CN115242063A - Inverter control method, system, device and storage medium - Google Patents
Inverter control method, system, device and storage medium Download PDFInfo
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- 230000005540 biological transmission Effects 0.000 claims description 42
- 230000001960 triggered effect Effects 0.000 claims description 40
- 238000004590 computer program Methods 0.000 claims description 9
- 238000010586 diagram Methods 0.000 description 17
- 238000007789 sealing Methods 0.000 description 8
- 230000001939 inductive effect Effects 0.000 description 7
- 230000003071 parasitic effect Effects 0.000 description 3
- 230000000295 complement effect Effects 0.000 description 2
- 238000004146 energy storage Methods 0.000 description 2
- 230000000903 blocking effect Effects 0.000 description 1
- 230000003111 delayed effect Effects 0.000 description 1
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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
- H02M1/08—Circuits specially adapted for the generation of control voltages for semiconductor devices incorporated in static converters
- H02M1/088—Circuits specially adapted for the generation of control voltages for semiconductor devices incorporated in static converters for the simultaneous control of series or parallel connected semiconductor devices
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
- H02M1/00—Details of apparatus for conversion
- H02M1/0003—Details of control, feedback or regulation circuits
- H02M1/0038—Circuits or arrangements for suppressing, e.g. by masking incorrect turn-on or turn-off signals, e.g. due to current spikes in current mode control
-
- 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
- H02M1/0048—Circuits or arrangements for reducing losses
- H02M1/0054—Transistor switching losses
- H02M1/0058—Transistor switching losses by employing soft switching techniques, i.e. commutation of transistors when applied voltage is zero or when current flow is zero
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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
- H02M1/08—Circuits specially adapted for the generation of control voltages for semiconductor devices incorporated in static converters
- H02M1/083—Circuits specially adapted for the generation of control voltages for semiconductor devices incorporated in static converters for the ignition at the zero crossing of the voltage or the current
-
- 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
- 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
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E10/00—Energy generation through renewable energy sources
- Y02E10/50—Photovoltaic [PV] energy
- Y02E10/56—Power conversion systems, e.g. maximum power point trackers
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Abstract
The invention discloses a method, a system, a device and a storage medium for controlling an inverter, which relate to the technical field of power electronics and are used for controlling a switching tube in the inverter. Therefore, the compensation switch tube in the inverter is turned off at zero current by setting the preset delay time so as to reduce the loss of the compensation switch tube, and the terminal voltage of the compensation switch tube is reduced to 0 or close to 0 at the moment, so that the voltage borne by the compensation switch tube when the compensation switch tube is turned off is reduced, the damage caused by overlarge borne voltage when the compensation switch tube is turned off is avoided, and the reliability of the whole inverter is improved.
Description
Technical Field
The present invention relates to the field of power electronics technologies, and in particular, to an inverter control method, system, device, and storage medium.
Background
The inverter is widely applied to new energy power generation and energy storage systems, and the working principle of the inverter is to convert direct current (a photovoltaic cell panel and a storage battery) into alternating current through an inverter circuit. In an inverter applied to a single-phase photovoltaic and energy storage system, an H full bridge is the most common inverter topology, and the control mode mainly comprises a unipolar modulation mode and a bipolar modulation mode. Unipolar modulation has a serious problem of common mode current although switching loss is smaller and required inversion inductance is smaller than bipolar modulation, and the value of the common mode current linearly increases with the increase of the switching frequency. To integrate the advantages of bipolar modulation and unipolar modulation, a Heric topology was extended by adding a bypass circuit on the ac side of the H full bridge.
