Switching power supply with air core transformer and DC output

Abstract

Switching power supply with air core transformer and DC output, which is related to the use of air core transformer in a switching power supply that supplies the required electrical power of the electrofilter in terms of voltage and current. Its main components are the primary coil, which is twisted into a filament with two ends P1 and P2, and an electromagnetic field is generated by the passage of current through the primary coil, the secondary coil, which is wound in the form of a number of discs with ends s1 and s2, in which the discs are stacked on top of each other in the form of a column with insulation. They are arranged in series and connected to each other in such a way that a silicone resin is used for insulation, with the feature that the secondary coil is placed inside the primary coil so that their electromagnetic fields intersect each other and with this method of placing and arranging the components, a desired magnetic coupling is achieved.

Description

Description of the invention Title of the invention (as stated in the declaration) Switching power supply with air core transformer and DC output Technical background of the relevant invention The present invention relates to the field of electronic engineering, in particular to a switching power supply with an air core transformer and a DC output for use in electrofilters. Technical problem and stating the objectives of the invention A review of the advantages and disadvantages of different types of voltage transformers in electrofilters is shown in Table 1. Table number one: Core type Disadvantages Advantages of iron core 1. Its rectified output has a lot of ripple. 2. Fluctuations in city power affect the output pattern. 3. Large size 4. High price 5. High weight 6. Slow speed to cut off during arc or short circuit 1. This transformer has a simple structure and can be directly connected to the 50Hz city power. Ferrite core 1. High weight 2. High price 3. Hysteresis drop and core heating 4. It does not work directly at the 50Hz network frequency. 1. It can work at high frequency and can control the network fluctuations with PWM and have a stable output. 2. Its DC output has a flat line because it cuts off short circuit and arc very quickly. Air core 1. It does not work directly at the 50Hz frequency with network power. 2. It works on the resonance frequency and its range. It has all the advantages of ferrite cores, and also has the following advantages: 1. Less weight 2. Cheaper price 3. No hysteresis loss. 4. No limitation at high frequency. In the present patent document, a switching power supply with an air-core transformer and a DC output is introduced, in which the disadvantages of previous types are eliminated. A description of the state of the prior art and the history of developments related to the claimed invention. According to definitions known in the prior art, a transformer is a low-voltage primary winding and a high-voltage secondary winding with magnetic coupling between the two windings. Magnetic coupling: When current passes through the primary winding, an electromagnetic field is created, and the transformer core transfers this field to the secondary winding, which transfers electrical power from the primary winding to the secondary winding of the transformer. Transformers are classified according to the type of core: 1) Iron, 2) Ferrite, 3) Air or coreless Iron and ferrite are the electrical power transfer agents of the core. Iron and ferrite cores are heavy, the price of the core itself is high, and hysteresis loss is one of the disadvantages of these types of transformers, which are examined in their patent table. The types of voltage transformers in electrofilters are specified in Table 1. Most transformers use a ferromagnetic core that conducts magnetic charge more effectively between the primary and secondary windings. Ferromagnetic cores are made of iron, cobalt, nickel, and other ferromagnetic materials, and the density of most of them is at least 7.38 g / cm, so transformers with ferromagnetic cores are heavier. Therefore, air-core transformers are significantly lighter and cheaper than transformers with ferromagnetic cores. In transformers with a ferromagnetic core, there is a hysteresis loop inside the core. Air core transformers work much better at high frequencies. Among the domestic patent documents, the closest documents to the present patent document are: The invention is entitled "Switching power supply from 1 watt to 1500 watts" and has registration number 98155, in which new ICs have been used in the design and construction of the electronic circuit of the device, which has achieved very high performance and efficiency in various tests and investigations. The use of ICs and transformers with ferrite cores at defined powers has increased the efficiency of the device from about 65 to 75 percent to about 75 to 85 percent. In this patent, an air core transformer is not used, but a ferrite core transformer in flyback and half-bridge mode is used. The invention is entitled "High-gain switching power supply with