Bus capacitance detection circuit

Abstract

According to the bus capacitance detection circuit provided by the embodiment of the invention, a bus voltage acquisition unit electrically connected with a power supply bus samples bus voltage to monitor voltage change of the power supply bus, and a regulation and control unit electrically connected with the bus voltage acquisition unit discharges the power supply bus to a preset voltage threshold after receiving a capacitance value test instruction. The timing unit electrically connected with the regulation and control unit can count the discharge operation duration of the regulation and control unit, and the capacitance value operation unit electrically connected with the timing unit calculates the ground capacitance value of the bus based on the charge and discharge characteristics of the capacitor and a first electric signal corresponding to the discharge operation duration. Therefore, a worker can overhaul the direct-current power supply system and the load thereof when the ground capacitance of the bus is relatively large, and the reason for the abnormal ground capacitance is determined and solved, so that the normal operation of the direct-current power supply system is ensured.

Description

Technical Field

[0001] The embodiments of this application relate to the field of power electronics technology, and in particular to a bus capacitance detection circuit. Background Technology

[0002] DC power supply systems are a crucial component for providing power to data centers, and they should operate in an ungrounded mode. When the bus capacitance to ground of a DC power supply system is large, this capacitance will filter the control signals received by the system, potentially causing at least one problem such as delays in the control signal's activation time or data offset within the control signals, leading to abnormal power supply to the DC power supply system.

[0003] Determining the bus-to-ground capacitance of a DC power supply system has become a key research focus. Summary of the Invention

[0004] This application provides a bus capacitance detection circuit to solve the above-mentioned technical problems.

[0005] This application provides a bus capacitance detection circuit, including:

[0006] The bus voltage acquisition unit has its input terminal electrically connected to the power bus and is used to sample the bus voltage.

[0007] The control unit has its first end electrically connected to the output end of the bus voltage sampling unit and its second end electrically connected to the power bus. It is used to discharge the power bus when the bus voltage is greater than a preset voltage threshold after receiving a capacitance value test command.

[0008] A timing unit, whose input terminal is electrically connected to the output terminal of the control unit, is used to count the discharge time of the power bus to discharge to a preset voltage threshold and output a first electrical signal corresponding to the discharge time;

[0009] The capacitance value calculation unit has its input terminal electrically connected to the timing unit, and is used to obtain the reference electrical signal and the first electrical signal, and output the second electrical signal corresponding to the bus capacitor.

[0010] The voltage value of the second electrical signal and the capacitance value of the bus capacitor are in a preset ratio.

[0011] In the above technical solution, the bus voltage acquisition unit samples the bus voltage to monitor the voltage change of the power bus. After receiving the capacitance value test command, the control unit electrically connected to it discharges the power bus to a preset voltage threshold. The timing unit can count the discharge operation time of the control unit so that the capacitance value calculation unit can calculate the bus-to-ground capacitance value based on the capacitance charging and discharging characteristics and the first electrical signal corresponding to the discharge operation time. This allows the staff to inspect the DC power system and its load when the bus-to-ground capacitance is large, identify and resolve the cause of the abnormal ground capacitance, and ensure the normal operation of the DC power system.

[0012] Optionally, the control unit includes: a switching control unit and a switching unit;

[0013] The first end of the switching control unit serves as the first end of the control unit, and its output end serves as the output end of the control unit. Its second end is electrically connected to the first end of the switching unit, and is used to control the switching unit to conduct to ground when the bus voltage is greater than a preset voltage threshold after receiving a capacitance value test command.

[0014] The second end of the switching unit serves as the second end of the control unit, and is used to discharge the power bus when it is connected to ground.

[0015] Optionally, the switching control unit includes:

[0016] The judgment unit, whose first terminal serves as the first terminal of the switching control unit and whose output terminal serves as the output terminal of the switching control unit, is used to obtain the sampling voltage and the first reference voltage of the power bus after receiving the capacitance value test command, and output a control electrical signal at a first level when the sampling voltage is greater than the first reference voltage; the first reference voltage is a voltage value that is proportional to the preset voltage threshold.

[0017] The switching operation unit has its input terminal electrically connected to the output terminal of the judgment unit, and its output terminal electrically connected to the switching unit. It is used to control the switching unit to turn on when the control electrical signal at the first level is obtained.

[0018] Optionally, the determination unit includes:

[0019] The first controllable switch, whose first end serves as the first end of the judgment unit, is used to turn on after receiving a capacitance value test command, and outputs the sampled voltage obtained from its first end from its second end.

[0020] The first comparator has its first input terminal electrically connected to the second terminal of the first controllable switch, its second input terminal electrically connected to the reference voltage generation circuit, and its output terminal serving as the output terminal of the judgment unit. It is used to obtain a sampled voltage from its first input terminal and the first reference voltage from its second input terminal. When the sampled voltage is greater than the first reference voltage, it outputs a control electrical signal at a first level.

[0021] Optionally, the first controllable switch is further configured to turn off upon receiving a capacitance value interruption test command, thereby stopping the output of the sampled voltage obtained from its first terminal from its second terminal.

