Motor controller firmware soldering defect detection method and system, motor controller and storage medium

Abstract

The application provides a motor controller firmware missing welding detection method and system, a motor controller and a storage medium, and relates to the technical field of motor controller fault detection. The detection method comprises the following steps: short-circuiting three-phase output ends of the controller to form a single current loop; sequentially turning on a preset cross conduction combination, collecting each-phase current obtained through internal calculation, calculating an average current, and determining that the lower bridge arm of any phase is missing welding when the deviation between the current of the phase and the average current is greater than a first set threshold; when the lower bridge arm detection passes, a six-step cross conduction test sequence is performed, loop impedance corresponding to each step is obtained, each loop impedance is transformed by using a differential characteristic transformation matrix, only upper bridge arm characteristic values of the three-phase upper bridge arms related to the internal resistance of the upper bridge arms are obtained, and the upper bridge arm of any phase is determined to be missing welding when the characteristic value of the phase is not less than a second set threshold and the ratio of the characteristic values of the other two-phase upper bridge arms to the characteristic value of the phase upper bridge arm falls into a preset proportion interval.

Description

Technical Field

[0001] This invention relates to the field of motor controller fault detection technology, and in particular to a method, system, motor controller, and storage medium for detecting missing solder joints in motor controller firmware. Background Technology

[0002] To improve power density and reduce conduction losses and costs, vehicle controllers commonly employ a 12-MOSFET topology with two MOSFETs connected in parallel per phase arm. In surface mount or wave soldering processes, poor soldering or device misalignment can lead to a single MOSFET failing to connect, causing the dual-MOSFET configuration to degenerate into single-MOSFET operation. This becomes a difficult-to-detect manufacturing defect. During light-load functional testing on the production line, even with a single MOSFET failing to connect, the device can still conduct with minimal voltage waveform distortion, failing to effectively intercept the defect. This can lead to the controller failing under heavy-load conditions such as hill climbing, due to the increased internal resistance of the defective bridge arm, ultimately causing the MOSFET to explode.

[0003] Existing technical solutions can be divided into two categories: hardware testing and software testing. Traditional micro-impedance testing schemes based on hardware testing require the addition of a four-wire resistor and a complex relay switching network to measure the on-resistance of each bridge arm one by one, resulting in high hardware costs and slow test cycles. Existing software testing schemes test MOSFETs based on absolute impedance thresholds. The software reads the phase current to calculate the total circuit impedance and compares it with the calibrated threshold to determine whether there is a solder joint leak. However, due to common-mode interference, including line resistance, contact resistance, and temperature drift, fault signals are easily drowned out by noise, resulting in extremely high false positive and false negative rates. Summary of the Invention

[0004] In a first aspect, the present invention provides a method for detecting missing solder joints in firmware of power devices in a motor controller, comprising the following steps: The three-phase output terminals of the controller, U, V, and W, are short-circuited through a low-impedance clamp to form a single current loop. The preset cross-conduction combinations are sequentially turned on, the current of each phase obtained by internal calculation is collected, and the average current is calculated. When the deviation of any phase current from the average current is greater than the first set threshold, it is determined that the lower bridge arm of that phase is missing; otherwise, it is determined that the lower bridge arm detection is passed. When the lower bridge arm passes the test, a six-step cross-continuity test sequence is executed to obtain the loop impedance corresponding to each step. The differential characteristic transformation matrix is ​​used to transform each loop impedance. This transformation cancels the common-mode interference component common to each loop impedance and the lower bridge arm internal resistance component related to each step of conduction, obtaining the characteristic value of each phase upper bridge arm that is only related to the internal resistance of the three phase upper bridge arms. When the characteristic value corresponding to each phase upper bridge arm is less than the second set threshold, the upper bridge arm is determined to pass the test. When the characteristic value of any phase upper bridge arm is not less than the second set threshold, and the ratio of the characteristic values ​​of the other two phase upper bridge arms to the characteristic value of the phase upper bridge arm falls within the preset ratio range, the phase upper bridge arm is determined to be missing solder.

[0005] Furthermore, the first set threshold is: when the current of any phase is greater than 1.2 to 1.5 times the average current, it is determined that the lower bridge arm of that phase is missing a weld.

