3TSMC control method for increasing maximum voltage transmission ratio

Abstract

The invention discloses a 3TSMC control method for increasing the maximum voltage transmission ratio, and relates to the field of third harmonic injection two-stage matrix converters. The method comprises the steps that respective overmodulation strategies of three overmodulation areas are designed in advance, in the overmodulation area I, the voltage transmission ratio is increased by increasing the voltage of a virtual bus to increase the voltage of a reference bus, and in the overmodulation area II, the voltage transmission ratio is increased; in the overmodulation area II, the amplitude of the output voltage of the inverter stage is changed by utilizing the minimum phase error overmodulation of the inverter stage to improve the modulation ratio of the inverter stage so as to improve the voltage transmission ratio; and in the overmodulation area III, the inversion stage basic vector is utilized to maintain overmodulation, and the amplitude and phase angle of the inversion stage output voltage are changed to improve the modulation ratio of the inversion stage so as to improve the voltage transmission ratio. Different overmodulation strategies are selected according to the required modulation ratio to obtain a duty ratio required by space vector modulation, and then an inverter-stage switching tube driving signal is obtained, so that the effect of improving the voltage transmission ratio can be achieved.

Description

Technical Field

[0001] The present application relates to the field of three - harmonic injection bipolar matrix converters, and in particular to a 3TSMC control method for improving the maximum voltage transfer ratio. Background Art

[0002] The three - harmonic injection bipolar matrix converter (3TSMC) is a new type of matrix converter (MC) based on a hybrid three - harmonic injection rectifier. It inherits most of the advantages of the traditional matrix converter and also has advantages such as stronger reactive power control ability, decoupling of the rectifier stage and the inverter stage, and the maximum linear voltage transfer ratio is not affected by the input - side power factor. Therefore, it is more suitable for occasions such as AC motor speed control systems, wind power generation sets, flexible AC transmission, and aviation starting power generation systems.

[0003] However, as a buck - type power converter, the maximum linear voltage transfer ratio of 3TSMC is limited to 0.866. The low voltage transfer ratio limits the application range of 3TSMC: in the AC speed control system, it limits the speed regulation range of the motor, and the devices need to withstand a higher voltage, which may cause device damage or shortened life. Summary of the Invention

[0004] In view of the above problems and technical requirements, the present application proposes a 3TSMC control method for improving the maximum voltage transfer ratio. The technical solution of the present application is as follows:

[0005] A 3TSMC control method for improving the maximum voltage transfer ratio, the 3TSMC control method includes:

[0006] Collect the three - phase input voltages of the three - harmonic injection bipolar matrix converter and calculate the amplitude U of the three - phase input voltages im , determine the amplitude U of the three - phase reference output voltage and the phase angle θ om according to the given three - phase reference output voltage r , and calculate the modulation ratio and the vector position angle of the output voltage vector in the sector where it is located where, / / is the modulo operator;

[0007] When the modulation ratio m < 0.866, determine the duty cycle required for space vector modulation according to the three - phase input voltages and the vector position angle θ;

[0008] When 0.866 ≤ m < m1, it is determined that it is in the over - modulation region I, determine the reference bus voltage as and calculate the virtual bus voltage u dcvir , and determine the duty cycle required for space vector modulation according to the virtual bus voltage u dcvir in combination with the vector position angle θ;

[0009] When the modulation ratio m1 ≤ m < m2, it is determined that the overmodulation region II is entered. According to the relationship between the voltage vector trajectory and the output voltage waveform during overmodulation with the minimum phase error of the inverter stage, the duty cycle required for space vector modulation is determined by combining the modulation ratio m and the vector position angle θ;

[0010] When the modulation ratio m ≥ m2, it is determined that the overmodulation region III is entered. According to the relationship between the voltage vector trajectory and the output voltage waveform during overmodulation with the basic vector of the inverter stage remaining unchanged, the duty cycle required for space vector modulation is determined by combining the modulation ratio m and the vector position angle θ;

