CN113659859A - Analog sine wave modulation method of off-grid inverter and storage medium - Google Patents
Analog sine wave modulation method of off-grid inverter and storage medium Download PDFInfo
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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
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Abstract
The invention relates to the technical field of inverters, and provides a sine wave simulation modulation method and a storage medium of an off-grid inverter.
Description
Technical Field
The invention relates to the technical field of inverters, in particular to a method for modulating an analog sine wave of an off-grid inverter and a storage medium.
Background
The inverter functions as a device that converts direct current electrical energy (batteries, battery cells) to alternating current (typically 220v50HZ sinusoidal or square wave). Conventionally, an inverter is a device that converts Direct Current (DC) into Alternating Current (AC). It is composed of inverter bridge, control logic and filter circuit.
The inverters include sine wave inverters and square wave inverters classified by the properties of the wave strings. The sine wave inverter outputs sine wave alternating current. In a sine wave inverter system, an input direct current needs to be converted into an alternating current for output after being subjected to sine modulation. In the inverter in the prior art, a table look-up method and Taylor series expansion are mainly adopted to calculate a sine value, then pulse width modulation is carried out according to the sine value, and the output is alternating current.
The advantages and disadvantages of the two modes are as follows;
1. the table look-up method has the advantages of high speed, small calculation amount and large occupied program space;
2. the Taylor series expansion has the advantages that the occupied space is smaller than that of the table lookup, and the defects that the calculation amount is large and the requirement is placed on the calculation capacity of a chip.
At present, the price of the chips on the market is generally too high, so that the production cost is limited, and the customers cannot obtain the chip cost with high calculation power and large space, so that the working efficiency of the inverter cannot be improved.
Disclosure of Invention
The invention provides a method for modulating an analog sine wave of an off-grid inverter and a storage medium, which solve the technical problem that the production cost is incompatible with the working efficiency (namely the operation capacity) due to the fact that the price of a processing chip of the existing inverter is too high.
In order to solve the technical problems, the invention provides a method for modulating an analog sine wave of an off-grid inverter, which comprises an MCU and an inverter circuit connected with the MCU, wherein the input end of the inverter circuit is connected with a direct-current power supply;
the MCU is used for calculating a target radian according to a preset modulation algorithm and further outputting a corresponding target sinusoidal carrier according to the target radian;
the inverter circuit is used for carrying out pulse width modulation according to the target sine carrier and converting an accessed direct-current power supply into corresponding sine-wave alternating current;
the preset modulation algorithm has the following calculation formula:
wherein, VacIs the voltage value of sine-wave alternating current, VdcAnd theta is the voltage value of the direct-current power supply, and theta is the target radian of the inverter circuit.
The basic scheme is based on the compatible requirement of the cost and the operational capability of the existing inverter, a preset modulation algorithm is designed to calculate a target radian, then a corresponding target sine carrier wave is output according to the target radian, an inverter circuit is controlled to perform pulse width modulation, an accessed direct-current power supply is converted into corresponding sine wave alternating current, the algorithm is simple, the calculated amount is small, and the operation efficiency is high, so that low-cost and high-efficiency inverter alternating current output can be realized by adopting a processing chip with a small program space.
In a further embodiment, the calculating the target radian according to the preset modulation algorithm specifically includes:
A. determining the total number of carriers in each inversion period according to the carrier frequency and the inversion frequency of the inversion circuit;
B. dividing a target angle variable of each carrier according to the total number of the carriers;
C. determining the change rule of the radian value of the inverter circuit in each inversion period according to the target angle variable;
D. and calculating the target radian according to the change rule and the current time stage.
In further embodiments, said step C comprises:
c1, equally dividing each inversion period into a plurality of time stages according to the total number of the carriers;
c2, calculating a first functional relation formula of each time phase and the target angle variable;
and C3, substituting the first functional relation formula into a sine formula to obtain an arc value of each time stage in each period, and establishing a second functional relation formula.
The scheme starts from the periodic variation of the arc value in the pulse width modulation, reversely calculates the arc value of the inverter in each time phase of each period, shortens the calculation time, and can quickly output sine wave alternating current.
In a further implementation, in the step C2, when each carrier corresponds to a time period, the first functional relationship formula is as follows:
wherein, X is a variable representing the current time phase, and n is the total number of carriers.
According to the scheme, each carrier is set to correspond to a time period, radian distribution and radian value calculation are carried out, the calculation difficulty of the radian value can be reduced, and the calculation efficiency is improved.
In a further embodiment, in the step C2, the second functional relationship formula is as follows:
when the time period is the positive half of the inversion cycle, i.e.
Then the process of the first step is carried out,
when the time period is the negative half of the inversion cycle, i.e.
Then the process of the first step is carried out,
wherein, X is a variable representing the current time phase, X belongs to N, and N is the total number of carriers.
