Control Method and System of Three-Level Six-Switch Split Topology Rectifier for SiC Devices

Abstract

The present invention belongs to the field of power electronics technology. The present invention relates to a control method and system for a three-level six-switch split topology rectifier of SiC devices, which generates a q-axis command current based on the three-phase grid voltage, the square-wave voltage transformation, the phase angles of the grid voltage and the square-wave voltage obtained after phase locking, and the d-axis command current generated according to the given and actual DC bus voltages; generates three-phase voltage modulation signals based on the command current, the phase angle of the grid voltage, the grid voltage and the grid current in the two-phase rotating coordinate system, and transforms them into voltage modulation signals in the two-phase stationary coordinate system, and generates large sector numbers according to the transformed voltage modulation signals; generates three-phase modulation waves based on the voltage modulation signals in the two-phase stationary coordinate system after translation processing, and generates drive signals according to the comparison results of the three-phase modulation waves and the set carrier wave, the NAND logic of the comparison results, and the large sector numbers. The present invention effectively reduces the distortion at the zero crossing of the AC current, the current waveform has a high sine degree, and the current quality is high.

Description

Technical Field

[0001] The present invention belongs to the technical field of power electronics, relates to rectifier control technology, and specifically, relates to a control method and system for a three-level six-switch split topology rectifier using SiC devices. Background Art

[0002] In modern power systems, rectifiers are key power electronic devices that convert alternating current into direct current and can be widely used in fields such as high-power DC power supplies and energy storage. The performance of rectifiers directly affects the efficiency and stability of power systems. Traditional two-level rectifiers use silicon (abbreviation: Si) material power switch devices. Although the technology is relatively mature, there are still many deficiencies in practical applications. First, the silicon material power switch devices have low voltage withstand, which cannot enable the rectifier to operate at a higher voltage level, restricting the application scenarios of the rectifier. Second, the silicon material power switch devices have large switching losses, reducing the efficiency of the rectifier; and the silicon material power switch devices have slow switching speeds and cannot further reduce the weight and volume of passive filters by increasing the switching frequency. Third, the number of output levels of the two-level rectifier topology is small, resulting in large harmonic currents on the AC side of the rectifier.

[0003] To solve these problems, researchers have begun to explore using silicon carbide (abbreviation: SiC) material power switch devices to replace traditional Si power switch devices. SiC material power switch devices have advantages such as high voltage withstand, low switching losses, and high switching speeds. These characteristics enable the rectifier to operate at a higher voltage level, thus expanding the application fields of the rectifier. At the same time, the low-loss characteristics of SiC material power switch devices help improve the efficiency of the rectifier, and the high switching speed enables the rectifier to reduce the volume and weight of passive filters by increasing the switching frequency, thereby enhancing the power density of the rectifier. However, directly using SiC material power switch devices also poses certain risks. Especially in traditional rectifier topologies, complementary SiC material power switch devices in the same bridge arm may affect each other, increasing the risk of bridge arm through short circuit. Therefore, it is necessary to improve the traditional rectifier topology to enhance the operating reliability of the rectifier.

[0004] Silicon carbide (SiC) material metal oxide semiconductor field effect transistor (hereinafter referred to as: SiC MOSFET), as a power switching device made of SiC material, has the advantages of high voltage resistance, low switching loss, and high switching speed. Applying SiC MOSFET to a three-level six-switch split topology rectifier can improve its switching frequency and efficiency. However, there are the following problems in the three-level six-switch split topology rectifier with SiC devices. If the traditional control strategy is adopted for the three-level six-switch split topology rectifier with SiC devices, in the traditional control strategy, it is usually required that the grid voltage and the output current maintain the same frequency and phase to achieve the goal of a power factor of 1, thereby maximizing the transmission of active power. However, in actual applications, due to the presence of filters, there is often a certain phase shift between the converted output voltage and current, which causes serious distortion of the three-phase current at the zero-crossing point. This current distortion not only reduces the sinusoidality of the alternating current but also generates a large amount of current harmonics, causing serious pollution to the power grid. When the harmonic current content in the power grid increases to a certain extent, it will further cause grid voltage distortion and affect the normal operation of power grid electrical equipment. Therefore, it is crucial to improve the quality of the alternating current on the AC side of the three-level six-switch split topology rectifier and reduce harmonic pollution. It is urgent to propose an effective solution to overcome this technical problem. Summary of the Invention

[0005] In view of the above problems such as zero-crossing current distortion existing in the prior art, the present invention provides a control method and system for a three-level six-switch split topology rectifier with SiC devices. By precisely locking the phase difference between the grid voltage and the square wave voltage, the q-axis reference current is generated, effectively reducing the zero-crossing distortion of the alternating current and significantly improving the sinusoidality of the alternating current waveform, thereby improving the quality of the alternating current.

[0006] In the first aspect of the present invention, a control method for a three-level six-switch split topology rectifier with SiC devices is provided, and the specific steps are as follows:

[0007] Static coordinate transformation and phase-locking step: Transform the three-phase grid voltage and the three-phase square wave voltage into the grid voltage and the square wave voltage in the two-phase static coordinate system, and perform phase-locking processing on the grid voltage and the square wave voltage in the two-phase static coordinate system to obtain the grid voltage phase angle and the square wave voltage phase angle;

[0008] Rotating coordinate transformation step: According to the voltage phase angle, transform the three-phase grid voltage and the three-phase grid current into the grid voltage and the grid current in the two-phase rotating coordinate system;

[0009] Command current generation step: Generate the d-axis command current according to the given DC bus voltage reference value and the actual DC bus voltage, and generate the q-axis command current according to the d-axis command current, the grid voltage phase angle, and the square wave voltage phase angle;

[0010] Modulation signal generation step: Generate the modulated wave command voltage in the two-phase rotating coordinate system according to the grid voltage phase angle, the grid voltage and grid current in the two-phase rotating coordinate system, the d-axis command current, and the q-axis command current, and transform the modulated wave command voltage in the two-phase rotating coordinate system into a three-phase voltage modulation signal;

[0011] Large sector number generation step: Transform the three-phase voltage modulation signal into a voltage modulation signal in the two-phase stationary coordinate system, generate a command signal according to the voltage modulation signal in the two-phase stationary coordinate system, and generate a large sector number according to the command signal;

[0012] Modulation signal translation step: Generate different modulation signals according to the voltage modulation signal in the two-phase stationary coordinate system and different set translation values, select the modulation signal corresponding to the large sector number from the different modulation signals, and obtain the translated voltage modulation signal in the two-phase stationary coordinate system according to the selected modulation signal;

[0013] Modulated wave generation step: Generate a three-phase initial modulated wave according to the translated voltage modulation signal in the two-phase stationary coordinate system, obtain a midpoint potential balance control signal according to the upper and lower capacitor voltages of the rectifier, and obtain a three-phase modulated wave by adding the midpoint potential balance control signal to the three-phase initial modulated wave;

[0014] Drive signal generation step: Generate different three-phase initial drive signals according to the comparison result between the three-phase modulated wave and the set carrier wave and the NAND logic of the comparison result, and select the three-phase initial drive pulse signal corresponding to the large sector number from the different three-phase initial drive signals as the three-phase drive signal.

[0015] Combined with the first aspect, in some embodiments, in the stationary coordinate transformation and phase-locking step, the method for transforming the three-phase grid voltage into the grid voltage in the two-phase stationary coordinate system is:

[0016] The grid voltage of phase A E A Subtract 0.5 times the grid voltage of phase B E B Then subtract 0.5 times the grid voltage of phase C E C After that, multiply by the first set coefficient to obtain the grid voltage E α ;

[0017] 0.866 times the grid voltage of phase B E B Subtract 0.866 times the grid voltage of phase C E C After that, multiply by the first set coefficient to obtain the grid voltage E β ;

[0018] The method for converting a three-phase square-wave voltage into a square-wave voltage in a two-phase stationary coordinate system is as follows:

[0019] The square-wave voltage of phase A V AN subtracts 0.5 times the square-wave voltage of phase B V BN and 0.5 times the square-wave voltage of phase C V CN and then multiplies by the first set coefficient to obtain a square-wave voltage V Nα ;

[0020] 0.866 times the square-wave voltage of phase B V BN subtracts 0.866 times the square-wave voltage of phase C V CN and then multiplies by the first set coefficient to obtain a square-wave voltage V Nβ ;

[0021] The method for performing phase-locked processing on the grid voltage in a two-phase stationary coordinate system to obtain the grid voltage phase angle is as follows:

[0022] The grid voltage E α and the direct signal of the feedback grid voltage E α The difference between them multiplies by the second set coefficient, subtracts the quadrature signal of the feedback grid voltage v α1 ' and then multiplies by the grid voltage angular frequency E α and then passes through an integral to obtain the feedback direct signal q_v α1 ' ; ω 1 The grid voltage v α1 ' ;

[0023] The grid voltage E β and the direct signal of the feedback grid voltage E β The difference between them multiplies by the second set coefficient, subtracts the quadrature signal of the feedback grid voltage v β1 ' and then multiplies by the grid voltage angular frequency E β and then passes through an integral to obtain the feedback direct signal q_v β1 ' and then multiplies by the grid voltage angular frequency ω 1 and then passes through an integral to obtain the feedback direct signalv β1 ' ;

[0024] Direct signal v α1 ' Minus the quadrature signal q_v β1 ' Then multiply by the third set coefficient to obtain a signal v αq1 Direct signal v β1 ' Plus the quadrature signal q_v α1 ' Then multiply by the third set coefficient to obtain a signal v βq1 ;

[0025] Signal v αq1 Multiply by the product of -sin( θ 1 ) and add the signal v βq1 Multiply by the product of cos( θ 1 ) to obtain signal v qq1 For signal v qq1 Perform PI regulation, then add 100π, then pass through an integral, and then perform a remainder operation with 2π to obtain the grid voltage phase angle θ 1 ;

[0026] The method for performing phase-locked processing on the square-wave voltage in the two-phase stationary coordinate system to obtain the square-wave voltage phase angle is as follows:

[0027] Square-wave voltage V Nα And the direct signal of the feedback square-wave voltage V Nα The difference is multiplied by the second set coefficient, and subtract the quadrature signal of the feedback square-wave voltage v α2 ' Then multiply by the square-wave voltage angular frequency V Nα The quadrature signal of q_v α2 ' Then pass through an integral to obtain the feedback direct signal ω 2 ; v α2 ' ;

[0028] Square-wave voltage V NβThe direct signal of the feedback square wave voltage V Nβ is multiplied by the second set coefficient after subtracting the feedback square wave voltage from the difference between the direct signal v β2 ' and the quadrature signal of the feedback square wave voltage V Nβ is then multiplied by the angular frequency of the square wave voltage q_v β2 ' and then integrated to obtain the feedback direct signal ω 2 ; v β2 ' ;

[0029] The direct signal v α2 ' minus the quadrature signal q_v β2 ' is then multiplied by the third set coefficient to obtain a signal v αq2 The direct signal v β2 ' plus the quadrature signal q_v α2 ' is then multiplied by the third set coefficient to obtain a signal v βq2 ;

[0030] The signal v αq2 multiplied by the product of -sin( θ 2 ) plus the signal v βq2 multiplied by the product of cos( θ 2 ) gives the signal v qq2 The signal v qq2 is PI - regulated, then added with 100π, then integrated, and then the remainder operation is performed with 2π to obtain the square wave voltage phase angle θ 2 .

