SiC device three-level six-switch split topological rectifier control method and system

Abstract

The invention belongs to the technical field of power electronics, and relates to a SiC device three-level six-switch split topological rectifier control method and system. A q-axis instruction current is generated according to a power grid voltage phase angle and a square wave voltage phase angle obtained after conversion and phase locking of the three-phase power grid voltage and the square wave voltage, and a d-axis instruction current generated according to given and actual DC bus voltages; generating a three-phase voltage modulation signal according to the instruction current, the power grid voltage phase angle, and the power grid voltage and the power grid current under the two-phase rotating coordinate system, converting the three-phase voltage modulation signal into a voltage modulation signal under a two-phase static coordinate system, and generating a large sector number according to the converted voltage modulation signal; generating a three-phase modulation wave according to the translated voltage modulation signal under the two-phase static coordinate system, and generating a driving signal according to a comparison result of the three-phase modulation wave and a set carrier, and NAND logic and a large sector number of the comparison result. The alternating current zero-crossing distortion is effectively reduced, the sine degree of the current waveform is high, and the current quality is high.

Description

Technical Field

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

[0002] In modern power systems, rectifiers are key power electronic devices that convert AC power into DC power. They can be widely used in high-power DC power supplies, energy storage and other fields. The performance of the rectifier directly affects the efficiency and stability of the power system. Traditional two-level rectifiers use silicon (English: Silicon, abbreviated as: Si) material power switching devices. Although the technology is relatively mature, there are still many shortcomings in practical applications. First, the Si material power switching device has a low withstand voltage, which cannot make the rectifier work at a higher voltage level, limiting the application scenarios of the rectifier. Secondly, the switching loss of the Si material power switching device is large, which reduces the efficiency of the rectifier; and the switching speed of the Si material power switching device is slow, and the weight and volume of the passive filter cannot be further reduced by increasing the switching frequency. Thirdly, the two-level rectifier topology has a small number of output levels, which makes the harmonic current on the AC side of the rectifier large.

[0003] To solve these problems, researchers began to explore the use of silicon carbide (SiC) power switching devices to replace traditional Si power switching devices. SiC power switching devices have the advantages of high voltage resistance, low switching loss and high switching speed. These characteristics enable the rectifier to operate at a higher voltage level, thereby expanding the application field of the rectifier. At the same time, the low loss characteristics of SiC power switching devices help to improve the efficiency of the rectifier, while the high switching speed enables the rectifier to reduce the volume and weight of the passive filter by increasing the switching frequency, thereby increasing the power density of the rectifier. However, there are certain risks in directly using SiC power switching devices, especially in traditional rectifier topologies, where complementary SiC power switching devices in the same bridge arm may affect each other, resulting in an increased risk of bridge arm direct short circuit. Therefore, it is necessary to improve the traditional rectifier topology to improve the operating reliability of the rectifier.

[0004] Silicon carbide metal oxide semiconductor field effect transistor (hereinafter referred to as: SiC MOSFET) is a SiC material power switching device with the advantages of high voltage resistance, low switching loss and high switching speed. Applying SiC MOSFET to three-level six-switch split topology rectifier can improve its switching frequency and efficiency. However, the three-level six-switch split topology rectifier of SiC device has the following problems. If the three-level six-switch split topology rectifier of SiC device adopts the traditional control strategy, in the traditional control strategy, it is usually required that the grid voltage and output current maintain the same frequency and phase to achieve the goal of power factor 1, thereby maximizing the transmission of active power. However, in practical applications, due to the presence of filters, there is often a certain phase offset between the output voltage and current of the converter, which causes serious distortion of the three-phase current when it passes through the zero point. This current distortion not only reduces the sinusoidality of the AC current, but also generates a large number 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, affecting the normal operation of power grid electrical equipment. Therefore, it is crucial to improve the current quality 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 difficulty. Summary of the invention

[0005] In view of the above-mentioned problems such as zero-crossing current distortion in the prior art, the present invention provides a control method and system for a three-level six-switch split topology rectifier of a SiC device, which accurately obtains the phase difference between the grid voltage and the square wave voltage through phase locking, and then generates a q-axis given current, so that the zero-crossing distortion of the AC current is effectively reduced and the sinusoidality of the AC current waveform is significantly improved, thereby improving the quality of the AC current.

