Low-ripple constant-current source driving circuit for laser

Abstract

The invention provides a low-ripple constant current source driving circuit for a laser, and relates to the technical field of laser driving, the low-ripple constant current source driving circuit comprises a direct current converter, an LCL filter circuit, a laser load and a current feedback circuit, an external power supply converts the direct current into stable direct current through the direct current converter, and the direct current is output by the direct current converter; direct current is input into the LCL filter circuit, current ripples in the direct current can be effectively reduced through an LCL filter, transient over-current peaks are restrained, then stable low-ripple driving current is formed, and a laser load is stably driven to operate. Secondly, sampling the actual current of the input end of the laser load in real time through a current feedback circuit, comparing the condition of the sampled actual current of the input end of the laser load with a set value, then calculating a control quantity, and adjusting the current output of the direct-current converter in real time through the calculated control quantity; and the stability of the laser during load operation is ensured.

Description

Technical Field

[0001] The invention relates to the technical field of laser driving, and in particular to a low-ripple constant current source driving circuit for a laser. Background Art

[0002] High-power lasers are widely used in industrial processing, communications, medical treatment, national defense and military industries, and other fields. The laser driver power supply is responsible for driving, controlling and protecting the laser. The quality of its technical performance directly affects the light source quality, reliability and service life of the laser system.

[0003] There are a large number of switching frequency subharmonics in the DC voltage output by the laser driver power supply. The structure in which the load is connected in parallel at both ends of the output capacitor makes the load current ripple largely dependent on the load resistance. The laser is a load with a very small on-state resistance. Even if the voltage ripple amplitude of the capacitor filter is very small, it may cause a large current ripple. This makes the capacitor filter power supply unable to fully meet the low current ripple requirements of the laser for the driver power supply. However, the stability of the laser current directly affects the stability of the laser output optical power. Therefore, the laser driver power supply output should reduce the ripple factor and improve the current stability. Summary of the invention

[0004] The present invention provides a low-ripple constant current source driving circuit for a laser. In order to solve the technical problem that the existing capacitor filter causes a large current ripple and cannot fully meet the laser's requirement for low current ripple of the driving power supply, an LCL filtering circuit is arranged between a DC converter and a laser load to effectively reduce the current ripple and suppress transient overcurrent spikes, thereby achieving the technical effect of stably driving the laser.

[0005] The embodiment of the present application provides a low ripple constant current source driving circuit for a laser, comprising:

[0006] A DC converter for providing a stable DC power supply;

[0007] An LCL filter circuit, wherein an input end of the LCL filter circuit is coupled to an output end of the DC converter, and is used for filtering the DC power output by the DC converter;

[0008] A laser load, wherein the laser load is arranged at an output end of the LCL filter circuit;

[0009] A current feedback circuit, wherein the sampling end of the current feedback circuit is coupled to the input end of the laser load, and the feedback end of the current feedback circuit is coupled to the DC converter, for sampling the actual current at the input end of the laser load and adjusting the DC power supply output by the DC converter according to the sampling result.

[0010] In some embodiments, the LCL filter circuit includes an inductor L1, a capacitor C1 and an inductor L2, the first end of the inductor L1 is coupled to the positive terminal of the DC converter, the first end of the inductor L2 is coupled to the second end of the inductor L1, the second end of the inductor L2 is coupled to the first end of the laser load, the second end of the laser load is coupled to the negative electrode of the DC converter, the first end of the capacitor C1 is coupled to the connecting part of the inductor L1 and the inductor L2, and the second end of the capacitor C1 is coupled to the negative electrode of the DC converter.

[0011] In some embodiments, a capacitor voltage differential feedback circuit is further included, a sampling end of the capacitor voltage differential feedback circuit is coupled to the first end of the capacitor C1, and a feedback end of the capacitor voltage differential feedback circuit is coupled to the DC converter.

[0012] In some embodiments, it also includes:

[0013] MOS tube Q1, the second end of the laser load is coupled to the negative electrode of the DC converter through the MOS tube Q1, the drain of the MOS tube Q1 is coupled to the negative end of the DC converter, and the source of the MOS tube Q1 is coupled to the second end of the laser load.

[0014] A voltage-slow-rise driving module, wherein the gate of the MOS tube Q1 is coupled to the output end of the voltage-slow-rise driving module, and the input end of the voltage-slow-rise driving module is coupled to the first end of the capacitor C1;

[0015] A start-stop signal receiving circuit, wherein the signal receiving end of the voltage ramp-up driving module is coupled to the signal output end of the start-stop signal receiving circuit. When the start-stop signal receiving circuit receives an external start signal, the start-stop signal receiving circuit controls the output voltage of the output end of the voltage ramp-up driving module to increase linearly.

