Electric bicycle and control method thereof

1. A chainless electric bicycle comprising:

a chainless wheel driven only by an electric motor in response to rotation of pedals;

a direction sensor to sense a rotation direction of the pedals;

a pedal load controller to adjust a load applied to the pedals to create for a rider a sensation of a drive chain when the rider is pedaling; and

an electronic control unit configured to apply the load through the pedal load controller to the pedals when the sensed rotation direction is a normal direction and to release the load applied to the pedals through the pedal load controller when the sensed rotation direction is a reverse direction,

wherein the pedal load controller comprises:

a generator to generate AC power in accordance with driving of the pedals;

a rectifier to rectify the AC power generated from the generator into DC power;

a smoothing circuit to charge the DC power output from the rectifier so as to smooth the output power; and

a switch connected in series between the generator and a battery to be charged with the power smoothed by the smoothing circuit,

wherein the electronic control unit performs a pulse width modulation (PWM) control to turn on or off the switch when the sensed rotation direction of the pedals is the normal direction to charge the battery with the power generated from the generator and turns off the switch when the sensed rotation direction of the pedals is the reverse direction to open output terminals of the generator.

2. The chainless electric bicycle according to claim 1 , further comprising:

a speed sensor to sense a speed of the electric bicycle,

wherein under a condition that the speed sensed by the speed sensor is equal to or lower than a predetermined speed, the electronic control unit applies the load to the pedals through the pedal load controller when the sensed rotation direction is the normal direction, while releasing the load applied to the pedals by the pedal load controller when the sensed rotation direction is the reverse direction.

3. A control method of a chainless electric bicycle having a chainless wheel which is driven only by an electric motor in response to rotation of pedals, the method comprising:

sensing a rotation direction of the pedals;

applying a load to the pedals to create for a rider a sensation of a drive chain when the rider is pedaling and the sensed rotation direction is a normal direction by performing a pulse width modulation (PWM) control to turn on or off a switch such that charged with power generated from a generator; and

releasing the load applied to the pedals when the sensed rotation direction is a reverse direction by turning off the switch such that output terminals of the generator are open,

wherein the bicycle comprises a direction sensor to sense the rotation direction the pedals, a pedal load controller including the generator to generate AC power in accordance with driving of the pedals, a rectifier to rectify the AC power generated from the into DC power, a smoothing circuit to charge the DC power output from the rectifier so as to smooth the output power, and the switch connected in series between the generator and the battery to be charged with the output power smoothed by the smoothing circuit to adjust the load applied to the pedals to create for the rider the sensation of the drive chain when the rider pedals, and an electronic control unit configured to apply the load through the pedal load controller to the pedals when the sensed rotation direction is the normal direction and to release the load applied to the pedals through the pedal load controller when the sensed rotation direction is the reverse direction.

4. The control method according to claim 3 , further comprising:

sensing a speed of the electric bicycle; and

applying the load to the pedals when the sensed rotation direction is a normal direction, under a condition that the sensed speed is equal to or lower than a predetermined speed while releasing the load applied to the pedals by the pedal load controller when the sensed rotation direction is the reverse direction.