A drive system, comprising: a control unit configured to receive a load variation signal indicating a vehicle load is to be or being changed and generate a traction torque in response to the load variation signal and a vehicle command torque; one or more load detection sensors configured to detect a load variation condition of the vehicle load and generate the load variation signal to the control unit according to the load variation condition; and a traction device coupled to the control unit and configured to drive a vehicle according to the traction torque, wherein the control unit is configured to: generate a load variation torque in response to the load variation signal and generate the traction torque based on the load variation torque and the vehicle command torque; decrease the vehicle command torque when the load variation signal indicates the vehicle load decreases and to increase the vehicle command torque when the load variation signal indicates the vehicle load increases; characterised in that the control unit is further configured to: determine a torque range having a lower limit value and an upper limit value in response to the load variation signal by extending a pre-set range when the load variation torque has a positive value and by narrowing the pre-set range when the load variation torque has a negative value; and limit the traction torque within the torque range. a control unit configured to receive a load variation signal indicating a vehicle load is to be or being changed and generate a traction torque in response to the load variation signal and a vehicle command torque; one or more load detection sensors configured to detect a load variation condition of the vehicle load and generate the load variation signal to the control unit according to the load variation condition; and a traction device coupled to the control unit and configured to drive a vehicle according to the traction torque, wherein the control unit is configured to: generate a load variation torque in response to the load variation signal and generate the traction torque based on the load variation torque and the vehicle command torque; decrease the vehicle command torque when the load variation signal indicates the vehicle load decreases and to increase the vehicle command torque when the load variation signal indicates the vehicle load increases; generate a load variation torque in response to the load variation signal and generate the traction torque based on the load variation torque and the vehicle command torque; decrease the vehicle command torque when the load variation signal indicates the vehicle load decreases and to increase the vehicle command torque when the load variation signal indicates the vehicle load increases; characterised in that the control unit is further configured to: determine a torque range having a lower limit value and an upper limit value in response to the load variation signal by extending a pre-set range when the load variation torque has a positive value and by narrowing the pre-set range when the load variation torque has a negative value; and limit the traction torque within the torque range. determine a torque range having a lower limit value and an upper limit value in response to the load variation signal by extending a pre-set range when the load variation torque has a positive value and by narrowing the pre-set range when the load variation torque has a negative value; and limit the traction torque within the torque range.