[0022] Optionally, the switching operation unit includes:

[0023] A controllable transistor, whose control terminal is electrically connected or coupled to the input terminal of the switching operation unit, whose second terminal is grounded, and whose first terminal and second terminal are connected when the voltage difference between its control terminal and its second terminal is within a preset voltage range;

[0024] A relay coil, with its first end electrically connected to a second power supply and its second end electrically connected to the first end of the controllable transistor, is used to control the switching unit to conduct by driving current when the first and second ends of the controllable transistor are turned on.

[0025] Optionally, the switching unit includes: a relay contact and a first resistor;

[0026] The first end of the relay contact is electrically connected to the power bus, and its second end is electrically connected to the first end of the first resistor. The second end of the first resistor is grounded, which is used to discharge the power bus to ground when its first end and second end are connected.

[0027] Optionally, the timing unit includes:

[0028] The counter has a first input terminal as the input terminal of the timing unit, and a second input terminal electrically connected to the clock unit. It is used to obtain a control electrical signal at its first terminal and a clock signal at its second terminal. When the control electrical signal is at a first level, it outputs a counting electrical signal.

[0029] An adjustment unit, whose input terminal is electrically connected to the output terminal of the counter, and whose output terminal is electrically connected or coupled to the output terminal of the timing unit, is used to convert the counting electrical signal into the first electrical signal.

[0030] Optionally, the adjustment unit includes:

[0031] The digital-to-analog converter circuit has its input terminal and the input terminal of the adjustment unit, and its output terminal and the output terminal of the timing unit electrically connected or coupled, for converting the counting electrical signal into a corresponding analog voltage signal to determine the first electrical signal.

[0032] Optionally, the capacitance value calculation unit includes:

[0033] The division operation circuit has a first input terminal as the input terminal of the capacitance value calculation unit, a second input terminal grounded, a third input terminal electrically connected to a third power supply, and an output terminal as the output terminal of the capacitance value calculation unit. It is used to obtain a first electrical signal from its first terminal, obtain a second reference voltage from its third input terminal, and output a second electrical signal based on the second reference voltage, the first electrical signal, and the operation ratio of the division operation circuit.

[0034] Optionally, the division circuit includes:

[0035] An analog multiplier, whose first input terminal serves as the third input terminal of the division operation circuit, and whose second input terminal is electrically connected to the output terminal of the division operation circuit;

[0036] The seventh resistor has its first end electrically connected to the output terminal of the analog multiplier;

[0037] An operational amplifier, whose inverting input terminal is electrically connected to the second terminal of the seventh resistor, whose non-inverting input terminal is electrically connected to the first terminal of the reference resistor, and whose output terminal is electrically connected to the second input terminal of the analog multiplier;

[0038] The second terminal of the reference resistor is grounded;

[0039] The sixth resistor has its first end serving as the first input terminal of the division operation circuit, and its second end electrically connected to the inverting input terminal of the operational amplifier.

[0040] The bus capacitance detection circuit provided in this application embodiment includes a bus voltage acquisition unit electrically connected to the power bus to sample the bus voltage and monitor the voltage change of the power bus. Upon receiving a capacitance value test command, a control unit electrically connected to the control unit discharges the power bus to a preset voltage threshold. A timing unit electrically connected to the control unit can statistically analyze the discharge operation duration of the control unit. A capacitance value calculation unit electrically connected to the timing unit calculates the bus-to-ground capacitance value based on the capacitor charging and discharging characteristics and the first electrical signal corresponding to the discharge operation duration. This allows personnel to inspect the DC power system and its load when the bus-to-ground capacitance is large, identify and resolve the cause of the abnormal ground capacitance, and ensure the normal operation of the DC power system. Attached Figure Description

[0041] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with this application and, together with the description, serve to explain the principles of this application.

[0042] Figure 1 This is a schematic diagram of the structure of a bus capacitance detection circuit provided in an exemplary embodiment of this application;

[0043] Figure 2 This is a schematic diagram of the circuit structure of a bus capacitance detection circuit provided in an exemplary embodiment of this application;

[0044] Figure 3 This is a schematic diagram of the circuit structure of a bus capacitance detection circuit provided in another exemplary embodiment of this application;

[0045] Figure 4 This is a schematic diagram of the circuit structure of a division operation circuit provided in this application according to an exemplary embodiment.

[0046] The accompanying drawings illustrate specific embodiments of this application, which will be described in more detail below. These drawings and descriptions are not intended to limit the scope of the concept in any way, but rather to illustrate the concept of this application to those skilled in the art through reference to particular embodiments. Detailed Implementation

[0047] Exemplary embodiments will now be described in detail, examples of which are illustrated in the accompanying drawings. When the following description relates to the drawings, unless otherwise indicated, the same numbers in different drawings denote the same or similar elements. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with this application. Rather, they are merely examples of apparatuses and methods consistent with some aspects of this application as detailed in the appended claims.

[0048] It should be noted that, in this document, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes that element. Furthermore, components, features, and elements with the same names in different embodiments of this application may have the same meaning or different meanings, the specific meaning of which must be determined by its interpretation in that specific embodiment or further in conjunction with the context of that specific embodiment.

