TEC control circuit and control method for pump laser temperature control

Abstract

The invention provides a TEC control circuit for pump laser temperature control and a control method, and relates to the technical field of semiconductor cooler control. The control circuit comprises a temperature acquisition circuit, a differential amplification circuit, a PID (Proportion Integration Differentiation) control circuit, a TEC control signal generating circuit and a TEC driving circuit, the temperature acquisition circuit, the differential amplification circuit, the PID control circuit, the TEC control signal generating circuit and the TEC driving circuit are electrically connected in sequence, and the temperature acquisition circuit and the TEC driving circuit are respectively and electrically connected with the pump laser. According to the invention, the problem that the cost cannot be saved and the efficient, stable, reliable and accurate temperature change control cannot be carried out on the pump laser due to the limitation of several common modes for controlling the TEC in the practical application at present is solved.

Description

Technical Field

[0001] The invention relates to the technical field of semiconductor refrigerator control, in particular to a TEC control circuit and a control method for temperature control of a pump laser. Background Art

[0002] With the continuous advancement of science and technology, the application of laser communication technology is becoming more and more extensive. As one of the key devices in laser communication, the core component of the optical amplifier includes the pump laser. The pump laser will generate a lot of heat during operation. The temperature change caused by the heat will cause the output wavelength of the laser to deviate, and will also make the signal light power output unstable, which will eventually lead to a serious decline in communication quality. In order to solve the above problems, the prior art adopts the method of integrating a semiconductor cooler in the pump laser. The semiconductor cooler is TEC (Thermoelectric cooler). TEC can utilize the semiconductor thermoelectric effect to heat or cool the pump laser under corresponding control, thereby achieving the effect of controlling the temperature change of the laser. However, the several commonly used methods for controlling TEC currently have limitations in practical applications, specifically:

[0003] In the control method using hardware circuits and software: the program logic inside the single-chip microcomputer is mainly used to control the working mode of the TEC; for example, the Chinese patent with publication number CN113625802A provides an intelligent TEC temperature control circuit, including a single-chip microcomputer main control circuit connected to the TEC, a temperature acquisition circuit, etc. However, the software operation used in this method is more susceptible to the influence of external interrupt signals, and the loop control time is long and there is a certain degree of uncertainty, which will greatly affect the control stability; in addition, the control method contains both operation software and hardware circuits, making the structure more complicated, which will lead to higher costs and inconvenience in maintenance.

[0004] In the control method using TEC dedicated chip: directly use TEC driver chip to control TEC heating or cooling; for example, Chinese patent with publication number CN103076827A provides a high-precision temperature control device in a small range, in which TEC driver chip is used to output temperature control signal to TEC cooling plate, and TEC cooling plate heats or cools the temperature control object. However, the TEC driver chip used in this method is generally more expensive, and the construction of peripheral circuits is also more complicated.

[0005] In the control method of using discrete components to build a TEC control circuit: there are design defects in the circuit used, which may lead to low temperature control accuracy. Some may also cause problems such as intermittent surge current in the optical module, making the pump laser unable to work stably; in addition, it also has the disadvantages of low power and high power consumption.

[0006] In summary, the present invention provides a TEC control circuit and a control method for temperature control of a pump laser. Summary of the invention

[0007] The purpose of the present invention is to provide a TEC control circuit and control method for temperature control of a pump laser, so as to solve the problem mentioned in the above background technology that the several commonly used methods for controlling TEC have limitations in practical applications, which leads to the inability to efficiently, stably, reliably and accurately control the temperature change of the pump laser while saving costs.

[0008] The present invention is achieved by adopting the following technical solutions:

[0009] A TEC control circuit for temperature control of a pump laser comprises a temperature acquisition circuit, a differential amplifier circuit, a PID control circuit, a TEC control signal generating circuit and a TEC driving circuit, wherein the temperature acquisition circuit, the differential amplifier circuit, the PID control circuit, the TEC control signal generating circuit and the TEC driving circuit are electrically connected in sequence, and the temperature acquisition circuit and the TEC driving circuit are also electrically connected to the pump laser respectively; the temperature acquisition circuit is used to acquire the temperature value of the pump laser; the differential amplifier circuit is used to obtain the difference between the temperature value and the set temperature value and perform differential amplification; the PID control circuit is used to perform proportional integral differential operation on the difference; the TEC control signal generating circuit is used to automatically generate a PWM control signal for controlling TEC heating or cooling; and the TEC driving circuit is used to drive the TEC accordingly according to the PWM control signal.

