Method and device for detecting the output current of a wireless excitation system

Abstract

The application provides a sampling method and a sampling device for output current of a wireless excitation system. In the technical scheme provided by the application, a transformer in the wireless excitation system is equivalent to a combination of an excitation inductor and an ideal transformer, a current value of the excitation inductor is obtained, then a primary side current value of the ideal transformer is determined based on a bridge arm output current value of an inverter in a stator side part of the wireless excitation system and the current value of the equivalent excitation inductor, the input current of a rectifier in a rotor part of the wireless excitation system is determined according to the primary side current value and a transformation ratio of the transformer, and finally the output current of the excitation coefficient can be determined according to the input current of the rectifier. According to the technical scheme provided by the application, the accurate output current of the rotor part can be obtained based on the signals obtainable by the stator part of the wireless excitation system, so that the precise control of the output current of the wireless excitation system can be conveniently realized.

Description

Technical Field

[0001] This application relates to the field of electrical engineering, and more specifically, to a method and apparatus for detecting the output current of a wireless excitation system. Background Technology

[0002] Many countries around the world have announced timelines for electric vehicles to gradually replace traditional gasoline vehicles, and it is foreseeable that the electric vehicle industry will become a huge market in the future. Currently, electric vehicles mainly use permanent magnet synchronous motors. Due to the high cost of rare earth elements, in order to improve the average efficiency of the motor under different operating conditions and reduce dependence on rare earth elements, the excitation technology of using electromagnetic windings instead of high-speed rotating permanent magnets has become a focus for automakers, with huge market potential.

[0003] During operation, the output current and output power of a motor change with the operating conditions. For example, a large power needs to be provided instantaneously when an electric vehicle starts and accelerates, while the output current and power change less during normal driving. Therefore, the wireless excitation converter that supplies power to the motor rotor needs to quickly and accurately detect the output current and perform corresponding control, that is, to detect and control the motor rotor current.

[0004] The rotor and stator of the motor are separate and have no electrical connection. Moreover, the rotor is in an environment with high temperature, high vibration, and high centrifugal force. Therefore, how to accurately detect the output current of the wireless excitation converter is a technical problem that urgently needs to be solved. Summary of the Invention

[0005] This application provides a method and device for detecting the output current of a wireless excitation system, which can conveniently and accurately detect the output current of the wireless excitation converter, thereby enabling convenient and accurate control of the output current of the wireless excitation converter. For example, when the rotor is in an environment with high temperature, high vibration, and high centrifugal force, the technical solution of this application can also conveniently and accurately detect the rotor's output current.

[0006] In a first aspect, this application provides a method for detecting the output current of a wireless excitation system. The wireless excitation system includes a stator section and a rotor section. The stator section includes an inverter, a resonant inductor, and a primary winding. The rotor section includes a secondary winding and a rectifier. The primary winding and the secondary winding constitute a transformer.

[0007] The method includes: sampling the voltage between a first terminal and a second terminal in the stator section to obtain a first voltage, wherein the circuit between the first terminal and the second terminal includes the primary winding; sampling the voltage of the resonant inductor to obtain a second voltage; sampling the output current of the bridge arm of the inverter to obtain a first current; determining a third voltage of the magnetizing inductor of the transformer based on the first voltage and the second voltage; determining a second current of the magnetizing inductor based on the third voltage; determining the secondary output current of the transformer based on the first current and the second current; and determining the output current of the wireless excitation system based on the secondary output current.

[0008] In the sampling method of this application, the excitation voltage of the equivalent excitation inductance of the transformer (i.e., the third voltage) is simulated by sampling the voltage across the resonant inductor (i.e., the second voltage) and the circuit voltage of the primary winding of the transformer in the rotor section (i.e., the first voltage). Then, the current of the simulated excitation inductance (i.e., the second current) is determined by the simulated excitation voltage. The primary current of the ideal transformer is obtained by using the current node method based on the bridge arm current (i.e., the first current) and the excitation current. Then, the input current of the rectifier is rectified and filtered by using the relationship between the primary current of the ideal transformer, the input current of the rectifier, and the turns ratio of the transformer to obtain the output current of the wireless excitation system.

[0009] The sampling method of this application, without increasing the auxiliary winding of the transformer and without secondary feedback current, and without needing to sample the current of the equivalent excitation inductor, can simulate the output current of the wireless excitation system by sampling and calculating specific current and voltage signals of the primary side of the converter. This allows for convenient and accurate knowledge of the output current of the wireless excitation system, thereby enabling control of the output current of the wireless excitation system.

[0010] In conjunction with the first aspect, in a first possible implementation, sampling the voltage between the first and second terminals in the stator section to obtain the first voltage includes: sampling the primary voltage of the transformer to obtain the first voltage.

[0011] When determining the third voltage of the transformer's magnetizing inductance based on the first voltage and the second voltage, the third voltage satisfies the following relationship with the second voltage and the first voltage:

[0012]

[0013] Wherein, Um represents the third voltage, Ut represents the first voltage, Ur represents the second voltage, Lr represents the inductance value of the resonant inductor, Lpri represents the primary-side self-inductance parameter of the transformer, and k represents the coupling coefficient of the transformer.

[0014] In the sampling method of this application, the excitation voltage of the equivalent excitation inductance of the transformer is simulated by sampling the voltage across the resonant inductor (i.e., the second voltage) and the primary voltage of the transformer (i.e., the first voltage). Then, the current of the simulated excitation inductance is determined by the simulated excitation voltage. The primary current of the ideal transformer is obtained by using the current node method based on the bridge arm current (i.e., the first current) and the excitation current. Then, the input current of the rectifier is rectified and filtered by using the relationship between the primary current of the ideal transformer, the input current of the rectifier, and the transformer turns ratio to obtain the output current of the wireless excitation system.