[0031] Combined with the first aspect, in some embodiments, in the rotation coordinate transformation step, the method of transforming the three - phase grid voltage into the grid voltage in the two - phase rotating coordinate system according to the grid voltage phase angle is as follows:

[0032] The grid voltage of phase A E A minus 0.5 times the grid voltage of phase B E B and then minus 0.5 times the grid voltage of phase CE C After that, multiply by the first set coefficient to obtain the grid voltage E α ;

[0033] 0.866 times the grid voltage of phase B E B Subtract 0.866 times the grid voltage of phase C E C After that, multiply by the first set coefficient to obtain the grid voltage E β ;

[0034] Grid voltage E α Multiply by the product of cos( θ 1 ) and add the grid voltage E β Multiply by the product of sin( θ 1 ) to obtain the grid voltage on the d-axis in the two-phase rotating coordinate system E d , grid voltage E α Multiply by the product of -sin( θ 1 ) and add the grid voltage E β Multiply by the product of cos( θ 1 ) to obtain the grid voltage on the q-axis in the two-phase rotating coordinate system E q ;

[0035] The method for transforming three-phase grid currents into grid currents in the two-phase rotating coordinate system according to the grid voltage phase angle is as follows:

[0036] Grid current of phase A I A Multiply by 0.667 times sin( θ 1 ) and add the grid current of phase B I b Multiply by sin( θ 1 -2π / 3) and add the grid current of phase C I c Multiply by sin( θ 1 +2π / 3) to obtain the grid current on the d-axis in the two-phase rotating coordinate system i d ;

[0037] Grid current of phase A I aMultiply by 0.667 times cos( θ 1 ) and add the B-phase grid current I b Multiply by cos( θ 1 -2π / 3) and add the C-phase grid current I c Multiply by cos( θ 1 +2π / 3) to obtain the q-axis grid current in the two-phase rotating coordinate system i q .

[0038] Combined with the first aspect, in some embodiments, in the instruction current generation step, the method for generating the d-axis instruction current according to the given DC bus voltage reference value and the actual DC bus voltage is as follows:

[0039] Given DC bus voltage reference value u dcref * Subtract the actual DC bus voltage u dc The obtained difference is adjusted by PI to obtain the d-axis instruction current i d * ;

[0040] The method for generating the q-axis instruction current according to the d-axis instruction current, the grid voltage phase angle, and the square wave voltage phase angle is as follows:

[0041] Square wave voltage phase angle θ 2 Subtract the grid voltage phase angle θ 1 To obtain the difference Δ θ , the difference Δ θ After passing through the tangent function tan, tanΔ is obtained θ , tanΔ θ Multiply by the d-axis instruction current i d * To obtain the q-axis instruction current i q * .

[0042] Combined with the first aspect, in some embodiments, in the modulation signal generation step, the method for generating the modulation wave command voltage in the two-phase rotating coordinate system is as follows:

[0043] d-axis instruction current i d * Subtract the q-axis grid current iq The difference is adjusted by a PI controller to obtain a first result, and the d-axis grid voltage E d minus the first result to obtain the d-axis modulation wave command voltage in the two-phase rotating coordinate system u d * ;

[0044] The q-axis command current i q * minus the q-axis grid current i q The difference is adjusted by a PI controller to obtain a second result, and the q-axis grid voltage E q minus the second result to obtain the q-axis modulation wave command voltage in the two-phase rotating coordinate system u q * ;

[0045] The method for transforming the modulation wave command voltage in the two-phase rotating coordinate system into a three-phase voltage modulation signal is as follows:

[0046] The d-axis modulation wave command voltage u d * is multiplied by 2 / u dc to obtain the modulation signal u d1 * , and the q-axis modulation wave command voltage u q * is multiplied by 2 / u dc to obtain the modulation signal u q1 * ;

[0047] The modulation signal u d1 * is multiplied by the product of sin( θ 1 ) and added to the product of the modulation signal u q1 * and cos ( θ 1 ) to obtain the A-phase voltage modulation signal u A * ; The modulation signal u d1 * is multiplied by the product of sin( θ 1 -2π / 3) and added to the modulation signalu q1 * Multiplied by cos( θ 1 -2π / 3) to obtain the B-phase voltage modulation signal u B * , the modulation signal u d1 * Multiplied by sin( θ 1 +2π / 3) and added to the modulation signal u q1 * Multiplied by cos( θ 1 +2π / 3) to obtain the C-phase voltage modulation signal u C * .

[0048] Combined with the first aspect, in some embodiments, in the large sector number generation step, the method for transforming the three-phase voltage modulation signal into a voltage modulation signal in the two-phase stationary coordinate system is as follows:

[0049] The A-phase voltage modulation signal u A * Subtracting 0.5 times the B-phase voltage modulation signal u B * , and then subtracting 0.5 times the C-phase voltage modulation signal u C * and then multiplying by a first set coefficient to obtain the voltage modulation signal in the two-phase stationary coordinate system u α * ;

[0050] 0.866 times the B-phase voltage modulation signal u B * Subtracting 0.866 times the C-phase voltage modulation signal u C * and then multiplying by a first set coefficient to obtain the voltage modulation signal in the two-phase stationary coordinate system u β * ;

[0051] The method for generating an instruction signal according to the voltage modulation signal in the two-phase stationary coordinate system is as follows:

[0052] Comparing the voltage modulation signal u α *and 0, if the voltage modulation signal u α * ≥0, then generate the first initial comparison result as 1, if the voltage modulation signal < 0, then generate the first initial comparison result as 0, and multiply the first initial comparison result by 4 to obtain the first comparison result;

[0053] 1.732 times the voltage modulation signal u β * Subtract the voltage modulation signal u α * to obtain the first comparison signal, compare the first comparison signal with 0, if the first comparison signal ≥ 0, then generate the second initial comparison result as 1, if the first comparison signal < 0, then generate the second initial comparison result as 0, and multiply by 2 to obtain the second comparison result;

[0054] 1.732 times the voltage modulation signal u β * Add the voltage modulation signal u α * to obtain the second comparison signal, compare the second comparison signal with 0, if the second comparison signal ≥ 0, then generate the third comparison result as 1, if the second comparison signal < 0, then generate the third comparison result as 0;

[0055] Add the first comparison result, the second comparison result, and the third comparison result to obtain the command signal;

[0056] The method for generating the large sector number according to the command signal is as follows:

[0057] If the command signal is 0, then the large sector number N is 5; if the command signal is 1, then the large sector number N is 0; if the command signal is 2, then the large sector number N is 4; if the command signal is 3, then the large sector number N is 3; if the command signal is 4, then the large sector number N is 6; if the command signal is 5, then the large sector number N is 1; if the command signal is 6, then the large sector number N is 0; if the command signal is 7, then the large sector number N is 2.

[0058] Combined with the first aspect, in some embodiments, in the modulation signal translation step, the method for generating different modulation signals according to the voltage modulation signal in the two-phase stationary coordinate system and different set translation values is as follows:

[0059] The voltage modulation signal u α * Subtract 0.333 to obtain the first initial modulation signal, the voltage modulation signal u α *Add 0.333 to obtain the second initial modulation signal, the voltage modulation signal u β * Subtract 0.577 as the third initial modulation signal, the voltage modulation signal u β * Add 0.577 as the fourth initial modulation signal;

[0060] Take the first initial modulation signal and the voltage modulation signal u α * as the first modulation signal, whose corresponding large sector number N is 1; take the first initial modulation signal and the third initial modulation signal as the second modulation signal, whose corresponding large sector number N is 2; take the second initial modulation signal and the third initial modulation signal as the third modulation signal, whose corresponding large sector number N is 3; take the second initial modulation signal and the voltage modulation signal u β * as the fourth modulation signal, whose corresponding large sector number N is 4; take the second initial modulation signal and the fourth initial modulation signal as the fifth modulation signal, whose corresponding large sector number N is 5; take the first initial modulation signal and the fourth initial modulation signal as the sixth modulation signal, whose corresponding large sector number N is 6;

[0061] The method for obtaining the voltage modulation signal in the translated two-phase stationary coordinate system according to the selected modulation signal is as follows:

[0062] Multiply the selected modulation signal by 2 to obtain the voltage modulation signal in the translated two-phase stationary coordinate system u α ' and the voltage modulation signal u β ' .

