Single Phase Bridge DC-AC Inverter with R Load

A single phase bridge DC-AC inverter is shown in Figure 8. The analysis of the single phase DC-AC inverters is done taking into account following assumptions and conventions:

• • The current entering node a in Figure 8 is considered to be positive.

• The switches S₁, S₂, S₃, and S₄ are unidirectional, i.e. they conduct current in one direction.

When the switches S₁ and S₂ are turned on simultaneously for a duration , the input voltage V_in appears across the load and the current flows from point a to b . If the switches S₃ and S₄ are turned on for a duration , the voltage across the load is reversed and the current through the load flows from point b to a . The voltage and current waveforms across the resistive load are shown in Figure 9 . The instantaneous output voltage can be expressed in Fourier series as

                                                             (11)

Due to the square wave symmetry along the x-axis (as seen in Figure 9 ), both a_o and a_n are zero , and b_n is obtained as

                                               (12)

Substituting the value of b_n from equation 12 into equation 11 gives

                                                                                        (13)

The instantaneous current through the resistive load is given by

                                                                                    (14)

Figure 8 : Full bridge DC-AC inverter with resistive load