For people of culture who have never specialized in electricity, even if you read the introductory book to study the circuit of switching power supply, it is not clear. The actual power supply circuit also uses new electronic components, so it is different from the explanation in the technical book.

I would like to explain the circuit of the switching power supply with the familiar TDK-Lambda “ZWS100B-5”. It is not perfect because there is no circuit diagram of the power supply, but you can understand the rough operation of the switching power supply in block units from the actual product. If you know this much, you can talk to a technician.

Switching Power Supply Circuit

I took a picture of ZWS100B-5.

A brief explanation of the circuit is as follows: “Input from the input connector at the left end of the power supply, ① via the filter circuit and ② inrush current prevention circuit, ③ rectified and smoothed current, ④ switch and send to the transformer. The output is rectified and smoothed. ”This is the general flow of this circuit.

Let’s take a closer look.

Filter Circuit

After inputting, first enter the filter circuit consisting of a film capacitor (film capacitor) and a coil. The film capacitor is a part of the black case in the photo, and it is a capacitor with a plastic film dielectric sandwiched between the internal electrodes.

The role of the filter circuit is to suppress noise coming in from the outside and noise (noise terminal voltage) going out from the power supply side to the input side. In particular, the noise terminal voltage is important and may have adverse effects such as malfunction on other devices and devices, and there are international standards. The coil is called a common mode choke coil.

Next to the film capacitor is a black component surge absorber (varistor). A surge absorber is a component that protects electronic devices from surge voltages such as lightning. Since the resistance value changes depending on the voltage, it is possible to protect elements such as ICs from static electricity and electronic devices from lightning surges.

The mechanism is that when a high voltage is applied to the surge absorber, the resistance value drops and current flows through the surge absorber. When a current flows, the resistance value of the circuit drops and the voltage drops. As a result, the voltage applied to electronic components such as ICs can be reduced.

Inrush Current Prevention Circuit

There was a 5A fuse after the filter circuit. This glass tube fuse is inexpensive and is often used as a component of electronic circuits. You can see that the fuse is blown from the outside, but this type has a protective seal wrapped around it to prevent debris from scattering around when the glass tube breaks.

When the fuse blows, the fuse is replaced, but in the case of a switching power supply, the fuse blow is rarely the primary cause, and most of the secondary blows are caused by the failure of peripheral parts. Peripheral parts are also broken, so you only need to replace the fuse

Inrush current flows when an electrolytic capacitor is on the circuit. If a surge current flows, the fuse will blow or the electrolytic capacitor will be overloaded, shortening its life. The inrush current can be suppressed with a thermistor. The gray part pointed with the pen in the photo above is the thermistor. It is also called an NTC thermistor.

As shown in the figure above, the thermistor has a high resistance value when the temperature is low, and when the temperature rises, the resistance value instantly drops to 0Ω. (The resistance value of the surge absorber changes with voltage, but the resistance value of the thermistor changes with temperature.)

The thermistor acts as a resistor when the temperature at power-on is low, and when current flows out, the resistance value drops and it becomes almost the same state as when there is no resistor. When a fixed resistor is used, heat loss always occurs, but the thermistor has almost no heat loss and efficiency is improved.

New products of 24V output switching power supplies are released every year by many manufacturers, and it has become possible to select highly reliable power supplies with distinctive specifications.

However, it is a fact that many people are wondering which switching power supply to choose because there are too many models. Therefore, in this article, we will explain the points to pay attention to when purchasing a switching power supply with 24V output and the characteristics of the power supply by recommended manufacturer. Choose the manufacturer’s power supply that suits your needs.

24V output switching power supply is roughly divided into two types

Before checking how to choose a switching power supply with 24V output and recommended models for each wattage, let’s first understand the basic types of power supplies.

• AC / DC converter
• DC / DC converter

There are two main types depending on the input voltage. The input voltage of the AC / DC power supply is AC (alternating current), and the input voltage of the DC / DC converter is DC (direct current).

The AC / DC power supply is the power supply that converts the commercial AC power supply (AC) sent to each factory or home to a stable DC voltage (DC). On the other hand, a DC / DC converter is a power supply that converts a direct current power supply (DC) such as a battery into another stable direct current voltage (DC).

From here, we will explain each feature

What are the features of AC / DC power supply

The most sought after “AC / DC power supply” among switching power supplies is a 24V output power supply. Therefore, the number of models is abundant, and it is easy for users to find a power supply with the specifications they desire.

The input voltage is generally single-phase 100 / 200V and three-phase 200V.
The current value ranges from 0.2A (5W) to 100A (2400W) for single-phase 100 / 200V input and 40A (960W) to 75A (1800W) for three-phase 200V input.

