TIM1 Dead time not working according manual

[franz2]

I use TIM1 as 3 Phase PWM for motor control. I need to adjust the dead time. But the dead time is not according the manual.

My code for dead time:

 TIM_BDTRInitStruct.OSSRState = LL_TIM_OSSR_ENABLE;

 TIM_BDTRInitStruct.OSSIState = LL_TIM_OSSI_DISABLE;

 TIM_BDTRInitStruct.LockLevel = LL_TIM_LOCKLEVEL_OFF;

 TIM_BDTRInitStruct.DeadTime = 1;

 TIM_BDTRInitStruct.BreakState = LL_TIM_BREAK_ENABLE;

 TIM_BDTRInitStruct.BreakPolarity = LL_TIM_BREAK_POLARITY_HIGH;

 TIM_BDTRInitStruct.BreakFilter = LL_TIM_BREAK_FILTER_FDIV1;

 TIM_BDTRInitStruct.BreakAFMode = LL_TIM_BREAK_AFMODE_INPUT;

 TIM_BDTRInitStruct.Break2State = LL_TIM_BREAK2_DISABLE;

 TIM_BDTRInitStruct.Break2Polarity = LL_TIM_BREAK2_POLARITY_HIGH;

 TIM_BDTRInitStruct.Break2Filter = LL_TIM_BREAK2_FILTER_FDIV1;

 TIM_BDTRInitStruct.Break2AFMode = LL_TIM_BREAK_AFMODE_INPUT;

 TIM_BDTRInitStruct.AutomaticOutput = LL_TIM_AUTOMATICOUTPUT_ENABLE;

 LL_TIM_BDTR_Init(TIM1, &TIM_BDTRInitStruct);

f PWM is 20kHz

This setting I changed in the SFRs Watch window:

When I set DTG to 0: dead time is 9.3us

When I set DTG to 127: dead time is 9.5us

When I set DTG to 240: dead time is 4.7us

When I set DTG to 255: dead time is 3.4us

I need a dead time of approximate 0.2us.

How I can implement shorter dead time. Accorrding manual I must be possible. Somewhere must be an error between reality and manual.

Franz

[waclawek.jan]

Which STM32?

Read out and check/post TIM registers content, and screenshot of the respective waveform.

What is the TIM input frequency?

JW

[franz2]

Dear JW

I use Nucleo-G474RE Board

CH 3 has duty fact 25%

Scope with dead time setting = 1 --> exactly code attached 2 days back

Franz

[waclawek.jan]

Registers content you've posted display a stopped timer (TIM_CR1.CEN=0) disabled all channels in TIM_CCER and zero TIM_BDTR, i.e. no dead time. It's hard to judge whether the waveform is OK from a random set of registers.

JW

[franz2]

Sorry here the running state. The scope diagram is equal and SW is unchanged.

[waclawek.jan]

OK and is there any change if you don't enable the breaks, i.e. set *only* MOE in BDTR (and then try to change DTG)?

JW