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How to improve the pressure compensation control accuracy required in the synthesis of artificial diamond？
Release time：
2025-09-29
source：
The pressure control accuracy of the HPHT Hydraulic Cubic Press directly affects the quality of synthetic diamond. To enhance the quality and yield of synthesized diamond, the critical factor is ensuring that the pressure gradient in the reaction chamber is minimized and remains stable, placing the diamond growth space within the ideal pressure range.
Required Accuracy Specification
In the pressure maintaining (compensation) stage of the synthesis process, the system must timely compensate for pressure loss. The required pressure compensation control precision specified by the process is:
The pressure fluctuation must be no greater than 0.1 MPa under the working pressure condition of 50 to 110 MPa.
Implementation and Achieved Accuracy
The improved system addresses the low precision and hydraulic shocks caused by the frequent starting and stopping of traditional three-phase asynchronous motors by utilizing a pump control pressure compensation system based on a Permanent Magnet Synchronous Motor (PMSM). The PMSM, acting as the drive motor for the auxiliary pump, allows for continuous pressure compensation at low speed.
The PMSM system, which employs vector control, has advantages such as good dynamic response and high closed-loop control accuracy.
The designed closed-loop pressure servo system (consisting of the PMSM, vector control process, and pump-controlled cylinder) was simulated using PID control in the MATLAB/Simulink environment.
The simulation results confirmed that the system achieves the required precision:
1. The system pressure stabilizes after 0.6 seconds.
2. During the pressure maintaining process, the pressure fluctuation stabilizes within 0.1 MPa.
The conclusion of the system design confirms that the PMSM-controlled HPHT Hydraulic Cubic Press compensation system realizes continuous pressure compensation at low speed, maintaining the pressure fluctuation at $\le \pm 0.1$ MPa. During the compensation stage, the PMSM operates continuously at low speed, typically between 20 and 100 r/min.
This high-precision control, realized through continuous low-speed operation rather than frequent starting and stopping, effectively improves the reliability of the pressure control system and reduces production and maintenance costs.
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