An LD pumping module insulation detection circuit

Abstract

The present application relates to the technical field of LD pumping module insulation detection scheme design, and particularly relates to an LD pumping module insulation detection circuit. The LD pumping module insulation detection circuit comprises an adjustable power supply, a signal injection module and an upper computer. The adjustable power supply drives the laser diode in the pumping module to a low resistance state, eliminating the hindrance of the nonlinear characteristics of the pumping module to the detection; the signal injection module injects a micro-voltage signal into the positive shell and the negative shell double circuit, synchronously measures the response current and calculates the insulation resistance; the upper computer compares the minimum value of the double circuit resistance with a threshold value to realize fault determination. The method breaks through the inherent limitations of the traditional megohmmeter in the detection of the LD pumping module, solves the problem of missed detection caused by high resistance masking, and realizes accurate insulation detection under the power-on state. The present application is suitable for pumping module production inspection and laser pre-assembly reinspection, and significantly improves the product reliability and production yield.

Description

TECHNICAL FIELD

[0001] The present application relates to a kind of LD pumping module insulation detection scheme design technical field, specifically to a kind of LD pumping module insulation detection circuit. BACKGROUND

[0002] At present, the insulation resistance value detection of electrical and electronic products is usually carried out under the condition that the product is not powered on, using megohmmeter or insulation resistance tester for detection.

[0003] The detection by megohmmeter or insulation resistance tester is not suitable for LD pumping module detection.

[0004] LD pumping module is packaged by several to several tens of laser diodes in series array, and the laser diodes in series array are connected by gold belt, as shown in Figure 1 Due to the defects caused by occasional factors in the production process, there may be insulation failure between the electrical parts such as gold belt in LD pumping module and the module shell, resulting in reduced insulation performance or even short circuit, which has adverse effects on the application of LD pumping.

[0005] The laser diode in LD pumping module belongs to a kind of semiconductor light-emitting diode, which has typical nonlinear volt-ampere characteristic. The impedance characteristic presented by semiconductor light-emitting diode is defined by R=U / I. Since it has nonlinear volt-ampere characteristic, the smaller the current I passing through the semiconductor light-emitting diode, the larger the ratio of U and I, and the larger the resistance presented to the outside.

[0006] The megohmmeter or insulation resistance tester used for conventional insulation detection has very small driving current capacity, only several mA or even several hundred uA, for the purpose of protecting the measured equipment. When megohmmeter or insulation resistance tester is used to detect the insulation resistance value of LD pumping module, if insulation failure occurs in the middle of laser diode series array, whether the positive electrode-shell insulation resistance value or the negative electrode-shell insulation resistance value of the LD pumping module is tested, part of the semiconductor laser diode will be connected in the test circuit. Due to the limitation of driving current capacity of megohmmeter or insulation resistance tester, the current in the test circuit is only several mA or even several hundred uA. Due to the nonlinear volt-ampere characteristic of laser diode, the laser diode in the test circuit presents high resistance at this time, so that the insulation resistance value detected by megohmmeter or insulation resistance tester is a high resistance value, and the low resistance value or even short circuit characteristic of the insulation failure point is covered up, so that the insulation failure cannot be effectively identified. The insulation failure cannot be effectively identified in production or before use, which may cause the insulation failure of LD pumping module to be discovered after being installed in laser and causing abnormality or failure, resulting in great economic loss.

[0007] Therefore, the prior art still needs further development. SUMMARY

[0008] The present application aims to overcome the above technical deficiencies, and provide an LD pumping module insulation detection circuit to solve the problems existing in the prior art.

[0009] To achieve the above technical purpose, according to the first aspect of the present application, the present application provides an LD pumping module insulation detection circuit, comprising:

[0010] The adjustable power supply is used to provide a driving current to the LD pumping module to make the laser diode present a low resistance state, and the signal injection module is used to inject a small signal voltage in the low resistance state and measure a response current to calculate an insulation resistance value.

[0011] Specifically, it further comprises a host computer, which is in communication connection with the signal injection module, and is used to receive and display the insulation resistance value.

[0012] Specifically, the signal injection module comprises three detection output ends, which are respectively configured to be connected to the positive electrode, the negative electrode and the shell of the LD pumping module, forming a positive electrode detection loop and a negative electrode detection loop.

[0013] Specifically, the adjustable power supply can adjust the output voltage and the output current to adapt to the driving requirements of different LD pumping modules.

[0014] Specifically, the host computer comprises a judgment module, which is used to compare the insulation resistance value with a preset threshold value to identify insulation failure.

