Our Kickstarter project is live – join us to bring E-Tac-Toe to life!

DC to DC Boost Converter

Disclaimers:

1. This tutorial is for educational purpose only and neither the author nor this website makes no warranty, representation, or guarantee regarding the information contained herein or any product based on this tutorial or use of any components or circuit design.

2. --- This project was submitted to EE458 - Design of Power System Components - class at California State University, Long beach.--- So, make sure to cite!

APA Citation:

Dual Polarity Variable Linear Power Supply. (2019, December 27). Retrieved MM/DD/YYYY, from https://www.fwdskillzone.com/variable-power-supply.html.

In this project, we delve into the intricacies of a DC to DC Boost Converter, a pivotal component in power electronics, particularly for elevating voltage levels efficiently. There are many different switching voltage regulator topologies like buck, boost, buck-boost, and chuck. However, this paper covers the design and construction of a boost converter only. This converter is capable of boosting a 12V input voltage to a variable 12 to 24V output voltage (potentiometer controlled). The boost converter steps up the input voltage by storing the electrical energy in an inductor and then releasing this energy to the load at a higher voltage level.

Throughout this project, we explain how to make and use this boost converter step by step. We talk about the parts you need and how to put them together. We also show you how to control it so that it gives out just the right amount of power.

By focusing on this boost converter, we hope to show you how useful and versatile it can be. Whether you're into electronics or just curious, we'll help you understand how to make and use one effectively for your projects.

The Basics:

At its core, the boost converter is a type of power-up tool known for its "step-up" ability. Picture it like this: it takes a lower voltage and amps it up to a higher one. How does it do this magic? Well, it works by doing a little dance with an electronic switch – sometimes it's on, sometimes it's off. The main working principle of the boost converter is that when the MOSFET is on, the inductor stores energy in the form of magnetic energy and discharges it when the MOSFET is open as shown in the figures below.

Here's the secret sauce: Inside the boost converter, there's a part called an inductor that acts like a little energy storage unit. It holds onto electricity for a bit, then lets it out in bursts. But here's the cool part: when it releases that energy, it sends it out at a higher voltage than what it took in.

So, imagine you give it a gentle 12-volt nudge. The boost converter grabs that and says, "I can do better!" and sends out a stronger jolt, like maybe 24 volts. It's like turning a small stream into a mighty river, all thanks to this clever switching and energy-storing trick. That's the boost converter in action – making power go up and up!

Transistor Off State

Transistor On State

Objectives:

The main goal of this project is to create and examine a boost converter circuit. This circuit should be able to take a 12V input and boost it up to an output ranging from 12V to 24V. We'll guide you through the process of designing this boost converter, using a special chip called the MAX1771 step-up switching controller IC to help control and manage the boosting process.

In addition to designing the circuit, we'll show you how to make a printed circuit board (PCB) and a 3D-printed case to house everything. This way, you'll have a complete prototype design ready to go. By the end of this tutorial, you'll have a solid understanding of how boost converters work and how to build one yourself, from start to finish.

Circuit Design:

The design of our boost converter takes the following requirements into consideration. The Schottky diode has to be a high-speed rectifier, the MOSFET has to be a logic level, capacitors need to have low ESR, and the inductor has to be magnetically shielded. The following table summarizes the requirements and the desired rating of the components used by this Boost converter.

Here's a summary of the requirements and desired specifications for the components used in our boost converter design:

Schottky Diode:

Requirement: High-speed rectifier
Desired Rating: Fast switching speed and low forward voltage drop

MOSFET (Metal-Oxide-Semiconductor Field-Effect Transistor):

Requirement: Logic level
Desired Rating: Able to switch on and off rapidly at low voltages

Capacitors:

Requirement: Low Equivalent Series Resistance (ESR)
Desired Rating: High capacitance for energy storage, low ESR for efficiency

Inductor:

Requirement: Magnetically shielded
Desired Rating: Provides smooth current flow, minimizes electromagnetic interference

Boost converter requirements

Calculations:

1- Output calculations:

The boost converter sets the output voltage with a resistive voltage divider network connected to the MAX1771 gate driver and controller as shown in the figure. With the given feedback voltage from the datasheet, VFB = 1.5V, and desired voltage output 12V to 24V, the values of R1 and R2 can be determined. For adjustable-output operation, R2 is in the range of 10kΩ to 500kΩ and we have selected 20KW (10K resistor + 10K potentiometer).

