A modulus decomposition-based active damping control method for bipolar direct current power distribution systems

Abstract

This invention discloses an active damping control method for bipolar DC distribution systems based on modulus decomposition. It incorporates line coupling into the system's stability criteria and active damping parameter design, deriving the pole-mode transformation matrix of the metal-return bipolar DC distribution system and obtaining a decoupling model of the bipolar DC line in the modulus component space. The modulus models of the source-side converter and load are also derived. Based on the established decoupling model of the bipolar DC distribution system in the modulus component space, an active damping control method based on modulus decomposition is proposed. This invention considers the impact of DC distribution lines on stability, incorporating line coupling into the system's stability criteria and active damping parameter design. The modulus damping control scheme proposed in this invention can more effectively suppress instability caused by the negative impedance characteristics of constant power loads and also provides a basis for parameter adjustment.

Description

Technical Field

[0001] This invention relates to the field of DC power distribution system control, specifically an active damping control method for bipolar DC power distribution systems based on modulus decomposition. Background Technology

[0002] Bipolar DC distribution systems offer advantages such as large power capacity, high power quality, and simple control, enabling efficient matching of DC distributed power sources, energy storage, and DC loads. Considering the corrosion and environmental issues caused by grounding current during asymmetrical operation, bipolar DC distribution systems with metal return will become the future trend for DC systems.

[0003] To enhance the stability of DC distribution systems and mitigate system instability caused by the negative impedance characteristics of constant power loads, scholars both domestically and internationally have conducted extensive research. Currently, methods for improving the stability of DC distribution systems are mainly divided into passive damping and active damping methods. Passive damping reduces the spikes in the system's transfer function by adding dissipative components to the inductors or capacitors in the system, thereby enhancing system stability. However, this method reduces the system's operating efficiency and cannot flexibly change the parameters of the passive damping. Another method achieves active damping by changing the control of the source-side converter in the DC distribution system and introducing virtual resistances into the capacitors and inductors.

[0004] Current active damping control methods for DC distribution systems include, for example, introducing feedback to the capacitors of the load converter to adjust its input impedance by adding virtual resistance. However, load converters in DC distribution systems are generally not centrally located, and their parameters and impedance characteristics vary significantly, thus limiting their application. For scenarios where the upstream and downstream converters contain LC filters, some studies have proposed adding active damping to the LC filters to achieve impedance matching between the upstream and downstream converters and enhance the stability of the DC distribution system. However, the LC filters in the upstream and downstream converters may increase hardware costs and system complexity. Another approach involves adding active damping devices (bidirectional DC / DC converters, synchronous Buck circuits, etc.) between the upstream and downstream converters. By applying appropriate control to these devices, the input and output impedance characteristics of the upstream and downstream converters can be altered, thereby protecting the system's stability. However, this method requires the introduction of additional circuitry and control systems, increasing system complexity and production costs. The aforementioned research on the stability of DC distribution systems is primarily based on unipolar DC systems; research on the stability of bipolar DC systems is limited, and all studies neglect the influence of the line on the control of active damping. Summary of the Invention

[0005] The purpose of this invention is to overcome the shortcomings of the prior art and provide an active damping control method for a bipolar DC power distribution system based on modulus decomposition, comprising the following steps:

[0006] Decoupling models of the bipolar DC converter, bipolar DC line, and DC load in the modulus component space are obtained respectively.

[0007] The decoupling models of the bipolar DC converter, the bipolar DC line, and the DC load in the modulus component space are integrated into a decoupling model of the DC distribution system in the modulus component space. Combined with the modulus transfer function of the bipolar DC system, active damping control is performed on the bipolar DC distribution system.

[0008] Furthermore, the decoupling model of the bipolar DC-DC converter in the module component space is as follows:

[0009] Voltage-current modulus transformation formula

[0010]

[0011] Its inverse change is:

[0012]

[0013] The decoupling model of the bipolar DC-DC converter in the modulus component space is obtained as follows:

[0014]

[0015] in:

[0016]

[0017] i L0 i L1 This represents the conversion of the positive and negative inductor currents in the mode component space, i.e., the common-mode inductor current and the differential-mode inductor current; v s0 v s1 V0, V1, and I0, I1 are the conversion quantities of the converter output voltage and power supply voltage in the modal component space; v0, v1 and i0, i1 are the conversion quantities of the positive and negative line voltages in the modal component space, i.e., the common-mode duty cycle and the differential-mode duty cycle, respectively. T B T This is the transpose of A and B.

