SPRUJ53B April 2024 – September 2024 TMS320F28P550SJ , TMS320F28P559SJ-Q1
A popular power topology that makes use of phase-offset between modules is shown in Figure 19-70. This system uses three PWM modules, with module 1 configured as the sync source. To work, the phase relationship between adjacent modules must be F = 120°. This is achieved by setting the sync receiver TBPHS registers 2 and 3 with values of 1/3 and 2/3 of the period value, respectively. For example, if the period register is loaded with a value of 600 counts, then TBPHS (sync receiver 2) = 200 and TBPHS (sync receiver 3) = 400. Both sync receiver modules are synchronized to the sync source module 1.
This concept can be extended to four or more phases, by setting the TBPHS values appropriately. The following formula gives the TBPHS values for N phases:
Where:
N = number of phases
M = PWM module number
For example, for the 3-phase case (N = 3), TBPRD = 600,
TBPHS(3,2) = (600/3) ˟ (2 - 1) = 200 (that is, Phase value for Sync Receiver module 2)
TBPHS(3,3) = 400 (that is, Phase value for Sync Receiver module 3)
Figure 19-71 shows the waveforms for the configuration in Figure 19-70.