Power management is critical to power-constrained real-time systems. In this paper, we present a dynamic power management algorithm for real-time heterogeneous systems. Unlike other approaches that focus on the tradeoff between power and performance, our algorithm maximizes power utilization and performance. Our algorithm considers a dynamic environment, allowing for changes in the available energy and adapting system parameters such as operating voltage, frequency, and the number of processors. In our algorithm, the power management problem is divided into three subproblems: i) initial power allocation to minimize wasted energy and avoid the undersupplied power situation, ii) system parameter computation based on the allocated power that maximizes the performance for a given power budget, and iii) dynamic update of the power and system parameters in run time. The simulation results of the algorithm for a satellite system using three heterogeneous processors is presented.