STM32H725ZGT6 Full Bridge Converter with TIM1 or TIM8

[smal]

Hello

I would like to build a full bridge converter according to attached topology picture. The signals for controlling the switches should be like in the picture pwm_scheme. The frequency should be 500KHz. How to configure TIM1 or TIM8 on STM32H725ZGT6 to achieve this?

To control the current i1 with lowering the duty cycle of the PWM which input is better to use: ETR or BKIN?

Best regards

Simon

[mƎALLEm]

Hello ​@smal and sorry for the late reply,

In your case you need to use PWM output with complementary channel for example using CH1 and CH1N outputs by inserting a dead time and duty cycle set at 50%.

ALL OFF→ is the dead time insertion.

This is an example (inspired from NUCLEO-H743ZI\Examples\TIM\TIM_ComplementarySignals) of code to configure TIM1 to generate complementarity PWM signal outputs on CH1 (PE9) and CH1N (PE8):

      __HAL_RCC_GPIOE_CLK_ENABLE();
    /**TIM1 GPIO Configuration
    PE8     ------> TIM1_CH1N
    PE9     ------> TIM1_CH1
    */
    GPIO_InitStruct.Pin = GPIO_PIN_8|GPIO_PIN_9;
    GPIO_InitStruct.Mode = GPIO_MODE_AF_PP;
    GPIO_InitStruct.Pull = GPIO_NOPULL;
    GPIO_InitStruct.Speed = GPIO_SPEED_FREQ_HIGH;
    GPIO_InitStruct.Alternate = GPIO_AF1_TIM1;
    HAL_GPIO_Init(GPIOE, &GPIO_InitStruct);

  /* Select the Timer instance */
  TimHandle.Instance = TIM1;

  TimHandle.Init.Prescaler         = <define your prescaler>;
  TimHandle.Init.Period            = <define a period value>;
  TimHandle.Init.ClockDivision     = 0;
  TimHandle.Init.CounterMode       = TIM_COUNTERMODE_UP;
  TimHandle.Init.RepetitionCounter = 0;
  if(HAL_TIM_PWM_Init(&TimHandle) != HAL_OK)
  {
    /* Initialization Error */
    Error_Handler();
  }

  /*##-2- Configure the PWM channels #########################################*/ 
  /* Common configuration for all channels */
  sPWMConfig.OCMode       = TIM_OCMODE_PWM1;
  sPWMConfig.OCPolarity   = TIM_OCPOLARITY_HIGH;
  sPWMConfig.OCNPolarity  = TIM_OCNPOLARITY_HIGH;
  sPWMConfig.OCIdleState  = TIM_OCIDLESTATE_SET;
  sPWMConfig.OCNIdleState = TIM_OCNIDLESTATE_RESET;  
  sPWMConfig.OCFastMode   = TIM_OCFAST_DISABLE;  

  /* Set the pulse value for channel 1 */
  sPWMConfig.Pulse = <pulse value = period value / 2 to obtain 50% of duty cycle>;  
  if(HAL_TIM_PWM_ConfigChannel(&TimHandle, &sPWMConfig, TIM_CHANNEL_1) != HAL_OK)
  {
    /* Configuration Error */
    Error_Handler();
  }

    /* Set the Break feature & Dead time */
  sBreakConfig.BreakState       = TIM_BREAK_ENABLE;
  sBreakConfig.DeadTime         = <set your dead time>;
  sBreakConfig.OffStateRunMode  = TIM_OSSR_ENABLE;
  sBreakConfig.OffStateIDLEMode = TIM_OSSI_ENABLE;
  sBreakConfig.LockLevel        = TIM_LOCKLEVEL_1;  
  sBreakConfig.BreakPolarity    = TIM_BREAKPOLARITY_HIGH;
  sBreakConfig.BreakFilter      = 0;
  sBreakConfig.AutomaticOutput  = TIM_AUTOMATICOUTPUT_ENABLE;
  if(HAL_TIMEx_ConfigBreakDeadTime(&TimHandle, &sBreakConfig) != HAL_OK)
  {
    /* Configuration Error */
    Error_Handler();
  }

  /*##-3- Start PWM signals generation #######################################*/ 
  /* Start channel 1 */
  if(HAL_TIM_PWM_Start(&TimHandle, TIM_CHANNEL_1) != HAL_OK)
  {
    /* Starting Error */
    Error_Handler();
  }
  /* Start channel 1N */
  if(HAL_TIMEx_PWMN_Start(&TimHandle, TIM_CHANNEL_1) != HAL_OK)
  {
    /* Starting Error */
    Error_Handler();
  }

What is needed from you is to define 3 parameters:

• The frequency of the signal which is defined mainly by TimHandle.Init.Period based on the timer clock.
• The duty cycle that should be set at 50% which is defined by sPWMConfig.Pulse.
• The dead time: defined by sBreakConfig.DeadTime.

This is what you should get at CH1 and CH1N:

Each channel i.e. CH1 and CH1N will control respectively a couple of the MOSFETS (T1, T4) and (T2, T3).

Hope that helps.