A novel ultra-high current three-terminal voltage regulator with overvoltage surge suppression function

Abstract

The present invention provides a novel ultra-high current three-terminal voltage regulator with overvoltage surge suppression function, which is small in size, low in cost and easy to be mass-produced and used. It includes two IGBT tubes Q9 and Q10 connected in parallel between the voltage input terminal Vin and the voltage output terminal Vo. The two IGBT tubes Q9 and Q10 are also connected to a drive control circuit, and the drive control circuit is a floating ground amplification drive control circuit. The drive control circuit further includes a soft start circuit inside and enables the voltage output terminal Vo to achieve soft start. The drive control circuit is connected to an overvoltage protection circuit, an overcurrent protection circuit and an undervoltage protection circuit.

Description

Technical Field

[0001] The present invention relates to the technical field of power supply systems, and particularly to a novel ultra-high current three-terminal voltage regulator with overvoltage surge suppression function. Background Art

[0002] At present, the electronic instruments and meters in the fields of military, aviation, aerospace, etc. require a stable DC voltage during operation. Moreover, the current during the operation of the electronic instruments and meters sometimes varies greatly. Coupled with the relatively long length of the power supply cable, instantaneous (duration of dozens to hundreds of milliseconds) overvoltage surges will be generated at the power input end of the electronic instruments and meters. In order to prevent abnormal overvoltage surges, the power supply system generally adopts two schemes for the voltage stabilizing circuit: one is to adopt a pulse width modulation type switching power supply, and the other is to adopt a three-terminal voltage regulator voltage stabilizing circuit. However, both methods have their own advantages and disadvantages.

[0003] The first one adopts a pulse width modulation type switching power supply. Its advantages are that the input end can withstand a relatively wide input voltage range and a relatively high input voltage. The disadvantage is that when the main power switch (mainly using MOS transistors) and the rectifier switch (mainly using MOS transistors or diodes) are in the switching state and working with a large current, a large amount of electrical noise with high energy will be generated. In order to suppress the electrical noise, it is usually necessary to install power noise filters at the input end and the output end of the switching power supply respectively. However, since the volume of the filter increases continuously with the increase of the working current, when the current reaches more than 20A, not only the circuit becomes more complex, but also the volume of the filter is very large, so it requires a large amount of space.

[0004] The second one adopts an integrated circuit three-terminal voltage regulator. The advantage is that since the main power adjustment transistor (triode) works in the amplification state and does not generate electrical noise, a power noise filter can be not installed. However, the output current carried by the three-terminal voltage regulator is relatively small (generally, the load current of a three-terminal voltage regulator does not exceed 7.5A). When the load requires a large current, several three-terminal voltage regulators are needed to supply power to the load respectively. In addition, the input voltage range of the three-terminal voltage regulator is relatively small, especially the upper limit of the input voltage is not high. When encountering a short-term (duration of dozens to hundreds of milliseconds) overvoltage surge exceeding the upper limit of the input voltage, breakdown and damage will occur. Therefore, it is necessary to install a special anti-overvoltage surge module (the maximum working current of the products on the market is generally 20A) at the input end of the three-terminal voltage regulator to ensure the normal and reliable operation of the three-terminal voltage regulator. Both of the above two methods have a common disadvantage: complex structure, large volume, and high cost, which are not suitable for use in power supply systems that require small volume, low cost, and mass production. Summary of the Invention

[0005] In view of the problems that when an overvoltage surge occurs in an existing power supply, using a pulse width modulation type switching power supply or a three-terminal voltage regulator voltage stabilizing circuit results in a complex body structure, a large volume, and a high cost, and it is not suitable for use in power supplies for mass production, the present invention provides a novel ultra-large current three-terminal voltage regulator with an overvoltage surge suppression function, which has a small volume, a low cost, and is easy to use in mass production.

[0006] Its technical solution is as follows: A novel ultra-large current three-terminal voltage regulator with an overvoltage surge suppression function, characterized in that it includes two IGBT tubes Q9 and Q10 connected in parallel between a voltage input terminal Vin and a voltage output terminal Vo, and the two IGBT tubes Q9 and Q10 are also connected to a drive control circuit, the drive control circuit is a floating ground amplification drive control circuit, the drive control circuit further includes a soft start circuit inside and enables the voltage output terminal Vo to achieve soft start, and the drive control circuit is connected to an overvoltage protection circuit, an overcurrent protection circuit, and an undervoltage protection circuit.