[0016] In some embodiments, it also includes:

[0017] A resistor R1, a first end of the resistor R1 is coupled to a first end of the inductor L2;

[0018] A MOS tube Q2, wherein a drain of the MOS tube Q2 is coupled to the second end of the resistor R1, and a source of the MOS tube Q2 is coupled to the second end of the laser load;

[0019] A fast shutdown driving module, wherein the output end of the fast shutdown driving module is coupled to the gate of the MOS tube Q2, and the signal receiving end of the fast shutdown driving module is coupled to the signal output end of the start-stop signal receiving circuit. When the start-stop signal receiving circuit receives an external stop signal, the fast shutdown driving module controls the drain and source of the MOS tube Q2 to be turned on.

[0020] In some embodiments, a diode D3 is further included, wherein an anode of the diode D3 is coupled to the second end of the inductor L2 , and a cathode of the diode D3 is coupled to the first end of the inductor L1 .

[0021] In some embodiments, the start / stop signal receiving circuit includes:

[0022] A signal receiving circuit, used for receiving an external stop signal or an external start signal;

[0023] A synchronization circuit, wherein the output end of the signal receiving circuit is coupled to the input end of the synchronization circuit, and the signal receiving ends of the voltage ramp-up driving module and the fast shutdown driving module are both coupled to the output end of the synchronization circuit;

[0024] Among them, at least one of the synchronization circuits is arranged at the output end of the signal receiving circuit, and when a plurality of groups of the synchronization circuits are arranged at the output end of the signal receiving circuit, the plurality of groups of the synchronization circuits are arranged in parallel at the output end of the signal receiving circuit.

[0025] In some embodiments, a diode D4 is further included. The diode D4 is arranged at the input end of the synchronization circuit, the anode of the diode D4 is coupled to the input end of the synchronization circuit, and the cathode of the diode D4 is coupled to the output end of the signal receiving circuit.

[0026] In some embodiments, the signal receiving circuit includes a voltage source V1, a voltage source V2, a resistor R3, a resistor R4, a resistor R5, a resistor R6, a capacitor C3, a transistor Q3 and a relay Q4, a first end of the resistor R4 is coupled to a signal receiving end for receiving an external start / stop signal, a second end of the resistor R4 is coupled to a base of the transistor Q3, a first end of the resistor R3 is coupled to a first end of the resistor R4, a second end of the resistor R3 is coupled to the voltage source V1, one end of the capacitor C3 is coupled to the second end of the resistor R4, the other end of the capacitor C3 is grounded, the resistor R5 is connected in parallel with the capacitor C3, the emitter of the transistor Q3 is grounded, the collector of the transistor Q3 is coupled to a first end of a coil in the relay Q4, a first end of the resistor R6 is coupled to a second end of the coil in the relay Q4, a second end of the resistor R6 is coupled to the voltage source V2, and an input end of the synchronization circuit is coupled to a contact in the relay Q4.

[0027] In some embodiments, the signal receiving circuit includes a voltage source V1, a voltage source V2, a resistor R3, a resistor R4, a resistor R5, a resistor R6, a capacitor C3, a transistor Q3 and an optocoupler Q4, the first end of the resistor R4 is coupled to the signal receiving end for receiving an external start / stop signal, the second end of the resistor R4 is coupled to the base of the transistor Q3, the first end of the resistor R3 is coupled to the first end of the resistor R4, the second end of the resistor R3 is coupled to the voltage source V1, one end of the capacitor C3 is coupled to the second end of the resistor R4, the other end of the capacitor C3 is grounded, the resistor R5 is connected in parallel with the capacitor C3, the emitter of the transistor Q3 is grounded, the collector of the transistor Q3 is coupled to the anode of the light-emitting diode in the optocoupler Q4, the first end of the resistor R6 is coupled to the cathode of the light-emitting diode in the optocoupler Q4, the second end of the resistor R6 is coupled to the voltage source V2, and the input end of the synchronization circuit is coupled to the phototransistor in the optocoupler Q4.

