This paper presents two modulation methods for current source inverter both in SVPWM point of view: Discontinuous-PWM (DPWM) and Continuous-SVPWM (CSVPWM), and proposed the third method Pulse-Width-Amplitude-Modulation (PWAM), also based on SVPWM theory. Different switching sequences of DPWM are proposed and compared. The Double Fourier Series equations and integration limits for both DPWM and PWAM are given. A THD and switching loss comparison has been conducted between all methods. Simulation results are given for all methods to demonstrate the theory analysis.