CN111669038A - Bus capacitor pre-charging circuit and method, frequency converter and air conditioning equipment - Google Patents
Bus capacitor pre-charging circuit and method, frequency converter and air conditioning equipment Download PDFInfo
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- CN111669038A CN111669038A CN202010543708.7A CN202010543708A CN111669038A CN 111669038 A CN111669038 A CN 111669038A CN 202010543708 A CN202010543708 A CN 202010543708A CN 111669038 A CN111669038 A CN 111669038A
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
- H02M1/00—Details of apparatus for conversion
- H02M1/32—Means for protecting converters other than automatic disconnection
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
- H02J7/00—Circuit arrangements for charging or depolarising batteries or for supplying loads from batteries
- H02J7/34—Parallel operation in networks using both storage and other dc sources, e.g. providing buffering
- H02J7/345—Parallel operation in networks using both storage and other dc sources, e.g. providing buffering using capacitors as storage or buffering devices
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
- H02M7/00—Conversion of ac power input into dc power output; Conversion of dc power input into ac power output
- H02M7/02—Conversion of ac power input into dc power output without possibility of reversal
- H02M7/04—Conversion of ac power input into dc power output without possibility of reversal by static converters
- H02M7/12—Conversion of ac power input into dc power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode
- H02M7/145—Conversion of ac power input into dc power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a thyratron or thyristor type requiring extinguishing means
- H02M7/155—Conversion of ac power input into dc power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a thyratron or thyristor type requiring extinguishing means using semiconductor devices only
- H02M7/1555—Conversion of ac power input into dc power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a thyratron or thyristor type requiring extinguishing means using semiconductor devices only with control circuit
- H02M7/1557—Conversion of ac power input into dc power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a thyratron or thyristor type requiring extinguishing means using semiconductor devices only with control circuit with automatic control of the output voltage or current
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Abstract
The invention discloses a bus capacitor pre-charging circuit and method, a frequency converter and air conditioning equipment. Wherein, this circuit includes: the input end of the charging module is connected with an alternating current power supply, and the output end of the charging module is connected with the direct current bus and used for outputting variable current; and the input end of the controller is connected with the direct current bus, and the output end of the controller is connected with the charging module and used for adjusting the current output by the charging module according to the voltage of the direct current bus. According to the invention, the charging current can be flexibly adjusted, the condition that the cement resistor is burnt due to overlarge current caused by the fact that direct current voltage is completely applied to two ends of the cement resistor at the moment of electrifying is avoided, and the safety is improved.
Description
Technical Field
The invention relates to the technical field of electronic power, in particular to a bus capacitor pre-charging circuit and method, a frequency converter and air conditioning equipment.
Background
The traditional air conditioner pre-charging circuit is formed by connecting a relay and a cement resistor in a main loop in parallel. When the frequency converter is powered on, the relay is disconnected, the three-phase alternating current input is rectified by the rectifying module and then charges the capacitor through the cement resistor, and when the bus voltage reaches a set value, the relay is controlled to be closed, so that the cement resistor is short-circuited, and the pre-charging of the capacitor is completed. The mode has the advantages of low charging efficiency and complex operation, and more importantly, the current is high at the moment of starting charging, so that the cement resistor can be damaged, and the safe operation of the frequency converter is influenced.
Aiming at the problems that the charging instantaneous current is large and the charging resistor is impacted in the prior art, an effective solution is not provided at present.
Disclosure of Invention
The embodiment of the invention provides a bus capacitor pre-charging circuit and method, a frequency converter and air conditioning equipment, and aims to solve the problem that in the prior art, the charging instantaneous current is large and impact is generated on the circuit.
In order to solve the above technical problem, the present invention provides a bus capacitor pre-charging circuit, wherein the number of the bus capacitors is at least two, and the bus capacitors are connected in series and then connected between direct current buses, wherein two ends of each bus capacitor are connected in parallel with a voltage-sharing resistor, and the circuit comprises:
the input end of the charging module is connected with an alternating current power supply, and the output end of the charging module is connected with the direct current bus and used for outputting variable current;
and the input end of the controller is connected with the direct current bus, and the output end of the controller is connected with the charging module and used for adjusting the current output by the charging module according to the voltage of the direct current bus.
