A linear high-power semiconductor laser driving power supply feedforward control model, system and method

Abstract

The application provides a linear high-power semiconductor laser driving power supply feedforward control model, system and method, and the model comprises: a semiconductor laser internal resistance, a semiconductor laser internal parasitic inductance, a wiring inductance equivalent inductance caused by wiring, a semiconductor laser internal parasitic capacitance and an equivalent capacitance formed by the semiconductor laser internal parasitic capacitance and a parasitic capacitance caused by a driving circuit. The second-order control model provided by the application not only realizes the correspondence with the actual test current waveform, but also avoids the complexity of the traditional high-order model control and is difficult to be applied in engineering.

Description

TECHNICAL FIELD

[0001] The application belongs to the field of semiconductor laser driving power supply, and particularly relates to a linear high-power semiconductor laser driving power supply feedforward control model, system and method. BACKGROUND

[0002] The driving power supply of a high-power semiconductor laser and a fiber laser is commonly divided into two types: a switching power supply and a linear power supply. The linear power supply has a relatively fast response speed and a low driving current ripple, and has been widely applied.

[0003] Among the many performance indicators of a high-power laser driving power supply, the driving current response speed is an important requirement. The patent application with the application number 202210646981.1 describes a segmented control method, which provides an effective means for accelerating the current response of the laser driving power supply. However, due to different parasitic parameters of lasers of different manufacturers and different models, and even the length of the power supply wiring of the whole machine manufacturer, the wiring method will affect the overall performance of the laser driving. The hardware power regulation circuit of the laser driving power supply either cannot be widely adapted to multiple models of lasers, resulting in overshoot or even oscillation of the driving current of some models of lasers, as shown in FIG. 1; or the current response time is not reached, which reduces its performance. Figure 1 SUMMARY

[0004] In view of the above technical problems, the application provides a linear high-power semiconductor laser driving power supply feedforward control model, system and method. A second-order control model of a high-power semiconductor laser is proposed, and a feedforward control method based on the model is realized on the basis of the model, which effectively accelerates the current response time and reduces the overshoot.

[0005] To achieve the above purpose, the technical scheme adopted by the application is as follows:

[0006] A linear high-power semiconductor laser driving power supply feedforward control model comprises: a semiconductor laser internal resistance , a semiconductor laser internal parasitic inductance, a wiring inductance equivalent inductance caused by wiring, a semiconductor laser internal parasitic capacitance, and a parasitic capacitance formed by the joint action of a driving circuit. .

[0007] A linear high-power semiconductor laser driving power supply feedforward control system comprises:

[0008] An output current closed-loop controller, which is used to subtract the output current feedback from the current input R(s) to obtain a difference value, and output a current closed-loop output control quantity after the difference value is operated by a PID controller.

[0009] ​​A current feedforward controller, the current input R(s) is calculated through the linear high-power semiconductor laser drive power supply feedforward control model F(s) by the current feedforward controller, and then the feedforward control quantity is output;

[0010] The current closed-loop output control quantity and the feedforward control quantity output by the linear high-power semiconductor laser drive power supply feedforward control model F(s) are added, and the drive current for driving the semiconductor laser is generated by controlling the drive power supply.

[0011] A linear high-power semiconductor laser drive power supply feedforward control method is executed by a linear high-power semiconductor laser drive power supply feedforward control system, comprising:

[0012] Step one, the current input R(s) is calculated through the linear high-power semiconductor laser drive power supply feedforward control model F(s) by the current feedforward controller, and then the feedforward control quantity is output;

[0013] Step two, the output current feedback and the current input R(s) are subtracted by the output current closed-loop controller, and the difference value is output after the PID controller is operated to obtain the current closed-loop output control quantity;

[0014] Step three, the current closed-loop output control quantity and the feedforward control quantity output by the linear high-power semiconductor laser drive power supply feedforward control model F(s) are added, and the drive current for driving the semiconductor laser is generated by controlling the drive power supply.