[0049] It should be understood that the specific embodiments described herein are merely illustrative of this application and are not intended to limit this application.

[0050] DC power supply systems are a crucial component for providing power to data centers, and they should operate in an ungrounded mode. When the bus capacitance to ground of a DC power supply system is large, this capacitance will filter the control signals received by the system, potentially causing at least one problem such as delays in the control signal's activation time or data offset within the control signals, leading to abnormal power supply to the DC power supply system.

[0051] Determining the bus-to-ground capacitance of a DC power supply system has become a key research focus.

[0052] To address the aforementioned technical problems, this application provides a bus capacitance detection circuit. The technical concept of this application is as follows: when measuring the bus-to-ground capacitance of a DC power supply system, a switching circuit is used to discharge the power bus. The power bus's ground capacitance and the equivalent resistance of the switching circuit form an RC discharge circuit. Based on the charging and discharging characteristics of the RC circuit, the discharge duration of the switching circuit, and the voltage change of the power bus, the capacitance value of the power bus to ground can be calculated.

[0053] Figure 1 This is a schematic diagram of the bus capacitance detection circuit provided in an exemplary embodiment of this application, as shown below. Figure 1 The circuit structure shown includes a bus capacitance detection circuit comprising: a bus voltage acquisition unit 12, a control unit 13, a timing unit 14, and a capacitance value calculation unit 15.

[0054] The bus voltage acquisition unit 12 has its input terminal electrically connected to the power bus 11 and is used to sample the bus voltage.

[0055] The control unit 13 has its first end electrically connected to the output end of the bus voltage sampling unit 12 and its second end electrically connected to the power bus 11. It is used to discharge the power bus when the bus voltage is greater than the preset voltage threshold after receiving the capacitance value test command.

[0056] The capacitance test command is a command to connect the circuit between the input terminal of the control unit 13 and the output terminal of the bus voltage acquisition unit 12.

[0057] The control unit 13 will not discharge the power bus before receiving a capacitance value test command.

[0058] The timing unit 14, whose input terminal is electrically connected to the output terminal of the control unit 13, is used to count the discharge time of the power bus and output the first electrical signal corresponding to the discharge time; wherein, the discharge time of the power bus can be the continuous discharge time of the power bus 11.

[0059] The capacitance value calculation unit 15 is electrically connected to the timing unit 14 at its input terminal. It is used to obtain a reference electrical signal and a first electrical signal, and outputs a second electrical signal corresponding to the bus capacitor.

[0060] The voltage value of the second electrical signal and the capacitance value of the bus capacitor are in a preset ratio.

[0061] In the above technical solution, the bus voltage acquisition unit samples the bus voltage to monitor the voltage change of the power bus. After receiving the capacitance value test command, the control unit electrically connected to it discharges the power bus to a preset voltage threshold. The timing unit can count the discharge operation time of the control unit so that the capacitance value calculation unit can calculate the bus-to-ground capacitance value based on the capacitance charging and discharging characteristics and the first electrical signal corresponding to the discharge operation time. This allows the staff to inspect the DC power system and its load when the bus-to-ground capacitance is large, identify and resolve the cause of the abnormal ground capacitance, and ensure the normal operation of the DC power system.

[0062] The specific circuit structure of the bus capacitance detection circuit provided in this application will be explained below with reference to several embodiments.

[0063] Figure 2 This is a schematic diagram of the circuit structure of a bus capacitance detection circuit provided in this application according to an exemplary embodiment.

[0064] refer to Figure 2 The bus voltage acquisition circuit 12 includes a first voltage divider resistor R1 and a second voltage divider resistor R2. The first end of the first voltage divider resistor R1 is electrically connected to the power bus 11, and the second end of the first voltage divider resistor R1 is electrically connected to the first end of the second voltage divider resistor R2. The second end of the second voltage divider resistor R2 is grounded. The connection point of the two voltage divider resistors serves as the output terminal of the bus voltage acquisition unit. The output sampled voltage value V1 is the product of the bus voltage value and the first voltage division ratio, where the first voltage division ratio is the ratio of the resistance value of the second voltage divider resistor R2 to the sum of the resistance values ​​of the two voltage divider resistors.

[0065] In some embodiments, the bus voltage acquisition circuit 12 further includes a first filter capacitor C1, the first end of the first filter capacitor C1 and the first end of the second voltage divider resistor R2 are electrically connected, and the second end is grounded, for filtering the output sampled voltage value V1 to ensure the stability of the sampled voltage value V1.

[0066] Continue to refer to Figure 2 The circuit structure shown includes a control unit 13 comprising a switching control unit 131 and a switching unit 132.

[0067] The first end of the switching control unit 131 serves as the first end of the control unit 13 and is electrically connected to the output end of the bus voltage sampling circuit 12. Its output end (at the output end of the first comparator U1) serves as the output end of the control unit 13. Its second end is electrically connected to the first end of the switching unit 132 and is used to control the switching unit 132 to conduct to ground when the bus voltage is greater than the preset voltage threshold.

[0068] The second end of the switching unit 132 serves as the second end of the control unit 13, and is used to discharge the power bus 11 when it is connected to ground.