The Heric (high efficiency Reliable Inverter) topology of a single-phase Inverter is shown in fig. 1, and fig. 1 is a schematic diagram of an Inverter structure in the prior art. In fig. 1, the voltage of the first compensation switch tube Q1 is bus voltage Upn, the first switch tube Q1 and its body diode D1s, the second switch tube Q2 and its body diode D2s, the third switch tube Q3 and its body diode D3s, the fourth switch tube Q4 and its body diode D4s in the full bridge circuit, the first compensation switch tube Q5 and its body diode D5s, the second compensation switch tube Q6 and its body diode D6s in the bypass circuit, and the first inverter inductor L1 and the second inverter inductor L2, the first inverter inductor L1 is connected in series between the first midpoint of the first switch tube Q1 and the second switch tube Q2 and the power grid, the second inverter inductor L2 is connected in series between the second midpoint of the third switch tube Q3 and the fourth switch tube Q4 and the power grid, the first compensation switch tube Q5 and the second compensation switch tube Q6 are connected in series, and then connected in parallel between the first midpoint and the second midpoint. When the switch tube is controlled, the first switch tube Q1 and the fourth switch tube Q4 are switched simultaneously and are high-frequency compensated with the first compensation switch tube Q5, and the second switch tube Q2 and the third switch tube Q3 are switched simultaneously and are high-frequency compensated with the second compensation switch tube Q6. Fig. 2 shows a control logic diagram of a Heric single-phase three-level inverter circuit, fig. 2 is a schematic control logic diagram of an inverter in the prior art, and Q1/Q4 are control signals of a first switching tube Q1 and a fourth switching tube Q4Q6 is a control signal of the second compensation switch tube Q6, Q5 is a control signal of the first compensation switch tube Q5, Q2/Q3 are control signals of the second switch tube Q2 and the third switch tube Q3, I L For the inductor current, the inductor current I is defined in FIG. 2 L The current flowing into the power grid is positive, and the voltage V of the power grid grid The upper positive and the lower negative are positive. In an active power transmission state in the interval I, the first switch tube Q1 and the fourth switch tube Q4 bear conduction loss and high-frequency switch loss, and the first compensation switch tube Q5 and the second compensation switch tube Q6 only have conduction loss; in the reactive power transmission state of the interval II, a parasitic diode D1s of the first switch tube Q1 and a parasitic diode D2s of the fourth switch tube Q4 bear conduction loss, and a first compensation switch tube Q5 bears conduction loss and high-frequency switching loss; the control process of the interval III is similar to that of the interval I, and the control process of the interval IV is similar to that of the interval II.
At present, the photovoltaic inverter mainly focuses on generating active power, the general power factor operating range is ± 0.8, the voltage stress of the first compensation switch tube Q5 and the second compensation switch tube Q6 is only the platform voltage of the bus in the active power state because no high-frequency switch-on exists in the active power transmission state, the first compensation switch tube Q5 and the second compensation switch tube Q6 are only high-frequency switches in the reactive power transmission state under the condition of small current, and the voltage spike is in direct proportion to the switch current, so the voltage stress borne by the first compensation switch tube Q5 and the second compensation switch tube Q6 is smaller than that borne by the first switch tube Q1 and the second switch tube Q2, in addition, since the switching loss is also small, when the first switching tube Q1, the second switching tube Q2, the third switching tube Q3, and the fourth switching tube Q4 of the inverter are selected, in general, a switching tube having a switching peak larger than those of the first compensation switching tube Q5 and the second compensation switching tube Q6 under the same current stress is selected, and for example, a switching tube having a withstand voltage of 700V is selected for the first switching tube Q1, the second switching tube Q2, the third switching tube Q3, and the fourth switching tube Q4, and a switching tube having a withstand voltage of 500V to 600V is selected for the first compensation switching tube Q5 and the second compensation switching tube Q6.
However, when the electronic device is turned off due to a fault or receives a shutdown instruction, if the first switching tube Q1, the second switching tube Q2, the third switching tube Q3, the fourth switching tube Q4, the first compensation switching tube Q5, and the second compensation switching tube Q6 are directly turned off by blocking waves, the first compensation switching tube Q5 or the second compensation switching tube Q6 may be turned off in a peak current state, so that the first compensation switching tube Q5 or the second compensation switching tube Q6 bears a large voltage spike, and the first compensation switching tube Q5 or the second compensation switching tube Q6 is damaged due to overvoltage.
