The IGBT drive circuit is one of the core components of power electronic systems, and its performance directly affects the switching loss, reliability, and overall efficiency of the IGBT and the entire system. The IGBT drive circuit must have two functions: one is to achieve electrical isolation between the control circuit and the gate of the driven IGBT; the other is to provide appropriate gate drive pulses. SHYSEMI presents several common forms of IGBT drive circuits, ranging from simple to complex, along with their advantages, disadvantages, and application scenarios.
1. Discrete components
The plug-in IGBT drive circuit composed of discrete components was widely used in IGBT-based equipment in the 1980s. The design and application of discrete component drive circuits were mainly constrained by the technical level and production process of electronic components at that time. However, with the development of large-scale integrated circuits and the emergence of surface mount technology, this type of discrete component plug-in drive circuit, due to its complex structure, low integration level, and high failure rate, has gradually been eliminated.
2.Integrated isolation drive chip
This is the most mainstream and recommended form for medium and high-power applications. It integrates the drive logic, powerful push-pull output stage, and complete protection circuit, and realizes electrical isolation between the input side (control side) and the output side (power side) through internal integrated isolation technology. Currently, isolation technologies such as optocouplers, magnetic isolation, and capacitive isolation have been developed to provide electrical isolation, ensuring safety and reliability, strong anti-interference ability, and allowing use in bridge circuits. "Dumb" applications significantly shorten the development cycle, improve product consistency, and are easy to use.
It can be applied in most medium and high-power fields, such as frequency converters, inverters, servo drives, new energy power generation, and electric vehicle control. This is the absolute mainstream choice in the industrial field.
3. Thick film drive circuit
The thick film drive circuit is a type of hybrid integrated circuit developed based on resistive and capacitive components and semiconductor technology. It uses thick film technology to fabricate patterned components and connecting wires on a ceramic substrate, integrating all the components of the drive circuit onto a single ceramic substrate as a whole component. The use of thick film drive circuits brings great convenience to design and wiring, improves the reliability of the entire machine and the consistency of mass production, and also enhances technical confidentiality. Current thick film drive circuits integrate many protection circuits and detection circuits.
4. Special integrated drive circuit
Some European and American manufacturers now use high-frequency isolation transformers in the design of IGBT drive circuits. Through high-frequency transformers to isolate the drive circuit power supply and signals, it enhances the reliability of the drive circuit and effectively prevents damage to the control circuit in case of faults in the main circuit. In practical applications, the failure rate of this type of drive circuit is very low, and high-power IGBT rarely has problems.
5. Modular drive board
The modular drive board integrates the isolation drive chip, gate resistor, filter capacitor, protection circuit, and even isolation power supply on a separate PCB board to form a "plug-and-play" drive module. Users do not need to design the drive circuit themselves; they only need to provide PWM signals and power supply to work. It is extremely convenient to use, maximizing the shortening of the development cycle.
The performance has been optimized and verified, with high reliability. It is suitable for prototype verification, scientific research experiments, small batches, and maintenance replacement, but the disadvantages are high cost, large size, and low flexibility. It may be difficult to integrate into compact products.
Therefore, for new project development, SHYSEMI suggests giving priority to using integrated isolation drive chips. Although it incurs slightly higher costs compared to the standalone solution in terms of the chip itself, it saves a significant amount of development and debugging time, reduces PCB space, and greatly enhances the reliability and security of the system. Overall, it offers the highest cost-effectiveness.