CN216312666U - Direct current bus capacitor buffer protection circuit - Google Patents

Abstract

The embodiment of the application provides a direct current bus capacitance buffer protection circuit, including direct current input end, at least one bus capacitor unit, direct current input end is connected with bus capacitor unit, bus capacitor unit includes: a capacitor; the buffer resistor is connected with the capacitor in series; and the controllable switch is connected with the buffer resistor in parallel and bypasses the buffer resistor when the controllable switch is closed. According to the embodiment of the application, the buffer resistors are connected in series in the bus capacitor unit, and the buffer resistors are controlled to be connected in the state, so that high-current buffering and protection of the direct-current bus capacitor unit are achieved, high-current impact is effectively prevented, the service life of the capacitor is prolonged, and the working stability and reliability of a circuit system are effectively improved.

Description

Direct current bus capacitor buffer protection circuit

Technical Field

The embodiment of the application relates to the technical field of electronic circuits, in particular to a direct-current bus capacitor buffer protection circuit.

Background

The direct current bus is widely used for power electronic systems, such as frequency converters, inverters and the like, and is a key circuit for ensuring stable, safe and reliable operation of a direct current transmission and distribution system and a direct current grid system.

At present, as shown in fig. 1, in a power electronic system, a capacitor energy storage circuit or a capacitor filter circuit connected to a dc bus is usually designed, and since a charging current of a capacitor is very large at the moment of power-on, the capacitor is easily damaged, the life of the capacitor is shortened, and other devices or devices are also easily damaged.

SUMMERY OF THE UTILITY MODEL

The following is a summary of the subject matter described in detail herein. This summary is not intended to limit the scope of the claims.

The embodiment of the application provides direct current bus capacitor buffer protection circuit, can effectively prevent the impact of heavy current to improve the capacitor life-span.

In a first aspect, an embodiment of the present application provides a dc bus capacitor buffer protection circuit, which includes a dc input terminal, at least one bus capacitor unit, the dc input terminal is connected to the bus capacitor unit,

the bus bar capacitance unit includes:

a capacitor;

the buffer resistor is connected with the capacitor in series;

and the controllable switch is connected with the buffer resistor in parallel and bypasses the buffer resistor when the controllable switch is closed.

In some optional embodiments, the capacitor is an energy storage capacitor or a filter capacitor.

In some optional embodiments, there are a plurality of the bus capacitor units, and the plurality of the bus capacitor units are connected in parallel.

In some alternative embodiments, there are a plurality of said controllable switches, and a plurality of said controllable switches are connected in parallel.

In some optional embodiments, there are a plurality of the buffer resistors, and the plurality of the buffer resistors are connected in series or in parallel.

In some alternative embodiments, the snubber resistor is a fusible snubber resistor.

In some optional embodiments, the bus capacitor unit comprises a plurality of the capacitors, and the plurality of the capacitors are connected in series or in parallel.

In some optional embodiments, the bus capacitor unit comprises a number of capacitors, which is matched with a voltage value of the input end and a withstand voltage value of the capacitors.

In some optional embodiments, the capacitor is further connected in parallel with a discharge resistor.

In some optional embodiments, the dc bus capacitor buffer protection circuit further includes:

the direct current output end is connected with the bus capacitor unit;

and the current detection device or the voltage detection device is connected with the direct current output end and is used for correspondingly detecting the current or the voltage of the direct current output end.

The first aspect of the embodiment of the present application provides a dc bus capacitor buffer protection circuit, including dc input end, at least one bus capacitor unit, dc input end is connected with bus capacitor unit, bus capacitor unit includes: a capacitor; the buffer resistor is connected with the capacitor in series; and the controllable switch is connected with the buffer resistor in parallel and bypasses the buffer resistor when the controllable switch is closed. According to the embodiment of the application, the buffer resistors are connected in series in the bus capacitor unit, and the buffer resistors are controlled to be connected in the state, so that high-current buffering and protection of the direct-current bus capacitor unit are achieved, high-current impact is effectively prevented, the service life of the capacitor is prolonged, and the working stability and reliability of a circuit system are effectively improved.

It is to be understood that the advantageous effects of the second aspect compared to the related art are the same as the advantageous effects of the first aspect compared to the related art, and reference may be made to the related description of the first aspect, which is not repeated herein.

