Power grid phase angle estimation method and device, rectifier and control method and device thereof

Abstract

The application discloses a power grid phase angle estimation method and device, a rectifier and a control method and device thereof. The power grid phase angle estimation method comprises the following steps: acquiring three current sampling signals output by a current sampling circuit; determining a power grid current according to the three current sampling signals; determining an angular velocity of an actual power grid voltage vector and a current component on a gamma axis and a current component on a delta axis of the power grid current in a two-phase rotating coordinate system of an estimated gamma-delta axis according to the power grid current; acquiring a target voltage on the delta axis and a target voltage on the gamma axis used for space vector pulse width modulation; and determining a phase angle of the power grid voltage according to the current component on the gamma axis, the current component on the delta axis, the target voltage on the delta axis, the target voltage on the gamma axis and the angular velocity of the actual power grid voltage vector. The technical scheme can improve the acquisition accuracy of the phase angle of the power grid voltage.

Description

Technical Field

[0001] This invention relates to the field of rectification and detection technology, and in particular to a method and apparatus for estimating the phase angle of a power grid, a rectifier and its control method and apparatus. Background Technology

[0002] Currently, vector control of the front-end rectifier circuit requires obtaining the phase angle of the grid voltage vector. However, existing technology obtains the phase voltage of the three-phase AC voltage of the grid by setting the voltage sampling point on the grid side, and determines the phase angle of the grid voltage vector based on the phase voltage sampling results.

[0003] Because the voltage sampling point is located on the grid side, the voltage sampling line is relatively long. This leads to problems such as the voltage sampling line being prone to incorrect phase sequence connection, damage, and interference. Consequently, the determined phase angle error is relatively large, which is not conducive to the precise control of the rectifier circuit. Summary of the Invention

[0004] The main objective of this invention is to provide a method for estimating the phase angle of a power grid, which aims to solve the problem of large errors in obtaining the phase angle of the power grid voltage caused by the voltage sampling point being located on the power grid side.

[0005] To achieve the above objectives, the present invention proposes a grid phase angle estimation method applied to a rectifier. The rectifier includes a grid voltage input terminal, a rectifier circuit, and a current sampling circuit. The grid voltage input terminal is used to connect to the grid voltage. The three-phase input terminals of the rectifier circuit are each connected to the grid voltage input terminal via an AC inductor. The three-phase sampling terminals of the current sampling circuit are connected one-to-one with the three-phase input terminals of the rectifier circuit. The current sampling circuit is used to sample the three-phase current connected to the three-phase input terminals of the rectifier circuit and output three current sampling signals. The grid phase angle estimation method includes:

[0006] The three current sampling signals output by the current sampling circuit are obtained, and the grid current is determined based on the three current sampling signals.

[0007] Based on the grid current, determine the angular velocity of the actual grid voltage vector and the γ-axis and δ-axis current components of the grid current in the estimated γδ-axis two-phase rotating coordinate system; and,

[0008] The target voltages on the δ-axis and γ-axis are obtained for space vector pulse width modulation, and the phase angle of the grid voltage is determined based on the angular velocity of the γ-axis current component, the δ-axis current component, the δ-axis target voltage, the γ-axis target voltage, and the actual grid voltage vector.

[0009] Optionally, the phase angle of the grid voltage is determined based on the angular velocity of the γ-axis current component, the δ-axis current component, the δ-axis target voltage, the γ-axis target voltage, and the actual grid voltage vector, including:

[0010] Based on the calculation formulas for the angular velocity, δ-axis current component, γ-axis current component, γ-axis target voltage, and preset γ-axis component of the actual grid voltage vector, the γ-axis voltage component of the actual grid voltage vector on the γ-axis is determined; and based on the calculation formulas for the angular velocity, δ-axis current component, γ-axis current component, δ-axis target voltage, and preset δ-axis component of the actual grid voltage vector, the δ-axis voltage component of the actual grid voltage vector on the δ-axis is determined.

[0011] The phase angle of the grid voltage is determined based on the determined γ-axis voltage component and δ-axis voltage component.

[0012] Optionally, based on the angular velocity of the actual grid voltage vector, the delta-axis current component, the γ-axis current component, the γ-axis target voltage, and the preset γ-axis component calculation formula, the γ-axis voltage component of the actual grid voltage vector is determined, specifically as follows:

[0013] The first product value is obtained by multiplying the inductance value of the sampled inductor, the angular velocity of the actual grid voltage vector, and the δ-axis current component.

[0014] The second product value is obtained by multiplying the differential value of the sampling inductor's inductance and the sum of the line impedance of the AC inductor with the γ-axis current component.

[0015] The difference between the first product value and the second product value is summed with the target voltage along the γ-axis to obtain the first sum value;

[0016] The difference between the estimated grid voltage vector angular velocity and the actual grid voltage vector angular velocity is multiplied by the inductance value of the sampled inductor and the δ-axis current component to obtain the third product value.

[0017] The sum of the third product and the first sum is low-pass filtered to determine the γ-axis voltage component of the actual grid voltage vector on the γ-axis.

[0018] Optionally, based on the angular velocity of the actual grid voltage vector, the delta-axis current component, the γ-axis current component, the delta-axis target voltage, and the preset delta-axis component calculation formula, the delta-axis voltage component of the actual grid voltage vector is determined, specifically as follows:

[0019] The fourth product value is obtained by multiplying the inductance value of the sampled inductor, the angular velocity of the actual grid voltage vector, and the γ-axis current component.

[0020] The fifth product value is obtained by multiplying the sum of the differential value of the sampling inductor and the line impedance of the AC inductor with the δ-axis current component.

[0021] The difference between the fourth and fifth product values ​​is summed with the δ-axis target voltage to obtain the second sum.

[0022] The difference between the estimated grid voltage vector angular velocity and the actual grid voltage vector angular velocity is multiplied by the inductance value of the sampled inductor and the γ-axis current component to obtain the sixth product value.