Therefore, the problem to be solved by those skilled in the art is how to control the compensation switch tube in the inverter to avoid the damage of the compensation switch tube when the inverter is turned off.
Disclosure of Invention
The invention aims to provide an inverter control method, a system, a device and a storage medium, wherein the compensation switch tube in the inverter is turned off at zero current by setting preset delay time so as to reduce the loss of the compensation switch tube, and the terminal voltage of the compensation switch tube is reduced to 0 or is close to 0 at the moment, so that the voltage borne by the compensation switch tube when the compensation switch tube is turned off is reduced, the damage caused by overlarge borne voltage when the compensation switch tube is turned off is avoided, and the reliability of the whole inverter is improved.
In order to solve the above technical problem, the present invention provides an inverter control method, including:
judging whether the inverter works in an active power transmission state at present when shutdown is triggered;
if yes, controlling a compensation switch tube in the inverter to be switched off after a preset delay time so as to enable the compensation switch tube to be switched off at zero current.
Preferably, before controlling the compensation switch tube in the inverter to turn off after the preset delay time, the method further includes:
judging whether the absolute value of the power grid voltage at the rear end of the inverter is smaller than a preset voltage threshold value or not before the preset delay time;
and if so, controlling the compensation switch tube in the inverter to be switched off.
Preferably, after determining whether the inverter is currently operating in an active power transmission state when shutdown is triggered, the method further includes:
if the inverter works in the active power transmission state, judging whether the inverter works in a pure active power transmission state;
and if the inverter works in the pure active power transmission state, controlling the compensation switch tube in the inverter to be switched off.
Preferably, after determining whether the inverter is currently operating in an active power transmission state when shutdown is triggered, the method further includes:
and if not, controlling a compensation switching tube in the inverter to be switched off.
Preferably, before controlling the compensation switch tube in the inverter to turn off after a preset delay time so that the compensation switch tube is turned off at zero current, the method further includes:
calculating the estimated delay time of the current from the triggering shutdown to the inverting inductor to be reduced to 0 based on the inductance value of the inverting inductor in the inverter, the phase angle when the shutdown is triggered, the peak value of the output inductor current and the peak value of the grid voltage;
and setting the estimated delay time as the preset delay time.
Preferably, after calculating the estimated delay time from the time of triggering shutdown to the time when the current of the inverter inductor is reduced to 0 based on the inductance value of the inverter inductor in the inverter, the phase angle when triggering shutdown, the peak value of the output inductor current, and the peak value of the grid voltage, the method further includes:
and determining the preset delay time based on the estimated delay time, wherein the preset delay time is greater than the estimated delay time.
Preferably, when shutdown is triggered, determining whether the inverter currently operates in an active power transmission state includes:
when shutdown is triggered, the current direction of an inverter inductor in the inverter and the voltage polarity of grid voltage at the rear end of the inverter are obtained;
and judging whether the inverter works in an active power transmission state currently or not based on the current direction and the voltage polarity.
In order to solve the above technical problem, the present invention provides an inverter control system, including:
the judging unit is used for judging whether the inverter works in an active power transmission state currently or not when the shutdown is triggered;
and the control unit is used for controlling the compensation switch tube in the inverter to be switched off after a preset delay time when the inverter works and the active power transmission state, so that the compensation switch tube is switched off at zero current.
In order to solve the above technical problem, the present invention provides an inverter control device including:
a memory for storing a computer program;
a processor for implementing the steps of the inverter control method as described above when executing the computer program.
To solve the above technical problem, the present invention provides a computer-readable storage medium having stored thereon a computer program which, when executed by a processor, implements the steps of the inverter control method as described above.
