Sine pulse width modulation circuit and method of six-switch converter

Abstract

The invention relates to the field of power supply control driving, in particular to a sine pulse width modulation circuit and method of a six-switch converter, a signal generator module of the sine pulse width modulation circuit controls work of an upper inverter and a lower inverter respectively, and a logic gate module controls the sine pulse width modulation circuit of the six-switch converter according to comparison operation of a signal comparison module. The pulse width modulation signals are selectively shielded or gated to drive the output ends of the modulation circuits. The driving pulse frequency of the output ends of the two modulation circuits at the middle position can be remarkably reduced. Under the optimal condition, the switching frequency of the output end of the modulation circuit at the middle position is the same as the frequency of the alternating current output voltage, and under the worst condition, the switching frequency of the output ends of the two modulation circuits at the middle position is kept to be half of the modulation frequency and is the same as the frequency of the other four power switches at the upper end and the lower end. Therefore, the thermal stability of the system is greatly improved.

Description

Technical Field

[0001] The present invention relates to the field of power supply control driving, and more specifically, to a sinusoidal pulse width modulation circuit and method for a six-switch converter. Background Art

[0002] Reducing the cost of power electronic converters and improving converter efficiency are the eternal themes of energy technology innovation. In recent years, the six-switch converter has shown broad application prospects in electric vehicles, uninterruptible power supply systems, smart grids, railway traction, electric drive systems, and power quality management equipment because it can achieve two-way AC voltage output by using fewer semiconductor power devices. However, for the six-switch converter, based on the existing sinusoidal pulse width modulation algorithm, the switching frequency of the two power devices in the middle of the converter is twice that of the other four power devices, resulting in the middle device generating significantly more heat than other devices, which greatly limits the promotion and application of the six-switch converter. Summary of the invention

[0003] In order to overcome at least one of the above-mentioned defects of the prior art, the present invention provides a sinusoidal pulse width modulation circuit and method for a six-switch converter.

[0004] The present invention aims to solve the above technical problems at least to a certain extent.

[0005] In order to solve the above technical problems, the technical solution of the present invention is as follows: A sinusoidal pulse width modulation circuit for a six-switch converter comprises: a signal generator module, a signal inversion module, a signal comparison module and a logic gate module, wherein the output end of the signal generator module is respectively connected to the input ends of the signal inversion module, the logic gate module and the signal comparison module, the output end of the signal inversion module is connected to the input end of the signal comparison module, the output end of the signal comparison module is connected to the input end of the logic gate module, and the output end of the logic gate module is connected to the power device of the six-switch converter.

[0006] Furthermore, the signal generator module includes a sinusoidal modulation signal generator of the upper inverter, a sinusoidal modulation signal generator of the lower inverter, a triangle modulation signal generator, a square wave modulation signal generator and a constant modulation signal generator. The output end of the sinusoidal modulation signal generator of the upper inverter is respectively connected to the input end of the signal inversion module and the input end of the signal comparison module, the output end of the sinusoidal modulation signal generator of the lower inverter is respectively connected to the input end of the signal comparison module and the input end of the signal inversion module, the output ends of the constant modulation signal generator and the triangle modulation signal generator are respectively connected to the input end of the signal comparison module, and the output end of the square wave modulation signal generator is connected to the input end of the logic gate module.