[0023] The sum of the third product and the second sum is low-pass filtered to determine the δ-axis voltage component of the actual grid voltage vector.

[0024] Optionally, after running for a preset time, the angular velocity of the actual grid voltage vector is equal to the angular velocity of the estimated grid voltage vector.

[0025] Optionally, the step of determining the phase angle of the grid voltage based on the determined γ-axis voltage component and δ-axis voltage component includes:

[0026] Based on the determined γ-axis voltage component and δ-axis voltage component, determine the angle between the grid voltage vector and the γ-axis voltage component in the triangle formed by the γ-axis voltage component, the δ-axis voltage component and the actual grid voltage vector in the estimated γδ-axis two-phase rotating coordinate system.

[0027] Based on the included angle, determine the angular velocity of the grid voltage vector, and update the angular velocity of the actual grid voltage vector based on the determined angular velocity of the grid voltage vector.

[0028] The phase angle of the grid voltage is determined based on the angular velocity of the determined grid voltage vector.

[0029] Optionally, the included angle decreases as the running time increases until it decreases to 0°.

[0030] The present invention also proposes a rectifier control method, the rectifier control method comprising:

[0031] Obtain the grid current and the phase angle of the grid voltage determined by the grid voltage phase estimation method described above, and determine the d-axis current component and q-axis current component in the dp-axis two-phase rotating coordinate system based on the phase angle of the grid current and the grid voltage.

[0032] Obtain the given d-axis current, given q-axis current, and grid voltage in the dp-axis two-phase rotating coordinate system, and determine the target d-axis voltage and target q-axis voltage based on the given d-axis current, given q-axis current component, d-axis current component, q-axis voltage component, and q-axis voltage component.

[0033] Based on the determined target voltages of the d-axis and q-axis, the corresponding PWM signals are output to the rectifier circuit to control its operation.

[0034] Optionally, the steps for determining the d-axis target voltage and the q-axis target voltage based on the given d-axis current, the given q-axis current, the d-axis current component, the q-axis current component, the d-axis voltage component, and the q-axis voltage component are as follows:

[0035] The difference between the given d-axis current and the d-axis current component is adjusted by PI and then summed with the d-axis voltage component to obtain a third sum, which is then used as the target d-axis voltage.

[0036] The difference between the q-axis given current and the q-axis current component is adjusted by PI and then summed with the q-axis voltage component to obtain a fourth sum, which is then used as the q-axis target voltage.

[0037] Optionally, the rectifier control method further includes:

[0038] The d-axis current component is taken as the γ-axis current component of the grid current in the estimated γδ-axis two-phase rotating coordinate system, and the q-axis current component is taken as the δ-axis current component of the grid current in the estimated γδ-axis two-phase rotating coordinate system.

[0039] Optionally, the rectifier control method further includes:

[0040] The determined d-axis target voltage is taken as the γ-axis target voltage, and the determined q-axis target voltage is taken as the δ-axis target voltage.

[0041] Optionally, the rectifier control method further includes:

[0042] Obtain the γ-axis voltage component and δ-axis voltage component of the actual grid voltage vector in the estimated γδ-axis two-phase rotating coordinate system, and take the γ-axis voltage component as the d-axis voltage component and the δ-axis voltage component as the q-axis voltage component.

[0043] The present invention also proposes a power grid phase angle estimation device, the power grid phase angle estimation device comprising:

[0044] First memory;

[0045] The first processor; and,

[0046] A power grid phase angle estimation program stored in a first memory and executable on a first processor, wherein the first processor executes the power grid phase angle estimation program to implement the power grid phase angle estimation method as described above.

[0047] The present invention also proposes a rectifier control device, the rectifier control device comprising:

[0048] Second memory;

[0049] Second processor; and,

[0050] A rectifier control program stored in a second memory and executable on a second processor, wherein the second processor, when executing the rectifier control program, implements the rectifier control method as described above.

[0051] The present invention also proposes a rectifier, characterized in that the rectifier comprises:

[0052] The mains voltage input terminal is used to connect to the mains voltage.

[0053] A rectifier circuit, wherein the three-phase input terminals of the rectifier circuit are respectively connected to the mains voltage input terminal via an AC inductor; and,

[0054] A current sampling circuit, wherein the three-phase sampling terminals of the current sampling circuit are connected one-to-one with the three-phase input terminals of the rectifier circuit, the current sampling circuit is used to sample the three-phase current connected to the three-phase input terminals of the rectifier circuit, and output three current sampling signals; and,

[0055] As described above, the rectifier control device is connected to both the current sampling circuit and the rectifier circuit.

[0056] This invention's technical solution obtains three current sampling signals output by the current sampling circuit and uses an estimated γδ-axis two-phase rotating coordinate system to determine the phase angle of the grid voltage in real time. This eliminates the need for phase voltage sampling of the grid voltage. Since the current sampling point is located between the AC inductor and the rectifier circuit, its overall length is shorter than that of the voltage sampling line, reducing the risk of incorrect phase sequence connection and damage. Furthermore, it does not need to cross the AC inductor, thus the transmitted current sampling signal is not affected by AC inductor interference. This improves the accuracy of the phase angle determined by the inverter control device, thereby solving the problem of large errors caused by voltage sampling points located on the grid side and obtaining the grid voltage phase angle. In addition, the current sampling line does not need to be led out from the main control board, which simplifies and improves the appearance of the main control board wiring. Attached Figure Description

[0057] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the structures shown in these drawings without creative effort.

