SLLU336A May   2021  – January 2022 MCT8316A

 

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4.3.13 Limiting and regulating supply power

MCT8316A provides options to limit and regulate supply power. This feature can be utilized in battery powered motor driver applications such as cordless vacuum cleaners, power tools etc.

Follow below steps to limit supply power. In this mode, supply power is only limited to reference power and not actively regulated.

Step 1: Configure CONST_POWER_MODE to "Power limit control".

Step 2: Configure MAX_POWER. This sets the maximum power that MCT8316A can draw from the DC input supply at 100% duty command.

Step 3: Configure CONST_POWER_LIMIT_HYST. This sets the hysteresis band for the power reference. For example, if MAX_POWER is set to 25W and device draws 25W at 100% duty command and CONST_POWER_LIMIT_HYST is set to 5%, input power will still be limited to 25W at 95% speed command.

CONST_POWER_LIMIT_HYST can be configured in applications where there are oscillations in speed around MAX_POWER. If speed oscillation is observed, it is recommended to increase the CONST_POWER_LIMIT_HYST.

Step 4: MCT8316A uses the same PI controller parameters as in the speed loop mode. Kp and Ki coefficients are configured through SPD_POWER_KP and SPD_POWER_KI. Tuning SPD_POWER_KP and SPD_POWER_KI is experimental. It is recommended to manually tune both parameters till the desired results are achieved.

Follow below steps to regulate supply power. In this mode, supply power is always actively regulated.

Step 1: Configure CLOSED_LOOP_MODE to "Power loop".

Step 2: Configure CONST_POWER_MODE to "Closed loop power control".

Step 3: Configure MAX_POWER. This sets the maximum power that MCT8316A can draw from the DC input supply at 100% duty command.

For example, if MAX_POWER is configured to 25W, MCT8316A will draw 12.5W from power supply at 50% duty command.

Step 4: MCT8316A uses the same PI controller parameters as in the speed loop mode. Kp and Ki coefficients are configured through SPD_POWER_KP and SPD_POWER_KI. Tuning SPD_POWER_KP and SPD_POWER_KI is experimental. It is recommended to manually tune both parameters till the desired results are achieved.