[0007] It is further characterized in that: the drive control circuit includes an operational amplifier Q3, the 1st pin of the operational amplifier Q3 is connected to one end of a resistor R10, the other end of the resistor R10 is connected to one end of a capacitor C6, the 4th pin of an optocoupler Q4, and one end of a resistor R11; the 2nd pin of the operational amplifier Q3 is connected to one end of a resistor R9, one end of a resistor R29, and one end of a capacitor C4; the 3rd pin of the optocoupler Q4 is connected to the other end of the capacitor C6, the other end of the resistor R9 and grounded; the 1st pin of the optocoupler Q4 is connected to one end of a resistor R14, the other end of the resistor R14 is connected to the VCC+ power supply; the 2nd pin of the optocoupler Q4 is connected to the cathode of a voltage reference Q8, the anode of the voltage reference Q8 is connected to one end of a resistor R17, the overvoltage protection circuit, the undervoltage protection circuit, the overcurrent protection circuit and the ground terminal GND; the reference terminal of the voltage reference Q8 is connected to the other end of the resistor R17 and one end of a resistor R16, the other end of the resistor R16 is connected to one end of a resistor R15, the other end of the resistor R15 is connected to the overcurrent protection circuit; the 3rd and 4th pins of the operational amplifier Q3 are connected together and grounded; the 5th pin of the operational amplifier Q3 is connected to one end of a capacitor C5 and the undervoltage protection circuit; the 6th pin of the operational amplifier Q3 is connected to one end of a resistor R8 and one end of a resistor R23, the other end of the resistor R8 is connected to one end of the resistor R29 and the other end of the capacitor C4, the other end of the resistor R23 is connected to the gates of an IGBT tube Q9 and an IGBT tube Q10, and one end of a resistor R12; the other end of the resistor R12 is connected to the emitters of the IGBT tube Q9 and the IGBT tube Q10, the overcurrent protection circuit and grounded; the overcurrent protection circuit is connected to an output voltage source Vo; the collectors of the IGBT tube Q9 and the IGBT tube Q10 are connected together and then connected to the undervoltage protection circuit, the overvoltage protection circuit and an input voltage source Vin; the 7th pin of the operational amplifier Q3 is connected to the overvoltage protection circuit, wherein the resistor R11, the capacitor C6 and the periphery of the operational amplifier Q3 form a soft start circuit, which makes the output voltage source Vo slowly increase from zero to the rated output voltage to achieve soft start;

[0008] The overvoltage protection circuit includes transistors Q1, Q2 and optocoupler Q5. The base of transistor Q1 is connected to one end of resistor R2 and one end of resistor R3. The other end of resistor R2 is connected to one end of resistor R1. The other end of resistor R1 is connected to the input voltage source Vin, one end of resistor R4, the collector of IGBT Q9, the collector of IGBT Q10, and the undervoltage protection circuit. The collector of transistor Q1 is connected to the other end of resistor R4 and one end of resistor R6. The emitter of transistor Q1 is connected to one end of resistor R5. The base of transistor Q2 is connected to the other end of resistor R5. The emitter of transistor Q2 is connected to the other end of resistor R6. The collector of transistor Q2 is connected to one end of resistor R7 and the positive electrode of diode D1. The negative electrode of diode D1 is connected to one end of resistor R21. The other end of resistor R21 is connected to the overcurrent protection circuit. The other end of resistor R7 is connected to the other end of resistor R3, the overcurrent protection circuit and the ground terminal GND. The 1st and 2nd pins of optocoupler Q5 are respectively connected to the overcurrent protection circuit. The 3rd pin of optocoupler Q5 is grounded. The 4th pin of optocoupler Q5 is connected to one end of resistor R13 and the 7th pin of operational amplifier Q3. The other end of resistor R13 is connected to the other end of resistor R11 and the undervoltage protection circuit;

[0009] The undervoltage protection circuit includes DC-DC converter Q11. The 1st pin of DC-DC converter Q11 is connected to one end of inductor L1. The 2nd pin of DC-DC converter Q11 is connected to one end of capacitor C1, one end of capacitor C2, one end of capacitor C3 and the ground terminal GND. The other end of inductor L1 is connected to the other end of capacitor C1, the other end of capacitor C2, the other end of capacitor C3 and the input voltage source Vin. The 3rd and 5th pins of DC-DC converter Q11 are grounded. The 4th pin of DC-DC converter Q11 outputs the VCC+ voltage source. The 7th pin of DC-DC converter Q11 is connected to the 5th pin of operational amplifier Q3, the other end of resistor R11 and the other end of resistor R13;

[0010] The overcurrent protection circuit includes an operational amplifier Q7. One end of a resistor R23 and one end of a resistor R24 are respectively connected to pins 1 and 5 of the operational amplifier Q7. One end of a resistor R27 and one end of a resistor R19 are connected to pin 3 of the operational amplifier Q7. One end of a resistor R28 and one end of a resistor R20 are connected to pin 2 of the operational amplifier Q7. The other end of the resistor R28 is connected to one end of a resistor R21. The other end of the resistor R21 is connected to the positive electrode of a diode D2 and pin 6 of the operational amplifier Q7. The negative electrode of the diode D2 is connected to one end of a resistor R26. The other end of the resistor R26 is connected to the base of a triode Q6 and the other end of the diode R21. The emitter of the triode Q6 is connected to the ground terminal GND. The collector of the triode Q6 is connected to pin 2 of the optocoupler Q5. The other end of the resistor R19 is connected to one end of a resistor Rs2, one end of a resistor Rs1, the other end of the resistor R12, the emitter of the IGBT transistor Q9, and the emitter of the IGBT transistor Q10. After the other end of the resistor Rs1 and the other end of the resistor Rs2 are connected to each other, they are connected to the other end of the resistor R22, the other end of the resistor R15, the other end of the resistor R20, one end of a capacitor C8, one end of a capacitor C9, one end of a capacitor C10, and the output voltage source Vo. The other ends of the capacitor C8, the capacitor C9, and the capacitor C10 are connected to each other and then connected to the ground terminal GND. Pin 4 of the operational amplifier Q7 is connected to the other end of the resistor R23, the other end of the resistor R24, VCC-, and one end of a capacitor C11. The other end of the capacitor C11 is connected to one end of a resistor R18 and one end of a capacitor C7 and is grounded. Pin 7 of the operational amplifier Q7 is connected to the other end of the capacitor C7 and VCC+. The other end of the resistor R18 is connected to the other end of the resistor R27.