[0015] The sampling method of this application, without increasing the auxiliary winding of the transformer and without secondary feedback current, and without needing to sample the current of the equivalent excitation inductor, can simulate the output current of the wireless excitation system by sampling and calculating specific current and voltage signals of the primary side of the converter. This allows for convenient and accurate knowledge of the output current of the wireless excitation system, thereby enabling control of the output current of the wireless excitation system.

[0016] For example, the voltage value of the equivalent magnetizing inductance can be calculated using a circuit capable of performing the functions of the above formula.

[0017] In conjunction with the first aspect, in the second possible implementation, sampling the voltage between the first and second terminals in the stator section to obtain the first voltage includes: sampling the output voltage of the inverter's bridge arm to obtain the first voltage;

[0018] When determining the third voltage of the transformer's magnetizing inductance based on the first voltage and the second voltage, the third voltage satisfies the following relationship with the second voltage and the first voltage:

[0019]

[0020] Wherein, Um represents the third voltage, Ub represents the first voltage, Ur represents the second voltage, Lr represents the inductance value of the resonant inductor, Lpri represents the primary self-inductance parameter of the transformer, and k represents the coupling coefficient of the transformer.

[0021] In the sampling method of this application, the excitation voltage of the equivalent magnetizing inductance of the transformer is simulated by sampling the voltage across the resonant inductor (i.e., the second voltage) and the output voltage of the inverter's bridge arm (i.e., the first voltage). Then, the current of the simulated magnetizing inductance (i.e., the third current) is determined by the simulated excitation voltage. The primary current of the ideal transformer is obtained based on the bridge arm current (i.e., the first current) and the excitation current using the current node method. Finally, the input current of the rectifier is rectified and filtered using the relationship between the primary current of the ideal transformer, the input current of the rectifier, and the transformer's turns ratio to obtain the output current of the wireless excitation system.

[0022] The sampling method of this application, without increasing the auxiliary winding of the transformer and without secondary feedback current, and without needing to sample the current of the equivalent excitation inductor, can simulate the output current of the wireless excitation system by sampling and calculating specific current and voltage signals of the primary side of the converter. This allows for convenient and accurate knowledge of the output current of the wireless excitation system, thereby enabling control of the output current of the wireless excitation system.

[0023] For example, the voltage value of the equivalent magnetizing inductance can be calculated using a circuit that can perform the function corresponding to the above formula.

[0024] In some possible implementations of the first aspect, when determining the second current of the magnetizing inductor based on the third voltage, the second current and the third voltage satisfy the following relationship:

[0025]

[0026] Wherein, Im represents the second current, Lpri represents the primary self-inductance parameter of the transformer, k represents the coupling coefficient of the transformer, and Um represents the third voltage.

[0027] In some possible implementations of the first aspect, when determining the secondary output current of the transformer based on the first current and the second current, the secondary output current satisfies the following relationship with the first current and the second current:

[0028]

[0029] Wherein, Is represents the secondary output current, Ib represents the first current, Im represents the second current, Np represents the number of turns in the primary winding of the transformer, and Ns represents the number of turns in the secondary winding.

[0030] In some possible implementations of the first aspect, when determining the output current of the wireless excitation system based on the secondary-side output current, the output current of the wireless excitation system and the secondary-side output current satisfy the following relationship:

[0031] Io = mean(|Is|)

[0032] Where Is represents the secondary output current, "|·|" represents the absolute value, mean(·) represents the average value, and Io represents the output current of the wireless excitation system.

[0033] Secondly, this application provides a device for detecting the output current of a wireless excitation system. The wireless excitation system includes a stator section and a rotor section. The stator section includes an inverter, a resonant capacitor, a resonant inductor, and a primary winding. The rotor section includes a secondary winding and a rectifier. The primary winding and the secondary winding constitute a transformer.

[0034] The sampling device includes: a first sampling circuit for sampling the voltage between a first terminal and a second terminal in the stator section to obtain a first voltage, wherein the circuit between the first terminal and the second terminal includes the primary winding; a second sampling circuit for sampling the voltage of the resonant inductor to obtain a second voltage; a third sampling circuit for sampling the output current of the inverter's bridge arm to obtain a first current; and a detection unit for: determining a third voltage of the excitation inductor of the transformer based on the first voltage and the second voltage, determining a second current of the excitation inductor based on the third voltage, determining the secondary output current of the transformer based on the first current and the second current, and determining the output current of the wireless excitation system based on the secondary output current.

[0035] In the sampling device of this application, the excitation voltage of the equivalent excitation inductance of the transformer is simulated by sampling the voltage across the resonant inductor (i.e., the second voltage) and the circuit voltage of the primary winding of the transformer in the rotor section (i.e., the first voltage). Then, the current of the simulated excitation inductance (i.e., the third current) is determined by the simulated excitation voltage. The primary current of the ideal transformer is obtained by using the current node method based on the bridge arm current (i.e., the first current) and the excitation current. Then, the input current of the rectifier is rectified and filtered by using the relationship between the primary current of the ideal transformer, the input current of the rectifier, and the transformer turns ratio to obtain the output current of the wireless excitation system.

[0036] The sampling device of this application, without increasing the auxiliary winding of the transformer and without secondary feedback current, and without needing to sample the current of the equivalent excitation inductor, can simulate the output current of the wireless excitation system by sampling and calculating specific current and voltage signals of the primary side of the converter. This allows for convenient and accurate knowledge of the output current of the wireless excitation system, thereby enabling control of the output current of the wireless excitation system.