low harmonic injection" and has registration number 67503. In this invention, a switching power supply device is presented that has four switches and a forward transformer, a clamping capacitor, a balancing capacitor and two output diodes. To balance the forward transformer volts and prevent it from saturating, a balancing capacitor Cb is connected in series with it in the secondary so that when the switch is turned off, due to the conduction of the output diode, this capacitor drops a negative voltage across the switch and prevents it from saturating. In invention 67503, an air-core transformer is also not used. Ferrite transformers and old chips TL494 and SG3525 are used. The invention entitled "High-efficiency constant current resonant switching power supply suitable for laser diode power supply" and registered number 88900, relates to a constant current resonant switching power supply suitable for laser diode power supply converter and has many advantages such as soft switching, high frequency operation and consequently reducing the converter dimensions and high efficiency. The main purpose of presenting this converter is to power a set of laser diodes with a source with high efficiency and low switching losses and resistance to load changes even without a control loop, because one of the properties of this converter is its resistance to load changes without a feedback loop, which is also due to the special design of its filter that uses the immittance property. In this invention, an air-core transformer is not used. The image of the ferrite transformer can be seen in the photo of the manufactured sample. The invention entitled "Wounded rotor Disk type resolver without rotary transformer's core" and registered number 68126, in this invention, an asymmetrical half-bridge flyback forward converter with zero voltage switching capability with a small number of semiconductor elements has been designed and manufactured. In this structure, two flyback and forward converters are paralleled and both converters are switched at zero voltage. On the other hand, only two switches are used in the converter structure. In this converter, the windings of two transformers are wound on one EE core. The use of a magnetic core reduces the volume and reduces the input current ripple due to the coupling between the strand wires of the two transformers. In addition, the ac charge at the middle base becomes zero, which reduces core losses. Patent 68126 In this invention, an air core transformer is also not used. Among foreign patent documents, the closest documents to the present patent document are: The patent, titled "Power electronics equipments" and registered with US patent number 7622887 B2, concerns an electric vehicle starter panel made of two parts. -A generator that converts the 280-volt battery voltage to 750 volts for use in a three-phase inverter, and when the vehicle brakes, the electrical energy from the brakes is used to charge the battery. -A three-phase inverter that takes 750 volts from the generator and starts the three-phase motor of an electric vehicle. In this invention, an air-core transformer is used in the three-phase inverter unit to send and receive control pulses from the CPU to the panel (EGBT) and to transmit feedback pulses from the panel (EGBT) to the CPU. The specifications of this air core transformer are: -Small dimensions, only a few centimeters, and the maximum transmittable power is about 10 watts. -The primary and secondary windings are made flat, and the primary and secondary windings are placed on top of each other with proper insulation to perform magnetic coupling. As a result, the air core transformer in this patent is used to send and receive control signals in a three-phase inverter, while in our patent, the air core transformer is used to transmit power up to 20 kW and a voltage of 100 kV, which is why it differs from this invention in terms of its structure. The patent entitled "Transformer-based driver for power switches" and registered number US 10958268 B1, relates to the use of an air core transformer as a power MOSFET driver in a small package. Small dimensions and high operating frequency are the advantages of this patent. In this patent, a pulse transmission air core transformer is used for the power MOSFET driver and has no similarity to the subject of our invention. The present patent is an air core transformer for power transmission up to 20 kW and an operating voltage of 100 kV in the form of (SMPS). The invention is entitled "HIGH VOLTAGE / LOW VOLTAGE TRANSFORMER WITH THERMOPLASTIC AIR-CORE INSULATION" and has the registration number WO / 1998 / 010447 A1. This invention relates to a transformer with air core insulation, which includes a high voltage winding and a low voltage winding mounted on a column of the magnetic circuit. Its characteristic is that its high voltage winding is covered in a thermoplastic resin insulating housing and is placed on it with a surface layer of a thermoplastic resin. Its low voltage winding is covered with an electrically conductive resin. This transformer has a low voltage winding and a high voltage winding. These