Power circuit based on SiC MOSFET

Abstract

The invention relates to a power circuit based on a SiC MOSFET, and belongs to the field of high-voltage direct-current intelligent power distribution. Comprising a power supply unit, a first energy storage unit, a second energy storage unit, a first SiC MOSFET circuit and a second SiC MOSFET circuit. The first energy storage unit is connected between the positive electrode of the power supply unit and the positive ends of the first SiC MOSFET circuit and the second SiC MOSFET circuit; the negative end of the first SiC MOSFET circuit is connected with the negative output end of the double-switch Boost circuit, and the negative end of the second SiC MOSFET circuit is connected with the positive output end of the double-switch Boost circuit; the second energy storage unit is connected between the positive output end and the negative output end of the double-switch Boost circuit; and under the action of a control signal, the second SiC MOSFET circuit is independently conducted or is alternately conducted with the first SiC MOSFET circuit. The power circuit with high power distribution efficiency and high adaptability is realized.

Description

Technical Field

[0001] This invention relates to the field of high voltage DC intelligent power distribution technology, and in particular to a power circuit based on SiC MOSFET. Background Technology

[0002] With the rapid development of power supply and distribution systems for my country's aerospace equipment towards higher efficiency, higher voltage, and higher power density, power circuits in these systems must also develop towards higher efficiency, higher voltage, and higher power density.

[0003] As the on-resistance of silicon-based power devices increases with their voltage rating, IGBTs have become the mainstream choice for high-voltage applications. However, IGBTs generate tail current during turn-off, resulting in significant switching losses. Furthermore, in existing aerospace equipment, the output voltage of power batteries decreases as battery energy is depleted, leading to reduced equipment efficiency.

[0004] Therefore, there is an urgent need for a power circuit with high power distribution efficiency and boost function in the field of power supply and distribution for aerospace equipment. Summary of the Invention

[0005] Based on the above analysis, the present invention aims to provide a power circuit based on SiC MOSFET to solve the problem that the switching on-resistance of the power circuit is large and the output voltage of the power circuit will decrease as the battery energy is consumed during the power supply and distribution process of existing aerospace equipment.

[0006] This invention provides a power circuit based on SiC MOSFETs, comprising a dual-switch Boost circuit. The dual-switch Boost circuit includes a power supply unit, first and second energy storage units, a first SiC MOSFET circuit, and a second SiC MOSFET circuit. One end of the first energy storage unit is connected to the positive terminal of the power supply unit, and the other end is connected to the positive terminals of both the first and second SiC MOSFET circuits. The negative terminal of the first SiC MOSFET circuit is connected to the negative output terminal of the dual-switch Boost circuit, and the negative terminal of the second SiC MOSFET circuit is connected to the positive output terminal of the dual-switch Boost circuit. The second energy storage unit is connected between the positive and negative output terminals of the dual-switch Boost circuit.

[0007] Under the control signal, the second SiC MOSFET circuit is turned on individually or alternately with the first SiC MOSFET circuit to supply power to the load connected between the positive and negative output terminals of the dual-switch Boost circuit.

[0008] Furthermore, the control signal includes a first control signal and a second control signal;

[0009] The first control signal is connected to the control terminal of the first SiC MOSFET circuit, and the second control signal is connected to the control terminal of the second SiC MOSFET circuit.

[0010] The first control signal and the second control signal are used to control the second SiC MOSFET circuit to be turned on independently when the power supply unit voltage is normal; and to control the second SiC MOSFET circuit and the first SiC MOSFET circuit to be turned on alternately when the power supply unit voltage drops below a set threshold.

[0011] Furthermore, the first SiC MOSFET circuit includes a first SiC MOSFET branch, a second SiC MOSFET branch, and a first resistor; the first SiC MOSFET branch includes a first SiC MOSFET and a third resistor; the second SiC MOSFET branch includes a second SiC MOSFET and a second resistor; the source of the first SiC MOSFET is connected to the source of the second SiC MOSFET as the negative terminal of the first SiC MOSFET circuit; the drain of the first SiC MOSFET is connected to the drain of the second SiC MOSFET as the positive terminal of the first SiC MOSFET circuit; the gate of the first SiC MOSFET is connected to one end of the third resistor, the gate of the second SiC MOSFET is connected to one end of the second resistor, the other ends of the third resistor and the second resistor are connected together and then connected to one end of the first resistor, and the other end of the first resistor is the control terminal.

