Reactive power compensation technology for the inductive sensors of magnetic bearings

doi:10.19799/j.cnki.2095-4239.2021.0249

Abstract

Abstract:

Inductive displacement sensors are widely used to measure magnetic bearing rotor position because of their high sensitivity, good linearity, and low cost. The sensitivity of inductive sensors is typically positively correlated with power consumption. Power improvement is necessary to obtain high sensitivity, particularly for applying the constant flux axial inductive displacement sensor, which requires high power amplifiers. Accordingly, finding a way to reduce the total power of the sensor without changing its sensitivity will help reduce hardware costs. In this paper, a reactive power compensation technology for the inductive sensors of magnetic bearings is proposed. By paralleling appropriate capacitors at both ends of the excitation coils of the sensor, the study was able to realize a parallel resonance state, thereby greatly reducing the reactive power of the entire circuit. The experimental results showed that, without affecting the sensors' sensitivity, the power amplifier's apparent output power could be reduced by more than 70% at 20～40 kHz. This reduced the maximum output power requirement of the power amplifiers. Following that, the influence of compensation point selection on the compensation effect was tested. The results showed that the compensation point selection demand was very low. Finally, the influence of compensation capacitance precision on the compensation effect was evaluated. The results indicated that reactive compensation did not require high compensation capacitance precision, and the 10% precision capacitor could achieve a satisfactory power optimization effect. Parallel reactive power compensation could significantly reduce the total apparent power of the sensors and the cost of power amplifiers. This technology presents practical value in the field of engineering.

Key words: magnetic bearing, inductive sensor, reactive power compensation

CLC Number:

TP 212.1

Chunyi WANG, Kai ZHANG, Yang XU. Reactive power compensation technology for the inductive sensors of magnetic bearings[J]. Energy Storage Science and Technology, 2021, 10(5): 1650-1655.

Figures/Tables 10

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频率/kHz	补偿电容/nF	补偿前干路电流/A	补偿前视在功率/W	补偿后干路电流/A	补偿后视在功率/W	功率降低比例/%
20	1466	4.44	15.76	0.84	2.94	81
30	669	3.64	15.11	0.80	3.32	78
40	409	3.20	15.04	0.84	3.99	73

频率/kHz	补偿电容/nF	补偿前灵敏度/(mV·μm^-1)	补偿后灵敏度/(mV·μm^-1)	灵敏度变化率/%
20	1466	1.807	1.834	1.5
30	669	2.257	2.286	1.3
40	409	2.450	2.477	1.1

轴向位移/mm	最佳补偿电容/nF	实际补偿电容/nF
0	331	333
3.50	362	364
5.00	389	386
6.50	411	409
9.00	428	427

补偿电容/nF	相对最佳补偿电容的电容值误差/%	平衡位置处干路电流有效值/A	相比未补偿时干路电流减少比例/%	传感器工作范围内干路电流有效值变化/A
0	—	1.240	0	1.180～1.294
333	-14.4	0.249	80	0.227～0.276
364	-6.4	0.233	81	0.233～0.242
386	-0.8	0.251	80	0.239～0.273
409	+5.1	0.300	76	0.274～0.336
427	+9.8	0.336	73	0.304～0.379

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