A method, system and application of discontinuous carrier modulation for reducing switching loss

Abstract

The application belongs to the technical field of power electronics, and discloses a discontinuous carrier modulation method, system and application for reducing switching loss. The method obtains normalized sinusoidal waves of phase A, phase B and phase C according to a three-phase normalization formula of a SPWM modulation strategy of a three-phase Vienna rectifier; calculates a corrected modulation wave; calculates a zero sequence voltage for reducing switching loss, and injects the zero sequence voltage into the three-phase normalized sinusoidal waves to obtain three-phase Vienna rectifier discontinuous modulation waves of phase A, phase B and phase C for reducing switching loss. The application can greatly reduce switching loss and improve the efficiency of a converter. The application does not need to calculate additional modulation coefficients according to different modulation ratios, and only needs one expression to calculate a zero sequence component under different modulation ratios. The application does not need sector judgment, and only needs to inject a zero sequence component once, so the calculation is simple and the calculation burden of a digital controller can be reduced.

Description

Technical Field

[0001] This invention belongs to the field of power electronics technology, and particularly relates to a discontinuous carrier modulation method, system and application for reducing switching losses. Background Technology

[0002] Vienna rectifiers are widely used in industrial applications due to their high power density, high efficiency, and high reliability. In this topology, only half the DC link voltage is present on the bidirectional switches, thus requiring only lower voltage stress on these switches. These advantages make it an attractive topology for active front-end rectification applications. Increasing the switching frequency can reduce the size of passive components such as filter inductors and increase power density, but it also leads to increased switching losses, which is detrimental to improving converter efficiency. At the same time, a higher switching frequency means shorter interrupt calculation cycles and a higher computational burden on the digital controller.

[0003] The literature X. Zhang, Q. Wang, R. Burgos and D. Boroyevich, "Discontinuous pulsewidth modulation methods with neutral point voltage balancing for three-phase Vienna rectifiers," 2015 IEEE Energy Conversion Congress and Exposition (ECCE), 2015, pp. 225-232, doi:10.1109 / ECCE.2015.7309692, proposes a discontinuous modulation method to reduce switching losses for Vienna rectifiers. However, this method is based on space vectors, which requires complex judgment of large and small sectors, vector selection, and calculation of the action time, resulting in complex calculations and a large computational load. The literature K. Li, M. Wei, C. Xie, F. Deng, JM Guerrero, and JCVasquez, “Triangle Carrier-based DPWM for Three-level NPC Inverters,” IEEE J. Emerg. Sel. Topics Power Electron, vol. 6, no. 4, pp. 1966-1978, Dec. 2018, proposes a three-level carrier discontinuous modulation method. However, this method requires selecting and setting modulation coefficients according to different modulation ratios, and the tables used for setting these coefficients vary across different modulation ratio ranges. Furthermore, this method requires two common-mode coefficients, necessitating the injection of two different common-mode components to generate the final zero-sequence component. Therefore, the coefficient setting process is complex and the steps are cumbersome. Thus, it is necessary to research a discontinuous carrier modulation method that is computationally simple, has a low control burden, and improves converter efficiency. Summary of the Invention

[0004] To overcome the problems existing in related technologies, the present invention discloses a discontinuous carrier modulation method, system and application for reducing switching losses.

[0005] The technical solution is as follows: a discontinuous carrier modulation method for reducing switching losses, comprising:

[0006] Based on the three-phase normalization formula of the SPWM modulation strategy of the three-phase Vienna rectifier, the normalized sine waves of phases A, B, and C are obtained as u... ma ,u mb ,u mc ;

[0007] Calculate the modified modulation wave

[0008] Calculate the zero-sequence voltage u to reduce switching losses z.loss and the zero-sequence voltage u z.loss Injecting a three-phase normalized sine wave yields a three-phase Vienna rectifier discontinuous modulation wave with reduced switching losses, consisting of phases A, B, and C. ref_a ,u ref_b ,u ref_c .

[0009] Furthermore, the normalized sine waves of phases A, B, and C obtained are respectively u ma ,u mb ,u mc In this context, the method for determining a three-phase normalized sine wave is as follows:

[0010]

[0011]

[0012] In the formula, u ma For phase A normalized sine wave, u mb For the normalized sine wave of phase B, u mc For a C-phase normalized sine wave, f g U is the power grid frequency, m is the modulation ratio, m∈(0,1); m U is the amplitude of the AC reference phase voltage. dc This is the DC-side bus voltage.

