Frequency multiplication carrier amplitude shift modulation method

Abstract

The invention discloses a frequency multiplication carrier amplitude shift modulation method, which is based on a two-unit inversion topological structure, and the two-unit inversion topological structure comprises a first switch tube S11, a second switch tube S12, a third switch tube S13, a fourth switch tube S14, a fifth switch tube S15, a sixth switch tube S16, a seventh switch tube S17, an eighth switch tube S18, an inductor L and a resistor R, according to the invention, the inverter is subjected to frequency doubling modulation, so that the equivalent frequency of the output voltage is improved, and the THD content of the output voltage is low; harmonic waves of the output voltage of the inverter are mainly distributed at and near 2n (n = 1, 2,...) times of the carrier frequency fc = 5kHz, the design of a filter can be simplified, and certain economic benefits are achieved. Simple logic combination is carried out, and control is easy to realize digitalization.

Description

Technical Field

[0001] The present invention relates to the field of inverter technology for switching power supplies, and specifically to a method for frequency-doubling carrier amplitude modulation. Background Art

[0002] The traditional carrier amplitude modulation strategy for a two-cell cascaded H-bridge is as Figure 1 shown. The characteristic of this modulation is that the output voltage harmonics are mainly distributed at the carrier frequency, and the design of the filter is complex and the cost is high. Summary of the Invention

[0003] An object of the present invention is to provide a method for frequency-doubling carrier amplitude modulation to solve the problems raised in the above background art.

[0004] To achieve the above object, the present invention provides the following technical solutions: A frequency-doubling carrier amplitude modulation method is based on a two-cell inverter topology. The two-cell inverter topology includes a first switch tube S11, a second switch tube S12, a third switch tube S13, a fourth switch tube S14, a fifth switch tube S15, a sixth switch tube S16, a seventh switch tube S17, an eighth switch tube S18, an inductor L, and a resistor R. The drain of the first switch tube S11 is connected to the drain of the third switch tube S13 and the positive pole of the power supply. The source of the first switch tube S11 is connected to the inductor L and the drain of the second switch tube S12. The source of the third switch tube S13 is connected to the drain of the fourth switch tube S14, the source of the fifth switch tube S15, and the drain of the sixth switch tube S16. The other end of the inductor L is connected to the resistor R. The other end of the resistor R is connected to the source of the fifth switch tube S17 and the drain of the sixth switch tube S18. The source of the second switch tube S12 is connected to the source of the fourth switch tube S14 and the negative pole of the power supply. The drain of the fifth switch tube S15 is connected to the drain of the fifth switch tube S17 and the positive pole of the power supply. The source of the sixth switch tube S16 is connected to the source of the sixth switch tube S18 and the negative pole of the power supply. It is characterized in that it further includes a modulation wave. The modulation wave includes a first carrier wave, a second carrier wave, a third carrier wave, a fourth carrier wave, a fifth carrier wave, a sixth carrier wave, a seventh carrier wave, an eighth carrier wave, and a sine modulation wave. Two signals obtained after comparing the sine modulation wave with the first carrier wave and the second carrier wave are then subjected to an OR logic operation to obtain the drive signal of the first switch tube S11. Taking the inverse logic of the drive signal of the first switch tube S11 can obtain the drive signal of the second switch tube S12. Two signals obtained after comparing the sine modulation wave with the seventh carrier wave and the eighth carrier wave are then subjected to an OR logic to obtain the drive signal of the third switch tube S13. Taking the inverse logic of the drive signal of the third switch tube S13 can obtain the drive signal of the fourth switch tube S14. Similarly, two signals obtained after comparing the sine modulation wave with the third carrier wave and the fourth carrier wave are then subjected to an OR logic to obtain the drive signal of the fifth switch tube S15. Taking the inverse logic of the drive signal of the fifth switch tube S15 can obtain the drive signal of the sixth switch tube S16. Two signals obtained after comparing the sine modulation wave with the fifth carrier wave and the sixth carrier wave are then subjected to an OR logic to obtain the drive signal of the seventh switch tube S17. Taking the inverse logic of the drive signal of the seventh switch tube S17 can obtain the drive signal of the eighth switch tube S18.

[0005] As a further technical solution of the present invention: the drive signals of the first switch tube S11 and the second switch tube S12 are complementary, the drive signals of the third switch tube S13 and the fourth switch tube S14 are complementary, the drive signals of the fifth switch tube S15 and the sixth switch tube S16 are complementary, and the drive signals of the seventh switch tube S17 and the eighth switch tube S18 are complementary.

