CN115242072A - Method and device for reducing stress of inverter tube and inverter - Google Patents
Method and device for reducing stress of inverter tube and inverter Download PDFInfo
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- CN115242072A CN115242072A CN202211128300.9A CN202211128300A CN115242072A CN 115242072 A CN115242072 A CN 115242072A CN 202211128300 A CN202211128300 A CN 202211128300A CN 115242072 A CN115242072 A CN 115242072A
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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
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
- H02M1/00—Details of apparatus for conversion
- H02M1/32—Means for protecting converters other than automatic disconnection
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
- H02M7/00—Conversion of ac power input into dc power output; Conversion of dc power input into ac power output
- H02M7/42—Conversion of dc power input into ac power output without possibility of reversal
- H02M7/44—Conversion of dc power input into ac power output without possibility of reversal by static converters
- H02M7/48—Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode
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- 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
Abstract
The invention relates to the technical field of energy storage inversion, and mainly provides a method and a device for reducing stress of an inverter tube and an inverter. The method comprises the steps of obtaining a first inversion current, a load reduction voltage and a first bus voltage of an inversion tube, then reducing the power of the inversion tube when the first bus voltage is larger than the load reduction voltage, obtaining a second inversion current of the inversion tube after the power is reduced, obtaining an analog voltage according to the second inversion current, and obtaining a protection current of the inversion tube according to the load reduction voltage; and finally, triggering the inverter tube to carry out wave-by-wave current limiting so as to reduce the stress of the inverter tube when the analog voltage is greater than the protection voltage. The stress of the inverter tube is reduced through the mode, the limit of hardware is not required to be triggered all the time, and therefore the loss and the cost of the hardware are reduced, and meanwhile the development period is shortened.
Description
Technical Field
The invention relates to the technical field of energy storage inversion, in particular to a method and a device for reducing stress of an inverter tube and an inverter.
Background
In a commonly used single-phase two-stage grid-connected inverter, the front stage is a direct current circuit part, the rear stage is an inverter circuit part, and direct current is arranged in the middle. The front stage is responsible for tracking the maximum power of the photovoltaic cell panel and adjusting the power of the battery end, energy is gathered into the direct current bus, and the rear stage inverts the energy of the bus into current with the same frequency and phase as the power grid and enters the power grid. In the working process of the inverter, if the conditions of mains supply short circuit, mains supply voltage mutation and the like occur, because the internal parameters of the inverter are in a limit design state, the protection threshold value of the inverter needs to be adjusted to ensure that the stress of an inverter tube is in a normal range, so that the condition that the inverter is damaged by overvoltage or overcurrent is avoided.
In the prior art, a protection point for wave-by-wave current limiting is usually triggered fixedly, when a current exceeds the protection point, the stress of an inverter tube is ensured to be within a normal range by directly triggering the limit of the stress of hardware, and the stress range is avoided to be exceeded by the method, so that the damage to hardware equipment is increased, the service life of the equipment is shortened, and the hardware development cost is increased.
Disclosure of Invention
The embodiment of the invention mainly provides a method and a device for reducing stress of an inverter tube and an inverter, and aims to solve the technical problems of high hardware loss, high cost and long development period when the stress of the inverter tube is reduced in the prior art.
In order to solve the technical problem, one technical scheme adopted by the embodiment of the invention is as follows: the method for reducing the stress of the inverter tube is applied to an inverter and comprises the following steps: acquiring a first inversion current of an inversion tube; acquiring load reduction voltage and first bus voltage of the inverter tube, reducing power of the inverter tube when the first bus voltage is greater than the load reduction voltage, and acquiring second inverter current of the inverter tube after the power is reduced; obtaining analog voltage according to the second inverter current, and obtaining protection current of the inverter tube according to the load reduction voltage; and converting the protection current into protection voltage, and triggering the inverter tube to carry out wave-by-wave current limiting when the analog voltage is larger than the protection voltage by comparing the analog voltage with the protection voltage so as to reduce the stress of the inverter tube.
Optionally, the obtaining of the load reduction voltage of the inverter tube includes: acquiring the safe voltage of the inverter tube; controlling the full-load operation of the inverter based on the safe voltage, and tracking the maximum power of the inverter in real time; acquiring a second bus voltage and a third inverter current corresponding to the maximum power of the inverter; obtaining the stress of the inverter tube according to the second bus voltage and the third inverter current; acquiring a stress peak of the inverter tube according to the third inverter current; and acquiring the difference between the stress and the stress spike, and setting the difference as the load reduction voltage of the inverter tube.
