A direct current SSPC low latency RC driving circuit and a direct current SSPC

Abstract

The application relates to the technical field of solid-state power controllers, and particularly discloses a low-delay RC driving circuit of a direct-current SSPC and the direct-current SSPC. The low-delay RC driving circuit of the direct-current SSPC comprises a triode level conversion circuit, a resistance-capacitance network circuit and a totem pole push-pull circuit. The triode level conversion circuit receives a control instruction, generates a driving control voltage through the resistance-capacitance network circuit, and drives the main power tube of the direct-current SSPC to be turned on or turned off through the totem pole push-pull circuit. The resistance-capacitance network circuit comprises a turn-on unit, a turn-off unit and a capacitor, and the turn-on unit and the turn-off unit are connected in parallel and then connected in series with the capacitor. The application can regulate the driving voltage change rate in stages, takes into account the turn-on safety and the dynamic response speed, has the characteristics of simple control and high reliability, and effectively improves the anti-impact capability and switching performance of the SSPC.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of solid-state power controller, and particularly relates to a low-delay RC drive circuit of a direct-current solid-state power controller and the direct-current SSPC. BACKGROUND

[0002] A solid-state power controller (SSPC) is an intelligent power distribution device with a power semiconductor as a core and integrating switching control of a relay and fault protection function of a circuit breaker. As a core component of a solid-state power distribution system of an airplane, the SSPC has advantages of no contact, no arc, no noise, small electromagnetic interference, long service life, high reliability, and convenience for remote control by a computer.

[0003] With development of a high-voltage direct-current power supply system of a more-electric / all-electric airplane, impact loads in a power distribution system are increasing, which puts forward new requirements for the direct-current SSPC for fast and reliable switching of the impact loads. However, due to physical characteristics of the impact loads, high-amplitude impact current is generated at start-up, which causes instantaneous thermal stress accumulation of a power tube and leads to thermal failure and even system burning accident. And with increase of voltage grade of the power supply system of the airplane, the above problems will be further aggravated. In order to ensure safe and reliable operation of the more-electric / all-electric airplane, it is urgent to carry out in-depth research on a drive control circuit of the direct-current SSPC.

[0004] At present, in order to suppress the impact current, the existing technology sets an RC resistance-capacitance network with fixed parameters in a drive part to limit the rising rate of a drive voltage, but the technology eventually leads to slow rising of the drive voltage, and the load current establishment time is prolonged to the millisecond level, which delays establishment and exit of the load current, and further leads to slow response of the direct-current SSPC. When a load overcurrent or short-circuit fault occurs, the delayed response of the protection mechanism will increase the risk of fault diffusion. If the RC time constant is reduced to accelerate the response, the suppression effect on the impact current is weakened, and the risk of sudden temperature rise of the power tube is increased.

[0005] Therefore, a drive circuit design is urgently needed to suppress the impact current effectively while shortening the dynamic response time of the direct-current SSPC to the microsecond level to meet the requirements of high safety and rapidity of the aviation power distribution system. SUMMARY

[0006] In view of the deficiencies in the foregoing background art, the application first proposes a low-delay RC drive circuit of a direct-current SSPC to solve the problems of thermal failure risk caused by impact current when the direct-current SSPC switches on a load and slow switching dynamic response speed.

[0007] The technical scheme of the application is as follows:

[0008] The direct current SSPC low delay RC drive circuit is characterized in that it comprises a triode level conversion circuit, a resistance-capacitance network circuit and a totem pole push-pull circuit; the triode level conversion circuit receives a control instruction, generates a drive control voltage through the resistance-capacitance network circuit, and drives the main power tube of the direct current SSPC to turn on or turn off through the totem pole push-pull circuit.

[0009] The resistance-capacitance network circuit comprises a turn-on unit, a turn-off unit and a capacitor, and the turn-on unit and the turn-off unit are connected in parallel and then connected in series with the capacitor.