[0028] Beneficial effect: The present application provides a low-ripple constant current source driving circuit for a laser. In the embodiment of the present application, after the external power supply is output to the DC converter, it is converted into a stable DC current by the DC converter and output by the DC converter. After the DC current is output from the DC converter, it will be input into the LCL filter circuit. The LCL filter can effectively reduce the current ripple in the DC current and suppress transient overcurrent spikes, thereby forming a stable low-ripple driving current, thereby stably driving the laser load to operate. Secondly, in the present embodiment, a current feedback circuit is also provided. The feedback end of the current feedback circuit can sample the actual current of the input end of the laser load in real time, and calculate the control amount after comparing the actual current of the sampled laser load input end with the set value. The current output of the DC converter is adjusted in real time by the control amount obtained after calculation, thereby ensuring the stability of the laser load during operation. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 A framework diagram of a low ripple constant current source driving circuit for a laser provided by an embodiment of the present invention;

[0030] Figure 2 A schematic diagram of a synchronous control circuit is provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0031] The following embodiments of the technical solution of the present application are described in detail in conjunction with the accompanying drawings. The following embodiments are only used to more clearly illustrate the technical solution of the present application, and are therefore only used as examples, and cannot be used to limit the scope of protection of the present application.

[0032] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by technicians in the technical field to which this application belongs; the terms used herein are only for the purpose of describing specific embodiments and are not intended to limit this application; the terms "including" and "having" in the specification and claims of this application and the above-mentioned figure descriptions and any variations thereof are intended to cover non-exclusive inclusions.

[0033] In the description of the embodiments of the present application, the technical terms "first", "second", etc. are only used to distinguish different objects, and cannot be understood as indicating or implying relative importance or implicitly indicating the number, specific order or primary and secondary relationship of the indicated technical features. In the description of the embodiments of the present application, the meaning of "multiple" is more than two, unless otherwise clearly and specifically defined.

[0034] Reference to "embodiments" herein means that a particular feature, structure, or characteristic described in conjunction with the embodiments may be included in at least one embodiment of the present application. The appearance of the phrase in various locations in the specification does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment that is mutually exclusive with other embodiments. It is explicitly and implicitly understood by those skilled in the art that the embodiments described herein may be combined with other embodiments.

[0035] In the description of the embodiments of the present application, the term "and / or" is only a description of the association relationship of associated objects, indicating that three relationships may exist. For example, A and / or B can represent: A exists alone, A and B exist at the same time, and B exists alone. In addition, the character " / " in this article generally indicates that the associated objects before and after are in an "or" relationship.

[0036] In the description of the embodiments of the present application, the term "multiple" refers to more than two (including two). Similarly, "multiple groups" refers to more than two groups (including two groups), and "multiple pieces" refers to more than two pieces (including two pieces).

[0037] In the description of the embodiments of the present application, the technical terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc. indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, which are only for the convenience of describing the embodiments of the present application and simplifying the description, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the embodiments of the present application.

[0038] In the description of the embodiments of the present application, unless otherwise clearly specified and limited, technical terms such as "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, and it can be the internal connection of two elements or the interaction relationship between two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the embodiments of the present application can be understood according to the specific circumstances.

[0039] High-power lasers are widely used in industrial processing, communications, medical treatment, national defense and military industries, and other fields. The laser driver power supply is responsible for driving, controlling and protecting the laser. The quality of its technical performance directly affects the light source quality, reliability and service life of the laser system.

[0040] There are a large number of switching frequency subharmonics in the DC voltage output by the laser driver power supply. The structure in which the load is connected in parallel at both ends of the output capacitor makes the load current ripple largely dependent on the load resistance. The laser is a load with a very small on-state resistance. Even if the voltage ripple amplitude of the capacitor filter is very small, it may cause a large current ripple. This makes the capacitor filter power supply unable to fully meet the low current ripple requirements of the laser for the driver power supply. However, the stability of the laser current directly affects the stability of the laser output optical power. Therefore, the laser driver power supply output should reduce the ripple factor and improve the current stability.

[0041] In order to solve the technical problem that the existing capacitive filter will cause large current ripple and cannot fully meet the laser's requirement for low current ripple of the driving power supply, the embodiment of the present application discloses a low ripple constant current source driving circuit for the laser. By setting an LCL filtering circuit between the DC converter and the laser load, the current ripple is effectively reduced and the transient overcurrent spike is suppressed, thereby achieving the technical effect of stably driving the laser.