[0007] Further, the signal comparison module includes a first comparator, a second comparator, a third comparator, a fourth comparator, a fifth comparator, a sixth comparator, a seventh comparator and an eighth comparator, wherein the non-phase input terminal of the first comparator is connected to the output terminal of the sinusoidal modulation signal generator of the upper inverter, the inverting input terminal of the first comparator is connected to the output terminal of the triangular modulation signal generator, the non-phase input terminal of the second comparator is connected to the output terminal of the signal inversion module, the inverting input terminal of the second comparator is connected to the output terminal of the triangular modulation signal generator, the non-phase input terminal of the third comparator is connected to the output terminal of the sinusoidal modulation signal generator of the lower inverter, the inverting input terminal of the third comparator is connected to the output terminal of the triangular modulation signal generator, the non-phase input terminal of the fourth comparator is connected to the output terminal of the signal inversion module The output end of the block is connected, the inverting input end of the fourth comparator is connected to the output end of the triangular modulation signal generator, the non-phase input end of the fifth comparator is connected to the output end of the constant modulation signal generator, the inverting input end of the fifth comparator is connected to the output end of the sine modulation signal generator of the upper inverter, the non-phase input end of the sixth comparator is connected to the output end of the constant modulation signal generator, the inverting input end of the sixth comparator is connected to the output end of the signal inversion module, the non-phase input end of the seventh comparator is connected to the output end of the constant modulation signal generator, the inverting input end of the seventh comparator is connected to the output end of the sine modulation signal generator of the lower inverter, the non-phase input end of the eighth comparator is connected to the output end of the constant modulation signal generator, and the inverting input end of the eighth comparator is connected to the output end of the signal inversion module.

[0008] Furthermore, the signal inversion module includes a first inverter and a second inverter, the input end of the first inverter is connected to the output end of the sinusoidal modulation signal generator of the upper inverter, the output end of the first inverter is connected to the input end of the sixth comparator, the input end of the second inverter is connected to the output end of the sinusoidal modulation signal generator of the lower inverter, the output end of the second inverter is connected to the input end of the fourth comparator, and the signal inversion module is used to reverse the sinusoidal modulation signal of the upper inverter and the sinusoidal modulation signal of the lower inverter.

[0009] Further, the logic gate module includes a first OR gate, a second OR gate, a third OR gate, a fourth OR gate, a fifth OR gate, a sixth OR gate, a first AND gate, a second AND gate, a third AND gate, a fourth AND gate and a NOT gate, the input end of the first OR gate is connected to the output end of the first comparator and the square wave modulation signal generator, the input end of the second OR gate is connected to the square wave modulation signal generator and the output end of the second comparator, the input end of the fifth OR gate is connected to the output end of the NOT gate and the output end of the third comparator, and the input end of the sixth OR gate is connected to the output end of the NOT gate and the output end of the fourth comparator. , the input end of the first AND gate is connected to the output end of the fifth comparator and the output end of the NOT gate, the input end of the second AND gate is connected to the output end of the square wave modulation signal generator and the output end of the seventh comparator, the output end of the first AND gate is connected to the output end of the second AND gate and the input end of the third OR gate, the input end of the third AND gate is connected to the output end of the sixth comparator and the output end of the NOT gate, the fourth AND gate is connected to the output end of the square wave modulation signal generator and the output end of the eighth comparator, and the output end of the third AND gate is connected to the output end of the fourth AND gate and the input end of the fourth OR gate.

[0010] Further, the power device includes: a first power tube, a second power tube, a third power tube, a fourth power tube, a fifth power tube and a sixth power tube, the input end of the first power tube is connected to the output end of the first OR gate, the input end of the second power tube is connected to the output end of the second OR gate, the input end of the third power tube is connected to the output end of the third OR gate, the input end of the fourth power tube is connected to the output end of the fourth OR gate, the input end of the fifth power tube is connected to the output end of the fifth OR gate, and the input end of the sixth power tube is connected to the output end of the sixth OR gate.

[0011] A sinusoidal pulse width modulation method for a six-switch converter, the sinusoidal pulse width modulation method being applied to the sinusoidal pulse width modulation circuit, comprising the following steps: S1: The signal generator module outputs the sinusoidal modulation signal of the upper inverter, the sinusoidal modulation signal of the lower inverter, the square wave modulation signal and the triangle modulation signal respectively; S2: Inputting the sinusoidal modulation signal of the upper inverter, the sinusoidal modulation signal of the lower inverter and the triangular modulation signal into a signal comparison module; S3: Compare the sinusoidal modulation signal of the upper inverter and the sinusoidal modulation signal of the lower inverter with the triangular modulation signal through a signal comparison module to generate a pulse width modulation signal, wherein the pulse width modulation signal controls the first power tube, the second power tube, the fifth power tube and the sixth power tube; S4: The square wave modulation signal controls the third power tube and the fourth power tube.

