Application and Improvement of IGBT Driver Chip IXDN404

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Application and Improvement of IGBT Driver Chip IXDN404 [Copy link]

Abstract: The characteristics and performance of IXYS's high-power IGBT driver chip IXDN404 are introduced. On this basis, according to the actual requirements of IGBT driving, a simple and effective driving circuit with overcurrent protection and slow shutdown function is designed, and the actual circuit diagram and driving waveform are given. Keywords: IGBT; driving and protection; IXDN404 Introduction Insulated gate transistor IGBT is a composite device with the fastest development and great prospects in recent years. It has been widely used in switching power supplies, UPS, inverters, frequency converters, AC servo systems, DC/DC conversion, welding power supplies, induction heating devices, household appliances and other fields due to its comprehensive performance advantages. However, in the process of its use, many problems that affect its application have been found, one of which is the gate driving and protection of IGBT. At present, the driving circuits used more in China include the EXB series produced by Fuji, the M579 series produced by Mitsubishi, and the MC33153 produced by MOTOROLA. These drive circuits have their own characteristics and can realize the drive and protection of IGBT, but they also have their application limitations, such as low drive power, long delay time, imperfect protection circuit, application frequency limit, etc. This paper, based on the IGBT driver chip IXDN404 produced by IXYS, introduces its characteristics and parameters, designs the actual drive and protection circuit, and through experimental verification, it can meet the actual drive of IGBT and the protection requirements of implementing slow shutdown strategy in overcurrent and short circuit. 1 Introduction to IXDN404 driver chip IXDN404 is a high-speed CMOS-level IGBT/MOSFET driver produced by IXYS. Its characteristics are as follows: --High output peak current can reach 4A; --Operating voltage range 4.5V～25V; --Drive capacitance 1800pF<15ns; --Low transmission delay time; --Rise and fall time matching; --Output high impedance; --Low input current; --Each chip contains two drive channels; --Input can be TTL or CMOS level. Its circuit schematic is shown in Figure 1, and its main electrical parameters are listed in Table 1. Table 1 Main electrical parameters of IXDN404

Symbol	Parameter	Test conditions	Minimum value	Typical value	Maximum value	Unit
Vih	Input threshold voltage, logic 1	Null	3.5	Empty	Empty	V
Vil	Input threshold voltage, logic 0	Empty	Empty	Empty	0.8	V
Voh	Output voltage, logic 1	Output voltage, logic 0	Empty	Vcc－0.025	Empty	Empty	V
Vol	Output voltage, logic 0	Empty	Empty	Empty	0.025	V
Ipeak	Peak output current	Vcc=18V	4	Empty	Empty	A
Idc	Continuous output current	Vce=18V	Empty	Empty	1	A
tr	Rise time	C1=1800pF Vcc=18V	11	12	15	ns
tf	Fall time	C1=1800pF Vcc=18V	12	14	17	ns
tond	Rise time delay	C1=1800pF Vcc=18V	33	34	38	ns
toffd	Fall time delay	C1=1800pF Vcc=18V	28	30	35	ns
Vcc	Supply voltage	Null	4.5	18	25	V
Icc	Supply current	Vin=+Vcc	Empty	Empty	10	μA

2 Application and improvement of driver chip Figure 2 shows the practical IGBT driving and protection circuit composed of IXDN404. This circuit can drive 1200V/100A IGBT. The signal delay time of the driving circuit does not exceed 150ns, so the switching frequency can be as high as 100kHz. It can be applied to power circuits such as high-frequency switching power supplies, inverters, and frequency converters controlled by DSP. According to the user manual of IXYS, IXDN404 can only provide driving pulses of 0~+Vcc. On this basis, we add a 5.1V Zener diode Z3 to achieve a -5V bias voltage; the Zener voltage is used to power the optocoupler 6N137 and the inverter CD4069, saving a driving power supply; the gate voltage reduction and slow shutdown protection circuit are added to realize the protection function of the IGBT; the gate voltage reduction and slow shutdown circuit are realized by controlling the IXDN404 power supply voltage Vcc, which is obviously different from the pre-stage voltage reduction control method of other protection circuits. The working principle is introduced below. 