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PWM IR2110 Half-Bridge duty cycle

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I consider about driving transducer. I want to drive 60W transducer. And for this operation, I want to use 70W-80W transformator. But how can I be sure that my transducer will not take upper 60W power. Some frequency such as resonance frequency, transducer may take maximum power,right? So maybe my transformer will also be damaged. Second question : is it possible that high voltages on the transducer side effects my H-bridge power circit? if it is possibble, how can I recover my power circuit?
Click to expand...
If you are feeding 100 watts, you cant take out 110 watts. Voltage and current vary, but their product remains the same.
In your hbridge voltage is 300V. If you feed 90 watts input to bridge, it will be drawing 90/300=0.3A =300mA.
If you put a resistor of 3.3 ohm in series to source of lower FET so that all current pass through it. 0.3 A passing through 3.3 ohm resistor will produce 0.3 x 3.3 = 0.99 volts. By monitoring this voltage, maximum power allowed can be controlled.
PIC can sample this voltage through ADC module and stop or reduce PWM. If your transducer is china made, dont drive it at maximum capacity. It also need good contact with other surface to pass vibrations generated. Put a good quality 100mA fuse in sries with transducer.(600v x 0.1A =60 Watts). Further you can monitor DC bus voltage and output current/voltage. There are loss of power in terms of heat etc, you may get 10% less power in output.
 

Dear ALERTLINKS,
Coming back to you.
Please tel me why when I apply the gate signals to the MOSFETs, these last become hot and I do not get anything at the inverter output, maybe I have to add resistors on collectors or somethings else.
 

ALERTLINKS said:
If you are feeding 100 watts, you cant take out 110 watts. Voltage and current vary, but their product remains the same.
In your hbridge voltage is 300V. If you feed 90 watts input to bridge, it will be drawing 90/300=0.3A =300mA.
If you put a resistor of 3.3 ohm in series to source of lower FET so that all current pass through it. 0.3 A passing through 3.3 ohm resistor will produce 0.3 x 3.3 = 0.99 volts. By monitoring this voltage, maximum power allowed can be controlled.
PIC can sample this voltage through ADC module and stop or reduce PWM. If your transducer is china made, dont drive it at maximum capacity. It also need good contact with other surface to pass vibrations generated. Put a good quality 100mA fuse in sries with transducer.(600v x 0.1A =60 Watts). Further you can monitor DC bus voltage and output current/voltage. There are loss of power in terms of heat etc, you may get 10% less power in output.
Click to expand...

dear ALERTLINKS,

you are right on
ALERTLINKS said:
If you put a resistor of 3.3 ohm in series to source of lower FET so that all current pass through it. 0.3 A passing through 3.3 ohm resistor will produce 0.3 x 3.3 = 0.99 volts. By monitoring this voltage, maximum power allowed can be controlled.
Click to expand...

but if we connect a load to the output of H-bridge, for this time all current will not pass through Rsense resistor, so on the operaiton we couldnt catch output power information correctly...
 

if we connect a load to the output of H-bridge, for this time all current will not pass through Rsense resistor
Click to expand...
38_1322040216.png

Return of capacitor is included. Sense output is after filtering by capacitor averaging pulses.
 

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