[0058] Figure 1 This is a schematic flowchart of an embodiment of the power grid phase angle estimation method of the present invention;

[0059] Figure 2 This is a schematic diagram showing the positions of various spatial vector coordinate systems in one embodiment of the power grid phase angle estimation method of the present invention;

[0060] Figure 3 This is a schematic diagram of the mathematical model of the power grid voltage phase angle estimation module in one embodiment of the power grid phase angle estimation method of the present invention;

[0061] Figure 4 for Figure 3 A schematic diagram of the mathematical model of the rectifier control device when the operating conditions of the embodiment shown are in steady state;

[0062] Figure 5 This is a flowchart illustrating the steps of an embodiment of the rectifier control method of the present invention;

[0063] Figure 6 This is a schematic diagram of another embodiment of the power grid phase angle estimation method of the present invention;

[0064] Figure 7 This is a structural schematic diagram of an embodiment of the subject matter of the present invention;

[0065] Figure 8 This is a schematic diagram of a circuit module of an embodiment of the rectifier of the present invention;

[0066] Figure 9 This is a schematic diagram of the circuit module of an existing rectifier.

[0067] Explanation of icon numbers:

[0068] label name label name 10 Grid voltage input terminal 101 First memory 20 rectifier circuit 102 First processor 30 Current sampling circuit 103 Second memory 40 rectifier control device 104 Second processor L AC inductor 105 Communication bus <![CDATA[U dc ]]> DC bus voltage

[0069] The realization of the objective, functional features and advantages of the present invention will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation

[0070] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the protection scope of the present utility model.

[0071] It should be noted that all directional indicators (such as up, down, left, right, front, back, etc.) in this utility model embodiment are only used to explain the relative positional relationship and movement of each component in a certain specific posture (as shown in the figure). If the specific posture changes, the directional indicator will also change accordingly.

[0072] In this utility model, unless otherwise explicitly specified and limited, the terms "connection," "fixing," etc., should be interpreted broadly. For example, "fixing" can mean a fixed connection, a detachable connection, or an integral part; it can mean a mechanical connection or an electrical connection; it can mean a direct connection or an indirect connection through an intermediate medium; it can mean the internal communication of two components or the interaction between two components, unless otherwise explicitly limited. Those skilled in the art can understand the specific meaning of the above terms in this utility model according to the specific circumstances.

[0073] Furthermore, in this utility model, descriptions involving "first," "second," etc., are for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined with "first" or "second" may explicitly or implicitly include at least one of that feature. Additionally, the technical solutions of the various embodiments can be combined with each other, but only on the basis of being achievable by those skilled in the art. When the combination of technical solutions is contradictory or impossible to implement, such a combination of technical solutions should be considered non-existent and not within the scope of protection claimed by this utility model.

[0074] This invention proposes a method for estimating the phase angle of a power grid, which can be applied to rectifiers.

[0075] Reference Figure 8 The rectifier may have a mains voltage input terminal, a rectifier circuit, and a current sampling circuit. The mains voltage input terminal can be connected to the mains power grid to receive the three-phase AC voltage provided by the grid. The rectifier circuit may have three-phase input terminals, each of which can be connected to the mains voltage input terminal via an AC inductor to receive the AC current generated by that phase AC voltage under the action of the AC inductor, i.e., the line current. The three-phase sampling terminals of the current sampling circuit can be connected between the AC inductor and the rectifier circuit, and are connected one-to-one with the three-phase input terminals of the rectifier circuit. The current sampling circuit can sample the three AC currents received by the three-phase input terminals of the rectifier circuit and output three corresponding current sampling signals.

[0076] It should be noted that when existing technologies determine the phase angle of the grid voltage vector by obtaining the phase voltage, please refer to [the relevant documentation / reference]. Figure 9One end of the voltage sampling line is connected to the mains voltage input terminal, and the other end needs to be connected to the main control board inside the equipment. This results in a relatively long overall length of the voltage sampling line, which not only makes it easy to connect the phase sequence incorrectly at either end, but also makes it prone to damage. Furthermore, since each voltage sampling line needs to cross an AC inductor, the voltage sampling signal transmitted on it is easily interfered with by the AC inductor. Incorrect connection, damage, or interference will all lead to a large error in the phase angle determined by the frequency converter control device, thus affecting the vector control accuracy of the rectifier circuit. In addition, since the voltage sampling line needs to be led out from the main control board, the wiring on the main control board is also less aesthetically pleasing and less indirect.

[0077] In response to the above issues, refer to Figure 1 In one embodiment, the power grid phase angle estimation method includes:

[0078] Step S100: Obtain the three current sampling signals output by the current sampling circuit, and determine the grid current based on the three current sampling signals.

[0079] In this embodiment, the execution entity of the power grid phase angle estimation method of the present invention can be an independent power grid phase angle estimation device, or it can also be a control device in a rectifier. The following description uses the "power grid phase angle estimation device" as an example to explain the power grid phase angle estimation method of the present invention. The power grid phase angle estimation device can obtain the AC current value corresponding to each current sampling signal by converting each current sampling signal from analog to digital and then analyzing and identifying it, thereby determining the magnitude of the three-phase current of the power grid, that is, the current value of the three-phase line current of the power grid.

[0080] Step S200: Based on the grid current, determine the angular velocity of the actual grid voltage vector and the γ-axis current component and δ-axis current component of the grid current in the estimated γδ-axis two-phase rotating coordinate system.

[0081] In this embodiment, the power grid phase angle estimation device can determine the three-phase line voltage of the power grid based on the determined three-phase current of the power grid, the inductance value of each AC inductor, and its line impedance. The power grid phase angle estimation device can extract the positive sequence component from the determined three-phase line voltage, and can transform the extracted positive sequence component to the αβ two-phase stationary coordinate system, and then transform the voltage component in the αβ two-phase stationary coordinate system to the dq two-phase rotating coordinate system to obtain the d-axis voltage component Ud on the d-axis and the q-axis voltage component Uq on the q-axis. Furthermore, the angular velocity of the actual power grid voltage vector can be obtained by performing PI adjustment on the d-axis voltage component Ud or the q-axis voltage component Uq on the q-axis.

