A power module switching current broadband integrated measurement method

Abstract

The application is a kind of power module switch current broadband integrated measurement method, the mixed current sensor used in the method includes an induction probe and a processing circuit, the induction probe is located near the current element inside the power module, for measuring the induction magnetic field signal generated by the measured switch current; the processing circuit is used for converting the induction magnetic field signal into current; the induction probe includes a Rogowski coil and a plurality of magnetic resistance sensors arranged in a circumferential array around the current element of the power module, the output anode of the Rogowski coil is connected with an input of the processing circuit, and the output anode of the magnetic resistance sensor is connected with another input of the processing circuit; the Rogowski coil is used for sensing the high-frequency induction magnetic field signal, i.e. the high-frequency component of the measured switch current; the magnetic resistance sensor is used for sensing the low-frequency induction magnetic field signal, i.e. the low-frequency component of the measured switch current. The mixed current sensor enhances the anti-interference ability under the premise of being integrated, and has the characteristics of high bandwidth and high sensitivity.

Description

Technical Field

[0001] The present invention belongs to the technical field of power module switch current measurement and application, and in particular provides a wide-band integrated measurement method for power module switch current. Background Art

[0002] The switching current of power modules is a key common information required for fault protection, status monitoring, and closed-loop control of power electronic equipment and systems. It is mainly composed of high-frequency switching transient currents above MHz and switching on-state currents below MHz. The measurement frequency band of switching current includes DC-MHz. Traditional current sensors have difficulty meeting the requirements of wide bandwidth, easy integration, anti-interference, and intrusion resistance of switching current. In particular, with the advancement of technology and process development, the switching speed, power level, temperature tolerance, and on-state resistance of power modules have gradually improved, making the objects and environments of switching current measurement more complex. As a result, the contradiction between switching current measurement requirements and current sensor performance has become increasingly prominent, which is specifically reflected in the following two aspects:

[0003] Conflict 1: The conflict between the bandwidth performance of current sensors and the wideband requirement for switch current sensing. On the one hand, the switch current is rich in low-frequency components during the conduction phase, and the current sensor requires excellent low-frequency performance to avoid droop errors. On the other hand, the turn-on time of power modules can be as short as nanoseconds, requiring circuit sensors with measurement bandwidths as high as hundreds of MHz.

[0004] The second contradiction is the conflict between current sensor structure and process technology and the high-power density design of power electronics. Traditional current sensors are often designed for universal applicability, focusing on the sensor itself. They lack coordinated optimization with the power module packaging design, making their spurious parameters, volume, weight, and operating temperature performance difficult to meet high-power density requirements. Common shunts are limited by thermal effects, skin effect, and parasitic parameters, making them difficult to meet the requirements of high-power and high-frequency measurement. Coaxial shunts achieve bandwidths of several GHz by creating a magnetic-free space to reduce parasitic inductance and skin effect, but this high frequency comes at the expense of size, making integration difficult. Hall-effect current sensors are limited by core losses, hindering their full high-frequency performance. While magnetoresistive sensors offer bandwidths of several MHz and response times of less than a hundred nanoseconds, they still cannot meet the requirements of measuring nanosecond switching transients. Current transformers can achieve bandwidths of hundreds of MHz and exhibit strong anti-interference capabilities, but the large size and losses associated with the use of a magnetic core to concentrate the magnetic field make them challenging to integrate. The hollow structure of the Rogowski coil current sensor makes it easy to miniaturize, and its bandwidth can reach tens to hundreds of MHz. However, it will produce serious droop errors when measuring low-frequency currents, making it impossible to accurately measure the on-state current of the switch.

[0005] Without disrupting the existing power module packaging structure, existing designs primarily integrate PCB Rogowski coils within the power module to measure switching current. Due to prolonged operation, the internal temperature of the power module can exceed 150°C. This high temperature environment alters the material properties of the PCB substrate and causes significant deformation, leading to undesirable errors in PCB parameters, which in turn affects sensor sensitivity and measurement bandwidth. Furthermore, existing PCB substrates have a maximum of eight layers. As the number of layers increases, the production cost increases significantly, significantly reducing the sensor's designability and practicality.

