Direct current SSPC capacitive load and short circuit fault distinguishing circuit and method

Abstract

The invention discloses a direct current SSPC capacitive load and short circuit fault distinguishing circuit and method, and relates to the field of power electronics and electricians. The circuit comprises a feedback circuit for acquiring a feedback signal; the current-limiting judgment circuit judges whether a current-limiting state is entered or not according to the feedback signal and outputs a current-limiting state signal; the current-limiting control circuit outputs a control voltage according to the first current-limiting state signal and the current feedback signal; the load distinguishing circuit performs capacitive load and short-circuit fault distinguishing according to the second current limiting state signal and the load end voltage, and outputs a short-circuit signal; and the execution circuit performs execution processing of a current limiting action according to the control voltage and performs fault protection or load charging processing according to the short circuit signal. The invention aims to accurately distinguish the capacitive load from the load short-circuit fault and improve the reliability.

Description

Technical Field

[0001] The present application relates to the field of power electronics and electrical engineering, and in particular to a circuit and method for distinguishing between a DC SSPC capacitive load and a short-circuit fault. Background Art

[0002] Solid State Power Controller (SSPC) is an intelligent power distribution device with power semiconductor as the core, integrating the switch control of relays and the fault protection functions of circuit breakers. As the core component of aircraft solid-state power distribution system, SSPC has the advantages of no contact, no arc, no noise, fast response, low electromagnetic interference, long life, high reliability and convenient computer remote control. Therefore, it is widely used in aircraft, tanks, ships and civil power distribution networks.

[0003] With the development of more electric aircraft, the number and capacity of onboard electrical equipment have increased significantly. When a capacitive load is started, an impact current will be generated. Its current characteristics are similar to the short-circuit fault current, which can easily cause the short-circuit protection to malfunction when the DC SSPC is connected to the capacitive load, causing the load to fail to work normally; or the protection does not operate when the load has a short-circuit fault, and the fault cannot be isolated, causing the power distribution system to burn out. In order to ensure the safe and reliable operation of the aircraft, the DC SSPC is required to accurately and quickly distinguish between capacitive loads and short-circuit faults.

[0004] The existing technology is to distinguish between capacitive load and short circuit fault by comparing the SSPC current after a certain delay with the short circuit current threshold after the DC SSPC enters the current limiting state. Usually the fixed delay is hundreds of microseconds to several milliseconds, and the distinction time is long. The DC SSPC is prone to thermal failure due to long-term high power consumption.

[0005] Alternatively, an identification curve is constructed using equivalent capacitor voltage, and the capacitive load and short circuit fault are distinguished by judging whether the actual load voltage intersects with the identification curve. However, as the capacitive load capacity of the DC SSPC increases, the time required for this identification method becomes longer, making it difficult to meet the application requirements of SSPC for rapid load identification.

[0006] Therefore, there is an urgent need to study a new load differentiation solution that is faster and more compatible with loads. Summary of the invention

[0007] The purpose of the present application is to provide a DC SSPC capacitive load and short-circuit fault distinguishing circuit and method, which can accurately distinguish capacitive load and load short-circuit fault and improve reliability.

[0008] To achieve the above objectives, this application provides the following solutions:

[0009] In a first aspect, the present application provides a circuit for distinguishing between capacitive load and short - circuit fault of a DC SSPC, including: a DC power controller and a load; the DC power controller is connected to the load;

[0010] Wherein, the DC power controller includes: a feedback circuit, a load discrimination circuit, a current - limiting judgment circuit, a current - limiting control circuit, an execution circuit and a sampling resistor;

[0011] The feedback circuit is respectively connected to the sampling resistor, the load discrimination circuit, the current - limiting control circuit and the current - limiting judgment circuit;

[0012] The load discrimination circuit is further connected to the execution circuit; the current - limiting judgment circuit is respectively connected to the current - limiting control circuit and the load discrimination circuit; the execution circuit is further connected to the sampling resistor; the sampling resistor is connected to the load;

[0013] The feedback circuit is used to obtain a feedback signal; the feedback signal includes: the load - end voltage and a current feedback signal corresponding to the sampling resistor;

[0014] The current - limiting judgment circuit is used to judge whether it enters the current - limiting state according to the feedback signal and output a current - limiting state signal; the current - limiting state signal includes: a first current - limiting state signal and a second current - limiting state signal;

[0015] The current - limiting control circuit is used to output a control voltage according to the first current - limiting state signal and the current feedback signal;

[0016] The load discrimination circuit is used to distinguish between capacitive load and short - circuit fault according to the second current - limiting state signal and the load - end voltage and output a short - circuit signal;

[0017] The execution circuit is used for:

[0018] Performing an execution process of current - limiting action according to the control voltage;

[0019] Performing fault protection or load charging process according to the short - circuit signal.

