Capacitor high voltage resistance detection response protection circuit and method

Abstract

The application discloses a capacitor high-voltage resistance detection response protection circuit and method, and relates to the technical field of capacitor detection. The circuit comprises a main control module, a voltage generation module connected with the main control module, a first current limiting module connected with the voltage generation module, a second current limiting module with an input end connected with an output end of the first current limiting module, an output end connected with one end of a capacitor to be detected, and the other end of the capacitor to be detected connected with an input end of the voltage generation module, a current limiting threshold module connected with the main control module, a drive feedback module with an input end connected with an output end of the current limiting threshold module and an output end connected with a controlled end of the second current limiting module, a switch module with an input end connected with the main control module and an output end connected with the drive feedback module, a constant voltage power supply module connected with the first current limiting module, and a short circuit protection module with an input end connected with the main control module and the drive feedback module and an output end connected with the second current limiting module. The circuit can improve the voltage resistance and perform short circuit protection.

Description

Technical Field

[0001] This invention relates to the field of capacitor testing technology, and in particular to a capacitor high voltage withstand test response protection circuit and method. Background Technology

[0002] The new energy vehicle market is currently experiencing explosive growth, and its power supply platform has also extended from 400V to 2000V or even higher. This requires the voltage platforms of corresponding battery, power distribution, and power supply products to match, resulting in a continuous increase in demand for high-voltage MLCC (Multilayer Ceramic Capacitor) capacitors, with very large production volumes.

[0003] In the field of high withstand voltage testing of MLCC capacitors, the 2000V high voltage power supply current limiting module is the last line of defense for the external output of the 2000V high voltage power supply. It controls whether the output is possible and the magnitude of the output current. It needs to withstand high withstand voltages of over 2000V while also withstanding the high heat generated by the high voltage drop, in order to avoid a series of safety hazards such as MLCC capacitor breakdown, short circuit, and fire, which could lead to losses.

[0004] Existing technical solutions typically use a single MOSFET to design current limiting modules. However, the highest withstand voltage of most commercially available MOSFETs is only 1500V. Due to the voltage withstand capability of MOSFETs, they cannot meet the requirements for long-term operation under 2000V high voltage. Moreover, when the MLCC capacitor is short-circuited during testing, it can easily lead to a series of safety hazards such as fire.

[0005] Furthermore, the current market supply of 2000V high-voltage power supplies is extremely scarce, and those with single output channels are expensive. The existing technical solution for the 2000V high-voltage withstand test station of the high-speed multi-channel sorting and testing machine for MLCC capacitors involves installing one 2000V high-voltage power supply for each track. For example, for 8-channel measurement, this requires 8 2000V high-voltage power supplies. This drastically increases the number of 2000V high-voltage power supplies needed for the high-speed multi-channel sorting and testing machine, leading to an increase in the size and number of components. Moreover, the 2000V high-voltage power supply is expensive, the control interfaces are numerous, the process is complex, and the components are plentiful. This makes large-scale, mass production difficult, unable to meet the needs of various customers, and hinders widespread application. Summary of the Invention

[0006] This invention aims to at least solve one of the technical problems existing in the prior art. To this end, this invention proposes a capacitor high voltage withstand detection response protection circuit and method, which can improve the withstand voltage capability of the current limiting module and provide short-circuit protection for the circuit.

[0007] In a first aspect, a capacitor high-voltage withstand detection and response protection circuit according to an embodiment of the present invention includes:

[0008] Main control module;

[0009] A voltage generating module is electrically connected to the main control module, and the voltage generating module is used to provide detection voltage and detection current;

[0010] The first current limiting module has its input terminal electrically connected to the output terminal of the voltage generating module;

[0011] The second current limiting module has its input terminal electrically connected to the output terminal of the first current limiting module, its output terminal electrically connected to one end of the capacitor under test, and the other end of the capacitor under test electrically connected to the input terminal of the voltage generating module.

[0012] A current limiting threshold module, the input terminal of which is electrically connected to the main control module, is used to set the limiting threshold of the detected current;

[0013] The drive feedback module has its input terminal electrically connected to the output terminal of the current limiting threshold module and its output terminal electrically connected to the controlled terminal of the second current limiting module. The drive feedback module is used to drive the second current limiting module and also to provide feedback on the detected current.

[0014] A switching module, wherein the input terminal of the switching module is electrically connected to the main control module, and the output terminal of the switching module is electrically connected to the input terminal of the drive feedback module, and the switching module is used to control the on and off of the first current limiting module and the second current limiting module;

[0015] A constant voltage power supply module, wherein the output terminal of the constant voltage power supply module is electrically connected to the controlled terminal of the first current limiting module, and is used to provide a constant driving voltage to the first current limiting module; the constant voltage power supply module is also electrically connected to the main control module.

[0016] A short-circuit protection module is provided, wherein the input terminal of the short-circuit protection module is electrically connected to the main control module and the drive feedback module, and the output terminal of the short-circuit protection module is electrically connected to the second current limiting module. The short-circuit protection module is used to shut down the second current limiting module and the first current limiting module when a short circuit occurs in the capacitor under test.

[0017] According to some embodiments of the present invention, a reverse isolation module is further provided between the constant voltage power supply module and the first current limiting module, the reverse isolation module comprising:

[0018] A plurality of diodes are connected in series. The anode of the first diode is electrically connected to the output terminal of the constant voltage power supply module, and the cathode of the last diode is electrically connected to the controlled terminal of the first current limiting module through a first resistor.

[0019] According to some embodiments of the present invention, the first current limiting module includes:

[0020] The first regulating tube has its first end electrically connected to the output terminal of the voltage generating module, and its controlled end is electrically connected to the first resistor through the second resistor.

[0021] The first Zener diode has its anode electrically connected to the input terminal of the second current limiting module, and its cathode electrically connected to the controlled terminal of the first regulating transistor.

[0022] The third resistor has one end electrically connected to the second end of the first regulating tube, and the other end electrically connected to the input end of the second current limiting module.

[0023] The second Zener diode has its anode electrically connected to the input terminal of the second current limiting module, and its cathode electrically connected to the second terminal of the first regulating tube.

[0024] According to some embodiments of the present invention, the second current limiting module includes:

[0025] The second regulating tube has its first end electrically connected to the output end of the first current limiting module, and its controlled end electrically connected to the output end of the drive feedback module through a fourth resistor.

[0026] The third Zener diode has its anode electrically connected to one end of the capacitor under test, and its cathode electrically connected to the controlled end of the second regulating diode.

[0027] The fifth resistor has one end electrically connected to the second end of the second regulating tube, and the other end electrically connected to one end of the capacitor to be tested.

[0028] The fourth Zener diode has its anode electrically connected to one end of the capacitor under test, and its cathode electrically connected to the second end of the second regulating diode.

[0029] According to some embodiments of the present invention, the current limiting threshold module includes:

[0030] The first operational amplifier has its non-inverting input terminal electrically connected to the main control module via a sixth resistor. The non-inverting input terminal of the first operational amplifier is also grounded via a first capacitor. The positive power supply terminal of the first operational amplifier is connected to a first positive voltage, and the negative power supply terminal of the first operational amplifier is connected to a first negative voltage.

[0031] The seventh resistor has one end grounded and the other end electrically connected to the inverting input terminal of the first operational amplifier.

[0032] The eighth resistor has one end electrically connected to the other end of the seventh resistor, and the other end of the eighth resistor is electrically connected to the output terminal of the first operational amplifier.

[0033] The ninth resistor has one end electrically connected to the other end of the eighth resistor, and the other end of the ninth resistor is electrically connected to the input terminal of the drive feedback module.

[0034] According to some embodiments of the present invention, the drive feedback module includes:

[0035] The second operational amplifier has its non-inverting input terminal electrically connected to the output terminal of the current limiting threshold module and the output terminal of the switching module, and its output terminal electrically connected to the controlled terminal of the second current limiting module. The positive power supply terminal of the second operational amplifier is connected to a first positive voltage, and the negative power supply terminal of the second operational amplifier is connected to a first negative voltage.

[0036] The tenth resistor has one end electrically connected to the inverting input terminal of the second operational amplifier, and the other end electrically connected to the second current limiting module and the short-circuit protection module.