There are various types such as single-phase 100 / 200V input type, board type, DIN rail type, onboard type, and power module. Three-phase 200V input is only partly DIN rail type and unit type.

What are the features of DC / DC converters

　A power supply whose input voltage and output voltage of the DC / DC converter are direct current voltage (DC).
The 24V output DC / DC converter in Thailand mounted on the board has a power module. The small onboard power supply and POL (Point of Load) have only 15V output.

Input voltages are generally DC48V, DC110V, and DC280V. DC48V is often used for communication systems, DC110V for power systems, and DC280V for FA robots. The capacity is about 50W to 500W.

Four points to check when selecting a switching power supply

Check the load factor (current) from the ambient temperature.

When choosing a power source, the current value is a very important point. It is wise to choose a power supply that matches the ambient temperature of the power supply in the device / equipment when choosing the optimum power supply, rather than “choose a 10A power supply because the required current is 10A”. The value varies greatly depending on the ambient temperature of the power supply.

Be sure to check the “Load factor for ambient temperature” table in the specifications.
In the table below, when the ambient temperature of the power supply is 50 ° C and it is used with standard mounting A, it can only be used at 70%. In other words, if the rated current is 10A, it will be 7A.

If you are particular about reliability, read the calculated value of electrolytic capacitor life.

Also look at features

The sound is different from usual, what does it smell like, it’s hot, maybe it’s because of my mind?
Please refer to the causes and countermeasures for each of the common symptoms.

Abnormal noise

Fan

As the grease in the fan bearing deteriorates (hardens), it loses its function as a lubricant. Therefore, as the fan rotates, a larger force (torque) is required and the fan rotation noise becomes louder.

If the fan makes a strange noise, replace the fan.
The life of the fan at an ambient temperature of 40 ° C is about 4 to 5 years. It will last faster in a dusty environment.

* The fan manufacturer’s definition of life is when the rotation speed reaches 70% of the rated rotation speed. The time when the fan stops is not the life of the fan.

Trance

Since the core of the transformer vibrates, it makes a “boom” or “keen” sound, but it is usually not noticeable. There is no problem with the power supply itself.
However, if it is too large, it will be returned to the manufacturer.

Harmonic current suppression circuit

A power supply with a harmonic current suppression circuit may make a humming noise when the input is turned on. It is temporary until the internal voltage stabilizes and is not a malfunction.

Offensive odor (white smoke rises)

If the pressure inside the electrolytic capacitor rises for some reason, the “explosion-proof valve” of the electrolytic capacitor will open to release the pressure. At that time, a “shoe” sound is heard and white smoke rises and gives off a strange odor, so people who see it for the first time mistake it for smoke.

The power supply is out of order, so replace it with a new one.
Since it is a phenomenon that does not occur normally, ask the manufacturer to analyze it.

If an overvoltage is applied to the electrolytic capacitor, the internal pressure may increase. The explosion-proof valve opens to reduce the internal pressure before the electrolytic capacitor explodes. The explosion-proof valve has a slit (notch) in the head of the electrolytic capacitor, and the shape of the slit differs depending on the manufacturer. When the explosion-proof valve is opened, the gas inside is released, so smoke is emitted and there is a strange odor, so many people mistakenly think that it has “smoke”. The opening of the explosion-proof valve is proof that the safety device worked normally.

異常発熱

The power supply heats up because it transfers heat to the housing (chassis, cover) for heat dissipation.
If the temperature inside the power supply rises too high, overheat protection will work and the output will stop.

To lower the temperature of the power supply, change the power supply to one with a larger capacity (lower the load factor), change the location and orientation of the power supply, and open a slit in the housing to allow heat to escape.

Smoke / ignition

Since the parts used in switching power supplies are flame-retardant, they are unlikely to ignite due to smoke.
By the time it has protection, it is designed to stop safely.

However, usage outside the warranty, usage environment, and some adverse conditions may overlap.

In the unlikely event that smoke or fire occurs, immediately turn off the input and return it to the manufacturer as it is without touching anything.

For those who want to choose a switching power supply but do not know which one to choose

The designer said, “I want to use a long-life power supply for the device under design.”
The person in charge of materials said, “I want to reduce costs, but I don’t know which power supply to choose.” “I want to know an alternative model of power supply that will be scrapped.”
Are dealer salespeople thinking, “I want to compare specifications and prices with competing models.” “I want to know more about switching power supplies.”

I will answer these questions.

