Application Cases

Experiment Name: Levitation Experiment of Position Control System

Test Purpose: The electrostatic levitation position control system is the foundation and core of electrostatic levitation material processing technology. There have been no reports in China that this core technology has been fully mastered. Based on the analysis of the working principles of each component of the position control system, this paper designs and implements an electrostatic levitation position control system, achieving stable position control of levitated samples.

Testing Equipment: High-voltage amplifier, levitation electrodes, laser power supply, etc.

Figure 1: Electrostatic Levitation Position Control System

Experiment Process:

The vertical position control system experimental setup consists of a 650nm semiconductor laser light source, a three-dimensional control board, a high-voltage amplifier, levitation electrodes, etc. The upper part of Figure 2 shows the PSD, signal amplification circuit, levitation electrodes, laser light source, and high-voltage amplifier, while the lower part shows the control board and its power supply.

Figure 2: Experimental Setup of the Vertical Position Control System

The levitated object is a graphite-coated ceramic sphere with a diameter of approximately 3mm. When the system is powered on, the graphite-coated ceramic sphere is immediately levitated and gradually stabilizes at the center position between the upper and lower electrodes, as shown in Figure 3.

Figure 3: Levitation Situation

After amplification, the levitation accuracy can be observed to be within ±0.05mm, as shown in Figure 4 for the levitation situation within 0.7 seconds.

Figure 4: Levitation Accuracy Measurement

Figure 5 shows the Z-direction position signal and control voltage signal output by the PSD observed by the oscilloscope during the levitation startup process. Channel 1 (CH1) is the position signal, and Channel 2 (CH2) is the control voltage signal (the ratio of the actual value to the observed value is 2000:1). It can be seen that the control voltage required at the beginning of levitation is approximately 7000V, while the levitation control voltage for the sphere at the center position between the two electrodes is only about 4000V.

Figure 5: Oscilloscope Observation of Levitation Startup Process

Experimental Results:

The position control accuracy of the vertical position control system using a 650nm light source is ±0.05mm, which meets the design requirement of the electrostatic levitation position control system in this paper (±0.25mm). In the future, using a higher-performance 808nm laser for position measurement will undoubtedly achieve higher control accuracy in the vertical direction. Additionally, horizontal position control does not need to overcome gravity. The center position is the equilibrium point of the horizontal electric field force on the levitated sample. The main purpose of horizontal position control is to prevent external disturbances, so higher accuracy can be achieved in horizontal position control.

Voltage Amplifier Recommendation: ATA-7050

Figure: Specification Parameters of the ATA-7050 High-Voltage Amplifier

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