[0012] Further, in step S3, the sinusoidal modulation signal of the upper inverter and the sinusoidal modulation signal of the lower inverter are respectively compared with the triangular modulation signal through a signal comparison module to generate a pulse width modulation signal, and the pulse width modulation signal controls the first power tube, the second power tube, the fifth power tube and the sixth power tube, including: The sinusoidal modulation signal of the upper inverter and the sinusoidal modulation signal of the lower inverter are respectively compared with the triangular modulation signal through the signal comparison module. If the sinusoidal modulation signal of the upper inverter is greater than the triangular modulation signal, the first power tube and the fifth power tube are at a high level. If the sinusoidal modulation signal of the upper inverter is less than the triangular modulation signal, the first power tube and the fifth power tube are at a low level. If the sinusoidal modulation signal of the lower inverter is greater than the triangular modulation signal, the second power tube and the sixth power tube are at a high level. If the sinusoidal modulation signal of the lower inverter is less than the triangular modulation signal, the second power tube and the sixth power tube are at a low level.

[0013] Further, in step S4, the square wave modulation signal controls the third power tube and the fourth power tube, including: When the phases of the sinusoidal modulation signal of the upper inverter and the sinusoidal modulation signal of the lower inverter are opposite, the third power tube and the fourth power tube are alternately turned on under the control of the square wave modulation signal.

[0014] Further, calculating the switching frequencies of the third power tube and the fourth power tube includes:

[0015] In the formula, is the switching frequency of the third power tube and the fourth power tube, is the carrier signal frequency, is the phase difference.

[0016] Compared with the prior art, the technical solution of the present invention has the following beneficial effects: The present invention can significantly reduce the driving pulse frequency of the two power devices in the middle position. Under the best conditions, the switching frequency of the power device in the middle position is the same as the frequency of the AC output voltage. Under the worst conditions, the switching frequency of the two power devices in the middle position is maintained at half of the modulation frequency, thereby greatly improving the thermal stability of the system. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 is a structural diagram of the sinusoidal pulse width modulation circuit of the present invention; Figure 2 is an application diagram of the sinusoidal pulse width modulation circuit described in this embodiment; Figure 3 The modulation method of the present invention is a control diagram of an inverter; Figure 4The modulation method of the present invention is used to control the lower inverter; Figure 5 This is a diagram showing the best working state of the sinusoidal pulse width modulation circuit described in this embodiment; Figure 6 This is a diagram of the worst working state of the sinusoidal pulse width modulation circuit described in this embodiment. DETAILED DESCRIPTION

[0018] The drawings are for illustrative purposes only and should not be construed as limiting the present patent; In order to better illustrate the present embodiment, some parts in the drawings may be omitted, enlarged or reduced, and do not represent the size of the actual product; It is understandable to those skilled in the art that some well-known structures and their descriptions may be omitted in the drawings.

[0019] The technical solution of the present invention is further described below in conjunction with the accompanying drawings and embodiments.

[0020] Example 1 A six-switch converter sinusoidal pulse width modulation circuit, such as Figure 1 As shown, it includes: a signal generator module, a signal inversion module, a signal comparison module and a logic gate module, the output end of the signal generator module is respectively connected to the input end of the signal inversion module, the logic gate module and the signal comparison module, the output end of the signal inversion module is connected to the input end of the signal comparison module, the output end of the signal comparison module is connected to the input end of the logic gate module, and the output end of the logic gate module is connected to the power device of the six-switch converter.