I’m comparing the power supplies of various manufacturers, but the specifications are different for each company, and is this the right way to see the load factor and life of the power supply? If you are uneasy, please see the article.

How to choose a switching power supply that will not fail

The following three are important.

Let me explain.

Confirmation of basic specifications

This basic specification is the most important.

The basic specifications of the power supply are “input voltage”, “number of outputs”, “output voltage”, and “output current”. Once these four specifications are decided, the power supply model can be selected.

Please refer to “Basic specifications important when choosing a switching power supply” for the basic specifications of the power supply.

Once the basic specifications are decided, the power supply of each manufacturer is searched, that is, the search is performed, but if you search using the specification search function of this site “dengen-navi”, you only have to search once, so it is the easiest. After all, we have a database of 35,000 power supply models from major domestic power supply manufacturers.

For how to use it, see “Search Guide for Switching Power Supply [Explanation of how to use and tips for searching in an easy-to-understand manner]“.

Confirmation of narrowing specifications

You can search without checking the refined search, but please check the specifications and standards that you can never remove.

By checking the narrowing items, you can sort out whether the specifications / standards are really necessary.
There are 56 specific items to narrow down by mechanism, function, standard, fan, manufacturer, and production status.

Important items to check

The search result table you searched for has the most important items. However, it is OK if you keep only the main points in the following three items.

Before that, I will explain each item. If you know it, please skip it.

The load factor indicates the percentage of load that can be taken when the ambient temperature is 50 ° C. There is a big difference between a power supply that can use 100% and a power supply that can only use 60% even with the same capacity. “0%” means that it cannot be used at an ambient temperature of 50 ° C.

The life of the electric capacitor is the expected life (year) of the electrolytic capacitor when the ambient temperature is 40 ° C and the load factor is 80%. This is the life under general environmental conditions. Select a power supply that is at least longer than the life of the equipment or equipment to be installed. The description “electric capacitor-less” means that the electrolytic capacitor of the life component is not used.

The lowest price shows the cheapest price on the net and the mail order company that sells the power supply. However, since it is the price for one unit, please use it as a reference price only. If the quantity is large, it will be much cheaper than this price. The reason why the lowest price is not stated is that the online sales company does not sell the model, or even if it sells, there is no price display.

In addition, this site has a convenient sorting function for comparison. You can sort in a complex manner using sort order 1 and sort order 2.

First, check “Load factor” in sort order 1. It is arranged in descending order of load factor, that is, in descending order of usable capacity, so how much is acceptable. In the case of a 100W power supply, 100% load factor can be used as 100W, and 80% load factor cannot be used as 80W.

Check “Electric computer life” for sort order 2. If the life of the device or equipment is 5 years, a longer life value of the electric controller is required. However, the life of the electric controller here is the number of years in 24h365 days.

Next, check “Lowest price” in sort order 1 and “Electrical controller life” or “Load factor” in sort order 2, and select a power supply that is cheaper and has a device life or longer or a load factor of 80% or higher.
If you do it several times, you can see that the low price does not mean that the life of the electric controller is short.

]]> https://dengen-navi.com/wp/en/glossary/y-capacitor/ Tue, 17 Aug 2021 01:40:12 +0000 https://dengen-navi.com/wp/?p=6358 Y capacitor connected between the AC line and the FG has the function of releasing the common mode noise current to the FG. Leakage current flows through the Y capacitor according to the frequency and voltage of the AC power supply. If the capacity of the Y capacitor is large, the leakage current will be large and there is a risk of electric shock, so safety standards such as UL limit it so that it does not exceed a certain value. Common mode noise and leakage current are inversely proportional.

　The higher the “efficiency” of the switching power supply, the less heat it generates, and the lower the efficiency, the more heat it generates. The unit of efficiency is expressed in%. Previously, switching power supplies were about 75-80% efficient, but modern power supplies are 85% or more and less than 90%, and 95% high-efficiency power supplies are not uncommon. The linear power supply (dropper power supply) was 50% to 60%, so the efficiency is much better. The efficiency has improved due to the circuit method, but the efficiency of electronic components has improved.

Let’s take TDK-Lambda’s HWS100A-5 as an example. There is “efficiency” in the input field of the following specifications. The efficiency differs by 2 to 3% between 100VAC input and 200VAC input. A 200VAC input is more efficient. Also, the higher the output voltage (the smaller the output current), the better the efficiency. Efficiency varies by 5-6% between 3.3V and 48V outputs. In other words, a power supply with AC100V input and 3.3V output is 8% less efficient than a power supply with AC200V input and 48V output.

