On-chip broken line detection circuit and method for fluxgate sensor
By introducing an on-chip open circuit detection circuit into the fluxgate sensor, and utilizing a current mirror and a delay detection module, highly integrated open circuit detection is achieved, solving the problems of low sensitivity and high complexity in traditional solutions, and improving the system's stability and anti-interference capability.
Patent Information
- Application Number
- CN202511060918.X
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-07-30
- Publication Date
- 2025-11-07
AI Technical Summary
Traditional fluxgate sensor off-chip open circuit detection schemes suffer from low sensitivity, high interference, and complex peripheral circuits, resulting in poor overall system performance.
An on-chip open circuit detection circuit is adopted, including an enable module, a coil drive module, a delay detection module, and an open circuit detection module. The mirror current of the coil current is obtained through a current mirror, and the open circuit detection is achieved by combining the delay judgment, thereby eliminating external interference.
It improves the integration and response speed of detection, reduces circuit complexity, optimizes the system integration and anti-interference performance, and ensures the stability of the fluxgate sensor in the zero flux state.
Smart Images
Figure CN120908718A_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The present application belongs to the technical field of broken line detection, and particularly relates to an on-chip broken line detection circuit and method for a fluxgate sensor. BACKGROUND
[0002] The fluxgate sensor is a high-precision magnetic field measuring device based on the fluxgate effect, and its core is to maintain the zero-flux state of the magnetic core through a closed-loop feedback mechanism. When the measured magnetic field exists, the sensor generates a reverse magnetic field through the compensation coil to offset its influence, thereby accurately measuring the magnetic field strength.
[0003] The fluxgate sensor system usually contains multiple groups of winding structures such as excitation coils, induction coils and compensation coils. Any open circuit failure of the coils or connections will cause signal interruption, closed loop failure and even device damage. Therefore, during the use of the fluxgate sensor system, broken line detection is often performed to ensure the reliability and safety of the system.
[0004] Traditional broken line detection schemes are generally implemented off-chip, mainly including direct current resistance monitoring method, alternating current impedance analysis method, and hardware watchdog circuit. However, the direct current resistance detection method judges the open and closed states by measuring the direct current resistance of the coil, but cannot distinguish between coil short circuit and normal state (small resistance difference), and needs to inject additional detection current, which not only interferes with the sensor operation, but also has low sensitivity and high false alarm rate. The alternating current impedance analysis method applies a high-frequency test signal to detect the open circuit by impedance change, but the fluxgate itself works in the kHz-MHz frequency band, the test signal is easily coupled with the sensor excitation, introduces noise, interferes with the compensation coil loop, and has high design complexity. The hardware watchdog circuit monitors the abnormal threshold of the coil driving current (such as zero-crossing failure), but cannot identify intermittent open circuit or high resistance fault, and has large response delay and limited coverage.
[0005] Therefore, the traditional off-chip broken line detection scheme has the technical problems of low sensitivity, large interference, complex peripheral circuit, large area, and affects the overall use effect of the system. SUMMARY
[0006] In order to solve the technical problems of low sensitivity, large interference, complex peripheral circuit, large area and affecting the overall use effect of the system of the traditional off-chip broken line detection scheme in the background art, the present application provides an on-chip broken line detection circuit and method for a fluxgate sensor.
[0007] In order to achieve the above purpose, the present application adopts the following technical scheme:
[0008] In a first aspect, the present application provides an on-chip broken line detection circuit for a fluxgate sensor, which comprises an enable module, a coil driving module, a delay detection module and a broken line detection module, wherein:
[0009] The enable module is electrically connected with the wire break detection module.
[0010] The wire break detection module is electrically connected with the coil driving module and the delay detection module.
[0011] The enable module is configured to receive an external enable signal and output an enable or disable signal to the wire break detection module.
[0012] The wire break detection module is configured to obtain a mirror current of the coil current through a current mirror, compare the output voltage of the coil driving module and the mirror current of the coil current with detection thresholds, determine a wire break state of a coil loop, and output a corresponding signal to the delay detection module.
[0013] The delay detection module is configured to perform delay determination on the output signal of the wire break detection module and output a corresponding electrical signal based on the determination result.
[0014] Optionally, the wire break detection module comprises a voltage detection unit and a current comparison unit.