[0013] Furthermore, the modified modulation wave is calculated. In the middle, the modulated wave is corrected. Based on the following formula, we get:

[0014]

[0015] In the formula, u mx Normalized sine waves u for phases A, B, and C ma ,u mb ,u mc , x = a, b, and c.

[0016] Furthermore, the zero-sequence voltage u that reduces switching losses is calculated. z.loss The method for determining it is shown in the following formula:

[0017]

[0018] In the formula, u mid Normalized sine waves u for phases A, B, and C ma ,u mb ,u mc The median value, Modulation waves for phases A, B, and C The maximum, minimum, and median values.

[0019] Furthermore, the zero-sequence voltage u z.loss Injecting a three-phase normalized sine wave yields a three-phase Vienna rectifier discontinuous modulation wave with reduced switching losses, consisting of phases A, B, and C. ref_a ,u ref_b ,u ref_c ,include:

[0020] For u ref_a ,u ref_b ,u ref_c The determination method is as follows:

[0021]

[0022] In the formula, u ref_a ,u ref_b ,u ref_c These are three-phase discontinuous carrier modulation waves to reduce switching losses, u ma For phase A normalized sine wave, u mb For the normalized sine wave of phase B, u mc For the C-phase normalized sine wave, u z.loss Zero-sequence voltage injected by discontinuous carrier modulation to reduce switching losses.

[0023] Another object of the present invention is to provide a discontinuous carrier modulation system for reducing switching losses, which is achieved by the aforementioned discontinuous carrier modulation method for reducing switching losses. The system includes:

[0024] The three-phase normalized sine wave acquisition module is used to obtain the normalized sine waves of phases A, B, and C, respectively, based on the three-phase normalization formula of the three-phase Vienna rectifier SPWM modulation strategy. ma ,u mb ,u mc ;

[0025] The modified modulation wave calculation module is used to calculate the modified modulation wave.

[0026] The discontinuous modulation wave acquisition module is used to calculate the zero-sequence voltage u to reduce switching losses. z.loss and the zero-sequence voltage u z.loss Injecting a three-phase normalized sine wave yields a three-phase Vienna rectifier discontinuous modulation wave with reduced switching losses, consisting of phases A, B, and C. ref_a ,u ref_b ,u ref_c .

[0027] Furthermore, the system is integrated into the Vienna rectifier to improve power density.

[0028] Furthermore, the system is integrated into the rectifier circuit to improve power density.

[0029] Furthermore, the system is integrated into the motor to increase power density.

[0030] Furthermore, this system is installed in environmentally friendly electric vehicles to improve power density.

[0031] Combining all the above technical solutions, the advantages and positive effects of this invention are as follows: Compared with traditional modulation methods, this invention only requires a single expression to calculate the zero-sequence component under different modulation ratios, without the need for additional coefficient adjustments, which can minimize switching losses and improve converter efficiency. This invention does not require sector judgment and only needs to inject the zero-sequence component once, making engineering implementation simple and convenient.

[0032] This invention significantly reduces switching losses and improves converter efficiency. It eliminates the need to calculate additional modulation coefficients for different modulation ratios; the zero-sequence component is calculated using only the same expression across all modulation ratios. Furthermore, it eliminates the need for sector judgment and requires only one injection of the zero-sequence component, simplifying calculations and reducing the computational burden on the digital controller. This invention reduces the need for high-end controllers, lowering the hardware cost of controllers used in fast-charging systems for electric vehicles; it also reduces converter switching losses and improves overall converter efficiency. The carrier wave method significantly reduces the modulation signal calculation time. Attached Figure Description

[0033] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with this disclosure and, together with the description, serve to explain the principles of this disclosure;

[0034] Figure 1 This is a schematic diagram of a common three-phase Vienna rectifier main circuit topology and its oscillation and unbalanced midpoint voltage in the prior art provided by the embodiments of the present invention;

[0035] Figure 2 This is a flowchart of a discontinuous carrier modulation method for reducing switching losses provided in an embodiment of the present invention;

[0036] Figure 3 This refers to the clamping region of the method of the present invention provided in this embodiment;

[0037] Figure 4 This is a simulation waveform diagram of the A-phase modulated wave of the zero-sequence voltage and the discontinuous carrier modulation method for reducing switching losses according to the present invention when m=0.4, provided in an embodiment of the present invention.

[0038] Figure 5This is a simulation waveform diagram of the AC side A-phase input voltage and AC side A-phase input current when m=0.4, using the discontinuous carrier modulation method for reducing switching losses provided in this embodiment of the invention.