[0037] According to some embodiments of the present invention, the switching module includes:

[0038] The third operational amplifier has its non-inverting input terminal electrically connected to the main control module via an eleventh resistor, its inverting input terminal connected to a reference voltage, its positive power supply terminal connected to a second positive voltage, its negative power supply terminal connected to a first negative voltage, and its output terminal electrically connected to the input terminal of the drive feedback module via a twelfth resistor.

[0039] According to some embodiments of the present invention, the short-circuit protection module includes:

[0040] The short-circuit threshold adjustment unit includes a thirteenth resistor, a fourteenth resistor, a fifteenth resistor, a sixteenth resistor, a second capacitor, and a fourth operational amplifier. The non-inverting input terminal of the fourth operational amplifier is electrically connected to the main control module through the thirteenth resistor. The non-inverting input terminal of the fourth operational amplifier is also grounded through the second capacitor. One end of the fourteenth resistor is grounded, and the other end of the fourteenth resistor is electrically connected to the inverting input terminal of the fourth operational amplifier and one end of the fifteenth resistor. The other end of the fifteenth resistor is electrically connected to the output terminal of the fourth operational amplifier. One end of the sixteenth resistor is electrically connected to the output terminal of the fourth operational amplifier.

[0041] The threshold window comparison unit includes a fifth operational amplifier, a seventeenth resistor, and an eighteenth resistor. The non-inverting input of the fifth operational amplifier is electrically connected to the other end of the sixteenth resistor. The inverting input of the fifth operational amplifier is electrically connected to the drive feedback module through the seventeenth resistor. The positive power supply terminal of the fifth operational amplifier is connected to a second positive voltage, and the negative power supply terminal of the fifth operational amplifier is grounded. One end of the eighteenth resistor is connected to the second positive voltage, and the other end of the eighteenth resistor is electrically connected to the output terminal of the fifth operational amplifier.

[0042] The accelerated shutdown unit includes an inverter, a switching transistor, and a nineteenth resistor. The input terminal of the inverter is electrically connected to the output terminal of the fifth operational amplifier, and the output terminal of the inverter is electrically connected to the controlled terminal of the switching transistor. The first terminal of the switching transistor is electrically connected to the controlled terminal of the second current limiting module through the nineteenth resistor, and the second terminal of the switching transistor is grounded.

[0043] The twentieth resistor has one end electrically connected to the main control module and the other end electrically connected to the output terminal of the fifth operational amplifier.

[0044] According to some embodiments of the present invention, a voltage equalization protection module is further included, which is electrically connected to the first current limiting module and the second current limiting module, and is used to provide voltage equalization protection for the first current limiting module and the second current limiting module.

[0045] In a second aspect, according to an embodiment of the present invention, a capacitor high-voltage withstand detection and response protection method, based on the capacitor high-voltage withstand detection and response protection circuit as described in the first aspect embodiment, the method includes:

[0046] The main control module sets the current limiting threshold module and the switch module, so that the drive feedback module controls the second current limiting module to be in the conducting state.

[0047] The constant voltage power supply module is configured via the main control module to enable the first current limiting module to be in a conducting state.

[0048] A detection voltage and a detection current are generated by a voltage generation module, and the detection voltage and the detection current are used to detect the capacitor under test through the first current limiting module and the second current limiting module.

[0049] When the capacitor under test is short-circuited, the first current limiting module and the second current limiting module are shut down by the short-circuit protection module.

[0050] The capacitor high voltage withstand detection response protection circuit and method according to embodiments of the present invention have at least the following beneficial effects: when the capacitor under test is short-circuited, the first current limiting module and the second current limiting module will disconnect, so that the voltage generating module cannot provide current to the capacitor under test. This can be used to prevent the internal circuit of the voltage generating module from burning out when the capacitor under test is abnormally short-circuited or broken down, thereby improving the safety of the circuit. At the same time, the first current limiting module and the second current limiting module can distribute the detection voltage provided by the voltage generating module, reducing the voltage that each module needs to withstand, thereby improving the voltage withstand capability of the circuit.

[0051] Additional aspects and advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. Attached Figure Description

[0052] The above and / or additional aspects and advantages of the present invention will become apparent and readily understood from the description of the embodiments taken in conjunction with the following drawings, in which:

[0053] Figure 1 This is a schematic diagram of a capacitor high voltage withstand detection and response protection circuit according to an embodiment of the present invention.

[0054] Figure 2 This is a circuit diagram of the capacitor high voltage withstand detection and response protection circuit according to an embodiment of the present invention;

[0055] Figure 3 This is a flowchart illustrating the steps of the capacitor high voltage withstand detection and response protection method according to an embodiment of the present invention. Detailed Implementation

[0056] The embodiments of the present invention are described in detail below. Examples of these embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain this application, and should not be construed as limiting this application. The step numbers in the following embodiments are set only for ease of explanation, and there is no limitation on the order between the steps. The execution order of each step in the embodiments can be adaptively adjusted according to the understanding of those skilled in the art.

[0057] In the description of this invention, it should be understood that the orientation descriptions, such as up, down, front, back, left, right, etc., are based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limiting this invention.

[0058] The terms "first," "second," "third," and "fourth," etc., used in the specification, claims, and accompanying drawings of this invention are used to distinguish different objects, not to describe a specific order. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion. For example, a process, method, system, product, or apparatus that includes a series of steps or units is not limited to the listed steps or units, but may optionally include steps or units not listed, or may optionally include other steps or units inherent to these processes, methods, products, or apparatuses.

[0059] In this invention, the reference to "embodiment" means that a specific feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of the invention. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment mutually exclusive with other embodiments. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.

[0060] The capacitor high voltage withstand detection response protection circuit and method of the present invention will be described in detail below with reference to the accompanying drawings.

[0061] On one hand, embodiments of the present invention propose a capacitor high voltage withstand detection and response protection circuit, such as... Figure 1As shown, the circuit includes a main control module 100, a voltage generation module 200, a first current limiting module 300, a second current limiting module 400, a current limiting threshold module 500, a drive feedback module 600, a switching module 700, a constant voltage power supply module 800, and a short-circuit protection module 900. The voltage generation module 200 is electrically connected to the main control module 100 and is used to provide the detection voltage and detection current. The input terminal of the first current limiting module 300 is electrically connected to the output terminal of the voltage generation module 200. The output terminal of the first current limiting module 300 is electrically connected to the input terminal of the second current limiting module 400. The output terminal of the second current limiting module 400 is electrically connected to one end of the capacitor C0 under test, and the other end of the capacitor C0 under test is electrically connected to the input terminal of the voltage generating module 200. The input terminal of the current limiting threshold module 500 is electrically connected to the main control module 100. The current limiting threshold module 500 is used to set the limiting threshold of the detection current. The output terminal of the current limiting threshold module 500 is electrically connected to the input terminal of the drive feedback module 600. The output terminal of the feedback module 600 is electrically connected to the controlled terminal of the second current limiting module 400. The drive feedback module 600 is used to drive the second current limiting module 400 and also to provide feedback of the detected current to the short-circuit protection module 900. The input terminal of the switch module 700 is electrically connected to the main control module 100, and the output terminal of the switch module 700 is electrically connected to the input terminal of the drive feedback module 600. The switch module 700 is used to control the on and off states of the first current limiting module 300 and the second current limiting module 400. The constant voltage power supply module 800... The output terminal is electrically connected to the controlled terminal of the first current limiting module 300 to provide a constant driving voltage for the first current limiting module 300. The constant voltage power supply module 800 is also electrically connected to the main control module 100. The input terminal of the short circuit protection module 900 is electrically connected to the main control module 100 and the drive feedback module 600. The output terminal of the short circuit protection module 900 is electrically connected to the second current limiting module 400. The short circuit protection module 900 is used to turn off the second current limiting module 400 and the first current limiting module 300 when a short circuit occurs in the capacitor under test.