[0018] Furthermore, the decoupling model of the bipolar DC line in the mode component space is as follows: using the modified polar mode transformation matrix

[0019]

[0020] Decouple the bipolar DC line and consider the effects of the line resistance, inductance, capacitance, and conductance matrix of the metal-return bipolar DC system:

[0021]

[0022]

[0023]

[0024]

[0025] In the formula: R +-n L +-n C +-n G +-n Represent the line resistance, inductance, capacitance, and conductance matrix of a metal-return bipolar DC system, R + R n R - L represents the resistance of the positive, neutral, and negative lines of a bipolar DC return system. + L n L - M represents the self-inductance of the positive, neutral, and negative lines of a bipolar DC return system, respectively. +n M +- M -n These represent the mutual inductances between the positive terminal and the neutral line, the positive terminal and the negative terminal, and the negative terminal and the neutral line in a bipolar DC system with return current, respectively. +i C ni C -i These represent the capacitances of the positive terminal to ground, the neutral terminal to ground, and the negative terminal to ground in a bipolar DC return system, respectively. +n C +- C -n These represent the capacitances of the positive terminal to the neutral line, the positive terminal to the negative terminal, and the negative terminal to the neutral line in a bipolar DC system with a return current, respectively. G +i G ni G -i G represents the conductance of the positive terminal to ground, the neutral terminal to ground, and the negative terminal to ground in a bipolar DC system with return current, respectively. +n G +- G -n These represent the conductances of the positive terminal to the neutral line, the positive terminal to the negative terminal, and the negative terminal to the neutral line in a bipolar DC system with a return current, respectively.

[0026] The model of the bipolar DC circuit in the modulus component space is obtained as follows:

[0027]

[0028]

[0029]

[0030] In the formula: R 01 L 01 C01 This represents the modulo components of resistance, inductance, and capacitance in a bipolar DC circuit.

[0031] Furthermore, the decoupling model of the DC load in the modulus component space is as follows:

[0032] The common-mode and differential-mode voltages satisfy:

[0033]

[0034] In the formula: v L0 v L1 Represents the common-mode and differential-mode voltages, respectively, R Lp R Ln These represent the equivalent DC loads at the positive and negative terminals, respectively, and V0 represents the rated voltage.

[0035] The parameters of the bipolar DC load in the modulus component space satisfy the following:

[0036]

[0037] In the formula: R pn This indicates a bipolar DC load.

[0038] Furthermore, the modulus transfer function of the bipolar DC system satisfies:

[0039]

[0040] In the formula: Let these represent the common-mode and differential-mode transfer functions of a bipolar DC system, respectively. V represents the common-mode and differential-mode small disturbances of a bipolar DC system, respectively. s Indicates the power supply voltage;

[0041] When the load is balanced, considering the effects of line inductance and capacitance on system stability, the transfer function satisfies:

[0042]

[0043] Where: G v0d0 (s), G v1d1 (s) represent the common-mode and differential-mode transfer functions of the bipolar DC system under balanced load, respectively; R0 and R1, L0 and L1, C0 and C1 represent the common-mode and differential-mode components of the line resistance, inductance, and capacitance of the bipolar DC system, respectively; Y lp This represents the equivalent impedance of the positive load.

[0044] Furthermore, the active damping control of the bipolar DC power distribution system includes:

[0045] If active damping based on inductor current is used, the common-mode output impedance expression of the input converter is:

[0046]

[0047] R L0v This represents the virtual resistance value connected in series with the inductor;

[0048] If active damping control is achieved using capacitor current, then the common-mode output impedance is:

[0049]

[0050] In the formula: R C0v This represents the virtual resistance connected in parallel with the capacitor;

[0051] set up If the pole is less than one-tenth of the switching angular frequency (2πfs), then:

[0052]

[0053] Right now

[0054] for Then we have:

[0055]

[0056] Right now

[0057] The beneficial effects of this invention are: 1. Existing active damping control methods that increase virtual resistance and adjust the input impedance of load converters are difficult to apply to non-centralized power distribution systems with large differences in parameters and impedance characteristics. This solution can be applied to scenarios with large differences in parameters and impedance characteristics.