[0082] The power grid phase angle estimation device can be pre-integrated with corresponding transformation algorithms to transform the three-phase current of the power grid to an estimated γδ-axis two-phase rotating coordinate system, thereby obtaining the γ-axis current component and the δ-axis current component of the three-phase current of the power grid. When the power grid phase angle estimation device or the rectifier control device is not in steady state, the power grid phase angle estimation device can obtain a preset γ-axis current component as the γ-axis current component of the power grid current in the estimated γδ-axis two-phase rotating coordinate system, and obtain a preset δ-axis current component as the δ-axis current component of the power grid current in the estimated γδ-axis two-phase rotating coordinate system. After entering steady state, the device can obtain the d-axis current component and q-axis current component obtained by sequentially performing Clark transformation and Park transformation on the power grid current, and use them as the γ-axis current component and δ-axis current component, respectively.

[0083] Step S300: Obtain the δ-axis target voltage and γ-axis target voltage for space vector pulse width modulation, and determine the phase angle of the grid voltage based on the γ-axis current component, δ-axis current component, δ-axis target voltage, γ-axis target voltage and the angular velocity of the actual grid voltage vector.

[0084] In this embodiment, the delta-axis target voltage and the γ-axis target voltage can be converted into multiple PWM signals after space vector pulse width modulation. These multiple PWM signals can be output to multiple switching devices in the rectified current, controlling the switching devices in the rectifier circuit to turn on or off sequentially, thereby enabling the rectified current to rectify the connected three-phase grid voltage into a DC bus voltage before output. The grid phase angle estimation device can pre-store corresponding component calculation formulas, such as preset γ-axis component calculation formulas and preset delta-axis component calculation formulas. By substituting the corresponding parameters from the delta-axis target voltage, γ-axis target voltage, γ-axis current component, delta-axis current component, and the angular velocity of the actual grid voltage vector into the corresponding component calculation formulas, the δ-axis voltage component and the γ-axis voltage component of the actual grid voltage vector on the delta-axis of the estimated γδ-axis two-phase rotating coordinate system can be obtained.

[0085] It should be noted that the estimated γδ-axis two-phase rotating coordinate system proposed in this invention can be considered to be between the dq-axis two-phase rotating coordinate system and the αβ-axis two-phase stationary coordinate system when the power grid phase angle estimation device or rectifier control device has not entered a steady state. That is, when the origins of the estimated γδ-axis two-phase rotating coordinate system, the dq-axis two-phase rotating coordinate system, and the αβ-axis two-phase stationary coordinate system are the same, there will be a first included angle Δθ between the γ-axis and the d-axis, δ-axis, and q-axis, and a second included angle θ between the γ-axis and the α-axis, δ-axis, and β-axis. r For details on the positional relationships of the three spatial vector coordinate systems, please refer to the appendix. Figure 2As shown. Since the d-axis voltage component is the active component of the grid voltage vector, and the q-axis voltage component is the reactive component of the grid voltage vector, and the phase angle of the grid voltage is actually the angle between the α-axis in the αβ two-phase stationary coordinate system and the d-axis in the dq-axis two-phase rotating coordinate system, the grid phase angle estimation device can determine the aforementioned first included angle based on the obtained δ-axis and γ-axis voltage components, and calculate the phase angle of the grid voltage based on the determined first included angle, thereby realizing the determination of the grid voltage phase angle. In this way, the inverter control device can use the determined phase angle to perform vector control on the rectifier circuit.

[0086] This invention's technical solution obtains three current sampling signals output by the current sampling circuit and uses an estimated γδ-axis two-phase rotating coordinate system to determine the phase angle of the grid voltage in real time. This eliminates the need for phase voltage sampling of the grid voltage. Since the current sampling point is located between the AC inductor and the rectifier circuit, its overall length is shorter than that of the voltage sampling line, reducing the risk of incorrect phase sequence connection and damage. Furthermore, it does not need to cross the AC inductor, thus the transmitted current sampling signal is not affected by AC inductor interference. This improves the accuracy of the phase angle determined by the inverter control device, thereby solving the problem of large errors caused by voltage sampling points located on the grid side and obtaining the grid voltage phase angle. In addition, the current sampling line does not need to be led out from the main control board, which simplifies and improves the appearance of the main control board wiring.

[0087] Reference Figures 1 to 4 In one embodiment, step S300, determining the phase angle of the grid voltage based on the γ-axis current component, the δ-axis current component, the δ-axis target voltage, the γ-axis target voltage, and the angular velocity of the actual grid voltage vector, includes:

[0088] Based on the calculation formulas for the angular velocity, δ-axis current component, γ-axis current component, γ-axis target voltage, and preset γ-axis component of the actual grid voltage vector, the γ-axis voltage component of the actual grid voltage vector on the γ-axis is determined; and based on the calculation formulas for the angular velocity, δ-axis current component, γ-axis current component, δ-axis target voltage, and preset δ-axis component of the actual grid voltage vector, the δ-axis voltage component of the actual grid voltage vector on the δ-axis is determined.

[0089] The phase angle of the grid voltage is determined based on the determined γ-axis voltage component and δ-axis voltage component.

[0090] In this embodiment, the formula for calculating the γ-axis voltage component can be:

[0091]

[0092] e is the amplitude of the grid voltage; Δθ is the first included angle; R is the line impedance of the AC inductor; L is the inductance of the AC inductor; ρ is the differential operator; iγ i represents the grid current component along the γ-axis. δ The current component of the grid current on the delta axis; u cγ The target voltage along the γ-axis; To estimate the angular velocity of the grid voltage vector: ω is the actual angular velocity of the grid voltage vector. The grid voltage amplitude, after uncontrolled rectified charging, can be calculated using the following formula: Calculations show that u dc The DC bus voltage is used; the line impedance of the AC inductor, the inductance value of the AC inductor, and the estimated grid voltage vector angular velocity can be obtained through pre-testing and stored in advance, and the estimated grid voltage vector angular velocity corresponds to the angular velocity when the grid voltage is normal. It can be understood that ecosΔθ is the γ-axis voltage component.

