Heterogeneous high-power-density T-type three-level converter system based on SiC-bidirectional GaN
By adopting SiC-bidirectional GaN heterogeneous power devices and optimized heat dissipation management in T-type three-level converters, the loss and thermal stress problems of traditional silicon-based converters in high-frequency applications are solved, and high power density and high-efficiency conversion are achieved.
Patent Information
- Application Number
- CN202411694787.6
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-11-25
- Publication Date
- 2025-03-07
AI Technical Summary
Traditional silicon-based T-type three-level inverters have problems such as high conduction loss, limited switching speed, uneven internal and external tube losses and inconsistent thermal stresses in high-frequency applications, which affect system efficiency and reliability.
Using a heterogeneous high-power density T-type three-level inverter system based on SiC-bidirectional GaN, power conversion is realized through SiC MOSFET and bidirectional GaN HEMT. Combining the advantages of SiC and GaN heterogeneous power devices, the loss distribution and heat dissipation management of internal and external tubes are optimized.
It significantly improves the power density and conversion efficiency of the inverter, solves the problems of uneven losses and inconsistent thermal stress of the internal and external pipes, and improves the overall performance and reliability of the system.
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Figure CN119582635A_ABST
Abstract
Description
Technical Field
[0001] The present invention belongs to the technical field of power electronics, and in particular relates to a SiC-bidirectional GaN-based heterogeneous high power density T-type three-level converter system. Background Art
[0002] With the rapid development of technologies such as renewable energy generation, electric transportation, and energy storage systems, the application of power electronic devices has become increasingly widespread, and higher requirements have been put forward for converter systems with high efficiency, high power density, low loss, and high reliability. Due to the high output voltage harmonic content and large switching loss, the traditional two-level converter is difficult to meet the growing technical requirements in high-frequency and high-power applications. In contrast, the three-level topology has gradually become the mainstream technology in high-power applications due to its advantages such as smoother output voltage waveform, low switching loss, and better EMI performance. As a special form of the three-level structure, the T-type three-level topology has obvious structural advantages. It not only inherits the characteristics of low voltage harmonics and low switching loss of the three-level structure, but also improves the power density of the system by reducing the number of switching devices and the volume of inductors. However, the traditional T-type three-level converter based on silicon (Si) power devices still has problems such as high conduction loss, limited switching speed, uneven loss of inner and outer tube devices, and inconsistent thermal stress in high-frequency applications, which affects the efficiency and reliability of the system. Therefore, how to improve the performance of the T-type three-level topology and further improve the efficiency and power density of the system has become the focus of research.
[0003] In recent years, third-generation wide bandgap semiconductor materials, such as silicon carbide (SiC) and gallium nitride (GaN), have gradually attracted widespread attention due to their excellent electrical properties. SiC devices have higher breakdown voltage and lower switching losses, and are suitable for applications in high-voltage and high-power applications; while GaN devices perform well in high-frequency applications due to their extremely low on-state voltage drop and fast switching speed. Combining SiC and GaN heterogeneous devices can effectively solve the limitations of traditional silicon-based power devices, achieve higher switching frequencies and lower losses, and improve the overall performance of the converter. At present, some scholars have studied the application of wide bandgap semiconductor devices SiC and GaN in power electronic converters, showing good performance improvement effects. However, how to better combine the advantages of SiC and GaN in practical applications is still a technical problem that needs to be solved urgently.
[0004] Therefore, there is an urgent need for a converter system that can improve the thermal imbalance problem of the inner and outer tubes of a T-type three-level converter, and improve the power density and reliability of the three-level converter. Based on this demand, the present invention discloses a heterogeneous high power density T-type three-level converter system based on SiC-bidirectional GaN. Summary of the invention
[0005] In order to solve the above-mentioned problems, the present invention proposes: a heterogeneous high power density T-type three-level converter system based on SiC-bidirectional GaN, comprising an input module, a T-type three-level topology main circuit, a control module, a heat dissipation management module and an output module, wherein the input module, the T-type three-level topology main circuit, the control module, the heat dissipation management module and the output module are connected in sequence.
