Application of Current Transformer in Overcurrent Detection of Induction Cooker

“There are many circuits for current detection. Generally, the current signal is converted into a voltage signal, and then the voltage is detected through the AD port of the single-chip microcomputer. For large voltage and high current occasions, it is generally necessary to reduce the voltage before testing. The current transformer is this principle. It uses the principle of electromagnetic induction, a device that converts a large current in the primary to a small current in the secondary.

“

There are many circuits for current detection. Generally, the current signal is converted into a voltage signal, and then the voltage is detected through the AD port of the single-chip microcomputer. For large voltage and high current occasions, it is generally necessary to reduce the voltage before testing. The current transformer is this principle. It uses the principle of electromagnetic induction, a device that converts a large current in the primary to a small current in the secondary.

The number of turns of the primary winding of the current transformer is generally small, and it is connected in the circuit of the measured current. The following figure shows the current transformer.

The current transformer is widely used in the overcurrent detection of the induction cooker. The following figure is a part of the current detection circuit of a current transformer. Its ultimate purpose is to test the working current of the circuit, so as to continuously adjust the power output of the induction cooker to keep its work stable. The circuit is mainly composed of current transformers, resistors, capacitors and so on. Working principle: After the mains passes through the power transformer, the secondary voltage is obtained. After being rectified by the rectifier diodes D1-D4, it is filtered by the electrolytic capacitor MC1 to obtain a relatively smooth DC current, and the signal obtained after dividing the voltage by R3 and R4 is sent to IC, IC detects the magnitude of the voltage sent over to judge the magnitude of the current. The greater the voltage, the greater the current. In this way, the IC will control the on-time of the IGBT switch to ensure the stability of the power output. Some current detection circuits are composed of LM339, which compares the voltages of the two to output a signal.