CN113937734B - Inverter, control method and control device thereof - Google Patents
Inverter, control method and control device thereof Download PDFInfo
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- CN113937734B CN113937734B CN202111548461.9A CN202111548461A CN113937734B CN 113937734 B CN113937734 B CN 113937734B CN 202111548461 A CN202111548461 A CN 202111548461A CN 113937734 B CN113937734 B CN 113937734B
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
- H02H7/00—Emergency protective circuit arrangements specially adapted for specific types of electric machines or apparatus or for sectionalised protection of cable or line systems, and effecting automatic switching in the event of an undesired change from normal working conditions
- H02H7/10—Emergency protective circuit arrangements specially adapted for specific types of electric machines or apparatus or for sectionalised protection of cable or line systems, and effecting automatic switching in the event of an undesired change from normal working conditions for converters; for rectifiers
- H02H7/12—Emergency protective circuit arrangements specially adapted for specific types of electric machines or apparatus or for sectionalised protection of cable or line systems, and effecting automatic switching in the event of an undesired change from normal working conditions for converters; for rectifiers for static converters or rectifiers
- H02H7/122—Emergency protective circuit arrangements specially adapted for specific types of electric machines or apparatus or for sectionalised protection of cable or line systems, and effecting automatic switching in the event of an undesired change from normal working conditions for converters; for rectifiers for static converters or rectifiers for inverters, i.e. dc/ac converters
- H02H7/1227—Emergency protective circuit arrangements specially adapted for specific types of electric machines or apparatus or for sectionalised protection of cable or line systems, and effecting automatic switching in the event of an undesired change from normal working conditions for converters; for rectifiers for static converters or rectifiers for inverters, i.e. dc/ac converters responsive to abnormalities in the output circuit, e.g. short circuit
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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
- 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
- H02M7/42—Conversion of dc power input into ac power output without possibility of reversal
- H02M7/44—Conversion of dc power input into ac power output without possibility of reversal by static converters
- H02M7/48—Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode
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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
- H02M7/42—Conversion of dc power input into ac power output without possibility of reversal
- H02M7/44—Conversion of dc power input into ac power output without possibility of reversal by static converters
- H02M7/48—Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode
- H02M7/53—Conversion of dc power input into ac 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 triode or transistor type requiring continuous application of a control signal
- H02M7/537—Conversion of dc power input into ac 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 triode or transistor type requiring continuous application of a control signal using semiconductor devices only, e.g. single switched pulse inverters
- H02M7/539—Conversion of dc power input into ac 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 triode or transistor type requiring continuous application of a control signal using semiconductor devices only, e.g. single switched pulse inverters with automatic control of output wave form or frequency
- H02M7/5395—Conversion of dc power input into ac 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 triode or transistor type requiring continuous application of a control signal using semiconductor devices only, e.g. single switched pulse inverters with automatic control of output wave form or frequency by pulse-width modulation
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Abstract
The invention provides an inverter and a control method and a control device thereof, which relate to the technical field of electricity, and the method comprises the following steps: acquiring output current, output voltage and direct current bus voltage of an inverter; judging whether the output current is greater than or equal to an overcurrent protection threshold value; if yes, controlling the inverter to stop working; if not, further judging whether the output current is greater than or equal to the cycle-by-cycle current limiting threshold value; if yes, controlling the inverter to work in a cycle-by-cycle current limiting mode; and if not, adjusting the duty ratio of the PWM signal input to the inverter according to the output voltage, the direct current bus voltage and the output current. The invention adjusts the working mode of the inverter according to the working parameters of the inverter in real time, can limit the starting current when an impact load is accessed, prevents the inverter from being shut down due to overcurrent protection, further improves the loading capacity of the inverter, and simultaneously can lead the inverter to adapt to direct current buses with different dynamic response characteristics.
Description
Technical Field
The invention relates to the technical field of electricity, in particular to a control method of an inverter, a control device of the inverter and the inverter.
Background
The inverter has a wide application range, for example, in a power grid, in order to ensure that a load supplies power when power is cut off, an energy storage system is generally provided, and an energy storage power supply (a direct current power supply) is inverted by the inverter through a direct current conversion circuit to obtain alternating current and supply the alternating current to the load.
