Semiconductor laser power supply based on linear constant current and design method thereof

Abstract

The invention provides a semiconductor laser power supply based on linear constant current and a design method thereof, and relates to the technical field of lasers. The system comprises a front-stage charging network and a rear-stage discharging network, wherein the rear-stage discharging network is connected with the front-stage charging network; the post-stage discharge network comprises a voltage reference calibration module, a linear constant current driving module, a broadband pulse control module, an intelligent power switch module, a high-precision sampling feedback module and a multiple follow current protection module. The input end of the voltage reference calibration module is connected with external reference voltage, and the output end is connected with the linear constant-current driving module; the linear constant-current driving module is connected with the broadband pulse control module; the broadband pulse control module is connected with the intelligent power switch module; the intelligent power switch module is connected with the semiconductor laser load. According to the invention, accurate current control can be realized, and current impact during mode switching is avoided.

Description

Technical Field

[0001] This invention belongs to the field of laser technology, and in particular relates to a semiconductor laser power supply and its design method. Background Technology

[0002] Semiconductor lasers, as core components in pulsed laser applications, have become a core support in the field of modern laser technology due to their significant advantages such as high photoelectric conversion efficiency, narrow spectral linewidth, miniaturization, and long lifespan. As laser technology develops towards higher power, higher frequency modulation, and higher precision, semiconductor lasers place more stringent demands on the performance of their driving power supplies, specifically requiring "high-precision constant current, low ripple, high dynamic response, and wide parameter adjustability."

[0003] In the field of industrial laser processing, the stability of the laser's output power directly determines the processing accuracy, requiring the output current fluctuation error of the drive power supply to be ≤±0.5%. In the field of medical diagnostics, the consistency of laser wavelength is crucial, and wavelength stability is highly dependent on the precise control of the drive current. Even a small fluctuation in current (such as ±1%) can cause the wavelength drift to exceed the allowable range. In high-frequency modulation scenarios, such as automotive lidar, the power supply is required to have nanosecond-level pulse rise time and low overshoot characteristics to achieve fast and accurate signal modulation.

[0004] However, existing semiconductor laser power supply technology still has many technical shortcomings that urgently need to be addressed: Insufficient constant current control accuracy: Traditional power supplies mostly use switching power supply topologies. Switching noise causes large output current ripple. Furthermore, when the load characteristics change (such as the equivalent resistance of a semiconductor laser changing with the current) or the input voltage fluctuates, the feedback regulation lags, making it difficult to maintain current stability. The current fluctuation error is generally between ±1% and ±3%, which cannot meet the requirements of high-precision applications.

[0005] Limited pulse drive performance: Existing pulse power supplies have a narrow pulse parameter adjustment range, especially at high frequencies (e.g., ≥10kHz), where the pulse rise time often exceeds 200ns and the overshoot is greater than 10%, resulting in laser pulse waveform distortion and affecting modulation accuracy. At the same time, the switching between pulse mode and constant current mode is not smooth enough, and there is a current surge during mode switching.

[0006] Temperature drift has a significant impact: the performance of core power supply components (such as sampling resistors and operational amplifiers) is greatly affected by temperature. Within a wide operating temperature range of -20℃ to 85℃, temperature drift can cause current fluctuations to increase by more than 30%, which seriously affects the working stability of the laser in extreme environments.

[0007] Inadequate protection mechanisms: Existing power supplies only have simple overcurrent protection functions and lack comprehensive monitoring and rapid response mechanisms for faults such as overvoltage, overtemperature, and device failure. This results in insufficient reliability of the power supply and laser, making the equipment susceptible to damage due to sudden failures.

[0008] To address the aforementioned issues, some research has been conducted in related fields. For example, Chinese patent application number 202110190603.2 proposes a topology that uses a BUCK and a linear constant current source in parallel to improve the instantaneous charging power, but it does not solve the problems of pulse number control and temperature drift. Some academic studies have adopted digital control methods to optimize the constant current accuracy, but these methods suffer from drawbacks such as slow response speed and high cost. Summary of the Invention

[0009] Therefore, the technical problem to be solved by the present invention is to provide a semiconductor laser power supply based on linear constant current and its design method, which can achieve precise current control and avoid current surges during mode switching.

[0010] In a first aspect, the present invention provides a semiconductor laser power supply based on linear constant current, including a front-stage charging network and a rear-stage discharging network, wherein the rear-stage discharging network is connected to the front-stage charging network. The subsequent discharge network includes a voltage reference calibration module, a linear constant current drive module, a wideband pulse control module, an intelligent power switch module, a high-precision sampling feedback module, and a multiple freewheeling protection module. The voltage reference calibration module has an input terminal connected to an external reference voltage and an output terminal connected to the linear constant current drive module, which is used to provide a stable reference voltage. The linear constant current drive module is connected to the wideband pulse control module and is used to generate a constant current drive signal based on the difference between the reference voltage and the feedback voltage. The wideband pulse control module is connected to the intelligent power switch module, which enables the drive current to switch between constant current and off state to form pulse current output. The intelligent power switch module is connected to the semiconductor laser load and is used to output a controlled drive current. The high-precision sampling feedback module is connected to the semiconductor laser load at one end and to the linear constant current drive module at the other end, and is used to collect the feedback voltage. The multiple freewheeling protection module is connected to the intelligent power switch module and the semiconductor laser load.

[0011] Furthermore, the front-end charging network is a DC / DC phase-shifted full-bridge topology; the primary side includes an input capacitor, a full-bridge inverter circuit, a resonant inductor, a DC blocking capacitor, and a high-frequency transformer; the secondary side includes a full-bridge rectifier circuit, an output filter inductor, and an output filter capacitor.

[0012] Furthermore, the voltage reference calibration module includes a first operational amplifier, a first resistor R1, a second resistor R2, a third resistor R3, and a first filter capacitor C1; The input terminal of the first operational amplifier is connected to the first resistor R1 and the second resistor R2; The output terminal of the first operational amplifier is connected to the third resistor R3, and the first filter capacitor C1 is connected in parallel across the third resistor R3.

