This gives rise to many serious problems, including poor noise immunity, a need for slope compensation, and peak toaverage current errors which. Peak current mode and continuous current mode dctodc. Both peak current mode and voltage mode have been implemented and are available as possible options for the converter control. There has been a long history of the current mode control modeling.
Designing flyback converters using peakcurrentmode. Many previous attempts have been made especially for constantfrequency peak current mode control. Peak currentmode control lecture slides part 2 more accurate models ecen 5807 dragan maksimovic. Smallsignal model for a flyback converter with peak current mode control article pdf available in iet power electronics 74. More recently, it has been applied widely in pfc preregulator converters. Average current mode control of switching power supplies lloyd dixon abstract current mode control as usually implemented in switching power supplies actually senses and controls peak inductor current. Stepbystep design guide for digital peak current mode. The max17595 offers optimized input thresholds for universal input acdc converters and telecom dcdc 36v to 72. His landmark dissertation compared all of the different modeling approaches of the time, and developed a new model that accurately predicted the behavior of current mode power supplies. A updated model which includes all conduction losses is established. Using a peakcurrentmode controller to design a boost converter. Understanding and applying current mode control theory by robert sheehan for emulated peak current mode, the valley current is sampled on the downslope of the inductor current. Implementing peak current mode control of a switchmode power.
Robert mammano unitrode ic corporation has, since its inception, been active in the development of leadingedge control circuits to implement stateoftheart progressions in power supply technology. Loop compensation is often viewed as a very challenging design task by engineers, especially in fast load transient applications. Mp3910 controllers peak current mode boost pwm controller. Minimal external components are necessary to develop a complete stepdown dcdc converter power supply. The digital implementation of peak current mode control achieves the desirable cyclebycycle peak current limiting eect of the analog equivalent. Currentmode modeling for peak, valley and emulated control methods reference guide for fixedfrequency, continuous conduction mode operation robert sheehan principal applications engineer national semiconductor corporation santa clara, ca current mode control for current mode control there are three things to consider. This is used as the dc value of current to start the next cycle. The dss function greatly simplifies the design of the auxiliary. Design equations are given and a practical design for a 400 w board is illustrated and evaluated. The waveform is obtained assuming that the input voltage and the output voltage are constant over a switching period, and this assumption will hold during the entire analysis presented in this paper. A lot of pcm loop models are available for system design. Ridley tackled the challenging topic of current mode control. The max17595max17596max17597 is a family of peak current mode controllers for design of wide inputvoltage flyback and boost regulators. Peak current mode control of the output capacitor current.
Over the years many new products have been introduced to. Implementing peak current mode control july 2012 texas instruments 3 peak current mode control pcmc analog versus digital implementation in both implementations of pcmc, there is a plant our actual power stage and a control function. Boost converter with peak current mode control a widely used alternative to pulse width modulation pwm are the so called peak current mode pcm and average current mode acm. Pdf analysis and modeling of digital peak current mode control.
The current feedback loop with slope compensation is analyzed. Digital peak current mode control with slope compensation. An2388, peak current controlled zvs fullbridge converter. Loop response considerations in peak current mode buck. Understanding and applying currentmode control theory. Peak current mode control lecture slides part 2 more accurate models ecen 5807 dragan maksimovic. Abstract microcontroller based peak current mode control of a buck converter is investigated.
Peak current mode control pcmc is a popular control technique for dcdc converters due to the fast transient response, overload protection, accuracy and ease of compensation. High converter efficiency is achieved by integrating the current limited, low resistance, highspeed n. Peak currentmode dcdc converter stability analysis power. Max17595 peakcurrentmode controllers for flyback and boost. Pdf analysis and modeling of digital peak current mode. This paper presents analysis of peak current mode control for a buck converter operating in continuous conduction mode. The control signal addition of the sensor signal and the compensating slope is compared. Fast control technique based on peak current mode control of. Biricha digital power ltd biricha digital power ltd 9251 yonge street, suite 206, richmond hill, l4c 9t3, ontario, canada. Similar analysis can be equally applied to other types of converters. Peak current mode model the buck converter in figure 3 is used to describe the peak current mode model used in this application note. The mp3910 is a peak current mode pwm controller that can drive an external mosfet capable of handling more than 10a current.
