A Novel Intermittent High-Frequency Square-Wave Injection of IPMSM Sensorless Drive for Eliminating Inverter Dead time Nonlinear Effect

2021 ◽  
Author(s):  
Yiming Wang ◽  
Qiwei Xu ◽  
Guanya Zhang ◽  
Yun Yang
Keyword(s):  
Nonlinear Effect ◽  
High Frequency ◽  
Dead Time ◽  
Square Wave ◽  
Sensorless Drive

scholarly journals Delay compensation based controller for rotary electrohydraulic servo system

2021 ◽  
Author(s):  
Zakarya Omar ◽  
Xingsong Wang ◽  
Khalid Hussain ◽  
Mingxing Yang
Keyword(s):  
High Frequency ◽  
Dead Time ◽  
Sliding Mode ◽  
Servo System ◽  
Smith Predictor ◽  
Delay Compensation ◽  
Mechanical Parts ◽  
System Output ◽  
Electrohydraulic Servo System ◽  
The Stability

AbstractThe typical power-assisted hip exoskeleton utilizes rotary electrohydraulic actuator to carry out strength augmentation required by many tasks such as running, lifting loads and climbing up. Nevertheless, it is difficult to precisely control it due to the inherent nonlinearity and the large dead time occurring in the output. The presence of large dead time fires undesired fluctuation in the system output. Furthermore, the risk of damaging the mechanical parts of the actuator increases as these high-frequency underdamped oscillations surpass the natural frequency of the system. In addition, system closed-loop performance is degraded and the stability of the system is unenviably affected. In this work, a Sliding Mode Controller enhanced by a Smith predictor (SMC-SP) scheme that counts for the output delay and the inherent parameter nonlinearities is presented. SMC is utilized for its robustness against the uncertainty and nonlinearity of the servo system parameters whereas the Smith predictor alleviates the dead time of the system’s states. Experimental results show smoother response of the proposed scheme regardless of the amount of the existing dead time. The response trajectories of the proposed SMC-SP versus other control methods were compared for a different predefined dead time.

High Frequency ZVS GaN-Inverter with Adaptive Dead Time

2021 ◽  
Author(s):  
Benedikt Kohlhepp ◽  
Thomas Foerster ◽  
Thomas Duerbaum
Keyword(s):  
High Frequency ◽  
Dead Time

scholarly journals Effect of Air Gap on Electrical Tree in Epoxy Resin Under High Frequency Bipolar Square-Wave Voltage

Materials ◽  
2020 ◽  
Vol 13 (24) ◽  
pp. 5722
Author(s):  
Shihang Wang ◽  
Chuang Zhang ◽  
Hang Fu ◽  
Jiao Xiang ◽  
Jianying Li ◽  
...  
Keyword(s):  
Epoxy Resin ◽  
High Frequency ◽  
Air Gap ◽  
Heat Accumulation ◽  
Air Gaps ◽  
Square Wave ◽  
Electrical Tree ◽  
Electrical Trees ◽  
Voltage Frequency ◽  
Tree Characteristics

Insulation fails quickly under high-frequency AC high voltage, especially bipolar square-wave voltage with a high dV/dt. It is of great significance to study the failure mechanism of epoxy casting insulation under such kind of voltage. In this paper, pin-plane epoxy casting insulation samples with air gaps were prepared, and the relation between the electrical trees under the high frequency bipolar square-wave voltage and the air gap conditions and voltage frequencies (1~20 kHz) were studied. Results indicated that, with the presence of air gaps, the electrical trees were bush-type and had a relatively slow growth rate, which was different from the fast-growing branch-type trees in the samples without air gap. The electrical tree characteristics related with the size of air gap and voltage frequency were also studied. The electrical tree grew faster under higher voltage frequency or with a smaller air gap. Results proved that discharge introduced a lot of defects for the surface layer of the epoxy resin samples and hence induced the possibility of multi-directional expansion of electrical trees. In addition, the resulting heat accumulation and unique charge transport synergistically affected the electrical tree characteristics under the high frequency bipolar square-wave voltage.

scholarly journals Comparative Evaluation of a Permanent Magnet Machine Saliency-Based Drive with Sine-Wave and Square-Wave Voltage Injection

Energies ◽  
2018 ◽  
Vol 11 (9) ◽  
pp. 2189 ◽  
Author(s):  
Jyun-You Chen ◽  
Shih-Chin Yang ◽  
Kai-Hsiang Tu
Keyword(s):  
Permanent Magnet ◽  
Pulse Width Modulation ◽  
Dead Time ◽  
Sine Wave ◽  
Position Estimation ◽  
Feedback Signal ◽  
Estimation Errors ◽  
Square Wave ◽  
Position Errors ◽  
Voltage Signal

This paper improves a permanent magnet (PM) machine saliency-based drive performance based on the selection of a suitable injection signal. For the saliency-based position estimation, a persistently high-frequency (HF) voltage signal is injected to obtain a measurable spatial saliency feedback signal. The injection signal can be sine-wave or square-wave alternating current (AC) voltage manipulated by the inverter’s pulse width modulation (PWM). Due to the PWM dead-time effect, these HF voltage injection signals might be distorted, leading to secondary harmonics on the saliency signal. In addition, the flux saturation in machine rotors also results in other saliency harmonics. These nonlinear attributes cause position estimation errors on saliency-based drives. In this paper, two different voltage signals are analyzed to find a suited voltage which is less sensitive to these nonlinear attributes. Considering the inverter dead-time, a sine-wave voltage signal reduces its influence on the saliency signal. By contrast, the flux saturation causes the same amount of error on two injection signals. Analytical equations are developed to investigate position errors caused by the dead-time and flux saturation. An interior PM machine with the saliency ratio of 1.41 is tested for the experimental verification.

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