Thermistor | PartQuest™ Explore

Laser Temperature Regulator using Peltier TEC

Designer19

Member for

11 years 6 months

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Member of the PartQuest Explore Development Team. Focused on modeling and simulation of analog, mixed-signal and multi-discipline systems covering a broad range of applications, including power electronics, controls and mechatronic systems.

Description

This example shows the ability of a Peltier Module, or Thermo-Electric Cooler (TEC), to actively transfer heat away from a "laser" or other electronic device, during fast-changing power dissipation conditions. A thermistor, with resistance that is sensitive to temperature, is used in a Wheatstone Bridge configuration. It produces a differential voltage that is amplified by an op-amp circuit. The op-amp output voltage is approximately proportional to temperature, and 180 degrees out of phase.

The rest of the control loop is modeled here using ideal mathematical control blocks. This abstraction allows the designer to focus on the overall performance of the regulator, and to assess the choice of PID gains during actual transient operation. These gains were selected using a nominal operating point, to ensure stability of the loop at that point. This was done in the companion design:

https://www.systemvision.com/design/laser-temperature-regulator-tdfs

But because many of the components in this loop are non-linear in nature (e.g. the TEC, thermistor, even the op-amp with rail voltage limiting), it is good practice to use simulation to verify performance during large-signal transients.

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Laser Temperature Regulator TDFS - on Mon, 12/23/2024 - 17:17

Designer260333

Member for

5 months 1 week

4

designs

2

groups

Welcome to the community!!

Laser Temperature Regulator using Peltier TEC - on Mon, 12/23/2024 - 17:09

Designer260333

Member for

5 months 1 week

4

designs

2

groups

Welcome to the community!!

Description

This example shows the ability of a Peltier Module, or Thermo-Electric Cooler (TEC), to actively transfer heat away from a "laser" or other electronic device, during fast-changing power dissipation conditions. A thermistor, with resistance that is sensitive to temperature, is used in a Wheatstone Bridge configuration. It produces a differential voltage that is amplified by an op-amp circuit. The op-amp output voltage is approximately proportional to temperature, and 180 degrees out of phase.

The rest of the control loop is modeled here using ideal mathematical control blocks. This abstraction allows the designer to focus on the overall performance of the regulator, and to assess the choice of PID gains during actual transient operation. These gains were selected using a nominal operating point, to ensure stability of the loop at that point. This was done in the companion design:

https://www.systemvision.com/design/laser-temperature-regulator-tdfs

But because many of the components in this loop are non-linear in nature (e.g. the TEC, thermistor, even the op-amp with rail voltage limiting), it is good practice to use simulation to verify performance during large-signal transients.

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Copy of LED Driver with Auto-Dimming for Thermal Protection - on Tue, 12/10/2024 - 10:13

Designer260185

Member for

5 months 2 weeks

2

designs

1

groups

Welcome to the community!!

Description

This LED lighting example demonstrates the value of simulating both the electrical and thermal* aspects of power dissipating circuits together, simultaneously.

In this application example, a Vishay NTCS0603 Thermistor provides feedback of the enclosure temperature. This feedback is used to control PWM dimming of the LEDs, thereby limiting the internal temperature when operating at high external ambient temperature conditions.

This is a "Live" design, the user can change key parameter values and then run new simulations to see the results. These parameters include "r_mirror", the resistance of the current mirror that controls the capacitor charging rate of the 555 timer, and thereby set the PWM frequency. The user can also change "r_offset" that controls the temperature level at which the dimming operation begins. Finally, the user can set "r_iLED_set", to control the ON-state operating current of the LEDs.

----------------

* To reduce the time needed to simulate the transition and settling at 6 different temperature levels, all thermal time constants were reduced by approximately 1000x. The actual thermal response time constant of the NTCS0603 is approximately 3 seconds (depends on mounting), not 3 msec! Also, the enclosure thermal capacitance value would more likely be 3 (J/degC) instead of 3 (mJ/degC), giving a thermal time constant for the enclosure of 10 (degC/Watt) * 3 (J/degC) = 30 seconds. This time scaling does not affect the static relationship between the outside temperature and PWM dimming.

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Copy of Analog LED Driver with Thermal Protection using FloTHERM Netlist - on Fri, 11/08/2024 - 14:38

Designer240663

Member for

3 years 11 months

22

designs

2

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Member of the PartQuest Explore team.

Description

This LED spotlight example demonstrates the value of simulating both the electrical and thermal aspects of power dissipating circuits together, simultaneously.