[0020] Optionally, the load discrimination circuit includes: an operational amplifier, a comparator, an SR latch, an NPN transistor, a first capacitor, a second capacitor, a first resistor, a second resistor, a third resistor, a fourth resistor, a fifth resistor, a sixth resistor, a seventh resistor and an eighth resistor;

[0021] The first terminal of the second resistor is connected to the terminal corresponding to the second current - state signal; the second terminal of the second resistor is respectively connected to the second terminal of the first resistor and the base of the NPN transistor; the first terminal of the first resistor is connected to the emitter of the NPN transistor and is grounded after connection;

[0022] The collector of the NPN transistor is connected to the first terminal of the third resistor; the second terminal of the third resistor is respectively connected to the first terminal of the fourth resistor and the first terminal of the first capacitor; the second terminal of the fourth resistor is respectively connected to the second terminal of the first capacitor and the output terminal of the operational amplifier;

[0023] The first terminal of the second capacitor is grounded; the second terminal of the second capacitor is connected to the first terminal of the fifth resistor; the second terminal of the fifth resistor is connected to the inverting input terminal of the operational amplifier;

[0024] The first terminal of the sixth resistor is connected to the terminal corresponding to the load terminal voltage; the second terminal of the sixth resistor is connected to the non-inverting input terminal of the operational amplifier;

[0025] The output terminal of the operational amplifier is also connected to the first terminal of the seventh resistor; the second terminal of the seventh resistor is connected to the non-inverting input terminal of the comparator; the inverting input terminal of the comparator is connected to the reference voltage terminal; the output terminal of the comparator is respectively connected to the second terminal of the eighth resistor and the set terminal of the SR latch; the first terminal of the eighth resistor is connected to the DC voltage source;

[0026] The output terminal of the SR latch is connected to the execution circuit.

[0027] Optionally, the feedback circuit specifically includes: a current feedback circuit and a load voltage feedback circuit;

[0028] The current feedback circuit is respectively connected to the sampling resistor, the current limiting control circuit and the current limiting judgment circuit;

[0029] The load voltage feedback circuit is respectively connected to the load, the current limiting judgment circuit and the load discrimination circuit;

[0030] The current feedback circuit is used to obtain the current feedback signal corresponding to the sampling resistor;

[0031] The load voltage feedback circuit is used to obtain the load terminal voltage.

[0032] Optionally, the execution circuit includes: a short-circuit protection circuit, a drive amplification circuit and a main power circuit;

[0033] The short-circuit protection circuit is connected to the load discrimination circuit; the drive amplification circuit is connected to the short-circuit protection circuit; the main power circuit is connected to the drive amplification circuit;

[0034] The short-circuit protection circuit is used to perform circuit protection processing according to the short-circuit signal;

[0035] The drive amplification circuit is used for:

[0036] After performing power amplification processing based on the short - circuit signal, control the turn - off of the main power circuit for fault protection, or control the main power circuit to perform load charging processing;

[0037] Perform power amplification processing based on the control voltage, and control the main power circuit to perform current - limiting operation execution processing.

[0038] Optionally, when the result judged by the current - limiting judgment circuit is a non - current - limiting state, the first current - limiting state signal is at a low level, and the second current - limiting state signal is at a high level; the low level is a voltage value less than the set threshold; the high level is a voltage value greater than the set threshold;

[0039] When the result judged by the current - limiting judgment circuit is a current - limiting state, the first current - limiting state signal is at a high level, and the second current - limiting state signal is at a low level.

[0040] In a second aspect, the present application provides a method for distinguishing between capacitive load and short - circuit fault of a DC SSPC. The method for distinguishing between capacitive load and short - circuit fault of a DC SSPC is implemented by a circuit for distinguishing between capacitive load and short - circuit fault of a DC SSPC; the method includes:

[0041] Obtain a feedback signal; the feedback signal includes: load - end voltage and current feedback signal;

[0042] Judge whether to enter a current - limiting state according to the feedback signal, and output a current - limiting state signal; the current - limiting state signal includes: a first current - limiting state signal and a second current - limiting state signal;

[0043] Output a control voltage according to the first current - limiting state signal and the current feedback signal;

[0044] Distinguish between capacitive load and short - circuit fault according to the second current - limiting state signal and the load - end voltage, and output a short - circuit signal;

[0045] Perform current - limiting operation execution processing according to the control voltage;

[0046] Perform fault protection or load charging processing according to the short - circuit signal.

[0047] Optionally, judging whether to enter a current - limiting state according to the feedback signal and outputting a current - limiting state signal specifically includes:

[0048] Compare the feedback signal with a set signal threshold to obtain a comparison result;

[0049] Judge whether to enter a current - limiting state according to the comparison result to obtain a judgment result;

[0050] If the judgment result is yes, the output first current limiting state signal is at a high level and the second current limiting state signal is at a low level; wherein, the low level is a voltage value less than a set threshold; the high level is a voltage value greater than the set threshold;

[0051] If the judgment result is no, the output first current limiting state signal is at a low level and the second current limiting state signal is at a high level.

