Design and Implementation of a High Efficiency Multiple Output Charger based on the Time Division Multiple Control Technique

 

Abstract

Multiple output converters (MOCs) are widely applied to applications requiring various levels of output voltages due to their advantages in terms of cost, volume, and efficiency. However, most of the conventional MOCs cannot regulate multiple outputs tightly and they can barely avoid the cross regulation problem. In this paper, the recently developed Time Division Multiple Control (TDMC) method, which can regulate all of the outputs with a high accuracy, is used for a multiple output battery charger based on the phase shift full bridge topology to simultaneously charge three batteries. The proposed charger is able to charge three different kinds of batteries or three of the same kind of battery in different state of charges (SOCs) independently and accurately with the constant current/constant voltage (CC/CV) charge method. As a result, the strict ripple specification of a battery can be satisfied for multiple battery charges without difficulty. In addition, the proposed charger exhibits a high efficiency since the soft switching of all of the switches during the entire charge process can be guaranteed. The operating principle of the converter and the design of the controller, including the state-space average modeling, will be detailed and the validity of the proposed method is verified through experiments.

EXISTING SYSTEM:

Another method uses a controlled current source in the form of a fairly big inductor connected to each output through a switch on a time shared basis during one switching cycle.  However, since it requires a large inductor as a current source, the converter becomes bulky and expensive. In addition, the method is extremely difficult to implement and complex in terms of small signal modeling on account of the differences in time sharing at each output during the freewheeling period of the inductor current. As a result, cross regulation problem is an inherent disadvantage of this method.  Other methods utilize a hybrid control to regulate the multiple outputs. In, two outputs are regulated by controlling the duty cycle and frequency of the switch. However, the number of converter outputs is limited to two and the regulation performance of each output is not good enough for the charge applications. In, the outputs are regulated independently based on multiple-band modulation and demodulation, which are operated by superposed sinusoidal pulse width modulation, pulse frequency modulation, and band-pass filtering. However, this method is very complex in terms of its control and the large filter required for each output increases the volume and decreases the efficiency of the converter.

PROPOSED SYSTEM:

Since all of the above mentioned methods are designed to control all of the outputs in one switching cycle, the cross regulation between the outputs is an inherent problem. In addition, this requires as many secondary windings in the transformer as the number of outputs in case of isolated converter topologies. The recently developed Time Division Multiple Control (TDMC) method has been applied to multiple output chargers in order to overcome the drawbacks mentioned above. However, since the proposed topology was developed based on the double ended forward converter, it is only suitable for small power applications due to the inherent limitation of the topology. In addition the efficiency is not high enough since all the switches operate with hard switching and the duty cycle of the switch is limited less than 50% in order to reset the magnetizing current of the transformer. In this paper, a TDMC method based on the phase shift full bridge topology is proposed for multiple output charger applications to overcome the drawbacks of previous research. The major advantages of the proposed multiple output chargers can be summarized as follows.  i) It offers an even degree of tight and independent regulation for each output, which is essential for multiple output charge applications.  ii) It is simple in design and analysis, and easy to model the circuit.   iii) No cross regulation problem exists a the outputs. iv) Only one secondary winding of the transformer is  required to regulate the multiple outputs if no isolation between the outputs is required.  v) Zero voltage switching (ZVS) turn-on can be achieved at all primary switches during the entire charge process  vi) Zero current switching (ZCS) turn-on and ZVS turn-off can be achieved at all the secondary switches with no additional circuit.  As a result, the proposed converter can be used for the higher power applications since it has been developed based on the full bridge topology and exhibit a high efficiency. The proposed multiple battery charger is able to charge a number of batteries at different state of charges (SOCs) by using constant current and constant voltage (CC/CV) charge modes, which is considered to be an efficient method to charge batteries . Since the TDMC method can control each output independently, the battery at each output can be charged independently by either the CC mode or the CV mode. As a result, three batteries can be charged simultaneously. In addition, it is possible to satisfy the strict ripple specifications of the batteries since the cross regulation problem between the outputs does not exist. The circuit operation and modeling of the proposed topology will be detailed in the following sections. The effectiveness and feasibility of the proposed multiple output chargers will be verified by experimental results.

CONCLUSION

In this paper, a multiple output battery charger based on the  Time Division Multiple Control (TDMC) technique is proposed and applied to the phase shift full bridge topology to simultaneously charge three Li-Po batteries. The proposed charger can regulate three outputs precisely and independently with only one secondary winding in the transformer. With the help of a digital signal processor capable of high speed operation, the TDMC method can be simply implemented. However, there is a trade-off in the design between the number of outputs and the switching frequency of each output due to the size of the reactive components at the secondary side.   The proposed method offers a simple control technique to achieve an even degree of tight regulation for all of the outputs and can be applied to all kinds of isolated converter topologies. If it is applied to off-board charger applications for the EVs, the installation area can be significantly reduced thereby providing another benefit by decreasing the overall cost of the system.

REFERENCES   

[1] Singh. S, Bhuvaneswari. G, and Singh. B, “Multiple Output SMPS with Improved Input Power Quality”, Industrial and Information Systems (ICIIS), 2010 International Conference on, Mangalore, August 2010, pp: 382~387.

[2]  Reddy. J, Bhuvaneswari. G, and Singh. B, “A Single DCDC  Converter Based Multiple Output SMPS with Fully Regulated and Isolated Outputs”, INDICON, 2005 Annual IEEE, December 2005, pp: 585~589.

[3] Joy. A.E, and Anudev. J, “Analysis of Multiple Output SMPS Topology for PC Application”, Computation of Power, Energy Information and Commuincation (ICCPEIC), 2015 International Conference on, Chennai, April 2015, pp: 0059~0063.

[4] C. D. Technologies, “Charging Valve Regulated Lead Acid Batteries,”Tech. Note., C. D. Technologies, Blue Bell, PA, USA, 2012.

[5] Emerson Network Power,“Effect of AC Ripple Current on VRLA Battery Life,” Tech. Note., Experts in BusinessCritical  Continuity, Columbus, Ohio, USA, 2011. [Online] Available: http://www.emersonetworkpower.com/

[6] S. Dearborn. “Charging Li-Ion Battery for Maximum run times,”Power Electron. Technol. Mag., pp. 40 – 49, Apr. 2005. [Online] Available: http://powerelectronics.com/content/charging-li-ionbatteries-maximum-run-times

[7] Quest Battery, “Harding Battery Handbook for Lithium Polymer,” Section 6 [Online]. Available: http://www.hardingenergy.com/handbook/

[8] Yie-Tone Chen, “Small-Signal Analysis of a Synchronous-Switch Post Regulator with Coupled Inductor”, Industrial Electronics, IEEE Transactions on, Vol. 47, Feb 2000, pp: 55~66.

[9] P. Patra, J. Ghosh, and A. Patra, “Control Scheme for Reduced Cross-Regulation in Single-Inductor MultipleOutput DC-DC  Converters,” Industrial Electronics, IEEE Transactions on, vol. 60, pp. 5095-5104, 2013.

[10] J. Chuanwen, M. Smith, Jr., K. M. Smedley, and K. King, “Cross regulation in flyback converters: analytic model and solution,” Power Electronics, IEEE Transactions on, vol. 16, pp. 231-239, 2001