[0006] In a first aspect, the present invention provides a control method for a three-level six-switch split-topology rectifier of a SiC device, the specific steps of which are as follows: 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 generating step is as follows: generating a d-axis command current according to a given DC bus voltage reference value and an actual DC bus voltage, and generating a q-axis command current according to the d-axis command current, a grid voltage phase angle, and a square wave voltage phase angle; 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.

[0007] In combination with the first aspect, in some embodiments, in the stationary coordinate transformation and phase locking step, a method for transforming the three-phase grid voltage into the grid voltage in a two-phase stationary coordinate system is: A phase grid voltage E A Minus 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 VBN 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 oh 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 oh 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 signalv β1 ' Add quadrature signals q_v α1 ' Then multiply the third setting coefficient to get the signal v βq1 ; Signal v αq1 Multiplication - sin( i 1) The product signal v βq1 Multiply cos( i 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 i 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 oh 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 oh 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( i 2) The product signal v βq2 Multiply cos( i 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 i 2.

[0008] In combination with the first aspect, in some embodiments, in the rotating coordinate transformation step, a method for 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: A phase grid voltage E A Minus 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( i 1) Product of grid voltage E β Multiply sin( i 1) to obtain the d-axis grid voltage in the two-phase rotating coordinate system E d , grid voltage Eα Multiplication - sin( i 1) Product of grid voltage E β Multiply cos( i 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 grid voltage phase angle is: A phase grid current I A Multiply 0.667 times sin( i 1) Add the B phase grid current I b Multiply sin( i 1-2π / 3) plus the C-phase grid current I c Multiply sin( i 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( i 1) The product of the B-phase grid current I b Multiply cos( i 1-2π / 3) plus the C-phase grid current I c Multiply by cos( i 1+2π / 3) to obtain the q-axis grid current in the two-phase rotating coordinate system i q .

[0009] In combination with the first aspect, in some embodiments, in the command current generating step, a method for generating a d-axis command current according to a given DC bus voltage reference value and an 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 * ; 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: Square wave voltage phase angle i 2 minus grid voltage phase angle i 1Get the difference Δ i , the difference Δ i After the tangent function tan, we get tanΔ i , tanΔ i Multiply d-axis command current i d * Get the q-axis command current i q * .

[0010] In combination with the first aspect, in some embodiments, in the modulation signal generating step, a method for generating a modulation wave command voltage in a 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 Signalu d1 * Multiply sin( i 1) The product modulated signal u q1 * Multiply cos ( i 1) to obtain the A phase voltage modulation signal u A * ; Modulation signal u d1 * Multiply sin( i 1-2π / 3) product-add modulation signal u q1 * Multiply cos( i 1-2π / 3) to obtain the B phase voltage modulation signal u B * , the modulation signal u d1 * Multiply sin( i 1+2π / 3) product-add modulation signal u q1 * Multiply cos( i 1+2π / 3) to obtain the C phase voltage modulation signal u C * .

[0011] In combination with the first aspect, in some embodiments, in the large sector number generating 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 * Reduce the B-phase voltage modulation signal by 0.5 times 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 for 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.

[0012] In combination with the first aspect, in some embodiments, in the modulation signal translation step, a 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: 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 its 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 its 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 ' .

[0013] In combination with the first aspect, in some embodiments, in the modulation wave generating step, a method for generating a 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 ' ; Modulate the voltage signal by 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 .

[0014] In combination with the first aspect, in some embodiments, in the drive signal generating step, a method for generating different three-phase initial drive signals according to the comparison result of the three-phase modulation wave and the set carrier 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.

[0015] In a second aspect of the present invention, a three-level six-switch split-topology rectifier control system for a SiC device is provided, which is used to implement the three-level six-switch split-topology rectifier control method for a SiC device according to the first aspect of the present invention, comprising: 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.

