A generator comprising at least one thermal stage having magnetocaloric elements (2) arranged around an axis and a magnetic arrangement (3) supported by a drive shaft (30) that rotates about the axis to subject the elements to a variation in magnetic field. The generator comprises pistons (70) to force heat transfer fluid through the elements with the pistons being driven in reciprocating translation within chambers (73) by at least one cam (71) that is rotationally driven the drive shaft (30). The generator comprises a forced circulation unit (8a) having planet gears (80) arranged around the central axis, supported by the body (72) of the generator and meshing with an inner crown gear (81) integral with the cam (71). Each gear (80) forms a gear pump that mixes the heat transfer fluid and places the fluid in forced circulation in the tanks (74) and the chambers (73).