Regenerative Testing of a Concentrated-Winding Permanent-Magnet Synchronous Machine for Offshore Wind Generation—Part I: Test Concept and Analysis

Abstract

Some high-torque electric machines, such as lowspeed wind generators, may be very difficult to test on load because of the large and expensive mechanical equipment required to load them (motors) or to drive them (generators). In this paper, a full-load regenerative testing methodology is described which does not require any rotating equipment to be coupled to the machine where the rated active power flows in a closed loop between the machine and a suitably connected dual-stage converter. The successful application of this methodology to a 780-kW 14-r/min wind generator prototype is addressed as a study case. Relevant experimental results are reported in a companion paper.

Regenerative Testing of a Concentrated-Winding Permanent-Magnet Synchronous Machine for Offshore Wind Generation—Part II: Test Implementation and Results

“…After describing the physical testing arrangement and equipment, measurement results are reported and compared with theoretical predictions presented in Part I [3]. A good matching between experimental and theoretical results is found.…”

“…In fact, since no brake or prime mover is involved, it is possible to swiftly move from one operating point to the other by only acting on converter controls: To change the speed, the set point of the inverter stage (which is operated in speed control mode [3]) is modified; whereas to change the load, one needs to adjust the reference torque of the rectifier stage, which works in torque control mode [3]. Any operating point can be stably maintained until the required recordings are taken with measurement instrumentation to achieve a full machine performance characterization for all the possible speed and load combinations within design limits.…”

“…This is particularly critical for large electric machinery characterized by high torque and low speed values, such as direct-drive wind generators [2]. In a companion paper [3], a possible solution to the problem is investigated, which is applicable when the machine stator can be split into two independent halves. In the proposed strategy, such winding halves are connected to the two stages of a dual-stage voltage-source converter and are respectively operated as a motor and as a generator.…”

“…The generator winding is split into decoupled three-phase sections to enhance system fault tolerance. Such features make the prototype suitable for implementing the proposed test methodology [3].…”

Sensorless Control for SPMSM With Concentrated Windings Using Multisignal Injection Method

“…In the presence of multiple saliencies, the NSC response is a sum of all saliency responses, as expressed in [17] i s dqc = I cp e j(ω c t−π/2) + i I cni e j(−ω c t+h i θ e +ϕ i −π/2) (6) where i = 1 …”