CN114759769A - Current sampling method and device and inversion equipment - Google Patents
Current sampling method and device and inversion equipment Download PDFInfo
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- CN114759769A CN114759769A CN202210475691.5A CN202210475691A CN114759769A CN 114759769 A CN114759769 A CN 114759769A CN 202210475691 A CN202210475691 A CN 202210475691A CN 114759769 A CN114759769 A CN 114759769A
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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
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R19/00—Arrangements for measuring currents or voltages or for indicating presence or sign thereof
- G01R19/003—Measuring mean values of current or voltage during a given time interval
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R19/00—Arrangements for measuring currents or voltages or for indicating presence or sign thereof
- G01R19/25—Arrangements for measuring currents or voltages or for indicating presence or sign thereof using digital measurement techniques
- G01R19/2506—Arrangements for conditioning or analysing measured signals, e.g. for indicating peak values ; Details concerning sampling, digitizing or waveform capturing
- G01R19/2509—Details concerning sampling, digitizing or waveform capturing
Abstract
The invention provides a current sampling method, a current sampling device and inversion equipment. The method comprises the following steps: when a first carrier point of a carrier of a PWM unit corresponding to a target load device in a target PWM period is detected, sampling the load current of the target load device according to the moment of the first carrier point to obtain a first current sampling value; the first carrier point is any one carrier point of a carrier in the first half period of the target PWM period; when a second carrier point in the target PWM period is detected, sampling the load current according to the moment of the second carrier point to obtain a second current sampling value; the second carrier point is a carrier point which is half of a target PWM period away from the first carrier point; and determining the average value of the first current sampling value and the second current sampling value as the sampling value of the load current. The invention can eliminate the influence of the switch ripple on current sampling and improve the accuracy of current sampling.
Description
Technical Field
The invention relates to the technical field of electric signal sampling, in particular to a current sampling method, a current sampling device and inversion equipment.
Background
In PWM (Pulse Width Modulation) control, an output waveform of a bridge circuit is a high-frequency square wave, and a filter circuit is required to continuously output the waveform. Limited by the requirements of cost and size, the number of selectable filter circuits is small, and the filter circuit cannot provide good filtering capability, so that the switching-level interference signals cannot be completely filtered, and high-frequency components, such as switching ripples, exist in the output voltage or the output current at the load end. These high frequency components greatly reduce the accuracy of the current sampling, which in turn will reduce the PWM control effect.
Disclosure of Invention
The embodiment of the invention provides a current sampling method, a current sampling device and inversion equipment, and aims to solve the problem that the accuracy of current sampling caused by switching ripples is low in the prior art.
In a first aspect, an embodiment of the present invention provides a current sampling method, including:
when a first carrier point of a carrier of a PWM unit corresponding to target load equipment in a target PWM period is detected, sampling the load current of the target load equipment according to the moment of the first carrier point to obtain a first current sampling value; the first carrier point is any one carrier point of a carrier in the first half period of the target PWM period;
When a second carrier point in the target PWM period is detected, sampling the load current according to the moment of the second carrier point to obtain a second current sampling value; the second carrier point is a carrier point which is half of a target PWM period away from the first carrier point;
and determining the average value of the first current sampling value and the second current sampling value as the sampling value of the load current.
In one possible implementation manner, sampling a load current of a target load device according to a time of a first carrier point to obtain a first current sample value includes:
sampling a current value corresponding to the moment of the first carrier point in the load current into a first current sampling value;
sampling the load current of the target load device according to the moment of the second carrier point to obtain a second current sampling value, wherein the sampling comprises the following steps:
and sampling a current value corresponding to the moment of the second carrier point in the load current to obtain a second current sampling value.
In one possible implementation manner, sampling a load current of a target load device according to a time of a first carrier point to obtain a first current sample value includes:
sampling a current value corresponding to a first moment in the load current into a first current sampling value; the first moment is the sum of the moment of the first carrier point and a preset lag time, and the preset lag time is the delay time of the load current relative to the carrier;
Sampling the load current of the target load device according to the moment of the second carrier point to obtain a second current sampling value, wherein the sampling comprises the following steps:
sampling a current value corresponding to the second moment in the load current into a second current sampling value; and the second moment is the sum of the moment of the second carrier point and a preset lag time.
In a possible implementation manner, the carrier wave is an isosceles triangle wave, the first carrier point is a starting point of the isosceles triangle wave, and the second carrier point is a highest point of the isosceles triangle wave.
