CN214409737U

CN214409737U - Temperature control circuit of unbalanced H-bridge laser

Info

Publication number: CN214409737U
Application number: CN202122050989.5U
Authority: CN
Inventors: 朱佑强; 韩军; 赵保来; 孟卓
Original assignee: Tianjin Boke Optoelectronics Technology Co ltd
Current assignee: Tianjin Boke Optoelectronics Technology Co ltd
Priority date: 2021-08-30
Filing date: 2021-08-30
Publication date: 2021-10-15
Anticipated expiration: 2031-08-30

Abstract

The embodiment of the utility model discloses nonequilibrium H bridge laser ware temperature control circuit belongs to control by temperature change technical field, including power supply circuit, temperature detect circuit, asymmetric H bridge circuit, drive circuit and TEC semiconductor refrigeration piece, power supply circuit is temperature detect circuit, asymmetric H bridge circuit and drive circuit power supply, temperature detect circuit and asymmetric H bridge circuit connection, drive circuit and asymmetric H bridge circuit connection, TEC semiconductor refrigeration piece setting inside asymmetric H bridge circuit. The power supply system uses a single power supply to supply power, and solves the problem of power supply redundancy and complexity of dual power supplies; the driving point of the circuit is not at V/2 by adopting a bidirectional asymmetric structure, wherein two switching tubes only bear the switching action and do not consume energy; the application adopts a pure analog circuit to work, so that the influence on the stability of the system is avoided; the circuit system also adopts low-cost devices and basic resistance-capacitance networks, so that the circuit system is low in cost and simple in structure.

Description

Temperature control circuit of unbalanced H-bridge laser

Technical Field

The embodiment of the utility model provides a relate to control by temperature change technical field, concretely relates to nonequilibrium H bridge laser instrument temperature control circuit.

Background

At present, a laser temperature control system based on NTC (negative temperature coefficient thermistor) + TEC (thermoelectric cooling plate) is mainly composed of a PID (proportional-derivative-integral) control unit and a power driving unit. PID proportion calculus control is a core control unit in the control field, is distinguished by digital PID and analog PID, and aims to realize temperature locking quickly and stably. The power driving part has a plurality of methods, namely bipolar triode geminate transistors, complementary high-power operational amplifier and PWM switching power supply technology. Each technique has advantages and disadvantages. The H-bridge circuit is widely applied because the power supply system and the circuit are simplified due to the single power supply.

The current H-bridge circuit is mainly used for controlling the direction of a direct current motor, and a typical application circuit thereof is used for reference. The H bridge circuit has various realization modes, the working point of the balanced H bridge is at the midpoint of the power supply, and when the direction is controlled, the control unit of the opposite angle is started to enable the balanced H bridge to work in one direction. In which the PWM-based H-bridge technology is ultimately and widely applied to integrated temperature control chips such as MAX1978 series and ADN8830 series. Because the H-bridge temperature control system based on PWM belongs to a DC-DC power supply control system, the structure is simple, the energy-saving heating small body is small, the integration level is high, and the H-bridge temperature control system is favored. But its application is limited due to its PWM switching noise, which can cause the laser output to be disturbed if the noise problem is not handled well. And the driving mode of the integrated chip can not be modified, and the cost is higher.

Therefore, how to provide a novel temperature control circuit with few devices, simple structure and low cost, which is free from switching noise and low frequency noise, is a technical problem to be solved urgently by those skilled in the art.

SUMMERY OF THE UTILITY MODEL

Therefore, the embodiment of the utility model provides an unbalanced H bridge laser temperature control circuit to because integrated chip is expensive among the solution prior art, and there is switching noise and the cost height that leads to and the restricted problem of application.

In order to achieve the above object, the embodiment of the present invention provides the following technical solutions:

the utility model provides a temperature control circuit of unbalanced H bridge laser, includes power supply circuit, temperature detect circuit, asymmetric H bridge circuit, drive circuit and TEC semiconductor refrigeration piece, power supply circuit does temperature detect circuit, asymmetric H bridge circuit and drive circuit power supply, temperature detect circuit with asymmetric H bridge circuit connects, drive circuit with asymmetric H bridge circuit connects, TEC semiconductor refrigeration piece sets up inside the asymmetric H bridge circuit.