Optionally, the inverter further includes a sensor, and the obtaining an analog voltage according to the second inverter current includes: acquiring a second inversion current of the inversion tube, and converting the second inversion current into inversion voltage through the sensor; acquiring a reference voltage output by the sensor; and comparing the inverted voltage with the reference voltage to obtain the analog voltage of the inverter.
Optionally, the obtaining of the protection current of the inverter tube according to the step-down voltage includes:
acquiring the slope of the protection current according to the load reduction voltage and the first bus voltage; acquiring a difference value between the first bus voltage and the load shedding voltage; and calculating the protection current of the inverter tube according to the difference, the third inverter current and the slope.
Optionally, triggering the inverter tube to perform wave-by-wave current limiting includes: acquiring the duty ratio of the inverter tube in normal working; obtaining a comparison result of the analog voltage and the protection voltage; when the analog voltage is smaller than the protection voltage, maintaining the duty ratio of the inverter tube, and acquiring the inverter current of the inverter tube in real time; and when the analog voltage is greater than the protection voltage, adjusting the duty ratio of the inverter tube to reduce a second inverter current of the inverter tube.
In order to solve the above technical problem, another technical solution adopted by the embodiment of the present invention is: the device for reducing the stress of the inverter tube is applied to an inverter and comprises: the current sampling module is used for acquiring a first inversion current of the inversion tube; the over-voltage load reduction module is used for obtaining load reduction voltage and first bus voltage of the inverter tube, reducing the power of the inverter tube when the first bus voltage is greater than the load reduction voltage, and obtaining second inverter current of the inverter tube after the power is reduced; the acquisition module is used for acquiring analog voltage according to the second inverter current and acquiring protection current of the inverter tube according to the load reduction voltage; the comparison module is used for converting the protection current into protection voltage and comparing the magnitude of the analog voltage with the magnitude of the protection voltage; and the wave-by-wave current limiting module is used for triggering the inverter tube to carry out wave-by-wave current limiting when the analog voltage is greater than the protection voltage so as to reduce the stress of the inverter tube.
Optionally, the excess voltage load reduction module is specifically configured to: obtaining the safe voltage of the inverter tube;
controlling the full-load operation of the inverter based on the safe voltage, and tracking the maximum power of the inverter in real time; acquiring a second bus voltage and a third inverter current corresponding to the maximum power of the inverter; acquiring a first stress of the inverter tube according to the second bus voltage and the third inverter current; acquiring a stress peak of the inverter tube according to the third inverter current; and acquiring the difference between the first stress and the stress peak, and setting the difference as the load reduction voltage of the inverter tube.
Optionally, the inverter further includes a sensor, and the obtaining module is specifically configured to: acquiring a second inversion current of the inversion tube, and converting the second inversion current into inversion voltage through the sensor; acquiring a reference voltage output by the sensor; and comparing the inverted voltage with the reference voltage to obtain the analog voltage of the inverter.
In order to solve the above technical problem, another technical solution adopted by the embodiment of the present invention is: provided is an inverter including: a controller; a DC circuit; an inverter circuit; and a dc bus connecting the dc circuit to the inverter; wherein the controller comprises at least one processor; and a memory communicatively coupled to the at least one processor; wherein the memory stores instructions executable by the at least one processor to enable the at least one processor to perform the method as described above.
In order to solve the above technical problem, another technical solution adopted by the embodiment of the present invention is: a non-transitory computer-readable storage medium is provided that stores computer-executable instructions for causing an inverter to perform the method as described above.
The embodiment of the invention provides a method, a device and an inverter for reducing stress of an inverter tube, which are different from the related technical situation, and mainly comprises the steps of obtaining a first inverter current, a load reduction voltage and a first bus voltage of the inverter tube, reducing the power of the inverter tube when the first bus voltage is greater than the load reduction voltage, obtaining a second inverter current of the inverter tube after the power is reduced, obtaining an analog voltage according to the second inverter current, and obtaining a protection current of the inverter tube according to the load reduction voltage; and finally, when the analog voltage is greater than the protection voltage, triggering the inverter tube to carry out wave-by-wave current limiting so as to reduce the stress of the inverter tube. The stress of the inverter tube is reduced through the mode, the limit of hardware is not required to be triggered all the time, and therefore the loss and the cost of the hardware are reduced, and meanwhile the development period is shortened.