[0063] Combined with the first aspect, in some embodiments, in the modulation wave generation step, the method for generating a three-phase initial modulation wave according to the voltage modulation signal in the translated two-phase stationary coordinate system is as follows:

[0064] Multiply 0.866 times the voltage modulation signal u β ' Subtract 0.5 times the voltage modulation signal u α ' to obtain the signal u B ' ; multiply negative 0.866 times the voltage modulation signal u β ' Subtract 0.5 times the voltage modulation signalu α ' Obtain a signal u C ' ;

[0065] Voltage modulation signal u α ' Add 1 and then multiply by 1 / 2 to obtain a signal u A1 ' , the signal u B ' Add 1 and then multiply by 1 / 2 to obtain a signal u B1 ' , the signal u C ' Add 1 and then multiply by 1 / 2 to obtain a signal u C1 ' ;

[0066] From the signals u A1 ' , the signal u B1 ' , the signal u C1 ' Take the maximum and minimum values, and multiply the difference obtained by subtracting the maximum value and the minimum value from 1 by 1 / 2 to obtain the adjustment value;

[0067] The signal u A1 ' Add the adjustment value to obtain the initial modulation wave of phase A v tA , the signal u B1 ' Add the adjustment value to obtain the initial modulation wave of phase B v tB , the signal u C1 ' Add the adjustment value to obtain the initial modulation wave of phase C v tC ;

[0068] The method for obtaining the neutral point potential balance control signal according to the upper and lower capacitor voltages of the rectifier is as follows:

[0069] The upper capacitor voltage of the rectifier u dc1 Subtract the lower capacitor voltage of the rectifier u dc2Multiply the difference by -1 to obtain the midpoint potential balance control signal n p 。

[0070] Combined with the first aspect, in some embodiments, in the step of generating the driving signal, the method for generating different three-phase initial driving signals according to the comparison result between the three-phase modulation wave and the set carrier wave and the NAND logic of the comparison result is as follows:

[0071] Compare the A-phase modulation wave m tzA with the set carrier wave m s to obtain the first modulation wave comparison result, and perform NAND logic on the first modulation wave comparison result to obtain the first logic result; compare the B-phase modulation wave m tzB with the set carrier wave m s to obtain the second modulation wave comparison result, and perform NAND logic on the second modulation wave comparison result to obtain the second logic result; compare the C-phase modulation wave m tzC with the set carrier wave m s to obtain the third modulation wave comparison result, and perform NAND logic on the third modulation wave comparison result to obtain the third logic result;

[0072] Take the first logic result, the second modulation wave comparison result, and the third modulation wave comparison result as the first three-phase initial driving signal, whose corresponding large sector number N is 1; take the first logic result, the second logic result, and the third modulation wave comparison result as the second three-phase initial driving signal, whose corresponding large sector number N is 2; take the first modulation wave comparison result, the second logic result, and the third modulation wave comparison result as the third three-phase initial driving signal, whose corresponding large sector number N is 3; take the first modulation wave comparison result, the second logic result, and the third logic result as the fourth three-phase initial driving signal, whose corresponding large sector number N is 4; take the first modulation wave comparison result, the second modulation wave comparison result, and the third logic result as the fifth three-phase initial driving signal, whose corresponding large sector number N is 5; take the first logic result, the second modulation wave comparison result, and the third logic result as the sixth three-phase initial driving signal, whose corresponding large sector number N is 6.

[0073] In the second aspect of the present invention, a three-level six-switch split-topology rectifier control system for SiC devices is provided, which is used to implement the SiC device three-level six-switch split-topology rectifier control method described in the first aspect of the present invention, including:

[0074] A setting module for setting different coefficients;

[0075] A grid voltage static coordinate transformation module that transforms the three-phase grid voltage into the grid voltage in the two-phase static coordinate system;

[0076] A square-wave voltage stationary coordinate transformation module that transforms three-phase square-wave voltage into square-wave voltage in a two-phase stationary coordinate system;

[0077] A first phase-locked module that performs phase-locking processing on the grid voltage in a two-phase stationary coordinate system to obtain the grid voltage phase angle;

[0078] A second phase-locked module that performs phase-locking processing on the square-wave voltage in a two-phase stationary coordinate system to obtain the square-wave voltage phase angle;

[0079] A grid voltage rotating coordinate transformation module that transforms three-phase grid voltage into grid voltage in a two-phase rotating coordinate system according to the voltage phase angle;

[0080] A grid current rotating coordinate transformation module that transforms three-phase grid current into grid current in a two-phase rotating coordinate system according to the voltage phase angle;

[0081] A d-axis command current generation module that generates a d-axis command current according to the given DC bus voltage reference value and the actual DC bus voltage;

[0082] A q-axis command current generation module that generates a q-axis command current according to the d-axis command current, the grid voltage phase angle, and the square-wave voltage phase angle;

[0083] A modulation wave command voltage generation module that generates a modulation wave command voltage in a two-phase rotating coordinate system according to the grid voltage phase angle, the grid voltage and grid current in the two-phase rotating coordinate system, the d-axis command current, and the q-axis command current;

[0084] A modulation signal rotating coordinate transformation module that transforms the modulation wave command voltage in a two-phase rotating coordinate system into three-phase voltage modulation signals;

[0085] A large sector number generation module that transforms the three-phase voltage modulation signals into voltage modulation signals in a two-phase stationary coordinate system, generates a command signal according to the voltage modulation signals in the two-phase stationary coordinate system, and generates a large sector number according to the command signal;

[0086] A modulation signal translation module that generates different modulation signals according to the voltage modulation signals in a two-phase stationary coordinate system and different set translation values, selects the modulation signal corresponding to the large sector number from the different modulation signals, and obtains the translated voltage modulation signals in a two-phase stationary coordinate system according to the selected modulation signal;

[0087] A modulation wave generation module that generates three-phase initial modulation waves according to the translated voltage modulation signals in a two-phase stationary coordinate system, obtains a midpoint potential balance control signal according to the upper and lower capacitor voltages of the rectifier, and obtains three-phase modulation waves by adding the midpoint potential balance control signal to the three-phase initial modulation waves;

[0088] The drive signal generation module generates different three-phase initial drive signals based on the comparison results of the three-phase modulation wave and the set carrier wave and the NAND logic of the comparison results, and selects the three-phase initial drive pulse signal corresponding to the large sector number from the different three-phase initial drive signals as the three-phase drive signal.

[0089] Compared with the prior art, the advantages and positive effects of the present invention are as follows:

[0090] The three-level six-switch split topology rectifier control method and system for SiC devices provided by the present invention can accurately obtain the phase difference between the grid voltage and the square wave voltage through coordinate transformation and phase locking, and then generate the specified current on the q-axis, effectively reducing the zero-crossing distortion of the alternating current and improving the sinusoidality of the alternating current waveform, thereby effectively improving the current quality. Description of the Drawings

[0091] Figure 1 It is the circuit diagram of the three-level six-switch split topology rectifier for SiC devices described in the embodiment of the present invention;

[0092] Figure 2 It is the flow chart of the three-level six-switch split topology rectifier control method for SiC devices described in the embodiment of the present invention;

[0093] Figure 3 It is the schematic diagram of the static coordinate transformation of the three-phase grid voltage described in the embodiment of the present invention;

[0094] Figure 4 It is the schematic diagram of the static coordinate transformation of the three-phase square wave voltage described in the embodiment of the present invention;

[0095] Figure 5 It is the schematic diagram of the phase-locked processing of the two-phase grid voltage described in the embodiment of the present invention;

[0096] Figure 6 It is the schematic diagram of the phase-locked processing of the two-phase square wave voltage described in the embodiment of the present invention;

[0097] Figure 7 It is the schematic diagram of the rotating coordinate transformation of the three-phase grid voltage described in the embodiment of the present invention;

[0098] Figure 8 It is the schematic diagram of the rotating coordinate transformation of the three-phase grid current described in the embodiment of the present invention;

[0099] Figure 9 It is the schematic diagram of the generation of the d-axis command current described in the embodiment of the present invention;

[0100] Figure 10 It is the schematic diagram of the generation of the q-axis command current described in the embodiment of the present invention;

[0101] Figure 11Schematic diagram of the generation of the modulation wave command voltage according to the embodiments of the present invention;

[0102] Figure 12 Schematic diagram of the rotational coordinate transformation of the modulation signal according to the embodiments of the present invention;

[0103] Figure 13 Schematic diagram of the generation of the large sector number according to the embodiments of the present invention;

[0104] Figure 14 Schematic diagram of the translation of the modulation signal according to the embodiments of the present invention;

[0105] Figure 15 Schematic diagram of the generation of the modulation wave according to the embodiments of the present invention;

[0106] Figure 16 Schematic diagram of the generation of the drive signal according to the embodiments of the present invention;

[0107] Figure 17 Block diagram of the control system of the three-level six-switch split topology rectifier of the SiC device according to the embodiments of the present invention;

[0108] Figure 18 Schematic diagram of the three-phase output current waveform using the traditional control method;

[0109] Figure 19 Schematic diagram of the three-phase output current waveform of the control method and system of the three-level six-switch split topology rectifier of the SiC device according to the embodiments of the present invention.

[0110] In the figure, 1. Grid voltage static coordinate transformation module, 2. Square wave voltage static coordinate transformation module, 3. First phase-locked module, 4. Second phase-locked module, 5. Grid voltage rotational coordinate transformation module, 6. Grid current rotational coordinate transformation module, 7. d-axis command current generation module, 8. q-axis command current generation module, 9. Modulation wave command voltage generation module, 10. Modulation signal rotational coordinate transformation module, 11. Large sector number generation module, 12. Modulation signal translation module, 13. Modulation wave generation module, 14. Drive signal generation module. Detailed implementation manners

[0111] Next, the present invention will be specifically described by way of exemplary embodiments in conjunction with the accompanying drawings. However, it should be understood that without further narration, the elements, structures and features in one embodiment can also be beneficially combined into other embodiments.

[0112] Figure 1 The main topology circuit of the three-level six-switch split topology rectifier of the SiC device shown, where u dc is the DC side voltage, C1 , C 2 is the DC bus capacitor, Q A1 , Q A2 is the SiC MOSFET power switch device of phase A, D A1 , D A2 , D A3 , D A4 is the diode of phase A, L A1 , L A2 is the isolation inductor of phase A; Q B1 , Q B2 is the SiC MOSFET power switch device of phase B, D B1 、D B2 、D B3 、 D B4 is the diode of phase B, L B1 、L B2 is the isolation inductor of phase B; Q C1 、Q C2 is the SiC MOSFET power switch device of phase C, D C1 、 D C2 、D C3 、D C4 is the diode of phase C, L C1 、L C2 is the isolation inductor of phase C; L A 、L B 、L C is the three-phase filter inductor, E A 、E B 、E C is the three-phase grid voltage, IA , I B , I C is the three-phase grid current.

