Indirect matrix converter (IMC) typically requires zero current commutation (ZCC) at its rectifier stage. This paper proposes a fixed slope carrier modulation for IMC. According to homothetic triangle, the modulating functions in the inverter stage are scaled by the rectifier stage to accomplish ZCC. Compared with space vector modulation (SVM) or variable slope carrier modulation, the fixed slope carrier PWM benefits in implementation and reliability. The feasibility of the proposed method is verified by experimental results.