[0052] Optionally, distinguish between capacitive load and short - circuit fault according to the second current limiting state signal and the load terminal voltage, and output a short - circuit signal, which specifically includes:

[0053] Determine a characteristic quantity according to the load terminal voltage;

[0054] Compare the characteristic quantity with a set reference voltage to distinguish between capacitive load and short - circuit fault;

[0055] When the discrimination result is a short - circuit fault, output a short - circuit signal according to the second current limiting state signal. At this time, the short - circuit signal is set to a high level;

[0056] When the discrimination result is a capacitive load, output a short - circuit signal according to the second current limiting state signal. At this time, the short - circuit signal remains at a low level.

[0057] Optionally, determine a characteristic quantity according to the load terminal voltage, which specifically includes:

[0058] Construct a characteristic quantity based on the sum of proportion and differentiation according to the load terminal voltage.

[0059] Optionally, the expression of the characteristic quantity is:

[0060]

[0061] wherein, V te is the characteristic quantity; k V is the voltage proportionality coefficient in the load discrimination circuit; k VFB is the feedback coefficient in the load voltage feedback circuit; V load is the load terminal voltage; k dV is the voltage differentiation coefficient in the load discrimination circuit; t is the time.

[0062] According to the specific embodiments provided by the present application, the present application has the following technical effects:

[0063] The present application provides a circuit and method for distinguishing capacitive loads and short - circuit faults in a DC SSPC. A feedback signal is obtained through a feedback circuit; a current - limiting judgment circuit determines whether to enter a current - limiting state based on the feedback signal and outputs a current - limiting state signal; a current - limiting control circuit outputs a control voltage according to the first current - limiting state signal and the current feedback signal; a load - distinguishing circuit distinguishes capacitive loads and short - circuit faults based on the second current - limiting state signal and the load - terminal voltage and outputs a short - circuit signal; an execution circuit performs an execution process of current - limiting actions according to the control voltage, and performs fault protection or load charging processing according to the short - circuit signal. By using the current - limiting judgment circuit to judge the current - limiting state, and then based on the load - distinguishing circuit to distinguish capacitive loads and short - circuit faults, capacitive loads and load short - circuit faults can be accurately distinguished. In addition, due to the existence of the current - limiting judgment circuit, the current - limiting control circuit, and the load - distinguishing circuit, the execution circuit can be controlled to perform the execution process of current - limiting actions or perform fault protection or load charging processing, so as to improve the reliability of the circuit. Therefore, the present application can accurately distinguish capacitive loads and load short - circuit faults and improve the reliability. BRIEF DESCRIPTION OF THE DRAWINGS

[0064] In order to more clearly illustrate the technical solutions in the embodiments of the present application or related technologies, the following will briefly introduce the drawings required for use in the embodiments. Obviously, the drawings in the following description are only some embodiments of the present application. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained based on these drawings.

[0065] Figure 1 FIG. is a schematic diagram for distinguishing capacitive loads and short - circuit faults in a DC SSPC.

[0066] Figure 2 FIG. is a current diagram of the load - distinguishing circuit in a DC SSPC.

[0067] Figure 3 FIG. is a working timing diagram during a short - circuit fault.

[0068] Figure 4 FIG. is a working timing diagram for capacitive loads.

[0069] Reference numerals: operational amplifier - OP1, comparator - CMP1, SR latch - U1, NPN transistor - T1, first capacitor - C1, second capacitor - C2, first resistor - R1, second resistor - R2, third resistor - R3, fourth resistor - R4, fifth resistor - R5, sixth resistor - R6, seventh resistor - R7, eighth resistor - R8, sampling resistor - R sense . DETAILED DESCRIPTION OF THE EMBODIMENTS

[0070] The following will clearly and completely describe the technical solutions in the embodiments of the present application with reference to the accompanying drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments in the present application without creative efforts shall fall within the protection scope of the present application.

[0071] The present application aims to solve the problems of misprotection when the DC solid-state power controller connects a capacitive load or non-protection during a short-circuit fault. The discrimination method includes a load discrimination circuit, a short-circuit protection circuit, a drive amplification circuit, a current-limiting judgment circuit, a current-limiting control circuit, a current feedback circuit, a load voltage feedback circuit, a main power circuit, and a sampling resistor Rsense. After the current-limiting judgment circuit determines that the DC SSPC enters the current-limiting state, a characteristic quantity V is constructed using the sum of the ratio and derivative of the load voltage feedback signal V L_FB , and by comparing the characteristic quantity V te with the set reference voltage V te and V REF1 to distinguish between capacitive loads and short-circuit faults. In addition, the present application also provides a load discrimination circuit. The present application can accurately distinguish between capacitive loads and load short-circuit faults. The load discrimination speed is not limited by the load capacitance value, and it has good versatility, effectively improving the reliability of the DC solid-state power controller.

[0072] To make the above objects, features, and advantages of the present application more obvious and understandable, the present application will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0073] In an exemplary embodiment, as Figure 1 shown, a circuit for discriminating between capacitive loads and short-circuit faults of a DC SSPC is provided. The circuit includes: a DC power controller and a load; the DC power controller is connected to the load.