windings are insulated inside the thermoplastic resin. These resin-coated windings are placed on magnetic columns. Therefore, this transformer has a magnetic core. While in the air core transformer of our invention, no magnetic material is used. And in the air core transformer of our invention, there is no core. The invention entitled "AIR-CORE ELECTRIC TRANSFORMER LOW VOLTAGE STAGE" and registered number WO / 1998 / 010444 A1, relates to an air-core transformer having a magnetic circuit with columns around which electrical windings are arranged, the "low voltage" in each phase of the power supply consisting of an electrically conductive metal coil embedded in a heat-conducting coating. Polymer resin is molded onto each column of the magnetic circuit. Thus a more compact transformer is obtained in which the thickness of the air layers required for ventilation of the installation is reduced as much as possible. This invention, like the previous invention WO / 1998 / 010447 A1, places a low voltage coil and a high voltage coil on magnetic columns after resination. Therefore, the transformer of this invention also has a magnetic core. While the transformer of our invention is completely without a magnetic core. Providing a solution to an existing technical problem along with an accurate, sufficient, and integrated description of the invention The present invention relates to a switching power supply with an air core transformer and a DC output. In one embodiment of the invention, its application is in 200W-20KW electrofilters, in which the voltage and current ranges are 10KV-100KV and 2mA-200mA, respectively, but not limited to this. Figure 1 shows a view of the air transformer. P1 and P2 are the primary winding heads that have a secondary winding inside them like a spring. A1-A100 are wound discs with heads S1 and S2 connected in series and the secondary output of the transformer is S01 and S02. For complete disclosure of information, some basic definitions, such as magnetic coupling operations, are included in the text. The magnetic coupling operation in coreless transformers is such that the primary winding is positioned relative to the secondary winding in such a way that the electromagnetic field of the primary winding affects the secondary winding, or so to speak, the fields of the windings cancel each other out. This is done in two ways: 1) Facing each other: The primary and secondary windings are made flat and face each other. This design is often used for mobile phone chargers and electric vehicle chargers, where there is a flat coil inside the vehicle that, when charging, is placed in front of a coil that is in the ground to be charged. 2) Inside: The secondary coil is placed inside the primary coil. Because the maximum concentration of the magnetic field of a cylindrical coil is inside the coil (according to Lenz's law), and in this case, the electrical power is transferred from the primary coil to the secondary. This is how electromagnetic coupling is done. To start up an iron core transformer, with all its disadvantages, it is sufficient to connect it to the city's electricity and operate without any intermediaries. To start up, a ferrite transformer requires a generator that receives electrical energy from the city's electricity and injects it into the ferrite transformer at a frequency of about 50 kHz. The air core transformer also has its own generator that takes electrical energy from the city electricity and injects it into the air core transformer. In this type of transformer, due to its use in high powers, hard switches cannot be used; because it will cause the switch transistors to overheat and the power loss of the switch will increase. That is why the zvt method has been used in this invention. (This means zero voltage transfer). That is, the switch signals are programmed in such a way that when they are turned off, the voltage across them first becomes zero. In a transformer, an electromagnetic field is generated by passing an electric current through the primary winding. If the transformer has a core, the core transfers this electromagnetic field to the secondary winding to perform magnetic coupling and transfer electrical power from the primary to the secondary winding system. In the present invention, an air core transformer is used in a switching power supply. Since there is no ferromagnet in the core power supply to transfer the electromagnetic field and perform the magnetic coupling, the primary and secondary windings are arranged in such a way that their electromagnetic fields intersect each other to perform the magnetic coupling. There are various methods for the magnetic coupling operation, some of which have been mentioned in the invention documents and prior art, and in them, the way in which the primary winding is placed next to the secondary winding varies depending on its application. Figures two and three show a view of the primary and secondary windings, respectively. The schematic drawings drawn in this document relate to only one of the inventive embodiments and the description of the invention will be explained with reference to its