[0016] Compared with the prior art, the advantages and positive effects of the present invention are: The SiC device three-level six-switch split topology rectifier control method and system 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 a q-axis specified current, so that the zero-crossing distortion of the AC current is effectively reduced, and the sinusoidality of the AC current waveform is improved, thereby effectively improving the current quality. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 A circuit diagram of a three-level six-switch split-topology rectifier of a SiC device according to an embodiment of the present invention; Figure 2 This is a flow chart of a control method for a three-level six-switch split-topology rectifier of a SiC device according to an embodiment of the present invention; Figure 3 It is a principle diagram of static coordinate transformation of three-phase grid voltage according to an embodiment of the present invention; Figure 4 It is a principle diagram of the static coordinate transformation of the three-phase square wave voltage according to an embodiment of the present invention; Figure 5 This is a schematic diagram of the voltage phase-locking process of a two-phase power grid according to an embodiment of the present invention; Figure 6 This is a schematic diagram of the two-phase square wave voltage phase-locking process according to an embodiment of the present invention; Figure 7 It is a principle diagram of the three-phase grid voltage rotation coordinate transformation according to an embodiment of the present invention; Figure 8 It is a principle diagram of the rotation coordinate transformation of the three-phase grid current according to the embodiment of the present invention; Figure 9 This is a schematic diagram of the generation of the d-axis command current according to an embodiment of the present invention; Figure 10 This is a schematic diagram of the generation of the q-axis command current according to an embodiment of the present invention; Figure 11 A schematic diagram of the modulation wave instruction voltage generation according to an embodiment of the present invention; Figure 12 The schematic diagram of the rotation coordinate transformation of the modulation signal according to the embodiment of the present invention; Figure 13 A schematic diagram of the large sector number generation according to an embodiment of the present invention; Figure 14 A schematic diagram of the modulation signal shifting according to an embodiment of the present invention; Figure 15 A schematic diagram of the modulation wave generation according to an embodiment of the present invention; Figure 16 A schematic diagram of the driving signal generation according to an embodiment of the present invention; Figure 17 This is a structural block diagram of a three-level six-switch split-topology rectifier control system for SiC devices according to an embodiment of the present invention; Figure 18 It is a schematic diagram of the three-phase output current waveform using the traditional control method; Figure 19The figure is a schematic diagram of a three-phase output current waveform of a control method and system for a three-level six-switch split-topology rectifier of a SiC device according to an embodiment of the present invention.

[0018] In the figure, 1. grid voltage static coordinate transformation module, 2. square wave voltage static coordinate transformation module, 3. first phase locking module, 4. second phase locking module, 5. grid voltage rotation coordinate transformation module, 6. grid current rotation 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 rotation 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 DESCRIPTION

[0019] The present invention will be described in detail below by way of exemplary embodiments in conjunction with the accompanying drawings. However, it should be understood that, without further description, elements, structures and features in one embodiment may also be beneficially combined in other embodiments.

[0020] Figure 1 The main topology circuit of the SiC device three-level six-switch split topology rectifier is shown, where: u dc is the DC side voltage, C 1. C 2 is the DC bus capacitor, Q A1 , Q A2 SiC MOSFET power switch device for phase A, D A1 , D A2 , D A3 , D A4 is the diode of phase A, L A1 , L A2 Isolation inductance of phase A; Q B1 , Q B2 SiC MOSFET power switch device for phase B, D B1 、D B2 、D B3 、 D B4 is the diode of phase B, L B1、L B2 Isolation inductance of phase B; Q C1 、Q C2 SiC MOSFET power switch device for phase C, D C1 、 D C2 、D C3 、D C4 The diode of phase C, L C1 、L C2 Isolation inductor for 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, I A , I B , I C is the three-phase grid current.

[0021] Continue to see Figure 1 Since the ABC three-phase bridge arms are completely symmetrical, phase A is used as an example to explain the connection method of the main circuit. C 1 and DC bus capacitor C 2 connected to point O; power switch device Q A1 One end and the diode D A3 pass X A4 point connection, and the other end to the diode D A1 pass X A2 Point connection, diode D A1 The other end is connected to the DC bus capacitor C 2 connected through point N; at the same time, the power switch device Q A1 The other end of the isolation inductor L A1 pass X A2 Point connection, isolation inductorL A1 The other end of the filter inductor L A pass X A1 Point connection, filter inductor L A The other end is connected to the grid voltage E A Direct connection; power switching devices Q A2 One end and the DC bus capacitor C 1 is connected to point O and the other end is connected to the diode D A2 pass X A5 Point connection, diode D A2 The other end of the diode D A4 pass X A3 Point connection, diode D A4 The other end is connected to the DC bus capacitor C 1 connected through point P; at the same time, the isolation inductor L A2 The other end of the filter inductor L A pass X A1 Point connection, filter inductor L A The other end is connected to the grid voltage E A Direct connection. The connection method of the B-phase and C-phase main circuits is the same as that of the A-phase, and will not be repeated here.

[0022] The above three-level six-switch split topology rectifier adopts SiC power switching devices and adds isolation inductors in each phase bridge arm, which can reduce the mutual influence of complementary SiC power switching devices in the same bridge arm and has high operating reliability.