Drawings
One or more embodiments are illustrated in drawings corresponding to, and not limiting to, the embodiments, in which elements having the same reference number designation may be represented as similar elements, unless specifically noted, the drawings in the figures are not to scale.
Fig. 1 is an application scenario provided by an embodiment of the present invention;
fig. 2 is a block diagram of an inverter according to an embodiment of the present invention;
fig. 3 is a flowchart of a method for reducing stress of an inverter tube according to an embodiment of the present invention;
fig. 4 is a graph of the maximum power point of the inverter in an embodiment of the present invention;
fig. 5a is a graph illustrating the relationship between the inverter current and the stress spike according to an embodiment of the present invention;
FIG. 5b is a graph illustrating the relationship between the inverter current and the stress according to an embodiment of the present invention;
fig. 6 is a graph of a load reduction curve, a CBC protection curve and a charging power according to the present embodiment;
fig. 7 is a block diagram of a structure of an apparatus for reducing stress of an inverter tube according to an embodiment of the present invention.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is described in further detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.
It should be noted that, if not conflicted, the various features of the embodiments of the invention may be combined with each other within the scope of protection of the invention. Additionally, while functional block divisions are performed in the device diagrams, with logical sequences shown in the flowcharts, in some cases, the steps shown or described may be performed in a different order than the block divisions in the device diagrams, or the flowcharts.
Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. The terminology used in the description of the invention herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. As used herein, the term "and/or" includes any and all combinations of one or more of the associated listed items.
Referring to fig. 1, fig. 1 is an application scenario provided by an embodiment of the present invention, the application scenario includes an inverter 100, a photovoltaic panel 200, and a power grid 300, the inverter 100 is respectively connected to the photovoltaic panel 200 and the power grid 300, the photovoltaic panel 200 is configured to acquire solar energy and store the solar energy, and the inverter 100 is configured to acquire the solar energy stored by the photovoltaic panel 200, convert the solar energy into an alternating current, and output the alternating current to the power grid 300, so as to convert the solar energy into electric energy.
Referring to fig. 2, fig. 2 is a block diagram of an inverter according to an embodiment of the present invention, and as shown in fig. 2, the inverter 100 includes a dc circuit 10, an inverter circuit 20, and a controller 30. The inverter circuit 20 is connected to the dc circuit 10 through a dc bus, and the controller 30 is connected to the dc circuit 10 and the inverter circuit 20, respectively. The direct current circuit 10 obtains the solar energy and converts the solar energy into direct current, the direct current is input to the inverter circuit 20 through the direct current bus, and then the direct current is inverted into alternating current through the inverter circuit 20 and finally output to the power grid 300. The controller 30 is configured to control the operations of the inverter circuit 20 and the dc circuit 10, obtain the voltage and the current output by the dc circuit 10 in real time, determine whether the sum of the voltage and the current output by the dc circuit 10 exceeds the tolerance range of the inverter circuit 20, and reduce the output current of the dc circuit 10 if the sum exceeds the tolerance range of the inverter circuit 20, thereby avoiding the inverter circuit 20 from being damaged. Specifically, the inverter circuit 20 includes an inverter tube, and the inverter tube inverts the dc power into an ac power, but in a working process of the inverter circuit, it needs to be ensured that a stress borne by the inverter tube does not exceed a standard, where the stress of the inverter tube refers to a maximum voltage when the inverter tube is turned off. The stress borne by the inverter tube includes a voltage and a charging current on a dc bus, wherein the charging current of the inverter circuit 20 is an output current of the dc circuit 10. When the sum of the voltage on the dc bus and the charging current is greater than the maximum voltage when the inverter tube is turned off, the inverter tube may be damaged, thereby causing a problem in the inverter circuit 20. Therefore, during the operation of the inverter 100, it is required to ensure that the sum of the voltage and the current output by the dc circuit 10 does not exceed the stress of the inverter tube in the inverter circuit 20, so as to ensure the normal operation of the inverter.
