CN107612302B - Current-limiting protection method and system for inverter - Google Patents
Current-limiting protection method and system for inverter Download PDFInfo
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Abstract
The invention discloses a current-limiting protection method and a current-limiting protection system for an inverter, which are applied to an inverter circuit of an H6 bridge topology, wherein the method comprises the steps of obtaining an instantaneous detection value of inductive current, an instantaneous detection value of load current and an instantaneous detection value of inverter output voltage; calculating an output capacitance current instantaneous value and an inductance current change rate according to the inductance current instantaneous detection value and the load current instantaneous detection value; judging whether the instantaneous detection value of the inductive current, the instantaneous detection value of the load current, the instantaneous detection value of the output voltage of the inverter, the instantaneous value of the output capacitive current and the change rate of the inductive current meet preset conditions or not, and if so, outputting a current-limiting enabling signal; and controlling the high-frequency switching tube in the inverter circuit to be disconnected according to the current-limiting enabling signal. The inverter current-limiting protection method and the inverter current-limiting protection system provided by the invention can effectively inhibit the condition that the output current of the inverter is overlarge under various working conditions, and avoid the shutdown or damage of the inverter caused by overlarge instantaneous impact current.
Description
Technical Field
The invention relates to the technical field of inverter control, in particular to a current-limiting protection method and system for an inverter.
Background
In recent years, with the rapid development of electronic power technology, inverter power supplies are widely applied to the fields of daily life, vehicle-mounted systems, post and telecommunications, and the like.
The inverter mainly comprises an inverter bridge, control logic and a filter circuit, when a load circuit is connected into the inverter circuit through the filter circuit, particularly when the situation that output voltage reverse drop is serious when the load circuit is a capacitive load occurs, the inverter circuit can generate large surge current, the current is increased in a short time, and the inverter is often damaged due to overcurrent. Therefore, the current inverter devices are all provided with overcurrent protection circuits, and the inverter is prevented from being stopped or damaged due to overlarge instantaneous impact current.
The current inverter current limiting mode is mainly characterized in that whether the inverter should limit current or not is judged by comparing whether the real-time value of the output current of the inverter exceeds the current limiting value or not, but due to the complexity of the working conditions of the inverter, such as sudden load change, sudden grid change, direct current input characteristic change and the like, under the working conditions, the inverter is likely to fail to normally enter a current limiting state and carry out overcurrent protection on the inverter, so that the working stability of the inverter is reduced, and the inverter is damaged.
Disclosure of Invention
The invention aims to provide a current-limiting protection method and a current-limiting protection system for an inverter, so as to effectively inhibit the condition that the output current of the inverter is overlarge under various working conditions and avoid the shutdown or damage of the inverter caused by overlarge instantaneous impact current.
In order to achieve the purpose, the invention provides the following technical scheme:
an inverter current-limiting protection method is applied to an inverter circuit of an H6 bridge topology, and comprises the following steps:
detecting inductive current, load current and inverter output voltage in an inverter circuit to obtain an inductive current instantaneous detection value, a load current instantaneous detection value and an inverter output voltage instantaneous detection value;
calculating an output capacitance current instantaneous value and an inductance current change rate according to the inductance current instantaneous detection value and the load current instantaneous detection value;
judging whether the instantaneous inductance current detection value, the instantaneous load current detection value, the instantaneous inverter output voltage detection value, the instantaneous output capacitance current value and the inductance current change rate meet preset conditions or not, and if so, outputting a current-limiting enabling signal;
and controlling a high-frequency switching tube in the inverter circuit to be disconnected according to the current-limiting enabling signal.
Preferably, the determining whether the instantaneous inductance current detection value, the instantaneous load current detection value, and the instantaneous output capacitance current value satisfy a preset condition, and if the preset condition is satisfied, outputting a current-limiting enable signal includes:
judging whether the instantaneous inductive current detection value and the change rate of the inductive current meet a first preset condition, wherein the first preset condition is that the instantaneous inductive current detection value is larger than a first inductive current preset threshold value, the change rate of the inductive current is larger than a first preset threshold value, and if the first preset condition is met, outputting a current-limiting enabling signal;
if the first preset condition is not met, judging whether the instantaneous inductive current detection value and the instantaneous output capacitive current value meet a second preset condition, wherein the second preset condition is that the instantaneous inductive current detection value is larger than a second inductive current preset threshold value and the instantaneous output capacitive current value is larger than a second preset threshold value, and if the second preset condition is met, outputting a current-limiting enabling signal;
if the second preset condition is not met, judging whether the instantaneous inductive current detection value meets a third preset condition, wherein the third preset condition is that the instantaneous inductive current detection value is larger than a third inductive current preset threshold value, and if the third preset condition is met, outputting a current-limiting enabling signal;
if the third preset condition is not met, judging whether the instantaneous detection value of the output voltage of the inverter meets a fourth preset condition, wherein the fourth preset condition is that the instantaneous detection value of the output voltage of the inverter is larger than a voltage limiting threshold value, and if the fourth preset condition is met, outputting a current limiting enabling signal.