Further, the asymmetric H-bridge circuit comprises power tubes Q400, Q401, Q402 and Q403 and divider resistors R405, R406, R407 and R408, and gates of the power tubes Q400 and Q403 are connected to an output terminal of the operational amplifier IC 400B.

Further, the driving circuit comprises a direction control tube Q404, a pull-up resistor R409 and a current limiting resistor R419, wherein the drain electrode of the direction control tube Q404 is connected with the grid electrodes of the power tubes Q401 and Q402, the current limiting resistor R419 is arranged between the grid electrode of the power tube Q402 and the drain electrode of the direction control tube Q404, the pull-up resistor R409 is arranged at a power supply, and the grid electrode of the direction control tube Q404 is connected with the output end of the operational amplifier IC 400B.

Further, the temperature detection circuit comprises an operational amplifier IC400B and an RC circuit, wherein the RC circuit comprises voltage dividing resistors R400, R401, R402 and R403, a thermistor R404 and capacitors C400, C401, C402, C403 and C404, the thermistor R404 is connected with the voltage dividing resistor R403 in series, and the thermistor R404 is connected with the inverting input end of the operational amplifier IC 400B.

Further, the TEC semiconductor refrigeration piece is provided with a cold end and a hot end.

Further, the hot end of the TEC semiconductor chilling plate is connected to the source of the power tube Q400 and the drain of the power tube Q401.

Further, the cold end of the TEC semiconductor chilling plate is connected to the source of the power tube Q402 and the drain of the power tube Q403.

Further, four power transistors Q400, Q401, Q402, and Q403 are high-turn-on voltage mosfet NDT451N, and the MOS fet NDT451N is packaged by SOT-223.

Further, the direction control transistor Q404 is a MOS field effect transistor BSS138 with a low turn-on voltage.

Further, the thermistor R404 is a negative temperature coefficient thermistor.

The embodiment of the utility model provides a have following advantage:

aiming at power supply redundancy and complexity of dual power supplies, single power supply can be realized by using single power supply; the bidirectional asymmetric structure is adopted, and different current limiting is carried out in the forward direction and the reverse direction. Because the circuit is a simplified H-bridge circuit, the driving point of the circuit is not at V/2, two switching tubes only bear the switching action and do not consume energy, only two switching tubes in four switching tubes consume energy, and the circuit structure is simple; the application adopts a pure analog circuit to work, and the circuit basically has no noise interference and can not generate crosstalk to surrounding circuits as long as a power supply and grounding are processed, so that the stability of the system is prevented from being influenced; the present application also employs low cost devices and a basic RC network, where four low voltage turned on N-channel FETs have a large choice. The circuit system has low cost and simple structure.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below. It should be apparent that the drawings in the following description are merely exemplary, and that other embodiments can be derived from the drawings provided by those of ordinary skill in the art without inventive effort.

The structure, ratio, size and the like shown in the present specification are only used for matching with the content disclosed in the specification, so as to be known and read by people familiar with the technology, and are not used for limiting the limit conditions which can be implemented by the present invention, so that the present invention has no technical essential significance, and any structure modification, ratio relationship change or size adjustment should still fall within the scope which can be covered by the technical content disclosed by the present invention without affecting the efficacy and the achievable purpose of the present invention.

Fig. 1 is a block diagram of an embodiment of the present invention;

fig. 2 is a circuit diagram of an embodiment of the present invention.

Detailed Description

The present invention is described in terms of specific embodiments, and other advantages and benefits of the present invention will become apparent to those skilled in the art from the following disclosure. Based on the embodiments in the present invention, all other embodiments obtained by a person skilled in the art without creative work belong to the protection scope of the present invention.

