Alfred

Thermoelectric Cooling Through Electrical Conductors: Patent Background

Q: Does this concept apply only to batteries?

No. Batteries are one application. The broader concept applies to electrical devices in which a conductor can act as part of the heat-transfer path between an internal temperature-sensitive region and a thermoelectric module.

Electrical conductors are normally designed around current capacity, voltage drop, mechanical connection, and electrical reliability. In some applications, however, those same conductors can also become part of the thermal-management system.

This page reviews an earlier patent developed by Alfred Piggott, founder and CTO of Applied Thermoelectric Solutions, and other inventors while he was working at Gentherm. The patent explored using terminals, electrodes, leads, bus bars, and other current-carrying conductors as thermal pathways between temperature-sensitive regions of electrical devices and thermoelectric heating or cooling modules.

The central idea was to use a conductor for two functions:

Carry electrical current to or from the device
Transfer heat between the device and a thermoelectric module

This approach can provide a more direct thermal path to an internal hotspot or temperature-sensitive region that may be difficult to reach through the exterior housing.

Its success, however, depends on more than attaching a thermoelectric module to a wire or terminal. The electrical conductor, thermal path, thermoelectric device, interfaces, controls, packaging, and waste-side heat rejection must be designed and integrated as one complete system.

Patent Overview

Many electrical devices contain internal regions that generate heat or must remain within a specific temperature range.

Examples can include:

Power semiconductors
Transistors and IGBTs
Power amplifiers
Inverters and converters
Transformers
Motors and generators
High-power LEDs
Lasers
Batteries
Sensors
Other high-current electrical devices

The temperature-sensitive region may be buried inside the assembly, surrounded by electrical insulation, enclosed by a housing, or connected to the exterior mainly through electrical leads and terminals.

In those cases, the external housing may not provide the shortest or lowest-resistance thermal path to the region that requires temperature control.

The patented concept used an existing electrical conductor as part of the thermal pathway. A thermoelectric device could be coupled directly or indirectly to the conductor, allowing heat to move between the temperature-sensitive region and the thermoelectric module.

In cooling mode, the thermoelectric device pumps heat away from the electrical device. In heating mode, reversing current direction reverses the direction of heat pumping.

How an Electrical Conductor Can Also Transfer Heat

Most electrical conductors are made from materials with relatively high thermal conductivity, such as copper or aluminum.

That means a lead, terminal, electrode, bus bar, or other conductor can carry both:

Electrical current
Thermal energy

The amount of heat transferred through the conductor depends on:

Conductor material
Length
Cross-sectional area
Temperature difference
Thermal contact resistance
Geometry
Connection to surrounding structures
Heat generated within the conductor itself

A short, thick conductor generally has lower electrical resistance and lower thermal resistance than a long, thin conductor made from the same material.

This creates an important design opportunity. A conductor sized to carry substantial current may already provide a relatively conductive thermal path to an internal device region.

If a thermoelectric module is coupled to that conductor at the right location, the conductor can transfer heat between the module and the region requiring temperature control.

Why Conductor-Based Cooling Can Improve the Thermal Path

Heat generated inside an electrical device flows through all available thermal paths.

Some of those paths may pass through:

Semiconductor packaging
Dielectric materials
Encapsulants
Structural components
Housings
Mounting interfaces
Electrical terminals and leads

If the exterior housing is separated from the hotspot by high-resistance materials, attaching a cooling device to the outside of the enclosure may not cool the internal region efficiently.

An electrical lead or terminal may provide a more direct path because it can be physically connected to the current-carrying or heat-generating region inside the device.

Using that conductor as part of the cooling path can:

Reduce the effective thermal resistance to the hotspot
Increase heat flow toward the thermoelectric module
Reduce the temperature rise at the temperature-sensitive region
Improve thermal response
Reduce the cold-side temperature required from the thermoelectric module
Simplify packaging in some applications

The conductor does not become the only heat-transfer path. Heat continues to flow through every available path according to the associated thermal resistances and temperature gradients.

The benefit comes from adding or improving a relatively low-resistance path between the temperature-sensitive region and the active thermal-management system.

Direct and Indirect Thermoelectric Coupling

The thermoelectric module can be connected to the conductor in different ways.

Direct coupling

The thermoelectric module is mounted directly against the conductor or terminal.

Potential advantages include:

Shorter thermal path
Fewer intermediate components
Lower interface resistance
Compact packaging
Faster thermal response

Direct coupling may require electrical isolation if the thermoelectric module or attached heat-rejection structure cannot share the conductor’s electrical potential.

Indirect coupling

An intermediate thermal component connects the conductor to the thermoelectric module.

This can help with:

Electrical isolation
Mechanical packaging
Module positioning
Load distribution
Thermal expansion
Assembly and serviceability

However, every added material layer and interface introduces additional thermal resistance.