[0006] Furthermore, the input module receives a DC input power supply and provides a stable voltage U dc .
[0007] Furthermore, the T-type three-level topology main circuit realizes power conversion through SiC MOSFET and bidirectional GaN-HEMT; the topology structure of the converter system adopts SiC-bidirectional GaN heterogeneous T-type three-level topology structure, including the following components: upper bridge arms Sa1, Sb1, Sc1 and lower bridge arms Sa2, Sb2, Sc2, each bridge arm is composed of a switch device and a diode connected in reverse parallel, Sa1, Sb1, Sc1 and Sa2, Sb2, Sc2 are the outer tubes of the T-type three-level; the midpoint switch tubes Sam, Sbm, Scm are connected to the midpoint of the bridge arm, Sam, Sbm, Scm are the inner tubes of the T-type three-level; the output voltage of the T-type three-level topology structure has three level states: positive voltage, intermediate voltage, and negative voltage; the outer tube selects SiC MOSFET as the outer switch device, and the inner tube selects bidirectional GaN HEMT as the inner switch device; the converter system also includes a filter capacitor C, a filter inductor L and a midpoint split capacitor U dc1 , U dc2 , a midpoint splitting capacitor U is set between the midpoint of the bridge arm and the upper bridge arm dc1 , a midpoint splitting capacitor U is set between the midpoint of the bridge arm and the lower bridge arm dc2 , a DC input power supply U is set between the upper bridge arm and the lower bridge arm dc , filter capacitors C and filter inductors L are set on the three output branches of the midpoint switch tubes Sam, Sbm, and Scm, and then connected to the three-phase load.
[0008] Furthermore, the control module is implemented using a digital signal processor DSP and a field programmable gate array FPGA. The DSP generates three-phase modulation signals ma, mb, and mc, and transmits the modulation signals to the FPGA. The FPGA completes carrier comparison and generates a pulse signal, which is processed by reverse and dead time to provide a driving signal for each switching device.
[0009] Furthermore, the inverter system also integrates overvoltage, overcurrent and overtemperature circuits.
[0010] Furthermore, the heat dissipation management module adopts fan cooling. By selecting high thermal conductivity materials and heat dissipation channel design, the high-temperature inner tube device is designed to be closer to the air outlet, and the lower-loss outer tube is farther away from the air duct.
[0011] Furthermore, the output module provides a stable AC output by connecting to a filter circuit to provide energy for the load.
[0012] Furthermore, the bidirectional GaN power switch structure adds a polarization junction structure at the drain end, acting as a diode in the GaN-based bidirectional blocking HEMT. The drain end is connected to the ohmic electrode on the polarization junction, and the forward current is composed of the ohmic current at the drain end and the pn junction current.
[0013] Furthermore, a buffer layer, an i-GaN channel layer, a barrier layer, an i-GaN spacer layer, a p-type semiconductor layer and a heavily doped p-type semiconductor layer are sequentially epitaxially grown on the substrate; a polarization junction structure is formed at the gate end and the drain end respectively, and an electric field control electrode B1 and an electric field control electrode B2 are formed in ohmic contact with the 2DHG region through a p-type semiconductor; the gate metal is in direct contact with the polarization junction where the electric field control electrode B1 is located, and the drain metal is in direct contact with the polarization junction where the electric field control electrode B2 is located; the source and the drain are in ohmic contact with the 2DEG channel below; the gate part adopts two schemes: a recessed gate MIS structure and a p-type gate structure; at the gate end and the drain end, polarization junction structures are formed by etching respectively, and ohmic contacts B1 and B2 are formed with the 2DHG above them through a p-type semiconductor; at the i-GaN / barrier layer interface The δ doping of n-type Si is introduced, and at the same time, in order to form a charge balance with the n-type doping, the p-type semiconductor is thickened, and a heavily doped p-type semiconductor layer is added to form an ohmic contact, and a polarized superjunction is realized at the same time; the drain is connected to the electrode B2 through a metal interconnect, and the additional drain-end ohmic current reduces the turn-on voltage; at the same time, in the on state, the B2 electrode injects holes to enhance the concentration of the 2DEG below and increase the current density; when the device is turned off, the current from the source S to the drain D is blocked due to the barrier formed by the polarization junction where B2 is located, and the electric field regulation effect of the polarization junction improves the reverse withstand voltage; the gate or source is connected to the electrode B1 through a metal interconnect; when the device is turned off, by synchronously adjusting the B1 voltage, a flat electric field distribution is formed under the polarization junction where it is located, thereby blocking the current from the drain D to the source S, thereby improving the forward withstand voltage.