[0013] Furthermore, the linear constant current drive module includes a second operational amplifier, a fourth resistor R4, a fifth resistor R5, a sixth resistor R6, a seventh resistor R7, and a second filter capacitor C2; The non-inverting input of the second operational amplifier is connected to the fifth resistor R5 and the second filter capacitor C2; The inverting input terminal is connected to the fourth resistor R4 and the sixth resistor R6; the output terminal of the second operational amplifier is connected to the seventh resistor R7.

[0014] Furthermore, the wideband pulse control module includes a first switching transistor Q1, a second switching transistor Q2, an eighth resistor R8, a first diode D1, and a pulse signal generator; The first switching transistor Q1 and the second switching transistor Q2 form a push-pull circuit; The input terminal of the push-pull circuit is connected to the pulse signal generator through the first diode D1; The output terminal of the push-pull circuit is connected to the eighth resistor R8.

[0015] Furthermore, the wideband pulse control module also includes a signal isolation unit and a pulse shaping circuit; the signal isolation unit is an optocoupler, and the pulse shaping circuit consists of an RC circuit and a Schmitt trigger.

[0016] Furthermore, the intelligent power switch module includes a power transistor and a sampling resistor Rc; the source of the power transistor is connected to the eighth resistor R8, and the drain is connected in series with the sampling resistor Rc and the semiconductor laser load; the power transistor is an insulated gate bipolar transistor.

[0017] Furthermore, the multiple freewheeling protection module includes a ninth resistor R9, a tenth resistor R10, a second diode D2, and a third filter capacitor C3; The third filter capacitor C3, the ninth resistor R9, and the tenth resistor R10 are connected in series; the third filter capacitor C3 is connected to the drain of the power transistor; the second diode D2 is connected in parallel across the ninth resistor R9 and the third filter capacitor C3.

[0018] Furthermore, in the DC / DC phase-shifted full-bridge topology, the input capacitor is 1.5mF, the transformer turns ratio is 2, the resonant inductor is 12μH, the DC blocking capacitor is 800nF, the output filter inductor is 380μH, and the output filter capacitor is 10.5mF.

[0019] Secondly, the present invention also provides a design method for a semiconductor laser power supply based on linear constant current, comprising the following steps: Demand analysis and index calibration steps: Based on the rated operating current, voltage range, and pulse parameters of the semiconductor laser load, determine the performance index of the semiconductor laser power supply; the performance index includes peak pulse current, output voltage range, pulse repetition frequency, pulse width, constant current accuracy error, and system efficiency; Topology and module partitioning steps: The front-end charging network selects a DC / DC phase-shifted full-bridge topology; the rear-end discharging network is divided into the voltage reference calibration module, the linear constant current drive module, the wideband pulse control module, the intelligent power switch module, the high-precision sampling feedback module, and the multiple freewheeling protection module; Key parameter calculation and component selection steps: Based on the performance indicators, calculate the key parameters of the front-end charging network, including the parameter values ​​of input capacitance, transformer turns ratio, resonant inductance, and DC blocking capacitor; and select components for each module of the back-end discharging network. Control steps: The front-end charging network controls the phase difference between the primary and secondary voltages by adjusting the phase shift angle of the primary-side bridge arm switch to regulate the transmission power; it utilizes the resonant inductor and switching timing to reduce switching losses; it implements current closed-loop feedback control through the voltage reference calibration module; and it intervenes in the current closed-loop feedback control based on the wideband pulse control module. Simulation verification and implementation steps: Verify the design performance through circuit simulation, and fabricate a semiconductor laser power supply prototype based on the design results for testing and optimization.

[0020] Beneficial effects: This invention outputs a stable reference voltage through a voltage reference calibration module, acquires the load feedback voltage through a high-precision sampling feedback module, amplifies the error signal between the reference voltage and the feedback voltage through a linear constant current drive module, and adjusts the on-resistance of the insulated gate bipolar transistor (IGBT) to achieve precise current control.

[0021] The wideband pulse control module enables pulse current of 0-400A, frequency of 0-1000Hz, pulse width of 0-300μs, rise time of <100ns, and no mode switching impact.

[0022] The pulse signal, after isolation and amplification, is output to the linear constant current control module as a reference for current modulation, thereby driving the pulsed current of the semiconductor laser load module. By accurately reproducing the pulse conditions in actual operating conditions, this module provides a dynamic load testing environment for the system, verifying the response speed and stability of the constant current control under transient conditions, and supporting the performance optimization of the semiconductor laser in high-speed modulation and high peak power application scenarios.

[0023] This invention provides stable operation under wide temperature ranges; the protection mechanism has been expanded from simple overcurrent protection to overvoltage, overtemperature, and follow current protection, with fault response reaching the microsecond level and reducing equipment damage rate by more than 90%.

[0024] It adopts a front-stage phase-shifting full-bridge topology, with a system efficiency of no less than 90%; it supports at least 4 modules in parallel, is compatible with multi-power lasers, and does not require main body reconstruction, reducing upgrade costs. Attached Figure Description

[0025] To make the content of this invention easier to understand, the invention will be further described in detail below with reference to specific embodiments and accompanying drawings.