embodiments and the description of these embodiments is only to clarify the operation of the device and the drawings and figures do not create a limitation on the final shape of the device and the placement of components. Figure 2 shows a view of the primary coil introduced in the present invention. This coil is in the form of a thick spring that houses the secondary pack, which will be described later. An electromagnetic field is generated by passing current through the primary coil. On the other hand, the secondary coil is also placed inside the primary coil, and with this movement, electromagnetic coupling is created and electrical power is transferred from the primary coil to the secondary. Figure 3 shows a view of the secondary winding introduced in the present invention. This winding is wound in the form of a disk with ends s1 and s2 and has an inner diameter a1 and an outer diameter a2. In one embodiment of the invention, the secondary winding wire is made of copper and its wire diameter is 0.5 mm, but it is not limited to this and Litz wire can also be used, but it should be noted that in that case the Foucault loss is lower. Figure 4 shows a schematic view of a secondary pack. In one embodiment of the invention, this pack comprises a number of, for example, 100 A-shaped disc pieces, labeled A1-A100. These discs are stacked on top of each other in a suitably insulated column and connected in series. The secondary output ends are labeled SO1 and SO2. It should be noted that electrical insulation between the A1-A100 discs in the secondary pack and the secondary to primary winding is very important. In this invention, a switching power supply drives an air-core transformer of an electrofilter, in other words, it supplies the electrical power required by the electrofilter in terms of voltage and current. For this reason, the items no connect, clean Overlood, Arc are the system control items. The device proposed in this invention; hv with negative output for ionizing smoke and dust and absorbing particles in the electrofilter. The innovative part is the presence of an air core transformer in the structure of the switching power supply to turn on an electrofilter. Connections: In high-frequency transformers, the use of ordinary wire creates a loss of phaco. The higher the amperage, the greater the amount of this phaco loss. Phaco is an eddy current in the wire that does not pass through the center of the wire but moves through the wire shell. For this reason, Litz wire is used in high-frequency transformers. Its structure is, for example, that for a wire strand with a diameter of half a millimeter, twenty strands of coated wire twisted together with a diameter of one tenth of a millimeter are used. But in this invention, because the maximum output amperage is 200 milliamps, a single-layer wire with a diameter of half a millimeter is used instead of Litz wire, and the power loss is not significant. In high voltage transformers, proper insulation is essential. If proper insulation is not provided, the transformer will burn out. This invention uses two coils. First, the primary coil is made in the form of twisted strands (similar to a spring) and the second secondary coil is made by connecting a number of discs, for example, 100 wound and insulated discs, which are placed in layers inside the primary coil. The insulation between the discs and between the discs and the primary coil is very important. The electromagnetic field inside the primary coil is very intense, which is why the secondary coil is placed inside the primary coil to achieve a desired magnetic coupling with this method of placement and arrangement of components. In one embodiment of the invention, Rv2 resin, which is a silicone resin, is used for insulation, and because this resin transfers heat, the transformer can be cooled by installing a fan. The number of turns of each disk and the stacking of a large number of disks on top of each other create a desired scattered coil capacitance (cr). This capacitance, together with the inductance L of the transformer secondary winding, creates a resonant frequency for the transformer introduced in this document. According to physical relationship number one, the transformer has the most power at this resonant frequency. (1) F0= The block diagram of a switching power supply device with an air-core transformer and a DC output consists of the components and units that are explained below. The Ih-Control unit is shown in Figure 5. This unit analyzes the voltage output current and allows the device to operate if the output current is normal, otherwise it stops the device. The device is in stop mode in the following situations: No Connect: When the HV output cable is disconnected. Clean: When the output current is less than the nominal value, the cause is that the electrofilter device is dirty and the device needs to be washed. Overload: If the HV output is short-circuited or the insulator is burnt, the current exceeds the rated value. Arc: In this mode, if an electric arc is created inside the electrofilter, the device stops for a few seconds and then starts again. This mode is