[0015] Advantages:

[0016] The application proposes a second-order model based on high-power laser driving, which avoids the inconsistency between the traditional first-order system and the actual current output response waveform, or the complexity of the traditional high-order system, which is not conducive to analysis. According to the model, a feedforward controller based on load characteristics is designed, which effectively speeds up the response time of the drive current and reduces the system overshoot. BRIEF DESCRIPTION OF DRAWINGS

[0017] Figure 1 The semiconductor laser drive current overshoot and oscillation waveform in the prior art;

[0018] Figure 2 The semiconductor laser drive power supply electrical schematic diagram in the linear high-power semiconductor laser drive power supply feedforward control model;

[0019] Figure 3 The semiconductor laser drive power supply small signal schematic diagram in the linear high-power semiconductor laser drive power supply feedforward control model;

[0020] Figure 4 The semiconductor laser drive power supply equivalent small signal schematic diagram in the linear high-power semiconductor laser drive power supply feedforward control model;

[0021] Figure 5 The control schematic diagram for increasing the feedforward control in the feedforward control system of the linear high-power semiconductor laser driving power supply;

[0022] Figure 6 The semiconductor laser driving current waveform after increasing the feedforward control. DETAILED DESCRIPTION

[0023] In order to make the purpose, technical scheme and advantages of the present application more clear, the present application is further described in detail below in combination with embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and do not limit the present application. In addition, the technical features involved in each embodiment of the present application described below can be combined with each other as long as they do not conflict with each other.

[0024] The present application provides a linear high-power semiconductor laser driving power supply feedforward control model and a feedforward control method based on the model. The segmented control method described in the invention patent application number 202210646981.1 is applied, and in the output stage two, i.e. the closed-loop output stage, the discrete feedforward model is multiplied by a certain coefficient according to the sampling frequency output by the single-chip microcomputer output DAC, and the closed-loop feedback compensation value is added by the adder, which jointly controls the current output of the driving power supply.

[0025] The equivalent electrical schematic diagram of the high-power semiconductor laser linear driving power supply considering parasitic parameters is shown in Figure 2 , wherein is the input control voltage; is the front constant voltage source; is the inductance equivalent to the wiring inductance; LD is the semiconductor laser; is the internal resistance of the semiconductor laser, is the MOSFET gate drive resistance; Q is the N-channel MOSFET; is the integrated parasitic capacitance of the semiconductor laser; Cgs is the MOSFET gate-drain parasitic capacitance; Cdg is the gate-source parasitic capacitance; Cds is the source-drain parasitic capacitance, and Csc is the equivalent capacitance formed by the combined action of the internal parasitic capacitance of the semiconductor laser and the parasitic capacitance caused by the driving circuit.

[0026] When the MOSFET works in the saturation region, the output current output relationship is:

[0027] ;

[0028] wherein: K: is the transfer gain, is the input control voltage, which is also the gate drive voltage, : is the MOSFET conduction threshold voltage.

[0029] The segmented control method described in application patent number 202210646981.1 is applied, Figure 2 The equivalent small signal circuit is as shown in Figure 3 .

[0030] According to the experimental results, the capacitance values of Cgs and Cdg are much smaller than those of Cds and Csc, so the small signal equivalent circuit can ignore them; by combining Cds and Csc, the small signal circuit can be equivalent to Figure 4 .

[0031] According to an embodiment of the present application, a linear high-power semiconductor laser drive power supply feedforward control model is provided, Figure 4 The structure diagram of the model is shown. As Figure 4 shown, the model includes the internal resistance of the semiconductor laser , the inductance equivalent to the wiring inductance caused by the internal parasitic inductance of the semiconductor laser, wiring, etc. , the equivalent capacitance formed by the joint action of the internal parasitic capacitance of the semiconductor laser and the parasitic capacitance caused by the driving circuit .

[0032] Figure 4 The model shown in the above can be referred to as a small signal model. Under the small signal model, the MOSFET output current is:

[0033] (1)

[0034] Among them:

[0035] (2)

[0036] The above linear high-power semiconductor laser drive power supply feedforward control model provides the laser current. According to Kirchhoff's current law, the small signal of the semiconductor laser current is:

[0037] (3)

[0038] Among them is the parasitic capacitance current.

[0039] In addition:

[0040] (4)

[0041] (5)

[0042] Among them, is the MOSFET source voltage, L is the inductance value of the inductance equivalent to the wiring inductance and the like caused by the wiring, R is the resistance value of the internal resistance of the semiconductor laser, C is the equivalent parasitic capacitance.

[0043] Substituting formula (1) and (5) into formula (3) can obtain:

[0044] (6)

[0045] wherein, is the small signal of the semiconductor laser current, is the small signal of the MOSFET driving voltage.

[0046] is the small signal of the semiconductor laser current, The open-loop transfer function is:

[0047] (7)

[0048] The model is a typical second-order system, when the damping coefficient < 1, the system presents the characteristics of damped oscillation, and the oscillation angular frequency is: , which corresponds to the actual engineering phenomenon.

