基于FPGA的飞轮磁轴承一体化控制系统设计

Integrated control system design of magnetic bearings for flywheel based on FPGA

为了精简磁悬浮飞轮控制系统体积和功耗,介绍一种四轴飞轮磁轴承一体化控制系统及其现场可编程门阵列(FPGA)实现。将磁轴承控制器和功率放大器整合到一起,用单片FPGA实现含不平衡补偿的转子位移控制、电流控制以及三电平脉宽调制(PWM)算法。采用分时复用浮点运算IP核的方式实现控制算法。为均衡运算速度和资源消耗,提出一种A/D转换器精确度和浮点IP核数据精确度的选择方法。提出一种增量式算法,仅用乘加单元和查找表即可实现不平衡补偿算法中的三角函数值的在线计算。介绍三电平PWM的FPGA实现方法以及转子位移信号的自动标定方法。实验结果表明,一体化控制器可以达到0～7 000 r/min转速范围内飞轮径向位移不超过保护间隙10%的控制效果。四轴飞轮磁轴承控制任务可以用单片FPGA以小于20万逻辑门的资源消耗实现。

In order to reduce the volume and power consumption of the control system for magnetically suspended flywheel, an integrated controller for 4-axis flywheel magnetic bearings and its field programmable gate array （FPGA） implementation were proposed. The integrated controller optimizes the signal conditioning, the position controller and the power amplifier as a whole, using a single FPGA chip to implement the rotor position control with unbalance compensation, current control, and the three-level PWM algorithms. The calculation tasks were implemented by means of reusing floating-point IP cores in timepieces. In order to balance the calculation speed and logic resources consumption, a method to select the precision of the A/D converter and the word length of the floating-point IP cores in the control algorithms was proposed. An incremental algorithm was proposed to calculate the trigonometric function online, using only muhipliers, accumulators, and lookup tables. The FPGA solution of the three -level PWM and an auto calibration method for the rotor position signals were proposed. Experiment results show that the maximum radial position error at the rotation speeds of 0 -7 000 r/min is less than 10% of the protection gap. The conclusion is that all the control task for 4-axis flywheel magnetic bearings can be implemented on a single FPGA with less than 0.2 million equivalent logic gates.