[0069] In some embodiments, the switching control unit 131 includes a judgment unit 1311 and a switching operation unit 1312.

[0070] The first terminal of the judgment unit 1311 serves as the first terminal of the switching control unit 131, and its output terminal serves as the output terminal of the switching control unit 131. It is used to obtain the sampling voltage of the power bus and the first reference voltage Vref1 after receiving the capacitance value test command, and output a control electrical signal at the first level when the sampling voltage is greater than the first reference voltage Vref1.

[0071] The sampling voltage is the voltage division of the power supply bus voltage by the voltage divider resistor in the bus voltage acquisition circuit 12;

[0072] Wherein, the first reference voltage Vref1 is a voltage value that is proportional to a preset voltage threshold.

[0073] The judgment unit 1311 is also used to output a control signal at the second level when the sampled voltage is less than the first reference voltage Vref1;

[0074] When the sampling voltage is equal to the first reference voltage Vref1, an intermediate level control signal is output, wherein the voltage value of the intermediate level signal is between the first level and the second level.

[0075] The input terminal of the switching operation unit 1312 is electrically connected to the output terminal of the judgment unit 1311, and its output terminal is electrically connected to the switching unit 132. It is used to control the switching unit 132 to conduct when a control electrical signal at the first level is obtained.

[0076] In some embodiments, the determining unit 1311 includes:

[0077] The first controllable switch K1 serves as the bus capacitor detection start switch.

[0078] The first terminal of the first controllable switch K1 serves as the first terminal of the judgment unit 1311, which is used to turn on after receiving the capacitance value test command and output the sampled voltage obtained from the first terminal from its second terminal.

[0079] When the operator needs to measure the capacitance value of the bus capacitor, the first controllable switch K1 is turned on so that the control unit 13 can obtain the sampling voltage V1 for subsequent comparison, switching, timing and calculation operations.

[0080] Among them, the first controllable switch K1 is a normally open switch. After the staff performs capacitance measurement and operates it, the first controllable switch K1 closes to conduct.

[0081] In some embodiments, the operator can directly operate the first controllable switch K1 to turn it on;

[0082] In other embodiments, operators can generate capacitance value test commands through the control circuit of the bus capacitance detection circuit.

[0083] More specifically, the output terminal of the control circuit is electrically connected to the control terminal of the first controllable switching device in the bus capacitance detection circuit, and the control circuit responds to the capacitance value test command generated by the capacitance detection trigger command.

[0084] Among them, the capacitance detection trigger command is a command generated based on the input information received by the control circuit from the staff.

[0085] The control circuit can receive input information from staff through at least one of the following methods: touch screen, mouse click on preset module icons, mouse input, voice input, gesture recognition, etc.

[0086] In some embodiments, the judgment unit 1311 further includes a first comparator U1, whose first input terminal is electrically connected to the second terminal of the first controllable switch K1, whose second input terminal is electrically connected to the reference voltage generation circuit, and whose output terminal serves as the output terminal of the judgment unit. Figure 2 In the circuit structure shown, the first input terminal of the first comparator U1 is its non-inverting input terminal, and the second input terminal is its inverting input terminal.

[0087] The first comparator U1 is used to obtain a sampled voltage V1 from its first input terminal and a first reference voltage Vref1 from its second input terminal. When the sampled voltage V1 is greater than the first reference voltage Vref1, it outputs a control electrical signal at the first level.

[0088] When the sampling voltage V1 is less than the first reference voltage Vref1, the output is a control signal at the second level.

[0089] When the sampling voltage V1 is equal to the first reference voltage Vref1, the control signal at the intermediate state level is output.

[0090] In some embodiments, a first controllable switch K1 is connected in series between the non-inverting input terminal of the first comparator U1 and the output terminal of the bus voltage acquisition unit 12, serving as a bus capacitance detection start switch.

[0091] In some embodiments, the circuit structure of the reference voltage generation circuit 16 can be referenced. Figure 3 The circuit structure shown includes a ninth voltage divider resistor R9, a tenth voltage divider resistor R10, a third filter capacitor C3, and a second controllable switch K2.

[0092] Among them, the first end of the ninth voltage divider resistor R9 is electrically connected to the power bus 11, its second end is electrically connected to the first end of the tenth voltage divider resistor R10 and the first end of the second controllable switch K2, the second end of the tenth voltage divider resistor R10 is grounded, the second end of the second controllable switch K2 is electrically connected to the first end of the third filter capacitor C3, and the second end of the third filter capacitor C3 is grounded.

[0093] The first terminal of the third filter capacitor C3 provides the output terminal of the first reference voltage Vref1 for the reference voltage generation circuit 16.

[0094] The sum of the resistance values ​​of the tenth voltage divider resistor R10 and the two voltage divider resistors refers to the second voltage division ratio of the voltage generation circuit 16. This second voltage division ratio is 0.63 times the first voltage division ratio, where 0.63 is the proportion of voltage change after the power bus discharges for one discharge time constant.

[0095] The ratio 0.63 is just an example and can be replaced with other integer multiples of the discharge time constant. No limitation is made here.

