Driving system of laser
By synchronous control of the parallel multi-switch constant current circuit, the contradiction between current stability and high-current output in constant current driving of high-power lasers is solved, and the large and stable power output of the laser is achieved.
Patent Information
- Application Number
- CN202421674578.0
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-07-15
- Publication Date
- 2025-04-22
- Estimated Expiration
- 2034-07-15
AI Technical Summary
In constant current driving, high-power semiconductor lasers are difficult to meet the requirements of high-current output and current stability at the same time. The prior art has failed to effectively solve the consistency problem of various adjustment circuits, affecting the constant current output.
By synchronous control of the parallel multi-switch constant current circuit, the consistency of the output current of each switch constant current circuit is ensured, and then the output is combined to the laser.
The consistency of the constant current circuit of each switch is achieved, the driving system is optimized, and the large and stable power output of the laser is ensured.
Smart Images
Figure CN222785637U_ABST
Abstract
Description
Technical Field
[0001] The present application relates to a laser in a medical device, and in particular to a driving system of a laser. Background Art
[0002] In medical devices, semiconductor lasers are mostly high-power, such as laser medical devices. The startup method used by such high-power semiconductor lasers is mostly constant current drive. Constant current drive is very important to ensure the stable operation of semiconductor lasers, because the life of the laser depends largely on whether the current passing through it is stable.
[0003] The so-called high-power constant current drive will inevitably require a large output current. In order to ensure the stability of the constant current, it will also require that the current rising and falling edges are fast, and the output current fluctuation amplitude must be less than the limit value.
[0004] From the above description, it can be seen that there is a contradiction between the high current output of high-power lasers and the requirement of constant current stability. In order to meet both of the above requirements, the patent publication document CN117712820B discloses a laser drive system, which outputs the power input to the load through the adjustment circuit, wherein the adjustment circuit includes n-way current control units, and adjusts the output current of each current control unit separately, and then combines the output current of the n-way current control units and outputs them to the laser load. This circuit design of first splitting and then combining avoids the disadvantages brought by single-way current. However, the technical solution disclosed in patent CN117712820B does not take into account the consistency of each adjustment circuit, thereby affecting the constant current output. Utility Model Content
[0005] The purpose of the present application is to provide a laser driving system, which achieves consistency in the output current of each switching constant current circuit and then merges them by synchronously controlling multiple parallel switching constant current circuits.
[0006] A laser driving system in an embodiment of the present application includes a power input terminal and n parallel switch constant current circuits, where n is greater than or equal to 2, and the n switch constant current circuits each include a switch power control chip, a sampling resistor, and a current feedback circuit, wherein the power input terminal is connected to the switch power control chip, the switch power control chip outputs current through the sampling resistor, and the sampling resistor inputs a feedback current signal to the switch power control chip through the current feedback circuit;
[0007] The output currents of n-way switching constant current circuits are combined and then transmitted to the laser;
[0008] The n switching constant current circuits are all connected to the same current control signal input terminal, and the current control signal input terminal is connected to the switching power supply control chip.
[0009] Preferably, the n-way switch constant current circuits are connected to the same voltage feedback circuit, the input end of the voltage feedback circuit is connected to the sampling resistor, and the output end of the voltage feedback circuit is connected to the switch power supply control chip.
[0010] Preferably, it also includes a switching signal generator, which has n signal output terminals, the same number as the switching constant current circuit, which are the first to nth signal output terminals, and the first to nth signal output terminals output the first to nth switching signals to their respective corresponding switching constant current circuits.
[0011] Preferably, the first to nth switching signals are switching signals with n different phases, and the phases of the n switching signals are all between 0° and 360°.
[0012] Preferably, the first to nth switch signals are arranged from small to large to form an arithmetic progression with a tolerance of 360° / n.
[0013] Preferably, the first to nth switching signals are switching signals of n different frequencies, and the frequencies of the n switching signals are all greater than or equal to 200 kHz and less than or equal to 1 MHz.
[0014] Preferably, the first to nth switching signals are arranged from small to large to form an arithmetic progression with a tolerance of 800kHz / (n-1).