[0010] The turn-on unit comprises a turn-on diode D ON , a turn-on resistor R ON1 , a turn-on resistor R ON2 and a turn-on MOS tube Q ON ; the turn-on MOS tube Q ON is connected in series with the turn-on resistor R ON1 and then connected in parallel with the turn-on resistor R ON2 , one end of the parallel circuit is connected in series with the turn-on diode D ON , and the other end is connected in series with the capacitor; the anode of the turn-on diode D ON is connected to the output end of the triode level conversion circuit; the gate of the turn-on MOS tube Q ON is connected to a turn-on reference voltage V REF-ON .

[0011] The turn-off unit comprises a turn-off diode D OFF , a turn-off resistor R OFF1 , a turn-off resistor R OFF2 and a turn-off MOS tube Q OFF ; the turn-on diode D ON and the turn-off diode D OFF have equal conduction voltage drops; the turn-off MOS tube Q OFF is connected in series with the turn-off resistor R OFF2 and then connected in parallel with the turn-off resistor R OFF1 , one end of the parallel circuit is connected in series with the turn-off diode D OFF , and the other end is connected in series with the capacitor; the cathode of the turn-off diode D OFF is connected to the output end of the triode level conversion circuit; the gate of the turn-off MOS tube Q OFF is connected to a turn-off reference voltage V REF-OFF .

[0012] The direct current SSPC low delay RC drive circuit is characterized in that it comprises a triode level conversion circuit, a resistance-capacitance network circuit and a totem pole push-pull circuit; the triode level conversion circuit receives a control instruction, generates a drive control voltage through the resistance-capacitance network circuit, and drives the main power tube of the direct current SSPC to turn on or turn off through the totem pole push-pull circuit.

[0013] The beneficial effects brought by the technical scheme of the present application are as follows:

[0014] The application adjusts the traditional RC network circuit, and adds two MOS tubes to form a new RC network circuit with dynamically switchable time constant, which is combined with the Totem-pole circuit to form a DC SSPC low-delay RC drive circuit.

[0015] (1) The new RC network circuit adds a switching transient gate resistor of the main power tube, reduces the time interval from the issue of the control command to the actual start of the switching process to tens of microseconds, has a simple structure, and improves the response speed of the SSPC.

[0016] (2) The new RC network circuit can effectively limit the rising rate of the drive voltage and suppress the thermal shock of the impact current on the main power tube during the switching process.

[0017] (3) After the load current reaches stability, the MOS tube switches the switching state to change the time constant of the RC network, ensures that the drive voltage quickly reaches steady state after switching on, and eliminates the "tail phenomenon" existing in the traditional RC drive circuit.

[0018] (4) The switching state of the MOS tube can be automatically switched, and the timing of the MOS tube switching state can be automatically set according to different parameters of the main power tube, which has a wide range of applications.

[0019] (5) Under the action of the switching transient gate resistor, the protection time after a short-circuit fault can be reduced to microseconds, improving the reliability of the SSPC. BRIEF DESCRIPTION OF DRAWINGS

[0020] Figure 1 is a DC SSPC circuit diagram based on a low-delay RC drive circuit;

[0021] Figure 2 is a working mode diagram of the low-delay RC drive circuit;

[0022] Figure 3 is a working timing diagram of the low-delay RC drive circuit. DETAILED DESCRIPTION

[0023] The technical solutions of the application will be described in detail below with reference to the drawings and examples.

[0024] Example 1

[0025] This example provides a DC SSPC low-delay RC drive circuit. As shown in the figure, Figure 1 the drive circuit includes a triode level conversion circuit, an RC network circuit, and a Totem-pole circuit. The triode level conversion circuit is used to receive a control command CMD and generate a drive control voltage V gc through the RC network circuit, and the drive control voltage V gcThe main power tube Q of the direct current SSPC is driven to open or close by the Totem pole circuit.

[0026] The triode level conversion circuit of the embodiment comprises resistance R0, resistance R1, resistance R2, triode Q1 and triode Q2, wherein the triode Q1 is connected in series with the resistance R0, the triode Q2 is connected in series with the resistance R1, and the two series circuits are connected in parallel with each other and with the control voltage V CC The base of the triode Q2 is connected with the emitter of the triode Q1, the base of the triode Q1 is connected with the control command CMD, the emitter of the triode Q2 is connected with one end of the resistance R2, and the other end of the resistance R2 is connected as the output end of the triode level conversion circuit to the resistance-capacitance network circuit and the Totem pole circuit.