[0011] According to the phase angle θ of the three-phase input voltage i The driving signals of the rectifier stage switching tubes and the bidirectional switch are determined to drive the rectifier stage switching tubes and the bidirectional switch in the 3TSMC. Pulse width modulation is performed according to the duty cycle required for space vector modulation, and the driving signals of the inverter stage switching tubes are obtained to drive the switching tubes in the three-phase bridge arm of the inverter stage of the 3TSMC;

[0012] Among them, in the overmodulation region I, by increasing the virtual bus voltage u dcvir to increase the reference bus voltage u dcref to increase the voltage transfer ratio. In the overmodulation region II, on the basis of keeping the maximum value of the reference bus voltage u dcref the voltage transfer ratio is increased by changing the amplitude of the output voltage of the inverter stage to increase the modulation ratio of the inverter stage. In the overmodulation region III, on the basis of keeping the maximum value of the reference bus voltage u dcref the voltage transfer ratio is increased by changing the amplitude and phase angle of the output voltage of the inverter stage to increase the modulation ratio of the inverter stage.

[0013] The beneficial technical effects of this application are:

[0014] This application discloses a 3TSMC control method for improving the maximum voltage transfer ratio. This method does not need to change the topology of the three-harmonic injection bipolar matrix converter. By using different overmodulation strategies corresponding to the designed three overmodulation regions, the duty cycle required for space vector modulation can be obtained by selecting different overmodulation strategies according to the required modulation ratio, and then pulse width modulation is performed to obtain the driving signals of the inverter stage switching tubes to drive the switching tubes in the three-phase bridge arm of the inverter stage of the 3TSMC, thereby achieving the effect of improving the voltage transfer ratio.

[0015] In the overmodulation region I designed in this application, by increasing the virtual bus voltage u dcvir to increase the reference bus voltage u dcref to increase the voltage transfer ratio. In the overmodulation region II, on the basis of the reference bus voltage u dcrefOn the basis of maintaining the maximum value, the voltage transfer ratio is improved by changing the amplitude of the inverter output voltage to increase the inverter modulation ratio. In the overmodulation area III, the reference bus voltage u dcref On the basis of maintaining the maximum value, the voltage transfer ratio is improved by changing the amplitude and phase angle of the inverter output voltage to improve the inverter modulation ratio. On the basis of improving the voltage transfer ratio, the voltage and current quality of 3TSMC during overmodulation can be effectively improved. And the use of the pre-constructed first lookup table curve, the second lookup table curve and the third lookup table curve can simplify the calculation process, improve the control efficiency and reduce the calculation load. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 This is the topological structure diagram of the 3TSMC targeted by the method of this application.

[0017] Figure 2 It is a relationship diagram of various voltage variables in the overmodulation region I.

[0018] Figure 3 It is a schematic diagram of the first look-up table curve.

[0019] Figure 4 It is a schematic diagram of the voltage vector trajectory and the output voltage waveform when the inverter stage minimum phase error overmodulation is performed in the overmodulation zone II.

[0020] Figure 5 It is a schematic diagram of the second look-up table curve.

[0021] Figure 6 It is a schematic diagram of the voltage vector trajectory and the output voltage waveform when the inverter stage basic vector is maintained overmodulated in the overmodulation zone III.

[0022] Figure 7 Schematic diagram of the third look-up table curve.

[0023] Figure 8 It is a flow chart of a 3TSMC control method according to an embodiment of the present application. DETAILED DESCRIPTION

[0024] The specific implementation of the present application is further described below in conjunction with the accompanying drawings.

[0025] The present application discloses a 3TSMC control method for improving the maximum voltage transfer ratio. The method is aimed at a topology structure of a third harmonic injection double-stage matrix converter (3TSMC) such as Figure 1 As shown in FIG, the third harmonic injection two-stage matrix converter mainly includes a three-phase AC power supply, a three-phase bridge arm of the rectifier stage, three bidirectional switches, a harmonic injection control bridge arm and a three-phase bridge arm of the inverter stage. Figure 1 As shown, the three-phase AC power supply provides a three-phase input voltage u ia 、u iband u ic The three-phase bridge arm of the rectifier stage includes the switch tube S ap , S bp , S cp , S an , S bn , S cn , three bidirectional switches include switch tube S ay , S by , S cy , S ya , S yb , S yc , and the harmonic injection control bridge arm includes S yp , S yn , L y The inverter-level three-phase bridge arm includes S up , S vp , S wp , S un , S vn , S wn , this application will not go into detail about the specific structure of 3TSMC.