[0015] The voltage detection unit is electrically connected with an output port of the coil driving module and configured to obtain a voltage value output by the output port, and activate the current comparison unit when the voltage value output by the output port is lower than a voltage detection threshold.
[0016] The current comparison unit is electrically connected with the voltage detection unit, the coil driving module and the delay detection module, and configured to obtain a mirror current of the coil current through a current mirror, detect the mirror current of the coil current, and output a corresponding signal to the delay detection module when the mirror current of the coil current is less than a current detection threshold.
[0017] Optionally, the current comparison unit is provided with a hysteresis threshold.
[0018] Optionally, the coil driving module is a Class AB driving module.
[0019] Optionally, the on-chip wire break detection circuit for the fluxgate sensor further comprises a reference clock module electrically connected with the delay detection module and configured to generate a clock signal.
[0020] The delay detection module performs delay determination based on the clock signal and the signal output by the current comparison unit, and outputs a wire break electrical signal when the duration of the signal output by the current comparison unit exceeds a preset value.
[0021] Optionally, the delay detection module comprises an edge detection unit, a frequency divider and a counter.
[0022] The edge detection unit is electrically connected with the current comparison unit and the counter;
[0023] The frequency divider is electrically connected with the reference clock module and the counter;
[0024] The edge detection unit is configured to start the counter when detecting the signal output by the current comparison unit;
[0025] The frequency divider is configured to output the clock signal after frequency division to the counter;
[0026] The counter is configured to judge whether the duration of the signal output by the current comparison unit exceeds a preset value based on the clock signal after frequency division, and output the electrical signal of disconnection when the judgment result is that the preset value is exceeded.
[0027] In a second aspect, the application provides an on-chip disconnection detection method for a fluxgate sensor, which is used in the on-chip disconnection detection circuit for a fluxgate sensor described above, and includes the following steps:
[0028] S1: enabling control: receiving an enabling signal by the enabling module, activating the detection function of the on-chip disconnection detection circuit by the enabling signal, and starting the work of the disconnection detection module;
[0029] S2: voltage threshold detection: comparing the output voltage of the coil driving module with a preset voltage detection threshold by the voltage detection unit in the disconnection detection module, and activating the current detection unit in the disconnection detection module if the output voltage of the coil driving module is less than the preset voltage detection threshold;
[0030] S3: current hysteresis judgment: using the current detection unit in the disconnection detection module to mirror sample the driving current of the coil driving module, and outputting a corresponding signal to the delay detection module by the current comparison unit when the driving current is less than the current detection threshold;
[0031] S4: delay confirmation: judging whether the duration of the signal output by the current comparison unit exceeds a preset value by the delay detection module, and outputting the electrical signal of disconnection when the judgment result is that the preset value is exceeded.
[0032] Optionally, the hysteresis judgment in the step S3 is realized by double thresholds:
[0033] That is, including a rising threshold and a falling threshold;
[0034] The rising threshold is used to detect the sudden decrease of the driving current;
[0035] The falling threshold is used to detect the abnormal increase of the driving current.
[0036] In a third aspect, the application provides a signal conditioning chip for a fluxgate sensor, wherein the signal conditioning chip is integrated with the on-chip open-circuit detection circuit described above.
[0037] In a fourth aspect, the application provides a fluxgate sensor, comprising a probe coil, a supplementary coil and the signal conditioning chip described above.
[0038] The probe coil and the supplementary coil are electrically connected to the signal conditioning chip.
[0039] The application has the following advantages:
[0040] The application provides an on-chip open-circuit detection circuit for a fluxgate sensor, which is integrated on-chip, and is started and controlled by an enabling module to ensure stable operation when the circuit is externally driven. The open-circuit detection circuit directly detects and compares the output voltage of the coil driving module and the coil current mirrored by the current mirror in real time, and outputs the open-circuit detection result after the output signal of the open-circuit detection module is delayed and judged by a delay detection module. The open-circuit detection circuit of the application has the advantages of high integration, no external circuit interference, fast response speed and low circuit complexity, eliminates the peripheral complex structure such as high-frequency test signal injection and hardware watchdog circuit in the traditional scheme, and significantly optimizes the system integration and anti-interference performance while ensuring the stability of the zero magnetic flux state of the fluxgate sensor. BRIEF DESCRIPTION OF DRAWINGS
[0041] Figure 1 FIG. 1 is a schematic diagram of the on-chip open-circuit detection circuit for a fluxgate sensor in the application;
[0042] Figure 2 FIG. 4 is a schematic diagram of the open-circuit detection module in the application;
[0043] Figure 3 FIG. 7 is a schematic diagram of the Class AB driving module in the application;
[0044] Figure 4 FIG. 10 is a schematic diagram of the delay detection module in the application. DETAILED DESCRIPTION
[0045] In order to describe the on-chip open-circuit detection circuit and method for a fluxgate sensor provided in the application, the following embodiments will be specifically explained and described.