In order to solve the related technical problems in the prior art, the embodiment of the application provides a temperature control circuit of an unbalanced H-bridge laser, which aims to solve the problems of high cost, limited application and the like, and achieve the effects of low cost and no switching noise and low-frequency noise interference. As shown in fig. 1, the temperature detection circuit specifically includes a power circuit, a temperature detection circuit, an asymmetric H-bridge circuit, a driving circuit, and a TEC semiconductor refrigeration chip, where the power circuit supplies power to the temperature detection circuit, the asymmetric H-bridge circuit, and the driving circuit, the temperature detection circuit is connected to the asymmetric H-bridge circuit, the driving circuit is connected to the asymmetric H-bridge circuit, and the TEC semiconductor refrigeration chip is disposed inside the asymmetric H-bridge circuit.

The temperature control circuit with double power supplies needs to work by using positive and negative power supplies, which requires a power supply system to provide two sets of power supplies. The power supply circuit adopts a single power supply circuit, and the power supply pins of the temperature detection circuit, the asymmetric H-bridge circuit and the drive circuit can realize the power supply effect only by connecting the positive electrode of the power supply and the ground, so that a power supply system and the circuit are simplified, and the power supply redundancy and the complexity of dual power supplies are avoided.

Specifically, in this embodiment, as shown in fig. 2, the temperature detection circuit includes an operational amplifier IC400B and an RC circuit, the RC circuit includes voltage dividing resistors R400, R401, R402, and R403, a thermistor R404 and capacitors C400, C401, C402, C403, and C404, the thermistor R404 is connected in series with the voltage dividing resistor R403, and the thermistor R404 is connected to the inverting input terminal of the operational amplifier IC 400B. The RC circuit is a basic RC circuit of the temperature detection circuit, and is not described herein.

The thermistor R404 is a negative temperature coefficient thermistor. A ntc thermistor is a type of sensor resistor whose resistance decreases with increasing temperature. That is, the resistance of the thermistor R404 decreases as the temperature increases, and the resistance of the thermistor R404 increases as the temperature decreases. When the temperature decreases, the resistance value of the thermistor R404 increases, the thermistor R404 starts to divide the voltage, at this time, the voltage of the inverting input terminal of the operational amplifier IC400B increases, and the voltage of the output terminal of the operational amplifier IC400B starts to decrease; when the temperature increases, the resistance of the thermistor R404 decreases, the voltage drop across the thermistor R404 decreases, the voltage at the inverting input of the operational amplifier IC400B decreases, and the voltage at the output of the operational amplifier IC400B begins to increase.

As shown in fig. 2, additional control and detection circuitry is included. The power supply circuit also provides power to the additional control and detection circuitry. The additional control and detection circuit comprises an operational amplifier IC400A and voltage dividing resistors R413, R414 and R415, wherein the voltage dividing resistor R413 is connected with a power tube Q403 in the asymmetric H-bridge circuit, the forward input end of the operational amplifier IC400A is connected with the voltage dividing resistor R413, the reverse input end of the operational amplifier IC400A is connected with the voltage dividing resistor R414, the voltage dividing resistor R415 is arranged between the reverse input end and the output end of the operational amplifier IC400A, and the output end of the operational amplifier IC400A is connected with the MON end of the TEC semiconductor refrigeration piece. Wherein the operational amplifier IC400A and peripheral circuitry provide a 20-fold gain in the temperature controlled current sensing circuit for additional control and monitoring purposes. For example, if the temperature control current 2A × 0.1R =0.2V, the output Vo =0.2V × 20(G =20) =4V, and is suitable for use in an ADC having a reference voltage of 4.096V. The four power transistors Q400, Q401, Q402 and Q403 are high-turn-on voltage MOS field effect transistors NDT451N, and the MOS field effect transistors NDT451N are packaged by SOT-223. The direction control transistor Q404 is a low turn-on voltage mosfet BSS 138. The power tubes Q400, Q401, Q402, Q403 and the direction control tube Q404 are all N-channel MOS field effect tubes, and when the grid voltage of the N-channel MOS field effect tubes is high level, the N-channel MOS field effect tubes are turned on. And the turn-on voltage of the power tubes Q400, Q401, Q402 and Q403 is greater than the turn-on voltage of the direction control tube Q404. In this embodiment, the output of the operational amplifier IC400B is always high.