In some embodiments, the controller 30 may be a microprocessor chip, and preferably, the microprocessor chip may be a DSP control chip. For example, a micro-processing chip with model number TMS320F 280049. When the inverter 100 works, the bus voltage and the charging current of the inverter 100 need to be obtained in real time to ensure that the stress borne by the inverter 100 is within the stress range of an inverter tube, so that the inverter tube is protected. Specifically, the output current signal of the dc circuit 10 is collected in real time. And then converting the current signal into a voltage signal through an external sensor, wherein the external sensor can be a voltage output type sensor, and outputting the voltage signal after conversion in a certain proportion in the external sensor by inputting the collected current into the external sensor. At this time, since the current signal output by the dc circuit 10 is a sine wave analog signal, the current signal has a positive or negative polarity, and after the current signal is converted into a voltage signal by the external sensor, the voltage signal also includes a positive voltage signal and a negative voltage signal. And for the determination of the voltage signal, it is possible to determine whether the voltage signal is a positive voltage signal or a negative voltage signal by acquiring a reference voltage of the external sensor and comparing the reference voltage with the voltage signal. When the voltage signal is greater than the reference voltage, the voltage signal is a positive voltage signal, and when the voltage signal is less than the reference voltage, the voltage signal is a negative voltage signal. And then inputting the voltage signal to an ADC (analog-to-digital conversion) port of the micro-processing chip to convert the voltage signal from an analog signal to a digital signal, wherein the voltage signal comprises a sine wave analog signal, the sine wave analog voltage signal is converted through the ADC port to obtain a rectangular wave digital signal, and the rectangular wave digital signal is input to a negative terminal of a comparator in the micro-processing chip. Further, the maximum bus voltage on the bus is obtained through the micro-processing chip, and the load reduction voltage is obtained based on the maximum bus voltage. And then, acquiring the current bus voltage in real time, judging whether the bus voltage is greater than the load reduction voltage, and if the bus voltage is greater than the load reduction voltage, reducing the power of the inverter 100 through the microprocessor chip so as to reduce the current signal and ensure that the stress borne by the inverter tube is within the stress range of the inverter tube. And then obtaining the protection current of the inverter, converting the protection current into protection voltage, and finally inputting the protection voltage to the positive end of a comparator inside the microprocessor. The microprocessor chip comprises at least two comparators, and the positive voltage signal and the negative voltage signal are respectively input into different comparators, so that the upper limit and the lower limit of the current signal can be set. And then obtaining a comparison result of the voltage signal and the protection voltage, and sending the comparison result to a processing module in a micro-processing chip, wherein the processing module generates a waveform signal based on the comparison result, and sends the waveform signal to a register in the micro-processing chip to pull down the drive of the register, so that a current signal of an inverter tube corresponding to the register is reduced, the stress of the inverter tube is reduced, and the inverter tube is protected from being damaged.
Wherein, as shown in fig. 2, the controller 30 includes at least one processor 31; a memory 32 to which the at least one processor 31 is communicatively connected.
Wherein the memory storage 32 stores instructions executable by the at least one processor 31, the instructions being executable by the at least one processor 31 to enable the at least one processor 31 to perform the method of reducing inverter tube stress as described below.
Memory 32, which is a non-volatile computer-readable storage medium, may be used to store non-volatile software programs, non-volatile computer-executable programs, and modules, such as program instructions/modules corresponding to the method of reducing inverter tube stress in embodiments of the present invention. The processor 31 executes various functional applications and data processing of the controller 30, i.e., implementing the method of reducing inverter tube stress in the method embodiments described below, by running non-volatile software programs, instructions, and modules stored in the memory 32.
The memory 32 may include a program storage area and a data storage area, wherein the program storage area may store an operating system, an application program required for at least one function. Further, the memory 32 may include high speed random access memory and may also include non-volatile memory. For example, at least one magnetic disk storage device, flash memory device, or other non-volatile solid state storage device. In some embodiments, the memory 32 may optionally include memory that is remotely located with respect to the processor 31.
The one or more modules are stored in the memory 32 and, when executed by the one or more processors 31, perform the method of reducing inverter tube stress in any of the method embodiments described above, e.g., performing the method steps of fig. 3 described below.
The controller 30 can execute the method provided by the embodiment of the present invention, and has a corresponding functional module for executing the method. For technical details that are not described in detail in this embodiment, reference may be made to the method provided in the embodiment of the present invention.
Referring to fig. 3, fig. 3 is a flowchart of a method for reducing stress of an inverter according to an embodiment of the present invention, as shown in fig. 3, the method includes:
s11, obtaining a first inversion current of the inversion tube.
In the working process of the inverter, there are many ways to obtain the first inversion current of the inverter tube. For example, the output current of the dc circuit, i.e. the inverter current of the inverter, may be collected by the controller. For another example, when the inverter includes a sampling module, the first inverter current may be obtained by the sampling module.
S12, load reduction voltage and first bus voltage of the inverter tube are obtained, when the first bus voltage is larger than the load reduction voltage, power of the inverter tube is reduced, and second inverter current of the inverter tube after the power is reduced is obtained.
