A control method and system of dual active bridge converter for motor load current feedforward

Abstract

The application discloses a motor load current feedforward double active bridge converter control method and system, comprising the following steps: constructing an associated equation of an output voltage of a double active bridge converter with a motor load, a phase shift ratio and a motor load current; determining the motor load current according to a motor instantaneous input power; obtaining a phase shift ratio feedforward control amount after feedforward control of the motor load current based on a feedforward coefficient; obtaining a phase shift ratio reference control amount according to a current output voltage and an output voltage given value; obtaining an output voltage control value by using the associated equation according to the phase shift ratio feedforward control amount, the phase shift ratio reference control amount and the motor load current, so as to control on-off of a switch tube of the double active bridge converter, and make the output voltage meet the output voltage control value. Without increasing external devices of the system, dynamic stability of a high-voltage direct-current system of an electric vehicle is effectively improved.

Description

Technical Field

[0001] This invention relates to the field of motor drive control technology, and in particular to a dual active bridge converter control method and system with motor load current feedforward. Background Technology

[0002] The statements in this section are merely background information related to the present invention and do not necessarily constitute prior art.

[0003] Regenerative braking is a key feature of electric vehicles (EVs), and short driving range is a significant factor limiting their development. Its effectiveness is particularly pronounced in urban traffic conditions with frequent start-stop, acceleration, and deceleration. Therefore, optimizing regenerative braking systems to recover, store, and reuse energy that would otherwise be lost during braking is crucial for improving the driving range of EVs. Currently, most EVs use a single battery pack as an energy storage device, so improving the accuracy and dynamic efficiency of regenerative braking control in battery-powered EVs is a key area for technological breakthroughs.

[0004] Currently, in electric vehicle high-voltage DC systems, each module is designed independently and simply interconnected on the DC bus, neglecting the coupling between modules. Although each module can operate stably independently, the integrated system may experience bus instability. This is due to the strict closed-loop control of the power electronic converter and the negative impedance characteristics of the driven motor load, which reduce system stability. Therefore, analyzing the stability of electric vehicle high-voltage DC systems from a holistic system perspective and clarifying the limitations of the motor load are of positive significance for reducing high-voltage faults and ensuring safe vehicle operation. Summary of the Invention

[0005] To address the aforementioned issues, this invention proposes a dual active bridge converter control method and system with motor load current feedforward. This method controls the change of motor load current using a feedforward approach, effectively improving the dynamic stability of the electric vehicle's high-voltage DC system without increasing system peripherals.

[0006] To achieve the above objectives, the present invention adopts the following technical solution:

[0007] In a first aspect, the present invention provides a dual active bridge converter control method with motor load current feedforward, comprising:

[0008] Construct the correlation equation between the output voltage of a dual active bridge converter with motor load and the shift ratio and motor load current;

[0009] The motor load current is determined based on the instantaneous input power of the motor. After the motor load current is fed forward based on the feedforward coefficient, the shift ratio feedforward control quantity is obtained.

[0010] Based on the current output voltage and the output voltage setpoint, the shift ratio reference control quantity is obtained. Based on the shift ratio feedforward control quantity, the shift ratio reference control quantity, and the motor load current, the output voltage control value is obtained using the correlation equation. This control is used to control the on / off state of the switching transistors of the dual active bridge converter, so that the output voltage meets the output voltage control value.

[0011] As an alternative implementation, the correlation equation is:

[0012]

[0013] Among them, v o G is the output voltage of the dual active bridge converter. DV (s) represents a single voltage loop model; Z out (s) is the motor load current coefficient; C2 is the DC bus capacitance; d is the shift ratio of the dual active bridge converter; g od s is the offset of the output current relative to d; s is the complex frequency of the Laplace transform; R is the stator resistance; i load This is the motor load current.