[0011] After adopting the above structure, by using the IGBT transistors Q9 and Q10 connected in parallel and taking advantage of their larger power capacity than MOS transistors, the MOS transistors in a general dedicated overvoltage surge module are replaced to absorb the energy generated by overvoltage surges, achieving the function of resisting overvoltage surges. When there is no overvoltage surge, the input voltage is in the rated input voltage state. The two IGBT transistors can also adjust the voltage between the collector and the emitter, playing a role in stabilizing the output voltage. At the same time, since the working regions of the two IGBT transistors are always in the amplification state and no electrical noise will be generated, there is no need to additionally install a power noise filter, reducing the volume and saving costs. It is suitable for use in power supplies for mass production. At the same time, the drive control circuit of the two IGBT transistors is a floating-ground amplification drive control circuit, and an overvoltage protection circuit, an overcurrent protection circuit, and an undervoltage protection circuit are also installed to provide overvoltage, overcurrent, and undervoltage protection functions respectively. Description of the Drawings

[0012] Figure 1 It is the overall circuit structure schematic diagram of the present invention. Detailed Embodiments

[0013] As Figure 1 shown, a new type of ultra - large - current three - terminal voltage regulator with over - voltage surge suppression function includes two IGBT tubes Q9 and Q10 connected in parallel between the voltage input terminal Vin and the voltage output terminal Vo. The two IGBT tubes Q9 and Q10 are also connected to a drive control circuit, and the drive control circuit is a floating - ground GND1 amplification drive control circuit. The drive control circuit also includes a soft - start circuit inside and enables the voltage output terminal Vo to achieve soft - start. The drive control circuit is connected to an over - voltage protection circuit, an over - current protection circuit, and an under - voltage protection circuit.

[0014] The requirements for the power supply module of the present invention are: rated input voltage 18 ± 2 1 VDC, output voltage 15 V, output voltage accuracy better than 1.5%, output current 20 A, operating ambient temperature - 40~ + 70 °C, having an over - voltage surge resistance function (50 VDC / 100 mS, 10 times per minute), and being required to pass a certain electromagnetic compatibility test standard. In addition, it has a small volume and low cost. To meet the requirement of a load current of 25 A and reduce the thermal resistance, two IKW75N60T - type IGBT tubes are used in parallel, and the working region is in the variable - resistance region (amplification state) of the IGBT tube.

[0015] The calculation of the safe operating point of the IGBT tube is as follows:

[0016] The electrical parameters of the IGBT tube (IKW75N60T) are: collector - emitter breakdown voltage V CE = 600 V, maximum current I CMAX = 75 A, maximum power consumption P CMAX = 428 W, operating junction temperature range T J = - 40~ + 175 °C, collector - emitter saturation voltage drop V CESAT = 1.5 V, thermal resistance between junction and case R thjc = 0.35 °C / W. When there is an over - voltage surge (50 VDC / 100 mS, 10 times per minute), the duty cycle is D = 0.1 s÷(60 s÷10)=0.017. At this time, the dynamic thermal resistance Z thjc = 0.25 °C / W, and the highest operating temperature of the product T AMAX = 70 °C.

[0017] The calculation of the actual electrical stress is as follows:

[0018] Rated operating current: I O = 20 A < 2I CMAX ;

[0019] Power consumption at rated maximum input voltage: P O1 =(20 - 15)V×20 A = 100 W;

[0020] Junction temperature during operation at high - temperature rated input voltage: T J1 = R thjc × P O1 ÷ 2 + T AMAX = 87.5 °C;

[0021] Maximum power consumption during over - voltage surge: P O2 =(V INMAX - V O ) × I O =(50 - 15)V × 20A = 700W < 2P CMAX；

[0022] Highest operating junction temperature during over - voltage surge is: T J2 = Z thjc × (P O2 - P O1 ) ÷ 2 + T J1 (1)

[0023] Substitute P O1 = 100W, P O2 = 700W, Z thjc = 0.25 °C, T J1 = 87.5 °C into formula (1), the highest operating junction temperature T J2 = 162.5 < T JMAX (175 °C). Therefore, the operating current, operating voltage, power consumption and highest operating junction temperature of the IGBT transistor are all in a safe state.