[0012] Furthermore, the second SiC MOSFET circuit includes a third to a sixth SiC MOSFET and a fifth to an eighth resistor; the sources of the third and fifth SiC MOSFETs are connected; the sources of the fourth and sixth SiC MOSFETs are connected; the drains of the third and fourth SiC MOSFETs are connected as the positive terminal of the second SiC MOSFET circuit; the drains of the fifth and sixth SiC MOSFETs are connected as the negative terminal of the second SiC MOSFET circuit; one end of the fifth resistor is connected to the gate of the fourth SiC MOSFET, one end of the sixth resistor is connected to the gate of the third SiC MOSFET, one end of the seventh resistor is connected to the gate of the sixth SiC MOSFET, one end of the eighth resistor is connected to the gate of the fifth SiC MOSFET, and the other ends of the fifth to eighth resistors are connected to the control terminal.

[0013] Furthermore, the second SiC MOSFET circuit also includes a fourth resistor; the other end of the fifth to eighth resistors is connected to the control terminal through the fourth resistor.

[0014] Furthermore, the power circuit also includes a pre-charging circuit; the control signal also includes a third control signal;

[0015] The pre-charge circuit is connected in parallel between the positive terminal of the power supply unit and the positive output terminal in the dual-switch Boost circuit; the pre-charge circuit is used to supply power to the load based on the third control signal when the power circuit is started.

[0016] Furthermore, the pre-charge circuit includes a seventh SiC MOSFET and ninth to eleventh resistors;

[0017] The gate of the seventh SiC MOSFET is connected to the control terminal of the pre-charge circuit through the ninth resistor. The control terminal is used to receive the third control signal. The drain of the seventh SiC MOSFET is connected to the positive terminal of the power supply unit. The source of the seventh SiC MOSFET is connected to the positive output terminal of the dual-switch Boost circuit through the tenth resistor and the eleventh resistor in sequence.

[0018] Furthermore, the first energy storage unit is an energy storage inductor; the second energy storage unit is an energy storage capacitor.

[0019] Furthermore, the dual-switch Boost circuit also includes a SiC Schottky diode; the negative terminal of the SiC Schottky diode is connected to the positive output terminal of the dual-switch Boost circuit, and the positive terminal is connected to the negative terminal of the power supply unit.

[0020] Furthermore, the dual-switch Boost circuit also includes a filter capacitor, one end of which is connected to the positive terminal of the power supply unit, and the other end of which is connected to the negative terminal of the power supply unit.

[0021] Compared with the prior art, the present invention can achieve at least one of the following beneficial effects:

[0022] 1. The power circuit of this invention uses SiC MOSFETs, enabling it to operate in high-voltage, high-frequency, and high-temperature environments. Compared to Si-based power devices currently used in aerospace equipment, this significantly reduces the size and weight of the power circuit and allows for stable operation with lower on-resistance and higher switching frequency. It also offers higher power distribution efficiency, greater environmental adaptability, and higher reliability.

[0023] 2. This invention innovatively proposes a dual-switch Boost circuit design. This circuit can efficiently distribute power to downstream devices when the battery voltage is normal, and simultaneously boost the input voltage to power downstream devices when the battery voltage is low, ensuring the continuous and efficient operation of downstream devices. It ensures that the output voltage does not decrease with the decrease in the power supply battery voltage, guaranteeing the efficient operation of downstream devices. Compared to current power circuits that only handle power distribution without dynamically adjusting the distribution voltage, this invention ensures that the output voltage is continuously maintained within a certain range, guaranteeing the continuous and efficient operation of downstream devices.

[0024] 3. Both the first and second SiC MOSFET circuits of this invention include two identical parallel branches to share the current required by the subsequent load of aerospace equipment. Furthermore, the power circuit of this invention is adapted to high supply voltages of thousands of volts. Each branch of the second SiC MOSFET circuit includes two SiC MOSFETs connected in series, with the sources of the third and fifth SiC MOSFETs connected; the sources of the fourth and sixth SiC MOSFETs are also connected, preventing the output voltage from flowing back from the negative terminal to the positive terminal of the second SiC MOSFET circuit when the first SiC MOSFET circuit is turned on.

[0025] 4. This invention designs a pre-charge circuit with two resistors at the source of the pre-charge circuit. This avoids the situation where the servo system, which is the load part, suddenly increases the current due to no-load at the moment of startup, and the surge current of large energy passes through at the moment of conduction, which may cause damage or even burnout of the seventh SiC MOSFET, thereby improving the reliability of the pre-charge circuit.