Preferably, the controlling the high-frequency switching tube in the inverter circuit to be turned off according to the current-limiting enable signal includes:
carrying out level conversion on the current-limiting enabling signal to obtain a current-limiting logic signal;
and controlling the high-frequency switching tube in the inverter circuit to be disconnected according to the current-limiting logic signal.
Preferably, the method further comprises the following steps:
judging whether the inductive current instantaneous value is smaller than an inductive current recovery threshold value or not, and if so, outputting a second enabling signal;
controlling the high-frequency switch tube in the inverter circuit to be closed according to the second enabling signal.
Preferably, the controlling the high-frequency switching tube in the inverter circuit to be closed according to the second enable signal includes:
carrying out level conversion on the second enabling signal to obtain a logic signal for controlling the high-frequency switch tube to be closed;
and controlling the high-frequency switch tube in the inverter circuit to be closed according to the logic signal.
An inverter current limiting protection system applied to an inverter circuit of an H6 bridge topology, the system comprising:
the detection circuit is used for detecting inductive current, load current and inverter output voltage in the inverter circuit to obtain an inductive current instantaneous detection value, a load current instantaneous detection value and an inverter output voltage instantaneous detection value;
the output capacitance current calculation circuit is connected with the detection circuit and is used for calculating an output capacitance current instantaneous value and an inductance current change rate according to the inductance current instantaneous detection value and the load current instantaneous detection value;
a current-limiting enable signal generating circuit, connected to the detection circuit and the output capacitance current calculation circuit, respectively, for determining whether the instantaneous detection value of the inductance current, the instantaneous detection value of the load current, the instantaneous detection value of the inverter output voltage, the instantaneous value of the output capacitance current, and the change rate of the inductance current satisfy preset conditions, and if the preset conditions are satisfied, outputting a current-limiting enable signal;
and the control circuit is connected with the current-limiting enabling signal generating circuit and is used for controlling the disconnection of a high-frequency switching tube in the inverter circuit according to the current-limiting enabling signal.
Preferably, the current limit enable signal generating circuit includes:
the first judgment circuit is used for judging whether the instantaneous inductance current detection value and the change rate of the inductance current meet a first preset condition, wherein the first preset condition is that the instantaneous inductance current detection value is larger than a first inductance current preset threshold value, the change rate of the inductance current is larger than a first preset threshold value, and if the first preset condition is met, a current-limiting enabling signal is output;
a second determining circuit, configured to determine whether the instantaneous inductor current detection value and the instantaneous output capacitor current value satisfy a second preset condition when the first preset condition is not satisfied, where the second preset condition is that the instantaneous inductor current detection value is greater than a second inductor current preset threshold, and the instantaneous output capacitor current value is greater than a second preset threshold, and if the second preset condition is satisfied, output a current-limiting enable signal;
the third judgment circuit is used for judging whether the instantaneous inductive current detection value meets a third preset condition or not when the second preset condition is not met, wherein the third preset condition is that the instantaneous inductive current detection value is larger than a third inductive current preset threshold value, and if the third preset condition is met, a current-limiting enabling signal is output;
and the fourth judgment circuit is used for judging whether the instantaneous detection value of the output voltage of the inverter meets a fourth preset condition or not when the third preset condition is not met, wherein the fourth preset condition is that the instantaneous detection value of the output voltage of the inverter is greater than a voltage limiting threshold value, and if the fourth preset condition is met, a current limiting enabling signal is output.
Preferably, the control circuit includes:
the first level conversion circuit is connected with the current-limiting enabling signal generation circuit and is used for carrying out level conversion on the current-limiting enabling signal to obtain a current-limiting logic signal;
and the current-limiting control circuit is connected with the first level conversion circuit and is used for controlling the high-frequency switching tube in the inverter circuit to be disconnected according to the current-limiting logic signal.