[0037] In conjunction with the second aspect, in the first possible implementation, the first sampling unit is specifically used to: sample the primary voltage of the transformer to obtain the first voltage.

[0038] Specifically, the detection unit is used to perform addition and / or subtraction operations on the first voltage and the second voltage to obtain the third voltage, and the third voltage satisfies the following relationship with the first voltage and the second voltage:

[0039]

[0040] Wherein, Um represents the third voltage, Ut represents the first voltage, Ur represents the second voltage, Lr represents the inductance value of the resonant inductor, Lpri represents the primary-side self-inductance parameter of the transformer, and k represents the coupling coefficient of the transformer.

[0041] In the sampling device of this application, the excitation voltage of the equivalent excitation inductance of the transformer is simulated by sampling the voltage across the resonant inductor (i.e., the second voltage) and the primary voltage of the transformer (i.e., the first voltage). Then, the current of the simulated excitation inductance (i.e., the third current) is determined by the simulated excitation voltage. The primary current of the ideal transformer is obtained based on the bridge arm current (i.e., the first current) and the excitation current using the current node method. Then, the input current of the rectifier is rectified and filtered using the relationship between the primary current of the ideal transformer, the input current of the rectifier, and the transformer turns ratio to obtain the output current of the wireless excitation system.

[0042] The sampling device of this application, without increasing the auxiliary winding of the transformer and without secondary feedback current, and without needing to sample the current of the equivalent excitation inductor, can simulate the output current of the wireless excitation system by sampling and calculating specific current and voltage signals of the primary side of the converter. This allows for convenient and accurate knowledge of the output current of the wireless excitation system, thereby enabling control of the output current of the wireless excitation system.

[0043] In conjunction with the second aspect, in the second possible implementation, the first sampling unit is specifically used to: sample the output voltage of the bridge arm of the inverter to obtain the first voltage.

[0044] Specifically, the detection unit is used to perform addition and / or subtraction operations on the first voltage and the second voltage to obtain the third voltage, and the third voltage satisfies the following relationship with the second voltage and the first voltage:

[0045]

[0046] Wherein, Um represents the third voltage, Ub represents the first voltage, Ur represents the second voltage, Lr represents the inductance value of the resonant inductor, Lpri represents the primary self-inductance parameter of the transformer, and k represents the coupling coefficient of the transformer.

[0047] In the sampling device of this application, the excitation voltage of the equivalent excitation inductance of the transformer is simulated by sampling the voltage across the resonant inductor (i.e., the second voltage) and the output voltage of the inverter bridge arm (i.e., the first voltage). Then, the current of the simulated excitation inductance is determined by the simulated excitation voltage. The primary current of the ideal transformer is obtained based on the bridge arm current (i.e., the first current) and the excitation current using the current node method. Then, the input current of the rectifier is rectified and filtered by using the relationship between the primary current of the ideal transformer, the input current of the rectifier, and the transformer turns ratio to obtain the output current of the wireless excitation system.

[0048] The sampling device of this application, without increasing the auxiliary winding of the transformer and without secondary feedback current, and without needing to sample the current of the equivalent excitation inductor, can simulate the output current of the wireless excitation system by sampling and calculating specific current and voltage signals of the primary side of the converter. This allows for convenient and accurate knowledge of the output current of the wireless excitation system, thereby enabling control of the output current of the wireless excitation system.

[0049] In some possible implementations of the second aspect, the detection unit is specifically used to perform an integral operation on the third voltage to obtain the second current, wherein the second current and the third voltage satisfy the following relationship:

[0050]

[0051] Wherein, Im represents the second current, Lpri represents the primary self-inductance parameter of the transformer, k represents the coupling coefficient of the transformer, and Um represents the third voltage.

[0052] In some possible implementations of the second aspect, the detection unit is specifically used to perform addition and / or subtraction operations on the first current and the second current to obtain the secondary output current, wherein the secondary output current satisfies the following relationship with the first current and the second current:

[0053]

[0054] Wherein, Is represents the secondary output current, Ib represents the first current, Im represents the second current, Np represents the number of turns in the primary winding of the transformer, and Ns represents the number of turns in the secondary winding.

[0055] In some possible implementations of the second aspect, the detection unit is specifically used to rectify and low-pass filter the secondary-side output current sequentially to obtain the output current of the wireless excitation system, wherein the secondary-side output current and the output current of the wireless excitation system satisfy the following relationship:

[0056] Io = mean(|Is|)

[0057] Where Is represents the secondary output current, "|·|" represents the absolute value, mean(·) represents the average value, and Io represents the output current of the wireless excitation system.

[0058] Thirdly, this application provides a wireless excitation system, characterized in that the wireless excitation system includes the sampling device described in the second aspect or any of its implementations. Attached Figure Description

[0059] Figure 1 This is a schematic structural diagram of a wireless excitation system according to an embodiment of this application.

[0060] Figure 2 This is a schematic structural diagram of a wireless excitation system according to another embodiment of this application.

[0061] Figure 3 This is a schematic diagram showing the shapes of the primary and secondary currents of a transformer according to an embodiment of this application.

[0062] Figure 4 This is a schematic structural diagram of a sampling device for the output current of a wireless excitation system according to an embodiment of this application.

[0063] Figure 5 This is a schematic flowchart illustrating a sampling method for the output current of a wireless excitation system according to an embodiment of this application.

[0064] Figure 6 This is a schematic structural diagram of a sampling device for the output current of a wireless excitation system according to another embodiment of this application.

