The principle of induction cooker is shown as the schematic diagram of induction cooker. It uses high-frequency current to coil inside the induction cooker.
(1) According to the working principle of induction cooker, the physical knowledge that may be involved in the use of induction cooker includes: magnetic effect of current, thermal effect of current (Joule heat), impedance (resistance), magnetic field, magnetization, magnetic induction line, electromagnetic induction, energy conversion, molecular thermal motion, heat transfer, internal energy, molecular current, induced current and eddy current. (2) due to. When steaming steamed bread, you should boil the water, which will generate steam and transfer the heat to steamed bread. It takes 25 minutes to steam one steamed bun and five steamed buns. (3) The lowest thermal efficiency is 90% and the lowest temperature is adjusted to 100℃. In the range of power regulation and temperature regulation, the relationship between heating temperature and power regulation of induction cooker is linear. At this time, the actual power P consumed by induction cooker is proportional to the heating temperature T. 70℃P? 450W=240℃？ 70℃ 1600W？ 450W ① Available: t temperature =17℃15w (p-450 w)+70℃, when t temperature = 100℃, P=653W ② Heat absorbed by water: q absorption = cm (. Energy absorbed by water when the induction cooker does work: W=Ptη, heat generated by the induction cooker is equal to heat absorbed by water, W=Q suction =Ptη, and heating time of the induction cooker: t = WP η = 9.825. ④ So the answers are: (1) magnetic effect of current, thermal effect of current (Joule heat), impedance (resistance), magnetic field and magnetization; (2) pot; Induction cooker; Electricity; Inside; (3) At 1 standard atmospheric pressure, it takes 1672s at most to boil a pot of water with a mass of 3kg and a temperature of 22℃.
What is the working principle of induction cooker?
The induction cooker adopts the principle of magnetic field induction eddy current heating. It uses current to generate a magnetic field through a coil. When the magnetic force in the magnetic field passes through the bottom of the iron-containing pot, it will produce countless tiny eddy currents, which will make the pot itself heat at high speed, and then heat the food in the pot. Electromagnetic waves generated when the induction cooker works are completely absorbed by the shielding layer at the bottom of the coil and the iron pan on the top plate.
Heating principle of induction cooker
Electromagnetic induction cookers are used to heat food. The surface of the induction cooker is a heat-resistant ceramic plate. Alternating current generates a magnetic field through a coil under a ceramic plate. When the magnetic lines of force in the magnetic field pass through the bottom of an iron pan, a stainless steel pot and the like. , produce vortex, so that the bottom of the pot quickly heats up, thus achieving the purpose of heating food. Its working process is as follows: AC voltage is converted into DC by rectifier, and then DC is converted into high-frequency AC which exceeds audio frequency by high-frequency power conversion device, and the high-frequency AC is added to flat hollow spiral induction heating coil, thus generating high-frequency alternating magnetic field. Its magnetic field lines penetrate the ceramic platen of the furnace and act on the metal pot. Due to electromagnetic induction, there is a strong eddy current in the pot. When the vortex flows against the internal resistance of the pot, the conversion from electric energy to heat energy is completed, and the generated Joule heat is the heat source of cooking.
What is the principle of induction cooker?
Principle of induction cooker
When the loop coil is energized, its effect is equivalent to a magnetic bar. Therefore, there is a magnetic field N-S pole on the surface of the coil, that is, there is a magnetic flux crossing. If the power supply is alternating current, the magnetic pole of the coil and the magnetic flux crossing back to the road will change.
When the magnetic conductive metal surface is placed above the annular coil, current will be induced on the metal surface. Because the metal surface has resistance, the induced current will generate heat energy on the metal surface, which can be used to cook food.
The greater the induced current, the higher the heat generated and the shorter the cooking time. The greater the induced current, the greater the change of magnetic flux passing through the metal surface, and of course the stronger the magnetic field strength. In this way, the more turns are needed to wind the original coil with alternating current.
Because of the high-intensity magnetic field induction, there is no current on the surface of the stove, so the surface of the stove will not produce high temperature when cooking food, so it is a relatively safe cooking appliance.
Working principle of induction cooker
Working principle and structure of induction cooker The induction cooker is mainly a kitchen appliance that uses electromagnetic induction principle to convert electric energy into heat energy. When the induction cooker works normally, the AC voltage of 50Hz is converted into DC voltage through the rectifier circuit, and then the DC voltage is converted into high-frequency voltage with the frequency of 20-40KHz through the control circuit, so that an alternating magnetic field is generated on the coil disc of the induction cooker, which is repeatedly cut and changed at the bottom of the pot, so that a ring current (eddy current) is generated at the bottom of the pot, and heat is directly generated by the short-circuit thermal effect of small resistance and large current.
This oscillating heating method can reduce the intermediate links of heat transfer and greatly improve the heating efficiency. The working principle block diagram of electric control of induction cooker is as follows: AC power supply LC oscillation circuit power control bridge rectifier temperature adjustment power drive circuit waveform generation circuit overvoltage detection circuit pot detection circuit main control ic circuit buck rectifier circuit temperature detection circuit current adjustment. In the second quarter, the model and article number expression method 1, induction cooker M- Midea C- induction cooker 1 model expression method. For ceramic plates, P- means that the surface of the ceramic plate is flat, and A- means that the surface of the ceramic plate is concave. For display mode, V- means VFD display.
That is, fluorescent color display (high-end series) C- stands for LCD display. That is, blue screen LCD (mid-range series) S- stands for digital display.