[0062] Specifically, the main control module 100 can be implemented using a microcontroller (MCU), PLC, FPGA, etc., and is responsible for controlling the entire circuit's operation. The main control module 100 and the voltage generating module 200 can be connected via a communication interface isolation module 1200. The communication interface isolation module 1200 can use devices such as optocouplers to electrically isolate the main control module 100 and the voltage generating module 200, ensuring safe circuit operation. The voltage generating module 200 provides the precise detection voltage and current required for detection. The first current limiting module 300 and the second current limiting module 400 prevent damage to the internal circuitry of the voltage generating module 200 in case of abnormal short circuit or breakdown of the capacitor C0 under test, thus improving circuit safety. Simultaneously, the first current limiting module 300 and the second current limiting module 400 can distribute the detection voltage provided by the voltage generating module 200, reducing the voltage that each module needs to withstand, thereby improving the circuit's withstand voltage. The current limiting threshold module 500 is used to set a limit threshold for the detected current, so that when the detected current of the capacitor C0 under test exceeds the limit threshold, the first current limiting module 300 and the second current limiting module 400 are turned off, thus protecting the circuit and the capacitor C0 under test. The drive feedback module 600 drives the second current limiting module 400. When the circuit is working normally, the drive feedback module 600 drives the second current limiting module 400 to conduct; when a short circuit or other abnormal condition occurs, the drive feedback module 600 drives the second current limiting module 400 to turn off. The drive feedback module 600 also feeds back the detected current to the short-circuit protection module 900, allowing the short-circuit protection module 900 to determine whether a short circuit has occurred and, if a short circuit occurs, to turn off the first current limiting module 300 and the second current limiting module 400, thus achieving short-circuit protection for the circuit. The switch module 700 prepares for the turning on and off of the first current limiting module 300 and the second current limiting module 400, facilitating the control of their on / off states. The constant voltage power supply module 800 is used to output a constant driving voltage to the first current limiting module 300, so that the first current limiting module 300 can be turned on.

[0063] Furthermore, such as Figure 1 and Figure 2 As shown, in some embodiments of this application, a reverse isolation module 1000 is further provided between the constant voltage power supply module 800 and the first current limiting module 300. The reverse isolation module 1000 includes: a plurality of diodes connected in series, the anode of the first diode being electrically connected to the output terminal of the constant voltage power supply module 800, and the cathode of the last diode being electrically connected to the controlled terminal of the first current limiting module 300 through a first resistor R11. Figure 2As shown, in this example, the reverse isolation module 1000 includes diodes D1 and D2 connected in series. The anode of diode D1 is electrically connected to the output terminal of the constant voltage power supply module 800, the cathode of diode D1 is electrically connected to the anode of diode D2, the cathode of diode D2 is electrically connected to one end of the first resistor R11, and the other end of the first resistor R11 is electrically connected to the controlled terminal of the first current limiting module 300. By setting the reverse isolation module 1000 between the constant voltage power supply module 800 and the first current limiting module 300, a series of risks such as high voltage feedback from the first current limiting module 300 to the constant voltage power supply module 800, thereby preventing it from burning out or being damaged, are prevented.

[0064] Furthermore, such as Figure 2 As shown, in some embodiments of this application, the first current limiting module 300 includes a first regulating transistor Q2, a first Zener diode D3, a second resistor R16, a third resistor R19, and a second Zener diode D5. The first terminal of the first regulating transistor Q2 is electrically connected to the output terminal of the voltage generating module 200. The controlled terminal of the first regulating transistor Q2 is electrically connected to the first resistor R11 through the second resistor R16. The anode of the first Zener diode D3 is electrically connected to the input terminal of the second current limiting module 400, and the cathode of the first Zener diode D3 is electrically connected to the controlled terminal of the first regulating transistor Q2. One end of the third resistor R19 is electrically connected to the second terminal of the first regulating transistor Q2, and the other end of the third resistor R19 is electrically connected to the input terminal of the second current limiting module 400. The anode of the second Zener diode D5 is electrically connected to the input terminal of the second current limiting module 400, and the cathode of the second Zener diode D5 is electrically connected to the second terminal of the first regulating transistor Q2. It should be noted that the first regulating transistor Q2 can be a commonly used regulating device such as a MOSFET, transistor, insulated gate bipolar transistor (IGBT), or gate turn-off thyristor (GTO). In this example, the first regulating transistor Q2 is an enhancement-mode N-channel MOSFET. The drain of the first regulating transistor Q2 is electrically connected to the output terminal of the voltage generation module 200. The gate of the first regulating transistor Q2 is electrically connected to the first resistor R11 through the second resistor R16. The gate of the first regulating transistor Q2 is also electrically connected to the cathode of the first Zener diode D3. The source of the first regulating transistor Q2 is electrically connected to one end of the third resistor R19 and the cathode of the second Zener diode D5. The constant voltage power supply module 800 can provide a driving voltage for the gate of the first regulating transistor Q2.

[0065] Furthermore, such as Figure 2As shown, in some embodiments of this application, the second current limiting module 400 includes a second regulating transistor Q3, a third Zener diode D4, a fourth resistor R18, a fifth resistor R20, and a fourth Zener diode D6. The first end of the second regulating transistor Q3 is electrically connected to the output end of the first current limiting module 300, and the controlled end of the second regulating transistor Q3 is electrically connected to the output end of the drive feedback module 600 through the fourth resistor R18. The anode of the third Zener diode D4 is electrically connected to one end of the capacitor C0 under test, and the cathode of the third Zener diode D4 is electrically connected to the controlled end of the second regulating transistor Q3. One end of the fifth resistor R20 is electrically connected to the second end of the second regulating transistor Q3, and the other end of the fifth resistor R20 is electrically connected to one end of the capacitor C0 under test. The anode of the fourth Zener diode D6 is electrically connected to one end of the capacitor C0 under test, and the cathode of the fourth Zener diode D6 is electrically connected to the second end of the second regulating transistor Q3. It should be noted that the second regulating transistor Q3 can be a commonly used regulating device such as a MOSFET, transistor, insulated gate bipolar transistor (IGBT), or gate turn-off thyristor (GTO). In this example, the second regulating transistor Q3 is an enhancement-mode N-channel MOSFET. The drain of the second regulating transistor Q3 is electrically connected to the output terminal of the first current limiting module 300. The gate of the second regulating transistor Q3 is electrically connected to the output terminal of the drive feedback module 600 through the fourth resistor R18. The gate of the second regulating transistor Q3 is also electrically connected to the cathode of the third Zener diode D4. The source of the second regulating transistor Q3 is electrically connected to one end of the fifth resistor R20 and the cathode of the fourth Zener diode D6.

[0066] Furthermore, such as Figure 2 As shown, in some embodiments of this application, the current limiting threshold module 500 includes a first operational amplifier U1A, a sixth resistor R2, a seventh resistor R1, an eighth resistor R6, a ninth resistor R9, and a first capacitor C1. The non-inverting input terminal of the first operational amplifier U1A is electrically connected to the main control module 100 through the sixth resistor R2. The non-inverting input terminal of the first operational amplifier U1A is also grounded (GND2) through the first capacitor C1. The positive power supply terminal (pin 4) of the first operational amplifier U1A is connected to a first positive voltage (+9V). The negative power supply terminal (pin 8) of amplifier U1A is connected to the first negative voltage (-9V); one end of the seventh resistor R1 is grounded (GND2), and the other end of the seventh resistor R1 is electrically connected to the inverting input terminal of the first operational amplifier U1A; one end of the eighth resistor R6 is electrically connected to the other end of the seventh resistor R1, and the other end of the eighth resistor R6 is electrically connected to the output terminal of the first operational amplifier U1A; one end of the ninth resistor R9 is electrically connected to the other end of the eighth resistor R6, and the other end of the ninth resistor R9 is electrically connected to the input terminal of the drive feedback module 600.