[0058] 2. The existing method of adding active damping to the LC filter to achieve impedance matching between the front and rear stage converters and enhance the stability of the DC power distribution system increases hardware costs and system complexity. This solution is more cost-effective than this method.

[0059] 3. Existing methods that add active damping devices (bidirectional DC / DC converters, synchronous Buck circuits, etc.) between the front-end converter and the back-end converter require the introduction of additional circuits and control systems, which increases the complexity of the system and production costs. This solution is lower in cost and simpler to maintain compared to such solutions.

[0060] 4. Existing studies on the stability of DC distribution systems are all based on unipolar DC systems, not specifically designed for bipolar DC systems, and all neglect the influence of the line on the control of active damping. This scheme is not specifically designed for bipolar DC systems and takes into account the influence of the line on the control of active damping. Attached Figure Description

[0061] Figure 1 This is a flowchart illustrating an active damping control method for a bipolar DC power distribution system based on modulus decomposition.

[0062] Figure 2 This is a schematic diagram of the decoupling model of a bipolar DC line in the modulus component space.

[0063] Figure 3 This is a block diagram of the modulus damping control based on capacitor current.

[0064] Figure 4 This is a block diagram of the modulus damping control based on inductor current.

[0065] Figure 5 This is a circuit diagram for a bipolar DC power supply. Detailed Implementation

[0066] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings, but the scope of protection of the present invention is not limited to the following description.

[0067] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention; that is, the described embodiments are only a part of the embodiments of the invention, and not all of them. The components of the embodiments of the invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0068] Therefore, the following detailed description of the embodiments of the invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the invention without inventive effort are within the scope of protection of the invention. It should be noted that relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations.

[0069] Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0070] The features and performance of the present invention will be further described in detail below with reference to embodiments.

[0071] like Figure 1 As shown, the decoupling models of the bipolar DC converter, bipolar DC line, and DC load in the modulus component space are obtained respectively.

[0072] The decoupling models of the bipolar DC converter, the bipolar DC line, and the DC load in the modulus component space are integrated into a decoupling model of the DC distribution system in the modulus component space. Combined with the modulus transfer function of the bipolar DC system, active damping control is performed on the bipolar DC distribution system.

[0073] The decoupling model of the bipolar DC-DC converter in the modulus component space is as follows:

[0074] Voltage-current modulus transformation formula

[0075]

[0076] Its inverse change is:

[0077]

[0078] The decoupling model of the bipolar DC-DC converter in the modulus component space is obtained as follows:

[0079]

[0080] in:

[0081]

[0082] The decoupling model of the bipolar DC line in the modulus component space is as follows: using the modified polar mode transformation matrix

[0083]

[0084] Decouple the bipolar DC line and consider the effects of the line resistance, inductance, capacitance, and conductance matrix of the metal-return bipolar DC system:

[0085]

[0086]

[0087]

[0088]

[0089] The model of the bipolar DC circuit in the modulus component space is obtained as follows:

[0090]

[0091]

[0092]

[0093] The decoupling model of the DC load in the modulus component space is as follows:

[0094] The common-mode and differential-mode voltages satisfy:

[0095]

[0096] The parameters of the bipolar DC load in the modulus component space satisfy the following:

[0097]

[0098] The modulus transfer function of the bipolar DC system satisfies:

[0099]

[0100] When the load is balanced, considering the effects of line inductance and capacitance on system stability, the transfer function satisfies:

[0101]

[0102] The active damping control of the bipolar DC power distribution system includes:

[0103] If active damping based on inductor current is used, the common-mode output impedance expression of the input converter is:

[0104]

[0105] If active damping control is achieved using capacitor current, then the common-mode output impedance is:

[0106]

[0107] set up If the pole is less than one-tenth of the switching angular frequency (2πfs), then:

[0108]

[0109] Right now

[0110] for Then we have:

[0111]

[0112] Right now

[0113] The present invention will now be described in further detail with reference to the accompanying drawings.