In the related art, in order to prevent the inverter from being damaged due to overcurrent during operation, the inverter is generally provided with an overcurrent protection circuit, however, when an impact load is connected, because a starting current is large, the overcurrent protection of the inverter is easily triggered, so that the inverter is shut down, and further the operational reliability of the load is affected.
Disclosure of Invention
The present invention is directed to solving the above problems, and a first object of the present invention is to provide a method for controlling an inverter, in which the operating mode of the inverter is adjusted in real time according to the output current, the output voltage, and the dc bus voltage of the inverter, so as to limit the starting current when an impact load is connected, prevent the inverter from being shut down due to overcurrent protection, further improve the loading capacity of the inverter, and make the inverter suitable for dc buses with different dynamic response characteristics.
A second object of the present invention is to provide a control device for an inverter.
A third object of the invention is to propose an inverter.
The technical scheme adopted by the invention is as follows:
an embodiment of the first aspect of the present invention provides a control method of an inverter, including the steps of: acquiring output current, output voltage and direct current bus voltage of the inverter; judging whether the output current is greater than or equal to an overcurrent protection threshold value; if the output current is greater than or equal to an overcurrent protection threshold value, controlling the inverter to stop working; if the output current is smaller than the overcurrent protection threshold, further judging whether the output current is larger than or equal to a cycle-by-cycle current limiting threshold, wherein the cycle-by-cycle current limiting threshold is smaller than the overcurrent protection threshold; if the output current is larger than or equal to the cycle-by-cycle current limiting threshold value, controlling the inverter to work in a cycle-by-cycle current limiting mode; and if the output current is smaller than the cycle-by-cycle current limiting threshold value, adjusting the duty ratio of a PWM (Pulse Width Modulation) signal input to the inverter according to the output voltage, the DC bus voltage and the output current.
The control method of the inverter proposed by the invention can also have the following additional technical characteristics:
according to an embodiment of the present invention, adjusting the duty ratio of the PWM signal input to the inverter according to the output voltage, the dc bus voltage, and the output current includes: acquiring a dynamic current limiting curve according to the direct current bus voltage; obtaining an output current set value according to the output voltage and the output voltage set value; and acquiring the duty ratio of the PWM signal input to the inverter according to the output current given value, the output current and the dynamic current limiting curve.
According to one embodiment of the present invention, the dynamic current limit curve is obtained according to the following formula:
wherein the content of the first and second substances,
in order to achieve a dynamic current limiting curve,
in order to limit the upper limit value of the current,
in order to limit the lower limit value of the current,V bus is a voltage of the direct-current bus,
is a first preset voltage, and is a second preset voltage,
is the second preset voltage, and is the second preset voltage,
is the third preset voltage, and is,
，
，
the current limit threshold is cycle by cycle.
According to an embodiment of the present invention, obtaining the given value of the output current according to the given value of the output voltage and the given value of the output voltage specifically includes: inputting the output voltage and the output voltage given value into a positive input end and a negative input end of a first adder respectively to obtain a difference value of the output voltage and the output voltage given value; and inputting the difference value of the output voltage and the output voltage given value into a first PID (Proportion Integration Differentiation) regulator to obtain an output current given value.
According to an embodiment of the present invention, obtaining a duty ratio of a PWM signal input to the inverter according to the output current set value, the output current, and the dynamic current limit curve includes: inputting the output current and the output current set value into a positive input end and a negative input end of a second adder respectively to obtain a difference value of the output current and the output current set value; and inputting the difference value of the output current and the output current given value and the dynamic current limiting curve into a second PID regulator to obtain the duty ratio of the PWM signal input to the inverter.
An embodiment of a second aspect of the present invention proposes a control device of an inverter, including: the first acquisition module is used for acquiring the output current, the output voltage and the direct-current bus voltage of the inverter; the control module is used for judging whether the output current is greater than or equal to an overcurrent protection threshold value or not, and if the output current is greater than or equal to the overcurrent protection threshold value, the control module controls the inverter to stop working; if the output current is smaller than the overcurrent protection threshold, the control module further judges whether the output current is larger than or equal to a cycle-by-cycle current limiting threshold, wherein the cycle-by-cycle current limiting threshold is smaller than the overcurrent protection threshold; if the output current is larger than or equal to the cycle-by-cycle current limiting threshold value, the control module controls the inverter to work in a cycle-by-cycle current limiting mode; and if the output current is smaller than the cycle-by-cycle current limiting threshold value, the control module adjusts the duty ratio of the PWM signal input to the inverter according to the output voltage, the direct-current bus voltage and the output current.