Specifically, in this embodiment, as shown in fig. 2, the asymmetric H-bridge circuit includes four power transistors Q400, Q401, Q402, and Q403, voltage dividing resistors R405, R406, R407, and R408, and gates of the power transistors Q400 and Q403 are connected to an output terminal of the operational amplifier IC 400B. The gates of power transistors Q400 and Q403 control the switching of power transistors Q400 and Q403 by sensing the voltage at the output of operational amplifier IC 400B.

When the temperature rises, namely the voltage at the output end of the operational amplifier IC400B rises, the voltage at the output end of the operational amplifier IC400B rises to the starting voltage of the power tubes Q400 and Q403, the grid electrodes of the power tubes Q400 and Q403 sense the voltage output by the output end of the operational amplifier IC400B, the power tubes Q400 and Q403 are conducted, the current positively flows through the TEC semiconductor chilling plate, and the TEC semiconductor chilling plate plays a role in chilling; when the temperature decreases, that is, the voltage at the output terminal of the operational amplifier IC400B decreases, the voltage at the output terminal of the operational amplifier IC400B decreases to the turn-on voltage of the power transistors Q400 and Q403, the power transistors Q400 and Q403 are turned off, no current flows in the forward direction through the TEC semiconductor chilling plates, and the TEC semiconductor chilling plates do not refrigerate any more.

Specifically, in this embodiment, as shown in fig. 2, the driving circuit includes a direction control tube Q404, a pull-up resistor R409, and a current limiting resistor R419, the drain of the direction control tube Q404 is connected to the gates of the power tubes Q401 and Q402, the current limiting resistor R419 is disposed between the gate of the power tube Q402 and the drain of the direction control tube Q404, the pull-up resistor R409 is disposed at the power supply, and the gate of the direction control tube Q404 is connected to the output terminal of the operational amplifier IC 400B.

When the power-on and power-on are performed, the pull-up resistor R409 is in an open state, and a circuit between the gate of the power tube Q402 and the drain of the direction control tube Q404 is conducted. When the temperature is reduced, namely the voltage at the output end of the operational amplifier IC400B is reduced, the voltage at the output end of the operational amplifier IC400B is reduced to the starting voltage of the direction control tube Q404, the direction control tube Q404 is closed, because the circuit between the grid electrode of the power tube Q402 and the drain electrode of the direction control tube Q404 is conducted, the power tubes Q401 and Q402 are directly opened, and the current reversely flows through the TEC semiconductor chilling plate, so that the heating function is realized; when the temperature rises, namely the voltage at the output end of the operational amplifier IC400B rises, the voltage at the output end of the operational amplifier IC400B rises to the starting voltage of the direction control tube Q404, the direction control tube Q404 is opened, the grid electrode of the power tube Q402 is disconnected with the drain electrode of the direction control tube Q404, the power tubes Q401 and Q402 are closed, no current reversely flows through the TEC semiconductor chilling plates, and the TEC semiconductor chilling plates do not heat any more.

In addition, the asymmetrical H-bridge circuit and the driving circuit also comprise resistors R411, R412, R418, R420 and R410 which are all used for voltage division and current limitation and are generally applied to the circuit.

Specifically, in this embodiment, as shown in fig. 2, the TEC semiconductor chilling plates have a cold side and a hot side. And the hot end of the TEC semiconductor chilling plate is connected with the source electrode of the power tube Q400 and the drain electrode of the power tube Q401. And the cold end of the TEC semiconductor chilling plate is connected with the source electrode of the power tube Q402 and the drain electrode of the power tube Q403.