[0021] In the actual implementation process, the signal generator module is located at the front end of the circuit, and generates a sinusoidal modulation signal, a triangular modulation signal, a square wave modulation signal and a constant modulation signal for the upper inverter and the lower inverter. The sinusoidal modulation signal of the upper inverter and the sinusoidal modulation signal of the lower inverter are respectively compared with the triangular modulation signal through the signal comparison module to generate a pulse width modulation signal. The pulse width modulation signal controls the switching frequency of the first power tube, the second power tube, the fifth power tube and the sixth power tube of the six-switch converter, and the square wave modulation signal controls the frequency of the third power tube and the fourth power tube. Compared with the existing sinusoidal pulse width modulation algorithm, when the present invention controls the upper inverter, the switching frequency of the third power tube and the fourth power tube is the same as the switching frequency of the sinusoidal modulation signal of the upper inverter (if the frequency of the sinusoidal modulation signal of the upper inverter is 50Hz, the switching frequency of the third power tube and the fourth power tube is also 50Hz), and the switching frequency of the first power tube and the second power tube is half of the frequency of the triangular modulation signal (if the switching frequency of the triangular modulation signal is fs, the switching frequency of the first power tube and the second power tube is 0.5fs). When controlling the lower inverter, the switching frequencies of the third power tube and the fourth power tube are consistent with the frequency of the sinusoidal modulation signal of the lower inverter, and the switching frequencies of the fifth power tube and the sixth power tube are 0.5fs, which can greatly reduce the switching frequencies of the third power tube and the fourth power tube, thereby greatly improving the thermal stability of the system.

[0022] Example 2 This embodiment further discloses the following contents based on the embodiment 1: like Figure 2 As shown, the signal generator module includes a sinusoidal modulation signal generator of an upper inverter, a sinusoidal modulation signal generator of a lower inverter, a triangle modulation signal generator, a square wave modulation signal generator and a constant modulation signal generator. The output end of the sinusoidal modulation signal generator of the upper inverter is respectively connected to the input end of the signal inversion module and the input end of the signal comparison module, the output end of the sinusoidal modulation signal generator of the lower inverter is respectively connected to the input end of the signal comparison module and the input end of the signal inversion module, the output ends of the constant modulation signal generator and the triangle modulation signal generator are respectively connected to the input end of the signal comparison module, and the output end of the square wave modulation signal generator is connected to the input end of the logic gate module.

[0023] The signal comparison module includes a first comparator, a second comparator, a third comparator, a fourth comparator, a fifth comparator, a sixth comparator, a seventh comparator and an eighth comparator, wherein the non-phase input terminal of the first comparator is connected to the output terminal of the sinusoidal modulation signal generator of the upper inverter, the inverting input terminal of the first comparator is connected to the output terminal of the triangular modulation signal generator, the non-phase input terminal of the second comparator is connected to the output terminal of the signal inversion module, the inverting input terminal of the second comparator is connected to the output terminal of the triangular modulation signal generator, the non-phase input terminal of the third comparator is connected to the output terminal of the sinusoidal modulation signal generator of the lower inverter, the inverting input terminal of the third comparator is connected to the output terminal of the triangular modulation signal generator, the non-phase input terminal of the fourth comparator is connected to the output terminal of the signal inversion module The output end is connected, the inverting input end of the fourth comparator is connected to the output end of the triangular modulation signal generator, the non-phase input end of the fifth comparator is connected to the output end of the constant modulation signal generator, the inverting input end of the fifth comparator is connected to the output end of the sine modulation signal generator of the upper inverter, the non-phase input end of the sixth comparator is connected to the output end of the constant modulation signal generator, the inverting input end of the sixth comparator is connected to the output end of the signal inversion module, the non-phase input end of the seventh comparator is connected to the output end of the constant modulation signal generator, the inverting input end of the seventh comparator is connected to the output end of the sine modulation signal generator of the lower inverter, the non-phase input end of the eighth comparator is connected to the output end of the constant modulation signal generator, and the inverting input end of the eighth comparator is connected to the output end of the signal inversion module.

[0024] In the actual implementation process, each comparator receives a signal from the signal generator module and performs comparison processing through the comparator module. In the sinusoidal pulse width modulation circuit, the comparator compares the sinusoidal modulation signal of the upper inverter and the lower inverter with the triangular modulation. When the amplitude of the sinusoidal modulation wave is greater than the amplitude of the triangular modulation, the comparator module outputs a high level; when the amplitude of the sinusoidal modulation wave is less than the amplitude of the triangular modulation, it outputs a low level.