The control device for the inverter according to the present invention may further include the following additional features:
according to an embodiment of the present invention, the control module is specifically configured to: acquiring a dynamic current limiting curve according to the direct current bus voltage; obtaining an output current set value according to the output voltage and the output voltage set value; and acquiring the duty ratio of the PWM signal input to the inverter according to the output current given value, the output current and the dynamic current limiting curve.
According to one embodiment of the invention, the control module obtains the dynamic current limit curve according to the following formula:
wherein the content of the first and second substances,
in order to achieve a dynamic current limiting curve,
in order to limit the upper limit value of the current,
in order to limit the lower limit value of the current,V bus is a voltage of the direct-current bus,
is a first preset voltage, and is a second preset voltage,
is the second preset voltage, and is the second preset voltage,
is the third preset voltage, and is,
，
，
the current limit threshold is cycle by cycle.
According to an embodiment of the invention, the control module is further configured to: inputting the output voltage and the output voltage given value into a positive input end and a negative input end of a first adder respectively to obtain a difference value of the output voltage and the output voltage given value; inputting the difference value of the output voltage and the output voltage given value into a first PID regulator to obtain an output current given value; inputting the output current and the output current set value into a positive input end and a negative input end of a second adder respectively to obtain a difference value of the output current and the output current set value; and inputting the difference value of the output current and the output current given value and the dynamic current limiting curve into a second PID regulator to obtain the duty ratio of the PWM signal input to the inverter.
An embodiment of the third aspect of the invention proposes an inverter comprising a control device of the inverter according to the embodiment of the second aspect of the invention.
The invention has the beneficial effects that:
the invention adjusts the working mode of the inverter according to the output current, the output voltage and the DC bus voltage of the inverter in real time, can limit the starting current when an impact load is connected, prevents the inverter from being shut down due to overcurrent protection, further improves the loading capacity of the inverter, and simultaneously enables the inverter to adapt to DC buses with different dynamic response characteristics.
Drawings
Fig. 1 is a flowchart of a control method of an inverter according to an embodiment of the present invention;
fig. 2 is a schematic view of a control method of an inverter according to an embodiment of the present invention;
FIG. 3 is a schematic diagram of a dynamic current limit curve according to one embodiment of the present invention;
FIG. 4 is a schematic diagram of an acquisition of the duty cycle of an inverter according to one embodiment of the present invention;
fig. 5 is an experimental simulation diagram of a control method of an inverter according to an embodiment of the present invention;
fig. 6 is an experimental simulation diagram of a control method of an inverter according to another embodiment of the present invention;
fig. 7 is a block schematic diagram of a control apparatus of an inverter according to an embodiment of the present invention.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and 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.
Fig. 1 is a flowchart of a control method of an inverter according to an embodiment of the present invention, as shown in fig. 1, the method including the steps of:
s1, obtaining the output current of the inverterI ac Output voltage of the power supplyV ac DC bus voltageV bus 。
Specifically, as shown in fig. 2, an output end of the dc power supply is connected to a dc bus of the inverter, the inverter can convert dc power output by the dc power supply into ac power to output the ac power and supply power to a load, and one or more dc power supplies can be provided and are set according to an actual application scenario. The output voltage of the inverter can be obtained by arranging a voltage sampling circuit at the output end of the inverterV ac The DC bus end of the inverter is provided with a voltage sampling circuit to obtain the DC bus voltageV bus The output end of the inverter is provided with a current sampling circuit to obtain output currentI ac 。
S2, judging the output current I ac Whether or not toGreater than or equal to the overcurrent protection thresholdI limit_ocp . Wherein the overcurrent protection thresholdI limit_ocp The presetting can be carried out according to the actual situation.
S3, if the current is outputI ac Greater than or equal to the overcurrent protection thresholdI limit_ocp And controlling the inverter to stop working.
S4, if the current is outputI ac Less than the over-current protection thresholdI limit_ocp Then further judging the output currentI ac Whether greater than or equal to the cycle-by-cycle current limit thresholdI limit_cbc . Wherein the current limiting threshold is cycle by cycleI limit_cbc Less than the over-current protection thresholdI limit_ocp The presetting can be carried out according to the actual situation.
S5, if the current is outputI ac Greater than or equal to the cycle-by-cycle current limit thresholdI limit_cbc And controlling the inverter to work in a cycle-by-cycle current limiting mode.