[0065] Figure 7 This is a schematic flowchart illustrating a sampling method for the output current of a wireless excitation system according to another embodiment of this application. Detailed Implementation

[0066] The technical solution of this application can be applied to wireless excitation systems, for example, to wireless excitation systems that achieve excitation through LLC resonant converters.

[0067] Figure 1 This is a schematic structural diagram of a wireless excitation system according to an embodiment of this application. Figure 1As shown, the wireless excitation system consists of a stator and a rotor, which are separate and have no electrical connection. The stator includes a DC power supply, an inverter, a resonant network, and a primary winding Lp. The rotor includes a secondary winding Ls, a rectifier, an output capacitor Co, and a load. The primary winding of the stator and the secondary winding of the rotor form a rotary transformer, which couples the stator and rotor. The rotor supplies power to the load.

[0068] In the embodiments of this application, the stator part of the wireless excitation system is also referred to as the stator side, and the rotor part is also referred to as the rotor side.

[0069] In wireless excitation scenarios, one example of a load is a motor winding. The transformer's turns ratio is denoted as N:1, and can also be simply referred to as the turns ratio.

[0070] As an example, such as Figure 2 As shown, the resonant network in the wireless excitation system can be an LLC resonant network, which can be composed of a resonant inductor Lr and a resonant capacitor Cr (the LLC can also include the excitation inductance Lm of the transformer). Figure 2 (The inductor is shown by the dashed line in the diagram). The inverter can be composed of switching transistors Q1-Q4, and the rectifier can be composed of diodes D1-D4.

[0071] Figure 2 In the wireless excitation system shown, the power supply, inverter, resonant inductor Lr, resonant capacitor Cr, and primary winding Lp of the transformer can also be referred to as the primary side of the wireless excitation system, while the secondary winding Ls of the transformer, rectifier, output filter capacitor Co, and load can be referred to as the secondary side.

[0072] In wireless excitation systems, it is typically necessary to detect the output current of the rotor section in order to control its magnitude and thus better provide the load with the required current. In the embodiments of this application, the output current of the rotor section is the output current of the wireless excitation system.

[0073] However, in wireless excitation scenarios, the stator and rotor sections are independent, and the rotor section is typically exposed to high temperature, high vibration, and high centrifugal force environments. Therefore, it is difficult to detect the output current by sampling the output current in the rotor section. To address this technical problem, this application proposes a technical solution that simulates and detects the output current of the rotor section in the stator section.

[0074] by Figure 2Taking the wireless excitation system shown as an example, in order to detect the magnitude of the output current of the secondary side from the primary side, it is usually assumed that the inverter's bridge arm current Ib is equal to the transformer's primary side current Ip (i.e., Ib = Ip), the rectifier's input current Is is proportional to the output current Io (the magnitude of the ratio depends on the size of the filter capacitor, let Io = β·Is), and the transformer's primary side current Ip and secondary side current Is are related to the transformation ratio N (let N = Is / Ip). Based on the above assumptions, the secondary side current Is can be calculated from the primary side current Ip, and thus the output current Io can be obtained (Io = β·N·Ip or Io = β·N·Ib).

[0075] Although a transformer has only one primary winding Lp, it actually has an equivalent magnetizing inductance Lm during operation, such as... Figure 2 The inductance is represented by a dashed line. Moreover, the excitation current Im in the magnetizing inductance varies with the voltage across the primary winding Lp. Therefore, the bridge arm current Ib is not actually equal to the primary current Ip of the transformer. In particular, when the load is a motor-type load, the excitation current Im varies greatly under different load conditions.

[0076] Figure 3 This is a schematic diagram of the simulated waveforms of the primary current Ip and secondary current Is of the transformer. Figure 3 It can be seen that Ip and Ib are not a simple ratio relationship.

[0077] Therefore, the output current cannot be simply determined by the turns ratio of the primary and secondary sides of the transformer. Instead, the influence of the excitation current Im needs to be considered to obtain a more accurate output current.

[0078] However, actual transformers do not have a magnetizing inductance branch, that is... Figure 2 The branches indicated by dashed lines cannot be directly sampled to obtain the excitation current Im. To address this technical problem, this application proposes a method that, without adding auxiliary windings to the transformer, sampling the excitation current, or obtaining secondary feedback current, indirectly simulates the output current of the rotor by sampling and calculating specific voltage and current signals in the stator section. This allows for the detection of the rotor's output current and, consequently, control of the rotor's output current.

[0079] In the detection method proposed in this application, the voltage between two endpoints in the stator section is sampled to obtain a first voltage, and these two endpoints are referred to as the first endpoint and the second endpoint, respectively. The circuit between the first endpoint and the second endpoint includes the primary winding. The voltage across the resonant inductor is sampled to obtain a second voltage. The output current of the inverter's bridge arm is sampled to obtain a first current. A third voltage of the transformer's magnetizing inductor is simulated based on the first voltage and the second voltage. A second current of the magnetizing inductor is simulated based on the third voltage. The secondary output current of the transformer is simulated based on the first current and the second current. The output current of the wireless excitation system is simulated based on the secondary output current.

[0080] Accordingly, the detection device proposed in this application includes a first sampling circuit, a second sampling circuit, a third sampling circuit, and a detection unit. The first sampling circuit samples the voltage between the first and second terminals of the stator section to obtain a first voltage; the circuit between the first and second terminals includes a primary winding. The second sampling circuit samples the voltage across the resonant inductor to obtain a second voltage. The third sampling circuit samples the output current of the inverter's bridge arm to obtain a first current. The detection unit is used to: simulate the third voltage of the transformer's magnetizing inductor based on the first and second voltages; simulate the second current of the magnetizing inductor based on the third voltage; simulate the secondary output current of the transformer based on the first and second currents; and simulate the output current of the wireless excitation system based on the secondary output current.