The application provides an inverter control method, a system, a device and a storage medium, the scheme relates to the technical field of power electronics and is used for controlling a switch tube in an inverter. Therefore, the compensation switch tube in the inverter is turned off at zero current by setting the preset delay time so as to reduce the loss of the compensation switch tube, and the terminal voltage of the compensation switch tube is reduced to 0 or close to 0 at the moment, so that the voltage borne by the compensation switch tube when the compensation switch tube is turned off is reduced, the damage caused by overlarge borne voltage when the compensation switch tube is turned off is avoided, and the reliability of the whole inverter is improved.
Drawings
In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings required in the prior art and the embodiments will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and it is obvious for those skilled in the art to obtain other drawings without creative efforts.
Fig. 1 is a schematic diagram of an inverter structure in the prior art;
FIG. 2 is a schematic diagram of a control logic for an inverter according to the prior art;
fig. 3 is a schematic flow chart of an inverter control method according to the present invention;
fig. 4 is a schematic diagram of a control logic in a pure active power transmission state according to the present invention;
fig. 5 is a schematic diagram illustrating a current flowing direction when the first inverter according to the present invention freewheels;
fig. 6 is a schematic diagram illustrating a current flowing direction when the second inverter according to the present invention freewheels;
FIG. 7 is a schematic diagram of a control logic for triggering shutdown according to the present invention;
fig. 8 is a schematic structural diagram of an inverter control system according to the present invention;
fig. 9 is a schematic structural diagram of an inverter control device according to the present invention.
Detailed Description
The core of the invention is to provide a control method, a system, a device and a storage medium of an inverter, wherein the compensation switch tube in the inverter is turned off at zero current by setting preset delay time so as to reduce the loss of the compensation switch tube, and the terminal voltage of the compensation switch tube is reduced to 0 or is close to 0 at the moment, so that the voltage borne by the compensation switch tube when the compensation switch tube is turned off is reduced, the damage caused by overlarge borne voltage when the compensation switch tube is turned off is avoided, and the reliability of the whole inverter is improved.
In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, 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 some, but not all, embodiments of the present invention. All other embodiments, which can be obtained by a person skilled in the art without making any creative effort based on the embodiments in the present invention, belong to the protection scope of the present invention.
Referring to fig. 3, fig. 3 is a schematic flow chart of an inverter control method according to the present invention, the method includes:
s11: judging whether the inverter works in an active power transmission state at present when shutdown is triggered;
in this embodiment, considering that when the inverter is designed, the compensation switch tube in the inverter is usually selected to be a switch tube with a smaller withstand voltage, and when the inverter is shut down due to a fault or shutdown is triggered by receiving a shutdown instruction, the compensation switch tube may be currently turned off at a peak current, so that the compensation switch tube is damaged due to a larger voltage spike, for example, when a first switch tube Q1 and a fourth switch tube Q4 in the inverter are simultaneously turned on and turned off in a control process of high-frequency complementation with a first compensation switch tube Q5, and at this time, a second compensation switch tube Q6 is in a continuous on state, the second compensation switch tube Q6 may be damaged due to a larger voltage spike, which is caused by turn-off at the peak current when the turn-off is triggered; or if the second switching tube Q2 and the third switching tube Q3 in the inverter are switched simultaneously and triggered to be turned off in the control process of high-frequency complementation with the second compensation switching tube Q6, at this time, the first compensation switching tube Q5 is in a continuous conducting state, and the first compensation switching tube Q5 may be damaged due to a large voltage spike borne by the turn-off of the peak current when the turn-off is triggered.
In order to avoid damage to the compensation switch tube, in this embodiment, when shutdown is triggered, it is first determined whether the inverter is currently in an active power transmission state, that is, when shutdown is not triggered, the compensation switch tube is immediately controlled to be turned off.
S12: and if the inverter works in an active power transmission state, controlling a compensation switch tube in the inverter to be switched off after a preset delay time so as to switch off the compensation switch tube at zero current.