[0093] Therefore, the above calculation process is as follows: The inductance value L of the sampled inductor, the angular velocity ω of the actual grid voltage vector, and the delta-axis current component i are used. δ The three are multiplied, and the result is used as the first product value ωLi. δ The differential value ρL of the sampling inductor (i.e., Figure 3 The sum of Ls) and the line impedance R of the AC inductor is calculated to obtain the sum R+ρL. Then, the sum R+ρL is combined with the γ-axis current component i. γ Perform a product operation to obtain the second product value Ri. γ +ρLi γ Then multiply the first product value ωLi δ With the second product value Ri γ +ρLi γ The difference ωLi δ -(Ri γ +ρLi γ ) and the target voltage u along the γ axis cγ Perform sum calculations to obtain the first sum, ωLi. δ -(Ri γ +ρLi γ )+u cγ ; to estimate the grid voltage vector angular velocity The difference between the actual grid voltage vector angular velocity ω and the actual grid voltage vector angular velocity ω The inductance value L of the sampling inductor and the delta-axis current component i δ Perform a product operation to obtain the third product value. The third product value And the first sum ωLi δ -(Ri γ +ρLi γ )+u cγ The sum of Low-pass filtering is performed, and the processed value is determined as the γ-axis voltage component (ecosΔθ) of the actual grid voltage vector on the γ-axis.

[0094] The formula for calculating the delta-axis voltage component is as follows:

[0095]

[0096] The specific meanings of the parameters that are the same as those in the above formula for calculating the delta-axis voltage component can be found in the above formula for calculating the delta-axis voltage component, and will not be repeated here. The difference is that esinΔθ is the delta-axis voltage component.

[0097] Therefore, the above calculation process is as follows: The inductance value L of the sampled inductor, the angular velocity ω of the actual grid voltage vector, and the delta-axis current component i are used. γ The three are multiplied, and the result is used as the fourth product value ωLi. γ The differential value ρL of the sampling inductor is summed with the line impedance R of the AC inductor to obtain the sum R+ρL. Then, the sum R+ρL is compared with the delta-axis current component i. δ Perform a product operation to obtain the fifth product value Ri. δ +ρLi δ Then the target voltage u along the γ axis cγ With the fourth product value ωLi δ With the fifth product value Ri γ +ρLi γ The sum of ωLi δ +(Ri γ +ρLi γ Perform difference calculations to obtain the first difference, i.e., -[ωLi]. γ +(Ri δ +ρLi δ )]+u cδ ; to estimate the grid voltage vector angular velocity The difference between the actual grid voltage vector angular velocity ω and the actual grid voltage vector angular velocity ω The inductance value L of the sampling inductor and the γ-axis current component i γ Perform a product operation to obtain the sixth product value. The first difference -[ωLi γ +(Ri δ +ρLi δ )]+u cδ With the sixth product value The difference - [ωLi γ The +Riδ+ρLiδ+ucδ-(ω-ω)Liγ is subjected to low-pass filtering, and the processed value is determined as the δ-axis voltage component esinΔθ of the actual grid voltage vector on the δ axis.

[0098] Optionally, the step of determining the phase angle of the grid voltage based on the determined γ-axis voltage component and δ-axis voltage component includes:

[0099] Based on the determined γ-axis voltage component and δ-axis voltage component, determine the angle between the grid voltage vector and the γ-axis voltage component in the triangle formed by the γ-axis voltage component, the δ-axis voltage component and the actual grid voltage vector in the estimated γδ-axis two-phase rotating coordinate system.

[0100] It is understandable that the γ-axis voltage component, the δ-axis voltage component, and the actual grid voltage vector, in the estimated γδ-axis two-phase rotating coordinate system, can form a triangle with the actual grid voltage vector as the hypotenuse and the γ-axis and δ-axis voltage components as the two legs. In this triangle, the angle formed by the grid voltage vector and the γ-axis voltage component is the first included angle. The grid phase angle estimation device can obtain the first included angle by calculating the ratio of the δ-axis voltage component and the γ-axis voltage component, and then calculating the arctangent of the ratio. This arctangent value can be expressed by the formula... Where e δ Let e ​​be the δ-axis voltage component of the grid voltage vector on the δ-axis, which is also esinΔθ; γ Let γ be the γ-axis voltage component of the grid voltage vector on the γ-axis, also known as ecosΔθ.

[0101] Based on the included angle, determine the angular velocity of the grid voltage vector, and update the angular velocity of the actual grid voltage vector based on the determined angular velocity of the grid voltage vector.

[0102] The power grid phase angle estimation device can obtain the angular velocity of the power grid voltage vector by adjusting the angle of the first included angle using a PI converter. This angular velocity can then be used as the actual angular velocity of the power grid voltage vector in the next calculation. In the first calculation, a preset angular velocity can be used as the estimated angular velocity of the power grid voltage vector, thereby enabling continuous real-time determination of the power grid voltage phase angle.

[0103] This process repeats itself. When the operating condition reaches a steady state, the angular velocity of the actual grid voltage vector will equal the angular velocity of the estimated grid voltage vector. However, during the process of entering a steady state, the first included angle decreases with the increase of operating time until it decreases to 0°. It can be understood that when the first included angle decreases to 0, it indicates that the operating condition has entered a steady state. At this time, the γ-axis coincides with the d-axis, and the δ-axis coincides with the q-axis. In other words, after entering a steady state, the estimated γδ-axis two-phase rotating coordinate system coincides with the dq-axis two-phase stationary coordinate system.

[0104] The phase angle of the grid voltage is determined based on the angular velocity of the determined grid voltage vector.

[0105] The power grid phase angle estimation device can integrate the calculated angular velocity of the power grid voltage vector to obtain the phase angle of the power grid voltage.

[0106] It is understandable that the specific calculation of the grid voltage phase angle mentioned above can be regarded as being performed by a grid voltage estimation module, and the mathematical model corresponding to the grid voltage estimation module can be as follows: Figure 3 As shown.

