CN116203409A - Power conversion system and main switch short circuit detection method thereof - Google Patents
Power conversion system and main switch short circuit detection method thereof Download PDFInfo
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- CN116203409A CN116203409A CN202310034691.6A CN202310034691A CN116203409A CN 116203409 A CN116203409 A CN 116203409A CN 202310034691 A CN202310034691 A CN 202310034691A CN 116203409 A CN116203409 A CN 116203409A
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R31/00—Arrangements for testing electric properties; Arrangements for locating electric faults; Arrangements for electrical testing characterised by what is being tested not provided for elsewhere
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Abstract
The application provides a power conversion system and a main switch short circuit detection method thereof. In the short-circuit fault detection method, when all the first side main switches in the power conversion system do not have short-circuit faults, the power converter in the power conversion system is utilized to charge the second side bus capacitor in the power conversion system, so that when the second side voltage of the power conversion system is equal to zero, the second bus capacitor can be charged, the condition that the voltages at two ends of the second bus capacitor are always consistent with the second side voltage is avoided, and further misjudgment in the process of short-circuit fault detection of the second side main switches is avoided; the power conversion system can also be a direct current conversion system, and the second side main switch can also be a contactor, so that the main switch short circuit detection method of the power conversion system can avoid misjudgment in the process of carrying out adhesion fault detection on the contactor at one side of the direct current conversion system when the voltage at the other side of the direct current conversion system is equal to zero.
Description
Technical Field
The invention relates to the technical field of power electronics, in particular to a power conversion system and a main switch short circuit detection method thereof.
Background
At present, in order to ensure the safe operation of the direct current conversion system, before the direct current conversion system is started, the adhesion fault detection is carried out on contactors at two sides of the direct current conversion system respectively; in general, before the adhesion failure detection of one contactor, the one-side bus capacitor needs to be charged by the one-side voltage of the dc conversion system.
However, when the operation mode of the dc conversion system is the constant bus voltage operation mode, since the voltage on one side of the dc conversion system is equal to zero, the charging of the bus capacitor on the side of the dc conversion system cannot be achieved, so that the voltages on both ends of the bus capacitor on the side are always consistent with the voltages on the side, and further misjudgment occurs in adhesion fault detection, that is, the dc conversion system cannot be started normally.
Therefore, how to avoid erroneous judgment in the process of performing adhesion fault detection on the contactor at one side of the direct current conversion system when the voltage at the other side is equal to zero is a technical problem to be solved.
Disclosure of Invention
In view of the above, the present invention provides a power conversion system and a method for detecting a short circuit of a main switch thereof, so as to avoid erroneous judgment in the process of detecting a stuck fault of a contactor at one side of a dc conversion system when the voltage at the other side is equal to zero.
In order to achieve the above object, the embodiment of the present invention provides the following technical solutions:
in one aspect, the application provides a method for detecting a short circuit of a main switch of a power conversion system, wherein a first side of the power conversion system is connected with a power supply, and a second side of the power conversion system is a direct current side; the main switch short circuit detection method comprises the following steps:
judging whether all first side main switches in the power conversion system have no short circuit fault;
if all the first side main switches do not have short-circuit faults, charging a second side bus capacitor in the power conversion system by using a first side voltage of the power conversion system and a power converter in the power conversion system;
and after the charging is completed, detecting the short-circuit fault of each second side main switch in a divided manner.
Optionally, the detecting the short-circuit fault of one of the second side main switches includes:
the second side main switches to be detected are in an off state and the rest second side main switches are in an on state through control of each second side main switch;
judging whether the voltage of two ends of the second side bus capacitor after being charged is equal to the second side voltage of the power conversion system;
and if the voltage of the two ends of the second side bus capacitor after being charged is equal to the second side voltage of the power conversion system, judging that the second side main switch to be detected has a short-circuit fault.
Optionally, if the power converter is used as a voltage source, the voltages at two ends of the second side bus capacitor are charged to a first preset value, and the first preset value is smaller than or equal to a set voltage value of the second side bus capacitor.
Optionally, if the power converter is used as a current source, the voltages at two ends of the second side bus capacitor are charged to a second preset value; the difference between the second side voltage of the power conversion system minus the second preset value is less than or equal to a first preset overvoltage.
Optionally, charging a second side bus capacitor in the power conversion system with a power converter in the power conversion system includes:
and closing all the first side main switches, and controlling the power converter to perform power conversion.