2.1 Normal turn-on process When the control signal is high, the fast optocoupler 6N137 is turned on, after a first-stage inversion, input IXDN404, output +15V pulse, and the IGBT is turned on normally. At the same time, since the output of the optocoupler is inverted, V4 is cut off, V5 is turned on, C1 is charged by the power supply, and the voltage of C1 will not exceed 9V. This is because when the IGBT is turned on normally, Vces is not higher than 3V, the diode D2 is turned on, the potential of point A is clamped at 8V, and the voltage drop of the resistor R10 is added. The potential of point C is close to 9V. Z1 is off, V2 is off, V1 is on, and the potential at point B is close to 20V; Z2 is off, V3 is off, and the potential at point D is close to the potential at point B. The charging time constant of C1 is τ1=R9×C1=2.42μs, and the time for C1 to charge to 9V is t1=τ1ln[20/(20-19)]=1.45μs (1) 2.2 Normal shutdown process When the control signal is low level, the optocoupler outputs high level, and the inverting output is low level. Since the output pulse of IXDN404 is -5V due to the clamping of Z3, the IGBT is normally shut down. At this time, V4 is on, V5 is off, and the potential at point C remains at 9V; Z1 is off, V2 is off, V1 is on, and the potential at point B is close to 20V; Z2 is off, V3 is off, and the potential at point D is close to the potential at point B. Figure 2 2.3 Protection process Assume that the IGBT is already turned on, and the potentials of each point are as described in 2.1. When the circuit is overcurrent, the IGBT exits the resistance area due to the large current, Vces rises, the diode D2 is cut off, and the clamping effect of point A on the capacitor C1 disappears; the potential of point C rises from 9V, and at the same time Z1 reversely breaks down, V2 is turned on, V1 is cut off, and the potential of point B is determined by the voltage division of R1 and Rc and the internal resistance of the IXDN404 chip, clamped at 15V, and the gate voltage drops to 10V. The drop in gate voltage can effectively suppress the fault current and increase the short-circuit allowable time. The gate voltage reduction operation time is t2=τ1ln(20-0)/(20-13)=1.09μs (2) If the circuit returns to normal during this period, D2 is turned on, point A continues to clamp, V2 is turned off, V1 is turned on, and the circuit returns to the state described in 2.1. If D2 is still in the off state, that is, the fault current still exists, the voltage at point C continues to rise, and after t2 time it rises to 13V, Z2 reversely breaks down, V3 is turned on, capacitor C2 discharges through resistor R12, the potentials at points D and B drop at the same time, and the IGBT gate voltage gradually drops, realizing the slow shutdown process, avoiding the overvoltage caused by normal shutdown of large current. The slow shutdown process time is t3, which is determined by C2 and R12. Since the operating voltage range of IXDN404 is 4.5～25V, τ2=R12×C2=4.84μs, we know that t3=τ2ln(15/4.5)=5.83μs (3) In addition, during the IGBT turn-on process, if the diode D2 cannot be turned on in time, it will cause the protection circuit to malfunction. Therefore, a fast diode should be selected for D2. The protection circuit action time can also be extended by appropriately increasing the Z1 voltage regulator value and increasing the resistor R9 to increase the C1 charging time constant. However, this is inconsistent with the rapidity of the protection action. In specific applications, a compromise should be made based on the actual circuit requirements and the characteristics of the power device. 2.4 Some explanations 1) In order to maximize the driving power, this circuit uses two input and output in parallel. The maximum driving peak current can reach 8A. This peak current is generated by the instantaneous discharge of capacitor Cc; 2) The output of the optocoupler 6N137 is the input inversion, and the IXDN404 is the same phase input and output. To ensure the correct control logic, an inverter is required in the middle. The IXDI404 with inversion can also be used; 3) In Figure 2, an optocoupler can be added at point E, and its output can be sent to the control logic as a short-circuit protection signal to block the PWM signals of this and other channels to ensure the safety of the main circuit; 4) The IXDN404 drive circuit is very sensitive to pulse signals. In actual operation, the connection should be as short as possible. The output should be connected to the IGBT with a twisted pair. The components used in the circuit can also be patch-type, which not only reduces the size of the drive circuit but also improves the working stability. Figure 3 shows the gate drive signal of the measured IGBT, where channel 1 is the input control signal and channel 2 is the output drive signal. The IGBT used is the Fairchild HGTG18N120BND. It can be seen from the figure that the delay time of the drive circuit is only 100ns. Figure 3 (d) is a protection waveform simulating the overcurrent of the IGBT. First, the gate voltage is reduced, then it is slowly turned off, and finally, due to the low voltage power supply, the output drive voltage of the IXDN404 is locked at about -2V. 3 Conclusion The IGBT drive and protection circuit composed of IXDN404 can meet the IGBT drive requirements, and its characteristics can be summarized as follows: --Drive power supply +20V single-channel power supply, drive gate voltage +15V~-5V; --The maximum drive peak current can reach 8A, which meets the requirements of high-power IGBT drive; --The circuit signal delay time is short, and the operating frequency can reach 100kHz or higher, which can meet the needs of most