[0107] The present invention also proposes a rectifier control method based on the grid voltage phase angle determined by the above-mentioned grid voltage phase estimation method. The specific steps of the grid phase angle estimation method are as described in the above embodiments. Since the rectifier control method adopts all the technical solutions of all the above embodiments, it has at least all the beneficial effects brought about by the technical solutions of the above embodiments, which will not be described in detail here.

[0108] Reference Figure 5 In one embodiment, the rectifier control method includes:

[0109] Step S400: Obtain the grid current and the phase angle of the grid voltage determined by the grid voltage phase estimation method described above, and determine the d-axis current component and q-axis current component in the dp-axis two-phase rotating coordinate system based on the grid current and the phase angle of the grid voltage.

[0110] In this embodiment, the rectifier control method can be executed by a rectifier control device. The rectifier control device can also determine the three-phase current of the power grid based on the three current sampling signals, and can sequentially perform Clark and Park transformations on the three-phase current of the power grid. The obtained phase angle can be used as a reference quantity during the Park transformation to obtain the d-axis current component and the q-axis current component of the three-phase current in the dq-axis two-phase rotating coordinate system, which are then used as the d-axis current component and the q-axis current component, respectively.

[0111] Step S500: Obtain the given current on the d-axis, the given current on the q-axis, and the grid voltage components on the d-axis and q-axis in the two-phase rotating coordinate system of the dp-axis. Based on the given current on the d-axis, the given current on the q-axis, the current components on the d-axis, the current components on the q-axis, the voltage components on the d-axis, and the voltage components on the q-axis, determine the target voltage on the d-axis and the target voltage on the q-axis.

[0112] The rectifier control device can obtain the bus reference voltage and the DC bus voltage output from the rectifier circuit, and use the difference between the two as the q-axis reference current after PI regulation. The rectifier control uses a pre-stored preset current component as the d-axis reference current.

[0113] The process by which the rectifier control device determines the target voltage on the d-axis and the target voltage on the q-axis can be described as follows:

[0114] The rectifier control device can calculate the difference between the d-axis given current and the d-axis current component, and perform PI adjustment on the calculated difference. Furthermore, it can sum the PI-adjusted difference with the d-axis voltage component to obtain a third sum, which can be used as the d-axis target voltage. Similarly, the rectifier control device can calculate the difference between the q-axis given current and the q-axis current component, and perform PI adjustment on the calculated difference. Furthermore, it can sum the PI-adjusted difference with the q-axis voltage component to obtain a fourth sum, which can be used as the q-axis target voltage.

[0115] Step S600: Based on the determined d-axis target voltage and q-axis target voltage, output the corresponding PWM signal to the rectifier circuit to control the operation of the rectifier circuit.

[0116] The rectifier control device can be pre-integrated with a space vector pulse width algorithm to perform space vector pulse width modulation on the determined d-axis target voltage and q-axis target voltage to obtain multiple PWM signals required for controlling multiple switching devices in the rectifier circuit, and output them one-to-one to the controlled terminals of multiple switching devices in the rectifier circuit, thereby realizing dual closed-loop vector control of the rectifier circuit.

[0117] Optionally, the rectifier control device can also control the d-axis current component I. d As the current grid current, I is the γ-axis current component in the estimated γδ-axis two-phase rotating coordinate system. γ and the q-axis current component I q As the current grid current, I is the δ-axis current component in the estimated γδ-axis two-phase rotating coordinate system. δ To perform step S200 in the power grid phase angle estimation method.

[0118] Optionally, the rectifier control device can also determine the target d-axis voltage U. cd Target voltage U along the γ-axis cγ and the determined q-axis target voltage U cq δ-axis target voltage U cδ To perform step 300 in the power grid phase angle estimation method.

[0119] Optionally, the rectifier control device can also acquire the γ-axis voltage component U of the actual grid voltage vector in the estimated γδ-axis two-phase rotating coordinate system. cγ and δ-axis voltage component U cδ and the γ-axis voltage component U cγ U, the voltage component along the d-axis dand the δ-axis voltage component U cδ U, the voltage component along the q-axis q To execute step S500 in the rectifier control method.

[0120] In this way, the estimated γδ-axis two-phase rotating coordinate system can be made to coincide with the dq-axis two-phase rotating coordinate system over time. The estimated γδ-axis two-phase rotating coordinate system can then be used to perform dual closed-loop vector control of the rectifier circuit. At this point, the overall mathematical model of the rectifier control device can be as follows: Figure 4 As shown.

[0121] The present invention also proposes a power grid phase angle estimation device that can be applied to rectifiers.

[0122] The rectifier may have a mains voltage input terminal, a rectifier circuit, and a current sampling circuit. The mains voltage input terminal can be connected to the mains power grid to receive the three-phase AC voltage provided by the grid. The rectifier circuit may have three-phase input terminals, each of which can be connected to the mains voltage input terminal via an AC inductor to receive the AC current generated by that phase AC voltage under the influence of the AC inductor, i.e., the line current. The three-phase sampling terminals of the current sampling circuit can be connected between the AC inductor and the rectifier circuit, and are connected one-to-one with the three-phase input terminals of the rectifier circuit. The current sampling circuit can sample the three AC currents received by the three-phase input terminals of the rectifier circuit and output three corresponding current sampling signals.

[0123] refer to Figure 6 In one embodiment, the power grid phase angle estimation device includes:

[0124] First memory 101;

[0125] First processor 102; and,

[0126] A power grid phase angle estimation program is stored in a first memory 101 and can run on a first processor 102. When the first processor 102 executes the power grid phase angle estimation program, it implements the power grid phase angle estimation method as described above.

[0127] In this embodiment, the specific steps of the power grid phase angle estimation method are the same as those in the above embodiments. Since this power grid phase angle estimation device adopts all the technical solutions of all the above embodiments, it has at least all the beneficial effects brought about by the technical solutions of the above embodiments, and will not be described in detail here.

[0128] The first memory 101 can be a high-speed RAM first memory 101, or a stable first memory 101 (non-volatile memory), such as a disk first memory 101. Optionally, the first memory 101 can also be a storage device independent of the aforementioned power grid phase angle estimation device. The first processor 102 can be a CPU. The first memory 101 and the first processor 102 are connected by a communication bus 105, which can be a UART bus or an I2C bus.