[0113] Continue to refer to Figure 1 . Since the ABC three-phase bridge arms are completely symmetrical, the connection method of the main circuit is illustrated by taking phase A as an example. The DC bus capacitor C 1 and the DC bus capacitor C 2 are connected to point O; one end of the power switch device Q A1 is connected to the diode D A3 through X A4 point, and the other end is connected to the diode D A1 through X A2 point. The other end of the diode D A1 is connected to the DC bus capacitor C 2 through point N; at the same time, the other end of the power switch device Q A1 is connected to the isolation inductor L A1 through X A2 point. The other end of the isolation inductor L A1 is connected to the filter inductor L A through X A1 point. The other end of the filter inductor L A is directly connected to the grid voltage E A ; one end of the power switch device Q A2 is connected to the DC bus capacitor C 1 through point O, and the other end is connected to the diode D A2 through X A5 point. The other end of the diode D A2 is connected to the diode D A4 through X A3 point. The other end of the diode D A4 is connected to the DC bus capacitorC 1 Connected through point P; meanwhile, the isolation inductor L A2 The other end of is connected to the filter inductor L A Through X A1 Point connection, and the other end of the filter inductor L A Is directly connected to the grid voltage E A Direct connection. The connection methods of the B-phase and C-phase main circuits are the same as that of the A-phase, which will not be elaborated here.

[0114] The above three-level six-switch split-topology rectifier uses SiC power switch devices and adds isolation inductors to each phase arm, which can reduce the mutual influence of complementary SiC power switch devices on the same phase arm and has high operation reliability.

[0115] For the above SiC device three-level six-switch split-topology rectifier, a control method and system for the SiC device three-level six-switch split-topology rectifier provided by the present invention generate a q-axis command current according to the three-phase grid voltage, the square-wave voltage transformation, the grid voltage phase angle and the square-wave voltage phase angle obtained after phase locking, and the d-axis command current generated according to the given and actual DC bus voltage; generate three-phase voltage modulation signals according to the command current, the grid voltage phase angle, the grid voltage and the grid current in the two-phase rotating coordinate system, and transform them into voltage modulation signals in the two-phase stationary coordinate system, generate large sector numbers according to the transformed voltage modulation signals; generate three-phase modulation waves according to the translated voltage modulation signals in the two-phase stationary coordinate system, and generate drive signals according to the comparison result between the three-phase modulation waves and the set carrier wave, the NAND logic of the comparison result, and the large sector number. It can effectively reduce the distortion of the AC current zero crossing, the current waveform has a high sinusoidality, and the current quality is high.

[0116] The following will describe in detail the control method and system for the SiC device three-level six-switch split-topology rectifier of the present invention with reference to the drawings and embodiments.

[0117] See Figure 2 , the first aspect embodiment of the present invention provides a control method for a SiC device three-level six-switch split-topology rectifier, and its specific steps are as follows:

[0118] S1. Static coordinate transformation and phase-locking step: Transform the three-phase grid voltage and the three-phase square-wave voltage into the grid voltage and the square-wave voltage in the two-phase stationary coordinate system, and perform phase-locking processing on the grid voltage and the square-wave voltage in the two-phase stationary coordinate system to obtain the grid voltage phase angle and the square-wave voltage phase angle.

[0119] The subsequent signal processing can be simplified through two-phase stationary coordinate transformation, the influence of three-phase imbalance can be removed, and the stability and anti-interference ability of the rectifier can be improved. By performing phase-locked processing on the grid voltage and square-wave voltage in the two-phase stationary coordinate system, the phase angle of the grid voltage and the phase angle of the square-wave voltage can be accurately extracted to ensure the accuracy of grid synchronous control.

[0120] Specifically, in some embodiments, referring to Figure 3 , the method for transforming the three-phase grid voltage into the grid voltage in the two-phase stationary coordinate system is:

[0121] The grid voltage of phase A E A minus 0.5 times the grid voltage of phase B E B and then minus 0.5 times the grid voltage of phase C E C and then multiplied by the first set coefficient to obtain the grid voltage E α ;

[0122] 0.866 times the grid voltage of phase B E B minus 0.866 times the grid voltage of phase C E C and then multiplied by the first set coefficient to obtain the grid voltage E β .

[0123] Specifically, in some embodiments, referring to Figure 4 , the method for transforming the three-phase square-wave voltage into the square-wave voltage in the two-phase stationary coordinate system is:

[0124] The square-wave voltage of phase A V AN subtracting 0.5 times the square-wave voltage of phase B V BN and 0.5 times the square-wave voltage of phase C V CN and then multiplied by the first set coefficient to obtain the square-wave voltage V Nα ;

[0125] 0.866 times the square-wave voltage of phase B V BN subtracting 0.866 times the square-wave voltage of phase C V CN , and then multiplied by the first set coefficient to obtain the square-wave voltage V Nβ .

[0126] Specifically, in some embodiments, referring to Figure 5, the method for performing phase-locking processing on the grid voltage in the two-phase stationary coordinate system to obtain the grid voltage phase angle is as follows:

[0127] Grid voltage E α and the feedback grid voltage E α of the direct signal v α1 ' the difference is multiplied by the second set coefficient and subtracted from the feedback grid voltage E α of the quadrature signal q_v α1 ' and then multiplied by the grid voltage angular frequency ω 1 , and then passed through an integral to obtain the feedback direct signal v α1 ' ;

[0128] Grid voltage E β and the feedback grid voltage E β of the direct signal v β1 ' the difference is multiplied by the second set coefficient, and subtracted from the feedback grid voltage E β of the quadrature signal q_v β1 ' and then multiplied by the grid voltage angular frequency ω 1 , and then passed through an integral to obtain the feedback direct signal v β1 ' ;

[0129] Direct signal v α1 ' minus the quadrature signal q_v β1 ' and then multiplied by the third set coefficient to obtain the signal v αq1 , direct signal v β1 ' plus the quadrature signal q_v α1 ' and then multiplied by the third set coefficient to obtain the signal v βq1 ;

[0130] Signal v αq1 is multiplied by -sin(θ 1 The product addition signal of v βq1 multiplied by cos( θ 1 ) to obtain the signal v qq1 , for the signal v qq1 After PI regulation, add 100π, then go through an integration, and then perform a remainder operation with 2π to obtain the grid voltage phase angle θ 1 . Specifically, in some embodiments, the PI regulation uses a transfer function of K PI = 0.571 + 50.766 / s of the PI regulator, where s is a complex variable in the frequency domain.

[0131] Specifically, in some embodiments, referring to Figure 6 , the method for performing phase-locked processing on the square-wave voltage in the two-phase stationary coordinate system to obtain the square-wave voltage phase angle is as follows:

[0132] The square-wave voltage V Nα and the direct signal of the feedback square-wave voltage V Nα The difference of v α2 ' is multiplied by a second set coefficient, subtract the quadrature signal of the feedback square-wave voltage V Nα The q_v α2 ' and then multiply by the square-wave voltage angular frequency ω 2 , and then go through an integration to obtain the feedback direct signal v α2 ' ;

[0133] The square-wave voltage V Nβ and the direct signal of the feedback square-wave voltage V Nβ The difference of v β2 ' is multiplied by a second set coefficient, subtract the quadrature signal of the feedback square-wave voltage V Nβ The q_v β2 ' and then multiply by the square-wave voltage angular frequency ω 2 , and then go through an integration to obtain the feedback direct signal vβ2 ' ;

[0134] Direct signal v α2 ' Minus quadrature signal q_v β2 ' Then multiply by the third set coefficient 0.5 to obtain a signal v αq2 , direct signal v β2 ' Plus quadrature signal q_v α2 ' Then multiply by the third set coefficient to obtain a signal v βq2 ;

[0135] Signal v αq2 Multiply by the product of -sin( θ 2 ) and add the signal v βq2 Multiply by the product of cos( θ 2 ) to obtain signal v qq2 , for signal v qq2 Perform PI regulation, then add 100π, then go through an integration, and then perform a remainder operation with 2π to obtain the square wave voltage phase angle θ 2 . Specifically, in some embodiments, the PI regulation uses a PI regulator with a transfer function of K PI = 0.571 + 50.766 / s , where s is a complex variable in the frequency domain.

[0136] Specifically, in some embodiments, the first set coefficient is set to but not limited to 0.816, the second coefficient is set to but not limited to 1.414, and the third set coefficient is set to but not limited to 0.5. It should be noted that the first set coefficient, the second set coefficient, and the third set coefficient can be specifically set according to actual needs.

[0137] S2. Rotating coordinate transformation step: Transform the three-phase grid voltage and three-phase grid current into the grid voltage and grid current in the two-phase rotating coordinate system according to the grid voltage phase angle. Convert the three-phase grid voltage and current to the rotating coordinate system to achieve decoupling control, improve the energy transmission efficiency, reduce the harmonic influence at the same time, and improve the power quality.

[0138] Specifically, in some embodiments, refer to Figure 7, the method of transforming three-phase grid voltage into grid voltage in a two-phase rotating coordinate system according to the grid voltage phase angle is as follows:

[0139] Grid voltage of phase A E A Subtract 0.5 times the grid voltage of phase B E B Then subtract 0.5 times the grid voltage of phase C E C After that, multiply by the first set coefficient to obtain the grid voltage E α ;

[0140] 0.866 times the grid voltage of phase B E B Subtract 0.866 times the grid voltage of phase C E C After that, multiply by the first set coefficient to obtain the grid voltage E β ;

[0141] Grid voltage E α Multiply by the product of cos( θ 1 ) and add the grid voltage E β Multiply by the product of sin( θ 1 ) to obtain the d-axis grid voltage in the two-phase rotating coordinate system E d , grid voltage E α Multiply by the product of -sin( θ 1 ) and add the grid voltage E β Multiply by the product of cos( θ 1 ) to obtain the q-axis grid voltage in the two-phase rotating coordinate system E q .