Optionally, if the first side of the power conversion system is a dc side and each of the first side main switches is connected in parallel with a slow start circuit, determining whether all the first side main switches in the power conversion system have no short-circuit fault includes:
charging a first side bus capacitor in the power conversion system by using the first side voltage of the power conversion system and all the slow start circuits;
after the charging is completed, short-circuit fault detection is carried out on each first side main switch in a divided manner, and a corresponding detection result is obtained;
and if each detection result is that the first side main switch to be detected has no short circuit fault, executing the step of charging the second side bus capacitor in the power conversion system by using the power converter in the power conversion system.
Optionally, detecting a short-circuit fault of one of the first side main switches, and obtaining a corresponding detection result, including:
the first side main switches to be detected are in an off state by controlling each first side main switch, and the rest first side main switches are in an on state;
judging whether the voltage of the first side of the power conversion system is equal to the voltage of two ends of the charged first side bus capacitor or not;
and if the voltage of the first side of the power conversion system is not equal to the voltage of the two ends of the charged first side bus capacitor, the corresponding detection result is that the first side main switch to be detected has no short circuit fault.
Another aspect of the present application provides a power conversion system comprising: the power converter comprises a controller, a power converter, a first side bus capacitor, a second side bus capacitor, at least one first side main switch and at least one second side main switch; wherein:
the first side bus capacitor is connected between two poles of the first side of the power converter;
the second side bus capacitor is connected between two poles of the second side of the power converter;
a first side of the power converter is connected to a first side of the power conversion system, and a second side of the power converter is connected to a second side of the power conversion system;
the first side main switch is arranged on: a first port of the first side of the power converter and a first port of the first side of the power conversion system or a second port of the first side of the power converter and a second port of the first side of the power conversion system;
the second side main switch is arranged on: a positive electrode of the second side of the power converter and a positive electrode of the second side of the power conversion system, or a negative electrode of the second side of the power converter and a negative electrode of the second side of the power conversion system;
the power converter and all the main switches are controlled by the controller, and the controller is used for executing the main switch short circuit detection method according to any one of the aspects of the application.
Optionally, the first side of the power conversion system is a direct current side or an alternating current side.
Optionally, if the first side of the power conversion system is a dc side, the power conversion system further includes: at least one slow start circuit; wherein:
each slow start circuit is connected with: two ends of a corresponding first side main switch;
all the slow start circuits are controlled by the controller.
Optionally, if the first side of the power conversion system is a dc side, the first side main switch is a circuit breaker, a contactor, a MOS transistor, or an IGBT;
if the first side of the power conversion system is an ac side, the first side main switch is a circuit breaker or contactor.
Optionally, the second side main switch is a breaker, a contactor, a MOS transistor or an IGBT.
According to the technical scheme, the invention provides a main switch short circuit detection method of a power conversion system, which is suitable for the power conversion system with a power supply connected to a first side and a direct current side connected to a second side. In the short-circuit fault detection method, when all the first side main switches in the power conversion system do not have short-circuit faults, the power converter in the power conversion system is utilized to charge the second side bus capacitor in the power conversion system, so that when the second side voltage of the power conversion system is equal to zero, the second bus capacitor can be charged, the condition that the voltages at two ends of the second bus capacitor are always consistent with the second side voltage is avoided, and further misjudgment in the process of short-circuit fault detection of the second side main switches is avoided; the power conversion system can also be a direct current conversion system, and the second side main switch can also be a contactor, so that the main switch short circuit detection method of the power conversion system can avoid misjudgment in the process of carrying out adhesion fault detection on the contactor at one side of the direct current conversion system when the voltage at the other side of the direct current conversion system is equal to zero.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings that are required to be used in the embodiments or the description of the prior art will be briefly described below, and it is obvious that the drawings in the following description are only embodiments of the present invention, and that other drawings can be obtained according to the provided drawings without inventive effort for a person skilled in the art.
Fig. 1 is a schematic flow chart of an implementation of a method for detecting a short circuit of a main switch of a power conversion system according to an embodiment of the present application;
fig. 2 is a flowchart illustrating a specific example of a method for detecting a short circuit of a main switch of a power conversion system according to an embodiment of the present application;
fig. 3 is a schematic flow chart of a specific implementation manner of short-circuit fault detection for a second side main switch according to an embodiment of the present application;
FIG. 4 is a schematic flow chart of another implementation of a method for detecting a short circuit of a main switch of a power conversion system according to an embodiment of the present disclosure;
FIG. 5 is a schematic flow chart of a specific implementation manner of short-circuit fault detection for a first side main switch according to an embodiment of the present application;
fig. 6 is a schematic structural diagram of a power conversion system according to an embodiment of the present application.
Fig. 7 and fig. 8 are schematic structural diagrams of two specific examples of the power conversion system provided in the embodiment of the present application, respectively.
