The present invention is an electric vehicle power system that uses multiple permanent magnet motorgenerators connected in series or parallel and multiple battery step switching. The crane warning system may include a crane warning device integrated into the ball of the crane. Such a cam self-adaptive automatic speed shift hub can allow the motorengine output power and vehicle running condition always in an optimal matching state, to achieve balance control between the vehicle driving torque and the comprehensive driving resistance. pastoris expression, the efficacy of antibody-CPG2 fusions is enhanced.