—— Saving the working principle of induction cooker
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 rectifier circuit converts 50Hz AC voltage into DC voltage, and then the DC voltage is converted into high frequency voltage with frequency of 20-40KHz through the control circuit, so that an alternating magnetic field will be generated on the coil disc of the induction cooker to cut and change at the bottom of the pot repeatedly, thereby generating annular current (eddy current) at the bottom of the pot, and using the short-circuit thermal effect of small resistance and large current to generate heat to directly heat the bottom of the pot, and then rapidly heat the contents in the pot. This oscillating heating method can reduce the intermediate links of heat transfer and greatly improve the heating efficiency.
The working principle diagram of electric control of induction cooker is as follows: AC power supply LC oscillation circuit power control bridge rectifier temperature regulation
Power drive circuit waveform generation circuit overvoltage detection circuit potential detection circuit main control IC circuit
Step-down rectifier circuit temperature detection circuit current adjustment.
In the second quarter, the model and project number of induction cooker are indicated.
First, the model representation method of induction cooker M- beautiful C- induction cooker
1. As far as the ceramic plate is concerned, p means that the surface of the ceramic plate is flat and a means that the surface of the ceramic plate is concave.
2. In terms of display mode: V- stands for 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. In other words, the digital tube display (mid-range series) is empty-indicating that there is no display function (low-range series).
3. As far as the shape of the ceramic panel is concerned: y- indicates that the panel is round (y: circle) 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. Such as: 08-indicates the maximum power of 800 W；; 16- indicates that the maximum power is1600 w w.
5. 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—— Maximum power is 2000 W；; A model.
Second, the number of induction cookers 1 22 Y V:
① Product display feature code: one letter indicates the display features of the product, distinguishing grades. V: VFD display-high-grade product (single furnace) C: LCD display-high-grade product S: digital display-mid-grade product E: LED display-low-grade induction cooker.
② Appearance characteristics of ceramic plate: one letter indicates the appearance characteristics of the product. Y-shaped circular ceramic plate F-shaped square ceramic plate
③ Product power feature code: two digits, representing the power of induction cooker1100. For example, 22 represents an induction cooker with 2200w W power.
④ Product identification code: distinguish the digital forms of different products. "1, 2, 3 ..." and so on.
Section III Introduction of Main Components and Functions of Induction Cooker
Midea's induction cooker is mainly composed of the following parts:
1, power cord 2, fan 3, coil disk 4, transformer 5, thermistor 6, ceramic board 7, base 8, upper cover 9, electric control board!
The functions and characteristics of each component are described as follows:
1, power cord: function: it is to introduce external commercial power into the induction cooker. Because the induction cooker consumes a lot of electricity, it requires a strong overcurrent capacity of the power cord. If the diameter of the wire core is too small, the power cord will heat up, and the skin 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 plate 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 groups of power supplies are +5V for MCU, display button and some low-voltage processing circuits, and+18V for IGBT drive or fan power supply. 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: it senses the heating temperature of the cooker and sends a signal to the control circuit. 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.
Step 7 sit at the bottom
8. Cover function: the plastic 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; Power control module; Key display module; Power module.
Features: 1, IGBT: working temperature less than 85 degrees, Toshiba of Japan, IR of the United States, Samsung of South Korea, Siemens of Germany. Beauty-Japan Toshiba 2, Chip: Japan, Motorola, South Korea, Taiwan Province Province; America-Toshiba 3. Capacitance: high-voltage oscillating capacitor, which constitutes the core of the oscillating circuit; High current, high voltage, fast charge and discharge, 105 high-quality high-temperature capacitor (ordinary 85 degrees) 4. Rectifier bridge: converts AC power supply into DC power supply to generate DC high voltage. Japan-new battery 5. Voltage comparator: 8, 6 produced by National Semiconductor Company. IGBT Drive: Midea-Toshiba, Japan 7. Regulator: Italian-French semiconductor company 7805 regulator.