[0096] The third filter capacitor C3 is used to filter and store the voltage division values ​​of the bus voltage by the two voltage divider resistors mentioned above.

[0097] Among them, the second controllable switch K2 is a normally closed switch. When the operator performs the bus-to-ground capacitance measurement, the bus capacitance measurement circuit responds to the capacitance value test command, controls the first controllable switch K1 to be turned on, and at the same time operates the second controllable switch K2 to be turned off. Then, the voltage value of the first reference voltage Vref1 output by the third filter capacitor C3 is not affected by the voltage change when the power bus 11 is discharging.

[0098] In some embodiments, the first controllable switch K1 is further configured to turn off upon receiving a capacitance value interruption test command, thereby stopping the output of the sampled voltage obtained from its first terminal from its second terminal.

[0099] The second controllable switch K2 is also used to turn on after receiving a capacitance value interruption test command, and update the voltage value of the first reference voltage Vref1 output at its output terminal.

[0100] Among them, the capacitance value interruption test command is the command obtained by the control unit after the staff determines the ground capacitance value output by the bus capacitance detection circuit.

[0101] The method for generating this instruction is the same as that for generating the capacitance value test instruction, so it will not be described again here.

[0102] In some embodiments, the determination unit 1311 further includes a second filter capacitor C2, the first end of which is electrically connected to the output terminal of the first comparator U1, and the second end of which is grounded, for filtering the control electrical signal output by the first comparator U1 to improve the reliability of control.

[0103] In some embodiments, the switching operation unit 1312 includes a controllable transistor Q1 and a relay coil K3.

[0104] The control terminal of the controllable transistor Q1 is electrically connected or coupled to the input terminal of the switching operation unit 1312, and its second terminal is grounded. When the voltage difference between its control terminal and its second terminal is within a preset voltage range, its first terminal and its second terminal are turned on.

[0105] In some embodiments, the controllable transistor Q1 is a bipolar transistor, with its base as its control terminal, its emitter as its second terminal, and its collector as its first terminal.

[0106] The base of the transistor is electrically connected to the output terminal of the judgment unit 1311, which is used to control the collector and emitter to conduct when the voltage value of the control signal output by the judgment unit 1311 is greater than or equal to its conduction voltage, and to turn off when it is less than its conduction voltage.

[0107] When the high-level voltage value output by the first comparator U1 is too large, a third voltage divider resistor R3 and a fourth voltage divider resistor R4 can be set in the switching operation unit 1312. The first end of the third voltage divider resistor R3 is electrically connected to the output end of the first comparator U1, the second end is electrically connected to the control end of the controllable transistor Q1 and the first end of the fourth voltage divider resistor R4, and the second end of the fourth voltage divider resistor R4 is grounded.

[0108] The two voltage-dividing resistors mentioned above are used to divide the high-level output of the first comparator U1, and the divided voltage value is greater than or equal to the turn-on voltage of the controllable transistor Q1. By adjusting the resistance ratio of the two voltage-dividing resistors, the voltage division value of the high-level control signal can turn on the controllable transistor Q1, while the voltage division value of the control signal at other levels can turn off the controllable transistor Q1.

[0109] It is worth noting that the controllable transistor Q1 is a triode, which is just an example for the sake of illustration in this embodiment. Other devices that can be controlled to switch on and off based on voltage can also be used as controllable transistor Q1, such as: MOS transistor, IGBT transistor, TFT transistor, relay, optocoupler, etc., which will not be listed here.

[0110] The first terminal of the relay coil K3 is electrically connected to the second power supply VDD, and its second terminal is electrically connected to the first terminal of the controllable transistor Q3. This is used to control the switching unit to turn on by driving current when the first and second terminals of the controllable transistor Q3 are turned on.

[0111] More specifically, the relay includes a relay coil K3 and a relay contact S1. When the relay coil K3 is not energized, no electromagnetic force is generated, and the relay contact S1 does not receive electromagnetic force, so its first and second terminals are open. When the relay coil K3 is energized, electromagnetic force is generated, and the relay contact S1 closes its first and second terminals after receiving electromagnetic force.

[0112] Based on this characteristic, the relay contact S1 can be set in the switching unit 132 to control the ground discharge process of the switching unit 132.

[0113] Continue to refer to Figure 2 The circuit structure shown includes a switching unit 132 comprising: a relay contact S1 and a first resistor R5;

[0114] The first end of the relay contact S1 is electrically connected to the power bus 11, and its second end is electrically connected to the first end of the first resistor R5. The second end of the first resistor R5 is grounded, which is used to discharge the power bus to ground when its first and second ends are connected.

[0115] Continue to refer to Figure 2 The circuit structure shown includes a timing unit 14 comprising a counter 141 and an adjustment unit 142.

[0116] The first input terminal of the counter 141 serves as the input terminal of the timing unit 14, and its second input terminal is electrically connected to the clock unit. It is used to obtain a control signal at its first terminal and a clock signal at its second terminal. When the control signal is at the first level, it outputs a counting signal.

[0117] The clock unit is a unit that provides a fixed frequency clock signal. In some embodiments, the clock unit includes a crystal oscillator or a clock signal generation circuit based on the crystal oscillator.