Preferably, the method further comprises the following steps:
a fifth judging circuit, connected to the control circuit, the detecting circuit and the output capacitance current calculating circuit, for judging whether the instantaneous value of the inductor current is smaller than an inductor current recovery threshold, and if so, outputting a second enable signal;
the control circuit is used for controlling the high-frequency switching tube in the inverter circuit to be closed according to the current restoration power supply enabling signal.
Preferably, the control circuit further includes:
the second level conversion circuit is connected with the fifth judgment circuit and is used for carrying out level conversion on the second enabling signal to obtain a logic signal for controlling the high-frequency switch tube to be closed;
the control circuit is used for controlling the high-frequency switch tube in the inverter circuit to be closed according to the logic signal.
According to the technical scheme, compared with the prior art, the invention discloses an inverter current-limiting protection method and an inverter current-limiting protection system, which are applied to an inverter circuit of an H6 bridge topology, and the method detects inductive current, load current and inverter output voltage in the inverter circuit to obtain an inductive current instantaneous detection value, a load current instantaneous detection value and an inverter output voltage instantaneous detection value; calculating an output capacitance current instantaneous value and an inductance current change rate according to the inductance current instantaneous detection value and the load current instantaneous detection value; judging whether the instantaneous detection value of the inductive current, the instantaneous detection value of the load current, the instantaneous detection value of the output voltage of the inverter, the instantaneous value of the output capacitive current and the change rate of the inductive current meet preset conditions or not, and if so, outputting a current-limiting enabling signal; and controlling the high-frequency switching tube in the inverter circuit to be disconnected according to the current-limiting enabling signal. The inverter current-limiting protection method and the inverter current-limiting protection system provided by the invention have the advantages that the inductance, the load current and the inverter output voltage of the inverter are comprehensively monitored, and various judgment conditions are set, so that the inverter can more quickly limit the current under various emergency conditions, the inverter can follow the current through the H6 bridge low-frequency switching tube, the condition that the output current of the inverter is overlarge under various working conditions is effectively inhibited, and the inverter is prevented from being stopped or damaged due to overlarge instantaneous impact current.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to the provided drawings without creative efforts.
Fig. 1 is a schematic flow chart of a current-limiting protection method for an inverter according to an embodiment of the present invention;
fig. 2 is a schematic flow chart of another inverter current limiting protection method according to an embodiment of the present invention;
fig. 3 is a schematic diagram of a freewheeling mode of an inverter circuit of an H6 bridge topology according to an embodiment of the present invention;
fig. 4 is a schematic structural diagram of a current-limiting protection system of an inverter according to an embodiment of the present invention;
fig. 5 is a schematic structural diagram of another inverter current limiting protection system 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.
Referring to fig. 1, fig. 1 is a schematic flow chart of a current limiting protection method for an inverter according to an embodiment of the present invention. As shown in fig. 1, an embodiment of the present invention discloses a current-limiting protection method for an inverter, which is applied to an inverter circuit of an H6 bridge topology, and the method specifically includes the following steps:
s101, detecting an inductive current, a load current and an inverter output voltage in an inverter circuit to obtain an inductive current instantaneous detection value, a load current instantaneous detection value and an inverter output voltage instantaneous detection value.
In the present embodiment, the instantaneous detection value of the inductor current, the instantaneous detection value of the load current, and the instantaneous detection value of the inverter output voltage are obtained by detecting the inductor current, the load current, and the inverter output voltage for the inverter circuit.
And S102, calculating an output capacitance current instantaneous value and an inductance current change rate according to the inductance current instantaneous detection value and the load current instantaneous detection value.
The instantaneous output capacitor current value is an absolute value of a difference between the instantaneous load current detection value and the instantaneous inductor current detection value, and the change rate of the inductor current is an absolute value of a difference between the instantaneous inductor current value at the present time and the instantaneous inductor current value at the previous time.
S103, judging whether the instantaneous detection value of the inductive current, the instantaneous detection value of the load current, the instantaneous detection value of the output voltage of the inverter, the instantaneous value of the output capacitive current and the change rate of the inductive current meet preset conditions, if so, entering a step S104, and if not, ending the process.
And S104, outputting a current limiting enable signal, and controlling a high-frequency switching tube in the inverter circuit to be disconnected according to the current limiting enable signal.
In addition, the above-mentioned controlling the high-frequency switching tube in the inverter circuit to be turned off according to the current limit enable signal includes:
carrying out level conversion on the current-limiting enabling signal to obtain a current-limiting logic signal;
and controlling the high-frequency switching tube in the inverter circuit to be disconnected according to the current-limiting logic signal.
