Direct current carrying type II superconductors present a dynamic resistance when subjected to an oscillating magnetic field perpendicular to the current direction. If a superconductor is under a homogeneous field with high magnitude, the dynamic resistance value is nearly independent of transport current. Hoffmann and coworkers [C. Hoffmann, D. Pooke, and A. D. Caplin, IEEE Trans. Appl. Supercond. 21, 1628 (2011)] discovered, however, flux pumping effect when a superconducting tape is under an inhomogeneous field orthogonal to the tape surface generated by rotating magnets. Following their work, we report the whole Voltage-Ampere (V-I) curves of an YBCO coated conductor under permanent magnets rotating with different frequencies and directions. We discovered that the two curves under opposite rotating directions differ from each other constantly when the transport current is less than the critical current, whereas the difference gradually reduces after the transport current exceeds the critical value. We also find that for different field frequencies, the difference between the two curves decreases faster with lower field frequency. The result indicates that the transport loss is dependent on the relative direction of the transport current and field travelling, which is distinct from traditional dynamic resistance model. The work may be instructive for the design of superconducting motors. It is well known that type II superconductors carrying a direct current present a resistance when they are under a perpendicular oscillating magnetic field. 1-10 Theoretical analysis 1,3,7,8 and experimental results 1-7,10 have shown that this resistance is due to flux flow caused by the interaction between the transport current and the applied field, and it is defined as dynamic resistance. The dynamic resistance value is proportional to the applied field magnitude and frequency if the superconductor in a homogeneous field, and it is nearly independent of transport current if the field magnitude is high. 7 Hoffmann and coworkers 11 discovered flux pumping effect when a piece of superconducting stator connecting to a superconducting load was subjected to inhomogeneous magnetic fields orthogonal to the tape surface generated by rotating permanent magnets. Researchers from VUW 12 pointed out that dynamic resistance is the main limiting factor of saturation current in the flux pump. Concerning the open circuit voltage, they proposed a geometrical explanation considering screening current. 13 All these existing researches 11-13 focus on the flux pumping effect, where the superconducting stator generates dc power. In this letter, we extend the research to the V-I characteristics of YBCO Coated Conductor (CC) under rotating permanent magnets. The experimental system is shown in Fig. 1(a), which is similar to rotating magnets flux pumps 11-15. Eight Neodymium 52 magnets with a diameter of 20mm are uniformly mounted on a round copper disc. The outer diameter of the disc is about 81mm. All magnets were mounted with their north poles fa...

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