CCS/TMS320F28027F: Documentation on Over modulation

Ibraheem,

Due to US holidays, most of the experts are out of office. Please expect delay in response. Sincere apology for inconvenience.

Hi,

Have you checked the document shown below?

You can find details about overmodulation on page 228.

www.ti.com/.../spruhj1h.pdf

Let me know if you still have questions.

Best,

John

Thank you, John

I have gone through the documentation, but I couldn't find any details on the current reconstruction configuration parameters. For example in the following code, 

// Initialize and setup the 100% SVM generator
svgencurrentHandle = SVGENCURRENT_init(&svgencurrent, sizeof(svgencurrent));

// setup svgen current
{
float_t minWidth_microseconds = 1.0;
uint16_t minWidth_counts = (uint16_t) (minWidth_microseconds
* USER_SYSTEM_FREQ_MHz);
float_t fdutyLimit = 0.5
- (2.0 * minWidth_microseconds * USER_PWM_FREQ_kHz * 0.001);
_iq dutyLimit = _IQ(fdutyLimit);

SVGENCURRENT_setMinWidth(svgencurrentHandle, minWidth_counts);
SVGENCURRENT_setIgnoreShunt(svgencurrentHandle, use_all);
SVGENCURRENT_setMode(svgencurrentHandle, all_phase_measurable);
SVGENCURRENT_setVlimit(svgencurrentHandle, dutyLimit);
}

what does minWidth_microseconds represent? Tweaking it affects what part of the performance?

What is the significance of the following lines of code in mainISR as if it's trying to adjust the sampling point in the next cycle or something else. I found if I add these lines of code, the current controller seriously goes unstable when SVM enters in overmodulation region as I am using 100% overmodulation unless I remove these lines of code.   

SVGENCURRENT_IgnoreShunt_e ignoreShuntNextCycle =
SVGENCURRENT_getIgnoreShunt(svgencurrentHandle);
SVGENCURRENT_VmidShunt_e midVolShunt = SVGENCURRENT_getVmid(
svgencurrentHandle);

// Set trigger point in the middle of the low side pulse
HAL_setTrigger(halHandle, ignoreShuntNextCycle, midVolShunt); 

my Main ISR function is below

interrupt void mainISR(void)
{
uint32_t timer0Cnt;
uint32_t timer1Cnt;

SVGENCURRENT_MeasureShunt_e measurableShuntThisCycle = SVGENCURRENT_getMode(
svgencurrentHandle);

// read the timer 1 value and update the CPU usage module
timer1Cnt = HAL_readTimerCnt(halHandle, 1);
CPU_USAGE_updateCnts(cpu_usageHandle, timer1Cnt);

// read the timer 0 value and update the FEM
timer0Cnt = HAL_readTimerCnt(halHandle, 0);
FEM_updateCnts(femHandle, timer0Cnt);
FEM_run(femHandle);

// acknowledge the ADC interrupt
HAL_acqAdcInt(halHandle, ADC_IntNumber_1);

// convert the ADC data
HAL_readAdcData(halHandle, &gAdcData);

// run the current reconstruction algorithm
SVGENCURRENT_RunRegenCurrent(svgencurrentHandle,
(MATH_vec3*) (gAdcData.I.value));

gIavg.value[0] += (gAdcData.I.value[0] - gIavg.value[0]) >> gIavg_shift;
gIavg.value[1] += (gAdcData.I.value[1] - gIavg.value[1]) >> gIavg_shift;
gIavg.value[2] += (gAdcData.I.value[2] - gIavg.value[2]) >> gIavg_shift;

if (measurableShuntThisCycle > two_phase_measurable)
{
gAdcData.I.value[0] = gIavg.value[0];
gAdcData.I.value[1] = gIavg.value[1];
gAdcData.I.value[2] = gIavg.value[2];
}

// run the controller
CTRL_run(ctrlHandle, halHandle, &gAdcData, &gPwmData);

// run the PWM compensation and current ignore algorithm
SVGENCURRENT_compPwmData(svgencurrentHandle, &(gPwmData.Tabc),
&gPwmData_prev);

// write the PWM compare values
HAL_writePwmData(halHandle, &gPwmData);

{
/* SVGENCURRENT_IgnoreShunt_e ignoreShuntNextCycle =
SVGENCURRENT_getIgnoreShunt(svgencurrentHandle);
SVGENCURRENT_VmidShunt_e midVolShunt = SVGENCURRENT_getVmid(
svgencurrentHandle);

// Set trigger point in the middle of the low side pulse
HAL_setTrigger(halHandle, ignoreShuntNextCycle, midVolShunt); */
}

// setup the controller
CTRL_setup(ctrlHandle);

// read the timer 1 value and update the CPU usage module
timer1Cnt = HAL_readTimerCnt(halHandle, 1);
CPU_USAGE_updateCnts(cpu_usageHandle, timer1Cnt);

// run the CPU usage module
CPU_USAGE_run(cpu_usageHandle);

return;
} // end of mainISR() function

Looking forward to your reply,

Thank you

Ibraheem

You might take a look at the lab10a chapter of the instaSPIN lab user's guide. The value of the "minWidth_microseconds" is dependent on the ADC sampling time and headband value of FET and gate driver, it should be greater than the sum of both values.

As replied to another thread you posted, set the USER_MAX_VS_MAG_PU to a value below 0.5777, or limit the PWM duty directly.

e2e.ti.com/.../3577068