“As one of the most basic configurations of a car, an automotive air conditioner can heat, cool, ventilate and purify the air in the cabin to meet people’s comfort requirements for the vehicle’s riding environment. This article will give you a detailed introduction to an important part of the automotive air conditioning system: the air conditioning controller.
Introduction: As one of the most basic configurations of a vehicle, automotive air conditioners can heat, cool, ventilate and purify the air in the cabin to meet people’s comfort requirements for the vehicle’s riding environment. This article will give you a detailed introduction to an important part of the automotive air conditioning system: the air conditioning controller.
1. Composition of air conditioning system
A standard automotive air conditioning system consists of an air conditioning control panel, an air conditioning compressor, an air conditioning PTC, an air conditioning controller, a blower, and various executive devices and sensors. Among them, the air-conditioning control Panel is responsible for the input of user instructions, and the driver and passengers can adjust the temperature, humidity, cleanliness, flow rate, etc. of the air in the car through the air-conditioning control panel; the air-conditioning compressor is used for air cooling; the air-conditioning PTC is used for air conditioning Heating; the blower is used to output a certain air volume; and the air conditioner controller is the core of connecting the above products. It can accurately obtain the actual situation of the interior environment and control each module according to the user’s needs, so that the interior environment can meet the needs of users. requirements.
Figure 1. Air conditioning system composition
2. Block Diagram of Air Conditioning Controller
The air conditioning controller is connected to multiple sensors in the car, and can accurately obtain the interior environment through these sensors. At the same time, the controller communicates with the air-conditioning control panel through CAN, which can obtain the driver’s requirements for the environment in real time. Using the internal algorithm, the air-conditioning compressor, the air-conditioning PTC, the blower and the air-conditioning compressor, air-conditioning PTC, blower and other actuators are controlled through CAN to achieve precise control of the interior environment of the vehicle.
The detailed block diagram of the air conditioner controller is as follows:
Figure 2. Air Conditioner Controller Block Diagram
1. Key device recommendation
Main control: Since the air-conditioning controller needs to connect multiple sensors in the car, it needs a more complex control algorithm, and has high requirements for the FLASH size and the number of ADC channels of the main control. NXP’s S32K series MCUs are rich in resources and cost-effective. Flash is from 128KB to 2MB, and the number of ADC channels is from 13 to 64. It is sufficient for air conditioning controller applications with different needs.
Figure 3. S32K Series Resources
Multi-channel H-bridge drive: ON’s NCV772x (x: 1,3,4,5,6) series, which can drive up to 11 DC motors. Has the following characteristics:
l 0.5A continuous current, 1.1A peak current;
l 5MHz SPI communication
l Compatible with 5V and 3.3V systems;
l Over-voltage, under-voltage shutdown; over-temperature, over-current protection;
l Light load detection;
l Fault error reporting;
Figure 4. NCV7726 Typical Application
Multi-channel low-side driver: E520.01 (12 channels) and E520.03 (8 channels) of ELMOS are multi-channel low-side driver chips with stall detection. It is very suitable for stepper motor drive occasions, and its characteristics are as follows:
l (RON typ. 1.2Ohm / IMAX = 350mA), with stall detection function
l Open circuit, over temperature detection, short circuit detection and limit, drive inductive load can output clamp
l The output can drive larger loads in parallel
l Digital voltage range 3V~5.5V
l Small standby current
l SPI interface to communicate with MCU
Figure 5. E520.0x Block Diagram