[0006] Furthermore, the six-step cross-conduction test sequence is as follows: the upper bridge arm of phase U is connected to the lower bridge arm of phase V, the upper bridge arm of phase U is connected to the lower bridge arm of phase W, the upper bridge arm of phase V is connected to the lower bridge arm of phase U, the upper bridge arm of phase V is connected to the lower bridge arm of phase W, the upper bridge arm of phase W is connected to the lower bridge arm of phase U, and the upper bridge arm of phase W is connected to the lower bridge arm of phase V. After each step of conduction, the current value is read in the steady state and the mean is filtered to obtain the loop current. The loop current is then converted into equivalent impedance according to the preset scaling factor.

[0007] Furthermore, the characteristic value of the upper arm of any phase is twice the internal resistance of the upper arm of that phase minus the sum of the internal resistances of the upper arms of the other two phases.

[0008] Furthermore, when the characteristic value of any phase upper arm is greater than the second set threshold, but the ratio of the characteristic values ​​of the other two phase upper arms to the characteristic value of the phase upper arm does not fall within the preset ratio range, it is determined to be external interference and a delayed retest is triggered; when the number of retests exceeds the preset upper limit, the test failure is reported.

[0009] Furthermore, the preset ratio range is -0.35 to -0.65.

[0010] Furthermore, the maximum value of each upper bridge arm characteristic value is compared with the second set threshold.

[0011] Secondly, this invention provides a firmware leak detection system for motor controller power devices, comprising: a three-phase output short-circuit unit, used to short-circuit the U, V, and W phase output terminals of the controller through a low-impedance fixture to form a single current loop during the production line testing phase; a lower bridge arm diagnostic module, built into the microcontroller unit of the motor controller, used to sequentially conduct preset cross-conduction combinations, collect the phase currents calculated internally by the microcontroller unit, calculate the average current, and determine that the lower bridge arm of any phase has a leak when the deviation between the current of any phase and the average current is greater than a first set threshold, otherwise the lower bridge arm is determined to have passed the test; an upper bridge arm fine screening module, built into the microcontroller unit of the motor controller, used to perform differential characteristic transformation and fault determination according to a preset six-step cross-conduction test sequence when the lower bridge arm has passed the test; and a host computer communication module, connected to the microcontroller unit, used to send a test start command and receive the test results.

[0012] Thirdly, the present invention provides a motor controller, including a microcontroller unit, a three-phase inverter bridge arm circuit and a power device drive circuit, wherein the motor controller has the aforementioned detection system built in.

[0013] Fourthly, the present invention also provides a computer-readable storage medium having a computer program stored thereon, which, when executed by a microcontroller unit of a motor controller, implements the steps of the above-described method.

[0014] The method, system, motor controller, and storage medium for detecting missing solder joints in motor controller firmware provided by this invention have the following beneficial effects: 1. Taking advantage of the significant signal of lower bridge arm weld defects, the weld defect of the lower bridge arm can be quickly detected and located by a simple phase current-mean value comparison. 2. The impedance of each circuit measured by the six-step cross-conduction method contains the same clamp contact resistance and temperature drift component. After processing by the differential characteristic transformation matrix, the common mode component is canceled out. The characteristic value only reflects the difference in the internal resistance of the upper bridge arm, which solves the problem of weak upper bridge arm fault signals being drowned out by noise and improves the detection accuracy. 3. By using a dual-condition approach of threshold and ratio to locate the missing weld on the upper bridge arm, the judgment result is automatically verified, reducing false alarms caused by random disturbances. 4. The entire testing process does not increase additional hardware costs, balancing testing costs and accuracy. Attached Figure Description

[0015] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0016] Figure 1 The circuit topology diagram of the test loop provided in the embodiment of the present invention; Figure 2 A flowchart of a method for detecting missing solder joints in motor controller firmware provided in an embodiment of the present invention; Figure 3 The upper arm solder joint defect feature value mapping map of the motor controller firmware defect detection method provided in the embodiments of the present invention; Figure 4 This is a schematic diagram of a firmware leak detection system for motor controller power devices provided in an embodiment of the present invention.

[0017] Icons: 100 - Three-phase output short-circuit unit; 200 - Microcontroller unit; 210 - Lower bridge arm diagnostic module; 220 - Upper bridge arm fine screening module; 300 - Host computer communication module. Detailed Implementation

[0018] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. The components of the embodiments of the present invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0019] Therefore, the following detailed description of the embodiments of the invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the invention without inventive effort are within the scope of protection of the invention.

[0020] It should be noted that similar labels and letters in the following figures indicate similar items. Therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures.