[0014] The beneficial effects of the present invention are:
[0015] The invention provides a heterogeneous high power density T-type three-level converter system based on SiC-bidirectional GaN. By combining the advantages of SiC and GaN heterogeneous power devices, it solves the problems of uneven power device loss, large junction temperature deviation, and insufficient system reliability in the existing T-type three-level converter system. The system improves the power density and conversion efficiency of the converter, making the system stable under high-frequency operation, and is suitable for high-demand application scenarios such as electric transportation, energy storage systems, and new energy power generation.
[0016] (1) T-type three-level topology. This system adopts a T-type three-level topology. Compared with the traditional two-level and three-level topologies, this structure reduces the number of switching devices while significantly reducing the harmonic content and switching loss of the output voltage, thereby improving the conversion efficiency and power quality of the system.
[0017] (2) A heterogeneous device combination of SiC and GaN, with silicon carbide (SiC) MOSFET as the external switch device and bidirectional gallium nitride (GaN) HEMT as the internal switch device. SiC devices have high voltage resistance and low switching loss, and are suitable for withstanding the high voltage stress of the system; while GaN devices have extremely low on-state voltage drop and faster switching speed, which can effectively reduce conduction losses. At the same time, bidirectional GaN devices have bidirectional conductivity and can conduct electricity in both directions. This heterogeneous device combination gives full play to the respective advantages of SiC and GaN power devices, achieving a smaller loss deviation of the T-type three-level internal and external switch tubes, and improving the overall efficiency of the system.
[0018] Compared with the prior art, the technical solution of the present invention has the following beneficial effects:
[0019] 1. By utilizing the bidirectional conduction and bidirectional blocking characteristics of bidirectional GaN devices, the number of intermediate bridge arm switches in a single bridge arm of a T-type three-level converter can be reduced from 4 to 1, greatly reducing the number of system components and improving system power density and efficiency.
[0020] 2. The low on-state voltage drop and zero reverse recovery loss characteristics of GaN power devices can significantly reduce conduction loss and switching loss at high switching speeds, thereby improving the conversion efficiency and reliability of the system.
[0021] 3. By optimizing the loss distribution of internal and external tubes and the design of the heat dissipation management module, this system achieves consistent management of the junction temperature of power devices, prevents local overheating, and improves the service life of the devices.
[0022] 4. Through the collaborative work of SiC and GaN heterogeneous devices, this system can still maintain high power density and small volume under high-frequency operation, and is suitable for applications with high power density requirements. BRIEF DESCRIPTION OF THE DRAWINGS
[0023] Figure 1 This is a topological structure diagram of the SiC-bidirectional GaN heterogeneous high power density T-type three-level converter proposed in the present invention;
[0024] Figure 2 This is a schematic diagram of the heat dissipation structure of the heterogeneous high power density T-type three-level converter proposed in the present invention;
[0025] Figure 3 This is a schematic diagram of a control unit of a heterogeneous high power density T-type three-level converter proposed in the present invention;
[0026] Figure 4 The equivalent circuit diagram and working mode diagram of the bidirectional GaN power device in the heterogeneous high power density T-type three-level converter proposed in the present invention, wherein (a) is the equivalent circuit diagram of the bidirectional GaN device, and (b) is the working mode diagram of the bidirectional GaN device;
[0027] Figure 5 A schematic diagram of the internal structure of a bidirectional GaN power device in a heterogeneous high power density T-type three-level converter proposed in the present invention;
[0028] Figure 6 This is a schematic diagram of the control system of the heterogeneous high power density T-type three-level converter proposed in the present invention.