The current limiting mode will sample the current (referred to as output current in the present invention) cycle by cycle, i.e. every cycleI ac ) And a reference value (in the present invention, the cycle-by-cycle current limit threshold value)I limit_cbc ) And comparing, if the sampling current reaches the reference value, closing the pulse of the current period, and waiting until the pulse is sent out again in the next period.
S6, if the current is outputI ac Less than cycle-by-cycle current limit thresholdI limit_cbc According to the output voltageV ac DC bus voltageV bus And output currentI ac The duty ratio of the PWM signal input to the inverter is adjusted.
Particularly, the related control function of the inverter can be realized through a microcontroller and a driver, the driver can realize the driving of the inverter, and the output current collected by the current sampling circuit can be usedI ac Directly input to the over-current protection circuit, and the over-current protection circuit can output powerFlow ofI ac Greater than or equal to the overcurrent protection thresholdI limit_ocp When the overcurrent protection circuit is used, the enable signal of the driver is directly driven to be in an enable-free state, the inverter is controlled to stop working by blocking the drive, the purpose of limiting the increase of current is achieved, the overcurrent protection purpose is achieved, and the response speed is high. The current sampling circuit and the voltage sampling circuit can also be connected to the microcontroller through an analog-to-digital conversion circuit so as to convert analog signals collected by the current sampling circuit and the voltage sampling circuit into related digital signals for the microcontroller to recognize. If the current is outputI ac Less than the over-current protection thresholdI limit_ocp The microcontroller will further output currentI ac And a cycle-by-cycle current limit threshold Ilimit_cbcIf the current is outputI ac Greater than or equal to the cycle-by-cycle current limit thresholdI limit_cbc And the microcontroller controls the inverter to work in a cycle-by-cycle current limiting mode, and controls the driver to achieve the purpose of limiting the increase of the current by closing the PWM output in advance in each switching cycle. If the current is outputI ac Less than cycle-by-cycle current limit thresholdI limit_cbc The microcontroller further outputs a voltage according to the output voltageV ac DC bus voltageV bus And output currentI ac And adjusting the duty ratio of the PWM signal input to the inverter so as to adjust the inverter in real time according to the working parameters of the inverter. Therefore, the method adjusts the working mode of the inverter according to the output current, the output voltage and the direct current bus voltage of the inverter in real time, can limit the starting current when an impact load is connected, prevents the inverter from being shut down due to overcurrent protection, further improves the loading capacity of the inverter, and enables the inverter to adapt to direct current buses with different dynamic response characteristics.
According to one embodiment of the invention, the output voltage is dependent onV ac DC bus voltageV bus And output currentI ac Adjusting duty ratio of PWM signal input to inverterThe method specifically comprises the following steps: according to the DC bus voltageV bus Obtaining a dynamic current limit curve
(ii) a According to the output voltageV ac And given value of output voltageV ac_ref Obtaining given value of output currentI ac_ref (ii) a According to the given value of output currentI ac_ref Output current of the power supplyI ac And dynamic current limiting curve
The duty ratio of the PWM signal input to the inverter is acquired.
Further, according to an embodiment of the present invention, the dynamic current limit curve is obtained according to the following formula:
wherein the content of the first and second substances,
in order to achieve a dynamic current limiting curve,
in order to limit the upper limit value of the current,
in order to limit the lower limit value of the current,V bus is a voltage of the direct-current bus,
is a first preset voltage, and is a second preset voltage,
is the second preset voltage, and is the second preset voltage,
is a thirdThe voltage is preset to a preset voltage, and the voltage is preset to a preset voltage,
，
，
the current limit threshold is cycle by cycle.
Specifically, the dynamic current limiting curve can be seen in fig. 3, where fig. 3 is the dc bus voltageV bus At the position ofV 1 AndV 2 dynamic time-varying current limiting curve
And bus voltage DC bus voltageV bus The linear relationship is an example, and the nonlinear relationship can be set according to the actual situation.