[0074] Among them, the DC power controller includes: a feedback circuit, a load discrimination circuit, a current-limiting judgment circuit, a current-limiting control circuit, an execution circuit, and a sampling resistor R sense .

[0075] The feedback circuit is respectively connected to the sampling resistor R sense , the load discrimination circuit, the current-limiting control circuit, and the current-limiting judgment circuit. The load discrimination circuit is also connected to the execution circuit; the current-limiting judgment circuit is also respectively connected to the current-limiting control circuit and the load discrimination circuit; the execution circuit is also connected to the sampling resistor; the sampling resistor R sense is connected to the load.

[0076] The feedback circuit is used to obtain a feedback signal; the feedback signal includes: the load terminal voltage and the current feedback signal corresponding to the sampling resistor R sense .

[0077] In one embodiment, the feedback circuit specifically includes: a current feedback circuit and a load voltage feedback circuit.

[0078] The current feedback circuit is respectively connected to a sampling resistor, a current limiting control circuit, and a current limiting judgment circuit; the load voltage feedback circuit is respectively connected to a load, the current limiting judgment circuit, and a load discrimination circuit.

[0079] The current feedback circuit is used to obtain the current feedback signal corresponding to the sampling resistor R sense ; the load voltage feedback circuit is used to obtain the voltage at the load end.

[0080] The current limiting judgment circuit is used to judge whether to enter the current limiting state according to the feedback signal and output a current limiting state signal; the current limiting state signal includes: a first current limiting state signal and a second current limiting state signal.

[0081] When the judgment result of the current limiting judgment circuit is a non-current limiting state, the first current limiting state signal is at a low level and the second current limiting state signal is at a high level; the low level is a voltage value less than the set threshold; the high level is a voltage value greater than the set threshold.

[0082] When the judgment result of the current limiting judgment circuit is a current limiting state, the first current limiting state signal is at a high level and the second current limiting state signal is at a low level.

[0083] The current limiting control circuit is used to output a control voltage according to the first current limiting state signal and the current feedback signal.

[0084] The load discrimination circuit is used to distinguish between a capacitive load and a short circuit fault according to the second current limiting state signal and the voltage at the load end and output a short circuit signal.

[0085] As Figure 2 shown, the load discrimination circuit includes: an operational amplifier OP1, a comparator CMP1, an SR latch U1, an NPN transistor T1, a first capacitor C1, a second capacitor C2, a first resistor R1, a second resistor R2, a third resistor R3, a fourth resistor R4, a fifth resistor R5, a sixth resistor R6, a seventh resistor R7, and an eighth resistor R8.

[0086] The first terminal of the second resistor R2 is connected to the terminal corresponding to the second current state signal; the second terminal of the second resistor R2 is respectively connected to the second terminal of the first resistor R1 and the base of the NPN transistor T1; the first terminal of the first resistor R1 is connected to the emitter of the NPN transistor T1 and is grounded after connection.

[0087] The collector of the NPN transistor T1 is connected to the first terminal of the third resistor R3; the second terminal of the third resistor R3 is respectively connected to the first terminal of the fourth resistor R4 and the first terminal of the first capacitor C1; the second terminal of the fourth resistor R4 is respectively connected to the second terminal of the first capacitor C1 and the output terminal of the operational amplifier OP1.

[0088] The first terminal of the second capacitor C2 is grounded; the second terminal of the second capacitor C2 is connected to the first terminal of the fifth resistor R5; the second terminal of the fifth resistor R5 is connected to the inverting input terminal of the operational amplifier OP1.

[0089] The first terminal of the sixth resistor R6 is connected to the terminal corresponding to the load terminal voltage; the second terminal of the sixth resistor R6 is connected to the non-inverting input terminal of the operational amplifier OP1.

[0090] The output terminal of the operational amplifier OP1 is also connected to the first terminal of the seventh resistor R7; the second terminal of the seventh resistor R7 is connected to the non-inverting input terminal of the comparator CMP1; the inverting input terminal of the comparator CMP1 is connected to the reference voltage terminal; the output terminal of the comparator CMP1 is respectively connected to the second terminal of the eighth resistor R8 and the set terminal of the SR latch U1; the first terminal of the eighth resistor R8 is connected to the DC voltage source; the output terminal of the SR latch U1 is connected to the execution circuit.

[0091] The execution circuit is used to perform the execution process of the current limiting action according to the control voltage; the execution circuit is also used to perform the fault protection or load charging process according to the short circuit signal.

[0092] The execution circuit includes: a short circuit protection circuit, a drive amplification circuit, and a main power circuit; the short circuit protection circuit is connected to the load discrimination circuit; the drive amplification circuit is connected to the short circuit protection circuit; the main power circuit is connected to the drive amplification circuit.

[0093] The short circuit protection circuit is used to perform the circuit protection process according to the short circuit signal; the drive amplification circuit is used to perform the power amplification process according to the short circuit signal and then control the turn-off of the main power circuit to perform the fault protection, or control the main power circuit to perform the load charging process.

[0094] The drive amplification circuit is also used to perform the power amplification process according to the control voltage and control the main power circuit to perform the execution process of the current limiting action.