[0026] 5. The present invention adopts a scheme of multiple pre-charging resistors connected in series in the pre-charging circuit, which reduces the probability of the power circuit burning out due to short circuit of the pre-charging resistor, thus improving the reliability of the circuit.

[0027] In this invention, the above-described technical solutions can be combined with each other to achieve more preferred combinations. Other features and advantages of this invention will be set forth in the following description, and some advantages may become apparent from the description or be learned by practicing the invention. The objects and other advantages of this invention can be realized and obtained from what is particularly pointed out in the description and drawings. Attached Figure Description

[0028] The accompanying drawings are for illustrative purposes only and are not intended to limit the invention. Throughout the drawings, the same reference numerals denote the same parts.

[0029] Figure 1 This is a schematic diagram of a power circuit based on SiC MOSFET according to an embodiment of the present invention;

[0030] Figure 2 This is a schematic diagram of a power circuit based on SiC MOSFET according to another embodiment of the present invention. Detailed Implementation

[0031] Preferred embodiments of the present invention will now be described in detail with reference to the accompanying drawings, which form part of this application and are used together with the embodiments of the present invention to illustrate the principles of the present invention, but are not intended to limit the scope of the present invention.

[0032] One specific embodiment of the present invention discloses a power circuit based on SiC MOSFET, such as... Figure 1 As shown. The power circuit includes a dual-switch Boost circuit U3; the dual-switch Boost circuit U3 includes a power supply unit, first and second energy storage units (L1, C2), a first SiC MOSFET circuit, and a second SiC MOSFET circuit; one end of the first energy storage unit L1 is connected to the positive terminal of the power supply unit, and the other end is connected to the positive terminals of the first SiC MOSFET circuit and the second SiC MOSFET circuit respectively; the negative terminal of the first SiC MOSFET circuit is connected to the negative output terminal of the dual-switch Boost circuit U3, and the negative terminal of the second SiC MOSFET circuit is connected to the positive output terminal of the dual-switch Boost circuit U3; the second energy storage unit C2 is connected between the positive and negative output terminals of the dual-switch Boost circuit U3;

[0033] Under the control signal, the second SiC MOSFET circuit is turned on individually or alternately with the first SiC MOSFET circuit to supply power to the load connected between the positive and negative output terminals of the dual-switch Boost circuit U3.

[0034] The second SiC MOSFET circuit alternately conducts with the first SiC MOSFET circuit to provide a boost continuous conduction mode when the voltage of the power supply unit (battery UDC) decreases.

[0035] Specifically, such as Figure 1 As shown, the power circuit performs power distribution actions according to the first to third control signals (Vg1-Vg3); when the power circuit is distributing power, the power circuit outputs the power distribution output voltage VOUT to the external load.

[0036] The control signals can be output by an external control circuit, including a first control signal Vg1 and a second control signal Vg2;

[0037] The first control signal Vg1 is connected to the control terminal of the first SiC MOSFET circuit, and the second control signal Vg2 is connected to the control terminal of the second SiC MOSFET circuit.

[0038] The first control signal Vg1 and the second control signal Vg2 are used to control the second SiC MOSFET circuit to be turned on independently when the voltage of the power supply unit is normal; and to control the second SiC MOSFET circuit and the first SiC MOSFET circuit to be turned on alternately when the voltage value of the power supply unit (battery UDC) drops below a set threshold and the duration is greater than the undervoltage protection preset time threshold.

[0039] Specifically, when the power supply unit voltage is normal, controlling the second SiC MOSFET circuit to conduct independently allows the power supply unit (battery UDC) to directly supply power to the load through the first energy storage unit and the second SiC MOSFET circuit. When the voltage of the power supply unit (battery UDC) drops below a set threshold, controlling the second SiC MOSFET circuit and the first SiC MOSFET circuit to conduct alternately allows energy to be stored first through the first energy storage unit L1 (while the first SiC MOSFET circuit is conducting) in each cycle (the cycle of the PWM waveform) when the voltage of the power supply unit (battery UDC) decreases. Then, the first energy storage unit L1 and the power supply unit (battery UDC) release energy, supplying power to the load through the second SiC MOSFET circuit (while the first SiC MOSFET circuit is turned off). This ensures that the power distribution to the downstream load is not affected when the power supply unit (battery UDC) voltage is insufficient.

