A prototype 35We, JP‐8 fueled, soldier‐wearable power system for the DARPA Palm Power program has been developed and tested by Sunpower. A hermetically‐sealed 42We Sunpower Free‐Piston Stirling Engine (FPSE) with integral linear alternator is the prime mover for this system. To maximize system efficiency over a broad range of output power, a non‐dissipative, highly efficient electronic control system which modulates engine output power by varying piston stroke and converts the AC output voltage of the FPSE into 28Vdc for the Palm Power end user, has been designed and demonstrated as an integral component of the Palm Power system. This paper reviews the current status and progress made in developing the control electronics for the Palm Power system, in addition to describing the operation and demonstrated performance of the engine controller in the context of the current JP‐8 fueled Palm Power system.