Proceedings of the Asian Conference on Thermal Sciences 2017, 1st ACTS
March 26-30, 2017, Jeju Island, Korea
ACTS-P00367
HEAT TRANSFER CHARACTERISTICS OF ELECTRONIC CONTROL UNIT
HEATSINK FOR 72V NEIGHBORHOOD ELECTRIC VEHICLE
Mahesh Suresh Patil1, You-Ma Bang1, Jae-Hyeong Seo2, Dae-Wan Kim2, Moo-Yeon Lee3*
1
Graduate School of Mechanical Engineering, Dong-A University Hadan 840, Saha-gu, Busan 604-714, Republic of
Korea
2
NTF Tech co., Hadan 840, Saha-gu, Busan 604-714, Republic of Korea
3
Department of Mechanical Engineering, Dong-A University, Hadan 840, Saha-gu, Busan 604-714, Republic of
Korea

Presenting Author: [email protected]
Corresponding Author: [email protected]
*
ABSTRACT
Electronic control modules are basic components in most of the battery operated vehicles and bicycles with different
controlling functions including speed and power control. The ECUs in vehicles and bicycles are usually made with
air-tight enclosure to prevent the admittance of water and moisture, which makes it tough to provide forced
convection cooling solutions. This suggests to create a cooling system with innovative and efficient cooling system
design to dissipate heat adequately. The present study involves analysis of thermal performance of existing cooling
system used for electronic control module of 72 V 3-wheeler neighborhood electric vehicle. To evaluate the cooling
performance of existing heatsink case model under city-drive and uphill drive mode with varying load conditions an
experiment is conducted. Based on experimental results, a new model is proposed with modified design. A
numerical analysis is carried out to validate and analyze the thermal performance of the developed model.
KEYWORDS: Cooling performance, Electronic control unit, Heatsink, Heat transfer, Neighborhood electric
vehicle
1. INTRODUCTION
Electric vehicles (EVs) are being considered as promising option in-place of internal combustion engine (ICE) based
vehicles to overcome the issues like fossil fuel depletion and CO2 emission which are degrading the environmental
quality rapidly. There is an urgent need to increase the EV market penetration to compete with very popular ICEbased vehicles. ICE uses fuel combustion energy to move the piston and eventually translate it into linear motion of
vehicle. The speed and torque generation depends on fuel mass flow rate and combustion cylinder specifications. In
case of EVs, the power is supplied by batteries and the speed and power is controlled by electronic control unit
(ECU) and electric motor. In a neighborhood electric vehicle (NEV) ECU is composed of many electronic
components including capacitors and metal–oxide–semiconductor field-effect transistors (MOSFETs). During
operation, capacitors and MOSFETs dissipate large amount of heat. The dissipated heat is needed to be removed
continuously for smooth operation of NEV. It is very important to maintain the ECU operating temperature in
optimum range in order to increase the durability and longevity of the ECU components. Moreover, electronic
devices and components are sealed and packaged air tight to prevent from water and moisture ingress, which creates
three issues. Firstly, due to sealed system it becomes extremely hard to include a forced convection option. Secondly,
due to compact designs, heat flux is surprisingly high owing to availability of lesser surface area to transfer
generated heat. Thirdly, it indicates that, the cooling system should be based on conduction models such as efficient
heatsink. In this study, an experiment is conducted on 72V 3-wheeler to evaluate the surface temperature of ECU
casing. Using computer-aided design software, a model is created and ANSYS 17.0 is used to carry out numerical
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simulation. The results of numerical simulation are validated with experimental data and thermal performance is
analyzed.
2. EXPERIMENT
An experiment is conducted to measure the ECU case temperature. The fig. 1 (b) and (c) show the experiment setup.
The battery and ECU are located below the rear seat of NEV. The relative location of battery, BMS, ECU and
thermocouples are shown in schematic diagram (Fig.1 (a)). Experiment parameters are discussed in Table 1. To
measure the position, velocity and altitude, global positioning system (GPS) Bluetooth instrument (RoyalTek logger)
is used. Thermocouples (T-type), data logger (GRAPHTEC midi LOGGER GL 820) and a computer is used for post
processing of obtained data. The measurement accuracy of data logger is (±0.1% of reading + 0.5ºC). The
maximum surface temperature of ECU casing is obtained as 45 ºC and 49 ºC for plain city drive and hilly area drive,
respectively.