[0142] Specifically, in some embodiments, refer to Figure 8 , the method of transforming three-phase grid current into grid current in a two-phase rotating coordinate system according to the grid voltage phase angle is as follows:

[0143] Grid current of phase A I A Multiply by 0.667 times sin( θ 1 ) and add the grid current of phase B I b Multiply by sin( θ 1The product of -2π / 3) plus C-phase grid current I c multiplied by sin( θ 1 +2π / 3) gives the d-axis grid current in the two-phase rotating coordinate system i d ;

[0144] A-phase grid current I a multiplied by 0.667 times cos( θ 1 ) plus B-phase grid current I b multiplied by cos( θ 1 -2π / 3) plus C-phase grid current I c multiplied by cos( θ 1 +2π / 3) gives the q-axis grid current in the two-phase rotating coordinate system i q .

[0145] S3. Instruction current generation step: Generate the d-axis instruction current according to the given DC bus voltage reference value and the actual DC bus voltage, and generate the q-axis instruction current according to the d-axis instruction current, the grid voltage phase angle, and the square wave voltage phase angle. Calculating the q-axis instruction current through the d-axis instruction current, the grid voltage phase angle, and the square wave voltage phase angle can achieve precise control of reactive power. Since the dq-axis decoupling control converts the AC signal into a DC signal, it can avoid the steady-state error of the traditional PI control under the AC signal, improve the control accuracy, reduce the grid harmonic content, and improve the power quality of the rectifier.

[0146] Specifically, in some embodiments, continue to refer to Figure 9 , the method for generating the d-axis instruction current according to the given DC bus voltage reference value and the actual DC bus voltage is:

[0147] Given DC bus voltage reference value u dcref * subtracted from the actual DC bus voltage u dc The obtained difference is PI-regulated to obtain the d-axis instruction current i d * . The PI regulation uses a PI regulator with a transfer function of 0.4 + 10 / s .

[0148] Specifically, in some embodiments, continue to refer to Figure 10, the method for generating the q-axis command current based on the d-axis command current, the grid voltage phase angle, and the square-wave voltage phase angle is as follows:

[0149] Square-wave voltage phase angle θ 2 Subtract the grid voltage phase angle θ 1 To obtain the difference Δ θ , the difference Δ θ After passing through the tangent function tan, tanΔ is obtained θ , tanΔ θ Multiply by the d-axis command current i d * To obtain the q-axis command current i q * .

[0150] S4. Modulation signal generation step: Generate the modulation wave command voltage in the two-phase rotating coordinate system based on the grid voltage phase angle, the grid voltage and grid current in the two-phase rotating coordinate system, the d-axis command current, and the q-axis command current, and transform the modulation wave command voltage in the two-phase rotating coordinate system into a three-phase voltage modulation signal.

[0151] Calculating the modulation wave command voltage based on the grid voltage phase angle, the grid dq-axis voltage, current, and command current and converting it into a three-phase modulation signal can reduce the total harmonic distortion rate THD and improve the current tracking ability.

[0152] Specifically, in some embodiments, refer to Figure 11 , the method for generating the modulation wave command voltage in the two-phase rotating coordinate system is as follows:

[0153] d-axis command current i d * Subtract the q-axis grid current i q The difference is adjusted by a PI to obtain a first result, and the d-axis grid voltage E d Subtract the first result to obtain the d-axis modulation wave command voltage in the two-phase rotating coordinate system u d * ;

[0154] q-axis command current i q * Subtract the q-axis grid current i q The difference is adjusted by a PI to obtain a second result, and the q-axis grid voltage E qSubtract the second result to obtain the q-axis modulation wave command voltage in the two-phase rotating coordinate system u q * .

[0155] Specifically, in some embodiments, referring to Figure 12 , the method for transforming the modulation wave command voltage in the two-phase rotating coordinate system into a three-phase voltage modulation signal is as follows:

[0156] d-axis modulation wave command voltage u d * Multiply by 2 / u dc To obtain the modulation signal u d1 * , q-axis modulation wave command voltage u q * Multiply by 2 / u dc To obtain the modulation signal u q1 * ;

[0157] The modulation signal u d1 * Multiply by the product of sin( θ 1 ) and add the product of the modulation signal u q1 * Multiply by cos( θ 1 ) to obtain the A-phase voltage modulation signal u A * ; The modulation signal u d1 * Multiply by the product of sin( θ 1 - 2π / 3) and add the product of the modulation signal u q1 * Multiply by cos( θ 1 - 2π / 3) to obtain the B-phase voltage modulation signal u B * , the modulation signal u d1 * Multiply by the product of sin( θ 1 + 2π / 3) and add the product of the modulation signal u q1 * Multiply by cos(θ 1 The product of +2π / 3) gives the C-phase voltage modulation signal u C * .

[0158] S5. Large sector number generation step: Transform the three-phase voltage modulation signal into a voltage modulation signal in the two-phase stationary coordinate system, generate an instruction signal based on the voltage modulation signal in the two-phase stationary coordinate system, and generate a large sector number based on the instruction signal.

[0159] Specifically, in some embodiments, refer to Figure 13 , the method for transforming the three-phase voltage modulation signal into a voltage modulation signal in the two-phase stationary coordinate system is as follows:

[0160] The A-phase voltage modulation signal u A * Subtract 0.5 times the B-phase voltage modulation signal u B * , and then subtract 0.5 times the C-phase voltage modulation signal u C * After that, multiply by the first set coefficient to obtain the voltage modulation signal in the two-phase stationary coordinate system u α * ;

[0161] 0.866 times the B-phase voltage modulation signal u B * Subtract 0.866 times the C-phase voltage modulation signal u C * After that, multiply by the first set coefficient to obtain the voltage modulation signal in the two-phase stationary coordinate system u β * .

[0162] Specifically, in some embodiments, continue to refer to Figure 13 , the method for generating an instruction signal based on the voltage modulation signal in the two-phase stationary coordinate system is as follows:

[0163] Compare the voltage modulation signal u α * with 0. If the voltage modulation signal u α * ≥0, then generate the first initial comparison result as 1. If the voltage modulation signal < 0, then generate the first initial comparison result as 0. Multiply the first initial comparison result by 4 to obtain the first comparison result;

[0164] 1.732 times the voltage modulation signal u β * Subtract the voltage modulation signal u α * Obtain the first comparison signal, compare the first comparison signal with 0. If the first comparison signal ≥ 0, generate the second initial comparison result as 1. If the first comparison signal < 0, generate the second initial comparison result as 0, and multiply by 2 to obtain the second comparison result;

[0165] 1.732 times the voltage modulation signal u β * Add the voltage modulation signal u α * Obtain the second comparison signal, compare the second comparison signal with 0. If the second comparison signal ≥ 0, generate the third comparison result as 1. If the second comparison signal < 0, generate the third comparison result as 0;

[0166] Add the first comparison result, the second comparison result, and the third comparison result to obtain the command signal.

[0167] Specifically, in some embodiments, continue to refer to Figure 13 , the method for generating the large sector number according to the command signal is:

[0168] If the command signal is 0, the large sector number N is 5; if the command signal is 1, the large sector number N is 0; if the command signal is 2, the large sector number N is 4; if the command signal is 3, the large sector number N is 3; if the command signal is 4, the large sector number N is 6; if the command signal is 5, the large sector number N is 1; if the command signal is 6, the large sector number N is 0; if the command signal is 7, the large sector number N is 2.

[0169] S6. Modulation signal translation step: Generate different modulation signals according to the voltage modulation signal in the two-phase stationary coordinate system and different set translation values, select the modulation signal corresponding to the large sector number from the different modulation signals, and obtain the translated voltage modulation signal in the two-phase stationary coordinate system according to the selected modulation signal. Generating different modulation signals by setting the translation value improves the flexibility of modulation. By analyzing the large sector numbers corresponding to multiple modulation signals and selecting the most suitable modulation signal, it is ensured that the rectifier output voltage vector is located in the optimal sector, reducing the modulation error, improving the control accuracy, reducing the total harmonic distortion rate THD, improving the current tracking ability, and thus improving the power quality and making the rectifier current output smoother.

[0170] Specifically, in some embodiments, refer to Figure 14, the method for generating different modulation signals based on the voltage modulation signal in the two-phase stationary coordinate system and different set translation values is as follows:

[0171] Voltage modulation signal u α * Subtract 0.333 to obtain the first initial modulation signal, the voltage modulation signal u α * Add 0.333 to obtain the second initial modulation signal, the voltage modulation signal u β * Subtract 0.577 as the third initial modulation signal, the voltage modulation signal u β * Add 0.577 as the fourth initial modulation signal;

[0172] Take the first initial modulation signal and the voltage modulation signal u α * as the first modulation signal, whose corresponding large sector number N is 1; take the first initial modulation signal and the third initial modulation signal as the second modulation signal, whose corresponding large sector number N is 2; take the second initial modulation signal and the third initial modulation signal as the third modulation signal, whose corresponding large sector number N is 3; take the second initial modulation signal and the voltage modulation signal u β * as the fourth modulation signal, whose corresponding large sector number N is 4; take the second initial modulation signal and the fourth initial modulation signal as the fifth modulation signal, whose corresponding large sector number N is 5; take the first initial modulation signal and the fourth initial modulation signal as the sixth modulation signal, whose corresponding large sector number N is 6;

[0173] Specifically, in some embodiments, continue to refer to Figure 14 , the method for obtaining the translated voltage modulation signal in the two-phase stationary coordinate system according to the selected modulation signal is as follows:

[0174] Multiply the selected modulation signal by 2 to obtain the translated voltage modulation signal in the two-phase stationary coordinate system u α ' and the voltage modulation signal u β ' .

