Abstract: This paper briefly introduces the principles of IGBT drive protection circuits, analyzes in detail the characteristics of various commonly used ICBT integrated drive modules, and compares them. Keywords : Insulated Gate Bipolar Transistor; Integrated Drive Module; Drive Protection Circuit 0 Introduction With the development of power electronics technology towards high power, high frequency, and modularity, Insulated Gate Bipolar Transistors (IGBTs) have been widely used in switching power supplies, frequency converters, motor control, and other fields requiring fast speed and low loss. IGBTs are composite fully controllable voltage-driven power electronic devices, combining the advantages of MOSFETs and GTRs: high input impedance, low drive power, low on-state voltage drop, high operating frequency, and fast dynamic response. Currently, IGBTs with voltages ranging from 500 to 3000V and 800 to 1800A have become the preferred power devices for high-power switching power supplies and other power electronic devices due to their high voltage resistance and high power characteristics. 1 Principles of Drive Protection Circuits Since it is a voltage-controlled device, the ICBT can be turned on or off simply by controlling its gate voltage, and a relatively low on-state voltage drop is maintained when it is turned on. Studies have shown that the safe operating area and switching characteristics of IGBTs change with the driving circuit. Therefore, the driving protection circuit is crucial to ensure the reliable operation of IGBTs. The principles of IGBT driving protection circuits are as follows: (1) Strong dynamic driving capability, capable of providing driving pulses with steep leading and trailing edges to the gate; (2) Capable of providing a suitable forward gate voltage (12-15V) when turned on, and sufficient reverse turn-off gate voltage (-5V) when turned off; (3) Minimal input-output delay time to improve working efficiency; (4) Sufficiently high input-output electrical isolation characteristics to insulate the signal circuit from the gate driving circuit; (5) Sensitive protection capability in the event of short circuits or overcurrents. Currently, in practical applications, dedicated IGBT driving modules that integrate driving and protection functions are commonly used. 2 Integrated Driving Modules To solve the problem of reliable IGBT driving, manufacturers around the world have released numerous integrated IGBT driving modules. Examples of typical integrated driver modules include the EXB series from Fuji Electric Corporation (Japan), the M57 series from Mitsubishi Electric Corporation (Mitsubishi Electric Corporation), the GH series from Sansha Electric Corporation (Sansha Electric Corporation), the TR series from International Rectifier Corporation (USA), the UC37 series from Unitrode Corporation (Unitrode Corporation), and the HL series from China. The following are some typical integrated driver modules. 2.1 Analysis of the EXB841 Module The EX841 high-speed driver module is a 15-pin single-in-line package (SILB) structure. It uses a high-isolation voltage optocoupler for signal isolation. Its internal structure is shown in Figure 1. Its operating frequency can reach 40 kHz, and it can drive IGBTs up to 400 M/600 V and 300 A/1200 V. Its isolation voltage can reach 2500 AC/min. The operating power supply is an independent 20±1V power supply. It contains an internal 5V voltage regulator circuit to provide a +15V drive voltage to the IGBT gate and a -5V bias voltage for reliable turn-off. When a 10 mA current flows through pins 15 and 14, pin 3 outputs a high level, turning on the IGBT within 1 μs. When no current flows through pins 15 and 14, pin 3 outputs a low level, turning off the IGBT. If the IGBT exits saturation due to short-circuit current during turn-on, Vce rises rapidly, pin 6 is left floating, and the potential at pin 3 begins to soft-drop approximately 3.5 μs after the short circuit. A typical application diagram of the EXB841 is shown in Figure 2. Capacitors C1 and C2 are used to absorb high-frequency noise. Simultaneously with the output pulse at pin 3, the voltage between the collector and emitter of the IGBT is detected by the fast diode D1. When Vce > 7V, the overcurrent protection current controls the operational amplifier, causing it to output a soft-turn-off signal, reducing the output level of pin 3 to 0 within 10 μs. Because the EXB841 lacks overcurrent latching functionality, an external overcurrent protection circuit is added. Once an overcurrent occurs, an overcurrent protection signal can be output via an external optocoupler TLP521. After a certain delay to prevent malfunction and ensure soft shutdown, the signal is then locked by a trigger to achieve protection. Disadvantages: The EXB841 overcurrent protection threshold is too high, operating when Vce > 7V, which is far greater than the saturation voltage drop; it has a blind zone; it can only provide a 5V bias voltage for normal shutdown, making shutdown unreliable at high switching frequencies and heavy loads; it lacks overcurrent latching functionality, and its soft shutdown process during short-circuit protection is interrupted by the input shutdown signal. 