All-fiber isolation SiC MOSFET gate driver suitable for ultrahigh voltage and application

Abstract

The invention relates to the field of power electronic devices, in particular to an all-fiber isolation SiC MOSFET grid driver suitable for ultrahigh voltage and application, the all-fiber isolation SiC MOSFET grid driver comprises a transmitting side, a fiber group and a receiving side which are connected in sequence, the transmitting side comprises a constant-current laser driver, a semiconductor fiber coupling laser, a fiber coupler of an FC connector, a high-speed light emitter driver and a light emitter, and the receiving side comprises a high-speed light emitter driver and a high-speed light emitter. The optical fiber group comprises a quartz power optical fiber and a plastic signal optical fiber of an FC (Fiber Channel) joint, and the receiving side comprises a beam expander, a laser battery, a 5V boost IC (Integrated Circuit), a 25V boost IC, an optical receiver, a non-isolated driving IC and a push-pull current expanding circuit. And common-mode interference caused by a coupling capacitor is eliminated. Meanwhile, the efficiency of a device is reasonably calculated, and a high-efficiency boost IC is matched, so that the driving power of 0.8 W is realized, and a 6.5 kV 25A high-voltage SiC MOSFET module can be driven to work at the switching frequency of more than 100kHz.

Description

Technical Field

[0001] The present invention relates to the field of power electronic devices, and particularly to a fully fiber-optic isolated SiCMOSFET gate driver applicable to ultra-high voltages and its applications. Background Art

[0002] For medium-voltage (MV) fields such as rail transit, ship traction, and photovoltaic power generation, in order to pursue higher power levels, the voltage levels are also increasing, reaching levels of several kV to dozens of kV. Using multi-chip series modules of high-voltage SiCMOSFETs or high-voltage multi-level topologies at such voltage levels has become a promising solution. However, the extremely high isolation voltage requirements, extremely large dv / dt during switching, and higher drive waveform accuracy requirements in these application fields pose difficulties for the design of isolation drivers.

[0003] The high isolation voltage poses very high requirements for the insulation performance of the isolated drive. The traditional magnetic coupling isolation structure needs to increase the insulation distance to improve the insulation voltage. However, increasing the insulation distance will greatly increase the volume of the iron core, reduce the coupling degree, increase the leakage inductance, resulting in a decrease in the efficiency of the traditional isolated SiC MOSFET gate driver and an increase in cost; and electric field concentration may occur at the insulation interface, leading to partial discharge, which has a great impact on the insulation reliability of the traditional isolated SiC MOSFET gate driver.

[0004] The extremely high dv / dt during switching also poses great difficulties for the design of traditional isolated SiC MOSFET gate drivers. Due to the inherent coupling capacitance of the traditional isolation structure becomes the transmission channel of common-mode interference. The extremely high dv / dt will generate extremely large common-mode currents through the coupling capacitance This current directly surges to the voltage control side. In severe cases, this common-mode current will damage the low-voltage control system, causing serious losses. In the field of multi-chip series modules or high-voltage multi-level topologies, the dv / dt increases exponentially, and the dv / dt can reach several hundred V / ns, making the traditional gate isolation structure inapplicable and new isolation structures need to be sought.

[0005] In addition, in the fields of multi-chip series modules or high-voltage multi-level topologies, extremely high precision requirements are imposed on the driving waveforms. If a 10-ns switching time error is caused by the distortion of the driving waveforms, a 1-kV uneven voltage division will occur under the condition of dt / dt of 100 V / ns, which will affect the insulation reliability of the devices. In severe cases, it may cause the module to break down and burn out. However, the parasitic parameters of the drive, including the parasitic parameters of the power supply (the internal resistance of the power supply, parasitic inductance), the parasitic inductance of the drive trace, etc., will distort the driving waveforms. Therefore, the gate isolation drive for the multi-chip series module or high-voltage multi-level topology fields should be optimized for the drive parasitic parameters to reduce their influence. Summary of the Invention

[0006] Aiming at the problem that the traditional isolation structure in the fields of multi-chip series modules or high-voltage multi-level topologies in the prior art cannot meet the usage requirements and the driving waveforms are distorted due to the drive parasitic parameters, the present invention provides a fully fiber-optic isolated SiC MOSFET gate driver applicable to ultra-high voltages and its application.