[0025] Example 3 This embodiment further discloses the following contents based on Embodiments 1 and 2: The signal inversion module includes a first inverter and a second inverter, the input end of the first inverter is connected to the output end of the sinusoidal modulation signal generator of the upper inverter, the output end of the first inverter is connected to the input end of the sixth comparator, the input end of the second inverter is connected to the output end of the sinusoidal modulation signal generator of the lower inverter, and the output end of the second inverter is connected to the input end of the fourth comparator. The signal inversion module is used to reverse the sinusoidal modulation signal of the upper inverter and the sinusoidal modulation signal of the lower inverter.

[0026] The signal inversion module receives the sinusoidal modulation signals from the upper inverter and the lower inverter, and performs phase inversion on these signals through the inverter, and the inverted signals are connected to the corresponding comparators in the signal comparison module through wires.

[0027] The logic gate circuit includes a first OR gate, a second OR gate, a third OR gate, a fourth OR gate, a fifth OR gate, a sixth OR gate, a first AND gate, a second AND gate, a third AND gate, a fourth AND gate and a NOT gate. The input end of the first OR gate is connected to the output end of the first comparator and the square wave modulation signal generator, the input end of the second OR gate is connected to the square wave modulation signal generator and the output end of the second comparator, the input end of the fifth OR gate is connected to the output end of the NOT gate and the output end of the third comparator, the input end of the sixth OR gate is connected to the output end of the NOT gate and the output end of the fourth comparator, the input end of the first AND gate is connected to the output end of the fifth comparator and the output end of the NOT gate, the input end of the second AND gate is connected to the output end of the square wave modulation signal generator and the output end of the seventh comparator, the output end of the first AND gate is connected to the output end of the second AND gate and the input end of the third OR gate, the input end of the third AND gate is connected to the output end of the sixth comparator and the output end of the NOT gate, the fourth AND gate is connected to the output end of the square wave modulation signal generator and the output end of the eighth comparator, and the output end of the third AND gate is connected to the output end of the fourth AND gate and the input end of the fourth OR gate.

[0028] The power device includes: a first power tube, a second power tube, a third power tube, a fourth power tube, a fifth power tube and a sixth power tube, the input end of the first power tube is connected to the output end of the first OR gate, the input end of the second power tube is connected to the output end of the second OR gate, the input end of the third power tube is connected to the output end of the third OR gate, the input end of the fourth power tube is connected to the output end of the fourth OR gate, the input end of the fifth power tube is connected to the output end of the fifth OR gate, and the input end of the sixth power tube is connected to the output end of the sixth OR gate.

[0029] The switching frequencies of the third power tube and the fourth power tube are the same as the sinusoidal modulation signal frequencies of the upper inverter and the lower inverter, and the switching frequencies of the first power tube, the second power tube, the fifth power tube, and the sixth power tube are half of the triangular modulation signal frequency.

[0030] In the actual implementation process, the switching state of the power tube determines the waveform of the output voltage or current, thereby realizing the modulation of the sinusoidal pulse width. In the sinusoidal pulse width modulation circuit, the switching state of the power tube determines the waveform of the output voltage or current. By controlling the pulse width of the power tube, the modulation of the sinusoidal pulse width can be realized.

[0031] Example 4 This embodiment further discloses the following contents based on Embodiments 1, 2 and 3: A sinusoidal pulse width modulation method for a six-switch converter, the sinusoidal pulse width modulation method being applied to the sinusoidal pulse width modulation circuit, comprising the following steps: S1: The signal generator module outputs the sinusoidal modulation signal of the upper inverter, the sinusoidal modulation signal of the lower inverter, the square wave modulation signal and the triangle modulation signal respectively; S2: Inputting the sinusoidal modulation signal of the upper inverter, the sinusoidal modulation signal of the lower inverter and the triangular modulation signal into a signal comparison module; S3: Compare the sinusoidal modulation signal of the upper inverter and the sinusoidal modulation signal of the lower inverter with the triangular modulation signal through a signal comparison module to generate a pulse width modulation signal, wherein the pulse width modulation signal controls the first power tube, the second power tube, the fifth power tube and the sixth power tube; S4: The square wave modulation signal controls the third power tube and the fourth power tube.