2.2 Analysis of the M57962L Module The M57962AL is a 14-pin single-row direct-access thick-film driver module, and its internal structure is shown in Figure 3. It consists of an optocoupler, interface circuit, detection circuit, timing reset circuit, and gate turn-off circuit. It boasts high driving power and can drive IGBT modules of 600A/600V and 400A/1200V series. The M5796AL features high-speed input/output isolation, with an insulation voltage reaching AC 2500V/min; its input level is compatible with TTL levels, suitable for microcontroller control; it has internal timing logic short-circuit protection circuit and delay protection characteristics; it uses a dual power supply method, which, compared to the EXB841, requires an additional power supply, but allows for more reliable IGBT switching. A typical application diagram is shown in Figure 4. When the drive signal passes through pins 14 and 13, it is transmitted to the power amplifier stage via the M57962AL's built-in interface circuit after high-speed optocoupler isolation. A +15V gate-opening voltage and a -10V gate-off voltage are generated at pin 5 of the M57962AL, driving the IGBT to switch on and off. When a 7V voltage is detected at pin 1, the module determines that the circuit is short-circuited and immediately outputs a shutdown signal through the optocoupler, causing pin 5 to output a low level. This puts the G-E terminals of the IGBT in a negative bias, reliably shutting it off. Simultaneously, an error signal is output, causing the fault output terminal (pin 8) to go low, thus driving the external protection circuit. After a delay of 2-3 seconds, if a high level is detected at pin 13, the M57962AL resumes operation. Zener diode DZ1 is used to prevent D1 from breaking down and damaging the M57962AL. Rg is a current-limiting resistor, and DZ2 and DZ3 act as amplitude limiters to ensure reliable switching. Comparison: Compared to the EXB841, the M57962AL requires dual power supplies (+15V, -10V), resulting in a more complex external circuit. The M57962AL's ability to output a -10V bias voltage ensures reliable IGBT turn-off. Furthermore, the M57962AL features automatic overcurrent protection lockout and externally adjustable soft-turn-off time, unlike the EXB841, which does not. Therefore, the M57962AL is safer and more reliable than the EXB841. 2.3 Analysis of the HL402 Module: The HL402 is a 17-pin single-in-line package with a high-speed optocoupler featuring an internal electrostatic shielding layer for signal isolation. It boasts strong anti-interference capabilities, fast response, and high isolation voltage. It provides dual protection for the IGBT through gate voltage reduction and soft turn-off. Simultaneously with soft turn-off and gate voltage reduction, it outputs an alarm signal to enable protection against pulse blocking or main circuit interruption. It outputs a high-amplitude drive voltage, with a positive drive voltage of 15-17V and a negative bias voltage of 10-12V, thus it can be used to directly drive IGBTs with capacities of 400A/600V and below 300A/1200V. The HL402 structure is shown in Figure 5. In Figure 5, VL1 is an electrostatically shielded optocoupler used to isolate it from the input signal. Due to its electrostatic shielding, it significantly improves the HL402's common-mode interference immunity. In Figure 5, U1 is a pulse amplifier, S1 and S2 amplify the drive pulse power, and U2 is a gate voltage comparator. Under normal conditions, since the IGBT collector voltage VCE input at pin 9 is not higher than the reference voltage VREF of U2, U2 does not flip, and S3 is not turned on. Therefore, the drive pulse signals input from pins 17 and 16 are not blocked after being shaped by S2. The drive pulse, amplified by S2 and S2, is provided to the IGBT to turn it on or off. Once the IGBT desaturates, the collector voltage input at pin 9 is used to turn it on or off. Furthermore, the collector voltage sampling signal VCE input at pin 9 is higher than the reference voltage VREF of U2, causing comparator U2 to flip and output a high level, turning on S3. Zener diode DZ2 then reduces the gate voltage VGE output by the driver to 10V. At this time, after the gate voltage comparator U2 flips for the set time, the soft-turn-off timer U3 outputs a positive voltage, turning on S4 and soft-turning the gate voltage down to the IGBT's gate-emitter threshold voltage, providing a negative drive voltage to ensure reliable IGBT turn-off. A typical application diagram of HL402 is shown in Figure 6. In the actual circuit, C1, C2, C3, and C4 should be installed as close as possible to pins 2, 1, and 4 of the H1402. To avoid high-frequency coupling and electromagnetic interference, the leads from the HL402 output to the gate and emitter of the driven IGBT must use twisted-pair or shielded coaxial cable, with a lead length not exceeding 1m. The leads from pins 9 and 13 to the IGBT collector must be routed separately and must not be twisted with the gate and emitter leads to avoid cross-interference. Optocoupler L1 can input a pulse blocking signal; when L1 is on, the HLA02 output pulse is immediately blocked to -10V. Optocoupler L2 provides a soft-shutdown alarm signal; it activates optocoupler L3 simultaneously with the actuator's soft shutdown, providing a gate voltage drop alarm signal. During use, by adjusting the values ​​of capacitors C5, C6, and C7, the gate voltage drop delay time, gate voltage drop time, and soft-shutdown slope time in the protection waveform can be adjusted to appropriate values. In high-frequency applications, to prevent the IGBT from being subjected to multiple overcurrent surges, the signal between input pins 16 and 17 can be blocked after the optocoupler L2 outputs several or one alarm signal. In summary, among the three, the M57962AL and HL402 use black ceramic substrate packaging, while the EXB841 uses yellow copper-clad laminate packaging. Due to the superior heat dissipation and frequency characteristics of ceramic