[0095] Specifically, as Figure 1 shown, the DC SSPC capacitive load and short circuit fault discrimination circuit includes a load discrimination circuit, a short circuit protection circuit, a drive amplification circuit, a current limiting judgment circuit, a current limiting control circuit, a current feedback circuit, a load voltage feedback circuit, a main power circuit, a load, and a sampling resistor R sense . The DC power voltage source U inThe positive terminal is connected to the DC SSPC power terminal P in and the DC SSPC power terminal P out is connected to the first terminal of the load, and the second terminal of the load is connected to the DC power voltage source U in negative terminal.

[0096] The load voltage feedback circuit is used to detect the load terminal voltage in the DC SSPC and outputs a voltage feedback signal V L_FB ; the current feedback circuit is used to detect the current in the SSPC, and the input is the voltage of the sampling resistor R sense and outputs a current feedback signal LCS; the current limiting judgment circuit determines whether the DC SSPC enters the current limiting state according to the detected SSPC voltage (load terminal voltage) and the current feedback signal, and outputs a first current limiting state signal Limit and a second current limiting state signal When the SSPC is in the non-current limiting state, the Limit signal is at a low level while is at a high level. When the SSPC is in the current limiting state, Limit is at a high level while is at a low level; when the SSPC is in the current limiting state, the current limiting control circuit outputs a control voltage V gc1 which is power amplified by the drive amplifier circuit to control the main power circuit to perform the current limiting action; the load discrimination circuit uses the sum of the ratio and derivative of the voltage feedback signal V L_FB of the load terminal voltage to construct a characteristic quantity V te and distinguishes capacitive loads and short circuit faults by comparing the characteristic quantity V te with the set reference voltage V REF1 . When the SSPC determines a load short circuit fault, the short circuit signal SC is set to a high level, and the short circuit protection circuit turns off the main power circuit through the drive amplifier circuit, and the SSPC completes the short circuit fault protection. When the SSPC determines a capacitive load, the current limiting signal Limit remains at a high level and the short circuit signal SC remains at a low level until the load capacitor is fully charged.

[0097] The characteristic quantity V te can be expressed as:

[0098]

[0099] where V te is the characteristic quantity; k V is the voltage proportionality coefficient in the load discrimination circuit; k VFB is the feedback coefficient in the load voltage feedback circuit; V load is the load terminal voltage; k dV is the voltage differential coefficient in the load discrimination circuit; t is the time.

[0100] If the characteristic quantity V teless than or equal to the set reference voltage V REF1 When it is the case, the DC SSPC judges a load short - circuit fault, sets the short - circuit signal SC to a high level, and the short - circuit protection circuit turns off the main power circuit through the drive and amplification circuit, and the DC SSPC completes the short - circuit protection. When the characteristic quantity V te is always greater than the set reference voltage V REF1 , the DC SSPC judges it as a capacitive load, keeps the current - limiting signal Limit at a high level, and keeps the short - circuit signal SC at a low level until the load capacitor is fully charged, and then resets the current - limiting signal Limit to a low level.

[0101] As Figure 2 shown, the load discrimination circuit consists of an operational amplifier OP1, a comparator CMP1, an SR latch U1, an NPN transistor T1, two capacitors (the first capacitor C1 and the second capacitor C2) and eight resistors (the first resistor R1, the second resistor R2, the third resistor R3, the fourth resistor R4, the fifth resistor R5, the sixth resistor R6, the seventh resistor R7 and the eighth resistor R8). The first terminal of the sixth resistor R6 is connected to the terminal corresponding to the load terminal voltage, that is, the terminal corresponding to the voltage feedback signal V L_FB . The second terminal of the sixth resistor R6 is connected to the non - inverting input terminal of the operational amplifier OP1; the first terminal of the second capacitor C2 is connected to the analog ground Fgnd, that is, the first terminal of the second capacitor C2 is grounded. The second terminal of the second capacitor C2 is connected to the first terminal of the fifth resistor R5; the first terminal of the first resistor R1 is connected to the emitter of the NPN transistor T1 at the analog ground Fgnd; the first terminal of the second resistor R2 is connected to the current - limiting state signal , that is, the terminal corresponding to the second current - limiting state signal; the second terminal of the first resistor R1, the second terminal of the second resistor R2 and the base of the NPN transistor T1 are connected to the common point A; the collector of the NPN transistor T1 is connected to the first terminal of the third resistor R3; the second terminal of the fifth resistor R5, the inverting input terminal of the operational amplifier OP1, the second terminal of the third resistor R3, the first terminal of the fourth resistor R4 and the first terminal of the first capacitor C1 are connected to the common point B; the second terminal of the fourth resistor R4, the second terminal of the first capacitor C1, the output terminal of the operational amplifier OP1 and the first terminal of the seventh resistor R7 are connected to the terminal corresponding to the characteristic quantity V te ; the second terminal of the seventh resistor R7 is connected to the non - inverting input terminal of the comparator CMP1; the inverting input terminal of the comparator CMP1 is connected to the set reference voltage V REF1The corresponding terminal; the first terminal of the eighth resistor R8 is connected to the DC voltage source VCC; the output terminal of the comparator CMP1, the second terminal of the eighth resistor R8, and the set terminal of the SR latch U1 are connected to the common point E; the reset terminal of the SR latch U1 is connected to the SSPC switch control signal CMD; the output terminal of the SR latch U1 is the terminal corresponding to the short - circuit signal SC.

