IGBTs are used in VFDs (variable frequency drives) because they are more efficient than other switching devices, such as BJTs or SCRs, and they can switch faster than other semiconductor devices, allowing for more precise control of the motor. They also require less power to operate, making them more energy efficient. Finally, IGBTs are typically more reliable than other devices and can be used in harsher environments. This was brief introduction about why IGBT is used in VFD.
What is VFD (Variable Frequency Drive)?
First to know that, VFD (Variable Frequency Drives) are important components in any electrical system as they help regulate and control the speed and torque of an electrical motor. By changing the frequency of the alternating current, these drives can control the speed of the motor, allowing for greater precision, efficiency, and cost savings. VFDs also provide better protection for the motor, as they help reduce the amount of mechanical stress on the motor when it is running. Additionally, VFDs can help reduce energy consumption and save money by only running the motor at the required speed.
IGBTs (insulated-gate bipolar transistors) are a type of power semiconductor device used in VFDs (variable frequency drives). An IGBT works by combining the advantages of a MOSFET and a BJT, allowing it to switch faster and operate at higher voltages than a MOSFET while offering lower losses than a BJT. They are typically used in VFDs to control the current and voltage supplied to the motor, allowing for variable speed and torque control.
What is IGBT?
IGBT stands for insulated-gate bipolar transistor. It is a type of power semiconductor device that combines the advantages of a MOSFET and a BJT. IGBTs are used in variable frequency drives (VFDs) to control the current and voltage supplied to the motor, allowing for variable speed and torque control. They are faster and more efficient than traditional MOSFETs and BJTs, making them ideal for use in high-power applications.
It can be used to control the voltage and current supplied to the motor, allowing for variable speed and torque control. The IGBT can also protect the motor from overcurrent and overvoltage conditions.
An IGBT is typically made up of two layers of semiconductor material, a P-type layer and an N-type layer, which are separated by a thin layer of insulating material (usually silicon dioxide). When a current is passed between the two layers, the insulating material breaks down, allowing electrons to cross the gap and flow between the two layers. This creates a channel, which allows current to flow. The current can then be regulated by adjusting the voltage applied to the gate of the transistor.
Why is IGBT used in VFD?
IGBTs are used in variable frequency drives (VFDs) to control the current and voltage supplied to the motor, allowing for variable speed and torque control. The IGBT behaves like a switch and can be used to control the voltage and current supplied to the motor, allowing for variable speed and torque control. The IGBT can also protect the motor from overcurrent and overvoltage conditions.
Step 1: The AC power is converted to DC power using an AC/DC converter.
Step 2: The DC power is stored and converted into a sinusoidal waveform using a DC link.
Step 3: The frequency controller modulates the frequency and voltage of the output using the sinusoidal waveform.
Step 4: The IGBT is used to control the current and voltage supplied to the motor, allowing for variable speed and torque control.
Step 5: The DC power is then converted back into AC power and outputted to the motor.
Let us understand more explanation step by step
- As we know VFD is used to control motor speed by variations in voltage and frequency. IGBT as switch acts so fast by creating on off pulsating waveforms. Switching rate of IGBT is controllable based on output you require. If gate opens and closes slowly, then you will get low frequency and vice versa. This is the basic principle of VFDS of controlling very fast motor.
- The voltage drop and conduction loss are lesser in IGBT as compared to other semiconductors.
- IGBT has more low RON (on-state resistance) than equivalent MOSFET. Therefore I2R drop agaist bipolar structure for given switching current is also low. That’s why as compare to MOSFET, it has low on-state resistance, which enhances current rating.
- IGBT is good for motor harmonic and noise reduction due to high switching frequencies which minimizes switching losses. That’s why IGBT has fast switching speed.
- VFD IGBT Turn on speed is less than 400 nanoseconds and turn off speed is less than 500 nano seconds. You can imagine how it is fast.