[0024] Specifically, the drive control circuit includes operational amplifier Q3 (OPA548T), optocoupler Q4 (PC817), voltage reference Q8 (TL431) and peripheral resistors R8, R9, R 10 、R 11 、R 14 、R 15 、R 16 、R 17and capacitors C4 to C6. The 1st pin of operational amplifier Q3 is connected to one end of resistor R10, the other end of resistor R10 is connected to one end of capacitor C6, the 4th pin of optocoupler Q4, and one end of resistor R11. The 2nd pin of operational amplifier Q3 is connected to one end of resistor R9, one end of resistor R29, and one end of capacitor C4. The 3rd pin of optocoupler Q4 is connected to the other end of capacitor C6, the other end of resistor R9 and grounded. The 1st pin of optocoupler Q4 is connected to one end of resistor R14, the other end of resistor R14 is connected to the VCC+ power supply. The 2nd pin of optocoupler Q4 is connected to the cathode of voltage reference Q8, the anode of voltage reference Q8 is connected to one end of resistor R17, overvoltage protection circuit, undervoltage protection circuit, overcurrent protection circuit and ground terminal GND. The reference terminal of voltage reference Q8 is connected to the other end of resistor R17 and one end of resistor R16, the other end of resistor R16 is connected to one end of resistor R15, the other end of resistor R15 is connected to the overcurrent protection circuit. The 3rd and 4th pins of operational amplifier Q3 are connected together and grounded. The 5th pin of operational amplifier Q3 is connected to one end of capacitor C5 and the undervoltage protection circuit. The 6th pin of operational amplifier Q3 is connected to one end of resistor R8 and one end of resistor R23. The other end of resistor R8 is connected to one end of resistor R29 and the other end of capacitor C4. The other end of resistor R23 is connected to the gates of IGBT transistors Q9 and Q10, and one end of resistor R12. The other end of resistor R12 is connected to the emitters of IGBT transistors Q9 and Q10, the overcurrent protection circuit and grounded. The overcurrent protection circuit is connected to the output voltage source Vo. The collectors of IGBT transistors Q9 and Q10 are connected together and then connected to the undervoltage protection circuit, overvoltage protection circuit and input voltage source Vin. The 7th pin of operational amplifier Q3 is connected to the overvoltage protection circuit. Among them, resistor R11, capacitor C6 and the periphery of operational amplifier Q3 form a soft-start circuit, which makes the output voltage source Vo slowly increase from zero to the rated output voltage, realizing soft start.

[0025] In the drive control circuit, where resistor R 15 、R 16 、R 17 form the sampling circuit of voltage output terminal V O . Since IGBT transistors Q9 and Q10 need floating drive, first, the voltage signals on the sampling signals RS1 and RS2 are amplified by operational amplifier Q7 through operation, then inverted and amplified by triode Q6, and isolated and transmitted by optocoupler Q4. The isolated signal Vc is added to the non-inverting input terminal of high-current operational amplifier Q3. After being amplified by operational amplifier Q3, it drives and controls the gates G of IGBT transistors Q9 and Q10. By changing the magnitude of the gate voltage Vg, the magnitude of voltage output terminal V O can be adjusted, realizing a stable voltage output terminal V O . Operational amplifier Q3 uses a high-output current operational amplifier, then it can directly drive the gates G of IGBT transistors Q9 and Q10. The specific process is: when voltage output terminal V O ↑ (higher than 15V), the sampling voltage V r↑→Cathode voltage V of voltage reference Q8 k ↓→Diode current I of optocoupler Q4 F ↑→Collector current Ic of optocoupler Q4↑→Non-inverting input voltage Vc of operational amplifier Q3↓→Gate voltages Vg of two IGBT transistors↓→Voltage output terminal Vo↓→Maintain V O = 15V; When the voltage output terminal V O ↓ (below 15V), sampled voltage Vr↓→Cathode voltage V of voltage reference Q8 K ↑→Diode current I of optocoupler Q4 F ↓→Collector current Ic of optocoupler Q4↓→Non-inverting input voltage Vc of operational amplifier Q3↑→Gate voltages Vg of two IGBT transistors↑→Voltage output terminal Vo↑→Maintain V O = 15V.

[0026] The main calculation process is as follows:

[0027] The relationship between the sampled voltage Vr and the voltage output terminal Vo is: V O = V r × [1 + (R 15 + R 16 ) ÷ R17] (2);

[0028] Where Vr is the voltage reference of voltage reference Q8, Vr = 2.49V. Take R 17 = 5.1K, from formula (2) we get R 15 + R 16 = 25.6K, take R 15 = 24K, R 16 = 1.8K. During actual production, R 16 is used as a debugging resistor to finely adjust the output voltage accuracy.

[0029] The control characteristic of the IGBT transistor is: G fs = I CE ÷ Vg (3);

[0030] In the formula, G fs is the transconductance of the IGBT transistor, I CE is the operating current of a single IGBT transistor. In fact, G fs ≈ 3.3s, I CE = 10A, substituting into formula (3) we get Vg ≈ 3V.

[0031] The relationship between the amplification factor K of operational amplifier Q3 and the external resistors is: K = [1 + (R8 + R 29 ) ÷ R9] (4);

[0032] Take K = 50, R9 = 10K, from formula (4) we get R8 + R 29If = 490K, then R8 = 470K can be selected, and R 29 = 20K. And take R 29 as the debugging resistor, finely adjust its resistance value, finely adjust the amplification factor, and can also accurately control the gate voltage Vg of the IGBT tube to make the output voltage meet the accuracy requirements.

