Motor drive unit for an in-wheel motor, comprising a housing and one or more capacitors and solid state switching devices arranged within the housing, the housing comprising: a lower compartment comprising a bottom plate, sidewalls which extend from the bottom plate, and end sides at the transverse ends of the sidewalls and bottom plate, wherein the bottom plate is provided with cooling channels for receiving a liquid coolant; a separation plate covering the lower compartment, wherein the separation plate is in thermal contact with the sidewalls and with the one or more capacitors; an upper compartment having a top plate and sidewalls, wherein the capacitors are arranged in the upper compartment between the top plate and the separation plate, wherein the upper compartment, the separation plate, and the lower compartment together enclose the one or more capacitors and the solid state switching devices; characterized in that the separation plate makes direct contact with the sidewalls or makes contact with the sidewalls via a thermal paste or grease applied between the separation plate and the sidewalls; wherein the motor drive unit further comprises DC bus bars (151,152) which are electrically connected to the one or more capacitors, wherein the DC bus bars (151, 152) are mechanically fixed to the separation plate and thermally conductively connected thereto; and wherein the solid state switching devices are arranged in the lower compartment between the bottom plate and the separation plate and in thermal contact with the bottom plate, wherein the capacitors are arranged at a side of the separation plate that faces away from the lower compartment and are mounted on and substantially supported by the DC bus bars (151, 152). a lower compartment comprising a bottom plate, sidewalls which extend from the bottom plate, and end sides at the transverse ends of the sidewalls and bottom plate, wherein the bottom plate is provided with cooling channels for receiving a liquid coolant; a separation plate covering the lower compartment, wherein the separation plate is in thermal contact with the sidewalls and with the one or more capacitors; an upper compartment having a top plate and sidewalls, wherein the capacitors are arranged in the upper compartment between the top plate and the separation plate, wherein the upper compartment, the separation plate, and the lower compartment together enclose the one or more capacitors and the solid state switching devices; characterized in that the separation plate makes direct contact with the sidewalls or makes contact with the sidewalls via a thermal paste or grease applied between the separation plate and the sidewalls; wherein the motor drive unit further comprises DC bus bars (151,152) which are electrically connected to the one or more capacitors, wherein the DC bus bars (151, 152) are mechanically fixed to the separation plate and thermally conductively connected thereto; and wherein the solid state switching devices are arranged in the lower compartment between the bottom plate and the separation plate and in thermal contact with the bottom plate, wherein the capacitors are arranged at a side of the separation plate that faces away from the lower compartment and are mounted on and substantially supported by the DC bus bars (151, 152).