In this embodiment, when the instantaneous detection value of the inductor current, the instantaneous detection value of the load current, the instantaneous detection value of the inverter output voltage, the instantaneous value of the output capacitor current, and the change rate of the inductor current satisfy preset conditions, the current-limiting enable signal is output, and the high-frequency switching tube in the inverter circuit is controlled to be turned off according to the current-limiting enable signal, that is: as shown in fig. 3, the high-frequency switching tubes Q1, Q2, Q14 and Q15 in the inverter circuit of the H6 bridge topology are turned off, so that the inverter freewheels through the low-frequency switching tubes Q7 and Q8 in the inverter circuit of the H6 bridge topology, the current is limited to continue to increase, and the inverter is prevented from being damaged.
The embodiment provides a current-limiting protection method for an inverter, which enables the inverter to perform current limiting more quickly under various emergency conditions by comprehensively monitoring the inductance, the load current and the output voltage of the inverter and setting various judgment conditions, and enables the inverter to perform follow current through a low-frequency switching tube of an H6 bridge. The inverter current-limiting protection method provided by the embodiment can effectively inhibit the condition that the output current of the inverter is overlarge under various working conditions, and avoid the shutdown or damage of the inverter caused by overlarge instantaneous impact current.
Referring to fig. 2, fig. 2 is a schematic flow chart of another inverter current limiting protection method according to an embodiment of the present invention. As shown in fig. 2, an embodiment of the present invention discloses a current-limiting protection method for an inverter, which is applied to an inverter circuit of an H6 bridge topology, and the method specifically includes the following steps:
s201, detecting an inductive current, a load current and an inverter output voltage in an inverter circuit to obtain an inductive current instantaneous detection value, a load current instantaneous detection value and an inverter output voltage instantaneous detection value.
In the present embodiment, the instantaneous detection value I of the inductor current is obtained by detecting the inductor current, the load current, and the inverter output voltage of the inverter circuitLInstantaneous load current detection value ILoadAnd instantaneous detection value V of inverter output voltageint。
And S202, calculating an output capacitance current instantaneous value and an inductance current change rate according to the inductance current instantaneous detection value and the load current instantaneous detection value.
It should be noted that the output capacitance current instantaneous value ICFor instantaneous detection of load current ILoadAnd instantaneous detection value of inductor current ILThe absolute value of the difference, i.e.: output capacitor current transient value IC＝|ILoad-ILI rate of change of inductor current Δ ILFor the instantaneous value I of the inductor current at the present momentLInstantaneous value of the inductor current I from the previous momentL /The absolute value of the difference of (a) is: rate of change of inductive current Δ IL＝|IL /-IL|。
S203, judging whether the instantaneous inductance current detection value and the change rate of the inductance current meet a first preset condition, wherein the first preset condition is that the instantaneous inductance current detection value is larger than a first inductance current preset threshold value, the change rate of the inductance current is larger than a first preset threshold value, if the first preset condition is met, the step S207 is executed, and if the first preset condition is not met, the step S204 is executed.
It should be noted that the first inductor current preset threshold is Ilimit1A first predetermined threshold value IΔlimitWhen the instantaneous inductance current is detectedLGreater than a first inductor current preset threshold value of Ilimit1And the rate of change of the inductor current Δ ILGreater than a first preset threshold value IΔlimitAnd if so, outputting a current limiting enable signal. When the two conditions are both satisfied, the current is considered to be limited, the judgment of the change rate of the increased inductor current is mainly used for preventing the sudden change of the inductor current, and the preset condition is suitable for various abnormal working conditions, such as inductor saturation and the like.
And S204, judging whether the instantaneous inductive current detection value and the instantaneous output capacitive current value meet a second preset condition, wherein the second preset condition is that the instantaneous inductive current detection value is greater than a second inductive current preset threshold value, and the instantaneous output capacitive current value is greater than a second preset threshold value, if the second preset condition is met, the step S207 is executed, and if the second preset condition is not met, the step S205 is executed.