[0042] Please refer to Figure 1 , Figure 1 A framework diagram of a low-ripple constant current source driving circuit for a laser is provided for an embodiment of the present application, including a DC converter, an LCL filter circuit, a laser load and a current feedback circuit, wherein the DC converter is used to provide a stable DC power supply; the input end of the LCL filter circuit is coupled to the output end of the DC converter, and is used to filter the DC power supply output by the DC converter; the laser load is arranged at the output end of the LCL filter circuit; the sampling end of the circuit feedback circuit is coupled to the input end of the laser load, and the feedback end of the current feedback circuit is coupled to the DC converter, and is used to sample the actual current at the input end of the laser load, and adjust the DC power supply output by the DC converter according to the sampling result.

[0043] Specifically, in the present embodiment, after the external power source is output to the DC converter, it is converted into a stable DC current by the DC converter and output by the DC converter. After the DC current is output from the DC converter, it will be input into the LCL filter circuit. The LCL filter can effectively reduce the current ripple in the DC current and suppress transient overcurrent spikes, thereby forming a stable low-ripple drive current, thereby stably driving the laser load to operate. Secondly, in the present embodiment, a current feedback circuit is also provided. The feedback end of the current feedback circuit can sample the actual current of the input end of the laser load in real time, and calculate the control amount after comparing the actual current of the sampled laser load input end with the set value. The current output of the DC converter is adjusted in real time by the control amount obtained after calculation, thereby ensuring the stability of the laser load during operation.

[0044] Furthermore, in the embodiment provided in the present application, the LCL filtering circuit includes an inductor L1, a capacitor C1 and an inductor L2, the first end of the inductor L1 is coupled to the positive terminal of the DC converter, the first end of the inductor L2 is coupled to the second end of the inductor L1, the second end of the inductor L2 is coupled to the first end of the laser load, the second end of the laser load is coupled to the negative electrode of the DC converter, the first end of the capacitor C1 is coupled to the connecting portion of the inductor L1 and the inductor L2, and the second end of the capacitor C1 is coupled to the negative electrode of the DC converter. In this embodiment, a third-order resonant circuit is formed by the inductor L1, the capacitor C1 and the inductor L2, which can effectively filter out high-frequency harmonics, thereby filtering out the harmonic components output to the laser load, thereby reducing the load current ripple, and further ensuring the stability of the laser current.

[0045] In this embodiment, the value of the inductance L1 can be calculated according to formula (1).

[0046]

[0047] ΔI1 DC converter side ripple current, f s is the DC converter switching frequency.

[0048] The values ​​of capacitor C1 and inductor L2 can be calculated based on the relationship between ripple currents i2 and i1 (2).

[0049]

[0050] Therefore, in this embodiment, the values ​​of inductance L1 and inductance L2 can be reasonably selected according to the above-mentioned relationships (1) and (2), so as to reduce the current ripple and the volume of the total inductance, ω S is the ripple frequency.

[0051] Furthermore, in the embodiment provided in the present application, a capacitor voltage differential feedback circuit is also included, wherein a sampling end of the capacitor voltage differential feedback circuit is coupled to the first end of the capacitor C1, and a feedback end of the capacitor voltage differential feedback circuit is coupled to the DC converter. In the present embodiment, the capacitor voltage differential feedback circuit can take the voltage across the capacitor C1 and perform a differential operation to obtain a result after the differential operation, and adjust the switching action of the DC converter according to the differential operation result, thereby affecting the current flowing through the LCL filter, and further affecting the voltage across the capacitor C1, thereby achieving the effect of increasing the damping of the LCL filter and suppressing the resonance peak.

[0052] Specifically, in this embodiment, after capacitor voltage differential feedback control is adopted, the transfer function relationship between the laser current and the input voltage is expressed as formula (4):

[0053]

[0054] In formula (4), k1 and k2 are determined by the gain of the DC converter. It can be seen from formula (4) that the LCL filter attenuates noise at a rate of -60dB / dec at high frequencies, has a fast dynamic response speed, and the resonance peak is effectively suppressed after the introduction of capacitor voltage differential feedback.

[0055] In this embodiment, the capacitor voltage differential feedback circuit samples the voltage across the capacitor C1 and performs a differential operation as the inner loop control quantity in the closed-loop control of the DC converter, which is used to increase the damping of the LCL filter and suppress the resonance peak. The laser current feedback circuit collects the actual laser current through a current transformer, and calculates the control quantity after comparing it with the set value, which is used as the outer loop control quantity in the closed-loop control of the DC converter. In this embodiment, the capacitor voltage differential feedback circuit and the current feedback circuit are used as the inner loop control quantity and the outer loop control quantity in the closed-loop control of the DC converter, respectively, and the DC converter is comprehensively regulated at the same time, thereby ensuring the stability of the laser load during operation.