The present invention also provides a storage medium having stored thereon a computer program for implementing the above-described method of modulating an analog sine wave of an off-grid inverter. The storage medium may be a magnetic disk, an optical disk, a Read Only Memory (ROM), a Random Access Memory (RAM), or the like.
Drawings
Fig. 1 is a schematic diagram of an output of a sine wave ac in an off-grid inverter simulation sine wave modulation method according to an embodiment of the present invention;
wherein: MCU1, inverter circuit 2.
Detailed Description
The embodiments of the present invention will be described in detail below with reference to the accompanying drawings, which are given solely for the purpose of illustration and are not to be construed as limitations of the invention, including the drawings which are incorporated herein by reference and for illustration only and are not to be construed as limitations of the invention, since many variations thereof are possible without departing from the spirit and scope of the invention.
Example 1
As shown in fig. 1, in the present embodiment, the off-grid inverter includes an MCU1 and an inverter circuit 2 connected to the MCU1, wherein an input end of the inverter circuit 2 is connected to a dc power supply;
the MCU1 is used for calculating a target radian according to a preset modulation algorithm and further outputting a corresponding target sinusoidal carrier according to the target radian;
the inverter circuit 2 is used for performing pulse width modulation according to a target sine carrier and converting an accessed direct-current power supply into corresponding sine-wave alternating current. The inverter circuit 2 in this embodiment is a conventional inverter bridge circuit, and therefore, is not described in detail in the embodiment of the present invention.
The preset modulation algorithm is calculated as follows:
wherein,Vacis the voltage value of sine-wave alternating current, VdcIs the voltage value of the DC power supply, theta is the target radian of the inverter circuit 2, and theta is more than or equal to 0<2π。
In this embodiment, the calculating the target radian according to the preset modulation algorithm specifically includes:
A. and determining the total number of the carriers in each inversion period according to the carrier frequency and the inversion frequency of the inversion circuit 2.
In this embodiment, if the inversion frequency is Fb (fundamental frequency) and the carrier frequency is Fc, the number of carriers in the whole cycle can be defined
I.e. per carrier, inverter output rotation
N carriers rotate exactly one revolution (circle) for each radian.
B. Dividing a target angle variable of each carrier according to the total number of the carriers;
C. determining the change rule of the radian value of the inverter circuit 2 in each inversion period according to the target angle variable, wherein the change rule comprises the following steps of C1-C2:
c1, equally dividing each inversion period into a plurality of time stages according to the total number of the carriers;
and C2, calculating a first functional relation formula of each time phase and the target angle variable.
In this embodiment, when each carrier corresponds to a time period, the first functional relationship formula is as follows:
wherein, X is a variable representing the current time phase, and n is the total number of carriers.
In the embodiment, each carrier is set to correspond to a time stage, and radian allocation and radian value calculation are performed, so that the calculation difficulty of the radian value can be reduced, and the calculation efficiency is improved.
And C3, substituting the first functional relation formula into a sine formula to obtain an arc value of each time stage in each period, and establishing a second functional relation formula.
In this embodiment, the second functional relationship formula is as follows:
when the time phase is the positive half of the inversion cycle, i.e.
Then the process of the first step is carried out,
when the time period is the negative half of the inversion cycle, i.e.
Then the process of the first step is carried out,
wherein, X is a variable representing the current time phase, X belongs to N (N is an integer), and N is the total number of carriers.
The present embodiment starts with the periodic variation of the arc value in the pulse width modulation, and reversely calculates the arc value of the inverter in each time phase of each period, thereby shortening the calculation time and rapidly outputting the sine wave ac.
D. And calculating the target radian according to the change rule and the current time stage.
In the present embodiment, a specific sine wave ac output process is as follows:
taking the initial phase of the sine wave alternating current as 0 as an example, at this time, the initial value of X is 0, the MCU1 will directly calculate the target radian according to the formula (3), X +1 after each time period, and then output the corresponding target sine carrier according to the formula (1);
for example, when θ is 0, X is 0, sin (θ) is 0;
when in use
Then
sin(θ)＝1；
When in use
Then
sin(θ)＝-1。
The inverter circuit 2 is used for performing pulse width modulation according to a target sine carrier and converting an accessed direct-current power supply into corresponding sine-wave alternating current.
When the inversion cycle enters the negative half cycle, the MCU1 will directly calculate the target radian according to formula (4), and similarly, X +1 after each time period, and then output the corresponding target sinusoidal carrier according to formula (1).
The embodiment of the invention designs a preset modulation algorithm to calculate the target radian based on the compatible requirement of the cost and the operational capability of the existing inverter, further outputs the corresponding target sinusoidal carrier according to the target radian, controls the inverter circuit 2 to carry out pulse width modulation, converts the accessed direct current power supply into the corresponding sinusoidal alternating current, and has the advantages of simple algorithm, small calculated amount and high operation efficiency, so that the low-cost and high-efficiency inverted alternating current output can be realized by adopting a processing chip with smaller program space.