[0010] The TEC control circuit provided by the present invention is constructed by discrete devices, and has the advantages of simple circuit and low cost. On this basis: by setting a differential amplifier circuit, the common mode component of the differential signal in the line can be suppressed, and the overall anti-interference ability of the control circuit is improved, so that the temperature control accuracy is higher; by setting a PID control circuit, the overall response speed of the control circuit can be improved and the circuit oscillation can be reduced through the simultaneous action of proportion, integration and differentiation, and the generation of surge current can be suppressed, so that the entire temperature control process of TEC is smoother; by setting a TEC control signal generating circuit, a PWM control signal for controlling TEC can be generated, and there is no need to use a special PWM integrated chip, which can effectively reduce costs.

[0011] Furthermore, the TEC driving circuit adopts an H-bridge circuit, which includes four transistors, four base bias resistors and four diodes; the four base bias resistors are respectively connected to the bases of the four transistors, the four transistors include two passive trigger transistors and two linkage trigger transistors, and the two diodes are connected between the two passive trigger transistors and the two linkage trigger transistors.

[0012] Furthermore, the input signal of the base of one of the passively triggered transistors is the heating temperature control signal TEC_CTRL+ in the PWM control signal, and the input signal of the base of the other passively triggered transistor is the cooling temperature control signal TEC_CTRL- in the PWM control signal.

[0013] The TEC driving circuit in the present TEC control circuit adopts an optimized H-bridge circuit, specifically: the traditional H-bridge circuit is usually mainly composed of four MOS tubes, and four control signals are used to realize the opening and closing of two of the MOS tubes, thereby controlling the current direction of the TEC; this method is prone to abnormal control signal timing due to the large number of control signals, which will lead to power short circuit, rapid increase of current, and the problem of MOS tube temperature rising sharply and burning out. In the present invention, two base bias resistors are set to provide bias current to two linkage trigger transistors, so these two linkage trigger transistors do not need additional control signals; when a passive trigger transistor is turned on, a corresponding linkage trigger transistor will become cut-off due to the reduction of base voltage, thereby controlling the flow direction of current flowing through TEC, thereby controlling the working mode of TEC; two diodes play the role of reverse cut-off. Therefore, the present H-bridge circuit only needs to use two control signals to realize the control of the TEC working mode. Compared with the traditional H-bridge circuit, the required hardware resources are less, and the risk of failure is reduced, and the safety and stability of the circuit are improved.

[0014] Furthermore, the temperature acquisition circuit includes a resistance temperature detector RT, one end of the resistance temperature detector RT is connected to one end of the thermistor NTC inside the pump laser, and the other end of the resistance temperature detector RT is connected to the differential amplifier circuit.

[0015] Furthermore, the differential amplifier circuit includes a bridge circuit, two input resistors, a bias resistor R12, a first operational amplifier U1A and a feedback resistor R13; the bridge circuit is connected to the non-inverting input terminal of the first operational amplifier U1A through one of the input resistors, the resistance temperature detector RT is connected to the inverting input terminal of the first operational amplifier U1A through another input resistor, and the output terminal of the first operational amplifier U1A is connected to the PID control circuit.

[0016] Furthermore, the PID control circuit includes a common-phase input resistor R14 and a proportional-integral-differential controller, the proportional-integral-differential controller includes a second operational amplifier U1B, two resistors and three capacitors, and the output end of the proportional-integral-differential controller is connected to the TEC control signal generating circuit.

[0017] Furthermore, the TEC control signal generating circuit includes a third operational amplifier U1C and a fourth operational amplifier U1D.

