As the new energy vehicle (NEV) industry advances toward higher range, higher power, and faster charging, the power density of electric drive systems continues to increase, and the amount of heat generated during operation grows exponentially. From the rapid charging of a 100 kWh battery pack to the full-load operation of a 200 kW permanent magnet synchronous motor, if heat cannot be dissipated in time, it will directly threaten vehicle safety and performance.
This article systematically analyzes the causes of heat generation in NEVs, details mainstream types of heat sinks and their application cases, and provides practical selection guidelines and high power thermal solutions for engineers and designers.
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Sources and Hazards of Heat Generation in New Energy Vehicles
Compared with traditional fuel vehicles, NEVs have higher drive efficiency. However, under high power and high current conditions, they still produce a large amount of heat. If this heat is not removed promptly, it will lead to safety risks and performance degradation.
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Three Core Sources of Heat
1.1 Power Battery System
Heat sources: Ohmic resistance heat (I²R), polarization heat, and side reaction heat.
During high-rate charging and discharging, electrode polarization, electrolyte decomposition, and SEI film reactions generate additional heat.
Data show that for a mainstream 100 kWh ternary lithium battery pack (400 V voltage platform, 250 Ah capacity) with a single cell internal resistance of about 2 mΩ, under a 3C charge/discharge condition (750 A current), the heat generated per cell can reach 1.1 kW according to Joule’s law. A pack composed of 20 cells in series can therefore produce an instantaneous heat load exceeding 20 kW.
1.2 Motor System
Heat sources: Copper losses (I²R) in the winding and iron losses (eddy currents) in the stator core are the main contributors.During high-speed operation, motor efficiency is usually between 90–95%, meaning 5–10% of the input energy converts to heat.
For example, a 200 kW permanent magnet synchronous motor operating at 92% efficiency generates approximately 16 kW of heat at full load.
1.3 Electronic Control System
Heat sources: The core of the inverter consists of IGBT or SiC power modules, which generate switching and conduction losses during high-frequency operation.Even though inverter efficiency can reach 98%, for devices controlling hundreds of kilowatts, the remaining 2% of loss can amount to several kilowatts of heat.
For instance, in a 200 kW drive system with a 3% loss, the IGBT module generates about 6 kW of heat. Since the chip area is only a few square centimeters, the heat flux density can exceed 50 W/cm²—far higher than that of ordinary electronic components.
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Hazards of Inadequate Cooling
The accumulation of heat in NEVs is not a theoretical issue but a practical problem that has repeatedly caused failures in real-world use, directly affecting driving safety, component lifespan, and user experience.
2.1 Battery Risks
Permanent performance degradation: Prolonged exposure to high temperatures accelerates electrolyte decomposition and electrode aging. Studies show that when a battery operates at 45°C, its lifespan declines twice as fast as at 25°C. A temperature difference greater than 10°C between cells can reduce battery life by more than 20%.
Thermal runaway and fire: Once the temperature exceeds 60°C, exothermic side reactions intensify and can cause thermal runaway—the most dangerous outcome. A chain of internal reactions can push the temperature above 500°C, triggering fire or explosion. Many early EV self-ignition incidents were traced to battery thermal management failures and local overheating.
2.2 Motor and Inverter Risks
Power derating: To prevent damage, the ECU automatically limits power output when temperatures rise, causing sluggish acceleration and reduced top speed. If you’ve ever felt your EV “lose power” on a hot day, it was likely thermal protection kicking in.
Permanent magnet demagnetization: High temperatures can irreversibly demagnetize the motor’s rare-earth magnets, permanently reducing efficiency. Magnets begin to demagnetize above 150°C, and coil insulation degrades rapidly above 120°C, halving its lifespan.
Component burnout: IGBT chips are extremely temperature-sensitive; when the junction temperature exceeds about 175°C, thermal breakdown can occur, leading to module failure and vehicle shutdown.
Hence, an efficient cooling system is not an optional feature—it is the lifeline for safe and reliable NEV operation.
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Types of Heat Sinks for NEVs and Real Application Cases
Different NEV components have different power densities and installation constraints. The following are the four mainstream categories of heat sinks, each with its own structural design, performance characteristics, and application scenarios.
1.Liquid Cold Plate Heat Sink
Principle: Uses aluminum or copper base plates (copper has higher thermal conductivity, aluminum offers lower cost) with internal channels formed by etching, welding, or extrusion. Common channel patterns include serpentine, parallel, and micro pin-fin types. Coolant circulates through the plate under pump pressure, directly absorbing heat from sources such as battery cells or IGBT modules, which is then transferred to the front-end condenser (integrated with the vehicle’s air conditioning system) for dissipation.
