Texas Instruments 28xxx, TMS320x28xx manual Controlling a 3-Phase Interleaved DC/DC Converter

Models: 28xxx TMS320x28xx

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3.8Controlling a 3-Phase Interleaved DC/DC Converter

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Controlling a 3-Phase Interleaved DC/DC Converter

Figure 3-12. Timing Waveforms Associated With Phase Control Between 2 Modules

FFFFh

TBCTR[0-15]

 

 

 

Master Module

600

600

TBPRD

 

 

 

 

0000

 

 

 

CTR = PRD

 

 

time

(SycnOut)

 

 

 

 

 

FFFFh

TBCTR[0-15]

Phase = 120°

 

 

Φ2

 

Slave Module

 

600

600

TBPRD

 

200

200

TBPHS

 

0000

 

SyncIn

time

 

3.8Controlling a 3-Phase Interleaved DC/DC Converter

A popular power topology that makes use of phase-offset between modules is shown in Figure 3-13. This

system uses three PWM modules, with module 1 configured as the master. To work, the phase relationship between adjacent modules must be F = 120°. This is achieved by setting the slave 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 (slave 2) = 200 and TBPHS (slave 3) = 400. Both slave modules are synchronized to the master 1 module.

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:

TBPHS(N,M) = (TBPRD/N) x (—1)

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) x (2-1) = 200 (i.e., Phase value for Slave module 2) TBPHS(3,3) = 400 (i.e., Phase value for Slave module 3)

Figure 3-14shows the waveforms for the configuration in Figure 3-13.

SPRU791D–November 2004–Revised October 2007

Applications to Power Topologies

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Texas Instruments 28xxx, TMS320x28xx manual Controlling a 3-Phase Interleaved DC/DC Converter