[0118] Due to the characteristics of counter 141, the counting signal is a digital signal.

[0119] The input terminal of the adjustment unit 142 is electrically connected to the output terminal of the counter 141, and its output terminal is electrically connected or coupled to the output terminal of the timing unit 14, which is used to convert the counting electrical signal into a first electrical signal.

[0120] The first electrical signal is an analog electrical signal.

[0121] In some embodiments, the adjustment unit 142 includes:

[0122] The digital-to-analog converter (DAC) circuit, whose input terminal is the input terminal of the adjustment unit 142, and whose output terminal is electrically connected or coupled to the output terminal of the timing unit 14, is used to convert the counting electrical signal into a corresponding analog voltage signal to determine the first electrical signal V2.

[0123] In some embodiments, the analog voltage signal output by the DAC can be directly output as the first electrical signal V2;

[0124] In other embodiments, the counting unit 14 further includes an amplifier electrically connected between the output of the DAC and the output of the counting unit 14, for signal amplification of the analog voltage signal and outputting a first electrical signal V2.

[0125] Continue to refer to Figure 2 The circuit structure shown includes a capacitance value calculation unit 15 comprising:

[0126] The division operation circuit 151 has a first input terminal as the input terminal of the capacitance value operation unit 15, a second input terminal grounded, a third input terminal electrically connected to a third power supply, and an output terminal as the output terminal of the capacitance value operation unit 15. It is used to obtain a first electrical signal V2 from its first terminal and a second reference voltage Vref2 from its third input terminal. Based on the operation ratio of the second reference voltage Vref2, the first electrical signal V2, and the division operation circuit 151, it outputs a second electrical signal Vo.

[0127] In some embodiments, the circuit structure of the division operation circuit 151 can be referred to Figure 4 The circuit shown, the division operation circuit 151 includes:

[0128] The analog multiplier U3 has its first input terminal as the third input terminal of the division operation circuit 151, and its second input terminal is electrically connected to the output terminal of the division operation circuit 151. The output voltage value is the product of the voltage values ​​of the two input terminals and their preset product ratio.

[0129] The seventh resistor R7 has its first terminal electrically connected to the output terminal of the analog multiplier U3;

[0130] Operational amplifier U2 has its inverting input terminal U2- electrically connected to the second terminal of the seventh resistor R7, its non-inverting input terminal U2+ electrically connected to the first terminal of the reference resistor R8, and its output terminal electrically connected to the second input terminal of analog multiplier U3.

[0131] The second terminal of the reference resistor R8 is grounded;

[0132] The sixth resistor R6 has its first end serving as the first input terminal of the division operation circuit 151, and its second end being electrically connected to the inverting input terminal U2- of the operational amplifier U2.

[0133] Based on the above circuit structure, the voltage relationship between the output terminal and each input terminal of the division operation circuit 151 is as follows: Wherein, Uo represents the voltage value of the second electrical signal output by the division circuit 151, R7 represents the resistance value of the seventh resistor, R6 represents the resistance value of the sixth resistor, k represents the preset product ratio of the analog multiplier U3, V2 represents the voltage value of the first electrical signal, and Vref2 represents the voltage value of the second reference voltage.

[0134] By The preset amplification ratio is used to adjust the relationship between the output voltage value and the bus capacitor. For example, when the time constant applied to Vref1 is 1, the value is set to the quotient of 1 divided by the first resistor R5, and the output voltage value is the same as the capacitance value of the bus capacitor. When the time constant applied to Vref1 is multiple times the time constant, the value is set to the quotient of 1 divided by multiple times the first resistor R5, and the multiple of the first resistor R5 is the multiple of the time constant.

[0135] In some embodiments, the output of the division operation circuit 151 is also electrically connected to a second comparator. The non-inverting input of the second comparator is electrically connected to the output of the division operation circuit 151, the inverting input is electrically connected to a preset level generation circuit, and the output is electrically connected to an alarm.

[0136] Among them, the preset level generation circuit is the circuit of the third reference voltage, which is the voltage value converted by the maximum capacitance to ground that the DC power supply system can withstand.

[0137] The second comparator is used to control the alarm to sound when the voltage value of the second electrical signal Vo obtained at its non-inverting input is greater than the third reference voltage value.

[0138] When the voltage value of the second electrical signal Vo obtained at its non-inverting input terminal is less than or equal to the three reference voltage values, the alarm will not be triggered.

[0139] Based on the above circuit structure, the following section discusses... Figure 3 The operation of the circuit structure shown will be explained.

[0140] Before the technicians calculate the capacitance to ground of the power bus, the first controllable switch K1 is opened and the second controllable switch K2 is closed. Then the voltage value V1 on the left side of the first controllable switch K1 will change proportionally with the change of the power bus voltage.

[0141] The voltage value Vref1 on the right side of the second controllable switch K2 also changes proportionally with the change of the bus voltage, and the ratio of V1 to Vref1 is 1:0.63, where 0.63 is the proportion of voltage change after the time constant corresponding to the discharge time constant 1 of the RC circuit.