If the inverter works in an active power transmission state when the shutdown is triggered, the compensation switch tube is not immediately controlled to be turned off, but the compensation switch tube is controlled to be turned off after the shutdown is triggered for a preset delay time so as to ensure that the compensation switch tube is turned off at zero current, namely, the conduction current of the compensation switch tube is reduced to 0 after the preset delay time, and the compensation switch tube is controlled to be turned off at the moment, so that the current terminal voltage of the compensation switch tube can be reduced to 0 or close to 0, the bearing voltage of the compensation switch tube during the turn-off is reduced, and the compensation switch tube is prevented from being damaged due to overlarge bearing voltage.
It should be noted that, if the current inverter is in the control process that the first switching tube Q1 and the fourth switching tube Q4 are simultaneously switched and are high-frequency complementary to the first compensation switching tube Q5, that is, in the interval i in fig. 2, at this time, the second compensation switching tube Q6 is in a continuous conduction state, if shutdown is triggered, the first switching tube Q1 and the fourth switching tube Q4 are shut down by wave sealing, and after a preset delay time, the second compensation switching tube Q6 is controlled to shut down by wave sealing, that is, the second compensation switching tube Q6 is controlled to shut down; if the current inverter is in the control process that the second switching tube Q2 and the third switching tube Q3 are simultaneously switched and are complementary to the second compensation switching tube Q6 at high frequency, that is, in the interval iii in fig. 2, at this time, the first compensation switching tube Q5 is in a continuous conduction state, if shutdown is triggered at this time, the second switching tube Q2 and the third switching tube Q3 are shut down by wave sealing, and after a preset delay time, the first compensation switching tube Q5 is controlled to shut down by wave sealing, that is, the first compensation switching tube Q5 is controlled to shut down.
As a preferred embodiment, when shutdown is triggered, it is determined whether the inverter is currently in an active power transmission state, specifically, by obtaining a current direction of an inverter inductor in the inverter and a voltage polarity of a grid voltage at a rear end of the inverter when shutdown is triggered, and determining whether the inverter is currently in the active power transmission state based on the current direction and the voltage polarity.
Specifically, in fig. 2, a power frequency cycle is divided into four stages i, ii, iii, and iv, in the stage i, the inverter outputs a voltage which is positive and negative, and a current flows to a power grid, which is in an active power transmission state; in the stage II, the output voltage of the inverter is positive and negative, and the current flows to the inverter and is in a reactive power transmission state; in the stage III, the output voltage of the inverter is negative and positive, and the current flows to the inverter and is in an active power transmission state; and in the stage IV, the output voltage of the inverter is positive at the upper part and negative at the lower part, and the current flows to the power grid, so that the reactive power transmission state is realized.
The current and the grid voltage of the inverter inductor can be acquired by the current acquisition module and the voltage acquisition module respectively to determine the current direction of the inverter inductor and the voltage polarity of the grid voltage at the rear end of the inverter.
In addition, as a preferred embodiment, when shutdown is triggered, if the inverter operates in an active power transmission state, it is further determined whether the inverter operates in a pure active power transmission state, and if the inverter operates in the pure active power transmission state, a compensation switching tube in the inverter is controlled to be turned off.
If the inverter operates in a pure active power transmission state, that is, when a phase angle between grid voltage and inductive current is 0, shutdown is triggered when the phase angle is close to a zero crossing point of the grid voltage, as shown in fig. 4, where fig. 4 is a schematic control logic diagram in the pure active power transmission state provided by the present invention. In fig. 4, after shutdown is triggered at time t1, according to the control logic, a preset delay time needs to elapse, for example, the wave sealing of the second compensation switch Q6 is performed after being delayed to time t3, but the grid voltage passes through a zero crossing point at time t2, so that the wave sealing shutdown of the second compensation switch Q6 can be performed at time t2 without delaying to time t3, so as to improve the control efficiency.