Detailed Description
The following description of the embodiments of the present application will be made clearly and fully with reference to the accompanying drawings, in which it is evident that the embodiments described are only some, but not all, of the embodiments of the present application. All other embodiments, which can be made by one of ordinary skill in the art based on the embodiments herein without making any inventive effort, are intended to be within the scope of the present application.
In this application, relational terms such as first and second, and the like are used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. Also, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising one … …" does not exclude the presence of other like elements in a process, method, article, or apparatus that comprises the element.
In order to avoid misjudgment in the process of carrying out adhesion fault detection on a contactor at one side of a direct current conversion system when the voltage at the other side is equal to zero, the application provides a main switch short circuit detection method of the power conversion system, which is suitable for the power conversion system with a power supply connected to a first side and a direct current side at a second side.
Wherein the power conversion system comprises two sides, respectively denoted as a first side and a second side; optionally, the first side of the power conversion system may be a dc side, where the power conversion system is a dc conversion system and the power converter in the power conversion system is a dc converter; the first side of the power conversion system may also be an ac side, where the power conversion system is an ACDC conversion system and the power converter is an ACDC converter; in practical applications, including but not limited to, the present application is not limited to, and can be applied to the protection scope of the present application as the case may be.
If the first side of the power conversion system is a direct current side, namely the power conversion system is a direct current conversion system, in the power conversion system, a first side bus capacitor is connected between two poles of the first side of the power converter; the second side bus capacitor is connected between two poles of the second side of the power converter; the first side main switch may be provided in: the positive electrode of the first side of the power converter is connected with the positive electrode of the first side of the power conversion system, or the negative electrode of the first side of the power converter is connected with the negative electrode of the first side of the power conversion system; the second side main switch is arranged on: the positive electrode of the second side of the power converter and the positive electrode of the second side of the power conversion system, or the negative electrode of the second side of the power converter and the negative electrode of the second side of the power conversion system.
The specific flow of the main switch short circuit detection method of the rate conversion system is shown in fig. 1, and specifically comprises the following steps:
s110, judging whether all the first side main switches in the power conversion system have no short circuit fault.
If all the first side main switches have no short circuit fault, sequentially executing the steps S120 and S130; and stopping executing the main switch short circuit detection method of the power conversion system if at least one first side main switch has short circuit fault.
Optionally, the first side main switch may be a mechanical switch such as a contactor or a circuit breaker, or may be an electronic switch such as a MOS transistor or an IGBT, which is not specifically limited herein, and may be within the protection scope of the present application as the case may be.
It should be noted that when the power conversion system is a dc conversion system, the first side main switch may be a mechanical switch or an electronic switch; when the power conversion system is an ACDC conversion system, the first side main switch may be only a mechanical switch.
In practical application, if the first side main switch is a mechanical switch, the short-circuit fault of the first side main switch is usually caused by adhesion of contacts in the mechanical switch; if the first side main switch is an electronic switch, a short-circuit fault of the first side main switch is usually caused by the damage of a PN junction in the electronic switch.
S120, charging a second side bus capacitor in the power conversion system by using a first side voltage of the power conversion system and a power converter in the power conversion system.
In practical application, the specific implementation manner of step S120 is as follows: all the first side main switches are closed, and the power converter is controlled to perform power conversion, namely, the first side voltage is converted into corresponding voltage through the power conversion, and the second side bus capacitor is charged; specifically, when the power conversion system is a dc conversion system, that is, when the power converter is a dc converter, the second-side bus capacitor is charged by chopping.
In a specific example, the second side voltage of the power conversion system is equal to zero before starting, that is, the power converter is used as a voltage source, and the voltages at two ends of the second side bus capacitor after being charged are charged to a first preset value, wherein the first preset value is smaller than or equal to the set voltage value of the second side bus capacitor; if the power conversion system is a dc conversion system, the operation mode of the power conversion system is a constant bus voltage operation mode.
The set voltage value of the second side bus capacitor is preset according to actual requirements, and is not specifically limited herein, and is within the protection scope of the application.
It should be noted that, in general, after determining that all the second side main switches have no short-circuit fault, the power conversion system will perform grid-connected operation, so in order to enable direct grid-connected operation subsequently, in practical application, a lower limit value is set for the voltages at two ends of the second side busbar capacitor after charging, and the lower limit value is set according to the practical grid-connected requirement, which is not limited specifically herein.