[0046] The fluxgate sensor is a high-precision current and magnetic field measuring device based on the fluxgate effect, and its core is to maintain the zero magnetic flux state of the magnetic core through a closed-loop feedback mechanism. When the measured magnetic field exists, the sensor generates a reverse magnetic field through the compensation coil to offset its influence, thereby accurately measuring the magnetic field strength.
[0047] The magnetic flux gate sensor system usually contains multiple groups of winding structures such as excitation coils, induction coils and compensation coils. Any coil or connection failure will cause signal chain interruption, closed loop failure and even device damage. Therefore, during the use of the magnetic flux gate sensor system, wire breakage detection is often accompanied to ensure the reliability and safety of the system.
[0048] The compensation coil loop is the feedback main loop of the system. If the compensation coil is open, the zero magnetic flux state of the system will be destroyed, and the measurement accuracy will drop sharply. Therefore, the compensation coil loop wire breakage detection circuit is a key technology to ensure the reliability of the system, which is mainly used for real-time monitoring of the physical connection state of the compensation coil to prevent false output caused by insufficient driving capacity or open compensation coil.
[0049] Embodiment one
[0050] In the first aspect, referring to Figures 1 to 4 , a schematic diagram of an on-chip wire breakage detection circuit in the application is shown. The wire breakage detection circuit is used for a magnetic flux gate sensor and includes an enable module, a coil driving module, a delay detection module and a wire breakage detection module. The enable module is electrically connected to the wire breakage detection module.
[0051] The wire breakage detection module is electrically connected to the coil driving module and the delay detection module.
[0052] The enable module is used for receiving an external enable signal and outputting a start or stop signal to the wire breakage detection module.
[0053] The wire breakage detection module is used for obtaining a mirror current of a coil current through a current mirror, comparing the output voltage of the coil driving module and the mirror current of the coil current with a detection threshold value to determine the wire breakage state of the coil loop, and outputting a corresponding signal to the delay detection module.
[0054] The delay detection module is used for performing delay judgment on the output signal of the wire breakage detection module and outputting a corresponding electrical signal based on the judgment result.
[0055] In this embodiment, the on-chip wire breakage detection circuit is integrated. The enable module is used for starting control of the wire breakage detection circuit to ensure stable operation when the circuit is externally driven. The wire breakage detection module is used for real-time detection and comparison of the output voltage of the coil driving module and the mirror current of the coil current. The delay detection module is used for delay judgment on the output signal of the wire breakage detection module. The wire breakage detection result is outputted. The on-chip wire breakage detection circuit of the application has the advantages of high integration, no external circuit interference, fast response speed and low circuit complexity. The peripheral complex structure such as high-frequency test signal injection and hardware watchdog circuit in the traditional scheme is eliminated. The stability of the zero magnetic flux state of the magnetic flux gate sensor is ensured, and the system integration and anti-interference performance are significantly optimized.
[0056] Optionally, the broken line detection module in the application comprises: a voltage detection unit and a current comparison unit; wherein, the voltage detection unit is electrically connected with an output port of the coil driving module, used for acquiring a voltage value output by the output port, and when the voltage value output by the output port is lower than a voltage detection threshold, the current comparison unit is activated;
[0057] The current comparison unit is electrically connected with the voltage detection unit, the coil driving module and the delay detection module, used for acquiring a mirror current of a coil current through a current mirror, detecting the mirror current of the coil current, and when the mirror current of the coil current is less than a current detection threshold, performing inversion and outputting a corresponding signal to the delay detection module.
[0058] Optionally, the current comparison unit in the application is provided with a hysteresis threshold.