[0029] 1. Clark transform module, 2. Controller, 3. Decoupling control module, 4. Feedforward module, 5. Inverse Clark transform, 6. PWM wave generation module. DETAILED DESCRIPTION
[0030] Example 1
[0031] In order to make the technical means and objectives of the present invention easy to understand, the present invention is further described below in combination with specific embodiments. A heterogeneous high power density T-type three-level converter system based on SiC-bidirectional GaN, such as Figure 1 As shown, it includes an input module, a T-type three-level topology main circuit, a control module, a heat dissipation management module and an output module, and the input module, the T-type three-level topology main circuit, the control module, the heat dissipation management module and the output module are connected in sequence.
[0032] The input module receives a DC input power supply and provides a stable voltage U dc .
[0033] The T-type three-level topology main circuit realizes power conversion through SiC MOSFET and bidirectional GaN-HEMT; the topology structure of the converter system adopts SiC-bidirectional GaN heterogeneous T-type three-level topology structure, including the following components: upper bridge arms Sa1, Sb1, Sc1 and lower bridge arms Sa2, Sb2, Sc2, each bridge arm is composed of a switch device and a diode connected in reverse parallel, Sa1, Sb1, Sc1 and Sa2, Sb2, Sc2 are the outer tubes of the T-type three-level; the midpoint switch tubes Sam, Sbm, Scm are connected to the midpoint of the bridge arm, and Sam, Sbm, Scm are the inner tubes of the T-type three-level; the output voltage of the T-type three-level topology structure has three level states: positive voltage, intermediate voltage, and negative voltage; the outer tube selects SiC MOSFET as the outer switch device, and the inner tube selects bidirectional GaNHEMT as the inner switch device; the converter system also includes a filter capacitor C, a filter inductor L and a midpoint split capacitor U dc1 , U dc2 , a midpoint splitting capacitor U is set between the midpoint of the bridge arm and the upper bridge arm dc1 , a midpoint splitting capacitor U is set between the midpoint of the bridge arm and the lower bridge arm dc2 , a DC input power supply U is set between the upper bridge arm and the lower bridge arm dc , filter capacitors C and filter inductors L are set on the three output branches of the midpoint switch tubes Sam, Sbm, and Scm, and then connected to the three-phase load.
[0034] The system adopts a T-type three-level topology structure. The external switch device is SiC-MOSFET, and the internal switch device is a bidirectional GaN-HEMT. By combining the advantages of SiC and GaN heterogeneous power devices, the high voltage tolerance of SiC devices and the low conduction voltage drop characteristics of GaN devices are fully utilized to achieve balanced distribution of losses between internal and external tubes, reduce loss deviation, and improve the thermal management performance and overall operation reliability of the converter.
[0035] The external switch device is SiC-MOSFET, which is used to withstand the high voltage of the DC bus and has the characteristics of low switching loss. The internal switch device is a bidirectional GaN-HEMT, which uses its bidirectional conduction and bidirectional blocking characteristics to reduce the number of power devices. At the same time, the low conduction voltage drop of GaN devices is used to reduce conduction losses and improve system efficiency.
[0036] Among them, Figure 3 As shown, the control module is implemented using a digital signal processor DSP and a field programmable gate array FPGA. The DSP generates three-phase modulation signals ma, mb, and mc, and transmits the modulation signals to the FPGA. The FPGA completes carrier comparison and generates a pulse signal. After the pulse signal is processed by reverse and dead time, it provides a driving signal for each switching device.
[0037] Ga1 and Ga2 are two signals of the GaN bidirectional switch in bridge arm a, Ga3 is the switch signal of the upper SiC MOSFET in bridge arm, and Ga4 is the switch signal of the lower SiC MOSFET in bridge arm. The same is true for bridge arm b and bridge arm c.