Drawings

In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings required to be used in the embodiments or the related technical descriptions will be briefly introduced below, and it is obvious that the drawings in the following description are only some embodiments of the present application, and it is obvious for those skilled in the art to obtain other drawings based on these drawings without inventive labor.

FIG. 1 is a schematic diagram of a related art DC bus capacitor circuit;

fig. 2 is a schematic structural diagram of a dc bus capacitor buffer protection circuit according to an embodiment of the present disclosure;

fig. 3 is a schematic structural diagram of a dc bus capacitor buffer protection circuit according to another embodiment of the present disclosure.

Detailed Description

In the following description, for purposes of explanation and not limitation, specific details are set forth, such as particular system structures, techniques, etc. in order to provide a thorough understanding of the embodiments of the present application. It will be apparent, however, to one skilled in the art that the embodiments of the present application may be practiced in other embodiments that depart from these specific details. In other instances, detailed descriptions of well-known systems, devices, circuits, and methods are omitted so as not to obscure the description of the embodiments of the present application with unnecessary detail.

It should be noted that, although a logical order is illustrated in the flowcharts, in some cases, the steps illustrated or described may be performed in an order different from that in the flowcharts. The terms first, second and the like in the description and in the claims, and the drawings described above, are used for distinguishing between similar elements and not necessarily for describing a particular sequential or chronological order.

It should also be appreciated that reference throughout the specification to "one embodiment" or "some embodiments," or the like, means that a particular feature, structure, or characteristic described in connection with the embodiment is included in one or more embodiments of the present application. Thus, appearances of the phrases "in one embodiment," "in some embodiments," "in other embodiments," or the like, in various places throughout this specification are not necessarily all referring to the same embodiment, but rather "one or more but not all embodiments" unless specifically stated otherwise. The terms "comprising," "including," "having," and variations thereof mean "including, but not limited to," unless expressly specified otherwise.

The direct current bus is widely used for power electronic systems, such as frequency converters, inverters and the like, and is a key circuit for ensuring stable, safe and reliable operation of a direct current transmission and distribution system and a direct current grid system.

At present, as shown in fig. 1, in a power electronic system, a capacitor energy storage circuit or a capacitor filter circuit connected to a dc bus is usually designed, and since a charging current of a capacitor is very large at the moment of power-on, the capacitor is easily damaged, the life of the capacitor is shortened, and other devices or devices are also easily damaged.

Based on this, this application provides a direct current bus capacitance buffer protection circuit, wherein, direct current bus capacitance buffer protection circuit includes direct current input end, at least one bus capacitor unit, direct current input end and bus capacitor unit are connected, bus capacitor unit includes: a capacitor; the buffer resistor is connected with the capacitor in series; and the controllable switch is connected with the buffer resistor in parallel and bypasses the buffer resistor when the controllable switch is closed. According to the embodiment of the application, the buffer resistors are connected in series in the bus capacitor unit, and the buffer resistors are controlled to be connected in the state, so that high-current buffering and protection of the direct-current bus capacitor unit are achieved, high-current impact is effectively prevented, the service life of the capacitor is prolonged, and the working stability and reliability of a circuit system are effectively improved.

In a first aspect, referring to fig. 2, an embodiment of the present application provides a dc bus capacitor buffer protection circuit, which includes a dc input terminal, at least one bus capacitor unit, the dc input terminal is connected to the bus capacitor unit,

the bus bar capacitance unit includes:

capacitance (bus capacitance);

the buffer resistor is connected with the capacitor in series;

and the controllable switch is connected with the buffer resistor in parallel and bypasses the buffer resistor when the controllable switch is closed.

In some embodiments, the dc bus is a high voltage dc bus, which may be, for example, 100V to 300V. In the related technology, a bus capacitor is connected between the positive electrode and the negative electrode of a direct current bus, and as the voltage of the capacitor cannot be suddenly changed, current flows from the positive electrode to the negative electrode through the bus capacitor at the moment of electrification, which is equivalent to a short circuit state, and the current flowing through the capacitor is very large, thus tripping or even damage to a device is easily caused. According to the embodiment of the application, the buffer resistor is connected to the bus capacitor unit in series, and the bypass state of the buffer resistor is controlled through the controllable switch, so that in the charging instant or charging process of the capacitor, the current of the direct current bus can reach the negative electrode from the positive electrode through the capacitor and the buffer resistor, and the buffer protection of the circuit is realized.

