Switching power supply operating principles

Switching power supply operating principles

Switching power supply operating criteria of capacitor charge skill inclusive physical quantities.Capacitance physics suggests that it is a dynamic charge storage medium, can charge will last forever, this is one of the characteristics of it, its wide use, it is lack in the category of electronics, electrical, electronic components.Important for the power supply filtering, signal filtering, signal coupling, resonance, filtering, offset, charge and discharge, energy storage, such as separated dc circuits.Also known as the “capacity”, refers to the charge storage capacity, under a given potential difference for C, is the domestic farads (F).Individual, charge will force and move in the electric field, as a medium between conductors, the obstacles to the moving electric charge and makes the accumulated charge on the conductor, form the accumulation of charge storage, storage power refers to the inclusion of the electric field of talents.Any electrostatic field is composed of many capacitance, the electrostatic field is the capacitor, capacitance is made on the description of electrostatic field.Individual thought: isolated conductor and the infinite form capacitance, grounding conductor is equivalent to received infinity, and with the earth as a whole.The need to use all kinds of capacitor, they break up plays a different role in the circuit.Like resistor, usually referred to as “as a capacitor, with the letter” C “.That means, capacitor is “container” storage charge.Just single capacitor sort, but they are the basic structure and principle of the same.Two electrodes apart close to a break up on the power of positive and negative, even if the power supply disconnected in a moment, will still have residual voltage between two pins, the charge storage capacitor.Set up the voltage between capacitor plates, accumulate power, the process is called capacitor charging.Charged electric capacitor have positive voltage at both ends.Capacitor storage charge to justify circuit course, known as the capacitor discharge.
Kind of energy storage device, let’s get this device called filter capacitance.Switch power supply operation criterion filter capacitor electric polarity, let’s call it the electrolytic capacitor.One end of the electrolytic capacitor anode, the other end of the cathode, are extremely cohesion in the input rectifier circuit is end, the negative terminals of the cathode connection in the circuit.In all need to exchange of electricity is converted to direct current circuit, set the filter capacitor will make the task of electronic circuit performance is more stable, but also decreased by alternating pulse ripples of electronic circuits that trouble.Filter capacitance in a circuit the symbols in the individual with a “C” signal, the greater the capacitance, to fall in the exchange of pulsation coefficient of corrugated and smooth dc input a storage device.In use will exchange into dc power electronic circuits, filter capacitance is not only the power supply dc input, dropped by alternating pulse ripple effect on the electronic circuit, it also can transfer line electronic circuit task in current shake and through the trouble of switching power supply series, makes the task of electronic circuit performance more stable.In 50 hz grid rectifier circuit, in order to obtain good filtering result, choice of filter capacitance of electric capacity are compared, the most rare for hundreds or thousands of micro method for the electrolytic capacitor, high request also has use of tantalum or niobium capacitor;But in the higher frequencies, even with a few thousand Hertz to the request of the frequency characteristic request is much more important than capacity.
Frequency of the filter, its task is several thousand Hz for tens of thousands of Hz.When we will be low frequency filter capacitor is used in high frequency circuit, the frequency characteristic because of the low frequency filter capacitor is bad, it is in the high frequency when the charge and discharge resistance is bigger, the equivalent inductance is higher.Thus in use will happen due to frequent polarization of electrolyte larger heat.And high temperature will lead to electrolyte capacitor external gasification, capacitance pressure is reduced, finally cause the capacitance of the bulge and burst.Filter capacitor plays a very important role in switching power supply, how to accurately decide filtering electrolytic capacitor in hz or so they start to rational, not satisfied with the use of switch power supply request.And dedicated high frequency switch power supply aluminum electrolytic capacitor has four terminals, the anode aluminum at both ends of the lead to break up as a capacitor anode, cathode aluminium plates at both ends of the also lead to break up as the cathode.Current flow from a four terminal capacitance is end, through the external capacitance, then from another is end to load;Returning from the load current is also flows from the capacitance of a negative end, again from another negative side to negative power supply.To reduce the voltage pulsation and weight control switch peak noise supply and extremely strong wrist.Operating standards high frequency switch power supply aluminum electrolytic capacitor and multi-fiber situation, SE – 350-12 is aluminum foil short segments of share out bonus, SE – 350-12 in parallel connection with more lead to minimize capacitive reactance of the impedance components.And take low resistivity data as leading-out terminal, improved capacitor suffered large current ability.