[0021] In the description of this invention, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship commonly used when the product of this invention is in use. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this invention. In addition, the terms "first," "second," "third," etc., are only used to distinguish descriptions and should not be construed as indicating or implying relative importance.

[0022] Furthermore, terms such as "horizontal," "vertical," and "sag" do not imply that components must be absolutely horizontal or suspended, but rather that they can be slightly tilted. For example, "horizontal" simply means that its direction is more horizontal relative to "vertical," and does not mean that the structure must be completely horizontal, but can be slightly tilted.

[0023] In the description of this invention, it should also be noted that, unless otherwise explicitly specified and limited, the terms "set," "install," "connect," and "link" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0024] The following detailed description of some embodiments of the present invention is provided in conjunction with the accompanying drawings. Unless otherwise specified, the following embodiments and features can be combined with each other.

[0025] First, refer to Figure 1 and Figure 2 This describes a method for detecting missing solder joints in the firmware of a motor controller power device according to an embodiment of the present invention. Figure 1 and Figure 2 As shown, the method includes the following steps: Before testing, the three-phase output terminals of the controller (U, V, W) are short-circuited through a low-impedance clamp to form a single current loop.

[0026] In the embodiments of this application, during the production line testing phase, the three-phase outputs U, V, and W of the controller are short-circuited by a low-impedance fixture to form a single current loop. The test loop circuit topology model is as follows: Figure 1 As shown. Currently, in the FOC algorithm of the controller, the lower bridge arm dual MOS transistor V is read... DS The phase current is derived from the voltage drop, and the internal calculation formula of the MCU is as follows: I mcu = K1·V DS_ADC / R nom (T) Where V DS_ADC R is the drain-source voltage value calculated from the ADC reading. nom (T) represents the nominal internal resistance and temperature compensation coefficient of the bridge arm, and K1 represents the voltage acquisition gain coefficient.

[0027] In the above V DS In the sampling architecture, the upper bridge arm power devices only act as switches and do not participate in current sampling, while the lower bridge arm power devices also function as current sampling sensors. When solder joint defects occur in different bridge arms, they exhibit fundamental differences in fault response—that is, physical-sensing asymmetry. When the lower bridge arm is not properly welded, the internal resistance of the bridge arm doubles to 2·R. nom (T), V DS The voltage drop approximately doubles, and the MCU calculates the current I. mcu It produces nearly 100% positive distortion, which can directly locate the faulty lower bridge arm, but the impedance calculation fails because the sampling reference is deeply coupled with the target under test when the current is used to calculate the impedance. When the upper bridge arm is missing a solder joint, it only functions as a switch and does not participate in current sampling. Doubling its resistance only causes a slight decrease (approximately 5%) in the total physical current of the entire test circuit. This current flows through the intact lower bridge arm and is used as the I obtained by the sensor sampling. mcu It will accurately reflect the total current of the physical circuit, but the defect signal is weak and easily masked by noise.

[0028] The stark contrast between the amplified lower bridge fault signal and the weak upper bridge fault signal constitutes the physical-sensing asymmetry characteristic upon which this invention relies.

[0029] In step S1, the preset cross-conduction combinations are turned on sequentially, the current of each phase obtained by internal calculation is collected, and the average current is calculated. When the deviation between any phase current and the average current is greater than the first set threshold, it is determined that the lower bridge arm of that phase is missing a weld; otherwise, it is determined that the lower bridge arm detection is passed.

[0030] In the embodiments of this application, step S1 utilizes the lower bridge solder joint failure to cause I mcu The asymmetric amplification characteristic, resulting in nearly 100% distortion of the current reading, is used for millisecond-level coarse screening. Specifically, the microcontroller unit 200 outputs a reference duty cycle (e.g., 10%), sequentially conducting three cross-conduction combinations: U-phase upper bridge arm - V-phase lower bridge arm, V-phase upper bridge arm - W-phase lower bridge arm, and W-phase upper bridge arm - U-phase lower bridge arm. The internally calculated current is then acquired and denoted as I. u I v I w Calculate the average current I of the three. avg = (I u +I v +I w ) / 3.

[0031] In an ideal situation where there are no defects in the lower bridge and the contact resistance is balanced, the three-phase current is close to the average value; if the current reading of one phase is significantly higher than the other readings, it can be immediately determined that the lower bridge arm of that phase is missing a weld.