substrates compared to copper-clad laminates, the HL402 boasts the best load capacity and heat dissipation. Combined with its optimized layout design, it achieves the highest operating frequency and the most comprehensive protection features among the three. In contrast, neither the EXB841 nor the M57962AL offers gate voltage reduction protection. Furthermore, the HL402 and M57962AL provide externally placed negative bias Zener diodes, offering both flexibility and improved reliability. The EXB841's Zener diode, located internally, frequently fails due to its damage. Therefore, the HL402's superior performance compensates for the shortcomings of the other two. 2.4 Analysis of the GH-039 Module The GH-039 adopts a single-in-line 12-pin package, featuring low power consumption and minimal heat generation during operation, allowing for high-density use. It operates on a single power supply, incorporates a high-speed optocoupler, and includes a soft-shutdown overcurrent protection circuit. In addition to blocking its own output, the overcurrent protection also provides a synchronous output for user use. It can directly drive IGBT modules below 300A/600V. Its internal structure is shown in Figure 7. Its working principle is similar to the EXB and M57 series modules, and will not be elaborated further here. However, unlike the EXB and M57 series modules, this module already contains an optocoupler for sending alarm or action signals after protection. Therefore, it does not require an external optocoupler like the EXB and M57 series modules, making it more convenient. Its performance is superior to the EXB and M57 series modules in terms of protection performance. Regarding reliability, because the GH-039 is powered by a single power supply, it cannot provide a negative bias voltage, which may lead to unreliable IGBT turn-off. Compared to HL402, CH-039's protection functions are incomplete; like EXB841 and M57962AL, it lacks gate voltage reduction protection. Therefore, the GH-039 driver module also has defects. A typical wiring diagram for GH-039 is shown in Figure 8. The operating power supply VCC is 26V; to maintain voltage stability, the filter capacitor should be installed and used as close as possible to the GH-039 module, and its capacitance value should not be less than 10μF; high-quality capacitors should be selected. The diode D1 connected in series between pin 12 of GH-039 and the collector of the IGBT should be an ultra-fast recovery diode, and its reverse withstand voltage should not be lower than the rated voltage between the collector and gate of the IGBT. To prevent malfunction of the opto-isolator connected to the overcurrent protection terminal, a 100Ω resistor should be connected in series between D1 and pin 12 of GH-039. D2 connected between pin 10 and pin 12 should be an ultra-fast recovery diode, and its reverse withstand voltage can be lower than the collector-emitter withstand voltage of the IGBT. 2.5 Other Drivers (1) IR Series Drivers The IR series drivers are mainly designed for driving bridge arm circuits. The chip has 14 pins and is packaged in DIP. It has overcurrent protection and undervoltage protection functions. In particular, it has a bootstrap floating power supply, which greatly simplifies the design of the drive power supply. Multiple power devices can be driven with only one power supply. Its disadvantage is that it cannot generate negative bias voltage. When used to drive bridge circuits, due to the Miller effect, interference is easily generated on the gate at the turn-on and turn-off times, causing a short circuit in the bridge arm. In addition, the IR series drivers adopt a non-isolated driving method. When the power devices in the main circuit are damaged, high voltage may be directly connected to the driving devices, causing damage to the drive module and the front-end circuit. (2) UC37 Series Drivers This series of drivers is generally used by pairing two chips, UC3726 and UC3727. Its operating frequency is relatively high, but a pulse transformer needs to be added between the two chips, which brings inconvenience to the use and design of the circuit. Therefore, this series of drivers has not been widely promoted in China. 3 Conclusion Through the above analysis and comparison, the following conclusions can be drawn. (1) All six series of drivers can drive and protect IGBTs; (2) EXB841 has a simple peripheral circuit and only requires a single power supply. It is the earliest ICBT driver module to enter the Chinese market. It is technically mature and widely used; (3) EXB841 and M57962AL can apply a negative voltage to the gate during IGBT turn-off, which further ensures the reliable turn-off of IGBTs; (4) EXB841, M57962AL, GH-039 and HL402 are all ICBT driver modules with built-in desaturation and overcurrent protection functions for IGBTs. They all perform protection functions by detecting the voltage between the collector and emitter of the IGBT. However, EXB841, M57962AL and GH-039 can only perform soft turn-off protection when the ICBT is desaturated or overcurrent. HL402 can not only perform soft turn-off protection, but also gate voltage reduction protection. Therefore, HL402 is the IGBT driver with the strongest protection function, the most reasonable protection function design, and the most convenient protection performance among the four; (5) When driving the same number of IGBT power switches, the IR series requires the least amount of working power, but it does not have negative bias voltage, which can easily cause bridge arm short circuits. It is suitable for low power drive applications.