[0040] Specifically, the first SiC MOSFET circuit includes a first SiC MOSFET branch, a second SiC MOSFET branch, and a first resistor R1; the first SiC MOSFET branch includes a first SiC MOSFET (M1) and a third resistor R3; the second SiC MOSFET branch includes a second SiC MOSFET (M2) and a second resistor R2; the source of the first SiC MOSFET is connected to the source of the second SiC MOSFET as the negative terminal of the first SiC MOSFET circuit; the drain of the first SiC MOSFET is connected to the drain of the second SiC MOSFET as the positive terminal of the first SiC MOSFET circuit; the gate of the first SiC MOSFET (M1) is connected to one end of the third resistor R3, the gate of the second SiC MOSFET (M2) is connected to one end of the second resistor R2, the other ends of the third resistor R3 and the second resistor R2 are connected together and then connected to one end of the first resistor R1, and the other end of the first resistor R1 is the control terminal.

[0041] Specifically, the second resistor R2 and the third resistor R3 are usually chosen to have the same resistance value. The first resistor R1 to the third resistor R3 are set to suppress the oscillations in the gate drive circuit caused by parasitic inductance and capacitance on the printed circuit board. Simultaneous switching of the first and second SiC MOSFETs (M1, M2) ensures the stability of the power circuit operation and the consistency of the actions of each parallel switch. In a specific embodiment of the present invention, when the power circuit conduction time is 500ms, the sum of the resistance values ​​of R1 and R2, and the sum of the resistance values ​​of R1 and R3, is 20-30kΩ.

[0042] The second SiC MOSFET circuit includes the third to sixth SiC MOSFETs (M3-M6) and the fifth to eighth resistors (R5-R8); the sources of the third and fifth SiC MOSFETs (M3 and M5) are connected; the sources of the fourth and sixth SiC MOSFETs (M4 and M6) are connected; the drains of the third and fourth SiC MOSFETs (M3 and M4) are connected as the positive terminal of the second SiC MOSFET circuit; the drains of the fifth and sixth SiC MOSFETs (M5 and M6) are connected as the negative terminal of the second SiC MOSFET circuit; one end of the fifth resistor R5 is connected to the gate of the fourth SiC MOSFET (M4), one end of the sixth resistor R6 is connected to the gate of the third SiC MOSFET (M3), one end of the seventh resistor R7 is connected to the gate of the sixth SiC MOSFET (M6), one end of the eighth resistor R8 is connected to the gate of the fifth SiC MOSFET (M5), and the other ends of the fifth to eighth resistors (R5-R8) are connected to the control terminal.

[0043] The second SiC MOSFET circuit also includes a fourth resistor R4; the other end of the fifth to eighth resistors (R5-R8) is connected to the control terminal through the fourth resistor R4.

[0044] Specifically, the gates of the third to sixth SiC MOSFETs (M3 to M6) are all connected to the same resistor, and then a fourth resistor R4 is connected in the main circuit. The purpose is to ensure that the gate control terminals of the third to sixth SiC MOSFETs have current sharing characteristics, so as to ensure that the third to sixth SiC MOSFETs operate in a consistent manner, and also to give them good resistance to gate voltage oscillation.

[0045] The second control signal Vg2 provides a high-level signal to power the load when the power supply unit is supplying power normally, and provides a PWM waveform when the power supply unit's voltage is insufficient, causing the second SiC MOSFET circuit to conduct intermittently. Specifically, when not conducting, Vg2 is low and the first energy storage unit is charging, at which point the second energy storage unit can power the load. When conducting, Vg2 is high, and the first energy storage unit L1, after charging, releases its energy and, together with the power supply unit, powers the load and charges the second energy storage unit C2 when the second SiC MOSFET circuit is conducting.

[0046] To improve load capacity and operating margin, both the first SiC MOSFET circuit and the second SiC MOSFET circuit adopt a dual-branch parallel connection.

[0047] The control logic of the power circuit is as follows: When the battery voltage is normal, the first control signal controls M1 and M2 to turn off, and the second control signal controls M3 to M6 to turn on. During this stage, voltage and current information are collected in real time. If a short circuit is detected, the controlled SiC MOSFET is immediately turned off through the second control signal. If the battery voltage VIN is found to be lower than the set threshold voltage and the duration is greater than the undervoltage protection preset time threshold, the first and second control signals (Vg1, Vg2) send alternating PWM control signals to the first and second SiC MOSFET circuits in the dual-switch Boost circuit U3 in the power circuit, respectively, to keep the dual-switch Boost circuit U3 in a boost continuous conduction state, ensuring that the output voltage VOUT does not decrease as the battery voltage VIN decreases, thereby ensuring that the downstream equipment can work efficiently. During this stage, voltage and current information are collected in real time. If a short circuit is detected, the controlled SiC MOSFET is immediately turned off through the first and second control signals (Vg1, Vg2).