[0032] As a specific embodiment, the first set threshold is: when the current of any phase is greater than 1.2 to 1.5 times the average current, it is determined that the lower bridge arm of that phase is missing a weld.

[0033] Therefore, step S1 utilizes the significant characteristic of the lower bridge arm missing solder joint signal to quickly detect and locate the fault when the lower bridge arm is missing solder joint through a simple phase current-mean value comparison, without the need for additional precision impedance measurement.

[0034] In step S2, when the lower bridge arm passes the test, a six-step cross-continuity test sequence is executed to obtain the loop impedance corresponding to each step. The differential characteristic transformation matrix is ​​used to transform each loop impedance. This transformation cancels the common-mode interference component common to each loop impedance and the lower bridge arm internal resistance component related to each step's conduction, obtaining the characteristic values ​​of each phase upper bridge arm that are only related to the internal resistance of the three-phase upper bridge arms. When the characteristic values ​​corresponding to each phase upper bridge arm are all less than the second set threshold, the upper bridge arm is determined to have passed the test. When the characteristic value of any phase upper bridge arm is not less than the second set threshold, and the ratio of the characteristic values ​​of the other two phase upper bridge arms to the characteristic value of the phase upper bridge arm falls within the preset ratio range, the phase upper bridge arm is determined to have a missing weld.

[0035] In the embodiments of this application, step S1 has logically proven that all three lower bridge arms are functionally intact, therefore the I read by the MCU in step S2 mcu This can be considered a reliable and accurate loop current measurement. The goal of step S2 is to identify minor solder joint defects in the upper bridge arm while eliminating common-mode interference.

[0036] For ease of description, let the internal resistances of the upper arms of phases U, V, and W be denoted as u, ... h v h w h The internal resistances of the lower bridge arms of phases U, V, and W are respectively u l v l w l The common-mode interference component in the test circuit (including fixture contact impedance, cable resistance, and temperature drift) is C.

[0037] As a specific embodiment, the six-step cross-conduction test sequence is as follows: the upper arm of phase U is connected to the lower arm of phase V, the upper arm of phase U is connected to the lower arm of phase W, the upper arm of phase V is connected to the lower arm of phase U, the upper arm of phase V is connected to the lower arm of phase W, the upper arm of phase W is connected to the lower arm of phase U, and the upper arm of phase W is connected to the lower arm of phase V.

[0038] After each conduction step, the current value is read during the steady-state current and then averaged and filtered to obtain the loop current I. xy Press R' xy =K / I xy Calculate the equivalent impedance, where K is a preset scaling factor. The six sets of loop impedances obtained from the six-step measurement are denoted as follows: R uv (U-phase upper bridge arm and V-phase lower bridge arm are connected), R uw (U-phase upper bridge arm and W-phase lower bridge arm are connected), R vu (V-phase upper bridge arm and U-phase lower bridge arm are connected), R vw (V-phase upper bridge arm and W-phase lower bridge arm are connected), R wu (W-phase upper bridge arm and U-phase lower bridge arm are connected), R wv (The upper arm of phase W and the lower arm of phase V are connected).

[0039] A system of linear equations was established based on the six sets of measured impedances:

[0040] By performing a basis transformation in linear algebraic space, the common terms including the fixture contact impedance C and the lower bridge arm interference are mathematically canceled out to zero, thus refining the pure upper bridge arm internal resistance characteristic value. The characteristic values ​​of the upper bridge arms for each phase are defined as follows:

[0041]

[0042]

[0043] From the above definition, we can see that H u H v H w Only related to the internal resistance variable u of the upper bridge arm h v h w h Related to the lower bridge arm internal resistance variable u l v l w l It is completely unrelated to the common-mode interference component C.

[0044] By transforming the loop impedance using the differential eigenvalue transformation matrix, the aforementioned eigenvalues ​​can be directly calculated from the six measured sets of loop impedance values. Let the loop impedance vector be... eigenvectors of the upper bridge arm Construct a 3x6 difference eigentransformation matrix T:

[0045] Therefore, the difference elimination process is condensed into a very simple matrix transformation. It involves only a small number of multiplication and addition operations, resulting in extremely low computational overhead.