In another specific example, the second side voltage of the power conversion system is not equal to zero before starting, that is, the power converter is used as a current source, and the two-end voltage of the second side bus capacitor after being charged is charged to a second preset value, wherein the difference value of the second side voltage of the power conversion system minus the second preset value is less than or equal to the first preset overvoltage; if the power conversion system is a dc conversion system, the operation mode of the power conversion system is a constant current operation mode or a constant power operation mode.
The first preset overvoltage is determined according to the actual working requirement of the second side main switch and the impact capability range which can be born by the second side bus capacitor, so that the second side main switch is prevented from generating larger impact during closing, namely the second side main switch and the second side bus capacitor are prevented from being damaged, and the second side main switch and the second side bus capacitor are not particularly limited and are all in the protection range of the application.
And S130, after the charging is completed, short-circuit fault detection is carried out on each second side main switch in a divided manner.
For example, assuming that the power conversion system includes two second-side main switches, which are respectively denoted as an anode second-side main switch and a cathode second-side main switch, short-circuit fault detection is performed on each second-side main switch in a number of times, specifically: short-circuit fault detection is carried out on the positive electrode second side main switch for the first time, and short-circuit fault detection is carried out on the negative electrode second side main switch for the second time.
At this time, in one example, as shown in fig. 2, step S130 includes the following steps;
s131, short-circuit fault detection is conducted on the positive electrode second side main switch.
And S132, detecting a short-circuit fault of the main switch at the second side of the negative electrode.
Optionally, the second side main switch may be a mechanical switch such as a contactor or a circuit breaker, or may be an electronic switch such as a MOS transistor or an IGBT, which is not specifically limited herein, and may be within the protection scope of the present application as the case may be.
In practical applications, if the second side main switch is a mechanical switch, the short-circuit fault of the second side main switch is usually caused by adhesion of contacts in the mechanical switch; if the second side main switch is an electronic switch, a short circuit fault of the second side main switch is usually caused by the broken PN junction in the electronic switch.
When all the first side main switches in the power conversion system do not have short-circuit faults, the power converter in the power conversion system is utilized to charge the second side bus capacitor in the power conversion system, so that the second bus capacitor can be charged when the second side voltage of the power conversion system is equal to zero, the condition that the voltages at two ends of the second bus capacitor are consistent with the second side voltage all the time is avoided, and misjudgment in the process of short-circuit fault detection of the second side main switch is avoided; the power conversion system can also be a direct current conversion system, and the second side main switch can also be a contactor, so that the main switch short circuit detection method of the power conversion system can avoid misjudgment in the process of carrying out adhesion fault detection on the contactor at one side of the direct current conversion system when the voltage at the other side of the direct current conversion system is equal to zero.
Another embodiment of the present application provides a specific implementation manner of short-circuit fault detection for a second side main switch, as shown in fig. 3 (fig. 3 only shows an example of short-circuit fault detection for a second side main switch), which specifically includes the following steps:
s210, controlling each second side main switch to enable the second side main switch to be detected to be in an off state and enable the rest second side main switches to be in an on state.
For example, assume that the power conversion system includes two second-side main switches, which are respectively denoted as an anode second-side main switch and a cathode second-side main switch, and short-circuit fault detection is performed on the anode second-side main switch, where the anode second-side main switch is the second-side main switch to be detected.
In practical application, the main switch short-circuit detection method is performed before the power conversion system is started, so that if the short-circuit fault detection performed at the moment is the first time, before the short-circuit fault detection is performed, each second side main switch is in a default state, namely an off state; if the short-circuit fault detection is not the first time, the second side main switches are in the on state except the second side main switch to be detected last time before the short-circuit fault detection.
In a specific example, the short-circuit fault detection performed at this time is the first time, if the number of the second side main switches included in the power conversion system is greater than 1, the second side main switches to be detected are kept in a current state by controlling the second side main switches to be detected, and the rest of the second side main switches are controlled to be closed, so that the second side main switches to be detected can be in an off state, and the rest of the second side main switches can be in an on state; if the number of the second side main switches included in the power conversion system is equal to 1, the second side main switches to be detected can be in an off state and the rest second side main switches can be in an on state by controlling the second side main switches to be detected to keep the current state.
In a specific example, the short-circuit fault detection performed at this time is not the first time, and the number of the second side main switches included in the power conversion system is greater than 1, and the second side main switches to be detected can be in an off state and the rest of the second side main switches are in an on state by controlling the second side main switches to be detected to be off, controlling the second side main switches to be detected last time to be on, and controlling other second side main switches to be in a current state.
S220, judging whether the voltage of two ends of the second side bus capacitor after being charged is equal to the second side voltage of the power conversion system.