[0015] Specifically, the signal injection module injects a first small signal voltage u1 and measures a first small signal current i1 in the positive electrode detection loop, injects a second small signal voltage u2 and measures a second small signal current i2 in the negative electrode detection loop, and calculates a positive electrode insulation resistance value R1 according to u1 and i1, and calculates a negative electrode insulation resistance value R2 according to u2 and i2.

[0016] Specifically, the amplitudes of the first small signal voltage u1 and the second small signal voltage u2 are smaller than the output voltage of the adjustable power supply, so as to avoid interfering with the low resistance state of the laser diode.

[0017] Specifically, the driving current range of the adjustable power supply is adjustable, so as to make the laser diode present a low resistance state.

[0018] Specifically, the judgment module is configured to take the smaller value of R1 and R2 as the final insulation resistance value R, and compare R with the preset threshold value, and if R is smaller than the threshold value, it is determined as insulation failure.

[0019] Specifically, the signal injection module includes a voltage injection unit and a current detection unit, the voltage injection unit generates u1 and u2, the current detection unit measures i1 and i2, and the signals are transmitted to the host computer through an analog-to-digital converter.

[0020] Specifically, the electrical circuit resistance in the positive electrode detection circuit and the negative electrode detection circuit is known, and the resistance value of the laser diode in the low resistance state is lower than 10Ω.

[0021] Beneficial effects:

[0022] 1. Eliminate high resistance masking effect: through the adjustable power supply to provide sufficient driving current, force the laser diode to enter the saturated conduction state, so that the dynamic resistance is reduced to a negligible level, and the fault point masking problem caused by the high resistance characteristics of the laser tube in the traditional method is fundamentally eliminated.

[0023] 2. Double-circuit full-range coverage: The signal injection module detects the positive electrode-shell and the negative electrode-shell double circuit, and no matter where the insulation fault point is located, such as near the electrode, the middle or the gold belt of the series array, it can be accurately positioned through the double resistance value comparison.

[0024] 3. Intelligent decision-making anti-misjudgment: The minimum value of the double-circuit resistance is used as the basis for judgment, which avoids the measurement deviation caused by the residual impedance of part of the laser tube or the asymmetry of the circuit, and significantly improves the fault recognition accuracy.

[0025] 4. Micro-perturbation safe detection: The small signal voltage injection amplitude is strictly limited within a small proportion of the main power output, which ensures that the operating point of the laser tube does not deviate, and realizes non-destructive detection in the power-on state.

[0026] 5. Full-process efficiency optimization: From the driving current loading to the fault judgment, the automation processing is realized, the time consumption of single detection is significantly lower than that of manual operation mode, and the high-speed inspection demand of the production line is met.

[0027] 6. Self-adaptive strong compatibility: The adjustable power supply has a wide range of output to adapt to different specifications of pumping modules, and the judgment threshold can be dynamically adjusted according to product standards, which is suitable for all scenes such as research and development verification, production line quality inspection and customer end re-inspection. BRIEF DESCRIPTION OF DRAWINGS

[0028] Figure 1 It is a circuit connection schematic diagram of the LD pumping module insulation detection circuit provided in the embodiment of the present application. DETAILED DESCRIPTION

[0029] In order for the personnel in the art to better understand the technical solutions of the present application, the technical solutions of the present application will be described clearly and completely below in combination with the drawings of the present application. Based on the embodiments in the present application, other similar embodiments obtained by the personnel in the art without creative labor should belong to the protection scope of the present application. In addition, the direction words mentioned in the following embodiments, such as “up”, “down”, “left”, “right” and the like are only the directions of the drawings, therefore, the direction words used are used for illustration but not for limiting the present application.

[0030] The present application will be further described below in combination with the drawings and the preferred embodiments.

[0031] First of all, it needs to be pointed out that the laser diode (LD) pumping module as the core energy source of the fiber laser is usually composed of a plurality of laser tubes through gold ribbon series packaging. The insulation performance between the internal electrical components (such as gold ribbon, electrode) and the metal shell directly affects the safety of the whole machine. The traditional insulation detection adopts megohmmeter or insulation resistance tester. This method is effective when detecting conventional linear resistor devices, but it has a fundamental defect when facing the LD pumping module. The reason is that the semiconductor laser diode has a significant non-linear voltage-current characteristic, and presents a very high impedance (up to megohm level) under the microampere level driving current provided by the megohmmeter. If the insulation fault point is located in the middle of the laser tube series array, part of the laser tube will be inevitably connected in the detection circuit, and its high impedance characteristic will completely mask the low impedance state of the actual insulation fault point, resulting in distorted test results. The existing technology cannot distinguish the resistance of the fault point and the impedance of the laser tube, causing missed detection of insulation faults. Such hidden dangers may cause short circuit accidents after the module is installed, which may cause the laser to shut down, or even burn the optical components. The industry urgently needs an insulation detection scheme for the special structure of the LD pumping module to realize accurate fault identification under the premise of safety.