[0006] In summary, achieving broadband and integrated power module switching current measurement requires addressing three key challenges: 1) How to increase the measurement bandwidth of current sensors based on a single sensing principle to accurately measure both low-frequency and high-frequency components of the switching current. 2) How to minimize the impact of sensor integration on the power module structure and power circuit to avoid the introduction of excessive spurious parameters. 3) How to prevent the high temperature environment within the power module from affecting sensor performance. Summary of the Invention

[0007] In view of the deficiencies in the prior art, the present invention aims to provide a broadband integrated measurement method for the switching current of a power module.

[0008] The technical solution adopted by the present invention to solve the technical problem is as follows:

[0009] A method for broadband integrated measurement of power module switching current is disclosed. The method uses a hybrid current sensor to measure the switching current of the power module. The hybrid current sensor comprises an induction probe and a processing circuit. The induction probe is located near a current element within the power module and is used to measure an induced magnetic field signal generated by the switching current to be measured. The processing circuit is used to convert the induced magnetic field signal into current. The induction probe comprises a Rogowski coil and multiple magnetoresistive sensors arranged in a circular array around the power module current element. The multi-turn windings of the Rogowski coil are arranged in a circular array around the power module current element. The output cathodes of the Rogowski coil and the magnetoresistive sensors are both grounded. The output anode of the Rogowski coil is connected to one input of the processing circuit, and the output anode of the magnetoresistive sensor is connected to another input of the processing circuit. The Rogowski coil is used to sense high-frequency induced magnetic field signals, i.e., the high-frequency component of the switching current to be measured. The magnetoresistive sensor is used to sense low-frequency induced magnetic field signals, i.e., the low-frequency component of the switching current to be measured. The power module circuit elements are power terminals or bonding wires.

[0010] Furthermore, the sensing probe is integrated on the LTCC substrate, the power module current element passes through the center of the LTCC substrate, the LTCC substrate is formed by stacking several layers of green porcelain tapes, and the multiple layers of green porcelain tapes located in the middle of the LTCC substrate form a block for preparing a Rogowski coil. The inner and outer edges of the block are respectively provided with No. 1 through holes arranged in a circular array, and the upper and lower surfaces of the block are respectively provided with multiple grooves radiating from the center line of the power module current element to the surrounding areas. The two ends of each groove are respectively connected to the corresponding No. 1 through hole, and metal liquid is poured into the No. 1 through hole and the groove and sintered by LTCC technology to obtain a Rogowski coil composed of multiple turns of winding interlaced and connected. The Rogowski coil and The metal materials on the LTCC substrate remain electrically isolated; the upper and lower surfaces of the LTCC substrate are respectively coated with metal films, thereby forming a top shielding layer and a bottom shielding layer on the LTCC substrate; the outer edge of the LTCC substrate is densely distributed in a circular array of No. 2 through holes along the stacking direction, and metal liquid is poured into each No. 2 through hole and sintered using LTCC technology to produce metal wires. All metal wires form a shielding layer along the stacking direction on the outer edge of the LTCC substrate, and then together with the top and bottom shielding layers form a semi-enclosed shielding cover, which shares the same ground with the processing circuit; multiple magnetoresistive sensors are mounted on the top shielding layer of the LTCC substrate; LTCC stands for low-temperature co-fired ceramic technology.

[0011] Furthermore, the processing circuit includes a low-frequency processing branch and a high-frequency processing branch. The low-frequency processing branch scales the low-frequency induced magnetic field signal collected by the magnetoresistive sensor, and the high-frequency processing branch integrates and scales the high-frequency induced magnetic field signal collected by the Rogowski coil. Finally, the induced magnetic field signals of the two frequency bands are added together, so that the output of the hybrid current sensor within the designed frequency band has a proportional characteristic. The high-frequency processing branch is composed of a low-pass filter and a proportional amplifier. The transfer function of the hybrid current sensor is:

[0012]

[0013] Where, I'(s), V MR (s) are the frequency domain expressions of the output current and output voltage of the magnetoresistive sensor, I(s) is the frequency domain expression of the switch current to be measured, and K S is the sensitivity of the hybrid current sensor, K L Represents the output gain of the magnetoresistive sensor, U coil (s), V Low (s) are the frequency domain expressions of the output voltages of the Rogowski coil and the low-pass filter, respectively. T L represents the response delay of the magnetoresistive sensor, s represents the Laplace operator, M represents the mutual inductance coefficient of the Rogowski coil, represents the transfer function of the proportional amplifier, represents the transfer function of the magnetoresistive sensor, sM represents the transfer function of the Rogowski coil, Represents the transfer function of a low-pass filter.