How to make the switch power supply design more simple and some problems in the use of switching power supply

How to make the switch power supply design more simple and some problems in the use of switching power supply

In the design of switch power supply of the first step is to define the power requirements, including the output voltage, voltage range, load current.Possible solutions will be automatically evaluation, and recommend one or two scheme is presented to the user.The first place that this is also the designer may have a problem: if not correct demand expression (for example, if the actual input voltage range above or below the input value), is not a suitable solution will be displayed.The user can try to set of requirements, but must have a clear idea on the system requirements.
Elected the stabilizer solution, can determine the components of the circuit.The tool will display the component number.User can change to a preset substitutes, or enter a custom components.Values for the components and all the key
Parasitic parameter value guidance.If used with recommended value differences of custom components, performance will drop a lot, I’m afraid.
1 performance evaluation
Once the circuit components is selected, the time to evaluate performance.Generally speaking, the performance evaluation depends on the frequency response values (crossover frequency and phase margin), peak current and voltage, as well as the thermal performance value (efficiency, mild component temperature).Although these calculations based on model, the simulation results and the data table or match well.
2 electric simulation and thermal simulation
Electrical simulation support some solutions.Simulators will show the logic diagram, users can further changes of components, and the voltage regulation circuit to run the test.The existing test including bode diagram, the steady state, circuit, the transient load transient and starting.(note that bode diagram can only be used for those who adopt the fixed frequency voltage regulator IC circuit.)More useful for the online test, the user should carefully check all test conditions.The input voltage and load current of each test are likely to change, and the default value may be related to the user’s system does not match.Users must first estimate the due as a result, if the simulation results with different, to find out why.
Thermal simulation can be used in many schemes.Online tool will use a reference design layout, evaluation of implementation of voltage stabilizing circuit on the PCB.Components and circuit board with full-color images and table display the results of temperature.Due to the thermal simulation run faster can give results (within minutes), precision nature than a hours of CFD (computational fluid dynamics) simulation results.The temperature estimates, however, generally within the actual value of 20 ° C.For the circuit boards or components of the hot spots, to prevent overheating situation is enough to use.
3 test prototype
Switch voltage regulator design and put into production the last step is to create a prototype, used for testing the workbench.Some solution containing custom design support, other solutions have a reference design board.Online tool has powerful functions, you may skip this step from this idea – don’t do that!Most of the design works well, but others need to elaborate layout to get the best performance.The actual components may not be an exact match simulation results, especially after considering their parasitic effects, the actual performance (including PCB layout effect) will be slightly different with the simulation results.

Because often design of radio frequency or low frequency analog circuit, so rarely used in the design of switch power supply, but there are several cases, must choose switching power supply, can satisfy the system’s performance!
1. Input low voltage power supply voltage is less than what the system, in this case, the system need to boost chips to improve the input voltage, for this kind of circuit, if the power supply circuit is sensitive analog signal or the rf signal, the LC network filter, then recommended “to step down or use level, so as to achieve the output characteristics of the low ripple.
2. Voltage need to negative pressure in the system, in this case, the system needs to convert positive pressure for negative pressure switch power supply.If the power supply circuit is sensitive analog signal or a radio frequency signal, the network of LC filter, then recommended by level or the negative pressure “to step down, so as to achieve the output characteristics of the low ripple.
3. The system than the input voltage of the voltage needed to much larger, and the system require a large current, if use at this time “or three-terminal voltage regulator chip, chip power consumption will be very big, not only reduce the efficiency of the system, and brings to the system of heat dissipation problem.Can be the first to use at this time of switch power supply voltage is reduced to a more appropriate voltage, use “again.
In the process of using and some problems need to pay attention to:
A.Recently used positive to the negative pressure chip, found that the output load voltage is not enough, when with load disconnect, found that the voltage recovery, began to suspect that level after circuit out of the question, but when regulated power supply is used, negative voltage is not limited flow, and using a multimeter to test the current file, found that the current is only 50 ma, later found that when I put the chip output in the positive line series inductance are removed, the output is normal.So in the switching power supply, join in the line of the input voltage power supply large inductance, although to a certain extent, has the effect of separated out dc component, but also affect the normal work of the switch power supply.
2.Although has the very high efficiency of switch power supply, but after all is not 100%, and switching power supply chip’s thermal resistance is relatively small, cooling ability is relatively poor, so be sure to calculate voltage and current required by the system, and system power consumption is calculated, and then according to the efficiency curve to calculate the consumption on the switching power supply chip power consumption.Chip through the calculation of thermal resistance temperature is more than able to withstand the temperature of the chip.Then set aside under the condition of certain allowance, select chips.