[0026] Figure 1 This is a circuit topology diagram of the pre-charging network in Embodiment 1 of the present invention; Figure 2 This is a circuit diagram of the post-discharge network control circuit structure in Embodiment 1 of the present invention; Figure 3a This is a pulse charging load test diagram of Embodiment 1 of the present invention; Figure 3b This is a pulse discharge test diagram of Embodiment 1 of the present invention; Figure 4a The waveform diagram of the adjustable pulse current from 0-400A in Embodiment 1 of the present invention is shown. The pulse current is 100A, the repetition frequency is 1000Hz, and the pulse width is 300μs. Figure 4b The waveform diagram of the adjustable pulse current from 0-400A in Embodiment 1 of the present invention is shown. The pulse current is 200A, the repetition frequency is 1000Hz, and the pulse width is 300μs. Figure 4c The waveform diagram of the adjustable pulse current from 0-400A in Embodiment 1 of the present invention is shown. The pulse current is 300A, the repetition frequency is 1000Hz, and the pulse width is 300μs. Figure 4d The waveform diagram of the adjustable pulse current from 0-400A in Embodiment 1 of the present invention is shown. The pulse current is 400A, the repetition frequency is 1000Hz, and the pulse width is 300μs. Figure 5a The waveform diagram of the adjustable repetition frequency of 0-1000Hz in Embodiment 1 of the present invention is shown, with a pulse current of 400A, a repetition frequency of 100Hz, and a pulse width of 300μs. Figure 5b The waveform diagram of the adjustable repetition frequency of 0-1000Hz in Embodiment 1 of the present invention is shown, with a pulse current of 400A, a repetition frequency of 500Hz, and a pulse width of 300μs. Figure 5c The waveform diagram of the adjustable repetition frequency of 0-1000Hz in Embodiment 1 of the present invention is shown, with a pulse current of 400A, a repetition frequency of 1000Hz, and a pulse width of 300μs. Figure 6a The waveform diagram of the pulse width adjustable from 0-300μs in Embodiment 1 of the present invention is shown. The pulse current is 400A, the repetition frequency is 1000Hz, and the pulse width is 100μs. Figure 6b The waveform diagram for the pulse width adjustable from 0 to 300 μs in Embodiment 1 of the present invention is shown. The pulse current is 400 A, the repetition frequency is 1000 Hz, and the pulse width is 300 μs. Detailed Implementation

[0027] The present invention will now be described in detail with reference to the accompanying drawings and embodiments. The principles and features of the present invention are described below with reference to the accompanying drawings. It should be noted that, unless otherwise specified, the embodiments and features described in these embodiments can be combined with each other. The embodiments given are only for explaining the present invention and are not intended to limit the scope of the present invention.

[0028] Due to the shortcomings of existing technologies, developing a semiconductor laser power supply with high-precision constant current control, wide-band pulse drive and strong environmental adaptability has become an urgent need for the development of semiconductor laser technology, and is of great significance for promoting the in-depth expansion of laser applications in various fields.

[0029] This invention provides a semiconductor laser power supply based on linear constant current and its design method. Through the organic combination of modular topology design, high-precision closed-loop control, wideband pulse coordination, and multiple protection mechanisms, the following objectives are achieved: (1) Pulse current peak value: 0-400A adjustable; (2) Output voltage range: 0-200V adaptive; (3) Repetition frequency: Adjustable from 0-1000Hz for single pulse; (4) Pulse width: adjustable from 0-300μs; (5) Overall system efficiency ≥ 90%; (6) Supports ≥4 modules in parallel, with synchronization error between modules ≤20us.

[0030] The modular design enhances the compatibility and expandability of the power supply, making it compatible with semiconductor lasers of different power and models.

[0031] Example 1 Embodiment 1 of the present invention provides a semiconductor laser power supply based on linear constant current, including a pre-stage charging network and a post-stage discharging network. The post-stage discharging network includes a voltage reference calibration module, a linear constant current drive module, an intelligent power switch module, a wideband pulse control module, a high-precision sampling feedback module, a multiple freewheeling protection module, a temperature compensation module, and a fault diagnosis module. These modules work together to form a complete closed-loop control and protection system.

[0032] like Figure 1 As shown, the topology of the front-end charging network is as follows: For a high-power semiconductor laser to operate normally, the front-end charging network must meet two core indicators: first, it must replenish the energy of the capacitive energy storage element within the pulse interval period, ensuring that the energy reserve for a single pulse meets the system requirements; second, it must maintain the voltage at the energy storage element terminals above the laser array threshold voltage during the discharge termination phase, satisfying the constraints of the device's operating characteristic curve. This requires the front-end charging network to have the ability to quickly charge the energy storage capacitor. This module exhibits significant nonlinear load characteristics during the charging cycle: in the initial charging phase, because the capacitive element potential approaches zero, the system's equivalent load impedance is close to a short-circuit state, and it operates in peak current mode. As the current increases to the rated value, the system transitions to a near-open-circuit condition, and the current output drops to the minimum threshold. This impedance change spanning three orders of magnitude poses a severe challenge to the load adaptability of the power supply system. Therefore, the front-end charging network needs to have high efficiency, high power density, and high integration, and a resonant converter capable of soft switching should be selected. Based on the power requirements of the discharge network following the pulse drive source of the semiconductor laser, traditional RC charging power supplies suffer from drawbacks such as low repetition frequency and low charging efficiency, and are therefore not adopted. Thus, a DC / DC phase-shifted full-bridge topology is used for the pre-stage charging network. Its main circuit structure is as follows: Figure 1 As shown, it mainly includes: the primary side containing the input capacitor. (Stable input voltage) ), The resulting full-bridge inverter circuit converts DC to high-frequency AC, along with a resonant inductor. (Suppressing switching stress, assisting soft switching), DC blocking capacitor (To avoid DC bias in transformer T); the high-frequency transformer T is an isolation element, achieving electrical isolation between the primary and secondary sides and voltage ratio (ratio n:1) adjustment; the secondary side is connected via... The full-bridge rectifier circuit converts high-frequency AC into pulsating DC, which is then passed through the output capacitor. Filtering provides a stable output voltage to the load. Its working principle is to change the phase difference between the primary and secondary voltages by adjusting the phase shift angle of the switching transistors on the primary side of the transformer, thereby regulating the transmitted power and achieving output voltage regulation; resonant inductor The auxiliary switching transistor enables zero-voltage switching (ZVS) and reduces switching losses; iLf This refers to the current flowing through the output filter inductor; i o This refers to the output current of the converter; i Co This refers to the current flowing through the output filter capacitor. This topology combines advantages such as isolation, soft switching, and high power density. While ensuring power conversion efficiency, it achieves symmetrical distribution of electrical stress in the power devices through a symmetrical bridge arm structure, resulting in a simpler circuit structure. The control strategy employs PWM modulation and integrates phase modulation and resonant soft-switching technology. Through the coordinated design of the resonant network and switching timing, it achieves a zero-voltage transition operating mode for the power devices. This hybrid control mechanism not only maintains a constant frequency and simplifies control but also significantly reduces switching losses and improves power supply efficiency.

[0033] Design of front-end charging network circuit parameters: In order to achieve the following relevant technical indicators, (1) input voltage: 500VDC; (2) output voltage: 0-200VDC; (3) power: 5kW; (4) switching frequency: 25kHz, it is necessary to design and calculate the parameters of the front-end charging network circuit.