[0175] S7. Modulation Wave Generation Step: Generate three-phase initial modulation waves based on the voltage modulation signals in the translated two-phase stationary coordinate system, obtain the neutral point potential balance control signal according to the upper and lower capacitor voltages of the rectifier, and add the neutral point potential balance control signal to the three-phase initial modulation waves to obtain three-phase modulation waves. Obtaining the neutral point potential balance control signal according to the upper and lower capacitor voltages of the rectifier can improve the balance of the DC bus voltage. By compensating and correcting the initial modulation waves with the neutral point potential, optimizing the three-phase modulation waves, and using the compensated three-phase modulation waves for drive control, the high-order harmonic components can be reduced, the total harmonic distortion rate THD can be lowered, and the quality of the output current can be improved.

[0176] Specifically, in some embodiments, refer to Figure 15 , the method for generating three-phase initial modulation waves based on the voltage modulation signals in the translated two-phase stationary coordinate system is as follows:

[0177] Multiply the voltage modulation signal by 0.866 u β ' Subtract the voltage modulation signal multiplied by 0.5 u α ' To obtain signal u B ' ; Multiply the negative voltage modulation signal by 0.866 u β ' Subtract the voltage modulation signal multiplied by 0.5 u α ' To obtain signal u C ' ;

[0178] Add 1 to the voltage modulation signal u α ' And then multiply by 1 / 2 to obtain signal u A1 ' , signal u B ' Add 1 to it and then multiply by 1 / 2 to obtain signal u B1 ' , signal u C ' Add 1 to it and then multiply by 1 / 2 to obtain signal u C1 ' ;

[0179] From signal u A1 ' 、signalu B1 ' and take the maximum and minimum values from the signals u C1 ' ; multiply the difference obtained by subtracting the maximum value and the minimum value from 1 by 1 / 2 to get the adjustment value;

[0180] The signal u A1 ' plus the adjustment value to obtain the initial modulation wave of phase A v tA and the signal u B1 ' plus the adjustment value to obtain the initial modulation wave of phase B v tB and the signal u C1 ' plus the adjustment value to obtain the initial modulation wave of phase C v tC ;

[0181] Specifically, in some embodiments, referring to Figure 15 , the method for obtaining the neutral point potential balance control signal according to the upper and lower capacitor voltages of the rectifier is as follows:

[0182] The upper capacitor voltage of the rectifier u dc1 minus the lower capacitor voltage of the rectifier u dc2 multiply the difference by -1 to obtain the neutral point potential balance control signal n p .

[0183] S8. Driving signal generation step: Generate different three-phase initial driving signals according to the comparison results of the three-phase modulation waves and the set carrier wave and the NAND logic of the comparison results, and select the three-phase initial driving pulse signal corresponding to the large sector number from the different three-phase initial driving signals as the three-phase driving signals. Use NAND logic operation to process different comparison results, optimize the initial driving signals, avoid the interference of repeated switching, glitch signals and dead time, and improve the switching stability. By comparing the three-phase modulation waves with the carrier wave, logical optimization, and selecting the driving signal corresponding to the optimal large sector number, the optimal three-phase driving signals are finally generated, effectively reducing the total harmonic distortion rate THD and improving the output current quality.

[0184] Specifically, in some embodiments, referring to Figure 16 , the method for generating different three-phase initial driving signals according to the comparison results of the three-phase modulation waves and the set carrier wave and the NAND logic of the comparison results is as follows:

[0185] Compare the modulation wave of phase A mtzA With the set carrier wave m s Obtain the first modulation wave comparison result, perform NAND logic on the first modulation wave comparison result to obtain the first logic result; compare the B-phase modulation wave m tzB With the set carrier wave m s Obtain the second modulation wave comparison result, perform NAND logic on the second modulation wave comparison result to obtain the second logic result; compare the C-phase modulation wave m tzC With the set carrier wave m s Obtain the third modulation wave comparison result, perform NAND logic on the third modulation wave comparison result to obtain the third logic result;

[0186] Take the first logic result, the second modulation wave comparison result, and the third modulation wave comparison result as the first three-phase initial drive signal, and its corresponding large sector number N is 1; take the first logic result, the second logic result, and the third modulation wave comparison result as the second three-phase initial drive signal, and its corresponding large sector number N is 2; take the first modulation wave comparison result, the second logic result, and the third modulation wave comparison result as the third three-phase initial drive signal, and its corresponding large sector number N is 3; take the first modulation wave comparison result, the second logic result, and the third logic result as the fourth three-phase initial drive signal, and its corresponding large sector number N is 4; take the first modulation wave comparison result, the second modulation wave comparison result, and the third logic result as the fifth three-phase initial drive signal, and its corresponding large sector number N is 5; take the first logic result, the second modulation wave comparison result, and the third logic result as the sixth three-phase initial drive signal, and its corresponding large sector number N is 6.

[0187] During Figure 13 the generation of the large sector number shown, Figure 14 the translation of the modulation signal, and Figure 16 the generation process of the drive signal shown, judge and select signals through the selection switch Switch. The Switch switch is divided into an input side and an output side. The input side has 7 signal input terminals. The uppermost 1 signal input terminal is the control signal input terminal, and the remaining 6 input terminals are selection signal input terminals. The output side has only one signal output terminal. Select which selection signal input terminal to input the signal according to the control signal. For example: if the control signal is 6, select to input the signal from the 6th selection signal input terminal and output it from the signal output terminal.

[0188] Refer to Figure 17 , the second aspect embodiment of the present invention provides a SiC device three-level six-switch split topology rectifier control system for implementing the SiC device three-level six-switch split topology rectifier control method described in the first aspect embodiment of the present invention, including:

[0189] A setting module (not shown in the figure) for setting different coefficients;

[0190] A three-phase grid voltage stationary coordinate transformation module 1 for transforming the three-phase grid voltage into the grid voltage in a two-phase stationary coordinate system;

[0191] A square-wave voltage stationary coordinate transformation module 2 for transforming the three-phase square-wave voltage into the square-wave voltage in a two-phase stationary coordinate system;

[0192] A first phase-locked module 3 for performing phase-locking processing on the grid voltage in a two-phase stationary coordinate system to obtain the grid voltage phase angle;

[0193] A second phase-locked module 4 for performing phase-locking processing on the square-wave voltage in a two-phase stationary coordinate system to obtain the square-wave voltage phase angle;

[0194] A three-phase grid voltage rotating coordinate transformation module 5 for transforming the three-phase grid voltage into the grid voltage in a two-phase rotating coordinate system according to the voltage phase angle;

[0195] A three-phase grid current rotating coordinate transformation module 6 for transforming the three-phase grid current into the grid current in a two-phase rotating coordinate system according to the voltage phase angle;

[0196] A d-axis command current generation module 7 for generating a d-axis command current according to a given DC bus voltage reference value and the actual DC bus voltage;

[0197] A q-axis command current generation module 8 for generating a q-axis command current according to the d-axis command current, the grid voltage phase angle, and the square-wave voltage phase angle;

[0198] A modulation wave command voltage generation module 9 for generating a modulation wave command voltage in a two-phase rotating coordinate system according to the grid voltage phase angle, the grid voltage and grid current in a two-phase rotating coordinate system, the d-axis command current, and the q-axis command current;

[0199] A modulation signal rotating coordinate transformation module 10 for transforming the modulation wave command voltage in a two-phase rotating coordinate system into a three-phase voltage modulation signal;

[0200] A large sector number generation module 11 for transforming the three-phase voltage modulation signal into a voltage modulation signal in a two-phase stationary coordinate system, generating a command signal according to the voltage modulation signal in a two-phase stationary coordinate system, and generating a large sector number according to the command signal;

[0201] A modulation signal translation module 12 for generating different modulation signals according to the voltage modulation signal in a two-phase stationary coordinate system and different set translation values, selecting the modulation signal corresponding to the large sector number from the different modulation signals, and obtaining the translated voltage modulation signal in a two-phase stationary coordinate system according to the selected modulation signal;

[0202] The modulation wave generation module 13 generates three-phase initial modulation waves according to the voltage modulation signals in the translated two-phase stationary coordinate system, obtains the neutral point potential balance control signal based on the upper and lower capacitor voltages of the rectifier, and obtains three-phase modulation waves by adding the neutral point potential balance control signal to the three-phase initial modulation waves;

[0203] The drive signal generation module 14 generates different three-phase initial drive signals according to the comparison results of the three-phase modulation waves and the set carrier wave and the NAND logic of the comparison results, and selects the three-phase initial drive pulse signals corresponding to the large sector numbers from the different three-phase initial drive signals as the three-phase drive signals.

[0204] The three-level six-switch split topology rectifier control system of the SiC device of the present invention can accurately obtain the phase difference between the grid voltage and the square wave voltage through coordinate transformation and phase locking, and then generate the specified current on the q-axis, effectively reducing the distortion of the zero-crossing of the alternating current and improving the sinusoidality of the alternating current waveform, thereby effectively improving the current quality.

[0205] To verify the effectiveness of the control method and system of the three-level six-switch split topology rectifier of the SiC device of the present invention, a simulation model is built using SIMULINK for verification. The effective value of the grid line voltage is 380V, the frequency of the isosceles triangular wave of the reference signal U 0 is 10kHz, the frequency of the modulation wave SINA is 50Hz, the DC bus capacitor is C 1 and the DC bus capacitor C 2 is 2200μF, the switching frequency f s is 20kHz, the filter inductance L a 、the filter inductance L b and the filter inductance L c is 1.8mH. In the simulation model, the traditional control method and the control method and system of the three-level six-switch split topology rectifier of the SiC device proposed by the present invention are respectively adopted for the three-level six-switch split topology rectifier of the SiC device. Figure 18 The waveforms of the three-phase output currents using the traditional control method are given. Through Fourier analysis, the total harmonic distortion rates THD of the A, B, and C phase currents are 2.21%, 2.22%, and 2.26% respectively. Figure 19The three-phase output current waveforms of the three-level six-switch split topology rectifier control method and system proposed by the present invention are given. Through Fourier analysis, the total harmonic distortion rates THD of the three-phase currents of A, B, and C are 1.05%, 1.07%, and 1.08%, respectively. The sinusoidality of the three-phase output current waveforms is significantly improved, and the output current waveforms with zero-crossing distortion are effectively improved, verifying the effectiveness of the method and system proposed by the present invention.