When the inverter works, the first bus voltage and the load reduction voltage of the inverter are obtained in real time, and then the first bus voltage of the current inverter is compared with the load reduction voltage to judge whether the first bus voltage is larger than the load reduction voltage or not. When the first bus voltage is greater than the load reduction voltage, if the inverter is under the condition of sudden loading, the first inverter current of the inverter suddenly becomes very large, so that the stress borne by the inverter tube exceeds the stress of the inverter tube, and the inverter tube is damaged. Therefore, when the first bus voltage is greater than the load reduction voltage, in order to prevent the inverter current of the inverter from suddenly increasing and the stress borne by the inverter tube from exceeding the stress of the inverter tube, the power of the inverter tube needs to be reduced, so that the first inverter current of the inverter tube is reduced, and the stress borne by the inverter tube is ensured to be within the stress range of the inverter tube. Based on the method, the service life of the inverter tube is prolonged, and meanwhile, the cost of hardware is reduced.
The load reduction voltage is used for reducing the power of the inverter by reducing and adjusting the output duty ratio when the sum of the bus voltage and the inverter current exceeds the stress of the inverter tube, so that the stress born by the inverter tube is reduced while hardware is protected. Specifically, firstly, a safety voltage of the inverter tube is obtained, where the safety voltage indicates that the inverter tube can work normally within the safety voltage, and once the safety voltage is exceeded, the inverter tube may break down, so as to damage the inverter tube. And controlling the inverter to run fully based on the safe voltage, namely, under the condition that the safe voltage is not exceeded, enabling the output of the inverter to be optimal. For example, the operating voltage of the inverter is 500V, the safety voltage of the inverter tube is 650V, and if the voltage of the inverter is about 500V after the inverter power is increased to the full power, it is considered that the inverter is fully operated without exceeding the safety voltage. When the inverter runs fully, the output Maximum Power of the inverter is tracked in real time, namely, the Maximum Power Point Tracking (MPPT) of the inverter is controlled to track to the left normally. Referring to fig. 4, fig. 4 is a graph illustrating a maximum power point of an inverter according to an embodiment of the present invention. As shown in fig. 4, when the inverter runs fully, the MPPT can track from right to left normally, at this time, the bus voltage of the inverter is decreasing and the output power is increasing, and when the output power is maximum, the bus voltage of the inverter is about 500V, that is, when the bus voltage of the inverter is about 500V, the output power of the inverter is maximum power. And then, acquiring corresponding second bus voltage and third inverter current based on the maximum power point of the inverter, wherein at the moment, the second bus voltage and the third inverter current are also the load shedding point bus voltage and the maximum current of the inverter because the power of the inverter is maximum. And then obtaining the maximum stress of the inverter tube based on the second bus voltage and the third inverter current, wherein when the inverter works, the maximum stress of the inverter is obtained by adding a stress spike caused by the maximum current and the load shedding point bus voltage, that is, by obtaining a stress voltage spike corresponding to the third inverter current and calculating the sum of the stress voltage spike and the second bus voltage, the maximum stress of the inverter can be obtained. At the moment, the maximum stress spike is subtracted from the maximum stress of the inverter, and the load reduction voltage of the inverter tube can be obtained.
In some embodiments, please refer to fig. 5a, fig. 5a is a graph of a curve relationship between an inverter current and a stress spike according to an embodiment of the present invention, as shown in fig. 5a, a horizontal axis represents a charging current of the inverter tube, that is, an inverter current of the inverter tube; the vertical axis is the stress voltage peak of the inverter tube, and the relationship between the inverter current and the stress voltage peak can be known according to fig. 5 a. Preferably, when the bus voltage is 500V, a curve relation between the charging current and the stress of the inverter tube may be obtained based on a curve graph of the stress voltage spike, as shown in fig. 5b, where a horizontal axis represents the charging current of the inverter tube and a vertical axis represents the stress of the inverter tube.
And S13, acquiring an analog voltage according to the second inverter current, and acquiring a protection current of the inverter tube according to the load reduction voltage.
