Methods and systems are provided for adjusting a ratio of friction to regenerative brake effort and running an electric air conditioning compressor to collect condensed water for water injection into an engine. In one example, a method may include adjusting the air conditioning compressor load of the electric AC system and the ratio of friction to regenerative brake effort based on a water level in a water storage tank of the water injection system. Further, the method may include directing energy from regenerative braking to a battery and/or to the AC compressor in response to the battery state of charge.

An air conditioner for a vehicle has a compressor, a radiator, a first pressure reducer, a gas-liquid separator, a second pressure reducer, an exterior heat exchanger, an intermediate pressure refrigerant passage, a switching device, and a controller. The controller operates the switching device to switch from a refrigerant circuit of a two-stage compression mode to a refrigerant circuit of a single-stage compression mode when a compressor stop signal is output in the two-stage compression mode. The single-stage compression mode is a mode that blocks at least a flow of an intermediate-pressure refrigerant into the intermediate pressure refrigerant passage and makes refrigerant remained in the intermediate pressure refrigerant passage to flow out of the intermediate pressure refrigerant passage. The controller stops the compressor after controls the compressor to continue operating for a specified time in the single-stage compression mode. The controller restarts the compressor when the compressor stop signal is canceled.

A refrigeration system for a vehicle includes a compressor in fluid communication with a condenser and an evaporator. The compressor includes a variable speed motor and employs capacity modulation using refrigerant injection. The condenser and the evaporator include variable speed fans. The refrigeration system includes a battery to supply power to the refrigeration system. The battery is charged by one or more sources of power including the vehicle. The refrigeration system includes a control module configured to monitor one or more characteristics of the battery and to control one or more operating parameters of one or more of the compressor, the condenser, and the evaporator based on the one or more characteristics of the battery.

A method for controlling torque of an air conditioner compressor is disclosed. In one example, the air conditioner compressor is a variable displacement compressor. The method may provide smooth transitions between different air conditioner compressor torques.

A method for controlling an air conditioner compressor of a vehicle is disclosed. The method includes adjusting a displacement command in response to an error between an expected air conditioner evaporator temperature and a measured or inferred air conditioner evaporator temperature, the displacement command is further adjusted via adding a value to the displacement command based on desired air conditioner evaporator temperature, the value determined apart from the error between the expected air conditioner evaporator temperature and the measured or inferred air conditioner evaporator temperature.

A method and an apparatus for controlling a compressor are provided. The method includes measuring a vehicle speed, an engine speed, a position value of an accelerator pedal, and an external air temperature and comparing the vehicle speed with a predetermined speed. A basic operation rate of the compressor is then determined based on the engine speed and the position value of the accelerator pedal when the vehicle speed is equal to or less than the predetermined speed. A final operation rate of the compressor is determined based on the external air temperature and the determined basic operation rate and the compressor is operated based on the determined final operation rate.

A method for controlling transitions between activating and deactivating a vehicle air conditioner compressor is disclosed. In one example, displacement of the air conditioner compressor is adjusted before the air conditioner is coupled to an energy conversion device. The method may provide smooth transitions between different air conditioner compressor control modes.

A method of operating a transport refrigeration system is provided. The method includes electrically powering a first plurality of components of a first refrigeration unit and a second plurality of components of a second refrigeration unit, wherein electrically powering comprises operating a prime mover and an electric generation device. The method also includes monitoring a plurality of operating parameters of the first refrigeration unit. The method further includes monitoring a plurality of operating parameters of the second refrigeration unit. The method yet further includes calculating a combined power load of the first refrigeration unit and the second refrigeration unit. The method also includes comparing the combined power load to a maximum available power of the prime mover.