[0129] The present invention also proposes a rectifier control device that can be applied to rectifiers.

[0130] The rectifier may have a mains voltage input terminal, a rectifier circuit, and a current sampling circuit. The functions and connections of the mains voltage input terminal, the rectifier circuit, and the current sampling circuit can be referred to the embodiments of the above-mentioned mains phase angle estimation method or mains phase angle estimation device, and will not be elaborated here.

[0131] refer to Figure 7 In one embodiment, the rectifier control device includes:

[0132] Second memory 103;

[0133] Second processor 104; and,

[0134] A rectifier control program is stored in a second memory 103 and can run on a second processor 104. When the second processor 104 executes the rectifier control program, it implements the rectifier control method as described above.

[0135] In this embodiment, the specific steps of the rectifier control method are as described in the above embodiments. Since this rectifier control device adopts all the technical solutions of all the above embodiments, it has at least all the beneficial effects brought about by the technical solutions of the above embodiments, and will not be described in detail here.

[0136] In this embodiment, the second memory 103 can be a high-speed RAM second memory 103, or a stable second memory 103 (non-volatile memory), such as a disk second memory 103. Optionally, the second memory 103 can also be a storage device independent of the aforementioned rectifier control device. The second processor 104 can be a CPU. The second memory 103 and the second processor 104 are connected by a communication bus 105, which can be a UART bus or an I2C bus.

[0137] In another embodiment, the grid phase angle estimation device may be integrated into the rectifier control device.

[0138] The present invention also proposes a rectifier.

[0139] Reference Figure 8 The rectifier includes a grid voltage input terminal 10, a rectifier circuit 20, a current sampling circuit 30, and a rectifier control device 40. The specific structure of the rectifier control device 40 is as described in the above embodiments. Since this rectifier adopts all the technical solutions of all the above embodiments, it has at least all the beneficial effects brought about by the technical solutions of the above embodiments, which will not be described in detail here.

[0140] The grid voltage input terminal 10 is connected to the mains power grid for receiving the grid voltage provided by the mains power grid. The rectifier circuit 20 can be implemented using a three-phase bridge circuit constructed with multiple switching devices, such as MOSFETs and thyristors, which are not limited here. The rectifier circuit 20 can have three-phase input terminals and a DC output terminal. Each phase input terminal can be connected to the grid voltage input terminal 10 via an AC inductor L, and the DC output terminal can be connected to the inverter circuit via an intermediate bus capacitor. The three-phase sampling terminals of the current sampling circuit 30 are connected one-to-one with the three-phase input terminals of the rectifier circuit 20 to sample the AC current generated by the three-phase AC voltage under the action of the AC inductor, i.e., the line current. The current sampling circuit 30 is used to sample the three-phase AC current connected to the three-phase input terminals of the rectifier circuit 20 and outputs three corresponding current sampling signals. In this embodiment, the current sampling circuit 30 can be implemented using three current sensors. The rectifier control device 40 can be connected to the three output terminals of the current sampling circuit 30 and the controlled terminals of multiple switching devices in the rectifier circuit 20, respectively. The rectifier control device is used to implement the above-mentioned grid phase angle estimation method and the above-mentioned rectifier control method based on the received three-channel circuit sampling signals, so as to output corresponding multi-channel PWM signals to the controlled terminals of multiple switching devices in the rectifier circuit, thereby controlling the multiple switching devices in the rectifier circuit 20 to turn on or off according to a preset timing sequence, thereby rectifying the connected three-phase grid voltage into a DC bus voltage U. dc Then, the voltage is output to the inverter circuit via the intermediate bus capacitor, so that the inverter circuit can again convert the DC bus voltage into AC voltage and output it to AC drive components such as motors.

[0141] The above description is merely an optional embodiment of the present invention and does not limit the patent scope of the present invention. All equivalent structural transformations made using the contents of the present invention's specification and drawings under the inventive concept of the present invention, or direct / indirect applications in other related technical fields, are included within the patent protection scope of the present invention.

Claims

1. A method for estimating the phase angle of a power grid, applied to a rectifier, characterized in that, The rectifier includes a grid voltage input terminal for connecting to the grid voltage; a rectifier circuit, wherein the three-phase input terminals of the rectifier circuit are respectively connected to the grid voltage input terminal via an AC inductor; and a current sampling circuit, wherein the three-phase sampling terminals of the current sampling circuit are connected one-to-one with the three-phase input terminals of the rectifier circuit, and the current sampling circuit is used to sample the three-phase current connected to the three-phase input terminals of the rectifier circuit and output three current sampling signals. The power grid phase angle estimation method includes: The three current sampling signals output by the current sampling circuit are acquired, and the grid current is determined based on the three current sampling signals. Based on the grid current, determine the angular velocity of the actual grid voltage vector and the γ-axis and δ-axis current components of the grid current in the estimated γδ-axis two-phase rotating coordinate system; and, The delta-axis target voltage and γ-axis target voltage are obtained for space vector pulse width modulation, and the phase angle of the grid voltage is determined based on the γ-axis current component, delta-axis current component, delta-axis target voltage, γ-axis target voltage and the angular velocity of the actual grid voltage vector. Based on the calculation formulas for the angular velocity, δ-axis current component, γ-axis current component, γ-axis target voltage, and preset γ-axis component of the actual grid voltage vector, the γ-axis voltage component of the actual grid voltage vector on the γ-axis is determined; and based on the calculation formulas for the angular velocity, δ-axis current component, γ-axis current component, δ-axis target voltage, and preset δ-axis component of the actual grid voltage vector, the δ-axis voltage component of the actual grid voltage vector on the δ-axis is determined. Based on the determined γ-axis voltage component and δ-axis voltage component, determine the angle between the grid voltage vector and the γ-axis voltage component in the triangle formed by the γ-axis voltage component, the δ-axis voltage component and the actual grid voltage vector in the estimated γδ-axis two-phase rotating coordinate system. Based on the included angle, determine the angular velocity of the grid voltage vector, and update the angular velocity of the actual grid voltage vector based on the determined angular velocity of the grid voltage vector. Determine the phase angle of the grid voltage based on the angular velocity of the determined grid voltage vector; The included angle decreases as the running time increases until it decreases to 0°; Furthermore, the estimated γδ axis two-phase rotating coordinate system is considered to be between the dq axis two-phase rotating coordinate system and the αβ two-phase stationary coordinate system when the power grid phase angle estimation device or rectifier control device has not entered a steady state of operation.