[0081] In one possible implementation of the detection method and detection device of this application, the aforementioned first voltage can be the primary output voltage of a transformer; in another implementation, the aforementioned first voltage can be the bridge arm output voltage of an inverter.

[0082] When the first voltage is the primary output voltage of the transformer, the third voltage can be simulated based on the first and second voltages using a circuit capable of performing the mathematical operations in formula (1); the second current can be simulated based on the third voltage using a circuit capable of performing the mathematical operations in formula (2); the secondary output current of the transformer can be simulated based on the first and second currents using a circuit capable of performing the mathematical operations in formula (3); and the output current of the wireless excitation system can be simulated based on the secondary output current of the transformer using a circuit capable of performing the mathematical operations in formula (4).

[0083] When the first voltage is the output voltage of the inverter's bridge arm, the circuit that can perform the mathematical operations in formula (5) can be used to simulate the third voltage based on the first and second voltages; the circuit that can perform the mathematical operations in formula (2) can be used to simulate the second current based on the third voltage; the circuit that can perform the mathematical operations in formula (3) can be used to simulate the secondary output current of the transformer based on the first and second currents; and the circuit that can perform the mathematical operations in formula (4) can be used to simulate the output current of the wireless excitation system based on the secondary output current of the transformer.

[0084] The following example uses the primary output voltage of the transformer as the first voltage, combined with... Figure 4 and Figure 5 This paper presents an example of detecting the output current of a wireless excitation system.

[0085] Figure 4 This is a schematic structural diagram of an output current detection device for a wireless excitation system according to an embodiment of this application.

[0086] The wireless excitation system includes a stator side and a rotor side. The stator side includes a power supply, an inverter, a resonant inductor Cr, a resonant capacitor Lr, and a winding with Np turns. The rotor side includes a winding with Ns turns, a rectifier, an output capacitor Co, and a load R. The winding with Np turns and the winding with Ns turns constitute a transformer. The winding with Np turns is the primary winding of the transformer, and the winding with Ns turns is the secondary winding of the transformer.

[0087] Figure 4 In the wireless excitation system shown, the transformer is represented by its equivalent decoupling model. The equivalent decoupling model of the transformer includes an inductance of (1-k)*Lpri, an inductance of k*Lpri, and an ideal transformer. The number of turns in the primary winding of the ideal transformer is Np, and the number of turns of the ideal transformer is Ns. Here, k is the coupling coefficient of the transformer, Lpri represents the primary self-inductance of the transformer, the inductance of (1-k)*Lpri is called the leakage inductance, and the inductance of k*Lpri is called the magnetizing inductance.

[0088] like Figure 4 As shown, the detection device includes a first sampling circuit, a second sampling circuit, a third sampling circuit, and a detection unit.

[0089] The first sampling circuit is for sampling the resonant voltage Ur of the resonant inductor Lr; the second sampling circuit is for sampling the primary input voltage Ut of the transformer; and the third sampling circuit is for sampling the bridge arm current Ib of the inverter.

[0090] The detection unit is used to perform addition, subtraction, integration, multiplication, absolute value taking, and average value taking on all sampled signals to generate an output current sampling signal Io that is equivalent to the output current of the wireless excitation system.

[0091] Among them, the absolute value operation performed by the detection unit is an equivalent mathematical description of the current signal rectification performed by the detection unit; the average value operation performed by the detection unit is an equivalent data description of the current signal low-pass filtering performed by the detection unit.

[0092] use Figure 4 When the detection device shown detects the output current of the wireless excitation system, it can obtain the inductance Lr of the resonant inductor, the coupling coefficient k of the transformer, and the self-inductance Lpri of the primary winding, and calculate the ratio between the resonant inductance and the leakage inductance of the transformer. Alternatively, it can perform parameter tests on the actual resonant inductor and transformer to obtain the inductance Lr of the resonant inductor, the coupling coefficient k of the transformer, and the self-inductance Lpri of the primary winding, and calculate the ratio between the resonant inductance and the leakage inductance of the transformer. The device also samples the resonant voltage Ur of the resonant inductor through the first sampling circuit and the second sampling circuit... The circuit samples the primary input voltage Ut of the transformer and calculates the voltage Um of the simulated magnetizing inductor based on these two voltages. By integrating the voltage of the simulated magnetizing inductor, the current Im of the simulated magnetizing inductor is obtained. The bridge arm current Ib is sampled by the third sampling circuit, and the secondary output current Is of the transformer is obtained by subtracting the magnetizing current Im from the bridge arm current and then multiplying it by the turns ratio. The secondary output current of the transformer is rectified to obtain Iss. After low-pass filtering of Iss, a current signal Io proportional to the output current of the wireless excitation system is obtained.

[0093] As an example, using such Figure 4 The process of the detection device shown detecting the output current of the wireless excitation system is as follows: Figure 5 As shown.

[0094] First, relevant parameters of the transformer and resonant inductor can be measured to obtain the coupling coefficient k of the transformer, the primary self-inductance parameter Lpri of the transformer, and the inductance Lr of the resonant inductor (not shown in the figure). Then, the resonant voltage Urs of the resonant inductor Lr, the primary input voltage Ut of the transformer, and the bridge arm current Ib of the inverter are sampled by the first sampling circuit, the second sampling circuit, and the third sampling circuit, respectively.

