Abstract: A variable flux reluctance machine（VFRM）control system based on the excitation current control

of a single leg was proposed. Compared with the VFRM control system based on the H-bridge which controlling the

excitation current，fewer switch devices were used，in which the cost of the inverter was reduced while also the loss

of the inverter reducing. In the VFRM control system based on single-leg excitation current control，the excitation

current passed through the neutral point of the armature windings and the fourth leg，the optimal distribution of

excitation current and q axis current by Lagrange multiplier method was obtained. Finally，the loss and efficiency of

the VFRM control system of single leg excitation current control and H-bridge excitation control were compared.

The results show that，under the same torque and speed conditions，compared with the VFRM control system based on H-bridge excitation control，inverter losses are reduced by 50%，and efficiency is increased by 3.3%.

      Key words: variable flux reluctance machine（VFRM）；single leg excitation current control；optimal current

distribution；inverter losses