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This article proposes a pseudo-random high-frequency triangular-wave current signal injection (PR-HFTCI) based sensorless control scheme for synchronous reluctance motor (SynRM) drives at zero-low speed domain to suppress the high-frequency (HF) loss and the HF audible noise which are introduced by the significant nonlinearities of SynRMs and the traditional constant amplitude HF square-wave voltage injection method. The pseudo-random HF triangular-wave current signal with random frequency and random phase is injected to eliminate the discrete spectrum of the current power spectra density (PSD) and the corresponding current PSD analysis is performed to evaluate it. In addition, the HF component amplitude of the d-axis voltage reference can be adjusted adaptively with the variation of load to maintain the HF current amplitude constant, it is easy to implement and does not require any extra regulator and signal processing. Hence, the HF loss and the HF torque ripple can be effectively reduced under the heavy load. Finally, the effectiveness and the correctness of the proposed PR-HFTCI based sensorless control scheme are validated with experiments on a 1.5-kW SynRM drive platform. [ABSTRACT FROM AUTHOR]

This study proposes a sensorless flux adaption direct torque and flux control (DTFC) for an interior permanent magnet synchronous motor (IPMSM), in which an maximum torque per ampere (MTPA) based on active flux and an adaptive second-order sliding mode observer (SOSMO) are adopted. Flux adaption DTFC is proposed based on the existing active flux concept. Thus, the stator current amplitude can be minimised in both steady state and transient state. Furthermore, to realise the sensorless control of the IPMSM, an adaptive SOSMO is proposed. Compared with constant gains SOSMO, the gains of the adaptive SOSMO can be adjusted adaptively with the motor speed changing. Then, the precision of position estimation is enhanced effectively in a wide speed range. Numerical simulations and experiments with a 60 kW IPMSM are implemented. In addition, the results validate the capability of the proposed sensorless flux adaption DTFC scheme. [ABSTRACT FROM AUTHOR]

The scheme based on direct torque and flux control (DTFC) as well as active flux is a good choice for the interior permanent magnet synchronous motor (IPMSM) sensorless control. The precision of the stator flux observation is essential for this scheme. However, the performance of traditional observers like pure integrator and the low-pass filter (LPF) is severely deteriorated by disturbances, especially dc offset. Recently, a sliding-mode stator flux observer (SMFO) was proposed to reduce the dc offset in the estimated stator flux. However, it cannot eliminate the dc offset totally and will cause the chattering problem. To solve these problems, a novel super-twisting sliding-mode stator flux observer (STSMFO) is proposed in this paper. Compared with SMFO, STSMFO can reduce the chattering and fully eliminate the dc offset without any amplitude and phase compensation. Then, the precision of the stator flux and rotor position can be greatly improved over a wide speed region. The detailed mathematical analysis has been given for comparing it with another three traditional observers. The numerical simulations and experimental testing with an IPMSM drive platform have been implemented to verify the capability of the proposed sensorless scheme. [ABSTRACT FROM AUTHOR]