[0046] Taking a leaky weld on the upper bridge of phase U as an example, let the nominal internal resistance of each bridge arm under normal operation be R, and let the increase in internal resistance of a single bridge arm due to a leaky weld be ΔR. Then the internal resistance of the upper bridge arm of phase U changes abruptly to R + ΔR (while the other bridge arms maintain normal internal resistance R). Substituting into the definition of characteristic value, we get:

[0047] Fault feature vector The characteristic pattern exhibits the following three main patterns: defects are positively amplified, the corresponding eigenvalue of the faulty bridge arm surges by +2ΔR, and the signal-to-noise ratio doubles; the same-side negative mirror image is formed, and the eigenvalues ​​of the other two phases of the same half-bridge shift negatively with equal amplitude. ΔR; the opposite side is completely isolated, and the corresponding feature of the other half of the bridge is always zero, with no coupling interference. Matrix T is a minimal complete linear transformation system, and any bridge arm is of equal status in the derivation, with no detection blind zone.

[0048] Figure 3 The complete characteristic value output is presented in detail under any single bridge arm weld failure.

[0049] As a specific embodiment, the maximum value of each upper bridge arm characteristic value is compared with a second preset threshold, that is, MaxH = max(|H u |, |H v |, |H w|): If MaxH is less than the preset calibration threshold, all upper bridge arm power devices are determined to be properly soldered, and a pass signal is returned; otherwise, the phase corresponding to MaxH (such as H) is locked. u ), check the other two phases (such as H) v H w Does the ratio simultaneously satisfy the relationship that falls within a preset ratio range—that is, H? v / H u With H w / H u Whether all values ​​fall within this range. The preset ratio range is from -0.35 to -0.65, corresponding to the theoretical ratio. A tolerance of approximately ±30% of 0.5 is allowed. If this is met, the upper arm of that phase is considered to have a weld defect, and the host computer reports the faulty phase information.

[0050] As a specific implementation, when MaxH exceeds the second set threshold, but the ratio of the characteristic values ​​of the other two phases to the characteristic value of the phase corresponding to MaxH does not fall within the preset ratio range, it is determined to be external interference and a delayed retest is triggered; when the number of retests exceeds the preset upper limit, the test failure is reported.

[0051] The entire testing process is fast, including the lower bridge arm diagnosis in step S1 and the upper bridge arm diagnosis in step S2, with a total time of less than 500ms.

[0052] Using H u / H v / H w Positive amplification of eigenvalues ​​- negative mirror self-verification polarity, i.e., fault phase eigenvalue + 2ΔR, and the other two phases on the same side. ΔR effectively distinguishes between genuine solder joint defects and random electrical noise interference, significantly reducing the false alarm rate. This self-checking mechanism is one of the core advantages of this solution compared to traditional single-point threshold detection.

[0053] Therefore, according to the method of the present invention, by rapidly screening for missing welds in the lower bridge arm in step S1 and extracting the feature values ​​of the upper bridge arm after eliminating common-mode interference using the differential feature transformation matrix in step S2, the detection of missing welds in all six bridge arms without increasing any additional hardware costs is achieved. The detection speed is fast and the accuracy is high, taking into account both the cost and quality requirements of production line testing.

[0054] The following is combined Figure 4 A system for detecting missing solder joints in the firmware of a motor controller power device according to a first aspect of the present invention is described. Figure 4As shown, the system includes a three-phase output short-circuit unit 100, a lower bridge arm diagnostic module 210 and an upper bridge arm fine screening module 220 built into the motor controller microcontroller unit 200, and a host computer communication module 300 connected to the microcontroller unit 200. The entire testing process is fully integrated into the firmware of the motor controller microcontroller unit 200. The host computer only needs to send a start command and receive the results, and the testing hardware cost is zero.

[0055] The three-phase output shorting unit 100 is used to short-circuit the U, V, and W three-phase output terminals of the controller through a low-impedance clamp to form a single current loop during the production line testing phase.

[0056] The lower bridge arm diagnostic module 210 is built into the microcontroller unit 200 of the motor controller. It is used to sequentially conduct preset cross conduction combinations, collect the phase currents calculated by the microcontroller unit 200, calculate the average current, and determine that the lower bridge arm of any phase is missing when the deviation between the phase current and the average current is greater than the first set threshold. Otherwise, the lower bridge arm is determined to pass the test.