[0067] Furthermore, such as Figure 2As shown, in some embodiments of this application, the drive feedback module 600 includes a second operational amplifier U4 and a tenth resistor R12. The non-inverting input terminal of the second operational amplifier U4 is electrically connected to the output terminal of the current limiting threshold module 500 (i.e., the other end of the ninth resistor R9) and the output terminal of the switching module 700. The output terminal of the second operational amplifier U4 is electrically connected to the controlled terminal of the second current limiting module 400 (i.e., electrically connected to the gate of the second regulating transistor Q3 through the fourth resistor R18). The positive power supply terminal (pin 5) of the second operational amplifier U4 is connected to a first positive voltage (+9V), and the negative power supply terminal (pin 2) of the second operational amplifier U4 is connected to a first negative voltage (-9V). One end of the tenth resistor R12 is electrically connected to the inverting input terminal of the second operational amplifier U4, and the other end of the tenth resistor R12 is electrically connected to the second current limiting module 400 (i.e., the source of the second regulating transistor Q3) and the short-circuit protection module 900.

[0068] Furthermore, such as Figure 2 As shown, in some embodiments of this application, the switch module 700 includes a third operational amplifier U2, an eleventh resistor R3, and a twelfth resistor R10. The non-inverting input of the third operational amplifier U2 is electrically connected to the main control module 100 through the eleventh resistor R3. The inverting input of the third operational amplifier U2 is connected to a reference voltage (VREF_2.5V). The positive power supply terminal (pin 5) of the third operational amplifier U2 is connected to a second positive voltage (+5V). The negative power supply terminal (pin 2) of the third operational amplifier U2 is connected to a first negative voltage (-9V). The output terminal of the third operational amplifier U2 is electrically connected to the input terminal of the drive feedback module 600 (i.e., the non-inverting input terminal of the second operational amplifier U4) through the twelfth resistor R10.

[0069] Furthermore, such as Figure 1 and Figure 2As shown, in some embodiments of this application, the short-circuit protection module 900 includes a short-circuit threshold adjustment unit 910, a threshold window comparison unit 920, an accelerated shutdown unit 930, and a twentieth resistor R14. The short-circuit threshold adjustment unit 910 includes a thirteenth resistor R5, a fourteenth resistor R4, a fifteenth resistor R7, a sixteenth resistor R8, a second capacitor C2, and a fourth operational amplifier U1B. The non-inverting input terminal of the fourth operational amplifier U1B is electrically connected to the main control module 100 through the thirteenth resistor R5. The non-inverting input terminal of the fourth operational amplifier U1B is also grounded (GND2) through the second capacitor C2. One end of the fourteenth resistor R4 is grounded (GND2), and the other end of the fourteenth resistor R4 is electrically connected to the inverting input terminal of the fourth operational amplifier U1B and one end of the fifteenth resistor R7. The other end of the fifteenth resistor R7 is electrically connected to the output terminal of the fourth operational amplifier U1B, and one end of the sixteenth resistor R8 is electrically connected to the output terminal of the fourth operational amplifier U1B. The threshold window comparison unit 920 includes a fifth operational amplifier U5, a seventeenth resistor R13, and an eighteenth resistor R15. The non-inverting input of the fifth operational amplifier U5 is electrically connected to the other end of the sixteenth resistor R8. The inverting input of the fifth operational amplifier U5 is electrically connected to the drive feedback module 600 (i.e., the other end of the tenth resistor R12) through the seventeenth resistor R13. The positive power supply terminal (pin 5) of the fifth operational amplifier U5 is connected to a second positive voltage (+5V), and the negative power supply terminal (pin 2) of the fifth operational amplifier U5 is grounded (GND2). One end of the eighteenth resistor R15 is connected to the second positive voltage (+5V), and the other end of the eighteenth resistor R15 is electrically connected to the output terminal of the fifth operational amplifier U5. The accelerated shutdown unit 930 includes an inverter U3, a switching transistor Q1, and a nineteenth resistor R17. The input terminal of the inverter U3 is electrically connected to the output terminal of the fifth operational amplifier U5, and the output terminal of the inverter U3 is electrically connected to the controlled terminal of the switching transistor Q1. The first terminal of the switching transistor Q1 is electrically connected to the controlled terminal of the second current limiting module 400 (i.e., the gate of the second regulating transistor Q3) through the nineteenth resistor R17, and the second terminal of the switching transistor Q1 is grounded (GND2). One end of the twentieth resistor R14 is electrically connected to the main control module 100, and the other end of the twentieth resistor R14 is electrically connected to the output terminal of the fifth operational amplifier U5. It should be noted that the switching transistor Q1 can be a common switching device such as a MOSFET, a transistor, or a relay. In this example, the switching transistor Q1 is an enhancement-mode N-channel MOSFET. The drain of the switching transistor Q1 is electrically connected to the controlled terminal of the second current limiting module 400 (i.e., the gate of the second regulating transistor Q3) through the nineteenth resistor R17. The gate of the switching transistor Q1 is electrically connected to the output terminal of the inverter U3. The drain of the switching transistor Q1 is grounded (GND2).

[0070] Furthermore, such as Figure 1 and Figure 2As shown, in some embodiments of this application, the circuit further includes a voltage equalization protection module 1100, which is electrically connected to the first current limiting module 300 and the second current limiting module 400, and is used to provide voltage equalization protection for the first current limiting module 300 and the second current limiting module 400. Specifically, as shown... Figure 2 As shown, in this example, the equalizing protection module 1100 includes resistors R21, R22, R23, and R24, and capacitors C3, C4, C5, and C6. One end of resistor R21 is electrically connected to the output terminal (VCC1) of the voltage generating module 200, and the other end of resistor R21 is electrically connected to one end of resistor R22. The other end of resistor R22 is electrically connected to one end of resistor R23, and the other end of resistor R23 is electrically connected to one end of resistor R24. Resistor R24 ​​is electrically connected to the other end of the tenth resistor R12. One end of capacitor C3 is electrically connected to the output terminal (VCC1) of the voltage generating module 200, and the other end of capacitor C3 is electrically connected to the other end of resistor R21 and one end of capacitor C4. The other end of capacitor C4 is electrically connected to the other end of resistor R22 and one end of capacitor C5. The other end of capacitor C5 is electrically connected to the other end of resistor R23 and one end of capacitor C6. The other end of capacitor C6 is electrically connected to the other end of resistor R24. The equalization protection module 1100 is used to provide equalization protection for the first regulating tube Q2 and the second regulating tube Q3.

[0071] It should be noted that, in Figure 2 In the diagram, GND1 is the output reference point of the power supply voltage generation module 200, and GND2 is another reference point of the circuit, 0V.

[0072] In this application, the working principle of the current limiting threshold module 500 is as follows: The main control module 100 first sets the value of the threshold output port to DAC1. Since the input of the operational amplifier is high impedance, DAC1 = VCC13 (1); Since the "virtual short" principle of the operational amplifier is true, VCC13 = VCC12 (2); According to Kirchhoff's law (KCL), the following can be derived:

[0073] ;

[0074] From equations (1), (2) and (3), we get:

[0075] .

[0076] The working principle of the short-circuit threshold adjustment unit 910 is as follows: The main control module 100 sets the output value of the short-circuit threshold port to DAC2. Since the input terminal of the operational amplifier is high impedance, DAC2 = VCC18 (5); According to the "virtual short" principle of the operational amplifier, VCC18 = VCC17 (6); According to Kirchhoff's law (KCL), the following can be obtained:

[0077] ;

[0078] From equations (5), (6) and (7), we can obtain:

[0079] .

[0080] Therefore, before testing the capacitor C0, the values ​​of DAC1 and DAC2 need to be set by the main control module 100. At the same time, the output value VCC28 of the constant voltage power supply module 800 also needs to be set by the main control module 100 so that the first current limiting module 300 can be turned on normally.