[0014] Furthermore, the measurement signals of all magnetoresistive sensors are aggregated into one signal for output through an addition processing circuit; the addition processing circuit includes the same number of differential signal acquisition circuits as the magnetoresistive sensors and an in-phase addition circuit, the output end of each magnetoresistive sensor is connected to the input end of its respective differential signal acquisition circuit, the output ends of all differential signal acquisition circuits are connected to the input end of the in-phase addition circuit, the output end of the in-phase addition circuit and the output end anode of the Rogowski coil are connected to the processing circuit through a two-core coaxial line, and the outer ground wire of the coaxial line is grounded in common with the processing circuit.

[0015] Furthermore, the differential signal acquisition circuit includes resistors R2 to R4, an operational amplifier No. 1, capacitors C1 and C2, and the in-phase addition circuit includes a resistor R1 and an operational amplifier No. 2; the in-phase input terminal and the inverting input terminal of the operational amplifier No. 1 are respectively connected to one end of their respective resistors R2, and the in-phase input terminal and the inverting input terminal of the operational amplifier No. 1 are respectively connected to a parallel branch consisting of a resistor R3 and a capacitor C1, and the end of the resistor R3 connected to the capacitor C1 is grounded, and the other ends of the two resistors R2 are connected to the output end of the magnetoresistive sensor; after the resistor R4 and the capacitor C2 are connected in parallel, they are connected to the inverting input terminal and the output end of the operational amplifier No. 1; the output end of each operational amplifier No. 1 is connected to the in-phase input terminal of the operational amplifier No. 2 through a resistor R1, the inverting input terminal and the in-phase input terminal of the operational amplifier No. 2 are respectively grounded through the resistor R1, and a resistor R1 is connected between the inverting input terminal and the output end of the operational amplifier No. 2.

[0016] Furthermore, the magnetoresistive sensor is a tunnel magnetoresistive sensor, an anisotropic magnetoresistive sensor or a giant magnetoresistive sensor.

[0017] Compared with the prior art, the present invention has the following beneficial effects:

[0018] 1. The present invention designs a hybrid current sensor based on the performance requirements of wide bandwidth, high integration, strong anti-interference, and low intrusion. The induction probe of the hybrid current sensor is composed of a Rogowski coil and a plurality of magnetoresistive sensors. The Rogowski coil is used to measure the high-frequency component of the switch current to be measured, and the magnetoresistive sensor is used to measure the low-frequency component of the switch current to be measured. The Rogowski coil is made based on LTCC technology. The LTCC substrate is not affected by the high-temperature environment inside the power module, thereby ensuring the measurement accuracy. Under the premise of being able to be integrated, the induction probe not only enhances the anti-interference ability, but also has the characteristics of high bandwidth and high sensitivity. Without adding any magnetic concentrating materials, the hybrid current sensor can achieve a measurement bandwidth of DC-100 MHz. Multiple magnetoresistive sensors are arranged in a circular array, which can enhance the reception of effective induced magnetic field signals and play a certain role in compensating for external interference magnetic fields.