[0056] Furthermore, in the embodiment provided in the present application, the low ripple constant current source driving circuit for the laser also includes a laser starting circuit, and the laser starting circuit is used to control the start of the laser load after receiving an external starting signal.

[0057] Specifically, in the present embodiment, the laser start circuit includes a MOS tube Q1, a voltage ramp-up drive module and a start-stop signal receiving circuit, wherein the second end of the laser load is coupled to the negative electrode of the DC converter through the MOS tube Q1, the drain of the MOS tube Q1 is coupled to the negative end of the DC converter, the source of the MOS tube Q1 is coupled to the second end of the laser load, the gate of the MOS tube Q1 is coupled to the output end of the voltage ramp-up drive module, the input end of the voltage ramp-up drive module is coupled to the first end of the capacitor C1; the signal receiving end of the voltage ramp-up drive module is coupled to the signal output end of the start-stop signal receiving circuit.

[0058] When the start-stop signal receiving circuit receives an external start signal, the start-stop signal receiving circuit sends a start instruction to the voltage ramp-up driving module. At this time, after receiving the start instruction, the voltage ramp-up driving module adjusts the voltage transmitted by the voltage ramp-up driving module to the gate of the MOS tube Q1, so that the gate voltage of the MOS tube Q1 increases linearly and slowly. In this process, as the gate voltage of the MOS tube Q1 increases, the charge density of the conductive channel between the source and drain of the MOS tube Q1 increases, and the conductivity is enhanced. Therefore, this also makes the current of the laser increase linearly, thereby achieving the effect of linear constant voltage soft start of the laser.

[0059] Furthermore, in the embodiment provided in the present application, the low ripple constant current source driving circuit for the laser also includes a laser stop circuit, and the laser stop circuit is used to control the laser load to stop running after receiving an external stop signal.

[0060] Specifically, the laser stop circuit includes a resistor R1, a MOS tube Q2 and a fast shutdown drive module, wherein the first end of the resistor R1 is coupled to the first end of the inductor L2; the second end of the resistor R1 is coupled to the drain of the MOS tube Q2, and the source of the MOS tube Q2 is coupled to the second end of the laser load; the output end of the fast shutdown drive module is coupled to the gate of the MOS tube Q2, and the signal receiving end of the fast shutdown drive module is coupled to the signal output end of the start-stop signal receiving circuit. During use, when the start-stop signal receiving circuit receives an external stop signal, the start-stop signal receiving circuit controls the fast shutdown drive module to output a voltage to the gate of the MOS tube Q2. At this time, the drain and source of the MOS tube Q2 are turned on under the action of the voltage output by the fast shutdown drive module, thereby enabling the resistor R1 to be connected in parallel with the laser load, and in this process, the current flows through the resistor R1, causing the current of the laser load to decay rapidly, thereby achieving the effect of fast shutdown of the laser load.

[0061] Furthermore, in the embodiment provided in the present application, a diode D3 is also included, wherein the anode of the diode D3 is coupled to the second end of the inductor L2, and the cathode of the diode D3 is coupled to the first end of the inductor L1. In the present embodiment, the diode D3 can clamp the turn-off reverse voltage across the inductor L2 during the rapid decay of the laser load current, thereby effectively protecting the circuit from damage caused by the excessive reverse voltage generated by the inductor L2 when the current decays rapidly.

[0062] For further information, please refer to Figure 2 In the embodiment provided in the present application, the start-stop signal receiving circuit includes a signal receiving circuit and a synchronization circuit, and the signal receiving circuit is used to receive an external stop signal or an external start signal; the output end of the signal receiving circuit is coupled to the input end of the synchronization circuit, and the signal output ends of the start voltage ramp-up drive module and the fast shutdown drive module are coupled to the output end of the synchronization circuit; wherein, at least one synchronization circuit is provided at the output end of the signal receiving circuit, and when the output end of the signal receiving circuit is provided with multiple groups of synchronization circuits, the multiple groups of synchronization circuits are provided in parallel at the output end of the signal receiving circuit. In this embodiment, a group of signal receiving circuits can control multiple laser loads at the same time through the synchronization circuit. When the signal receiving circuit receives the start / stop signal of the external laser, the signal is synchronously transmitted to multiple groups of low-ripple constant current source drive circuits through the synchronization circuit, thereby achieving the technical effect of being able to quickly and synchronously shut down each laser load.