[0006] As a further technical solution of the present invention: the first switching tube S11, the second switching tube S12, the third switching tube S13, the fourth switching tube S14, the fifth switching tube S15, the sixth switching tube S16, the seventh switching tube S17 and the eighth switching tube S18 are all IGBT tubes.

[0007] Compared with the prior art, the beneficial effects of the present invention are: 1. By double-frequency modulation of the inverter, the equivalent frequency of the output voltage is increased, and the THD content of the output voltage is low; 2. The harmonics of the inverter output voltage are mainly distributed at 2n (n = 1, 2,...) times and nearby of the carrier frequency fc = 5 kHz, which can simplify the design of the filter and has certain economic benefits; 3. Through simple logical combination, the control is easy to be realized digitally. Description of the Drawings

[0008] Figure 1 is the schematic diagram of traditional carrier amplitude shift modulation; Figure 2 is the schematic diagram of double-frequency carrier amplitude shift modulation; Figure 3 is the two-cell inverter topology diagram; Figure 4 is the THD waveform diagram of the inverter output voltage using the carrier amplitude shift modulation strategy of the traditional two-cell cascaded H-bridge.

[0009] Figure 5 is the THD waveform diagram of the inverter output voltage using the method of the present invention. Detailed Embodiment

[0010] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0011] Please refer to Figure 2-5, A frequency-doubling carrier amplitude modulation method, based on a two-cell inverter topology. The two-cell inverter topology includes a first switch tube S11, a second switch tube S12, a third switch tube S13, a fourth switch tube S14, a fifth switch tube S15, a sixth switch tube S16, a seventh switch tube S17, an eighth switch tube S18, an inductor L, and a resistor R. The drain of the first switch tube S11 is connected to the drain of the third switch tube S13 and the positive pole of the power supply. The source of the first switch tube S11 is connected to the inductor L and the drain of the second switch tube S12. The source of the third switch tube S13 is connected to the drain of the fourth switch tube S14, the source of the fifth switch tube S15, and the drain of the sixth switch tube S16. The other end of the inductor L is connected to the resistor R. The other end of the resistor R is connected to the source of the fifth switch tube S17 and the drain of the sixth switch tube S18. The source of the second switch tube S12 is connected to the source of the fourth switch tube S14 and the negative pole of the power supply. The drain of the fifth switch tube S15 is connected to the drain of the fifth switch tube S17 and the positive pole of the power supply. The source of the sixth switch tube S16 is connected to the source of the sixth switch tube S18 and the negative pole of the power supply. It is characterized in that it further includes a modulation wave. The modulation wave includes a first carrier wave, a second carrier wave, a third carrier wave, a fourth carrier wave, a fifth carrier wave, a sixth carrier wave, a seventh carrier wave, an eighth carrier wave, and a sine modulation wave. Two signals obtained after comparing the sine modulation wave with the first carrier wave and the second carrier wave are then subjected to an OR logic operation to obtain the drive signal of the first switch tube S11. Taking the inverse logic of the drive signal of the first switch tube S11 can obtain the drive signal of the second switch tube S12. Two signals obtained after comparing the sine modulation wave with the seventh carrier wave and the eighth carrier wave are then subjected to an OR logic to obtain the drive signal of the third switch tube S13. Taking the inverse logic of the drive signal of the third switch tube S13 can obtain the drive signal of the fourth switch tube S14. Similarly, two signals obtained after comparing the sine modulation wave with the third carrier wave and the fourth carrier wave are then subjected to an OR logic to obtain the drive signal of the fifth switch tube S15. Taking the inverse logic of the drive signal of the fifth switch tube S15 can obtain the drive signal of the sixth switch tube S16. Two signals obtained after comparing the sine modulation wave with the fifth carrier wave and the sixth carrier wave are then subjected to an OR logic to obtain the drive signal of the seventh switch tube S17. Taking the inverse logic of the drive signal of the seventh switch tube S17 can obtain the drive signal of the eighth switch tube S18.

[0012] Among them, the drive signals of the first switch tube S11 and the second switch tube S12 are complementary, the drive signals of the third switch tube S13 and the fourth switch tube S14 are complementary, the drive signals of the fifth switch tube S15 and the sixth switch tube S16 are complementary, and the drive signals of the seventh switch tube S17 and the eighth switch tube S18 are complementary.

[0013] The first switching transistor S11, the second switching transistor S12, the third switching transistor S13, the fourth switching transistor S14, the fifth switching transistor S15, the sixth switching transistor S16, the seventh switching transistor S17 and the eighth switching transistor S18 are all IGBT transistors.

[0014] Adopting the carrier amplitude-shifted modulation strategy of the traditional two-cell cascaded H-bridge, the THD of the inverter output voltage is as Figure 4 shown. Adopting a double-frequency carrier amplitude-shifted modulation strategy, the THD of the inverter output voltage is as Figure 5 shown.

