(Slide 1) Hi. My name is ( your name), and I'd like to talk to you today about electric vehicle technology.

(Slide 2) First, some definition. EV stands for Electric Vehicle. Let's take a look at what's out there now. First, EV's are all over the place. Airport service vehicles, golf carts, and forklifts comprise a vast population of off-road EV's. These have been around for many years, and the technology is fairly well developed. But what about on the road? Are there roadgoing EV's today? - Yes. Not only that, but there is technology available to the general public that will allow you and me to build and operate a practical, fun-to-drive EV today. Let's look at some of the on-road EV's that are out there.

(Slide 3) OEM EV's. GM EV1

(Slide 4) Solectria Force

(Slide 5) Corbin Sparrow (That'll get attention). Also available is the Ford Electric Ranger.

(Slide 6) Hobbyist EV's. The hobbyist is unwilling to wait for an industry that never seems to move. There are 1000's of vehicles, although this is still a drop in the bucket for the USA. Most are conversions of ICE powered cars, so you'd probably never know.

So what does it take to build one of these conversions (besides batteries)?

(Slide 9) System components. Basically, it takes takes a motor, a motor controller, a battery charger, a DC/DC converter, a heater, Instrumentation, contactor(s), and electrical safety devices. We'll look a little at each of these.

(Slide 10) Motors. The motors you'll hear about have a deceptively low HP rating. This is because motor's ratings are for continuous HP, and produce many times that for short time periods. ICE engines can only produce their rated power at specific throttle, fuel flow, temperature, RPM, etc. "Test Bench" conditions. And then only for a short time. The performance characteristics of the electric motor better match real-world driving conditions.

  • Most OEM's use Std. AC induction motors
  • Why - AC var, speed drive technology familiar, used widely in industry, low risk
  • Torque - fixed throughout speed range. Results in seemingly low torque at low speeds, with high performance at speed.
  • Requires a high voltage system (240-350 VDC)
  • Requires a complicated electronics package

    (Slide 11) Most hobbyists use brushed DC motors

  • 100% torque is available at 0 RPM - serious acceleration
  • Series wound usually used (some shunt wounds are used)
  • Why - Choice of hobbyists because of price, good performance, and availability. Also proven in industrial vehicles. Easy to control, and controllers are available.
  • Torque - proportional to amperage the controller can put through the motor.
  • Brush changes required every 10,000 hours or so. (3-5 years) Can be done at any motor shop, cheap.

    (Slide 12) here is a cutaway of the most popular motor for bobbyist conversions, the Advanced DC 9" motor.

    (Slide 13) Controllers In general, the more volts you have, the higher top speed you have, and the more amps the controller can push through the motor, the more torque the motor will generate.

  • AC - Derivative of industrial technology, but needs inverter added to convert DC from batteries to AC.
  • Mfrs. - AC Propulsion, Siemens, Hughes, etc. Big names, Big Prices
  • Failure mode - lose a phase, lower performance or loss of power
  • DC - SCR (early, simple)
  • Most modern DC motor controllers use PWM technology.
  • Simple technology compared to AC propulsion, and controllers are usually smaller.
  • Mfrs. - Curtis, Auburn, DCP, EVCL
  • Later ones developed for on-road EV's, Curtis is the grandfather of them all, all technology similar.
  • Failure mode can be full on (cascade or domino failure of power transistors) - that's what the clutch is forů

    (Slide 14) This is what an Auburn controller looks like.

    (Slide 15) Chargers - OEM uses weird hookups like GM's inductive paddle charger and the AVCON connector. The hobbyist wants to just use what everybody already has - a 120 or 240 VAC plug-in.

  • Chargers are available that provide everything from simple voltage regulated charging to computer-controlled 3-stage charging. New totally sealed AGM batteries require specific charging algorithms
  • Mfrs. - K & W, Bycan, Lester, Russco, Zivan

    (Slide 16) DC-DC Converters - For safety reasons, you want to keep your car's 12V system totally isolated from the high voltage components. So how do you keep your 12V battery recharged? The solution is a DC/DC converter.

  • Steps pack voltage down to 13.5 VDC using PWM technology to recharge accessory battery (like an electronic alternator)

    (Slide 17) Heaters - Just like in the little ceramic heaters you can buy at the hardware store. Resistive loads don't care whether the source is AC or DC.

    (Slide 18) Here is what a typical core and frame look like.

  • DC rated switches and relays required.

    (Slide 19) Instrumentation

    (Slide 20) Contactors - BIG relays

    (Slide 21) Safety

  • Inertia switches - same function as in gas car, except they cut power to the contactors instead of fuel pumps.
  • AGM Batteries - no spillage.
  • Service disconnects - BIG circuit breakers.
  • Electrical Isolation - traction pack is kept isolated from the chassis - car is still 12V.
  • The National Electric DRAG RACING association has a required load rating of 8G's that the battery restraint systems must endure.
  • Emergency disconnects - same as used in industrial carts and forklifts.
  • Primary fuses

    (Slide 22) Performance - Acceleration and speed for conversions is about the same as gas vehicles. Depending on the design, it ranges from "economy to muscle car". The DC motors are great for drag racing. The current electric drag racing record is 8.801 seconds in the 1/4 mile by "Current Eleiminator".

    (Slide 23) This purpose built vehicle, the tZero, is probably the fastest street-legal EV available.

    (Slide 24) Range - Somewhat dependent on speed and whether you have a lead foot, but typically 30-60 miles. Over 100 miles easily achievable with a purposeful design or with advanced (non-lead-acid) batteries that are not available to the public yet. This is a great match for today's driving habits. Example - commuting. Use an ICE car for long trips.

    (Slide 25) This EV pickup gets over 120 miles range

    (Slide 26) With plain old flooded lead-acid golf cart batteries!

    (Slide 27) Emissions - Common claim is that pollution is only moved. Point taken, but overall efficiency jump plus scrubbing of power plant emissions reduces overall emissions significantly.

    (Slide 28)

    (Slide 29) - This is just an overview of the components available and what has been done with them. These are available, just not widely known.

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