Switch power supply, the questions needed to attention in use

Switch power supply, the questions needed to attention in use

1, recently, the use of positive to negative pressure chip, found that the output load voltage is not enough, when with load disconnect, found that the voltage recovery, began to suspect that level after circuit out of the question, but when regulated power supply is used, negative voltage is not limited flow, and using a multimeter to test the current file, found that the current is only 50 ma, later found that when I put the chip output in the positive line series inductance are removed, the output is normal.So in the switching power supply, join in the line of the input voltage power supply large inductance, although to a certain extent, has the effect of separated out dc component, but also affect the normal work of the switch power supply.
2, although has the very high efficiency of switch power supply, but after all is not 100%, and switching power supply chip’s thermal resistance is relatively small, cooling ability is relatively poor, so be sure to calculate voltage and current required by the system, and system power consumption is calculated, and then according to the efficiency curve to calculate the consumption on the switching power supply chip power consumption.Chip through the calculation of thermal resistance temperature is more than able to withstand the temperature of the chip.Then set aside under the condition of certain allowance, select chips.

Switching power supply is classified according to the different ways

Switching power supply is classified according to the different ways

People at the edge of the switch power technology is developing related power electronics device, a single set of 320 w switching power supply development switch frequency conversion technology, which both promote each other to promote switch power every year the growth rate of more than two digits to light, small, thin, low noise, high reliable and anti-jamming in the direction of development.Switching power supply can be divided into AC/DC and DC/DC two kinds big.
Miniature low power switching power supply
Switching power supply is heading for popularization, miniaturization.Will gradually replace the switch power supply transformer in the life of all applications, the application of low power miniature switch power supply to embodied in the first, digital display table, smart meters, cell phone chargers, etc.Current state in vigorously promoting the smart grid construction, increase to the requirement of watt-hour meter, switching power supply will gradually replace the transformer on the watt-hour meter application.
Inversion type series switching power supply
Inversion type series switching power supply with general series switching power supply, is the difference between the reverse type series switching power supply output voltage is negative, as it happens and general series switching power supply output voltage polarity is opposite;And because the energy storage the inductance L only if there is a switch K off output current to the load, therefore, under the same conditions, inversion type series switching power supply output current than small series switching power supply output current.
According to the function can be divided into:
Losing a single set of switch power supply, double set of output switching power supply, three sets of output switching power supply, four groups of output switching power supply, waterproof switch power supply, waterproof switch power supply, guide rail type switching power supply, guide rail type switching power supply
According to the output voltage can be divided into:
5 v switching power supply, switching power supply 12 v, 15 v, 24 v switch power supply switch power supply, 48 v, 36 v switching power supply, switching power supply, etc…

Switching power supply/linear power supply/resistance capacity plan how to choice?

Switching power supply/linear power supply/resistance capacity plan how to choice?

As is known to all, there are two decision led drive power supply quality is the most important:
A: want to look for the capacitance of the brand;With ruby (Rubycom Japan) particularly prominent, constant English (HY domestic) says (SAMXON) are common, and of course prices than other is not a few cents more expensive brands capacitance;

2: IC control chip;Because IC control chip has a short circuit, over voltage, overload, over temperature protection function.

Now use more on market has the following three types of driving mode, do a simple example:

A, switching power supply

Finished product high-end switch power supply are: Ming weft (Taiwan), alum (shenzhen), low-end less known and inferior brand is too much;But overall switch power supply, the price is more expensive.This part of the high-end brand positioning is “maoye department type” consumption.

Second, linear power supply

Linear power supply many, is also a trend of the future market, plan has linear IC driver, including the sectional, constant current diodes, etc.

1. Linear IC (import and domestic).

Imported brand, mainly the United States mikpower linear power supply, single IC current doing great, linear technology is at a leading level.Compared with domestic linear IC or constant current diodes, excellent quality, good stability, compared with switching power supply, the price is reasonable, positioning for “wal-mart” cost-effective;

May be homebred brand propaganda and do a lot of MW and some other less known and inferior brand that MW brand big, do anything, but the linear drive professional aspect to be fastidious.Just log in the market, and product technology is not mature, at present most of the listed company to import brand.