If the voltage of the two ends of the second side bus capacitor after being charged is equal to the voltage of the second side of the power conversion system, executing step S230; if the voltage at the two ends of the second side bus capacitor after charging is not equal to the voltage at the second side of the power conversion system, step S240 is performed.
S230, judging that the second side main switch to be detected has a short-circuit fault.
S240, judging that the to-be-detected second side main switch has no short circuit fault.
In this embodiment, since the voltage across the second-side bus capacitor after the step S210 is performed is not equal to the second-side voltage of the power conversion system, if the voltage across the second-side bus capacitor after the charging is equal to the second-side voltage of the power conversion system, it may be determined that the second-side main switch to be detected has a short-circuit fault, and thus this embodiment may implement the short-circuit fault detection of the second-side main switch to be detected.
The present application provides a specific implementation manner of step S110, which is applicable to a case where the first side of the power conversion system is a dc side and each of the first side main switches is connected in parallel with a slow start circuit, that is, to a case where the power conversion system is a dc conversion system and each of the first side main switches is connected in parallel with a slow start circuit; the specific flow of this embodiment can be seen in fig. 4 (only shown on the basis of fig. 1), and specifically includes the following steps:
s310, charging a first side bus capacitor in the power conversion system by using the first side voltage of the power conversion system and all the slow start circuits.
The voltage at two ends of the first side bus capacitor is charged to a third preset value; the difference value of the first side voltage minus the third preset value of the power conversion system is smaller than or equal to the second preset overvoltage.
In addition, the second preset overvoltage is determined according to the actual working requirement of the first side main switch and the impact capability range that the first side bus capacitor can bear, so that the first side main switch is prevented from generating larger impact during closing, namely, the first side main switch and the first side bus capacitor are prevented from being damaged, and the second preset overvoltage is not specifically limited and is in the protection range of the application.
S320, after the charging is completed, short-circuit fault detection is carried out on each first side main switch in a divided manner, and corresponding detection results are obtained.
The embodiment also provides a specific implementation manner of detecting a short-circuit fault of a first side main switch and obtaining a corresponding detection result, where a specific flow of this implementation manner may be referred to fig. 5 (fig. 5 is only based on fig. 4, and shows an example of detecting a short-circuit fault of a first side main switch), and specifically includes the following steps:
s410, controlling each first side main switch to enable the first side main switch to be detected to be in an off state and enabling the rest first side main switches to be in an on state.
For example, assume that the power conversion system includes two first side main switches, which are respectively denoted as a positive first side main switch and a negative first side main switch, and short-circuit fault detection is performed on the positive first side main switch, then the positive first side main switch is the first side main switch to be detected.
It should be noted that, the first side main switch to be detected is in an off state, and the other first side main switches are in an on state, which are the same as the second side main switch to be detected is in an off state, and the other second side main switches are in an on state, which are not described herein.
S420, judging whether the first side voltage of the power conversion system is equal to the voltage of two ends of the charged first side bus capacitor.
If the voltage at the first side of the power conversion system is not equal to the voltage at the two ends of the charged first side bus capacitor, executing step S430; if the first side voltage of the power conversion system is equal to the voltage between the two ends of the charged first side bus capacitor, step S440 is performed.
And S430, the corresponding detection result is that the main switch at the first side to be detected has no short circuit fault.
S440, the corresponding detection result is that the first side main switch to be detected has a short circuit fault.
In this embodiment, since the first side voltage of the power conversion system is not equal to the voltage across the charged first side bus capacitor after step S410 is performed, when the first side voltage of the power conversion system is equal to the voltage across the charged first side bus capacitor, it may be determined that the short-circuit fault occurs in the first side main switch to be detected, thereby implementing the short-circuit fault detection on the first side main switch.
S330, after all the first side main switches are subjected to short-circuit fault detection, judging whether each detection result is that the first side main switch to be detected has no short-circuit fault.
If each detection result is that the short-circuit fault does not occur in the first side main switch to be detected, executing step S120; and if the detected result is that the short-circuit fault does not occur in the main switch at the first side to be detected, stopping executing the main switch short-circuit detection method.
The foregoing is only one specific embodiment of step S110, and in practical applications, including but not limited to this, the present invention is not limited thereto, and the present invention is applicable to any case.
The present application provides a power conversion system, the second side of the power conversion system is a dc side, and the specific structure of the power conversion system may be seen in fig. 6, which specifically includes: a controller (the controller is not shown in fig. 6 or 7 for simplicity of the drawing), a power converter 10, a first side bus capacitor 20, a second side bus capacitor 30, at least one first side main switch S1 (only two first side main switches S1 are shown in fig. 6 as an example), at least one second side main switch S2 (only two second side main switches S2 are shown in fig. 6 as an example), and at least one slow start circuit 40 (only two slow start circuits 40 are shown in fig. 6 as an example).
