Inverter air conditioner current detection circuit

A current-voltage conversion circuit is commonly utilized in current detection applications. An example is the current detection circuit for a ring inverter air conditioner, which primarily serves to monitor the supply current of the compressor motor. Excessive current can potentially damage the compressor motor or even cause the motor coil to burn out. This current detection circuit identifies abnormal supply currents, prompting the air conditioner to automatically display an error code and initiate protective measures. When the AC power supply of 22V is applied to the compressor, the current transformer L2 generates a current signal that is subsequently rectified by the diode VD2. The signal is then processed through resistors R10 and R11, along with capacitor C13, before being input to the MB89865 microcontroller. The current transformers and rectifier diode VD2 convert the compressor's current consumption into a DC voltage that is fed to the CPU. The CPU performs analog-to-digital conversion and monitors the voltage; if it increases beyond a certain threshold, protective actions are triggered. The diode VD1 functions as a clamping diode, ensuring that if the output voltage from VD2 exceeds 5V, it is clamped to a maximum of 5V.

The current-voltage conversion circuit described functions as a critical component in ensuring the operational safety of air conditioning systems, particularly those using a ring inverter technology. The circuit design incorporates a current transformer, which is essential for isolating the high-voltage AC supply from the low-voltage control circuitry. This isolation is crucial for protecting sensitive electronic components from potential damage due to high currents.

The rectification process performed by diode VD2 is vital for converting the alternating current (AC) signal induced by the transformer into a direct current (DC) signal. This DC signal is then scaled down through the resistors R10 and R11, which serve to limit the voltage levels that the microcontroller MB89865 will interpret. Capacitor C13 plays a role in filtering the rectified signal, smoothing out any ripples and providing a stable input voltage to the microcontroller.

The MB89865 microcontroller is programmed to continuously monitor the voltage levels received from the current detection circuit. It is equipped with an analog-to-digital converter (ADC) that translates the analog voltage into a digital format for processing. If the detected voltage exceeds a predefined threshold, indicating an overcurrent condition, the microcontroller triggers an error code display on the air conditioner's interface, alerting the user to the fault condition. Additionally, the microcontroller can initiate protective mechanisms, such as shutting down the compressor to prevent further damage.

The clamping action of diode VD1 is a protective feature that safeguards the microcontroller from overvoltage conditions. By clamping the voltage to a maximum of 5V, it ensures that the input to the microcontroller remains within safe operational limits, thus enhancing the reliability and longevity of the entire system.

Overall, this current-voltage conversion circuit is an essential part of modern air conditioning systems, providing real-time monitoring and protection for critical components, thereby ensuring efficient and safe operation.Current-voltage conversion circuit is often used in the current detection circuit, shown 6-19 ring inverter air conditioner current detection circuit, the circuit is mainly use d to detect the size of the supply current of the compressor motor. When the current is too large, you may damage the compressor motor, and even will burn the motor coil using current detection circuit for detecting the supply current, if found abnormal supply current, the air conditioner will automatically display the error code and immediate protection. When the AC 22V power supply for the compressor, the current transformer L2 induce a current signal, and then rectified by the VD2, Rl0 and Rll partial pressure and C13 cicada after wave input to the MB89865 feet.

Current transformers and rectifier diode VD2 current consumption of the compressor will turn into a DC voltage supplied to the CPU (foot of snow, the A/D conversion and detection in the CPU, such as the voltage increases, will be protected. Diode VD] as a clamping diode, when the output voltage VD2 high voltage over 5v, VD1 DC voltage clamped at 5v.