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Toelichting Opdracht DMO Sports Cars

Onderzoek naar het aansturen van OEM EV componenten voor elektrische conversie

November 2020 Confidentiality clause This document is confidential. Neither the whole nor any part of this document may be disclosed to any third party without the prior written consent of DMO Sports Cars. The copyright of this document is vested in DMO Sports Cars 2020.

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1. Toelichting DMO is een Britse fabrikant van hoogwaardige sportwagens die voertuigen volledig gebouwd of in onderdelen levert, klaar voor thuismontage. Voor meer informatie: Facebook, Instagram, Youtube en www.dmosportscars.com. DMO Sports Cars heeft de ambitie om op de markt te komen met een elektrische sportauto. In een haalbaarheidsstudie van 2018 wordt deze ambitie beschreven. Na onderzoek is geconcludeerd dat het gebruik van nieuwe componenten voor elektrisch voertuig de volgende vraagstukken oplevert: - Nieuwe componenten zijn kostbaar wat zich vertaalt in een kostenplaatje vanaf € 35.000,00 in

onderdelen; - Nieuwe onderdelen zijn niet EMC gecertificeerd, hierdoor is toelating op de Nederlandse wegen

verboden door de RDW; - Componenten met een EMC certificaat zijn geen performance componenten (vermogen) en zijn

kostbaar vanwege de R&D investering van de aanbieder; - Componenten met een EMC certificaat hebben niet de ideale afmetingen en specificaties voor DMO

Sports Cars, daarnaast is de keuze erg beperkt. Een gunstige marktontwikkeling is het feit dat de RDW voertuigen die geconverteerd zijn naar elektrisch toelaat indien de componenten afkomstig zijn uit een elektrisch voertuig wat eerder toegelaten is tot het Nederlands wegverkeer. Zogenaamde OEM onderdelen. In de haalbaarheidsstudie van 2019 wordt de inzet van OEM componenten beschreven. De onderzoeksvraag voor DMO Sports Cars is als volgt: Het aantal automerken wat performance onderdelen gebruikt is groeiend. Hierbij is Tesla een goed voorbeeld, maar Jaguar en de klassieke Duitse merken bieden inmiddels +300 PK elektrische voertuigen aan. Het klopt dat Rimac of Lotus inmiddels 2000 PK aanbiedt, echter, componenten uit deze auto’s zijn zeer kostbaar. De focus ligt dus op aanbieders van performance elektrische voertuigen (+300PK) en de componenten daarvan. DMO Sports Cars ziet een kans in het hergebruik, circulair, van deze componenten in het chassis van het DMO model Legend. Concreet is de onderzoeksvraag: Op welke manier kan DMO Sports Cars componenten van verscheidene automerken met elkaar laten communiceren. Voorbeeld: Een accupakket uit een Audi wordt geladen met een “on board charger” uit een BMW, de BMS afkomstig uit een Tesla moet de waarden van de accu lezen en communiceren met de “on board charger” wanneer de accu voldoende geladen is. Eventueel moet de BMS communiceren met een koelsysteem uit een Volkswagen om de accu te koelen tijdens het laden. Een systeem ontwikkelen wat de communicatie verzorgt tussen deze componenten, ongeacht de fabrikant, is voor DMO een welkome ontwikkeling. Punt twee is een beknopt overzicht van de componenten van een elektrisch voertuig ter referentie.

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2. Overzicht elektrische componenten (Engels)

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Motor

The motor converts electric energy into kinetic energy that moves the wheels. The advantage of using the motor instead of an engine is numerous: first, the noise and the vibration we typically associate with cars are minimized. Many passengers riding EVs for the first time are surprised by just how quiet and comfortable the ride feels. Moreover, the EV powertrain is smaller than the engine, thus providing lots of additional space for efficient vehicle design―like expanded cabin space or storage.

The motor is also in part an electric generator―it converts the kinetic energy generated while in neutral gear(e.g. while the car is going downhill) into electric energy saved to the battery. The same energy-saving idea applies when the car is reducing its speed, culminating in the so-called “regenerative braking system.” Some of the Hyundai Motor Group’s EVs are equipped with a mechanism that can control the levels of regenerative braking via paddle shifters on the steering wheel, which not only improves the fuel economy but also adds an interesting and fun element to driving.