[0048] In one specific embodiment of the present invention, the fifth to eighth resistors (R5 to R8) are all identical, and the third to sixth SiC MOSFETs (M3 to M6) are all identical. The design of completely symmetrical branches ensures that the conduction times of the two branches are synchronized, avoiding safety hazards caused by excessive current in one branch.

[0049] Another embodiment of the present invention, such as Figure 2 Specifically, the SiC MOSFET-based power circuit includes the dual-switch Boost circuit U3 of the above embodiment, and also includes a pre-charge circuit U4; the power circuit also includes the pre-charge circuit U4; the control signal also includes a third control signal Vg3;

[0050] The pre-charge circuit U4 is connected in parallel between the positive terminal of the power supply unit and the positive output terminal in the dual-switch Boost circuit U3; the pre-charge circuit U4 is used to supply power to the load based on the third control signal Vg3 when the power circuit is started.

[0051] The pre-charge circuit U4 includes a seventh SiC MOSFET (M7) and ninth to eleventh resistors (R9 to R11);

[0052] The gate of the seventh SiC MOSFET (M7) is connected to the control terminal of the pre-charge circuit U4 through the ninth resistor R9. The control terminal is used to receive the third control signal Vg3. The drain of the seventh SiC MOSFET (M7) is connected to the positive terminal of the power supply unit. The source of the seventh SiC MOSFET (M7) is connected to the positive output terminal of the dual-switch Boost circuit U3 through the tenth resistor R10 and the eleventh resistor R11 in sequence.

[0053] Specifically, when the power circuit starts up, the pre-charge circuit U4 pre-charges the capacitive load in the load with a small current. This prevents damage to the SiC MOSFET due to excessive surge current.

[0054] Preferably, the pre-charge circuit U4 receives the third control signal Vg3 to control the switching state of the seventh SiC MOSFET (M7); the other end of R10 is connected to a pre-charge resistor R11 of the same specification as R10. Using two pre-charge resistors can effectively avoid the situation where a single pre-charge resistor is short-circuited, causing damage or even burnout to M7 due to the surge current passing through M7 at the moment of conduction, thereby improving the reliability of the pre-charge circuit U4.

[0055] In this embodiment, the first to seventh SiC MOSFETs (M1 to M7) used in the power circuit have on-resistance values ​​in the milliohm range, ensuring high operating efficiency and significantly reducing power loss. The second SiC MOSFET circuit has two source-interconnected SiC MOSFETs in each branch, providing short-circuit protection. The pre-charge circuit U4 has surge suppression, and the dual-switch Boost circuit U3 has a boost function, efficiently meeting the power distribution needs of both conventional loads and loads with servo characteristics. If the output voltage falls below the set threshold, the level control commands Vg1 and Vgi2 are output as PWM waveforms, thereby controlling the dual-switch Boost circuit U3 in the power circuit to enter a continuous boost conduction mode, maintaining the output voltage from decreasing as the battery voltage drops.

[0056] The first energy storage unit is an energy storage inductor; the second energy storage unit is an energy storage capacitor.

[0057] The dual-switch Boost circuit U3 also includes a SiC Schottky diode; the negative terminal of the SiC Schottky diode is connected to the positive output terminal of the dual-switch Boost circuit U3, and the positive terminal is connected to the negative terminal of the power supply unit.

[0058] The dual-switch Boost circuit U3 also includes a filter capacitor C1, one end of which is connected to the positive terminal of the power supply unit and the other end is connected to the negative terminal of the power supply unit.