[0019] 2. The LTCC substrate has an unlimited number of layers, offering greater design flexibility, lower costs, and ease of large-scale production. The overall size of the sensor probe is small, and the impact on the original layout of the power module during integration is negligible. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 Schematic diagram of the hybrid current sensor integrated into the power module;

[0021] Figure 2 Schematic diagram of the overall structure of the hybrid current sensor;

[0022] Figure 3 This is the schematic diagram of the addition processing circuit;

[0023] Figure 4 It is a structural diagram of the addition processing circuit;

[0024] Figure 5 Schematic diagram of the structure of the TMR magnetoresistive sensor;

[0025] Figure 6 This is the relationship between the resistance of the TMR magnetoresistive sensor and the external magnetic field strength;

[0026] Figure 7 is the equivalent circuit diagram of the magnetoresistive sensor;

[0027] Figure 8 Equivalent circuit diagram of magnetoresistive sensor taking into account parasitic effects;

[0028] Figure 9 This is the working principle diagram of the hybrid current sensor. DETAILED DESCRIPTION

[0029] The technical solution of the present invention will be described in detail below with reference to the accompanying drawings and specific embodiments, but the scope of protection of the present application is not limited thereto.

[0030] The present invention is a broadband integrated measurement method for power module switching current (hereinafter referred to as method, see 1-9), the hybrid current sensor used in the method includes two parts: a sensing probe and a processing circuit. Figure 1 As shown in FIG, the inductive probe is located near current components such as power terminals and bonding wires inside the power module. When the switch current to be measured flows through the current component, the inductive probe measures the induced magnetic field signal generated by the switch current to be measured; the processing circuit is used to convert the induced magnetic field signal into current; as shown in FIG. Figure 2 As shown, the induction probe includes a Rogowski coil and multiple magnetoresistive sensors arranged in a circular array around the current element of the power module. The multi-turn winding of the Rogowski coil is arranged in a circular array around the current element, and the cathodes of the output ends of the Rogowski coil and the magnetoresistive sensor are both grounded; the anode of the output end of the Rogowski coil is connected to one input end of the processing circuit, and the anode of the output end of the magnetoresistive sensor is connected to the other input end of the processing circuit; the Rogowski coil is used to sense the high-frequency induced magnetic field signal, that is, the high-frequency component of the switching current to be measured; the magnetoresistive sensor is used to sense the low-frequency induced magnetic field signal, that is, the low-frequency component of the switching current to be measured, and the measurement signals of the multiple magnetoresistive sensors are aggregated into one signal for output through the addition processing circuit; the multiple magnetoresistive sensors arranged in a circular array can enhance the reception of effective magnetic field signals and play a certain role in compensating for external interfering magnetic fields.

[0031] The induction probe is manufactured based on LTCC (Low Temperature Co-fired Ceramics) technology. The induction probe is integrated on an LTCC substrate. The current element of the power module passes through the center of the LTCC substrate. The LTCC substrate is composed of several layers of green porcelain tapes stacked together. The multiple layers of green porcelain tapes located in the middle of the LTCC substrate form a block for preparing a Rogowski coil. The inner and outer edges of the block are respectively provided with through holes arranged in a circumferential array. The upper and lower surfaces of the block are respectively provided with multiple grooves radiating from the center line of the power module current element. The two ends of each groove are respectively connected to the corresponding through hole. Metal liquid is poured into the through hole and the groove and sintered through the LTCC technology to produce a Rogowski coil composed of multiple turns of windings interlaced and connected. The Rogowski coil is electrically isolated from the metal material on the LTCC substrate. The upper and lower surfaces of the substrate are respectively coated with metal films, thereby forming a top shielding layer and a bottom shielding layer on the LTCC substrate; the outer edge of the LTCC substrate is densely distributed with through holes in a circumferential array along the stacking direction, and metal liquid is poured into each through hole and sintered through the LTCC technology to produce metal wires. All metal wires form a shielding layer along the stacking direction on the outer edge of the LTCC substrate, and then form a semi-enclosed shielding cover together with the top and bottom shielding layers. The semi-enclosed shielding cover shares the same ground with the processing circuit to block the interference of the external magnetic field on the Rogowski coil; one core of the two-core coaxial line passes through the top shielding layer and is connected to the output anode of the Rogowski coil, and the output cathode of the Rogowski coil is connected to the bottom shielding layer through a metal wire to complete grounding; multiple magnetoresistive sensors are installed on the top shielding layer of the LTCC substrate.