[0015] Preferably, it also includes a switch constant current circuit quantity input terminal, which is electrically connected to the switch power supply control chip in the n switch constant current circuits to control the on and off of the switch constant current circuits.
[0016] Preferably, the current control signal input terminal is also coupled to a switch constant current circuit quantity input terminal, and the switch constant current circuit quantity input terminal is used to control the on and off of the switch constant current circuit.
[0017] Preferably, the output current values of the n switching constant current circuits are all less than or equal to 20A.
[0018] The main technical effect achieved by the embodiments of the present application is: by inputting the same current control to the parallel multi-way switch constant current circuits, each switch constant current circuit is synchronously controlled, thereby ensuring the current consistency of each switch constant current circuit and optimizing the drive system. BRIEF DESCRIPTION OF THE DRAWINGS
[0019] Figure 1 It is a block diagram of a laser driving system in the prior art;
[0020] Figure 2 This is a block diagram of the laser driving system of this application;
[0021] Figure 3 for Figure 2 The block diagram of the switch signal generator and the switch circuit control chip. DETAILED DESCRIPTION
[0022] Here, exemplary embodiments are described in detail, and examples thereof are shown in the accompanying drawings. When the following description refers to the drawings, unless otherwise indicated, the same numbers in different drawings represent the same or similar elements. The methods described in the following exemplary embodiments do not represent all methods consistent with the present application.
[0023] like Figure 2 As shown, the present application discloses a laser driving system, which can stabilize the output voltage and current value, and the output current can be relatively large, and is particularly suitable for use with some high-power lasers. The driving system includes n sub-circuits connected to the power input end, and the value of n is greater than or equal to 2. The sub-circuit is a switching constant current circuit, and the output current of the sub-circuit is less than or equal to 20A. In this system, the power input end is mainly used for power supply. Figure 1 As shown, in the prior art, lasers are usually driven by constant current, but there is only one constant current circuit, which is acceptable for low-power lasers. However, if it is used for high-power lasers, there are some problems. For high-power lasers, when the output voltage is constant, the output current of the driving system must be relatively large. However, once the current is large, it is easy to cause the rising and falling time of the current to become longer, which is not conducive to the stable output of the laser power. For this reason, the present application designs a multi-way switch constant current circuit in the laser driving system, and these sub-circuits are connected in parallel, which not only ensures that the voltage of each sub-circuit is consistent, but also shunts the current, thereby realizing a large and stable power output of the laser. Moreover, since the multi-way switch constant current circuit shunts the current, the output current of each sub-circuit is at a lower level, the sampling resistor is not easy to accumulate heat to produce temperature drift, the output current error is small, and the current ripple is also relatively small.
[0024] In order to ensure that the current of the sub-circuits in the drive system is stable and consistent, the n-way switch constant current circuits are all connected to the current control signal input terminal. The current control signal input terminal controls the consistency of the current value of each switch constant current circuit with only one input, simplifying the input operation of the drive system. Not only that, when the current value of each sub-circuit is the same, it is also the optimal solution for the current distribution of the drive system, which can avoid the current value of a certain sub-circuit being significantly higher than that of other circuits, thereby causing the problem of unstable output current.
[0025] The switch constant current circuit includes a switch power supply control chip, a sampling resistor and a current feedback circuit. Figure 2As shown, the output end of the sampling resistor is electrically connected to the input end of the current feedback circuit, and the output end of the current feedback circuit is electrically connected to the switching power supply control chip, and the output end of the chip is connected to the input end of the sampling resistor. The three form a closed current regulation system. The current feedback circuit feeds back the actual value of the current passing through the sampling circuit to the switching power supply control chip, and the switching power supply control chip compares the actual current value provided by the feedback circuit with the theoretical value, and controls the current value of the adjustment subcircuit so that the current in the switching constant current circuit remains stable. Among them, the theoretical value of the current is determined according to the current control signal input in advance.
[0026] Each of the n-way switching constant current circuits is equipped with a switching power supply control chip, which is used to regulate the current and voltage values in the circuit. It is basically a switching regulator or a power management IC, and can be selected from LT3741, LT3744, LT3763, MAX20096, MAX20097 and other models. Figure 2 It can be seen that the output ends of the current feedback circuit and the voltage feedback circuit are both connected to the switching power supply control chip, and the switching power supply control chip adjusts the voltage and current values in the circuit according to the information fed back by the feedback circuit. In addition, an output current control port is also provided on each switching power supply control chip, which is electrically connected to the current control signal input end, and controls the circuit size and on-off mode in the switching constant current circuit according to the current size and on-off mode input by the current control signal input end.