[0038] Among them, the inverter system also integrates overvoltage, overcurrent and overtemperature circuits.
[0039] Among them, Figure 2 As shown, the heat dissipation management module adopts fan cooling. By selecting high thermal conductivity materials and heat dissipation channel design, the high-temperature inner tube device is designed to be closer to the air outlet, and the lower-loss outer tube is farther away from the air duct.
[0040] The output module provides a stable AC output by connecting to a filter circuit to provide energy for the load.
[0041] Example 2
[0042] This invention patent involves a high power density T-type three-level converter system based on SiC-bidirectional GaN. Through the combination of T-type three-level topology and SiC and GaN heterogeneous devices, it aims to optimize the performance of the converter and improve the system efficiency and reliability. The specific steps are as follows:
[0043] (1) See Appendix Figure 1 , which is a SiC-bidirectional GaN heterogeneous T-type three-level topology structure. The topology of the converter system of the present invention patent includes the following components:
[0044] Upper bridge arms Sa1, Sb1, Sc1 and lower bridge arms Sa2, Sb2, Sc2: Each bridge arm is composed of a switch device and a diode connected in reverse parallel, which are used to control the direction of current flow. Among them, Sa1, Sb1, Sc1 and Sa2, Sb2, Sc2 are also called T-type three-level external tubes;
[0045] Midpoint switch tubes Sam, Sbm, and Scm: connected to the midpoint of the bridge arm, used to realize the output of different level voltages of the three-level converter. Among them, Sam, Sbm, and Scm are also called the inner tubes of the T-type three-level. The output voltage of the T-type three-level topology has three level states (positive voltage, intermediate voltage, and negative voltage). Compared with the traditional two-level structure, it can significantly reduce the output voltage harmonics and reduce switching losses.
[0046] (2) See Appendix Figure 1 , a combination of SiC and GaN heterogeneous devices, the external switch tube selects silicon carbide (SiC) MOSFET as the external switch device. SiC has the characteristics of high voltage resistance and low switching loss, suitable for withstanding high voltage stress. The external tube carries the high voltage operation of the system and reduces the switching loss during the switching process;
[0047] The internal switch tube selects bidirectional gallium nitride (GaN) HEMT as the internal switch device. On the one hand, the bidirectional GaN device has the characteristics of bidirectional conduction and bidirectional blocking, and can conduct and cut off in both the forward and reverse directions, which enables it to achieve flexible current control in the middle bridge arm of the T-type three-level topology. At the same time, GaN devices have the characteristics of low conduction voltage drop and high switching speed, which effectively reduces conduction loss. The internal switch device is responsible for low-voltage operation, and because the conduction voltage drop of GaN devices is much lower than that of traditional silicon-based devices, it can further reduce system losses under the same conditions;
[0048] The combination of SiC and GaN minimizes the loss deviation of the inner and outer tubes in the T-type three-level topology while improving the overall efficiency by fully leveraging the high withstand voltage and low switching loss advantages of SiC devices under high voltage conditions and the low on-state voltage drop advantage of GaN devices under low voltage conditions.
[0049] (3) Filter capacitors and inductors: The converter system also includes filter capacitors and filter inductors, which are used to smooth the output voltage waveform and reduce voltage and current ripples. In addition, the midpoint split capacitor can stabilize the midpoint potential during the three-level conversion process, and the inductor can reduce the harmonic component and improve the quality of the output waveform.