Then, R1 is calculated as follows.

Where:

VOUT = output voltage
VFB = feedback voltage

To find the calculated output voltage, we have to use the following formula from the MAX1771 datasheet.

2- Duty Cycle calculation:

The duty cycle refers to the ratio of time a system is active compared to the total time of its operation. In electrical engineering and electronics, it specifically indicates the proportion of time during which a signal is in an active state compared to the total time of one cycle.

For example, in the context of a boost converter, the duty cycle represents the fraction of time during which the electronic switch (like a transistor or a MOSFET) is turned on, allowing current to flow, versus the total time of the switching cycle. This on-off switching action controls the output voltage of the boost converter.

A duty cycle of 0% means the system is always off, while a duty cycle of 100% means the system is always on. In practical terms, duty cycles often fall between these extremes, representing different levels of activity or output.

For our Boost converter, the duty cycle is calculated using the following formula.

So, the duty cycle (D) of our boost converter ranges from 0 to 0.55, corresponding to the output voltage ranging from 12V to 24V.

3- Inductor Value calculation:

An inductor is a passive electronic component that stores energy in the form of a magnetic field when electric current flows through it. It consists of a coil of wire wound around a core, typically made of ferromagnetic materials like iron or ferrite.

When current flows through the coil, it creates a magnetic field around the coil. The strength of this magnetic field is directly proportional to the amount of current flowing through the inductor. When the current changes, the magnetic field also changes, and this change induces a voltage in the coil, according to Faraday's law of electromagnetic induction.

Inductors are commonly used in electronic circuits for various purposes, including filtering out noise, smoothing out voltage ripples, storing energy, and creating magnetic fields in applications like transformers. They are characterized by their inductance, measured in henries (H), which indicates how much energy they can store per unit of current.

Before we calculate the inductor value, we have to take the recommended estimation of inductor ripple current in the datasheet that is from 20% to 40% of the output current. Our maximum expected current is 1A, and let's use 40% ripple current (worst case scenario). Similarly, the maximum frequency is obtained from the datasheet that is 300kHz. Using this information, the inductor value is calculated as follows.

Note: this is the critical inductor value. The actual inductor value has to be higher than the critical value.

4- Output Capacitor Value Calculation:

In a boost converter, the output capacitor plays a crucial role in stabilizing the output voltage and reducing ripple.

When the boost converter's switch (typically a transistor or a MOSFET) turns on, current flows through the inductor, storing energy. When the switch turns off, the energy stored in the inductor is released, but it also causes fluctuations in the output voltage.

The output capacitor helps smooth out these fluctuations by storing and releasing energy as needed. It acts as a reservoir, supplying additional current to the load when the switch is off and absorbing excess current when the switch is on.

Choosing the right value for the output capacitor is important to ensure that the output voltage remains stable and the ripple is minimized. It is typically selected based on factors such as the desired output voltage ripple, output current, and switching frequency.

In order to calculate the value of the output capacitor, first we need to determine the expected output ripple voltage. Set the desired output voltage ripple to be 1% as per the recommendation from the MAX1771 datasheet. Then, the output capacitor is calculated using the following formula.

The frequency of the MAX1771 is obtained from the datasheet (300kHz), the maximum required current for our boost converter is 1A. Then, using these values, the minimum capacitor value is determined as follows:

Note: this is the critical cappcitor value. The actual capacitor value has to be higher than the critical value.

Circuit Diagram

This circuit diagram illustrates the design of the boost converter using the MAX1771 gate driver and controller as the main component. The components are arranged according to their connections and functionalities.

The MAX1771 gate driver and controller is positioned at the center of the diagram, signifying its central role in controlling the boost converter operation.

The input voltage source, ranging from 2V to 16V, is connected to the VIN pin of the MAX1771.

The Schottky diode, MOSFET, input capacitor, output capacitor, and inductor are connected in a specific configuration around the MAX1771, as per the design requirements and calculations provided earlier.

The feedback pin of the MAX1771 is connected to a resistive voltage divider network, allowing for adjustable output voltage settings.

Each component is labeled with its corresponding values and ratings, ensuring clarity and ease of identification during the construction process.

This circuit layout is designed to optimize space utilization and component placement, facilitating efficient assembly and operation of the boost converter.