[0034] 1. Input capacitor design The voltage value of the input capacitor is given by the output of the three-phase uncontrolled rectifier bridge, and the line voltage is... 380V, phase voltage The voltage is 220V, and the frequency f is 50Hz. The maximum DC voltage ripple after uncontrolled rectification and filtering is: (1) Minimum DC voltage after uncontrolled rectification: (2) Single-cycle input filter capacitor Energy provided is: (3) in, P For total power, η For overall machine efficiency, we take 90%.

[0035] Minimum filter capacitor value: (4) Take a margin of 1.5: (5) 2. Transformer turns ratio design Input voltage Take 500V, output voltage Take 200V, and assume maximum duty cycle loss. Given a maximum effective duty cycle of 0.2, The transformer turns ratio is 0.8. (6) 3. Resonant Inductor Design Assuming a 30% load, ZVS (Zero Current Per Second) needs to be achieved. (25A), at this time the primary current is: (7) parasitic capacitance of switching transistor C oss The parasitic capacitance of the transformer primary winding is 120pF. It is 0.

[0036] (8) The maximum duty cycle loss is 0.2, that is... : (9) Ultimately, the resonant inductance is set to a value of ,in f s This represents the switching frequency.

[0037] 4. DC blocking capacitor design To avoid the presence of DC components, a DC blocking capacitor is often connected in series on the primary winding of the transformer. The peak-to-peak voltage across the capacitor is less than 10% of the input voltage. (10) I p,max The peak value of the transformer primary current is taken as 10A; The peak value of the voltage across the DC blocking capacitor is taken as 20V.

[0038] 5. Output filter inductor design From the inductor ripple calculation formula, take for Assume the DC component of the inductance. The diode voltage drop is 1.5V. For 0.5V, we get : (11) L f This is the output filter inductor.

[0039] 6. Output filter capacitor design Assuming the output voltage ripple is maximum 1V, discharge time of the subsequent stage 300us: (12) I c，max The maximum current across the capacitor is 35A.

[0040] like Figure 2 As shown, the subsequent discharge network circuit mainly includes a voltage reference calibration module, a linear constant current drive module, an intelligent power switch module, a wideband pulse control module, a high-precision sampling feedback module, and a multiple freewheeling protection module.

[0041] Voltage reference calibration module: This module is fundamental to achieving high-precision constant current control. Its core function is to provide a stable, low-noise reference voltage. The voltage reference calibration module includes a first operational amplifier, a first resistor R1, a second resistor R2, a third resistor R3, and a first filter capacitor C1.

[0042] The first operational amplifier uses an OPA320 to construct a highly stable voltage follower structure. The OPA320 features low offset voltage, low drift, and high input impedance, effectively ensuring the stability of the reference voltage. An external programmable reference voltage Vref is connected to the non-inverting input of the OPA320 via a shielded cable. The shielded cable reduces the impact of electromagnetic interference on the reference signal. The non-inverting input of the OPA320 is connected to the external reference voltage Vref, and the input is connected to a first resistor R1 and a second resistor R2. The output of the OPA320 is connected to a third resistor R3, and a first filter capacitor C1 is connected in parallel across the third resistor R3. This connection method constitutes the feedback network of the voltage follower.

[0043] Linear Constant Current Drive Module: The linear constant current drive module is the core component for achieving precise current control. It includes a second operational amplifier, a fourth resistor R4, a fifth resistor R5, a sixth resistor R6, a seventh resistor R7, and a second filter capacitor C2. The second operational amplifier uses a low-offset operational amplifier OPA27G as its core component. The OPA27G features high gain, wide bandwidth, and low noise, enabling precise amplification and fast response of error signals. The non-inverting input of the second operational amplifier OPA27G is connected to the output of the voltage reference calibration module via the fifth resistor R5, and is also connected to the second filter capacitor C2 before being grounded. The inverting input is connected to the voltage divider node of the sampling feedback module. The inverting input is connected to the fourth resistor R4 and the sixth resistor R6 respectively; the output of the second operational amplifier OPA27G is connected to the seventh resistor R7.

[0044] The seventh resistor R7 is connected at one end to the output of the second operational amplifier OPA27G and at the other end to the gate of the first switching transistor Q1. When there is no drive signal, it pulls the gate voltage low to ground, ensuring that the first switching transistor Q1 is reliably turned off. The output signal of the second operational amplifier OPA27G is transmitted to the gate of the first switching transistor Q1 to control its conduction level.

[0045] Wideband pulse control module: This module realizes the generation, isolation, shaping and driving of pulse signals. Its core function is to work with constant current control to realize wideband pulse current output.

[0046] The wideband pulse control module includes a first switching transistor Q1, a second switching transistor Q2, an eighth resistor R8, a first diode D1, and a pulse signal generator; the first switching transistor Q1 and the second switching transistor Q2 form a push-pull circuit, and the output of the push-pull circuit is connected to the eighth resistor R8.

[0047] The pulse signal generator `pulse` is connected to the base of the second switching transistor Q2 via a first diode D1. The emitter of the second switching transistor Q2 is grounded, and its collector is connected to the drain of the power transistor. The pulse signal is generated by an external signal generator or an internal controller, and its parameters, including repetition frequency (0-1000Hz), pulse width (0-300ns), and pulse current (0A-400A), can be set via a host computer or a local knob. V1 is the feedback adjustment voltage, and V2 is the pulse setpoint voltage. The pulse current is output through the periodic change of the pulse signal.

[0048] In a preferred embodiment, the wideband pulse control module also includes a signal isolation unit and a pulse shaping circuit. The signal isolation unit uses a 6N137 optocoupler to achieve electrical isolation of the pulse signal, with an isolation voltage ≥2500Vrms, effectively suppressing electromagnetic interference and ensuring the electrical safety of the control circuit and power circuit. The pulse shaping circuit consists of an RC circuit and a Schmitt trigger, used to optimize the pulse edge characteristics, ensuring a pulse rise time <100ns, a fall time <80ns, and jitter ≤±2ns.