[0018] A TEC control method for temperature control of a pump laser, using the above-mentioned TEC control circuit for temperature control of a pump laser, comprises the following steps:

[0019] Step 1), after the pump laser is powered on, the temperature acquisition circuit acquires the temperature value of the pump laser in real time, and outputs the acquired temperature value to the differential amplifier circuit in the form of a voltage signal;

[0020] Step 2), the differential amplifier circuit performs differential amplification on the collected temperature value based on the set temperature value and outputs the result to the PID control circuit;

[0021] Step 3), the PID control circuit performs proportional integral differential operation, and outputs the calculated value to the TEC control signal generating circuit;

[0022] Step 4), the TEC control signal generating circuit automatically generates a PWM control signal for controlling TEC heating or cooling based on the calculated value, and outputs the PWM control signal to the TEC driving circuit;

[0023] Step 5), the TEC driving circuit is used to drive the TEC according to the PWM control signal, so that the TEC performs heating or cooling.

[0024] Furthermore, in the step 1), after the pump laser is powered on, the resistance value of its internal thermistor NTC is fed back to the resistance temperature detector RT in the temperature acquisition circuit to link the voltage value of the resistance temperature detector RT; in the step 2), the voltage value of the resistance temperature detector RT is input into the inverting input terminal of the first operational amplifier U1A in the differential amplifier circuit, and the set temperature value is input into the non-inverting input terminal of the first operational amplifier U1A.

[0025] Further, in the step 4), the PWM control signal includes a heating temperature control signal TEC_CTRL+ and a cooling temperature control signal TEC_CTRL-; in the step 5), when the heating temperature control signal TEC_CTRL+ is input to the TEC drive circuit, one of the passively triggered transistors is turned on and the other passively triggered transistor is turned off, and the TEC performs cooling; conversely, when the cooling temperature control signal TEC_CTRL- is input to the TEC drive circuit, the TEC performs heating.

[0026] The beneficial effects achieved by the present invention are:

[0027] Provided is a TEC control circuit and control method for temperature control of a pump laser. By setting a temperature acquisition circuit, a differential amplifier circuit, a PID control circuit, a TEC control signal generation circuit and a TEC drive circuit, it is possible to capture in time when the ambient temperature or the temperature of the pump laser changes, and to adjust quickly, accurately and reliably, so that the pump laser can work at the set temperature. Based on this, while ensuring the optical performance, the service life of the device can also be extended, which is conducive to ensuring the stable and reliable operation of the entire optical amplifier. Compared with the existing TEC control method, the present invention not only has lower cost, but also has the advantages of higher accuracy and more stable and reliable operation. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 is a structural block diagram of the TEC control circuit according to an embodiment of the present invention;

[0029] Figure 2 is an overall circuit structure diagram of the TEC control circuit according to an embodiment of the present invention;

[0030] Figure 3 is a circuit structure diagram of a differential amplifier circuit in a TEC control circuit according to an embodiment of the present invention;

[0031] Figure 4 is a circuit structure diagram of a PID control circuit in a TEC control circuit according to an embodiment of the present invention;

[0032] Figure 5 is a circuit structure diagram of a TEC control signal generating circuit in the TEC control circuit according to an embodiment of the present invention;

[0033] Figure 6 4 is a circuit structure diagram of a TEC driving circuit in a TEC control circuit according to an embodiment of the present invention. DETAILED DESCRIPTION

[0034] To clearly illustrate the solution in the present invention, further description is given below in conjunction with the accompanying drawings:

[0035] Example 1

[0036] In a first aspect, the present embodiment provides a TEC control circuit for temperature control of a pump laser. Figure 1 As shown, it includes a temperature acquisition circuit, a differential amplifier circuit, a PID control circuit, a TEC control signal generating circuit and a TEC driving circuit. The temperature acquisition circuit, the differential amplifier circuit, the PID control circuit, the TEC control signal generating circuit and the TEC driving circuit are electrically connected in sequence, and the temperature acquisition circuit and the TEC driving circuit are also electrically connected to the pump laser respectively.

[0037] In the above structure, the temperature acquisition circuit and the TEC drive circuit are also electrically connected to the pump laser respectively; the temperature acquisition circuit is used to collect the temperature value of the pump laser; the differential amplifier circuit is used to obtain the difference between the temperature value and the set temperature value and perform differential amplification; the PID control circuit is used to perform proportional integral differential operations on the difference; the TEC control signal generation circuit is used to automatically generate a PWM control signal for controlling TEC heating or cooling; and the TEC drive circuit is used to drive the TEC accordingly according to the PWM control signal.