[0142] When technicians calculate the capacitance to ground of the power bus, they operate the first controllable switch K1 and the second controllable switch K2 to turn on the first controllable switch K1 and turn off the second controllable switch K2. Then, the first terminal of the first filter capacitor C1 outputs a sampling voltage V1 to the power bus, and this voltage value changes proportionally with the change of the bus voltage.

[0143] The voltage output from the first terminal of the third filter capacitor C3 is the voltage divided by the ninth voltage divider resistor R9 and the tenth voltage divider resistor R10 on the bus voltage before the second controllable switch K2 is turned off. This voltage serves as the first reference voltage Vref1. When both controllable switches are operating, the voltage value of the first reference voltage Vref1 is 0.63 times the voltage value of the sampled voltage V1. Furthermore, after the second controllable switch K2 is turned off, the first reference voltage Vref1 output by the third filter capacitor C3 remains unchanged.

[0144] The first comparator U1 outputs a high-level control signal after comparing the sampling voltage V1 and the first reference voltage Vref1. This control signal controls the controllable transistor Q1 to turn on, so that the relay coil K3 is energized and electromagnetic force is generated to close the relay contact S1.

[0145] The closed relay contact S1 and the first resistor R5 form a discharge path from the power bus 11 to ground, and under the influence of the ground capacitance of the power bus 11, this discharge path forms an RC discharge path.

[0146] The RC discharge path continues to discharge until the voltage value of the sampled voltage V1 is less than or equal to the first reference voltage Vref1. The first comparator U1 stops outputting a high-level control signal, the controllable transistor Q1 turns off, no more current flows through the relay coil K3, the electromagnetic force disappears, the relay contact S1 turns off, and the discharge to the power bus 11 stops.

[0147] Counter 141 receives control signals. When the control signal it receives is high, it counts up following the clock signal until the control signal changes to another level. The digital signal output by counter 141 is the counting signal corresponding to the time when the switching unit 132 continuously discharges to the power bus 11. This count value will not change before it receives the initialization signal.

[0148] The DAC 142 converts the counting electrical signal and outputs an analog voltage value, which is the first electrical signal V2 corresponding to the bus discharge time.

[0149] After obtaining the first electrical signal, the division circuit 151 calculates the first electrical signal V2, outputs the second electrical signal Vo to determine the bus capacitance, and displays the bus capacitance value.

[0150] The second comparator compares the voltage value of the second electrical signal Vo with the third reference voltage, and controls the alarm to sound when the voltage value of the second electrical signal Vo is greater than the third reference voltage.

[0151] After the staff determines the calculated capacitance value to ground, the controller can send an initialization signal to the counter 141 to reset its count value.

[0152] After the staff determines the calculated capacitance value to ground, the bus capacitance detection circuit receives a capacitance value stop test command to disconnect the first controllable switch K1 and turn on the second controllable switch K2, so that the bus capacitance detection circuit does not affect the voltage value of the power bus.

[0153] In the above technical solution, when measuring the bus-to-ground capacitance of the DC power supply system, the bus voltage acquisition unit, which is electrically connected to the power bus, samples the bus voltage to monitor changes in the bus voltage. After receiving the capacitance value test command, the control unit, upon determining that the bus voltage is greater than a preset voltage threshold, discharges the power bus using a switching circuit. The bus-to-ground capacitance and the equivalent resistance of the switching circuit form an RC discharge circuit. Based on the charging and discharging characteristics of the RC circuit, the discharge time of the switching circuit, and the voltage change of the power bus, the capacitance value of the bus-to-ground capacitance can be calculated. This allows personnel to inspect the DC power supply system and its load when the bus-to-ground capacitance is large, identify and resolve the cause of the abnormal ground capacitance, and ensure the normal operation of the DC power supply system.

[0154] Other embodiments of this application will readily occur to those skilled in the art upon consideration of the specification and practice of the disclosure herein. This application is intended to cover any variations, uses, or adaptations of this application that follow the general principles of this application and include common knowledge or customary techniques in the art not disclosed herein. The specification and examples are to be considered exemplary only, and the true scope and spirit of this application are indicated by the following claims.

[0155] It should be understood that this application is not limited to the precise structure described above and shown in the accompanying drawings, and various modifications and changes can be made without departing from its scope. The scope of this application is limited only by the appended claims.

Claims

1. A bus capacitance detection circuit, characterized in that, include: The bus voltage acquisition unit has its input terminal electrically connected to the power bus and is used to sample the bus voltage. The control unit has its first end electrically connected to the output end of the bus voltage sampling unit and its second end electrically connected to the power bus. It is used to discharge the power bus when the bus voltage is greater than a preset voltage threshold after receiving a capacitance value test command. A timing unit, whose input terminal is electrically connected to the output terminal of the control unit, is used to count the discharge time of the power bus and output a first electrical signal corresponding to the discharge time. The capacitance value calculation unit has its input terminal electrically connected to the timing unit, and is used to obtain the reference electrical signal and the first electrical signal, and output the second electrical signal corresponding to the bus capacitor. The voltage value of the second electrical signal and the capacitance value of the bus capacitor are in a preset ratio.