[0050] (4) See Appendix Figure 2 , is the layout diagram of the heat sink module and each device. The inverter system integrates an efficient heat sink module. By selecting high thermal conductivity materials and optimizing the heat dissipation channel design, the high-temperature inner tube device is designed to be closer to the air outlet, and the lower-loss outer tube is farther away from the air duct, further improving the heat dissipation capacity of the system. Under high-power operation, the heat sink module effectively reduces the heat accumulation on the device surface, ensuring the thermal stability of the system during long-term operation;
[0051] (5) See Appendix Figure 3 , is the inverter system controller, equipped with a digital signal processor (DSP) and a field programmable gate array (FPGA) control module; this module can monitor the key parameters of the system such as input voltage, output current, power factor and temperature in real time, and use DSP to implement feedback control algorithm based on these data to obtain three-phase debugging signals ma, mb, mc, and then use FPGA to control the switching pulses, dead time and switching frequency of internal and external switching devices, and further obtain the driving signals of 9 power devices. In addition, the control system can also respond quickly when the load changes to ensure stable operation of the system.
[0052] (6) Inverter overvoltage and overcurrent control: To ensure the safety of the system, the inverter system of the present invention is equipped with multiple protection functions, including:
[0053] Overvoltage protection: When the system input voltage or output voltage exceeds the safe range, the control system will quickly shut down the converter to prevent damage to the power devices;
[0054] Overcurrent protection: When the system output current exceeds the rated value, the control system will activate the overcurrent protection function to prevent device damage or line short circuit caused by excessive current;
[0055] Over-temperature protection: When it is detected that the junction temperature of the SiC or GaN device exceeds the set threshold, the system will automatically reduce the switching frequency or directly shut down the converter to ensure device safety.
[0056] (7) See Appendix Figure 4 (a), the structural feature of the bidirectional GaN power switch is the addition of a polarized junction structure at the drain end, which acts as a diode in the GaN-based bidirectional blocking HEMT, and has a higher reverse breakdown voltage compared to the GaN bidirectional power device embedded in the drain end in the prior art. The polarized junction structure at the gate and drain ends is used to adjust and optimize the electric field distribution to make it close to a flat rectangular distribution, thereby improving the bidirectional withstand voltage performance, while maintaining a low on-resistance while increasing the device breakdown voltage. The drain end is connected to the ohmic electrode on the polarized junction, and the forward current is composed of the ohmic current at the drain end and the pn junction current. The additional drain ohmic current helps to reduce the turn-on voltage, and when turned on, the ohmic electrode on the polarized junction injects holes, thereby enhancing the concentration of the 2DEG region below and increasing the current density. See Appendix Figure 4 (b) When both G1 and G2 are turned on, the bidirectional switch will operate in a bidirectional conduction mode, capable of conducting current in both forward and reverse directions. When G1 is turned on and G2 is turned off, the bidirectional switch will operate in a forward blocking and reverse conduction mode, capable of conducting reverse current and blocking forward voltage. When G2 is turned on and G1 is turned off, the bidirectional switch will operate in a forward conduction and reverse blocking mode. When both G1 and G2 are turned off, the bidirectional switch will operate in a bidirectional blocking mode, capable of blocking forward and reverse voltages.
[0057] (8) See Appendix Figure 5, schematic diagram of the structure of a bidirectional GaN power switch, the substrate material can be selected from silicon, silicon carbide, sapphire, GaN or diamond, etc. Based on the substrate, a GaN buffer layer, an i-GaN channel layer, an i-AlGaN barrier layer, an i-GaN spacer layer, a p-type semiconductor layer and a heavily doped p-type semiconductor layer are epitaxially grown in sequence. The source and drain form ohmic contacts with the 2DEG channel below. The gate part adopts two schemes: a recessed gate MIS structure and a p-type gate structure to realize a normally-off device. At the gate and drain ends, polarized junction structures are formed by etching respectively, aiming to improve the trade-off between breakdown voltage and on-resistance, and ohmic contacts B1 and B2 are formed with 2DHG through a p-type semiconductor above it. The polarized junction at the drain end is not only used to adjust the electric field distribution, but also acts as a diode in a bidirectional blocking HEMT, which helps to increase the reverse breakdown voltage. In order to enhance the density of 2DEG, n-type Si delta doping is introduced at the interface of i-GaN / barrier layer. At the same time, in order to form charge balance with the n-type doping, the p-type semiconductor is thickened compared with the traditional design, and a heavily doped p-type semiconductor layer is added to form an ohmic contact, thereby achieving the effect of polarization super junction. The drain is connected to the electrode B2 through metal interconnection, and the additional drain-end ohmic current helps to effectively reduce the turn-on voltage; at the same time, in the on state, the B2 electrode injects holes, thereby enhancing the concentration of the 2DEG below and increasing the current density (if the drain and B2 are regulated separately, this function can be achieved independently). When the device is turned off, the current from the source S to the drain D is blocked due to the barrier formed by the polarization junction where B2 is located, and the electric field regulation effect of the polarization junction can improve the reverse withstand voltage. The gate or source is connected to the electrode B1 through metal interconnection. When the device is turned off, by synchronously adjusting the B1 voltage, a flat electric field distribution is formed under the polarization junction where it is located, thereby blocking the current from the drain D to the source S, thereby improving the forward withstand voltage.