The first side of the power conversion system is connected with a power supply, and the second side of the power conversion system is a direct current side; in practical application, the power supply can be a direct current power supply or an alternating current power supply, and is not particularly limited herein, and can be determined according to specific conditions; however, the type of the power supply is matched with the type of the first side, for example, if the first side is a dc side, the power supply is a dc power supply.
Alternatively, the first side of the power conversion system may be a dc side, where the power conversion system is a dc conversion system and the power converter 10 in the power conversion system is a dc converter; the first side of the power conversion system may also be an ac side, where the power conversion system is an ACDC conversion system and the power converter 10 is an ACDC converter; in practical applications, including but not limited to, the present application is not limited to, and can be applied to the protection scope of the present application as the case may be.
Optionally, the first side main switch S1 may be a mechanical switch such as a contactor or a circuit breaker, or may be an electronic switch such as a MOS transistor or an IGBT, which is not specifically limited herein, and may be within the protection scope of the present application as the case may be.
It should be noted that, when the power conversion system is a dc conversion system, the first side main switch S1 may be a mechanical switch or an electronic switch; when the power conversion system is an ACDC conversion system, the first side main switch S1 may be only a mechanical switch.
Optionally, the second side main switch S2 may be a mechanical switch such as a contactor or a circuit breaker, or may be an electronic switch such as a MOS transistor or an IGBT, which is not specifically limited herein, and may be within the protection scope of the present application as the case may be.
Wherein, the first side bus capacitor 20 and the second side bus capacitor 30 each comprise: one capacitor, or at least two capacitors connected in series; the method is not particularly limited, and the method can be used for protecting the application as the case may be; in practical applications, it is preferable that the first side bus capacitor 20 and the second side bus capacitor 30 each include two serially connected capacitors, such as the capacitors C1 and C2 in fig. 6.
The slow start circuit 40 may be a slow start circuit in the prior art, for example, as shown in fig. 6, a structure formed by connecting a slow start resistor and a MOS transistor in series is adopted, and in the prior art, various implementation manners of the slow start circuit are provided, which are not described in detail herein.
The connection relationship between the devices is specifically as follows:
the first side bus capacitor 20 is connected between the two poles of the first side of the power converter 10; the second side bus capacitor 30 is connected between the two poles of the second side of the power converter 10.
A first side of the power converter 10 is connected to a first side of the power conversion system and a second side of the power converter 10 is connected to a second side of the power conversion system.
The first side main switch S1 may be provided at: between a first port on a first side of the power converter 10 and a first port on a first side of the power conversion system, or between a second port on a first side of the power converter 10 and a second port on a first side of the power conversion system.
If the first side of the power conversion system may be a dc side, the first port and the second port are positive and negative, respectively.
The second-side main switch S2 is provided in: the positive pole of the second side of the power converter 10 is between the positive pole of the second side of the power conversion system or the negative pole of the second side of the power converter 10 is between the negative pole of the second side of the power conversion system.
In practical application, the number of the first side main switches S1 and the number of the second side main switches S2 may be determined according to specific situations, and are not specifically limited herein, and are all within the protection scope of the present application; preferably, the number of the first side main switches S1 is equal to 2, and the number of the second side main switches S2 is equal to 2.
In a specific example, as shown in fig. 6, the number of the first side main switches S1 is equal to 2, and one first side main switch S1 is disposed between the positive electrode on the first side of the power converter 10 and the positive electrode on the first side of the power conversion system, and is denoted as a positive electrode first side main switch; the other first side main switch S1 is provided between the negative electrode of the first side of the power converter 10 and the negative electrode of the first side of the power conversion system, and is denoted as a negative electrode first side main switch.
In another specific example, as shown in fig. 6, the number of second side main switches S2 is equal to 2, and one second side main switch S2 is disposed between the positive electrode on the second side of the power converter 10 and the positive electrode on the second side of the power conversion system, and is denoted as a positive electrode second side main switch; the other second side main switch S2 is provided between the negative pole of the second side of the power converter 10 and the negative pole of the second side of the power conversion system, denoted as negative pole second side main switch.
Each of the slow start circuits 40 is connected across a corresponding one of the first side main switches S1.
In a specific example, as shown in fig. 7, two sides of the power conversion system are both dc sides and are connected with a power supply, and the two sides are respectively denoted as a side and B side, where the first side of the power conversion system is denoted as a side and the second side is denoted as B side, the a side is provided with two main switches denoted as SA, the B side is provided with two main switches denoted as SB, and two ends of each main switch SA are connected in parallel with a slow start circuit 40.