[0081] The working principle of the entire circuit is as follows:

[0082] (a) The circuit is operating normally:

[0083] When the main control module 100 outputs a high level at the switch control port, i.e., ON / OFF=3.3V, the pull-up resistor at the output terminal of the third operational amplifier U2 is R9, so its output voltage is VCC15=VCC9=VCC11 (9); according to the high impedance principle of the input terminal of the operational amplifier, VCC10=VCC8 (10). Let the detection current be I, then VCC8=I×R20 (11). When VCC10 is less than VCC9, according to equations (9), (10) and (11), VCC10=I×R20<VCC9. At this time, the output voltage VCC6 of the second operational amplifier U4 is +9V. After the current limiting effect of the fourth resistor R18 and the protection effect of the third Zener diode D4, the voltage value of VCC7 is limited to a stable voltage, about 8V. The voltage between the gate and source of the second regulating transistor Q3 is much greater than the turn-on voltage of the second regulating transistor Q3, so the drain and source of the second regulating transistor Q3 are in a fully conducting state. The main control module 100 sets the constant voltage power supply module 800 to output VCC28 via the control port. This output passes through diodes D1 and D2 of the reverse isolation module 1000 and the first resistor R11 to VCC2. With the current limiting effect of the second resistor R16 and the protection of the first Zener diode D3, the voltage value of VCC3 is limited to a stable voltage of approximately 8V. Since the drain and source of the second regulating transistor Q3 are fully conducting, and the resistances of R19 and R20 are very small, the voltage of VCC4 is approximately GND2. At this time, the voltage between the gate and source of the first regulating transistor Q2 is much greater than the turn-on voltage of Q2, so the drain and source of Q2 are fully conducting. Therefore, both the first current limiting module 300 and the second current limiting module 400 are in a conducting state. The main control module 100 sets the voltage generator module 200 to output VCC1 through the communication interface. The detected current passes through Q2, R19, Q3 and R20 and reaches GND1, which is VOUT. The capacitor under test C0 is charged and tested. The current eventually returns to GND1 of the voltage generator module 200.

[0084] The above normal working process can be simply represented as follows:

[0085] Set the ON / OFF values ​​of DAC1, VCC28 → VCC9 is greater than VCC10 → VCC6 outputs +9V → VCC7 is approximately 8V → Q3 turns on → Q2 turns on → normal output VOUT.

[0086] (ii) Circuit output shutdown:

[0087] When the main control module 100 outputs a low level at the switch control port, i.e., ON / OFF=0V, the output voltage of the third operational amplifier U2 is -9V, i.e., VCC15=-9V; the DAC1 value is positive, and the output voltage of the current limiting threshold module 500 is affected by the DC power supply +9V, so the output voltage VCC11 is less than +9V; at the same time, the resistance of R9 is greater than the resistance of R10; from Kirchhoff's law (KCL) and equation (4), we can deduce:

[0088] ;

[0089] From the above equation (12), it can be seen that at this time, the voltage of VCC9 is less than GND2, the voltage value of the fourth pin of the second operational amplifier U4, VCC10, is greater than the voltage value of the third pin of the second operational amplifier U4, VCC9, and the output voltage of U4, VCC6, is -9V; at this time, VCC7, VCC6, and -9V are much less than the turn-on voltage of the second regulating transistor Q3, so the drain and source of the second regulating transistor Q3 are in the cut-off state. Since the drain and source of the second regulating transistor Q3 are in the cut-off state, the gate and source of the first regulating transistor Q2 cannot form a circuit, that is, the turn-on voltage of the first regulating transistor Q2 cannot be reached, so the drain and source of the first regulating transistor Q2 are in the completely cut-off state; thus, the first current limiting module 300 and the second current limiting module 400 are both in the disconnected state, and the voltage generating module 200 cannot output VOUT to the capacitor C0 under test.

[0090] The above process of turning off the output can be simply represented as follows:

[0091] When ON / OFF is low, VCC9 is less than VCC10, VCC6 outputs -9V, VCC7 is negative, Q3 is cut off, Q2 is cut off, and output VOUT is turned off.

[0092] (III) Short-circuit protection process:

[0093] When the main control module 100 sets the output voltage of the threshold output port to DAC1, VCC9 = 0.01V; when the main control module 100 sets the output voltage of the short-circuit threshold port to DAC2, VCC20 = 0.6V; the main control module 100 sets the constant voltage power supply module 800 output VCC28 = 9V, and the forward voltage drop of diodes D1 and D2 is 0.3V; the turn-on voltage of Q2 and Q3 is UT = 2.5V, and IDO is the ID (drain current) value of 400mA when uGS = 2UT, i.e., IDO = 400mA; the gate-source voltage of Q3 is represented by uGS1, the drain-source power supply by uDS1, and the gate-drain voltage by uGD1; the gate-source voltage of Q2 is represented by uGS2, the drain-source power supply by uDS2, and the gate-drain voltage by uGD2; according to the analytical formula of the output transfer characteristics of the enhancement-mode N-channel MOSFET:

[0094] ;

[0095] Under normal output operation, when the capacitor under test C0 is short-circuited, the detection current I increases to 10mA (reaching the user-set current limiting threshold, which is converted to voltage form as DAC1). The voltage on R20 is VCC8 = I × R20 = 10mA × 1Ω = 0.01V, so VCC10 = VCC8 = 0.01V. When the detection current I continues to increase, VCC10 also increases accordingly with VCC8. When VCC10 ≥ VCC9, the output VCC6 of the second operational amplifier U4 is in a floating state. When the current on R20 is limited to 10mA, according to the above formula (13), we can conclude that:

[0096] ;

[0097] VCC4-VCC5=I×R20=10mA×1Ω=0.01V. Let the voltage between VCC1 and GND2 be represented by VCC, then:

[0098] When VCC < VCC2×2 = (VCC28 - 0.3×2V)×2 = (9V - 0.3×2V)×2 = 16.8V, D1 and D2 are forward-biased, and the equalizing protection module does not respond. R21 = R22 = R23 = R24, and their resistance is tens or hundreds of megohms. At this time, VCC2 = VCC28 - 0.3×2V = 8.4V.

[0099] (1) When VCC < uDS1 + I × (R20 + R19) = uGS1 - UT + I × (R20 + R19) = 2.9V - 2.5V + 10mA × (1 + 1Ω) = 0.42V, uGS1 > UT, uDS1 < uGS1 - UT (uDS1 < 2.9V - 2.5V = 0.4V), the drain characteristic of Q3 enters the variable resistance region. There is a conductive channel between the drain and the source. When the detection current I flows through the conductive channel, a voltage drop occurs, making the voltage at each point on the channel different. At this time, VCC drops to the drain characteristic variable resistance region, R20 and R19, that is, VCC4 = VCC < 0.42V.

[0100] If D1 and D2 are forward conducting, then VCC2 = VCC28 - 0.3 × 2V = 9V - 0.3 × 2V = 8.4V; VCC2 is much larger than VCC, so the above assumption holds; at this time, uGS2 = VCC3 - VCC4 = VCC2 - VCC4 = 8.4V - 0.42V = 7.98V, uGS2 > UT, and uDS2 < uGS2 - UT. The drain characteristic of Q2 enters the variable resistance region, and the induced charge increases. The conductive channel between the drain and the source widens, and the drain and the source are completely connected, i.e., uDS2 = 0V;

[0101] (2) When VCC>uDS1+I×(R20+R19)=uGS1-UT+I×(R20+R19)=2.9V-2.5V+10mA×(1+1Ω)=0.42V, and VCC<VCC3-uGS2+uDS2=VCC2-uGS2+(uGS2-UT)=VCC2-UT=8.4V-2.5V=5.9V; uGS1>UT, uDS1>uGS1-UT (uDS1>2.9V-2.5V=0.4V), the drain characteristic of Q3 enters the constant current region (or saturation region). During this process, because the channel resistance of the pinch-off region is very large, when uDS1 gradually increases, the increased uDS1 almost all falls on the pinch-off region, while the voltage across the conductive channel hardly increases, that is, it remains basically unchanged, and the drain current ID remains unchanged.

[0102] From the analytical expression of the output transfer characteristic of Q2, we know that uGS2 = 2.9V. At this time, the drain and source voltages of VCC4, Q3, and Q2 are respectively:

[0103] VCC4=VCC3-uGS2=VCC2-uGS2=8.4V-2.9V=5.4V;

[0104] uDS1=VCC4-I×(R20+R19)=5.4V-10mA×(1+1Ω)=5.38V;

[0105] uDS2<VCC-VCC4=5.9V-5.4=0.4V;

[0106] At this point, the conditions uGS2 > UT and uDS2 < uGS2 - UT (uDS2 < 2.9V - 2.5V = 0.4V) are met. The drain characteristic of Q3 enters the variable resistance region. There is a conductive channel between the drain and the source. When the detection current I flows through the conductive channel, a voltage drop occurs, causing the voltage at different points on the channel to be different. At this time, the remaining voltage of VCC drops to the drain characteristic variable resistance region, that is, the drain and source voltage values ​​of Q2 are less than VCC - VCC4 = 5.9V - 5.4 = 0.4V.