In a possible implementation manner, the carrier wave is a right-angle triangular wave, the first carrier point is a starting point of the right-angle triangular wave, and the second carrier point is a midpoint between the starting point and a highest point of the right-angle triangular wave.
In one possible implementation, the target load is a capacitive load or an inductive load.
In a second aspect, an embodiment of the present invention provides a current sampling apparatus, including:
the first sampling module is used for sampling the load current of the target load equipment according to the moment of a first carrier point when the first carrier point of the carrier of the PWM unit corresponding to the target load equipment in the target PWM period is detected, so as to obtain a first current sampling value; the first carrier point is any one carrier point of a carrier in the first half period of the target PWM period;
The second sampling module is used for sampling the load current according to the moment of a second carrier point when the second carrier point in the target PWM period is detected to obtain a second current sampling value; the second carrier point is a carrier point which is separated from the first carrier point by half of a target PWM period;
and the sampling value determining module is used for determining the average value of the first current sampling value and the second current sampling value as the sampling value of the load current.
In a possible implementation manner, the first sampling module is specifically configured to:
sampling a current value corresponding to the moment of the first carrier point in the load current into a first current sampling value;
the second sampling module is specifically configured to:
and sampling a current value corresponding to the moment of the second carrier point in the load current into a second current sampling value.
In a possible implementation manner, the first sampling module is specifically configured to:
sampling a current value corresponding to a first moment in the load current into a first current sampling value; the first moment is the sum of the moment of the first carrier point and a preset lag time, and the preset lag time is the delay time of the load current relative to the carrier;
the second sampling module is specifically configured to:
Sampling a current value corresponding to the second moment in the load current into a second current sampling value; and the second moment is the sum of the moment of the second carrier point and the preset lag time.
In a possible implementation manner, the carrier wave is an isosceles triangle wave, the first carrier point is a starting point of the isosceles triangle wave, and the second carrier point is a highest point of the isosceles triangle wave.
In a possible implementation manner, the carrier is a right-angle triangular wave, the first carrier point is a starting point of the right-angle triangular wave, and the second carrier point is a midpoint between the starting point and a highest point of the right-angle triangular wave.
In one possible implementation, the target load is a capacitive load or an inductive load.
In a third aspect, an embodiment of the present invention provides an inverter device, which includes a memory, a processor, and a computer program stored in the memory and executable on the processor, and when the processor executes the computer program, the steps of the method according to the first aspect are implemented.
The embodiment of the invention provides a current sampling method, a current sampling device and inverter equipment, wherein when a first carrier point of a carrier of a PWM unit corresponding to target load equipment in a target PWM period is detected, the load current of the target load equipment is sampled according to the moment of the first carrier point to obtain a first current sampling value; and when a second carrier point in the target PWM period is detected, sampling the load current according to the moment of the second carrier point to obtain a second current sampling value. Because the first carrier point and the second carrier point are set to be separated by half a target PWM period, when the first current sampling value and the second current sampling value are averaged, the switch ripple in the first current sampling value and the second current sampling value can be offset just, thereby avoiding the influence of the switch ripple on the accuracy of current sampling, greatly improving the accuracy of current sampling and further improving the control effect of PWM.
Drawings
In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings needed to be used in the embodiments or the prior art descriptions 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 based on these drawings without inventive exercise.
FIG. 1 is a flow chart illustrating steps of a current sampling method according to an embodiment of the present invention;
fig. 2 is a schematic diagram of a first carrier point and a second carrier point according to an embodiment of the present invention;
fig. 3 is a schematic diagram of another first carrier point and a second carrier point provided by an embodiment of the invention;
fig. 4 is a schematic structural diagram of a current sampling apparatus according to an embodiment of the present invention;
fig. 5 is a schematic diagram of an inverter according to an embodiment of the present invention.
Detailed Description
In the following description, for purposes of explanation and not limitation, specific details are set forth, such as particular system structures, techniques, etc. in order to provide a thorough understanding of the embodiments of the invention. It will be apparent, however, to one skilled in the art that the present invention may be practiced in other embodiments that depart from these specific details. In other instances, detailed descriptions of well-known systems, devices, circuits, and methods are omitted so as not to obscure the description of the present invention with unnecessary detail.
