Multi-electrode ablation systems, methods, and controllers are described. In one example, a multi-electrode ablation system generally includes a power supply and a controller. The power supply is configured to be coupled to a plurality of electrodes for delivering power to the electrodes. The controller is operable to compare a measured temperature at each electrode to a desired temperature to thereby define a temperature difference for each electrode. The controller is operable to determine, based on the temperature difference, a desired power for each electrode, compare the desired power of one of the electrodes to an actual power delivered to the one of the electrodes to define a power difference, and adjust the actual power delivered by the power supply to the one of the electrodes based on the power difference.