[0107] (3) When VCC > VCC3 - uGS2 + uDS2 = VCC2 - uGS2 + (uGS2 - UT) = VCC2 - UT = 8.4V - 2.5V = 5.9V, and VCC < VCC2 × 2 = (VCC28 - 0.3 × 2V) × 2 = (9V - 0.3 × 2V) × 2 = 16.8V, uGS1 > UT, uDS1 > uGS1 - UT (uDS1 > 2.9V - 2.5V = 0.4V), the drain characteristic of Q3 enters the constant current region (or saturation region). During this process, because the channel resistance of the pinch-off region is very large, when uDS1 gradually increases, the increased uDS1 almost all falls on the pinch-off region, while the voltage across the conductive channel hardly increases, that is, it remains basically unchanged, and the drain current ID remains unchanged.

[0108] From the analytical expression of the output transfer characteristic of Q2, we know that uGS2 = 2.9V. At this time, the drain and source voltages of VCC4, Q3, and Q2 are respectively:

[0109] VCC4=VCC3-uGS2=VCC2-uGS2=8.4V-2.9V=5.4V;

[0110] uDS1=VCC4-I×(R20+R19)=5.4V-10mA×(1+1Ω)=5.38V;

[0111] uDS2<VCC-VCC4=16.8V-5.4=11.4V;

[0112] At this point, the conditions ugs2 > UT and uDS2 > uGS2 - UT (uDS2 > 2.9V - 2.5V = 0.4V) are met. The drain characteristic of Q2 enters the constant current region (or saturation region). During this process, due to the large channel resistance in the pinch-off region, when uDS2 gradually increases, almost all of the increased uDS2 falls on the pinch-off region, while the voltage across the conductive channel hardly increases, that is, it remains basically unchanged, and the drain current ID remains unchanged. At this time, the remaining voltage of VCC falls to the drain characteristic variable resistance region, and the drain and source voltage values ​​of Q3 are less than VCC - VCC4 = 16.8V - 5.4 = 11.4V.

[0113] When VCC > VCC2×2 = (VCC28 - 0.3×2V)×2 = (9V - 0.3×2V)×2 = 16.8V, D1 and D2 are cut off, and the equalizing protection module 1100 starts to respond. R21 = R22 = R23 = R24, and their electrical values ​​are tens or hundreds of megohms. At this time, VCC2 = VCC÷2 > 16.8V÷2 = 8.4V;

[0114] When uGS1 > UT and uDS1 > uGS1 - UT (uDS1 > 2.9V - 2.5V = 0.4V), the drain characteristic of Q3 enters the constant current region (or saturation region). During this process, because the channel resistance of the pinch-off region is very large, when uDS1 gradually increases, almost all of the increased uDS1 falls on the pinch-off region, while the voltage across the conductive channel hardly increases, that is, it remains basically unchanged, and the drain current ID remains unchanged.

[0115] From the analytical expression of the output transfer characteristic of Q2, we know that uGS2 = 2.9V. At this time, the drain and source voltages of VCC4, Q3, and Q2 are respectively:

[0116] VCC4=VCC3-uGS2=VCC2-uGS2=VCC÷2-2.9V;

[0117] uDS1=VCC4-I×(R20+R19)=VCC÷2-2.9V-10mA×(1+1Ω)=VCC÷2-2.88V;

[0118] uDS2=VCC-VCC4=16.8V-5.4=VCC÷2+2.9V;

[0119] At this point, the conditions uGS2 > UT and uDS2 > uGS2 - UT (uDS2 > 2.9V - 2.5V = 0.4V) are met. The drain characteristic of Q2 enters the constant current region (or saturation region). During this process, due to the large channel resistance in the pinch-off region, when uDS2 gradually increases, almost all of the increased uDS2 drops onto the pinch-off region, while the voltage across the conductive channel hardly increases, i.e., it remains basically unchanged, and the drain current ID remains unchanged. At this time, the remaining voltage of VCC drops into the drain characteristic variable resistance region, i.e., the drain and source voltage values ​​of Q3 are less than VCC - VCC4 = VCC ÷ 2 + 2.9V.

[0120] For example, if the voltage between VCC1 and GND2 is VCC = 2000V, then the drain and source voltages of VCC4, Q3, and Q2 are respectively:

[0121] VCC4=VCC3-uGS2=VCC2-uGS2=2000÷2-2.9V=997.1V;

[0122] uDS1=VCC4-I×(R20+R19)=VCC÷2-2.9V-10mA×(1+1Ω)=2000÷2-2.88V=997.12V;

[0123] uDS2=VCC-VCC4=16.8V-5.4=2000V÷2+2.9=1002.9V;

[0124] As can be seen from the above, under the current limiting protection state of Q2 and Q3 in series output, the voltage uDS1 between the drain and source of the two MOSFETs is approximately uDS2, which evenly distributes the VCC voltage; the series output of the enhancement-mode N-channel MOSFETs increases the output withstand voltage and solves the problem of the withstand voltage limitation of a single MOSFET.

[0125] For the short-circuit protection module 900, based on the high impedance principle of the operational amplifier input, VCC16 = VCC20, VCC19 = VCC8. From the above equation (8), we can derive:

[0126] ;

[0127] When the voltage of VCC19 is less than VCC20 (reflecting that the detection current is within the user-set short-circuit threshold range), the output voltage of the fifth operational amplifier U5 is VCC21 = +5V; at this time, the output voltage of pin 2 of inverter U3 is VCC22 = 0V (i.e., GND2), and the drain and source of Q1 are completely cut off; the voltage at point VCC7 is not affected by the accelerated shutdown unit 930; at this time, the main control module 100 receives the short-circuit impact alarm signal Over through R14, which is at a high level (i.e. +5), and the main control module 100 does not respond.

[0128] When the capacitor C0 under test is short-circuited by an impulse, a very large current flows through R20 instantaneously. This causes a sudden increase in the voltage VCC8 across R20, and VCC19 increases accordingly. When the voltage of VCC19 exceeds VCC20 (reflecting a very large detection current exceeding the user-set short-circuit threshold), the output voltage VCC21 of the fifth operational amplifier U5 becomes 0V (i.e., GND2). At this time, the output voltage of the inverter U3 is VCC22 = +5V, and the drain and source of Q1 are fully conducting. VCC7 is energized. The voltage is quickly pulled down to GND2 through the drain and source of R17 and Q1. The gate and source voltage of Q3 is 0V (i.e., GND2), which is much lower than the turn-on voltage of Q3. Therefore, the fast response of Q3 enters the cut-off state. Since Q3 enters the cut-off state, the gate and source loop of Q2 is also cut off by the fast response. It cannot form a loop, that is, it cannot reach the turn-on voltage of Q2. Therefore, the drain and source fast response of Q2 enters the cut-off state. The voltage generation module 200 cannot output VOUT to the capacitor under test C0, thus realizing the short-circuit protection of the circuit.

[0129] The short-circuit protection process can be simply represented as follows:

[0130] VCC8↑ or I↑→VCC19↑→VCC19 is greater than VCC20→VCC21↓→VCC22↑→Q1 turns on→VCC7↓→Q3 turns off→Q2 turns off→VCC8↓ or I↓→VCC19↓→VCC19 is less than VCC20→VCC21↑→VCC22↓→Q1 turns off→VCC7↑→Q3 turns on→Q2 turns on→VCC8↑ or I↑;

[0131] At this time, the main control module 100 receives the short-circuit impact alarm signal Over low level (i.e. GND2) through R14. The main control module 100 responds to the fully shut-off output function state and outputs a low level ON / OFF=0V at the switch control port. According to equation (12), at this time, the voltage of VCC9 is less than GND2, VCC10 is greater than VCC9, and the output voltage of the second operational amplifier U4 is VCC6=-9V. At this time, when the main control module 100 responds to the fully shut-off output function state, regardless of whether the voltage at point VCC7 continues to be pulled down to GND2 by the accelerated shutdown unit 930, Q2 and Q3 are both in the cut-off state, protecting the entire circuit.