When the temperature rises, the voltage of the output end of the operational amplifier IC400B rises, the voltage of the output end rises to the starting voltage of the power tubes Q400 and Q403, namely the voltage is also greater than the starting voltage of the direction control tube Q404, when the direction control tube Q404 is opened, the grid of the power tube Q402 is disconnected with the drain of the direction control tube Q404, only the power tubes Q400 and Q403 are conducted at the moment, and the current flows from the hot end to the cold end of the TEC semiconductor chilling plate, so that the chilling effect is realized; when the temperature is reduced, the voltage of the output end of the operational amplifier IC400B is reduced, the voltage of the output end is reduced to the starting voltage of the direction control tube Q404, the power tubes Q400 and Q403 and the direction control tube Q404 are both closed, the grid electrode of the power tube Q402 is conducted with the drain electrode of the direction control tube Q404, the power tubes Q401 and Q402 are opened, and the current flows from the cold end to the hot end of the TEC semiconductor refrigeration piece, so that the heating effect is realized.

As shown in fig. 2, the control circuit part of this embodiment adopts a simplified analog PID control unit, which has a prototype and application in most laser temperature control circuits, and only uses the proportional integral part in the proportional micro-integral, so that the temperature control application of most lasers can be basically covered. The PID parameter adjustment is consistent with the conventional PID parameter adjustment steps, and the parameters are different because the gains of different temperature control circuits are different. The simplified PID parameter setting used here uses only a proportional-integral circuit, with the frequency point set to 0.4 Hz.

As shown in fig. 2, the power driving part adopts an asymmetric H-bridge circuit, wherein a current limiting resistor R419 is adopted between the gate of the heating direction power tube Q402 and the drain of the direction control tube Q404, so that the H-bridge is unbalanced, and the heat carrying power of the TEC semiconductor cooling plate is limited. When the TEC semiconductor refrigeration piece is in a heating state, the TEC semiconductor refrigeration piece is started by a pull-up resistor R409, and the start is automatically completed when the TEC semiconductor refrigeration piece is started and powered on. When the PID control unit starts to work, the working current is controlled to be in a balance position. When the refrigeration is started, the PID control unit outputs to enable the power tube Q404 to be started, the source electrode and the drain electrode of the power tube Q404 to be conducted, the grid electrode of the power tube Q402 and the drain electrode of the direction control tube Q404 are not conducted, the power tubes Q402 and Q401 which achieve the heating function are closed, and at the moment, along with the increase of the output of the PID control unit, the power tubes Q400 and Q403 are started to start the refrigeration function.

It can be seen from the principle that this power-driven fet does not operate at the middle equilibrium point, so the power consumption and heat generation carried by each pair of transistors are different when operating, and in addition, the cooling and heating switching point is not at the middle point, but near the turn-on voltage of the direction control transistor Q404, that is, near the threshold of the direction control transistor Q404, which requires the turn-on voltage of the direction control transistor Q404 to be appropriate and slightly lower than the turn-on voltage of the H-bridge power transistor.

Because the temperature control current of a common laser does not exceed 1.5A and the peak value does not exceed 3A under the full temperature, the continuous heat dissipation capacity of the field effect tube on a board is required to be not lower than 2W, and the temperature rise is not higher than 60 ℃.

In the specific implementation, two embodiments exist, one is heating, and the other is cooling.

Example 1:

when the temperature decreases, the resistance of the thermistor R404 increases, and the voltage at the inverting input terminal of the operational amplifier IC400B increases, so that the voltage at the output terminal of the operational amplifier IC400B decreases until the voltage decreases to the turn-on voltage of the steering tube Q404. At the moment, the power tubes Q401 and Q402 are opened, and current reversely flows through the TEC semiconductor refrigerating plate to realize the heating function. Until the temperature of the TEC semiconductor refrigeration piece is balanced at the set temperature.

Example 2:

when the temperature rises, the resistance value of the thermistor R404 is reduced, the voltage of the inverting input end of the operational amplifier IC400B is reduced, the voltage of the output end of the operational amplifier IC400B is increased until the operational amplifier output voltage is higher than the starting voltage of the direction control tube Q404, at the moment, the gap between the grid of the power tube Q402 and the drain of the direction control tube Q404 is closed, when the PID output voltage further rises, the power tubes Q400 and Q403 are opened, the current positively flows through the TEC semiconductor refrigeration piece, and the refrigeration function is realized. Until the temperature of the TEC semiconductor refrigeration piece is balanced with the set temperature, the TEC semiconductor refrigeration piece reaches a stable state.