[0026] The 3TSMC control method of this application does not need to change the original topology of 3TSMC. It introduces a space vector overmodulation strategy to improve the maximum voltage transfer ratio. The main methods include:

[0027] Step 1: Collect the three-phase input voltage u of the double-stage matrix converter injected with the third harmonic ia 、u ib and u ic , and determine the given three-phase reference output voltage u oa 、u ob and u oc .

[0028] The three-phase input voltage u ia 、u ib and u ic Then the amplitude of the three-phase input voltage U can be calculated. im . For the three-phase input voltage u ia 、u ib and u ic The αβ components of the three-phase input voltage are obtained by performing abc / αβ coordinate transformation, and the phase angle θ of the three-phase input voltage can be calculated through a dual generalized second-order integrator phase-locked loop. i .

[0029] In addition, the three-phase input voltage u ia 、u ib and u ic The DC bus voltage u can also be calculated dc for:

[0030]

[0031] Among them, / / is the remainder operator.

[0032] Similarly, when obtaining the three-phase reference output voltage u oa 、u ob and u oc Then the amplitude of the three-phase reference output voltage U can be calculated om . For the three-phase reference output voltage u oa 、u ob and u oc The αβ components of the three-phase reference output voltage are obtained by performing abc / αβ coordinate transformation, and the phase angle θ of the three-phase reference output voltage can be calculated through a dual generalized second-order integrator phase-locked loop. r , and then according to the phase angle θ of the three-phase reference output voltage r The sector where the output voltage vector is located and the angle that the output voltage vector rotates in the sector can be determined. This angle is called the vector position angle θ.

[0033] Then the required modulation ratio m can be calculated according to the following formula:

[0034]

[0035] After the modulation ratio m is obtained, two different methods are used to control the switch tubes in the three-phase bridge arm of the rectifier stage, the three bidirectional switches and the three-phase bridge arm of the inverter stage in the 3TSMC:

[0036] For the three-phase bridge arm and bidirectional switch of the rectifier stage, according to the phase angle θ of the three-phase input voltage i Determine the rectifier stage switch tube drive signal and the bidirectional switch drive signal to drive the rectifier stage switch tube and the bidirectional switch in the 3TSMC. This part is the same as the conventional method. Including according to the phase angle θ i The control strategy corresponding to the sector is used for control, and the switch signal table is as follows:

[0037]

[0038] For the inverter-level three-phase bridge arm, the space vector overmodulation strategy is used to obtain the inverter-level switch tube drive signal according to the required modulation ratio m to drive the inverter-level switch tube in the 3TSMC. Directly using SVPWM can make the maximum modulation ratio reach 0.866. Therefore, in order to improve the maximum voltage transfer ratio, it is necessary to design an overmodulation strategy so that the modulation ratio m>0.866 can be achieved to achieve the effect of improving the maximum voltage transfer ratio. This is the design focus of this application. Next, the design ideas of the overmodulation area corresponding to the modulation ratio m>0.866 are introduced as follows:

[0039] This application designs three overmodulation regions, corresponding to different modulation ratio intervals, which are introduced as follows:

[0040] I. Overmodulation region I, corresponding to the interval where the modulation ratio 0.866 ≤ m < m1.

[0041] In this overmodulation region I, by increasing the virtual bus voltage u dcvir to increase the reference bus voltage u dcref so as to increase the voltage transmission ratio until the virtual bus voltage u dcvir reaches the maximum value and the reference bus voltage u dcref also reaches the maximum value, and then it is impossible to further increase the voltage transmission ratio by increasing the virtual bus voltage u dcvir . As a result, the modulation ratio is increased from 0.866 to m1 until the virtual bus voltage u dcvir cannot be increased any further. Through actual calculation, it is determined that m1 = 0.955.

