Design of isolated silicon carbide H-bridge circuit

Abstract

The invention provides a design of an isolated silicon carbide H-bridge circuit, and relates to the field of circuit design. The design of the isolation silicon carbide H-bridge circuit comprises the steps of SIC power device selection, H-bridge topology design, drive circuit design and isolation design, the SIC power device selects a SiC MOSFET which is at least 600V in withstand voltage, low in on resistance, high in switching speed and suitable for high current and heat dissipation packaging, and in consideration of switching transient voltage spikes, the SIC power device is connected with the H-bridge topology design and the drive circuit design. The H-bridge topology design ensures that the power loop is short and wide, and ensures that sufficient current and voltage can be provided to quickly switch the SiC device. By selecting the SIC power device in the design process, the efficiency of the circuit can be remarkably improved, the energy loss can be reduced, the thermal management requirement can be reduced, by means of the H-bridge topology design, the efficiency of the circuit can be improved, the energy loss can be reduced, the overall performance of the system can be improved, and by means of the design of the driving circuit, the control circuit is protected against the influence of high voltage. The safety and reliability of the system are improved, the fault rate is reduced by using the isolation technology, and the overall reliability is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of circuit design, and in particular to the design of an isolated silicon carbide H-bridge circuit. Background Art

[0002] Silicon carbide (SiC), as a wide bandgap semiconductor material, has been widely used in the field of power electronics due to its advantages such as high thermal conductivity, high breakdown voltage and high temperature stability. The H-bridge circuit is a common power conversion circuit topology that can convert DC to AC or convert between DC levels. The H-bridge circuit usually consists of four switching devices that can control the direction and size of the current, thereby achieving load control.

[0003] Although the prior art uses silicon-based power MOSFET or IGBT as switching devices, silicon-based devices have some limitations in high temperature, high voltage and high frequency applications, such as high on-resistance, slow switching speed and poor thermal stability, which may become a performance bottleneck in certain high-performance applications, such as electric vehicles, solar inverters and industrial drives. Therefore, those skilled in the art provide a design of an isolated silicon carbide H-bridge circuit to solve the problems raised in the above background technology. Summary of the invention

[0004] 1. Technical issues to be resolved

[0005] In view of the deficiencies in the prior art, the present invention provides a design of an isolated silicon carbide H-bridge circuit, which solves the problem of significantly improving the efficiency of the circuit, reducing energy loss, protecting the control circuit from high voltage, and improving the safety and reliability of the system.

[0006] (II) Technical solution

[0007] To achieve the above objectives, the present invention is implemented through the following technical solutions: a design of an isolated silicon carbide H-bridge circuit, including selecting a SIC power device, an H-bridge topology design, a drive circuit design and an isolation design, wherein the SIC power device selects a SiC MOSFET with a withstand voltage of at least 600V, a low on-resistance, a fast switching speed and a package suitable for high current and heat dissipation, taking into account the switching transient voltage spike;

[0008] The H-bridge topology design should ensure that the power loop is short and wide, and that sufficient current and voltage can be provided to quickly switch the SiC device;

[0009] The drive circuit design requires designing an isolated power supply to provide a stable power supply for the drive circuit, selecting a suitable isolated drive chip, and designing over-current, over-voltage and over-temperature protection circuits;

[0010] The isolation design needs to ensure that sufficient current and voltage can be provided to quickly switch the SiC device, and use optocouplers or digital isolators for signal isolation;

[0011] In summary, the SiC MOSFET is C3M0065100K, with a withstand voltage of 1200V, an on-resistance of 65mΩ, and a T0-247 package; the isolation driver chip is ACPL-344JT, the isolated DC-DC converter is B0505S-1W; and the optocoupler is 6N137.

[0012] Preferably, the following formula is used in the process of selecting the SIC power device:

[0013] Switching losses:

[0014] Among them, v ds is the drain-source voltage, I ds Drain-source current, t r and t f ) are the rise and fall time, f sw is the switching frequency;

[0015] Conduction loss:

[0016] Among them, I rms is the rms current, R ds(on) is the on-resistance.