In another specific example, as shown in fig. 8, two sides of the power conversion system are both dc sides and are connected with a power supply, and the two sides are respectively denoted as a side and B side, wherein the first side of the power conversion system is the B side, the second side is the a side, the a side is provided with two main switches, denoted as SA, the B side is provided with two main switches, denoted as SB, and two ends of each main switch SB are connected in parallel with a slow start circuit 40.
In practical application, if the power conversion system is provided with a slow start circuit, the power conversion system is further provided with at least one fuse Fu, wherein the fuse Fu and the slow start circuit are arranged on the same side of the power conversion system; the specific connection relationship of the fuse Fu is as follows:
in a specific example, as shown in fig. 7, the power conversion system is provided with two fuses Fu, one fuse Fu being provided between the positive electrode of the a side of the power converter 10 and the positive electrode of the a side of the power conversion system, and the other fuse Fu being provided between the negative electrode of the a side of the power converter 10 and the negative electrode of the a side of the power conversion system.
In another specific example, as shown in fig. 8, the power conversion system is provided with two fuses Fu, one fuse Fu being provided between the positive electrode on the B side of the power converter 10 and the positive electrode on the B side of the power conversion system, and the other fuse Fu being provided between the negative electrode on the B side of the power converter 10 and the negative electrode on the B side of the power conversion system.
The power converter 10, all main switches, and all slow start circuits 40 are controlled by a controller for performing the main switch short circuit detection method as provided in the above embodiments.
It should be noted that, in practical applications, the controller may be independently provided or may be integrated in the power converter 10, which is not limited herein, and may be within the scope of the present application as appropriate.
In the prior art, a non-on-board circuit is required to connect the slow start circuit in parallel at two ends of a contactor at one side of the dc conversion system, but there is a possibility of misconnection of the non-on-board circuit, for example, it is assumed that in the dc conversion system, a positive contactor at the one side is disposed at: the negative electrode contactor of the side is arranged between the negative electrode of the side of the direct current conversion system and the negative electrode of the side of the direct current conversion converter in the direct current conversion system, one end of the positive electrode slow starting circuit is connected with the positive electrode of the side of the direct current conversion converter, the other end of the positive electrode slow starting circuit is connected with the negative electrode of the side of the direct current conversion converter, and one end of the negative electrode slow starting circuit is connected with the negative electrode of the side of the direct current conversion converter; when the misconnection occurs, if the short-circuit fault detection method in the prior art is used for detecting the short-circuit fault of the two contactors at the side, the side voltage can be directly applied to the two ends of the slow start circuit, so that the slow start resistor in the slow start circuit is overheated, the PCB circuit board is scrapped, and large loss is caused.
In the power conversion system provided by the application, if the slow start circuit is arranged on the first side of the power conversion system, the problem of misconnection of the off-board circuit can be solved, so that economic loss is reduced, and the overall cost of the power conversion system is optimized, so that the slow start circuit is arranged on the first side of the power conversion system as a preferred embodiment.
The features described in the various embodiments of the present disclosure may be interchanged or combined with each other in the above description of the disclosed embodiments to enable those skilled in the art to make or use the present application. The above description is only of the preferred embodiment of the present invention, and is not intended to limit the present invention in any way. While the invention has been described with reference to preferred embodiments, it is not intended to be limiting. Any person skilled in the art can make many possible variations and modifications to the technical solution of the present invention or modifications to equivalent embodiments using the methods and technical contents disclosed above, without departing from the scope of the technical solution of the present invention. Therefore, any simple modification, equivalent variation and modification of the above embodiments according to the technical substance of the present invention still fall within the scope of the technical solution of the present invention.
Claims (12)
1. A main switch short circuit detection method of a power conversion system is characterized in that a first side of the power conversion system is connected with a power supply, and a second side of the power conversion system is a direct current side; the main switch short circuit detection method comprises the following steps:
judging whether all first side main switches in the power conversion system have no short circuit fault;
if all the first side main switches do not have short-circuit faults, charging a second side bus capacitor in the power conversion system by using a first side voltage of the power conversion system and a power converter in the power conversion system;
and after the charging is completed, detecting the short-circuit fault of each second side main switch in a divided manner.