It should be noted that the preset threshold of the second inductor current is Ilimit2A second predetermined threshold value I/ ΔlimitWhen the instantaneous inductance current is detectedLGreater than the second inductor current by a preset threshold value of Ilimit2And outputs a capacitor current instantaneous value ICGreater than a second predetermined threshold value I/ ΔlimitAnd if so, outputting a current limiting enable signal. When the two conditions are met, the current is considered to be limited, the significance of the instantaneous value of the output capacitor current is that when the load suddenly changes, the current of the output capacitor can be suddenly increased or decreased according to kirchhoff's law because the inductive current can not suddenly change, the value is limited, the inverter is prevented from being damaged by sudden changes of the load, and the preset condition is suitable for sudden changes of the load and dynamic changes of the loadAnd (5) changing the large working condition.
S205, judging whether the instantaneous inductance current detection value meets a third preset condition, wherein the third preset condition is that the instantaneous inductance current detection value is larger than a third inductance current preset threshold value, if so, entering S207, and if not, entering S206.
It should be noted that the preset threshold of the third inductor current is Ilimit3Wherein the third inductor current is preset with a threshold Ilimit3>Second inductor current preset threshold Ilimit2>First inductor current preset threshold Ilimit1When the instantaneous inductance current is detectedLGreater than a third inductor current by a preset threshold value Ilimit3And if so, outputting a current limiting enable signal. When the condition is only met, the inverter enters the current limiting mode, the preset condition is suitable for the situation that the load does not change suddenly, the current is increased slowly, but the absolute value is large and is close to the limit value of the power device.
S206, judging whether the instantaneous detection value of the output voltage of the inverter meets a fourth preset condition, wherein the fourth preset condition is that the instantaneous detection value of the output voltage of the inverter is larger than a voltage limiting threshold value, if the fourth preset condition is met, entering the step S207, and if the fourth preset condition is not met, ending the process.
The voltage limiting threshold V is set tolimitThe preset condition is mainly used as an auxiliary judgment and is suitable for the condition of large voltage fluctuation of the power grid.
And S207, outputting a current-limiting enabling signal, and controlling a high-frequency switching tube in the inverter circuit to be disconnected according to the current-limiting enabling signal.
In addition, the above-mentioned controlling the high-frequency switching tube in the inverter circuit to be turned off according to the current limit enable signal includes:
carrying out level conversion on the current-limiting enabling signal to obtain a current-limiting logic signal;
and controlling the high-frequency switching tube in the inverter circuit to be disconnected according to the current-limiting logic signal.
In this embodiment, when the instantaneous detection value of the inductor current, the instantaneous detection value of the load current, the instantaneous detection value of the inverter output voltage, the instantaneous value of the output capacitor current, and the change rate of the inductor current satisfy preset conditions, the current-limiting enable signal is output, and the high-frequency switching tube in the inverter circuit is controlled to be turned off according to the current-limiting enable signal, that is: as shown in fig. 3, the high-frequency switching tubes Q1, Q2, Q14 and Q15 in the inverter circuit of the H6 bridge topology are turned off, so that the inverter freewheels through the low-frequency switching tubes Q7 and Q8 in the inverter circuit of the H6 bridge topology, the current is limited to continue to increase, and the inverter is prevented from being damaged.
The invention discloses a current-limiting protection method and a current-limiting protection system for an inverter, which are applied to an inverter circuit of an H6 bridge topology, wherein the method detects inductive current, load current and inverter output voltage in the inverter circuit to obtain an inductive current instantaneous detection value, a load current instantaneous detection value and an inverter output voltage instantaneous detection value; calculating an output capacitance current instantaneous value and an inductance current change rate according to the inductance current instantaneous detection value and the load current instantaneous detection value; judging whether the instantaneous detection value of the inductive current, the instantaneous detection value of the load current, the instantaneous detection value of the output voltage of the inverter, the instantaneous value of the output capacitive current and the change rate of the inductive current meet preset conditions or not, and if so, outputting a current-limiting enabling signal; and controlling the high-frequency switching tube in the inverter circuit to be disconnected according to the current-limiting enabling signal. The inverter current-limiting protection method provided by the invention can enable the inverter to perform current limiting more quickly under various emergency conditions by comprehensively monitoring the inductance, the load current and the output voltage of the inverter and setting various judgment conditions, so that the inverter can follow current through the H6 bridge low-frequency switching tube, thereby effectively inhibiting the condition that the output current of the inverter is overlarge under various working conditions and avoiding the shutdown or damage of the inverter due to overlarge instantaneous impact current.
Preferably, on the basis of fig. 1 and 2, the method may further include the steps of:
judging whether the instantaneous value of the inductive current is smaller than an inductive current recovery threshold value or not, and if so, outputting a second enabling signal;
and controlling the high-frequency switch tube in the inverter circuit to be closed according to the second enabling signal.