Example 2
An embodiment of the present invention further provides a storage medium, on which a computer program is stored, where the computer program is used to implement the off-grid inverter analog sine wave modulation method provided in embodiment 1 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.
The above embodiments are preferred embodiments of the present invention, but the present invention is not limited to the above embodiments, and any other changes, modifications, substitutions, combinations, and simplifications which do not depart from the spirit and principle of the present invention should be construed as equivalents thereof, and all such changes, modifications, substitutions, combinations, and simplifications are intended to be included in the scope of the present invention.
Claims (6)
1. A simulation sine wave modulation method of an off-grid inverter is characterized by comprising the following steps: the inverter comprises an MCU and an inverter circuit connected with the MCU, wherein the input end of the inverter circuit is connected with a direct-current power supply;
the MCU is used for calculating a target radian according to a preset modulation algorithm and further outputting a corresponding target sinusoidal carrier according to the target radian;
the inverter circuit is used for carrying out pulse width modulation according to the target sine carrier and converting an accessed direct-current power supply into corresponding sine-wave alternating current;
the preset modulation algorithm has the following calculation formula:
wherein, VacIs the voltage value of sine-wave alternating current, VdcAnd theta is the voltage value of the direct-current power supply, and theta is the target radian of the inverter circuit.
2. The method according to claim 1, wherein the calculating the target radian according to the preset modulation algorithm specifically comprises:
A. determining the total number of carriers in each inversion period according to the carrier frequency and the inversion frequency of the inversion circuit;
B. dividing a target angle variable of each carrier according to the total number of the carriers;
C. determining the change rule of the radian value of the inverter circuit in each inversion period according to the target angle variable;
D. and calculating the target radian according to the change rule and the current time stage.
3. The method as claimed in claim 2, wherein the step C comprises:
c1, equally dividing each inversion period into a plurality of time stages according to the total number of the carriers;
c2, calculating a first functional relation formula of each time phase and the target angle variable;
and C3, substituting the first functional relation formula into a sine formula to obtain an arc value of each time stage in each period, and establishing a second functional relation formula.
4. The method as claimed in claim 3, wherein in the step C2, when each carrier wave corresponds to a time period, the first functional relationship formula is as follows:
wherein, X is a variable representing the current time phase, and n is the total number of carriers.
5. The method as claimed in claim 4, wherein in step C2, the second functional relationship formula is as follows:
when the time period is the positive half of the inversion cycle, i.e.
Then the process of the first step is carried out,
when the time period is the negative half of the inversion cycle, i.e.
Then the process of the first step is carried out,
wherein, X is a variable representing the current time phase, X belongs to N, and N is the total number of carriers.
6. A storage medium having a computer program stored thereon, characterized in that: the computer program is for implementing an off-grid inverter analog sine wave modulation method as claimed in claims 1-5.
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN115037176A (en) * | 2022-05-19 | 2022-09-09 | 天宝电子（惠州）有限公司 | High-precision simulation sine wave modulation algorithm, system and storage medium |
Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH03215173A (en) * | 1990-01-19 | 1991-09-20 | Mitsubishi Electric Corp | Pwm inverter device |
| US5376872A (en) * | 1993-04-29 | 1994-12-27 | Fuji Electric Co., Ltd. | Control device for voltage type pulse width modulation inverter |
| CN101789709A (en) * | 2010-01-13 | 2010-07-28 | 哈尔滨工业大学 | Sine wave pulse width modulation method for four-switch three-phase inverter |
| CN105978390A (en) * | 2016-03-17 | 2016-09-28 | 天宝电子（惠州）有限公司 | Pure sine wave inverter control method and device and inverter circuit |
| CN205647290U (en) * | 2016-03-17 | 2016-10-12 | 天宝电子（惠州）有限公司 | Inverter circuit |
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- 2021-07-30 CN CN202110867881.7A patent/CN113659859B/en active Active
Patent Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH03215173A (en) * | 1990-01-19 | 1991-09-20 | Mitsubishi Electric Corp | Pwm inverter device |
| US5376872A (en) * | 1993-04-29 | 1994-12-27 | Fuji Electric Co., Ltd. | Control device for voltage type pulse width modulation inverter |
| CN101789709A (en) * | 2010-01-13 | 2010-07-28 | 哈尔滨工业大学 | Sine wave pulse width modulation method for four-switch three-phase inverter |
| CN105978390A (en) * | 2016-03-17 | 2016-09-28 | 天宝电子（惠州）有限公司 | Pure sine wave inverter control method and device and inverter circuit |
| CN205647290U (en) * | 2016-03-17 | 2016-10-12 | 天宝电子（惠州）有限公司 | Inverter circuit |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN115037176A (en) * | 2022-05-19 | 2022-09-09 | 天宝电子（惠州）有限公司 | High-precision simulation sine wave modulation algorithm, system and storage medium |
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