According to one embodiment of the invention, the output voltage is dependent onV ac And given value of output voltageV ac_ref Obtaining given value of output currentI ac_ref The method specifically comprises the following steps: will output voltageV ac And given value of output voltageV ac_ref Respectively input into the positive input end and the negative input end of the first adder to obtain output voltageV ac And given value of output voltageV ac_ref A difference of (d); will output voltageV ac And given value of output voltageV ac_ref The difference value of the first voltage and the second voltage is input into a first PID regulator to obtain the given value of the output currentI ac_ref。
According to one embodiment of the invention, the setpoint is based on an output currentI ac_ref 、Output currentI ac And dynamic current limiting curve
Obtaining input to an inverterThe duty ratio of the PWM signal of (1) specifically includes: will output currentI ac And output current set valueI ac_ref Respectively input into the positive input end and the negative input end of the second adder to obtain output currentI ac And output current set valueI ac_ref A difference of (d); will output currentI ac And output current set valueI ac_ref Differential, dynamic current limit curve
And inputting the PWM signals into a second PID regulator to obtain the duty ratio of the PWM signals input into the inverter.
Specifically, as shown in fig. 4, the positive terminal input signal of the first adder is the given value of the output voltageV ac_ref The negative end input signal is the output voltage of the inverterV ac The purpose of the first adder in the invention is to obtain the given value of the output voltageV ac_ref And an output voltageV ac The difference (deviation) therebetween. The output of the first adder is connected to a first PID regulator, and the first PID regulator can obtain the given value of the output current through a series of internal operationsI ac_ref The regulation parameters of the first PID regulator can be obtained in advance according to relevant experiments, and the purpose of the first PID regulator is to set the value according to the output voltageV ac_ref And an output voltageV ac Gives the desired output current setpointI ac_ref 。
The output end of the first PID regulator is connected to the positive end of the second adder, and the negative end signal of the second adder is the given value of the output currentI ac_ref The purpose of the second adder in the invention is to obtain the given value of the output currentI ac_ref And output currentI ac The difference (deviation) therebetween. The output end of the second adder is connected to a second PID regulator, and the output amplitude limiting signal of the second PID regulator comes from a dynamic current limiting curve
The output of which after clipping is the duty cycle of the inverter's PWM signal, generally speaking, if the input of the second PID regulator is lower than the dynamic current limit curve
Then there is no need to adjust the current duty cycle, if the input is higher than the dynamic current limit curve
If the duty ratio needs to be reduced, the specific adjusting parameters of the second PID adjuster can be obtained in advance according to relevant experiments, and the purpose of the invention is achieved.
To demonstrate the effectiveness of the present invention, the inventors verified using the following tests.
As shown in fig. 5, the operating waveform of the inverter is t = t1When the impact load is switched on at any moment, the DC bus voltageV bus Is obviously reduced when the output current is reducedI ac Increase to reach the cycle-by-cycle current limiting threshold Ilimit_cbcAnd triggering the cycle-by-cycle current limiting mode to limit the output current to continue increasing. At t = t2Time of day, DC bus voltageV bus Begins to rise due to the DC bus voltageV bus Without reduction to dynamic current limit curve
In the operating range, the load is therefore started normally.
As shown in fig. 6, at t = t3When the impact load is switched on at any moment, the DC bus voltageV bus Is obviously reduced when the output current is reducedI ac Increase to reach the cycle-by-cycle current limiting threshold Ilimit_cbcAnd triggering the cycle-by-cycle current limiting mode to limit the output current to continue increasing. At t = t4Time of day, DC bus voltageV bus Further decrease, at which time the dynamic current limit curve
Function according to the current DC bus voltageV bus And adjusting the output current limiting value to enable the actual output current to be continuously reduced along with the voltage of the direct current bus, thereby realizing the current-limiting starting of the load.
In summary, according to the control method of the inverter of the embodiment of the invention, the operating mode of the inverter is adjusted in real time according to the output current, the output voltage and the dc bus voltage of the inverter, so that the starting current during the access of the impact load can be limited, the inverter is prevented from being shut down due to overcurrent protection, the loading capacity of the inverter is further improved, and the inverter can adapt to dc buses with different dynamic response characteristics.
Corresponding to the control method of the inverter, the invention also provides a control device of the inverter. Since the device embodiment of the present invention corresponds to the method embodiment described above, details that are not disclosed in the device embodiment may refer to the method embodiment described above, and are not described again in the present invention.
Fig. 7 is a block schematic diagram of a control apparatus of an inverter according to an embodiment of the present invention, as shown in fig. 7, the apparatus including: a first acquisition module 1 and a control module 2.
