Ripple Current Reduction of DC Link Electrolytic Capacitors by Switching Pattern Optimisation

The use of electrolytic capacitors in automotive applications is critical. High ambient temperatures lower lifetime and reliability, while further disadvantages arise from costs and installation space. The presented work shows a method to reduce the capacitor ripple current, which accordingly leads to a reduced demand on DC link electrolytic capacitors. The proposed method is based on applying an optimised switching pattern to the power transistors. Thereby, the ripple current can be reduced to approximately one third compared to conventional PWM signals. The optimisation is also described graphically, and measurements verify the practicability