[0132] The capacitor high voltage withstand test response protection circuit according to the embodiments of this application has the function of fast response protection against short circuit breakdown, thereby avoiding a series of safety hazards such as short circuit and fire of MLCC capacitors when the high-speed multi-channel sorting and testing machine tests MLCC capacitors at 2000V high withstand voltage, thus avoiding losses. The modular design of the circuit makes it easy to expand the output channels of the high voltage power supply, which can increase the output channels of the voltage generation module 200. The interface control is simple, the process is simple, the cost is reduced, and large-scale mass production can be achieved to meet the needs of various equipment and customers' various testing requirements, which is convenient for widespread use.

[0133] Secondly, based on the capacitor high-voltage withstand detection and response protection circuit described in the first aspect embodiment above, this application also proposes a capacitor high-voltage withstand detection and response protection method, such as... Figure 3 As shown, the method includes:

[0134] Step S100: The main control module 100 sets the current limiting threshold module 500 and the switch module 700 so that the drive feedback module 600 controls the second current limiting module 400 to be in the conducting state.

[0135] Step S200: Configure the constant voltage power supply module 800 through the main control module 100 to make the first current limiting module 300 in the conducting state;

[0136] Step S300: The voltage generation module 200 generates a detection voltage and a detection current, which are then passed through the first current limiting module 300 and the second current limiting module 400 to detect the capacitor under test.

[0137] Step S400: When a short circuit occurs in the capacitor under test, the first current limiting module 300 and the second current limiting module 400 are shut off by the short circuit protection module 900.

[0138] Specifically, when the circuit is working normally, the main control module 100 outputs a high level at the switch control port, i.e., ON / OFF=3.3V. The pull-up resistor at the output of the third operational amplifier U2 is R9, so its output voltage is VCC15=VCC9=VCC11 (9); according to the high impedance principle of the input terminal of the operational amplifier, VCC10=VCC8 (10). Let the detection current be I, then VCC8=I×R20 (11). When VCC10 is less than VCC9, from equations (9), (10) and (11), we can conclude that VCC10 = I × R20 < VCC9. At this time, the output voltage VCC6 of the second operational amplifier U4 is +9V. Under the current limiting effect of the fourth resistor R18 and the protection effect of the third Zener diode D4, the voltage value of VCC7 is limited to a stable voltage, about 8V. The voltage between the gate and source of the second regulating transistor Q3 is much greater than the turn-on voltage of the second regulating transistor Q3, so the drain and source of the second regulating transistor Q3 are in a fully conducting state. The main control module 100 sets the constant voltage power supply module 800 to output VCC28 through the control port. After passing through the diodes D1 and D2 of the reverse isolation module 1000 and the first resistor R11, it reaches VCC2. After the current limiting effect of the second resistor R16 and the protection effect of the first Zener diode D3, the voltage value of VCC3 is limited to a stable voltage, about 8V. Since the drain and source of the second regulating transistor Q3 are fully conducting, and the resistances of R19 and R20 are very small, the voltage of VCC4 is approximately GND2. At this time, the voltage between the gate and source of the first regulating transistor Q2 is much greater than the turn-on voltage of the first regulating transistor Q2, so the drain and source of the first regulating transistor Q2 are fully conducting. Therefore, both the first current limiting module 300 and the second current limiting module 400 are in the conducting state. The main control module 100 sets the voltage generation module 200 to output VCC1 through the communication interface. The detected current, after passing through Q2, R19, Q3, and R20, reaches GND1, which is VOUT. This is used to charge the capacitor C0 under test, and the current eventually returns to GND1 of the voltage generation module 200.

[0139] When the circuit is off, the main control module 100 outputs a low level at the switch control port, i.e., when ON / OFF=0V, the output voltage of the third operational amplifier U2 is -9V, i.e., VCC15=-9V; the DAC1 value is positive, and the output voltage of the current limiting threshold module 500 is affected by the DC power supply +9V, so the output voltage VCC11 is less than +9V; at the same time, the resistance of R9 is greater than the resistance of R10; as can be seen from the above formula (12), at this time the voltage of VCC9 is less than GND2, the voltage value of the fourth pin of the second operational amplifier U4, VCC10, is greater than the voltage value of the third pin of the second operational amplifier U4, VCC9, and the output voltage of U4, VCC6=-9V; at this time, VCC7=VCC6=-9V, which is much less than the turn-on voltage of the second regulating tube Q3, so the drain and source of the second regulating tube Q3 are in the cut-off state. Since the drain and source of the second regulating transistor Q3 are in the off state, the gate and source of the first regulating transistor Q2 cannot form a circuit, that is, the turn-on voltage of the first regulating transistor Q2 cannot be reached. Therefore, the drain and source of the first regulating transistor Q2 are in the completely off state. As a result, the first current limiting module 300 and the second current limiting module 400 are both in the off state, and the voltage generating module 200 cannot output VOUT to the capacitor C0 under test.

[0140] When the capacitor C0 under test is short-circuited, for the short-circuit protection module 900, based on the high impedance principle of the operational amplifier input, VCC16=VCC20, VCC19=VCC8. From the above equation (8), we can derive:

[0141] ;

[0142] When the voltage of VCC19 is less than VCC20 (reflecting that the detection current is within the user-set short-circuit threshold range), the output voltage of the fifth operational amplifier U5 is VCC21 = +5V; at this time, the output voltage of pin 2 of inverter U3 is VCC22 = 0V (i.e., GND2), and the drain and source of Q1 are completely cut off; the voltage at point VCC7 is not affected by the accelerated shutdown unit 930; at this time, the main control module 100 receives the short-circuit impact alarm signal Over through R14, which is at a high level (i.e. +5), and the main control module 100 does not respond.

[0143] When the capacitor C0 under test is short-circuited by an impulse, a very large current flows through R20 instantaneously. This causes a sudden increase in the voltage VCC8 across R20, and VCC19 increases accordingly. When the voltage of VCC19 exceeds VCC20 (reflecting a very large detection current exceeding the user-set short-circuit threshold), the output voltage VCC21 of the fifth operational amplifier U5 becomes 0V (i.e., GND2). At this time, the output voltage of the inverter U3 is VCC22 = +5V, and the drain and source of Q1 are fully conducting. VCC7 is energized. The voltage is quickly pulled down to GND2 through the drain and source of R17 and Q1. The gate and source voltage of Q3 is 0V (i.e., GND2), which is much lower than the turn-on voltage of Q3. Therefore, the fast response of Q3 enters the cut-off state. Since Q3 enters the cut-off state, the gate and source loop of Q2 is also cut off by the fast response. It cannot form a loop, that is, it cannot reach the turn-on voltage of Q2. Therefore, the drain and source fast response of Q2 enters the cut-off state. The voltage generation module 200 cannot output VOUT to the capacitor under test C0, thus realizing the short-circuit protection of the circuit.

[0144] At this time, the main control module 100 receives the short-circuit impact alarm signal Over low level (i.e. GND2) through R14. The main control module 100 responds to the fully shut-off output function state and outputs a low level ON / OFF=0V at the switch control port. According to equation (12), at this time, the voltage of VCC9 is less than GND2, VCC10 is greater than VCC9, and the output voltage of the second operational amplifier U4 is VCC6=-9V. At this time, when the main control module 100 responds to the fully shut-off output function state, regardless of whether the voltage at point VCC7 continues to be pulled down to GND2 by the accelerated shutdown unit 930, Q2 and Q3 are both in the cut-off state, protecting the entire circuit.

[0145] The capacitor high voltage withstand test response protection method according to the embodiments of this application has the function of fast response protection against short circuit breakdown, thereby avoiding a series of safety hazards such as MLCC capacitor breakdown, short circuit, and fire when the high-speed multi-channel sorting and testing machine tests MLCC capacitors at 2000V high withstand voltage, thus avoiding losses; the modular design of the circuit makes it easy to expand the output channels of the high voltage power supply, which can increase the output channels of the voltage generation module 200, simplify the interface control, simplify the process, reduce the cost, realize large-scale mass production, meet the needs of various equipment, meet various customer testing needs, and facilitate wide application.