[0027] The drive system is also provided with a voltage feedback circuit for stabilizing the output voltage. All n switching constant current circuits are connected to the voltage feedback circuit. Specifically, the input end of each switching constant current circuit is electrically connected to the output end of the sampling resistor, and the output end is connected to the switching power supply control chip. The voltage feedback circuit collects the actual value of the voltage in the circuit and feeds it back to the switching power supply control chip, which regulates the output voltage of the laser. The output voltage value can be determined according to the type of laser. For semiconductor lasers, the output voltage is generally lower than 6V.
[0028] Conducted emission refers to an electromagnetic phenomenon in which the voltage or current inside the system is transmitted through a signal cable, power line or ground line and becomes an interference source for other systems or equipment. Any product with a power line will be involved. Electromagnetic radiation emission refers to the electromagnetic waves emitted by electronic equipment into the surrounding space when it is working. This emission is not transmitted through wires, but through media such as air. For laser drive systems, both conducted emission and electromagnetic radiation emission are involved, especially for drive systems with large current output, the two phenomena are more significant. In order to solve the impact of electromagnetic effects on laser drive systems, the present application provides a switch signal generator in the drive system to provide a switch signal to each switch constant current circuit. The switch signal generator can be a microprocessor (MCU), a programmable logic array (FPGA), a digital frequency synthesizer (DDS), etc. The controller controls the switching frequency and / or phase of the switch power control chip by sending different switch signals to the switch power control chip in the n-way sub-circuit. In this way, the frequency and / or phase of the output current of each switch constant current circuit are staggered, so that the conducted emission and electromagnetic radiation emission are extended to a wider frequency band, thereby reducing the peak noise and average noise at a specific frequency.
[0029] Since the laser driving system has n-way switching constant current circuits, in this embodiment, Figure 3 As shown, the switch signal generator is provided with n signal output terminals, which are the first to nth signal output terminals, respectively. The n signal output terminals are electrically connected to the input terminals of the switch power supply control chip of the n-way switch constant current circuit, and each inputs the first to nth switch signals to the n-way switch constant current circuit, wherein the switch signal is mainly a phase and / or frequency signal. In order to stagger the n switch signals as much as possible, the n switch signals sent by the switch signal generator are set to an arithmetic progression with the largest tolerance in phase and / or frequency.
[0030] For n switching signals with different phases, the switching signal phase sent by the switching signal generator to each switching constant current circuit is within 0-360°, where 0° and 360° are overlapped. The switching signal phases obtained by the n switching constant current circuits are all different. Arranging all the switching signals from small to large can form an arithmetic progression with a tolerance of 360° / n. For example: when there are 4 closed switching constant current circuits in the drive system, and the switching signals only have a phase difference, the switching signal generator sends switching signals with phases of 0°, 90°, 180°, and 270° to the 4 switching constant current circuits respectively.
[0031] For n switching signals of different frequencies, the switching signal frequency sent by the switching signal generator to each switching constant current circuit is in the range of 200kHz to 1MHz, including the end value. The switching signal frequencies obtained by the n switching constant current circuits are all different. Arranging all the switching signal frequencies from small to large can form an arithmetic progression with a tolerance of 800kHZ / (n-1). For example: when there are 3 closed switching constant current circuits in the drive system, and the switching signals only have a frequency difference, the switching signal generator sends switching signals with frequencies of 200kHz, 600kHz, and 1MHz to the 3 switching constant current circuits respectively.
[0032] When the switching signal generator sends switching signals of different frequencies and phases to the switching constant current circuit at the same time, the phase and frequency obtained by each switching constant current circuit are also as described above, that is, the phases and frequencies are an arithmetic progression of a certain value, but it is not required that there is a certain correlation between the phases and the frequencies, that is, the larger the phase, the larger the frequency, or the smaller the phase, the larger the frequency, etc. The matching of the phase and frequency is random.
