High Voltage System Cooling Control

SYSTEM

HIGH VOLTAGE SYSTEM COOLING CONTROL : System Description

VCM controls water pump 1, water pump 2, and cooling fan according to information from various sensors and
ECUs.

SYSTEM DIAGRAM







WATER PUMP CONTROL

Control Description
The cooling system includes two pumps. By driving these two pumps individually, VCM controls the coolant flow rate according to the coolant temperature and vehicle speed. In addition, if one of the pumps malfunctions, VCM increases the rotation speed of the other to prevent a decrease in the coolant flow rate.
VCM controls the water pump as per the following.





NOTE:
- VCM performs the low vehicle speed and low temperature coolant flow control at approximately 30 km/h (19
MPH) or less. The low vehicle speed and low temperature coolant flow control is switched to the normal control when vehicle speed becomes approximately 35 km/h (22 MPH) or more.
- VCM performs the low vehicle speed and low temperature coolant flow control when coolant temperature is less than 30�
C (86�F). The low vehicle speed and low temperature coolant flow control is switched to normal control when coolant temperature is 30�
C (86�F) or more.
Fail-Safe
If either water pump malfunctions, VCM controls the water pumps as per the following.











COOLING FAN CONTROL

Control Description
VCM calculates the required cooling fan speed from the operation status of the air conditioner, coolant temperature, refrigerant pressure, and vehicle speed. VCM transmits the PWM signal to the cooling fan control module according to the calculated value.
During normal driving or Li-ion battery charging, VCM determines a cooling fan speed by selecting the highest value from a coolant temperature request value and the sum of an air conditioner request value and an evaporator temperature correction value, as shown in the following table.
Coolant temperature request
Unit: %





Air conditioner request (MIN)
Unit: %





Air conditioner request (MAX)
Unit: %





Evaporator temperature correction





During timer A/C mode or remote A/C mode, VCM determines a cooling fan speed by selecting the highest value from a coolant temperature request value and the sum of an air conditioner request value and an evaporator temperature correction value, as shown in the following table.
Coolant temperature request





Air conditioner request (MIN)





Air conditioner request (MAX)





Evaporator temperature correction










The cooling fan speed control reduces the cooling fan speed fluctuation by having a range for the operating conditions.





When the vehicle speed is 10km/h or less, VCM reduces the frequency of ON/OFF cycles by setting a period of time (A) in which the cooling fan continuously operates after the A/C compressor is turned
OFF.