2. The constant current diode

Mainly altek brands such as, also can have the effect of a certain constant current, disadvantages exist power grid volatility to high pressure tube, pressure impact resistance ability is poor, life is short, calorific value is big, constant current precision is not high.

3. The sectional

Advantage is of high efficiency, but in linear scheme, cost is the highest, at the same time there is a drawback, grid pressure changes, can make the current of each different, can cause the brightness of the different segments, lamp bead death probability is different also, simply be different brightness.Sectional still has more than a bit is the pin, SOP packaging line spacing and small, can bring trouble to design, use rise more limited.

Third, resistance capacity

The author here said, in addition to cheap, do not have what advantages.In a small motor using it is easy to die under the environment of light, the power grid volatility, a great influence on the LED, not constant current, which is now LED market when there is no standard fish in troubled waters once, this way to do the low-end market, more and more narrow, only road don’t do spare are introduced.

The classification of the dc switching power supply

The classification of the dc switching power supply

High frequency switching dc power supply with high quality import IGBT as the main power device, with amd crystal (also known as nanocrystalline soft magnetic alloy material is given priority to transformer core, the main control system adopts a multi-loop control technology, structure of acidic salt mist measures were taken.Power supply products reasonable structure, high reliability.The power supply for its small volume, light weight, high efficiency, high reliability and superior performance of the update products become the thyristor power supply.Applicable to the experiment, oxidation, electrochemical, galvanized, nickel plating, tin plating, chrome plating, photoelectric, smelting, into, corrosion and other places of all kinds of precision surface treatment.In the anodic oxidation, vacuum coating, electrolysis, electrophoresis, water treatment, electronic products, such as aging, electric heating, electrochemical aspects have been praised by users.Especially in the field of PCB, electroplating, electrolysis, become the first power supply products of many customers.
Application characteristics
1, to reduce the porosity, the formation of crystal nucleus growth faster than speed, prompt refine crystal nucleus.
2, improve the bonding force, make the passive film breakdown, is advantageous to the strong bond between substrate and coating.
3, improve coverage and dispersion ability, high negative potential cathode make the position of ordinary plating passivation can also deposit, salient parts due to the deposition of slow form complex components ion “burned” resulted from the excessive consumption of “dendritic” deposit defects, for a given feature coating (such as color, no pore) thickness can be reduced to the original 1/3 ~ 1/2, save raw materials.
4, reduce the internal stress of coating, lattice defects, impurities, hollow, tumors, such as easy to get no crack coating, reduce additive.
5, is helpful to obtain ingredients stability of the alloy coating.
6, improve the dissolution of anode anode activator is not required.
7, improvement of mechanical and physical properties of the coating, such as higher density lower surface resistance and volume resistance, improve toughness, wear resistance, corrosion resistance and can control the hardness of coating.

The classification of the switching power supply

The classification of the switching power supply

People in switch power technology development related power electronics device is edge, edge development switch frequency conversion technology, which both promote each other to promote switch power supply each year the growth rate of more than two digits to light, small, thin, low noise, high reliable and anti-jamming in the direction of development.
Switching power supply can be divided into two major categories of AC/DC and DC/DC, DC/DC converter has been modularity, and design technology and production technology at home and abroad have been mature and standardized, and has been recognized by users, AC/DC modular, however, because of its own feature makes in the process of modularization, the technique and technology of the complicated manufacturing problems

Switching power supply is the use of modern power electronic technology

Switching power supply is the use of modern power electronic technology

Switching power supply is the use of modern power electronic technology, control switch tube opened and shut off time ratio, to maintain stable output voltage of a power supply, switching power supply by general pulse width modulation (PWM) control IC and MOSFET.

Power transformer industry is an important part in the electronic information industry in China, is one of the electronics industry has stronger international competitiveness, and even the global financial crisis in 2009, electronic power industry output value reached 106.1 billion yuan, still has more than 5% growth rate.As countries a series of macroeconomic stimulus policy implementation and the global economy tends to be stable, in 2010 China’s electronic information industry quickly restored the momentum of development, electronic power industry is taking advantage, scale of production reached 117.2 billion yuan, the fast growth of more than 10%.