2. The power grid phase angle estimation method as described in claim 1, characterized in that, Based on the angular velocity of the actual grid voltage vector, the δ-axis current component, the γ-axis current component, the γ-axis target voltage, and the preset γ-axis component calculation formula, the γ-axis voltage component of the actual grid voltage vector on the γ-axis is determined, specifically as follows: The first product value is obtained by multiplying the inductance value of the sampled inductor, the angular velocity of the actual grid voltage vector, and the δ-axis current component. The second product value is obtained by multiplying the differential value of the sampling inductor's inductance and the sum of the line impedance of the AC inductor with the γ-axis current component. The difference between the first product value and the second product value is summed with the target voltage along the γ-axis to obtain the first sum value; The difference between the estimated grid voltage vector angular velocity and the actual grid voltage vector angular velocity is multiplied by the inductance value of the sampled inductor and the δ-axis current component to obtain the third product value. The sum of the third product and the first sum is low-pass filtered to determine the γ-axis voltage component of the actual grid voltage vector on the γ-axis.

3. The power grid phase angle estimation method as described in claim 2, characterized in that, Based on the angular velocity of the actual grid voltage vector, the δ-axis current component, the γ-axis current component, the δ-axis target voltage, and the preset δ-axis component calculation formula, the δ-axis voltage component of the actual grid voltage vector is determined on the δ-axis, specifically as follows: The fourth product value is obtained by multiplying the inductance value of the sampled inductor, the angular velocity of the actual grid voltage vector, and the γ-axis current component. The fifth product value is obtained by multiplying the sum of the differential value of the sampling inductor and the line impedance of the AC inductor with the δ-axis current component. The difference between the fourth and fifth product values ​​is summed with the δ-axis target voltage to obtain the second sum. The difference between the estimated grid voltage vector angular velocity and the actual grid voltage vector angular velocity is multiplied by the inductance value of the sampled inductor and the γ-axis current component to obtain the sixth product value. The sum of the sixth product and the second sum is low-pass filtered to determine the δ-axis voltage component of the actual grid voltage vector.

4. The power grid phase angle estimation method as described in claim 2 or 3, characterized in that, After a preset running time, the angular velocity of the actual grid voltage vector is equal to the angular velocity of the estimated grid voltage vector.

5. A rectifier control method, characterized in that, The rectifier control method includes: Obtain the grid current and the phase angle of the grid voltage determined by the grid voltage phase estimation method as described in any one of claims 1-4, and determine the d-axis current component and q-axis current component in the dq-axis two-phase rotating coordinate system based on the grid current and the phase angle of the grid voltage. Obtain the given d-axis current, given q-axis current, and grid voltage in the d-axis two-phase rotating coordinate system, and determine the target d-axis voltage and target q-axis voltage based on the given d-axis current, given q-axis current component, d-axis current component, q-axis voltage component, and q-axis voltage component. Based on the determined target voltages of the d-axis and q-axis, the corresponding PWM signals are output to the rectifier circuit to control its operation.

6. The rectifier control method as described in claim 5, characterized in that, The steps to determine the target voltage on the d-axis and the target voltage on the q-axis based on the given current on the d-axis, the given current on the q-axis, the current component on the d-axis, the current component on the q-axis, the voltage component on the d-axis, and the voltage component on the q-axis are as follows: The difference between the given d-axis current and the d-axis current component is adjusted by PI and then summed with the d-axis voltage component to obtain a third sum, which is then used as the target d-axis voltage. The difference between the q-axis given current and the q-axis current component is adjusted by PI and then summed with the q-axis voltage component to obtain a fourth sum, which is then used as the q-axis target voltage.

7. The rectifier control method as described in claim 5, characterized in that, The rectifier control method further includes: The d-axis current component is taken as the γ-axis current component of the grid current in the estimated γδ-axis two-phase rotating coordinate system, and the q-axis current component is taken as the δ-axis current component of the grid current in the estimated γδ-axis two-phase rotating coordinate system.

8. The rectifier control method as described in claim 5, characterized in that, The rectifier control method further includes: The determined d-axis target voltage is taken as the γ-axis target voltage, and the determined q-axis target voltage is taken as the δ-axis target voltage.

9. The rectifier control method as described in claim 5, characterized in that, The rectifier control method further includes: Obtain the γ-axis voltage component and δ-axis voltage component of the actual grid voltage vector in the estimated γδ-axis two-phase rotating coordinate system, and take the γ-axis voltage component as the d-axis voltage component and the δ-axis voltage component as the q-axis voltage component.

10. A power grid phase angle estimation device, characterized in that, The power grid phase angle estimation device includes: First memory; The first processor; and, A power grid phase angle estimation program stored in a first memory and executable on a first processor, wherein the first processor, when executing the power grid phase angle estimation program, implements the power grid phase angle estimation method as described in any one of claims 1-4.

11. A rectifier control device, characterized in that, The rectifier control device includes: Second memory; Second processor; and, A rectifier control program stored in a second memory and executable on a second processor, wherein the second processor, when executing the rectifier control program, implements the rectifier control method as described in any one of claims 5-9.

12. A rectifier, characterized in that, The rectifier includes the rectifier control device as described in claim 11, wherein the rectifier control device is connected to the current sampling circuit and the rectifier circuit respectively.

Images