[0058] (9) See Appendix Figure 6, is the control principle diagram of T-type three-level inverter. First, the three-phase load current is sampled and the d-axis and q-axis currents are obtained through Clark transformation. Then, the d-axis and q-axis currents are adjusted by controllers with reference currents i*d and i*q, which can be PI controllers, repetitive controllers or other controllers to obtain adjusted signals. After being processed by the decoupling and feedforward modules, the signals are generated by Clark inverse transformation and modulation modules to generate 12 duty cycle signals of 9 switch tubes, among which the dead time needs to be added between the complementary switch signals. The switch signals of the upper and lower tubes of the bridge arm are complementary. Each bidirectional GaN switch device requires two drive signals, and the two switch signals are complementary to the upper and lower tubes of the outer tube, respectively. Taking phase A as an example, the upper and lower tube drive signals Ga3 and Ga4 of the outer tube are complementary and symmetrical, the inner tube drive signal Ga1 is complementary and symmetrical to the upper tube drive signal Ga3 of the outer tube, and the inner tube drive signal Ga2 is complementary and symmetrical to the lower tube drive signal Ga4 of the outer tube. The upper and lower tube drives directly need to increase the dead time, and the bidirectional GaN power switch and SiC MOSFET. Finally, the inverter output is connected to the three-phase load through the filter.
[0059] The above description is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can make equivalent replacements or changes according to the technical solutions and concepts of the present invention within the technical scope disclosed by the present invention, which should be covered by the protection scope of the present invention.
Claims
1. A heterogeneous high power density T-type three-level converter system based on SiC-bidirectional GaN, characterized in that: It includes an input module, a T-type three-level topology main circuit, a control module, a heat dissipation management module and an output module, which are connected in sequence.
2. The SiC-bidirectional GaN-based heterogeneous high power density T-type three-level converter system according to claim 1, characterized in that: The input module receives a DC input power supply and provides a stable voltage U dc .
3. The SiC-bidirectional GaN-based heterogeneous high power density T-type three-level converter system according to claim 1, characterized in that: The T-type three-level topology main circuit realizes power conversion through SiC MOSFET and bidirectional GaN-HEMT; the topology structure of the converter system adopts SiC-bidirectional GaN heterogeneous T-type three-level topology structure, including the following components: upper bridge arms Sa1, Sb1, Sc1 and lower bridge arms Sa2, Sb2, Sc2, each bridge arm is composed of a switch device and a diode connected in reverse parallel, Sa1, Sb1, Sc1 and Sa2, Sb2, Sc2 are the outer tubes of the T-type three-level; the midpoint switch tubes Sam, Sbm, Scm are connected to the midpoint of the bridge arm, Sam, Sbm, Scm are the inner tubes of the T-type three-level; the output voltage of the T-type three-level topology structure has three level states: positive voltage, intermediate voltage, and negative voltage; the outer tube selects SiC MOSFET as the outer switch device, and the inner tube selects bidirectional GaNHEMT as the inner switch device; the converter system also includes a filter capacitor C, a filter inductor L and a midpoint split capacitor U dc1 , U dc2 , a midpoint splitting capacitor U is set between the midpoint of the bridge arm and the upper bridge arm dc1 , a midpoint splitting capacitor U is set between the midpoint of the bridge arm and the lower bridge arm dc2 , a DC input power supply U is set between the upper bridge arm and the lower bridge arm dc , filter capacitors C and filter inductors L are set on the three output branches of the midpoint switch tubes Sam, Sbm, and Scm, and then connected to the three-phase load.