[0027] The resistance-capacitance network circuit of the embodiment adopts a new structure comprising an opening unit, a closing unit and a capacitor C, wherein the opening unit and the closing unit are connected in parallel and then connected in series with the capacitor C.

[0028] The opening unit comprises opening diode D ON , opening resistance R ON1 , opening resistance R ON2 and opening MOS tube Q ON , wherein the opening MOS tube Q ON is connected in series with the opening resistance R ON1 and then connected in parallel with the opening resistance R ON2 , one end of the parallel circuit is connected in series with the opening diode D ON , and the other end is connected in series with the capacitor C. The anode of the opening diode D ON is connected with the output end of the triode level conversion circuit. The gate of the opening MOS tube Q ON is connected with the opening reference voltage V REF-ON .

[0029] The closing unit comprises closing diode D OFF , closing resistance R OFF1 , closing resistance R OFF2 and closing MOS tube Q OFF . The conduction voltage drops of the opening diode D ON and the closing diode D OFF are both U D . The closing MOS tube Q OFF is connected in series with the closing resistance R OFF2 and then connected in parallel with the closing resistance R OFF1 , one end of the parallel circuit is connected in series with the closing diode D OFF , and the other end is connected in series with the capacitor C. The cathode of the closing diode D OFF is connected with the output end of the triode level conversion circuit, and the gate of the closing MOS tube Q OFF is connected with the closing reference voltage VREF-OFF .

[0030] wherein the turn-on reference voltage V REF-ON is divided by the turn-on reference voltage dividing resistor R div-ON1 and the turn-on reference voltage dividing resistor R div-ON2 to generate the control voltage V CC . REF-OFF is divided by the turn-off reference voltage dividing resistor R div-OFF1 and the turn-off reference voltage dividing resistor R div-OFF2 to generate the control voltage V CC .

[0031] (1)

[0032] (2)

[0033] wherein the turn-on MOS Q ON is an enhancement N-channel MOSFET, and the turn-on threshold voltage is V th-QON , which is driven by V REF-ON and U C . The turn-off MOS Q OFF is an enhancement P-channel MOSFET, and the turn-off threshold voltage is V th-QOFF , which is driven by V REF-OFF and U C . U C is the voltage across the capacitor C and the turn-on MOS Q ON . The turn-off MOS Q OFF is connected to the voltage across the capacitor C.

[0034] When the DC SSPC is turned on, the voltage across the capacitor C, i.e. the voltage U C , is initially 0, and the control command CMD controls the triode Q1 to be turned on and the triode Q2 to be turned off, the turn-on diode D ON is turned on, and the turn-off diode D OFF is reverse-biased and turned off, the turn-on MOS Q ON is in the turn-on state, and the control voltage V CC charges the capacitor C, and the drive control voltage V gc is raised from 0, and the main power tube Q of the DC SSPC is gradually turned on by the totem-pole push-pull circuit triode Q3. When the voltage U C is raised to V REF-ON -V th-QON , the turn-on MOS Q ON is turned off, and the drive control voltage V gc begins to be raised for the second time, and the turn-on process ends.

[0035] When the DC SSPC is turned off, the voltage across the capacitor C, i.e. the voltage UC The initial value is V CC -U D The control command CMD controls transistor Q1 to be cut off and Q2 to be turned on, thus turning off diode D. OFF Conduction, turn-on diode D ON Reverse cutoff, turning off MOSFET Q OFF When the circuit is open, capacitor C discharges, driving the control voltage V. gc By V CC As the voltage U decreases, the main power transistor Q of the DC SSPC, driven by transistor Q4 in the totem-pole push-pull circuit, is gradually turned off. C Reduce to V REF-OFF -V th-QOFF When, turn off MOSFET Q OFF Turn off, drive control voltage V gc A second drop occurred, and the shutdown process ended.

[0036] Figure 2 This is the operating mode diagram of a low-delay RC drive circuit, based on the turn-on MOSFET Q. ON and turn off MOSFET Q OFF The switching states divide the turn-on and turn-off processes into two stages, respectively. (a) shows the first stage of the turn-on process, (b) shows the second stage of the turn-on process, (c) shows the first stage of the turn-off process, and (d) shows the second stage of the turn-off process.