[0063] In this embodiment, a specific embodiment of a synchronization circuit is provided, which specifically includes a voltage source V3, a resistor R7, a resistor R8, a resistor R9, a resistor R10, a resistor R11, a capacitor C4, a capacitor C5, an optical coupler D5 and a voltage regulator diode D6. The positive terminal of the output end of the signal receiving circuit is coupled to the first end of the resistor R7, the second end of the resistor R7 is coupled to the voltage source V3, the second end of the resistor R7 is coupled to the first end of the resistor R11, the second end of the resistor R11 is coupled to the cathode of the light emitting diode in the optical coupler D5, the anode of the light emitting diode in the optical coupler D5 is coupled to the anode of the voltage regulator diode, the optical transistor in the optical coupler D5 is coupled to the start voltage slow rise drive module and The signal receiving end of the fast shutdown driving module is coupled, the cathode of the voltage regulator diode is coupled to the negative end of the output end of the signal receiving circuit, the first end of the resistor R10 is coupled to the anode of the voltage regulator diode D6, the second end of the resistor R10 is coupled to the first end of the capacitor C5, the second end of the capacitor C5 is coupled to the control end of the voltage regulator diode, the first end of the resistor R8 is coupled to the first end of the resistor R7, the second end of the resistor R8 is coupled to the control end of the voltage regulator diode D6, the first end of the capacitor C4 is coupled to the second end of the resistor R8, the second end of the capacitor C4 is grounded, the resistor R9 is connected in parallel with the capacitor C4, and one end of the resistor R9 is coupled to the cathode end of the voltage regulator diode D6.

[0064] In this embodiment, another specific embodiment of the synchronization circuit is provided, which specifically includes a voltage source V4, a resistor R12, a resistor R13, a resistor R14, a resistor R15, a capacitor C6, an optical coupler D8 and a transistor Q5. The positive terminal of the output end of the signal receiving circuit is coupled to the first end of the resistor R7, the second end of the resistor R7 is coupled to the voltage source V3, the second end of the resistor R7 is coupled to the first end of the resistor R11, the second end of the resistor R11 is coupled to the cathode of the light emitting diode in the optical coupler D5, and the anode of the light emitting diode in the optical coupler D5 is coupled to the transistor Q 5 is coupled to the collector of the optical coupler D5, the phototransistor in the optical coupler D5 is coupled to the signal receiving ends of the start voltage slow rise driving module and the fast shutdown driving module, the emitter of the transistor Q5 is coupled to the negative terminal of the output end of the signal receiving circuit, the first end of the resistor R13 is coupled to the first end of the resistor R12, the second end of the resistor R13 is coupled to the base of the transistor Q5, the first end of the capacitor C6 is coupled to the second end of the resistor R13, the second end of the capacitor C6 is grounded, the resistor R14 is connected in parallel with the capacitor C6, and one end of the resistor R14 is coupled to the emitter of the transistor Q5.

[0065] Furthermore, in the embodiment provided in the present application, a diode D4 is also included. The diode D4 is arranged at the input end of the synchronization circuit, the anode of the diode D4 is coupled to the input end of the synchronization circuit, and the cathode of the diode D4 is coupled to the output end of the signal receiving circuit.

[0066] Taking the above-mentioned synchronization circuit as an example, the cathode of the diode D4 is coupled to the positive terminal of the output end of the signal receiving circuit, and the anode of the diode D4 is coupled to the first end of the resistor R7 or the resistor R12. In this embodiment, the diode D4 can prevent multiple synchronization control circuits with different parameters from influencing each other, so that the total current of the multiple synchronization control circuit input signals superimposed on the optocoupler Q4 is small.

[0067] Further, in the embodiment provided in the present application, the signal receiving circuit includes a voltage source V1, a voltage source V2, a resistor R3, a resistor R4, a resistor R5, a resistor R6, a capacitor C3, a transistor Q3 and a relay Q4, a first end of the resistor R4 is coupled to a signal receiving end for receiving an external start-stop signal, a second end of the resistor R4 is coupled to a base of the transistor Q3, a first end of the resistor R3 is coupled to a first end of the resistor R4, a second end of the resistor R3 is coupled to the voltage source V1, one end of the capacitor C3 is coupled to a second end of the resistor R4, and the capacitor C3 The other end of is grounded, the resistor R5 is connected in parallel with the capacitor C3, the emitter of the transistor Q3 is grounded, the collector of the transistor Q3 is coupled to the first end of the coil in the relay Q4, the first end of the resistor R6 is coupled to the second end of the coil in the relay Q4, the second end of the resistor R6 is coupled to the voltage source V2, and the input end of the synchronization circuit is coupled to the contact in the relay Q4. In this embodiment, the signal receiving circuit controls the conduction of the transistor Q3 by inputting high and low level edge signals, thereby controlling the working state of the optocoupler or the relay to achieve load control.