[0007] The present invention is realized through the following technical solutions: A fully fiber-optic isolated SiC MOSFET gate driver applicable to ultra-high voltages, comprising a transmitting side, a fiber optic group, and a receiving side connected in sequence. The transmitting side includes a constant current laser driver, a semiconductor fiber-coupled laser, a fiber optic coupler with an FC connector, a high-speed optical transmitter driver, and an optical transmitter. The input ends of both the constant current laser driver and the high-speed optical transmitter driver are connected to an external output voltage. The output end of the constant current laser driver is connected to the input end of the semiconductor fiber-coupled laser. The output end of the semiconductor fiber-coupled laser is connected to the input end of the fiber optic coupler with an FC connector. The output end of the high-speed optical transmitter driver is connected to the input end of the optical transmitter. The fiber optic group includes a quartz power fiber with an FC connector and a plastic signal fiber. The input end of the quartz power fiber is connected to the output end of the fiber optic coupler with an FC connector. The input end of the plastic signal fiber is connected to the output end of the optical transmitter. The receiving side includes a beam expander, a laser battery, a 5V boost IC, a 25V boost IC, an optical receiver, a non-isolated drive IC, and a push-pull current boosting circuit. The output end of the quartz power fiber is connected to the laser battery through the beam expander. The output end of the laser battery is connected to the 5V boost IC and the 25V boost IC in sequence. The output ends of both the 5V boost IC and the 25V boost IC are connected to the input end of the push-pull current boosting circuit. The output end of the plastic signal fiber is connected to the input end of the optical receiver. The output end of the optical receiver is connected to the input end of the non-isolated drive IC. The output end of the non-isolated drive IC is connected to the input end of the push-pull current boosting circuit. The push-pull current boosting circuit is provided with three output ports for outputting power drive signals.

[0008] Preferably, the maximum output current of the constant current laser driver is 5A.

[0009] Preferably, the driving wavelength of the semiconductor fiber-coupled laser is 808 nm and the optical power is 2.65 W.

[0010] Preferably, the output current driven by the high-speed optical transmitter is 400 mA.

[0011] Preferably, the laser battery uses a gallium arsenide laser battery, and its normal operating output voltage is 2V.

[0012] Preferably, the push-pull current-boosting circuit includes a push-pull circuit, a decoupling capacitor bank, and a low-parasitic inductance trace. The push-pull circuit includes three pairs of triodes. The decoupling capacitor bank includes 18 MLCC capacitors, and the 18 MLCC capacitors are distributed on the three ports of the push-pull current-boosting circuit in a ratio of 1:1:1.

[0013] Preferably, the triode has a continuous current output capacity of 7A and an extremely low time delay of 30 ns.

[0014] Preferably, the capacitance of the MLCC capacitor is 10 uF.

[0015] Preferably, the inductance of the low-parasitic inductance trace is 1.17 nH.

[0016] An application of the described all-fiber isolated SiC MOSFET gate driver suitable for ultra-high voltage in a multi-chip series module or a high-voltage multi-level topology.

[0017] Compared with the prior art, the present invention has the following beneficial effects: The all-fiber isolated SiC MOSFET gate driver suitable for ultra-high voltage of the present invention uses insulated power fibers and signal fibers to transmit power and signals, has an infinitely high isolation voltage in theory, eliminates the common-mode interference caused by coupling capacitors, and at the same time optimizes the parasitic parameters, improves the driving waveform accuracy, and can be used in ultra-high voltage fields such as multi-chip series and high-voltage multi-level topologies. At the same time, by reasonably calculating the device efficiency and matching with a high-efficiency boost IC, a driving power of 0.8W is achieved, which is sufficient to drive a 6.5kV 25A high-voltage SiC MOSFET module to operate at a switching frequency above 100 kHz, and has considerable driving ability.

[0018] The present invention also optimizes the structure of the push-pull current-boosting circuit, reduces the maximum power supply voltage fluctuation during instantaneous power output to within 15 mV, and reduces the driving parasitic inductance to 1.17 nH, greatly reducing the influence of the power supply impedance and the trace parasitic inductance on the driving waveform, and greatly improving the driving waveform accuracy. Description of the Drawings

[0019] Figure 1 It is a schematic structural diagram of a fully fiber - isolated SiC MOSFET gate driver applicable to ultra - high voltage in the present invention; Figure 2 It is a circuit schematic diagram of a laser driver in a fully fiber - isolated SiC MOSFET gate driver applicable to ultra - high voltage in the present invention; Figure 3 It is a circuit schematic diagram of an optical transmitter driver in a fully fiber - isolated SiC MOSFET gate driver applicable to ultra - high voltage in the present invention; Figure 4 It is a circuit schematic diagram of the receiving side in a fully fiber - isolated SiC MOSFET gate driver applicable to ultra - high voltage in the present invention; Figure 5 It is the rising - edge waveform of the double - pulse test of a fully fiber - isolated SiC MOSFET gate driver applicable to ultra - high voltage in the present invention; Figure 6 It is the falling - edge waveform of the double - pulse test of a fully fiber - isolated SiC MOSFET gate driver applicable to ultra - high voltage in the present invention. Detailed implementation manners

[0020] The following further elaborates on the present invention in conjunction with specific embodiments, which is an explanation rather than a limitation of the present invention.