The preferred architecture depends on whether the thermoelectric device can be located directly at the intended thermal interface without creating electrical, mechanical, manufacturing, or reliability problems.

Why Thermal Resistance Affects Thermoelectric Performance

The thermal resistance between the temperature-sensitive region and the thermoelectric cold side affects the operating point of the entire thermoelectric system.

For a given heat flow, the temperature drop across a thermal path increases as thermal resistance increases.

If the path between the electrical device and the thermoelectric module has high thermal resistance, the thermoelectric cold side must operate at a lower temperature to maintain the internal device region at its target temperature.

This increases the temperature difference across the thermoelectric module.

A larger thermoelectric temperature difference generally:

Reduces available cooling capacity
Increases electrical power consumption
Lowers coefficient of performance
Increases the hot-side heat-rejection requirement
Makes the system more sensitive to ambient temperature
Places greater demands on the heat sink or coolant system

A well-designed conductor path can reduce this penalty by lowering the temperature drop between the internal temperature-sensitive region and the thermoelectric module.

The goal is not merely to make the conductor cold. The goal is to reduce the complete thermal resistance between the heat source and the thermoelectric cold side.

The Parasitic Heat-Leak Tradeoff

The same conductor that creates a useful thermal path toward the electrical device can also create an unwanted thermal path away from it.

For example, a cooled terminal may also be connected to:

External wiring
A connector
A bus bar
A circuit board
A power supply
A chassis
Ambient surroundings

Some cooling can therefore be lost through the external portion of the conductor instead of being delivered only to the intended temperature-sensitive region.

This creates a competition between two thermal paths:

A useful path between the thermoelectric module and the target region
A parasitic path between the thermoelectric module and external hardware

The system works best when the useful path has lower thermal resistance than the unwanted path.

Design methods for reducing parasitic heat leakage can include:

Selecting the thermoelectric attachment location carefully
Reducing conductor length between the module and target region
Increasing useful-path cross-sectional area
Reducing unnecessary external conductor cross section
Using thermal isolation features where electrically practical
Controlling contact area
Managing connector and cable geometry
Separating the heat-rejection structure from the cooled conductor
Modeling the complete thermal-resistance network

This is one reason conductor-based thermoelectric cooling must be evaluated at the system level.

A conductor geometry that is excellent electrically may not be optimal thermally. Likewise, a geometry that minimizes heat leakage may create excessive electrical resistance, voltage drop, current density, or resistive heat generation.

The design must balance both functions.

Electrical and Thermal Design Tradeoffs

Electrical and thermal resistance often move in the same direction for a metallic conductor.

Increasing conductor cross-sectional area tends to reduce:

Electrical resistance
Resistive heating
Thermal resistance

Reducing conductor length has similar effects.

This can be beneficial when the conductor links the thermoelectric module to the target region. However, it can be detrimental when the same conductor continues past the cooled region and creates an unwanted heat leak.

Important tradeoffs include:

Electrical resistance versus thermal isolation
Current capacity versus parasitic heat transfer
Conductor stiffness versus thermal expansion
Compact packaging versus serviceability
Electrical isolation versus thermal interface resistance
Mechanical reliability versus thermal contact pressure
Cooling performance versus condensation risk

The best design is not necessarily the conductor with the highest thermal conductivity.

It is the conductor geometry and system architecture that direct the greatest useful heat flow toward the thermoelectric module while limiting unwanted heat flow elsewhere.

Thermoelectric Cooling of Power Electronics

Power electronics are a natural application for conductor-based thermal management because high-current terminals and bus structures often connect directly to heat-generating semiconductor devices.

Possible applications include:

IGBT modules
MOSFET assemblies
Power converters
Inverters
Motor drives
High-current switching equipment
Power amplifiers
Rectifiers
High-power DC systems

In many of these systems, the semiconductor package is connected to copper conductors with substantial cross-sectional area.

A thermoelectric module coupled to the correct part of that conductor may provide localized cooling closer to the internal heat source than an enclosure-mounted cooling system.

Whether this is beneficial depends on:

Device heat generation
Duty cycle
Junction-to-terminal thermal resistance
Junction-to-case thermal resistance
Conductor geometry
Module placement
Maximum allowable junction temperature
Available electrical power
Ambient conditions
Hot-side heat rejection

Conductor-based cooling should therefore be compared with conventional baseplate, cold-plate, air-cooling, and liquid-cooling approaches rather than assumed to be superior in every application.

Lasers, LEDs, and Optical Devices

Lasers and high-power LEDs can be sensitive to temperature because temperature affects:

Optical output
Wavelength
Efficiency
Lifetime
Dimensional stability
Calibration
Spectral performance

Electrical leads or electrodes may provide direct access to regions near the active device.