[0032] In step S3, the sinusoidal modulation signal of the upper inverter and the sinusoidal modulation signal of the lower inverter are respectively compared with the triangular modulation signal through a signal comparison module to generate a pulse width modulation signal, and the pulse width modulation signal controls the first power tube, the second power tube, the fifth power tube and the sixth power tube, including: The sinusoidal modulation signal of the upper inverter and the sinusoidal modulation signal of the lower inverter are respectively compared with the triangular modulation signal through the signal comparison module. If the sinusoidal modulation signal of the upper inverter is greater than the triangular modulation signal, the first power tube and the fifth power tube are at a high level. If the sinusoidal modulation signal of the upper inverter is less than the triangular modulation signal, the first power tube and the fifth power tube are at a low level. If the sinusoidal modulation signal of the lower inverter is greater than the triangular modulation signal, the second power tube and the sixth power tube are at a high level. If the sinusoidal modulation signal of the lower inverter is less than the triangular modulation signal, the second power tube and the sixth power tube are at a low level.

[0033] In the actual implementation process, in the first period, such as Figure 3 As shown, when the square wave modulation signal generator outputs a high level, the pulse width modulation signals of the two switch elements of the fifth power tube and the sixth power tube are effectively shielded, that is, the two switches remain in a high level state and do not participate in the current power conversion process. In order to avoid switching action in the upper inverter, thereby reducing heat loss.

[0034] The two switch elements, the third power tube and the fourth power tube in the upper inverter, work according to the pulse width modulation signal provided by the two control signal sources, the first comparator and the second comparator. The pulse width modulation signal accurately controls the switching state of the third power tube and the fourth power tube.

[0035] In the second period, if Figure 4As shown, when the square wave modulation signal generator outputs a low level, the logic gate module controls again, and the pulse width modulation signals of the two switch elements of the first power tube and the second power tube are shielded, that is, the first power tube and the second power tube remain in a high level state and do not participate in the power conversion process of the lower inverter. The third power tube and the fourth power tube in the lower inverter work according to the pulse width modulation signal provided by the third comparator and the fourth comparator.

[0036] like Figure 5 As shown, in the optimal working state of the modulation scheme provided by the present invention, the switching frequencies of the first power tube, the second power tube, the fifth power tube and the sixth power tube are 0.5 times the modulation frequency fs, and the switching frequencies of the third power tube and the fourth power tube are consistent with the frequency of the output voltage sinU / sinL.

[0037] Figure 6 As shown, Figure 6 This is the worst working state of the modulation method. In this mode, the switching frequencies of the first power tube, the second power tube, the third power tube, the fourth power tube, the fifth power tube and the sixth power tube are all 0.5 times the modulation frequency fs. Under the best conditions, the switching frequencies of the two power devices in the middle position can be the same as the frequency of the AC output voltage; in the worst case, the switching frequencies of the two power devices in the middle position remain half of the carrier frequency and are the same as the frequencies of the other four power switches at the upper and lower ends, thereby greatly improving the thermal stability of the system.

[0038] In other voltage frequencies, i.e., phase difference modes, the switching frequencies of the first power tube, the second power tube, the fifth power tube, and the sixth power tube are all maintained at 0.5 times the modulation frequency fs, and the switching frequencies of the third power tube and the fourth power tube can be described by the following formula:

[0039] In the formula, is the switching frequency of the third power tube and the fourth power tube, is the carrier signal frequency, When the six-switch converter is controlled by a sinusoidal pulse width modulation circuit and method, the switching frequency of the T3 and T4 power tubes can be effectively reduced, thereby overcoming the defects of the existing SPWM algorithm.

[0040] The same or similar reference numerals correspond to the same or similar components; The terms used in the drawings to describe positional relationships are only used for illustrative purposes and should not be construed as limiting this patent; Obviously, the above embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not intended to limit the embodiments of the present invention. For those skilled in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the embodiments here. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the claims of the present invention.