[0032] like Figure 3 As shown, the addition processing circuit includes a differential signal acquisition circuit and an in-phase addition circuit, the same number as the magnetoresistive sensors. The output end of each magnetoresistive sensor is connected to the input end of its own differential signal acquisition circuit, and the output ends of all differential signal acquisition circuits are connected to the input end of the in-phase addition circuit. The output end of the in-phase addition circuit and the output end anode of the Rogowski coil are connected to the processing circuit through a two-core coaxial line. The outer ground wire of the coaxial line is grounded with the processing circuit to generate a correct potential and a good shielding effect.

[0033] In order to ensure the output impedance matching of the magnetoresistive sensor, the differential signal acquisition circuit adopts a first-level differential proportional circuit, such as Figure 4As shown, each differential signal acquisition circuit includes resistors R2 to R4, an operational amplifier No. 1, capacitors C1 and C2, and the in-phase adding circuit includes a resistor R1 and an operational amplifier No. 2; the in-phase input terminal and the inverting input terminal of the operational amplifier No. 1 are respectively connected to one end of their respective resistors R2, and the in-phase input terminal and the inverting input terminal of the operational amplifier No. 1 are respectively connected to a parallel branch consisting of a resistor R3 and a capacitor C1, one end of the resistor R3 connected to the capacitor C1 is grounded, and the other ends of the two resistors R2 are connected to the output end of the magnetoresistive sensor; after the resistor R4 and the capacitor C2 are connected in parallel, they are connected to the inverting input terminal and the output end of the operational amplifier No. 1; the output end of each operational amplifier No. 1 is respectively connected to the operational amplifier No. 2 through a resistor R1 The non-inverting input of the first operational amplifier is connected to the non-inverting input of the second operational amplifier, the inverting input and the non-inverting input of the second operational amplifier are respectively grounded through resistor R1, and a resistor R1 is connected between the inverting input and the output of the second operational amplifier; each magnetoresistive sensor is connected to the reference ground, and the introduction of the reference ground ensures that the output of the magnetoresistive sensor and the processing circuit maintain the correct potential; the outputs of multiple magnetoresistive sensors are superimposed through the non-inverting addition circuit, which not only reduces the burden of a single magnetoresistive sensor in collecting the induced magnetic field signal (the same measurement sensitivity is shared by multiple magnetoresistive sensors), but also weakens the influence of external interfering magnetic fields on the measurement (the circular array arrangement makes the effects of the interfering magnetic field on each magnetoresistive sensor cancel each other out, thereby reducing the total error to within the allowable range).

[0034] The magnetoresistive sensor can be a tunnel magnetoresistive sensor (TMR), anisotropic magnetoresistive sensor (AMR) or giant magnetoresistive sensor (GMR). TMR magnetoresistive sensor is preferred because it has better thermal stability and higher sensitivity, which can ensure the accuracy of measurement. The principle of magnetoresistive sensor for measuring power module switching current is as follows: the magnetoresistive sensor consists of two ferromagnetic layers and an insulating layer, forming a sandwich structure, see Figure 5 Because the insulating layer is very thin, electrons can migrate from one ferromagnetic layer (free layer) to another ferromagnetic layer (pinned layer) through the insulating layer, thereby forming a magnetic tunnel junction. Each magnetic tunnel junction is equivalent to a resistor R MR Since the strength of the external magnetic field determines the concentration of tunneling electrons, the resistance of the magnetoresistive sensor changes with the external magnetic field. Figure 6 As shown in the figure, when the resistance of the magnetoresistive sensor is in the linear range, the resistance of the magnetoresistive sensor is directly proportional to the external magnetic field strength. Since the magnetic field strength is proportional to the magnitude of the switch current to be measured, the change in the resistance of the magnetoresistive sensor can reflect the change in the switch current to be measured. Since the properties of the conductive material in the magnetoresistive sensor change with temperature, in order to reduce the influence of temperature drift on the measurement effect, as shown in the figure, Figure 7As shown, the four magnetic tunnel junctions of the magnetoresistive sensor are connected into a bridge structure. The bridge structure includes two bridge arms. The two resistors on each bridge arm are in opposite phases. The two resistors on the diagonal of the two bridge arms are in phase. The two inverted resistors provide resistance change trends in opposite directions, so that the linear relationship between the external magnetic field strength and the output voltage of the magnetoresistive sensor is not affected by factors such as temperature drift and magnetic field offset. Therefore, in theory, the output voltage of the magnetoresistive sensor is proportional to the switch current to be measured; considering the influence of response delay, the transfer function of the magnetoresistive sensor is shown as (1);