[0023] For the above-mentioned SiC device three-level six-switch split topology rectifier, the present invention provides a SiC device three-level six-switch split topology rectifier control method and system, according to the three-phase grid voltage, square wave voltage conversion and phase-locked grid voltage phase angle and square wave voltage phase angle obtained and the d-axis command current generated according to the given and actual DC bus voltage to generate the q-axis command current; according to the command current, grid voltage phase angle, grid voltage and grid current in the two-phase rotating coordinate system, generate a three-phase voltage modulation signal, and transform it into a voltage modulation signal in the two-phase stationary coordinate system, and generate a large sector number according to the transformed voltage modulation signal; according to the voltage modulation signal in the two-phase stationary coordinate system processed by translation, generate a three-phase modulation wave, and generate a drive signal according to the comparison result of the three-phase modulation wave and the set carrier and the comparison result of the non-AND logic and the large sector number. It can effectively reduce the zero-crossing distortion of the AC current, and the current waveform has high sinusoidality and high current quality.

[0024] The control method and system of the three-level six-switch split-topology rectifier of the SiC device of the present invention are described in detail below in conjunction with the accompanying drawings and embodiments.

[0025] See also Figure 2 The first aspect of the present invention provides a method for controlling a three-level six-switch split-topology rectifier of a SiC device, and the specific steps are as follows: S1. Stationary coordinate transformation and phase-locking steps: 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.

[0026] The two-phase stationary coordinate transformation can simplify subsequent signal processing, remove the influence of three-phase imbalance, and improve the stability and anti-interference ability of the rectifier. By performing phase-locking processing on the grid voltage and square wave voltage in the two-phase stationary coordinate system, the grid voltage phase angle and square wave voltage phase angle can be accurately extracted to ensure the accuracy of grid synchronization control.

[0027] Specifically, in some embodiments, see Figure 3 , the method of transforming the three-phase grid voltage into the grid voltage in the two-phase stationary coordinate system is: A phase grid voltage E A Minus 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 EB Subtract 0.866 times the C-phase grid voltage E C Then, multiply the first setting coefficient to get the grid voltage E β .

[0028] Specifically, in some embodiments, see Figure 4 , the method of transforming the three-phase square wave voltage into the square wave voltage in the two-phase 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 .

[0029] Specifically, in some embodiments, see Figure 5 , the method of performing phase-locking processing on the grid voltage in the two-phase stationary coordinate system to obtain the grid voltage phase angle is: Grid voltage E α With feedback grid voltage E α Direct signal v α1 ' The difference 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 oh 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 Eβ The orthogonal signal q_v β1 ' Multiply the grid voltage angular frequency by oh 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( i 1) The product signal v βq1 Multiply cos( i 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 i 1. Specifically, in some embodiments, the PI regulation adopts a transfer function of K PI = 0.571+50.766 / s The PI regulator, where s is a complex variable in the frequency domain.

[0030] Specifically, in some embodiments, see Figure 6 , the method of phase-locking the square wave voltage in the two-phase stationary coordinate system to obtain the square wave voltage phase angle 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 oh 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 oh 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 0.5 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( i 2) The product signal v βq2 Multiply cos( i 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 i 2. Specifically, in some embodiments, the PI regulation adopts a transfer function of K PI = 0.571+50.766 / s The PI regulator, where s is a complex variable in the frequency domain.

[0031] Specifically, in some embodiments, the first setting coefficient is set to but not limited to 0.816, the second setting coefficient is set to but not limited to 1.414, and the third setting coefficient is set to but not limited to 0.5. It should be noted that the first setting coefficient, the second setting coefficient, and the third setting coefficient can be set according to actual needs.

[0032] 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 energy transmission efficiency, reduce harmonic impact, and improve power quality.

[0033] Specifically, in some embodiments, see Figure 7 , 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: A phase grid voltage E A Minus 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( i 1) Product of grid voltage E β Multiply sin( i 1) to obtain the d-axis grid voltage in the two-phase rotating coordinate system E d , grid voltage E α Multiplication - sin( i 1) Product of grid voltage E β Multiply cos( i 1) to obtain the q-axis grid voltage in the two-phase rotating coordinate system E q .

[0034] Specifically, in some embodiments, see Figure 8, the method of transforming the three-phase grid current into the grid current in the two-phase rotating coordinate system according to the grid voltage phase angle is: A phase grid current I A Multiply 0.667 times sin( i 1) Add B phase grid current I b Multiply sin( i 1-2π / 3) plus the C-phase grid current I c Multiply sin( i 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( i 1) The product of the B-phase grid current I b Multiply cos( i 1-2π / 3) plus the C-phase grid current I c Multiply by cos( i 1+2π / 3) to obtain the q-axis grid current in the two-phase rotating coordinate system i q .