Suitable for: High-temperature and high-power scenarios—traction batteries (≥50 kWh), medium to high-power motors (>100 kW), and electronic control systems (IGBT/SiC modules).
Real Cases:
Tesla Model 3 employs a “direct-contact cooling plate” design that keeps the battery temperature below 47°C during a 5-minute fast charge.
BYD Han EV integrates a liquid cooling plate in its inverter system, reducing IGBT chip temperature by 15°C and improving power stability by 20%.
Liquid cold plates are widely regarded as the “temperature control king” of high-end EVs.
2. Air-Cooled Heat Sink
Principle: Uses forced air convection driven by fans, with either parallel (uniform cooling) or series (simpler structure) airflow designs.
Suitable for: Small EV batteries, low-power motors (<50 kW), and onboard chargers.
Real Case:
Wuling Hongguang MINI EV adopts a serial air-cooled system, which costs 70% less than liquid cooling. This setup is ideal for short urban commutes and can be restored simply by replacing the fan during maintenance. Air cooling remains the most cost-effective option for budget-friendly vehicles.
3.Die Casting Heat Sink
Principle: Made from ADC12 aluminum alloy using one-piece die-casting. The heat dissipation area is increased by 40% compared with traditional designs, while also providing high mechanical strength and impact resistance.
Suitable for: Battery housing and motor casing.
Real Cases:
Li Auto L8 uses an integrated die-cast battery pack underplate with 200 fins, reducing battery temperature by 5–8°C in summer and retaining heat in winter through the heat pump system.
Yutong E10 electric bus features a die-cast motor housing with 20 mm fins combined with forced air cooling, keeping full-load temperature ≤140°C.
4. Extrusion Heat Sink
Principle: Manufactured by extruding 6063 or 6061 aluminum alloys at high temperatures to form continuous parallel fins. The large surface area enhances convection efficiency, and the surface is anodized for higher emissivity and corrosion resistance.
Suitable for: DC–DC converters and small electronic modules.
Real Case:
Geely Galaxy L7 DC–DC converter uses a 120 × 60 × 25 mm aluminum heat sink and maintains operating temperature ≤ 100°C.
Typical DC–DC converters operate between 1–3 kW with efficiencies of 94–96%, meaning 40–180 W of heat is dissipated—well within the capacity of forced air cooling, without requiring liquid cooling.
III. Heat Sink Recommendations by NEV Component
| Component | Recommended Type | Application Scenario | Key Advantage |
| Power Battery | Liquid Cold Plate Heat Sink | Mainstream EV models | Achieves the optimal balance of efficiency, cost, and performance; ensures fast charging, safety, and battery life; is the absolute mainstream in the current market. |
| Air-Cooled Heat Sink | Micro or economy EVs | Optimal cost and simple structure; sufficient for low-power and slow-charging scenarios. | |
| Die Casting Heat Sink | Battery pack casings | Provides auxiliary heat dissipation and structural protection. | |
| Drive Motor | Liquid Cold Plate Heat Sink | Medium/high power EVs | Liquid cooling can continuously dissipate the heat from copper loss/iron loss. |
| Air-Cooled Heat Sink | Micro-cars/low-cost models | Simple structure and low cost; suitable for motors <50kW. | |
| Die Casting Heat Sink | Motor casings | Enables overall heat dissipation and serves as a structural component. | |
| Electronic Control System | Liquid Cold Plate Heat Sink | EV/PHEV systems | IGBT/SiC chips generate a large amount of heat per unit area; heat must be quickly conducted away through liquid-cooled plates to prevent overheating and burnout. |
| Air-Cooled Heat Sink | Economy models | Low-power electronic control systems generate less heat; air cooling is low in cost. | |
| DC–DC Converter | Extrusion Heat Sink | Power conversion modules | Mature technology and cost-effective |
The cooling system of a new energy vehicle functions as its temperature regulator, directly determining performance and safety under environments ranging from –40°C to 40°C.
For automakers, heat sink selection should follow the principle of “power matching + application suitability”:High-power, long-range vehicles → prioritize liquid cooling systems.Low-cost commuter EVs → adopt air-cooled solutions.Complex or heavy-duty vehicles → combine die-cast structures for both protection and heat dissipation.Partnering with heat sink manufacturers who provide thermal simulation and customized design services ensures optimized flow channel design, validated prototypes, and high-efficiency mass production.
We are a heat sink manufacturer based in Guangdong, China, offering customized designs and specialized solutions for new energy vehicle battery cooling plate manufacturing.Our engineering team provides comprehensive thermal simulation and design optimization support. Contact us anytime for professional technical assistance.