[0068] Furthermore, in the embodiments provided in the present application, the relay in the above-mentioned signal receiving circuit is replaced by an optocoupler. Compared with relays, optocouplers use optical signals to transmit control signals, and their response speed is usually in microseconds or even faster. They have the characteristics of fast speed, high reliability, no mechanical wear, no noise, no sparks, etc., and are very suitable for low current, low voltage, high frequency and high speed signal isolation scenarios.

[0069] Specifically, the signal receiving circuit includes a voltage source V1, a voltage source V2, a resistor R3, a resistor R4, a resistor R5, a resistor R6, a capacitor C3, a transistor Q3 and an optocoupler Q4, a first end of the resistor R4 is coupled to a signal receiving end for receiving an external start / stop signal, a second end of the resistor R4 is coupled to a base of the transistor Q3, a first end of the resistor R3 is coupled to a first end of the resistor R4, a second end of the resistor R3 is coupled to the voltage source V1, one end of the capacitor C3 is coupled to a second end of the resistor R4, the other end of the capacitor C3 is grounded, the resistor R5 is connected in parallel with the capacitor C3, the emitter of the transistor Q3 is grounded, the collector of the transistor Q3 is coupled to an anode of a light-emitting diode in the optocoupler Q4, a first end of the resistor R6 is coupled to a cathode of a light-emitting diode in the optocoupler Q4, a second end of the resistor R6 is coupled to the voltage source V2, and an input end of the synchronization circuit is coupled to a phototransistor in the optocoupler Q4.

[0070] It should be noted that the present application is not limited to the above-mentioned embodiments. The above-mentioned embodiments are only examples, and the embodiments having the same structure as the technical idea and exerting the same effect within the scope of the technical solution of the present application are all included in the technical scope of the present application. In addition, without departing from the scope of the main purpose of the present application, various modifications that can be thought of by those skilled in the art to the embodiments and other methods of combining some of the constituent elements in the embodiments are also included in the scope of the present application.

Claims

1. A low ripple constant current source driving circuit for a laser, characterized in that: include: A DC converter for providing a stable DC power supply; An LCL filter circuit, wherein an input end of the LCL filter circuit is coupled to an output end of the DC converter, and is used for filtering the DC power output by the DC converter; A laser load, wherein the laser load is arranged at an output end of the LCL filter circuit; A current feedback circuit, wherein the sampling end of the current feedback circuit is coupled to the input end of the laser load, and the feedback end of the current feedback circuit is coupled to the DC converter, for sampling the actual current at the input end of the laser load and adjusting the DC power supply output by the DC converter according to the sampling result.

2. The low ripple constant current source driving circuit for laser according to claim 1, characterized in that: The LCL filter circuit includes an inductor L1, a capacitor C1 and an inductor L2, wherein the first end of the inductor L1 is coupled to the positive terminal of the DC converter, the first end of the inductor L2 is coupled to the second end of the inductor L1, the second end of the inductor L2 is coupled to the first end of the laser load, the second end of the laser load is coupled to the negative electrode of the DC converter, the first end of the capacitor C1 is coupled to the connecting portion between the inductor L1 and the inductor L2, and the second end of the capacitor C1 is coupled to the negative electrode of the DC converter.

3. The low ripple constant current source driving circuit for laser according to claim 2, characterized in that: It also includes a capacitor voltage differential feedback circuit, a sampling end of the capacitor voltage differential feedback circuit is coupled to the first end of the capacitor C1, and a feedback end of the capacitor voltage differential feedback circuit is coupled to the DC converter.

4. The low ripple constant current source driving circuit for laser according to claim 2, characterized in that: Also includes: MOS tube Q1, the second end of the laser load is coupled to the negative electrode of the DC converter through the MOS tube Q1, the drain of the MOS tube Q1 is coupled to the negative end of the DC converter, and the source of the MOS tube Q1 is coupled to the second end of the laser load. A voltage-slow-rise driving module, wherein the gate of the MOS tube Q1 is coupled to the output end of the voltage-slow-rise driving module, and the input end of the voltage-slow-rise driving module is coupled to the first end of the capacitor C1; A start-stop signal receiving circuit, wherein the signal receiving end of the voltage ramp-up driving module is coupled to the signal output end of the start-stop signal receiving circuit. When the start-stop signal receiving circuit receives an external start signal, the start-stop signal receiving circuit controls the output voltage of the output end of the voltage ramp-up driving module to increase linearly.