[0095] Next, in the detection unit, according to the relationship in formula (1), the resonant voltage of the resonant inductor and the primary input voltage of the transformer are added together to obtain the simulated excitation voltage Um of the transformer. The excitation voltage is the voltage across the equivalent excitation inductor.

[0096]

[0097] Wherein, Um represents the third voltage, Ut represents the first voltage, Ur represents the second voltage, Lr represents the inductance value of the resonant inductor, Lpri represents the primary-side self-inductance parameter of the transformer, and k represents the coupling coefficient of the transformer.

[0098] In the detection unit, the excitation voltage is integrated according to the relationship in formula (2) to obtain the simulated excitation current Im, which is the current of the equivalent excitation inductor:

[0099]

[0100] Wherein, Im represents the second current, Lpri represents the primary self-inductance parameter of the transformer, k represents the coupling coefficient of the transformer, and Um represents the third voltage.

[0101] In the detection unit, the excitation voltage is subtracted according to the relationship in formula (3) to obtain the primary output current Is of the transformer:

[0102]

[0103] Wherein, Is represents the secondary output current, Ib represents the first current, Im represents the second current, Np represents the number of turns in the primary winding of the transformer, and Ns represents the number of turns in the secondary winding.

[0104] In the detection unit, based on the relationship in formula (4), the secondary output current is subjected to absolute value calculation and low-pass filtering to obtain a current signal I that is proportional to the output current of the wireless excitation system. o :

[0105] Io = mean(|Is|) (4)

[0106] Where Is represents the secondary output current, "|·|" represents the absolute value, mean(·) represents the average value, and Io represents the output current of the wireless excitation system.

[0107] Understandable, Figure 4 and Figure 5 The various calculations used in the apparatus and method shown to derive the output current of the wireless excitation system based on the primary input voltage, resonant voltage, and bridge arm current are merely examples and should not be construed as limiting the method and apparatus of this embodiment.

[0108] In this embodiment, the detection device and method, when the rotor is in an environment of high temperature, high vibration, and high centrifugal force, and it is inconvenient to sample the output current or there is no output feedback, can obtain an output current sampling signal equivalent to the output current of the wireless excitation system by sampling and calculating the voltage and current signals on the stator side.

[0109] The following example uses the first voltage as the bridge arm voltage of the inverter, combined with... Figure 6 and Figure 7 This application presents another example of detecting the output current of a wireless excitation system. Figure 6 This is an exemplary structural diagram of a detection device according to another embodiment of this application.

[0110] The wireless excitation system includes a stator side and a rotor side. The stator side includes a power supply, an inverter, a resonant inductor Cr, a resonant capacitor Lr, and a winding with Np turns. The rotor side includes a winding with Ns turns, a rectifier, an output capacitor Co, and a load R. The winding with Np turns and the winding with Ns turns constitute a transformer. The winding with Np turns is the primary winding of the transformer, and the winding with Ns turns is the secondary winding of the transformer.

[0111] Figure 6 In the wireless excitation system shown, the transformer is represented by its equivalent decoupling model. The equivalent decoupling model of the transformer includes an inductance of (1-k)*Lpri, an inductance of k*Lpri, and an ideal transformer. The number of turns in the primary winding of the ideal transformer is Np, and the number of turns of the ideal transformer is Ns. Here, k is the coupling coefficient of the transformer, Lpri represents the primary self-inductance of the transformer, the inductance of (1-k)*Lpri is called the leakage inductance, and the inductance of k*Lpri is called the magnetizing inductance.

[0112] like Figure 6 As shown, the detection device includes a first sampling circuit, a second sampling circuit, a third sampling circuit, and a detection unit.

[0113] The first sampling circuit is for sampling the resonant voltage Ur of the resonant inductor Lr; the second sampling circuit is for sampling the bridge arm voltage Ub of the inverter; and the third sampling circuit is for sampling the bridge arm current Ib of the inverter.

[0114] The detection unit is used to perform addition, subtraction, integration, multiplication, absolute value taking, and average value taking on all sampled signals to generate an output current sampling signal Io that is equivalent to the output current of the wireless excitation system.

[0115] Among them, the absolute value operation performed by the detection unit is an equivalent mathematical description of the current signal rectification performed by the detection unit; the average value operation performed by the detection unit is an equivalent data description of the current signal low-pass filtering performed by the detection unit.

[0116] use Figure 6 When the detection device shown detects the output current of the wireless excitation system, it can obtain the inductance Lr of the resonant inductor, the coupling coefficient k of the transformer, and the self-inductance Lpri of the primary winding, and calculate the ratio between the resonant inductance and the leakage inductance of the transformer. Alternatively, it can perform parameter tests on the actual resonant inductor and transformer to obtain the inductance Lr of the resonant inductor, the coupling coefficient k of the transformer, and the self-inductance Lpri of the primary winding, and calculate the ratio between the resonant inductance and the leakage inductance of the transformer. The device also samples the resonant voltage Ur of the resonant inductor through the first sampling circuit and the second sampling circuit... The sampling circuit samples the inverter's bridge arm voltage Ub and calculates the simulated magnetizing inductor voltage Um based on these two voltages. By integrating the simulated magnetizing inductor voltage, the simulated magnetizing inductor current Im is obtained. The bridge arm current Ib is sampled by the third sampling circuit, and the magnetizing current Im is subtracted from the bridge arm current and then multiplied by the turns ratio to obtain the transformer's secondary output current Is. The transformer's secondary output current is rectified to obtain Iss. After low-pass filtering Iss, a current signal Io proportional to the output current of the wireless excitation system is obtained.