2. The method of claim 1, wherein short-circuit fault detection for one of the second side main switches comprises:
the second side main switches to be detected are in an off state and the rest second side main switches are in an on state through control of each second side main switch;
judging whether the voltage of two ends of the second side bus capacitor after being charged is equal to the second side voltage of the power conversion system;
and if the voltage of the two ends of the second side bus capacitor after being charged is equal to the second side voltage of the power conversion system, judging that the second side main switch to be detected has a short-circuit fault.
3. The method according to claim 1, wherein if the power converter is used as a voltage source, the voltage across the second side bus capacitor is charged to a first preset value, and the first preset value is less than or equal to a set voltage value of the second side bus capacitor.
4. The method according to claim 1, wherein if the power converter is used as a current source, the voltages at both ends of the second-side bus capacitor are charged to a second preset value; the difference between the second side voltage of the power conversion system minus the second preset value is less than or equal to a first preset overvoltage.
5. The method according to any one of claims 1 to 4, wherein charging a second side bus capacitor in the power conversion system with a power converter in the power conversion system, comprises:
and closing all the first side main switches, and controlling the power converter to perform power conversion.
6. The method according to any one of claims 1 to 4, wherein if the first side of the power conversion system is a dc side and each of the first side main switches is connected in parallel with a slow start circuit, determining whether all of the first side main switches in the power conversion system have no short circuit fault comprises:
charging a first side bus capacitor in the power conversion system by using the first side voltage of the power conversion system and all the slow start circuits;
after the charging is completed, short-circuit fault detection is carried out on each first side main switch in a divided manner, and a corresponding detection result is obtained;
and if each detection result is that the first side main switch to be detected has no short circuit fault, executing the step of charging the second side bus capacitor in the power conversion system by using the power converter in the power conversion system.
7. The method for detecting a short circuit of a main switch according to claim 6, wherein detecting a short circuit fault of one of the first side main switches and obtaining a corresponding detection result comprises:
the first side main switches to be detected are in an off state by controlling each first side main switch, and the rest first side main switches are in an on state;
judging whether the voltage of the first side of the power conversion system is equal to the voltage of two ends of the charged first side bus capacitor or not;
and if the voltage of the first side of the power conversion system is not equal to the voltage of the two ends of the charged first side bus capacitor, the corresponding detection result is that the first side main switch to be detected has no short circuit fault.
8. A power conversion system, comprising: the power converter comprises a controller, a power converter, a first side bus capacitor, a second side bus capacitor, at least one first side main switch and at least one second side main switch; wherein:
the first side bus capacitor is connected between two poles of the first side of the power converter;
the second side bus capacitor is connected between two poles of the second side of the power converter;
a first side of the power converter is connected to a first side of the power conversion system, and a second side of the power converter is connected to a second side of the power conversion system;
the first side main switch is arranged on: a first port of the first side of the power converter and a first port of the first side of the power conversion system or a second port of the first side of the power converter and a second port of the first side of the power conversion system;
the second side main switch is arranged on: a positive electrode of the second side of the power converter and a positive electrode of the second side of the power conversion system, or a negative electrode of the second side of the power converter and a negative electrode of the second side of the power conversion system;
the power converter, all main switches being controlled by the controller for performing the main switch short circuit detection method according to any one of claims 1 to 7.
9. The power conversion system of claim 8, wherein the first side of the power conversion system is a direct current side or an alternating current side.
10. The power conversion system of claim 9, wherein if the first side of the power conversion system is a dc side, the power conversion system further comprises: at least one slow start circuit; wherein:
each slow start circuit is connected with: two ends of a corresponding first side main switch;
all the slow start circuits are controlled by the controller.
11. The power conversion system according to claim 9, wherein if the first side of the power conversion system is a dc side, the first side main switch is a circuit breaker, a contactor, a MOS transistor, or an IGBT;
if the first side of the power conversion system is an ac side, the first side main switch is a circuit breaker or contactor.
12. The power conversion system according to any one of claims 8 to 11, wherein the second side main switch is a circuit breaker, a contactor, a MOS transistor, or an IGBT.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202310034691.6A CN116203409A (en) | 2023-01-10 | 2023-01-10 | Power conversion system and main switch short circuit detection method thereof |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202310034691.6A CN116203409A (en) | 2023-01-10 | 2023-01-10 | Power conversion system and main switch short circuit detection method thereof |
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| Publication Number | Publication Date |
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| CN116203409A true CN116203409A (en) | 2023-06-02 |
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| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202310034691.6A Pending CN116203409A (en) | 2023-01-10 | 2023-01-10 | Power conversion system and main switch short circuit detection method thereof |
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| Country | Link |
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| CN (1) | CN116203409A (en) |
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2023
- 2023-01-10 CN CN202310034691.6A patent/CN116203409A/en active Pending
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