[0037] Opening process drive control voltage V gc The change over time can be expressed as:

[0038] (3)

[0039] Among them U C R represents the initial value of the capacitor voltage at different stages. eq-ON For the equivalent turn-on resistance, according to Q ON The switch state is set to R ON1 / / R ON2 Or R ON2 , τ ON =(R1+R2+R eq-ON C.

[0040] a) First stage of the opening process:

[0041] U C The initial value is 0, because V CC >V REF-ON >0, Q ON The device is in the ON state. Upon issuing an ON command, CMD changes from low to high, Q1 turns on, Q2 turns off, and V... CC Through R1, R2 and RON1 / / R ON2 Charging C, V gc The initial lift pressure value is V gc-ON1 , can be represented as:

[0042] (4)

[0043] V then gc The load current increases slowly in an exponential manner, controlling the gradual increase. Meanwhile, U... C It also rises slowly according to an exponential pattern, when U C =V REF-ON -V th-QON At that time, V gc The value is V gc-ON’ , can be represented as:

[0044] (5)

[0045] b) Second phase of the opening process:

[0046] U C The initial value is V REF-ON -V th-QON Q ON It is currently off. CC Through R1, R2 and R ON2 Charging C, V gc The second stage of lifting pressure value is V gc-ON2 , can be represented as:

[0047] (6)

[0048] Shutdown process V gc The change over time can be expressed as:

[0049] (7)

[0050] Where R eq-OFF For the equivalent turn-off resistance, according to Q OFF The switch state is set to R OFF1 / / R OFF2 Or R OFF1 , τ OFF =(R2+R eq-OFF C.

[0051] c) First stage of the shutdown process:

[0052] U C The initial value is V CC -U D Because of V CC -U D >V REF-OFF >0, QOFF The device is in the ON state. When a OFF command is issued, CMD changes from high to low, Q1 is turned off, Q2 is turned on, and V... gc Through R2 and R OFF1 / / R OFF2 Discharge to ground, V gc The initial decrease value is V gc-OFF1 , can be represented as:

[0053] (8)

[0054] V then gc The load current decreases slowly in an exponential manner, controlling the load current to decrease gradually. Meanwhile, U... C It also decreases slowly according to an exponential law, when U C =V REF-OFF -V th-QOFF At that time, V gc The value is V gc-OFF’ , can be represented as:

[0055] (9)

[0056] d) Second stage of the shutdown process:

[0057] U C The initial value is V REF-OFF -V th-QOFF Q OFF It is currently off. gc For through R2 and R OFF1 Discharge to ground, V gc The second decrease value is V gc-OFF2 , can be represented as:

[0058] (10)

[0059] Figure 3 This is a timing diagram of a low-delay RC drive circuit, where (a) shows the timing of switching a resistive load and (b) shows the timing of turning on a capacitive load.

[0060] When switching on / off a resistive load:

[0061] t1~t2: At time t1, U C When the value is 0, an enable command is issued, CMD changes from low to high, Q1 is turned on, Q2 is turned off, and D... ON Conduction, D OFF Reverse cutoff, V gc The initial lift pressure value is V gc-ON1 V gc-ON1 Slightly below the turn-on threshold voltage V1 of Q, then V gcexponentially slow growth, the DC SSPC current I SSPC starts to rise slowly.

[0062] t2~t3: at t2, U gc increases to V gc-ON’ , V gc-ON’ is slightly higher than the Miller voltage V2 of Q, at this time Q is turned on, I SSPC reaches a steady value, under the control of V REF-ON Q ON is turned off, V gc is raised from V gc-ON’ to V gc-ON2 , the turn-on process ends at t3.

[0063] t4~t5: at t4, U C is V CC -U D , at this time the turn-off instruction is issued, CMD changes from high level to low level, Q1 is cut off, Q2 is turned on, D OFF is turned on, D ON is reverse cut off, V gc is reduced from V CC to V gc-OFF1 , V gc-OFF1 is slightly higher than the Miller voltage V2 of Q, then V gc exponentially slow decrease, I SSPC starts to fall slowly.