[0206] The above embodiments are used to explain the present invention rather than to limit the present invention. Any modifications and changes made to the present invention within the spirit and scope of the claims of the present invention fall within the protection scope of the present invention.

Claims

1. A control method for a three-level six-switch split-topology rectifier of a SiC device, characterized in that: The specific steps are: The stationary coordinate transformation and phase-locking steps are as follows: transforming the three-phase grid voltage and the three-phase square wave voltage into the grid voltage and the square wave voltage in the two-phase stationary coordinate system, and performing phase-locking processing on the grid voltage and the square wave voltage in the two-phase stationary coordinate system to obtain the grid voltage phase angle and the square wave voltage phase angle; Rotation coordinate transformation step: transform the three-phase grid voltage and the three-phase grid current into the grid voltage and the grid current in the two-phase rotation coordinate system according to the voltage phase angle; The command current generation step is as follows: the d-axis command current is generated according to the given DC bus voltage reference value and the actual DC bus voltage, and the q-axis command current is generated according to the d-axis command current, the grid voltage phase angle and the square wave voltage phase angle; the method for generating the q-axis command current according to the d-axis command current, the grid voltage phase angle and the square wave voltage phase angle is as follows: Square wave voltage phase angle θ 2 minus grid voltage phase angle θ 1Get the difference Δ θ , the difference Δ θ After the tangent function tan, we get tanΔ θ , tanΔ θ Multiply the d-axis command current id* to obtain the q-axis command current iq*; Modulation signal generation step: generating a modulation wave command voltage in a two-phase rotating coordinate system according to a grid voltage phase angle, a grid voltage and a grid current in a two-phase rotating coordinate system, a d-axis command current, and a q-axis command current, and converting the modulation wave command voltage in the two-phase rotating coordinate system into a three-phase voltage modulation signal; The large sector number generating step includes: transforming the three-phase voltage modulation signal into a voltage modulation signal in a two-phase stationary coordinate system, generating a command signal according to the voltage modulation signal in the two-phase stationary coordinate system, and generating a large sector number according to the command signal; Modulation signal translation step: generating different modulation signals according to the voltage modulation signal in the two-phase stationary coordinate system and different set translation values, selecting the modulation signal corresponding to the large sector number from the different modulation signals, and obtaining the voltage modulation signal in the two-phase stationary coordinate system after translation according to the selected modulation signal; Modulation wave generation step: generate a three-phase initial modulation wave according to the voltage modulation signal in the two-phase stationary coordinate system after translation, obtain a midpoint potential balance control signal according to the upper and lower capacitor voltages of the rectifier, and obtain a three-phase modulation wave by adding the midpoint potential balance control signal to the three-phase initial modulation wave; The driving signal generating step is as follows: generating different three-phase initial driving signals according to the comparison result between the three-phase modulation wave and the set carrier wave and the logical negation of the comparison result, and selecting the three-phase initial driving pulse signal corresponding to the large sector number from the different three-phase initial driving signals as the three-phase driving signal.

2. The SiC device three-level six-switch split topology rectifier control method according to claim 1, characterized in that: In the stationary coordinate transformation and phase locking step, the method for transforming the three-phase grid voltage into the grid voltage in the two-phase stationary coordinate system is: A phase grid voltage E A Subtract 0.5 times the B-phase grid voltage E B Subtract 0.5 times the C phase grid voltage E C Then, multiply the first setting coefficient to get the grid voltage E α ; 0.866 times the B-phase grid voltage E B Subtract 0.866 times the C-phase grid voltage E C Then, multiply the first setting coefficient to get the grid voltage E β ; The method of converting the three-phase square wave voltage into a two-phase square wave voltage in a stationary coordinate system is: Phase A square wave voltage V AN Subtract 0.5 times the B-phase square wave voltage V BN and 0.5 times the C-phase square wave voltage V CN After that, multiply the first setting coefficient to get the square wave voltage V Nα ; 0.866 times the B-phase square wave voltage V BN Subtract 0.866 times the C-phase square wave voltage V CN , multiplied by the first set coefficient to obtain the square wave voltage V Nβ ; The method for obtaining the grid voltage phase angle by performing phase-locking processing on the grid voltage in the two-phase stationary coordinate system is: Grid voltage E α With feedback grid voltage E α Direct signal v α1 ' The difference is multiplied by the second setting coefficient, minus the feedback grid voltage E α The orthogonal signal q_v α1 ' Multiply the grid voltage angular frequency by ω 1. Then get the direct feedback signal through an integral v α1 ' ; Grid voltage E β With feedback grid voltage E β Direct signal v β1 ' The difference is multiplied by the second setting coefficient, minus the feedback grid voltage E β The orthogonal signal q_v β1 ' Multiply the grid voltage angular frequency by ω 1. Then get the direct feedback signal through an integral v β1 ' ; Direct signal v α1 ' Subtract quadrature signal q_v β1 ' Then multiply the third setting coefficient to get the signal v αq1 , direct signal v β1 ' Add quadrature signals q_v α1 ' Then multiply the third setting coefficient to get the signal v βq1 ; Signal v αq1 Multiplication - sin( θ 1) The product signal v βq1 Multiply cos( θ 1) The product of the signal v qq1 , for the signal v qq1 After PI adjustment, add 100π, then perform an integration, and then perform a modulo operation with 2π to obtain the grid voltage phase angle θ 1; The method for obtaining the phase angle of the square wave voltage by performing phase-locking processing on the square wave voltage in the two-phase stationary coordinate system is: Square wave voltage V Nα With feedback square wave voltage V Nα Direct signal v α2 ' The difference is multiplied by the second setting coefficient, minus the feedback square wave voltage V Nα The orthogonal signal q_v α2 ' Post-multiplied square wave voltage angular frequency ω 2. Then get the direct feedback signal through an integral v α2 ' ; Square wave voltage V Nβ With feedback square wave voltage V Nβ Direct signal v β2 ' The difference is multiplied by the second setting coefficient, minus the feedback square wave voltage V Nβ The orthogonal signal q_v β2 ' Post-multiplied square wave voltage angular frequency ω 2. Then get the direct feedback signal through an integral v β2 ' ; Direct signal v α2 ' Subtract quadrature signal q_v β2 ' Then multiply the third setting coefficient to get the signal v αq2 , direct signal v β2 ' Add quadrature signals q_v α2 ' Then multiply the third setting coefficient to get the signal v βq2 ; Signal v αq2 Multiplication - sin( θ 2) The product signal v βq2 Multiply cos( θ 2) The product of the signal v qq2 , for the signal v qq2 After PI adjustment, add 100π, then perform an integration, and then perform a modulo operation with 2π to obtain the square wave voltage phase angle θ 2.

3. The SiC device three-level six-switch split topology rectifier control method according to claim 2, characterized in that: In the rotating coordinate transformation step, the method of transforming the three-phase grid voltage into the grid voltage in the two-phase rotating coordinate system according to the voltage phase angle is: A phase grid voltage E A Subtract 0.5 times the B-phase grid voltage E B Subtract 0.5 times the C phase grid voltage E C Then, multiply the first setting coefficient to get the grid voltage E α ; 0.866 times the B-phase grid voltage E B Subtract 0.866 times the C-phase grid voltage E C Then, multiply the first setting coefficient to get the grid voltage E β ; Grid voltage E α Multiply cos( θ 1) Product of grid voltage E β Multiply sin( θ 1) to obtain the d-axis grid voltage in the two-phase rotating coordinate system E d , grid voltage E α Multiplication - sin( θ 1) Product of grid voltage E β Multiply cos( θ 1) to obtain the q-axis grid voltage in the two-phase rotating coordinate system E q ; The method of transforming the three-phase grid current into the grid current in the two-phase rotating coordinate system according to the voltage phase angle is: A phase grid current I A Multiply 0.667 times sin( θ 1) Add the B phase grid current I b Multiply sin( θ 1-2π / 3) plus the C-phase grid current I c Multiply sin( θ 1+2π / 3) to obtain the d-axis grid current in the two-phase rotating coordinate system i d ; A phase grid current I a Multiply by 0.667 times cos( θ 1) The product of the B-phase grid current I b Multiply cos( θ 1-2π / 3) plus the C-phase grid current I c Multiply by cos( θ 1+2π / 3) to obtain the q-axis grid current in the two-phase rotating coordinate system i q .

4. The SiC device three-level six-switch split topology rectifier control method according to claim 3, characterized in that: In the command current generating step, the method for generating the d-axis command current according to the given DC bus voltage reference value and the actual DC bus voltage is: Given DC bus voltage reference value u dcref * The actual DC bus voltage u dc The difference obtained by subtraction is adjusted by PI to obtain the d-axis command current i d * .

5. The SiC device three-level six-switch split topology rectifier control method according to claim 4, characterized in that: In the modulation signal generation step, the method for generating the modulation wave command voltage in the two-phase rotating coordinate system is: D-axis command current i d * Reduced q-axis grid current i q The difference is adjusted by a PI to obtain the first result, the d-axis grid voltage E d Subtract the first result to obtain the d-axis modulation wave command voltage in the two-phase rotating coordinate system u d * ; The q-axis refers to the command current i q * Reduced q-axis grid current i q The difference is adjusted by a PI to obtain the second result, the q-axis grid voltage E q Subtract the second result to obtain the q-axis modulation wave command voltage in the two-phase rotating coordinate system u q * ; The method of converting the modulation wave command voltage in the two-phase rotating coordinate system into a three-phase voltage modulation signal is: d-axis modulation wave command voltage u d * Multiply by 2 / u dc Get the modulated signal u d1 * , q-axis modulation wave command voltage u q * Multiply by 2 / u dc Get the modulated signal u q1 * ; Modulation Signal u d1 * Multiply sin( θ 1) The product modulated signal u q1 * Multiply cos( θ 1) to obtain the A phase voltage modulation signal u A * ; Modulation signal u d1 * Multiply sin( θ 1-2π / 3) product-add modulation signal u q1 * Multiply cos( θ 1-2π / 3) to obtain the B phase voltage modulation signal u B * , the modulation signal u d1 * Multiply sin( θ 1+2π / 3) product-add modulation signal u q1 * Multiply cos( θ 1+2π / 3) to obtain the C phase voltage modulation signal u C * .