[0049] When the pulse signal is high, the second switching transistor Q2 is turned on, forcibly pulling down the drain voltage of the power transistor to ≤0.5V, causing the power transistor to turn off quickly. When the pulse signal is low, the second switching transistor Q2 is turned off, the circuit returns to constant current control, and the load current remains constant under closed-loop regulation. The pulse current output is achieved through the periodic change of the pulse signal, and the deviation of the pulse parameters from the set value is ≤±1%.

[0050] Intelligent Power Switch Module: This module handles power amplification and current output. Its core components are a power transistor and a precision sampling resistor Rc. The power transistor is a high-voltage, high-current IGBT (model FZ800R12KE3), with a rated voltage of 1200V, a rated current of 800A, an on-time ≤50ns, and an off-time ≤80ns, suitable for driving high-power semiconductor lasers. The source of the power transistor is connected to resistor R8, and the drain is connected in series with the sampling resistor Rc and the semiconductor laser load to achieve current output and detection. The precision sampling resistor Rc is a key component for current detection. Made of alloy material, it features low temperature drift and high stability, ensuring detection accuracy over high current and wide temperature ranges. Its low parasitic inductance avoids signal interference under high-frequency conditions, guaranteeing the authenticity of the sampled signal.

[0051] High-precision sampling feedback module: This module realizes real-time detection and feedback of load current, which is a key link in closed-loop constant current control. The voltage divider node is connected to the inverting input of the operational amplifier OPA27G; it forms a closed-loop comparison with the reference voltage Vs, providing a basis for the generation of error signals.

[0052] Multiple freewheeling protection module: This module protects power transistors and semiconductor laser loads from damage caused by sudden current changes or reverse voltage. The multiple freewheeling protection module includes a ninth resistor R9, a tenth resistor R10, a second diode D2, and a third filter capacitor C3.

[0053] The third filter capacitor C3, the ninth resistor R9, and the tenth resistor R10 are connected in series; the third filter capacitor C3 is connected to the drain of the power transistor; the second diode D2 is connected in parallel across the ninth resistor R9 and the third filter capacitor C3.

[0054] The third filter capacitor C3 is selected with a capacitance of 10μF to suppress the load voltage ripple, so that the voltage ripple is ≤5Vpp, ensuring the stable operation of the laser.

[0055] Furthermore, this embodiment also includes: Temperature Compensation Module: This module compensates for the impact of temperature changes on the output current, improving the power supply's wide-temperature adaptability. It includes a temperature sensor, a signal processing unit, and a compensation circuit. The high-precision platinum resistance thermometer PT100 is used, positioned close to the precision sampling resistor Rc and power transistor, to collect real-time temperature data from key components. The temperature measurement range is -20℃ to 85℃, with a measurement accuracy ≤ ±0.1℃. The signal processing unit consists of an instrumentation amplifier INA128 and an A / D converter ADS1256. The instrumentation amplifier amplifies the weak resistance change signal from the platinum resistance thermometer into a voltage signal, and the A / D converter converts the analog voltage signal into a digital signal, which is then transmitted to the microcontroller STM32F407. The compensation circuit consists of a digital-to-analog converter DAC8552 and an operational amplifier. The microcontroller calculates the compensation amount based on the temperature data, outputs the corresponding compensation voltage through the DAC8552, and after adjustment by the operational amplifier, it is superimposed on the error signal of the linear constant current drive module to compensate for current drift caused by temperature changes. Through temperature compensation, the power supply's output current fluctuation error is ≤ ±0.2% within the range of -20℃ to 85℃.

[0056] Fault Diagnosis Module: This module provides comprehensive monitoring and fault protection for the power supply's operating status, including an overcurrent detection unit, an overvoltage detection unit, an overtemperature detection unit, and an alarm output unit. The overcurrent detection unit monitors the load current by acquiring the voltage signal across a precision sampling resistor Rc. When the current exceeds a set threshold (adjustable within the range of 0A-400A), it outputs an overcurrent fault signal. The overvoltage detection unit is shared with the overvoltage detection unit of the multiple freewheeling protection module, monitoring the input voltage and load voltage. When the voltage exceeds a threshold, it outputs an overvoltage fault signal. The overtemperature detection unit acquires the temperature of the power transistor, heat sink, and ambient temperature using a temperature sensor. When the temperature exceeds 85℃, it outputs an overtemperature fault signal. The alarm output unit includes an audible and visual alarm module and a communication module. When a fault is detected, the audible and visual alarm module emits a flashing red alarm light and a buzzer sound. The communication module uploads the fault information to the host computer via RS485 or CAN bus, simultaneously triggering power supply shutdown protection to prevent the fault from escalating.

[0057] The hardware selection and parameter settings for this embodiment are as follows: Pre-amplifier charging network circuit parameters: input capacitor 1.5mF, transformer ratio 2:1, resonant inductor 12μH, DC blocking capacitor 800nF, output filter inductor 380μH, output filter capacitor 10.5mF.

[0058] Voltage reference calibration module: Operational amplifier OPA320, resistor R1=1kΩ, R2=10kΩ, first filter capacitor C1=10nF (NP0 material), external reference voltage Vref=0V-5V programmable.

[0059] Linear constant current drive module: Operational amplifier OPA27G, drive resistor R4=2kΩ, pull-down resistor R5=10kΩ, error amplification factor is 100 times.

[0060] Intelligent power switch module: power transistor FZ800R12KE3 (1200V / 800A), precision sampling resistor Rc=1.5mΩ (±0.1%, 5ppm / ℃), current limiting resistor R6=1kΩ.

[0061] Wideband pulse control module: Second switching transistor Q2=2N3904 (NPN type), optocoupler 6N137, current limiting resistor R7=1kΩ, pulse frequency 0Hz-1000Hz, duty cycle 0.1%-99.9%.

[0062] High-precision sampling feedback module: voltage divider resistors R8=10kΩ, R9=1kΩ, R10=1kΩ (all with ±0.1% accuracy), instrumentation amplifier INA128, A / D converter ADS1256, and second-order active low-pass filter with a cutoff frequency of 10kHz.