In some embodiments, the controllable switch may be an electrically controlled switching device, such as a relay. The controllable switch may be controlled by a controller. The controller can be a nerve center and a command center of the electronic power equipment. The controller can generate an operation control signal according to the instruction operation code and the timing signal to complete the control of instruction fetching and instruction execution. The relay can be used for realizing low-voltage control of the high-voltage bus capacitor unit, namely, the relay obtains a low-voltage control signal from the controller, so that the working state of the high-voltage bus capacitor unit is controlled.

According to the embodiment of the application, the buffer resistors are connected in series in the bus capacitor unit, and the buffer resistors are controlled to be connected in the state, so that high-current buffering and protection of the direct-current bus capacitor unit are achieved, high-current impact is effectively prevented, the service life of the capacitor is prolonged, and the working stability and reliability of a circuit system are effectively improved.

In some optional embodiments, the capacitor is an energy storage capacitor or a filter capacitor.

In some embodiments, the capacitor may be a bus capacitor for storing energy, and the energy stored in the capacitor may be used to power a load or other circuits, or may be consumed by a discharging resistor, which is not limited in this application. In other embodiments, the capacitor may also be a filter capacitor for filtering, which may implement filtering and voltage stabilizing processing on the current of the dc bus to provide a stable current to the load; in other embodiments, capacitors may be used for both energy storage and filtering.

In some embodiments, the energy stored by the capacitor may be used to power other devices of the electronic power apparatus, such as a load, a controller, a voltage or current detection module, and so forth. When the output of the capacitor is high voltage and needs to supply power to a low-voltage device (such as a controller), the high voltage can be converted into low voltage through a voltage conversion circuit (not shown in the figure) to provide power for the low-voltage device. The controller can control the relay through low pressure to control the operating condition of bus capacitor unit, realize low pressure control high pressure.

In some optional embodiments, there are a plurality of the bus capacitor units, and the plurality of the bus capacitor units are connected in parallel.

In some embodiments, the bus capacitor may be formed by a start-up snubber unit (including a controllable switch and a snubber resistor) bypassed by the centralized controllable switch in series with the centralized bus capacitor. The bus capacitor can only be put into, buffered or cut off as a whole. When a single component device in the circuit fails, the entire dc bus circuit may fail, thereby causing the entire device to fail and shut down. Meanwhile, the danger of fire of the starting buffer unit, damage of a bus capacitor and the like can be caused, and the generated impact can further damage a rectifying device, an alternating current/direct current power supply device or a front-end filtering device and the like at the front end of the circuit.

Although various power electronic devices can prompt users to replace the capacitor by predicting or detecting the service life of the bus capacitor, the reliability of the equipment is improved; or the suction state of the controllable switch is judged by detecting the pressure drop of the starting buffer unit or the feedback signal of the controllable switch, and fault alarm is carried out. But the problem that the whole circuit is invalid due to the fault of a single device, so that the whole equipment is stopped cannot be solved. Meanwhile, the device faults occurring in the operation process can not be effectively protected in time, so that the fault expansion is avoided, and the loss is reduced.

In view of the above problems, the embodiments of the present application further design a dc bus capacitor, a buffer resistor, and a controllable switch grouping parallel circuit, so as to solve the problem of shutdown of the whole device due to a failure of a part of devices, or device damage due to a wiring error.

Referring to fig. 3, firstly, in the embodiment of the present application, the dc bus capacitors and the buffer protection circuit are grouped, and when a part of the bus capacitor units fails, a part of the failure circuit is timely disconnected, and a part of the parallel branches of the failed capacitors are cut off, so that the remaining effective groups (the bus capacitor units) can ensure that the whole machine continues to operate, thereby improving the availability of the equipment.

Secondly, through the grouping of the direct-current bus capacitor and the buffer protection circuit, when part of grouping devices are in fault, because other groups are still in a normal state, the impact on a system can be reduced, the fault expansion is avoided, a rectifying device at the front end of the circuit, an alternating-current and direct-current power supply device or a front-end filtering device is damaged, and the loss is reduced.

In some alternative embodiments, there are a plurality of said controllable switches, and a plurality of said controllable switches are connected in parallel.