In compact systems, a conductor-based thermoelectric path may allow localized heating or cooling without requiring the thermoelectric module to occupy the same surface used for optical alignment, mounting, or heat spreading.

The approach may be especially useful when:

The active region is difficult to reach
Packaging space is limited
Bidirectional heating and cooling are required
Precise temperature control matters more than maximum bulk cooling capacity
The device operates intermittently
Localized control can reduce the need to condition the entire enclosure

Motors, Transformers, and Other Wound Electrical Devices

Motors, transformers, inductors, and wound electrical devices contain electrically active regions that may be difficult to cool directly.

Terminals, winding leads, and conductors can provide thermal paths from internal regions toward the exterior.

A thermoelectric system could potentially use these conductors to:

Assist localized cooling
Support cold-weather warm-up
Stabilize sensor or winding temperature
Reduce temperature variation
Manage intermittent high-load conditions

However, the conductor path must be evaluated against other heat-transfer paths through laminations, insulation, housings, oil, coolant, and airflow.

For high-heat-load devices, thermoelectric cooling may be most useful for localized control, temperature trimming, or transient conditions rather than as the sole bulk heat-rejection method.

Battery Applications and the Later Bus-Bar Concept

Batteries are one application of the broader conductor-based thermal-management principle.

Battery terminals and bus bars carry current and also conduct heat. This makes them potential pathways for heating or cooling selected cells or cell groups.

A later bus-bar-mounted thermoelectric battery thermal management patent applied this principle more specifically by placing thermoelectric devices on the electrical interconnects between adjacent batteries.

That configuration provided localized cell-pair heating and cooling through the bus bars, terminals, and electrical connections.

The broader electrical-device patent established the idea that a current-carrying conductor could become part of the thermal path. The later battery implementation applied that concept to a specific battery pack architecture.

Controls and Temperature Sensing

The usefulness of localized thermoelectric cooling depends heavily on sensing and control.

Possible control inputs include:

Device temperature
Conductor temperature
Ambient temperature
Electrical current
Voltage
Power dissipation
Duty cycle
Operating mode
Predicted thermal load
Maximum allowable temperature
Condensation conditions

A controller can adjust thermoelectric current to:

Maintain a target temperature
Limit peak temperature
Reduce temperature gradients
Preheat a device before operation
Provide additional cooling during high-load events
Reduce power when cooling demand is low
Reverse heat-pumping direction when heating is required

In some systems, feed-forward control based on electrical load can improve response because the controller can anticipate heat generation before the temperature sensor registers the full temperature increase.

The thermoelectric device should not be controlled independently from the rest of the system. The hot-side heat sink, fans, pumps, electrical load, thermal interfaces, and condensation limits all affect the safe operating range.

Waste-Side Heat Rejection

A thermoelectric device does not eliminate heat. It moves heat from one side to the other.

The hot side must reject:

Heat pumped from the electrical device
Electrical power consumed by the thermoelectric module

The total hot-side heat load is therefore greater than the cooling load alone.

Waste-side heat rejection may use:

Natural convection
Forced-air heat sinks
Liquid cooling
Refrigerant cooling
Chassis conduction
Heat pipes
Vapor chambers
Remote radiators
Other thermal-management systems

A poorly designed hot side increases the thermoelectric temperature difference, reduces cooling capacity, increases power consumption, and lowers COP.

In many thermoelectric applications, waste-side heat rejection is the dominant system constraint.

When Conductor-Based Thermoelectric Cooling Makes Sense

This approach is most promising when:

A conductor provides direct access to a temperature-sensitive region
Conventional surface cooling has a high-resistance path to the hotspot
Localized temperature control is more important than bulk cooling
Bidirectional heating and cooling are valuable
Packaging space is constrained
A compressor or refrigerant system is undesirable
The operating load is intermittent or variable
The electrical and thermal functions can be integrated without excessive complexity

It may be less attractive when:

The conductor creates a large parasitic heat leak
The heat load is too high for practical thermoelectric cooling
A conventional cold plate already provides a low-resistance path
Electrical isolation requirements add excessive thermal resistance
Available power is limited
Waste-side heat rejection is inadequate
Condensation cannot be controlled
Reliability requirements prohibit the added interfaces

A feasibility study should compare conductor-based cooling with other architectures before hardware is selected.

Relevance to Current Applied Thermoelectric Solutions Work

The principles explored in this earlier patent remain relevant to the thermoelectric engineering work led by Alfred Piggott at Applied Thermoelectric Solutions.

