Comparative Analysis of Peak Current Mode, Average Current Mode and Voltage Mode Control for Synchro

International Journal of Modern Research in Engineering & Management (IJMREM) ||Volume|| 2 ||Issue|| 7 ||Pages|| 01-08 || July 2019 || ISSN: 2581-4540

Comparative Analysis of Peak Current Mode, Average Current Mode and Voltage Mode Control for Synchronous Buck Converter 1,

Mansoor Mangrio, 2,Engr. Shafi Muhammad Jiskani, 3,Engr. Muhammad Rashid , 4,Engr. Noor Nabi Shaikh, 5,Iraj Mazhar 1,

Student M.E. (Electrical Power) IICT, Mehran UET Jamshoro Assistant Professor, Electrical Engg. Mehran UET, Jamshoro 5, Student B.E. Electrical Engg. Mehran UET, Jamshoro

23,4

---------------------------------------------------ABSTRACT------------------------------------------------------In this paper comparative analysis of three controller techniques for synchronous buck converter are presented.

One is voltage mode control (VMC) second one is crest current mode control and third is normal current mode control technique for synchronous buck converter. The voltage mode control adjusts addition also influence of the system dynamics performance as any variation in input voltage follows in the system. VMC cannot spot-on any disruption suddenly till that one is sensed at the output meanwhile the instabilities are hindered in point through the inductor and capacitor before the output changes. The voltage mode control does not contain protection of switches in the converter. The pinnacle inductor current (IL) controlled by the peak current mode control, innate pinnacle current restricting and distributing, worthy energetic presentation as shown in results sections. It include switches protections so, preferable control techniques to use in DC-DC synchronous Buck converters. While (ACM) average current mode control technique has least ripples in voltage as compared to other control techniques.

INDEX TERMS: VMC, CPM, ACM. ----------------------------------------------------------------------------------------------------------------------------- ---------Date of Submission: Date, 18 July 2019 Date of Publication: 05. August 2019 ----------------------------------------------------------------------------------------------------------------------------- ----------

I.

INTRODUCTION

DC-DC converters conquer actual weighty part in the arena of industries or daily life applications to charge batteries of lower voltages that are linked to continuous power supplies, DC-DC converters are required. Many DC-DC converters are available either to rise or to lessening the voltage as of source to the point of utilities [1].

Step down converter is also buck converter which excellently decreases voltage level of consistent with mandatory submission. When ON time increases diode in its roots better transmission facilities.. The competence of converter has less conduction losses. So, to realize great productivity is proposed for the synchronous buck converter [2].

For today’s VRs the dc to dc power converter is furthermost common topology. Freewheeling schottky diode is swapped in this converter MOSFET, the change in result in terrific transmission loss reduction the power metal oxide semiconductor field transistor, and then also shapes fresh tasks & desires. Most commonly issue regularly argued but not completely understand also said to be C dv/dt the loss of tempted switching MOSFETs castoff as synchronous rectifiers as shown in fig. 1 [3].

There are two control techniques intended for synchronous DC-DC buck converter

Fig 1. Synchronous Buck Converter [4].

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Comparative Analysis of Peak Current Mode‌ Single Loop Voltage Mode Control (VMC) :A single ring feedback a surrounded around a synchronous DCDC buck converter desires a manager that associates a non-natural saw tooth waveform (STW) beside a orientation worth to acquire one duty cycle for every independent. Every duty cycle of term VCM is directly related to control voltage [5]. Concept of VCM is shown in fig. 2.

Fig 2. DC-to-DC Converters for Voltage Mode Control [6] Double loop Peak Current Mode Control (PCM) : This type of controller is the widely used among current mode control techniques. The representative configuration of PCMC method is shown in Fig.3. Switching of the static switch is controlled on peak values of the duty cycle signal. It has quicker time response compared to VMC, and for power factor correction and DC converter PCMC is widely used.

Fig 3. CPM Method [8].

Average Current Mode Control :CMC, equated with VMC, offers some benefits for example easy paralleling of multiple converters, essential line aimed at automatic short circuit, overload protection, and feed-forward property. The CMC can be classified as: (i) Peak Current mode (PCM) Control or else current programmed controlled (CPM). (ii) Average Current Mode (ACM) Control. Application of average current mode control is shown in fig. 4.

Fig 4. Average Current Mode Control for Buck Converter [7]

II.

METHODOLOGY

System Model: For the required or regulated step-down DC voltage the DC-DC lowly converter is required.

Again Dc-DC buck converters have two main topologies (i) Diode lowly converter (ii) synchronous Lowly converter. From these two synchronous Buck converter is chosen in order to get rid of the reverse recovery losses.

The entire model of the DC-DC lowest converter is introduced in given figure 2. It comprises two semiconducting switches like MOSFET for switching performance activity while L and C utilized as low pass filter two remove

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Comparative Analysis of Peak Current Mode‌ ripples occurring now the yield power and output current. The capacitor as a low pass filter will remove voltage ripples by performing its charging and discharging action. Taking place, the further pointer inductor as resistance to current variation will filter out current ripples from the out current. As controller is the heart of any system to perform its action. So, Digital PID controller is designed using three different control techniques. Like conventional control technique which stays voltage mode control (VMC) and advance control techniques like average current mode control (ACM).

Design of Voltage Mode Controller for Synchronous Buck Converter : The voltage criticism game plan is identified for instance voltage-mode control once connected to any topology of dc-dc converters. This control technique is generally utilized in light of the fact that it is anything but difficult to plan and execute, and has great network to unsettling influences at the orientations contribution. VMC just covers single input circle from the yield voltage.

