Modular multilevel converters based on power semiconductor devices, including the insulated gate bipolar transistors (IGBTs) and power diodes, are key components of modern high voltage direct current transmission (HVDC) systems. In practical applications, the loss and junction temperature rise caused by the switching transient of IGBTs and diodes is the major concern. In this work, a joint simulation approach for transient analysis of MMCs under different control methods is developed, and the influence of control methods on the loss as well as junction temperatures of the IGBTs in MMC systems is investigated. The results indicate that though the pulse width modulation (PWM) control yields better waveform of the electric current with lower harmonics, due to its higher switching frequency, this method exhibits worse power loss and junction temperature when compared against the nearest level modulation (NLM) method.