无刷直流电机(brushless DC motor,BLDCM)换相时刻关断相电流的续流造成电机端电压的畸变。当采用无位置传感器反电动势过零检测法时,端电压波形畸变会使位置检测信号相位超前,偏离最佳换相时刻,重载条件下甚至会造成换相失败,制约了反...无刷直流电机(brushless DC motor,BLDCM)换相时刻关断相电流的续流造成电机端电压的畸变。当采用无位置传感器反电动势过零检测法时,端电压波形畸变会使位置检测信号相位超前,偏离最佳换相时刻,重载条件下甚至会造成换相失败,制约了反电动势检测法的电机功率应用范围。因此,该文针对电流续流影响端电压的机理加以分析,建立了电流续流产生相位超前的数学模型,并给出了位置检测信号相位超前的补偿算法。仿真和实验结果表明,经过补偿后的位置检测接近最佳换相时刻,重载条件下仍可正常运行。展开更多
As a third generation light source, Shanghai Synchrotron Radiation Facility (SSRF) has up to 140 beam position monitors (BPM) installed to monitor the beam dynamics on its storage ring. Once the operation mode is chos...As a third generation light source, Shanghai Synchrotron Radiation Facility (SSRF) has up to 140 beam position monitors (BPM) installed to monitor the beam dynamics on its storage ring. Once the operation mode is chosen, the betatron functions are determined. Since the sinusoidal betatron oscillation is the dominant component of the transverse motion, these BPMs can be used to measure the motion to get the betatron functions. Three methods are compared to calculate the phase advance among the BPMs in this paper, aiming to find one or more feasible ways to check the beam optics in SSRF. Some experiments have also been made to verify the practicality of the phase information.展开更多
The period length is usually much larger than the cavity effective length in a low energy superconducting linac.The long drifts between cavities will not only decrease the acceptance of the linac, but also lead to pos...The period length is usually much larger than the cavity effective length in a low energy superconducting linac.The long drifts between cavities will not only decrease the acceptance of the linac, but also lead to possible instability. The linac will be more sensitive to mismatch and other perturbations. From the longitudinal motion equation, the function which describes the parametric resonance is deduced and the relation between the instability region and the cavity filling factor is discussed. It indicates that if the zero current phase advance per period is kept below 90°, instability driven by parametric resonance will never occur. The space charge effect will enhance the instability, so that a stricter limitation on the phase advance per cell is required. From the numerical simulation results for two different schemes of Injector-Ⅰ of the C-ADS driver linac, one can find that even with just three cells in the unstable region, significant emittance growth can be observed. Further investigations show that it is apt to produce halo particles under resonance, and the machine becomes more sensitive to errors and mismatches. Therefore, it is important to keep all cells in the stable region throughout the linac of very high beam power to minimize beam losses.展开更多
文摘无刷直流电机(brushless DC motor,BLDCM)换相时刻关断相电流的续流造成电机端电压的畸变。当采用无位置传感器反电动势过零检测法时,端电压波形畸变会使位置检测信号相位超前,偏离最佳换相时刻,重载条件下甚至会造成换相失败,制约了反电动势检测法的电机功率应用范围。因此,该文针对电流续流影响端电压的机理加以分析,建立了电流续流产生相位超前的数学模型,并给出了位置检测信号相位超前的补偿算法。仿真和实验结果表明,经过补偿后的位置检测接近最佳换相时刻,重载条件下仍可正常运行。
基金Supported by National Natural Science Foundation of China (No.11075198)
文摘As a third generation light source, Shanghai Synchrotron Radiation Facility (SSRF) has up to 140 beam position monitors (BPM) installed to monitor the beam dynamics on its storage ring. Once the operation mode is chosen, the betatron functions are determined. Since the sinusoidal betatron oscillation is the dominant component of the transverse motion, these BPMs can be used to measure the motion to get the betatron functions. Three methods are compared to calculate the phase advance among the BPMs in this paper, aiming to find one or more feasible ways to check the beam optics in SSRF. Some experiments have also been made to verify the practicality of the phase information.
基金Supported by National Natural Science Foundation of China(10875099, 91126003)China ADS Project (XDA03020000)Institute of High Energy Physics Special Funding (Y0515550U1)
文摘The period length is usually much larger than the cavity effective length in a low energy superconducting linac.The long drifts between cavities will not only decrease the acceptance of the linac, but also lead to possible instability. The linac will be more sensitive to mismatch and other perturbations. From the longitudinal motion equation, the function which describes the parametric resonance is deduced and the relation between the instability region and the cavity filling factor is discussed. It indicates that if the zero current phase advance per period is kept below 90°, instability driven by parametric resonance will never occur. The space charge effect will enhance the instability, so that a stricter limitation on the phase advance per cell is required. From the numerical simulation results for two different schemes of Injector-Ⅰ of the C-ADS driver linac, one can find that even with just three cells in the unstable region, significant emittance growth can be observed. Further investigations show that it is apt to produce halo particles under resonance, and the machine becomes more sensitive to errors and mismatches. Therefore, it is important to keep all cells in the stable region throughout the linac of very high beam power to minimize beam losses.