[0035]

[0036] Where I(s) represents the current to be measured, V MR (s) represent the frequency domain expressions of the output current and output voltage of the magnetoresistive sensor, respectively, K L represents the output gain of the magnetoresistive sensor, T L represents the response delay of the magnetoresistive sensor, and s represents the Laplace operator;

[0037] Although the magnetoresistance effect is theoretically an effect that works in the range from DC to GHz, its effective working frequency range is often within a few MHz due to the parasitic effects of the magnetoresistance sensor. Research shows that there is an equivalent parasitic capacitance in each wafer of the magnetoresistance sensor. Therefore, the magnetoresistance sensor circuit topology taking into account the parasitic effects is as follows: Figure 8 As shown, each resistor R MR There is an equivalent capacitor in parallel. Therefore, due to the change in magnetic field intensity, the magnetoresistive sensor circuit taking into account the parasitic effect exhibits a low-pass filter characteristic. Therefore, the transfer function of the magnetoresistive sensor taking into account the parasitic effect is shown in formula (2), and the upper cutoff frequency of the effective working range is shown in formula (3);

[0038]

[0039]

[0040] Where, f C Indicates the upper cutoff frequency of the effective working range, C p represents equivalent capacitance, and f represents frequency;

[0041] According to Biot-Savart's law: the magnetic field strength of a current element on a current-carrying wire at a point in a vacuum is proportional to the magnitude of the current element, so the magnetic field strength of the power module current element at a point in space is as shown in formula (4);

[0042]

[0043] Where μ0 is the magnetic permeability of vacuum, I is the amplitude of the switch current to be measured, and r is the distance between the power module current element and a point in space;

[0044] Combined with the sensitivity K of the magnetoresistive sensor L , the relationship between the output voltage of the magnetoresistive sensor and the switch current to be measured is shown in formula (5);

[0045]

[0046] The principle of Rogowski coil measuring power module switching current is:

[0047] According to Lenz's law, the output voltage of the Rogowski coil is a multiple of the differential of the switch current to be measured, and its expression is shown in formula (6). The output voltage of the Rogowski coil can be restored to a high-frequency AC current through a low-pass filter, as shown in formula (7). The upper limit of the measurement bandwidth is usually near the first resonance point of the Rogowski coil, and the lower limit is the crossover frequency of the low-pass filter (the inflection point of the amplitude-frequency characteristic curve).

[0048]

[0049]

[0050] Where U coil (t) represents the time domain expression of the output voltage of the Rogowski coil, Φ represents the magnetic flux, N represents the number of turns of the Rogowski coil, I(t) and I'(t) represent the time domain expression of the actual value and measured value of the switch current to be measured, respectively, h is the width of the Rogowski coil, a and b represent the inner and outer diameters of the Rogowski coil, respectively, M represents the mutual inductance coefficient of the Rogowski coil, k I Indicates the integral coefficient, G th Indicates the sensitivity of the Rogowski coil;

[0051] Because the electromagnetic field coupling within the power module is tighter, the Rogowski coil needs to have strong anti-interference capabilities. Therefore, an external shielding layer is used to cut off the loop formed by the external magnetic field in the Rogowski coil, thereby shielding against external magnetic field interference. However, the addition of the shielding layer is equivalent to the introduction of parasitic capacitance, which lowers the resonance point of the Rogowski coil and reduces the measurement bandwidth of the induction probe. Taking various factors into consideration, shielding layers are added only to the top, bottom, and outside of the Rogowski coil, and a semi-enclosed shielding cover is used. This ensures that the parasitic capacitance is reduced while maintaining the Rogowski coil's ability to measure the induced magnetic field, thereby improving the measurement bandwidth of the induction probe.