[0042] Introduce the reference angle of overmodulation region I Use the reference angle α1 to calculate the upper limit u dcul of the virtual bus voltage as:

[0043]

[0044] Use the DC bus voltage u dc and the upper limit u dcul of the virtual bus voltage to synthesize the virtual bus voltage u dcvir as:

[0045]

[0046] Please refer to Figure 2 which shows the relationship diagram of the DC bus voltage u dc , the upper limit u dcul of the virtual bus voltage and the virtual bus voltage u dcvir .

[0047] After that, find the average value of the virtual bus voltage u dcvir which is the reference bus voltage u dcref :

[0048]

[0049] Figure 2 In (b) of , the solid line is the waveform of the synthesized virtual bus voltage u dcvir , while the dashed line is the reference bus voltage u dcref obtained by calculating the average value. It can be seen from Figure 2 that the value of the reference angle α1 directly affects the upper limit udcul value, thus affecting the synthesized virtual bus voltage u dcvir , and ultimately affecting the reference bus voltage u dcref , so it can be considered that the reference bus voltage u dcref is affected by the reference angle α1. Substituting the above formulas (2) to (4) into (5), the relationship between the reference bus voltage u dcref and the reference angle α1 can be obtained as follows:

[0050]

[0051] According to the relationship of formula (6), the corresponding reference bus voltage u can be obtained by adjusting the reference angle α1 dcref , thereby achieving the required modulation ratio. In order to simplify the operation and improve the control efficiency, a first look-up curve can be pre-constructed based on formula (5), including: taking the reference bus voltage u dcref as the independent variable and the reference angle α1 as the dependent variable, constructing a first look-up curve representing the relationship formula (6) between the reference bus voltage u dcref and the reference angle α1. The constructed first look-up curve is as shown in Figure 3 .

[0052] II. Overmodulation region II, corresponding to the interval where the modulation ratio m1 ≤ m < m2.

[0053] As described above, when the virtual bus voltage u dcvir increases to a certain extent, further increasing the virtual bus voltage u dcvir will not be able to continue to increase the reference bus voltage u dcref . Please refer to Figure 2 It can be seen that when the upper limit of the virtual bus voltage u dcul reaches , further increasing the upper limit of the virtual bus voltage u dcul will not be able to continue to increase the virtual bus voltage u dcvir and the reference bus voltage u dcref . At this time, it enters the overmodulation region II.

[0054] In the overmodulation region II, keep the reference bus voltage u dcref as the maximum value reached in the above overmodulation region I, then keep the phase angle of the inverter output voltage unchanged, and increase the voltage transmission ratio by changing the amplitude of the inverter output voltage, so that the modulation ratio is increased from m1 to m2 until further changing the amplitude of the inverter output voltage can no longer increase the voltage transmission ratio. At this time, through actual calculation, m2 = 1.002.

[0055] When performing minimum phase error overmodulation of the inverter in the overmodulation region II, The output voltage waveform within the interval is a piecewise function composed of four segment functions, and the expression is:

[0056]

[0057] Among them, θ r is the phase angle of the three-phase reference output voltage, θ o is the phase angle of the actual output voltage, and α2 is the reference angle of the overmodulation zone II.

[0058] Please combine Figure 4 The voltage vector trajectory and the output voltage waveform when the inverter stage has the minimum phase error overmodulation are shown in the figure. Due to the symmetry, the rest can be determined in the same way.

[0059] Since the phase angle of the inverter output voltage in the overmodulation region II remains unchanged, the actual output voltage phase angle θ in the overmodulation region II is o =θ r The characteristics of the inverter stage modulation ratio m can be calculated from this inv for:

[0060]

[0061] It can be seen from equation (8) that changing the reference angle α2 can change the inverter modulation ratio m inv , thereby achieving the required modulation ratio. In order to simplify the calculation and improve the control efficiency, a second lookup table curve can be constructed in advance based on formula (8), including: inv As the independent variable and the reference angle α2 as the dependent variable, the inverter modulation ratio m is constructed to represent inv The second lookup table curve of the relationship (8) with the reference angle α2 is constructed as follows: Figure 5 shown.

[0062] 3. Overmodulation zone III, corresponding to the interval of modulation ratio m≥m2.