[0033] Figure 1 In the prior art shown, since there is only one switching constant current circuit, the switching signal can be generated inside the switching power supply chip. In this embodiment, since there are multiple switching constant current circuits, the switching frequency and phase of each switching constant current circuit are different. Of course, the difference in one of the switching frequency or phase is beneficial to electromagnetic compatibility. Preferably, the switching frequency and phase are different. Therefore, a switching signal generator is independently set in the drive system to provide control signals about the switching frequency and phase to each switching constant current circuit. The output end of the switching signal generator is electrically connected to the switching power supply control chip in the switching constant current circuit, and the switching frequency and / or phase are controlled by the switching power supply control chip.
[0034] In the present embodiment, in the n-way switch constant current circuit, the magnitude of the current and voltage are consistent, but the frequency and / or phase of the current and voltage are different. The drive system determines the current parameters of each switch constant current circuit according to the input value of the current control signal input terminal, specifically including the current magnitude, phase, frequency and pulse mode, etc. For some embodiments, the number of switch constant current circuits in the drive system can also be controlled and adjusted as needed. For example, a switch constant current circuit quantity input terminal can be added to the drive system, and the input terminal is connected to the n-way switch power supply control chip, and the chip controls the disconnection of the switch constant current circuit according to the circuit quantity input value. In this way, the current output of any size can be achieved by changing the number of parallel switch constant current circuits. Of course, the switch constant current circuit quantity input terminal can also be coupled to the current control signal input terminal, and the disconnection of the switch constant current circuit can be achieved by increasing the input parameters.
[0035] The above description is only a preferred embodiment of the present application and is not intended to limit the present application. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present application shall be included in the scope of protection of the present application.
Claims
1. A laser driving system, comprising a power input terminal and n parallel switching constant current circuits, n being greater than or equal to 2, characterized in that: The n-way switch constant current circuits each include a switch power supply control chip, a sampling resistor, and a current feedback circuit, wherein the power input end is connected to the switch power supply control chip, the switch power supply control chip outputs current through the sampling resistor, and the sampling resistor inputs a feedback current signal to the switch power supply control chip through the current feedback circuit; The output currents of n-way switch constant current circuits are combined and then transmitted to the laser; The n switching constant current circuits are all connected to the same current control signal input terminal, and the current control signal input terminal is connected to the switching power supply control chip.
2. The laser driving system according to claim 1, characterized in that: The n-way switch constant current circuits are connected to the same voltage feedback circuit, the input end of the voltage feedback circuit is connected to the sampling resistor, and the output end of the voltage feedback circuit is connected to the switch power supply control chip.
3. The laser driving system according to claim 1, characterized in that: It also includes a switching signal generator, which has n signal output terminals, the same number as the switching constant current circuit, which are the first to nth signal output terminals, and the first to nth signal output terminals output the first to nth switching signals to the corresponding switching constant current circuits.
4. The laser driving system according to claim 3, characterized in that: The first to nth switching signals are switching signals with n different phases, and the phases of the n switching signals with different phases are all between 0° and 360°.
5. The laser driving system according to claim 4, characterized in that: The first to nth switch signals are arranged from small to large to form an arithmetic progression with a tolerance of 360° / n.
6. The laser driving system according to claim 3, characterized in that: The first to nth switching signals are switching signals with n different frequencies, and the frequencies of the n switching signals with different frequencies are all greater than or equal to 200 kHz and less than or equal to 1 MHz.
7. The laser driving system according to claim 6, characterized in that: The first to nth switching signals are arranged from small to large to form an arithmetic progression with a tolerance of 800kHz / (n-1).
8. The laser driving system according to claim 1, characterized in that: It also includes a switch constant current circuit quantity input terminal, which is electrically connected to the switch power supply control chip in the n-way switch constant current circuit for controlling the on and off of the switch constant current circuit.
9. The laser driving system according to claim 1, characterized in that: The current control signal input terminal is also coupled to a switch constant current circuit quantity input terminal, and the switch constant current circuit quantity input terminal is used to control the on and off of the switch constant current circuit.
10. The laser driving system according to claim 1, characterized in that: The output current values of the n switching constant current circuits are all less than or equal to 20A.