It should be further noted that, when the shutdown is triggered in the interval i, the first switching tube Q1 and the fourth switching tube Q4 are driven to the ground, and at this time, the inductor current flows to the power grid side through the second compensation switching tube Q6 and the body diode D5s of the first compensation switching tube Q5, please refer to fig. 5, where fig. 5 is a schematic diagram of the current flow direction of the current flow of the first inverter provided in the present invention, and the inductor current is substantially reduced to 0 when the second compensation switching tube Q6 is turned off after a preset delay time, so that zero current turn-off of the second compensation switching tube Q6 can be realized; when the interval III triggers shutdown, the second switching tube Q2 and the third switching tube Q3 are driven to be grounded, at the moment, the current of the inductor flows to the power grid side through the body diodes D6s of the first compensation switching tube Q5 and the second compensation switching tube Q6, the current of the inductor is basically reduced to 0 when the first compensation switching tube Q5 is turned off through the preset delay time, and zero current turn-off of the first compensation switching tube Q5 can be realized.
It should be further noted that, in the present application, when the switching tube is controlled, the switching tube is specifically controlled by the DSP and the external logic control circuit, which is not limited in the present application, and a single chip microcomputer or the like may also be used for control.
In conclusion, the preset delay time is set in the application, so that the compensation switch tube in the inverter is turned off at zero current to reduce the loss of the compensation switch tube, and the terminal voltage of the compensation switch tube is reduced to 0 or is close to 0 at the moment, so that the voltage borne by the compensation switch tube when the compensation switch tube is turned off is reduced, the phenomenon that the compensation switch tube bears too large voltage to be damaged when the compensation switch tube is turned off is avoided, and the reliability of the whole inverter is improved.
On the basis of the above-described embodiment:
as a preferred embodiment, before the compensation switch tube in the inverter is controlled to turn off after the preset delay time elapses, the method further includes:
judging whether the absolute value of the power grid voltage at the rear end of the inverter is smaller than a preset voltage threshold value or not before the preset delay time;
and if so, controlling the compensation switch tube in the inverter to be switched off.
In order to avoid that the grid voltage is over 0 and the polarity is suddenly reversed before the preset delay time is reached, so that the originally continuously reduced inductive current is changed into continuously increased, and the conducting current of the switch tube is still larger when the preset delay time is reached, in the embodiment, before the preset delay time is reached, if the absolute value of the grid voltage is detected to be smaller than the preset voltage threshold, the compensation switch tube is directly controlled to be turned off, the compensation switch tube does not need to be turned off after the preset delay time is reached, and the compensation switch tube is prevented from being damaged due to overlarge bearing voltage when the compensation switch tube is turned off.
Specifically, if the shutdown is triggered in the interval i in fig. 2, before the preset delay time is reached, when the grid voltage is reduced from the positive direction to the preset voltage threshold, the second compensation switch Q6 is controlled to be turned off, that is, the second compensation switch Q6 is shut down by wave sealing; if the shutdown is triggered in the interval iii in fig. 2, before the preset delay time is reached, when the grid voltage rises from the negative direction to the preset voltage threshold, the first compensation switch Q5 is controlled to be turned off, that is, the first compensation switch Q5 is shut down by sealing waves.
It should be noted that the preset voltage threshold in this embodiment is a value close to 0V, so as to ensure that the compensation switching tube is controlled to be turned off when the grid voltage is close to 0.
As a preferred embodiment, after determining whether the absolute value of the grid voltage at the back end of the inverter is smaller than the preset voltage threshold before the preset delay time elapses, the method further includes:
if not, the compensation switch tube in the inverter is controlled to be switched off after a preset delay time by taking the moment of triggering shutdown as a time starting point.
If the absolute value of the power grid voltage at the rear end of the inverter is not detected to be smaller than the preset voltage threshold value within the time period from the triggering shutdown to the passing of the preset delay time, the compensation switch tube can be controlled to be turned off when the preset delay time is reached, so that the compensation switch tube can be turned off at zero current.
As a preferred embodiment, after determining whether the inverter is currently operating in the active power transmission state when shutdown is triggered, the method further includes:
if not, the compensation switch tube in the inverter is controlled to be switched off.