[0063] Multiple freewheeling protection module: freewheeling diodes D1 and D2 = FRD-50A / 1200V (fast recovery type), third filter capacitor C3 = 10μF / 450V, voltage comparator LMV339, overvoltage protection threshold is 100V.

[0064] A prototype semiconductor laser power supply based on linear constant current was successfully developed and debugged, achieving an output pulse current of 400A, a pulse width of 300μs, and a repetition frequency of 1000Hz, meeting the expected technical specifications and verifying the feasibility and effectiveness of the proposed solution. Testing of the 400A pulse power supply's high-energy charging and discharging networks demonstrated the mastery of fast charging parameter design methods, meeting the design requirements of high-current charging networks.

[0065] like Figures 3a-3b As shown, under pulse repetition frequency load, the energy storage capacitor voltage remains stable (voltage fluctuation <5V). Testing of the 400A pulse power supply high-energy charging and discharging network demonstrates the mastery of fast charging parameter design methods, meeting the design requirements of high-current charging networks, and ensuring stable energy storage capacitor voltage under pulse repetition frequency load.

[0066] The pulse charging test curve shows that the charging load current ranges from 200A to >400A. According to the curve, the voltage fluctuation is <5V, and the voltage fluctuation of the energy storage capacitor is stable.

[0067] The pulse discharge test curve shows that the output current is adjustable from 0 to 400A.

[0068] like Figures 4a-4dAs shown, the semiconductor laser power supply based on linear constant current of the present invention can achieve adjustable pulse current from 0-400A.

[0069] like Figures 5a-5c As shown, the semiconductor laser power supply based on linear constant current of the present invention can achieve an adjustable repetition frequency of 0-1000Hz.

[0070] like Figures 6a-6b As shown, the semiconductor laser power supply based on linear constant current of the present invention can achieve pulse width adjustable from 0-300μs.

[0071] Figures 4a-6b In the diagram, the upper waveform is the voltage waveform, and the lower waveform is the current waveform.

[0072] Figures 3a-6b In the diagram, the solid line and the dashed line are two independent, movable measurement cursor lines.

[0073] The linear constant current-based semiconductor laser power supply of this invention can be widely used in the following fields: Industrial laser processing, such as laser cutting, laser welding, and laser marking, uses high-precision constant current control to ensure consistent processing accuracy, and wideband pulse drive to adapt to the processing needs of different materials.

[0074] Medical diagnostics: such as laser therapy equipment, laser endoscopes, etc. Stable laser power output can improve treatment effectiveness and safety, and low noise characteristics can avoid interference with medical test signals.

[0075] Optical communication: such as high-speed fiber optic communication systems, high-frequency pulse drive can achieve high-speed signal modulation, improving communication speed and stability.

[0076] Scientific research detection: such as lidar, spectral analysis equipment, etc., with wide parameter adjustment and high dynamic response, can meet the testing needs of different scientific research scenarios.

[0077] Vehicle-mounted LiDAR: High-frequency, low-overshoot pulse output can improve the detection accuracy and range of the radar, and its wide temperature adaptability can be adapted to the complex working environment of vehicles.

[0078] Example 2 This embodiment provides a semiconductor laser power supply design method based on linear constant current, including the following steps: S1. Requirements Analysis and Indicator Criteria Application scenario matching: Identify the target application field (such as industrial laser processing, medical diagnosis, automotive lidar, etc.) and extract the core electrical requirements of semiconductor lasers in this scenario, including rated operating current, voltage range, pulse parameters (repetition frequency, width) and environmental adaptability requirements (such as wide temperature range of -20℃ to 85℃).

[0079] Performance index quantification: Key technical indicators are set according to scenario requirements, including: peak pulse current (0~400A adjustable), adaptive output voltage range (0~200V), constant current accuracy (fluctuation error ≤±0.2%), system efficiency (≥90%), module synchronization error (≤20μs) and protection response time (microsecond level), forming an index constraint document.

[0080] Laser characteristic adaptation: Obtain parameters such as the equivalent resistance, threshold voltage, and maximum withstand current / voltage of the target laser to determine the energy storage requirements of the front-end charging network (such as the amount of energy replenishment during pulse intervals) and the current adjustment range of the rear-end discharging network, so as to avoid device overload.

[0081] S2. Topology and Modular Design Front-end charging network topology selection: Based on the 5kW power requirement and soft-switching characteristics, a DC / DC phase-shifted full-bridge topology is selected. The connection relationships of the primary-side full-bridge inverter circuit (S1~S4), resonant inductor (Lr), DC blocking capacitor (Cb), high-frequency transformer (T), and secondary-side full-bridge rectifier circuit (D1~D4) are defined, and the topology diagram is drawn (e.g., Figure 1 This ensures that the dual requirements of "fast charging + stable voltage" are met.

[0082] The post-discharge network module is broken down into eight functional modules: voltage reference calibration, linear constant current drive, intelligent power switch, wideband pulse control, high-precision sampling feedback, multiple freewheeling protection, temperature compensation, and fault diagnosis. The signal flow of each module is clearly defined (e.g., reference voltage → constant current drive → power output → sampling feedback), constructing a closed-loop control and protection system framework (e.g., ...). Figure 2 ).

[0083] Compatibility design: Reserves ≥4 parallel interface channels for modules, designs synchronous signal transmission links to ensure balanced current distribution among modules, synchronization error ≤20μs, and adapts to the expansion needs of lasers with different power.

[0084] S3. Key Module Parameter Calculation and Component Selection Pre-charger network parameter design: Input capacitance (Cin) calculation: Based on the voltage ripple after rectification of the 380V line voltage (≤38V) and the energy demand of a single cycle (37J), the minimum capacitance value is calculated by formula (1)~(5), and Cin=1.5mF is determined with a margin of 1.5. Transformer turns ratio (n) design: Based on the input voltage (500V), output voltage (200V) and maximum duty cycle loss (0.2), the turns ratio n=4 is calculated using formula (6); Design of resonant inductor (Lr) and DC blocking capacitor (Cb): Based on the requirement of 30% load ZVS, combined with the switching frequency (25kHz) and parasitic capacitance parameters, Lr=12μH and Cb=800nF are determined by formula (7)~(10); Output filter component selection: Based on the ripple requirements (voltage ripple ≤ 1V), calculate the output filter inductance as 380μH and the filter capacitor parameters using formulas (11) to (12) to ensure stable charging voltage.