Further, the charging module comprises three charging units arranged in parallel: first charging unit, second charging unit and third charging unit, first charging unit the second charging unit and the third charging unit connects gradually respectively alternating current power supply's first phase line, second phase line and third phase line.
Further, in the first charging unit, the second charging unit and the third charging unit, each charging unit includes a thyristor and a diode connected in series in the same direction, and the first phase line of the ac power supply is connected between the thyristor and the diode in the first charging unit; a second phase line of the alternating current power supply is connected between a thyristor and a diode in the second charging unit; and a third phase line of the alternating current power supply is respectively connected between a thyristor and a diode in the third charging unit.
Further, the controller is specifically configured to control the firing angle of the thyristor to decrease, so that the output current of the charging module increases; or controlling the trigger angle of the thyristor to be unchanged, so that the output current of the charging module is unchanged;
wherein the difference of the firing angles between any two thyristors is always kept at 120 degrees, and the maximum variation value of the firing angle of each thyristor is 180 degrees.
Further, each charging unit further includes:
and the current limiting resistor is connected with the thyristor and the diode in series.
Further, each charging unit further includes:
and the indicating element is connected with the thyristor and the diode in series and is used for indicating whether the charging unit works normally or not.
Further, the circuit further comprises:
the input end of the current detection unit is connected between the charging module and the direct current bus, and the output end of the current detection unit is connected with the controller, is used for detecting the current output by the charging module and transmits the current to the controller;
the controller is further configured to control the charging module to be turned on or off according to the magnitude of the current output by the charging module.
The invention also provides a frequency converter which comprises the bus capacitor pre-charging circuit.
The invention also provides air conditioning equipment comprising the frequency converter.
The invention also provides a bus capacitor pre-charging method based on the bus capacitor pre-charging circuit, which comprises the following steps:
after the charging module is controlled to be conducted, acquiring direct-current bus voltage;
and adjusting the output current of the charging module according to the voltage of the direct current bus.
Further, adjusting the output current of the charging module according to the dc bus voltage includes:
judging whether the voltage of the direct current bus reaches a preset voltage threshold value;
if yes, controlling the output current of the charging module to be unchanged;
and if not, controlling the output current of the charging module to increase.
Further, controlling the output current of the charging module to be constant comprises: controlling the trigger angles of thyristors in the first charging unit, the second charging unit and the third charging unit to be unchanged;
controlling an output current of the charging module to increase, comprising: controlling the trigger angles of thyristors in the first charging unit, the second charging unit and the third charging unit to be reduced;
wherein the difference of the firing angles between any two thyristors is always kept at 120 degrees, and the maximum variation value of the firing angle of each thyristor is 180 degrees.
Further, while the output current of the charging module is adjusted according to the dc bus voltage, the method further includes:
detecting an output current of the charging module;
judging whether the output current is larger than a preset current threshold value or not;
if yes, controlling the charging module to be closed;
if not, controlling the charging module to be continuously conducted.
The present invention also provides a computer-readable storage medium having stored thereon a computer program which, when executed by a processor, implements the bus capacitor precharge method described above.
By applying the technical scheme of the invention, the charging module outputs the changed current, and the controller adjusts the current output by the charging module according to the voltage of the direct current bus, so that the flexible adjustment of the charging current can be realized, the condition that the cement resistor is burnt due to the fact that the direct current voltage is completely applied to two ends of the cement resistor at the moment of electrifying is avoided, and the safety is improved.