5. The low ripple constant current source driving circuit for laser according to claim 4, characterized in that: Also includes: A resistor R1, a first end of the resistor R1 is coupled to a first end of the inductor L2; A MOS tube Q2, wherein a drain of the MOS tube Q2 is coupled to the second end of the resistor R1, and a source of the MOS tube Q2 is coupled to the second end of the laser load; A fast shutdown driving module, wherein the output end of the fast shutdown driving module is coupled to the gate of the MOS tube Q2, and the signal receiving end of the fast shutdown driving module is coupled to the signal output end of the start-stop signal receiving circuit. When the start-stop signal receiving circuit receives an external stop signal, the fast shutdown driving module controls the drain and source of the MOS tube Q2 to be turned on.

6. The low ripple constant current source driving circuit for laser according to claim 2, characterized in that: A diode D3 is further included. An anode of the diode D3 is coupled to the second end of the inductor L2 , and a cathode of the diode D3 is coupled to the first end of the inductor L1 .

7. The low ripple constant current source driving circuit for laser according to claim 5, characterized in that: The start / stop signal receiving circuit comprises: A signal receiving circuit, used for receiving an external stop signal or an external start signal; A synchronization circuit, wherein the output end of the signal receiving circuit is coupled to the input end of the synchronization circuit, and the signal receiving ends of the voltage ramp-up driving module and the fast shutdown driving module are both coupled to the output end of the synchronization circuit; Among them, at least one of the synchronization circuits is arranged at the output end of the signal receiving circuit, and when a plurality of groups of the synchronization circuits are arranged at the output end of the signal receiving circuit, the plurality of groups of the synchronization circuits are arranged in parallel at the output end of the signal receiving circuit.

8. The low ripple constant current source driving circuit for laser according to claim 7, characterized in that: It also includes a diode D4, which is arranged at the input end of the synchronization circuit, an anode of the diode D4 is coupled to the input end of the synchronization circuit, and a cathode of the diode D4 is coupled to the output end of the signal receiving circuit.

9. The low ripple constant current source driving circuit for laser according to claim 7, characterized in that: The signal receiving circuit includes a voltage source V1, a voltage source V2, a resistor R3, a resistor R4, a resistor R5, a resistor R6, a capacitor C3, a transistor Q3 and a relay Q4, a first end of the resistor R4 is coupled to a signal receiving end for receiving an external start / stop signal, a second end of the resistor R4 is coupled to a base of the transistor Q3, a first end of the resistor R3 is coupled to a first end of the resistor R4, a second end of the resistor R3 is coupled to the voltage source V1, one end of the capacitor C3 is coupled to the second end of the resistor R4, the other end of the capacitor C3 is grounded, the resistor R5 is connected in parallel with the capacitor C3, the emitter of the transistor Q3 is grounded, the collector of the transistor Q3 is coupled to a first end of a coil in the relay Q4, a first end of the resistor R6 is coupled to a second end of the coil in the relay Q4, a second end of the resistor R6 is coupled to the voltage source V2, and an input end of the synchronization circuit is coupled to a contact in the relay Q4.

10. The low ripple constant current source driving circuit for laser according to claim 7, characterized in that: The signal receiving circuit includes a voltage source V1, a voltage source V2, a resistor R3, a resistor R4, a resistor R5, a resistor R6, a capacitor C3, a transistor Q3 and an optical coupler Q4, wherein a first end of the resistor R4 is coupled to a signal receiving end for receiving an external start / stop signal, a second end of the resistor R4 is coupled to a base of the transistor Q3, a first end of the resistor R3 is coupled to a first end of the resistor R4, a second end of the resistor R3 is coupled to the voltage source V1, one end of the capacitor C3 is coupled to a second end of the resistor R4, the other end of the capacitor C3 is grounded, the resistor R5 is connected in parallel with the capacitor C3, an emitter of the transistor Q3 is grounded, a collector of the transistor Q3 is coupled to an anode of a light emitting diode in the optical coupler Q4, a first end of the resistor R6 is coupled to a cathode of a light emitting diode in the optical coupler Q4, a second end of the resistor R6 is coupled to the voltage source V2, and an input end of the synchronization circuit is coupled to a phototransistor in the optical coupler Q4.

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