[0085] Selection of components for downstream modules: Voltage reference calibration module: The low offset operational amplifier OPA320 is selected, along with 1kΩ (R1), 10kΩ (R2) high-precision resistors and the first filter capacitor (C1). The first filter capacitor (C1) is a 10nF NP0 filter capacitor. Intelligent power switch module: adopts 1200V / 800AIGBT (FZ800R12KE3) and 1.5mΩ (±0.1% accuracy) alloy sampling resistor (Rc); Wideband pulse control module: Select optocoupler 6N137 (isolation voltage ≥2500Vrms) and high-speed NPN transistor 2N3904 (switching speed ≤50ns); S4. Control Strategy and Algorithm Design Pre-charge control: A hybrid strategy of "PWM modulation + phase modulation + resonant soft switching" is adopted. By adjusting the phase shift angle of the primary side bridge arm switch, the phase difference between the primary and secondary voltages is controlled to regulate the transmission power. The resonant inductor (Lr) is used in conjunction with the switching timing to reduce switching losses and ensure an efficiency of ≥90% at a switching frequency of 25kHz.

[0086] Post-stage constant current and pulse coordinated control: Closed-loop constant current control: The voltage reference calibration module outputs a stable Vs, the high-precision sampling feedback module collects the load voltage Vref, and the linear constant current drive module (OPA27G) amplifies the error signal between Vs and Vref, adjusts the IGBT on-resistance, and achieves precise current control. Wideband Pulse Control: Generates configurable pulse sequence signals with adjustable frequency, duty cycle, and amplitude parameters to simulate pulse drive requirements in real-world applications. The pulse signal is isolated and amplified before being output to the linear constant current control module as a current modulation reference, enabling pulsed current drive of the semiconductor laser load module. By accurately reproducing the pulse conditions in actual operating conditions, this module provides a dynamic load testing environment for the system, verifying the response speed and stability of the constant current control under transient conditions, and supporting performance optimization of the semiconductor laser in high-speed modulation and high peak power applications.

[0087] S5. Simulation Verification and PCB Design Simulation Analysis: A simulation model of the front-end phase-shifted full-bridge and the rear-end closed-loop control was built using PLECS simulation software to verify: Pre-charger efficiency, soft-switching effect, and voltage ripple; The accuracy of the post-stage constant current, the pulse waveform distortion, and the temperature drift compensation effect; Improve the response speed of the protection mechanism under fault conditions (overcurrent, overvoltage, overtemperature) and optimize control parameters.

[0088] PCB Layout Design: Power circuits (such as IGBTs and sampling resistors) use short-path, wide-line wiring to reduce parasitic inductance; Control signals (such as reference voltage and sampling feedback) use shielded wiring and single-point grounding to avoid electromagnetic interference; Heat-generating components (IGBTs, transformers) are placed near heat dissipation areas, with space reserved for heat sink installation to ensure that the component temperature is ≤85℃ under high-temperature operating conditions.

[0089] S6. Prototyping and Performance Testing Prototype fabrication: Based on the PCB design and component selection list, solder and assemble the power supply prototype, complete the inter-module wiring and interface debugging, and ensure that each module is powered normally and that signal transmission is interference-free.

[0090] Performance testing: Basic parameter testing: Use an oscilloscope and precision multimeter to test the pulse current (adjustable from 0 to 400A), repetition frequency (adjustable from 0 to 1000Hz), and pulse width (adjustable from 0 to 300μs) to verify whether the indicators meet the standards (e.g., Figures 4a-6b ); Efficiency and stability testing: Test system efficiency under different loads (20%~100%) to ensure ≥90%; conduct 24-hour continuous operation testing to monitor current fluctuations and voltage stability; Environmental adaptability testing: Current drift was tested in a temperature chamber ranging from -20℃ to 85℃, and ripple suppression was tested in an electromagnetic compatibility (EMC) environment. S7. Optimization, Iteration, and Finalization Problem rectification: For problems found in the test (such as pulse overshoot, excessive low temperature drift), adjust parameters (such as optimizing the pulse shaping RC value, enhancing the temperature compensation algorithm) or replace components (such as using a sampling resistor with a lower temperature coefficient). Batch verification: Produce 3-5 prototypes for consistency testing to verify the stability of the production process and optimize BOM costs and assembly efficiency; Finalization and archiving: The final design drawings, component list, control program and test report are generated, the power supply design is finalized, and it is ready for mass production and engineering application.

[0091] This invention addresses existing pain points, provides crucial power support for laser technologies in multiple fields, and achieves: Significant improvement in constant current accuracy: Existing power supply current fluctuations are generally ±1% to ±3%. This invention, through a low offset reference source, ±0.1% accuracy alloy sampling resistor, and PT100 temperature compensation, achieves current fluctuations ≤ ±0.2% and ripple ≤ 0.5mVpp within the range of -20℃ to 85℃, meeting the high-precision requirements of laser processing and medical diagnosis.

[0092] Breakthrough in pulse performance: Existing high-frequency pulses have a rise time of over 200ns and a frequency limit of only 1kHz. This invention achieves pulse current of 0-400A, frequency of 0-1000Hz, width of 0-300μs, rise time of <100ns, no mode switching impact, and is suitable for high-frequency scenarios such as vehicle-mounted LiDAR.

[0093] Wide operating temperature range and high reliability: Existing power supplies experience a 30% increase in current fluctuation over a wide operating temperature range, while this invention maintains stability under wide operating temperature conditions; the protection mechanism has been expanded from simple overcurrent protection to overvoltage, overtemperature, and freewheeling protection, with fault response reaching the microsecond level and equipment failure rate reduced by more than 90%.

[0094] High efficiency and scalability: The front-end phase-shifting full-bridge topology achieves a system efficiency of ≥90%; it supports ≥4 modules in parallel, adapts to multi-power lasers, eliminates the need for main body reconstruction, and reduces upgrade costs.

[0095] This invention is applicable to driving scenarios of high-power, high-frequency modulated semiconductor lasers and can be widely used in many fields such as industrial laser processing, medical diagnosis, optical communication, scientific research and exploration, and vehicle-mounted lidar.

