AbstractDifferent from the copper loss of general permanent magnet (PM) motors, the copper loss of ultra‐high‐speed permanent magnet motors (UHSPMSM) includes DC losses and eddy current losses, which lead to difficulty in analysis. In consideration of the influence of speed, wire diameter and current harmonic loss, DC copper loss and eddy current copper loss are calculated and analysed, respectively, so as to find the main excitation source of copper loss of UHSPMSM. Then, in order to calculate the Litz wire loss in a slotless stator, a Litz wire loss equivalent model is established, which can be used to accurately and quickly calculate the DC loss and eddy current loss of Litz wire independently. Finally, a copper loss separation method is designed to test copper loss of 550,000 rpm UHSPMSM considering the influence of the rotor PM flux at ultra‐high speed. The theoretical analysis and experimental results verify each other. In the end, the experimental results verify the effectiveness of theoretical analysis.

超高速永磁电机驱动系统在超高基频运行条件下,延迟会严重影响系统稳定性.该文对电流环动态模型进行精确重构,并系统分析高基频运行条件下延迟引入的交叉耦合与时延效应对系统稳定性的影响.在此基础上,提出一种适用于超高速电机的基于双采样电流预测的阻尼-积分型电流环调节机制,通过对系统阻尼比进行补偿,消除附加交叉耦合影响.此外,该文还设计一种分段执行式的双采样电流预测算法,可在不依赖任何参数的情况下实现下一拍反馈电流预测,有效补偿系统稳定裕度.以上两个措施为确保超高基频系统全局稳定提供有力保障.最后,在一台550000r/min/110W超高速实验样机平台上,对所提改进型电流环调节机制进行充分仿真与实验分析,有效验证了所提方案的有效性与优越性.

针对传统电流源逆变器(current source inverter,CSI)超高速电机驱动系统存在的控制对象阶次高、电流调节器设计困难问题,提出基于混合型两级式CSI的改进型控制策略.其基本思想为:前级引入宽禁带(wide band gap,WBG)器件高频调节定子电流幅值;后级采用普通硅器件调节定子电流相位.在此基础上,为实现最大转矩电流比控制,提出单电流传感器锁相环(phase-locked loop,PLL)方案,通过对转子位置信号与相电流锁相实现电流相位自动校正.混合型CSI前后级通过该改进控制策略进行协同控制,从而实现闭环系统降阶.同时考虑到混合型CSI在超高基频运行条件下控制延迟的实际问题,进一步完善电流控制环路模型,并与CSI传统拓扑及其控制策略下的电流环稳定性及动态性能进行深入分析与对比.最后研制一套混合型CSI驱动平台,并以一台(550000r/min)/110W的超高速永磁同步电机(ultra-high-speed permanent magnet synchronous motor,UHSPMSM)为对象进行仿真及实验验证,结果表明混合型驱动拓扑及改进型策略具备更高的稳定裕度与动态性能.

为了对环境中的低频声能量进行高效回收,提出了一种基于Helmholtz共鸣器、压电单晶片以及接口电路的压电式微型俘能器.通过理论分析了俘能器的最佳工作频率,通过实验对理论分析结果进行了验证,并且研究了声源在不同距离下,俘能器的输出特性.实验结果表明:当俘能器在共振频率下工作时,在距离声源0.1 m,声压级为110 dB,负载值为48 kΩ时,最大输出功率高达24 mW;当距离从1 m增加至4 m时,输出功率从1.17 mW降低至0.38 mW,俘能器在距离较远的情况下仍能够提供足够的功率为微电子器件进行远距离独立供能.

针对采用线性霍尔元件检测高速永磁同步电机转子位置时,存在多种非理想因素造成的误差进行分析,并提出了相应的误差补偿方法.当两路霍尔信号幅值不相等、相位非正交时,检测的转子位置信号中存在二倍基频的误差分量,对此提出一种基于坐标变换的位置误差补偿方法,即构造坐标变换以提取出霍尔信号中的正序分量,根据其正序分量解算出转子位置;当霍尔信号采样调理电路中存在低通滤波器以及安装角度存在偏差时,两路霍尔信号存在一定的相位偏差,提出了一种基于电流环特征量的位置误差自适应补偿方法,即根据电流环的特征量与转子位置误差之间的关系,对位置补偿角进行自适应调整以补偿误差.最后,通过仿真和实验验证了所提出的两种方法的有效性.

