Poor noise immunity of Average Current Mode Control of Switching Power Supplies

Peak method for the control of inductor current have the following functions through comparing an upslope for the inductor current have the current programme where the level is set through an outer loop a shown in background section. Turns of comparator by the power switch off when an instantaneous current reaches a desired level. A ramp current is usually small which is compared by the programming level, especially when V_IN is low. The above method is extremely susceptible for the noise. As the noise is spike that is generated form each time and the switch is turn on. Volt coupled fraction for the control circuit that causes the turn off immediately, have the results of sub harmonic operating mode by the much greater ripple. Bypass and the circuit layout which is very important for the successful operation.   (Dixon, 1999)  

In above figure the slope which is rising for the inductor current of waveform is compared by the control current. Switching operation that is control by the current control.  As we know that, the ramp current is very small which is compared by the current control that is set through outer loop as well as however this method is less immune for the noise that is compared for the voltage mode control. In every time the switch is turned on. Then there is no spike generated; the current control is higher than the ramp current, since the fraction voltage coupled the outer loop that causes the switch turn off by the sub-harmonic oscillations through large magnitudes of ripple.

Current error peak to average Control of Switching Power Supplies

For the buck converters, the main problem is the average value for inductor is much higher than the noise ripple. Feedback loop of voltage compensates for the error of compensations. Inductor current is at peak which by controlled through modulator wave form the while of the average current is not. In the conduction mode the discontinuous error is higher for the sine wave of the modulators approaches for the zero half cycles. This error is made by the small as the possible to obtain the low distortion levels. The ripple is small for the noise; however, the size of the inductor has to large, and however it reduces the noise immunity as the inductor ripple gets smaller. (Kazimierczuk, 2008.)   

The necessity of Slope Compensation
of Average Current Mode Control of Switching Power Supplies

The Current mode control scheme is unstable, and the half of the switching frequency that gives the results of the sustained oscillations. The external ramp is needed for the comparators of the where the input is stable for the converter operation. The buck converter, where the inductor current is down to the slopes and then rises the input voltages rectified the sine waveform. The fixed external ramp is same in the most cases, and then over compensates the inductor current which will eventually give the performance and the distortions is also increased.

Topology problem of Average Current Mode Control of Switching Power Supplies

The peak value of the inductor current is controlled by the conventional control mode technique. In case buck-derived converter this technique is affected as the inductor current is on the load-side of the buck converter. But the inductor is not at the output and this is for the boost or else fly back scheme. In these schemes the average current should be controlled. Hence in these schemes with this type of topology most of the advantage of this technique is lost where the inductor is on the load-side. For the topology of boost and the fly back the input current control is more suitable (Kazomierczuk, 2008).

 Requirements of Average Current Mode Control of Switching Power Supplies

The purpose of the research paper is to use the UC3842 to implement the Buck converter for the ACMC of the SPS. UC3842 is the integrated PWM “Pulse width modulator," for the objective of obtaining good electrical performance, plus the low cost. All the performance benefits of the current mode control operations re-obtained, by this IC which is the inexpensive controller. Dc-Dc converter, transistors, regulators are the power sequencing for the off-line converter of the series of the UC3842.

 IC Selection of Average Current Mode Control of Switching Power Supplies

Selection of the maximum duty cycle for the UC3842 is approximately100%; it is claimed during mostly forward and the fly back Converter. The performance and the dead time are not exceeding the 15% of the oscillators with clock period. The output is at low states duty the internal clock signal for the discharge and the dead time, which limit the maximum duty cycle;

The UC3843 is used to create the Synchronous pulse by minimum external components. To drive the MOSFET gates, the UC3842 has a single totem-pole output that can be operating at plus the 200mA average current. (Soloelectronica.Net)

The UC3842, since the current input is configured in the below figure 3; where the Current to Voltage is done externally by the ground referenced of Rs resistors. The normal operations for the peak voltage across the Rs are controlled through the Error amplifier by the below relation;

The Control to sensed current gain; for the small signal analysis;

Prediction of model of Average Current Mode Control of Switching Power Supplies

By using the MATLAB, the below picture is used as the predictions of the model, the buck converter in CCM is used to creating the projection of the model with the following parameters as assumptions

The most popular technique is the Current Mode Control that issued for the operation of the SMPS, CMC also has the inner and the outer loop, that control the peak current of the inductor. Component of the project plan; the scope of the Final year project is that we researched on the different topologies which are used in the ACMC for the SPS, because of the

ACMC eliminates many problems. CMC is one of the methods in the digital controller to explore the potential is for research. ACMC is dealing with the noise issues to improve the design flexibility. The performance level is better for the CMC that issued in the digital controller. PSM is also caused the audio noise and reduce the board life because of the resonance of mechanical capacitor as well as coils (Vekslender & at, 2017).

GOAL of the FYP should think of “SMART” Specific, measurable, achievable, Realistic, Time.

Four members are working on the project “Average Current Mode Control of Switching Power Supplies." In this project build the synchronous buck converter by using UC3842 and compare the practical and the simulation results. All the objectives should be measured and obtained in the given period. In this project, the time that is taken to fulfil all the requirements is approximately one year (A & D, 2016). 

The project deliverable includes the Hardware, software, app assessment results. By using the MATLAB implemented the circuit of the buck converter in the ACMC which is shown in figure 2 above.

Being an only person working on this project, there are so many responsibilities which to be performed. My first responsibility is to build the required hardware circuits with all basic circuit and component the circuits. Secondly, I will manage operations of the software, like on MATLAB, all the required course is implanted as shown in this project. Then, I will maintain/manage the entire management problem; fulfil all the requirements, components. At the end, report will be drafted. The time of this project is approximately one year, and the cost of the project is around about $500 (maximintegrated, 2006).

Gant Chart of Average Current Mode Control of Switching Power Supplies

Reference of Average Current Mode Control of Switching Power Supplies

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N.Vishwanathan, & V.Ramanarayanan, D. (2002). Average Current Mode Control of High Voltage DC Power Supply for Pulsed Load Application. IEEE.

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Soloelectronica.Net. (n.d.). UC3842/3/4/5 PROVIDES LOW-COST CURRENT-MODE CONTROL. Retrieved from http://www.soloelectronica.net/PDF/AppNote03.pdf

Vekslender, T., & at, a. (2017). Fully-Integrated Digital Average Current-Mode Control 12V-to-1.xV Voltage Regulator Module IC. IEEE.

Ying Qiu, H. L., & Chen, X. (2010). Digital Average Current-Mode Control of PWM DC–DC Converters Without Current Sensors. IEEE TRANSACTIONS ON INDUSTRIAL ELECTRONICS, 57(5).