This paper presents a junction temperature controller which increases the reliability of IGBT power modules in power electronic applications without affecting the demanded output power. Power electronic applications have to deal with varying load conditions. These varying load conditions lead to temperature swings which lead to mechanical stress of common IGBT power modules. At low load conditions the switching losses are increased by increasing the switching frequency. This leads to reduced temperature swings resulting in a higher reliability. The functionality of the control system is verified on a three phase two level inverter connected to a passive load.