Drawings
FIG. 1 is a block diagram of a bus capacitor precharge circuit according to a first embodiment of the present invention;
FIG. 2 is a block diagram of a bus capacitor precharge circuit according to a second embodiment of the present invention;
FIG. 3 is a block diagram of a bus capacitor precharge circuit according to a third embodiment of the present invention;
FIG. 4 is a block diagram of a bus capacitor precharge circuit according to a fourth embodiment of the present invention;
FIG. 5 is a block diagram of a bus capacitor precharge circuit according to a fifth embodiment of the present invention;
FIG. 6 is a diagram illustrating the connection between a bus capacitor pre-charge circuit and a load circuit according to a sixth embodiment of the present invention;
FIG. 7 is a flowchart of a precharge method according to a ninth embodiment of the present invention;
fig. 8 is a flowchart of a bus capacitor pre-charging method according to a tenth embodiment of the invention.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention clearer, the present invention will be described in further detail with reference to the accompanying drawings, and it is apparent that the described embodiments are only a part of the embodiments of the present invention, not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
The terminology used in the embodiments of the invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. As used in the examples of the present invention and the appended claims, the singular forms "a", "an", and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise, and "a plurality" typically includes at least two.
It should be understood that the term "and/or" as used herein is merely one type of association that describes an associated object, meaning that three relationships may exist, e.g., a and/or B may mean: a exists alone, A and B exist simultaneously, and B exists alone. In addition, the character "/" herein generally indicates that the former and latter related objects are in an "or" relationship.
It should be understood that although the terms first, second, third, etc. may be used to describe the charging units in the embodiments of the present invention, the charging units should not be limited to these terms. These terms are only used to distinguish between charging units disposed at different locations. For example, the first charging unit may also be referred to as a second charging unit, and similarly, the second charging unit may also be referred to as a first charging unit, without departing from the scope of embodiments of the present invention.
The words "if", as used herein, may be interpreted as "at … …" or "at … …" or "in response to a determination" or "in response to a detection", depending on the context. Similarly, the phrases "if determined" or "if detected (a stated condition or event)" may be interpreted as "when determined" or "in response to a determination" or "when detected (a stated condition or event)" or "in response to a detection (a stated condition or event)", depending on the context.
It is also noted that the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that an 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 article or apparatus. Without further limitation, an element defined by the phrase "comprising an … …" does not exclude the presence of other like elements in the article or device in which the element is included.
Alternative embodiments of the present invention are described in detail below with reference to the accompanying drawings.
Example 1
In this embodiment, a first bus capacitor C1 and a second bus capacitor C2 are included between dc buses, the first bus capacitor C1 and the second bus capacitor C2 are connected in series and then connected between a first line and a second line of the dc buses, a first equalizing resistor R1 is connected in parallel to a first bus capacitor C1, a second equalizing resistor R2 is connected in parallel to two ends of a second bus capacitor C2, in order to charge the first bus capacitor C1 and the second bus capacitor C2, fig. 1 is a structural diagram of a bus capacitor precharge circuit according to a first embodiment of the present invention, as shown in fig. 1, the bus capacitor precharge circuit includes:
the charging module 10, the input end of the charging module 10 is connected with the alternating current power supply AC, the output end includes a first terminal and a second terminal, the first terminal and the second terminal are respectively connected with a first line and a second line of the direct current bus, and are used for outputting a variable current;
the charging device further comprises a controller 20, wherein the input end of the controller 20 is connected with the first line and the second line of the direct current bus, and the output end of the controller 20 is connected with the charging module 10 and used for adjusting the current output by the charging module 10 according to the voltage between the first line and the second line of the direct current bus.
The bus capacitor pre-charging circuit of this embodiment is through the current that the module output that charges changes to through the controller according to direct current bus voltage, adjust the current of the module output that charges can realize nimble regulation charging current, avoid because the power-on direct current voltage all adds at cement resistance both ends in the twinkling of an eye, lead to the too big condition of burning out of cement resistance current, promote the security.