created by the entry of large particles into the electrofilter. The ZVT Generator unit is shown in Figure 5. This unit is the main switching part. IGBT power panels at high powers suffer from high power losses during switching. In this document, the ZVT method has been used to reduce losses and minimize power line noise. ZVT is equivalent to zero transfer voltage. In this method, the IGBT turns off when the voltage across it is zero. At this time, the power loss of the IGBT is equal to PW=V*I and since V=0, the power loss is close to zero at the moment of turning off. When the primary winding starts its current from zero, therefore I=0 and according to the same process at the time of turning on, PW≈0. Air core transformer building sensitivities: These sensitivities include: Transformer power: The maximum power that can be transferred from primary to secondary.  Transformer resonant frequency: Depends on the type of transformer design and the stray capacitors inside the transformer.  Magnetic coupling to achieve maximum transmittable power: The smaller the distance between the primary and secondary windings, the better the magnetic coupling operation and the more power can be transmitted. Review of the transformer proposed in this document and its sensitivities: 1- Maximum power that can be transmitted by this transformer: According to Figures 2 to 4, which show the transformer components, the maximum power transfer of the transformer depends on the ratio and . Considering the above ratios, the higher the transformer's transmission power, the higher it will be, provided that the values ​​of a2, b1, and b2 also increase in proportion to the increase in a1. 2- Transformer resonance frequency: The air core transformer has the ability to operate at a resonant frequency, and this frequency is the result of the Henry value of the secondary winding with the capacitive effect scattered within the secondary winding. F0= In the transformer presented here, the secondary winding must be designed so that the frequency f0 is in the moderate range. The high voltage diodes at the output are not capable of operating at very high frequencies. 3- Magnetic coupling: If there are two coils in the form of disks, including the primary and secondary coils, and they are mounted on top of each other so that the primary magnetic field affects the secondary coil, the smaller the distance between the two disks, the greater the power that can be transferred from the primary to the secondary, and vice versa. In the method of placing the coils introduced in the present invention, namely placing the secondary coil inside the primary coil with the aforementioned characteristics for the coils, maximum magnetic coupling can be achieved. The various embodiments of the invention merely provide the detailed technical content of the present invention and its inventive features and do not limit the scope of the present invention. Various minor changes and substitutions made by those skilled in the art and experts in the field based on the information and suggestions of the present invention are all within the scope of the present document. Explanation of shapes, maps and diagrams Figure 1: A block diagram of the device introduced in the present invention. Figure 2: Shows a view of the primary coil introduced in the present invention. Figure 3: Shows a view of the secondary winding introduced in the present invention. Figure 4: Shows a schematic view of the secondary pack. Figure 5: A block diagram of the device introduced in the present invention. A clear and precise statement of the advantages of the claimed invention over prior inventions. The switching power supply with air core transformer has the following advantages over conventional models: Removing the transformer core increases the efficiency of the device, and the efficiency of the device is above 90%. Lower weight than the model with iron or ferrite core Cheaper price: In air core transformer, the cost of the core is eliminated and there are no losses inside the core. It has no hysteresis drop. There is no limit on high frequency. Description of at least one implementation method for implementing the invention Electric filters are one of the types of industrial dust collectors and hydrocarbon smoke and vapor purifiers that are used in many industries, including the steel, cement, foundry, ceramic, tile, brick, textile, Refinery and petrochemical industries. Electric filters have the ability to absorb fumes and hydrocarbon vapors and remove dust from the volume. Gas filters have a wide range of temperature, pressure and humidity of dust particles in wet or dry state. In many industries, the filtration efficiency of these filters is 99%. Electrostatic filters work by charging the particles in the gas stream and the electric current connected to the discharge electrodes creates a strong electric field between these electrodes and the collector surfaces. After entering the filter, the aerosol particles in the gas stream pass through the electric field around the discharge electrodes and the gas molecules are ionized due to being in this strong field. The suspended