6. The SiC device three-level six-switch split topology rectifier control method according to claim 5, characterized in that: In the large sector number generation step, the method of transforming the three-phase voltage modulation signal into a voltage modulation signal in a two-phase stationary coordinate system is: Phase A voltage modulation signal u A * Subtract 0.5 times the B-phase voltage modulation signal u B * , minus 0.5 times the C phase voltage modulation signal u C * After that, multiply the first setting coefficient to obtain the voltage modulation signal in the two-phase stationary coordinate system u α * ; 0.866 times the B phase voltage modulation signal u B * Subtract 0.866 times the C-phase voltage modulation signal u C * After that, multiply the first setting coefficient to obtain the voltage modulation signal in the two-phase stationary coordinate system u β * ; The method of generating a command signal according to a voltage modulation signal in a two-phase stationary coordinate system is: Comparison voltage modulation signal u α * and 0, if the voltage modulation signal u α * ≥0, the first initial comparison result is 1; if the voltage modulation signal is <0, the first initial comparison result is 0, and the first initial comparison result is multiplied by 4 to obtain the first comparison result; 1.732 times the voltage modulation signal u β * Subtract voltage modulation signal u α * Obtain a first comparison signal, compare the first comparison signal with 0, if the first comparison signal is ≥ 0, generate a second initial comparison result of 1, if the first comparison signal is < 0, generate a second initial comparison result of 0, and multiply by 2 to obtain a second comparison result; 1.732 times the voltage modulation signal u β * Apply voltage modulation signal u α * Obtain a second comparison signal, compare the second comparison signal with 0, if the second comparison signal ≥ 0, generate a third comparison result of 1, if the second comparison signal < 0, generate a third comparison result of 0; The first comparison result plus the second comparison result plus the third comparison result obtains the instruction signal; The method of generating a large sector number according to the command signal is: If the command signal is 0, the large sector number N is 5; if the command signal is 1, the large sector number N is 0; if the command signal is 2, the large sector number N is 4; if the command signal is 3, the large sector number N is 3; if the command signal is 4, the large sector number N is 6; if the command signal is 5, the large sector number N is 1; if the command signal is 6, the large sector number N is 0; if the command signal is 7, the large sector number N is 2.

7. The SiC device three-level six-switch split topology rectifier control method according to claim 1, characterized in that: In the modulation signal translation step, the method of generating different modulation signals according to the voltage modulation signal in the two-phase stationary coordinate system and different set translation values ​​is: Voltage modulation signal u α * Subtract 0.333 to get the first initial modulation signal, the voltage modulation signal u α * Add 0.333 to get the second initial modulation signal, the voltage modulation signal u β * Subtract 0.577 as the third initial modulation signal, the voltage modulation signal u β * Add 0.577 as the fourth initial modulation signal; The first initial modulation signal and the voltage modulation signal u α * As the first modulation signal, its corresponding large sector number N is 1; the first initial modulation signal and the third initial modulation signal are used as the second modulation signal, and its corresponding large sector number N is 2; the second initial modulation signal and the third initial modulation signal are used as the third modulation signal, and its corresponding large sector number N is 3; the second initial modulation signal and the voltage modulation signal u β * As the fourth modulation signal, its corresponding large sector number N is 4; The second initial modulation start signal and the fourth initial modulation signal are used as the fifth modulation signal, and the corresponding large sector number N is 5; the first initial modulation start signal and the fourth initial modulation signal are used as the sixth modulation signal, and the corresponding large sector number N is 6; The method of obtaining the voltage modulation signal in the two-phase stationary coordinate system after translation according to the selected modulation signal is: Multiply the selected modulation signal by 2 to obtain the voltage modulation signal in the two-phase stationary coordinate system after translation. u α ' and voltage modulation signal u β ' .

8. The SiC device three-level six-switch split topology rectifier control method according to claim 1, characterized in that: In the modulation wave generation step, the method for generating the three-phase initial modulation wave according to the voltage modulation signal in the translated two-phase stationary coordinate system is: The voltage modulation signal is 0.866 times u β ' Reduce the voltage modulation signal by 0.5 times u α ' Get the signal u B ' ; The voltage modulation signal is negative 0.866 times u β ' Reduce the voltage modulation signal by 0.5 times u α ' Get the signal u C ' ; Voltage modulation signal u α ' Add 1 and multiply by 1 / 2 to get the signal u A1 ' ,Signal u B ' Add 1 and multiply by 1 / 2 to get the signal u B1 ' ,Signal u C ' Add 1 and multiply by 1 / 2 to get the signal u C1 ' ; From the signal u A1 ' ,Signal u B1 ' ,Signal u C1 ' Take the maximum and minimum values, subtract the maximum and minimum values ​​from 1 and multiply the difference by 1 / 2 to get the adjustment value. Signal u A1 ' Add the adjustment value to get the initial modulation wave of phase A v tA ,Signal u B1 ' Add the adjustment value to get the initial modulation wave of phase B v tB ,Signal u C1 ' Add the adjustment value to get the initial modulation wave of phase C v tC ; The method of obtaining the midpoint potential balance control signal according to the upper and lower capacitor voltages of the rectifier is: Rectifier capacitor voltage u dc1 Reduce the capacitor voltage under the rectifier u dc2 The difference is multiplied by -1 to obtain the midpoint potential balance control signal n p .

9. The SiC device three-level six-switch split topology rectifier control method according to claim 8, characterized in that: In the driving signal generating step, the method of generating different three-phase initial driving signals according to the comparison result of the three-phase modulation wave and the set carrier wave and the logical negation of the comparison result is: Compare A phase modulation wave m tzA With carrier setting m s Obtain the first modulation wave comparison result, perform logical AND on the first modulation wave comparison result to obtain the first logic result; compare the B phase modulation wave m tzB With carrier setting m s Get the second modulation wave comparison result, perform logical AND on the second modulation wave comparison result to get the second logic result; compare the C phase modulation wave m tzC With carrier setting m s Obtaining a third modulation wave comparison result, and performing a logic AND operation on the third modulation wave comparison result to obtain a third logic result; The first logic result, the second modulation wave comparison result and the third modulation wave comparison result are used as the first three-phase initial drive signal, and the corresponding large sector number N is 1; the first logic result, the second logic result and the third modulation wave comparison result are used as the second three-phase initial drive signal, and the corresponding large sector number N is 2; the first modulation wave comparison result, the second logic result and the third modulation wave comparison result are used as the third three-phase initial drive signal, and the corresponding large sector number N is 3; the first modulation wave comparison result, the second logic result and the third logic result are used as the fourth three-phase initial drive signal, and the corresponding large sector number N is 4; the first modulation wave comparison result, the second modulation wave comparison result and the third logic result are used as the fifth three-phase initial drive signal, and the corresponding large sector number N is 5; the first logic result, the second modulation wave comparison result and the third logic result are used as the sixth three-phase initial drive signal, and the corresponding large sector number N is 6.

10. A SiC device three-level six-switch split-topology rectifier control system, used to implement the SiC device three-level six-switch split-topology rectifier control method according to any one of claims 1 to 9, characterized in that: include: Setting module, used to set different coefficients; A grid voltage static coordinate transformation module transforms the three-phase grid voltage into a grid voltage in a two-phase static coordinate system; A square wave voltage static coordinate transformation module transforms the three-phase square wave voltage into a square wave voltage in a two-phase static coordinate system; A first phase-locking module performs phase-locking processing on the grid voltage in a two-phase stationary coordinate system to obtain a grid voltage phase angle; The second phase-locking module performs phase-locking processing on the square wave voltage in the two-phase stationary coordinate system to obtain the square wave voltage phase angle; A grid voltage rotation coordinate transformation module transforms the three-phase grid voltage into a grid voltage in a two-phase rotation coordinate system according to the voltage phase angle; A grid current rotation coordinate transformation module transforms the three-phase grid current into a grid current in a two-phase rotation coordinate system according to the voltage phase angle; A d-axis command current generating module generates a d-axis command current according to a given DC bus voltage reference value and an actual DC bus voltage; A q-axis command current generating module generates a q-axis command current according to the d-axis command current, the grid voltage phase angle and the square wave voltage phase angle; A modulation wave command voltage generating module generates a modulation wave command voltage in a two-phase rotating coordinate system according to a grid voltage phase angle, a grid voltage and a grid current in a two-phase rotating coordinate system, a d-axis command current, and a q-axis command current; The modulation signal rotation coordinate conversion module converts the modulation wave command voltage in the two-phase rotation coordinate system into a three-phase voltage modulation signal; A large sector number generating module converts the three-phase voltage modulation signal into a voltage modulation signal in a two-phase stationary coordinate system, generates a command signal according to the voltage modulation signal in the two-phase stationary coordinate system, and generates a large sector number according to the command signal; A modulation signal translation module generates different modulation signals according to the voltage modulation signal in the two-phase stationary coordinate system and different set translation values, selects the modulation signal corresponding to the large sector number from the different modulation signals, and obtains the voltage modulation signal in the two-phase stationary coordinate system after translation according to the selected modulation signal; The modulation wave generation module generates a three-phase initial modulation wave according to the voltage modulation signal in the two-phase stationary coordinate system after translation, obtains a midpoint potential balance control signal according to the upper and lower capacitor voltages of the rectifier, and obtains a three-phase modulation wave by adding the midpoint potential balance control signal to the three-phase initial modulation wave; The drive signal generating module generates different three-phase initial drive signals according to the comparison result between the three-phase modulation wave and the set carrier wave and the AND-NOT logic of the comparison result, and selects the three-phase initial drive pulse signal corresponding to the large sector number from the different three-phase initial drive signals as the three-phase drive signal.

Images