Abstract: This research investigated influence of load type, operational mode and modulation index on the SHEM current source inverter (CSI). For this purpose an inverter designed and constructed which can be operated in single and three phase mode with any number of harmonics elimination capability. In current source inverters with resistive- inductive loads, over voltages in output voltage waveform appears. To remove this over voltage, we used a capacitor. In this study the effect of this capacitor on the output voltage has been investigated. The result of varying of modulation index shows that the amplitude of the system`s harmonics varied with their variation, which can cause undesired effects on the supplied devices with inverter. The effect of these parameters on the CSI, simulated with PSPICE. The comparisons have been done on our laboratorial system outputs, with simulated results. Then it has been shown that experimental results verify the simulation results.