[0038] Please refer to Figures 2 to 6 , specifically:

[0039] The temperature acquisition circuit includes a resistance temperature detector RT. One end of the resistance temperature detector RT is connected to one end of the thermistor NTC inside the pump laser, the other end of the resistance temperature detector RT is connected to the differential amplifier circuit, and the other end of the thermistor NTC is grounded.

[0040] The differential amplifier circuit includes a bridge circuit, two input resistors, a bias resistor R12, a first operational amplifier U1A and a feedback resistor R13. The bridge circuit includes a first resistor R1, a second resistor R2, a third resistor R3 and a fourth resistor R4, wherein the first resistor R1 and the third resistor R3 are connected in series, the second resistor R2 and the fourth resistor R4 are connected in series, and the thermistor NTC is connected in parallel with the third resistor R3; the two input resistors are respectively a first input resistor R19 and a second input resistor R20; the bridge circuit is connected to the non-inverting input terminal of the first operational amplifier U1A through the first input resistor R19, the resistance temperature detector RT is connected to the inverting input terminal of the first operational amplifier U1A through the second input resistor R20, and the output terminal of the first operational amplifier U1A is connected to the PID control circuit.

[0041] In the above structure, the ratio of the second resistor R2 to the fourth resistor R4 determines the set temperature value T0 for the pump laser. When the temperature of the pump laser changes, the resistance of the thermistor NTC will change, and the voltage value at the resistance temperature detector RT will also change. This voltage value will be connected to the first operational amplifier U1A through the second input resistor R20; at this time, the voltage difference between the two input terminals of the first operational amplifier U1A is ≠0, and this voltage difference is used as the output of the differential amplifier circuit after differential amplification.

[0042] The PID control circuit includes a common-phase input resistor R14 and a proportional-integral-differential controller, and the output end of the proportional-integral-differential controller is connected to the TEC control signal generating circuit. The proportional-integral-differential controller includes a second operational amplifier U1B, two resistors and three capacitors; the two resistors are the fifth resistor R5 and the sixth resistor R6, and the three capacitors are the first capacitor C1, the second capacitor C2 and the third capacitor C3.

[0043] In the above structure, by adjusting the values ​​of two resistors and three capacitors, the PID parameters can be flexibly set so that the PID control circuit works according to actual needs.

[0044] The TEC control signal generating circuit includes a third operational amplifier U1C, a fourth operational amplifier U1D and two resistors. The two resistors are an eighth resistor R8 and a ninth resistor R9, one end of the eighth resistor R8 is connected to the non-inverting input terminal of the third operational amplifier U1C and the other end is grounded, one end of the ninth resistor R9 is connected to the non-inverting input terminal of the fourth operational amplifier U1D and the other end is grounded; the output end of the PID control circuit is connected to the inverting input terminal of the third operational amplifier U1C through a current limiting resistor R21.

[0045] In the above structure, the third operational amplifier U1C and the fourth operational amplifier U1D are used as comparators, and the eighth resistor R8 and the ninth resistor R9 both play a role in anti-interference. The TEC control signal generation circuit generates a PWM waveform. Specifically: the output voltage ΔV output by the PID control circuit is compared with the reference voltage REF_VCC-U1D of the third operational amplifier U1C. If ΔV > REF_VCC-U1D, the TEC_CTRL+ output by the third operational amplifier U1C is at a low level; after the output voltage ΔV is compared with the reference voltage REF_VCC-U1B of the fourth operational amplifier U1D, the TEC_CTRL- output by the fourth operational amplifier U1D is at a high level. Similarly, if ΔV < REF_VCC-U1D, TEC_CTRL+ is at a high level and TEC_CTRL- is at a low level. According to the circuit design, TEC_CTRL+ and TEC_CTRL- must be mutually exclusive, that is, when one is at a high level, the other must be at a low level; under the combined action of the two, a PWM control signal is formed to control the direction of the TEC current.