Example 2
In this embodiment, another bus capacitor pre-charging circuit is provided, and fig. 2 is a structural diagram of a bus capacitor pre-charging circuit according to a second embodiment of the present invention, in order to realize the rectification of three-phase alternating current and simultaneously realize the charging of a dc bus capacitor, as shown in fig. 2, the charging module includes three charging units arranged in parallel: the first charging unit 101, the second charging unit 102 and the third charging unit 103 are respectively connected with the first phase line, the second phase line and the third phase line of the alternating current power supply in sequence, the three-phase alternating current rectification is realized through the first charging unit 101, the second charging unit 102 and the third charging unit 103, the current with variable size is output, and the bus capacitor is charged through the variable current.
Example 3
In this embodiment, another bus capacitor pre-charging circuit is provided, and fig. 3 is a structural diagram of a bus capacitor pre-charging circuit according to a third embodiment of the present invention, as shown in fig. 3, each of the first charging unit 101, the second charging unit 102, and the third charging unit 103 includes a thyristor and a diode connected in series in the same direction, and the first phase line of the AC power source AC is connected between the thyristor T1 and the diode D1 in the first charging unit 101; a second phase line of the alternating current power AC is connected between the thyristor T2 and the diode D2 in the second charging unit 102; the third phase line of the alternating current power AC is connected between the thyristor T3 and the diode D3 in the third charging unit 103. The output end of the controller 20 is respectively connected to the control end of the thyristor T1, the control end of the thyristor T2 and the control end of the thyristor T3 in sequence, and the controller 20 controls the trigger angles of the thyristors T1, T2 and T3 to decrease, so that the output current of the charging module 10 increases; alternatively, the output current of the charging module 10 is made constant by controlling the firing angles of the thyristors T1, T2, and T3 to be constant, thereby realizing the adjustment of the charging current. In the present embodiment, the difference of the firing angles between any two thyristors is always maintained at 120 °, the maximum variation value of the firing angle of each thyristor is 180 °, for example, the initial angles of the thyristors T1, T2 and T3 may be 180 °, -60 ° and 60 °, the final angles may be 0 °, 120 °, -120 °, the firing angles of the thyristors T1, T2 and T3 may be varied at the maximum by 180 °, and the output current is changed from the minimum value to the maximum value during the process of the change of the firing angles from the initial angles to the final angles.
Example 4
In order to limit the current flowing through each thyristor, as shown in fig. 4, the first charging unit 101, the second charging unit 102, and the third charging unit 103 respectively include a first current-limiting resistor R3, a second current-limiting resistor R4, and a third current-limiting resistor R5, wherein the first current-limiting resistor R3 is connected in series with the thyristor T1 and the diode D1, the second current-limiting resistor R4 is connected in series with the thyristor T2 and the diode D2, and the third current-limiting resistor R5 is connected in series with the thyristor T3 and the diode D3, and the current flowing through each thyristor is limited by the current-limiting resistor, so as to ensure the safe operation of the thyristor.
In addition, each charging unit may be failed and turned off, and in order to enable a user to intuitively know whether each charging unit is working normally and quickly locate the failure, the first charging unit 101, the second charging unit 102, and the third charging unit 103 respectively include: the first indication element D4, the second indication element D5 and the third indication element D6 are connected in series, wherein the first indication element D4 is connected in series with the thyristor T1 and the diode D1 to indicate whether the first charging unit 101 operates normally, the second indication element D5 is connected in series with the thyristor T2 and the diode D2 to indicate whether the second charging unit 102 operates normally, and the second indication element D6 is connected in series with the thyristor T3 and the diode D3 to indicate whether the third charging unit 103 operates normally, specifically, the first indication element D4, the second indication element D5 and the third indication element D6 are turned on and off simultaneously, and if one on and two off or one on and one off occurs, the circuit is determined to be in an abnormal state, so that the circuit can be powered off manually in time, and a safety accident can be avoided. The first indicator element D4, the second indicator element D5, and the third indicator element D6 may be light emitting diodes.