[0057] The lower arm diagnostic module 210 utilizes V DS Sampling architecture with missing solder joint on the lower bridge causing I mcu The asymmetric amplification characteristic, resulting in nearly 100% distortion of the current reading, enables millisecond-level coarse screening. The lower bridge arm diagnostic module 210 outputs a reference duty cycle (e.g., 10%), sequentially activating three cross-conduction combinations: U-phase upper bridge arm - V-phase lower bridge arm, V-phase upper bridge arm - W-phase lower bridge arm, and W-phase upper bridge arm - U-phase lower bridge arm. The internally calculated current is collected and denoted as I0. u I v I w Calculate the average current I of the three. avg = (I u +I v +I w ) / 3. Under ideal conditions where there are no defects in the lower bridge and the contact resistance is balanced, the three-phase current is close to the average value; if the current reading of one phase significantly exceeds the readings of the others, it can be immediately determined that the lower bridge arm of that phase is missing a weld.

[0058] As a specific embodiment, in the lower bridge arm diagnostic module 210, the first set threshold is: when the current of any phase is greater than 1.2 to 1.5 times the average current, it is determined that the lower bridge arm of that phase is missing a weld.

[0059] Therefore, the lower arm diagnostic module 210 takes advantage of the significant characteristic of the lower arm missing solder joint signal and can quickly detect and locate the fault when the lower arm is missing solder joint by a simple phase current-mean value comparison, without the need for additional precision impedance measurement.

[0060] The upper bridge arm precision screening module 220 is built into the microcontroller unit 200 of the motor controller and is activated after the lower bridge arm diagnostic module 210 determines that the test has passed. When the lower bridge arm test passes, the upper bridge arm precision screening module 220 performs the following operations: according to the preset six-step cross-conduction test sequence, different combinations of upper and lower bridge arm power devices are sequentially turned on. After each step of conduction, the current value is read and averaged after steady state. The equivalent impedance is calculated according to the preset scaling factor to obtain six sets of loop impedances. The characteristic value corresponding to each phase upper bridge arm is calculated by matrix transformation using the differential characteristic transformation matrix. The characteristic value is only related to the internal resistance of each phase upper bridge arm and is not related to the internal resistance of the lower bridge arm or the common-mode interference component of the test loop. Based on the comparison of each phase characteristic value with the second set threshold and whether the ratio of the other two phase characteristic values ​​to the maximum characteristic value falls within the preset ratio range, the upper bridge arm incomplete welding fault is determined and the phase where the fault is located is located.

[0061] In one specific embodiment, the six-step cross-continuity test sequence in the upper bridge arm screening module 220 is as follows: the upper bridge arm of phase U is connected to the lower bridge arm of phase V; the upper bridge arm of phase U is connected to the lower bridge arm of phase W; the upper bridge arm of phase V is connected to the lower bridge arm of phase U; the upper bridge arm of phase V is connected to the lower bridge arm of phase W; the upper bridge arm of phase W is connected to the lower bridge arm of phase U; and the upper bridge arm of phase W is connected to the lower bridge arm of phase V. After each connection step, the current value is read in steady state and averaged to obtain the loop current I. xy Press R' xy = K / I xy Calculate the equivalent impedance, where K is a preset scaling factor, to obtain six sets of loop impedances R. uv R uw R vu R vw R wu R wv .

[0062] The upper bridge arm fine screening module 220 uses a basis transformation in linear algebraic space to cancel out all common terms, including the fixture contact impedance C, and interference from the lower bridge arm, thus refining the pure upper bridge arm internal resistance characteristic value H. u H v H w In one specific embodiment, in the upper bridge arm fine screening module 220, the characteristic value of any phase upper bridge arm is twice the internal resistance value of that phase's upper bridge arm minus the sum of the internal resistance values ​​of the upper bridge arms of the other two phases. The upper bridge arm fine screening module 220 uses the differential characteristic transformation matrix T to transform the loop impedance vector. The transformation is performed to obtain the eigenvalue vector of the upper bridge arm. It involves only a small number of multiplication and addition operations, resulting in extremely low computational overhead.

[0063] Taking a leaky weld on the upper bridge of phase U as an example, let the nominal internal resistance of each bridge arm under normal operation be R, and let the increase in internal resistance of a single bridge arm due to a leaky weld be ΔR. Then, the internal resistance of the upper bridge arm of phase U changes abruptly to R + ΔR, while the remaining bridge arms maintain the normal internal resistance R. The upper bridge arm fine screening module 220 calculates the following:

[0064] Fault feature vector The following patterns emerge: defects are positively amplified, with the corresponding eigenvalue of the faulty bridge arm surging by +2ΔR, doubling the signal-to-noise ratio; they are negatively mirrored on the same side, with the eigenvalues ​​of the other two phases of the same half-bridge shifting negatively by -ΔR of equal amplitude; the opposite side is completely isolated, with the corresponding eigenvalue of the other half-bridge remaining constant at zero, indicating no coupling interference. Matrix T is a minimal complete linear transformation system, with all bridge arms having equal status in the derivation, and no detection blind spots.

