2022-07-27 09:07 PM
(Environment)
MC_SDK 5.Y.3 + STM32CubeMX 6.3.0 with HAL + IAR EWARM 8.5
(Hardware)
custom board based on F446RE + custom power board(3-shunt) + Low Voltage BLDC motor with Encoder
(Control Mode)
Speed Control
(What I found)
In "parameters_conversion.h", there is defined MAX_MODULE as follows:
=================================================
/* MMI Table Motor 1 MAX_MODULATION_100_PER_CENT */
#define MAX_MODULE 32767
=================================================
If this 100% modulation is used, there might be some moments where low-side duty becomes close to zero (less than dead time). Then the boot capacitors might not be charged properly.
Solved! Go to Solution.
2022-08-10 12:49 AM
Hello,
100% is not a default value, increasing the PWM frequency you will notice that Max Modulation Index will decrease.
The occurrence of having high side closed shouldn't happen during a long period (long enough have an impact on boot strap capacitor charge...), but if needed, you can change MAX_MODULE define.
Best regards.
GMA
2022-08-02 08:28 AM
Hello,
Thank you for your question.
May I propose you to have a look at this application note?
Considerations on bootstrap circuitry for gate drivers - Application note
On the other hand, investigations have to be done in order to cover all your points...
Best regards.
GMA
2022-08-07 08:59 PM
Thank you for your reply.
I read that application note - I understood a few factors(dutycycle time, capacitance, etc) should be considered for proper operations.
MCSDK looks like using 100% modulation as default. Does ST recommend to appropriately change it(directly modifying #define MAX_MODULE 32767 in "parameters_conversion.h" while not supported at workbench tools)?
2022-08-10 12:49 AM
Hello,
100% is not a default value, increasing the PWM frequency you will notice that Max Modulation Index will decrease.
The occurrence of having high side closed shouldn't happen during a long period (long enough have an impact on boot strap capacitor charge...), but if needed, you can change MAX_MODULE define.
Best regards.
GMA
2022-08-10 01:35 AM
Thank you for your answer !
Regards,
THA.1