[0063] As mentioned above, while maintaining the reference bus voltage u dcref When the modulation ratio is the maximum value and the amplitude of the inverter output voltage is changed, the modulation ratio can be increased to m2 at most, and then it cannot be increased further. In order to further increase the modulation ratio, in the overmodulation zone III, the reference bus voltage u dcrefThe voltage transfer ratio is improved by changing the amplitude and phase angle of the inverter output voltage while maintaining the maximum value. At this time, the virtual bus voltage reaches the maximum, and the inverter stage is modulated in six steps. The cost of this approach is that it causes more input and output waveform distortion compared to only changing the inverter output voltage amplitude. Due to the physical limitations of the topological structure, the maximum modulation ratio that can be achieved in the overmodulation zone III is 1.053, that is, in practical applications, the overmodulation zone III corresponds to the modulation ratio interval of 1.002≤m≤1.053.

[0064] When the inverter level basic vector is maintained overmodulated in overmodulation zone III, The output voltage waveform within the interval is:

[0065]

[0066] Wherein, α3 is the reference angle of the overmodulation zone III.

[0067] Please combine Figure 6 The diagram shown is a diagram of the voltage vector trajectory and the output voltage waveform when the inverter stage basic vector is maintained overmodulated. Due to the symmetry, the remaining parts can be determined in the same way.

[0068] Since the phase angle of the inverter output voltage in the overmodulation zone III will also change, the actual output voltage phase angle θ o No longer with the phase angle θ of the three-phase reference output voltage r are equal, but satisfy the following relationship:

[0069]

[0070] Combining equations (9) and (10), we can construct the inverter modulation ratio m: inv Relationship with reference angle α3:

[0071]

[0072] It can be seen from formula (11) that changing the reference angle α3 can change the inverter modulation ratio m inv , thereby achieving the required modulation ratio. In order to simplify the calculation and improve the control efficiency, a third lookup table curve can also be constructed in advance based on formula (11), including: inv As the independent variable and the reference angle α3 as the dependent variable, the inverter modulation ratio m is constructed to represent inv The third lookup table curve of the relationship equation (11) with the reference angle α3 is constructed as follows: Figure 7 shown.

[0073] Based on the design of the above three overmodulation regions, after calculating the required modulation ratio m according to formula (2), the process of obtaining the driving signals of the inverter stage switches is as follows. Please refer to Figure 8 :

[0074] (1) When the modulation ratio m < 0.866, according to the three-phase input voltages u ia , u ib and u ic and the vector position angle θ, determine the duty cycles d1 and d2 required for space vector modulation:

[0075]

[0076] This part is the same as the conventional method, and the required reference bus voltage u dcref and the required modulation ratio m inv of the inverter stage can be determined as:

[0077]

[0078] (2) When the modulation ratio 0.866 ≤ m < m1, it is determined that it is in overmodulation region I. The required reference bus voltage u dcref and the modulation ratio m inv of the inverter stage can be determined as:

[0079]

[0080] It can also be seen from the above formula that in overmodulation region I, the modulation ratio m inv of the inverter stage is fixed, and the modulation ratio m is mainly increased by changing the reference bus voltage u dcref .

[0081] Then, according to the required reference bus voltage u dcref , calculate the required virtual bus voltage u dcvir . One method is to calculate the required virtual bus voltage u dcvir according to formula (5). However, in order to simplify the calculation and improve the efficiency, based on the first look-up table curve shown in Figure 3 , in another embodiment, first query the first look-up table curve to directly determine the reference angle α1 corresponding to the calculated reference bus voltage u dcref , and then use the obtained reference angle α1 to calculate the upper limit u dcul of the virtual bus voltage according to formula (3), and combine formula (4) to obtain the virtual bus voltage u dcvir , thereby simplifying the operation.

