Introduction to PWM Inverters

Now a days most of the inverters available in the market utilizes the PWM(Pulse Width Modulation) technology. The inverters based on PWM technology are superior in many factors compared to other inverters designed using conventional technologies. The PWM based inverters generally use MOSFETs in the output switching stage. In such cases the inverters
Introduction to PWM Inverters - schematic

are generally termed as PWM MOSFET inverters. The inverters based on PWM technology has a lot of protection and control circuits compared to the traditional inverters. PWM or Pulse width Modulation is used to keep the output voltage of the inverter at the rated voltage(110V AC / 220V AC) (depending on the country) irrespective of the output load. In a conventional inverter the output voltage changes according to the changes in the load. To nullify effect caused by the changing loads, the PWM inverter correct the output voltage according to the value of the load connected at the output. This is accomplished by changing the width of the switching frequency generated by the oscillator section. The AC voltage at the output depend on the width of the switching pulse. The process is achieved by feed backing a part of the inverter output to the PWM controller section (PWM controller IC). Based on this feedback voltage the PWM controller will make necessary corrections in the pulse width of the switching pulse generated at oscillator section. This change in the pulse width of the switching pulse will cancel the changes in the output voltage and the inverter output will stay constant irrespective of the load variations. This circuit senses the charging current of the battery in order to keep the charging current with in the rated value. A charging current lower or higher than the allowed range can reduce battery life. This circuit...

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