[0059] In the embodiment, the voltage detection unit is used to detect the output voltage of the coil driving module, when the output voltage is lower than a preset voltage detection threshold, the current comparison unit is activated, the current comparison unit is used to compare the current output by the coil driving module with the current detection threshold, when the current output by the coil driving module is less than the current detection threshold, inversion is performed and a signal is output to the delay detection module, the delay detection module outputs a broken line detection result after delay judgment of the output signal; the broken line detection module in the application combines voltage threshold detection and current threshold detection to form double detection, avoids mis-triggering of the current detection in use, and improves the reliability of the circuit.
[0060] Specifically, referring to Figure 2 , a schematic diagram of the broken line detection module in the application is shown, the broken line detection module is composed of a plurality of PM tubes (PMOS tubes) and a plurality of NM tubes (NMOS tubes), and the working principle is as follows: the voltage bias module Vnbias and Vncas are used to increase the anti-interference ability, generate the bias voltage Vpbias and Vpcas of the PM tube, and then control the saturation current of each branch; in use, first, the voltage value of the output port ICOMP of the driving module is detected, only when the voltage value of ICOMP is lower than the voltage detection threshold, the saturation region current of NM7 can be greater than that of PM6, NM7 has sufficient pull-down capability, PM 18 , PM 22 is in the on state, D point voltage is raised, NM 18 is in the on state, PM 26 is turned off, at this time, the current comparison unit in the broken line detection module can start detection; further, the broken line detection is mainly realized by detecting the output current of the compensation coil, through NM 10The current value of the coil NM power tube is proportionally mirrored, and the mirrored current is obtained through the NM 11 The feedback loop of R2, NM9 and NM8 realizes the addition and subtraction operation of the current, and the current is further obtained through the PM 12 and the PM 14 The current mirror structure realizes the mirroring of the current, obtains the mirrored current of the coil current, and compares the mirrored current with the preset bias current value. 12 When the saturation current value of the PM 14 , the PM 17 is greater than the bias current of the NM 12 , the pull-up ability of the PM 14 is strong enough to make the voltage value of the C point rise, the PM 19 and the NM 14 form an inverter structure, so that the F point is pulled low, the NM 17 is in the cutoff region, the PM 25 is in the on state, and the CCdig port is pulled high to output the CCdig electrical signal corresponding to the disconnection to the delay detection module.
[0061] Optionally, the coil driving module in the present application is a Class AB driving module.
[0062] In the present embodiment, the coil driving module is a Class AB driving module to realize the bidirectional driving of the compensation coil.
[0063] Further, the Class AB driving module in the present application can refer to that shown in Figure 3 , which is composed of a plurality of PM tubes (PMOS tubes) and a plurality of NM tubes (NMOS tubes), wherein, in the use process, the input tube is NM3 and NM4, to realize the bidirectional driving of the compensation coil, two groups of complementary floating gate control driving tubes (PM 14 , NM 18 ) and (PM 18 , NM 14 ) are provided, the transconductance linear loop is used to realize the static current control, and the left side of the circuit is a common mode feedback circuit, and the common mode output voltage VCM is set to VDD / 2.
[0064] Optionally, the on-chip disconnection detection circuit in the present application further comprises a reference clock module, which is electrically connected with the delay detection module and is used to generate a clock signal; the delay detection module performs delay judgment based on the clock signal and the signal output by the current comparison unit, and outputs the electrical signal of the disconnection when the duration of the signal output by the current comparison unit exceeds the preset value.
[0065] Optionally, the time delay detection module in the application comprises: an edge detection unit, a frequency divider and a counter; the edge detection unit is electrically connected with the current comparison unit and the counter; the frequency divider is electrically connected with the reference clock module and the counter; the edge detection unit is configured to start the counter when detecting the signal output by the current comparison unit; the frequency divider is configured to output the clock signal after frequency division to the counter; and the counter is configured to judge whether the duration of the signal output by the current comparison unit exceeds the preset value based on the clock signal after frequency division, and output the broken line electrical signal when the judgment result is that the preset value is exceeded.