[0102] In an exemplary embodiment, the present application further provides a method for distinguishing between capacitive load and short - circuit fault of a DC SSPC. The method for distinguishing between capacitive load and short - circuit fault of a DC SSPC is implemented by a circuit for distinguishing between capacitive load and short - circuit fault of a DC SSPC. The method includes:

[0103] Obtain a feedback signal; the feedback signal includes: the load - end voltage and the current feedback signal.

[0104] Judge whether to enter the current - limiting state according to the feedback signal, and output a current - limiting state signal; the current - limiting state signal includes: a first current - limiting state signal and a second current - limiting state signal.

[0105] Output a control voltage according to the first current - limiting state signal and the current feedback signal.

[0106] Distinguish between capacitive load and short - circuit fault according to the second current - limiting state signal and the load - end voltage, and output a short - circuit signal.

[0107] Execute the current - limiting action according to the control voltage.

[0108] Perform fault protection or load charging processing according to the short - circuit signal.

[0109] In one embodiment, judging whether to enter the current - limiting state according to the feedback signal and outputting a current - limiting state signal specifically includes:

[0110] Compare the feedback signal with a set signal threshold to obtain a comparison result; judge whether to enter the current - limiting state according to the comparison result to obtain a judgment result.

[0111] If the judgment result is yes, the output first current - limiting state signal is at a high level and the second current - limiting state signal is at a low level; wherein, the low level is a voltage value less than the set threshold; the high level is a voltage value greater than the set threshold.

[0112] If the judgment result is no, the output first current - limiting state signal is at a low level and the second current - limiting state signal is at a high level.

[0113] In one embodiment, distinguishing between capacitive load and short - circuit fault according to the second current - limiting state signal and the load - end voltage and outputting a short - circuit signal specifically includes:

[0114] Determine the characteristic quantity according to the load terminal voltage; compare the characteristic quantity with the set reference voltage to distinguish between capacitive load and short - circuit fault; when the discrimination result is a short - circuit fault, output a short - circuit signal according to the second current - limiting state signal. At this time, the short - circuit signal is set to a high level.

[0115] When the discrimination result is a capacitive load, output a short - circuit signal according to the second current - limiting state signal. At this time, the short - circuit signal remains at a low level.

[0116] Determine the characteristic quantity according to the load terminal voltage, specifically including:

[0117] Construct based on the sum of proportion and differentiation according to the load terminal voltage to obtain the characteristic quantity.

[0118] The expression of the characteristic quantity is:

[0119]

[0120] Among them, V te is the characteristic quantity; k V is the voltage proportionality coefficient in the load discrimination circuit; k VFB is the feedback coefficient in the load voltage feedback circuit; V load is the load terminal voltage; k dV is the voltage differential coefficient in the load discrimination circuit; t is the time.

[0121] Taking a certain type of DC SSPC as an example, elaborate on the working timing of the load discrimination method in this application. This DC SSPC uses a power semiconductor as the current - limiting device and adopts a current - closed - loop current - limiting control method. When the DC SSPC enters the current - limiting state, the current is limited to I Limit .

[0122] Figure 3 It is the load discrimination working timing diagram when the load is a short - circuit fault.

[0123] The DC SSPC is initially in the conducting state.

[0124] t1 - t2: At time t1, the load has a short - circuit fault, and the current I SSPC of the DC SSPC rises rapidly.

[0125] t2 - t3: At time t2, the current - limiting judgment circuit determines that the DC SSPC enters the current - limiting state, and the current - limiting state signal Limt is set to a high level and latched, reset to a low level and latched. Under the action of the current - limiting control circuit, the equivalent resistance of the main power circuit of the DC SSPC increases, and the current I SSPC is limited to I Limit , and the load voltage V load rapidly decreases and remains at a low value V loadSCDue to the operation delay of the load discrimination circuit, the characteristic quantity V te starts to decline after a certain delay.

[0126] t3 - t4: At time t3, the characteristic quantity V te declines to the reference value V REF1 , the short - circuit signal SC is set to high level and latched. Under the action of the short - circuit protection circuit, the main power circuit of the DC SSPC is gradually turned off, and the current I SSPC and the load voltage V load gradually decrease to zero.

[0127] Figure 4 is the load discrimination working timing diagram when the load is a capacitive load.

[0128] The DC SSPC is initially in the off state.

[0129] t1 - t2: At time t1, the DC SSPC connects the capacitive load, and the current I SSPC of the DC SSPC rises rapidly.

