In-depth analysis and comparison are made of the difference and relation between different closed-loop control strategies for LC-filtered voltage source inverters（VSI）from the perspective of the controller coordinate system，control loop structure and controller design.And it is pointed out that adoption of a separate resonant controller without output voltage decoupling achieves better control effects，but instability of the system will occur when there is one.Meanwhile，the difference between single-voltage-loop control and dual-closed-loop control is discussed.Finally，a VSI controller for use in uninterrupted power supply with motor load is designed.Experimental results show that，by using the design methods and conclusions under discussion，the process of designing the controller for VSI can be greatly shortened while achieving satisfactory performance.