[0064] t5~t6: at t5, U gc decreases to V gc-OFF’ , V gc-OFF’ is slightly lower than the turn-on threshold voltage V1 of Q, at this time Q is turned off, I SSPC decreases to zero, under the control of V REF-OFF Q OFF is turned off, V gc is reduced from V gc-OFF’ to V gc-OFF2 , the turn-off process ends at t6.

[0065] When the turn-on capacitive load:

[0066] t1~t2: at t1, U C is 0, the turn-on instruction is issued, CMD changes from low level to high level, Q1 is turned on, Q2 is cut off, D ON is turned on, D OFF is reverse cut off, the initial voltage lifting value of V gc is V gc-ON1 , V gc-ON1 is slightly lower than the turn-on threshold voltage V1 of Q, then V gcThe inrush current of capacitive loads is limited by the slow growth of the driving voltage, which increases exponentially.

[0067] t2~t3: One moment before t2, I SSPC Once the peak value is reached, the load capacitor is fully charged, and then I... SSPC Reduced to zero, V gc Growth to V gc-ON’ In V REF-ON Q under the influence ON Off, V gc By V gc-ON’ Rise to V gc-ON2 The process ends at time t3.

[0068] This invention modifies a traditional RC network circuit to form a novel RC network circuit, controlling the rise rate of the drive voltage to suppress inrush current and dynamically switching the on / off state of the MOSFET in the RC network circuit to change the time constant of the drive circuit, thereby improving the response speed of the DC SSPC. Specifically, this is achieved in three stages: In the on-off stage: Before the SSPC is turned on, the capacitor voltage in the RC network circuit is zero. Under the action of the on-off reference voltage, the MOSFET in the RC network circuit is in the conducting state. At the moment of on-off, the drive voltage rapidly reaches the turn-on threshold of the DC SSPC main power transistor under the action of the gate resistor, and then rises slowly due to the constraint of the RC network circuit, thereby suppressing the thermal shock of the DC SSPC main power transistor caused by the inrush current. In the dynamic switching stage: After the load current stabilizes, when the capacitor voltage in the RC network circuit rises to the difference between the turn-on reference voltage and the turn-on threshold voltage of the MOSFET, the MOSFET turns off, and the time constant of the drive circuit changes accordingly. In the response optimization stage: The switching of the time constant of the drive circuit causes the drive voltage to rise a second time, eliminating the "tailing phenomenon" of the drive voltage and ensuring that the drive voltage quickly reaches a steady state after the DC SSPC is turned on. This invention can regulate the rate of change of the driving voltage in stages, taking into account both turn-on safety and dynamic response speed. It features simple control and high reliability, effectively improving the shock resistance and switching performance of SSPC.

[0069] Example 2

[0070] This embodiment provides a DC SSPC, such as Figure 1 The DC SSPC consists of four parts: a DC source, a DC SSPC main power branch, a load, and a drive circuit. The main power transistor Q of the DC SSPC main power branch is an N-channel Si MOSFET, and the drive circuit adopts the aforementioned DC SSPC low-delay RC drive circuit.

[0071] The above examples only illustrate the technical idea of the present application, and cannot be used to limit the protection scope of the present application. Any modification made according to the technical idea of the present application on the basis of the technical scheme falls within the protection scope of the present application.

Claims

1. A DC SSPC low-delay RC drive circuit, characterized in that, It includes a transistor level conversion circuit, an RC network circuit, and a totem-pole push-pull circuit; the transistor level conversion circuit receives a control command and generates a drive control voltage through the RC network circuit, and the drive control voltage drives the main power transistor of the DC SSPC to turn on or off through the totem-pole push-pull circuit. The resistor-capacitor network circuit includes an on-state unit, an off-state unit, and a capacitor. The on-state unit and the off-state unit are connected in parallel and then connected in series with the capacitor. The turn-on unit includes a turn-on diode D. ON On-resistance R ON1 On-resistance R ON2 and turn on the MOSFET Q ON The turned-on MOS transistor Q ON With the turn-on resistor R ON1 Then connected in series with the turn-on resistor R ON2 Parallel connection, one end of the parallel circuit is connected in series with the turn-on diode D ON The other end is connected in series with the capacitor; the turn-on diode D ON The anode of the transistor is connected to the output terminal of the transistor level conversion circuit; the turn-on MOS transistor Q ON The gate connection is turned on with the reference voltage. V REF-ON ; The shutdown unit includes a shutdown diode D. OFF , turn-off resistor R OFF1 , turn-off resistor R OFF2 and turn off MOSFET Q OFF The turn-on diode D ON and the turn-off diode D OFF The on-state voltage drop is equal; the off-state MOS transistor Q OFF With the shut-off resistor R OFF2 Then connected in series with the turn-off resistor R OFF1 Parallel connection, with one end of the parallel circuit connected in series with the turn-off diode D. OFF The other end is connected in series with the capacitor; the turn-off diode D OFF The cathode is connected to the output terminal of the transistor level conversion circuit; the turn-off MOS transistor Q OFF The gate connection is turned off reference voltage V REF-OFF .