[0049] Based on the second-order system driving model, a control system with feedforward compensation is proposed, and the principle is shown in Figure 5 . As shown in Figure 5 , the control system includes:

[0050] an output current closed-loop controller, the difference between the output current feedback and the current input R(s) is obtained through the output current closed-loop controller, and the difference value is output after the output current closed-loop output control quantity is calculated by the PID controller;

[0051] a current feedforward controller, the feedforward control quantity is output after the current input R(s) is calculated by the current feedforward controller through the linear high-power semiconductor laser drive power supply feedforward control model F(s);

[0052] The current closed-loop output control quantity and the feedforward control quantity output by the linear high-power semiconductor laser drive power supply feedforward control model F(s) are added, and the drive power supply is controlled to generate the drive current of the laser.

[0053] Figure 5 in formula (7) is a feedforward compensation model based on the controlled object, which is the inverse of the controlled object. Therefore, formula (7) can be obtained:

[0054] (8)

[0055] in formula (8) is the MOSFET drive voltage required for the model output drive current.

[0056] In order to reduce the influence of the high frequency part of the feedforward term on the system, a second order low pass filter is added to the drive current output, and the formula (8) is obtained:

[0057] (9)

[0058] Wherein, τ is a parameter related to the system design target bandwidth, and s is the Laplace operator.

[0059] Although the added low pass filter weakens the effect of the feedforward, it improves the system stability, and the overall response and overshoot of the system are improved. The current response curve after adding the feedforward is shown in Figure 6 Compared with Figure 1 , the overshoot and adjustment time are significantly reduced.

[0060] According to the embodiment of the present application, a feedforward control method of linear high-power semiconductor laser driving power supply is provided. The method comprises:

[0061] Step one, after the current input R(s) is calculated by the current feedforward controller through the linear high-power semiconductor laser driving power supply feedforward control model F(s), the feedforward control quantity is outputted;

[0062] Step two, the difference between the output current feedback and the current input R(s) is obtained by the output current closed loop controller, and the difference is calculated by the PID controller to output the current closed loop output control quantity;

[0063] Step three, the current closed loop output control quantity and the feedforward control quantity outputted by the linear high-power semiconductor laser driving power supply feedforward control model F(s) are added to control the driving power supply to generate the drive current of the laser.

[0064] The present application is not limited to the above specific embodiments, and the embodiments slightly modified or changed by the general technical personnel in the art according to the content disclosed in the present embodiment or the drawings are also within the protection scope of the present application.

Claims

1. A feedforward control model for a linear high-power semiconductor laser driver power supply, characterized in that, include: internal resistance of semiconductor laser Parasitic inductance inside semiconductor lasers, wiring inductance, and equivalent inductance. The equivalent capacitance formed by the combined effect of parasitic capacitance within the semiconductor laser and the parasitic capacitance caused by the driving circuit. ; The small-signal current of the semiconductor laser is calculated based on the feedforward control model of the linear high-power semiconductor laser driver. The control quantity is: （9） in, This is the feedforward control variable. K: is the transfer gain. : is the MOSFET turn-on voltage threshold of the drive power supply. For input control voltage, It is the inductance value of the equivalent inductance caused by the wiring. This represents the internal resistance value of the semiconductor laser. It is the equivalent capacitance. τ is a small signal of the semiconductor laser current, τ is a parameter related to the target bandwidth of the system design, and s is the Laplace operator.

2. A linear high-power semiconductor laser driver power supply feedforward control system, characterized in that, include: The output current closed-loop controller calculates the difference between the output current feedback and the current input R(s), and the difference is then processed by the PID controller to output the closed-loop control quantity of the output current. The current feedforward controller calculates the current input R(s) using the linear high-power semiconductor laser driver power supply feedforward control model F(s) as described in claim 1, and then outputs the feedforward control quantity. The current closed-loop output control quantity is added to the feedforward control quantity output by the linear high-power semiconductor laser driver power supply feedforward control model F(s) to control the driver power supply to generate the driving current for driving the semiconductor laser.

3. A feedforward control method for a linear high-power semiconductor laser driver power supply, characterized in that, Executed by the linear high-power semiconductor laser driver power supply feedforward control system according to claim 2, comprising: Step 1: After the current input R(s) is calculated by the current feedforward controller through the linear high-power semiconductor laser driver power supply feedforward control model F(s), the feedforward control quantity is output. Step 2: The output current feedback and the current input R(s) are subtracted by the output current closed-loop controller. The difference is then calculated by the PID controller to output the closed-loop control quantity of the output current. Step 3: After adding the current closed-loop output control quantity to the feedforward control quantity output by the linear high-power semiconductor laser driver power supply feedforward control model F(s), the driver power supply is controlled to generate the driving current for driving the semiconductor laser.

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