Boost converter Circuit Diagram

Circuit explanation:

The boost converter circuit is divided into three main sections: the Input, Boost, and Output sections, each serving specific functions in the operation of the converter.

Input Section:

The Input section serves as the starting point of the boost converter. It includes primary and secondary input ports, which can be selected using the jumper "JMPR1." Additionally, it features a single pole single throw switch, a reverse current protection diode, and a safety fuse to ensure safe operation. An input filter capacitor helps smooth out any fluctuations in the input voltage, while an input voltage display provides real-time measurement capabilities ranging from 0 to 99 volts.

Boost Section:

The Boost section is where the magic happens. It includes a jumper-selected input port for the gate driver, allowing for the use of either the same input voltage as the boost circuit or an external input DC barrel jack, which can be selected using "JMPR2." This section also comprises an input filtering capacitor to further stabilize the voltage, a gate driver to control the switching of the MOSFET, and an N-channel enhancement mode MOSFET itself. The inductor and Schottky diode work together to boost the input voltage to the desired output level. A voltage divider network, current sensing resistor, and potentiometer help fine-tune the output voltage to the desired range.

Output Section:

Finally, the Output section is responsible for delivering the boosted voltage to the load. It includes output filter capacitors to smooth out any remaining ripples in the output voltage. The output port provides a connection point for the load, while an output voltage display allows for monitoring the output voltage. The voltage meter display used in this project offers precise measurement capabilities from 0 to 99.9 volts with a low current draw, making it ideal for this application.

Circuit analysis:

To analyze the boost converter circuit, we'll use Matlab Simulink to simulate its various stages. The circuit is designed to step up a 12V input voltage, and we'll vary the load to assess its performance under different conditions.

Input Voltage:

The input voltage to the boost converter is set at 12V, representing the typical voltage supplied to the circuit.

Load Variation:

We'll vary the load connected to the output of the boost converter to observe how the circuit responds under different load conditions. This will help us understand the converter's ability to maintain stable output voltage levels across a range of loads.

Simulation Setup:

Using Matlab Simulink, we'll model each component of the boost converter circuit, including the MAX1771 gate driver, MOSFET, inductor, Schottky diode, capacitors, and resistors.
We'll define the characteristics of each component based on their datasheet specifications and the values selected during the design phase.
The simulation will run for a specified duration, allowing us to observe the transient response of the circuit as well as its steady-state behavior.

Analysis:

During the simulation, we'll monitor key parameters such as input voltage, output voltage, output current, and ripple voltage.
We'll assess the converter's efficiency, voltage regulation, and transient response under varying load conditions.
By analyzing the simulation results, we'll gain insights into the performance of the boost converter and identify any areas for improvement or optimization.

Boost converter Simulink simulation

After configuring the circuit with the desired component values, we initiated the simulation with a duration of 0.05 seconds. Observing the simulation results, we noticed an initial spike in the output voltage, peaking at 34.9V for a brief period before settling down to the desired output voltage of 24V. This transient behavior is expected during the startup phase of the boost converter as it reaches steady-state operation.

Similarly, the load current exhibited a spike, reaching 2.2A momentarily before stabilizing at 0.44A, reflecting the converter's ability to regulate the output current within the specified range under varying load conditions. These transient spikes in voltage and current are inherent to the operation of the boost converter and are within acceptable limits for the desired performance.

Overall, the simulation results confirm that the boost converter is functioning as intended, providing stable output voltage and current levels within the specified parameters. Further analysis and optimization can be performed based on these simulation results to fine-tune the converter's performance and efficiency.

PCB and Enclosure Design

1- Printed Circuit Board (PCB)

Designing the Printed Circuit Board (PCB) for the boost converter can be efficiently accomplished using the Eagle CAD program, available for download from the Autodesk website. This software offers a comprehensive suite of tools for seamlessly integrating schematic diagrams, component placement, circuit routing, and utilization of component libraries.

The design process typically begins in the "schematic" view within Eagle CAD. Here, designers can place and orient symbols representing the various components of the boost converter circuit onto a blank schematic sheet. These components include the MAX1771 gate driver, MOSFET, inductor, capacitors, resistors, and other necessary elements.

By organizing and connecting these symbols in the schematic view, designers create a visual representation of the boost converter circuit's electrical connections and functionality. This step is crucial for ensuring accurate translation of the circuit design to the physical PCB layout.

