Huaishu Li

Analytical design and modeling of a transverse flux permanent magnet machine

A transverse flux permanent magnet machine (TFPM) is ideally suited to high torque and lower speed applications such us the generation of electricity by wind-energy and the electric propulsion of naval ships. This paper introduces the basic principles and construction of the transverse flux permanent magnet machine, and illustrates the flux paths of two typical TFPM topologies. The analytical approach to dimensioning an application-specific 20 kW two-phase TFPM with C-form stator cores is provided. The equivalent circuit is given and the important features of TFPM are outlined with the help of solving the equivalent circuit. The instantaneous torque equation, flux linkage equation and voltage equation are also proposed, so that the mathematical model is established.

Commutation torque ripple reduction in BLDC motor using PWM_ON_PWM mode

The paper analyzes the steady commutation process of the BLDC motor using PWM mode, confirms the commutation time to keep non-commutation phase current amplitude constant during commutation period by way of PWM in the period to implement the compensation control to eliminate commutation torque ripple under both low speed and high speed operation, investigates the effect by PWM mode on a three-phase six-state 120° turn-on BLDC motor, and presents torque ripple compensation control in PWM ON PWM mode, which can not only entirely eliminate torque ripple resulted from the current emerging in the turn-off phase during non-commutation period but also compensate torque ripple caused by the commutation current during commutation period.

A novel discontinuous space vector PWM control for multiphase inverter

PWM control of multi-phase inverter is one of the key technologies in the ships electrical propulsion. In this paper, a novel discontinuous space vector PWM (DSVPWM) method of multiphase inverter is proposed by arranging the two zero vectors skillfully. Comparing with the continuous space vector PWM (CSVPWM) method the DSVPWM use only one zero vector in one switching period, so the switching loss is only four fifths of the CSVPWM. However, the output target line voltages of DSVPWM are still sine wave, the harmonic performance is excelled that of traditional SVPWM (TSVPWM) therefore. Several classic DSVPWM realization methods are given, and the operation characteristic, adapted load types and total harmonic distortion rate of them are analyzed and simulated

Power system load-frequency controller design based on discrete variable structure control theory

This paper proposes a discrete-time variable structure reaching law with attenuating quasi-sliding mode band, and gives the variable condition of quasi-sliding mode band. The proposed reaching law is applied to design a load-frequency controller for a power system. The simulation results show that the controller can not only eliminate system chattering, but also improve dynamic performance of the system effectively and make the system possess a strong robustness property.

FEM analysis and simulation of multi-phase BLDC motor

This paper introduces a time stepping finite element analysis (FEA) model coupling circuit-field and movement used in analyzing multi-phase permanent magnet brushless DC (BLDC) motors, presents the element analysis about the coupling problem of control circuit and field, adopts the interpolation moving boundary method to solve rotation problem of the rotor, and employs the above model to analyze the performance of a multi-phase BLDC motor. The simulation results are very close to the experimental results, which verifies the validity of the proposed method.

A novel starting control for sensorless three-phase permanent-magnet brushless DC motor

The paper analyses the SVPWM control schema of three-phase inverter employing 120° switch-on mode, proposes a starting control method combined the SVPWM control schema with current regulation adopting the two-point comparator for a sensorless three-phase permanent-magnet (PM) brushless DC (BLDC) motor, establishes the simulation model of the starting control system in Matlab / Simlink environment, and implements the proposed starting control system through digital simulation. Simulation results verify that the proposed starting method can not only control the starting current effectively but also improve the open-loop starting performance of the BLDC motor.

FEM simulation and harmonic torque analysis of six-phase BLDC motor

This paper introduces a time stepping finite element analysis (FEA) model coupling circuit-field and movement used in analyzing multi-phase permanent magnet brushless DC (BLDC) motors, presents the element analysis about the coupling problem of control circuit and field, adopts the interpolation moving boundary method to solve rotation problem of the rotor, and employs the above model to analyze the performance of a multi-phase BLDC motor. Simulation and experiment research on the key factors producing the torque—back EMF and current waveform are performed, and the harmonic torques of six-phase BLDC motor are analyzed and deduced. Finally the conclusion is obtained that the sinusoidal harmonic torques can be decreased or removed by reducing the lagging angles of current.

Analytical calculation of inductance parameter of tangentially magnetized PM motor based on basic air-gap magnetic field

Because permanent magnets (PMs) exist in the d-axis magnetic circuit of tangentially magnetized PM synchronous motor, its magnetic field and calculation of inductance parameter is different from common synchronous motor. A new analytic method of calculation of PM motor inductance parameter is proposed in this paper, which is based on basic air gap magnetic field and is more convenient than the conventional method using air gap magnetic permeability. The concept of basic air gap magnetic field and how to calculate its magnetic induction are introduced, the analytic calculation procedure of this method is given and the analytic calculation formula is deduced. The inductance parameters of a 350kW twelve-phase tangential magnetized PM propulsion motor are calculated by the analytic method and Finite Element Method (FEM) and the results have shown that the two cases agree well, so the validity and accuracy of the presented method are verified.

Analysis and simulation of high power multi-phase BLDC motor

A trapezoidal waveform is usually used instead of the actual back EMF in numerous research literatures on simulation of brushless DC (BLDC) motors, which causes the errors to the simulation and calculation of the motor. This paper adopts the flux linkage changing rate matrixes of the permanent magnets to calculate the back EMF, establishes the mathematical model of a 30 kW six-phase BLDC motor based on it, simulates the dynamic performance of the motor, and verifies the validity by experimental results.

Study on variable frequency operation and starting performance of single-phase permanent-magnet synchronous motor fed by three-phase inverter

This paper discusses the balanced operation condition for single-phase permanent-magnet synchronous motor (SPPM) at the variable frequency applications and introduces a control method that adopts the three-phase inverter to adjust speed of the motor based on the analysis of operation mechanism of SPPM. A simulation shows that a good performance can be achieved in wide frequency ranges by using the control method. Moreover, the paper investigates the variable frequency starting performance of the SPPM fed by the three-phase inverter based on the starting torques analysis, presents the simplified equivalent circuit for the analysis of variable frequency starting process, verifies the method of the simplified equivalent circuit, whose calculation result is consistent with the result derived from the quasi-steady state method, deduces the voltage compensation method to ensure a constant maximum asynchronous torque during the variable frequency starting process, and verifies the validity of the proposed method by the quasi-steady state method to compute the asynchronous torque and the magnet braking torque of the SPPM employing the voltage compensation method during the variable frequency starting process.