The first obtaining module 1 is used for obtaining output current, output voltage and direct current bus voltage of the inverter; the control module 2 is used for judging whether the output current is greater than or equal to an overcurrent protection threshold value or not, and if the output current is greater than or equal to the overcurrent protection threshold value, the control module controls the inverter to stop working; if the output current is smaller than the overcurrent protection threshold, the control module further judges whether the output current is larger than or equal to a cycle-by-cycle current limiting threshold, wherein the cycle-by-cycle current limiting threshold is smaller than the overcurrent protection threshold; if the output current is larger than or equal to the cycle-by-cycle current limiting threshold value, the control module controls the inverter to work in a cycle-by-cycle current limiting mode; and if the output current is smaller than the cycle-by-cycle current limiting threshold value, the control module adjusts the duty ratio of the PWM signal input to the inverter according to the output voltage, the direct-current bus voltage and the output current.
According to an embodiment of the present invention, the control module 2 is specifically configured to: acquiring a dynamic current limiting curve according to the DC bus voltage; obtaining an output current set value according to the output voltage and the output voltage set value; and acquiring the duty ratio of the PWM signal input to the inverter according to the output current given value, the output current and the dynamic current limiting curve.
According to one embodiment of the invention, the control module 2 obtains the dynamic current limit curve according to the following formula:
wherein the content of the first and second substances,
in order to achieve a dynamic current limiting curve,
in order to limit the upper limit value of the current,
in order to limit the lower limit value of the current,V bus is a voltage of the direct-current bus,
is a first preset voltage, and is a second preset voltage,
is the second preset voltage, and is the second preset voltage,
is the third preset voltage, and is,
，
，
the current limit threshold is cycle by cycle.
According to an embodiment of the invention, the control module 2 is further configured to: respectively inputting the given values of the output voltage and the output voltage into a positive input end and a negative input end of a first adder to obtain the difference value of the given values of the output voltage and the output voltage; inputting the difference value of the output voltage and the given value of the output voltage into a first PID regulator to obtain the given value of the output current; respectively inputting the output current and the output current set value into a positive input end and a negative input end of a second adder to obtain a difference value of the output current and the output current set value; and inputting the difference value of the output current and the output current given value and the dynamic current limiting curve into a second PID regulator so as to obtain the duty ratio of the PWM signal input to the inverter.
According to the control device of the inverter, the working mode of the inverter is adjusted in real time according to the output current, the output voltage and the direct current bus voltage of the inverter, the starting current during the access of an impact load can be limited, the shutdown of the inverter due to overcurrent protection is prevented, the loading capacity of the inverter is further improved, and meanwhile the inverter can adapt to direct current buses with different dynamic response characteristics.
In addition, the invention also provides an inverter, which comprises the control device of the inverter.
According to the inverter provided by the embodiment of the invention, through the control device of the inverter, the working mode of the inverter is adjusted in real time according to the output current, the output voltage and the direct current bus voltage of the inverter, the starting current during the access of an impact load can be limited, the inverter is prevented from being shut down due to overcurrent protection, the loading capacity of the inverter is further improved, and the inverter can be adapted to direct current buses with different dynamic response characteristics.
In the description of the present invention, the terms "first" and "second" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance or implying any number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. The meaning of "plurality" is two or more unless specifically limited otherwise.
In the description herein, references to the description of the term "one embodiment," "some embodiments," "an example," "a specific example," or "some examples," etc., mean that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the invention. In this specification, the schematic representations of the terms used above are not necessarily intended to refer to the same embodiment or example. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples. Furthermore, various embodiments or examples and features of different embodiments or examples described in this specification can be combined and combined by one skilled in the art without contradiction. In the description herein, references to the description of the term "one embodiment," "some embodiments," "an example," "a specific example," or "some examples," etc., mean that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the invention. In this specification, the schematic representations of the terms used above are not necessarily intended to refer to the same embodiment or example. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples. Furthermore, various embodiments or examples and features of different embodiments or examples described in this specification can be combined and combined by one skilled in the art without contradiction.
Any process or method descriptions in flow charts or otherwise described herein may be understood as representing modules, segments, or portions of code which include one or more executable instructions for implementing steps of a custom logic function or process, and alternate implementations are included within the scope of the preferred embodiment of the present invention in which functions may be executed out of order from that shown or discussed, including substantially concurrently or in reverse order, depending on the functionality involved, as would be understood by those reasonably skilled in the art of the present invention.