[0117] As an example, using such Figure 6 The process of the detection device shown detecting the output current of the wireless excitation system is as follows: Figure 7 As shown.

[0118] First, relevant parameters of the transformer and resonant inductor can be measured to obtain the coupling coefficient k of the transformer, the primary self-inductance parameter Lpri of the transformer, and the inductance Lr of the resonant inductor (not shown in the figure). Then, the resonant voltage Ur of the resonant inductor Lr, the bridge arm voltage Ub of the inverter, and the bridge arm current Ib of the inverter are sampled by the first sampling circuit, the second sampling circuit, and the third sampling circuit, respectively.

[0119] Next, in the detection unit, according to the relationship in formula (6), the resonant voltage of the resonant inductor and the bridge arm voltage of the inverter are added together to obtain the transformer-simulated excitation voltage Um. The excitation voltage is the voltage across the equivalent excitation inductor.

[0120]

[0121] Wherein, Um represents the third voltage, Ut represents the first voltage, Ur represents the second voltage, Lr represents the inductance value of the resonant inductor, Lpri represents the primary-side self-inductance parameter of the transformer, and k represents the coupling coefficient of the transformer.

[0122] In the detection unit, the excitation voltage is integrated according to the relationship in formula (2) to obtain the simulated excitation current Im, which is the current of the equivalent excitation inductor.

[0123] In the detection unit, the excitation voltage is subtracted according to the relationship in formula (3) to obtain the primary output current Is of the transformer.

[0124] In the detection unit, according to the relationship in formula (4), the absolute value of the secondary output current is calculated and low-pass filtered to obtain a current signal that is proportional to the output current of the wireless excitation system.

[0125] Understandable, Figure 4 and Figure 5 The various calculations used in the apparatus and method shown to derive the output current of the wireless excitation system based on the bridge arm voltage, resonant voltage, and bridge arm current are merely examples and should not be construed as limiting the method and apparatus of this embodiment.

[0126] In this embodiment, the detection device and method, when the rotor is in an environment of high temperature, high vibration, and high centrifugal force, and it is inconvenient to sample the output current or there is no output feedback, can obtain an output current sampling signal equivalent to the output current of the wireless excitation system by sampling and calculating the voltage and current signals on the stator side.

[0127] It is understood that the processing of a signal described in the embodiments of this application is not limited to performing that specific processing on that signal, but rather includes that specific processing within the processing of the signal, and may include other processing besides that specific processing. For example, performing an addition operation on the resonant voltage and the primary input voltage means performing a processing operation that includes addition on the resonant voltage and the primary input voltage to obtain the excitation voltage.

[0128] The sampling circuits and detection units in this application that implement various corresponding functions can be implemented using analog circuits or digital circuits. Specific implementation methods can be found in existing technologies. For example, when using analog circuits, different combinations of components such as operational amplifiers, resistors, capacitors, and diodes can achieve the functions corresponding to the various mathematical operations mentioned above. These mathematical operations are common techniques in analog electronics.

[0129] Those skilled in the art will recognize that the units and algorithm steps of the various examples described in conjunction with the embodiments disclosed herein 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.

[0130] Those skilled in the art will understand that, for the sake of convenience and brevity, the specific working processes of the systems, devices, and units described above can be referred to the corresponding processes in the foregoing method embodiments, and will not be repeated here.

[0131] In the several embodiments provided in this application, it should be understood that the disclosed systems, apparatuses, and methods can be implemented in other ways. For example, the apparatus embodiments described above are merely illustrative; for instance, the division of units is only a logical functional division, and in actual implementation, there may be other division methods. For example, multiple units or components may be combined or integrated into another system, or some features may be ignored or not executed. Furthermore, the coupling or direct coupling or communication connection shown or discussed may be through some interfaces; the indirect coupling or communication connection between apparatuses or units may be electrical, mechanical, or other forms.

[0132] The units described as separate components may or may not be physically separate. The components shown as units may or may not be physical units; that is, they may be located in one place or distributed across multiple network units. Some or all of the units can be selected to achieve the purpose of this embodiment according to actual needs.

[0133] In addition, the functional units in the various embodiments of this application can be integrated into one processing unit, or each unit can exist physically separately, or two or more units can be integrated into one unit.

[0134] If the aforementioned functions are implemented as software functional units and sold or used as independent products, they can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of this application, in essence, or the part that contributes to the prior art, or a portion of the technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute all or part of the steps of the methods described in the various embodiments of this application. The aforementioned storage medium includes various media capable of storing program code, such as USB flash drives, portable hard drives, read-only memory (ROM), random access memory (RAM), magnetic disks, or optical disks.

[0135] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A method for detecting the output current of a wireless excitation system, characterized in that, The wireless excitation system includes a stator section and a rotor section. The stator section includes an inverter, a resonant inductor, and a primary winding. The rotor section includes a secondary winding and a rectifier. The primary winding and the secondary winding constitute a transformer. The method includes: The first voltage is obtained by sampling the primary input voltage of the transformer, or the fourth voltage is obtained by sampling the output voltage of the bridge arm of the inverter. The voltage of the resonant inductor is sampled to obtain the second voltage; The first current is obtained by sampling the output current of the bridge arm of the inverter. The third voltage of the transformer's magnetizing inductance is determined based on the first voltage and the second voltage, or the third voltage is determined based on the fourth voltage and the second voltage; The second current of the magnetizing inductor is determined based on the third voltage; The secondary output current of the transformer is determined based on the first current and the second current. The output current of the wireless excitation system is determined based on the secondary output current.