[0033] The diode current I of the optocoupler Q4 F and the cathode voltage V of the voltage reference Q8 K have the following relationship:

[0034] V CC+ = I F × R 14 + V K + V F (5);

[0035] where V CC+ is the +12V voltage generated by the DC-DC converter Q11; V K is the cathode operating point voltage of the voltage reference Q8, and V F is the forward voltage drop of the optocoupler Q4 diode. Take the optimal voltage V K = 3V, the diode current I of the optocoupler Q4 K = 5mA, V F = 1.2V and substitute them into formula (5) to get R F = 1.5K. 14 = 1.5K.

[0036] The relationship between the output voltage Vg of the operational amplifier Q3 (i.e., the gate voltage of the IGBT tube) and the cathode voltage V of the voltage reference Q8 K is: V CC1 = R 11 × CTR × (V CC+ - V K - V F ) ÷ R 14 + Vg × R9 ÷ (R8 + R 29 + R9) (6);

[0037] In the formula, V CC1 is the +10V voltage generated by Q 11 ; CTR is the current transfer ratio of the optocoupler Q4: CTR = 100%. Substitute R 14 = 1.5K, V CC1 = +10V, CTR = 100%, V K = 3V, Vg = 3V, V F = 1.2V into (6), then R 11 = 1.9K, and take R 11 = 2K.

[0038] To prevent excessive output inrush current when just powered on, a soft start circuit is added to the drive control circuit. Resistor R 11 , capacitor C6 and the peripherals of operational amplifier Q3 form the soft start circuit. When just powered on, the voltage source V CC1 charges capacitor C6 through resistor R 11 . At this time, the non-inverting input voltage of operational amplifier Q3 slowly increases from zero, the control voltage Vg applied to the two IGBT tubes also slowly increases from zero, and the voltage output terminal Vo also slowly increases from zero to the rated output voltage, realizing soft start.

[0039] Specifically, the overvoltage protection circuit includes transistor Q1, transistor Q2, optocoupler Q5, diode D1, resistors R1, R2, R3, R4, R5, R6, R7, R 21 and R 13 . The base of transistor Q1 is connected to one end of resistor R2 and one end of resistor R3. The other end of resistor R2 is connected to one end of resistor R1. The other end of resistor R1 is connected to the input voltage source Vin, one end of resistor R4, the collector of IGBT tube Q9, the collector of IGBT tube Q10, and the undervoltage protection circuit. The collector of transistor Q1 is connected to the other end of resistor R4 and one end of resistor R6. The emitter of transistor Q1 is connected to one end of resistor R5. The base of transistor Q2 is connected to the other end of resistor R5. The emitter of transistor Q2 is connected to the other end of resistor R6. The collector of transistor Q2 is connected to one end of resistor R7 and the positive pole of diode D1. The negative pole of diode D1 is connected to one end of resistor R21. The other end of resistor R21 is connected to the overcurrent protection circuit. The other end of resistor R7 is connected to the other end of resistor R3, the overcurrent protection circuit and the ground terminal GND. The 1st and 2nd pins of optocoupler Q5 are respectively connected to the overcurrent protection circuit. The 3rd pin of optocoupler Q5 is grounded. The 4th pin of optocoupler Q5 is connected to one end of resistor R13 and the 7th pin of operational amplifier Q3. The other end of resistor R13 is connected to the other end of resistor R11 and the undervoltage protection circuit.

[0040] During operation, when the voltage input terminal Vin is higher than 55V, transistors Q1, Q2, optocoupler Q5, and diode D1 conduct. The voltage V CE at the collector of the transistor of optocoupler Q5 is a low voltage. The voltage applied to the enable terminal 7th pin of operational amplifier Q3 is a low level. Operational amplifier Q3 does not work. The control voltage Vg applied to the two IGBT tubes Q9 and Q10 is zero. The two IGBT tubes Q9 and Q10 are turned off. The voltage output terminal Vo is zero. On the contrary, when the voltage input terminal Vin is lower than 55V, transistors Q1, Q2, optocoupler Q5, and diode D1 are turned off. The voltage applied to the enable terminal 7th pin of operational amplifier Q3 is a high level. Operational amplifier Q3 works. The control voltage Vg applied to the two IGBT tubes Q9 and Q10 is the working voltage. The two IGBT tubes Q9 and Q10 are turned on. The voltage output terminal Vo is 15V.

