Phase-Shift Control of TMS320F280049 - Library Function Implementation

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Phase-Shift Control of TMS320F280049 - Library Function Implementation [Copy link]

Principle Introduction
The PWM module of F280049C is powerful and can easily realize phase shift control. This section mainly tells you how to use DSP programming to realize phase shift control. The following figure shows the phase shift control schematic diagram of the phase-shift full-bridge converter, where EPWM1A and EPWM1B are complementary signals with a duty cycle of 50%, and EPWM2A and EPWM2B are also complementary signals with a duty cycle of 50%. Phase shift control is achieved by controlling the phase shift angle of EPWM1A and EPWM2B.

As shown in the above figure, the control uses the counting time base of PWM1 as the reference signal. When the counter of PWM1 is zero (macro: EPWM_SYNC_OUT_PULSE_ON_COUNTER_ZERO), PWM1 sends out the synchronization pulse SyncOut, and configures the synchronization signal source of PWM2 to Syncln (macro: EPWM_SYNC_OUT_PULSE_ON_EPWMxSYNCIN). The relevant macro definitions are as follows:

typedef enum
{
//! sync pulse is generated by software
EPWM_SYNC_OUT_PULSE_ON_SOFTWARE = 0,
//! sync pulse is passed from EPWMxSYNCIN
EPWM_SYNC_OUT_PULSE_ON_EPWMxSYNCIN = 0,
//! sync pulse is generated when time base counter equals zero
EPWM_SYNC_OUT_PULSE_ON_COUNTER_ZERO = 1,
//! sync pulse is generated when time base counter equals compare B value.
EPWM_SYNC_OUT_PULSE_ON_COUNTER_COMPARE_B = 2,
//! sync pulse is disabled
EPWM_SYNC_OUT_PULSE_DISABLED = 4,
//! sync pulse is generated when time base counter equals compare D value.
EPWM_SYNC_OUT_PULSE_ON_COUNTER_COMPARE_C = 5,
//! sync pulse is disabled.
EPWM_SYNC_OUT_PULSE_ON_COUNTER_COMPARE_D = 6
}EPWM_SyncOutPulseMod

When the time base of PWM1 counts to zero, a synchronization pulse is sent. At this time, PWM2 receives the synchronization pulse and loads the value in the phase register TBPHS into the time base counter TBCTR. In other words, when PWM1 starts counting from zero, PWM2 starts counting from the value in the TBPHS register. Therefore, PWM1 and PWM2 realize phase shifting, and changing the value in the TBPHS register can change the phase shift angle of the phase shift control.