Single sensor current control of permanent magnet synchronous motor using field programmable gate array

An innovative current control scheme for a permanent magnet synchronous motor using a single current sensor placed at a low potential, in the DC return line of the inverter is proposed. The feedback mechanism employs a digital asymptotic sinusoidal curve-fitting observer implemented in a single field programmable gate array chip. The observer, activated by firing pulses, reconstructs the three-phase feedback signals. The asymptotic observer does not require the parameters of the motor or the load and it is robust under dynamic conditions. The development of the algorithm, implementation and experimental verification of the proposed control scheme are presented in detail.