The Fundamentals of Switched Mode Power Supplies
Switched-mode power supplies, or SMPS, are important parts of all electronic devices. They provide the needed power for these devices to work. The prominence of SMPS has grown due to their superior efficiency and reduced size.
In this blog, we’ll look at SMPS, how they work, their benefits, and how they’re not like linear power supplies. We’ll also explain how to join two SMPS together for more power. Last, we’ll talk about new things and future ideas in the world of SMPS.
This guide is for anyone interested in electronics, engineering, or working with SMPS. It aims to enhance your understanding of SMPS.
Short note on SMPS
SMPS are power supplies that use semiconductor switching to convert electrical power. SMPS manages output by turning a power switch, making less heat than other power supplies.
SMPS offers many advantages that make them vital in modern electronics:
High Efficiency: SMPS is efficient since they waste less energy as heat. This higher efficiency also means they use less energy, making them a better choice.
Compact Size: SMPS are smaller and lighter because they don’t need big transformers. This makes them ideal for small, carry-around gadgets.
Flexibility: SMPS handles variable power levels while maintaining stability, enabling versatility in applications.
Cost-effective: SMPS may cost more at first but save money in the long run due to their energy efficiency.
SMPS is used in many gadgets like computers, TVs, big machines, and telecom gear. Ongoing advancements in SMPS technology shape the future of electronics.
The Basics of Switched Mode Power Supplies (SMPS)
Definition of SMPS and How it Operates
A Switched Mode Power Supply (SMPS) is a good way to change small DC-to-DC or AC-to-DC power. SMPS uses components like switches, inductors, and capacitors to control and manage power. They use a technique called pulse width modulation (PWM) to control output. Switching devices enable smaller energy storage components and a compact, lightweight design.
Different Types of SMPS: DC-DC, AC-DC, DC-AC, AC-AC
There are various types of SMPS designed to meet specific power conversion needs:
DC-DC Converters: These are used to convert one DC voltage level to another. They are used in devices like laptops and mobile chargers.
AC-DC Converters: These convert AC voltage from the mains to a DC voltage. They are used in desktop computers, gaming consoles, and most home appliances.
DC-AC Converters: Also known as inverters, they convert DC voltage into AC voltage. They find use in solar power systems and uninterrupted power supply systems (UPS).
AC-AC Converters: These devices change the AC voltage level without affecting the frequency. They’re used in things like light dimmers or controllers for electric motors’ speed.
Importance of SMPS in Various Industries
SMPS technology plays a critical role across a multitude of industries:
Industrial Applications:
SMPS units are used in factories to change and give power. They are found in machine tools, welding systems, and robotics.
Medical Devices:
SMPS units are important for medical tools because they help them work. This is particularly important for life-saving devices.
Automotive:
In electric and hybrid cars, SMPS units are used to handle and manage how power is shared. This helps improve performance and extend the battery life.
As technology improves, we need smaller and better ways to manage power. SMPS units are key in powering electronics in various fields in the future.
SMPS Working Principle
SMPS, or Switched Mode Power Supplies, works on the principle of switching regulation. The main idea is to control power transfer by switching it on and off as needed. SMPS units outperform traditional linear power supplies that waste excess voltage as heat.
Detailed Explanation of SMPS Working Principle
The working principle of an SMPS can be understood in four primary stages:
Input Rectifier Stage:
In this stage, the AC input is converted to DC using a rectifier and filter capacitor. This produces an unregulated DC voltage.
Inverter Stage:
The inverter circuit uses a high-frequency transistor to switch the DC voltage on and off. This creates a pulsating DC voltage.
Transformer and Output Rectifier Stage:
A tiny device that works fast can adjust the direct current (DC) voltage, and it does this while taking up less room than the older, big power supply devices. The secondary winding of the transformer and the output rectifier then convert the pulsating voltage back into DC.
Output Regulator Stage:
The output voltage is regulated to provide a consistent supply, regardless of input voltage or load changes. This is done by adjusting the switching transistor’s duty cycle using feedback circuitry.
Different Stages of SMPS Operation: Energy Storage Stage, Energy Release Stage
A key part of the SMPS operation is how energy is stored and released.
Energy Storage Stage:
During the ON period of the switch, energy is stored in the inductor or transformer. The amount of energy stored depends on the duty cycle, i.e., the proportion of the period in which the switch is ON.
Energy Release Stage:
During the OFF period of the switch, the stored energy is transferred to the load. This energy release keeps the power supply to the load consistent, even when the switch is OFF.
By modulating the switch’s duty cycle, an SMPS can regulate its output voltage, providing a stable power supply to the load. Due to their efficiency and compactness, SMPS units are preferred for various applications.
How to Connect Two SMPS in Parallel
Before connecting two Switch Mode Power Supplies (SMPS) in parallel, ensure that:
- They have the same output voltage.
- You use diodes to prevent one power supply from drawing current from the other.
- Small resistors are used for better load sharing.
- Both units are connected to the same AC input source.
- Finally, connect the outputs of the power supplies (positive to positive and negative to negative). Please take necessary precautions, and if unsure, seek professional advice.
- Note that not all power supplies are designed to work in parallel and doing so could cause damage. Always consult the manufacturer’s instructions.