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Reducer

The reducer is a kind of transmission in that it serves to effectively convey the motor’s power to the wheel. But it carries the special name―reducer―for a reason: the motor has a far higher RPM than that of an internal combustion engine, so whereas transmissions change the engine RPM to match the driving circumstance, the reducer must always reduce the RPM to an appropriate level. With the reduced RPM, the EV powertrain can take advantage of the resulting higher torque.

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Battery

The battery stores electrical energy and is the equivalent of a fuel tank in an internal combustion engine. The maximum driving distance of an EV is often determined by the battery capacity―the higher the capacity, the higher the driving distance. In that light, increasing the capacity may seem an obvious choice, since high driving distance reduces the annoying need for frequent stops at charging stations. But the choice actually isn’t so obvious, because the battery’s size and weight also have large implications on vehicle performance. The larger and heavier battery takes away from cabin/storage space and worsens the energy efficiency and fuel economy. The best way to optimize performance, then, is to maximize the battery’s energy density―that is, having a small, lightweight battery that stores as much electric energy as possible.

Thanks to the recent advancements in battery technology, the more recent EVs boast significant upgrades over older models in terms of battery density and driving distance. The Kia Soul Booster EV, for example, is equipped with a 64kWh lithium-ion battery that lasts for the max distance of 386 km(according to Korean certification standards). The battery life also saw significant improvements: assuming a normal pattern of usage, the Soul Booster EV’s battery can last through the entire life cycle of the vehicle. To explain in greater detail, understand first that lithium-ion batteries on EVs show battery life that varies with the charging pattern. If the charging pattern is such that the entire battery is exhausted and recharged to full, the battery can be used for 1,000 charges; if the battery is used to half(50%) and recharged, 5,000 charges; if one-fifth of the battery is used(20%) and recharged, 8,000 charges. Meaning, if the Soul Booster EV is driven for 77 kilometers a day(equivalent to the 20% of the max driving distance) and recharged every night, the battery can last for 8,000 days(22 years).

Battery Management System(BMS)

The Battery Management System(BMS) manages the battery’s many cells so that they can operate as if they are a single entity. The EV’s battery consists of as little as tens to as many as thousands of mini-cells, and each cell needs to be in a similar condition to the others in order to optimize the battery’s durability and performance.

Most often, the BMS is built into the battery’s body, though sometimes it is incorporated into the Electric Power Control Unit(EPCU). The BMS mainly oversees the cell’s charge/discharge status, but when it sees a malfunctioning cell, it automatically adjusts the power status of the cell(on/off) through a relay mechanism (the conditional mechanism for opening/closing other circuits).

Battery Heating System

In lower temperatures, the battery sees a decrease in both charging capacity and speed. The battery heater exists to keep the battery within the ideal temperature range, preventing seasonal performance decreases and maintaining the max driving distance. The system functions while charging as well, ensuring the efficiency of the charge.

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On-board Charger(OBC)

The On-board Charger(OBC) is used to convert Alternating Current(AC) from slow chargers or portable chargers used on home outlets into Direct Current(DC). This may make the OBC look similar to the traditional inverter, but they differ crucially in function; the OBC is for charging, and the inverter is for acceleration/deceleration. Incidentally, the OBC is not needed in fast-charging, since fast chargers already supply the electricity in direct current.

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Electric Power Control Unit(EPCU)

The Electric Power Control Unit(EPCU) is an efficient integration of nearly all devices that control the flow of the electric power in the vehicle. It consists of the inverter, the Low voltage DC-DC Converter(LDC), and the Vehicle Control Unit(VCU).

1. Inverter

The inverter converts the battery’s DC into AC, which then is used to control the motor speed. The device is responsible for executing acceleration and deceleration, so it serves a crucial part in maximizing the EV’s drivability.

2. Low voltage DC-DC Converter

The LDC converts the high voltage electricity from the EV’s high-voltage battery into low-voltage(12V) and supplies it to the vehicle’s various electronic systems. All electronic systems in the EV use electricity in low voltage, so the high voltage in the battery must be converted first to be useful for these systems.

3. Vehicle Control Unit

As the control tower of all electric power control systems in the vehicle, The VCU is arguably the most important component of the EPCU. It oversees nearly all the vehicle’s power control mechanisms, including the motor control, regenerative braking control, A/C load management, and power supply for the electronic systems.