[0065] As a specific embodiment, the upper bridge arm fine screening module 220 compares the maximum value of each upper bridge arm feature value with a second preset threshold, that is, it calculates MaxH = max(|H u |, |H v |, |H w If MaxH is less than the preset calibration threshold, all upper bridge arm power devices are determined to be properly welded, and a pass signal is returned; otherwise, the phase corresponding to MaxH (such as H) is locked. u ), check the other two phases (such as H) v H w Does the ratio simultaneously satisfy the relationship that falls within a preset ratio range—that is, H? v / H u With H w / H u Whether all values ​​fall within this range. The preset ratio range is from -0.35 to -0.65, corresponding to a tolerance of approximately ±30% for the theoretical ratio of -0.5. If satisfied, it is determined that the upper bridge arm of that phase has a missing weld, and the information is uploaded to the upper computer communication module 300 and reported as a faulty phase.

[0066] As a specific embodiment, when MaxH exceeds the second set threshold, but the ratio of the characteristic values ​​of the other two phases to the characteristic value of the phase corresponding to MaxH does not fall within the preset ratio range, the upper bridge arm fine screening module 220 determines it as external interference and triggers a delayed retest; when the number of retests exceeds the preset upper limit, the test failure is reported.

[0067] In one specific embodiment, the total operating time of the lower arm diagnostic module 210 and the upper arm fine screening module 220 does not exceed 500ms.

[0068] Using H u / H v / H wBy amplifying the eigenvalues ​​positively and mirroring them negatively to self-verify their polarity, the upper arm precision screening module 220 can effectively distinguish between genuine weld defect and random electrical noise interference, significantly reducing the false alarm rate. Therefore, based on the successful detection by the lower arm diagnostic module 210, the upper arm precision screening module 220 uses a differential feature transformation matrix to eliminate common-mode interference and extracts the upper arm eigenvalues, achieving precise location of upper arm weld defects without increasing any additional hardware costs.

[0069] The host computer communication module 300 is connected to the microcontroller unit 200 and is used to send detection start commands and receive detection results returned by the microcontroller unit 200.

[0070] Those skilled in the art can understand the structure and specific operation of each module in the detection system according to the embodiments of the present invention by combining the content. For the sake of brevity, it will not be described in detail here.

[0071] Furthermore, according to an embodiment of the present invention, a motor controller is also provided, including a microcontroller unit 200, a three-phase inverter bridge arm circuit and a power device drive circuit, wherein the motor controller has the aforementioned detection system built in.

[0072] Furthermore, the present invention also provides a storage medium storing a computer program that, when run by the microcontroller unit 200 of the motor controller, causes the microcontroller unit 200 to execute a method for detecting firmware defects in the power devices of the motor controller. The storage medium may, for example, include a read-only memory, an erasable programmable read-only memory, a USB memory, or any combination of the above storage media.

[0073] Based on the above description, the motor controller power device firmware missing solder detection method according to the embodiment of the present invention achieves accurate detection of all six bridge arm missing solder faults without increasing any additional hardware costs by adopting a two-stage cascade detection strategy of coarse screening of lower bridge arm current deviation and fine screening of upper bridge arm differential characteristic transformation. This balances detection cost and accuracy.

[0074] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for detecting missing solder joints in motor controller firmware, characterized in that, Includes the following steps: The three-phase output terminals of the controller, U, V, and W, are short-circuited through a low-impedance clamp to form a single current loop. The preset cross-conduction combination is sequentially turned on, the current of each phase obtained by internal calculation is collected, the average current is calculated, and when the deviation of any phase current from the average current is greater than the first set threshold, it is determined that the lower bridge arm of that phase is missing weld. Otherwise, the lower bridge arm inspection is deemed passed; When the lower bridge arm passes the test, a six-step cross-continuity test sequence is executed to obtain the loop impedance corresponding to each step. The differential characteristic transformation matrix is ​​used to transform each loop impedance. This transformation cancels the common-mode interference component common to each loop impedance and the lower bridge arm internal resistance component related to each step of conduction, obtaining the characteristic value of each phase upper bridge arm that is only related to the internal resistance of the three phase upper bridge arms. When the characteristic value corresponding to each phase upper bridge arm is less than the second set threshold, the upper bridge arm is determined to pass the test. When the characteristic value of any phase upper bridge arm is not less than the second set threshold, and the ratio of the characteristic values ​​of the other two phase upper bridge arms to the characteristic value of the phase upper bridge arm falls within the preset ratio range, the phase upper bridge arm is determined to be missing solder.