[0032] Referring to Figure 1 The present application provides an LD pumping module insulation detection circuit, comprising:

[0033] The adjustable power supply is used to provide driving current to the LD pumping module to make the laser diode present a low resistance state, and the signal injection module is used to inject a small signal voltage in the low resistance state and measure the response current to calculate the insulation resistance value.

[0034] It needs to be further explained that the embodiment provides an LD pumping module insulation detection circuit, which is composed of an adjustable power supply and a signal injection module. The adjustable power supply outputs a driving current to the LD pumping module, so that the laser diode in series in the module enters a conduction state (i.e. a low resistance state, typically less than 10Ω); the signal injection module injects a small signal voltage into the detection circuit when the laser diode is in a low resistance state, and synchronously measures the response current, and calculates the insulation resistance value through Ohm's law. Its beneficial effect lies in: by forcing the laser diode to a low resistance state, the problem of traditional megohm meters masking insulation failure due to insufficient driving current causing the laser tube to present high resistance characteristics (>1MΩ) is completely avoided, and effective identification of insulation failure between the gold belt and the shell inside the pumping module is realized.

[0035] Specifically, it also includes a host computer, which is in communication connection with the signal injection module, and is used for receiving and displaying the insulation resistance value.

[0036] It needs to be further explained that the host computer is in communication connection with the signal injection module. The signal injection module transmits the calculated insulation resistance value to the host computer in real time, and the host computer displays the resistance value and the fault determination result through the human-machine interface. Its beneficial effect lies in: a closed-loop detection system is constructed, visual processing of detection data is realized, it is convenient for the operator to quickly judge the product quality, and the detection efficiency of the production line is improved.

[0037] Specifically, the signal injection module includes three detection output ends, which are respectively configured to be connected to the positive electrode, the negative electrode and the shell of the LD pumping module, to form a positive electrode detection circuit and a negative electrode detection circuit.

[0038] It needs to be further explained that the signal injection module is provided with three detection output ends: the first output end is connected to the positive electrode of the LD pumping module, the second output end is connected to the negative electrode, and the third output end is connected to the metal shell. Thereby, a positive electrode detection circuit (from the positive electrode to the shell) and a negative electrode detection circuit (from the negative electrode to the shell) are formed. Its beneficial effect lies in: the double-circuit design can cover any position where insulation failure may occur (such as near the positive electrode, near the negative electrode or in the middle of the series array), avoiding the single-point detection blind area.

[0039] Specifically, the adjustable power supply can adjust the output voltage and the output current to adapt to the driving requirements of different LD pumping modules.

[0040] It needs to be further explained that the adjustable power supply adopts a digital control voltage source, and the output voltage range is 0-100V and the output current range is 0-50A adjustable. When operating, the power supply parameters are set according to the rated working voltage and current of the LD pumping module to be tested (for example: 30V / 10A module), so as to ensure that the laser diode reaches a saturated conduction state. Its beneficial effect lies in: adapting to the detection requirements of pumping modules of different specifications, having strong universality, and accurately driving to ensure the stability of the low resistance state.

[0041] Specifically, the host computer comprises a determination module configured to compare the insulation resistance value with a preset threshold value to identify insulation failure.

[0042] It should be further explained that the host computer is built-in with a determination algorithm: receiving the positive electrode insulation resistance value R1 and the negative electrode insulation resistance value R2 uploaded by the signal injection module, comparing the two values and taking the minimum value as the final insulation resistance value R; if R is lower than the preset threshold value (such as 100 kΩ), an insulation failure alarm is triggered. The beneficial effect is that the automatic determination mechanism avoids manual misjudgment, and the preset threshold value can be flexibly adjusted according to product standards to ensure the consistency of quality control.

[0043] Specifically, the signal injection module injects a first small signal voltage u1 in the positive electrode detection loop and measures a first small signal current i1, injects a second small signal voltage u2 in the negative electrode detection loop and measures a second small signal current i2, and calculates the positive electrode insulation resistance value R1 according to u1 and i1, and calculates the negative electrode insulation resistance value R2 according to u2 and i2.