[0021] The present invention discloses a fully fiber - isolated SIC MOSFET gate driver applicable to ultra - high voltage. Referring to Figure 1 , it includes a transmitting side, a fiber optic group, and a receiving side connected in sequence. The transmitting side includes a constant - current laser driver, a semiconductor fiber - coupled laser, an FC - connector fiber optic coupler, a high - speed optical transmitter driver, and an optical transmitter. The input ends of both the constant - current laser driver and the high - speed optical transmitter driver are connected to an external output voltage. The output end of the constant - current laser driver is connected to the input end of the semiconductor fiber - coupled laser. The output end of the semiconductor fiber - coupled laser is connected to the input end of the FC - connector fiber optic coupler. The output end of the high - speed optical transmitter driver is connected to the input end of the optical transmitter.

[0022] Among them, the laser driver is composed of a DCDC chip that adjusts the output current through a current - sensing resistor feedback to form a constant - current power supply. Its circuit schematic diagram is as Figure 2 shown. The maximum output current can reach 5A, and its model is XL4501E1. This chip, in cooperation with external components such as capacitors C2, C4, C5, C3, inductor U5, Schottky diodes D1, D2, etc., converts the 9V voltage input to the system into a constant current of 5A to drive a semiconductor fiber - coupled laser with a driving wavelength of 808nm and an optical power of 2.65W to operate at full power.

[0023] The semiconductor fiber-coupled laser converts electrical energy into 808nm wavelength laser light with an efficiency of 40%.

[0024] The fiber coupler of the FC connector transmits 2.65W of optical power to the fiber group connecting the transmitting side and the receiving side.

[0025] Reference Figure 3 As shown in the circuit schematic diagram, the high-speed optical transmitter driver is composed of the U1 chip TPS54202DDCR, the U4 chip SN74LVC1G14DBVR and the U3 chip SN75451BP and their peripheral circuits. The chip TPS54202DDCR is a 4.5V to 28V input, 2A output, EMI-friendly synchronous buck converter that converts the 9V voltage output by the external power supply into a 5V voltage suitable for logic devices. The chip SN74LVC1G14DBV is a high-speed Schmitt-triggered inverter used to shape the input drive signal and overcome the signal inversion effect of the optical transceiver; the chip SN75451BP is a high-speed and high-current drive driver that provides up to 400mA of current to the optical transmitter to enable it to act quickly. These three chips and their external circuits constitute the high-speed optical transmitter driver.

[0026] The optical transmitter receives the electrical signal driven by the high-speed optical transmitter and converts it into an optical signal, which is then transmitted to the optical fiber group connecting the transmitting side and the receiving side.

[0027] The optical fiber group includes quartz power optical fiber and plastic signal optical fiber. Both the quartz power optical fiber and the plastic signal optical fiber have FC connectors. The input end of the quartz power optical fiber is connected to the output end of the optical fiber coupler of the FC connector, and the input end of the plastic signal optical fiber is connected to the output end of the optical transmitter.

[0028] Among them, the quartz power fiber of the FC connector has the advantage of low loss, and the fiber coupler connected to the FC connector is used to transmit optical power. The plastic signal fiber has the advantages of small size and low cost and is used to connect optical transmitters to transmit optical signals that are not sensitive to loss. The quartz power fiber and plastic signal fiber of the FC connector are two insulated optical fibers that can be extended arbitrarily, which plays the role of transmitting energy and signals, eliminating common mode interference, and providing infinitely high withstand voltage.

[0029] The receiving side includes a beam expander, a laser battery, a 5V boost IC, a 25V boost IC, an optical receiver, a non-isolated drive IC, and a push-pull current-boosting circuit. The output end of the quartz power fiber is connected to the laser battery through the beam expander. The output end of the laser battery is sequentially connected to the 5V boost IC and the 25V boost IC. The output ends of the 5V boost IC and the 25V boost IC are both connected to the input end of the push-pull current-boosting circuit. The output end of the plastic signal fiber is connected to the input end of the optical receiver. The output end of the optical receiver is connected to the input end of the non-isolated drive IC. The output end of the non-isolated drive IC is connected to the input end of the push-pull current-boosting circuit. The push-pull current-boosting circuit is provided with three ports for outputting a power drive signal. Among them, the push-pull current-boosting circuit includes a push-pull circuit, a decoupling capacitor bank, and a low-parasitic-inductance trace. The push-pull circuit includes three pairs of triodes. The decoupling capacitor bank includes 18 MLCC capacitors, and the 18 MLCC capacitors are distributed on the three ports of the push-pull current-boosting circuit in a ratio of 1:1:1.