[0059] Specifically, such as Figure 2 As shown, the dual-switch Boost circuit U3 receives the first control signal Vg1 output from the SiC MOSFET isolation drive module to control the switching states of the first SiC MOSFET (M1) and the second SiC MOSFET (M2), and receives the second control signal Vg2 to control the states of the third to sixth SiC MOSFETs (M3 to M6). Before the supply voltage VIN enters the first and second SiC MOSFET circuits, it first passes through the high-frequency filter capacitor C1. After filtering, it passes through the energy storage inductor L1, and then splits into two paths. One path connects to the drains of M1 and M2, and the sources of M1 and M2 are connected to the negative terminal of the battery UDC. The gate of M1 is connected to the gate resistor R3 (the third resistor), and the gate of M2 is connected to the gate resistor R2 (the second resistor). The other ends of R2 and R3 are connected to one end of the gate resistor R1 (the first resistor), and the other end of R1 is connected to the SiC MOSFET. The output terminal of the corresponding drive circuit in the MOSFET isolation drive module U2; the other end of the energy storage inductor L1 is connected to the common drain of M3 and M4, M3 and M5 are connected in series, M4 and M6 are connected in series, and the two series branches are connected in parallel. The common drain of M5 and M6 is connected to the output capacitor C2, the negative terminal of the SiC Schottky diode D1 for freewheeling, and the positive terminal of the load. The filter capacitor C1, the output capacitor C2, the SiC Schottky diode D1, and the negative terminal of the load are all connected to the negative terminal of the power supply battery UDC.

[0060] Preferably, the control logic of the power circuit is as follows: When the power circuit starts, the third control signal (Vg3) first drives the pre-charge circuit U4 to conduct, pre-charging the capacitive load in the load. After a period of time, the second control signal (Vg2) controls M3 to M6 in the dual-switch Boost circuit U3 to conduct while the pre-charge circuit U4 is conducting. After maintaining this state for a period of time, the pre-charge circuit U4 is turned off, leaving only M3 to M6 of the dual-switch Boost circuit U3 conducting to supply power to the load. During this stage, the control circuit collects voltage and current information in real time. If a short circuit is detected, all SiC MOSFETs are immediately turned off. If the battery voltage VIN is found to be lower than the set threshold voltage, the first and second control signals will send PWM control signals to the dual-switch Boost circuit U3 in the power circuit to keep the dual-switch Boost circuit U3 in a boost continuous conduction state, ensuring that the output voltage VOUT does not decrease as the battery voltage VIN decreases, thereby ensuring that the downstream equipment can work efficiently.

[0061] Preferably, the operation of the SiC MOSFET-based power circuit is as follows:

[0062] Phase 1: Start-up phase. The third control signal first drives M7 in the pre-charge circuit U4 to conduct. Because there are resistors R10 and R11 in this circuit, the capacitive load in the load will be pre-charged with a small current at this time, so as to prevent damage to the SiC MOSFET due to excessive surge current.

[0063] Phase Two: After a period of pre-charging, the second control signal controls M3 to M6 in the dual-switch Boost circuit U3 to conduct while the pre-charging circuit U4 is on. After maintaining this state for a period of time (several hundred milliseconds), the pre-charging circuit U4 is turned off, leaving only M3 to M6 in the dual-switch Boost circuit U3 conducting to supply power to the load. The reason for using M3 to M6, i.e., two sets of parallel transistors, is that when the dual-switch Boost circuit U3 is not operating in the boost continuous conduction mode, it ensures power supply to the main power distribution circuit (…). The on / off control of the dual-switch Boost circuit U3 requires the drains of M3 and M4 to be connected to the energy storage inductor L1. When entering the boost continuous conduction mode, when M1 and M2 are turned on, the voltage at the common drain of M3 and M4 is significantly lower than the voltage across the output capacitor C2. This voltage difference causes the parasitic diodes in M3 and M4 to conduct, thus preventing them from functioning as diode cut-off devices. Therefore, M5 and M6 need to be connected in series after M3 and M4, and the sources of M3 and M4 are connected to the sources of M5 and M6 respectively, so that the second SiC MOSFET circuit has the function of diode cut-off.

[0064] Phase 3: In this phase, voltage and current information need to be collected in real time. If a short circuit is detected, all SiC MOSFETs will be turned off immediately. If the battery voltage VIN is found to be lower than the set threshold voltage, the first and second control signals will send PWM control signals to the dual-switch Boost circuit U3 in the power circuit, so that the dual-switch Boost circuit U3 is in the boost continuous conduction state, ensuring that the output voltage VOUT will not decrease as the battery voltage VIN decreases, thereby ensuring that the downstream equipment can work efficiently.