[0130] t2 - t3: At time t2, the current - limiting judgment circuit determines that the DC SSPC enters the current - limiting state, and the current - limiting state signal Limt is set to high level and latched, reset to low level and latched. Under the action of the current - limiting control circuit, the current I SSPC of the DC SSPC is limited to I Limit . As the load capacitor charges, the load voltage V load rises linearly. After a certain operation delay of the load discrimination circuit, the characteristic quantity V te starts to rise linearly from the lowest value V te1 .

[0131] t3 - t4: The characteristic quantity V te is always greater than the reference value V REF1 , the short - circuit signal SC remains at low level until at time t4, the current - limiting judgment circuit determines that the load capacitor charging is complete, the DC SSPC exits the current - limiting state, Limt is reset to low level, and is set to high level.

[0132] The beneficial effects of this application are as follows:

[0133] 1) Accurately distinguish capacitive load from load short - circuit fault. When connecting a capacitive load, the DC SSPC is not mis - protected, and in case of short - circuit fault, the DC SSPC is quickly protected.

[0134] 2) Quickly distinguish the load. The load discrimination speed is not limited by the load capacitance value, and the load discrimination time can be shortened to within one hundred microseconds, shortening the duration of the DC SSPC current limiting state under short-circuit conditions, thereby reducing the heat generated by the DC SSPC, reducing the risk of thermal failure of the DC SSPC, and improving the reliability of the DC SSPC.

[0135] 3) The current limiting branch method based on the current limiting resistor, the open-loop / closed-loop gate voltage current limiting method using the power semiconductor as the current limiting device, the segmented current limiting method combining the current limiting branch and the power transistor gate voltage control, etc. have good versatility.

[0136] The technical features of the above embodiments can be combined arbitrarily. For the sake of brevity of description, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, it should be considered as the scope described in this specification.

[0137] Specific examples are used in this article to elaborate on the principles and implementation manners of the present application. The description of the above embodiments is only used to help understand the method and its core idea of the present application; at the same time, for those of ordinary skill in the art, according to the idea of the present application, there will be changes in the specific implementation manners and application scopes. In summary, the content of this specification should not be construed as a limitation to the present application.

Claims

1. A DC SSPC capacitive load and short circuit fault distinguishing circuit, characterized in that: include: A DC power controller and a load; the DC power controller is connected to the load; Wherein, the DC power controller includes: a feedback circuit, a load differentiation circuit, a current limiting judgment circuit, a current limiting control circuit, an execution circuit and a sampling resistor; The feedback circuit is respectively connected to the sampling resistor, the load distinguishing circuit, the current limiting control circuit and the current limiting judgment circuit; The load differentiation circuit is also connected to the execution circuit; the current limiting judgment circuit is also connected to the current limiting control circuit and the load differentiation circuit respectively; the execution circuit is also connected to the sampling resistor; the sampling resistor is connected to the load; The feedback circuit is used to obtain a feedback signal; the feedback signal includes: a load terminal voltage and a current feedback signal corresponding to the sampling resistor; The current limiting judgment circuit is used to judge whether to enter the current limiting state according to the feedback signal, and output a current limiting state signal; the current limiting state signal includes: a first current limiting state signal and a second current limiting state signal; The current limiting control circuit is used to output a control voltage according to the first current limiting state signal and the current feedback signal; The load distinguishing circuit is used to distinguish between a capacitive load and a short-circuit fault according to the second current limiting state signal and the load terminal voltage, and output a short-circuit signal; The execution circuit is used for: performing a current limiting action according to the control voltage; Fault protection or load charging processing is performed according to the short-circuit signal.

2. The DC SSPC capacitive load and short circuit fault distinguishing circuit according to claim 1, characterized in that: The load distinguishing circuit includes: an operational amplifier, a comparator, an SR latch, an NPN transistor, A first capacitor, a second capacitor, a first resistor, a second resistor, a third resistor, a fourth resistor, a fifth resistor, a sixth resistor, a seventh resistor, and an eighth resistor; The first terminal of the second resistor is connected to the terminal corresponding to the second current state signal; the second terminal of the second resistor is respectively connected to the second terminal of the first resistor and the base of the NPN transistor; the first terminal of the first resistor is connected to the emitter of the NPN transistor, and is grounded after the connection; The collector of the NPN transistor is connected to the first terminal of the third resistor; the second terminal of the third resistor is respectively connected to the first terminal of the fourth resistor and the first terminal of the first capacitor; the second terminal of the fourth resistor is respectively connected to the second terminal of the first capacitor and the output end of the operational amplifier; The first terminal of the second capacitor is grounded; the second terminal of the second capacitor is connected to the first terminal of the fifth resistor; the second terminal of the fifth resistor is connected to the inverting input terminal of the operational amplifier; The first terminal of the sixth resistor is connected to the terminal corresponding to the load terminal voltage; the second terminal of the sixth resistor is connected to the positive input terminal of the operational amplifier; The output terminal of the operational amplifier is also connected to the first terminal of the seventh resistor; the second terminal of the seventh resistor is connected to the positive input terminal of the comparator; the reverse input terminal of the comparator is connected to the reference voltage terminal; the output terminal of the comparator is respectively connected to the second terminal of the eighth resistor and the set terminal of the SR latch; the first terminal of the eighth resistor is connected to the DC voltage source; The output terminal of the SR latch is connected to the execution circuit.