[0017] Preferably, the drive circuit design needs to be protected by the following formula:

[0018] Overvoltage protection threshold: V trip =V max ×1.1 (usually set to 110% of the maximum voltage);

[0019] Overcurrent protection threshold: I trip =I max ×1.2 (usually set to 120% of the maximum current).

[0020] Preferably, the trace width needs to be calculated in the H-bridge topology design, and the following formula is required:

[0021] Trace width:

[0022] Where I is the current, ΔT is the temperature rise, and k and b are constants that depend on the material and thickness.

[0023] Preferably, it comprises four power switches Q1, Q2, Q3 and Q4, four diodes D1, D2, D3 and D4, the capacitor and the DC motor M.

[0024] Preferably, the four power switches adopt bipolar power diodes.

[0025] Preferably, the four diodes are Schottky diodes.

[0026] Working principle: During operation, the power switches Q1 and Q4 are closed, and the power switches Q2 and Q3 are disconnected. At this time, a power supply voltage with positive on the left and negative on the right will be applied to the load of the DC motor M, and the DC motor will rotate forward. Similarly, the power switches Q1 and Q4 are disconnected, and the power switches Q2 and Q3 are closed. The opposite power supply voltage will be applied to the load of the DC motor M, and the DC motor M will reverse. When all four power switches are disconnected, the two ends of the DC motor M are in a suspended state. At this time, the kinetic energy of the rotor of the DC motor M will be gradually consumed under the action of friction, and the motor will slowly stop rotating. When the power switches Q1 and Q3 or Q2 and Q4 are closed, the two ends of the DC motor M will be short-circuited together by the circuit, and the voltage at both ends of the motor is 0. If the DC motor M is working at this time, the rotor kinetic energy of the DC motor M will form a braking current in the external short-circuit circuit loop through the generated reverse electromotive force, and the DC circuit will brake quickly.

[0027] (III) Beneficial effects

[0028] The present invention provides a design of an isolated silicon carbide H-bridge circuit, which has the following beneficial effects:

[0029] 1. By selecting SIC power devices during the design process, choosing the right SiC power devices is the key to achieving efficient and high-density power conversion. SiC devices are known for their high withstand voltage, high switching speed and low on-resistance, which makes them perform well in high temperature and high frequency applications. By selecting the right devices, the efficiency of the circuit can be significantly improved, energy loss can be reduced, and thermal management requirements can be reduced.

[0030] 2. H-bridge topology design is essential to achieve efficient energy conversion. Good design can minimize parasitic inductance and resistance, which directly affect switching loss and electromagnetic interference (EMI). By optimizing layout and routing, the efficiency of the circuit can be improved, energy loss can be reduced, and the overall performance of the system can be improved. The efficiency of the circuit can be improved, energy loss can be reduced, and the overall performance of the system can be improved. The efficiency of the circuit can be improved, energy loss can be reduced, and the overall performance of the system can be improved. The efficiency of the circuit can be improved, energy loss can be reduced, and the overall performance of the system can be improved. The efficiency of the circuit can be improved, energy loss can be reduced, and the overall performance of the system can be improved. The efficiency of the circuit can be improved, energy loss can be reduced, and the overall performance of the system can be improved. High circuit efficiency, reduced energy loss, and improved overall system performance can improve circuit efficiency, reduce energy loss, and improve the overall system performance can improve circuit efficiency, reduce energy loss, and improve the overall system performance can improve circuit efficiency, reduce energy loss, and improve the overall system performance can improve circuit efficiency, reduce energy loss, and improve the overall system performance can improve circuit efficiency, reduce energy loss, and improve the overall system performance can improve circuit efficiency, reduce energy loss, and improve the overall system performance can improve circuit efficiency, reduce energy loss, and improve the overall system performance can improve circuit efficiency, reduce energy loss, and improve the overall system performance can improve circuit efficiency, reduce energy loss, and improve the overall system performance.