circuits; --It can realize overcurrent protection and gate voltage reduction slow shutdown function; --The circuit cost is relatively low. In summary, this drive protection circuit is a low-cost, high-performance IGBT drive circuit.2 Normal shutdown process When the control signal is low level, the optocoupler outputs high level, and the inverting output is low level. Since the output pulse of IXDN404 is -5V due to the clamping of Z3, the IGBT is normally shut down. At this time, V4 is turned on, V5 is turned off, and the potential at point C remains at 9V; Z1 is turned off, V2 is turned off, V1 is turned on, and the potential at point B is close to 20V; Z2 is turned off, V3 is turned off, and the potential at point D is close to the potential at point B. Figure 2 2.3 Protection process Assume that the IGBT has been turned on, and the potentials of each point are as described in 2.1. When the circuit is overcurrent, the IGBT exits the resistance zone due to the large current, Vces rises, the diode D2 is turned off, and the clamping effect of point A on the capacitor C1 disappears; the potential of point C rises from 9V, and at the same time Z1 reverses and breaks down, V2 is turned on, V1 is turned off, and the potential of point B is determined by the voltage division of R1 and Rc and the internal resistance of the IXDN404 chip, clamped at 15V, and the gate voltage drops to 10V. The reduction of the gate voltage can effectively suppress the fault current and increase the short-circuit allowable time. The gate voltage reduction operation time is t2=τ1ln(20-0)/(20-13)=1.09μs (2) If during this period of time, the circuit returns to normal, D2 is turned on, point A continues to clamp, V2 is turned off, V1 is turned on, and the circuit returns to the state described in 2.1. If D2 is still in the off state, that is, the fault current still exists, the voltage at point C continues to rise, and after t2 time it rises to 13V, Z2 reverses and breaks down, V3 turns on, capacitor C2 discharges through resistor R12, the potentials at points D and B drop at the same time, and the IGBT gate voltage gradually drops, realizing the slow shutdown process, avoiding the overvoltage caused by normal shutdown of large current. The slow shutdown process time is t3, which is determined by C2 and R12. Since the operating voltage range of IXDN404 is 4.5~25V, τ2=R12×C2=4.84μs, it can be known that t3=τ2ln(15/4.5)=5.83μs (3) In addition, during the IGBT turn-on process, if diode D2 cannot be turned on in time, it will cause malfunction of the protection circuit. Therefore, D2 should choose a fast diode. It can also extend the protection circuit action time by appropriately increasing the Z1 voltage regulator value and increasing the resistor R9 to increase the C1 charging time constant. But this is contradictory to the rapidity of the protection action. In specific applications, a compromise should be made according to the actual circuit requirements and the characteristics of the power device. 2.4 Some explanations 1) In order to maximize the driving power, this circuit uses two inputs and outputs in parallel. The maximum driving peak current can reach 8A. This peak current is generated by the instantaneous discharge of capacitor Cc; 2) The output of the optocoupler 6N137 is the input inversion, and the IXDN404 is the same phase input and output. To ensure the correct control logic, a first-level inverter is required in the middle. The IXDI404 with inversion can also be used; 3) In Figure 2, an optocoupler can be added at point E, and its output can be sent to the control logic as a short-circuit protection signal to block the PWM signals of this and other channels to ensure the safety of the main circuit; 4) The IXDN404 drive circuit is very sensitive to pulse signals. In actual operation, the connection should be as short as possible. The output should be connected to the IGBT with a twisted pair. The components used in the circuit can also be patch-type, which not only reduces the size of the drive circuit but also improves the working stability. Figure 3 shows the gate drive signal of the measured IGBT, where channel 1 is the input control signal and channel 2 is the output drive signal. The IGBT used is the Fairchild HGTG18N120BND. It can be seen from the figure that the delay time of the drive circuit is only 100ns. Figure 3 (d) is a protection waveform simulating the overcurrent of the IGBT. First, the gate voltage is reduced, then it is slowly turned off, and finally, due to the low voltage power supply, the output drive voltage of the IXDN404 is locked at about -2V. 3 Conclusion The IGBT drive and protection circuit composed of IXDN404 can meet the IGBT drive requirements, and its characteristics can be summarized as follows: --Drive power supply +20V single-channel power supply, drive gate voltage +15V~-5V; --The maximum drive peak current can reach 8A, which meets the requirements of high-power IGBT drive; --The circuit signal delay time