Table 1 Details of the experiment.
Parameters
Value
Velocity variation
0-35 Km/s
Ambient temperature
25 ºC
Time duration
1500 s
(a)
(b)
(c)
Fig. 1 Experiment setup
3. NUMERICAL SIMULATION
The numerical model is developed using CAD software SolidWorks’15. For meshing and solving, commercial heat
and flow analysis software ANSYS 17.0 steady-state thermal analysis is used. The rise in surface temperature of
capacitor is evaluated using the equation (1) [1]. The ‘I’ represents ripple current, ‘R’ represents equivalent series
resistance (ESR), ‘  ’ represents heat radiation factor and S is surface area of the capacitor. Heat radiation factor
and ESR are evaluated using equation (2) and (3), respectively. Values of tan  (dissipation factor), working voltage,
capacitance, frequency and ripple current are used from datasheet for aluminum electrolytic capacitor (TS13D
CD263) [2]. The capacitor surface temperature increases by 28.76 ºC, which makes the total average temperature of
capacitor surface as 53.76 ºC .The heat dissipated by MOSFET (CHN 447 made by ST [3]) is evaluated by equation
(4). The surface temperature of MOSFETs is considered as 50 ºC. The boundary conditions and mesh details are
provided in Table 2. The fig. 2 shows the ECU and model images.
2
(b)
(a)
(c)
(d)
Fig. 2 ECU system and model
Tc 
I2 R
 S
  2.3 103  S 0.2
R
tan 
2fC
Equation (1)
Equation (2)
Equation (3)
Table 2 Numerical simulation details
Parameters
Value
Capacitor surface temperature
53.76 ºC
MOSFET surface temperature
50 ºC
Surface boundary condition
Natural convection (10 W/m2-K)
Number of elements
2557993
The maximum surface temperature of ECU case using numerical simulation is recorded as 41 ºC. The
error of 8.8% is observed between experimental and simulation which is in acceptable range. The fig. 4
shows the temperature distribution of existing model.
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(a)
(b)
Fig. 4 (a) Meshing (b) temperature distribution
4. CONCLUSIONS
The NEVs are promising option for short-range driving. The ECU is an important component made of electronic
equipment including capacitors and MOSFETs. The heat dissipated by capacitor and MOSFET must be removed
continuously and for proper functioning the operating temperatures are needed to be maintained as low as possible.
This study is important for the design of an efficient cooling system of ECU and battery management system. To
measure the ECU casing surface temperature an experiment is conducted. The numerical model is developed and
validated with experiment data with an error of 8.8%.
ACKNOWLEDGMENT
This work was partly supported by the Materials and Components Technology Development Program of
MOTIE/KEIT [20161016] and this research was supported by Basic Science Research Program through the
National Research Foundation of Korea(NRF) funded by the Ministry of Education(2016R1D1A1B03935822). This
work (Grants No. C0398373) was supported by Business for Cooperative R&D between Industry, Academy, and
Research Institute funded Korea Small and Medium Business Administration in 2016.
NOMENCLATURE
ΔTc
R

f
Surface temperature rise
ESR of capacitor
Heat radiation factor
frequency
(ºC)
(Ω)
(W/ºC-cm2)
(Hz)
I
S
C
Ripple current
Surface area of capacitor
Capacitance
(Arms)
(cm2)
(μF)
REFERENCE
[1] Technical Notes for electrolytic capacitor, Rubycon Corporation, http://www.rubycon.co.jp/en/products/alumi/technote.html
[2] Suntan Technology Company Limited, Aluminum electrolytic capacitor, TS13D CD263 datasheet, Available:
http://www.suntan.com.hk/pdf/Aluminum-Electrolytic-Capacitors/TS13DG-CD263.pdf [Accessed: Oct. 30, 2016]
[3] ST Microelectronics, Power MOSFET, STH15810-2 datasheet, Available: http://www.st.com/content/st_com/en/products/powertransistors/power-mosfets.html [Accessed: Oct 30, 2016]
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