[0044] It should be further explained that the signal injection module performs double-loop synchronous detection: injecting a first small signal voltage u1 with an amplitude of 10 mV and a frequency of 1 kHz in the positive electrode detection loop, measuring the response current i1 and calculating R1 = u1 / i1; injecting u2 with the same parameters in the negative electrode detection loop, measuring i2 and calculating R2 = u2 / i2. The beneficial effect is that the small signal injection method (<100 mV) does not interfere with the main drive loop of the adjustable power supply, ensuring that the laser tube maintains a low resistance state while achieving high-precision measurement of the insulation resistance value.

[0045] Specifically, the amplitudes of the first small signal voltage u1 and the second small signal voltage u2 are smaller than the output voltage of the adjustable power supply, so as to avoid interfering with the low resistance state of the laser diode.

[0046] Specifically, the drive current range of the adjustable power supply can be adjusted according to the measured LD module, so that the laser diode presents a low resistance state.

[0047] It should be further explained that the drive current of the adjustable power supply is adjustable, and the current range makes the dynamic resistance of the laser diode drop below 10Ω. The beneficial effect is that it ensures reliable conduction of the laser tube and maximizes the elimination of high resistance masking effect.

[0048] Specifically, the determination module is configured to take the smaller value of R1 and R2 as the final insulation resistance value R, and compare R with a preset threshold value, and if R is smaller than the threshold value, it is determined as insulation failure.

[0049] It needs to be further explained that the determination module executes the "minimum priority" logic: after comparing R1 and R2, the smaller value is selected as R. If R is less than or equal to 50kΩ (an adjustable preset threshold), it is determined to be an insulation fault; if R is greater than 50kΩ, it is determined to be qualified. Its beneficial effect lies in: focusing on the worst insulation point, avoiding misjudgment caused by the residual impedance of part of the laser tube, and improving the fault detection rate to more than 99%.

[0050] Specifically, the signal injection module includes a voltage injection unit and a current detection unit, the voltage injection unit generates u1 and u2, the current detection unit measures i1 and i2, and the signal is transmitted to the host computer through an analog-to-digital converter.

[0051] It needs to be further explained that the hardware structure of the signal injection module includes: a voltage injection unit (generating accurate u1 / u2 based on a DAC chip), a current detection unit (converting i1 / i2 into a voltage signal based on a high-precision operational amplifier and a sampling resistor), and an analog-to-digital converter (24-bit ADC digitizes analog signals). Digital signals are transmitted to the host computer through an SPI interface. Its beneficial effect lies in: modular circuit design ensures the anti-interference ability of small signal measurement, 24-bit ADC realizes microampere-level current resolution, and realizes high-sensitivity detection.

[0052] Specifically, the electrical circuit resistance in the positive and negative detection circuits is known, and the resistance value of the laser diode in the low resistance state is less than 10Ω.

[0053] It can be understood that the present application realizes the function of effectively identifying the insulation fault of the LD pumping module by a circuit of a signal injection module cooperating with an adjustable power supply, as shown in Figure 1 The LD pumping module insulation detection circuit is composed of an adjustable power supply, a signal injection module and a host computer.

[0054] The adjustable power supply adjusts its output voltage and current according to the required detection of the pumping module, so as to provide a large enough driving current for the semiconductor laser diode in the LD pumping module, so that the semiconductor laser diode presents a low resistance state.

[0055] The signal injection module has three detection output ends, which are connected with the positive pole, the negative pole and the shell of the LD pumping module respectively, forming two detection circuits of the positive pole detection circuit and the negative pole detection circuit. When performing detection, small signal voltages u1 and u2 are injected into the positive pole detection circuit and the negative pole detection circuit respectively, and the small signal currents i1 and i2 formed by the small signal voltages in the positive pole detection circuit and the negative pole detection circuit are detected. The resistance values R1 and R2 of the positive pole detection circuit and the negative pole detection circuit can be calculated according to u1, u2, i1 and i2. Considering that the resistance values of the test cable and the LD pumping circuit are very small and can be ignored, and the semiconductor laser diode in the LD pumping module presents a low resistance characteristic under the driving of the adjustable power supply, R1 and R2 reflect the insulation resistance values of the insulation fault points detected by the positive pole detection circuit and the negative pole detection circuit.

