Liu Heng, Wu Jiale, Zhang Yu
School of Electronic & Information Engineering, Nanjing University of Information &Technology, Nanjing 210044, China.
Micromachines (Basel). 2022 Sep 27;13(10):1612. doi: 10.3390/mi13101612.
There is mutual coupling between amplitude control and frequency tracking control in the closed-loop control of micromechanical resonant sensors, which restricts sensor performance. This paper introduces the principle of an in-plane vibration micromechanical resonant accelerometer with electrostatic stiffness. The characteristic parameters of the microaccelerometer were obtained through computer-aided dimension measurement and an open-loop frequency sweep test of the fabricated microstructure. An accurate numerical model was established based on the accelerometer's dynamic principle and characteristic parameters. We established the double closed-loop driving analysis model of amplitude automatic gain control and resonant frequency phase-locked tracking. We used the averaging method to analyze the steady-state equilibrium point and the stable condition. We concluded that the integral coefficient can improve the startup overshoot when the amplitude automatic gain control loop satisfies the stability condition. Under the constraint of frequency tracking, the sizeable coefficient of the integrator can improve the system instability of the amplitude control loop. The theoretical analysis and simulation were helpful in the design and debugging of the system circuit.
微机械谐振传感器闭环控制中，幅度控制与频率跟踪控制之间存在相互耦合，这限制了传感器性能。本文介绍了一种具有静电刚度的面内振动微机械谐振加速度计的原理。通过计算机辅助尺寸测量和对制造的微结构进行开环频率扫描测试，获得了微加速度计的特征参数。基于加速度计的动力学原理和特征参数，建立了精确的数值模型。我们建立了幅度自动增益控制和谐振频率锁相跟踪的双闭环驱动分析模型。我们用平均法分析了稳态平衡点和稳定条件。我们得出结论，当幅度自动增益控制环满足稳定性条件时，积分系数可以改善启动过冲。在频率跟踪的约束下，积分器的较大系数会加剧幅度控制环的系统不稳定性。理论分析和仿真有助于系统电路的设计和调试。