[0039] Figure 6 This is a simulation waveform of the A-phase bridge arm voltage when m = 0.4, provided by an embodiment of the present invention, using the discontinuous carrier modulation method for reducing switching losses according to the present invention.

[0040] Figure 7 This is a simulation waveform diagram of the A-phase modulated wave of the zero-sequence voltage and the discontinuous carrier modulation method for reducing switching losses according to the present invention when m=0.7, provided in an embodiment of the present invention.

[0041] Figure 8 This is a simulation waveform diagram of the AC side A-phase input voltage and AC side A-phase input current when m=0.7, using the discontinuous carrier modulation method for reducing switching losses provided in this embodiment of the invention.

[0042] Figure 9 This is a simulation waveform of the A-phase bridge arm voltage when m=0.7, provided by an embodiment of the present invention, using the discontinuous carrier modulation method of the present invention to reduce switching losses. Detailed Implementation

[0043] To make the above-mentioned objects, features, and advantages of the present invention more apparent and understandable, specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings. Many specific details are set forth in the following description to provide a thorough understanding of the present invention. However, the present invention can be practiced in many other ways different from those described herein, and those skilled in the art can make similar modifications without departing from the spirit of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below.

[0044] The innovative aspects of the discontinuous carrier modulation method and system for reducing switching losses provided in this invention are as follows: This invention can significantly reduce switching losses and improve converter efficiency. This invention does not require calculating additional modulation coefficients based on different modulation ratios; for different modulation ratios, only the same expression is needed to calculate the zero-sequence component. This invention does not require sector determination and only needs to inject the zero-sequence component once, simplifying the calculation and reducing the computational burden on the digital controller.

[0045] Example 1, such as Figure 1The diagram shows a common three-phase Vienna rectifier main circuit topology and its oscillation and unbalanced midpoint voltage. The three-phase Vienna rectifier includes three-phase AC power supplies (ea, eb, ec), three-phase input filter inductors (La, Lb, Lc), first to sixth power diodes (D1-D6), first to sixth power switching transistors (S1-S6), a first DC bus filter capacitor (C1) and a second DC bus filter capacitor (C2), a first DC load (R1) and a second DC load (R2). The six power diodes are connected in pairs to form three-phase bridge arms, and the six power switching transistors are also connected in pairs to form three-phase bridge arms. The first and second DC bus filter capacitors are respectively connected to the two ends of the midpoint on the DC side.

[0046] The discontinuous carrier modulation method for reducing switching losses provided in this invention includes:

[0047] Based on the three-phase normalization formula of the SPWM modulation strategy of the three-phase Vienna rectifier, the normalized sine waves of phases A, B, and C are obtained as u... ma ,u mb ,u mc ;

[0048] Calculate the modified modulation wave

[0049] Calculate the zero-sequence voltage u to reduce switching losses z.loss and the zero-sequence voltage u z.loss Injecting a three-phase normalized sine wave yields a three-phase Vienna rectifier discontinuous modulation wave with reduced switching losses, consisting of phases A, B, and C. ref_a ,u ref_b ,u ref_c ;

[0050] The modulated wave is compared with the triangular carrier wave to generate the switching signal for the three-phase power switching device.

[0051] Example 2, as another specific embodiment of the present invention, such as Figure 2 As shown, the implementation process of the discontinuous carrier modulation method for reducing switching losses in this invention involves injecting a zero-sequence component into a three-phase normalized sine wave to generate a three-phase modulation signal, which is then compared with a triangular wave. Specifically, it includes:

[0052] Step 1: Based on the three-phase normalization formula of the three-phase Vienna rectifier SPWM modulation strategy, the normalized sine waves of phases A, B, and C are obtained as u... ma ,u mb ,u mc The method for determining the three-phase normalized sine wave is as follows:

[0053]

[0054]

[0055] In equation (1), u ma For phase A normalized sine wave, u mb For the normalized sine wave of phase B, u mc For a C-phase normalized sine wave, f g U is the power grid frequency, m is the modulation ratio, m∈(0,1); m U is the amplitude of the AC reference phase voltage. dc This is the DC-side bus voltage.

[0056] Step 2, Modified Modulation Wave Calculation: Modified Modulation Wave of Discontinuous Carrier Modulation Method for Reducing Switching Losses Calculate according to formula (2):

[0057]

[0058] In equation (2), u mx Normalized sine waves u for phases A, B, and C ma ,u mb ,u mc , x = a, b, and c.