To make the objects, technical solutions and advantages of the present invention more apparent, the following description will be made by way of specific embodiments with reference to the accompanying drawings.
As described in the background art, for devices that are limited by cost and size requirements, there are few selectable filter circuits, and generally, conventional filter circuits with low cost and small size are not capable of providing good filtering capability, so that the switch-level interference signals cannot be completely filtered out, resulting in high-frequency components such as switch ripples existing in the output voltage or output current at the load end. These high frequency components will greatly reduce the accuracy of the current sampling, which in turn will reduce the control effect of the PWM. Especially when the load is a capacitive load, the high-frequency impedance of the capacitive load is small, so that the high-frequency component in the load current is more obvious, and the accuracy of current sampling is further reduced.
In addition, the existing current sampling method has the problem of inaccurate sampling. Specifically, a current sampling method commonly used in the industry at present is to sample once in a PWM period, that is, a current value corresponding to a midpoint of a load current in the PWM period is determined as a sampled current value, but the sampling method ignores a phase shift change caused by a filter circuit in a load circuit, and the phase shift change cannot be accurately calculated, so that when the sampling is performed according to the midpoint of the PWM period, an obtained sampled current value is not a current value actually corresponding to the midpoint of the PWM period, and thus the sampled current value is not an average value of the load current, and the sampling is not accurate. In addition, the current sampling method is influenced by the switching ripple during sampling, and the accuracy of current sampling is further reduced.
In order to solve the problems in the prior art, embodiments of the present invention provide a current sampling method, a current sampling device, and an inverter device. The current sampling method provided by the embodiment of the invention is described below.
The main body of the current sampling method may be a current sampling device, such as an inverter including a sampling circuit, which is not specifically limited in the embodiments of the present invention.
Referring to fig. 1, it shows a flowchart of an implementation of a current sampling method provided by an embodiment of the present invention, including the following steps:
In some embodiments, the target load device may be any load device employing an inverter, for example the target load device may be a capacitive load or an inductive load. The target PWM period may be any one of PWM periods, and the carrier wave may be an isosceles triangle wave or a right triangle wave.
Optionally, in step 110, the processing of sampling the load current of the target load device at the time according to the first carrier point to obtain a first current sampling value may specifically be as follows: and sampling a current value corresponding to the moment of the first carrier point in the load current into a first current sampling value.
Specifically, when the first carrier point is detected, the detection time, that is, the time of the first carrier point, may be recorded. Then, sampling may be performed at the detection time, and a current value corresponding to the detection time in the load current may be sampled as a first current sample value.
Optionally, considering that some load currents have a delay with respect to the carrier, for such a case, the process of sampling the load current of the target load device at the time according to the first carrier point in step 110 to obtain the first current sample value may specifically be as follows: sampling a current value corresponding to a first moment in the load current into a first current sampling value; the first moment is the sum of the moment of the first carrier point and a preset hysteresis duration, and the preset hysteresis duration is the delay duration of the load current relative to the carrier.
Specifically, when the first carrier point is detected, the detection time, that is, the time of the first carrier point, may be recorded. Then, sampling may be performed according to a time of a sum of the detection time and a preset hysteresis time, that is, a first time, and a current value corresponding to the first time in the load current may be sampled as a first current sample value.
It should be noted that the delay of the load current with respect to the carrier can be accurately calculated, and is usually a PWM period, and accordingly, the preset delay time can be set to be a PWM period. Of course, the delay may be detected in advance, and then the detected delay time length is used as the preset delay time length.
In some embodiments, considering that the accuracy of some PWM counters is limited, a point easy to detect may be selected as the first carrier point, such as a starting point of a carrier, a midpoint of a carrier, etc., according to the accuracy of the PWM counter.
In some embodiments, in the case of using an isosceles triangular wave as the carrier, the first carrier point may be set as a starting point of the isosceles triangular wave, and accordingly, a point which is half the target PWM period away from the first carrier point is just the highest point of the isosceles triangular wave, i.e., the second carrier point. As shown in fig. 2, a schematic diagram of a first carrier point and a second carrier point is shown, in fig. 2, reference numeral 21 is the first carrier point, and reference numeral 22 is the second carrier point.
It should be noted that other carrier points convenient for detection may also be selected, for example, a carrier point corresponding to a quarter of the target PWM period in an isosceles triangle wave, a carrier point corresponding to a fifth of the target PWM period in the isosceles triangle wave, and the like.
