# A dual-mode dual-stator hybrid rotor synchronous and vernier machine for variable speed applications

## TL;DR

This paper introduces a new type of electric motor for washing machines that can efficiently switch between low-speed washing and high-speed drying.

## Contribution

The paper introduces a novel dual-mode dual-stator hybrid rotor machine for variable-speed applications.

## Key findings

- The machine achieves 20 Nm torque at 530 rpm in vernier mode with 77% efficiency.
- It provides 5.9 Nm torque at 1200 rpm in synchronous mode with 94.7% efficiency.
- The design is compact, magnet-light, and energy-efficient compared to existing motors.

## Abstract

This paper presents the design and electromagnetic performance evaluation of a Dual-Mode Dual-Stator Hybrid-Rotor Synchronous and Vernier Machine (DMDS-HRSVM) developed for automatic washing-machine applications. The washing machine operates in two distinct cycles: a low-speed, high-torque wash cycle and a high-speed, energy-efficient spin-dry cycle. The proposed configuration combines two stators with a single hybrid rotor, allowing the machine to operate in both brushless vernier and synchronous modes within one compact structure Machines outer stator is made of 24 slots, each with either a 4 pole main winding 2 pole auxiliary winding, which combine together to create fundamental and subharmonic magnetomotive force (MMF) components in the air gap. These elements cause voltages in a 2pole rotor excitation winding by the airgap the induced AC is rectified by a rotating rectifier to the 44pole field winding which allows the rotor to run brushless. The inner stator features a 4-pole layout that interacts with permanent magnets on the rotor’s inner surface to realize synchronous operation. Finite-element analysis (FEA) confirms strong electromagnetic performance, yielding a torque of 20 Nm at 530 rpm in the vernier mode and 5.9 Nm at 1200 rpm in the synchronous mode, with corresponding efficiencies of 77% and 94.7%. These results demonstrate the DMDS-HRSVM as a compact, magnet-light, and energy-efficient alternative to existing BL-WRVM and DMDS-WRSM designs for variable-speed domestic drives.