2. The method for detecting missing solder joints in motor controller firmware according to claim 1, characterized in that, The first set threshold is: when the current of any phase is greater than 1.2 to 1.5 times the average current, it is determined that the lower bridge arm of that phase is missing a weld.

3. The method for detecting missing solder joints in motor controller firmware according to claim 1, characterized in that, The six-step cross-conduction test sequence is as follows: U-phase upper bridge arm conducts through V-phase lower bridge arm, U-phase upper bridge arm conducts through W-phase lower bridge arm, V-phase upper bridge arm conducts through U-phase lower bridge arm, V-phase upper bridge arm conducts through W-phase lower bridge arm, W-phase upper bridge arm conducts through U-phase lower bridge arm, and W-phase upper bridge arm conducts through V-phase lower bridge arm. After each conduction step, the current value is read when the current is in steady state and the mean is filtered to obtain the loop current. The loop current is then converted into equivalent impedance according to a preset scaling factor.

4. The method for detecting missing solder joints in motor controller firmware according to claim 1, characterized in that, The characteristic value of the upper arm of any phase is twice the internal resistance of the upper arm of that phase minus the sum of the internal resistances of the upper arms of the other two phases.

5. The method for detecting missing solder joints in motor controller firmware according to claim 1, characterized in that, When the characteristic value of any phase upper arm is greater than the second set threshold, but the ratio of the characteristic values ​​of the other two phase upper arms to the characteristic value of the phase upper arm does not fall within the preset ratio range, it is determined to be external interference and a delayed retest is triggered; when the number of retests exceeds the preset upper limit, a test failure is reported.

6. The method for detecting missing solder joints in motor controller firmware according to claim 1, characterized in that, The preset ratio range is -0.35 to -0.

65.

7. The method for detecting missing solder joints in motor controller firmware according to claim 1, characterized in that, The maximum value of each upper bridge arm characteristic value is compared with the second set threshold.

8. A system for detecting missing solder joints in motor controller firmware, characterized in that, include: The three-phase output shorting unit (100) is used to short-circuit the U, V, and W three-phase output terminals of the controller through a low-impedance clamp to form a single current loop during the production line testing phase. The lower bridge arm diagnostic module (210) is built into the microcontroller unit (200) of the motor controller. It is used to sequentially conduct preset cross conduction combinations, collect the phase currents calculated by the microcontroller unit (200), calculate the average current, and determine that the lower bridge arm of the phase is missing when the deviation between any phase current and the average current is greater than the first set threshold. Otherwise, the lower bridge arm is determined to pass the test. The upper bridge arm fine screening module (220), built into the microcontroller unit (200) of the motor controller, is used to perform the following operations when the lower bridge arm passes the test: sequentially conduct different combinations of upper and lower bridge arm power devices according to a preset six-step cross-conduction test sequence; after each conduction step, read the current value and perform mean filtering when the current is in steady state; calculate the equivalent impedance according to the preset scaling factor to obtain 6 sets of loop impedance information; and use the differential characteristic transformation matrix to calculate the characteristic value corresponding to each phase upper bridge arm through matrix transformation. Based on the comparison of the characteristic values ​​of each phase with the second set threshold, and whether the ratio of the characteristic values ​​of the other two phases to the maximum characteristic value falls within the preset ratio range, the upper arm weld failure is determined and the phase where the failure is located is located. The host computer communication module (300) is connected to the microcontroller unit (200) and is used to send detection start commands and receive detection results.

9. A motor controller, comprising a microcontroller unit (200), a three-phase inverter bridge arm circuit, and a power device drive circuit, characterized in that, The motor controller has a built-in detection system as described in claim 8.

10. A storage medium having a computer program stored thereon, characterized in that, When the computer program is executed by the microcontroller unit (200) of the motor controller, it implements the steps of the method according to any one of claims 1 to 7.

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