Heat generation amount (electric energy amount) of switching power supply

　Now, let’s calculate the calorific value (electric energy) of the HWS100A-5 when AC100V is input. Since the output is 5V20A, the output power is 100W. According to the specifications, the efficiency is 84%, so 100W ÷ 0.84 = 119W is consumed on the load side (secondary side), which means that 100W is actually used on the load. The difference 119W-100W = 19W is converted to heat.
Since the calorific value of 19W is the electric power generated per second, the value obtained by multiplying this by the time is the calorific value (electric energy) and the unit is J (joule). Or cal.

The calorific value (electric energy) of HWS100A-5 for 1 hour (3600 seconds) is 19W x 3600 seconds = 68,400J. There is also a calorie unit for calories. Since it is decided that 1J = 4.2cal to convert from J (joule) to cal (calorie), it becomes 68400J ÷ 4.2 = 16,285cal.

Accurate switching power supply statistics do not exist because some manufacturers make switching power supplies in-house. (The reason for making the switching power supply in-house is that there is no model with the desired specifications and size for the standard switching power supply, and the conditions such as the quantity of ordered lots and the unit price are not met, so the custom-made switching power supply manufacturer did not accept it. )

Roughly speaking, the domestic market for custom power supplies and switching power supplies combined with standard products is said to be 400-500 billion yen, and standard products are said to be 40 billion yen. The standard products are oligopolistic (duopoly) with a 70% market share between Cosel and TDK-Lambda, which are specialized manufacturers of switching power supplies. Manufacturers of switching power supplies other than these two companies are Omron, IDEC, Sanken Electric, Nipron, Asia Electronics Industry, Keyence, Sanken Electric, etc.

As data, there is “Current Status and Trends of Switched Power Supply (2019)” published by JEITA (Japan Electronics and Information Technology Industries Association) every three years. Is 1,358.7 billion yen (FY2015 results). The headquarters (development) of switching power supply manufacturers is Japan, the United States, and Germany, and the producing countries are China and Southeast Asia.

Production trends of domestic switching power supply manufacturers

　In China and other Asian countries, the production of switching power supplies has been shifted overseas as well as other electronic parts because it is possible to procure materials other than special parts and the manufacturing cost is low. -Last year, due to the problem of discontinuation of production of ceramic capacitors, the delivery date of switching power supplies was very imminent, and some end users replaced switching power supplies with other companies. Switching power supply manufacturers are also responding by returning some of their main models to domestic production and changing to a system that can be produced at multiple factories for emergency backup.

Although the manufacturing cost of overseas factories is low, the manufacturing cost is actually higher than that of domestic factories in consideration of transportation costs, shipping days, customs procedures, exchange risk, and air handling in case of trouble. “Apparently” overseas products are cheap, but in response to late delivery, we negotiate with overseas factories and subcontract factories over a few days, arrange for a change to air, and a salesman goes directly to Narita Airport to pick up the power supply. In that case, the cost cannot be added to the cost of the product individually. I don’t know because those costs are summarized in the labor costs of process control staff and sales staff, and air service costs.

LED Module　

　To turn on the LED module, use the power supply suitable for the LED module. The circuit of the LED module determines whether it is a constant current power supply or a constant voltage power supply, and there is no switching power supply that can be used with either. LED module manufacturers make “dedicated power supplies”, and the power supplies of standard power supply manufacturers are introduced on HP etc. as “recommended power supplies”.

LED module manufacturers use those power supplies to light LED modules to check illuminance, measure temperature, and perform continuous energization tests. Even if the power supply has the same specifications, if you use a power supply that is not recommended by the LED module manufacturer, it will not be covered by the warranty.

Source: Lens Module / AP Japan

The home appliances we use at home only work with “alternating current”, but the electricity generated by the photovoltaic power generation system is “direct current”, so we cannot use it as it is. Therefore, it is a power conditioner (power-con) that converts direct current to alternating current.

In other words, a power conditioner is a power supply device that converts the power generated by a solar cell (DC Direct current) into alternating current (AC100V / 200V) used in homes and factories. Generally, DC 320-400V generated by solar cells is converted to AC100V for homes and AC200V for factories. It becomes DC / AC and works in the opposite way to the switching power supply. A power conditioner is an inverter because the power supply that converts DC (direct current) to AC (alternating current) is called an inverter. In English, it is called PCS (Power Conditioning System), and it seems that the power conditioner (Power Conditioner) that we generally call does not work.

Before explaining the power conditioner, let’s talk about the photovoltaic power generation system.

What is a photovoltaic power generation system?