2. The bus capacitance detection circuit according to claim 1, characterized in that, The control unit includes: a switching control unit and a switching unit; The first end of the switching control unit serves as the first end of the control unit, and its output end serves as the output end of the control unit. Its second end is electrically connected to the first end of the switching unit, and is used to control the switching unit to conduct to ground when the bus voltage is greater than a preset voltage threshold after receiving a capacitance value test command. The second end of the switching unit serves as the second end of the control unit, and is used to discharge the power bus when it is connected to ground.

3. The bus capacitance detection circuit according to claim 2, characterized in that, The switching control unit includes: The judgment unit, whose first terminal serves as the first terminal of the switching control unit and whose output terminal serves as the output terminal of the switching control unit, is used to obtain the sampling voltage and the first reference voltage of the power bus after receiving the capacitance value test command, and output a control electrical signal at a first level when the sampling voltage is greater than the first reference voltage; the first reference voltage is a voltage value that is proportional to the preset voltage threshold. The switching operation unit has its input terminal electrically connected to the output terminal of the judgment unit, and its output terminal electrically connected to the switching unit. It is used to control the switching unit to turn on when the control electrical signal at the first level is obtained.

4. The bus capacitance detection circuit according to claim 3, characterized in that, The determination unit includes: The first controllable switch, whose first end serves as the first end of the judgment unit, is used to turn on after receiving a capacitance value test command, and outputs the sampled voltage obtained from its first end from its second end. The first comparator has its first input terminal electrically connected to the second terminal of the first controllable switch, its second input terminal electrically connected to the reference voltage generation circuit, and its output terminal serving as the output terminal of the judgment unit. When the sampled voltage is obtained from its first input terminal, the first reference voltage is obtained from its second input terminal. When the sampled voltage is greater than the first reference voltage, the first comparator outputs a control electrical signal at a first level.

5. The bus capacitance detection circuit according to claim 4, characterized in that, The first controllable switch is also used to turn off upon receiving a capacitance value interruption test command, thereby stopping the output of the sampled voltage obtained from its first terminal from its second terminal.

6. The bus capacitance detection circuit according to claim 3, characterized in that, The switching operation unit includes: A controllable transistor, whose control terminal is electrically connected or coupled to the input terminal of the switching operation unit, whose second terminal is grounded, and whose first terminal and second terminal are connected when the voltage difference between its control terminal and its second terminal is within a preset voltage range; A relay coil, with its first end electrically connected to a second power supply and its second end electrically connected to the first end of the controllable transistor, is used to control the switching unit to conduct by driving current when the first and second ends of the controllable transistor are turned on.

7. The bus capacitance detection circuit according to claim 6, characterized in that, The switching unit includes: a relay contact and a first resistor; The first end of the relay contact is electrically connected to the power bus, and its second end is electrically connected to the first end of the first resistor. The second end of the first resistor is grounded, which is used to discharge the power bus to ground when its first end and second end are connected.

8. The bus capacitance detection circuit according to claim 1, characterized in that, The timing unit includes: The counter has a first input terminal as the input terminal of the timing unit, and a second input terminal electrically connected to the clock unit. It is used to obtain a control electrical signal at its first terminal and a clock signal at its second terminal. When the control electrical signal is at a first level, it outputs a counting electrical signal. An adjustment unit, whose input terminal is electrically connected to the output terminal of the counter, and whose output terminal is electrically connected or coupled to the output terminal of the timing unit, is used to convert the counting electrical signal into the first electrical signal.

9. The bus capacitance detection circuit according to claim 8, characterized in that, The adjustment unit includes: The digital-to-analog converter circuit has its input terminal and the input terminal of the adjustment unit, and its output terminal and the output terminal of the timing unit electrically connected or coupled, for converting the counting electrical signal into a corresponding analog voltage signal to determine the first electrical signal.

10. The bus capacitance detection circuit according to claim 1, characterized in that, The capacitance value calculation unit includes: The division operation circuit has a first input terminal as the input terminal of the capacitance value calculation unit, a second input terminal grounded, a third input terminal electrically connected to a third power supply, and an output terminal as the output terminal of the capacitance value calculation unit. It is used to obtain a first electrical signal from its first terminal, obtain a second reference voltage from its third input terminal, and output a second electrical signal based on the second reference voltage, the first electrical signal, and the operation ratio of the division operation circuit.

11. The bus capacitance detection circuit according to claim 10, characterized in that, The division operation circuit includes: An analog multiplier, whose first input terminal serves as the third input terminal of the division operation circuit, and whose second input terminal is electrically connected to the output terminal of the division operation circuit; The seventh resistor has its first end electrically connected to the output terminal of the analog multiplier; An operational amplifier, whose inverting input terminal is electrically connected to the second terminal of the seventh resistor, whose non-inverting input terminal is electrically connected to the first terminal of the reference resistor, and whose output terminal is electrically connected to the second input terminal of the analog multiplier; The second terminal of the reference resistor is grounded; The sixth resistor has its first end serving as the first input terminal of the division operation circuit, and its second end electrically connected to the inverting input terminal of the operational amplifier.

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