[0114] The block diagram of the modulus damping control based on inductor current is as follows: Figure 3 Example. Modulus damping control based on capacitor current, such as... Figure 4 The diagram illustrates how proportional feedback of inductor and capacitor currents achieves active damping in a system. The two proportional feedback modes correspond to the damping methods of inductor series virtual resistance and capacitor parallel virtual resistance, respectively. In the modulus control of a bipolar DC system, to achieve active damping using either of these methods, the inductor and capacitor currents at the positive and negative terminals need to be modulated separately to obtain their common-mode and differential-mode component values ​​before proportional feedback. (Figure V...) 0ref V 1ref These are the control reference values ​​for common-mode voltage and differential-mode voltage, respectively. T and T0 1 The block diagrams represent the forward and inverse modulus transforms, respectively, and the block diagram of PWM represents the modulator, K. L0 and K L1 K represents the active damping feedback coefficients for the common-mode inductor current and the differential-mode inductor current, respectively; C0 and K C1 These represent the active damping feedback coefficients for the common-mode capacitor current and the differential-mode capacitor current, respectively.

[0115] (i) Derive the pole-mode transformation matrix of the metal-return bipolar DC distribution system to obtain the decoupling model of the bipolar DC line in the mode component space, such as... Figure 2 As shown;

[0116] Using the modified polar mode transformation matrix Decoupling the metal return bipolar DC line

[0117] The effects of line resistance, inductance, capacitance, and conductance matrix of the metal-return bipolar DC system were considered.

[0118]

[0119]

[0120]

[0121]

[0122] The model (mode impedance matrix) of the bipolar DC line in the mode component space satisfies:

[0123]

[0124]

[0125]

[0126] (ii) Combining the Norton equivalent model of constant power load, derive the decoupling model of DC load in the modulus component space.

[0127] The common-mode and differential-mode voltages satisfy:

[0128]

[0129] Furthermore, the parameters of the bipolar DC load in the modulus component space can be obtained to satisfy...

[0130]

[0131] (iii) Deriving the decoupling model of the bipolar DC-DC converter in the modulus component space

[0132] Draw a typical bipolar DC power supply circuit diagram. Figure 5 S1~S4 represent the switching transistor numbers of the positive and negative DC-DC converters, and D1~D4 represent the anti-parallel diode numbers of the positive and negative DC-DC converters; L p L n and C p C n These represent the positive and negative terminals of the filter inductor and filter capacitor, respectively. V sp V sn These represent the power supply voltages on the positive and negative DC sides, respectively. Lp i Ln These represent the current flowing through the positive and negative terminals of the inductor, respectively. p and v n These represent the output voltages i of the positive and negative converters, respectively. p i m i n Current representing the positive, neutral, and negative terminals, respectively.

[0133] Introduce the voltage-current modulus transformation formula as shown below.

[0134]

[0135] Its inverse change is:

[0136]

[0137] The state-space average model of the bipolar power source under modulus conditions satisfies:

[0138]

[0139] in:

[0140]

[0141] (iv) Deriving the modulus transfer function of a bipolar DC system

[0142]

[0143] When the load is balanced, considering the effects of line inductance and capacitance on system stability, the transfer function satisfies:

[0144]

[0145] (v) Operation control method for bipolar DC distribution system based on decoupling in modulus component space

[0146] Taking the common-mode output impedance as an example to analyze the damping effect of active damping, if active damping based on inductor current is used, the common-mode output impedance expression of the input converter can be expressed as:

[0147]

[0148] Consider using capacitor current to achieve active damping control. In this case, the common-mode output impedance is:

[0149]

[0150] The frequency range in which active damping operates should be much smaller than the switching frequency to avoid adverse effects caused by converter modulation and control delays. This is achieved by limiting... and The extreme point can satisfy this condition.

[0151] set up If the pole is less than one-tenth of the switching angular frequency (2πfs), then we have

[0152]

[0153] Right now

[0154] for Then we have:

[0155]

[0156] Right now

[0157] The above description is merely a preferred embodiment of the present invention. It should be understood that the present invention is not limited to the forms disclosed herein and should not be construed as excluding other embodiments. It can be used in various other combinations, modifications, and environments, and can be altered within the scope of the concept described herein through the above teachings or related technologies or knowledge. Modifications and variations made by those skilled in the art that do not depart from the spirit and scope of the present invention should be within the protection scope of the appended claims.