In this embodiment, if the inverter does not work in an active power transmission state but works in a reactive power transmission state when shutdown is triggered, for example, in sections iii and iv in fig. 2, the inductive current is small at this time, a preset delay time does not need to be added before the first compensation switch Q5 or the second compensation switch Q6 is turned off, and when shutdown is triggered, the first compensation switch Q1, the second compensation switch Q2, the third compensation switch Q3, the fourth compensation switch Q4, the first compensation switch Q5, or the second compensation switch Q6 is shut down in a wave-blocking manner, for example, in section i, the inductive current freewheels to the bus C1 through D2s and D3s after the wave-blocking manner is performed, please refer to fig. 6, which is a schematic diagram of a current flow direction when the second inverter freewheels provided by the present invention. And after the inductive current is gradually reduced to 0, ending the shutdown. Based on this, the shutdown efficiency can be improved.
As a preferred embodiment, before the compensation switch tube in the inverter is controlled to turn off after the preset delay time elapses, so as to turn off the compensation switch tube at zero current, the method further includes:
calculating the estimated delay time of the current from the triggering of the shutdown to the inversion inductor to be reduced to 0 based on the inductance value of the inversion inductor in the inverter, the phase angle when the shutdown is triggered, the current peak value of the output inductor and the voltage peak value of a power grid;
and setting the pre-estimated delay time as the preset delay time.
In this embodiment, when the preset delay time is set, the estimated delay time for the current from the trigger shutdown to the inverter inductor to decrease to 0 may be specifically calculated according to the inductance value of the inverter inductor, the phase angle when the trigger shutdown is performed, the peak value of the output inductor current, and the peak value of the grid voltage.
If the phase angle of the grid voltage leading the inductor current in fig. 2 is set as a1, and the phase angle at the time of triggering shutdown is assumed as b1, the instantaneous value of the output inductor current is I1 × sin (b 1-a 1), the instantaneous value of the grid voltage is Vg × sin (b 1), I1 and Vg are the peak value of the output inductor current and the peak value of the grid voltage, respectively, and L is the sum of the inductance values of the first inverter inductor L1 and the second inverter inductor L2 in fig. 1. The estimated delay time td from the moment t1 triggering shutdown to the moment when the inductor current is reduced to 0 is as follows:
when the preset delay time is determined, the calculated estimated delay time can be directly set as the preset delay time so as to ensure that the compensation switch tube is controlled to be switched off when the inductive current is reduced to 0 and reduce the bearing voltage when the compensation switch tube is switched off.
As a preferred embodiment, after calculating the estimated delay time from the time of triggering shutdown to the time when the current of the inverter inductor drops to 0 based on the inductance value of the inverter inductor in the inverter, the phase angle when triggering shutdown, the peak value of the output inductor current, and the peak value of the grid voltage, the method further includes:
and determining a preset delay time based on the estimated delay time, wherein the preset delay time is greater than the estimated delay time.
Of course, considering the influence of parasitic parameters in the inverter, when the preset delay time is determined, the preset delay time may be set to be greater than the estimated delay time, so as to further ensure that the inductive current of the compensation switch tube is reduced to 0 when the compensation switch tube is turned off, that is, to further ensure that the zero current of the compensation switch tube is turned off. Referring to fig. 7, fig. 7 is a schematic diagram of a control logic for triggering shutdown according to the present invention, where shutdown is triggered at time t1 in fig. 7, and t1 to t2 may be set as a preset delay time to ensure that the inductor current is completely reduced to 0.
For example, shutdown is triggered at time t1, and the preset delay time may be set to be 1.1 times of t1, which is not limited in this application.
Referring to fig. 8, fig. 8 is a schematic structural diagram of an inverter control system according to the present invention, including:
a determining unit 81, configured to determine whether the inverter currently operates in an active power transmission state when shutdown is triggered;
and the control unit 82 is used for controlling the compensation switch tube in the inverter to be turned off after a preset delay time is passed in the working and active power transmission states, so that the compensation switch tube is turned off at zero current.
For the introduction of the inverter control system provided by the present invention, please refer to the above method embodiments, and the present invention is not repeated herein.
