Electric motors used in vehicles

v

ok,They are different in some way, and same in other way!

p The electric motor is called brushless dc motor, whereas old electric train use brush dc motor for theri driver. The front ac motor powered by a bettery as you said, because it has a set of converter which can change dc into 3 phs pulse current to drive the motor. of cause you can also use a pure dc motor as driver without the converter. the motor generally structured by permanent magnet. In the electric train. the ac line was change into DC to drive the dc motor. Thats their different.

what we call DC traction motors have the best starting torque, but are current hogs at zero. If you have ever ridden one and heard the arcs as the power is swicthed you would understand. This is OK in a train that runs on an infinite mains power source.

When you have a car running on batteries, you do not want these huge current surges as they drive the battery into very inefficient regimes of irreversibility. What you want is high torque from an AC motor that you adjust the speed and torque as needed. This is done by multi phase Pulse Width Modulation (PWM). These motors are wound with a higher than three phases, 6-10 and the controller gives each phase a high intensity short pulse and observes armature rotation and then it pulses the next winding and so on. SInce the pulse are short they current limit in inductive reactance and are not seen as a dead short to the battery = higher efficiency. Sinec the repeat they give a reasonable starting torque and usually the light vehicle starts to move and the controller adjusts pulses and phases to give the acceleratyion needed. Often people start slow to max the efficiency. So you end up with the longest possible battery life and reasonable starting torque. Not as good as a DC series motor, but the battery lasts far longeer on a charge

What is PWM ? how is the control done?

PWM works by increasing and reducing the width of a train of power pulses, so as to regulate the speed of the motor. It lends itself readily to the use of feedback control: in the space between the pulses, the back-EMF of the motor can be used as a speed measurement, and a control algorithm can be used to alter the width of the next few pulses so as to maintain the desired speed. A readily-available example of PWM control is the battery-electric drill, where the speed of the drill is related to the position of the trigger, despite changes in load experienced by the drill bit.

Go to the

http://www.rasertech.com/applications.html

Site. This is the real deal.

In addition to what others have said, you should also be aware that although electric motors used in cars are often AC, that does not have to be the case. In fact, 10 years ago, virtually all electric cars/golfcarts used DC motors.

The drive to get lighter batteries and greater endurance along with advances in controller technology is the driving force in replacing DC series motors with AC types.

In simple situations you might opt for DC, just a battery and a motor and a regulator switch

Yes

In fact, the www.ngcmarine.com products use dc motors. the thoosa 9000 rg 's tech. sheets are interesting. www.solomonindustries.com 's motors are also dc. Torque is the name of the game with heavy vehicles. Batteries are dc, so less lost in invertering the current to ac. Ac motor has its advantages ... as mentionned. The key will be to create good efficient light batteries.

Magnets could be a solution with a potential regen. capacities stored in the magnets. imagine a wankle (rotary) engine with (could be gasoline) fossil and electric propulsion. the key is to create a mini particle accelerator (particle being a shaft or a ring) that would need a little push for a great controled power surge. the advantage is that you can recharge (magnetise) the peripheral or core magnets. This would mean a cassette reload or a plug in.

For now one can use an electric dc motor with regen. and agm or gel deep cycle bat.. Other batteries will show up so replacements will be possible. The voltage is also a dilema. The more voltage the better efficiency, but the batterie pack will be tremendous, batteries being 12v or 6v. Security is a factor too. At 220-240 v you dont want to make a mistake ... like you dont want to use your cellphone or smoke filling your gas tank... the new solar photovoltaic polymer films are promising, deceleration recharge capabilities and possibly wind (mill or sail) recharge for near coast (beach) public transits. The sailecon blvd ... cruise with your own cool sail beach and road buggy ... we cruise with our cats, kites and windsurf.

A related question:

Every new home is required to have an external power master switch, so that emergency responders can safely cut electrical power in case of a fire. Electric cars carry enough charge to be a significant hazard and to warrent similar protections. Of course, a downside is pranksters, or worse, being able to disable a vehicle. My question: what are the options for cutting the main source of power in case of an accident/fire in an electric car?

Diesel-engined buses in the UK have a fuel shut-off valve, accessible from the outside by someone other than the driver in the event of an incident...

What has happened to the sodium-sulphur battery, which had such a bright future predicted for it when conceived around 30 years ago?

Characteristics:

• High energy-to-weight index
• High power-to-weight index
• Became a battery only above about 300degC
• Needs care in containing the contents in the event of a vehicle incident.

They seem to have disappeared...

http://www.worldenergy.org/wec-geis/publications/default/tech_papers/17th_congress/3_3_05.asp

History.....

Who remember "troley-bus" a street car on regular wheels w/tires and dc power from overhead lines? Some are still running on EU streets.

What about old race track hybrid cars that used DC series moror to get 150 mph in 4 sec? Then the rest was on gas engine?

Swiss buses with huge inertia wheels to drive up & down hills?

An old joke: An electric engineer wanted to kill his friends who already had electric cars with DC motors. He installed an AC motor in his car and drove 100 miles for just 25 cents but the cable costed him $ 89,232.88.

Was that the first time anybody built the electric car without a battery?

v

Some AC motor can also be good torque. we call this sort of motor as torque motor. the motor can work at zero rotation wothout burning winding.

more large power dc motor introduce multi-phase rectifier from 3 phase power like 12 phase, even more high to raise effeciency.I think car is smaller than bus and train and so brushless dc motor suit to them. They work in SPWM way mostly. if you use brush motor you neednt use the converter ( or inverter) This is different.