Switching power supply is the main categories of products, electronic power supply because of its light weight, miniaturization, wide range of input voltage and high power density/conversion efficiency, standby power consumption is small, and many other advantages, its development is rapid, has replaced the linear power supply, power frequency applied to all kinds of terminal dominated by electronic computer equipment, communications equipment almost all electronic equipment, is the rapid development of electronic information industry indispensable an electronic industry.

Switching power supply is the most accessible function is introduced

Switching power supply is the most accessible function is introduced

1. Switching power supply, is the grid after the rectifier dc voltage, using switch conduction and shut off, the section into a rectangular wave voltage (of course, the actual rectangular wave waveform is not perfect, but there will be a overshoot), doing so is the significance of the high-energy cut into thousands of low energy, passed to the output, output terminal through the output voltage high or low, to feedback the input (adjusting cutting frequency, and the width of the cut size, duty cycle), to achieve the purpose of stable output voltage
2. Why not use the traditional way?For example, the most typical 7805, it is transmitted through converting excess energy into heat, to achieve the goal of antihypertension.And the switch power supply is different, its low calorific value, that is, its efficiency is very high, so its use is so common!

About the working principle of switch power supply is introduced

About the working principle of switch power supply is introduced

Switching power supply in our usual in the oral is refers to the switch and the power of two things.
Professional books of switch power supply is the use of modern electric technology, control switch transistor opened and shut off time ratio, to maintain stable output voltage of a power supply, switching power supply usually controlled by pulse width modulation (PWM) IC and MOSFET.

Types can be divided into isolation and the isolation switch power supply, must have switch transformer isolation, rather than isolated not necessarily must have.

The working principle of switch power supply is:
1. The ac power input through rectifier filter (50 hz), as dc power;
2. Through the high frequency PWM (pulse width modulation) signal control switch tube, the dc power supply to the switch on the transformer primary;
3. The switch transformer secondary induction high-frequency voltage, the rectifier filter supply load;
4. The output part through certain feedback to control circuit, PWM duty ratio control, in order to achieve the purpose of stable output.

Usually go through when the ac power input flow of urban circle and the like for filter rectifier, filter and interfere with each other on the grid;
In the power phase at the same time, the higher the switching frequency, switching transformer of the smaller volume, but the higher requirements of the switch tube;
Switch transformer secondary windings can have multiple or a winding has multiple tap, to get to output;
Should add some protection circuit, such as light, short circuit, such as electric protection, to prevent burning switch power supply.
High frequency switch power supply is the future development direction, with broad prospects for development, high frequency switch power supply, make its miniaturization, and makes the switch power supply into a wider range of application fields, especially in the high and new technology in the field of application, promoted the high-tech products of miniaturization, light change. In addition the development and application of switching power supply in the aspect of saving energy, saving resources and protecting the environment has important significance.

Refers to the switch power supply ac power rectifier filter into dc power supply first, use through the circuit control switch tube high-speed way and globe, provide the direct current into high frequency alternating current (ac) to variable voltage transformer, and help to produce one or more sets of voltage output load electrical products. Into the cause of the high frequency alternating current (ac) is a high frequency ac in transformer transformer circuit efficiency is higher than 50 hz a lot, so the switch transformer can do is very small, and the work isn’t very hot. The cost is very low. If you don’t turn 50 hz into high frequency switch power supply are meaningless

The working principle of switch power supply is:

1. The ac power input by the rectifier filter into dc power;
2. Through the high frequency PWM (pulse width modulation) signal control switch tube, the dc to the switch on the transformer primary;
3. The switch transformer secondary induction high-frequency voltage, the rectifier filter supply load;
4. The output part through certain feedback to control circuit, PWM duty ratio control, in order to achieve the purpose of stable output.
Switch power supply circuit:

Switching power supply design: switching power supply can be divided into isolation and the isolation type two kinds, isolation switch transformer must be, not necessarily must have rather than isolation. When the ac power input general flow through urban circle and the like, to filter out interference on the grid, but also filter out the interference of power supply to the grid;
In the power phase at the same time, the higher the switching frequency, switching transformer of the smaller volume, but the higher requirements of the switch tube;
Switch transformer secondary windings can have multiple or a winding has multiple tap, need with the convenient voltage output;
Should also be add some protection circuit, such as open circuit, short circuit protection, otherwise it may burn switching power supply.