Nannan Zhao

Harbin Institute of Technology | HIT · Department of Electrical Engineering

To extend the lifetime, improve the power density and reduce the system cost, the film capacitor is applied to replace the large-volume electrolytic capacitor in motor drives. As the dc-link voltage fluctuates periodically, the rotor position estimation error and operation stability are necessary to be concerned in the position sensorless control m...

The power density can be improved and the system cost can be saved in the reduced dc-link capacitance motor drive system. The line inductance can also be diminished to reduce the system volume further. In previous research works, the active damping control methods mainly concentrated on the drive system equipped with a larger line inductor. In this...

As the dc-link capacitance decreases obviously, the dc-link voltage fluctuates severely in the electrolytic capacitorless permanent magnet synchronous motor (PMSM) drives for compressor applications. The control performance of the compressor deteriorates, and the dc-link may suffer from the fault of overvoltage. In this article, an acceleration ext...

In electrolytic capacitorless permanent magnet synchronous motor (PMSM) drives, the DC-link voltage will fluctuate in a wide range due to the use of slim film capacitor. When the flux-weakening current is lower than $-\psi_{\mathrm{f}}/L_{\mathrm{d}}$ during the high speed operation, the flux-weakening control loop will transform to a positive fe...

Permanent magnet synchronous motors (PMSMs) have been applied widely due to their advantages in terms of high power density, high torque-to-inertia ratio and high efficiency. Recently, they have been adopted more popularly in the gearless elevators of modern buildings.

After years of application and investigation, although the compensation strategies using weight transducers can meet the requirement of elevator operation, there are still limitations: (1) Load information transmitted via the communication board may be interfered because of the long cable and complicated electromagnetic environment. (2) As for weig...

Gearless traction systems have become the trend of modern elevators because it is easy to implement the non-machine room application. Several key issues of gearless traction systems should be concerned in the control strategy: (1) riding comfort during startup; (2) stability and security during the operation period; (3) high efficiency and strong r...

Various advanced control strategies have been proposed to optimize the speed-control performance and enhance the robustness against unknown disturbance. However, the weight-transducerless control for anti-rollback of elevator car should consider special requirements of riding comfort.

This chapter proposes a novel low-cost control strategy of gearless traction permanent magnet synchronous machine for direct-drive elevator applications. It can improve robustness of the weight-sensorless traction machine system installed an ordinary incremental encoder. In order to improve the riding comfort for the passengers during the brake rel...

As a vertical lifting vehicle, the elevator has become an important building equipment in high-rise buildings and public places. With the development of computer technology and power electronics technology, the modern elevator has become a typical mechatronics product. The traction elevator is the most widely used in modern elevator, and its core c...

Permanent magnet synchronous motors (PMSMs) have gained wide attention in traction-drive applications thanks to the high torque-weight ratio. Due to the rapid development of the traction drives with PMSMs, PMSM traction-drive system is widely researched both at home and at abroad. Traction drives with PMSMs have to meet with specific requirements....

To improve the starting performance of permanent magnet traction machine without a weight transducer in gearless elevator, an adaptive starting torque compensation strategy is proposed in this chapter. The dynamic model of the direct-drive elevator traction system considering the rope elasticity, the brake releasing and the friction torque is estab...

Generally, the electrical motor is divided into three types, the DC motor, the induction motor (IM) and the synchronous motor. Among these types of motors, the PMSM has been widely developed in the industry and household applications for its high power density, high efficiency, high power factor and excellent control performance.

The extra acoustic noise caused by the high–frequency (HF) signal injection imposes restrictions on its extensive applications for sensorless synchronous reluctance motor (SynRM) drives. To attenuate the undesired acoustic noise further, a hybrid pseudorandom signal injection scheme is proposed in this paper. The hybrid pseudorandom signal injectio...

In the voltage source inverter applications, inverter nonlinearities would affect the parameter identification process in many ways. Hence, this article proposes an offline identification method for resistance and dq -axis inductance surface by considering the inverter nonlinearity characteristics. A variable amplitude square-wave injection (VASI...

In order to extend the lifetime and save the system cost, the film capacitor is applied in the DC-link of IPMSM drives. Many active damping control methods have been carried out to improve the drive system stability, which needs the accurate value of the DC-link film capacitor. In this letter, an online DC-link capacitance estimation method is inve...

Accurate rotor position estimation is important to ensure the high-performance operation of position sensorless permanent magnet synchronous motor (PMSM) drives. To suppress the estimated rotor position offset error (RPOE) caused by the cross-saturation effect and the system digital time delay, etc. for high-frequency signal injection (HFSI) based...