[0146] The embodiments of the present invention have been described in detail above with reference to the accompanying drawings. However, the present invention is not limited to the above embodiments. Within the scope of knowledge possessed by those skilled in the art, various changes can be made without departing from the spirit of the present invention.

Claims

1. A capacitor high voltage withstand detection and response protection circuit, characterized in that, include: Main control module; The voltage generating module is electrically connected to the main control module; The first current limiting module has its input terminal electrically connected to the output terminal of the voltage generating module; The second current limiting module has its input terminal electrically connected to the output terminal of the first current limiting module, its output terminal electrically connected to one end of the capacitor under test, and the other end of the capacitor under test electrically connected to the input terminal of the voltage generating module. A current limiting threshold module, wherein the input terminal of the current limiting threshold module is electrically connected to the main control module; A drive feedback module, wherein the input terminal of the drive feedback module is electrically connected to the output terminal of the current limiting threshold module, and the output terminal of the drive feedback module is electrically connected to the controlled terminal of the second current limiting module; A switch module, wherein the input terminal of the switch module is electrically connected to the main control module, and the output terminal of the switch module is electrically connected to the input terminal of the drive feedback module; A constant voltage power supply module, wherein the output terminal of the constant voltage power supply module is electrically connected to the controlled terminal of the first current limiting module, and the constant voltage power supply module is also electrically connected to the main control module; A short-circuit protection module, wherein the input terminal of the short-circuit protection module is electrically connected to the main control module and the drive feedback module, and the output terminal of the short-circuit protection module is electrically connected to the second current limiting module. The short-circuit protection module is used to turn off the second current limiting module and the first current limiting module when the capacitor under test is short-circuited. The short-circuit protection module includes: The short-circuit threshold adjustment unit includes a thirteenth resistor, a fourteenth resistor, a fifteenth resistor, a sixteenth resistor, a second capacitor, and a fourth operational amplifier. The non-inverting input terminal of the fourth operational amplifier is electrically connected to the main control module through the thirteenth resistor. The non-inverting input terminal of the fourth operational amplifier is also grounded through the second capacitor. One end of the fourteenth resistor is grounded, and the other end of the fourteenth resistor is electrically connected to the inverting input terminal of the fourth operational amplifier and one end of the fifteenth resistor. The other end of the fifteenth resistor is electrically connected to the output terminal of the fourth operational amplifier. One end of the sixteenth resistor is electrically connected to the output terminal of the fourth operational amplifier. The threshold window comparison unit includes a fifth operational amplifier, a seventeenth resistor, and an eighteenth resistor. The non-inverting input of the fifth operational amplifier is electrically connected to the other end of the sixteenth resistor. The inverting input of the fifth operational amplifier is electrically connected to the drive feedback module through the seventeenth resistor. The positive power supply terminal of the fifth operational amplifier is connected to a second positive voltage, and the negative power supply terminal of the fifth operational amplifier is grounded. One end of the eighteenth resistor is connected to the second positive voltage, and the other end of the eighteenth resistor is electrically connected to the output terminal of the fifth operational amplifier. The accelerated shutdown unit includes an inverter, a switching transistor, and a nineteenth resistor. The input terminal of the inverter is electrically connected to the output terminal of the fifth operational amplifier, and the output terminal of the inverter is electrically connected to the controlled terminal of the switching transistor. The first terminal of the switching transistor is electrically connected to the controlled terminal of the second current limiting module through the nineteenth resistor, and the second terminal of the switching transistor is grounded. The twentieth resistor has one end electrically connected to the main control module and the other end electrically connected to the output terminal of the fifth operational amplifier.

2. The capacitor high voltage withstand detection and response protection circuit according to claim 1, characterized in that, A reverse isolation module is further provided between the constant voltage power supply module and the first current limiting module, the reverse isolation module comprising: A plurality of diodes are connected in series. The anode of the first diode is electrically connected to the output terminal of the constant voltage power supply module, and the cathode of the last diode is electrically connected to the controlled terminal of the first current limiting module through a first resistor.

3. The capacitor high voltage withstand detection and response protection circuit according to claim 2, characterized in that, The first current limiting module includes: The first regulating tube has its first end electrically connected to the output terminal of the voltage generating module, and its controlled end is electrically connected to the first resistor through the second resistor. The first Zener diode has its anode electrically connected to the input terminal of the second current limiting module, and its cathode electrically connected to the controlled terminal of the first regulating transistor. The third resistor has one end electrically connected to the second end of the first regulating tube, and the other end electrically connected to the input end of the second current limiting module. The second Zener diode has its anode electrically connected to the input terminal of the second current limiting module, and its cathode electrically connected to the second terminal of the first regulating tube.

4. The capacitor high voltage withstand detection and response protection circuit according to claim 1, characterized in that, The second current limiting module includes: The second regulating tube has its first end electrically connected to the output end of the first current limiting module, and its controlled end electrically connected to the output end of the drive feedback module through a fourth resistor. The third Zener diode has its anode electrically connected to one end of the capacitor under test, and its cathode electrically connected to the controlled end of the second regulating diode. The fifth resistor has one end electrically connected to the second end of the second regulating tube, and the other end electrically connected to one end of the capacitor to be tested. The fourth Zener diode has its anode electrically connected to one end of the capacitor under test, and its cathode electrically connected to the second end of the second regulating diode.

5. The capacitor high voltage withstand detection and response protection circuit according to claim 1, characterized in that, The current limiting threshold module includes: The first operational amplifier has its non-inverting input terminal electrically connected to the main control module via a sixth resistor. The non-inverting input terminal of the first operational amplifier is also grounded via a first capacitor. The positive power supply terminal of the first operational amplifier is connected to a first positive voltage, and the negative power supply terminal of the first operational amplifier is connected to a first negative voltage. The seventh resistor has one end grounded and the other end electrically connected to the inverting input terminal of the first operational amplifier. The eighth resistor has one end electrically connected to the other end of the seventh resistor, and the other end of the eighth resistor is electrically connected to the output terminal of the first operational amplifier. The ninth resistor has one end electrically connected to the other end of the eighth resistor, and the other end of the ninth resistor is electrically connected to the input terminal of the drive feedback module.

6. The capacitor high voltage withstand detection and response protection circuit according to claim 1, characterized in that, The drive feedback module includes: The second operational amplifier has its non-inverting input terminal electrically connected to the output terminal of the current limiting threshold module and the output terminal of the switching module, and its output terminal electrically connected to the controlled terminal of the second current limiting module. The positive power supply terminal of the second operational amplifier is connected to a first positive voltage, and the negative power supply terminal of the second operational amplifier is connected to a first negative voltage. The tenth resistor has one end electrically connected to the inverting input terminal of the second operational amplifier, and the other end electrically connected to the second current limiting module and the short-circuit protection module.

7. The capacitor high voltage withstand detection and response protection circuit according to claim 1, characterized in that, The switching module includes: The third operational amplifier has its non-inverting input terminal electrically connected to the main control module via an eleventh resistor, its inverting input terminal connected to a reference voltage, its positive power supply terminal connected to a second positive voltage, its negative power supply terminal connected to a first negative voltage, and its output terminal electrically connected to the input terminal of the drive feedback module via a twelfth resistor.

8. The capacitor high voltage withstand detection and response protection circuit according to claim 1, characterized in that, It also includes a voltage equalization protection module, which is electrically connected to the first current limiting module and the second current limiting module, and is used to provide voltage equalization protection for the first current limiting module and the second current limiting module.

9. A capacitor withstand high voltage detection response protection method, characterized in that, Based on the capacitor high voltage withstand detection and response protection circuit as described in any one of claims 1-8, the method includes: The main control module sets the current limiting threshold module and the switch module, so that the drive feedback module controls the second current limiting module to be in the conducting state. The constant voltage power supply module is configured via the main control module to enable the first current limiting module to be in a conducting state. A detection voltage and a detection current are generated by a voltage generation module, and the detection voltage and the detection current are used to detect the capacitor under test through the first current limiting module and the second current limiting module. When the capacitor under test is short-circuited, the first current limiting module and the second current limiting module are shut down by the short-circuit protection module.

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