In this embodiment, the controlling the high-frequency switching tube in the inverter circuit to be closed according to the second enable signal may specifically include the following steps:
carrying out level conversion on the second enabling signal to obtain a logic signal for controlling the high-frequency switch tube to be closed;
and controlling the high-frequency switch tube in the inverter circuit to be closed according to the logic signal.
It should be noted that, in this embodiment, when it is determined that the instantaneous value of the inductor current is smaller than the inductor current recovery threshold, the second enable signal is output, and the high-frequency switching tube in the inverter circuit is controlled to be closed according to the second enable signal, that is, the high-frequency switching tube is turned on, and the recovery high-frequency switching tube supplies current to the inverter circuit of the H6 bridge topology.
The invention also discloses a system based on the inverter current-limiting protection method.
It should be noted that, for the description of the inverter current limiting protection system, reference may be made to the inverter current limiting protection method provided above, and details are not described below.
Referring to fig. 4, fig. 4 is a schematic structural diagram of an inverter current limiting protection system according to an embodiment of the present invention, and as shown in fig. 4, the embodiment discloses an inverter current limiting protection system, which specifically includes the following components:
a detection circuit 401, configured to detect an inductive current, a load current, and an inverter output voltage in the inverter circuit, and obtain an instantaneous inductive current detection value, an instantaneous load current detection value, and an instantaneous inverter output voltage detection value;
an output capacitance current calculation circuit 402, connected to the detection circuit 401, for calculating an output capacitance current instantaneous value and an inductance current change rate according to the inductance current instantaneous detection value and the load current instantaneous detection value;
a current-limiting enable signal generating circuit 403, connected to the detecting circuit 401 and the output capacitor current calculating circuit 402, respectively, for determining whether the instantaneous detected value of the inductor current, the instantaneous detected value of the load current, the instantaneous detected value of the inverter output voltage, the instantaneous value of the output capacitor current, and the change rate of the inductor current satisfy preset conditions, and if the preset conditions are satisfied, outputting a current-limiting enable signal;
and a control circuit 404 connected to the current-limiting enable signal generating circuit 403, for controlling the high-frequency switch tube in the inverter circuit to be turned off according to the current-limiting enable signal.
Preferably, referring to fig. 5, the current limit enable signal generating circuit 403 may include:
the first judging circuit 501 is configured to judge whether the instantaneous detection value of the inductor current and the change rate of the inductor current satisfy a first preset condition, where the first preset condition is that the instantaneous detection value of the inductor current is greater than a first preset inductor current threshold, and the change rate of the inductor current is greater than a first preset threshold, and if the first preset condition is satisfied, output a current-limiting enable signal;
a second determining circuit 502, configured to determine whether the instantaneous inductor current detection value and the instantaneous output capacitor current value satisfy a second preset condition when the first preset condition is not satisfied, where the second preset condition is that the instantaneous inductor current detection value is greater than a second inductor current preset threshold, and the instantaneous output capacitor current value is greater than a second preset threshold, and if the second preset condition is satisfied, output a current-limiting enable signal;
a third determining circuit 503, configured to determine whether the instantaneous inductor current detection value meets a third preset condition when the second preset condition is not met, where the third preset condition is that the instantaneous inductor current detection value is greater than a third preset inductor current threshold, and if the third preset condition is met, output a current-limiting enable signal;
and a fourth determining circuit 504, configured to determine whether the instantaneous inverter output voltage detection value meets a fourth preset condition when the third preset condition is not met, where the fourth preset condition is that the instantaneous inverter output voltage detection value is greater than the voltage limiting threshold, and if the fourth preset condition is met, output a current limiting enable signal.
Preferably, referring to fig. 5, the control circuit 404 includes:
the first level conversion circuit 505 is connected with the current-limiting enabling signal generation circuit and is used for carrying out level conversion on the current-limiting enabling signal to obtain a current-limiting logic signal;
the control circuit 404 is used for controlling the high-frequency switch tube in the inverter circuit to be switched off according to the current-limiting logic signal.
Preferably, the system further comprises:
a fifth judging circuit 405, connected to the control circuit 404, the detecting circuit 401 and the output capacitance current calculating circuit 402, for judging whether the instantaneous value of the inductor current is smaller than the inductor current recovery threshold, and if so, outputting a second enable signal;
the control circuit 404 is used for controlling the high-frequency switch tube in the inverter circuit to close according to the current restoration power supply enabling signal.