Example 5
In this embodiment, another bus capacitor pre-charging circuit is provided, and fig. 5 is a structural diagram of a bus capacitor pre-charging circuit according to a fifth embodiment of the present invention, in order to avoid a safety problem caused by an excessive charging current, as shown in fig. 5, the circuit further includes:
the input end of the current detection unit 30 is connected between the charging module 10 and the first line of the direct current bus, and the output end of the current detection unit 30 is connected with the controller 20, and is used for detecting the current output by the charging module and transmitting the current to the controller 20; the controller 20 controls the charging units in the charging module to be turned on or off according to the magnitude of the current output by the charging module, and further controls the whole charging module to be turned on or off, specifically, when the output current of the charging module is greater than a preset current threshold, each charging unit is controlled to be turned off to cut off the charging module, and circuit protection is realized when the charging current is too large.
Example 6
This embodiment provides another bus capacitor pre-charging circuit, and fig. 6 is a connection relationship diagram between a bus capacitor pre-charging circuit and a load circuit according to a sixth embodiment of the present invention, as shown in fig. 6, the bus capacitor pre-charging circuit includes: thyristors T1-T3, diodes D1-D3, thyristors T1-T3 and diodes D1-D3 jointly form a semi-controlled rectifying circuit in the three-phase pre-charging circuit, the trigger angle of the thyristors is controlled to gradually decrease from 180 degrees, when the trigger angle reaches 0 degree, the output current of the charging circuit reaches the maximum, and in the process of gradually decreasing the trigger angle of the thyristors, the thyristors T1-T3 are simultaneously conducted to charge the capacitors. C1 and C2 are charging capacitors, two ends of C1 and C2 and a load circuit formed by a resistor R and a switch Q form a closed loop, and D4 to D6 are light emitting diodes and used for indicating the working states of thyristors T1 to T3.
The working principle of the bus capacitor and the charging circuit of the embodiment is as follows:
by adopting the semi-controlled rectifying circuit, a cement resistor and a relay in a traditional circuit are replaced, and the semi-controlled rectifying circuit is used as a switch for controlling the charging circuit. After the frequency converter is electrified, under the condition of normal charging, the trigger angles of the three thyristors are controlled to be gradually reduced, wherein the thyristor T1 is decreased from 180 degrees to 0 degrees, the initial trigger angles of the thyristors T2, T3 and T1 are different, the difference value of the trigger angles of the three thyristors is kept at 120 degrees, when the trigger angle of the thyristor T1 is changed from 180 degrees to 0 degrees, the three thyristors are conducted and the trigger angles are gradually changed, so that the output current is gradually increased, the pre-charging of the bus capacitor is realized, the output voltage is uniformly increased along with the reduction of the trigger angle of the thyristor, the current is also increased along with the increase of the trigger angle, the control of the trigger angle can be flexibly adjusted, the main circuit is ensured not to generate overlarge charging current, the problem that the traditional pre-charging circuit is burnt due to the fact that the direct current voltage is completely applied to two ends of the cement resistor at the, when the trigger angle of the thyristor T1 reaches 0 degree, the trigger angles of the three thyristors reach the minimum and the output current reaches the maximum at the same time, in the process of changing the trigger angle, whether the pre-charging of the bus capacitor is finished or not is detected in real time, if the pre-charging of the bus capacitor is finished, the trigger angle is controlled not to change any more, if the pre-charging of the bus capacitor is not finished, the trigger angle is controlled to continuously reduce until the pre-charging is reduced to the minimum, after the output current is the maximum, if the charging is not finished, the charging is kept by taking the maximum output current as the bus current.
In order to meet the working condition of the driving plate, a bus voltage threshold value is set, whether the circuit meets the working condition is judged by judging whether the voltage reaches the voltage threshold value, when the bus voltage does not reach the voltage threshold value, the trigger angle of the thyristor is continuously reduced until the bus voltage reaches the voltage threshold value, and if the trigger angle is reduced by 180 degrees, the bus voltage does not reach the voltage threshold value, and the trigger angle of the thyristor is controlled not to change.