is short, and the operating frequency can reach 100kHz or higher, which can meet the needs of most circuits; --It can realize overcurrent protection and gate voltage reduction slow shutdown function; --The circuit cost is relatively low. In summary, this drive protection circuit is a low-cost, high-performance IGBT drive circuit.2 Normal shutdown process When the control signal is low level, the optocoupler outputs high level, and the inverting output is low level. Since the output pulse of IXDN404 is -5V due to the clamping of Z3, the IGBT is normally shut down. At this time, V4 is turned on, V5 is turned off, and the potential at point C remains at 9V; Z1 is turned off, V2 is turned off, V1 is turned on, and the potential at point B is close to 20V; Z2 is turned off, V3 is turned off, and the potential at point D is close to the potential at point B. Figure 2 2.3 Protection process Assume that the IGBT has been turned on, and the potentials of each point are as described in 2.1. When the circuit is overcurrent, the IGBT exits the resistance zone due to the large current, Vces rises, the diode D2 is turned off, and the clamping effect of point A on the capacitor C1 disappears; the potential of point C rises from 9V, and at the same time Z1 reverses and breaks down, V2 is turned on, V1 is turned off, and the potential of point B is determined by the voltage division of R1 and Rc and the internal resistance of the IXDN404 chip, clamped at 15V, and the gate voltage drops to 10V. The reduction of the gate voltage can effectively suppress the fault current and increase the short-circuit allowable time. The gate voltage reduction operation time is t2=τ1ln(20-0)/(20-13)=1.09μs (2) If during this period of time, the circuit returns to normal, D2 is turned on, point A continues to clamp, V2 is turned off, V1 is turned on, and the circuit returns to the state described in 2.1. If D2 is still in the off state, that is, the fault current still exists, the voltage at point C continues to rise, and after t2 time it rises to 13V, Z2 reverses and breaks down, V3 turns on, capacitor C2 discharges through resistor R12, the potentials at points D and B drop at the same time, and the IGBT gate voltage gradually drops, realizing the slow shutdown process, avoiding the overvoltage caused by normal shutdown of large current. The slow shutdown process time is t3, which is determined by C2 and R12. Since the operating voltage range of IXDN404 is 4.5~25V, τ2=R12×C2=4.84μs, it can be known that t3=τ2ln(15/4.5)=5.83μs (3) In addition, during the IGBT turn-on process, if diode D2 cannot be turned on in time, it will cause malfunction of the protection circuit. Therefore, D2 should choose a fast diode. It can also extend the protection circuit action time by appropriately increasing the Z1 voltage regulator value and increasing the resistor R9 to increase the C1 charging time constant. But this is contradictory to the rapidity of the protection action. In specific applications, a compromise should be made according to the actual circuit requirements and the characteristics of the power device. 2.4 Some explanations 1) In order to maximize the driving power, this circuit uses two inputs and outputs in parallel. The maximum driving peak current can reach 8A. This peak current is generated by the instantaneous discharge of capacitor Cc; 2) The output of the optocoupler 6N137 is the input inversion, and the IXDN404 is the same phase input and output. To ensure the correct control logic, a first-level inverter is required in the middle. The IXDI404 with inversion can also be used; 3) In Figure 2, an optocoupler can be added at point E, and its output can be sent to the control logic as a short-circuit protection signal to block the PWM signals of this and other channels to ensure the safety of the main circuit; 4) The IXDN404 drive circuit is very sensitive to pulse signals. In actual operation, the connection should be as short as possible. The output should be connected to the IGBT with a twisted pair. The components used in the circuit can also be patch-type, which not only reduces the size of the drive circuit but also improves the working stability. Figure 3 shows the gate drive signal of the measured IGBT, where channel 1 is the input control signal and channel 2 is the output drive signal. The IGBT used is the Fairchild HGTG18N120BND. It can be seen from the figure that the delay time of the drive circuit is only 100ns. Figure 3 (d) is a protection waveform simulating the overcurrent of the IGBT. First, the gate voltage is reduced, then it is slowly turned off, and finally, due to the low voltage power supply, the output drive voltage of the IXDN404 is locked at about -2V. 3 Conclusion The IGBT drive and protection circuit composed of IXDN404 can meet the IGBT drive requirements, and its characteristics can be summarized as follows: --Drive power supply +20V single-channel power supply, drive gate voltage +15V~-5V; --The maximum drive peak