[0041] The under-voltage protection circuit includes a DC-DC converter Q11. One end of the inductor L1 is connected to pin 1 of the DC-DC converter Q11. One ends of the capacitor C1, capacitor C2, capacitor C3 and the ground terminal GND are connected to pin 2 of the DC-DC converter Q11. The other end of the inductor L1 is connected to the other ends of the capacitor C1, capacitor C2, capacitor C3 and the input voltage source Vin. Pins 3 and 5 of the DC-DC converter Q11 are grounded. Pin 4 of the DC-DC converter Q11 outputs the VCC+ voltage source. Pin 7 of the DC-DC converter Q11 is connected to pin 5 of the operational amplifier Q3, the other end of the resistor R11, and the other end of the resistor R13. The DC-DC converter Q11 serves as the auxiliary power supply in the present invention. It is a micro DC / DC converter. Since it only powers the operational amplifier, the actual output power (output power 5W) is very small, and the generated electrical noise energy is very small. There is no need to additionally install a power noise filter. Only small-sized inductors and capacitors need to be added at the input end of the DC-DC converter Q11. Its electrical performance requirements are: input 18 - 72VDC, output ±12VDC / +10VDC, with under-voltage protection function. When the input voltage is lower than 16.5V, the DC-DC converter Q11 has no output voltage, the operational amplifiers Q3 and Q7 do not work, and the two IGBT tubes Q9 and Q10 are cut off, and the product has no output voltage. Therefore, it has the function of under-voltage protection.

[0042] The over-current protection circuit includes sampling resistors R S1 、R S2 、operational amplifier Q7, diode D2, triode Q6, optocoupler Q5, capacitor C 11 、resistor R 18 、R 19 、R 20 、R 21 、R 23 、R 24 、R 26 、R 27 、R 28, where the optocoupler Q5 is an optocoupler shared by the overvoltage protection circuit and the overcurrent protection circuit, and the operational amplifier Q7 and the peripheral resistors form a differential operational amplifier. The 1st and 5th pins of the operational amplifier Q7 are respectively connected to one end of the resistor R23 and one end of the resistor R24. The 3rd pin of the operational amplifier Q7 is connected to one end of the resistor R27 and one end of the resistor R19. The 2nd pin of the operational amplifier Q7 is connected to one end of the resistor R28 and one end of the resistor R20. The other end of the resistor R28 is connected to one end of the resistor R21. The other end of the resistor R21 is connected to the positive electrode of the diode D2 and the 6th pin of the operational amplifier Q7. The negative electrode of the diode D2 is connected to one end of the resistor R26. The other end of the resistor R26 is connected to the base of the triode Q6 and the other end of the diode R21. The emitter of the triode Q6 is connected to the ground terminal GND. The collector of the triode Q6 is connected to the 2nd pin of the optocoupler Q5. The other end of the resistor R19 is connected to one end of the resistor Rs2, one end of the resistor Rs1, the other end of the resistor R12, the emitter of the IGBT tube Q9, and the emitter of the IGBT tube Q10. The other end of the resistor Rs1 is connected to the other end of the resistor Rs2, and then connected to the other end of the resistor R22, the other end of the resistor R15, the other end of the resistor R20, one end of the capacitor C8, one end of the capacitor C9, one end of the capacitor C10, and the output voltage source Vo. The other ends of the capacitor C8, the capacitor C9, and the capacitor C10 are connected together and then connected to the ground terminal GND. The 4th pin of the operational amplifier Q7 is connected to the other end of the resistor R23, the other end of the resistor R24, the voltage source VCC-, and one end of the capacitor C11. The other end of the capacitor C11 is connected to one end of the resistor R18 and one end of the capacitor C7 and grounded. The 7th pin of the operational amplifier Q7 is connected to the other end of the capacitor C7 and the voltage source VCC+. The other end of the resistor R18 is connected to the other end of the resistor R27.

[0043] When the output current is higher than 1.2 times the rated current, the operational amplifier Q7 outputs a high voltage, and the triode Q6 and the optocoupler Q5 are turned on. The voltage V of the collector of the triode of the optocoupler Q5 CE is a low voltage, and the voltage applied to the 7th pin of the enable terminal of the operational amplifier Q3 is a low level. The operational amplifier Q3 does not work, and the control voltage Vg applied to the two IGBT tubes Q9 and Q10 is zero. The two IGBT tubes Q9 and Q10 are turned off, and the output voltage is zero; conversely, when the output current is lower than 1.2 times the rated current, the operational amplifier Q7 outputs a low voltage, the triode Q6 and the optocoupler Q5 are turned off, the voltage applied to the 7th pin of the enable terminal of the operational amplifier Q3 is a high level, the operational amplifier Q3 works, the control voltage Vg applied to the two IGBT tubes Q9 and Q10 is the working voltage, the two IGBT tubes Q9 and Q10 are turned on, and the output voltage is 15V.

[0044] The main calculation process is as follows:

[0045] The differential voltage applied to the differential operational amplifier Q7 is: ⊿Ui = R S ×I OMAX (7);

[0046] In formula (7), RS is the parallel equivalent resistance of sampling resistors R S1 and R S2 . R S = R S1 / / R S2 = 1.5 mΩ, and I Omax is the maximum output current of the product. I OMAX = 1.2 × I O = 24 A. Substitute the values of R S and I OMAX into formula (7), and the differential voltage is obtained as ΔUi = 36 mV.