[0035] S3, command current generation step: Generate d-axis command current according to given DC bus voltage reference value and actual DC bus voltage, and generate q-axis command current according to d-axis command current, grid voltage phase angle and square wave voltage phase angle. Calculate q-axis command current by d-axis command current, grid voltage phase angle and square wave voltage phase angle, and precise control of reactive power can be achieved. Since dq-axis decoupling control converts AC signal into DC signal, steady-state error of traditional PI control under AC signal can be avoided, control accuracy can be improved, grid harmonic content can be reduced, and power quality of rectifier can be improved.

[0036] Specifically, in some embodiments, continue to see Figure 9 , the method of 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 *The PI regulation adopts a transfer function of 0.4+10 / s PI regulator.

[0037] Specifically, in some embodiments, continue to see Figure 10 , the method of 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: Square wave voltage phase angle i 2 minus grid voltage phase angle i 1Get the difference Δ i , the difference Δ i After the tangent function tan, we get tanΔ i , tanΔ i Multiply d-axis command current i d * Get the q-axis command current i q * .

[0038] S4, modulation signal generation step: generate 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, and transform the modulation wave command voltage in the two-phase rotating coordinate system into a three-phase voltage modulation signal.

[0039] The modulation wave command voltage is calculated based on the grid voltage phase angle, grid dq axis voltage, current, and command current, and converted into a three-phase modulation signal, which can reduce the total harmonic distortion rate THD and improve the current tracking capability.

[0040] Specifically, in some embodiments, see Figure 11 , 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 Eq Subtract the second result to obtain the q-axis modulation wave command voltage in the two-phase rotating coordinate system u q * .

[0041] Specifically, in some embodiments, see Figure 12 , 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( i 1) The product modulated signal u q1 * Multiply cos( i 1) to obtain the A phase voltage modulation signal u A * ; Modulation signal u d1 * Multiply sin( i 1-2π / 3) product-add modulation signal u q1 * Multiply cos( i 1-2π / 3) to obtain the B phase voltage modulation signal u B * , the modulation signal u d1 * Multiply sin( i 1+2π / 3) product-add modulation signal u q1 * Multiply cos( i 1+2π / 3) to obtain the C phase voltage modulation signal u C * .

[0042] S5, large sector number generating step: 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.

[0043] Specifically, in some embodiments, see Figure 13 , the method of transforming the three-phase voltage modulation signal into the voltage modulation signal in the two-phase stationary coordinate system is: Phase A voltage modulation signal u A * Reduce the B-phase voltage modulation signal by 0.5 times 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 * .

[0044] Specifically, in some embodiments, continue to see Figure 13 , the method of generating the command signal according to the voltage modulation signal in the 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.

[0045] Specifically, in some embodiments, continue to see Figure 13 , the method to generate the 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.

[0046] S6, modulation signal translation step: different modulation signals are generated according to the voltage modulation signal in the two-phase stationary coordinate system and different set translation values, the modulation signal corresponding to the large sector number is selected from the different modulation signals, and the voltage modulation signal in the two-phase stationary coordinate system after translation is obtained according to the selected modulation signal. Different modulation signals are generated by setting the translation value, which improves the flexibility of modulation. By analyzing the large sector numbers corresponding to multiple modulation signals, the most suitable modulation signal is selected to ensure that the rectifier output voltage vector is located in the optimal sector, reduce modulation errors, improve control accuracy, reduce total harmonic distortion THD, improve current tracking capability, and thus improve power quality, making the rectifier current output smoother.

[0047] Specifically, in some embodiments, see Figure 14 , 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 its 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 its corresponding large sector number N is 6; Specifically, in some embodiments, continue to see Figure 14 , 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 ' .

[0048] S7, 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. Obtaining the midpoint potential balance control signal according to the upper and lower capacitor voltages of the rectifier can improve the balance of the DC bus voltage. Correcting the initial modulation wave through midpoint potential compensation, optimizing the three-phase modulation wave, and using the compensated three-phase modulation wave for drive control can reduce high-order harmonic components, reduce the total harmonic distortion THD, and improve the output current quality.