Preferably, the control circuit 404 further includes:
the second level conversion circuit 506 is connected with the fifth judgment circuit 405 and is used for performing level conversion on the second enable signal to obtain a logic signal for controlling the high-frequency switch tube to be closed;
the control circuit 404 is used for controlling the high-frequency switch tube in the inverter circuit to close according to the logic signal.
The invention discloses an inverter current-limiting protection system, which is applied to an inverter circuit of an H6 bridge topology, and the system obtains an inductive current instantaneous detection value, a load current instantaneous detection value and an inverter output voltage instantaneous detection value by detecting inductive current, load current and inverter output voltage in the inverter circuit; calculating an output capacitance current instantaneous value and an inductance current change rate according to the inductance current instantaneous detection value and the load current instantaneous detection value; judging whether the instantaneous detection value of the inductive current, the instantaneous detection value of the load current, the instantaneous detection value of the output voltage of the inverter, the instantaneous value of the output capacitive current and the change rate of the inductive current meet preset conditions or not, and if so, outputting a current-limiting enabling signal; and controlling the high-frequency switching tube in the inverter circuit to be disconnected according to the current-limiting enabling signal. The inverter current-limiting protection system provided by the invention can be used for enabling the inverter to perform current limiting more quickly under various emergency conditions by comprehensively monitoring the inductance, the load current and the output voltage of the inverter and setting various judgment conditions, so that the inverter can perform follow current through the H6 bridge low-frequency switching tube, the condition that the output current of the inverter is overlarge under various working conditions is effectively inhibited, and the inverter is prevented from being stopped or damaged due to overlarge instantaneous impact current.
It is noted that, herein, relational terms such as first and second, and the like may be used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. Also, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that 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 an article or device that comprises the element.
The previous description of the disclosed embodiments is provided to enable any person skilled in the art to make or use the present invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other embodiments without departing from the spirit or scope of the invention. Thus, the present invention is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.
Claims (6)
1. A current-limiting protection method of an inverter is applied to an inverter circuit of an H6 bridge topology, and the method comprises the following steps:
detecting inductive current, load current and inverter output voltage in an inverter circuit to obtain an inductive current instantaneous detection value, a load current instantaneous detection value and an inverter output voltage instantaneous detection value;
calculating an output capacitance current instantaneous value and an inductance current change rate according to the inductance current instantaneous detection value and the load current instantaneous detection value;
judging whether the instantaneous inductance current detection value, the instantaneous load current detection value, the instantaneous inverter output voltage detection value, the instantaneous output capacitance current value and the inductance current change rate meet preset conditions or not, and if so, outputting a current-limiting enabling signal;
controlling a high-frequency switching tube in the inverter circuit to be disconnected according to the current-limiting enabling signal;
wherein the controlling the high-frequency switching tube in the inverter circuit to be disconnected according to the current-limiting enable signal comprises:
carrying out level conversion on the current-limiting enabling signal to obtain a current-limiting logic signal;
controlling the high-frequency switching tube in the inverter circuit to be disconnected according to the current-limiting logic signal;
the determining whether the instantaneous inductance current detection value, the instantaneous load current detection value, and the instantaneous output capacitance current value satisfy a preset condition, and if the preset condition is satisfied, outputting a current-limiting enable signal includes:
judging whether the instantaneous inductive current detection value and the change rate of the inductive current meet a first preset condition, wherein the first preset condition is that the instantaneous inductive current detection value is larger than a first inductive current preset threshold value, the change rate of the inductive current is larger than a first preset threshold value, and if the first preset condition is met, outputting a current-limiting enabling signal;
if the first preset condition is not met, judging whether the instantaneous inductive current detection value and the instantaneous output capacitive current value meet a second preset condition, wherein the second preset condition is that the instantaneous inductive current detection value is larger than a second inductive current preset threshold value and the instantaneous output capacitive current value is larger than a second preset threshold value, and if the second preset condition is met, outputting a current-limiting enabling signal;
if the second preset condition is not met, judging whether the instantaneous inductive current detection value meets a third preset condition, wherein the third preset condition is that the instantaneous inductive current detection value is larger than a third inductive current preset threshold value, and if the third preset condition is met, outputting a current-limiting enabling signal;
if the third preset condition is not met, judging whether the instantaneous detection value of the output voltage of the inverter meets a fourth preset condition, wherein the fourth preset condition is that the instantaneous detection value of the output voltage of the inverter is larger than a voltage limiting threshold value, and if the fourth preset condition is met, outputting a current limiting enabling signal.
