Switching power supply development and application
2018-11-09 Browse times: 3323
The switching power supply is a power supply that uses modern power electronics technology to control the opening
and closing of the switch. This ratio of output voltage is stable. The power supply is generally controlled by a pulse width
modulation integrated circuit and a field effect transistor. Switching power supplies, linear power supplies, and power
output with increased cost, but these two different development speeds. At a point of view of the output power of a linear
power cost, but higher than the switching power supply, it is called the cost reversal point. With the development and
innovation of power electronics technology and the continuous innovation of switching power supply technology, this
lower cost output provides a broad space for development of mobile and switching power supplies.
The development direction of high-frequency switching power supply is high-frequency switching power supply,
miniaturization, switching power supply to a wider range of applications, especially in high-tech applications, to promote
the miniaturization and light of high-tech products. The development and application of another switching power supply
is of great significance in saving energy, conserving resources and protecting the environment.
For applications in switching power supplies, power electronics IGBT modules are mainly used for diodes and field
effect transistors.
The input and soft-start circuits of the power supply of the thyristor rectifier circuit are gradually driven in a small
application, GTR, switching frequency, and gradually replace the IGBT and the field effect transistor.
Three conditions for switching power supplies
1. The switching state of the switching power supply unit, not the linear state
Second, high-frequency power electronic devices at high frequencies instead of low frequenciesDavid Kuta:
3, switching power supply output is DC instead of ACClassification of switching power supplies
At the edge of the development of switching power supply technology, the development of switching frequency
conversion technology for power electronic devices has jointly promoted the trend of driving switching power supplies
for more than two years, increasing data, thin, low noise, high reliability and anti-interference. . Switch AC and DC
power can be divided into two categories, DC permanent magnet DC/DC converter, which is realized, modular design
technology and production process, and mature and standardized at home and abroad, and has been recognized,
but AC and DC modular, because Its own characteristics, the more complex technologies encountered in the process
of modularity and process problems. The structure and features of these two switching power supply systems.
2.1 DC / DC transformation
DC/DC conversion is a fixed DC voltage that is converted into a variable DC voltage, also known as DC. There
are two different ways of working for helicopters. One is the pulse width modulation method, which changes the tons
of tons and general-purpose inverters, does not change, and changes Ts (prone to interference). The specific circuit
is divided into the following categories:
(1) Barker circuit, step-down kitchen knife, average output voltage
Input voltage user interface, half less polarity.
(2) boost circuit - booster chopper, average output voltage
The input voltage is half Ui, polarity.
(three) boost buck - buck or circuit, it boosts the kitchen knife
The average value of the semi-linear output voltage is greater or less than the input voltage Ui, the polarity is
opposite, and the inductance is transmitted.
(4) Cuk circuit, buck or boost average output power guard
The half pressure is greater or less than the input voltage Ui, the polarity is reversed, and the capacitance is
transmitted And Sepic, Zeta Circuit.
The circuit of the above isolation circuit, the separation, the flyback converter circuit induction circuit, the half
bridge circuit, the bridge circuit, the mosfet circuit.
22 AC and DC transformation
AC/DC conversion to AC and DC conversion The current can be a bidirectional flow source power flow load
called "rectifier, "current power load return, inverter" called "active AC/DC converter. 50/60Hz input AC, because it
must be rectified and filtered, so a larger filter capacitor is necessary, at the same time, from safety standards
(such as UL, CCEE, etc.), EMC directives (such as IEC, catalysis, CSA), AC input Side plus EMC filter and use of
elements and safety standards,AC and DC power limitations, and small size miniaturization, because high current
switching, making EMC problems more difficult to solve EMC, but also for internal high-density installation circuit
design And on this basis, higher requirements are put forward, because the same reason is due to the work of
high-voltage, high-current switching power loss, which makes the AC/DC converter limited, so it is necessary to use
modular advanced power system optimization. Design methods can make job satisfaction more efficient.
This AC-DC conversion can be divided into half-wave circuits and the entire circuit according to the circuit
connection mode. According to the main power phase can be divided into several, single-phase, three-phase,
multi-phase. According to the circuit can be divided into working quadrants, two, three, four quadrants in the
quadrant.
This power supply
1 Turn on the power input anti-interference performance, due to its own characteristics of the circuit structure,
multi-level series) (such as the input voltage surge output voltage, the main technical indicators of the stable linear
power compared to the advantages of its output voltage is stable ( 1) 0.5 ~. When switching power supply modules
are used as a power electronic device, the following points should be emphasized:
Output current selection. 3.1
Because switching power supplies, high efficiency, can reach 80n output current, such choice should be
accurate measurement and calculation, electrical equipment to maximize current sinking switching power supply
and cost-effective output, usually formula.
Is KIf =
Type: Yes, rated power switching power supply,
If the maximum absorption - electrical equipment,
Kathy-edge coefficient, spend 1.5 ~ 180 degrees,
32 grounding,
Switching power supply, linear power supply will generate more common mode interference than
interference sensitive electrical equipment, measures should be taken and shield grounding, according to
ICE1000, EN61000, FCC, etc., electromagnetic compatibility of switching power supply limits electromagnetic
compatibility, therefore, generally Electromagnetic compatibility filter for switching power supplies. If the weather
is only beneficial to the technology, series of switching power supplies or pick up the finished end user cabinet
on the ground, the required electromagnetic compatibility can be met.
33 protection circuit
In the design, it is necessary to use the switching power supply flow, overheating, short circuit protection
function design, selection and other multiple protection function modules, power circuit technical parameters
should be protected by the working characteristics of the electrical equipment to avoid damage to the
competition power equipment or switching power supply .
The development trend of switching power supply technology
The development direction of switching power supply is high frequency, high reliability, low energy
consumption, low noise, anti-interference and modularization. Due to its small size, light weight, switching power
supply, and key technologies, foreign manufacturers of major switching power supplies are committed to
developing new high-intelligent synchronous rectifier devices, especially for high-school, loss-of-power devices
(manganese-zinc ferrite). Materials), education, to improve the technology innovation process to increase the high
frequency and magnetic flux density (Bs) with the key technology of magnetic field and capacitor miniaturization.
The application of SMT technology has made great progress in the process of switching power supply, PCB layout
of two components to ensure that the light switch power supply is small and thin. The high-frequency switching
power supply is a traditional inevitable ZCS PWM switching technology innovation, zero voltage, soft switching
technology has become the mainstream switching power supply technology, and greatly improve the efficiency of
the switching power supply. High reliability indicators, switching power supply production reduce the temperature
of running through the current, reduce measures and other measures to reduce pressure equipment, product
reliability is greatly increased.
The development of switching power supplies is the trend, the distributed components of the module power
supply system can be used for N + 1 redundant power systems to achieve parallel capabilities. According to the
shortcoming of running noise, the high-frequency noise isolation will also increase the local resonance conversion,
and theoretically, the circuit technology can achieve higher frequency variation to reduce noise, but the actual
application of resonance technology still exists, but There is still a need for technical issues in this area, and a lot
of work to make practical techniques.
The innovation of power electronics technology has made the switching power supply industry have broad
development prospects. In order to accelerate the development of the switching power supply industry, in China,
we must take the speed of technological innovation and the development path of trade unions with Chinese
characteristics, which is the rapid development of China's national economy.
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