When the air conditioner quietly increases the fan speed in the middle of the night, or automatically starts the defrosting program when the outdoor unit frosts over—these seemingly simple actions are backed by a sophisticated industrial-grade control system. It is the “brain” of factory automation production lines: a miniaturized version of a PLC (Programmable Logic Controller).
1. The “Invisible Engineer” in Air Conditioners: How Does the Mini PLC Work?
The core control unit: the MCU (Microcontroller) chip on the air conditioner’s mainboard, is essentially a simplified version of a PLC. It executes tens of thousands of decision cycles per second:
1. Sensing the environment: collecting data through temperature and humidity sensors (error ±0.5℃), human infrared sensors, etc.
2. Logical operations: comparing set parameters (e.g., 26℃) with real-time data.
3. Output commands: adjusting compressor speed (0-120Hz stepless speed regulation), four-way valve direction, and fan power.
> Example: Detecting room temperature at 28℃→Starting cooling→Calculating temperature difference→Outputting PWM signal to control the compressor to operate at 70% power.
2. The key to being smarter than traditional appliances: Programmable Logic
Comparing mechanical control of ordinary appliances (like timed switches) with the PLC control of air conditioners:
Actual effects:
– After detecting that the user has fallen asleep, automatically switch to silent mode (fan ≤20dB).
– Recognizing that the room is unoccupied, entering energy-saving standby mode (power consumption reduced to 5W or below).
3. Three scenarios to see the PLC’s “highlights”:
1. Rapid defrosting:
– Traditional air conditioners: timed defrosting, may not defrost strongly.
– PLC control: Real-time monitoring through pipe temperature sensors (threshold <-3℃), reverse cycle heating defrosting, process shortened to 3 minutes.
2. Preventing cold wind traps:
When heating starts: first turn on the fan for preheating (air outlet ≥30℃ before blowing air), avoiding blowing out cold air.
3. Fault self-diagnosis:
Compressor overcurrent → PLC cuts off power → fault code E1 flashes → repair technician accurately locates capacitor fault based on the code.
4. Technical upgrade: from fixed logic to AI collaboration.
The new generation of air conditioners is evolving the PLC into an “edge computing node”:
1. Supported by learning algorithms: records the user’s return time every Friday night, preemptively starting cooling.
2. Cloud interconnection: uploads operational data through the WiFi module, allowing manufacturers to remotely optimize control logic.
3. Multi-device linkage: detects excessive indoor CO₂ concentration, automatically activates the fresh air system (requires PLC protocol interoperability).
> Industry data: By 2025, the global penetration rate of smart air conditioners will reach 65%, with the computing power of their control chips increasing by 15 times compared to ten years ago.
5. User-perceptible “PLC dividends”:
– Sharp reduction in electricity bills: dynamically adjusting power through PID algorithms, saving 40% compared to fixed-frequency air conditioners.
– Extended lifespan: intelligent start-stop reduces compressor wear, extending lifespan to 12 years.
– Silent revolution: stepless speed regulation of the fan, nighttime operating sound pressure level below 25dB (equivalent to the sound of turning a page).
Next time you hear the gentle start of the air conditioner compressor, imagine: a chip the size of a fingernail is meticulously guarding your comfort zone with industrial-grade precision, completing the full chain response of environment scanning → logical judgment → precise execution within 0.1 seconds. From factory assembly lines to home air conditioners, PLC technology is integrating into life in a miniaturized and intelligent manner—while you enjoy the constant cool breeze at 26℃, an intricate automated symphony is quietly unfolding within the walls.