In some embodiments, in the case of using a right-angle triangular wave as the carrier, such as a right-angle triangular wave with a waveform having a sequentially increasing amplitude from left to right, the first carrier point may be set as a starting point of the right-angle triangular wave, and a point which is separated from the first carrier point by half of the target PWM period is just a midpoint between the starting point and a highest point of the right-angle triangular wave. Correspondingly, for the right-angle triangular wave with the wave form gradually decreasing from left to right in amplitude, the first carrier point can be set as the starting point of the right-angle triangular wave, and the point which is half of the target PWM period away from the first carrier point is just the middle point between the starting point and the lowest point of the right-angle triangular wave. As shown in fig. 3, a schematic diagram of a first carrier point and a second carrier point is shown, and in fig. 3, reference numeral 31 is the first carrier point and reference numeral 32 is the second carrier point.
It should be noted that other carrier points convenient for detection may also be selected, for example, a carrier point corresponding to a quarter of the target PWM period in the right-angle triangular wave, a carrier point corresponding to a fifth of the target PWM period in the right-angle triangular wave, and the like.
In some embodiments, similar to the above-described processing of the first current sample value, when the second carrier point is detected, the detection time instant, i.e. the time instant of the second carrier point, may be recorded. Then, sampling may be performed at the detection time, and a current value corresponding to the detection time in the load current may be sampled as a second current sample value. In addition, for the case where the load current is delayed with respect to the carrier, sampling may be performed at a second time that is a time when the sum of the detection time of the second carrier point and a preset delay time period is added, and a current value corresponding to the second time in the load current may be sampled as a second current sample value.
And step 130, determining the average value of the first current sampling value and the second current sampling value as the sampling value of the load current.
After the first and second current samples are obtained, an average of the first and second current samples is calculated and determined as the sample of the load current of the target load device.
It should be noted that, when the first current sample value and the second current sample value obtained by sampling according to the above sampling method are averaged, the switching ripples in the first current sample value and the second current sample value can be exactly cancelled. The following describes the cancellation process of the switching ripple in detail.
The switching ripple may be expressed in the form:
accordingly, the switching ripple component in the first current sample may be expressed as:
the switching ripple component in the second current sample value may be expressed as:
based on the above, when the first current sample and the second current sample are added and averaged, the following results can be obtained for the switching ripple component:
it can be seen that the switching ripples in the first and second current sample values exactly cancel each other out. Therefore, according to the sampling mode provided by the embodiment of the invention, the switching ripples can be counteracted, and the influence of the switching ripples on the accuracy of current sampling is avoided, so that the accuracy of current sampling is greatly improved, and the control effect of PWM is further improved.
It should be noted that, in the sampling manner provided by the embodiment of the present invention, a phase shift change caused by a filter circuit in a load circuit does not need to be considered, because in the sampling process, in the embodiment of the present invention, it is not needed to accurately find a current value corresponding to a midpoint of a load current in a PWM period, in the embodiment of the present invention, sampling is performed only twice in one PWM period, an interval between two sampling is a half period, and then an average value of two sampling results is obtained, so that an average value of the load current can be obtained. That is to say, the existing sampling method cannot find the accurate midpoint of the load current in the PWM period, but the embodiment of the present invention bypasses the obstacle of finding the inaccurate midpoint from another angle, and not only can sample the average value of the load current, but also can cancel the switching ripple.
It should be noted that, because the current sampling method provided by the embodiment of the present invention can cancel the switching ripple in the sampling result, for the devices that are limited by the requirements of cost and size, even if the filtering effect of the filtering circuit is general or poor, the sampling accuracy can be very high. In addition, the current sampling mode provided by the embodiment of the invention only needs to sample twice in one PMW period, has low requirements on chip processing resources, does not prolong the time of program interruption, and has the advantage of low landing difficulty.
In the embodiment of the invention, a current sampling mode by using a carrier point is provided, that is, when a first carrier point of a carrier of a PWM unit corresponding to a target load device in a target PWM cycle is detected, a load current of the target load device is sampled according to a time of the first carrier point to obtain a first current sampling value; and when a second carrier point in the target PWM period is detected, sampling the load current according to the moment of the second carrier point to obtain a second current sampling value. Because the first carrier point and the second carrier point are set to be separated by half a target PWM period, when the first current sampling value and the second current sampling value are averaged, the switch ripples in the first current sampling value and the second current sampling value can be offset just, thereby avoiding the influence of the switch ripples on the accuracy of current sampling, greatly improving the accuracy of current sampling and further improving the control effect of PWM.