[0031] 3. The design of the drive circuit is crucial to ensure fast and reliable switching of SiC devices. An efficient drive circuit can provide sufficient current and voltage to quickly switch the device state while reducing switching losses. The isolation drive technology not only protects the control circuit from high voltage, but also improves the safety and reliability of the system.

[0032] 4. By using isolation technology, isolation technology plays a vital role in the power conversion system. It can not only prevent the high-voltage circuit from interfering with the low-voltage control circuit, but also protect the safety of operators. The use of isolated power supply and signal isolation technology can improve the system's anti-interference ability, reduce the failure rate, and improve overall reliability. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 A schematic diagram of the design process of the present invention;

[0034] Figure 2 This is a working schematic diagram of the invented circuit. DETAILED DESCRIPTION

[0035] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0036] Embodiment 1:

[0037] like Figure 1-2 As shown, an embodiment of the present invention provides a design of an isolated silicon carbide H-bridge circuit, including selecting a SIC power device, an H-bridge topology design, a drive circuit design, and an isolation design. The SIC power device selects a SiC MOSFET with a withstand voltage of at least 600V, a low on-resistance, a fast switching speed, and a package suitable for high current and heat dissipation. Considering the switching transient voltage spike, the SIC power device is selected during the design process. Selecting a suitable SiC power device is the key to achieving efficient and high-density power conversion. SiC devices are known for their high withstand voltage, high switching speed, and low on-resistance, which makes them perform well in high temperature and high frequency applications. By selecting the right device, the efficiency of the circuit can be significantly improved, energy loss can be reduced, and thermal management requirements can be reduced.

[0038] The H-bridge topology design ensures that the power loop is short and wide, and that sufficient current and voltage can be provided to quickly switch SiC devices. The H-bridge topology design is essential for achieving efficient energy conversion. Good design can minimize parasitic inductance and resistance, which directly affects switching losses and electromagnetic interference (EMI). By optimizing layout and routing, the efficiency of the circuit can be improved, energy loss can be reduced, and the overall performance of the system can be improved.

[0039] The drive circuit design needs to design an isolated power supply, provide a stable power supply for the drive circuit, select a suitable isolated drive chip, and design overcurrent, overvoltage and overtemperature protection circuits. The design of the drive circuit is crucial to ensure the fast and reliable switching of SiC devices. An efficient drive circuit can provide sufficient current and voltage to quickly switch the device state while reducing switching losses. Isolation drive technology not only protects the control circuit from high voltage, but also improves the safety and reliability of the system.

[0040] Isolation design needs to ensure that sufficient current and voltage can be provided to quickly switch SiC devices, and use optocouplers or digital isolators for signal isolation. By using isolation technology, isolation technology plays a vital role in power conversion systems. It can not only prevent high-voltage circuits from interfering with low-voltage control circuits, but also protect the safety of operators. Using isolated power and signal isolation technology can improve the system's anti-interference ability, reduce failure rates, and improve overall reliability.

[0041] In summary, the SiC MOSFET is C3M0065100K, with a withstand voltage of 1200V, an on-resistance of 65mΩ, and a TO-247 package; the isolation driver chip is ACPL-344JT, the isolated DC~DC converter is B0505S-1W; and the optocoupler is 6N137.

[0042] The following formula is used in the process of selecting SIC power devices:

[0043] Switching losses:

[0044] Among them, v ds is the drain-source voltage, I ds Drain-source current, t r and t f ) are the rise and fall time, f sw is the switching frequency;

[0045] Conduction loss:

[0046] Among them, I rms is the rms current, R ds(on) is the on-resistance.

[0047] In the design of driving circuit, it is necessary to carry out circuit protection design, and the following formula is needed:

[0048] Overvoltage protection threshold: V trip =V max ×1.1 (usually set to 110% of the maximum voltage);

[0049] Overcurrent protection threshold: I trip =I max ×1.2 (usually set to 120% of the maximum current).

