摘要：TeardownAfter disassembly, apart from the induction cooker's outer shell, the main internal components include a cooling fan, po
NOTE：Click here for the Chinese version.This episode disassembles a Xiaomi induction cooker.
Starting with the PCB motherboard, the upper right section in the image below shows the input interface, equipped with a fuse and connected to 220V AC power. The lower right section is the low-voltage part, which uses a non-isolated power supply chip (BP85976) from Bright Power Semiconductor in a DIP7 package to output 18V DC. This is further stepped down to 5V via a transformer. These outputs power the cooling fan, main control unit, buzzer, LEDs, etc.
The high-voltage section primarily consists of the induction cooker’s heating circuit, which includes three specialized capacitors, all housed in flame-retardant plastic casings. Two of these are from Chuangge Electronics’ MKP-X2 series, mainly used for input filtering, while the third is a BM resonant capacitor connected in parallel with the heating coil. The two interfaces on the left side of the image are for the heating coil. So, how exactly does the induction heating work? It’s a common misconception that the cooker directly uses mains electricity for heating. The frequency of mains power is too low for induction heating, which requires high-frequency AC. Thus, current conversion is necessary. Removing the aluminum heat sink from the PCB motherboard reveals the components underneath.
Beneath the heat sink are Leshan Sheier’s single-phase fully controlled rectifier bridge module (D20SB100) and CR Micro’s N-channel MOSFET (CRG25T135BKR3S). The filtered mains power first passes through Leshan Hill’s rectifier for conversion to DC. This DC power is then switched on and off by CR Micro’s N-channel MOSFET to achieve high-frequency current. Both of these power components generate significant heat, hence their placement under the heat sink. Now, let’s focus on the heating coil.
The heating coil is wound with enameled wire, meeting the induction cooker’s requirements for electrical insulation, compact layout, and efficient thermal conversion. The two thicker wires in the image above connect to the heating interfaces on the PCB motherboard. During actual heating, when you place a compatible pot (typically made of magnetic materials like iron or stainless steel) on the cooker’s surface, the alternating magnetic field’s lines of force penetrate the pot’s base. The pot’s bottom, due to cutting these magnetic lines, generates strong eddy currents. These currents, encountering the pot’s inherent resistance, convert electrical energy into heat via the Joule heating effect, rapidly heating the pot and its contents. Since the heat is generated directly in the pot itself, the thermal efficiency is exceptionally high, often exceeding 90%.
Additionally, the heating coil features magnetic strips (also called flux guiding strips) on both its front and back sides. These strips are arranged along the magnetic lines of force and serve to constrain and guide the magnetic field upward through the cooker’s ceramic panel to act on the pot. This reduces downward magnetic leakage and interference while preventing the cooker’s body from overheating. Adjacent to the cooker’s panel is an NTC thermistor, along with a white substance resembling thermal paste, which helps the NTC thermistor more accurately sense the temperature transmitted from the pot. Temperature changes alter the NTC’s resistance, which is converted into a voltage signal and sent to the cooker’s main control chip. Based on this signal, the chip can adjust heating power, stop heating, or trigger overheat protection. Returning to the PCB motherboard, the section discussed earlier primarily handles the heating circuit. Now, let’s examine the control section, where the microcontroller is located on the reverse side of the PCB.
The microcontroller is an 8-bit MCU from i-core, model AiP8F0010. According to official descriptions, this is a 8051-core MCU specifically designed for induction cookers.
The cooker’s power adjustment is achieved by the MCU reading signals from a rotary encoder, offering six power levels.
The cooling fan uses an 18V brushless DC motor from Dongguan Ningjie, model NJ9020SH.
SummaryThrough this disassembly of the Xiaomi induction cooker, its internal structure and hardware design choices become clear. The entire hardware solution undeniably relies entirely on Chinese chips. It’s worth noting that consumer electronics have been at the forefront of promoting domestic chip alternatives, and it’s hoped that industries like automotive electronics will follow suit.来源：与非网