In this design, a Vishay NTCLE100 Thermistor is used in a detection circuit to monitor the enclosure temperature. It is used for thermal shut-down protection, to keep the enclosure temperature well below the "Tg" (glass transition temperature) of the spotlight's Nylon 6 polymer lens. This is particularly helpful when operating at higher external ambient temperatures.

The "Thermals" (thermal dynamics) model was automatically generated from a full 3D-CFD analysis of the spotlight board layout and enclosure, using FloTHERM. The model is in the IEEE Standard VHDL-AMS format, so it can be directly imported into the SystemVision "1D" circuit and system simulation context. The ability to include an accurate model of the thermal environment is key to having "thermally-aware" circuit function design and board layout processes.

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Copy of Laser Temperature Regulator TDFS - on Fri, 01/05/2024 - 07:42

Designer244467

Member for

2 years 7 months

325

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4

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Member of the PartQuest Explore development team.

Copy of Laser Temperature Regulator TDFS - on Fri, 01/05/2024 - 07:42

Designer244467

Member for

2 years 7 months

325

designs

4

groups

Member of the PartQuest Explore development team.

Copy of Laser Temperature Regulator using Peltier TEC - on Sat, 09/09/2023 - 20:53

Designer249287

Member for

1 year 8 months

2

designs

1

groups

Description

This example shows the ability of a Peltier Module, or Thermo-Electric Cooler (TEC), to actively transfer heat away from a "laser" or other electronic device, during fast-changing power dissipation conditions. A thermistor, with resistance that is sensitive to temperature, is used in a Wheatstone Bridge configuration. It produces a differential voltage that is amplified by an op-amp circuit. The op-amp output voltage is approximately proportional to temperature, and 180 degrees out of phase.

The rest of the control loop is modeled here using ideal mathematical control blocks. This abstraction allows the designer to focus on the overall performance of the regulator, and to assess the choice of PID gains during actual transient operation. These gains were selected using a nominal operating point, to ensure stability of the loop at that point. This was done in the companion design https://www.systemvision.com/design/laser-temperature-regulator-tdfs. But because many of the components in this loop are non-linear in nature (e.g. the TEC, thermistor, even the op-amp with rail voltage limiting), it is good practice to use simulation to verify performance during large-signal transients.

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tunable example 2

Designer198997

Member for

7 years

58

designs

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Add a bio to your profile to share information about yourself with other SystemVision users.

Description

This LED lighting example demonstrates the value of simulating both the electrical and thermal* aspects of power dissipating circuits together, simultaneously.

In this application example, a Vishay NTCS0603 Thermistor provides feedback of the enclosure temperature. This feedback is used to control PWM dimming of the LEDs, thereby limiting the internal temperature when operating at high external ambient temperature conditions.

This is a "Live" design, the user can change key parameter values and then run new simulations to see the results. These parameters include "r_mirror", the resistance of the current mirror that controls the capacitor charging rate of the 555 timer, and thereby set the PWM frequency. The user can also change "r_offset" that controls the temperature level at which the dimming operation begins. Finally, the user can set "r_iLED_set", to control the ON-state operating current of the LEDs.

----------------

* To reduce the time needed to simulate the transition and settling at 6 different temperature levels, all thermal time constants were reduced by approximately 1000x. The actual thermal response time constant of the NTCS0603 is approximately 3 seconds (depends on mounting), not 3 msec! Also, the enclosure thermal capacitance value would more likely be 3 (J/degC) instead of 3 (mJ/degC), giving a thermal time constant for the enclosure of 10 (degC/Watt) * 3 (J/degC) = 30 seconds. This time scaling does not affect the static relationship between the outside temperature and PWM dimming.

About text formats

TEST TUNABLE Analog LED Driver with Thermal Protection using FloTHERM Netlist

Designer21

Member for

11 years 6 months

104

designs

3

groups

Member of the PartQuest Explore team.

Description

This LED spotlight example demonstrates the value of simulating both the electrical and thermal aspects of power dissipating circuits together, simultaneously.

In this design, a Vishay NTCLE100 Thermistor is used in a detection circuit to monitor the enclosure temperature. It is used for thermal shut-down protection, to keep the enclosure temperature well below the "Tg" (glass transition temperature) of the spotlight's Nylon 6 polymer lens. This is particularly helpful when operating at higher external ambient temperatures.

The "Thermals" (thermal dynamics) model was automatically generated from a full 3D-CFD analysis of the spotlight board layout and enclosure, using FloTHERM. The model is in the IEEE Standard VHDL-AMS format, so it can be directly imported into the SystemVision "1D" circuit and system simulation context. The ability to include an accurate model of the thermal environment is key to having "thermally-aware" circuit function design and board layout processes.

About text formats

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