Adaptive control of multi-compartment transport refrigeration system

1. A multi-compartment transport refrigeration system comprising:

a compressor having a suction port and a discharge port, the compressor suction port coupled to a compressor inlet path;

a heat rejecting heat exchanger downstream of the compressor discharge port;

a first evaporator expansion device downstream of the heat rejecting heat exchanger;

a first evaporator having a first evaporator inlet coupled to the first evaporator expansion device and a first evaporator outlet coupled to the compressor inlet path, the first evaporator associated with a first compartment of a container, the first compartment cooled to a first temperature;

a second evaporator expansion device downstream of the heat rejecting heat exchanger;

a second evaporator having a second evaporator inlet coupled to the second evaporator expansion device and a second evaporator outlet coupled to the compressor inlet path, the second evaporator associated with a second compartment of the container, the second compartment cooled to a second temperature greater than the first temperature; and

a controller for controlling the first evaporator expansion device in response to a first superheat setpoint and controlling the second evaporator expansion device in response to a second superheat setpoint, the controller adjusting the second superheat setpoint in response to the second temperature and the first temperature;

wherein the controller adjusts the second superheat setpoint by determining an adjusted second superheat setpoint equal to an original second superheat setpoint plus a difference between the second temperature and the first temperature.

2. The multi-compartment transport refrigeration system of claim 1 further comprising:

a first return air temperature sensor to generate the first temperature; and

a second return air temperature sensor to generate the second temperature.

3. The multi-compartment transport refrigeration system of claim 1 wherein:

the controller controls the second evaporator expansion device in response to the second superheat setpoint and a sensed second superheat at the second evaporator outlet.

4. A method of operating a multi-compartment transport refrigeration system, the method comprising:

operating a first evaporator and first evaporator expansion device to cool a first compartment of a container to a first temperature, a first evaporator outlet coupled to a compressor inlet path;

operating a second evaporator and second evaporator expansion device to cool a second compartment of the container to a second temperature greater than the first temperature, a second evaporator outlet coupled to the compressor inlet path;

controlling the first evaporator expansion device in response to a first superheat setpoint and controlling the second evaporator expansion device in response to a second superheat setpoint, the controller adjusting the second superheat setpoint in response to the second temperature and the first temperature;

wherein adjusting the second superheat setpoint includes determining an adjusted second superheat setpoint equal to an original second superheat setpoint plus a difference between the second temperature and the first temperature.

5. The method of claim 4 wherein:

controlling the second evaporator expansion device includes determining an error between the second superheat setpoint and a sensed second superheat at the second evaporator outlet.

6. The method of claim 4 wherein:

controlling the second evaporator expansion device is in response to the second superheat setpoint and a sensed second superheat at the second evaporator outlet.

7. The multi-compartment transport refrigeration system of claim 1 wherein:

the compressor comprises a motor;

the system further comprising a generator configured to power the motor.