[0082] After obtaining the required virtual bus voltage u dcvir , the virtual bus voltage u can be based ondcvir The duty ratios d1 and d2 required for space vector modulation are determined in combination with the vector position angle θ as follows:

[0083]

[0084] (3) When the modulation ratio m1 ≤ m < m2, it is determined that the overmodulation region II is in effect. Based on the relationship between the voltage vector trajectory and the output voltage waveform during overmodulation with the minimum phase error of the inverter stage, the duty ratios required for space vector modulation are determined in combination with the modulation ratio m and the vector position angle θ. According to the above analysis of the overmodulation region II, the required reference bus voltage u dcref and the modulation ratio m of the inverter stage inv are as follows:

[0085]

[0086] It can also be seen from the above formula that within the overmodulation region II, the reference bus voltage u dcref remains unchanged, and the modulation ratio m of the inverter stage is mainly increased inv to increase the modulation ratio m and thus improve the voltage transfer ratio.

[0087] Within the overmodulation region II, the modulation ratio m of the inverter stage is increased by changing the amplitude of the output voltage of the inverter stage inv . As analyzed above, the modulation ratio m of the inverter stage inv is related to the reference angle α2. Therefore, first, according to the relationship formula between the modulation ratio m of the inverter stage inv and the reference angle α2, the reference angle α2 required to achieve the desired modulation ratio m of the inverter stage inv is determined.

[0088] One approach is to calculate the required reference angle α2 according to the above formula (8). However, since formula (8) involves complex operations, in another embodiment, when the second look-up curve shown in Figure 5 is pre-constructed, the reference angle α2 corresponding to the calculated modulation ratio m of the inverter stage inv can be directly determined by querying the second look-up curve.

[0089] Then, the duty ratios required for space vector modulation are determined in combination with the reference angle α2, the modulation ratio m, and the vector position angle θ, including:

[0090] First, d1′ and d2′, which are intermediate variables of the two duty ratios, are determined according to the modulation ratio m and the vector position angle θ. d1′ and d2′ are two intermediate variables of the duty ratios.

[0091] When , the duty ratios d1 and d2 required for space vector modulation are Otherwise, the duty ratios d1 and d2 required for space vector modulation are directly determined as

[0092] (4) When the modulation ratio m ≥ m2, it is determined to be in the overmodulation zone III. According to the relationship between the voltage vector trajectory and the output voltage waveform when the inverter basic vector maintains overmodulation, the duty cycle required for space vector modulation is determined in combination with the modulation ratio m and the vector position angle θ. According to the above analysis of the overmodulation zone II, the required reference bus voltage u can be determined in this case. dcref and inverter modulation ratio m inv It is also shown in the above formula (16).

[0093] It can also be seen from the above formula (16) that in the overmodulation region III, the reference bus voltage u dcref unchanged, mainly by increasing the inverter modulation ratio m inv Increasing the modulation ratio m can improve the voltage transfer ratio.

[0094] However, unlike overmodulation region II, overmodulation region III increases the inverter modulation ratio m by changing the amplitude and phase angle of the inverter output voltage. inv As can be seen from the above analysis, the inverter stage modulation ratio m inv It is related to the reference angle α3, so firstly according to the inverter level modulation ratio m inv The relationship between the reference angle α3 is used to determine the required inverter modulation ratio m. inv Required reference angle α3.

[0095] One approach is to calculate the required reference angle α3 according to the above formula (11). However, since formula (11) involves complex calculations, in another embodiment, when the following formula is pre-constructed: Figure 7 After the third lookup table curve is shown, the inverter level modulation ratio m obtained by calculating can be determined by directly looking up the third lookup table curve. inv The corresponding reference angle is α3.

[0096] Then, the duty cycle required for space vector modulation is determined based on the obtained reference angle α3 combined with the modulation ratio m and the vector position angle θ. This includes determining based on the reference angle α3 combined with the modulation ratio m and the vector position angle θ:

[0097]

[0098] when The duty cycles d1 and d2 required for space vector modulation are determined as When 0<θ≤α3, the duty ratios d1 and d2 required for space vector modulation are determined as follows: Otherwise, the duty cycles d1 and d2 required for space vector modulation are determined as

[0099] Regardless of which of the above situations is the case, after determining the duty ratios d1 and d2 required for space vector modulation, pulse width modulation can be performed according to the duty ratios d1 and d2 required for space vector modulation to obtain the inverter-stage switch tube drive signal, and then the switch tubes in the inverter-stage three-phase bridge arm of the 3TSMC are driven according to the inverter-stage switch tube drive signal.

