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A vapor compression refrigeration cycle system includes a compressor and an electronic expansion valve connected between first and second refrigerant ports of a compressor. An expansion valve controller is configured to control a flow of refrigerant through the expansion valve in response to a super

A vapor compression refrigeration cycle system includes a compressor and an electronic expansion valve connected between first and second refrigerant ports of a compressor. An expansion valve controller is configured to control a flow of refrigerant through the expansion valve in response to a superheat temperature of the refrigerant. The controller is configured to execute a first control algorithm until a local maximum of the superheat temperature occurs, and then to execute a second control algorithm.

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1. A system comprising: a compressor comprising a refrigerant inlet port and a refrigerant outlet port;an expansion valve interoperably coupled to the compressor;a controller interoperably coupled to the compressor and the expansion valve;wherein the controller is configured to: determine whether th

1. A system comprising: a compressor comprising a refrigerant inlet port and a refrigerant outlet port;an expansion valve interoperably coupled to the compressor;a controller interoperably coupled to the compressor and the expansion valve;wherein the controller is configured to: determine whether the compressor is operating;responsive to a determination that the compressor is operating, execute a startup-control algorithm to adjust a flow rate of refrigerant through the expansion valve;determine an occurrence of a local maximum of a superheat temperature;responsive to a determination that the local maximum of the superheat temperature has occurred, initiate a steady-state control algorithm; andexecute a transition-control algorithm prior to execution of the steady-state control algorithm, the transition-control algorithm brings the superheat temperature from a value at an end of the startup-control algorithm to within a temperature range at which the steady-state control algorithm is configured to maintain the superheat temperature during execution of the steady-state control algorithm. 2. The system of claim 1, wherein the local maximum of the superheat temperature occurs when a first derivative of the superheat temperature changes from positive to negative and a current iteration time is greater than a predetermined startup time detected by the controller. 3. The system of claim 1, wherein the controller is configured to return to the startup-control algorithm in an event that the expansion valve reaches a zero flow condition after the controller initiates the steady-state control algorithm. 4. The system as claim 1, wherein, when executing the startup-control algorithm, the controller opens the expansion valve at a rate proportional to a second derivative of the superheat temperature. 5. The system of claim 1, wherein the steady-state control algorithm is a fuzzy-logic algorithm. 6. The system of claim 1, wherein the steady-state control algorithm is a proportional-integral-derivative control algorithm. 7. A controller comprising: a memory configured to store operating instructions of a control algorithm;an input interface configured to receive an input indicative of a superheat temperature of a refrigerant;a processor interoperably coupled to the memory and the input interface;in response to the input, the processor is configured to: execute the operating instructions and issue a control signal to control a stepper motor;determine whether a compressor is operating;responsive to a determination that the compressor is operating, execute a startup-control algorithm to adjust a flow rate of refrigerant through an expansion valve;determine occurrence of a local maximum of the superheat temperature; andresponsive to a determination that the local maximum of the superheat temperature has occurred, initiate a steady-state control algorithm; andwherein the controller is configured to execute, a transition-control algorithm prior to execution of the steady-state control algorithm that brings the superheat temperature from a value at an end of the startup-control algorithm to within a temperature range at which the steady-state control algorithm is configured to maintain the superheat temperature during execution of the steady-state control algorithm. 8. The controller of claim 7, wherein the local maximum of the superheat temperature occurs when a first derivative of the superheat temperature changes from positive to negative and a current iteration time is greater than a predetermined startup time detected by the controller. 9. The controller of claim 7, wherein the controller is configured to return to the startup-control algorithm in an event that the expansion valve reaches a zero flow condition after the controller executes the steady-state control algorithm. 10. The controller of claim 7, wherein, when executing the startup-control algorithm, the controller opens the expansion valve at a rate proportional to a second derivative of the superheat temperature. 11. The controller of claim 7, wherein the steady-state control algorithm is a fuzzy-logic algorithm. 12. The controller of claim 7, wherein the steady-state control algorithm is a proportional-integral-derivative control algorithm.