[0047] When overcurrent occurs, the output V D of the differential operational amplifier Q7 should be greater than 1.8 V. At this time, the amplification factor relationship of the operational amplifier Q7 is: K = V D ÷ΔUi (8);

[0048] Substitute V D = 1.8 V and ΔUi = 36 mV into formula (8), and K = 50 is obtained. The relationship between the amplification factor K of the differential operational amplifier Q7 and the external resistors is:

[0049] K = V D ÷ΔUi = (R 21 + R 28 ) ÷ R 20 = (R 18 + R 27 ) ÷ R 19 (9)

[0050] Take R 19 = R 20 = 10 K and substitute it into (9), then R 21 + R 28 = R 18 + R 27 = 500 K. In fact, R 18 = R 21 = 470 K and R 27 = R 28 = 30 K can be taken. R 27 and R 28 can be used as debugging resistors to finely adjust the resistance value for correcting the accuracy error of the resistance values of sampling resistors R S1 and R S2 . In addition, to further improve the overcurrent detection accuracy, a zero - adjustment circuit is set for the operational amplifier Q7. By changing the resistance values of R 23 and R 24 , the offset voltage of the operational amplifier Q7 is reduced.

[0051] IGBT transistors are generally used in high-power power electronics switches and rectification applications. Mainly in the fields of variable frequency speed regulation power supplies, high-power DC / AC inverter power supplies, charging piles, industrial heating, electroplating power supplies, electric vehicles, etc. They usually operate in two regions (states): conduction and cut-off. This patent applies IGBT transistors to a voltage stabilization circuit. By adding a novel floating ground drive control circuit, the IGBT transistors operate in their variable resistance region (amplification state). By adjusting the gate voltage Vg, the resistance between their C-E electrodes (i.e., the voltage between the collector and the emitter) is changed to achieve the purpose of stabilizing the output voltage. At the same time, since the IGBT transistors operate in their variable resistance region, there is no electrical noise generated during the commutation of MOS transistors or diodes, eliminating the power noise filter in the first solution of the background technology; furthermore, since IGBT transistors are used as the regulating transistors in a similar three-terminal voltage regulator, the current-carrying density and power capacity of the regulating transistors are expanded, enabling the regulating transistors to absorb (withstand) a large amount of energy during overvoltage surges, playing the role of the overvoltage surge protection module in the second solution of the background technology. Therefore, the dedicated overvoltage surge protection module is eliminated, greatly reducing the volume and cost. By adding debugging resistors R 16 、R 23 、R 24 、R 27 、R 28 , the control accuracy is greatly improved. The actual measured value of the output voltage accuracy is better than 1.2%, meeting the requirement of better than 1.5% proposed by the customer.

[0052] The above is only a preferred specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily thought of by those familiar with the technology within the technical scope disclosed by the present invention should be covered by the protection scope of the present invention. Therefore, the protection scope of the present invention should be subject to the protection scope of the claims.