[0100] The above is only a preferred embodiment of the present application, and the present application is not limited to the above embodiments. It is understood that other improvements and changes directly derived or associated by those skilled in the art without departing from the spirit and concept of the present application should be considered to be included in the protection scope of the present application.

Claims

1. A 3TSMC control method for improving the maximum voltage transfer ratio, characterized in that: The 3TSMC control method includes: Collect the three-phase input voltage of the double-stage matrix converter injected with the third harmonic and calculate the amplitude U of the three-phase input voltage im , according to the given three-phase reference output voltage, determine the amplitude U of the three-phase reference output voltage om and the phase angle θ r , and calculate the modulation ratio And the vector position angle of the output voltage vector in the sector Among them, / / is the remainder operator; When the modulation ratio m < 0.866, determine the duty cycle required for space vector modulation according to the three-phase input voltage and the vector position angle θ; When the modulation ratio satisfies \(0.866\leq m < m1\), it is determined that the overmodulation region I is entered, and the reference bus voltage is determined as and the virtual bus voltage \(u\) is calculated dcvir . According to the virtual bus voltage \(u\) dcvir , the duty ratio required for space vector modulation is determined in combination with the vector position angle \(\theta\). When the modulation ratio m1 ≤ m < m2, it is determined that it is in the overmodulation region II. According to the relationship between the voltage vector trajectory and the output voltage waveform during overmodulation with the minimum phase error of the inverter stage, combine the modulation ratio m and the vector position angle θ to determine the duty cycle required for space vector modulation; When the modulation ratio m ≥ m2, it is determined that it is in the overmodulation region III. According to the relationship between the voltage vector trajectory and the output voltage waveform during overmodulation with the basic vector of the inverter stage maintained, combine the modulation ratio m and the vector position angle θ to determine the duty cycle required for space vector modulation; According to the phase angle θ of the three-phase input voltage i Determine the rectifier-level switch tube drive signal and the bidirectional switch drive signal for driving the rectifier-level switch tube and the bidirectional switch in the 3TSMC, perform pulse width modulation according to the duty cycle required by the space vector modulation, and obtain the inverter-level switch tube drive signal for driving the switch tube in the inverter-level three-phase bridge arm of the 3TSMC; In the overmodulation region I, by increasing the virtual bus voltage u dcvir To increase the reference bus voltage u dcref To improve the voltage transfer ratio, in the overmodulation region II, the reference bus voltage u dcref On the basis of maintaining the maximum value, the voltage transfer ratio is improved by changing the amplitude of the inverter output voltage to increase the inverter modulation ratio. In the overmodulation area III, the reference bus voltage u dcref On the basis of maintaining the maximum value, the voltage transfer ratio is improved by changing the amplitude and phase angle of the inverter output voltage to improve the inverter modulation ratio.

2. The 3TSMC control method according to claim 1, characterized in that: Calculate the virtual bus voltage u dcvir And determine the duty cycle required for space vector modulation including: based on The relationship is based on the reference bus voltage u dcref Calculate the virtual bus voltage u dcvir , and determine the duty cycles d1 and d2 required for space vector modulation as: Among them, u dc It is the DC bus voltage calculated from the three-phase input voltage.

3. The 3TSMC control method according to claim 2, characterized in that: The 3TSMC control method includes: Using the reference angle of overmodulation zone I Construct virtual bus voltage u dcvir The expression is: Among them, u dcul is the upper limit of the virtual bus voltage associated with the reference angle α1 and: The virtual bus voltage u dcvir Substitute the expression into The reference bus voltage u is obtained from the relationship dcref The relationship with the reference angle α1 is: With reference bus voltage u dcref As the independent variable and the reference angle α1 as the dependent variable, the reference bus voltage u is constructed to represent dcref A first look-up table curve of a relationship with a reference angle α1; Calculate the virtual bus voltage u dcvir Also includes: Query the first look-up table curve to determine the reference bus voltage u dcref The corresponding reference angle α1 is obtained by querying the reference angle α1 according to Calculate the upper limit of the virtual bus voltage u dcul , and combined with Get the virtual bus voltage u dcvir .