The national average capacity of solar panels installed on the roof of a house is 4.5kW. Depending on the manufacturer, the output capacity of one solar panel is 200 to 250W, and 4kW requires 16 to 20 panels. The cost is 1.2 to 1.5 million yen. This is the price of only the solar panel, and in addition to this, a stand and junction box for installing the power conditioner, power conditioner, breaker, monitor, construction cost, etc. are required separately. The breaker itself is already installed in the house, but if you want to incorporate it into a PV system, you need to change it to a dedicated breaker. It may cost 1.5 million to 1.8 million yen or more in total. If you add a storage battery to this, it will cost an additional 700,000 to 800,000 yen.

In addition, 4kW solar panels always generate 4kW, but they rarely generate 100% of 4kw. 4kW is the amount of power generated at the optimum solar radiation angle when the panel temperature is 25 ° C. Every time the panel temperature rises by 1 ° C, the amount of power generation drops by about 0.5%, depending on the model. Imagine the roof of a car shining in the middle of summer. The panel temperature should be at least 65 ° C. Since it is 25 ℃ to 40 ℃ higher, 0.5% × 40 = 20% 4kW × 0.8 = 3.2kW The amount of power generation will be 3.2kW. In addition to that, it may not generate electricity in the worst case due to dirt on the panel, shadows of buildings and electric wires, and the direction of the roof to be installed.

PV-DR006L-SET-M 三菱電機 パワーコンディショナー パワコン 接続箱／パワーモニター ばら売り 全国発送可能 激安 楽天で購入

Two types of PSE technical standards

出典：電気用品安全法「特定電気用品」／経済産業省

Among the 116 items of PSE’s Specified Electrical Appliances and Materials, there are items that are subject to “DC power supply“, but general switching power supplies are not PSE’s “DC power supply”.
This is because switching power supplies are not used by themselves and are not applicable to PSEs that target final products because they are premised on being incorporated into equipment.

In order for a switching power supply to be a PSE target product, there are some conditions in terms of shape so that it can be used by itself.

PSE was changed from the ministerial ordinance item ◯ standard to the attached table ◯ in 2014, but the technical standard did not change and only the construction changed. PSE has traditionally had two technical standards.

* There is no original technical standard of Appended Table 12, and the international technical standard of IEC becomes the technical standard of ” Appended Table 12″ as it is.

経産省：電気用品の技術上の基準を定める省令の解釈について

The technical standards for switching power supplies are shown in ” Appended Table 8″ as “DC power supply”, and in ” Appended Table 12″, IEC international standards are specified as “power supply”.

There is no difference in PSE regardless of whether you obtain PSE in ” Appended Table 8″ or ” Appended Table 12″.

It is not that which technical standard is more difficult or easier, but the items of the technical standard are different. The 12th international standard in Appended Table 12 has strict EMC (electromagnetic compatibility) and harmonic current regulations, and Appended Table 8 in the domestic standard has stricter insulation distance and creepage distance.

Which PSE should be obtained？

Since the design standards and test methods of switching power supply manufacturers comply with the international standard IEC60950-1, it is not difficult to obtain a PSE in ” Appended Table 12″.
On the other hand, in order to obtain PSE in ” Appended Table 8″, the edge surface, space, and insulation distance between the transformer and the circuit board are stricter than IEC60950-1 in ” Appended Table 12″, so the power supply itself becomes large.
Then, I think that you should get PSE in “Appended Table 12”, but there is one problem.

　When a manufacturer acquires a PSE, for example, if a switching power supply that has acquired the PSE in ” Appended Table 8″ is purchased and the device side also applies for PSE in the same ” Appended Table 8″, as long as the switching power supply is used within the standard. Does not require re-evaluation of the power supply.

On the other hand, if the device side obtains a PSE that is different from the switching power supply, the conformity test for the power supply will not be simplified. For example, when the device is trying to acquire PSE in Appended Table 8 and the built-in switching power supply has acquired PSE in Appended Table 12. In this case, it is necessary to evaluate the entire device in Appended Table 8, that is, to re-evaluate the power supply section in Appended Table 8.

Details are described in “Handling of DC power supplies for lamp appliances” by the Ministry of Economy, Trade and Industry.

A common problem is that switching power supplies are incompatible in Appended Table 8. This happens because the technical standards of PSE are different between (1) domestic standards and (2) international standards. Specifically, it is the transformer of the switching power supply and the edge surface, space, and insulation distance of the circuit board. In this case, the design of the switching power supply itself must be changed, which is not realistic. When applying for a PSE for a device, it is wise to first look for a switching power supply that has the same PSE as the PSE you are trying to obtain.

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