[0050] In H-bridge topology design, the trace width needs to be calculated using the following formula:

[0051] Trace width:

[0052] Where I is the current, ΔT is the temperature rise, and k and b are constants that depend on the material and thickness.

[0053] An isolated silicon carbide H-bridge circuit includes four power switches Q1, Q2, Q3 and Q4, four diodes D1, D2, D3 and D4, a capacitor and a DC motor M. The four power switches use bipolar power diodes, and the four diodes use Schottky diodes. During operation, the power switches Q1 and Q4 are closed, and the power switches Q2 and Q3 are disconnected. At this time, a left positive and right negative power supply voltage will be applied to the DC motor M load, and the DC motor will rotate forward. Similarly, the power switches Q1 and Q4 are disconnected, and the power switches Q2 and Q3 are closed. The DC motor M load will be applied With the opposite power supply voltage, the DC motor M will reverse. When all four power switches are disconnected, the two ends of the DC motor M are in a suspended state. At this time, the kinetic energy of the rotor of the DC motor M will be gradually consumed under the action of friction, and the motor will slowly stop rotating. When the power switches Q1 and Q3 or Q2 and Q4 are closed, the two ends of the DC motor M will be short-circuited together by the circuit, and the voltage across the motor is 0. If the DC motor M is working at this time, the rotor kinetic energy of the DC motor M will form a braking current in the external short-circuit circuit loop through the generated reverse electromotive force, and the DC circuit will brake quickly.

[0054] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A design of an isolated silicon carbide H-bridge circuit, characterized in that: Including the selection of SIC power devices, H-bridge topology design, drive circuit design and isolation design. The SIC power device selects SiC MOSFET with a withstand voltage of at least 600V, low on-resistance, fast switching speed and a package suitable for high current and heat dissipation, taking into account the switching transient voltage spikes; The H-bridge topology design should ensure that the power loop is short and wide, and that sufficient current and voltage can be provided to quickly switch the SiC device; The drive circuit design requires designing an isolated power supply to provide a stable power supply for the drive circuit, selecting a suitable isolated drive chip, and designing over-current, over-voltage and over-temperature protection circuits; The isolation design needs to ensure that sufficient current and voltage can be provided to quickly switch the SiC device, and use optocouplers or digital isolators for signal isolation; In summary, the SiC MOSFET is C3M0065100K, with a withstand voltage of 1200V, an on-resistance of 65mΩ, and a TO-247 package; the isolation driver chip is ACPL-344JT, the isolated DC-DC converter is B0505S-1W; and the optocoupler is 6N137.

2. The design of an isolated silicon carbide H-bridge circuit according to claim 1, characterized in that: The following formula is required in the process of selecting SIC power devices: Switching losses: Among them, v ds is the drain-source voltage, I ds Drain-source current, t r and t f are the rise and fall times, f sw is the switching frequency; Conduction loss: Among them, I rms is the rms current, R ds(on) is the on-resistance.

3. The design of an isolated silicon carbide H-bridge circuit according to claim 1, characterized in that: The drive circuit design requires circuit protection design, and the following formula is required: Overvoltage protection threshold: V trip =V max ×1.1 (usually set to 110% of the maximum voltage; Overcurrent protection threshold: I trip =I max ×1.2 (usually set to 120% of the maximum current.

4. The design of an isolated silicon carbide H-bridge circuit according to claim 1, characterized in that: The H-bridge topology design requires the calculation of the trace width, using the following formula: Trace width: Where I is the current, ΔT is the temperature rise, and k and b are constants that depend on the material and thickness.

5. The isolated silicon carbide H-bridge circuit according to claim 1, characterized in that: The system includes four power switches Q1 , Q2 , Q3 and Q4 , four diodes D1 , D2 , D3 and D4 , the capacitor and the DC motor M.

6. The design of an isolated silicon carbide H-bridge circuit according to claim 1, characterized in that: The four power switches adopt bipolar power diodes.

7. The design of an isolated silicon carbide H-bridge circuit according to claim 1, characterized in that: The four diodes are Schottky diodes.

Images