2. The method according to claim 1, characterized in that, When sampling the primary input voltage of the transformer to obtain the first voltage, the third voltage satisfies the following relationship with the second voltage and the first voltage: ， in, Um This refers to the third voltage. Ut This represents the first voltage. Ur This indicates the second voltage. Lr This represents the inductance value of the resonant inductor. Lpri This represents the primary-side self-inductance parameter of the transformer. This represents the coupling coefficient of the transformer.

3. The method according to claim 1, characterized in that, When sampling the output voltage of the inverter's bridge arm to obtain the fourth voltage, the third voltage satisfies the following relationship with the second and fourth voltages: ， in, Um This refers to the third voltage. Ub This refers to the fourth voltage. Ur This indicates the second voltage. Lr This represents the inductance value of the resonant inductor. Lpri This represents the primary-side self-inductance parameter of the transformer. k This represents the coupling coefficient of the transformer.

4. The method according to any one of claims 1 to 3, characterized in that, When determining the second current of the magnetizing inductor based on the third voltage, the second current and the third voltage satisfy the following relationship: ， in, Im This indicates the second current. Lpri This represents the primary-side self-inductance parameter of the transformer. k This represents the coupling coefficient of the transformer. Um This refers to the third voltage.

5. The method according to any one of claims 1 to 3, characterized in that, When determining the secondary output current of the transformer based on the first current and the second current, the secondary output current satisfies the following relationship with the first current and the second current: ， in, Is This indicates the secondary-side output current. Ib This represents the first current. Im This indicates the second current. Np This indicates the number of turns in the primary winding of the transformer. Ns This indicates the number of turns in the secondary winding.

6. The method according to any one of claims 1 to 3, characterized in that, When determining the output current of the wireless excitation system based on the secondary-side output current, the output current of the wireless excitation system and the secondary-side output current satisfy the following relationship: ， in, Is This indicates the secondary-side output current. " indicates the absolute value, This indicates calculating the average value. Io This represents the output current of the wireless excitation system.

7. A device for detecting the output current of a wireless excitation system, characterized in that, The wireless excitation system includes a stator section and a rotor section. The stator section includes an inverter, a resonant inductor, and a primary winding. The rotor section includes a secondary winding and a rectifier. The primary winding and the secondary winding constitute a transformer. The device includes: The second sampling circuit is used to sample the primary input voltage of the transformer to obtain the first voltage, or to sample the output voltage of the bridge arm of the inverter to obtain the fourth voltage; The first sampling circuit is used to sample the voltage of the resonant inductor to obtain the second voltage; The third sampling circuit is used to sample the output current of the bridge arm of the inverter to obtain the first current. The detection unit is used for: The third voltage of the transformer's magnetizing inductance is determined based on the first voltage and the second voltage, or the third voltage is determined based on the fourth voltage and the second voltage; The second current of the excitation inductor is determined based on the third voltage, the secondary output current of the transformer is determined based on the first current and the second current, and the output current of the wireless excitation system is determined based on the secondary output current.

8. The apparatus according to claim 7, characterized in that, When the second sampling circuit is used to sample the primary voltage of the transformer to obtain the first voltage, the detection unit is specifically used to perform addition and / or subtraction operations on the first voltage and the second voltage to obtain the third voltage, wherein the third voltage satisfies the following relationship with the first voltage and the second voltage: ， in, Um This refers to the third voltage. Ut This represents the first voltage. Ur This indicates the second voltage. Lr This represents the inductance value of the resonant inductor. Lpri This represents the primary-side self-inductance parameter of the transformer. This represents the coupling coefficient of the transformer.

9. The apparatus according to claim 7, characterized in that, When the second sampling circuit is used to sample the output voltage of the inverter's bridge arm to obtain the fourth voltage, the detection unit is specifically used to perform addition and / or subtraction operations on the fourth voltage and the second voltage to obtain the third voltage. The third voltage satisfies the following relationship with the second voltage and the fourth voltage: ， in, Um This refers to the third voltage. Ub This refers to the fourth voltage. Ur This indicates the second voltage. Lr This represents the inductance value of the resonant inductor. Lpri This represents the primary-side self-inductance parameter of the transformer. k This represents the coupling coefficient of the transformer.

10. The apparatus according to any one of claims 7 to 9, characterized in that, The detection unit is specifically used to perform an integral operation on the third voltage to obtain the second current, and the second current and the third voltage satisfy the following relationship: ， in, Im This indicates the second current. Lpri This represents the primary-side self-inductance parameter of the transformer. k This represents the coupling coefficient of the transformer. Um This refers to the third voltage.

11. The apparatus according to any one of claims 7 to 9, characterized in that, The detection unit is specifically used to perform addition and / or subtraction operations on the first current and the second current to obtain the secondary output current. The secondary output current and the first current and the second current satisfy the following relationship: ， in, Is This indicates the secondary-side output current. Ib This represents the first current. Im This indicates the second current. Np This indicates the number of turns in the primary winding of the transformer. Ns This indicates the number of turns in the secondary winding.

12. The apparatus according to any one of claims 7 to 9, characterized in that, The detection unit is specifically used to rectify and low-pass filter the secondary-side output current sequentially to obtain the output current of the wireless excitation system, wherein the secondary-side output current and the output current of the wireless excitation system satisfy the following relationship: ， in, Is This indicates the secondary-side output current. " indicates the absolute value, This indicates calculating the average value. Io This represents the output current of the wireless excitation system.

13. A wireless excitation system, characterized in that, The wireless excitation system includes the detection device according to any one of claims 7 to 12.

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