3. The DC SSPC capacitive load and short circuit fault distinguishing circuit according to claim 1, characterized in that: The feedback circuit specifically includes: a current feedback circuit and a load voltage feedback circuit; The current feedback circuit is respectively connected to the sampling resistor, the current limiting control circuit and the current limiting judgment circuit; The load voltage feedback circuit is respectively connected to the load, the current limiting judgment circuit and the load distinguishing circuit; The current feedback circuit is used to obtain a current feedback signal corresponding to the sampling resistor; The load voltage feedback circuit is used to obtain the load terminal voltage.

4. The DC SSPC capacitive load and short circuit fault distinguishing circuit according to claim 1, characterized in that: The execution circuit includes: a short circuit protection circuit, a driving amplifier circuit and a main power circuit; The short-circuit protection circuit is connected to the load distinguishing circuit; the driving amplifier circuit is connected to the short-circuit protection circuit; the main power circuit is connected to the driving amplifier circuit; The short-circuit protection circuit is used to perform circuit protection processing according to the short-circuit signal; The driving amplifier circuit is used for: After power amplification processing is performed according to the short-circuit signal, the main power circuit is controlled to be turned off for fault protection, or the main power circuit is controlled to perform load charging processing; Power amplification processing is performed according to the control voltage, and the main power circuit is controlled to perform execution processing of current limiting action.

5. The DC SSPC capacitive load and short circuit fault distinguishing circuit according to claim 1, characterized in that: When the result of the current limiting judgment circuit is a non-current limiting state, the first current limiting state signal is a low level and the second current limiting state signal is a high level; the low level means that the voltage value is less than the set threshold; the high level means that the voltage value is greater than the set threshold; When the result of the current limiting judgment circuit is the current limiting state, the first current limiting state signal is a high level and the second current limiting state signal is a low level.

6. A method for distinguishing capacitive load and short circuit fault of a DC SSPC, characterized in that: The DC SSPC capacitive load and short-circuit fault distinguishing method is implemented by using the DC SSPC capacitive load and short-circuit fault distinguishing circuit described in any one of claims 1 to 5; The method for distinguishing between a DC SSPC capacitive load and a short circuit fault includes: Acquire feedback signals; the feedback signals include: load terminal voltage and current feedback signals; Determine whether to enter the current limiting state according to the feedback signal, and output a current limiting state signal; the current limiting state signal includes: a first current limiting state signal and a second current limiting state signal; outputting a control voltage according to the first current limiting state signal and the current feedback signal; Distinguishing between capacitive load and short-circuit fault according to the second current limiting state signal and the load terminal voltage, and outputting a short-circuit signal; performing a current limiting action according to the control voltage; Fault protection or load charging processing is performed according to the short-circuit signal.

7. The method for distinguishing between capacitive load and short circuit fault of DC SSPC according to claim 6, characterized in that: Determining whether to enter the current limiting state according to the feedback signal and outputting the current limiting state signal specifically includes: Compare the feedback signal with a set signal threshold to obtain a comparison result; Determine whether to enter the current limiting state according to the comparison result, and obtain a determination result; If the judgment result is yes, the output first current limiting state signal is a high level, and the second current limiting state signal is a low level; wherein the low level means that the voltage value is less than the set threshold value; and the high level means that the voltage value is greater than the set threshold value; If the judgment result is no, the first current limiting state signal is output as a low level and the second current limiting state signal is output as a high level.

8. The method for distinguishing between capacitive load and short circuit fault of DC SSPC according to claim 7, characterized in that: Distinguishing between a capacitive load and a short-circuit fault according to the second current limiting state signal and the load terminal voltage, and outputting a short-circuit signal, specifically includes: Determining a characteristic quantity according to the load terminal voltage; Comparing the characteristic value with a set reference voltage to distinguish between a capacitive load and a short circuit fault; When the distinction result is a short-circuit fault, a short-circuit signal is output according to the second current limiting state signal. At this time, the short-circuit signal is set to a high level; When the distinction result is a capacitive load, a short-circuit signal is output according to the second current limiting state signal. At this time, the short-circuit signal remains at a low level.

9. The method for distinguishing between capacitive load and short circuit fault of DC SSPC according to claim 8, characterized in that: Determining a characteristic quantity according to the load terminal voltage specifically includes: A construction based on the sum of proportion and differential is performed according to the load terminal voltage to obtain a characteristic quantity.

10. The method for distinguishing between capacitive load and short circuit fault of DC SSPC according to claim 9, characterized in that: The expression of the characteristic quantity is: Among them, V te is the characteristic quantity; k V k is the voltage proportionality factor in the load-differentiating circuit; VFB is the feedback coefficient in the load voltage feedback circuit; V load is the load terminal voltage; k dV is the voltage differential coefficient in the load differentiation circuit; t is the time.

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