Electric Air Conditioning Compressor Control

WARNING: This page is about a different car, the 2021 Jaguar I-Pace, 2020 Jaguar I-Pace, and 2019 Jaguar I-Pace. However, it is still accessible from the selected car via links, so may be relevant.

The HVAC control module determines the amount of heat transfer required from the Air Conditioning (A/C) system by evaluating the heat transfer requests from:

The Integrated Control Panel (ICP) and the Rear Integrated Control Panel (RICP) (if equipped), for the passenger compartment cooling.
The Battery Energy Control Module (BECM) for the Electric Vehicle (EV) battery cooling.
ICP and the RICP (if equipped), for the passenger compartment heating.
From the heat transfer requests the HVAC activates the following:
Electric A/C compressor.
The front A/C isolation valve. Only energized when passenger compartment cooling is not require.
A/C isolation valve (quantity 5). The HVAC energizes the A/C isolation valves necessary for the required refrigerant flow.
EV battery cooler isolation valve. Only energized when cooling is requested from the Battery Energy Control Module (BECM) to cool the EV battery.
Electric drive cooler isolation valve. Only energized when the HVAC is recovering heat from the electric drive temperature control system to heat the passenger compartment.

The HVAC calculates the optimum speed required by the electric A/C compressor to produce the amount of heat transfer required. The HVAC also calculates the energy required to drive the electric A/C compressor.

NOTE: The HVAC control module adopts a different cooling strategy in high ambient temperature conditions. For the first 15 minutes of the vehicle operation, the front Air Conditioning (A/C) isolation valve is closed. This allows the passenger compartment temperature to be achieved as quickly as possible. When the passenger compartment has reached the target temperature, or 15 minutes has elapsed, the front A/C isolation valve opens to reconnect the Electric Vehicle (EV) battery cooler to the refrigerant circuit.

The HVAC calculates the required energy to drive the electric A/C compressor. It transmits the request through the High Speed (HS) Controller Area Network (CAN) power mode zero systems bus to the Powertrain Control Module (PCM). The PCM then calculates the total energy requirement and communicates with the BECM to determine the EV battery capability to provide the energy requirements through the HS CAN power mode zero systems bus.

The PCM responds with a signal of the EV battery power available to drive the electric A/C compressor. Provided there is sufficient power available, the final calculated electric A/C compressor speed remains the optimum speed. If the available power is less than required to drive the electric A/C compressor at the optimum speed. The HVAC reduces the final calculated electric A/C compressor speed to match the power available. The HVAC then transmits a drive request with the final calculated speed on the Local Interconnect Network (LIN) connection to the electric A/C compressor. A return signal on the LIN of actual speed allows the HVAC to have closed loop control of electric A/C compressor.

When climate control cooling is requested the HVAC maintains the A/C evaporator at an operating temperature that varies with the passenger compartment cooling requirements. If the requirement for cooled air decreases, the HVAC raises the A/C evaporator operating temperature. The HVAC decreases the speed of the electric A/C compressor, which reduces the flow of refrigerant. The HVAC closely controls the rate of temperature increase to avoid introducing moisture into the passenger compartment.

If the requirement for cooled air increases, the HVAC lowers the A/C evaporator operating temperature by increasing the speed of the electric A/C compressor. As a result, the electric A/C compressor increases the flow of refrigerant.

When climate control cooling of the passenger compartment is not required the HVAC stops the electric A/C compressor, unless other heat transfer request are received. If other heat transfer requests are received the HVAC energizes the front A/C isolation valve to stop the flow of refrigerant to the A/C evaporator.

The HVAC incorporates limits for the operating pressure of the refrigerant system. If the system approaches the high pressure limit, the electric A/C compressor speed is progressively reduced until the system pressure decreases. If the system falls below the low pressure limit, the electric A/C compressor is stopped, to avoid depletion of the lubricant in the electric A/C compressor.

For additional information, refer to: AIR CONDITIONING .

For additional information, Refer to:ELECTRIC VEHICLE BATTERY TEMPERATURE CONTROL .