particles are charged due to collision with these ions and are deflected under the influence of the electric field towards the opposite pole, which are the collector plates. After colliding with the collector plates, the particles lose their charge or become liquid and fall into the hopper due to the force of gravity or, if dry, after a programmed period of time due to impact. Electrofilters are designed according to the volume of smoke or dust input, and the larger the volume of smoke or dust, the larger its dimensions and the higher its electrical power consumption. The operating voltage of the device is determined according to the type of design of the electrofilter device, i.e. the distance between the discharge electrode and the collector plates. The volume of the electrofilter device and the electrical current consumed by the device are determined according to the volume of smoke or dust input. The switching power supply with air core transformer introduced in the present patent document, with DC output, supplies the electrical power required by the electrofilter with a specific voltage and the required current. Explicit mention of the industrial application of the invention Switching power supply with air core transformer and DC output, which is related to the use of air core transformer in a switching power supply that supplies the required electrical power of the electrofilter in terms of voltage and current, and its main components are the primary winding which is twisted into a filament with two ends P1 and P2, and an electromagnetic field is generated by passing current through the primary winding, the secondary winding which is a number of wound discs with ends s1 and s2, in which the discs are located on top of each other in the form of an insulated column and are connected to each other in series, such that a silicone resin is used for insulation, with the feature that the secondary winding is placed inside the primary winding so that their electromagnetic fields cut each other off and with this method of placement and arrangement of the components, a desired magnetic coupling is achieved. Brief description of the invention Switching power supplies with air core transformers can be used in various electronic technologies, for example, wireless chargers for mobile phones or wireless chargers for electric vehicles. In the present patent document,

Claims

Claim What is claimed: Claim 1) Switching power supply with air core transformer and DC output, which relates to the use of an air core transformer in a switching power supply that supplies the required electrical power of the electrofilter in terms of voltage and current, and its main components are: - A primary winding that is twisted into a filament that has two ends P1 and P2, and an electromagnetic field is generated by passing current through the primary winding, - A secondary winding that is wound into a number of discs with ends s1 and s2, in which the discs are arranged on top of each other in an insulated column and are connected to each other in series, such that a silicone resin is used for insulation, with the feature that the secondary winding is placed inside the primary winding so that their electromagnetic fields cut each other off and with this method of placing and arranging the components, a desired magnetic coupling is achieved, - A source of electric current that injects electric energy into the air core transformer, and The switch signals are programmed so that when they are turned off, the voltage across them is initially zero.- hv which has a negative output to ionize smoke and dust and absorb particles in the electrofilter - Ih-Control unit which analyzes the voltage output current and if the output current is normal the device is allowed to work otherwise it stops the device - ZVT Generator unit which uses the ZVT method in this unit to reduce losses and minimize power line noise and the switch signals are programmed in such a way that when they are turned off, the voltage across them first becomes zero, Claim 2) The invention set forth in claim 1, wherein P1 and P2 are primary winding heads that house the secondary winding, and the wound discs are connected in series with heads S1 and S2, and the secondary output of the transformer is S01 and S02. Claim 3) The invention stated in the first claim is that the Ih-Control unit analyzes the voltage output current and if the output current is normal, the device is allowed to operate, otherwise it stops the device. Claim 4) The invention set forth in claims 1 and 3, in which the stop states are: when the HV output cable is disconnected, when the output current is less than the rated value, when the HV output is short-circuited or the insulator is burned, when the current exceeds the rated value, and in the ARC state, when an electric arc is created inside the electrofilter. Claim 5) The invention set forth in the first claim uses Rv2 resin, which is a silicone resin, for insulation. Claim 6) The invention set forth in claim 1, which states that the power supply is used in 200W-20KW electrofilters.

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