Connection Techniques: How to Connect Two SMPS in Parallel
Linking many small power supply units together can provide more power and a backup plan for important uses. Here’s a general step-by-step guide to connecting two SMPS in parallel. Only those who have a strong technical background and understand how to be safe with electricity should carry out this procedure.
Step-by-Step Guide on How to Connect Two SMPS in Parallel
Verify Compatibility: Ensure that the two SMPS units are identical models with the same output voltage rating. This is crucial as various models can respond to load changes, leading to uneven load distribution.
Preparation: Disconnect both power supplies from the mains. Never work on a power supply that’s plugged in.
Connect Outputs: Connect the positive output terminal of the first SMPS to the positive output terminal of the second one. Repeat the same process with the negative terminals. Ensure the connection is firm and secure.
Install Diodes (Optional): To be safer, you can put special parts called diodes on each small power supply’s output lines. This stops back feeding, which can happen if one power supply stops working or works at a lower voltage. Ensure that the diodes are rated for the current and voltage of your power supplies.
Connect Inputs: Connect each SMPS to the main power. It’s recommended to use separate fuses for each power supply for safety.
Testing: Before connecting the load, verify with a multimeter that the output voltage is as expected. Then connect the load and track the performance of the SMPS units to ensure they share the load.
Precautions and Safety Measures When Connecting Two SMPS in Parallel:
- In the future, we can expect more advanced SMPS solutions that consume less energy.
- Always disconnect power supplies from the mains before working on them.
- Make sure the power supplies are identical, or they may not share the load.
- Install protective diodes to prevent back feeding.
- Use separate fuses for each power supply for added safety.
- Test the setup before connecting the actual load.
- Watch the setup for any signs of uneven load sharing or other issues.
- Please note that some modern SMPS units come with built-in functionality for parallel operation. Always refer to the manufacturer’s manual or guidelines before attempting any modifications.
Differences between linear power supply and SMPS
A linear power supply is a type that regulates the output voltage by releasing excess power as heat. Linear power supplies operate by taking in an AC input, which is then converted to DC via a rectifier. The output voltage is regulated by stepping down the voltage using a transformer and using a transistor as a variable resistor. The transistor dissipates any excess voltage above the desired output as heat.
| Parameter | Linear Power Supply | Switched Mode Power Supply (SMPS) |
| Definition and Operation | A linear power supply regulates the output voltage by dissipating excess power in the form of heat, using a transformer to step down the voltage and a transistor to act as a variable resistor. | An SMPS regulates the voltage by switching a transistor between saturation and cut-off and uses storage components like inductors and capacitors to store energy. |
| Efficiency | Lower efficiency due to dissipation of excess power as heat. | Higher efficiency as energy is not wasted as heat, leading to less power consumption. |
| Size | Typically larger and heavier due to the use of 50/60Hz transformers. | Smaller and lighter due to the use of high-frequency transformers. |
| Heat Generation | Tends to generate more heat due to the dissipation of excess power. | Generates less heat due to more efficient operation. |
| Cost | Generally less expensive to produce but can lead to higher energy costs over time due to lower efficiency. | May be more expensive initially, but tend to be more cost-effective over time due to their higher energy efficiency. |
Advances and Future Trends in SMPS Technology
Improvements in SMPS help meet the growing need for power solutions that save energy, take up less space, and are affordable. Here are some of the key trends and future directions in SMPS technology:
Digital Power Management: Using digital control in small power supplies is becoming popular. It provides perks like being more efficient, performing better, and being more reliable. Plus, it allows for precise control of settings and offers new features.
GaN and SiC Devices: GaN and SiC semiconductors are popular in SMPS, making power devices smaller, faster, and more efficient, and reducing size.
High-Frequency Operation: Advances in technology are pushing the operational frequencies of SMPS higher. If we use high frequencies in power supplies, we can use tinier parts and transformers. This makes it smaller and cheaper.
Green Power Supplies: As caring for the environment and saving energy become more important, focusing on “green” small power supplies is growing.
These power supplies try to use less electricity, especially when not being used, and they follow global rules for energy saving.
Integration and Miniaturization: The trend of putting many features into one chip and making power supplies smaller will lead to solutions that take up less space and cost less. This will make it easier to create smaller electronic devices.
Wireless Power Transfer: Wireless power-sharing, although still new, could change the way we supply power in a big way. It could drop the need for power cords and create a wireless world.
Ongoing upgrades in small power supply tech will make electronics in the future work better, be tinier, and more energy-saving. If engineers and designers keep up with these changes, they can stay leading and make cool, creative electronic stuff.
Conclusion:
SMPS is crucial in electronics because it’s efficient, compact, and flexible. SMPS is more energy efficient and compact compared to traditional linear power supplies.
But, small power supplies do have problems. They can be hard to design and might cause noise and problems with other devices. As we progress and enhance this technology, we will overcome challenges and push the boundaries even further.
In the future, we can expect smaller, more efficient power supplies that save energy and have a positive impact on the environment. SMPS (Switched-Mode Power Supplies) will play a vital role in shaping the future of power supply technology. We expect the development of improved SMPS solutions that consume less energy and are more friendly.