Study on Different Types of Controlling Techniques Used For Interleaved DC-DC Boost Converters
Mrunali J. PanseM.Tech Student
Dr. Rakesh G. SriwastavaDepartment of Electrical Engineering
[email protected] – DC – DC boost converter were used in many applications such as renewable energy sources which includes photovoltaic ( PV ) cells and fuel cells. The reliability, efficiency and controllability of PV systems can be increased by using Boost converters. A DC – DC Boost converter provide higher output voltage but it produces some ripple current. In order to reduce the ripple current so as to improve the efficiency of boost converter, an interleaved boost converter is used. For maintaining the voltage at output constant irrespective of variations in DC input voltage and load current, a control system must be required for the interleaved converter. This paper presents a detailed study of various control techniques of DC – DC interleaved Boost for conversion of power from one level to another level. In addition, these control techniques are compared in terms of their advantages and dis-advantages.
Keywords – Boost Converter, DC-DC Interleaved Boost converter(IBC), PID control, Slide – Mode Control ( SMC ) and Sigma – Delta ( SDM )
In recent years, renewable energy sources has become the fastest growing power sector in the world. Conventional fossil-fuels takes millions of years to completely restore. It also has limited reserve capacity and costs for high price. Due to this reason, renewable energy sources are the possible solutions to the environmental problems. In research fields, most of the renewable energy sources such as fuel cell stacks and photovoltaic cells have received worldwide attention. 1
A switching converter is a power electronic devices which is used to transform an input voltage level into another level by switching action of semiconductor device. For this purpose a high power dc-dc converter is strongly required that has found widespread applications like aerospace, electric vehicle (EV), portable electronic device like pagers and microprocessor voltage regulation.
Power electronic based DC – DC converter interfaces for DC energy sources, but these power sources have quite low voltage output.
Most of the renewable power sources, have quite low-voltage output and to increase its output level, it requires series connection or voltage booster 4. DC-DC boost converters are generally employed in equipments, as pre-regulators 8 – 10 But, due to the inductor of classical boost converter, the ripple current is increased.
Interleaved boost converter IBC, is one such converter that can be used for high power applications. The advantages of interleaved boost converter are faster transient response, high efficiency, improved reliability and decreased electromagnetic emission. Due to interleaved operation ( parallel connection of two or more boost converter ), IBC proposes both lower current ripple at the input side and lower voltage ripple at the output side.
Few literatures related to the controller design so as to obtain high performance control of high-power interleaved boost converter can be found 2.
In this paper different control techniques, including linear and non-linear control such as current mode control, voltage mode control, PWM with PID control, slide mode control, digital control Sigma-Delta modulator, fuzzy control, for DC-DC boost converter have been studied. Fuzzy controller are non-linear controller that are effective but are difficult as well as expensive for practical application. Now a days, current-mode controllers and linear control methods are most frequently used for controlling DC-DC boost converter.
MODELLING AND DESIGN OF DC – DC BOOST CONVERTER
A boost converter is known as step – up converter. The circuit of dc – dc boost converter is shown in fig. 1. It step up the input voltage Vi and provides high output voltage Vo at the output side, for steady – state operation.
It ‘ boost ‘ the voltage to a higher level. Hence, Vo is always higher than Vi. The converter mainly consist of L as boost inductor, a power controlled MOSFET switch S, a diode D and a filter capacitor C configured in parallel to a resistive load R. The switch is set to ON and OFF state at a switching frequency fs = 1/T with duty ratio D = ton/, where ton is the time interval when switch S is at ON state3. It is a class of switching mode power supply (SMPS) containing at least two semi-conductors switches (a diode and a transistor) and at least one energy storage element. The capacitor is connected at the output side as the ripples present in output voltage is reduced 5
Boost converter is said to operate in two modes, they are as follows :Mode 1 : When the switch S is closed i.e. ON state, causes the current in the boost inductor increases linearly, storing energy in its magnetic field. During this mode of operation, the load is completely isolated from source, as shown in fig. 2
Mode 2 : When the transistor switch S is open i.e. OFF-state, energy stored in the inductor is released through the fly-back diode D to the input RC circuit. Voltage across the boost inductor L and the source Vi, charges the capacitor C and also supplies the energy to the load R 6. The conduction path is as shown in fig. 3
When the boost converter operates in continuous mode, the current through the inductor (IL) never falls to zero. The converter waveforms in the CCM are shown in fig. 4
The switching period,
Voltage across the boost inductor,
INTERLEAVED BOOST CONVERTER
Proportional, Integral, Differential Controllers (PID)
In various industrial applications proportional, integral and differential controllers organization is most commonly use to improve the performance of the selected control system.