[0046] The TEC drive circuit uses an H-bridge circuit. The H-bridge circuit includes four triodes, four base bias resistors, four diodes and two resistors; the four base bias resistors are respectively connected to the bases of the four triodes. The four triodes include two passive trigger triodes and two linked trigger triodes. Two diodes are connected between the two passive trigger triodes and the two linked trigger triodes. The two diodes are the first diode D1, the second diode D2, the third diode D3 and the fourth diode D4 respectively; the two passive trigger triodes are the first passive trigger triode Q3 and the second passive trigger triode Q4 respectively, and the two linked trigger triodes are the first linked trigger triode Q1 and the second linked trigger triode Q2 respectively; the four base bias resistors are the first base bias resistor R15 corresponding to the first linked trigger triode Q1, the second base bias resistor R16 corresponding to the second linked trigger triode Q2, the third base bias resistor R17 corresponding to the first passive trigger triode Q3 and the fourth base bias resistor R18 corresponding to the second passive trigger triode Q4 respectively; the two resistors include the tenth resistor R10 and the eleventh resistor R11; the input signal of the base of the first passive trigger triode Q3 is the heating temperature control signal TEC_CTRL+ in the PWM control signal, and the input signal of the base of the second passive trigger triode Q4 is the cooling temperature control signal TEC_CTRL- in the PWM control signal. Among them:

[0047] The first base bias resistor R15 and the second base bias resistor R16 are connected to the bases of the first linkage trigger transistor Q1 and the second linkage trigger transistor Q2 respectively. The collectors of the first linkage trigger transistor Q1 and the second linkage trigger transistor Q2 are simultaneously connected to the power supply VCC terminal. The emitters of the first linkage trigger transistor Q1 and the second linkage trigger transistor Q2 are connected to the TEC-terminal and TEC+terminal of the TEC respectively. The anode of the first diode D1 is connected to the emitter of the first linkage trigger transistor Q1 and the TEC-terminal of the TEC, and the cathode is connected to the base of the first linkage trigger transistor Q1 and the collector of the first passive trigger transistor Q3; the anode of the second diode D2 is connected to the emitter of the second linkage trigger transistor Q2 and the TEC+terminal of the TEC, and the cathode is connected to the base of the second linkage trigger transistor Q2 and the collector of the second passive trigger transistor Q4. After the third diode D3 and the tenth resistor R10 are connected in series, one end is connected to the input signal TEC_CTRL+, and the other end is connected to the base of the first passive trigger transistor Q3; after the fourth diode D4 and the eleventh resistor R11 are connected in series, one end is connected to the input signal TEC_CTRL-, and the other end is connected to the base of the second passive trigger transistor Q4. The emitters of the first passive trigger transistor Q3 and the second passive trigger transistor Q4 are connected and then connected to the AGND terminal through the seventh resistor R7.

[0048] In the above structure, the first base bias resistor R15 and the second base bias resistor R16 are used to control the opening of the first linkage trigger transistor Q1 and the second linkage trigger transistor Q2 respectively; the third base bias resistor R17 and the fourth base bias resistor R18 are used to make the first passive trigger transistor Q3 and the second passive trigger transistor Q4 work in the amplification area. According to the formula IC=βIB, by controlling the IC size of the first passive trigger transistor Q3 and the second passive trigger transistor Q4, the current size of the TEC can be controlled. The two diodes are Schottky diodes, which play a role of reverse cutoff. By using their unidirectional conduction and clamping effects, the first linkage trigger transistor Q1 and the second linkage trigger transistor Q2 can be ensured to be reliably turned on.

[0049] A second aspect of the present embodiment provides a TEC control method for temperature control of a pump laser, which uses the above-mentioned TEC control circuit for temperature control of a pump laser, and includes the following steps:

[0050] Step 1), after the pump laser is powered on, the temperature acquisition circuit acquires the temperature value of the pump laser in real time, and outputs the acquired temperature value to the differential amplifier circuit in the form of a voltage signal;

[0051] Step 2), the differential amplifier circuit performs differential amplification on the collected temperature value based on the set temperature value and outputs the result to the PID control circuit;

[0052] Step 3), the PID control circuit performs proportional integral differential operation, and outputs the calculated value to the TEC control signal generating circuit;

[0053] Step 4), the TEC control signal generating circuit automatically generates a PWM control signal for controlling TEC heating or cooling based on the calculated value, and outputs the PWM control signal to the TEC driving circuit;

[0054] Step 5), the TEC driving circuit is used to drive the TEC according to the PWM control signal, so that the TEC performs heating or cooling.