[0052] Working principle of induction probe measuring power module switching circuit:

[0053] According to the HOKA principle, the combination of a low-frequency probe and a high-frequency probe can achieve DC-MHz wide-band current measurement; based on the measurement characteristics of the Rogowski coil and the magnetoresistive sensor, the processing circuit needs to process the low-frequency and high-frequency induced magnetic field signals respectively. Therefore, the processing circuit includes a low-frequency processing branch and a high-frequency processing branch. The low-frequency processing branch scales the low-frequency induced magnetic field signal collected by the magnetoresistive sensor, and the high-frequency processing branch integrates and scales the high-frequency induced magnetic field signal collected by the Rogowski coil. Finally, the induced magnetic field signals of the two frequency bands are added together, so that the output of the hybrid current sensor of the present invention within the designed frequency band is proportional. See Figure 9 The magnetoresistive sensor exhibits low-pass characteristics in the low-frequency band, and only the amplification factor needs to be adjusted. Therefore, the transfer function of the low-frequency processing branch satisfies Because the Rogowski coil exhibits differential characteristics within the effective frequency band, the high-frequency processing branch needs to integrate the output signal of the Rogowski coil. Since the Rogowski coil collects the induced magnetic field signal in the high-frequency band, there is no need to consider the low-frequency band. Therefore, the low-pass filter and the proportional amplifier are used together for integration processing. The transfer function of the low-pass filter is: The transfer function of the proportional amplifier is

[0054] In summary, the transfer function of the hybrid current sensor is:

[0055]

[0056] Where V MR (s) is the frequency domain expression of the output voltage of the magnetoresistive sensor, U coil (s) is the frequency domain expression of the output voltage of the Rogowski coil, I(s) is the frequency domain expression of the switch current to be measured, K S is the sensitivity of the hybrid current sensor, V Low (s) represents the frequency domain expression of the low-pass filter output voltage, represents the transfer function of the magnetoresistive sensor, and sM represents the transfer function of the Rogowski coil.

[0057] Any matters not described in the present invention are applicable to the prior art.

Claims

1. A method for measuring the switching current of a power module by using a hybrid current sensor; characterized in that: The hybrid current sensor includes an induction probe and a processing circuit. The induction probe is located near the current element inside the power module and is used to measure the induced magnetic field signal generated by the switch current to be measured. The processing circuit is used to convert the induced magnetic field signal into current. The induction probe includes a Rogowski coil and multiple magnetoresistive sensors arranged in a circular array around the power module current element. The multi-turn winding of the Rogowski coil is arranged in a circular array around the power module current element. The output cathodes of the Rogowski coil and the magnetoresistive sensor are both grounded. The output anode of the Rogowski coil is connected to one input of the processing circuit, and the output anode of the magnetoresistive sensor is connected to the other input of the processing circuit. The Rogowski coil is used to sense the high-frequency induced magnetic field signal, that is, the high-frequency component of the switch current to be measured. The magnetoresistive sensor is used to sense the low-frequency induced magnetic field signal, that is, the low-frequency component of the switch current to be measured. The power module current element mentioned above is a power terminal or a bonding wire. The measurement signals of all magnetoresistive sensors are aggregated into one signal for output through an addition processing circuit; the addition processing circuit includes the same number of differential signal acquisition circuits as the magnetoresistive sensors and a multi-port in-phase addition circuit. The output end of each magnetoresistive sensor is connected to the input end of its respective differential signal acquisition circuit, and the output ends of all differential signal acquisition circuits are connected to the input end of the in-phase addition circuit. The output end of the in-phase addition circuit and the output end anode of the Rogowski coil are connected to the processing circuit via a two-core coaxial line, and the outer ground wire of the coaxial line shares a common ground with the processing circuit.

