Insulation detection circuit for LD pumping module

Abstract

The invention relates to the technical field of LD pumping module insulation detection scheme design, in particular to an LD pumping module insulation detection circuit. Comprising an adjustable power supply, a signal injection module and an upper computer. A laser diode in the pumping module is driven to a low-resistance state through the adjustable power supply, so that the obstruction of the non-linear characteristic to the detection is eliminated; the signal injection module injects micro-amplitude voltage signals into a positive electrode-shell double loop and a negative electrode-shell double loop, synchronously measures response current and calculates insulation resistance; and the upper computer compares the minimum value of the double-loop resistance with a threshold value to realize fault judgment. According to the method, the inherent limitation of a traditional megohmmeter in LD pumping module detection is broken through, the problem of leak detection caused by high-resistance masking is solved, and accurate insulation detection in a power-on state is achieved. The method is suitable for production inspection of the pump module and reinspection before assembly of the laser, and the product reliability and the production yield are remarkably improved.

Description

TECHNICAL FIELD

[0001] 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. BACKGROUND

[0002] At present, the insulation resistance detection of electrical and electronic products is usually implemented by using a megohmmeter or an insulation resistance tester under the condition that the product is not powered on.

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

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

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

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

[0007] Therefore, the prior art still needs to be further developed. 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: 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.

[0010] 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.

[0011] 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.

[0012] 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.

[0013] Specifically, the host computer comprises a judgment module, which is used to compare the insulation resistance value with a preset threshold to identify insulation failure.

[0014] 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 R1 according to u1 and i1, and calculates a negative electrode insulation resistance R2 according to u2 and i2.

[0015] 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.

[0016] Specifically, the driving current range of the adjustable power supply is adjustable to make the laser diode present a low resistance state.

[0017] 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, and if R is smaller than the threshold, it is determined that there is insulation failure.

[0018] 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.

[0019] 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.

[0020] Beneficial effects: 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.

[0021] 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.

[0022] 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.

[0023] 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.

[0024] 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.

[0025] 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

[0026] 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

[0027] 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 making creative efforts shall 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.

[0028] The present application will be further described below in combination with the drawings and the preferred embodiments.

[0029] 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 band series packaging. The insulation performance between the internal electrical components (such as gold band, 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 cover 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.

[0030] Please refer to Figure 1 The present application provides an LD pumping module insulation detection circuit, comprising: 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.

[0031] 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.

[0032] 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.

[0033] 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.

[0034] 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.

[0035] 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.

[0036] 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.

[0037] 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.

[0038] Specifically, the host computer comprises a determination module configured to compare the insulation resistance value with a preset threshold value to identify insulation failure.

[0039] It should be further explained that the host computer is built-in with a determination algorithm: receiving the positive insulation resistance value R1 and the negative 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.

[0040] Specifically, the signal injection module injects a first small signal voltage u1 in the positive detection loop and measures a first small signal current i1, injects a second small signal voltage u2 in the negative detection loop and measures a second small signal current i2, and calculates the positive insulation resistance R1 according to u1 and i1, and calculates the negative insulation resistance R2 according to u2 and i2.

[0041] 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 detection loop, measuring the response current i1 and calculating R1 = u1 / i1; injecting u2 with the same parameters in the negative 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.

[0042] 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.

[0043] 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.

[0044] 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.

[0045] 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 the preset threshold value, and if R is smaller than the threshold value, it is determined as insulation failure.

[0046] 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. The beneficial effect is that the worst insulation point is focused, the misjudgment caused by the residual impedance of part of the laser tube is avoided, and the fault detection rate is improved to more than 99%.

[0047] 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.

[0048] 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. The beneficial effect is that the modular circuit design ensures the anti-interference ability of small signal measurement, and the 24-bit ADC realizes microampere-level current resolution and high-sensitivity detection.

[0049] 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.

[0050] 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.

[0051] The adjustable power supply adjusts its output voltage and current according to the pumping module to be detected, 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.

[0052] The signal injection module has three detection output ends, which are connected with the positive electrode, the negative electrode and the shell of the LD pumping module respectively, forming two detection circuits of the positive electrode detection circuit and the negative electrode detection circuit. When performing detection, small signal voltages u1 and u2 are injected into the positive electrode detection circuit and the negative electrode detection circuit respectively, and the small signal currents i1 and i2 formed by the small signal voltages in the positive electrode detection circuit and the negative electrode detection circuit are detected. The resistance values R1 and R2 of the positive electrode detection circuit and the negative electrode 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 of the insulation fault point detected by the positive electrode detection circuit and the negative electrode detection circuit.

[0053] Considering that the insulation fault point occurs randomly, the number of semiconductor laser diodes in series in the positive electrode detection circuit and the negative electrode detection circuit may not be consistent, and therefore the values of R1 and R2 may be different, and the smaller value can better reflect the insulation resistance of the insulation fault point.

[0054] 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.

[0055] 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 detection in this state, effectively solving the problem that the semiconductor laser diode presents a high resistance characteristic under the traditional insulation resistance detection method, so that the traditional detection method cannot effectively detect the insulation resistance of the LD pumping module, and realizing effective detection of the insulation resistance of the LD pumping module and effective identification of insulation faults.

[0056] It can be understood that the scheme provides a circuit principle and a technical approach to solve the problem that the high resistance characteristic of the laser diode under low current hinders insulation detection. 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 tester cannot effectively detect the insulation resistance of the LD pumping module, and realizing effective detection of the insulation resistance of the LD pumping module and effective identification of insulation faults.

[0057] The above-described technical features 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 specification, as long as such a combination does not contradict.

[0058] The above description of the specific embodiments of the present application is not intended to limit the scope of the present application. Any other corresponding changes and modifications made according to the technical concept of the present application should be included in the scope of protection of the claims of the present application.

Claims

1. An LD pump module insulation detection circuit, characterized in that: It includes an adjustable power supply and a signal injection module. The adjustable power supply is used to provide a driving current to the LD pump module to make the laser diode present 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.

2. The LD pump module insulation detection circuit 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 LD pump module insulation detection circuit according to claim 1, characterized in that: The signal injection module includes three detection output terminals, which are respectively configured to be connected to the positive electrode, the negative electrode and the shell of the LD pump module to form a positive electrode detection loop and a negative electrode detection loop.

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

5. The LD pump module insulation detection circuit according to claim 2, characterized in that: The host computer includes a determination module for comparing the insulation resistance value with a preset threshold value to identify an insulation fault.

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

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

9. The LD pump module insulation detection circuit according to claim 5, characterized in that: 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 determine that an insulation fault occurs if R is less than the threshold value.

10. The LD pump module insulation detection circuit 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, and transmits the signal to the host computer through an analog-to-digital converter.

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

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