This paper proposes a position and speed detection method based on the cross-decoupling network filtering (CDNF) method combined with phase-locked loop (PLL). This method is used to enhance the detection precision of position and reduce the speed fluctuation at low-speed operation for gearless traction motor drives with an ordinary-resolution encod...

Beat phenomenon is an important issue for the practical application of electrolytic capacitorless motor drives. In this study, the characteristics of stator current harmonics caused by the voltage sampling delay are analyzed. Further, the beat phenomenon generated from the interaction between the harmonics and the fundamental currents is investigat...

The harmonic of the grid current is an important issue in the reduced DC-link capacitance motor drive system. An input inductor has been applied in the grid side to improve the grid current quality.

Overmodulation strategies can be used to increase the DC-link voltage utilization rate, which enhances the output torque ability. In practice, the motor can operate beyond linear modulation region, even enter the six-step operation by implementing effective overmodulation strategies.

Reduced DC-link capacitance permanent magnet synchronous motor (PMSM) drives have many advantages, such as longer lifetime, reduced cost and higher power density. However, due to the DC-link voltage fluctuation, the DC-link voltage utilization rate and the torque ripples are two major issues in flux-weakening operation region.

The beat phenomenon is an important issue in the reduced DC-link capacitance motor drive system and other power electronic converters, including the resonant switching converter, the inverter with low switching frequency, the distributed power systems, and the matrix converter.

Permanent magenent synchronous machine (PMSM) has been widely developed in the industry and household applications for its high-power density, high efficiency, high power factor, and excellent control performance.

This book focuses on the advanced control of reduced dc-link capacitance AC motor drives. Compared with the conventional AC motor drives, the reduced DC-link capacitance motor drives could reduce the cost, enhance the reliability and improve the power density. The control strategies proposed in this book are verified by experimental results, which...

The instability of the drive system is caused by the interaction of the LC resonance and the constant power load (CPL), hence the active damping methods have been applied to damp the resonance and stabilize the drive system.

The DC-link may suffer from overvoltage during motor transient process due to the use of slim film capacitors in the diode rectifier front end.

Large volume electrolytic capacitors are usually utilized at the DC-link of PMSM drives to buffer and store energy, which can stabilize the DC-link voltage and supply power for the inverter. Meanwhile, the power factor correction (PFC) circuit is necessary to improve the power factor and reduce the total harmonic distortion (THD) of the grid input...

Because of the time-sharing sampling logic, the three-phase currents reconstructed by single DC-link shunt present significant errors in the permanent magnet synchronous motor (PMSM) drives. A traceback-prediction current correction method for sampled currents is proposed in this paper to eliminate the reconstruction errors. According to the analys...

Gallium nitride high electron mobility transistor (GaN HEMT) has fast switching speed and low threshold voltage, which could result in a severe false triggering voltage pulse at the synchronous freewheeling transistor in bridge-leg circuit when the control transistor turns on . To suppress the crosstalk phenomenon, this article proposes an analyt...

The remarkable inductance nonlinearities of synchronous reluctance motors (SynRMs) could result in operating-point-dependent high frequency (HF) current responses, and more HF losses with audible noises with conventional constant amplitude high frequency signal injection (HFSI) methods applied. This paper proposes an adaptive pseudo-random high fre...

Motor parameter identification methods mostly depend on the voltage equations, which leads to the unsatisfactory identification effect at low current and low speed operation. This paper proposes a parameter identification method based on the high frequency (HF) equivalent impedance model of permanent magnet synchronous motor (PMSM) with HF signal i...

Synchronous reluctance machines (SynRMs) have drawn increasing attention in recent years owing to their advantages such as low cost, simple structure, ease of manufacture, and high robustness. The main obstacle to the promotion of SynRMs is severe parameter nonlinearity, which deteriorates drive performance. Sensorless control methods for SynRMs ar...

Torque smoothness is a strict requirement for synchronous reluctance motor (SynRM) industrial applications. The speed fluctuations induced by the high frequency and low frequency torque ripples deteriorate the drive performance. To suppress high frequency torque ripples chronically omitted by conventional high frequency signals injection methods at...

Initial rotor position detection is important to ensure the start-up operation of sensorless permanent magnet synchronous motor (PMSM) drives. In order to suppress the annoying noise caused by the additional signal injection during the detection process in the existing methods, a pseudorandom high-frequency (HF) square-wave voltage injection based...

In encoderless field-oriented-controlled permanent magnet synchronous motor (PMSM) drives, current sensors may malfunction in harsh working environments. A current sensor fault-tolerant control (FTC) strategy with single sliding mode observer (SMO) is proposed in this paper, which can achieve both phase current error construction and rotor position...