[0014] As an alternative implementation, after introducing feedforward coefficients into the single-voltage loop model, and combining them with the motor load current coefficient, a single-voltage loop feedforward model is constructed as follows: G DV (s)·G f (s)-Z out (s) = 0; where G f (s) represents the feedforward coefficients.

[0015] As an alternative implementation, the feedforward coefficient is the reciprocal of the output current shift relative to the offset.

[0016] As an alternative implementation, the difference between the shift ratio reference control quantity and the shift ratio feedforward control quantity is used as the input of the single voltage loop model. Based on the output of the single voltage loop model, the motor load current coefficient, and the motor load current, the output voltage correlation equation is used to determine the output voltage control value. The motor load current is fed forward as the shift ratio fluctuation, thereby controlling the on / off state of the dual active bridge converter switching transistors.

[0017] As an alternative implementation, the instantaneous input power of the motor is obtained based on the sum of the motor copper loss, reactive power and output mechanical power, and the motor load current is obtained based on the ratio of the instantaneous input power of the motor to the output voltage.

[0018] As an alternative implementation, a shift ratio reference control quantity is obtained by using PI control based on the difference between the output voltage setpoint and the current output voltage.

[0019] Secondly, the present invention provides a dual active bridge converter control system with motor load current feedforward, comprising:

[0020] The model building module is configured to construct the correlation equation between the output voltage of a dual active bridge converter with a motor load and the shift ratio and the motor load current.

[0021] The feedforward module is configured to determine the motor load current based on the instantaneous input power of the motor, and after performing feedforward control on the motor load current based on the feedforward coefficient, the shift ratio feedforward control quantity is obtained.

[0022] The control module is configured to obtain a shift ratio reference control quantity based on the current output voltage and the output voltage setpoint. Based on the shift ratio feedforward control quantity, the shift ratio reference control quantity, and the motor load current, the output voltage control value is obtained using an association equation. This control is then used to control the on / off state of the dual active bridge converter switching transistors, ensuring that the output voltage meets the output voltage control value.

[0023] Thirdly, the present invention provides an electronic device including a memory and a processor, and computer instructions stored in the memory and running on the processor, wherein the computer instructions, when executed by the processor, perform the method described in the first aspect.

[0024] Fourthly, the present invention provides a computer-readable storage medium for storing computer instructions, which, when executed by a processor, perform the method described in the first aspect.

[0025] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0026] This invention proposes a dual active bridge converter control method and system with motor load current feedforward. The method employs a feedforward approach to control the changes in the motor load current, feeding forward the influence of the motor load current as fluctuations in the shift ratio, thereby improving the dynamic stability of the system control. Compared to traditional closed-loop control systems, this method only requires feeding forward the influence of the motor load current as fluctuations in the shift ratio to complete the control of the dual active bridge converter, reducing the use of sensors and simplifying the control method's computation. It effectively improves the dynamic stability of the electric vehicle's high-voltage DC system without increasing system peripherals.

[0027] Advantages of additional aspects of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. Attached Figure Description

[0028] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an improper limitation of the invention.

[0029] Figure 1This is a schematic diagram of the control flow of the dual active bridge converter provided in Embodiment 1 of the present invention;

[0030] Figure 2 This is a schematic diagram of a single voltage loop model provided in Embodiment 1 of the present invention;

[0031] Figure 3 This is a schematic diagram of a dual active bridge converter system with a motor load provided in Embodiment 1 of the present invention. Detailed Implementation

[0032] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0033] It should be noted that the following detailed descriptions are exemplary and intended to provide further illustration of the invention. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains.

[0034] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the exemplary embodiments of the present invention. As used herein, unless the context clearly indicates otherwise, the singular form is also intended to include the plural form. Furthermore, it should be understood that the terms “comprising” and “having”, and any variations thereof, are intended to cover non-exclusive inclusion, for example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.

[0035] Where there is no conflict, the embodiments and features in the embodiments of the present invention can be combined with each other.