When the first bus voltage is larger than the load reduction voltage, the power of the inverter tube is reduced to reduce the first inverter current, and then the second inverter current with reduced power is obtained, wherein the second inverter current is smaller than the first inverter current. And then, obtaining an inversion voltage by passing the second inversion current through the sensor, wherein the inversion voltage is converted according to the inversion current, and the waveform of the inversion current output by the direct current circuit is a sine wave, that is, the current includes a positive current of a positive half shaft and a negative current of a negative half shaft, so that when the analog voltage is obtained, whether the inversion current corresponding to the analog voltage is the positive half shaft or the negative half shaft can be known according to the value of the analog voltage. Specifically, a reference voltage output by the sensor is obtained, and then the inverted voltage is compared with the reference voltage, so that the analog voltage can be obtained. When the value of the analog voltage is greater than the reference voltage, the inverter current corresponding to the analog voltage is considered as a positive half axis, and when the value of the analog voltage is less than the reference voltage, the inverter current corresponding to the analog voltage is considered as a negative half axis.
Further, a maximum current corresponding to the first bus voltage and a minimum current corresponding to the maximum bus voltage are obtained, and then a slope of the protection current is calculated based on the first bus voltage, the maximum current, the maximum bus voltage and the minimum current. And the maximum current is the third inverter current, and the maximum bus voltage is the second bus voltage. Then, the difference between the first bus voltage and the load reduction voltage is calculated, and the product of the difference and the slope is obtained. The inverter current includes positive and negative currents, so the third inverter current may also be a positive maximum current and a negative maximum current, and based on this, the upper and lower limit protection points of the inverter may be calculated according to the positive maximum current and the negative maximum current. Specifically, a gain value of the third inverter current is obtained according to the sensor, the third inverter current is converted into a corresponding digital value based on the gain value, and then the product is subtracted from the digital value converted by the third inverter current, so that an upper limit protection point of the inverter can be obtained; and adding the product to the digital value converted by the negative third inverter current so as to obtain the lower limit protection point of the inverter. Based on the upper limit protection point and the lower limit protection point, the protection current of the inverter can be obtained.
And S14, converting the protection current into protection voltage, and comparing the magnitude of the analog voltage with the magnitude of the protection voltage.
After the protection current is obtained, the protection current is converted into protection voltage through the sensor, and then the protection voltage is compared with the analog voltage, so that the magnitude of the analog voltage and the magnitude of the protection voltage are judged.
And S15, when the analog voltage is greater than the protection voltage, triggering the inverter tube to carry out wave-by-wave current limiting so as to reduce the stress of the inverter tube.
The wave-by-wave current limiting refers to monitoring the inversion current of the inversion tube in real time in the working process of the inverter, immediately closing the drive of the inversion tube in the current period once the inversion current exceeds the protection current, automatically enabling the drive until the next period, and continuously closing the drive of the inverter if the inversion current is still greater than the protection current in the next period, so that the inversion tube is protected. Specifically, the duty ratio of the inverter tube during normal operation is obtained, wherein the inverter is controlled by the duty ratio to operate, when the controller outputs a rectangular wave, the inverter starts to operate, and the controller adjusts the duty ratio of the waveform to adjust the output of the inverter, so that the inverter operates normally. When the analog voltage is smaller than the protection voltage, the controller maintains the duty ratio of the inverter unchanged, and acquires the inverter current of the inverter in real time based on the normally working inverter; and when the analog voltage is greater than the protection voltage, adjusting the duty ratio based on the comparison result to reduce the inversion current of the inversion tube, thereby reducing the stress of the inversion tube.
In some embodiments, please refer to fig. 6, fig. 6 is a graph illustrating a load reduction curve, a CBC protection curve and a charging power according to the present embodiment. Specifically, as can be seen from fig. 4, when the bus voltage of the inverter tube is about 500V, the power of the inverter is the maximum power, and at this time, the bus voltage is the maximum bus voltage, and the load reduction voltage of the inverter tube can be obtained based on the maximum bus voltage, where the load reduction voltage is about 500V. When the bus voltage acquired in real time is smaller than the load reduction and load reduction voltage, the output power of the inverter is kept, and once the bus voltage is larger than the load reduction voltage, the power of the inverter is immediately reduced, so that the inverter tube is protected. In practical application, due to the influence of ripple caused by hardware, corresponding allowance is reserved above the load reduction curve when the CBC protection curve is obtained, so that when the bus voltage is greater than the load reduction voltage, the current is reduced by the load reduction mode, and then the current is reduced by the protection curve.