2. The inverter current limiting protection method of claim 1, further comprising:
judging whether the inductive current instantaneous value is smaller than an inductive current recovery threshold value or not, and if so, outputting a second enabling signal;
controlling the high-frequency switch tube in the inverter circuit to be closed according to the second enabling signal.
3. The inverter current-limiting protection method according to claim 2, wherein the controlling the high-frequency switching tubes in the inverter circuit to be closed according to the second enable signal comprises:
carrying out level conversion on the second enabling signal to obtain a logic signal for controlling the high-frequency switch tube to be closed;
and controlling the high-frequency switch tube in the inverter circuit to be closed according to the logic signal.
4. An inverter current limiting protection system applied to an inverter circuit of an H6 bridge topology, the system comprising:
the detection circuit is used for detecting inductive current, load current and inverter output voltage in the inverter circuit to obtain an inductive current instantaneous detection value, a load current instantaneous detection value and an inverter output voltage instantaneous detection value;
the output capacitance current calculation circuit is connected with the detection circuit and is used for calculating an output capacitance current instantaneous value and an inductance current change rate according to the inductance current instantaneous detection value and the load current instantaneous detection value;
a current-limiting enable signal generating circuit, connected to the detection circuit and the output capacitance current calculation circuit, respectively, for determining whether the instantaneous detection value of the inductance current, the instantaneous detection value of the load current, the instantaneous detection value of the inverter output voltage, the instantaneous value of the output capacitance current, and the change rate of the inductance current satisfy preset conditions, and if the preset conditions are satisfied, outputting a current-limiting enable signal;
the control circuit is connected with the current-limiting enabling signal generating circuit and is used for controlling the high-frequency switching tube in the inverter circuit to be disconnected according to the current-limiting enabling signal;
wherein, the control circuit includes:
the first level conversion circuit is connected with the current-limiting enabling signal generation circuit and is used for carrying out level conversion on the current-limiting enabling signal to obtain a current-limiting logic signal;
the current-limiting control circuit is connected with the first level conversion circuit and used for controlling the high-frequency switching tube in the inverter circuit to be disconnected according to the current-limiting logic signal;
the current-limiting enable signal generating circuit includes:
the first judgment circuit is used for judging whether the instantaneous inductance current detection value and the change rate of the inductance current meet a first preset condition, wherein the first preset condition is that the instantaneous inductance current detection value is larger than a first inductance current preset threshold value, the change rate of the inductance current is larger than a first preset threshold value, and if the first preset condition is met, a current-limiting enabling signal is output;
a second determining circuit, configured to determine whether the instantaneous inductor current detection value and the instantaneous output capacitor current value satisfy a second preset condition when the first preset condition is not satisfied, where the second preset condition is that the instantaneous inductor current detection value is greater than a second inductor current preset threshold, and the instantaneous output capacitor current value is greater than a second preset threshold, and if the second preset condition is satisfied, output a current-limiting enable signal;
the third judgment circuit is used for judging whether the instantaneous inductive current detection value meets a third preset condition or not when the second preset condition is not met, wherein the third preset condition is that the instantaneous inductive current detection value is larger than a third inductive current preset threshold value, and if the third preset condition is met, a current-limiting enabling signal is output;
and the fourth judgment circuit is used for judging whether the instantaneous detection value of the output voltage of the inverter meets a fourth preset condition or not when the third preset condition is not met, wherein the fourth preset condition is that the instantaneous detection value of the output voltage of the inverter is greater than a voltage limiting threshold value, and if the fourth preset condition is met, a current limiting enabling signal is output.
5. The inverter current limiting protection system of claim 4, further comprising:
a fifth judging circuit, connected to the control circuit, the detecting circuit and the output capacitance current calculating circuit, for judging whether the instantaneous value of the inductor current is smaller than an inductor current recovery threshold, and if so, outputting a second enable signal;
the control circuit is used for controlling the high-frequency switching tube in the inverter circuit to be closed according to the current restoration power supply enabling signal.
6. The inverter current limiting protection system of claim 5, wherein the control circuit further comprises:
the second level conversion circuit is connected with the fifth judgment circuit and is used for carrying out level conversion on the second enabling signal to obtain a logic signal for controlling the high-frequency switch tube to be closed;
the control circuit is used for controlling the high-frequency switch tube in the inverter circuit to be closed according to the logic signal.
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