[0036] Example 1

[0037] This embodiment provides a dual active bridge converter control method with motor load current feedforward, such as... Figure 1 As shown, it includes:

[0038] Construct the correlation equation between the output voltage of a dual active bridge converter with motor load and the shift ratio and motor load current;

[0039] The motor load current is determined based on the instantaneous input power of the motor. After the motor load current is fed forward based on the feedforward coefficient, the shift ratio feedforward control quantity is obtained.

[0040] Based on the current output voltage and the output voltage setpoint, the shift ratio reference control quantity is obtained. Based on the shift ratio feedforward control quantity, the shift ratio reference control quantity, and the motor load current, the output voltage control value is obtained using the correlation equation. This control is used to control the on / off state of the switching transistors of the dual active bridge converter, so that the output voltage meets the output voltage control value.

[0041] In this embodiment, the instantaneous input power of the motor is determined based on the motor's copper losses, reactive power, and output mechanical power, specifically:

[0042] Detecting three-phase current i x The subscripts x = a, b, c represent the three phases a, b, and c, and the three-phase current i x The components on the dq axis are i d andi q ;

[0043] Then the copper loss P of the motor cu Reactive power P react and output mechanical power P mech They are respectively:

[0044]

[0045]

[0046]

[0047] Where R is the stator resistance, ω is the rotor speed; ψ f ψ is the flux linkage (back EMF coefficient) of the rotor permanent magnet; d ψ q These are the dq-axis components of the flux linkage vector; L d L q These are the dq-axis components of the inductance vector, respectively; i d i q dq-axis components of the three-phase current vectors; p is the number of motor pole pairs.

[0048] According to the motor copper loss P cu Reactive power P react and output mechanical power P mech The sum of these values ​​yields the instantaneous input power P of the motor. mt Specifically:

[0049]

[0050] Among them, u d u q dq-axis components of the stator voltage vector.

[0051] In this embodiment, based on the instantaneous input power P of the motormt Obtain the motor load current i load for:

[0052]

[0053] Among them, v o This is the output voltage of the dual active bridge converter.

[0054] In this embodiment, the process of constructing the correlation equation between the output voltage of the dual active bridge converter with motor load and the shift ratio and motor load current includes:

[0055] First, the output voltage v is constructed based on the DC bus capacitor C2. o Differential equation:

[0056]

[0057] Where C2 is the DC bus capacitor, d is the shift ratio of the dual active bridge converter, and g od The offset of the output current relative to d, v i g is the input voltage of the dual active bridge converter. ovi The output current versus the input voltage v i The offset;

[0058] The differential equation for the output voltage, obtained by Laplace transform, is as follows:

[0059]

[0060] Where s is the complex frequency of the Laplace transform; Z out This is the motor load current coefficient;

[0061] Ignoring the influence of the input voltage, the differential equation for the output voltage is expressed as:

[0062]

[0063] Among them, G DV (s) is a single voltage loop model, Z out (s) is the motor load current coefficient, such as Figure 2 As shown.

[0064] In this embodiment, the motor load current is controlled using a feedforward method to improve the dynamic stability of the system. The feedforward coefficients are obtained from the single-voltage loop model and the motor load current coefficients. By introducing feedforward coefficients into the single-voltage loop model and combining them with the load current coefficients, a single-voltage loop feedforward model is constructed, as follows: Figure 1 As shown;

[0065] The feedforward coefficient is:

[0066]

[0067] Among them, G f (s) represents the feedforward coefficients.

[0068] In this embodiment, after performing feedforward control on the motor load current based on the feedforward coefficient, the shift ratio feedforward control quantity is obtained.