[0065] The working principle of the dual-switch Boost circuit U3 is as follows: When M1 and M2 are turned on and M3 to M6 are turned off, the current I output by the battery UDC charges the energy storage inductor L1, and the energy obtained in the inductor at this time is E1 = VIN * I * t. on , where t on During the on-time of M1 and M2, the voltage across the output capacitor C2 supplies power to the load. When M1 and M2 are off, and M3 to M6 are on simultaneously, the energy storage inductor L1 and the battery UDC together charge the output capacitor C2 and supply power to the load. The energy released in the energy storage inductor during this stage is E2 = (VOUT - VIN) * I * t. off , where t off Let M1 and M2 be the turn-off times. Based on the principle that the energy stored and released by the inductor are consistent, we can obtain E1 = E2, i.e., VIN * I * t. on = (VOUT - VIN) * I * t off Simplifying, we get By adjusting the duty cycle of the control signals Vg1 and Vg2 in the dual-switch Boost circuit U3, the battery voltage VIN can be boosted to the required voltage VOUT, thereby ensuring the continuous and efficient operation of downstream equipment.

[0066] Phase 4: When power supply to the load is stopped, the first to third control signals will transfer negative voltages to the gates of all SiC MOSFETs to turn them off. Due to the inherent inductance of the load itself and the parasitic inductance of the power circuit, after the power is turned off, the relevant inductors will generate a large reverse electromotive force, which will cause the voltage across the drain and source of the SiC MOSFET to increase sharply and instantaneously, which may cause it to break down. In this solution, a SiC Schottky diode is connected in parallel at the output to provide a freewheeling effect for the energy in the aforementioned inductor, thereby maintaining the voltage across the drain and source of the SiC MOSFET at a voltage level that is almost consistent with VIN.

[0067] Compared to existing technologies, the power circuit provided in this embodiment uses SiC MOSFETs, enabling it to operate in high-voltage, high-frequency, and high-temperature environments with low on-resistance. Compared to solid-state power controllers based on Si-based power devices currently used in aerospace equipment, it offers higher power distribution efficiency, greater environmental adaptability, and higher reliability. This embodiment innovatively proposes a dual-switch Boost circuit U3 design. This circuit can efficiently distribute power to downstream devices when the battery voltage is normal, and simultaneously boost the input voltage to power downstream devices when the battery voltage is low, ensuring the continuous and efficient operation of downstream devices. It ensures that the output voltage does not decrease with the decrease in the battery voltage, guaranteeing the efficient operation of downstream devices. Compared to current power circuits that only distribute power without dynamically adjusting the distribution voltage, this invention ensures that the output voltage remains within a certain range, guaranteeing the continuous and efficient operation of downstream devices. Both the first and second SiC MOSFET circuits in this embodiment include two identical parallel branches to share the current required by the subsequent loads of aerospace equipment. Furthermore, the power circuit of this invention is adaptable to high supply voltages of thousands of volts. Each branch of the second SiC MOSFET circuit includes two SiC MOSFETs connected in series, with the sources of the third and fifth SiC MOSFETs (M3 and M5) connected; the sources of the fourth and sixth SiC MOSFETs (M4 and M6) are also connected, preventing the output voltage from flowing back from the negative terminal to the positive terminal of the second SiC MOSFET circuit when the first SiC MOSFET circuit is turned on. This embodiment incorporates a pre-charge circuit U4, whose source has two resistors. This prevents a sudden increase in current due to no-load conditions during startup of the servo system, thus avoiding a surge current that could damage or even burn out the seventh SiC MOSFET (M7) during turn-on, thereby improving the reliability of the pre-charge circuit U4. The pre-charge circuit U4 in this embodiment uses a multi-pre-charge resistor series configuration, reducing the probability of power circuit burnout due to short circuits in the pre-charge resistors, thus improving the circuit's reliability.

[0068] Those skilled in the art will understand that all or part of the processes of the methods described in the above embodiments can be implemented by a computer program instructing related hardware, and the program can be stored in a computer-readable storage medium. The computer-readable storage medium may be a disk, optical disk, read-only memory, or random access memory, etc.

[0069] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the scope of protection of the present invention.

Claims

1. A power circuit based on SiC MOSFET, characterized in that, the power circuit comprises a double-switch Boost circuit; the double-switch Boost circuit comprises a power supply unit, a first energy storage unit, a second energy storage unit, a first SiC MOSFET circuit and a second SiC MOSFET circuit; one end of the first energy storage unit is connected to the positive electrode of the power supply unit, and the other end is connected to the positive terminal of the first SiC MOSFET circuit and the second SiC MOSFET circuit respectively; the negative terminal of the first SiC MOSFET circuit is connected to the negative output terminal of the double-switch Boost circuit, and the negative terminal of the second SiC MOSFET circuit is connected to the positive output terminal of the double-switch Boost circuit; the second energy storage unit is connected between the positive and negative output terminals of the double-switch Boost circuit; under the action of a control signal, the second SiC MOSFET circuit is turned on alone or alternately with the first SiC MOSFET circuit, for supplying power to a load connected between the positive and negative output terminals of the double-switch Boost circuit.