Claims

1. A new type of ultra-high current three-terminal voltage regulator with overvoltage surge suppression function, characterized by: It includes two parallel-connected IGBT tubes Q9 and Q10 installed between the voltage input terminal Vin and the voltage output terminal Vo. The two IGBT tubes Q9 and Q10 are also connected to a drive control circuit. The drive control circuit is a floating ground amplification drive control circuit. The drive control circuit also includes a soft start circuit inside, and enables the voltage output terminal Vo to achieve soft start. The drive control circuit is connected to an overvoltage protection circuit, an overcurrent protection circuit and an undervoltage protection circuit. The drive control circuit includes an operational amplifier Q3, wherein pin 1 of the operational amplifier Q3 is connected to one end of a resistor R10, and the other end of the resistor R10 is connected to one end of a capacitor C6, pin 4 of an optical coupler Q4, and one end of a resistor R11, pin 2 of the operational amplifier Q3 is connected to one end of a resistor R9, one end of a resistor R29, and one end of a capacitor C4, pin 3 of the optical coupler Q4 is connected to the other end of the capacitor C6, the other end of the resistor R9 and grounded, pin 1 of the optical coupler Q4 is connected to one end of a resistor R14, and the other end of the resistor R14 is connected to a VCC+ power supply, and pin 2 of the optical coupler Q4 is connected to a voltage The cathode of the voltage reference Q8, the anode of the voltage reference Q8 is connected to one end of the resistor R17, the overvoltage protection circuit, the undervoltage protection circuit, the overcurrent protection circuit and the ground terminal GND, the reference end of the voltage reference Q8 is connected to the other end of the resistor R17 and one end of the resistor R16, the other end of the resistor R16 is connected to one end of the resistor R15, and the other end of the resistor R15 is connected to the overcurrent protection circuit, the 3rd and 4th pins of the operational amplifier Q3 are connected to ground, the 5th pin of the operational amplifier Q3 is connected to one end of the capacitor C5 and the undervoltage protection circuit, The other end of the capacitor C5 is grounded; the 6th pin of the operational amplifier Q3 is connected to one end of the resistor R8, one end of the resistor R23, the other end of the capacitor C4 and the other end of the resistor R29, the other end of the resistor R8 is connected to the other end of the resistor R29 and the other end of the capacitor C4, the other end of the resistor R23 is connected to the gate of the IGBT tube Q9, the gate of the IGBT tube Q10, and one end of the resistor R12, the other end of the resistor R12 is connected to the emitter of the IGBT tube Q9, the emitter of the IGBT tube Q10, the overcurrent protection circuit and grounded, The overcurrent protection circuit is connected to the voltage output terminal Vo, the collector of the IGBT tube Q9 and the collector of the IGBT tube Q10 are connected and then connected to the undervoltage protection circuit, the overvoltage protection circuit and the input voltage source Vin, the pin 7 of the operational amplifier Q3 is connected to the overvoltage protection circuit, wherein the resistor R11, the capacitor C6 and the periphery of the operational amplifier Q3 form a soft start circuit, which makes the voltage output terminal Vo slowly increase from zero to the rated output voltage to achieve soft start; the pins 1 and 2 of the operational amplifier Q3 are input terminals, and the pin 6 is an output terminal; The overvoltage protection circuit includes transistors Q1, Q2 and an optocoupler Q5, the base of the transistor Q1 is connected to one end of a resistor R2 and one end of a resistor R3, the other end of the resistor R2 is connected to one end of a resistor R1, the other end of the resistor R1 is connected to the input voltage source Vin, one end of a resistor R4, the collector of the IGBT tube Q9, the collector of the IGBT tube Q10, and the undervoltage protection circuit, the collector of the transistor Q1 is connected to the other end of the resistor R4 and one end of the resistor R6, the emitter of the transistor Q1 is connected to one end of the resistor R5, the base of the transistor Q2 is connected to the other end of the resistor R5, and the emitter of the transistor Q2 is connected to The other end of the resistor R6 is connected, the collector of the transistor Q2 is connected to one end of the resistor R7 and the positive electrode of the diode D1, the negative electrode of the diode D1 is connected to one end of the resistor R211, the other end of the resistor R211 is connected to the overcurrent protection circuit, the other end of the resistor R7 is connected to the other end of the resistor R3, the overcurrent protection circuit and the ground terminal GND, the 1st and 2nd pins of the optical coupler Q5 are respectively connected to the overcurrent protection circuit, the 3rd pin of the optical coupler Q5 is grounded, the 4th pin of the optical coupler Q5 is connected to one end of the resistor R13 and the 7th pin of the operational amplifier Q3, and the other end of the resistor R13 is connected to the other end of the resistor R11 and the undervoltage protection circuit; The undervoltage protection circuit includes a DC-DC converter Q11, wherein pin 1 of the DC-DC converter Q11 is connected to one end of an inductor L1, pin 2 of the DC-DC converter Q11 is connected to one end of a capacitor C1, one end of a capacitor C2, one end of a capacitor C3 and a ground terminal GND, the other end of the inductor L1 is connected to the other end of the capacitor C1, the other end of the capacitor C2, the other end of the capacitor C3 and an input voltage source Vin, pins 3 and 5 of the DC-DC converter Q11 are grounded, pin 4 of the DC-DC converter Q11 outputs a VCC+ voltage source, and pin 7 of the DC-DC converter Q11 is connected to pin 5 of the operational amplifier Q3, the other end of the resistor R11 and the other end of the resistor R13; The overcurrent protection circuit includes an operational amplifier Q7, wherein the 1st and 5th pins of the operational amplifier Q7 are respectively connected to one end of a resistor R23 and one end of a resistor R24, the 3rd pin of the operational amplifier Q7 is connected to one end of a resistor R27 and one end of a resistor R19, the 2nd pin of the operational amplifier Q7 is connected to one end of a resistor R28 and one end of a resistor R20, the other end of the resistor R28 is connected to one end of a resistor R21, the other end of the resistor R21 is connected to the positive electrode of a diode D2 and the 6th pin of the operational amplifier Q7, the negative electrode of the diode D2 is connected to one end of a resistor R26, the other end of the resistor R26 is connected to the base of a transistor Q6 and the other end of a resistor R211, the emitter of the transistor Q6 is connected to the ground terminal GND, the collector of the transistor Q6 is connected to the 2nd pin of the optical coupler Q5, the other end of the resistor R19 is connected to one end of a resistor Rs2, one end of a resistor Rs1, the other end of the resistor R12 and the emitter of the IGBT tube Q9, the IGBT tube Q The emitter of 10, the other end of the resistor Rs1 is connected to the other end of the resistor Rs2 and then connected to one end of the resistor R22, the other end of the resistor R15, the other end of the resistor R20, one end of the capacitor C8, one end of the capacitor C9, one end of the capacitor C10 and the voltage output terminal Vo, the other end of the capacitor C8, the other end of the capacitor C9 and the other end of the capacitor C10 are connected and then connected to the ground terminal GND, the 4th pin of the operational amplifier Q7 is connected to the other end of the resistor R23, the other end of the resistor R24, the voltage source VCC-, and one end of the capacitor C11, the other end of the capacitor C11 is connected to one end of the resistor R18, one end of the capacitor C7 and grounded, the 7th pin of the operational amplifier Q7 is connected to the other end of the capacitor C7 and the voltage source VCC+, the other end of the resistor R18 is connected to the other end of the resistor R27; the other end of the resistor R22 is connected to the 1st pin of the optical coupler Q5; the 2nd and 3rd pins of the operational amplifier Q7 are input terminals, and the 6th pin is an output terminal.

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