[0069] For the output voltage setpoint v ref and the current output voltage v o The difference, after PI control, yields the shift ratio reference control quantity D. * ;

[0070] The difference between the shift ratio and the reference control quantity and the shift ratio and the feedforward control quantity are used as the single voltage loop model G. DV The input of (s) is then based on the single voltage loop model G. DV The output voltage (s), motor load current coefficient, and motor load current are used to determine the output voltage control value using a differential equation. This control is then used to control the on / off state of the switching transistors VT1-VT6 of the dual active bridge converter. Figure 3 As shown, this embodiment feeds forward the influence of the motor load current to the fluctuation of the shift ratio, thereby improving the dynamic performance of the control.

[0071] Example 2

[0072] This embodiment provides a dual active bridge converter control system with motor load current feedforward, including:

[0073] The model building module is configured to construct the correlation equation between the output voltage of a dual active bridge converter with a motor load and the shift ratio and the motor load current.

[0074] The feedforward module is configured to determine the motor load current based on the instantaneous input power of the motor, and after performing feedforward control on the motor load current based on the feedforward coefficient, the shift ratio feedforward control quantity is obtained.

[0075] The control module is configured to obtain a shift ratio reference control quantity based on the current output voltage and the output voltage setpoint. Based on the shift ratio feedforward control quantity, the shift ratio reference control quantity, and the motor load current, the output voltage control value is obtained using an association equation. This control is then used to control the on / off state of the dual active bridge converter switching transistors, ensuring that the output voltage meets the output voltage control value.

[0076] It should be noted that the above modules correspond to the steps described in Embodiment 1, and the examples and application scenarios implemented by the above modules and the corresponding steps are the same, but are not limited to the content disclosed in Embodiment 1. It should also be noted that the above modules, as part of the system, can be executed in a computer system such as a set of computer-executable instructions.

[0077] In further embodiments, the following is also provided:

[0078] An electronic device includes a memory and a processor, as well as computer instructions stored in the memory and running on the processor, wherein the computer instructions, when executed by the processor, perform the method described in Embodiment 1. For brevity, further details are omitted here.

[0079] It should be understood that in this embodiment, the processor can be a central processing unit (CPU), or it can be other general-purpose processors, digital signal processors (DSPs), application-specific integrated circuits (ASICs), programmable gate arrays (FPGAs), or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc. The general-purpose processor can be a microprocessor or any conventional processor, etc.

[0080] Memory may include read-only memory and random access memory, and provides instructions and data to the processor. A portion of memory may also include non-volatile random access memory. For example, memory may also store information about the device type.

[0081] A computer-readable storage medium for storing computer instructions, which, when executed by a processor, perform the method described in Embodiment 1.

[0082] The method in Example 1 can be directly implemented by a hardware processor, or implemented by a combination of hardware and software modules within the processor. The software modules can reside in readily available storage media in the field, such as random access memory, flash memory, read-only memory, programmable read-only memory, electrically erasable programmable memory, or registers. This storage medium is located in memory, and the processor reads information from the memory and, in conjunction with its hardware, completes the steps of the above method. To avoid repetition, a detailed description is not provided here.

[0083] Those skilled in the art will recognize that the units, i.e., algorithm steps, of the various examples described in connection with this embodiment can be implemented in electronic hardware or a combination of computer software and electronic hardware. Whether these functions are implemented in hardware or software depends on the specific application and design constraints of the technical solution. Those skilled in the art can use different methods to implement the described functions for each specific application, but such implementation should not be considered beyond the scope of this application.

[0084] While the specific embodiments of the present invention have been described above in conjunction with the accompanying drawings, this is not intended to limit the scope of protection of the present invention. Those skilled in the art should understand that various modifications or variations that can be made by those skilled in the art without creative effort based on the technical solutions of the present invention are still within the scope of protection of the present invention.