[0056] Considering that the insulation fault point occurs randomly, the number of semiconductor laser diodes in series in the positive pole detection circuit and the negative pole detection circuit may be inconsistent, and therefore the values of R1 and R2 may be different, and the smaller value can better reflect the insulation resistance value of the insulation fault point.

[0057] The smaller value of R1 and R2 is taken as the final detection value R, which is uploaded to the host computer for display, and whether there is an insulation fault is determined according to the threshold preset by the host computer.

[0058] It can be understood that the scheme drives the semiconductor laser diode to a low resistance state by setting an appropriate adjustable power supply, and then uses the signal injection module to inject a small signal voltage to implement insulation resistance value detection in this state, effectively solving the problem that the semiconductor laser diode presents a high resistance characteristic under the traditional insulation resistance value detection method, so that the traditional detection method cannot effectively detect the insulation resistance value of the LD pumping module, and realizing effective detection of the insulation resistance value of the LD pumping module and effective identification of insulation faults.

[0059] It can be understood that the present application provides a circuit principle and a technical approach to solving the problem that the high resistance characteristic of the laser diode under low current hinders insulation detection.

[0060] It can be understood that the technical effects and advantages include solving the problem that the traditional detection method using a megohmmeter or an insulation resistance value tester cannot effectively detect the insulation resistance value of the LD pumping module, and realizing effective detection of the insulation resistance value of the LD pumping module and effective identification of insulation faults.

[0061] The technical features described above can be combined arbitrarily. Although all possible combinations of these technical features are not described, any combination of these technical features should be considered to be covered by the present application, as long as there is no contradiction in such a combination.

[0062] The above description of the specific embodiments of the present application is not intended to limit the scope of the present application. Various other corresponding changes and modifications according to the technical concept of the present application should be included in the scope of the present application claimed.

Claims

1. An insulation detection circuit for an LD pump module, characterized in that, It includes an adjustable power supply and a signal injection module. The adjustable power supply is used to provide a drive current to the LD pump module so that the laser diode presents a low resistance state. The signal injection module is used to inject a small signal voltage in the low resistance state and measure the response current to calculate the insulation resistance value.

2. The insulation detection circuit for the LD pump module according to claim 1, characterized in that, It also includes a host computer, which is communicatively connected to the signal injection module and is used to receive and display the insulation resistance value.

3. The insulation detection circuit for the LD pump module according to claim 2, characterized in that, The signal injection module includes three detection output terminals, which are respectively configured to be connected to the positive terminal, negative terminal, and outer casing of the LD pump module, forming a positive detection circuit and a negative detection circuit.

4. The insulation detection circuit for the LD pump module according to claim 1, characterized in that, The adjustable power supply can adjust the output voltage and output current to adapt to the driving requirements of different LD pump modules.

5. The insulation detection circuit for the LD pump module according to claim 2, characterized in that, The host computer includes a judgment module, which is used to compare the insulation resistance value with a preset threshold to identify insulation faults.

6. The insulation detection circuit for the LD pump module according to claim 3, characterized in that, The signal injection module injects a first small signal voltage u1 into the positive detection circuit and measures a first small signal current i1. It injects a second small signal voltage u2 into the negative detection circuit and measures a second small signal current i2. Based on u1 and i1, it calculates the positive insulation resistance value R1 and the negative insulation resistance value R2.

7. The insulation detection circuit for the LD pump module according to claim 6, characterized in that, The amplitudes of the first small-signal voltage u1 and the second small-signal voltage u2 are smaller than the output voltage of the adjustable power supply to avoid interfering with the low-resistance state of the laser diode.

8. The insulation detection circuit for the LD pump module according to claim 4, characterized in that, The driving current range of the adjustable power supply is adjustable so that the laser diode presents a low resistance state.

9. The insulation detection circuit for the LD pump module according to claim 5, characterized in that, The determination module is configured to take the smaller value between R1 and R2 as the final insulation resistance value R, and compare R with a preset threshold. If R is less than the threshold, it is determined to be an insulation fault.

10. The insulation detection circuit for the LD pump module according to claim 6, characterized in that, The signal injection module includes a voltage injection unit and a current detection unit. The voltage injection unit generates u1 and u2, and the current detection unit measures i1 and i2. The signals are then transmitted to the host computer via an analog-to-digital converter.

11. The insulation detection circuit for the LD pump module according to claim 3, characterized in that, The electrical circuit resistances in the positive and negative detection circuits are known, and the resistance of the laser diode in a low-resistance state is less than 10Ω.

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