EV Fundamentals: Overview
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Overview
05.37
| 00:00 | In this section of the course, we're going to be covering the basics of electrical vehicle systems, which is going to ensure that you've got a good understanding of the foundations before embarking on some of the more complex concepts found further into this course. |
| 00:12 | To start, let's take a look at how we got here. |
| 00:15 | Electric vehicles have been around longer than combustion engine powered ones and have a long history of false starts, along with plenty of conspiracy theories. |
| 00:21 | Generally, though, the last 120 or so years of electric vehicle history can be characterized by innovations that were just too far ahead of their time. |
| 00:30 | They had the right idea, but the technology and infrastructure just wasn't there yet. |
| 00:34 | That's all begun to change in the last few years as money has been poured into research and development of energy storage, electric power trains, and now we're at the point where the technology has caught up to those ideas. |
| 00:45 | These days, as I'm sure you're already aware, if you're taking this course, electric vehicles can produce ridiculous amounts of power and they can do that consistently. |
| 00:52 | A lot of this is thanks to the development of lithium ion batteries. |
| 00:55 | Before these came onto the market, traditional lead acid batteries were used. |
| 00:59 | These are heavy, require a ton of maintenance, and can't support very much power due to their inherent and unavoidable inefficiencies found with this type of energy storage. |
| 01:07 | Lithium based batteries, on the other hand, which is what we find in nearly all modern EVs, is incredibly efficient in comparison and requires far less maintenance. |
| 01:15 | It is considerably more expensive to produce, though. |
| 01:19 | At the same time, inverter and motor technologies have come a long way, allowing for massive amounts of power out of surprisingly small and light units. |
| 01:26 | The final big factor that has helped push EVs into the mainstream is the big advances in computing power, which has allowed manufacturers to control and efficiently manage all aspects of the system. |
| 01:36 | One of the most exciting parts of the EV world is that it's constantly evolving. |
| 01:39 | Sure, where we're at now with lithium ion, super efficient motors, and impressive computer control is a huge step forward, but we're still in the very early days and things are constantly improving. |
| 01:49 | The next 10 years in the EV space is going to be characterized by rapid development as the tech leaves adolescents behind and begins to mature. |
| 01:56 | And that means the aftermarket arena is going to get dragged along with it. |
| 01:59 | Now, that we're clear on where the technology is and how it's got there, let's take a broad 30,000 kind of foot view of what a typical modern EV system looks like today and the main components involved. |
| 02:10 | The modern electric drivetrain might seem complex, but once you strip it down to the basics, it's really not too bad and there's not all that much to it. |
| 02:17 | First, we have the largest part of the system, the battery pack. |
| 02:20 | The pack is made up of a number of battery cells connected in series and parallel to produce the voltage and capacity needed. |
| 02:26 | In all EVs, bar some dedicated race cars, the vehicle carries its own onboard charger unit , which takes alternating current or AC power from the wall or charging station and converts that to direct current, aka DC power to charge the high voltage battery. |
| 02:40 | The battery pack is connected to a power distribution module, which contains high voltage switches, also called contactors, that are able to fully isolate the battery voltage from the rest of the vehicle. |
| 02:50 | This module is often housed in the battery pack itself, although sometimes it's separate. |
| 02:54 | The rest of the high voltage components in the vehicle then are connected to this power distribution module. |
| 02:59 | They include the main drive inverter or inverters and those inverters are often directly connected to motors, in , which case the complete assembly is called a drive unit. |
| 03:07 | These inverters are necessary because the battery outputs high current, high voltage DC electricity, and the motor or motors require alternating current at constantly changing voltages. |
| 03:17 | Smaller leads also leave this power distribution module and those are for the high voltage accessories like an air conditioning compressor, heaters, or DC-DC converter, which uses high voltage to charge the 12-volt system. |
| 03:29 | You can think of a DC-DC converter like an alternator. |
| 03:31 | Finally, we have the vehicle control unit, which as its name suggests, manages the entire system. |
| 03:37 | It's mostly the EV's version of a traditional ECU in a combustion-powered vehicle. |
| 03:41 | Of course, this is just a broad overview and each of these items, as well as many other smaller components, will be covered in detail in the coming modules, which is where we'll discuss what their purpose is, how to control them, and how to get the most performance out of them. |
| 03:53 | Before we move on, it's important we wrap our heads around one fundamental and very important difference between internal combustion engines and EVs, the energy they carry on board. |
| 04:02 | Think of it this way. |
| 04:03 | 40 liters of gasoline has the equivalent energy of 356 kWh. |
| 04:08 | A quick little sidebar, kWh is a measure of energy and you can calculate it simply if you know the power and time. |
| 04:13 | We'll discuss more about kW and kWh in the next module, but anyways, back to what we're talking about. |
| 04:18 | When you compare that to a 75 kWh battery in a normal EV, you can see that to start with there's just a lot less energy. |
| 04:25 | So, for that reason, everything needs to be much more efficient. |
| 04:27 | For example, rolling resistance and aerodynamic drag become a massive suck on an otherwise very efficient system. |
| 04:34 | So, while you wouldn't notice an extra 10 horsepower worth of drag on a gasoline-powered vehicle because you're already using so much power just to overcome the internal combustion engine and driveline losses, on an EV, simply changing to wide, low-offset wheels with sticky tires can reduce highway range by as much as 25%. |
| 04:49 | We'll be diving into this topic in its own module very soon, but this concept is an important one that deserves an early mention and it's worth considering whenever discussing EV applications. |
| 04:59 | Let's quickly summarize what we've learned in this module before moving on. |
| 05:02 | Electric-powered vehicles have been around since the mid-19th century, but it's only in the last few years that the technology has caught up with the potential of this propulsion system and allowed it to become feasible in the mainstream. |
| 05:13 | As a general rule, most EV builds contain a battery, an onboard charger, a power distribution center and a DC-DC converter, an inverter or inverters, and motor or motors. |
| 05:23 | A typical EV battery provides considerably less energy than the average tank of gasoline and that means EV systems need to be far more efficient in order to be able to provide comparable performance and range. |
