1. Ac/DC converter

An AC converter is an electronic device whose main function is to convert alternating current (AC) to direct current (DC). Alternating current is a form of electrical energy in which the direction and magnitude of the current change periodically with time, while direct current is a form of electrical energy in which the direction of the current remains constant in the circuit.

Ac/DC converters are widely used in a variety of electronic devices and systems, including but not limited to home appliances, office equipment, communication systems, computer hardware, automotive electronics, industrial control, and aerospace. They can offer power outputs ranging from a few watts to a few kilowatts or more, depending on the design and needs, and can be integrated solutions packaged in small modules or large power supply systems.

Working principle

The process of converting alternating current to direct current begins with rectification, through semiconductor components such as diodes that allow the current to flow in only one direction, thus converting the positive and negative half cycles of alternating current into pulsating direct current in a single direction. The next filtering phase uses capacitors and inductors to remove the AC component of the pulsation, further smoothing the current. Finally, the voltage regulator ensures that the output voltage is constant and not affected by input voltage fluctuations or load changes, usually with linear or switching regulators.

Apply

AC/DC converters (AC/DC converters) are used in a wide range of applications, covering almost all modern electronic devices and systems that rely on a stable DC power supply. Here are some of the main application areas:

1. Consumer electronics: including mobile phone chargers, laptop adapters, flat screen TVS, game consoles, audio devices and home appliances, which require a stable DC power supply.

2. Information Technology and Communications: Data center servers, network routers and switches, communication base stations, and various office automation equipment such as printers, copiers, etc., require efficient and reliable AC/DC conversion to ensure continuous operation.

3. Industrial Control and automation: Industrial production equipment, automated control systems, meters and sensors, LED lighting systems, etc., these applications require highly stable DC power to maintain accurate control and long life.

4. Medical equipment: electrocardiogram machines, ultrasound equipment, patient monitoring systems and other medical electronic equipment, the purity and reliability of the power supply has a high requirement.

5. Automotive and transportation: power battery charging systems for electric vehicles, on-board electronic systems (such as navigation and entertainment systems), and electrical equipment in rail transit.

6. Energy and lighting: solar inverters, power regulation of wind power generation systems, LED street lights and building lighting systems, these fields use AC/DC conversion technology for electricity conversion and management.

7. Scientific research and experimental equipment: laboratory testing instruments, analytical equipment, scientific research equipment, etc. These precision equipment often need high-quality DC power to support its operation.

8. Aerospace: Electronic systems on aircraft, satellites, and spacecraft that have extremely stringent power requirements and must be highly efficient, lightweight, and stable in extreme environments.

Common fault causes and solutions

Common faults that may occur in AC/DC converters and their causes and solutions include:

The output voltage is unstable

Cause: It may be caused by input voltage fluctuation, filter capacitor aging, voltage regulator circuit failure or load mutation.

Solution: Check and stabilize the input voltage source; Replace the aging filter capacitor; Inspect and repair or replace faulty voltage regulator elements; Add appropriate protection circuits to cope with load changes.

Severe fever

Cause: Usually caused by overload of power devices, poor heat dissipation, unreasonable circuit design or aging of components.

Solution: Check and ensure that the load does not exceed the maximum rated power of the converter; Improve heat dissipation conditions, such as adding heat sinks or using fans; Check circuit design, optimize layout and select more suitable components; Replace aging or damaged components.

Failure to start

Cause: It may be a failure of the starting circuit, a burnt fuse, a damaged control circuit or an input power problem.

Solution: Check the starting circuit and components, such as relays or control ics; Replace a burned fuse; Check and repair control circuits; Check whether the input power is normal.

Noise interference

Cause: Insufficient filtering, improper electromagnetic compatibility (EMC) design, and poor grounding.

Solution: Enhance the filter design, add additional high-frequency filter capacitors or inductors; Improved EMC design, using shielding and grounding techniques; Ensure a good grounding connection.

Short-circuit protection trigger

Cause: External load is short-circuited or internal components are damaged.

Solution: Check the external load and eliminate short circuit; Detect and replace internal damaged components; Adjust or enhance the short-circuit protection mechanism if necessary.

When diagnosing the preceding faults, you are advised to check whether physical damage or loose components exist. Then, use a multimeter to measure the voltage and current of key nodes to locate the fault. For complex faults, professional circuit analysis tools and equipment may be required, or sent to a professional service point for repair. Before making your own repairs, be sure to disconnect the power supply and take appropriate safety measures to avoid the risk of electric shock.