4. The SiC-bidirectional GaN-based heterogeneous high power density T-type three-level converter system according to claim 3, characterized in that: The control module is implemented using a digital signal processor DSP and a field programmable gate array FPGA. The DSP generates three-phase modulation signals ma, mb, and mc, and transmits the modulation signals to the FPGA. The FPGA completes carrier comparison and generates a pulse signal, which is processed by reverse and dead time to provide a driving signal for each switching device.
5. The SiC-bidirectional GaN-based heterogeneous high power density T-type three-level converter system according to claim 4, characterized in that: The inverter system also integrates overvoltage, overcurrent and overtemperature circuits.
6. The SiC-bidirectional GaN based heterogeneous high power density T-type three-level converter system according to claim 1, characterized in that: The heat dissipation management module adopts fan cooling to dissipate heat. By selecting high thermal conductivity materials and designing heat dissipation channels, the high-temperature inner tube device is designed to be closer to the air outlet, and the lower-loss outer tube is farther away from the air duct.
7. The SiC-bidirectional GaN-based heterogeneous high power density T-type three-level converter system according to claim 1, characterized in that: The output module provides a stable AC output by connecting to a filter circuit to provide energy for the load.
8. The SiC-bidirectional GaN-based heterogeneous high power density T-type three-level converter system according to claim 3, characterized in that: The bidirectional GaN power switch structure adds a polarization junction structure at the drain end, acting as a diode in the GaN-based bidirectional blocking HEMT. The drain end is connected to the ohmic electrode on the polarization junction, and the forward current is composed of the ohmic current at the drain end and the pn junction current.
9. The SiC-bidirectional GaN-based heterogeneous high power density T-type three-level converter system according to claim 8, characterized in that: A buffer layer, an i-GaN channel layer, a barrier layer, an i-GaN spacer layer, a p-type semiconductor layer and a heavily doped p-type semiconductor layer are sequentially epitaxially grown on the substrate; a polarization junction structure is formed at the gate end and the drain end respectively, and an electric field control electrode B1 and an electric field control electrode B2 are formed to form an ohmic contact with the 2DHG region through the p-type semiconductor; The gate metal is in direct contact with the polarization junction where the electric field control electrode B1 is located, and the drain metal is in direct contact with the polarization junction where the electric field control electrode B2 is located; the source and drain form ohmic contacts with the 2DEG channel below; the gate part adopts two schemes: a recessed gate MIS structure and a p-type gate structure; at the gate end and the drain end, polarization junction structures are formed by etching respectively, and ohmic contacts B1 and B2 are formed with 2DHG through p-type semiconductors above them; n-type Si delta doping is introduced at the i-GaN / barrier layer interface, and at the same time, it is connected to the barrier layer. n-type doping forms charge balance, thickens the p-type semiconductor, and adds a heavily doped p-type semiconductor layer to form an ohmic contact, while realizing a polarized superjunction; the drain is connected to the electrode B2 through a metal interconnect, and the additional drain-end ohmic current reduces the turn-on voltage; at the same time, in the on state, the B2 electrode injects holes to enhance the concentration of the 2DEG below and increase the current density; when the device is turned off, the current from the source S to the drain D is blocked due to the barrier formed by the polarization junction where B2 is located, and at the same time, the electric field regulation effect of the polarization junction improves the reverse withstand voltage; The gate or source is connected to the electrode B1 through metal interconnection; when the device is turned off, the B1 voltage is adjusted synchronously to form a flat electric field distribution under the polarization junction where it is located, thereby blocking the current from the drain D to the source S, thereby improving the forward withstand voltage.