MOSFET Vout Inductor Load

Vin MOSFET

Digital PID Controller

PWM

Time Delay

Capacitor

Subtract VRef

Fig 5. Voltage Mode Control Technique for Synchronous Buck Converter The voltage mode controlled (VMC) synchronous buck converter circuit is showed up in figure 5. This one involves a deliberate catch (MOSFET), an excessive switch or diode, an inductor, a capacitor, and a pile hindrance R. Be that as it may, VMC have a couple of detriments. Any adjustment in information voltage will change the increase and impact the framework elements conduct. VMC can't right any unsettling influence promptly till this one is distinguished on the yield later the aggravations are postponed in stage by the inductor and capacitor preceding the yield.

Current programmed mode Control (CPM) for synchronous Buck Converter: Figure 6 the inductor current exhibit the waveform of a supplanting converters working in constant conduction mode (CCM). The (IL) inductor current vacillations by an inclination m1 during the principle sub interim, furthermore an inclination – m2 in the midst of the extra sub interim. The zenith inductor current remains controlled and the controlled technique is along these lines named apex current-mode control. The present mode controller is unreliable at whatever point the suffering state commitment cycle is more essential than 0.5, achieving sub-symphonic faltering. To avoid this trustworthiness issue, the control plot is regularly changed by means of figuring an outside slant to the recognized inductor current waveform. Let the grade of reimbursing slant is mom. right when ,by then the controller is consistent for all commitment cycles.

MOSFET Vout Inductor Load

Vin

MOSFET

Capacitor

Slope Comp Ramp

+ Time Delay

PWM

Digital PID Controller

Subtract VRef

Fig 6. Peak Current Mode Control Technique for Synchronous Buck Converter

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Comparative Analysis of Peak Current Mode‌ Favorable circumstances of pinnacle CMC incorporate mechanism of the pinnacle inductor current, inalienable pinnacle current constraining then distribution, great powerful execution, first request exchange work. A portion of the primary downsides of this control are the restricted obligation proportion, expanded yield impedance, subconsonant wavering, clamor affectability. These issues are redressed by methods for a fake slope flag whichever deducted after the rheostat ensign or further toward the inductor current gesture.

III.

RESULTS & DISCUSSIONS

The DC-DC synchronous buck converter has been given as an input voltage of 5 volts while, it gives an out voltage of 1.8Volts.

Results of Voltage Mode Control of Synchronous Buck Converter: Fig 7. Shows the LT Spice simulation model of VMC. Fig 9. Indicates the waveform of output voltage at 1.8vots through giving input of 5volts for the total duration of 600 micro seconds. In fig 9. It shows that by giving pulse at load variation in output voltage from 150 micro seconds to 175 micro seconds for the total duration of 25 micro seconds, the controller maintain its output waveform at 1.8vots.

Fig 7. Simulation of VMC Based Synchronous Buck Converters

Figure No: 8. Output Voltage Waveform of VMC Synchronous Buck Converter

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Comparative Analysis of Peak Current Mode‌

Fig 9. Load Variation Waveform for VMC Controlled Synchronous Buck Converter Results of Peak Current mode Control for Synchronous Buck Converters In Fig 10 it shows the LT Spice based Simulink model of peak current mode synchronous buck converter by inputting the pulse value in line and load variation. Fig 11 shows the two lines, upper line shows line variation waveform in which the input voltage is 5volts and by giving the pulse of 2 volts at 300 micro seconds for the duration 25 micro seconds. Lower line is indication the output voltage at 1.8volts and it is clearly indicating that how controller maintain its output voltage at 1.8volts by giving the pulse in input line at 300 micro seconds from 5 volts to 7 volts but controller maintained its output. Fig 12 shows the load variation waveform in which pulse is giving at the load side at 110 micro to 140 microseconds for the duration of 30 micro seconds and controller maintain its output at 1.8 volts.

Fig 10. Simulation of PCMC Based Synchronous Buck Converters

Fig 11. Output Voltage Waveform with Line Variation of PCMC Synchronous Buck Converter

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Comparative Analysis of Peak Current Mode‌

Fig 12. Load Variation Waveform from PCMC Synchronous Buck Converter Results of average Current Mode Control for Synchronous Buck Converters The switching circuit model used to validate only transient response and regulations so what about frequency response, crossover frequency and output impedance these issues can be further addressed by average current mode control. The simulation of average current mode control for synchronous buck converter is shown in fig 13 and fig 14 shows line variation at input side by giving the pulse at 300 micro seconds for the duration of 30 micro seconds and fig 15 shows the line variation at output voltage how controller maintain its output at 1.8volts. fig 16 shows load variation waveform.

Fig 13. Simulation of ACM Control for Synchronous Buck Converter

Fig 14. Line variation of ACMC for Synchronous Buck Converter

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Comparative Analysis of Peak Current Mode…

Fig 15. Line Variation of ACMC for Synchronous Buck Converter

Fig 16. Load Variation of ACMC for Synchronous Buck Converter

IV.

CONCLUSION

In conclusion, the response of voltage mode control (VMC) technique is slow and lethargic due to inclusion of inductor and capacitor. While, peak current mode control perform fast and has fats dynamic response as associated to the voltage mode control. The rise time for voltage mode control is 48us while, rise time for peak current mode control is 1us. The settling time for voltage mode control is 110us while the settling time for current programmed mode control is 19us. All in all, average current mode has better results in terms voltage ripples, settling time and rise time. The peak current mode control has fast dynamic response as compared to the voltage mode control technique.

V.

FUTURE WORK

These control techniques can also be applied on other topologies of DC-DC converters and also other 3 other types of converters, like DC-AC, AC-DC and AC-AC converter. These can be used in FACTS devices technology also.

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Comparative Analysis of Peak Current Mode…

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