In practice, due to the possible failure of the controllable switch after receiving the driving signal, the opening or closing is not performed as expected, resulting in failure to achieve the intended circuit control. For example, when the buffer resistor needs to be bypassed, the controller sends out a control signal to control the controllable switch to be closed, and at this time, if the controllable switch is not closed, the bypass of the buffer resistor cannot be realized. In view of the above problems, in some embodiments, each bus capacitor unit includes a plurality of controllable switches, the plurality of controllable switches are connected in parallel, and the plurality of controllable switches can be driven by the same signal, so as to improve reliability. For example, when the buffer resistor needs to be bypassed, the controller sends out a control signal to control the controllable switches to be closed, and at the moment, if part of the controllable switches are not closed, other controllable switches can be closed, and the bypass of the buffer resistor can still be realized, so that the normal use of the circuit function is effectively guaranteed.

In some optional embodiments, there are a plurality of the buffer resistors, and the plurality of the buffer resistors are connected in series or in parallel.

In some embodiments, a plurality of buffer resistors may be provided according to circuit characteristics (e.g., magnitude of input voltage) and electrical parameters of the electrical element (e.g., resistance value of the resistor). A plurality of buffer resistors may be connected in parallel; alternatively, a plurality of buffer resistors may be connected in series; alternatively, some of the buffer resistors may be connected in series and then connected in parallel to other buffer resistors.

In some alternative embodiments, the snubber resistor is a fusible snubber resistor.

In some embodiments, the buffer resistor is a fusible resistor, and disconnection protection of the bus capacitor unit can be realized. For example, when the controllable switches of some bus capacitor units are not closed, the input end supplies power to the dc bus, and if the over-current time of the buffer resistor is too long, the buffer resistor of the bus capacitor unit will be fused, so that the bus capacitor unit is cut off from the dc bus circuit system, and the related power electronic devices and equipment can be used continuously or derated, thereby realizing the protection of the circuit. For another example, when a capacitor of a certain bus capacitor unit has a short-circuit fault, if the controllable switch is not closed, the buffer resistor will be fused, and the bus capacitor unit will be cut off from the direct-current bus circuit system; if the bypass unit is in a closed state, the bypass unit can be combined with a controllable switch of a fusible contact, the closed contact of the controllable switch is fused at the moment, current flows through the buffer resistor, the buffer resistor is fused continuously, and the bus capacitor unit is cut off from the direct-current bus circuit system, so that related power electronic devices and equipment can be used continuously or derated, and the circuit protection is realized.

In some optional embodiments, the bus capacitor unit comprises a plurality of the capacitors, and the plurality of the capacitors are connected in series or in parallel. In some embodiments, the bussed capacitive unit may comprise a plurality of capacitors connected in series, depending on circuit characteristics (e.g. magnitude of input voltage) and electrical parameters of the electrical components (e.g. withstand voltage of the capacitors). A plurality of capacitors may be connected in parallel; alternatively, multiple capacitors may be connected in series; alternatively, some capacitors may be connected in series and then connected in parallel with other capacitors.

In some optional embodiments, the bus capacitor unit comprises a number of capacitors, which is matched with a voltage value of the input end and a withstand voltage value of the capacitors.

For example, when the voltage of the input end is 300V, and the withstand voltage value of the capacitor is 120V, 3 capacitors can be selected to be connected in series in the bus capacitor unit, so that the performance and the safety of the circuit are guaranteed. In addition, due to the fact that the capacitors with different voltage withstanding values are different in materials, volumes and cost, flexible circuit element configuration can be achieved in the mode, and therefore a better or more appropriate circuit is constructed.

In some optional embodiments, the capacitor is further connected in parallel with a discharge resistor.

In some embodiments, the capacitor is connected in parallel with a discharge resistor, so that when the circuit does not work, the energy stored in the capacitor can be discharged through the discharge resistor; when the circuit does not work, the energy stored by each capacitor can be discharged through the corresponding discharging resistor. During the circuit power-on period, the capacitor can be charged, but when the input end does not output current or is powered by other auxiliary power supplies, if the direct current bus does not discharge the electric energy due to the discharge resistor, safety accidents are easily caused.

In some optional embodiments, the dc bus capacitor buffer protection circuit further includes:

the direct current output end is connected with the bus capacitor unit;

and the current detection device or the voltage detection device is connected with the direct current output end and is used for correspondingly detecting the current or the voltage of the direct current output end.

