Regenerative power amount control system for hybrid vehicle, hybrid vehicle, and regenerative power amount control method for hybrid vehicle

When a road grade (G) of a travelling spot of a hybrid vehicle is a down grade equal to or greater than a set grade threshold value (G1) that has been set in advance, control is performed to calculatea desired regenerative power amount (Et), which is a desired value for the regenerative power amount of a motor generator (31), by adding a corrective regenerative power amount (Ec), which is set asa monotonically increasing function of the magnitude of the down gradient (G) of the travelling spot, to a basic regenerative power amount (Eb), which is a regenerative power amount set on the basis of the travelling status of the hybrid vehicle. 进行如下控制：在混合动力车辆的行驶地点的道路坡度(G)为预先设定的设定坡度阈值(G1)以上的下坡坡度的情况下，在基于混合动力车辆的行驶状态设定的再生电力量即基本再生电力量(Eb)上，加上被设定为行驶地点的下坡坡度(G)的大小的单调增加函数的校正再生电力量(Ec)，来算出电动发电机(31)的再生电力量的目标值即目标再生电力量(Et)。