, G. C. Verghese, and J. G. Kassakian,
“Sampled-data modeling and digital control of resonant
Fig.9. Controller Rectifier Output
converters,” IEEE Trans. Power Electron., vol. 3, no. 3,
pp. 344–354, Jul. 1988.
[5] A. F. Witulski, A. F. Hernandez, and R. W. Erickson,
E. Applications “Small signal equivalent circuit modeling of resonant
• In induction heating converters,” IEEE Trans. Power Electron., vol. 6, no. 1,
pp. 11–27, Jan. 1991.
• Capacitor charging [6] V. Agarwal and A. K. S. Bhat, “Small signal equivalent
• Battery charging circuit modeling of the LCC-type parallel resonant
• Semiconductor laser diode drivers converter,” in Proc. Int. Conf. Power Electron. and
• Sonar transmitter Drive Syst., 1995, vol. 1, pp. 146–151.
• Telephone equipment [7] D. Maksimovic, A. M. Stankovic, V. J. Thottuvelil, and
G. C. Verghese, “Modeling and simulation of power
• Ultrasonic generators electronic converters,” Proc. IEEE, vol. 89, no. 6, pp.
• Fluorescent lighting 898–912, Jun. 2001.
[8] S. R. Sanders, J.M. Noworolski, X. Z. Liu, and G. C.
III. CONCLUSION Verghese, “Generalized averaging method for power
conversion circuits,” IEEE Trans. Power Electron., vol.
A new phase-controlled series-parallel resonant 6, no. 2, pp. 251–259, Jul. 1991.
converter has been introduced which provides constant [9] E. X. Yang, F. C. Lee, and M. M. Jovanovic, “Small-
signal modeling of LCC resonant converter,” in Proc.
DC power supply for various applications. An attempt IEEE PESC, 1992, vol. 2, pp. 941–948.
is made to analyse the series parallel resonant converter [10] E. X. Yang, B. Choi, F. C. Lee, and B. H. Cho,
under open loop condition and closed loop control and “Dynamic analysis and control design of LCC resonant
the simulation results has been obtained for varying converter,” in Proc. IEEE PESC, 1992, vol. 1, pp. 362–
369.
load conditions.The essential control task is to
64
© 2010 ACEEE
DOI: 01.ijepe.01.02.12](https://image.slidesharecdn.com/12-120921231255-phpapp01/85/Open-Loop-Control-Of-Series-Parallel-Resonant-Converter-4-320.jpg)
Open Loop Control Of Series Parallel Resonant Converter
- 1. ACEEE International Journal on Electrical and Power Engineering, Vol. 1, No. 2, July 2010 Open Loop Control Of Series Parallel Resonant Converter Dr. S. Muralidharan and S. Aparna (PG Student) Department of Electrical and Electronics Engineering Mepco Schlenk Engineering College Sivakasi, India yes_murali@yahoo.com and s.aparna87@gmail.com Abstract— Resonant converters are desirable for power output voltage against load and line variations. This conversion due to their comparatively smaller size and makes it difficult to filter EMI and effectively utilize lower power losses resulting from high-frequency magnetic components. As a remedy for these problems, operation and inherent soft switching. Among all the full bridge topologies of phase-controlled resonant topologies of the resonant converters, the series–parallel inverters and converters have been proposed resonant converter (SPRC) is known to have the Resonant converters are desirable for power combined merits of the series resonant converter and parallel resonant converter. The converter can regulate conversion due to their comparatively smaller size and the output voltage at a constant switching frequency even lower power losses resulting from high-frequency for a change in load resistance from full load resistance to operation and inherent soft switching. Among all the infinity while maintaining good part load efficiency. The topologies of the resonant converters, the series– purpose of this project is to design a closed loop parallel resonant converter (SPRC) shares the controller for the phase-controlled series parallel advantages of both the pure series converter and pure resonant converter (PC SPRC). The open loop analysis parallel converter [1]. To regulate the output of an and closed loop control has been provided in this paper. SPRC, frequency control or phase control are usually Index Terms—Digital control, modeling, phase-shift used. The frequency control can be used in a half- control and resonant power conversion. bridge configuration. The phase control requires a full- bridge circuit. It allows, however, for a constant frequency operation. Some of the phase-controlled I. INTRODUCTION converters, for example, the phase-controlled SPRC (PC SPRC) introduced in [2], are capable of providing Power electronic systems are widely used today to inductive loads for the switching devices in both legs provide power processing for applications ranging of the inverter bridge. Thus, the reverse recovery from computing and communications to medical currents through the antiparallel diodes in the switches electronics, appliance control, transportation, and high- are minimized, and the power losses are reduced. power