In some embodiments, a load is connected to the dc output, and the dc output is configured to provide a dc supply voltage to the load. In some embodiments, the dc output is further provided with a current detection device or a voltage detection device for correspondingly detecting the current or the voltage of the dc output. The current or voltage of the direct current output end can be detected through the current detection device or the voltage detection device, and when the current or voltage of the direct current output end is abnormal, an alarm signal can be output. In other embodiments, the current detection device or the voltage detection device may further be connected with an alarm device (such as an audio alarm device, a light alarm device, etc.), so as to implement an abnormal alarm.

The following further illustrates embodiments of the present application in connection with a complete example.

Example 1

Referring to fig. 3, the dc bus capacitor buffer protection circuit of the present example may be used in a power electronic device (which may be a frequency converter or an inverter, etc.), and is designed to be formed by connecting multiple sets of bus capacitor units in parallel. The direct-current bus capacitor buffer protection circuit comprises an input end, N groups of bus capacitor units and an output end which are sequentially connected, and the output end is connected with a load. And a current detection device or a voltage detection device is also connected between the output end and the load, wherein N is a positive integer greater than or equal to 2.

Each bus capacitor unit comprises a capacitor subunit formed by connecting a plurality of capacitors in series or in parallel or simultaneously connecting the capacitors in series or in parallel with the voltage equalizing circuit, a buffer resistor subunit (resistor subunit for short) formed by connecting one or more buffer resistors in series or in parallel, and a buffer resistor bypass subunit (bypass subunit for short) formed by connecting one or more controllable open loops in parallel.

And after being connected in parallel with a bypass subunit, one resistor subunit is connected in series with one capacitor subunit to form a bus capacitor unit.

The plurality of bus capacitor units are connected in parallel and then connected to a direct current input end or a direct current reactor end of the power electronic device to form a direct current bus circuit of the power electronic device.

The buffer resistor is a fusible resistor.

Referring to fig. 3, the bus capacitor unit 1 includes a capacitor subunit, a resistor subunit, and a bypass subunit. The bus capacitor unit 1 comprises capacitors C111, C112, C121 and C122 and discharge resistors R111, R112, R121 and R122, the resistor subunit comprises buffer resistors R11, R12 and the like, and the bypass subunit comprises controllable switches K11, K12 and the like. In the capacitor subunit, capacitors C111 and C112 are connected in series, capacitors C121 and C122 are connected in series, and then the two series branches are connected in parallel; the discharge resistors R111, R112, R121 and R122 are correspondingly connected with the capacitors C111, C112, C121 and C122 in parallel and used for discharging the electric energy stored in the capacitors. In the resistor subunit, a buffer resistor R11 is connected in parallel with the buffer resistor R12, and then connected in series with the capacitor subunit. In the bypass subunit, controllable switches K11 and K12 are connected in parallel, and then in parallel with the resistor subunit.

Similarly, the bus capacitor unit 2 includes a capacitor subunit, a resistor subunit and a bypass subunit. The bus capacitor unit 1 comprises capacitors C211, C212, C221 and C222 and discharge resistors R211, R212, R221 and R222, the resistor subunit comprises buffer resistors R21, R22 and the like, and the bypass subunit comprises controllable switches K21, K22 and the like. In the capacitor subunit, capacitors C211 and C212 are connected in series, capacitors C221 and C222 are connected in series, and then the two series branches are connected in parallel; the discharge resistors R211, R212, R221 and R222 are correspondingly connected with the capacitors C211, C212, C221 and C222 in parallel and used for discharging the electric energy stored in the capacitors. In the resistor subunit, a buffer resistor R21 is connected in parallel with the buffer resistor R22, and then connected in series with the capacitor subunit. In the bypass subunit, controllable switches K21 and K22 are connected in parallel, and then in parallel with the resistor subunit.

In some application scenarios, the buffer resistor is a fusible resistor, and when the controllable switch of a part of the bus capacitor unit is not closed, if the input end supplies power to the dc bus at this time, the part of the buffer resistor will be fused, so that the part of the bus capacitor unit is cut off from the dc bus circuit. The associated power electronics and equipment may continue or be derated.

In other application scenes, if the contact adhesion fault of the controllable switch of part of the bus capacitor units occurs, if the direct-current bus is supplied with power, the rest of the bus capacitor units connected in parallel normally play a role in buffering, so that the impact on a rectifier device or an alternating-current/direct-current power supply device at the front end can be effectively reduced, the damage of the front-end device is avoided, and the power electronic device and the equipment can still be continuously and normally used.