2, DC converter

Dc converter is an electric energy conversion device, its function is to convert the voltage level of a direct current energy to another direct current energy output of a different voltage level, while it can involve the adjustment of current and power, but keep the output in the form of DC. This conversion is critical to meeting the specific needs of different electronic subsystems or components for power supply voltages, especially in those devices powered by batteries or other fixed voltage sources, such as mobile phones, laptops, electric vehicles, and various portable and embedded systems.

Dc-dc converters achieve voltage conversion through switching technology (switched mode power supply, SMPS) or linear voltage regulation technology, where switched mode converters are widely used because of their high efficiency. They can be divided into several basic types, including buck converters, boost converters, buck - boost converters, and isolation converters, each type according to the input and output voltage relationship and circuit structure, has its own unique application.

During the conversion process, the circuit will use energy storage components such as inductors and capacitors to smooth and adjust the voltage, by controlling the switching components (such as MOSFET) on and off, the input power wave into a high-frequency pulse, and then through the transformer (in the isolated converter) or directly (in the non-isolated converter) for energy transfer. A filter circuit is used to convert the pulse DC into a smooth DC output. By adjusting the duty cycle of the switch (that is, the ratio of the on-time to the switching period), the output voltage can be precisely controlled.

type

There are two basic types of DC converters: buck converters and boost converters. They use switching technology and energy storage components such as inductors and capacitors to change the level of the input DC voltage to suit the voltage requirements of different electronic devices. INFINITECH explains how they work and how they differ:

Buck converter

How it works:

1. On stage: When the switch (usually a MOSFET) is on, the input voltage is applied to the inductor, the inductor begins to store energy, the current gradually rises, and the capacitor supplies power to the load.

2. Shutdown phase: When the switch is off, the current on the inductor does not disappear immediately, but continues to supply power to the load through the diode continuous current, and smooths the output voltage through the capacitor, at which time the inductor releases the stored energy.

3. Repeat the above process: By controlling the on-off and off-off frequencies (duty cycle) of the switch, the average output voltage can be adjusted to be lower than the input voltage.

Features: The output voltage of the buck converter is always less than or equal to the input voltage, which is suitable for occasions where a lower voltage output is required.

Boost converter

How it works:

1. On stage: When the switch is on, the inductor is connected to the input power supply, the current rises through the inductor, and the inductor stores energy.

2. Off phase: After the switch is off, the inductor tries to keep the current continuous, so the current flows through the diode to the load and charges the capacitor so that the output voltage is higher than the input voltage.

3. Repeat the above process: by adjusting the duty cycle of the switch, you can control the increase of the output voltage.

Features: The output voltage of the boost converter is always greater than the input voltage, which is suitable for occasions where the voltage needs to be increased.

Difference between buck and boost converters

• Voltage conversion direction: The most fundamental difference is the relationship between the output voltage and the input voltage. A buck converter lowers the voltage, while a boost converter raises it.

• Energy transfer mechanism: Although both take advantage of the energy storage characteristics of inductors and capacitors, the direction and way of energy flow are different. In a buck converter, energy is directly transferred from the input source to the load, while a boost converter stores energy via inductance and "pumps up" voltage to the load when the switch is off.

• Application: The buck converter is suitable for voltage regulation in battery-powered devices, such as laptops and mobile phones, battery-powered to low voltage circuits such as cpus. Boost converters are often used where high voltage outputs are required, such as LED drivers, certain battery charging circuits, or systems that require a boost in battery voltage.

Buck to boost converter

In addition, there is a type called buck-boost Converter (or buck-boost Converter), which is able to Buck or Boost the input voltage as needed, for scenarios where the input voltage range may be higher or lower than the desired output voltage. This converter combines the characteristics of buck and boost modes, and realizes the function that the output voltage can be greater than or less than the input voltage by flexibly adjusting the switch operation.

Bidirectional converter

Two-way DC-DC converters can switch between boost and buck modes and are suitable for energy recovery systems, battery charge/discharge management and other fields. At its core is a highly flexible control strategy and circuit design that enables efficient energy conversion in different modes.

Module selection

There are many types of DC-DC conversion modules on the market, from fixed frequency to programmable, from single output to multiple output, and the selection should take into account power requirements, package size, cost budget and special requirements in specific application scenarios. It is equally important to evaluate the supplier's technical support and product reliability.

In summary, the design and application of both AC-DC converters and DC-DC converters are based on a deep understanding of efficiency, safety, cost, and the requirements of specific application scenarios. With technological progress and market development, future converters will be more intelligent and efficient to better serve the growing demand for electronic equipment.