The logic and/or steps represented in the flowcharts or otherwise described herein, e.g., an ordered listing of executable instructions that can be considered to implement logical functions, can be embodied in any computer-readable medium for use by or in connection with an instruction execution system, apparatus, or device, such as a computer-based system, processor-containing system, or other system that can fetch the instructions from the instruction execution system, apparatus, or device and execute the instructions. For the purposes of this description, a "computer-readable medium" can be any means that can contain, store, communicate, propagate, or transport the program for use by or in connection with the instruction execution system, apparatus, or device. More specific examples (a non-exhaustive list) of the computer-readable medium would include the following: an electrical connection (electronic device) having one or more wires, a portable computer diskette (magnetic device), a Random Access Memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or flash memory), an optical fiber device, and a portable compact disc read-only memory (CDROM). Additionally, the computer-readable medium could even be paper or another suitable medium upon which the program is printed, as the program can be electronically captured, via for instance optical scanning of the paper or other medium, then compiled, interpreted or otherwise processed in a suitable manner if necessary, and then stored in a computer memory.
It should be understood that portions of the present invention may be implemented in hardware, software, firmware, or a combination thereof. In the above embodiments, the various steps or methods may be implemented in software or firmware stored in memory and executed by a suitable instruction execution system. If implemented in hardware, as in another embodiment, any one or combination of the following techniques, which are known in the art, may be used: a discrete logic circuit having a logic gate circuit for implementing a logic function on a data signal, an application specific integrated circuit having an appropriate combinational logic gate circuit, a Programmable Gate Array (PGA), a Field Programmable Gate Array (FPGA), or the like.
It will be understood by those skilled in the art that all or part of the steps carried by the method for implementing the above embodiments may be implemented by hardware related to instructions of a program, which may be stored in a computer readable storage medium, and when the program is executed, the program includes one or a combination of the steps of the method embodiments.
In addition, functional units in the embodiments of the present invention may be integrated into one processing module, or each unit may exist alone physically, or two or more units are integrated into one module. The integrated module can be realized in a hardware mode, and can also be realized in a software functional module mode. The integrated module, if implemented in the form of a software functional module and sold or used as a stand-alone product, may also be stored in a computer readable storage medium.
The storage medium mentioned above may be a read-only memory, a magnetic or optical disk, etc. Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention, and that variations, modifications, substitutions and alterations can be made to the above embodiments by those of ordinary skill in the art within the scope of the present invention.
Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that changes, modifications, substitutions and alterations can be made in these embodiments without departing from the principles and spirit of the invention, the scope of which is defined in the appended claims and their equivalents.
Claims (8)
1. A control method of an inverter, characterized by comprising the steps of:
acquiring output current, output voltage and direct current bus voltage of the inverter;
judging whether the output current is greater than or equal to an overcurrent protection threshold value;
if the output current is greater than or equal to an overcurrent protection threshold value, controlling the inverter to stop working;
if the output current is smaller than the overcurrent protection threshold, further judging whether the output current is larger than or equal to a cycle-by-cycle current limiting threshold, wherein the cycle-by-cycle current limiting threshold is smaller than the overcurrent protection threshold;
if the output current is larger than or equal to the cycle-by-cycle current limiting threshold value, controlling the inverter to work in a cycle-by-cycle current limiting mode;
if the output current is smaller than the cycle-by-cycle current limiting threshold value, adjusting the duty ratio of a PWM signal input to the inverter according to the output voltage, the direct-current bus voltage and the output current; wherein the content of the first and second substances,
adjusting the duty ratio of a PWM signal input to the inverter according to the output voltage, the dc bus voltage, and the output current, specifically including:
acquiring a dynamic current limiting curve according to the direct current bus voltage;
obtaining an output current set value according to the output voltage and the output voltage set value;
and acquiring the duty ratio of the PWM signal input to the inverter according to the output current given value, the output current and the dynamic current limiting curve.
2. The method of controlling an inverter according to claim 1, wherein the dynamic current limit curve is obtained according to the following formula:
wherein the content of the first and second substances,
in order to achieve a dynamic current limiting curve,
in order to limit the upper limit value of the current,
in order to limit the lower limit value of the current,V bus is a voltage of the direct-current bus,
is a first preset voltage, and is a second preset voltage,
is the second preset voltage, and is the second preset voltage,
is the third preset voltage, and is,
，
，
the current limit threshold is cycle by cycle.