[0030] Among them, the beam expander equalizes the light intensity of the laser beam transmitted by the quartz power fiber of the FC connector and reduces the beam divergence angle to almost 0. Local overheating caused by uneven light intensity is avoided.

[0031] The laser battery is a gallium arsenide laser battery with a photosensitive area of 1 cm 2 , which converts light energy into electrical energy with an efficiency of 38%, and its normal operating output voltage is 2V.

[0032] Refer to Figure 4 the shown circuit schematic diagram. The model of the 5V boost IC is TPS61022, which is an 8A boost converter with an ultra-low input voltage of 0.5V. Its function is to convert the 2V output voltage of the gallium arsenide laser battery into 5V to provide power input for the subsequent 25V boost IC and optical receiver, and provide a -5V gate negative bias voltage.

[0033] The model of the 25V boost IC is TPS61040DBVR, which is a boost converter with an adjustable output voltage range up to 28V. Its function is to boost the output voltage of the 5V boost IC to 25V to supply power to the subsequent non-isolated drive IC and push-pull current-boosting circuit and provide a 20V gate positive bias voltage, achieving a driving power of 0.8W, which is sufficient to drive a 6.5kV 25A high-voltage SiC MOSFET module to work at a switching frequency above 100kHz, making the present invention have considerable driving ability.

[0034] The model of the optical receiver is HFBR-2521Z. It receives the optical signal transmitted by the plastic optical fiber, converts it into an electrical signal of 5V, and transmits the signal to the non-isolated drive IC.

[0035] The model of the non-isolated drive IC is UCC27531D, which is a single-channel high-speed gate driver with a maximum voltage of 35V and a maximum current of 5A. Its function is to convert a 5V drive electrical signal into a 25V drive electrical signal and perform preliminary current amplification to drive the push-pull current-boosting circuit to work.

[0036] The push-pull circuit of the push-pull current-boosting circuit includes three pairs of triodes Q1~Q6. The models of the triodes are 2SC5569 and 2SA2016 respectively. These two types of triodes Q1~Q6 have a continuous current output capacity of 7A and an extremely low time delay of 30ns, providing sufficient current output capacity to drive the SiC MOSFET well. The decoupling capacitor bank includes 18 10uF MLCC capacitors, with the model GRM21BR61H106KE43L, and is distributed on the three ports of the push-pull current-boosting circuit in a 1:1:1 ratio, greatly reducing the power supply impedance, reducing the influence of the power supply impedance on the drive waveform, and improving the drive waveform accuracy. The low-parasitic inductance traces use techniques such as mutual inductance cancellation and self-inductance reduction to greatly reduce the inductance of the trace parasitic inductance, as low as 1.17nH, reducing the influence of the trace parasitic inductance on the drive waveform and improving the drive waveform accuracy. The 25V drive electrical signal output by the non-isolated drive IC completes current amplification through the push-pull current-boosting circuit and becomes a drive signal with sufficient current drive ability and high waveform accuracy to drive the SiC MOSFET to work.

[0037] The transmitting side of a fully fiber-optic isolated SIC MOSFET gate driver suitable for ultra-high voltage is 6cm long, 6cm wide, and 6cm high, and the receiving side is 6.5cm long, 4cm wide, and 6cm high, with a small volume; the lengths of the power fiber and the signal fiber are both 1m, which can effectively isolate voltage and common-mode interference. Refer to Figure 4 For the double-pulse test of this gate driver, the double-pulse test is used to test the switching transient characteristics of the drive, and the load inductance used is 4mH. During the test, a fully fiber-optic isolated SiC MOSFET gate driver disclosed in the present invention is used to apply the drive signal between the gate and source electrodes of the upper tube, and the gate and source electrodes of the lower tube are short-circuited with tin wire, and the busbar voltage is set to 4kV. A double-pulse drive signal of 7us-3us-3us is output by the signal generator, the drive voltage is +20V, -5V, and the drive resistance is 1.1Ω.

[0038] In the double-pulse experiment of the upper tube at 4kV, when using a fully fiber-optic isolated SIC MOSFET gate driver suitable for ultra-high voltage in the present invention to drive a 6.5kV silicon carbide MOSFET module, dv / dt reached 110V / ns, and the drive waveform quality was excellent. The rising edge of the drive waveform was only 62ns (as shown in Figure 5 ), and the falling edge was only 78ns (as shown in Figure 6), without gate voltage oscillation, the driving characteristics are close to ideal driving, and it has the ability to be competent for high-performance requirements such as multi-chip series modules or high-voltage multi-level topologies.