Claims

1. A sinusoidal pulse width modulation circuit for a six-switch converter, characterized in that: include: A signal generator module, a signal inversion module, a signal comparison module and a logic gate module, wherein the output end of the signal generator module is respectively connected to the input ends of the signal inversion module, the logic gate module and the signal comparison module, the output end of the signal inversion module is connected to the input end of the signal comparison module, the output end of the signal comparison module is connected to the input end of the logic gate module, and the output end of the logic gate module is connected to the power device of the six-switch converter.

2. The sinusoidal pulse width modulation circuit of the six-switch converter according to claim 1, characterized in that: The signal generator module includes a sinusoidal modulation signal generator of an upper inverter, a sinusoidal modulation signal generator of a lower inverter, a triangle modulation signal generator, a square wave modulation signal generator and a constant modulation signal generator. The output end of the sinusoidal modulation signal generator of the upper inverter is respectively connected to the input end of the signal inversion module and the input end of the signal comparison module, the output end of the sinusoidal modulation signal generator of the lower inverter is respectively connected to the input end of the signal comparison module and the input end of the signal inversion module, the output ends of the constant modulation signal generator and the triangle modulation signal generator are respectively connected to the input end of the signal comparison module, and the output end of the square wave modulation signal generator is connected to the input end of the logic gate module.

3. The sinusoidal pulse width modulation circuit of the six-switch converter according to claim 2, characterized in that: The signal comparison module includes a first comparator, a second comparator, a third comparator, a fourth comparator, a fifth comparator, a sixth comparator, a seventh comparator and an eighth comparator, wherein the non-phase input terminal of the first comparator is connected to the output terminal of the sinusoidal modulation signal generator of the upper inverter, the inverting input terminal of the first comparator is connected to the output terminal of the triangular modulation signal generator, the non-phase input terminal of the second comparator is connected to the output terminal of the signal inversion module, the inverting input terminal of the second comparator is connected to the output terminal of the triangular modulation signal generator, the non-phase input terminal of the third comparator is connected to the output terminal of the sinusoidal modulation signal generator of the lower inverter, the inverting input terminal of the third comparator is connected to the output terminal of the triangular modulation signal generator, the non-phase input terminal of the fourth comparator is connected to the output terminal of the signal inversion module The output end is connected, the inverting input end of the fourth comparator is connected to the output end of the triangular modulation signal generator, the non-phase input end of the fifth comparator is connected to the output end of the constant modulation signal generator, the inverting input end of the fifth comparator is connected to the output end of the sine modulation signal generator of the upper inverter, the non-phase input end of the sixth comparator is connected to the output end of the constant modulation signal generator, the inverting input end of the sixth comparator is connected to the output end of the signal inversion module, the non-phase input end of the seventh comparator is connected to the output end of the constant modulation signal generator, the inverting input end of the seventh comparator is connected to the output end of the sine modulation signal generator of the lower inverter, the non-phase input end of the eighth comparator is connected to the output end of the constant modulation signal generator, and the inverting input end of the eighth comparator is connected to the output end of the signal inversion module.

4. The sinusoidal pulse width modulation circuit of the six-switch converter according to claim 2, characterized in that: The signal inversion module includes a first inverter and a second inverter, the input end of the first inverter is connected to the output end of the sinusoidal modulation signal generator of the upper inverter, the output end of the first inverter is connected to the input end of the sixth comparator, the input end of the second inverter is connected to the output end of the sinusoidal modulation signal generator of the lower inverter, and the output end of the second inverter is connected to the input end of the fourth comparator. The signal inversion module is used to reverse the sinusoidal modulation signal of the upper inverter and the sinusoidal modulation signal of the lower inverter.