transmission. The associated power The main advantage of series resonant converter is l0.00cmevels range from milliwatts to megawatts. that the series resonant capacitors act as a dc blocking These systems typically involve switching circuits capacitor. Because of this fact this converter is used in composed of semiconductor switches such as full bridge arrangements without any additional control thyristors, MOSFETs, and diodes, along with passive to control unbalance in the power FET switching times elements such as inductors, capacitors, and resistors, and forward voltage drops. The main advantage of and integrated circuits for control.To reduce the size of parallel resonant converter is that it is extremely power supplies intended for use in modem computing desirable for applications with short circuit proof. Also systems, it is desirable to raise the operating frequency in this converter, the current carried by the power to reduce the size of reactive components. To reduce FET’s and resonant components is relatively the higher switching losses resulting from higher independent of load. The series parallel resonant frequency operation, resonant power conversion is converter combines the above said advantages. receiving renewed interest. Resonant power conversion technology offers many II. PROPOSED CIRCUIT DIAGRAM advantages in comparison with PWM one. Among them are low electromagnetic interference (EMI), low The PC SPRC consists of two identical series– switching losses, small volume and weight of parallel inverters. Each inverter is composed of components due to high operating frequency, high two switches with their anti parallel diodes and a efficiency, and low reverse-recovery losses in diodes series–parallel resonant circuit with a shared because of low di/dt at turn-off. However, most parallel-connected capacitor 2Cp. These two frequency-controlled resonant converters, suffer from a resonant circuits form an overall resonant tank, wide range of frequencies which is required to regulate which is symmetrical with respect to 2Cp. The dc 61 © 2010 ACEEE DOI: 01.ijepe.01.02.12
- 2. ACEEE International Journal on Electrical and Power Engineering, Vol. 1, No. 2, July 2010 load R is connected to this resonant tank through a 1) The loaded quality factor QL of the inverter is rectifier and an output filter. high enough so that the currents i1 and i2 are sinusoidal. 2) The power MOSFET’s are modeled by switches with ON-resistances RDS. 3) The reactive components of the resonant circuits are passive, linear, time invariant, and do not have parasitic resonances. 4) Components of both resonant circuits are identical B Block Diagram Fig.1. Circuit diagram If the switching frequency is fixed at a value close to the resonant frequency, the output voltage Vo can be regulated against load and line variations by varying the phase shift between the voltages that drive inverter 1 and inverter 2 while maintaining a fixed operating Fig.2. Block Diagram frequency and inductive loads for both pairs of switches. For inductively loaded switching legs, zero- The DC supply is given to the series parallel inverter voltage switching can be accomplished by adding a with resonant tank which produces alternating voltages shunt capacitor in parallel with one of the switches in and currents due to resonance. This AC output is fed to each leg and using a dead time in drive voltages of a class-D voltage driven rectifier to obtain rectified MOSFET’s. The converter is suitable for medium-to- output. The resonant converter is used in low voltage high power applications with the upper switching power supply applications frequency limit of 150 kHz. C Simulation Results A Assumptions Simulation is done in MATLAB programming The analysis of the PC SPRI of Fig. 1 begins with language for the above mentioned problem and the the following simplifying assumptions: research is going on in to get absolute result. The simulation model are shown in the fig 3,4 and 5 Fig.3. Simulation circuit with variable load 62 © 2010 ACEEE DOI: 01.ijepe.01.02.12
- 3. ACEEE International Journal on Electrical and Power Engineering, Vol. 1, No. 2, July 2010 Fig.5. Series Variable Load Producing Circuit Fig.6. Simulation Result Continuous powergui g g D D Mosfet Mosfet 1 m m S S Scope Scope 2 + v - i DC Voltage Source + - Voltage Measurement Scope 3 Series RLC Branch Current Measurement Series RLC Branch 1 i + g D Series RLC Branch 4 - g D Series RLC Branch 2 Mosfet 3 Current Measurement 1 + v Mosfet 2 - m S Voltage Measurement 2 m S Diode Diode 1 + v - + Voltage Measurement 1 Series RLC Branch 3 variable load - Diode 2 Diode 3 Pulses In 1 PI 65 Scope 1 Discrete Constant PW M Generator PI Controller Fig.7. Resonant Converter Circuit With Controller respectively. The rectified output is constant