Thermal Application Guide

Vortex Thermal Specification, Performance, and Additional Resources

If you have more questions regarding thermal management, check out our Thermal Management Guide. If you have any other specific questions regarding your application, reach out to us and we would be happy to help.

For the most up-to-date Vortex thermal specifications and performance, please see the Products page at our website. https://www.salientmotion.com/products

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Temperature Rise vs. Continuous Power, Packaging Thermal Resistance

Given your application's required continuous power output, Vortex's board temperature rise above ambient can be determined for different values of your packaging/mounting solution's thermal resistance. Thermal resistance (Rja) is a unit of measurement used commonly to describe the performance of heat sinks and other thermal management solutions. It is the measurement of the temperature rise above ambient over the total power dissipated by the device.

In Figure 1, Trise represents the steady state ESC temperature achieved above the operating ambient temperature. For example, in a 40°C ambient environment, at a continuous output power of 250W, with a free convection junction-ambient thermal resistance of 10 °C/W, the steady state ESC temperature will be approximately 76°C).

Figure 1: Continuous Power Output Vs. Thermal Resistance. Results were obtained at 12VDC sweeping output current from 0-30A continuous. Trise represents the steady state ESC temperature achieved above the operating ambient temperature. (Ex. In a 40°C ambient environment, at a continuous output power of 250W, with a free convection packaging thermal resistance of 10 °C/W, the steady state ESC temperature will be approximately 76°C).

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Maximum Operating Ambient Temperature vs. Allowable Continuous Current

Similar to Figure 1, we can represent the same performance characteristics from a different perspective: Given a known worst-case ambient operating temperature, what is the expected continuous output current achievable, and what is the expected rate of current pullback given the heat rejection? This assumes that the temperature throttle setpoint is at its default value of 100C. For a thermal resistance solution of 10 C/W (example: small finned heat sink in still air) and an ambient operating temperature of 40C, the controller will be able to operate at a continuous current of ~23A.

Figure 2: Current Derating Vs. Ambient Operating Temperature. Results shown were obtained with a 12VDC supply. For higher voltages, expect somewhere between a 5-10% current reduction for ambient temperatures > 40°C. Profiles shown represent the expected continuous output current for various packaging thermal resistance values that achieve a steady state ESC temperature of <= 100°C. For example, a packaging solution containing a finned heat sink + small computer fan (e.g. <= 2 °C/W) would achieve the continuous output current of 30A for local ambient temperature <= 80°C. Similarly, a packaging solution containing a small low watt heat sink in stagnant air (e.g. >= 10 °C/W) would achieve a derated output current of 20A for a local ambient temperature of 50°C

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High Power Burst: Burst Time vs. Temperature

For events where high bursts of power are needed (such as when performing an aggressive maneuver) the amount of time that event can last will be dependent on two main factors: the thermal resistance of your thermal solution, as well as the thermal mass of the thermal system (typically PCB + enclosure + heat sink). The thermal mass of the system allows for longer burst event times, however keep in mind that this also means similarly longer temperature recovery times between events. If burst events are more frequent, consider a thermal solution with low thermal resistances, and lower capacitances (i.e. reduce your heat sink size and add a fan instead).

Figure 3: Allowable Burst Time vs. Temperature. Results above are from a transient thermal model derived from burst thermal testing for an unsunk, Vortex board vs. a heat sunk Vortex board, both in still air. Vortex’s temperature throttling setpoint was set to 90°C. For the unsunk Vortex and an ambient temperature of 40°C, an overpower burst event of 50A will last 14s until current derating will occur. For a heat sunk Vortex with ~7°C/W thermal resistance and a thermal capacitance of 30 J/°C, a 50A overpower event will last 33s.

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Thermal Application Support

Vortex Thermal Interface Design

For questions regarding selecting the right thermal interface materials, or enclosure and mounting plate interface design, Reach out to us and we will be sure to get you running cool.

In electronics with higher heat dissipations, it is necessary to create strong conduction paths out of critical components. This is commonly done with either thermal gap filler pads, or thermal pastes. Thermal interface materials range in many different hardnesses, viscosities, and thermal conductivities.