It should be understood that, the sequence numbers of the steps in the foregoing embodiments do not imply an execution sequence, and the execution sequence of each process should be determined by functions and internal logic of the process, and should not limit the implementation process of the embodiments of the present invention in any way.
The following are embodiments of the apparatus of the invention, reference being made to the corresponding method embodiments described above for details which are not described in detail therein.
Fig. 4 shows a schematic structural diagram of a current sampling apparatus provided in an embodiment of the present invention, and for convenience of description, only the parts related to the embodiment of the present invention are shown, and the details are as follows:
as shown in fig. 4, the current sampling device includes:
the first sampling module 410 is configured to, when a first carrier point of a carrier of a PWM unit corresponding to a target load device in a target PWM cycle is detected, sample a load current of the target load device according to a time of the first carrier point to obtain a first current sampling value; the first carrier point is any one carrier point of a carrier in the first half period of the target PWM period;
the second sampling module 420 is configured to, when a second carrier point in the target PWM period is detected, sample the load current according to a time of the second carrier point to obtain a second current sampling value; the second carrier point is a carrier point which is separated from the first carrier point by half of a target PWM period;
The sample value determination module 430 is configured to determine an average of the first current sample value and the second current sample value as the load current sample value.
In a possible implementation manner, the first sampling module is specifically configured to:
sampling a current value corresponding to the moment of the first carrier point in the load current into a first current sampling value;
correspondingly, the second sampling module is specifically configured to:
and sampling a current value corresponding to the moment of the second carrier point in the load current into a second current sampling value.
In a possible implementation manner, the first sampling module is specifically configured to:
sampling a current value corresponding to a first moment in the load current into a first current sampling value; the first moment is the sum of the moment of the first carrier point and a preset lag time, and the preset lag time is the delay time of the load current relative to the carrier;
correspondingly, the second sampling module is specifically configured to:
sampling a current value corresponding to the second moment in the load current into a second current sampling value; and the second moment is the sum of the moment of the second carrier point and a preset lag time.
In a possible implementation manner, the carrier wave is an isosceles triangle wave, the first carrier point is a starting point of the isosceles triangle wave, and the second carrier point is a highest point of the isosceles triangle wave.
In a possible implementation manner, the carrier is a right-angle triangular wave, the first carrier point is a starting point of the right-angle triangular wave, and the second carrier point is a midpoint between the starting point and a highest point of the right-angle triangular wave.
In one possible implementation, the target load is a capacitive load or an inductive load.
In the embodiment of the invention, a current sampling mode by using a carrier point is provided, that is, when a first carrier point of a carrier of a PWM unit corresponding to a target load device in a target PWM cycle is detected, a load current of the target load device is sampled according to a time of the first carrier point to obtain a first current sampling value; and when a second carrier point in the target PWM period is detected, sampling the load current according to the moment of the second carrier point to obtain a second current sampling value. Because the first carrier point and the second carrier point are set to be separated by half a target PWM period, when the first current sampling value and the second current sampling value are averaged, the switch ripples in the first current sampling value and the second current sampling value can be offset just, thereby avoiding the influence of the switch ripples on the accuracy of current sampling, greatly improving the accuracy of current sampling and further improving the control effect of PWM.
Fig. 5 is a schematic diagram of an inverter device 5 according to an embodiment of the present invention. As shown in fig. 5, the inverter device 5 of this embodiment includes: a processor 50, a memory 51 and a computer program 52 stored in said memory 51 and executable on said processor 50. The processor 50, when executing the computer program 52, implements the steps in the various current sampling method embodiments described above, such as steps 110-150 shown in fig. 1. Alternatively, the processor 50, when executing the computer program 52, implements the functions of the modules in the above-mentioned device embodiments, such as the functions of the modules 410 to 450 shown in fig. 4.
Illustratively, the computer program 52 may be partitioned into one or more modules that are stored in the memory 51 and executed by the processor 50 to implement the present invention. The one or more modules may be a series of computer program instruction segments capable of performing specific functions, which are used to describe the execution process of the computer program 52 in the inverter device 5. For example, the computer program 52 may be divided into the modules 410 to 450 shown in fig. 4.
