Controllers for brushless motors: E-bikes require high initial torque and therefore models that use brushless motors typically have Hall sensor commutation for speed and angle measurement. An electronic controller provides assistance as a function of the sensor inputs, the vehicle speed and the required force. The controllers generally allow input by means of potentiometer or Hall Effect twist grip (or thumb-operated lever throttle), closed-loop speed control for precise speed regulation, protection logic for over-voltage, over-current and thermal protection. Bikes with a pedal assist function typically have a disc on the crank shaft featuring a ring of magnets coupled with a Hall sensor giving rise to a series of pulses, the frequency of which is proportional to pedaling speed. The controller uses pulse width modulation to regulate the power to the motor. Sometimes support is provided for regenerative braking but infrequent braking and the low mass of bicycles limits recovered energy. An implementation is described in an application note for a 200 W, 24 V Brushless DC (BLDC) motor.
Electric bikes and E-bike kits (bikes with electric conversion kits) are part of a wide range of Light Electric Vehicles (LEVs) that provide convenient local transportation. Generally designed for one person and small cargo capacity, electric bike range, speed, and cost are moderate. For most of us, the majority of our trips are less than 20 miles - within the range of most e-bikes considering the latest advances in affordable lithium batteries. Clean, quiet, and efficient LEVs offer the advantages of an extra car without the burdens.
The environmental credentials of e-bikes, and electric / human powered hybrids generally, have led some municipal authorities to use them, such as Little Rock, Arkansas with their Wavecrest electric power-assisted bicycles or Cloverdale, California police with Zap e-bikes. China’s e-bike manufacturers, such as Xinri, are now partnering with universities in a bid to improve their technology in line with international environmental standards, backed by the Chinese government who is keen to improve the export potential of the Chinese manufactured e-bikes.
Come for the price, stay for the awesome. The August Live! LS is one of the lower-cost e-bikes you’ll find. What it lacks is gadgets it makes up for in flare and retains just what you need. You won't find a digital display or integrated lights, Instead you get trendy, chopper-style handlebars, a sweet paint job, and a 250 watt motor that is more than capable of tackling steep hills without a second thought. That said, this bike just begs to be ridden on casual cruises down the boardwalk or bike path.
For many bikes, battery range is more important that total power (because they're all pretty powerful). You want a bike that delivers a range long enough for your rides at the power levels you want. Most e-bikes will have three to five levels of assist kicking in anywhere from 25 percent of you pedal power to 200 percent boost. Consider how fast the battery takes to recharge, especially if you'll be using your bike for long commutes.