The embodiment of the invention provides a method for reducing stress of a transverse tube of an inverter, which mainly comprises the steps of obtaining a first inversion current, a load reduction voltage and a first bus voltage of an inverter tube, then reducing the power of the inverter tube when the first bus voltage is greater than the load reduction voltage, obtaining a second inversion current of the inverter tube after the power is reduced, then obtaining an analog voltage according to the second inversion current, and obtaining a protection current of the inverter tube according to the load reduction voltage; and finally, when the analog voltage is greater than the protection voltage, triggering the inverter tube to carry out wave-by-wave current limiting so as to reduce the stress of the inverter tube. By the method, the limit of hardware does not need to be triggered all the time, so that the loss and the cost of the hardware are reduced, and the development period is shortened.
Referring to fig. 7, fig. 7 is a block diagram of a structure of a device for reducing stress of an inverter tube according to an embodiment of the present invention, and as shown in fig. 7, the device 400 for reducing stress of an inverter tube includes a current sampling module 41, an overvoltage load reduction module 42, an obtaining module 43, a comparing module 44, and a wave-by-wave current limiting module 45.
The current sampling module 41 is configured to obtain a first inversion current of the inversion tube.
The overvoltage and undervoltage loading module 42 is configured to obtain a undervoltage and a first bus voltage of the inverter tube, reduce the power of the inverter tube when the first bus voltage is greater than the undervoltage, and obtain a second inverter current of the inverter tube after the power is reduced.
The overload and load drop module 42 is specifically configured to:
obtaining the safe voltage of the inverter tube;
controlling the full-load operation of the inverter based on the safe voltage, and tracking the maximum power of the inverter in real time;
acquiring a second bus voltage and a third inverter current corresponding to the maximum power of the inverter;
acquiring a first stress of the inverter tube according to the second bus voltage and the third inverter current;
acquiring a stress peak of the inverter tube according to the third inverter current;
and acquiring the difference between the first stress and the stress peak, and setting the difference as the load reduction voltage of the inverter tube.
The obtaining module 43 is configured to obtain an analog voltage according to the second inverter current, and obtain a protection current of the inverter tube according to the step-down voltage.
Wherein, the obtaining module 43 is specifically configured to:
acquiring a second inversion current of the inversion tube, and converting the second inversion current into inversion voltage through the sensor;
acquiring a reference voltage output by the sensor;
and comparing the inverted voltage with the reference voltage to obtain the analog voltage of the inverter.
The comparing module 44 is configured to convert the protection current into a protection voltage, and compare the analog voltage with the protection voltage.
The wave-by-wave current limiting module 45 is configured to trigger the inverter tube to limit current wave-by-wave when the analog voltage is greater than the protection voltage, so as to reduce stress of the inverter tube.
It should be noted that the apparatus for reducing inverter tube stress can execute the method for reducing inverter tube stress provided by the embodiment of the present invention, and has corresponding functional modules and beneficial effects of the execution method. Technical details that are not described in detail in the embodiment of the apparatus for reducing inverter tube stress may be referred to the method for reducing inverter tube stress provided by the embodiment of the present invention.
Embodiments of the present invention also provide a non-transitory computer-readable storage medium storing computer-executable instructions for execution by one or more inverters, e.g., to perform the method steps of fig. 3 described above, to implement the functions of the modules in fig. 7.
Through the above description of the embodiments, those skilled in the art will clearly understand that each embodiment can be implemented by software plus a general hardware platform, and certainly can also be implemented by hardware. Those skilled in the art will appreciate that all or part of the processes in the methods of the embodiments described above can be implemented by hardware related to instructions of a computer program, and the computer program can be stored in a computer readable storage medium, and when executed, the computer program can include the processes of the embodiments of the methods described above. The storage medium may be a magnetic disk, an optical disk, a Read-Only Memory (ROM), a Random Access Memory (RAM), or the like.
Finally, it should be noted that: the above examples are only intended to illustrate the technical solution of the present invention, but not to limit it; within the idea of the invention, also technical features in the above embodiments or in different embodiments may be combined, steps may be implemented in any order, and there are many other variations of the different aspects of the invention as described above, which are not provided in detail for the sake of brevity; although the present invention has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some technical features may be equivalently replaced; and the modifications or the substitutions do not make the essence of the corresponding technical solutions depart from the scope of the technical solutions of the embodiments of the present invention.
Claims (10)
1. The method for reducing the stress of the inverter tube is applied to the inverter and is characterized by comprising the following steps:
acquiring a first inverter current of an inverter tube;
the method comprises the steps of obtaining load reduction voltage and first bus voltage of an inverter tube, reducing power of the inverter tube when the first bus voltage is larger than the load reduction voltage, and obtaining second inverter current of the inverter tube after the power is reduced;
acquiring an analog voltage according to the second inverter current, and acquiring a protection current of the inverter tube according to the load reduction voltage;
converting the protection current into a protection voltage, and comparing the magnitude of the analog voltage with the magnitude of the protection voltage;
and when the analog voltage is greater than the protection voltage, triggering the inverter tube to carry out wave-by-wave current limiting so as to reduce the stress of the inverter tube.