3. The method for controlling an inverter according to claim 2, wherein obtaining the given output current value according to the given output voltage and the given output voltage value specifically comprises:
inputting the output voltage and the output voltage given value into a positive input end and a negative input end of a first adder respectively to obtain a difference value of the output voltage and the output voltage given value;
and inputting the difference value of the output voltage and the output voltage given value into a first PID regulator to obtain an output current given value.
4. The method of claim 3, wherein obtaining the duty ratio of the PWM signal input to the inverter according to the output current set point, the output current and the dynamic current limit curve comprises:
inputting the output current and the output current set value into a positive input end and a negative input end of a second adder respectively to obtain a difference value of the output current and the output current set value;
and inputting the difference value of the output current and the output current given value and the dynamic current limiting curve into a second PID regulator to obtain the duty ratio of the PWM signal input to the inverter.
5. A control device for an inverter, comprising:
the first acquisition module is used for acquiring the output current, the output voltage and the direct-current bus voltage of the inverter;
the control module is used for judging whether the output current is greater than or equal to an overcurrent protection threshold value or not, and if the output current is greater than or equal to the overcurrent protection threshold value, the control module controls the inverter to stop working; if the output current is smaller than the overcurrent protection threshold, the control module further judges whether the output current is larger than or equal to a cycle-by-cycle current limiting threshold, wherein the cycle-by-cycle current limiting threshold is smaller than the overcurrent protection threshold; if the output current is larger than or equal to the cycle-by-cycle current limiting threshold value, the control module controls the inverter to work in a cycle-by-cycle current limiting mode; the control module adjusts a duty cycle of a PWM signal input to the inverter based on the output voltage, the DC bus voltage, and the output current if the output current is less than the cycle-by-cycle current limit threshold, wherein,
the control module is specifically configured to:
acquiring a dynamic current limiting curve according to the direct current bus voltage;
obtaining an output current set value according to the output voltage and the output voltage set value;
and acquiring the duty ratio of the PWM signal input to the inverter according to the output current given value, the output current and the dynamic current limiting curve.
6. The inverter control device of claim 5, wherein the control module obtains the dynamic current limit curve according to the following equation:
wherein the content of the first and second substances,
in order to achieve a dynamic current limiting curve,
in order to limit the upper limit value of the current,
in order to limit the lower limit value of the current,V bus is a voltage of the direct-current bus,
is a first preset voltage, and is a second preset voltage,
is the second preset voltage, and is the second preset voltage,
is the third preset voltage, and is,
，
，
the current limit threshold is cycle by cycle.
7. The inverter control device according to claim 6, wherein the control module is further configured to:
inputting the output voltage and the output voltage given value into a positive input end and a negative input end of a first adder respectively to obtain a difference value of the output voltage and the output voltage given value;
inputting the difference value of the output voltage and the output voltage given value into a first PID regulator to obtain an output current given value;
inputting the output current and the output current set value into a positive input end and a negative input end of a second adder respectively to obtain a difference value of the output current and the output current set value;
and inputting the difference value of the output current and the output current given value and the dynamic current limiting curve into a second PID regulator to obtain the duty ratio of the PWM signal input to the inverter.
8. An inverter, characterized by comprising a control device of the inverter according to any one of claims 5 to 7.
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| CN1815838A (en) * | 2005-02-03 | 2006-08-09 | 昂宝电子（上海）有限公司 | Multi-threshold over-curreut protection system and method for switch powersupply converter |
| CN104917365A (en) * | 2015-06-25 | 2015-09-16 | 深圳市英威腾电气股份有限公司 | Current limiting method and current limiting apparatus |
| CN108011506A (en) * | 2017-11-23 | 2018-05-08 | 郑州云海信息技术有限公司 | A kind of Current limited Control method and system of inverter |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN1815838A (en) * | 2005-02-03 | 2006-08-09 | 昂宝电子（上海）有限公司 | Multi-threshold over-curreut protection system and method for switch powersupply converter |
| CN104917365A (en) * | 2015-06-25 | 2015-09-16 | 深圳市英威腾电气股份有限公司 | Current limiting method and current limiting apparatus |
| CN108011506A (en) * | 2017-11-23 | 2018-05-08 | 郑州云海信息技术有限公司 | A kind of Current limited Control method and system of inverter |
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