[0049] Specifically, in some embodiments, see Figure 15 , the method of generating the three-phase initial modulation wave according to the voltage modulation signal in the two-phase stationary coordinate system after translation 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 ' ; Modulate the voltage signal by 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 Cv tC ; Specifically, in some embodiments, see Figure 15 , 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 .

[0050] S8, drive signal generation step: different three-phase initial drive signals are generated according to the comparison result between the three-phase modulation wave and the set carrier and the comparison result and the NAND logic, and the three-phase initial drive pulse signal corresponding to the large sector number is selected from the different three-phase initial drive signals as the three-phase drive signal. The different comparison results are processed by NAND logic operation to optimize the initial drive signal, avoid repeated switching, burr signal and dead time interference, and improve the switching stability. By comparing the three-phase modulation wave with the carrier, optimizing the logic, and selecting the drive signal corresponding to the optimal large sector number, the optimal three-phase drive signal is finally generated, which effectively reduces the total harmonic distortion rate THD and improves the output current quality.

[0051] Specifically, in some embodiments, see Figure 16 , 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 and the logical AND 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.

[0052] exist Figure 13 The large sector number shown is generated, Figure 14 Modulation signal shift and Figure 16 In the process of generating the driving signal shown in the figure, the signal is judged and selected by selecting the switch Switch. The switch is divided into an input side and an output side. The input side has 7 signal input terminals, the top 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. According to the control signal, select which selection signal input terminal to input the signal. For example, if the control signal is 6, select the 6th selection signal input terminal to input the signal, and output it from the signal output terminal.

[0053] See also Figure 17 The second aspect of the present invention provides a SiC device three-level six-switch split topology rectifier control system, 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: A setting module (not shown in the figure) for setting different coefficients; A grid voltage static coordinate transformation module 1 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 2 transforms the three-phase square wave voltage into a square wave voltage in a two-phase static coordinate system; The first phase locking module 3 performs phase locking processing on the grid voltage in the two-phase stationary coordinate system to obtain the grid voltage phase angle; The second phase-locking module 4 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 5 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 6 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 7 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 8 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; The modulation wave command voltage generating module 9 generates the modulation 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; The modulation signal rotation coordinate conversion module 10 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 11 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; The modulation signal translation module 12 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 13 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 14 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 logical negation 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.

[0054] The above-mentioned SiC device three-level six-switch split topology rectifier control system 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 q-axis specified current, so that the zero-crossing distortion of the AC current is effectively reduced, and the sinusoidality of the AC current waveform is improved, thereby effectively improving the current quality.

[0055] In order to verify the effectiveness of the above-mentioned SiC device three-level six-switch split topology rectifier control method and system of the present invention, a simulation model is built using SIMULINK for verification. The effective value of the grid line voltage is 380V, the isosceles triangle wave frequency of the reference signal U0 is 10kHz, the frequency of the modulation wave SINA is 50Hz, and the DC bus capacitance isC 1 and DC bus capacitor C 2 is 2200μF, switching frequency f s For 20kHz, the filter inductor L a 、Filter inductor L b and filter inductor L c In the simulation model, the conventional control method and the control method and system for the three-level six-switch split topology rectifier of SiC device proposed in the present invention are respectively used for the three-level six-switch split topology rectifier of SiC device. Figure 18 The three-phase output current waveform using the traditional control method is given. Through Fourier analysis, it can be seen that the total harmonic distortion THD of the three-phase currents A, B, and C are 2.21%, 2.22%, and 2.26% respectively. Figure 19 The three-phase output current waveform of the SiC device three-level six-switch split topology rectifier control method and system proposed in the present invention is given. Through Fourier analysis, it can be seen that the total harmonic distortion THD of the three-phase currents A, B, and C is 1.05%, 1.07%, and 1.08%, and the sinusoidality of the three-phase output current waveform is significantly improved, which effectively improves the output current waveform with zero-crossing distortion, verifying the effectiveness of the method and system proposed in the present invention.

[0056] The above embodiments are used to explain the present invention rather than to limit the present invention. Any modification and change made to the present invention within the spirit of the present invention and the protection scope of the claims shall 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 generating step is as follows: generating a d-axis command current according to a given DC bus voltage reference value and an actual DC bus voltage, and generating a q-axis command current according to the d-axis command current, a grid voltage phase angle, and a square wave voltage phase angle; 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 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 * ; 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: 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 d-axis command current i d * Get the q-axis command current i q * .

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 * Reduce the B-phase voltage modulation signal by 0.5 times 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