2. The method for measuring the power module switching current by a wideband integrated circuit according to claim 1, wherein: The induction probe is integrated on the LTCC substrate, and the power module current element passes through the center of the LTCC substrate. The LTCC substrate is formed by stacking several layers of green porcelain tapes. The multiple layers of green porcelain tapes located in the middle of the LTCC substrate form a block for preparing a Rogowski coil. The inner and outer edges of the block are respectively provided with No. 1 through holes arranged in a circular array. The upper and lower surfaces of the block are respectively provided with multiple grooves radiating from the center line of the power module current element. The two ends of each groove are respectively connected to the corresponding No. 1 through hole. Metal liquid is poured into the No. 1 through hole and the groove and sintered through the LTCC technology to obtain a Rogowski coil composed of multiple turns of winding interlaced and connected. The Rogowski coil and the LTC The metal materials on the C substrate remain electrically isolated; the upper and lower surfaces of the LTCC substrate are respectively coated with metal films, thereby forming a top shielding layer and a bottom shielding layer on the LTCC substrate; the outer edge of the LTCC substrate is densely distributed in a circular array of No. 2 through holes along the stacking direction, and metal liquid is poured into each No. 2 through hole and sintered using LTCC technology to produce metal wires. All metal wires form a shielding layer along the stacking direction on the outer edge of the LTCC substrate, and then form a semi-enclosed shielding cover together with the top and bottom shielding layers. The semi-enclosed shielding cover shares the same ground with the processing circuit; multiple magnetoresistive sensors are mounted on the top shielding layer of the LTCC substrate; LTCC stands for low-temperature co-fired ceramic technology.

3. The method for measuring the power module switching current with a wideband integrated circuit according to claim 1, wherein: The processing circuit includes a low-frequency processing branch and a high-frequency processing branch. The low-frequency processing branch scales the low-frequency induced magnetic field signal collected by the magnetoresistive sensor, and the high-frequency processing branch integrates and scales the high-frequency induced magnetic field signal collected by the Rogowski coil. Finally, the induced magnetic field signals of the two frequency bands are added together, so that the output of the hybrid current sensor within the designed frequency band has a proportional characteristic. The high-frequency processing branch is composed of a low-pass filter and a proportional amplifier. The transfer function of the hybrid current sensor is: In the formula, I'(s), U MR (s) are the frequency domain expressions of the output current and output voltage of the magnetoresistive sensor, I(s) is the frequency domain expression of the switch current to be measured, and K S is the sensitivity of the hybrid current sensor, K L Represents the output gain of the magnetoresistive sensor, U coil (s), U Low (s) are the frequency domain expressions of the output voltages of the Rogowski coil and the low-pass filter, respectively. T L represents the response delay of the magnetoresistive sensor, s represents the Laplace operator, M represents the mutual inductance coefficient of the Rogowski coil, represents the transfer function of the proportional amplifier, represents the transfer function of the magnetoresistive sensor, sM represents the transfer function of the Rogowski coil, Represents the transfer function of a low-pass filter.

4. The method for measuring the power module switching current with a wideband integrated circuit according to claim 1, wherein: The differential signal acquisition circuit includes resistors R2 to R4, an operational amplifier No. 1, capacitors C1 and C2, and the in-phase addition circuit includes resistor R1 and operational amplifier No. 2; the in-phase input terminal and inverting input terminal of operational amplifier No. 1 are respectively connected to one end of their respective resistors R2, and the in-phase input terminal and inverting input terminal of operational amplifier No. 1 are respectively connected to a parallel branch consisting of resistor R3 and capacitor C1, the end of resistor R3 connected to capacitor C1 is grounded, and the other ends of the two resistors R2 are connected to the output end of the magnetoresistive sensor; after the resistor R4 and capacitor C2 are connected in parallel, they are connected to the inverting input terminal and output end of operational amplifier No. 1; the output end of each operational amplifier No. 1 is connected to the in-phase input terminal of operational amplifier No. 2 through a resistor R1, the inverting input terminal and the inverting input terminal of operational amplifier No. 2 are respectively grounded through resistor R1, and a resistor R1 is connected between the inverting input terminal and the output end of operational amplifier No.

2.

5. The method for wideband integrated measurement of power module switching current according to any one of claims 1 to 4, characterized in that: The magnetoresistive sensor is a tunnel magnetoresistive sensor, an anisotropic magnetoresistive sensor or a giant magnetoresistive sensor.

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