Digital Control for a Magnetic Suspension System as an Undergraduate Project

Oguchi, K.; Tomigashi, Yoshio

doi:10.1177/002072099002700305

Cited by 11 publications

(8 citation statements)

References 2 publications

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“…However, the electromagnet possesses a large inductance that leads to the large time constant; besides, the tiny turn-off delay of the full-bridge PWM inverter results in the nonlinear current-duty cycle characteristic around the zero current [10]. Both the large time constant and the current-duty cycle nonlinearity challenge the timely and accurate control on the current through the electromagnet [11].…”

Section: Introductionmentioning

confidence: 99%

Close-Loop Current Control With Current-Sensing Resistor for Electromagnet Driven by Full-Bridge PWM Inverter

2022

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The full-bridge pulse-width-modulation (PWM) inverter is wildly applied to drive the electromagnet and enables advanced technologies, such as the active magnetic bearing (AMB) and the permanent-electro magnetic suspension (PEMS). However, the characteristic relationship between the current through the electromagnet and the duty cycle of the PWM signal has strong nonlinearity around the zero current. Moreover, the electromagnet possesses the induction that results in the time constant and significantly hinders the change of the current. Hence, the open-loop control of the full-bridge PWM inverter cannot accurately or timely tune the current through the electromagnet, especially around the zero current. This work proposes a closed-loop current control approach by three steps: (1) inserting a current-sensing resistor into the middle of the electromagnet, (2) obtaining the current signal with an analog signal-processing circuit, and (3) generating the PWM signal with the bang-bang control circuit. The proposed approach innovatively arranges the current-sensing resistor to take advantage of the symmetry and to minimize the influence from the high-frequency switching of the inverter, so that the measured current signal is comparable to the hall-effect current sensor. The experimental results demonstrate the effectiveness and efficiency of the proposed closed-loop current control approach, though the weak charging capability of the full-bridge PWM inverter still hinders its performance.

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Section: Introductionmentioning

confidence: 99%

Close-Loop Current Control With Current-Sensing Resistor for Electromagnet Driven by Full-Bridge PWM Inverter

2022

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“…The electromagnetic suspension (EMS) technology has become an intensive research topic for the railway transportation in Germany, Japan, and China since 1960s [1]. Apart from the transportation, the maglev technology can also contribute to frictionless bearing [2], vibration isolation for semiconductor industry [3], levitation of metal slabs during manufacture [4], etc.…”

Section: Introductionmentioning

confidence: 99%

“…Due to its nonlinear dynamics, open-loop instability, and simplicity, the single-axis maglev system attracts great attention in terms of the controller design for the undergraduate education [2], [4]- [6]. In 1986, Wong [5] designed an analog maglev control system as an undergraduate project.…”

Section: Introductionmentioning

confidence: 99%

“…Specifically, the optical distance sensor was used to measure the floating distance of the floater, whereas the current in the electromagnet was adjusted by the analog controller accordingly in order to maintain a stable floating distance. In 1989, Oguchi and Tomigashi [2] proposed to incorporate the digital controller for the single-axis maglev system. Based on the digital controller, Cho et al [3],…”

Section: Introductionmentioning

confidence: 99%

“…• Optimizing the iron core of the electromagnet to minimize the magnetic reluctance [2], [6], [8], [9];…”

Section: Introductionmentioning

confidence: 99%

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Numerical Study for Zero-Power Maglev System Inspired by Undergraduate Project Kits

et al. 2020

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The single-axis maglev system is increasingly popular as undergraduate project kits over the recent years. Though it is simple and instructive, the large current in the electromagnet leads to the overheating problem. In order to enhance the energy-saving performance as well as the controller performance, this work compares three geometric modifications on the iron core, the upper permanent magnet and the floating permanent magnet for the maglev system. Four target cases are defined to incorporate the geometric modifications and are solved numerically. Moreover, the numerical solutions are carefully analyzed in terms of the zero-power force, the controller-gain requirement and the saturation current. Consequently, two approaches, i.e., extending the iron core and enlarging the floating magnet, can improve both the zero-power force and the controller-gain requirement and are highly recommended for the zero-power maglev system. On the contrary, though the upper magnet can improve the zero-power force, it significantly raises the controller-gain requirement and accelerates the saturation of the iron core. INDEX TERMS Zero-power maglev, electromagnetic suspension, permanent magnets, numerical simulation. FIGURE 2. Magnetic field (magnitude of the magnetic flux density) around the maglev system of Case 0 with I = 0 A.

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Electromagnetic design of a magnetic suspension system

Hurley¹,

Wölfle²

1997

IEEE Trans. Educ.

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Digital Control for a Magnetic Suspension System as an Undergraduate Project

Cited by 11 publications

References 2 publications

Close-Loop Current Control With Current-Sensing Resistor for Electromagnet Driven by Full-Bridge PWM Inverter

Close-Loop Current Control With Current-Sensing Resistor for Electromagnet Driven by Full-Bridge PWM Inverter

Numerical Study for Zero-Power Maglev System Inspired by Undergraduate Project Kits

Electromagnetic design of a magnetic suspension system

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