t Various combination of proportional (P), integral (I) and differential (D) controllers are shown below:
Proportional and Integral Controllers (PI)
Proportional and Derivative controllers(PD)
Proportional Integral and Derivative Controllers
tProportional controllers in which the actual signal is directly proportional to an error signal. An Integral controller in this controller actual signal is directly proportional to the integral of the error signal. Derivative controller in this controller actual signal is directly proportional to the derivative of the
t error signal 3 6 7. Proportional derivative (PD) controller improves the transient response of the system. Proportional integral (PI) controller reduces steady state error present in the system. The combination of PI and PD controller forms the PID controller, it involves P, I and D three different constant parameters. Signal which is present in between desired output and actual output is an error signal. PID controller operates directly on error signal. Advantages of PID controller are as faster response to change in the control input; control signal increases to lead steady state error towards zero and eliminates oscillations 6. By tuning the three constant the controller can provide the control action for the specific process. the factors on which the response of the controller depends are the responsiveness of controller for error, degree of system oscillation and the degree at which controller overshoots the set point 7.
For tuning to the PID controller, increasing parameter Kp, Ki and Kd have its own effects, it can be summarized as 7
In many case, PID tuning can be done by increasing the parameters Kp, Ki and Kd one by one. Firstly, the system needs to be determining what its characteristic need to be improving. Then the Kp parameter is use to decrease the rise time. After that the parameter Kd is use to reduce the overshoot, settling time and lastly eliminate the steady steady- state error using Ki parameter. When done tuning the parameters, the system need to be examined either it obtain or not acceptable stability. Acceptable stability is when the undershoot that follow the first overshoot of the response is small, or barely observable 7.
Advantages of PID controllers
PID controller which is independent of the model, simple in design and applicable for various fields has a predominant role in industrial control. Very fast response for change in the control input control signal increases to lead steady state error towards zero also eliminates oscillations
Disadvantages of PID controllers
PID controller technique cannot meet increasing requirements for fast dynamic response, high control precision. If there occurrence of uncertainties then the stability of this technique cannot be guaranteed.
1 Cacciato M., Consoli A., Attanasio R., and
Gennaro F. 2006. A multi-stage converter for domestic generation systems based on fuel cells. In Proc. IEEE Ind. Appl. Soc. Conf., vol. 1, pp. 230–235.
2 Xingyi Xu, Lizhi Zhu, “A DSP Based
Controller for High-Power Interleaved Boost Converters” APEC’03, vol. 1, pp.327-333, 9-13 February 2003.
3 Marian K. Kazimierczuk, ” Pulse–width
Modulated DC–DC Power Converters “, A
John Wiley and Sons, Ltd, Publication 2008.5 Lopamudra Mitra, Nibedita Sain, ” Closed Loop Control of Soalr Powered Boost Converter with PID Controller”, IEEE International Conference on Power Electronics, Drives and Energy System(PEDES), 2014
6 Mirza Faud Adnan, Md. Abdul Moin Oninda, Mirza Muntasir Nishat, Nafiul Islam, “Design and Simulation of a DC – DC Boost Converter with PID controller for Enhanced Performance “, IJERT, Vol. 6, 2017