Boost converter maximum ratio

V L across L1 in series with each other. Although the charge C1 drains away through the load during this period, C1 is recharged each time the MOSFET switches off, so maintaining an almost steady output voltage across the load. Because the output voltage is dependent on the duty cycle, it is important that this is accurately controlled. For example if the duty cycle increased from 0.

Before this level of output voltage was reached however, there would of course be some serious damage and smoke caused, so in practice, unless the circuit is specifically designed for very high voltages, the changes in duty cycle are kept much lower than indicated in this example.

See the current paths during the on and off periods of the switching transistor. Note that the operation during the first "On" period is different to later periods becaust the Capacitor C is not charged until the end of the first "On" period.

See the magnetic field around the inductor grow and collapse, and observe the changing polarity of the voltage across L. Watch the effect of ripple during the on and off states of the switching transistor.

See the input voltage and the back e. Because of the ease with which boost converters can supply large over voltages, they will almost always include some regulation to control the output voltage, and there are many I.

In this circuit, an appropriate fraction of the output voltage V OUT , dependent on the ratio of R2:R3 is used as a sample and compared with a reference voltage within the I. This produces an error voltage that is used to alter the duty cycle of the switching oscillator, enabling a range of automatically regulated boost voltages between 5V and 28V to be obtained.

The LM contains an internal oscillator operating at a fixed frequency of about 1. Notice also that a Schottky diode with an appropriate voltage and current rating is used for D1 to keep losses due to the forward voltage drop of the diode as small as possible, and to enable high switching speeds to be achieved.

The inductor loss due to the resistance is a major design parameter. The selection of the ratio and switching devices losses are the major contributors in the efficient operation of the converter.

The golden section search is a technique for finding extremum minimum or maximum by sequentially narrowing the range of values inside which extremum exists. The main aim is to find maximum functional value of within the input interval. Two points and are selected in the interval and function is evaluated at these points.

Assume a line segment as shown in Figure 4 b. Then ; that is, ; hence. Consider ; that is, is 0. For a GSS based MPPT for photovoltaic system, the characteristics are the operating characteristics wherein corresponds to power, whose maximum value has to be tracked. The range of operation is from zero to open circuit voltage ; that is, and as shown in Figure 4 b. The way of tracking maximum point is shown in Figure 4 a. The voltage corresponding to the maximum power is obtained and mapped into the characteristics to obtain the current reference.

MPPT is used to track the maximum power under different atmospheric conditions; this method is robust and also has a fast response as compared to the conventional MPPT algorithms. This algorithm has guaranteed convergence under continuous variable irradiance and temperatures. The algorithm for generating the PV characteristics is presented in Figure 5 a. The inductor current feedback is used to generate the error by comparing it with the reference current generated by the GSS algorithm and it is processed through proportional P controller.

This P controller changes the duty ratio according to error and governs the PV to track the maximum power point on its characteristics. Capacitors and are alternatively charged to their voltages and. Even though both capacitor values are equal, there is a voltage unbalance between output capacitors due to mismatch of two real capacitors and equivalent series resistance.

The voltage balancing controller is required to maintain the equal voltages across these capacitors through duty cycle control and is implemented as shown in Figure 7. In the three-level boost operation of the DC-DC converters with duty ration relates the fact that the input and output voltage are given as If , then where the input DC voltage is PV input voltage and varies with respect to varying environmental conditions.

The duty ratio of the boost switch is determined by the MPPT control and duty ratio of the boost switch is determined by the additional controller. The PI generates the duty from the voltage error obtained from. Consider where is the transfer function of the PI controller. The duty cycle controls switch of the converter to balance the voltage across the capacitors. In this section, the converter operation with the MPPT control and voltage balancing is presented through simulation.

The PV panel parameters are given in Table 1. The steady state and dynamic operation are presented for the various operating conditions.

The simulated results under steady state are shown in Figure 8. The converter operation with MPPT control and capacitor voltage balance activation at 0.

The voltages across these capacitors are maintained at the same value after the balancing; the voltage converges to a The MPPT algorithm with converter under varying irradiation levels and various loading condition is tested.

It is observed that the voltage is controlled after the load variation and maintained to The performance is evaluated under the partial shading. The partial shading characteristics are used to test the performance with local and global peak as given in Figure The reference voltage generated by these methods are given in Figure 12 with the number of iterations required by these methods.

The variation in the generated reference is stable in GSS as it is tracking the local and global peak. The parameters of the hardware are built with the same parameters as given in Table 2. The block diagram of hardware prototype built is shown in Figure The interfacing drivers with isolation circuit using TLP are built. The photograph of the hardware prototype built is shown in Figure Figure 15 shows the measured power generated by PV and current and voltage across it.

The PV current is controlled to maximum power point current 2. The voltages across the capacitors are indicating different voltages and they are balanced as the controller is activated. Figure 17 shows the controller tracking the maximum power with change in the current. The voltage balancing loop is also tested under load change and response shown in Figure The capacitor voltages are unbalanced before applying control loop.

The MPPT effectiveness is measured by measuring the efficiency. This is defined by the ratio of maximum power to the power tracking by MPPT. The variation of the inductor resistance by way of wire gauge selection influences the efficiency and it is indicated in Figure Use of switching device and its switching frequency in a converter has a trade-off with the losses in the inductor. The three-level boost converter is used to interface the PV system for maximization of the power extraction.

The new maximum power point tracking algorithm based on the golden section search method is implemented. This algorithm shows the better dynamic response with the faster convergence without any oscillations while tracking. The voltage balancing of the DC bus is executed through the PI controller and performance is observed to be satisfactory.

The steady state performance of the converter shows the balance voltage operation across the DC bus. It is indicated that the performance of the presented converter with varying irradiation as well as the load change is also in line with the simulation results. The authors declare that there is no conflict of interests regarding the publication of this paper. This is an open access article distributed under the Creative Commons Attribution License , which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Article of the Year Award: Outstanding research contributions of , as selected by our Chief Editors. Read the winning articles. Chouki Balakishan, 1 N. Determine duty cycle. Consider the buck-boost converter shown. Switch Q is operating at 25 kHz and 0.

Assume diode and switch to be ideal. Consider the boost converter shown. Switch Q operating at 25 kHz with a duty cycle of 0. Assume the diode and switch to be ideal. Round off to 2 decimal places.

A boost converter with an input voltage of 5 V dc and an output voltage of 10 V dc will have a duty cycle of. The circuit shown employs 2 choppers to supply the load. This chopper drive is:.