2. The power circuit of claim 1, wherein, the control signal comprises a first control signal and a second control signal; the first control signal is connected to the control terminal of the first SiC MOSFET circuit, and the second control signal is connected to the control terminal of the second SiC MOSFET circuit; the first control signal and the second control signal are used to control the second SiC MOSFET circuit to be turned on alone when the voltage of the power supply unit is normal, and are used to control the second SiC MOSFET circuit to be turned on alternately with the first SiC MOSFET circuit when the voltage of the power supply unit drops below a set threshold.

3. The power circuit of claim 2, characterized in that, the first SiC MOSFET circuit comprises a first SiC MOSFET branch, a second SiC MOSFET branch and a first resistor; the first SiC MOSFET branch comprises a first SiC MOSFET and a third resistor; the second SiC MOSFET branch comprises a second SiC MOSFET and a second resistor; the source of the first SiC MOSFET is connected to the source of the second SiC MOSFET as the negative terminal of the first SiC MOSFET circuit; the drain of the first SiC MOSFET is connected to the drain of the second SiC MOSFET as the positive terminal of the first SiC MOSFET circuit; the gate of the first SiC MOSFET is connected to one end of the third resistor, and the gate of the second SiC MOSFET is connected to one end of the second resistor; the other ends of the third resistor and the second resistor are connected to one end of the first resistor; the other end of the first resistor is the control terminal.

4. The power circuit of claim 2, characterized in that, The second SiC MOSFET circuit comprises third to sixth SiC MOSFETs and fifth to eighth resistors; the sources of the third and fifth SiC MOSFETs are connected; the sources of the fourth and sixth SiC MOSFETs are connected; the drains of the third and fourth SiC MOSFETs are connected as the positive terminal of the second SiC MOSFET circuit; the drains of the fifth and sixth SiC MOSFETs are connected as the negative terminal of the second SiC MOSFET circuit; one end of the fifth resistor is connected to the gate of the fourth SiC MOSFET, one end of the sixth resistor is connected to the gate of the third SiC MOSFET, one end of the seventh resistor is connected to the gate of the sixth SiC MOSFET, one end of the eighth resistor is connected to the gate of the fifth SiC MOSFET, and the other ends of the fifth to eighth resistors are connected to the control terminal.

5. The power circuit of claim 4, wherein, The second SiC MOSFET circuit further comprises a fourth resistor; the other ends of the fifth to eighth resistors are connected to the control terminal through the fourth resistor.

6. A power circuit according to any one of claims 2-5, characterized in that, The power circuit further comprises a pre-charge circuit; the control signal further comprises a third control signal; The pre-charge circuit is connected in parallel between the positive pole of the power supply unit and the positive output terminal of the double-switch Boost circuit; the pre-charge circuit is used to supply power to the load when the power circuit is started based on the third control signal.

7. The power circuit of claim 6, wherein, The pre-charge circuit comprises a seventh SiC MOSFET and ninth to eleventh resistors. The gate of the seventh SiC MOSFET is connected to the control terminal of the pre-charge circuit through the ninth resistor, the control terminal is used to receive the third control signal, and the drain of the seventh SiC MOSFET is connected to the positive pole of the power supply unit; the source of the seventh SiC MOSFET is connected to the positive output terminal of the double-switch Boost circuit in sequence through the tenth resistor and the eleventh resistor.

8. The power circuit of claim 1, wherein, The first energy storage unit is an energy storage inductor; and the second energy storage unit is an energy storage capacitor.

9. The power circuit of claim 1, wherein, The double-switch Boost circuit further comprises a SiC Schottky diode; the negative pole of the SiC Schottky diode is connected to the positive output terminal of the double-switch Boost circuit, and the positive pole is connected to the negative pole of the power supply unit.

10. The power circuit of claim 1, wherein, The double-switch Boost circuit further comprises a filter capacitor; one end of the filter capacitor is connected to the positive pole of the power supply unit, and the other end is connected to the negative pole of the power supply unit.

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