The inverter device 5 may include, but is not limited to, a processor 50 and a memory 51. It will be understood by those skilled in the art that fig. 5 is merely an example of the inverter device 5, and does not constitute a limitation of the inverter device 5, and may include more or less components than those shown, or combine some components, or different components, for example, the inverter device may further include a power module, an inverter module, a rectifier module, and the like.
The Processor 50 may be a Central Processing Unit (CPU), other general purpose Processor, a Digital Signal Processor (DSP), an Application Specific Integrated Circuit (ASIC), a Field Programmable Gate Array (FPGA) or other Programmable logic device, discrete Gate or transistor logic, discrete hardware components, etc. A general purpose processor may be a microprocessor or the processor may be any conventional processor or the like.
The memory 51 may be an internal storage unit of the inverter device 5, such as a hard disk or a memory of the inverter device 5. The memory 51 may also be an external storage device of the inverter device 5, such as a plug-in hard disk, a Smart Media Card (SMC), a Secure Digital (SD) Card, a Flash memory Card (Flash Card), or the like, provided on the inverter device 5. Further, the memory 51 may also include both an internal storage unit and an external storage device of the inverter device 5. The memory 51 is used to store the computer program and other programs and data required by the inverter device. The memory 51 may also be used to temporarily store data that has been output or is to be output.
It should be clear to those skilled in the art that, for convenience and simplicity of description, the foregoing division of the functional units and modules is only used for illustration, and in practical applications, the above function distribution may be performed by different functional units and modules as needed, that is, the internal structure of the apparatus may be divided into different functional units or modules to perform all or part of the above described functions. Each functional unit and module in the embodiments may be integrated in one processing unit, or each unit may exist alone physically, or two or more units are integrated in one unit, and the integrated unit may be implemented in a form of hardware, or in a form of software functional unit. In addition, specific names of the functional units and modules are only used for distinguishing one functional unit from another, and are not used for limiting the protection scope of the present application. For the specific working processes of the units and modules in the system, reference may be made to the corresponding processes in the foregoing method embodiments, which are not described herein again.
In the above embodiments, the description of each embodiment has its own emphasis, and reference may be made to the related description of other embodiments for parts that are not described or recited in any embodiment.
Those of ordinary skill in the art will appreciate that the various illustrative elements and algorithm steps described in connection with the embodiments disclosed herein may be implemented as electronic hardware, or combinations of computer software and electronic hardware. Whether such functionality is implemented as hardware or software depends upon the particular application and design constraints imposed on the technical solution. Skilled artisans may implement the described functionality in varying ways for each particular application, but such implementation decisions should not be interpreted as causing a departure from the scope of the present invention.
In the embodiments provided in the present invention, it should be understood that the disclosed apparatus/terminal device and method may be implemented in other ways. For example, the above-described embodiments of the apparatus/terminal device are merely illustrative, and for example, the division of the modules or units is only one type of logical function division, and other division manners may be available in actual implementation, for example, multiple units or components may be combined or integrated into another system, or some features may be omitted, or not executed. In addition, the shown or discussed mutual coupling or direct coupling or communication connection may be through some interfaces, indirect coupling or communication connection of devices or units, and may be in an electrical, mechanical or other form.
The units described as separate parts may or may not be physically separate, and parts displayed as units may or may not be physical units, may be located in one position, or may be distributed on multiple network units. Some or all of the units can be selected according to actual needs to achieve the purpose of the solution of the embodiment.
In addition, functional units in the embodiments of the present invention may be integrated into one processing unit, or each unit may exist alone physically, or two or more units are integrated into one unit. The integrated unit can be realized in a form of hardware, and can also be realized in a form of a software functional unit.
The integrated module, if implemented in the form of a software functional unit and sold or used as a stand-alone product, may be stored in a computer readable storage medium. Based on such understanding, all or part of the flow in the method according to the above embodiments may be implemented by a computer program, which may be stored in a computer readable storage medium and used by a processor to implement the steps of the current sampling method embodiments. Wherein the computer program comprises computer program code, which may be in the form of source code, object code, an executable file or some intermediate form, etc. The computer-readable medium may include: any entity or device capable of carrying the computer program code, recording medium, usb disk, removable hard disk, magnetic disk, optical disk, computer Memory, Read-Only Memory (ROM), Random Access Memory (RAM), electrical carrier wave signals, telecommunications signals, software distribution medium, and the like.
