Maximum Torque Per Ampere Control Scheme Considering NI HTS Field Coil Behavior for Synchronous Motor With Salient Rotor Core

This paper presents characteristics analysis results of no-insulation (NI) high-temperature superconducting (HTS) motor with saliency according to motor control schemes. In case of a salient motor, for efficient operation, the commonly-known maximum torque per ampere (MTPA) control method is applied to generate the maximum torque at the given absolute value of stator current by using optimal dq-axes current pair (
$i^{r}_{ds}$
,
$i^{r}_{qs}$
). To figure out whether MTPA control is applicable for NI HTS motor, we applied three control schemes referred from conventional motor control method: 1) MTPA with constant parameters; 2) MTPA with variable parameters; and 3)
$i^{r}_{ds}=0$
control. In addition, we proposed MTPA control with exponential function for suppressing radial leak current. The following key transient profiles of 500 kW NI HTS motor according to motor control schemes are presented: 1) dq-axes current; 2) field coil radial leak current; and 3) torque per ampere value.