[0096] Obviously, the above embodiments are merely illustrative examples for clear explanation and are not intended to limit the implementation. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations here. However, obvious variations or modifications derived therefrom are still within the scope of protection of this invention.

Claims

1. A linear constant current based semiconductor laser power supply, characterized by, The front-stage charging network and the rear-stage discharging network are connected; The rear-stage discharging network comprises a voltage reference calibration module, a linear constant current driving module, a wideband pulse control module, an intelligent power switch module, a high-precision sampling feedback module and a multiple freewheeling protection module. The voltage reference calibration module is connected with an external reference voltage at an input end and connected with the linear constant current driving module at an output end, and is used for providing a stable reference voltage. The linear constant current driving module is connected with the wideband pulse control module, and is used for generating a constant current driving signal according to a difference between the reference voltage and a feedback voltage. The wideband pulse control module is connected with the intelligent power switch module, and is used for switching the driving current between the constant current and an off state to form a pulse current output. The intelligent power switch module is connected with a semiconductor laser load, and is used for outputting a controlled driving current. The high-precision sampling feedback module is connected with the semiconductor laser load at one end and connected with the linear constant current driving module at the other end, and is used for collecting the feedback voltage. The multiple freewheeling protection module is connected with the intelligent power switch module and the semiconductor laser load.

2. The linear constant current based semiconductor laser power supply of claim 1, wherein, The front-stage charging network is a DC / DC phase-shifted full-bridge topology structure; the primary side comprises an input capacitor, a full-bridge inverter circuit, a resonant inductor, a DC blocking capacitor and a high-frequency transformer; the secondary side comprises a full-bridge rectifier circuit, an output filter inductor and an output filter capacitor.

3. The linear constant current based semiconductor laser power supply of claim 1, wherein, The voltage reference calibration module comprises a first operational amplifier, a first resistor R1, a second resistor R2, a third resistor R3 and a first filter capacitor C1. The input end of the first operational amplifier is connected with the first resistor R1 and the second resistor R2. The output end of the first operational amplifier is connected with the third resistor R3, and the first filter capacitor C1 is connected in parallel across the third resistor R3.

4. The linear constant current based semiconductor laser power supply of claim 1, wherein, The linear constant current driving module comprises a second operational amplifier, a fourth resistor R4, a fifth resistor R5, a sixth resistor R6, a seventh resistor R7 and a second filter capacitor C2. The non-inverting input end of the second operational amplifier is connected with the fifth resistor R5 and the second filter capacitor C2. The inverting input end is connected with the fourth resistor R4 and the sixth resistor R6; and the output end of the second operational amplifier is connected with the seventh resistor R7.

5. The linear constant current based semiconductor laser power supply of claim 1, wherein, The wideband pulse control module comprises a first switch transistor Q1, a second switch transistor Q2, an eighth resistor R8, a first diode D1 and a pulse signal generator. The first switch transistor Q1 and the second switch transistor Q2 constitute a push-pull circuit. The input end of the push-pull circuit is connected with the pulse signal generator through the first diode D1. The output end of the push-pull circuit is connected with the eighth resistor R8.

6. The linear constant current based semiconductor laser power supply of claim 5, wherein, The wideband pulse control module further comprises a signal isolation unit and a pulse shaping circuit; the signal isolation unit is an optoelectronic coupler, and the pulse shaping circuit is composed of an RC circuit and a Schmitt trigger.

7. The linear constant current based semiconductor laser power supply of claim 5, wherein, The intelligent power switch module comprises a power transistor and a sampling resistor Rc; the source of the power transistor is connected with the eighth resistor R8, and the drain is connected with the sampling resistor Rc and the semiconductor laser load in sequence; the power transistor is an insulated gate bipolar transistor.

8. The linear constant current based semiconductor laser power supply of claim 7, wherein, The multiple freewheeling protection module comprises a ninth resistor R9, a tenth resistor R10, a second diode D2 and a third filter capacitor C3. The third filter capacitor C3, the ninth resistor R9 and the tenth resistor R10 are connected in sequence; the third filter capacitor C3 is connected with the drain of the power transistor; the second diode D2 is connected in parallel across the ninth resistor R9 and the third filter capacitor C3.

9. The linear constant current based semiconductor laser power supply of claim 2, wherein, In the DC / DC phase-shifted full-bridge topology, the input capacitor is 1.5 mF, the transformer ratio is 2, the resonant inductance is 12 μH, the DC blocking capacitor is 800 nF, the output filter inductance is 380 μH, and the output filter capacitor is 10.5 mF.

10. A method of designing a linear constant current based semiconductor laser power supply according to any one of claims 1-9, characterized by, The method comprises the following steps: The demand analysis and index calibration step: according to the rated working current, voltage range and pulse parameters of the semiconductor laser load, the performance index of the semiconductor laser power supply is determined; the performance index comprises pulse current peak value, output voltage range, pulse repetition frequency, pulse width, constant current accuracy error and system efficiency; The topology architecture and module division step: the front-stage charging network selects a DC / DC phase-shifted full-bridge topology; the rear-stage discharging network is divided into the voltage reference calibration module, the linear constant current drive module, the wide-frequency pulse control module, the intelligent power switch module, the high-precision sampling feedback module and the multiple freewheeling protection module; The key parameter calculation and device selection step: based on the performance index, the key parameters of the front-stage charging network are calculated, and the key parameters comprise the parameter values of the input capacitor, the transformer ratio, the resonant inductance and the DC blocking capacitor; the devices of each module of the rear-stage discharging network are selected; The control step: the front-stage charging network controls the phase difference of the primary and secondary voltages by adjusting the phase-shifted angle of the primary bridge arm switch tube to control the transmission power; the resonant inductance and the switching time sequence are cooperated to reduce the switching loss; the current closed-loop feedback control is realized through the voltage reference calibration module; the current closed-loop feedback control is intervened based on the wide-frequency pulse control module; The simulation verification and implementation step: the design performance is verified through circuit simulation, and the semiconductor laser power supply prototype is manufactured according to the design results for testing and optimization.

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