The precharge circuit of the present embodiment further includes: and the current sampling unit is used for sampling the current value in the charging process, comparing the sampling result with a preset protection current threshold value, immediately disconnecting the thyristor to protect the rear-end circuit when the sampling current is greater than the preset protection current threshold value, and continuously keeping the thyristor on if the sampling current is less than or equal to the preset protection current value.
In practice, when a frequency converter works abnormally, when a circuit passes through a large current, heating components such as cement resistors and the like are easily damaged, and even the circuit can explode a plate when the circuit is serious, potential safety hazards exist, and factors causing the circuit to generate the large current are roughly two, namely, a rear end circuit has short circuit of the components, so that the circuit generates the large current in a straight-through mode; and the other is that the switch element is damaged and the switch cannot be normally controlled to be closed. Therefore, the front end of each branch of the semi-controlled rectifying circuit is provided with the light emitting diode, whether the thyristor normally works is judged according to the on-off condition of the light emitting diode, when the thyristor normally works, the three diodes should have the same on-off phenomenon, if the on-off or the on-off condition appears in a staggered mode, the circuit is judged to be in an abnormal state, if the circuit is found to be in the abnormal state, the circuit is timely powered off manually, and safety accidents are avoided.
The bus capacitor pre-charging circuit of the embodiment adopts the semi-controlled rectifying device, so that cement resistors and relays used in the traditional circuit are saved, the hardware structure is simplified, the problems that the charging time is adjusted by replacing RC resistors in the traditional circuit and the operation is complex are solved, the charging time can be flexibly changed, and the problem that the charging efficiency of the traditional pre-charging circuit is low is solved; the control of the charging current is realized by controlling the change speed of the trigger angle through software, so that the problem that components are burnt out due to large charging current caused by the fact that direct current voltage is completely applied to two ends of a cement resistor at the moment of electrifying in the traditional pre-charging circuit is solved; the on-off of the thyristor is controlled by comparing the sampling current with the set current, so that the phenomenon that the cement resistor is damaged due to overlarge current impact at the moment of electrifying to influence the safe operation of the frequency converter is avoided; whether the thyristor is damaged or not is indicated through the light emitting diode, and faults can be found in time.
Example 7
The embodiment provides a frequency converter, including the bus capacitor pre-charging circuit in the above-mentioned embodiment for realize accomplishing the charging to the bus capacitor through the change electric current, avoid appearing instantaneous heavy current, promote the security of frequency converter.
Example 8
The embodiment provides an air conditioning equipment, including the converter in the above-mentioned embodiment for realize accomplishing the charging to the bus capacitance through the change electric current, avoid appearing instantaneous heavy current, promote whole air conditioning equipment's security.
Example 9
This embodiment provides a bus capacitor pre-charging method implemented based on the bus capacitor pre-charging circuit described above, and fig. 7 is a flowchart of a pre-charging method according to a ninth embodiment of the present invention, as shown in fig. 7, the method includes:
s101, after the charging module is controlled to be conducted, acquiring direct current bus voltage; and S102, adjusting the output current of the charging module according to the voltage of the direct current bus. Specifically, step S102 includes: judging whether the voltage of the direct current bus reaches a preset voltage threshold value; if yes, controlling the output current of the charging module to be unchanged; and if not, controlling the output current of the charging module to increase.
Since the output current of the charging module can be changed by changing the trigger angle of the thyristor, in this embodiment, controlling the output current of the charging module to be unchanged specifically includes: controlling the trigger angles of thyristors in the first charging unit, the second charging unit and the third charging unit to be unchanged; and controlling the output current of the charging module to increase, specifically comprising: and controlling the trigger angles of the thyristors in the first charging unit, the second charging unit and the third charging unit to be reduced. The difference of the firing angles between any two thyristors is always kept at 120 degrees, the maximum change value of the firing angle of each thyristor is 180 degrees, for example, the initial angles of the thyristors T1, T2 and T3 can be respectively 180 degrees, -60 degrees and 60 degrees, the final angles can be respectively 0 degrees and 120 degrees and-120 degrees, the firing angles of the thyristors T1, T2 and T3 can be changed by 180 degrees at most, and the output current is changed from the minimum value to the maximum value in the process of changing the firing angles from the initial angles to the final angles.