In other application scenarios, when the capacitor sub-units of part of the bus capacitor units have open circuit faults, the bus capacitor units are automatically cut off from the direct current bus circuit. The associated power electronics and equipment may continue or be derated.

In some application scenarios, when a short-circuit fault occurs in a capacitor subunit of a part of the bus capacitor unit, if the bypass subunit is not closed, the resistor subunit is fused, and the bus capacitor unit is cut off from the direct-current bus circuit; if the bypass subunit is in a closed state, the closed contact of the bypass subunit will be blown, and the resistance subunit will be continuously caused to be blown, and the bus capacitor unit will be cut off from the direct current bus circuit system. The associated power electronics and equipment may continue or be derated.

In the related art, once the power input is mistakenly connected to the output terminal, the dc bus circuit of the power electronic device inevitably damages the device and cannot be effectively protected. Through setting up a plurality of bus capacitor units, can effectively prevent the device damage, and can cooperate the voltage or the current detection of former input or output, realize the fault suggestion.

In some application scenes, when a wiring error occurs, such as when a power supply is input from an output end, the resistance unit and the bypass unit can still effectively buffer and protect related devices, and signals such as voltage or current of the input end or the output end can be detected by combining a current detection device or a voltage detection device of the input end or the output end, so that fault prompt is realized.

The first aspect of the embodiment of the present application provides a dc bus capacitor buffer protection circuit, including dc input end, at least one bus capacitor unit, dc input end is connected with bus capacitor unit, bus capacitor unit includes: a capacitor; the buffer resistor is connected with the capacitor in series; and the controllable switch is connected with the buffer resistor in parallel and bypasses the buffer resistor when the controllable switch is closed. According to the embodiment of the application, the buffer resistors are connected in series in the bus capacitor unit, and the buffer resistors are controlled to be connected in the state, so that high-current buffering and protection of the direct-current bus capacitor unit are achieved, high-current impact is effectively prevented, the service life of the capacitor is prolonged, and the working stability and reliability of a circuit system are effectively improved.

While the preferred embodiments of the present invention have been described in detail, it will be understood, however, that the invention is not limited to those precise embodiments, and that various other modifications and substitutions may be affected therein by one skilled in the art without departing from the scope of the invention.

Claims (10)

1. A DC bus capacitor buffer protection circuit is characterized by comprising a DC input end and at least one bus capacitor unit, wherein the DC input end is connected with the bus capacitor unit,

the bus bar capacitance unit includes:

a capacitor;

the buffer resistor is connected with the capacitor in series;

and the controllable switch is connected with the buffer resistor in parallel and bypasses the buffer resistor when the controllable switch is closed.

2. The dc bus capacitor buffer protection circuit of claim 1, wherein the capacitor is an energy storage capacitor or a filter capacitor.

3. The dc bus capacitor buffer protection circuit of claim 1, wherein there are a plurality of said bus capacitor units, and a plurality of said bus capacitor units are connected in parallel.

4. The dc bus capacitor snubber protection circuit of claim 1, wherein there are a plurality of the controllable switches, and a plurality of the controllable switches are connected in parallel.

5. The dc bus capacitor buffer protection circuit as claimed in claim 1, wherein there are a plurality of said buffer resistors, and a plurality of said buffer resistors are connected in series or in parallel.

6. The dc bus capacitor snubber protection circuit of claim 1, wherein the snubber resistor is a fusible snubber resistor.

7. The dc bus capacitor buffer protection circuit of claim 1, wherein said bus capacitor unit comprises a plurality of said capacitors, and said plurality of said capacitors are connected in series or in parallel.

8. The dc bus capacitor buffer protection circuit of claim 1, wherein the bus capacitor unit comprises a number of capacitors matching a voltage value of the input terminal and a withstand voltage value of the capacitors.

9. The dc bus capacitor buffer protection circuit of claim 1, wherein the capacitor is further connected in parallel with a discharge resistor.

10. The dc bus capacitor snubber protection circuit of any one of claims 1 to 8, further comprising:

the direct current output end is connected with the bus capacitor unit;

and the current detection device or the voltage detection device is connected with the direct current output end and is used for correspondingly detecting the current or the voltage of the direct current output end.

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