2. The DC SSPC low-delay RC drive circuit as described in claim 1, characterized in that, The turn-on reference voltage V REF-ON Voltage divider resistors connected in series with turn-on reference voltage R div-ON1 and the on-state reference voltage divider resistor R div-ON2 For control voltage V CC Voltage divider generation, the shutdown reference voltage V REF-OFF Voltage divider resistors connected in series to the turn-off reference voltage R div-OFF1 and the voltage divider resistor for turning off the reference voltage R div-OFF2 For control voltage V CC Pressure is generated.

3. The DC SSPC low-delay RC drive circuit as described in claim 1, characterized in that, The transistor level conversion circuit includes resistors. R 0. Resistance R 1. Resistance R 2. Transistors Q1 and Q2; transistor Q1 and the resistor R 0 is connected in series, the transistor Q2 and the resistor R 1. Series connection, two series circuits are then connected in parallel by a control voltage. V CC Power is supplied; the base of transistor Q2 is connected to the emitter of transistor Q1; the base of transistor Q1 is connected to the control command; and the emitter of transistor Q2 is connected to the resistor. R 2, one end of the resistor R The other end of 2 is the output terminal of the transistor level conversion circuit.

4. The DC SSPC low-delay RC drive circuit as described in claim 1, characterized in that, The turned-on MOS transistor Q ON The turn-off MOSFET Q is an enhancement-mode N-channel MOSFET. OFF It is an enhancement-mode P-channel MOSFET.

5. The DC SSPC low-delay RC drive circuit as described in claim 1, characterized in that, When the DC SSPC is turned on, the initial voltage across the capacitor is 0, and the turn-on diode D... ON When the diode D is turned on, the turn-off diode is turned on. OFF Reverse cutoff, the turn-on MOS transistor Q ON In the on state, control voltage V CC The capacitor is charged, and the drive control voltage is... V gc Starting from 0, the main power transistor of the DC SSPC is gradually turned on via the totem-pole push-pull circuit. When the voltage across the capacitor increases to the turn-on reference voltage... V REF-ON With the turned-on MOS transistor Q ON Turn-on threshold voltage V th-QON When the difference is reached, the MOS transistor Q is turned on. ON When the circuit is turned off, the drive control voltage increases for the second time, and the turn-on process ends.

6. The DC SSPC low-delay RC drive circuit as described in claim 1, characterized in that, When the DC SSPC is turned off, the initial voltage across the capacitor is the control voltage. V CC The difference between the forward voltage drop and the voltage drop of the diode, the turn-off diode D OFF The turn-on diode D is activated. ON Reverse cutoff, the turn-off MOS transistor Q OFF When in the ON state, the capacitor discharges, and the drive control voltage is... V CC The voltage is reduced by gradually turning off the main power transistor of the DC SSPC driven by the totem-pole push-pull circuit, until the voltage across the capacitor drops to the turn-off reference voltage. V REF-OFF With the turn-off MOS transistor Q OFF Turn-on threshold voltage V th-QOFF When the difference is reached, the turn-off MOS transistor Q is activated. OFF The drive control voltage is reduced for the second time upon shutdown, ending the shutdown process.

7. A DC SSPC, characterized in that, Includes the DC SSPC low-delay RC drive circuit as described in any one of claims 1-6.

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