[0066] In the embodiment, the time delay detection module compares the duration of the broken line electrical signal output by the broken line detection module with the preset time T delay , prevents the misjudgment of the circuit state caused by system disturbance, and only when the output port CCdig of the broken line detection module lasts for a high level time exceeding T delay , the chip output port error is pulled high, so that most of the modules of the chip in the fluxgate sensor stop working.
[0067] Specifically, referring to Figure 4 , the working principle of the time delay detection module is that, first, the broken line electrical signal output by the CCdig port is edge detected, when the rising edge is detected, the reference clock signal is synchronized and the enable signal rise of the counter is pulled high, the counter starts to work, if the period of the reference clock CLK is T, the period of the output clock signal CLK_N of the frequency divider is NT, the counter result counter increases by 1 after one NT time, and when the falling edge is detected, the counter is reset to zero. When the counter is greater than the count threshold counter_delay, the time delay detection module outputs CCdig_out flip to high, wherein counter_delay=T delay / NT, so as to realize the effect of detecting whether the duration of the broken line state exceeds T delay , so as to judge whether the duration of the signal output by the current comparison unit exceeds the preset value, and output the broken line electrical signal when the judgment result is that the preset value is exceeded.
[0068] Embodiment two
[0069] In a second aspect, the application further provides an on-chip broken line detection method for a fluxgate sensor, which is used for the on-chip broken line detection circuit in the first aspect, and comprises the following steps:
[0070] S1: enable control: receiving an enable signal through the enable module, activating the detection function of the on-chip broken line detection circuit through the enable signal, and starting the broken line detection module to work;
[0071] S2: voltage threshold detection: comparing the output voltage of the coil driving module with a preset voltage detection threshold by the voltage detection unit in the break detection module, if the output voltage of the coil driving module is less than the preset voltage detection threshold, the current detection unit in the break detection module is activated;
[0072] S3: current hysteresis judgment: the driving current of the coil driving module is mirror sampled by the current detection unit in the break detection module, when the driving current is less than the current detection threshold, the corresponding signal is output to the delay detection module by the current comparison unit;
[0073] S4: delay confirmation: whether the signal output by the current comparison unit exceeds the preset value is judged by the delay detection module, and the electric signal of breakage is output when the judgment result exceeds the preset value.
[0074] Optionally, the hysteresis judgment in step S3 in the application is realized by double thresholds:
[0075] That is, including the rising threshold and the falling threshold;
[0076] The rising threshold is used to detect the sudden decrease of the driving current;
[0077] The falling threshold is used to detect the abnormal increase of the driving current.
[0078] In the embodiment, a break detection method is provided for the on-chip break detection circuit in embodiment one, the break detection circuit is started and controlled by the enabling module, the stable work is ensured when the circuit is externally driven, the output voltage of the coil driving module and the coil current mirror-sampled by the current mirror are detected and compared in real time by the break detection module, and the break detection result is output after the output signal of the break detection module is delayed and judged by the delay detection module, the break detection method of the application eliminates the peripheral complex structure such as high-frequency test signal injection and hardware watchdog circuit in the traditional scheme, while ensuring the stability of the zero magnetic flux state of the fluxgate sensor, the system integration and anti-interference performance are significantly optimized.
[0079] Embodiment three
[0080] In a third aspect, the application provides a signal conditioning chip for a fluxgate sensor, and the signal conditioning chip is integrated with the on-chip break detection circuit provided in embodiment one.
[0081] In the embodiment, a signal conditioning chip is provided, and it should be noted that the on-chip break detection circuit in the embodiment is consistent with the on-chip break detection circuit in embodiment one in composition and use process, and the beneficial effects are also consistent, which will not be repeated here.
[0082] Embodiment four
[0083] In a fourth aspect, the application provides a fluxgate sensor, which comprises a probe coil, a supplementary coil and the signal conditioning chip in the third embodiment; the probe coil and the supplementary coil are electrically connected with the signal conditioning chip.
[0084] In the embodiment, a fluxgate sensor is provided, and it should be noted that the on-chip disconnection detection circuit in the embodiment and the signal conditioning chip in the fourth embodiment are consistent in composition and use process, and have consistent beneficial effects, which will not be described here.