[0059] Step 3, zero-sequence voltage calculation, define the zero-sequence voltage that reduces switching losses as u. z.loss The zero-sequence voltage u that reduces switching losses z.loss The method for determining it is shown in equation (3):

[0060]

[0061] In the formula, u mid Normalized sine waves u for phases A, B, and C ma ,u mb ,u mc The median value, Modulation waves for phases A, B, and C The maximum, minimum, and median values.

[0062] Step 4: Obtain the modulation wave of the discontinuous carrier modulation method to reduce switching losses. Define the three-phase discontinuous carrier modulation wave for reducing switching losses as u... ref_a ,u ref_b ,u ref_c This invention relates to u ref_a ,u ref_b ,u ref_c The determination method is as follows:

[0063]

[0064] In the formula, u ref_a ,uref_b ,u ref_c These are three-phase discontinuous carrier modulation waves to reduce switching losses, u ma For phase A normalized sine wave, u mb For the normalized sine wave of phase B, u mc For the C-phase normalized sine wave, u z.loss Zero-sequence voltage injected by discontinuous carrier modulation to reduce switching losses.

[0065] The clamping modes of the discontinuous carrier modulation for reducing switching losses at different modulation ratios are as follows: Figure 3 As shown, phase A clamping, phase B clamping, and phase C clamping represent the voltage clamping of the bridge arms of phases A, B, and C, respectively.

[0066] Example 3: The present invention provides a discontinuous carrier modulation system for reducing switching losses, the system comprising:

[0067] The three-phase normalized sine wave acquisition module is used to obtain the normalized sine waves of phases A, B, and C, respectively, based on the three-phase normalization formula of the three-phase Vienna rectifier SPWM modulation strategy. ma ,u mb ,u mc ;

[0068] The modified modulation wave calculation module is used to calculate the modified modulation wave.

[0069] The discontinuous modulation wave acquisition module is used to calculate the zero-sequence voltage u to reduce switching losses. z.loss and the zero-sequence voltage u z.loss Injecting a three-phase normalized sine wave yields a three-phase Vienna rectifier discontinuous modulation wave with reduced switching losses, consisting of phases A, B, and C. ref_a ,u ref_b ,u ref_c .

[0070] Example 4: The present invention provides a discontinuous carrier modulation system with reduced switching losses, which is mounted on a Vienna rectifier to improve power density.

[0071] Example 5: The present invention provides a discontinuous carrier modulation system with reduced switching losses that is mounted on a rectifier circuit to improve power density.

[0072] Example 6: The present invention provides a discontinuous carrier modulation system for reducing switching losses that is mounted on a motor to improve power density.

[0073] Example 7: The present invention provides a discontinuous carrier modulation system for reducing switching losses that is mounted on an environmentally friendly electric vehicle to improve power density.

[0074] In the above embodiments, the descriptions of each embodiment have different focuses. For parts that are not described in detail or recorded in a certain embodiment, please refer to the relevant descriptions of other embodiments.

[0075] To further illustrate the effects of the embodiments of the present invention, the following experiments were conducted.

[0076] This invention utilizes PLECS software to build a simulation model of a three-phase Vienna rectifier, and verifies the effectiveness of the discontinuous carrier modulation method for reducing switching losses. The simulation conditions are: simulation step size 3µs, AC effective voltage 115V, fundamental frequency 400Hz, and switching frequency 100kHz.

[0077] Figure 4 The simulation waveform of the A-phase modulated wave, with zero-sequence voltage and input voltage at m=0.4, is shown below, using the discontinuous carrier modulation method for reducing switching losses as described in this invention. z.loss This is the zero-sequence voltage injected in this invention, u ref_a It is a phase A modulated wave;

[0078] Figure 5 The simulation waveforms of the AC-side A-phase input voltage and AC-side A-phase input current using the discontinuous carrier modulation method for reducing switching losses according to the present invention at m=0.4 are shown. a It is the AC side A-phase input voltage, i a It is the AC side A-phase input current;

[0079] Figure 6 The simulated waveform of the A-phase bridge arm voltage at m=0.4 is shown below, illustrating the discontinuous carrier modulation method for reducing switching losses according to the present invention. _AO It is the voltage of phase A bridge arm.