Once the schematic design is finalized and verified for accuracy, designers proceed to the "board" view within Eagle CAD. Here, the physical layout of the PCB is created, with components arranged and connected according to the schematic design. Designers utilize the software's routing tools to trace the connections between components, ensuring optimal signal integrity and minimal interference.

Throughout the PCB design process, designers can take advantage of Eagle CAD's extensive component library, which offers a wide range of pre-existing component footprints and symbols. This library streamlines the design process and ensures compatibility with industry-standard component specifications.

Although the free version of Eagle CAD imposes limitations, such as a maximum of two schematic sheets, double-layer PCBs, and an 80-cm2 board area, designers can still create professional-quality PCB designs suitable for the boost converter project.

Eagle CAD schematics drawing

Next, electrical connectivity is made between each part with a net layer and assigned values and names to our parts. Finally, make sure everything is connected as per the design by running an Electrical Rule Check (ERC). Once the schematic is completed, switch to the “board” page and position the components into their actual placement. Then use the “PCB Trace Width Calculator” tool to calculate the race width and route the corresponding wires with an appropriate trace width of 55 mil. Then, create a copper pour of the ground plane on both the top & bottom layers of the PCB and connect these ground planes with multiple “Vias” to deliver heat to the opposite layer of the board and to highly reduce heat resistance.

In order to minimize electromagnetic interference, a cut should be made on the ground plane where the inductor will be mounted. A best practice is to Keep the return path away from noise-causing areas, such as an inductor.

Finally, a Design Rule Check (DRC) is performed to validate the design meets the industry standards. Then, all the DRC errors were fixed, and validation was confirmed by the “DRC: No error” message. After adding silkscreen and text to the board, the design is converted to a Gerber file format using the CAM Processor in Eagle CAD, and the Gerber file is sent to a PCB manufacturing company.

Boost converter PCB component assembly

Once the PCB is fabricated, all the components are soldered onto the PCB as shown in the figure below.

PCB Assembly

1. Preparation

Gather Tools and Materials: Soldering iron, solder wire, flux, tweezers, wire cutters, multimeter, and safety gear.
Clean the PCB: Ensure the PCB is clean and free of dust, oils, or oxidation. You can use isopropyl alcohol and a lint-free cloth for cleaning.

2. Component Placement

Sort Components: Group the components by type (resistors, capacitors, ICs, etc.) and arrange them in the order of placement.
Insert Through-Hole Components:
Start with the lowest profile components such as resistors and diodes.
Bend the leads of the components and insert them into the corresponding holes on the PCB.
Slightly bend the leads on the solder side of the PCB to hold the components in place.
Place Surface-Mount Devices (SMD): If the PCB has SMD components, apply a small amount of solder paste on the pads, place the SMD components using tweezers, and use a reflow oven or a heat gun to solder them.

3. Soldering Through-Hole Components

Set Up Soldering Iron: Heat the soldering iron to the appropriate temperature (typically around 350°C/660°F).
Apply Flux: Apply flux to the joint area to help the solder flow and create a good connection.
Solder the Joints:
Place the soldering iron tip on the component lead and the PCB pad simultaneously to heat both parts.
Feed solder wire into the joint, allowing it to flow and cover the connection.
Remove the soldering iron and let the joint cool without disturbing it.
Inspect Joints: Check for shiny, smooth solder joints. Reheat and add more solder if necessary for any dull or incomplete joints.

4. Soldering ICs and Other Sensitive Components

Use IC Sockets: For ICs like the MAX77112EPA shown in the image, consider using sockets to avoid direct heat damage.
Heat Sinks: Use a heat sink or clip on the leads of heat-sensitive components to prevent overheating.
Solder Quickly: Solder the leads quickly to minimize heat exposure to sensitive components.

5. Final Component Placement

Large Components: Place and solder larger components such as capacitors, inductors, and heat sinks last.
Verify Polarity: Ensure that polarized components (diodes, electrolytic capacitors) are placed correctly according to the markings on the PCB.

6. Inspection and Testing

Visual Inspection: Inspect all solder joints for quality and completeness.
Remove Excess Flux: Clean any remaining flux residue using isopropyl alcohol and a brush.
Electrical Testing: Use a multimeter to check for continuity, short circuits, and correct component placement.
Power Testing: Carefully apply power to the circuit and verify correct operation. Start with a low current limit and gradually increase it.

