Circuit diagram of Midea induction cooker (1)

Midea induction cooker circuit diagram chv-cmi48616

Electric circuit diagram of Midea induction cooker

Circuit diagram of Midea induction cooker (2)

As a new heating appliance and the latest heating method, induction cooker has the following advantages:

1. High efficiency and energy saving: different from the traditional heating method, induction cooker heats the boiler itself, reduces the intermediate link of heat transfer, and greatly improves the heating efficiency, up to 85-99%, saving more than half of the energy compared with the traditional furnace (electric furnace, gas furnace);

2. Safe and reliable: the induction cooker eliminates all kinds of hidden dangers of traditional stoves, and has passed the national security verification, so it is safe to use;

3. Intelligent cooking: using microcomputer program control, special software, automatic cooking, with appointment timing function, no need to watch;

4. Easy to carry: the induction cooker is small in size, plug in and play to meet the needs of modern life;

5. Environmental protection and hygiene: the boiler body is directly heated, without thermal radiation, and the real “cooking without open fire”. There is no waste gas such as heat, fireworks and carbon monoxide in the environment, so as to avoid the “sweating like rain” situation encountered in the cooking process with traditional stoves.

Schematic diagram of Midea induction cooker

Electric circuit diagram of Midea induction cooker

Circuit diagram of Midea induction cooker (3)

Induction cooker is a kind of kitchen electrical appliance which uses electromagnetic induction principle to convert electric energy into heat energy. In the interior of the electromagnetic cooker, the 50 / 60Hz AC voltage is converted into DC voltage by the rectifier circuit, and then the DC voltage is converted into the high-frequency voltage with the frequency of 20-40khz through the control circuit. The high-speed changing current flowing through the coil will produce a high-speed magnetic field. When the magnetic line in the magnetic field passes through the bottom metal body of the metal vessel (magnetic and conductive material), numerous small eddy currents will be generated The dish itself heats itself at high speed, and then the contents of the dish are heated. As shown in the figure below, it is the principle circuit diagram of household induction cooker.

Electric circuit diagram of Midea induction cooker

Circuit diagram of Midea induction cooker (4)

Circuit diagram of Midea induction cooker

Electric circuit diagram of Midea induction cooker

Circuit diagram of Midea induction cooker (5)

The main board circuit of Midea sk2101 induction cooker is shown in the figure below.

1、 Introduction of single chip microcomputer main board circuit

1. Main board code and single chip microcomputer chip (U1) model

Take off the motherboard of the single-chip microcomputer, and you can see that “tm-s1-01a-a” is marked in the center of the motherboard, which is the code of the motherboard (the upgraded version of tm-s1-01a); “verm3.0” is the software version of the motherboard; and “2009-09-05” means that the motherboard is the 2009 standard board single-chip microcomputer. The main board circuit is shown in Figure L. the single chip microcomputer chip is a 20 pin dual in-line IC, and a white paper label is pasted on it, which indicates that “s01a-a-v12-n-7f” is the model calibrated by the manufacturer for the single-chip microcomputer chip. Under the label, there is a plastic package on the shell, and the original model is “S007”.

The MCU chip has built-in synchronous voltage comparison circuit, high-voltage protection circuit, grid voltage detection circuit, current detection circuit, surge protection circuit, pulse width control circuit, pot temperature detection circuit, IGBT tube temperature detection circuit, fan control circuit and alarm control circuit, etc., which greatly simplifies the peripheral circuit of the single-chip microcomputer.

Electric circuit diagram of Midea induction cooker

2. High voltage power supply and LC oscillation (resonance) circuit

The AC 220 V voltage is protected, rectified and filtered by FL, Cl, R38 and db1, ll, C4 to form a + 300V DC voltage, which is added to the LC oscillation circuit composed of coil ll and C5, and the electric energy is converted into heat energy by electromagnetic induction.

3. Synchronous sampling circuit

There are two sampling branches in the circuit. One is that the coil is close to the + 300V end, which is represented by V +. The V + sampling branch is composed of R3, R19, R14 and C8, which is added to UL (20) pin after depressurization and partial voltage; the second is that the coil is close to the IGBT / C end of the switch tube, which is represented by V -. The v-sampling branch is composed of R4, R5, R32, r37 and R24, R15, R16, which is added to UL (19) pin after depressurization and partial voltage of the above resistance. D5 in the figure plays a protective role, which can limit the high reverse peak voltage to about 5V to avoid UL breakdown.

4. High voltage protection circuit

Most of the components of the circuit are shared with v-sampling branch, only R18 is added to step down, and the peak sampling signal is added to UL (18) pin. When the reverse peak voltage of IGBT exceeds the preset value, UL will send out standby protection command.

5. Power grid voltage detection circuit

The grid voltage is rectified by the rectifier tubes of the two grounding terminals of DL, D2 and db1, and then is depressurized and divided by R29, R26, R40 and R12 of the detection circuit to UL 10 pin. When the grid voltage is too high or too low, UL will send out a standby protection command. In order to avoid the disturbance of the instantaneous peak voltage to the circuit and cause misoperation, the ec14 filter capacitor is added in the circuit.

6. Surge protection circuit

The circuit is composed of R29, RL, C2 and R40, RLL, C7. Surge voltage reduction and partial voltage are added to UL ① pin. When the power grid has surge, U1 will send out the standby protection command. In order to make the surge signal reach UL quickly and make UL react as soon as possible, C2 is specially designed as accelerating capacitor in the circuit. D4 in the figure plays a protective role to prevent UL from being broken down by high surge voltage. The protection principle is the same as D5.

7. Current detection circuit

The detection element of this circuit is Kangtong RK1. When the local current flows from “IGBT ground” to “rectifier bridge ground”, negative voltage drop will be generated on RKI. After R2, VR1 depressurization and regulation, C3 and C27 filtering high frequency clutter, it was added to UL (17) pin. The current detection signal will be separated into three kinds of special signals in UL: first, special power regulation; second, special boiler detection; third, special over-current protection.

8. IGBT tube driving circuit

The circuit consists of QL, Q2, Q3 and its peripheral components. The power regulation driving pulse is added to B pole of Q2 by U1 ③ pin, and then added to push-pull circuit composed of QL and Q3 after Q2 amplification. The output of push-pull circuit is added to g-pole of IGBT1 through R7 to control the on-time ratio of IGBT to realize power regulation.

9. Boiler temperature detection circuit

The circuit is composed of rt2 (via cn9 plug-in), C25 and R28, and the detection signal is added to U1 (12) pin.

10. IGBT tube temperature detection circuit

The circuit consists of RTI, R27, R34 and C24. The detection signal is added to UL (11) pin.

11. Fan and alarm control circuit

The fan control signal is output from U1 ⑤ pin and added to B pole of Q4 via R20. When Q4 is on, the fan rotates; when Q4 is cut off, the fan stops rotating (D3 in the figure is freewheeling diode). The alarm control signal is output by UL 6 pin and added to bz1 through C6.

12. Low voltage switching power supply circuit

The circuit consists of U2 (VIPer12A), switching transformer L2 (hxee10-18v-9v), U3 (78l05) and its peripheral components, which provides + 18V and + 5V stable working voltage for the main board.

Circuit diagram of Midea induction cooker (6)

Electric circuit diagram of Midea induction cooker

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