[0080] Figure 7 The simulation waveform of the A-phase modulated wave, with zero-sequence voltage and input voltage at m=0.7, is shown below, using the discontinuous carrier modulation method of the present invention to reduce switching losses. z.loss This is the zero-sequence voltage injected in this invention, u ref_a It is a phase A modulated wave;

[0081] Figure 8 The simulation waveforms of the AC-side A-phase input voltage and AC-side A-phase input current using the discontinuous carrier modulation method for reducing switching losses according to the present invention at m=0.7 are shown. a It is the AC side A-phase input voltage, i a It is the AC side A-phase input current;

[0082] Figure 9 The simulated waveform of the A-phase bridge arm voltage at m=0.7 is shown below, illustrating the discontinuous carrier modulation method for reducing switching losses according to the present invention._AO It is the voltage of phase A bridge arm.

[0083] Depend on Figure 4 and Figure 9 As can be seen, when using the discontinuous carrier modulation method of the present invention to reduce switching losses, the bridge arm voltage is clamped near the current peak, and... Figure 3 The consistent clamping region effectively reduces switching losses, and the AC current waveform quality is good, demonstrating the correctness of the proposed discontinuous carrier modulation method for reducing switching losses.

[0084] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any modifications, equivalent substitutions and improvements made by those skilled in the art within the scope of the technology disclosed in the present invention and within the spirit and principles of the present invention should be covered within the scope of protection of the present invention.

Claims

1. A discontinuous carrier modulation method for reducing switching losses, characterized in that, The method includes: Based on the three-phase normalization formula of the SPWM modulation strategy of the three-phase Vienna rectifier, the normalized sine waves of phases A, B, and C are respectively obtained. ; Calculate the modified modulation wave ; Calculate the zero-sequence voltage to reduce switching losses and zero-sequence voltage By injecting a three-phase normalized sine wave, a discontinuous modulation wave with reduced switching losses for the three-phase Vienna rectifier (phases A, B, and C) is obtained. ; The obtained normalized sine waves of phases A, B, and C are respectively... In this context, the method for determining a three-phase normalized sine wave is as follows: In the formula, For phase A, normalized sine wave, For phase B, normalized sine wave, For the C-phase normalized sine wave, For the power grid frequency, The modulation ratio, ; The amplitude of the AC reference phase voltage, This refers to the DC-side bus voltage. Calculate the modified modulation wave In the middle, the modulated wave is corrected. Based on the following formula, we get: In the formula, Normalized sine waves for phases A, B, and C , ; Calculate the zero-sequence voltage to reduce switching losses The method for determining is shown in the following formula: In the formula, Normalized sine waves for phases A, B, and C The median value, Modulation waves for phases A, B, and C The maximum, minimum, and median values.

2. The discontinuous carrier modulation method for reducing switching losses according to claim 1, characterized in that, zero-sequence voltage By injecting a three-phase normalized sine wave, a discontinuous modulation wave with reduced switching losses for the three-phase Vienna rectifier (phases A, B, and C) is obtained. ,include: right The determination method is as follows: In the formula, These are three-phase discontinuous carrier modulation waves designed to reduce switching losses. For phase A, normalized sine wave, For phase B, normalized sine wave, For the C-phase normalized sine wave, Zero-sequence voltage injected by discontinuous carrier modulation to reduce switching losses.

3. A discontinuous carrier modulation system for reducing switching losses, characterized in that, The system is implemented using the discontinuous carrier modulation method for reducing switching losses as described in any one of claims 1-2, and the system comprises: The three-phase normalized sine wave acquisition module is used to obtain the normalized sine waves of phases A, B, and C based on the three-phase normalization formula of the three-phase Vienna rectifier SPWM modulation strategy. ; The modified modulation wave calculation module is used to calculate the modified modulation wave. ; The discontinuous modulation wave acquisition module is used to calculate the zero-sequence voltage to reduce switching losses. and zero-sequence voltage By injecting a three-phase normalized sine wave, a discontinuous modulation wave with reduced switching losses for the three-phase Vienna rectifier (phases A, B, and C) is obtained. .

4. The discontinuous carrier modulation system for reducing switching losses according to claim 3, characterized in that, The system is integrated into the Vienna rectifier to improve power density.

5. The discontinuous carrier modulation system for reducing switching losses according to claim 4, characterized in that, This system is integrated into the rectifier circuit to improve power density.

6. The discontinuous carrier modulation system for reducing switching losses according to claim 5, characterized in that, The system is mounted on the motor to increase power density.

7. The discontinuous carrier modulation system for reducing switching losses according to claim 6, characterized in that, This system is installed in environmentally friendly electric vehicles to increase power density.

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