The above-mentioned embodiments are only used to illustrate the technical solution of the present invention, and not to limit the same; although the present invention has been described in detail with reference to the foregoing embodiments, it should 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; such modifications and substitutions do not depart from the spirit and scope of the embodiments of the present invention, and they should be construed as being included therein.
Claims (10)
1. A method of sampling current, comprising:
when a first carrier point of a carrier of a PWM unit corresponding to a target load device in a target PWM period is detected, sampling the load current of the target load device according to the moment of the first carrier point to obtain a first current sampling value; the first carrier point is any one carrier point of the carrier in the first half period of the target PWM period;
when a second carrier point in the target PWM period is detected, sampling the load current according to the moment of the second carrier point to obtain a second current sampling value; wherein the second carrier point is a carrier point half the target PWM period away from the first carrier point;
Determining an average of the first current sample and the second current sample as the sample of the load current.
2. The method for sampling current according to claim 1, wherein the sampling load current of the target load device according to the time of the first carrier point to obtain a first current sample value comprises:
sampling a current value corresponding to the moment of the first carrier point in the load current into a first current sampling value;
the sampling the load current of the target load device according to the time of the second carrier point to obtain a second current sampling value includes:
and sampling a current value corresponding to the moment of the second carrier point in the load current into the second current sampling value.
3. The method for sampling current according to claim 1, wherein the sampling load current of the target load device according to the time of the first carrier point to obtain a first current sample value comprises:
sampling a current value corresponding to a first moment in the load current into a first current sampling value; the first time is the sum of the time of the first carrier point and a preset hysteresis time, wherein the preset hysteresis time is the delay time of the load current relative to the carrier;
The sampling the load current of the target load device according to the time of the second carrier point to obtain a second current sampling value includes:
sampling a current value corresponding to a second moment in the load current into a second current sampling value; and the second moment is the sum of the moment of the second carrier point and a preset lag time.
4. The current sampling method according to any one of claims 1 to 3, wherein the carrier wave is an isosceles triangle wave, the first carrier point is a starting point of the isosceles triangle wave, and the second carrier point is a highest point of the isosceles triangle wave.
5. The current sampling method according to any one of claims 1 to 3, wherein the carrier is a right-angle triangle wave, the first carrier point is a starting point of the right-angle triangle wave, and the second carrier point is a midpoint between the starting point and a highest point of the right-angle triangle wave.
6. The current sampling method according to any one of claims 1 to 3, wherein the target load is a capacitive load or an inductive load.
7. A current sampling device, comprising:
the device comprises a first sampling module, a second sampling module and a control module, wherein the first sampling module is used for sampling the load current of target load equipment according to the moment of a first carrier point when the first carrier point of the carrier of a PWM unit corresponding to the target load equipment in a target PWM cycle is detected to obtain a first current sampling value; the first carrier point is any one carrier point of the carrier in the first half period of the target PWM period;
The second sampling module is used for sampling the load current according to the moment of a second carrier point when the second carrier point in the target PWM period is detected, so as to obtain a second current sampling value; wherein the second carrier point is a carrier point half the target PWM period away from the first carrier point;
and the sampling value determining module is used for determining the average value of the first current sampling value and the second current sampling value as the sampling value of the load current.
8. The current sampling device of claim 7, wherein the first sampling module is specifically configured to:
sampling a current value corresponding to the moment of the first carrier point in the load current into a first current sampling value;
the second sampling module is specifically configured to:
and sampling a current value corresponding to the moment of the second carrier point in the load current into the second current sampling value.
9. The current sampling device of claim 7, wherein the first sampling module is specifically configured to:
sampling a current value corresponding to a first moment in the load current into the first current sampling value; the first time is the sum of the time of the first carrier point and a preset hysteresis time, wherein the preset hysteresis time is the delay time of the load current relative to the carrier;
The second sampling module is specifically configured to:
sampling a current value corresponding to a second moment in the load current into a second current sampling value; and the second moment is the sum of the moment of the second carrier point and a preset lag time.
10. An inversion device comprising a memory, a processor and a computer program stored in the memory and executable on the processor, characterized in that the processor implements the steps of the method according to any one of claims 1 to 6 when executing the computer program.
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| CN202210475691.5A CN114759769A (en) | 2022-04-29 | 2022-04-29 | Current sampling method and device and inversion equipment |
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