Electric bicycle and control method thereof

1. A control method of an electric bicycle for driving the electric bicycle by rotating a motor using electrical energy accumulated in a battery, comprising:

receiving an acceleration command value input by a user to accelerate the electric bicycle upon starting the electric bicycle from a stopped state;

comparing the input acceleration command value with a reference value;

determining sudden start or normal start based on a result of the comparison, the normal start being determined if the input acceleration command value is lower than the reference value;

outputting a motor control signal depending on whether the sudden or the normal start is determined, a time taken for rotation speed of the motor to reach a target speed corresponding to the acceleration command value being fixed by the motor control signal such that the time is equal to a reference time if the normal start is determined while the time is greater than the reference time if the sudden start is determined such that a speed gradient of the motor is reduced when the input acceleration command value is greater than the reference value; and

sensing a throttle opening degree varied by the user and a pedal torque to rotate pedals varied by the user,

wherein the input acceleration command value is determined based on the throttle opening degree or the pedal torque.

2. The control method according to claim 1 , wherein the time taken for the rotation speed of the motor to reach the target speed is still further increased when the input acceleration command value is still further greater than the reference value.

3. The control method according to claim 1 , wherein the target speed corresponds to the input acceleration command value, and the time taken for the rotation speed of the motor to reach the target speed corresponding to the input acceleration command value is still further increased when the input acceleration command value is still further greater than the reference value.

4. An electric bicycle comprising:

a generator to generate electric energy in accordance with rotation of pedals;

a battery to accumulate the electric energy generated from the generator;

a motor to be driven by the electric energy accumulated by the battery;

a motor driver to drive the motor;

an input unit to receive an acceleration command value input by a user; and

an electronic control unit to compare the acceleration command value input through the input unit with a reference value when the electric bicycle starts from a stopped state, and to control the motor driver such that a time taken for a rotation speed of the motor to reach a target speed is increased when the input acceleration command value is greater than the reference value,

wherein the input unit comprises:

a throttle opening degree sensor to sense a throttle opening degree of a throttle provided at a handle of the electric bicycle and a pedal torque sensor to sense a pedal torque to rotate pedals generated when the user pedals;

a comparator to compare the input acceleration command value with the reference value;

a sudden start determiner to determine, based on a result of the comparison, whether sudden start or normal start will occur, the sudden start being determined if the input acceleration command value is greater than the reference value and the normal start being determined if the input acceleration command value is lower than the reference value; and

a sudden start preventer to output a motor control signal to the motor driver depending on whether the sudden or normal start is determined by the sudden start determiner, the sudden start preventer being configured to fix the time taken for the rotation speed of the motor to reach the target speed such that the time is equal to a reference time if the normal start is determined while the time is greater than the reference time if the sudden start is determined such that a speed gradient of the motor is reduced when the input acceleration command value is greater than the reference value.

5. The electric bicycle according to claim 4 , wherein the electronic control unit controls the motor driver such that the time taken for the rotation speed of the motor to reach the target speed is still further increased when the input acceleration command value is still further greater than the reference value.