Referring to fig. 9, fig. 9 is a schematic structural diagram of an inverter control device according to the present invention, the device includes:
a memory 91 for storing a computer program;
and a processor 92 for implementing the steps of the inverter control method as described above when executing the computer program.
For the introduction of the inverter control device provided by the present invention, please refer to the above method embodiment, and the present invention is not repeated herein.
The computer-readable storage medium in the present invention has stored thereon a computer program which, when being executed by a processor, realizes the steps of the inverter control method as described above.
For the introduction of the computer-readable storage medium provided by the present invention, please refer to the above-mentioned method embodiments, which are not described herein again.
It should also be noted that, in this specification, relational terms such as first and second, and the like are used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. Also, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. Without further limitation, an element defined by the phrases "comprising a," "8230," "8230," or "comprising" does not exclude the presence of additional like elements in a process, method, article, or apparatus 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 (10)
1. An inverter control method, characterized by comprising:
judging whether the inverter works in an active power transmission state at present when shutdown is triggered;
if yes, controlling a compensation switch tube in the inverter to be switched off after a preset delay time so as to enable the compensation switch tube to be switched off at zero current.
2. The inverter control method according to claim 1, further comprising, before controlling a compensation switch tube in the inverter to turn off after a preset delay time elapses:
judging whether the absolute value of the power grid voltage at the rear end of the inverter is smaller than a preset voltage threshold value or not before the preset delay time;
and if so, controlling the compensation switch tube in the inverter to be switched off.
3. The inverter control method of claim 1, wherein after determining whether the inverter is currently operating in an active power transfer state when shutdown is triggered, further comprising:
if the inverter works in the active power transmission state, judging whether the inverter works in a pure active power transmission state;
and if the inverter works in the pure active power transmission state, controlling the compensation switch tube in the inverter to be switched off.
4. The inverter control method of claim 1, after determining whether the inverter is currently operating in an active power transfer state when shutdown is triggered, further comprising:
and if not, controlling a compensation switching tube in the inverter to be switched off.
5. The inverter control method of claim 1, wherein before the compensating switch tube in the inverter is controlled to be turned off after a preset delay time so as to turn off the compensating switch tube with zero current, the method further comprises:
calculating the estimated delay time of the current from the triggering shutdown to the inverting inductor to be reduced to 0 based on the inductance value of the inverting inductor in the inverter, the phase angle when the shutdown is triggered, the peak value of the output inductor current and the peak value of the grid voltage;
and setting the pre-estimated delay time as the preset delay time.
6. The inverter control method of claim 5, wherein after calculating the estimated delay time from the triggering of shutdown to the current drop of the inverter inductance to 0 based on the inductance value of the inverter inductance in the inverter, the phase angle at the triggering of shutdown, the peak value of the output inductor current, and the peak value of the grid voltage, further comprising:
and determining the preset delay time based on the estimated delay time, wherein the preset delay time is greater than the estimated delay time.
7. The inverter control method of any one of claims 1-6, wherein determining whether the inverter is currently operating in an active power transfer state when shutdown is triggered comprises:
when shutdown is triggered, the current direction of an inverter inductor in the inverter and the voltage polarity of grid voltage at the rear end of the inverter are obtained;
and judging whether the inverter works in an active power transmission state currently or not based on the current direction and the voltage polarity.
8. An inverter control system, comprising:
the judging unit is used for judging whether the inverter works in an active power transmission state currently or not when the shutdown is triggered;
and the control unit is used for controlling the compensation switch tube in the inverter to be switched off after a preset delay time when the inverter works and the active power transmission state is achieved, so that the compensation switch tube is switched off at zero current.
9. An inverter control device, characterized by comprising:
a memory for storing a computer program;
a processor for implementing the steps of the inverter control method according to any one of claims 1 to 7 when executing the computer program.
10. A computer-readable storage medium, characterized in that a computer program is stored thereon which, when being executed by a processor, carries out the steps of the inverter control method according to any one of claims 1 to 7.
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