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The total control range of asymmetric dual three-phase permanent magnet synchronous motor (ADT_PMSM) is divided into three different segments by voltage modulation range and current control dimensions and respective control strategies to get the injected voltages in harmonic subspace for three segments are presented in this paper. The three segments are sinusoidal current modulation region, sinusoidal voltage modulation region and overmodulation region. In sinusoidal current modulation region, resonant controller is adopted in the harmonic subspace to calculate the injected voltages, which can compensate the effect of six-phase voltage source inverter (VSI) dead time for two sets of three-phase windings and takes the pole correction into consideration. In sinusoidal voltage modulation region, open loop control strategy in harmonic subspace is adopted. Overmodulation region 1 and 2 are defined in overmodulation region, and the harmonic voltages which are injected into harmonic subspace to extend the modulation index are calculated based on superposition principle and VSD theory. In order to achieve smooth transition from different regions, a novel space vector pulse width modulation (SVPWM) technique for ADT_PMSM is proposed. The experimental results demonstrate the validity and feasibility of the suggested control approach.

Monitoring critical temperatures in permanent magnet synchronous motors is crucial for improving working reliability. Aiming at resolving the difficulty in online temperature estimation, an accurate and simple five-node lumped parameter thermal network (LPTN) is proposed and the mathematical model of the LPTN is built. Both radial and axial heat transfer paths inside the motor are considered to model the complete thermal circuit. In addition, an innovative parameter identification method based on multiple linear regression is applied to identify the parameters of the LPTN model. The parameters in the state equation are identified instead of the data of the motor, which are strongly dependent on the material and geometrical parameters. Finally, an open-loop estimation scheme based on the state equation and Kalman filter algorithm is adopted to predict the motor temperature online. The model performances are validated by extensive experiments under varying speed and torque conditions in terms of the accuracy and robustness. The results indicate that the temperature estimation error is within the range of ±5 • C in most cases and the proposed model can quickly follow the load variation. Besides, the online temperature estimation scheme and parameter identification method are easy and convenient to implement in an embedded system, which is feasible in automobile applications. Appl. Sci. 2019, 9, 3158 2 of 18 permanent magnet but also changed the transient resistance of the rotor. If the transient resistance of the rotor can be obtained, the temperature of the rotor can be obtained indirectly. Therefore, when the rotor transient impedance was observed under the condition of high-frequency voltage, the rotor temperature information can be obtained by the relationship between the transient resistance and the temperature [12].However, the above-mentioned methods have some drawbacks. FEM has high estimation accuracy, but this method depends on the motor geometry, material properties, and boundary conditions, resulting in complex calculation and longer computing times. Thus, it can only be used for off-line analysis in the motor temperature field. Although the motor rotor temperature estimation algorithm based on rotor flux linkage is simple and easy to conduct, it is only able to predict the rotor temperature. In addition, the estimation accuracy depends on the observation accuracy of the rotor flux linkage, and the change of the flux linkage caused by temperature is not completely linear. Therefore, it is difficult to obtain a more accurate estimation of the rotor temperature. Compared with the method based on the rotor flux observation, the advantage of the approach based on the high frequency injection is that the change in rotor transient impedance is easier to detect. However, the injected high frequency signal may bring additional rotor loss, causing an increase in temperature.A suitable alternative to monitor motor temperature is lumped parameter thermal networks (LPTNs). This thermal network model is a simplifi...

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When a safety-related fault in the motor controller is detected, the torque output of the motor cannot be effectively shut off in time and an overcurrent occurs at the moment of switching. The advantages and disadvantages of the open circuit and active short-circuit methods are analyzed. Combining the advantages of these two operations, this paper proposes a new mixed voltage modulation method. It introduces a voltage modulation ratio that represents the duty cycle of the open circuit operation during a PWM period. This ratio is first set to a fixed value and gradually reduced to zero. The inverter is switched at a mixed operation and finally remains in the active short-circuit mode. The current can be quickly converged by a freewheeling diode of open circuit. After switching to active circuit, the brake torque is safety. The effectiveness of this shutoff method was verified by simulations and experiments. It shows that current fluctuations are suppressed and the torque output is also within a safety range. In addition, this shutoff method does not require any additional sensor information and is simple to implement.

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The torque output accuracy of the IPMSM in electric vehicles using a state of the art MTPA strategy highly depends on the accuracy of machine parameters, thus, a torque estimation method is necessary for the safety of the vehicle. In this paper, a torque estimation method based on flux estimator with a modified low pass filter is presented. Moreover, by taking into account the non-ideal characteristic of the inverter, the torque estimation accuracy is improved significantly. The effectiveness of the proposed method is demonstrated through MATLAB/Simulink simulation and experiment.