Claims

1. An active damping control method for a bipolar DC power distribution system based on modulus decomposition, characterized in that, Includes the following steps: Decoupling models of the bipolar DC converter, bipolar DC line, and DC load in the modulus component space are obtained respectively. The decoupling models of the bipolar DC converter, the bipolar DC line, and the DC load in the modulus space are integrated into a decoupling model of the DC distribution system in the modulus space. Combined with the modulus transfer function of the bipolar DC system, active damping control is performed on the bipolar DC distribution system. The decoupling model of the bipolar DC-DC converter in the modulus component space is as follows: Voltage-current modulus transformation formula Its inverse change is: The decoupling model of the bipolar DC-DC converter in the modulus component space is obtained as follows: in: , This refers to the conversion of the positive and negative inductor currents in the mode component space, namely the common-mode inductor current and the differential-mode inductor current. , This represents the conversion of the converter output voltage and power supply voltage in the modulus component space. , and , This refers to the conversion of the positive and negative line voltages in the modulus component, i.e., the line common-mode and differential-mode currents, and the current-limiting common-mode and differential-mode currents. , A represents the duty cycle of the positive and negative pole converter in the mode component space, namely the common-mode duty cycle and the differential-mode duty cycle. T B T This is the transpose of A and B; The decoupling model of the bipolar DC line in the modulus component space is as follows: using the modified polar mode transformation matrix Decouple the bipolar DC line and consider the effects of the line resistance, inductance, capacitance, and conductance matrix of the metal-return bipolar DC system: In the formula: R +-n 、L +-n 、C +-n 、G +-n These represent the line resistance, inductance, capacitance, and conductance matrices of a metal-return bipolar DC system. R + , R n , R - These represent the resistances of the positive, neutral, and negative lines in a bipolar DC return system, respectively. L + , L n 、L These represent the self-inductance of the positive, neutral, and negative lines of a bipolar DC return system, respectively. M +n 、M +- 、M -n These represent the mutual inductance between the positive terminal and the neutral line, the positive terminal and the negative terminal, and the negative terminal and the neutral line in a bipolar DC system with return current, respectively. C +i 、C ni 、C -i These represent the capacitances of the positive terminal to ground, the neutral terminal to ground, and the negative terminal to ground in a bipolar DC return system, respectively. C +n 、C +- 、C -n These represent the capacitances of the positive terminal to the neutral line, the positive terminal to the negative terminal, and the negative terminal to the neutral line in a bipolar DC system with return current, respectively. G +i 、G ni 、G -i These represent the conductances of the positive terminal to ground, the neutral terminal to ground, and the negative terminal to ground in a bipolar DC return system, respectively. G +n 、G +- 、G -n These represent the conductances of the positive terminal to the neutral line, the positive terminal to the negative terminal, and the negative terminal to the neutral line in a bipolar DC system with a return current, respectively. The model of the bipolar DC circuit in the modulus component space is obtained as follows: In the formula: R 01 、L 01 、C 01 This represents the modulo components of resistance, inductance, and capacitance in a bipolar DC circuit. The decoupling model of the DC load in the modulus component space is as follows: The common-mode and differential-mode voltages satisfy: In the formula: , These represent the common-mode and differential-mode voltages, respectively. , These represent the equivalent DC loads at the positive and negative terminals, respectively. V 0 represents the rated voltage; the parameters of the bipolar DC load in the modulus component space satisfy: In the formula: R pn Indicates a bipolar DC load; The modulus transfer function of the bipolar DC system satisfies: In the formula: , Let these represent the common-mode and differential-mode transfer functions of a bipolar DC system, respectively. , These represent common-mode and differential-mode small disturbances in a bipolar DC system, respectively. V s Represents the power supply voltage; when the load is balanced, considering the influence of line inductance and capacitance on system stability, the transfer function satisfies: In the formula: G v0d0 (s), G v1d1 (s) represent the common-mode and differential-mode transfer functions of the bipolar DC system under balanced load, respectively. R 0 and R 1. L 0 and L 1. C 0 and C 1 represents the common-mode and differential-mode components of the line resistance, inductance, and capacitance of a bipolar DC system, respectively. Y lp This represents the equivalent impedance of the positive load. The active damping control of the bipolar DC power distribution system includes: If active damping based on inductor current is used, the common-mode output impedance expression of the input converter is: R L0v This represents the virtual resistance value connected in series with the inductor; If active damping control is achieved using capacitor current, then the common-mode output impedance is: In the formula: R C0v This represents the virtual resistance connected in parallel with the capacitor; set up If the pole is less than one-tenth of the switching angular frequency (2πfs), then: Right now for Then we have: Right now .

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