Claims

1. A control method for a dual active bridge converter with motor load current feedforward, characterized in that, include: Construct the correlation equation between the output voltage of a dual active bridge converter with motor load and the shift ratio and motor load current; The correlation equation is: ； in, This is the output voltage of the dual active bridge converter; This is a single voltage loop model; C1 is the motor load current coefficient; C2 is the DC bus capacitance; Compared to the shift ratio of a dual active bridge converter, For output current shift ratio d The offset; s is the complex frequency of the Laplace transform; Stator resistance; This is the motor load current; The motor load current is determined based on the instantaneous input power of the motor. After the motor load current is fed forward based on the feedforward coefficient, the shift ratio feedforward control quantity is obtained. Based on the current output voltage and the output voltage setpoint, the shift ratio reference control quantity is obtained. Based on the shift ratio feedforward control quantity, the shift ratio reference control quantity and the motor load current, the output voltage control value is obtained by using the correlation equation. This control is used to control the on / off state of the switching transistors of the dual active bridge converter so that the output voltage meets the output voltage control value. Specifically, the difference between the shift ratio reference control quantity and the shift ratio feedforward control quantity is used as the input of the single voltage loop model. Based on the output of the single voltage loop model, the motor load current coefficient, and the motor load current, the output voltage correlation equation is used to determine the output voltage control value. The motor load current is fed forward to the shift ratio fluctuation, thereby controlling the on / off state of the dual active bridge converter switching transistor.

2. The dual active bridge converter control method with motor load current feedforward as described in claim 1, characterized in that, After introducing feedforward coefficients into the single-voltage loop model, and combining them with the motor load current coefficient, the single-voltage loop feedforward model is constructed as follows: ;in, is the feedforward coefficient.

3. The dual active bridge converter control method with motor load current feedforward as described in claim 2, characterized in that, The feedforward coefficient is the reciprocal of the output current shift relative to the offset.

4. The dual active bridge converter control method with motor load current feedforward as described in claim 1, characterized in that, The instantaneous input power of the motor is obtained based on the sum of the motor's copper losses, reactive power, and output mechanical power. The motor load current is obtained based on the ratio of the instantaneous input power to the output voltage.

5. The dual active bridge converter control method with motor load current feedforward as described in claim 1, characterized in that, Based on the difference between the given output voltage and the current output voltage, the shift ratio reference control quantity is obtained after PI control.

6. A dual active bridge converter control system with motor load current feedforward, characterized in that, include: The model building module is configured to construct the correlation equation between the output voltage of a dual active bridge converter with a motor load and the shift ratio and the motor load current. The correlation equation is: ； in, This is the output voltage of the dual active bridge converter; This is a single voltage loop model; C1 is the motor load current coefficient; C2 is the DC bus capacitance; Compared to the shift ratio of a dual active bridge converter, For output current shift ratio d The offset; s is the complex frequency of the Laplace transform; Stator resistance; This is the motor load current; The feedforward module is configured to determine the motor load current based on the instantaneous input power of the motor, and after performing feedforward control on the motor load current based on the feedforward coefficient, the shift ratio feedforward control quantity is obtained. The control module is configured to obtain a shift ratio reference control quantity based on the current output voltage and the output voltage setpoint. Based on the shift ratio feedforward control quantity, the shift ratio reference control quantity, and the motor load current, the output voltage control value is obtained by using an association equation. This control is used to control the on / off state of the dual active bridge converter switching transistors so that the output voltage meets the output voltage control value. Specifically, the difference between the shift ratio reference control quantity and the shift ratio feedforward control quantity is used as the input of the single voltage loop model. Based on the output of the single voltage loop model, the motor load current coefficient, and the motor load current, the output voltage correlation equation is used to determine the output voltage control value. The motor load current is fed forward to the shift ratio fluctuation, thereby controlling the on / off state of the dual active bridge converter switching transistor.

7. An electronic device, characterized in that, It includes a memory and a processor, as well as computer instructions stored in the memory and running on the processor, which, when executed by the processor, perform the method according to any one of claims 1-5.

8. A computer-readable storage medium, characterized in that, Used to store computer instructions, which, when executed by a processor, perform the method described in any one of claims 1-5.

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