[0015] It can be seen that under the traditional modulation strategy, the output voltage harmonics are mainly distributed at the carrier frequency (5KHz). Under the double-frequency modulation measurement, the output voltage harmonics are mainly distributed at twice the carrier frequency (10KHz), which improves the equivalent frequency of the output voltage. The THD content of the output voltage is low, and it can also simplify the design of the filter, having certain economic benefits.

[0016] For those skilled in the art, it is obvious that the present invention is not limited to the details of the above exemplary embodiments, and without departing from the spirit or basic characteristics of the present invention, the present invention can be implemented in other specific forms. Therefore, from any point of view, the embodiments should be regarded as exemplary and non-restrictive. The scope of the present invention is defined by the appended claims rather than the above description. Therefore, it is intended to embrace all changes falling within the meaning and scope of the equivalent elements of the claims in the present invention. Any reference signs in the claims should not be regarded as limiting the claimed rights.

[0017] In addition, it should be understood that although this specification is described according to the embodiments, not every embodiment only contains an independent technical solution. This narrative way of the specification is only for clarity. Those skilled in the art should regard the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. A frequency-multiplied carrier amplitude shift modulation method, based on a two-unit inverter topology structure, wherein the two-unit inverter topology structure comprises a first switch tube S11, a second switch tube S12, a third switch tube S13, a fourth switch tube S14, a fifth switch tube S15, a sixth switch tube S16, a seventh switch tube S17, an eighth switch tube S18, an inductor L and a resistor R, wherein the drain of the first switch tube S11 is connected to the drain of the third switch tube S13 and the positive electrode of the power supply, the source of the first switch tube S11 is connected to the inductor L and the drain of the second switch tube S12, and the third switch tube S14 is connected to the positive electrode of the power supply. The source of S13 is connected to the drain of the fourth switch tube S14, the source of the fifth switch tube S15 and the drain of the sixth switch tube S16, the other end of the inductor L is connected to the resistor R, the other end of the resistor R is connected to the source of the fifth switch tube S17 and the drain of the sixth switch tube S18, the source of the second switch tube S12 is connected to the source of the fourth switch tube S14 and the negative electrode of the power supply, the drain of the fifth switch tube S15 is connected to the drain of the fifth switch tube S17 and the positive electrode of the power supply, and the source of the sixth switch tube S16 is connected to the source of the sixth switch tube S18 and the negative electrode of the power supply, characterized in that: The invention also includes a modulation wave, which includes a first carrier wave, a second carrier wave, a third carrier wave, a fourth carrier wave, a fifth carrier wave, a sixth carrier wave, a seventh carrier wave, an eighth carrier wave and a sinusoidal modulation wave. The two signals obtained by comparing the sinusoidal modulation wave with the first carrier wave and the second carrier wave are subjected to an OR logic operation to obtain a driving signal of the first switch tube S11. The driving signal of the first switch tube S11 is inverted to obtain a driving signal of the second switch tube S12. The two signals obtained by comparing the sinusoidal modulation wave with the seventh carrier wave and the eighth carrier wave are subjected to an OR logic operation to obtain a driving signal of the third switch tube S13. The driving signal of the fourth switch tube S14 can be obtained by taking the inverted logic of the driving signal of the sinusoidal modulated wave and the third carrier and the fourth carrier, and the driving signal of the fifth switch tube S15 can be obtained by performing an OR logic operation on the two signals obtained by comparing the sinusoidal modulated wave with the third carrier and the fourth carrier, and the driving signal of the sixth switch tube S16 can be obtained by taking the inverted logic of the driving signal of the fifth switch tube S15, and the driving signal of the seventh switch tube S17 can be obtained by taking the inverted logic of the driving signal of the seventh switch tube S17, and the driving signal of the eighth switch tube S18 can be obtained by taking the inverted logic of the driving signal of the seventh switch tube S18.

2. A frequency-multiplied carrier amplitude shift modulation method according to claim 1, characterized in that: The first switch tube S11 and the second switch tube S12 have complementary driving signals, the third switch tube S13 and the fourth switch tube S14 have complementary driving signals, the fifth switch tube S15 and the sixth switch tube S16 have complementary driving signals, and the seventh switch tube S17 and the eighth switch tube S18 have complementary driving signals.

3. A frequency-multiplied carrier amplitude shift modulation method according to claim 1, characterized in that: The first switch tube S11, the second switch tube S12, the third switch tube S13, the fourth switch tube S14, the fifth switch tube S15, the sixth switch tube S16, the seventh switch tube S17 and the eighth switch tube S18 are all IGBT tubes.

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