Applied Thermoelectric Solutions evaluates the complete path between the heat-generating region and the final heat-rejection system, including:

Internal device thermal resistance
Electrical conductor geometry
Useful and parasitic thermal paths
Thermoelectric module placement
Thermal interface resistance
Electrical isolation
Power electronics
Temperature sensing
Control strategy
Mechanical integration
Condensation risk
Waste-side heat rejection
System efficiency

This work can support applications involving:

Electronics hotspot cooling
Power electronics
Lasers and optical systems
Electrical enclosures
Battery systems
Motors and generators
Laboratory instruments
Medical and scientific devices
Custom thermoelectric assemblies

The key question is not simply whether a thermoelectric module can cool an electrical device.

The more useful question is:

Can the thermoelectric device be connected to the temperature-sensitive region through a sufficiently low-resistance thermal path while limiting parasitic heat leakage and maintaining practical power consumption?

Thermoelectric Engineering Support

Applied Thermoelectric Solutions helps companies evaluate, design, model, prototype, test, and validate thermoelectric cooling, heating, and temperature-control systems.

Our work can include:

Thermoelectric feasibility studies
Thermal-resistance-network modeling
Conductor-based cooling analysis
Electronics hotspot evaluation
Thermoelectric module selection
Cold-side and hot-side thermal design
Thermal interface analysis
Power and COP prediction
Heat-sink and liquid-cooling evaluation
Electrical isolation strategy
Control-system development
Prototype design and engineering
Prototype fabrication and assembly
Instrumentation and testing
Performance validation
Design refinement based on test results
Custom Thermoelectric Solutions

Evaluating Thermoelectric Cooling for an Electrical Device?

Applied Thermoelectric Solutions can help determine whether conductor-based cooling, direct device cooling, enclosure cooling, or another architecture provides the best technical path.

Patent PDF

The patent PDF is provided below as technical background showing earlier work by Alfred Piggott, founder and CTO of Applied Thermoelectric Solutions, in thermoelectric cooling, conductor-based heat transfer, electrical-device thermal management, and system integration.

The patent was developed by Alfred Piggott and other inventors while he was working at Gentherm.

Frequently Asked Thermoelectrics for Electrical Conductor Questions

How can an electrical conductor also act as a thermal pathway?

Metals such as copper and aluminum conduct both electricity and heat. A terminal, lead, electrode, or bus bar can therefore carry electrical current while also transferring thermal energy between an internal device region and a thermoelectric module.

Why cool an electrical terminal or lead?

A terminal or lead may connect more directly to an internal hotspot than the external housing does. Cooling the conductor can create a lower-resistance thermal path to the temperature-sensitive region, depending on the device construction.

Does cooling the conductor guarantee that the device hotspot will be cooled?

No. Cooling effectiveness depends on the thermal resistance between the hotspot and conductor, the resistance between the conductor and thermoelectric module, and the competing heat-transfer paths within the device.

Can external wiring create an unwanted heat leak?

Yes. The conductor may transfer cooling toward the target region, but it may also transfer heat to or from external cables, connectors, circuit boards, or other hardware. This parasitic path must be included in the thermal analysis.

Why does conductor thermal resistance matter to thermoelectric performance?

A high resistance between the target region and thermoelectric module requires the module’s cold side to operate at a lower temperature. This increases the temperature difference across the module, reduces cooling capacity, increases power consumption, lowers COP, and increases hot-side heat rejection.

What types of electrical devices could use this approach?

Potential applications include power electronics, IGBTs, MOSFETs, inverters, power amplifiers, motors, transformers, lasers, LEDs, batteries, sensors, and other devices where conductors provide thermal access to a temperature-sensitive region.

Does this concept apply only to batteries?

No. We support thermoelectric cooling, heating, temperature control, and power-generation applications. We also work on related thermal management problems where thermoelectrics may be part of a broader system solution.

How is this different from attaching a thermoelectric module to a housing?

Housing-mounted cooling removes heat through the device enclosure. Conductor-based cooling uses an electrical lead, terminal, electrode, or bus structure that may provide a more direct path to the internal heat source. The better approach depends on the thermal resistance of each path.

Does conductor-based thermoelectric cooling eliminate the need for a heat sink?

No. Heat pumped from the electrical device, plus the electrical power consumed by the thermoelectric module, must be rejected from the module’s hot side.

Is direct coupling better than using an intermediate thermal component?

Direct coupling usually minimizes material and interface resistance. However, an intermediate component may be necessary for electrical isolation, mechanical packaging, load distribution, or assembly. The complete system must be evaluated.

How does this relate to the bus-bar-mounted battery cooling patent?

The broader electrical-device patent explored using current-carrying conductors as thermal pathways. The later battery patent applied the principle specifically to battery bus bars and provided localized heating and cooling of adjacent cell pairs.

Is this an Applied Thermoelectric Solutions patent?

The patent was developed by Alfred Piggott, founder and CTO of Applied Thermoelectric Solutions, and other inventors while he was working at Gentherm. It is included here to document Alfred Piggott’s earlier technical work and its relevance to current thermoelectric system design, prototype development, testing, and integration.