[0039] The present invention also discloses an application of a fully fiber-optic isolated SiC MOSFET gate driver suitable for ultra-high voltage in a multi-chip series module or a high-voltage multi-level topology. The above are only the preferred embodiments of the present invention and are not used to limit the technical solutions of the present invention. Those skilled in the art should understand that without departing from the spirit and principles of the present invention, the technical solutions can be subject to several simple modifications and substitutions, and these modifications and substitutions also fall within the protection scope covered by the claims.

Claims

1. An all-fiber isolated SiC MOSFET gate driver suitable for ultra-high voltage, characterized in that: It includes a transmitting side, an optical fiber group and a receiving side which are connected in sequence, the transmitting side includes a constant current laser driver, a semiconductor optical fiber coupled laser, an optical fiber coupler of an FC connector, a high-speed optical transmitter driver and an optical transmitter, the input end of the constant current laser driver and the input end of the high-speed optical transmitter driver are both connected to an external output voltage, the output end of the constant current laser driver is connected to the input end of the semiconductor optical fiber coupled laser, the output end of the semiconductor optical fiber coupled laser is connected to the input end of the optical fiber coupler of the FC connector, and the output end of the high-speed optical transmitter driver is connected to the input end of the optical transmitter; The optical fiber group includes a quartz power optical fiber with an FC connector and a plastic signal optical fiber, the input end of the quartz power optical fiber is connected to the output end of the optical fiber coupler with the FC connector, and the input end of the plastic signal optical fiber is connected to the output end of the optical transmitter; The receiving side includes a beam expander, a laser battery, a 5V boost IC, a 25V boost IC, an optical receiver, a non-isolated driver IC, and a push-pull current expansion circuit. The output end of the quartz power optical fiber is connected to the laser battery through the beam expander. The output end of the laser battery is connected to the 5V boost IC and the 25V boost IC in sequence. The output ends of the 5V boost IC and the 25V boost IC are both connected to the input end of the push-pull current expansion circuit. The output end of the plastic signal optical fiber is connected to the input end of the optical receiver, the output end of the optical receiver is connected to the input end of the non-isolated driver IC, the output end of the non-isolated driver IC is connected to the input end of the push-pull current expansion circuit, and the push-pull current expansion circuit is provided with three output ports for outputting power driving signals.

2. The all-fiber isolated SiC MOSFET gate driver suitable for ultra-high voltage according to claim 1, characterized in that: The maximum output current of the constant current laser driver is 5A.

3. The all-fiber isolated SiC MOSFET gate driver suitable for ultra-high voltage according to claim 1, characterized in that: The laser wavelength of the semiconductor fiber-coupled laser is 808nm and the optical power is 2.65W.

4. The all-fiber isolated SiC MOSFET gate driver suitable for ultra-high voltage according to claim 1, characterized in that: The high-speed optical transmitter is driven with an output current of 400mA.

5. The all-fiber isolated SiC MOSFET gate driver suitable for ultra-high voltage according to claim 1, characterized in that: The laser battery uses a gallium arsenide laser battery, and its normal operating output voltage is 2V.

6. The all-fiber isolated SiC MOSFET gate driver suitable for ultra-high voltage according to claim 1, characterized in that: The push-pull current expansion circuit includes a push-pull circuit, a decoupling capacitor group and a low parasitic inductance routing. The push-pull circuit includes three pairs of transistors. The decoupling capacitor group includes 18 MLCC capacitors, and the 18 MLCC capacitors are distributed on the three output ports of the push-pull current expansion circuit in a ratio of 1:1:

1.

7. The all-fiber isolated SiC MOSFET gate driver suitable for ultra-high voltage according to claim 6, characterized in that: The transistor has a continuous current output capability of 7A and an extremely low delay of 30ns.

8. The all-fiber isolated SiC MOSFET gate driver suitable for ultra-high voltage according to claim 6, characterized in that: The capacity of the MLCC capacitor in the decoupling capacitor group is 10uF.

9. The all-fiber isolated SiC MOSFET gate driver suitable for ultra-high voltage according to claim 6, characterized in that: The inductance of the low parasitic inductance trace is 1.17nH.

10. An application of the all-fiber isolated SiC MOSFET gate driver suitable for ultra-high voltage according to any one of claims 1 to 9 in a multi-chip series module or a high-voltage multi-level topology.

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