5. The sinusoidal pulse width modulation circuit of the six-switch converter according to claim 2, characterized in that: The logic gate module includes a first OR gate, a second OR gate, a third OR gate, a fourth OR gate, a fifth OR gate, a sixth OR gate, a first AND gate, a second AND gate, a third AND gate, a fourth AND gate and a NOT gate. The input end of the first OR gate is connected to the output end of the first comparator and the square wave modulation signal generator, the input end of the second OR gate is connected to the square wave modulation signal generator and the output end of the second comparator, the input end of the fifth OR gate is connected to the output end of the NOT gate and the output end of the third comparator, the input end of the sixth OR gate is connected to the output end of the NOT gate and the output end of the fourth comparator, the input end of the first AND gate is connected to the output end of the fifth comparator and the output end of the NOT gate, the input end of the second AND gate is connected to the output end of the square wave modulation signal generator and the output end of the seventh comparator, the output end of the first AND gate is connected to the output end of the second AND gate and the input end of the third OR gate, the input end of the third AND gate is connected to the output end of the sixth comparator and the output end of the NOT gate, the fourth AND gate is connected to the output end of the square wave modulation signal generator and the output end of the eighth comparator, and the output end of the third AND gate is connected to the output end of the fourth AND gate and the input end of the fourth OR gate.

6. The sinusoidal pulse width modulation circuit of the six-switch converter according to claim 5, characterized in that: The power device includes: a first power tube, a second power tube, a third power tube, a fourth power tube, a fifth power tube and a sixth power tube, the input end of the first power tube is connected to the output end of the first OR gate, the input end of the second power tube is connected to the output end of the second OR gate, the input end of the third power tube is connected to the output end of the third OR gate, the input end of the fourth power tube is connected to the output end of the fourth OR gate, the input end of the fifth power tube is connected to the output end of the fifth OR gate, and the input end of the sixth power tube is connected to the output end of the sixth OR gate.

7. A sinusoidal pulse width modulation method for a six-switch converter, characterized in that: The sinusoidal pulse width modulation method is applied to the sinusoidal pulse width modulation circuit according to any one of claims 1 to 6, comprising the following steps: S1: The signal generator module outputs the sinusoidal modulation signal of the upper inverter, the sinusoidal modulation signal of the lower inverter, the square wave modulation signal and the triangle modulation signal respectively; S2: Inputting the sinusoidal modulation signal of the upper inverter, the sinusoidal modulation signal of the lower inverter and the triangular modulation signal into a signal comparison module; S3: Compare the sinusoidal modulation signal of the upper inverter and the sinusoidal modulation signal of the lower inverter with the triangular modulation signal through a signal comparison module to generate a pulse width modulation signal, wherein the pulse width modulation signal controls the first power tube, the second power tube, the fifth power tube and the sixth power tube; S4: The square wave modulation signal controls the third power tube and the fourth power tube.

8. The sinusoidal pulse width modulation circuit of the six-switch converter according to claim 7, characterized in that: In step S3, the sinusoidal modulation signal of the upper inverter and the sinusoidal modulation signal of the lower inverter are respectively compared with the triangular modulation signal through a signal comparison module to generate a pulse width modulation signal, and the pulse width modulation signal controls the first power tube, the second power tube, the fifth power tube and the sixth power tube, including: The sinusoidal modulation signal of the upper inverter and the sinusoidal modulation signal of the lower inverter are respectively compared with the triangular modulation signal through the signal comparison module. If the sinusoidal modulation signal of the upper inverter is greater than the triangular modulation signal, the first power tube and the fifth power tube are at a high level. If the sinusoidal modulation signal of the upper inverter is less than the triangular modulation signal, the first power tube and the fifth power tube are at a low level. If the sinusoidal modulation signal of the lower inverter is greater than the triangular modulation signal, the second power tube and the sixth power tube are at a high level. If the sinusoidal modulation signal of the lower inverter is less than the triangular modulation signal, the second power tube and the sixth power tube are at a low level.

9. The sinusoidal pulse width modulation circuit of the six-switch converter according to claim 8, characterized in that: Step S4, the square wave modulation signal controls the third power tube and the fourth power tube, including: When the phases of the sinusoidal modulation signal of the upper inverter and the sinusoidal modulation signal of the lower inverter are opposite, the third power tube and the fourth power tube are alternately turned on under the control of the square wave modulation signal.

10. The sinusoidal pulse width modulation circuit of the six-switch converter according to claim 9, characterized in that: Calculating the switching frequencies of the third power tube and the fourth power tube includes: In the formula, is the switching frequency of the third power tube and the fourth power tube, is the carrier signal frequency, is the phase difference.

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