4. The 3TSMC control method according to claim 1, characterized in that: The 3TSMC control method further includes: When determining the minimum phase error overmodulation of the inverter stage in the overmodulation region II, The output voltage waveform within the interval is: Among them, θ r is the phase angle of the three-phase reference output voltage, θ o is the phase angle of the actual output voltage, α2 is the reference angle of the overmodulation region II; Combined with the phase angle θ of the actual output voltage in overmodulation region II o =θ r The characteristics of the inverter stage modulation ratio m inv Relationship with reference angle α2; When the modulation ratio m1 ≤ m < m2, combining the modulation ratio m and the vector position angle θ to determine the duty cycle required for space vector modulation includes: Determine the inverter level modulation ratio according to the modulation ratio m Combined with the inverter modulation ratio m inv The reference angle α2 is determined by a relationship equation with the reference angle α2, and the duty cycle required for space vector modulation is determined based on the reference angle α2 combined with the modulation ratio m and the vector position angle θ.

5. The 3TSMC control method according to claim 4, characterized in that: Determining the duty cycle required for space vector modulation according to the reference angle α2 in combination with the modulation ratio m and the vector position angle θ includes: Determined by the modulation ratio m and the vector position angle θ when The duty cycles d1 and d2 required for space vector modulation are determined as Otherwise, the duty cycles d1 and d2 required for space vector modulation are directly determined as 6. The 3TSMC control method according to claim 4, characterized in that: The 3TSMC control method further includes: Construct inverter level modulation ratio m inv The relationship with the reference angle α2 is: The inverter modulation ratio is m inv As the independent variable and the reference angle α2 as the dependent variable, the inverter modulation ratio m is constructed to represent inv A second look-up curve of a relationship with the reference angle α2; The determining of the reference angle α2 comprises: querying the second look-up table curve to determine the inverter level modulation ratio m obtained by calculation inv The corresponding reference angle is α2.

7. The 3TSMC control method according to claim 1, characterized in that: The 3TSMC control method further includes: When determining that the inverter level basic vector is maintained overmodulated in overmodulation zone III, The output voltage waveform within the interval is: Among them, θ r is the phase angle of the three-phase reference output voltage, θ o is the phase angle of the actual output voltage, α3 is the reference angle of the overmodulation region III; Combined with the phase angle θ of the actual output voltage in the overmodulation region III o The phase angle θ with the three-phase reference output voltage r The following relationship is used to construct the inverter modulation ratio m inv Relationship with reference angle α3: When the modulation ratio m ≥ m2, combining the modulation ratio m and the vector position angle θ to determine the duty cycle required for space vector modulation includes: Determine the inverter level modulation ratio according to the modulation ratio m Combined with the inverter modulation ratio m inv The reference angle α3 is determined by a relationship equation with the reference angle α3, and the duty cycle required for the space vector modulation is determined based on the reference angle α3 combined with the modulation ratio m and the vector position angle θ.

8. The 3TSMC control method according to claim 7, characterized in that: Determining the duty cycle required for space vector modulation according to the reference angle α3 in combination with the modulation ratio m and the vector position angle θ includes: Determine according to the reference angle α3 in combination with the modulation ratio m and the vector position angle θ: when The duty cycles d1 and d2 required for space vector modulation are determined as When 0<θ≤α3, the duty ratios d1 and d2 required for space vector modulation are determined as follows: Otherwise, the duty cycles d1 and d2 required for space vector modulation are determined as 9. The 3TSMC control method according to claim 7, characterized in that: The 3TSMC control method further includes: Construct inverter level modulation ratio m inv The relationship with the reference angle α3 is: The inverter modulation ratio is m inv As the independent variable and the reference angle α3 as the dependent variable, the inverter modulation ratio m is constructed to represent inv A third look-up table curve of a relationship with the reference angle α3; Combined with the inverter modulation ratio m inv The relationship between the reference angle α3 and the reference angle α3 includes: The third look-up table curve is determined by querying the inverter level modulation ratio m obtained by calculation. inv The corresponding reference angle is α3.

10. The 3TSMC control method according to claim 1, characterized in that: m1 = 0.955, m2 = 1.002.

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