The asymmetrical rotating (dq-) frame control leads to frequency coupling dynamics, which tends to bring in harmonic instability. In this paper, based on the established complex signal impedance model, the influence of the grid impedance and the frequency coupling on system stability is analyzed. For the phase-locked loop (PLL) mainly affects the q...

Permanent magnet synchronous motor (PMSM) drives equipped with slim film capacitors have many advantages, including longer lifetime, smaller volume and lower cost. However, improving the DC-link voltage utilization rate by typical overmodulation strategy will cause the distortion of the stator voltage and current due to the DC-link voltage fluctuat...

Three-phase input diode rectifier interior permanent magnet synchronous motor (IPMSM) drives with small-volume film capacitors have many merits, such as high reliability, high power density and low cost. However, in regenerative braking mode, the DC-link may suffer from overvoltage due to the application of slim film capacitors. In this paper, a no...

The instability issue is an important concern in the reduced dc-link capacitance motor drive system, which is caused by the interaction of the LC resonance and the negative impedance of the constant power load (CPL). Harmonics of the grid current also need to be concerned to meet the requirement of the application standards. In this paper, the im...

Beat phenomenon is an important concern in the reduced DC-link capacitance motor drive system. In previous researches, the topic is mainly concentrated on the beat phenomenon caused by the interaction of the fluctuated DC-link voltage and the motor phase voltage. In this paper, another form of the beat phenomenon generated by the fluctuated DC-link...

Reduced DC-link capacitance interior permanent magnet synchronous motor (IPMSM) drives have many advantages, such as longer lifetime, reduced cost and higher power density. However, due to the DC-link voltage fluctuation, the DC-link voltage utilization rate and the torque ripple are two major issues in flux-weakening operation region. It is import...

The LC resonance between the line inductor and the DC-link film capacitor is an important concern in the reduced DC-link capacitance interior permanent magnet synchronous motor (IPMSM) drive system. In this paper, an active damping method based on the virtual damping resistor is applied to suppress the LC resonance and improve the drive system stab...

High-frequency (HF) signal injection methods have been widely employed in the sensorless control of interior permanent magnet synchronous motor (IPMSM) drives from zero to low speed. However, the control performance will be deteriorated severely when the motor subjects to the disturbance. To cope with this issue, an enhanced linear active disturban...

The conventional high frequency (HF) voltage injection method can accurately extract rotor position for interior permanent magnet synchronous motor (IPMSM) drives at low and zero speed ranges. However, the fixed injection frequency will produce a loud audible noise. To solve this problem, a pseudo-random phase-switching fixed-frequency (PRPSFF) sig...

High frequency signal injection methods have been widely used in sensorless control of permanent magnet synchronous motor (PMSM) drives. However, the acoustic noise and torque ripples caused by the injected high frequency signal limit the application of the methods. To avoid these drawbacks, this paper proposes a position estimation method that com...

In order to mitigate harmonics of the grid input current, passive filters are applied widely in the power electric systems. The LC resonance and the negative input-impedance are important concerns in the reduced DC-link capacitance motor drive system. In this paper, an active damping control method is proposed to suppress the LC resonance by the di...

High-frequency (HF) signal injection has been widely used in the sensorless control of interior permanent magnet synchronous motor (IPMSM) drives for zero- and low-speed operation. However, the audible noise pollution caused by induced HF current has restricted its application. To solve this problem, a low frequency (LF) pulse voltage injection sch...

This paper presents a novel filtering method for speed measurements to improve the low-speed performance of the direct-drive permanent magnet traction machines for elevators. Based on the theory of nonlinear tracking differentiator (NTD), this method, which can act as a high performance filter of a raw speed signal, obtains a more accurate speed fe...

DC-link electrolytic capacitor critically affects the lifetime of the motor drive system. This paper proposes an inverter power control strategy based on DC-link voltage regulation for the electrolytic capacitor-less interior permanent magnet synchronous motor (IPMSM) drive system. The DC-link electrolytic capacitor is replaced by a small film capa...

To diminish the harmonic ripple in the rotor position estimation error for sensorless interior permanent magnet synchronous motor (IPMSM) drives, an adaptive linear neural (ADALINE)-network-based filter with a quadrature phase-locked loop (PLL) position observer is proposed. A fundamental model-based sliding-mode observer is used to obtain back ele...

The permanent magnet traction machine has become the tendency of modern gearless elevators, because of small volume, high efficiency, and good dynamics. However, the direct-drive elevator car will slide during the electromagnetic brake releasing at elevator startup, if the speed controller cannot generate a suitable electromagnetic torque to trace...