for fixed frequency, or 19.181 kHz. The designed resonant load and it varies for variable load. The analysis shows circuit resistance, series inductance and series that the combination series-parallel converter can run capacitance values are 5 Ω, 1.1 mH and 0.1 μF over a large input voltage range and a large load range respectively. The parallel capacitance value in the (no load to full load) while maintaining excellent resonant tank is 0.22 nF. The waveforms of the voltage efficiency when compared to series and parallel resonant converters analysed separately across the parallel capacitor Cp and the current through the resonant circuit of the inverter is shown in Fig.4. It D Experimental Results can be seen that these waveforms are sinusoidal over a wide range of the load resistance, which confirms the A phase controlled series parallel resonant converter assumption 4). The simulation has provided a rectified has been simulated with variable load. The natural output voltage of 100 V for fixed resistive load of 100 resonant frequency is 18.268 kHz for this converter, Ω. The output voltage and output current responses for and the switching frequency is 1.05 times the resonant 63 © 2010 ACEEE DOI: 01.ijepe.01.02.12
- 4. ACEEE International Journal on Electrical and Power Engineering, Vol. 1, No. 2, July 2010 the step changes in load resistance from 200 Ω to 50 Ω implement a control algorithm that generates the is shown in Fig.7. The output voltage and current control signals to the converter based on measured responses for step change in resistance from 150 Ω to output or state signals from converter as in [4]-[7]. The 100 Ω is shown in Fig.8. It can be seen Fig.9. that the controller must generate these control signals fast rectifier output voltage is maintained constant at 65 V enough to retain control of the plant. Therefore, speed using PI controller. can be a severe limitation on the controller for systems with dynamics at high frequency. The use of microprocessors as a replacement for conventional analog controllers to implement discrete controllers, therefore, has advantages and limitations. The advantages are flexibility, programmability, and the ability to handle other supplementary functions like start up and protection. On the other hand, since the controller must operate in real time, there is a speed limitation when controlling a very high speed system. Fig.8. Rectifier Output for variable load REFERENCES [1] R. L. Steigerwald, “A comparison of half-bridge resonant converter topologies,” IEEE Trans. Power Electron., vol. 3, no. 2, pp. 174–182, Apr. 1988. [2] D. Czarkowski andM. K. Kazimierczuk, “Phase- controlled series-parallel resonant converter,” IEEE Trans. Power Electron., vol. 8, no. 3, pp. 309– 319, Jul. 1993. [3] M. K. Kazimierczuk and D. Czarkowski, Resonant Power Converters. Hoboken, NJ: Wiley, 1995, ch. 15– 21. [4] M. E. Elbuluk, G. C. Verghese, and J. G. Kassakian, “Sampled-data modeling and digital control of resonant Fig.9. Controller Rectifier Output converters,” IEEE Trans. Power Electron., vol. 3, no. 3, pp. 344–354, Jul. 1988. [5] A. F. Witulski, A. F. Hernandez, and R. W. Erickson, E. Applications “Small signal equivalent circuit modeling of resonant • In induction heating converters,” IEEE Trans. Power Electron., vol. 6, no. 1, pp. 11–27, Jan. 1991. • Capacitor charging [6] V. Agarwal and A. K. S. Bhat, “Small signal equivalent • Battery charging circuit modeling of the LCC-type parallel resonant • Semiconductor laser diode drivers converter,” in Proc. Int. Conf. Power Electron. and • Sonar transmitter Drive Syst., 1995, vol. 1, pp. 146–151. • Telephone equipment [7] D. Maksimovic, A. M. Stankovic, V. J. Thottuvelil, and G. C. Verghese, “Modeling and simulation of power • Ultrasonic generators electronic converters,” Proc. IEEE, vol. 89, no. 6, pp. • Fluorescent lighting 898–912, Jun. 2001. [8] S. R. Sanders, J.M. Noworolski, X. Z. Liu, and G. C. III. CONCLUSION Verghese, “Generalized averaging method for power conversion circuits,” IEEE Trans. Power Electron., vol. A new phase-controlled series-parallel resonant 6, no. 2, pp. 251–259, Jul. 1991. converter has been introduced which provides constant [9] E. X. Yang, F. C. Lee, and M. M. Jovanovic, “Small- signal modeling of LCC resonant converter,” in Proc. DC power supply for various applications. An attempt IEEE PESC, 1992, vol. 2, pp. 941–948. is made to analyse the series parallel resonant converter [10] E. X. Yang, B. Choi, F. C. Lee, and B. H. Cho, under open loop condition and closed loop control and “Dynamic analysis and control design of LCC resonant the simulation results has been obtained for varying converter,” in Proc. IEEE PESC, 1992, vol. 1, pp. 362– 369. load conditions.The essential control task is to 64 © 2010 ACEEE DOI: 01.ijepe.01.02.12