In addition, in order to avoid the charging current too big, lead to the security problem, when adjusting the output current of the module of charging according to direct current bus voltage, still include: detecting an output current of the charging module; judging whether the output current is larger than a preset current threshold value or not; if yes, controlling the charging module to be closed; if not, controlling the charging module to be continuously conducted, and determining the specific trigger angle according to the direct current bus voltage judgment result.
According to the bus capacitor pre-charging method, the current output by the charging module is adjusted according to the direct current bus voltage, the charging current can be flexibly adjusted, the situation that the cement resistor is burnt due to the fact that the direct current voltage is completely applied to the two ends of the cement resistor in the instant of power-on is avoided, and safety is improved.
Example 10
This embodiment provides another bus capacitor pre-charging method, and fig. 8 is a flowchart of a bus capacitor pre-charging method according to a tenth embodiment of the present invention, as shown in fig. 8, the method includes:
and S1, controlling the frequency converter to be electrified, and setting a bus voltage value and a protection current threshold value. And S2, controlling the thyristor to conduct at the initial trigger angle and starting to charge the direct current bus. Wherein, under the initial trigger angle, the output current of the pre-charging circuit is minimum. And S3, judging whether the bus voltage reaches a voltage threshold value, if not, executing the step S4, and if so, executing the step S5. And S4, controlling the trigger angle of the thyristor to be reduced, continuing to maintain the charging state, and then returning to the step S3. And S5, judging whether the charging current is larger than the protection current threshold value, if not, executing the step S6 and then returning to the step S3, and if so, executing the step S7. And S6, controlling the thyristor to keep conducting. And S7, controlling the thyristor to shut down after being turned off.
Example 11
The present embodiment provides a computer-readable storage medium on which a computer program is stored, which when executed by a processor implements the bus capacitor precharge method in the above-described embodiments.
The above-described circuit embodiments are only illustrative, and the units described as separate parts may or may not be physically separate, and parts displayed as units may or may not be physical units, may be located in one place, or may be distributed on a plurality of network units. Some or all of the modules may be selected according to actual needs to achieve the purpose of the solution of the present embodiment.
Through the above description of the embodiments, those skilled in the art will clearly understand that each embodiment can be implemented by software plus a necessary general hardware platform, and certainly can also be implemented by hardware. With this understanding in mind, the above-described technical solutions may be embodied in the form of a software product, which can be stored in a computer-readable storage medium such as ROM/RAM, magnetic disk, optical disk, etc., and includes instructions for causing a computer device (which may be a personal computer, a server, or a network device, etc.) to execute the methods described in the embodiments or some parts of the embodiments.
Finally, it should be noted that: the above examples are only intended to illustrate the technical solution of the present invention, but not to limit it; although the present invention has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some technical features may be equivalently replaced; and such modifications or substitutions do not depart from the spirit and scope of the corresponding technical solutions of the embodiments of the present invention.
Claims (14)
1. The utility model provides a bus capacitor is charging circuit in advance, bus capacitor's quantity is two at least, inserts between the direct current bus after establishing ties, wherein, a equalizer resistor is connected in parallel at every bus capacitor both ends, its characterized in that, the circuit includes:
the input end of the charging module is connected with an alternating current power supply, and the output end of the charging module is connected with the direct current bus and used for outputting variable current;
and the input end of the controller is connected with the direct current bus, and the output end of the controller is connected with the charging module and used for adjusting the current output by the charging module according to the voltage of the direct current bus.
2. The circuit of claim 1, wherein the charging module comprises three charging units arranged in parallel: first charging unit, second charging unit and third charging unit, first charging unit the second charging unit and the third charging unit connects gradually respectively alternating current power supply's first phase line, second phase line and third phase line.