7. Troubleshooting

Identify Issues: If the circuit does not work as expected, identify and correct any misplaced components, cold solder joints, or short circuits.
Rework: Use a desoldering pump or braid to remove and correct any faulty solder joints.

2 - Enclosure 3D model

Designing the enclosure for the boost converter project can be accomplished using SolidWorks or any other 3D design tool capable of creating precise and detailed models. The enclosure dimensions are specified as 125 x 100 x 64.5 mm, providing ample space to house the boost converter circuitry while ensuring a compact and aesthetically pleasing design.

Once the enclosure design is completed in the chosen 3D design software, the model is converted to the .stl file format, which is compatible with most 3D printers. This file format accurately represents the geometry of the enclosure, including its shape, dimensions, and features.

For this project, ABS M30 (Acrylonitrile Butadiene Styrene) material in orange color is selected for 3D printing the enclosure. ABS is a popular and versatile material commonly used in 3D printing due to its strength, durability, and heat resistance properties. These characteristics make ABS ideal for enclosures and housings, providing protection for the boost converter circuitry while ensuring longevity and reliability.

Boost converter enclosure

Once the .stl file is prepared, it can be sent to a 3D printer equipped with ABS M30 filament for fabrication. The 3D printer will accurately reproduce the enclosure model layer by layer, resulting in a finished product that meets the specified dimensions and design requirements.

The final 3D printed case will provide a robust and visually appealing housing for the boost converter, offering protection for the circuitry while maintaining compatibility with the project's aesthetic preferences. With the enclosure design completed and the 3D printing process underway, the boost converter project is one step closer to completion.

Output Test

The output test is performed by setting the potentiometer of the boost converter to the highest voltage output and by connecting two loads in parallel (a DC motor and computer fan rated from 12V to 24V). At this point, the boost converter can provide an output voltage of 17.8V to the load. The same setting provides 24.4V output at no load as shown in the figure below.

During the output test of the boost converter, the potentiometer is adjusted to the highest voltage output setting. Two loads, a DC motor and a computer fan, both rated for operation within the 12V to 24V voltage range, are connected in parallel to the output of the boost converter.

Upon conducting the test, the boost converter demonstrates its ability to provide a stable output voltage of 17.8V to the connected loads. This voltage level falls within the specified operating range of the loads and ensures proper functionality without exceeding their rated voltage limits.

Additionally, when the boost converter operates with no load connected, it delivers a slightly higher output voltage of 24.4V. This phenomenon, known as "no-load voltage," is common in boost converters and occurs due to the absence of load resistance, allowing the output voltage to rise to its maximum level.

Overall, the output test confirms that the boost converter effectively regulates the output voltage within the desired range, providing sufficient power to the connected loads while maintaining stability and reliability. This successful test demonstrates the functionality and performance of the boost converter in real-world applications.

No load output (left) and full load output (right) at the maximum output potentiometer setting

In conclusion, the Boost Converter project has been a success, demonstrating the design, construction, and performance evaluation of a versatile voltage-boosting circuit. Throughout this project, we have explored the principles of boost converter operation, component selection, circuit design, PCB layout, enclosure design, and output testing.

The design process involved careful consideration of component specifications, such as the MAX1771 gate driver, MOSFET, inductor, Schottky diode, and capacitors, to ensure optimal performance and efficiency. Using simulation tools like Matlab Simulink, we analyzed the circuit's behavior and verified its ability to regulate output voltage and current under varying load conditions.
The PCB layout was meticulously crafted using Eagle CAD, adhering to design guidelines and ensuring proper signal routing for minimal interference. The enclosure design, created in SolidWorks, provided a robust and aesthetically pleasing housing for the boost converter circuitry, enhancing its functionality and appearance.
The output test validated the boost converter's ability to deliver stable output voltage to connected loads, meeting the project's specifications and demonstrating its suitability for real-world applications. The successful outcome of the output test reaffirmed the effectiveness and reliability of the boost converter design.

Overall, this project has provided valuable insights into the design and implementation of boost converter circuits, equipping us with knowledge and skills that can be applied to future projects in the field of electronics and electrical engineering. The Boost Converter project stands as a testament to the power of innovation, collaboration, and hands-on learning in the pursuit of technological advancement.

»»» END of Boost Converter Design »»»

Next -> Flight Sim Hardware

Google Sites

Report abuse