[0055] Specifically:

[0056] In step 1), after the pump laser is powered on, the resistance value (representing the temperature value) of its internal thermistor NTC is fed back to the resistance temperature detector RT in the temperature acquisition circuit to link the voltage value of the resistance temperature detector RT;

[0057] In step 2), the voltage value of the resistance temperature detector RT is input to the inverting input terminal of the first operational amplifier U1A in the differential amplifier circuit, and the set temperature value is input to the non-inverting input terminal of the first operational amplifier U1A. The first operational amplifier U1A outputs a value after differential amplification. Assuming that the value is error, the error is output to the PID control circuit;

[0058] In step 3), after the PID control circuit performs proportional-integral-differential operation on the error, its output value is used as the generation signal of the PWM control signal in the TEC control signal generating circuit;

[0059] In step 4), the PWM control signal includes a heating temperature control signal TEC_CTRL+ and a cooling temperature control signal TEC_CTRL-, and the heating temperature control signal TEC_CTRL+ and the cooling temperature control signal TEC_CTRL- are opposite high and low levels;

[0060] In step 5), when the input to the TEC drive circuit is the heating temperature control signal TEC_CTRL+, the first passive trigger triode Q3 conducts, and the second passive trigger triode Q4 cuts off. After the first passive trigger triode Q3 conducts, the base voltage of the first linked trigger triode Q1 decreases, so the first linked trigger triode Q1 changes to the cut-off state, while the second linked trigger triode Q2 is in the conducting state. At this time, the current flow is from the VCC terminal → the second linked trigger triode Q2 → TEC_+ → TEC_- → the first diode D1 → the first passive trigger triode Q3 → the seventh resistor R7 → the AGND terminal. Since the current on TEC_+ > the current on TEC_-, TEC performs refrigeration to cool the pump laser. Conversely, when the input to the TEC drive circuit is the refrigeration temperature control signal TEC_CTRL-, the second passive trigger triode Q4 conducts, and the first passive trigger triode Q3 cuts off. After the second passive trigger triode Q4 conducts, the base voltage of the second linked trigger triode Q2 decreases, so the second linked trigger triode Q2 changes to the cut-off state, while the first linked trigger triode Q1 is in the conducting state. At this time, the current flow is from the VCC terminal → the first linked trigger triode Q1 → TEC_- → TEC_+ → the second diode D2 → the second passive trigger triode Q4 → the seventh resistor R7 → the AGND terminal. Since the current on TEC_+ < the current on TEC_-, TEC performs heating to warm the pump laser.

[0061] In addition, by adjusting the resistance values of the third base bias resistor R17 and the fourth base bias resistor R18, as well as the models or parameters of the first linked trigger triode Q1, the second linked trigger triode Q2, the first passive trigger triode Q3, and the second passive trigger triode Q4, the TEC current value can be increased or decreased according to actual needs, thereby making the control circuit more flexible.

[0062] It should be particularly noted that the parts not described in detail or expanded in the above solution are all prior arts, not the improvements made by the present invention to the prior art, nor within the protection scope of the technical solution of the present invention. Therefore, they will not be elaborated herein.

[0063] Of course, the above content is only a preferred embodiment of the present invention and cannot be considered as limiting the scope of the embodiments of the present invention. The present invention is not limited to the above examples either. Equivalent changes and improvements made by those of ordinary skill in the art within the essence of the present invention shall fall within the scope covered by the patent of the present invention.

Claims

1. A TEC control circuit for temperature control of a pump laser, characterized in that: The invention comprises a temperature acquisition circuit, a differential amplifier circuit, a PID control circuit, a TEC control signal generating circuit and a TEC driving circuit, wherein the temperature acquisition circuit, the differential amplifier circuit, the PID control circuit, the TEC control signal generating circuit and the TEC driving circuit are electrically connected in sequence, and the temperature acquisition circuit and the TEC driving circuit are also electrically connected to the pump laser respectively; the temperature acquisition circuit is used to acquire the temperature value of the pump laser; the differential amplifier circuit is used to obtain the difference between the temperature value and the set temperature value and perform differential amplification; the PID control circuit is used to perform proportional integral differential operation on the difference; the TEC control signal generating circuit is used to automatically generate a PWM control signal for controlling TEC heating or cooling; and the TEC driving circuit is used to drive the TEC accordingly according to the PWM control signal.