3. The circuit of claim 2, wherein each of the first charging unit, the second charging unit, and the third charging unit comprises a thyristor and a diode connected in series in the same direction, and the first phase line of the ac power source is connected between the thyristor and the diode in the first charging unit; a second phase line of the alternating current power supply is connected between a thyristor and a diode in the second charging unit; and a third phase line of the alternating current power supply is respectively connected between a thyristor and a diode in the third charging unit.
4. The circuit of claim 3,
the controller is specifically configured to control a firing angle of the thyristor to decrease, so that an output current of the charging module increases; or controlling the trigger angle of the thyristor to be unchanged, so that the output current of the charging module is unchanged;
wherein the difference of the firing angles between any two thyristors is always kept at 120 degrees, and the maximum variation value of the firing angle of each thyristor is 180 degrees.
5. The circuit of claim 3, wherein each charging unit further comprises:
and the current limiting resistor is connected with the thyristor and the diode in series.
6. The circuit of claim 3, wherein each charging unit further comprises:
and the indicating element is connected with the thyristor and the diode in series and is used for indicating whether the charging unit works normally or not.
7. The circuit of claim 1, further comprising:
the input end of the current detection unit is connected between the charging module and the direct current bus, and the output end of the current detection unit is connected with the controller, is used for detecting the current output by the charging module and transmits the current to the controller;
the controller is further configured to control the charging module to be turned on or off according to the magnitude of the current output by the charging module.
8. A frequency converter, characterized in that it comprises a bus capacitor pre-charging circuit according to any of claims 1-7.
9. An air conditioning apparatus characterized by comprising the inverter of claim 8.
10. A bus capacitor pre-charging method implemented based on the bus capacitor pre-charging circuit of any one of claims 1-7, the method comprising:
after the charging module is controlled to be conducted, acquiring direct-current bus voltage;
and adjusting the output current of the charging module according to the voltage of the direct current bus.
11. The method of claim 10, wherein regulating the output current of the charging module based on the dc bus voltage comprises:
judging whether the voltage of the direct current bus reaches a preset voltage threshold value;
if yes, controlling the output current of the charging module to be unchanged;
and if not, controlling the output current of the charging module to increase.
12. The method of claim 11,
controlling the output current of the charging module to be constant, comprising: controlling the trigger angles of thyristors in the first charging unit, the second charging unit and the third charging unit to be unchanged;
controlling an output current of the charging module to increase, comprising: controlling the trigger angles of thyristors in the first charging unit, the second charging unit and the third charging unit to be reduced;
wherein the difference of the firing angles between any two thyristors is always kept at 120 degrees, and the maximum variation value of the firing angle of each thyristor is 180 degrees.
13. The method of claim 10, wherein while regulating the output current of the charging module based on the dc bus voltage, the method further comprises:
detecting an output current of the charging module;
judging whether the output current is larger than a preset current threshold value or not;
if yes, controlling the charging module to be closed;
if not, controlling the charging module to be continuously conducted.
14. A computer-readable storage medium, on which a computer program is stored, which, when being executed by a processor, carries out a bus capacitor pre-charging method according to any one of claims 10 to 13.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202010543708.7A CN111669038A (en) | 2020-06-15 | 2020-06-15 | Bus capacitor pre-charging circuit and method, frequency converter and air conditioning equipment |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202010543708.7A CN111669038A (en) | 2020-06-15 | 2020-06-15 | Bus capacitor pre-charging circuit and method, frequency converter and air conditioning equipment |
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| Publication Number | Publication Date |
|---|---|
| CN111669038A true CN111669038A (en) | 2020-09-15 |
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Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202010543708.7A Pending CN111669038A (en) | 2020-06-15 | 2020-06-15 | Bus capacitor pre-charging circuit and method, frequency converter and air conditioning equipment |
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| Country | Link |
|---|---|
| CN (1) | CN111669038A (en) |
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2020
- 2020-06-15 CN CN202010543708.7A patent/CN111669038A/en active Pending
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