current can reach 8A, which meets the requirements of high-power IGBT drive; --The circuit signal delay time is short, and the operating frequency can reach 100kHz or higher, which can meet the needs of most circuits; --It can realize overcurrent protection and gate voltage reduction slow shutdown function; --The circuit cost is relatively low. In summary, this drive protection circuit is a low-cost, high-performance IGBT drive circuit.4. Some explanations 1) To maximize the driving power, this circuit uses two inputs and outputs in parallel. The maximum driving peak current can reach 8A. This peak current is generated by the instantaneous discharge of capacitor Cc; 2) The output of the optocoupler 6N137 is the input inversion, and the IXDN404 is the same phase input and output. To ensure the correct control logic, an inverter is required in the middle. The IXDI404 with inversion can also be used; 3) In Figure 2, an optocoupler can be added at point E, and its output can be sent to the control logic as a short-circuit protection signal to block the PWM signals of this and other channels to ensure the safety of the main circuit; 4) The IXDN404 drive circuit is very sensitive to pulse signals. In actual operation, the connection should be as short as possible. The output should be connected to the IGBT with a twisted pair. The components used in the circuit can also be patch-type, which not only reduces the size of the drive circuit, but also improves the working stability. Figure 3 shows the gate drive signal of the measured IGBT, where channel 1 is the input control signal and channel 2 is the output drive signal. The IGBT used is Fairchild's HGTG18N120BND. It can be seen from the figure that the delay time of the drive circuit is only 100ns. Figure 3 (d) is a protection waveform simulating IGBT overcurrent. First, the gate voltage is reduced, then it is slowly turned off, and finally, due to the low voltage power supply, the output drive voltage of IXDN404 is locked at about -2V. 3 Conclusion The IGBT drive and protection circuit composed of IXDN404 can meet the IGBT drive requirements, and its characteristics can be summarized as follows: --Drive power supply +20V single-channel power supply, drive gate voltage +15V~-5V; --The maximum drive peak current can reach 8A, which meets the requirements of high-power IGBT drive; --The circuit signal delay time is short, and the operating frequency can reach 100kHz or higher, which can meet the needs of most circuits; --It can realize overcurrent protection and gate voltage reduction slow shutdown function; --The circuit cost is relatively low. In summary, this drive protection circuit is a low-cost, high-performance IGBT drive circuit.4. Some explanations 1) To maximize the driving power, this circuit uses two inputs and outputs in parallel. The maximum driving peak current can reach 8A. This peak current is generated by the instantaneous discharge of capacitor Cc; 2) The output of the optocoupler 6N137 is the input inversion, and the IXDN404 is the same phase input and output. To ensure the correct control logic, an inverter is required in the middle. The IXDI404 with inversion can also be used; 3) In Figure 2, an optocoupler can be added at point E, and its output can be sent to the control logic as a short-circuit protection signal to block the PWM signals of this and other channels to ensure the safety of the main circuit; 4) The IXDN404 drive circuit is very sensitive to pulse signals. In actual operation, the connection should be as short as possible. The output should be connected to the IGBT with a twisted pair. The components used in the circuit can also be patch-type, which not only reduces the size of the drive circuit, but also improves the working stability. Figure 3 shows the gate drive signal of the measured IGBT, where channel 1 is the input control signal and channel 2 is the output drive signal. The IGBT used is Fairchild's HGTG18N120BND. It can be seen from the figure that the delay time of the drive circuit is only 100ns. Figure 3 (d) is a protection waveform simulating IGBT overcurrent. First, the gate voltage is reduced, then it is slowly turned off, and finally, due to the low voltage power supply, the output drive voltage of IXDN404 is locked at about -2V. 3 Conclusion The IGBT drive and protection circuit composed of IXDN404 can meet the IGBT drive requirements, and its characteristics can be summarized as follows: --Drive power supply +20V single-channel power supply, drive gate voltage +15V~-5V; --The maximum drive peak current can reach 8A, which meets the requirements of high-power IGBT drive; --The circuit signal delay time is short, and the operating frequency can reach 100kHz or higher, which can meet the needs of most circuits; --It can realize overcurrent protection and gate voltage reduction slow shutdown function; --The circuit cost is relatively low. In summary, this drive protection circuit is a low-cost, high-performance IGBT drive circuit.