Gate driver outputs "Zero amps"

I am working on 3-phase inverter circuit.

I am using IR2110 to switch high and low side MOSFETs. Each MOSFET's gate is connected to the high/low side pins of driver IC. When I apply the PWM input to the gate driver, the MOSFET switches and the circuit works fine. I connected to the load (motor), the motor runs OK.

When I try to check the gate current of the MOSFET (that is, from driver IC output pin to the MOSFET's gate), I notice that zero amps is flowing to the gate. But how?

I am biasing the gate driver IC with 12 volts and I used a 30 ohm resistor in the gate terminal,

I = 12V/30 = 400mA

But when I measure the current it shows "0 amp". I also changed the value from 30 ohms to 10 ohms. But no change, so I think I am wrong somewhere.
Please correct me.
I attached the image which is taken from tamid blog, Which works good (Gate driver circuit)

Hi,

How do you measure it? DVM?
What setup? DC_average?
Where do you think the current should flow?
* The gate is high resistance. The capacitance causes only relatively small AC current.
* then there is only a 1k resistor...

--> average DC: I_DC = 12V * duty_cycle / (1k + 10R)

Klaus

But when I measure the current it shows "0 amp". I also changed the value from 30 ohms to 10 ohms. But no change, so I think I am wrong somewhere.

Click to expand...

Look at the circuit diagram closely; the gate is a small capacitor.

To turn on, the gate must have some charge and voltage. Like a capacitor, the charge flows only when you turn on and off.

If you want to turn off the mosfet fast, you must pump in the required charge in a short time. That means a large current flows for a short time. Same is the case when you want to turn off the MOSFET.

Because the current lasts for only a short time, it is tricky to measure. It is more convenient to use an oscilloscope to see the voltages.

You cannot measure the transient currents with a DVM.

That is a current will flow to gate in vera short time , to charge the mosfet gate cap.Right?
- Then how much current will flow to gate in short time. I'm my circuit for 12volt
- So i could use 10ohm or even lower one.

Not only is the gate current transient, it is reversing with
a net zero charge across the cycle and on average.

So the DMM reading is right, as far as it goes.

and here is a sim in ltspice...you run it and you see the current of you press ALT-left click