short circuit with HVP-MC3PH

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short circuit with HVP-MC3PH

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lethuer
Contributor V

Hi,

is it possible to get a short circuit while using the eFlexPWM independant block and powering the HVP-MC3PH board with a high input voltage 300V DC ?

With the independant block I'm principle able to generate signals for driving both igbt from one phase.

For example igbt high side (PWM0) and igbt low side (PWM1) are turned on at the same time.

This you can measure at the J10 connector.

Unbenannt.PNG

If I now connect a high voltage to the board the +15V voltage is available which is VCC for the 3 phase driver.

Unbenannt.PNG

So there would be a short circuit or is there any further protection ?

The FNB41560 has a short-circuit protection (PSP), but with that you detect an existing short circuit at pin10 (CSC).

I want to know if it is possible to turn on both igbt from one phase at the same time.

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dumitru-daniel_
NXP Employee
NXP Employee

Hi lethuer2‌,

With "independent pwm block" you have the option to control each of the PWM signals independently therefore based on your duty cycle algorithm generation you may end up with both output signals to be ON or OFF in the same time.

The IC FNB41560 can't block these signals to be applied to the IGBTs, it can only detect a short circuit and raise a fault output signal to the MCU. In that case you should monitor that signal and raise an interrupt when that happens in order to stop the PWM generation.

In order to avoid any potential damage due to the concurrent PWM signals going HIGH in the same time, you could use the eFlexPWM_Complementary_Output Simulink Block. This block is using only one Duty Cycle input and all the time the pairs of PWM signals are generated in anti-phase.  Also, you have the option to insert deadtime between PWM HIGH and LOW signals in order to allow sufficient time to shut down the IGBTs.

Anyhow, prior to applying high voltage, you should test for the corner cases the PWM signals making sure you do not open the upper and lower IGBTs in the same time.

Hope it helps!

Daniel