2. The TEC control circuit for temperature control of a pump laser according to claim 1, characterized in that: The TEC driving circuit adopts an H-bridge circuit, which includes four transistors, four base bias resistors and four diodes; the four base bias resistors are respectively connected to the bases of the four transistors, the four transistors include two passive trigger transistors and two linkage trigger transistors, and the two diodes are connected between the two passive trigger transistors and the two linkage trigger transistors.

3. The TEC control circuit for temperature control of a pump laser according to claim 2, characterized in that: The input signal of the base of one of the passively triggered transistors is the heating temperature control signal TEC_CTRL+ in the PWM control signal, and the input signal of the base of the other passively triggered transistor is the cooling temperature control signal TEC_CTRL- in the PWM control signal.

4. The TEC control circuit for temperature control of a pump laser according to claim 1, characterized in that: The temperature acquisition circuit comprises a resistance temperature detector RT, one end of the resistance temperature detector RT is connected to one end of the thermistor NTC inside the pump laser, and the other end of the resistance temperature detector RT is connected to a differential amplifier circuit.

5. The TEC control circuit for temperature control of a pump laser according to claim 4, characterized in that: The differential amplifier circuit includes a bridge circuit, two input resistors, a bias resistor R12, a first operational amplifier U1A and a feedback resistor R13; the bridge circuit is connected to the non-inverting input terminal of the first operational amplifier U1A through one of the input resistors, the resistance temperature detector RT is connected to the inverting input terminal of the first operational amplifier U1A through the other input resistor, and the output terminal of the first operational amplifier U1A is connected to the PID control circuit.

6. The TEC control circuit for temperature control of a pump laser according to claim 5, characterized in that: The PID control circuit includes a common-phase input resistor R14 and a proportional-integral-differential controller. The proportional-integral-differential controller includes a second operational amplifier U1B, two resistors and three capacitors. The output end of the proportional-integral-differential controller is connected to a TEC control signal generating circuit.

7. The TEC control circuit for temperature control of a pump laser according to claim 6, characterized in that: The TEC control signal generating circuit includes a third operational amplifier U1C and a fourth operational amplifier U1D.

8. A TEC control method for temperature control of a pump laser, using the TEC control circuit for temperature control of a pump laser according to any one of claims 1 to 7, characterized in that: The steps include: Step 1), after the pump laser is powered on, the temperature acquisition circuit acquires the temperature value of the pump laser in real time, and outputs the acquired temperature value to the differential amplifier circuit in the form of a voltage signal; Step 2), the differential amplifier circuit performs differential amplification on the collected temperature value based on the set temperature value and outputs the result to the PID control circuit; Step 3), the PID control circuit performs proportional integral differential operation, and outputs the calculated value to the TEC control signal generating circuit; Step 4), the TEC control signal generating circuit automatically generates a PWM control signal for controlling TEC heating or cooling based on the calculated value, and outputs the PWM control signal to the TEC driving circuit; Step 5), the TEC driving circuit is used to drive the TEC according to the PWM control signal, so that the TEC performs heating or cooling.

9. The TEC control method for temperature control of a pump laser according to claim 8, characterized in that: In the step 1), after the pump laser is powered on, the resistance value of its internal thermistor NTC is fed back to the resistance temperature detector RT in the temperature acquisition circuit to link the voltage value of the resistance temperature detector RT; in the step 2), the voltage value of the resistance temperature detector RT is input into the inverting input terminal of the first operational amplifier U1A in the differential amplifier circuit, and the set temperature value is input into the non-inverting input terminal of the first operational amplifier U1A.

10. The TEC control method for temperature control of a pump laser according to claim 8, characterized in that: In the step 4), the PWM control signal includes a heating temperature control signal TEC_CTRL+ and a cooling temperature control signal TEC_CTRL-; in the step 5), when the heating temperature control signal TEC_CTRL+ is input to the TEC driving circuit, one of the passively triggered transistors is turned on and the other passively triggered transistor is turned off, and the TEC performs cooling; conversely, when the cooling temperature control signal TEC_CTRL- is input to the TEC driving circuit, the TEC performs heating.

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