2. The method of claim 1, wherein the obtaining the load reduction voltage of the inverter tube comprises:
obtaining the safe voltage of the inverter tube;
controlling the full-load operation of the inverter based on the safe voltage, and tracking the maximum power of the inverter in real time;
acquiring a second bus voltage and a third inverter current corresponding to the maximum power of the inverter;
obtaining the stress of the inverter tube according to the second bus voltage and the third inverter current;
obtaining a stress spike of the inverter tube according to the third inverter current;
and acquiring the difference between the stress and the stress spike, and setting the difference as the load reduction voltage of the inverter tube.
3. The method of claim 2, wherein the inverter further comprises a sensor, and wherein the obtaining an analog voltage from the second inverter current comprises:
acquiring a second inversion current of the inversion tube, and converting the second inversion current into inversion voltage through the sensor;
acquiring a reference voltage output by the sensor;
and comparing the inverted voltage with the reference voltage to obtain the analog voltage of the inverter.
4. The method according to claim 3, wherein the obtaining of the protection current of the inverter tube according to the reduced load voltage comprises:
acquiring the slope of the protection current according to the load reduction voltage and the first bus voltage;
acquiring a difference value between the first bus voltage and the load shedding voltage;
and calculating the protection current of the inverter tube according to the difference value, the third inverter current and the slope.
5. The method of claim 4, wherein the triggering the inverter tube wave-by-wave current limiting comprises:
acquiring the duty ratio of the inverter tube in normal operation;
obtaining a comparison result of the analog voltage and the protection voltage;
when the analog voltage is smaller than the protection voltage, maintaining the duty ratio of the inverter tube, and acquiring the inverter current of the inverter tube in real time;
and when the analog voltage is greater than the protection voltage, adjusting the duty ratio of the inverter tube to reduce a second inverter current of the inverter tube.
6. The utility model provides a reduce device of contravariant pipe stress, is applied to the inverter, its characterized in that, the device includes:
the current sampling module is used for acquiring a first inversion current of the inversion tube;
the over-voltage load reduction module is used for obtaining load reduction voltage and first bus voltage of the inverter tube, reducing the power of the inverter tube when the first bus voltage is greater than the load reduction voltage, and obtaining second inverter current of the inverter tube after the power is reduced;
the acquisition module is used for acquiring analog voltage according to the second inverter current and acquiring protection current of the inverter tube according to the load reduction voltage;
the comparison module is used for converting the protection current into protection voltage and comparing the analog voltage with the protection voltage;
and the wave-by-wave current limiting module is used for triggering the inverter tube to carry out wave-by-wave current limiting when the analog voltage is greater than the protection voltage so as to reduce the stress of the inverter tube.
7. The apparatus of claim 6, wherein the overload-drop load module is specifically configured to:
obtaining the safe voltage of the inverter tube;
controlling the full-load operation of the inverter based on the safe voltage, and tracking the maximum power of the inverter in real time;
acquiring a second bus voltage and a third inverter current corresponding to the maximum power of the inverter;
acquiring a first stress of the inverter tube according to the second bus voltage and the third inverter current;
acquiring a stress peak of the inverter tube according to the third inverter current;
and acquiring the difference between the first stress and the stress peak, and setting the difference as the load reduction voltage of the inverter tube.
8. The apparatus of claim 6 or 7, wherein the inverter further comprises a sensor, and the acquisition module is specifically configured to:
acquiring a second inversion current of the inversion tube, and converting the second inversion current into inversion voltage through the sensor;
acquiring a reference voltage output by the sensor;
and comparing the inverted voltage with the reference voltage to obtain the analog voltage of the inverter.
9. An inverter, characterized in that the inverter comprises:
a controller;
a DC circuit;
an inverter circuit; and a dc bus connecting the dc circuit with the inverter;
wherein the controller comprises at least one processor; and the number of the first and second groups,
a memory communicatively coupled to the at least one processor; wherein the content of the first and second substances,
the memory stores instructions executable by the at least one processor to enable the at least one processor to perform the method of any one of claims 1-5.
10. A non-transitory computer-readable storage medium storing computer-executable instructions for causing an inverter to perform the method of any one of claims 1-5.
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