Using the averaged switch modeling approach,a nonlinear largesignal averaged model of nonideal pwm switch is. Based on ridleys buck converter model with peak currentmode control. This solution is a peak current mode control with fixedofftime fot. Voltage mode control, one of the pulse width modulation techniques 23 revolutionized the power supply industry since its invention in 1976. This gives rise to many serious problems including poor noise immunity, a need for slope compensation and peak to average current errors which the inherently low current loop gain cannot correct. Nov 17, 2017 he came up with a solution of adding an inner current loop to the voltage loop and let the switch turn off when the switching current reached an adjustable threshold. The dynamic nonlinearity of current mode control results in the difficulty of obtaining the smallsignal model for current mode control in the frequency domain. Smallsignal model for a flyback converter with peak current. The output capacitor current is sensed with the non invasive method described in 4. Peak current mode dcdc converter stability analysis. Peak current mode control 4 was introduced a couple of years later which falls under a different class of pwm control.
Use the following equations to calculate the primary and secondary peak and rms currents. Based on the widely used peak current control mode continous current buck device, this article has summarized the average small signal mathmatical modeling and loop calculation, and the adisimpesimplis fast and easy. The tps560430 employs peak current mode control with internal loop compensation, which reduces design time, and requires few external components. Equivalent circuit model for current mode controls and its extensions yingyi yan abstract current mode control architectures have been an indispensable technique in many applications, such as voltage regulator, pointofload converters, power factor correction, battery charger and led driver. In this control configuration, the inductor current, il is chosen as the programming variable and is compared to. Implementing peak current mode control of a switchmode.
Peak current mode with constant switching frequency turns on the transistor at the beginning of each switching period. Along this tutorial, the peak current mode control is going to be applied to a buck converter. To access the configuration window of the peak current mode control, there are three possible paths. Learn how to design a booststepup converter design using a peak current mode controller. The buck pwm switch model and the smallsignal model for peak current mode control the openloop transfer function of a peak current mode buck converter is listed below 1, 2. Compensation design for peak currentmode buck converters. Mcp16301 high voltage input integrated switch stepdown. Peak and rms current calculation primary and secondary rms currents and primary peak current calculations are needed to design the transformer in switched mode power supplies. Peak current mode control technique peak current control mode is a well established control technique in power conversions. Pdf digital peak current mode control of boost converter. This course covers advanced converter control techniques, including averagedswitch modeling and spice simulations, modeling and design of peak current mode and average current mode controlled converters, as well as an introduction to control of singlephase ac grid tied rectifiers and inverters.
An inductor emulator approach to peak current mode control in. Fixed frequency current mode controller for flyback converters the ncp1234 is a new fixed. Click on the remarked and then on the dcdc converter icon peak current mode control. The peak current control implementation eliminates the need for the series capacitor by virtue of dynamic flux balancing. Design and analysis of current mode control of boost converter. Peak current mode control pcmc with slope compensation has advantages of automatic input line feed forward, inherent cyclebycycle overload protection, and current sharing capability in multiphase converters. A graphical user interface gui running under windows has been designed in order to help the user in the interaction with the demo board simply using a pclaptop through a serial communication uart. Design the control loops of a pfc power factor correction boost converter, with converter implemented in psim pfc boost converter 3khz. Understanding and applying currentmode control theory by robert sheehan for emulated peak current mode, the valley current is sampled on the downslope of the inductor current. Equivalent circuit model for current mode controls and its. In this case, a ramp equal to the sum of both the upslope and downslope is required. Peak currentmode control in an llc converter power. The equations derived according to the model will be applied in compensation design for peak current mode buck converters. Ncp1234 fixed frequency current mode controller for flyback.
Pdf smallsignal model for a flyback converter with peak. A and can accommodate flyback, boost for nonisolated and isolated applications. Average current mode control of switching power supplies. Average current mode control eliminates these problems and may be.1159 1337 364 1528 617 880 8 1232 1483 478 1017 354 993 381 1197 1268 1355 1428 665 690 1632 855 22 261 936 574 432 1612 1286 814 1482 335 446 162 601 806 404 1297