That is, the display of the digital tube (mid-range series) is empty, indicating that there is no display function (low-range series). 3. As for the shape of the ceramic panel: Y- indicates that the panel is round (y: round) f- indicates that the panel is square. 4. Power description: It consists of two digits, and the data * 100 is the maximum power of the induction cooker. For example: 08-indicates the maximum power of 800W 16- indicates the maximum power of 1600W5. Equipment identification codes: A, B, C and D are used to distinguish different induction cookers in the same series (note: the new PSF series products will be listed as soon as possible, and the old PSD certification will be used temporarily, so the PSD codes of this series products will be kept. )
Coding example: MC-PVF 20 A M- Midea; C- induction cooker; Planar ceramic plate; V-VFD display mode; Square ceramic panel; 20-the maximum power is 2000W W. A model. Second, the expression method of the number of the induction cooker 1 22 Y V: ① product display feature code: a letter represents the product display characteristics, which is also the distinction of grades. V:VFD display-high-grade product (single furnace) C: liquid crystal display-high-grade product S: digital display-mid-grade product E:LED display-low-grade induction cooker ② Ceramic plate shape characteristics: a letter represents the product appearance characteristics.
Y round ceramic plate F square ceramic plate ③ product power feature code: two digits, representing the power of induction cooker1100. For example, 22 represents the product identification code of the induction cooker with 2200w power: digital form, which distinguishes different products.
"1, 2, 3 ...1,power cord: Function: Introducing external mains into induction Because the induction cooker consumes a lot of electricity, it needs a strong overcurrent capacity. If the diameter of the wire core is too small, the power cord will heat up, and the sheath will harden or even burn out after long-term use. Features: Midea's existing power cord core diameter is 1.0mm2, and it can pass the current of 10A.
2. Fan function: The fan is a heat dissipation component in the induction cooker. At present, there are three kinds of fans: brush fan 1 and brushless fan 2; Brushless fans are divided into 12V and 18V.
Features: Brushless fan is more durable, with larger air volume and less noise; The noise source of brush fan is mainly airflow sound. 3. coil function: in the induction cooker, it is one of the key devices to complete LC oscillation, to store and release electric energy, and to convert electric field energy into magnetic field energy.
In the circuit principle, it is generally analyzed as inductance, which is divided into two types: large coil and small coil. * * There are two kinds of inductors, 140uH and 157uH. Features: the national patent large coil ensures the heating area of the bottom of the pot 100%, which is more uniform in heating and higher in thermal efficiency. 4. transformer function: it is a device that converts 220V alternating current into low-voltage alternating current. Generally, there are two or three groups of power supplies on the induction cooker, +5V and+18V, and the three groups of power supplies also include+12V. Generally, two sets of power supplies are +5V for MCU, display buttons and some low-voltage processing circuits, and+18V for IGBT driving or fan power supply. Generally, three sets of power supplies are used to separate IGBT drive from fan power supply, and the fan power supply is+12V.
The transformer provides the preceding low-voltage alternating current for the above power supply. Therefore, transformers generally have three sets of power supplies.
Features: Midea adopts hot-rolled silicon steel sheet transformer to reduce power loss and heat generation of transformer and prolong service life. 5 Thermistor function: sense the heating temperature of the cooker and transmit the signal to the control loop. The main control IC controls the working process of the induction cooker through judgment. Features: adopting negative temperature coefficient material, imported quality.
6. The function of the ceramic plate: On the outermost surface of the induction cooker, the appearance quality of the induction cooker is determined, which is divided into two categories: domestic and imported, and domestic is divided into glazed and unglazed. Generally speaking, it is not easy to yellow after glazing. Features: Very small expansion coefficient, radial heat transfer, high temperature resistance and wear resistance when heated.
Imported ceramic plate: white. Ceramic plates for daily use: A, B, C and glazing.
7. Bottom seat 8. Upper cover function: the plastic upper cover and the base * * * together form the product protective shell. Features: Midea's induction cooker adopts V0 flame retardant, antibacterial, mildewproof and ultraviolet resistant plastic, and the antibacterial rate certified by the authoritative department is 99.89%.
Surface double-layer metal spraying process: spraying protective paint on the surface greatly improves the scratch resistance of the coating. 9, electric control board function: the key component of the induction cooker, with nearly 200 components.
There are the following modules on the circuit board: the power supply enters the EMC protection module; Rectifier module; A filtering module; LC oscillation module; IGBT switch module; Zero-crossing detection module; Current detection module; Voltage detection module; Temperature detection module; Synchronization module; Oscillation control module; IGBT drive module; Work.
Read this article and then answer the following questions. As shown in the figure, it is a schematic diagram describing the principle of induction cooker.
(1) According to "Because the induction cooker generates current through electromagnetic induction and generates heat through electrothermal effect, it is not applicable to all pots or appliances", it can be known that the thermal effect of current is used here; According to "the choice of pot, the method is very simple, as long as the pot bottom can attract the magnet", it can be seen that the magnetic effect of current is used here; (2) Because ceramics and glass are generally neither magnetic nor conductive, they will not generate induced current in a magnetic field, while aluminum and copper are not magnetic materials, so cookware made of these two materials cannot be used in induction cookers. (3) Because the induction wires can pass through the cardboard, and the iron pot has enough induction wires, the induction cooker can work normally. So the answer is: (1) the thermal effect of current; Magnetic effect of current; (2) Answer: Because ceramics and glass are generally non-conductive and non-conductive, they will not generate induced current in the magnetic field, while aluminum and copper are not magnetic materials. So the induction cooker can't use these two materials. (3) Answer: Because the magnetic induction wire can pass through the cardboard and the iron pot has enough magnetic induction wire, the induction cooker can work normally.