The utility model discloses use as follows:

the thermistor R404 senses temperature, when the temperature rises, the voltage at the output end of the operational amplifier IC400B rises, the voltage at the output end rises to the turn-on voltage of the power tubes Q400 and Q403, that is, the turn-on voltage is also greater than the turn-on voltage of the direction control tube Q404, when the direction control tube Q404 is turned on, the gate of the power tube Q402 and the drain of the direction control tube Q404 are disconnected, only the power tubes Q400 and Q403 are turned on at this time, and current flows from the hot end to the cold end of the TEC semiconductor chilling plate, thereby achieving the chilling effect; when the temperature is reduced, the voltage at the output end of the operational amplifier IC400B is reduced, the voltage at the output end is reduced to the starting voltage of the direction control tube Q404, the power tubes Q400 and Q403 and the direction control tube Q404 are both closed, the gate of the power tube Q402 is conducted with the drain of the direction control tube Q404, and the current flows from the cold end to the hot end of the TEC semiconductor chilling plate, thereby achieving the heating effect.

Although the invention has been described in detail with respect to the general description and the specific embodiments, it will be apparent to those skilled in the art that modifications and improvements can be made based on the invention. Therefore, such modifications and improvements are intended to be within the scope of the invention as claimed.

Claims

1. The temperature control circuit is characterized by comprising a power circuit, a temperature detection circuit, an asymmetric H-bridge circuit, a driving circuit and a TEC semiconductor refrigerating piece, wherein the power circuit supplies power to the temperature detection circuit, the asymmetric H-bridge circuit and the driving circuit, the temperature detection circuit is connected with the asymmetric H-bridge circuit, the driving circuit is connected with the asymmetric H-bridge circuit, and the TEC semiconductor refrigerating piece is arranged inside the asymmetric H-bridge circuit.

2. The temperature control circuit of claim 1, wherein the asymmetric H-bridge circuit comprises power transistors Q400, Q401, Q402, Q403 and voltage dividing resistors R405, R406, R407, R408, and gates of the power transistors Q400 and Q403 are connected to an output of an operational amplifier IC 400B.

3. The temperature control circuit of claim 2, wherein the driving circuit comprises a direction control transistor Q404, a pull-up resistor R409 and a current limiting resistor R419, the drain of the direction control transistor Q404 is connected to the gates of the power transistors Q401 and Q402, the current limiting resistor R419 is arranged between the gate of the power transistor Q402 and the drain of the direction control transistor Q404, the pull-up resistor R409 is arranged at the power supply, and the gate of the direction control transistor Q404 is connected to the output terminal of the operational amplifier IC 400B.

4. The unbalanced H bridge laser temperature control circuit of claim 3, wherein the temperature detection circuit comprises an operational amplifier IC400B and an RC circuit comprising voltage dividing resistors R400, R401, R402, R403, a thermistor R404 and capacitors C400, C401, C402, C403, C404, the thermistor R404 being connected in series with the voltage dividing resistor R403, the thermistor R404 being connected with an inverting input of the operational amplifier IC 400B.

5. The unbalanced H-bridge laser temperature control circuit of claim 4, wherein the TEC semiconductor chilling plate has one cold side and one hot side.

6. The temperature control circuit of the unbalanced H-bridge laser of claim 5, wherein the hot end of the TEC semiconductor chilling plate is connected with the source of the power tube Q400 and the drain of the power tube Q401.

7. The unbalanced H-bridge laser temperature control circuit of claim 6, wherein the cold side of the TEC semiconductor chilling plate is connected with the source of the power tube Q402 and the drain of the power tube Q403.

8. The temperature control circuit of claim 7, wherein four of the power transistors Q400, Q401, Q402, Q403 are high turn-on voltage MOSFETs NDT451N, and the MOSFETs NDT451N are packaged with SOT-223.

9. The temperature control circuit of claim 8, wherein the direction control transistor Q404 is a low turn-on voltage MOS fet BSS 138.

10. The unbalanced H-bridge laser temperature control circuit of claim 9, wherein the thermistor R404 is a negative temperature coefficient thermistor.