Claims
1. An on-chip open line detection circuit for a fluxgate sensor, characterized by, The in-chip open-circuit detection circuit comprises an enabling module, a coil driving module, a delay detection module and an open-circuit detection module, wherein: The enabling module is electrically connected with the open-circuit detection module; The open-circuit detection module is electrically connected with the coil driving module and the delay detection module; The enabling module is configured to receive an external enabling signal and output an enabling or disabling signal to the open-circuit detection module; The open-circuit detection module is configured to obtain a mirror current of a coil current through a current mirror, compare an output voltage of the coil driving module and the mirror current of the coil current with detection thresholds thereof, determine an open-circuit state of a coil loop, and output a corresponding signal to the delay detection module; The delay detection module is configured to perform delay determination on the output signal of the open-circuit detection module and output a corresponding electrical signal based on a determination result.
2. The on-chip open line detection circuit for a fluxgate sensor according to claim 1, characterized in that, The open-circuit detection module comprises a voltage detection unit and a current comparison unit; The voltage detection unit is electrically connected with an output port of the coil driving module and configured to obtain a voltage value output by the output port, and activate the current comparison unit when the voltage value output by the output port is lower than a voltage detection threshold; The current comparison unit is electrically connected with the voltage detection unit, the coil driving module and the delay detection module, configured to obtain a mirror current of a coil current through a current mirror, detect the mirror current of the coil current, and output a corresponding signal to the delay detection module when the mirror current of the coil current is lower than a current detection threshold.
3. The on-chip open wire detection circuit for a fluxgate sensor of claim 2, wherein, The current comparison unit is provided with a hysteresis threshold.
4. The on-chip open wire detection circuit for a fluxgate sensor of claim 3, wherein, The coil driving module is a Class AB driving module.
5. The on-die open detection circuit of claim 4, wherein, The in-chip open-circuit detection circuit further comprises a reference clock module, which is electrically connected with the delay detection module and configured to generate a clock signal; The delay detection module performs delay determination based on the clock signal and the signal output by the current comparison unit, and outputs an open-circuit electrical signal when a duration of the signal output by the current comparison unit exceeds a preset value.
6. The on-chip open wire detection circuit for a fluxgate sensor of claim 5, wherein, The delay detection module comprises an edge detection unit, a frequency divider and a counter; The edge detection unit is electrically connected with the current comparison unit and the counter; The frequency divider is electrically connected with the reference clock module and the counter; The edge detection unit is configured to start the counter when detecting the signal output by the current comparison unit; The frequency divider is configured to output the clock signal after frequency division to the counter; The counter is configured to determine whether the duration of the signal output by the current comparison unit exceeds a preset value based on the frequency-divided clock signal, and output an open-circuit electrical signal when the determination result is that the preset value is exceeded.
7. An on-chip open line detection method for a fluxgate sensor, for the on-chip open line detection circuit of claim 6, characterized in that, The method comprises the following steps: S1: enabling control: receiving an enabling signal through the enabling module, activating the detection function of the in-chip open-circuit detection circuit through the enabling signal, and starting the open-circuit detection module to work; S2: voltage threshold detection: comparing the output voltage of the coil driving module with a preset voltage detection threshold by the voltage detection unit in the broken line detection module, if the output voltage of the coil driving module is less than the preset voltage detection threshold, activating the current detection unit in the broken line detection module; S3: current hysteresis judgment: mirroring sampling the driving current of the coil driving module by the current detection unit in the broken line detection module, when the driving current is less than the current detection threshold, outputting the corresponding signal to the delay detection module by the current comparison unit; S4: delay confirmation: judging whether the duration of the signal output by the current comparison unit exceeds the preset value by the delay detection module, and outputting the electric signal of broken line when the judgment result exceeds the preset value.
8. The on-chip open wire detection method for a fluxgate sensor according to claim 7, characterized in that, The hysteresis judgment in the step S3 is realized by double thresholds: That is, including the rising threshold and the falling threshold; The rising threshold is used to detect the sudden decrease of the driving current; The falling threshold is used to detect the abnormal increase of the driving current.
9. A signal conditioning chip for a fluxgate sensor, characterized by The signal conditioning chip is integrated with the on-chip broken line detection circuit for the magnetic flux gate sensor in claim 6.
10. A fluxgate sensor, characterized by The magnetic flux gate sensor includes a probe coil, a supplementary coil and the signal conditioning chip in claim 9; The probe coil and the supplementary coil are electrically connected with the signal conditioning chip.