高速永磁同步电机驱动系统具有电磁时间常数小、高速区载波比低的特征,加剧了电流纹波,影响系统效率、振动噪声和电磁干扰.为降低高速永磁同步电机的电流纹波,基于SiC-MOSFET/Si-IGBT混合型逆变器设计了一种改进型低损耗空间矢量调制算法.首先,通过调整零电压矢量的生成方式和各功率器件的开关动作时序,将大部分开关动作转移至低损耗的SiC-MOSFET中,并为高损耗的Si-IGBT提供零电压开关条件,降低了逆变器损耗,提高了驱动系统的效率和可用开关频率,逆变器开关频率的提高有效降低了电机电流纹波.其次,对该算法作用时的电流纹波特性进行深入分析,在此基础上提出一种变开关频率模式的最优交轴电流纹波峰值调制算法以优化交轴电流纹波性能.然后,根据预测的交轴电流纹波峰值实时调整载波频率,通过削峰填谷的方式对交轴电流纹波进行平均,在不增加开关损耗的条件下,分散开关能量、降低转矩脉动、改善振动噪声和电磁兼容性能.所提方案的优势在于:较于传统型逆变器,逆变器开关损耗降低、效率提高,可进一步提升开关频率以改善电流纹波;较于传统空间矢量调制算法,改进了电压矢量的生成方式,并利用载波频率这一新增自由度分散能量,降低了交轴电流纹波.最后,通过仿真与实验对所提出算法的有效性进行了验证.

As a kind of renewable energy, acoustic energy can be converted into electrical energy to supply energy for micro-electronic devices, which is a meaningful research topic. In order to keep working at the maximum power point all the time, an acoustic energy harvest system based on the maximum power point tracking (MPPT) control method is proposed. The system is composed of a Helmholtz resonator, a piezoelectric transducer, and an interface circuit, and the interface circuit is composed of a rectifier circuit and a buck-boost circuit. When the acoustic wave enters the cavity, the acousto-electric conversion is carried out through the piezoelectric transducer, and then the DC power is output through the interface circuit. Finally, through the MPPT control program, the system always works at the maximum power point. The theoretical and simulation analysis of the interface circuit is carried out, and the performance of the system is studied and verified by experiments. When the load is constant and the SPL (Sound Pressure Level) increases, the optimal duty cycle fluctuates between 0.1 and 0.3, and the voltage and power of the load increase with the increase of the SPL. When the SPL is 110 dB and the duty cycle is 0.15, the maximum power of the load is 115.2 µW. When the SPL is 110 dB, the optimal duty cycle fluctuates between 0.1 and 0.2. When the load resistance is 30 kΩ, 50 kΩ, 70 kΩ, 90 kΩ, and 110 kΩ, the maximum power of the load is 110.45 µW, 115.2 µW, 104.14 µW, 106.78 µW, and 105.1 µW, respectively.

转子位置信息的精度影响高速永磁同步电机的运行性能,在高速运行条件下,转子位置估算容易受到环路滤波器和电机参数偏差等非理想因素的影响.首先,针对转子位置估算误差,该文提出一种自适应基准锁相环,主要思想是锁相环通过误差重构,实现对基频相关误差补偿.在此基础上,以最小电流为目标自适应调节锁相环的锁相基准,实现对非基频相关误差的补偿,最终实现对位置误差的全补偿,该方法实现简单、参数依赖性低、鲁棒性强.最后,基于一台高速永磁同步电机进行仿真与实验,结果验证了所提出方法的有效性.

The large current ripple caused by the limited switching frequency significantly degrades the control performance of the high-speed permanent magnet motor drive system. To mitigate the current ripple, the switching frequency of the inverter should be high enough. The purpose of this article is to reduce the current ripple of the HSPMSM drive system. First, a Silicon-Carbide/Silicon(SiC/Si) hybrid inverter is designed. The designed hybrid inverter consists of two SiC-MOSFETs and six Si-IGBTs, and the circuit modals of the SiC/Si hybrid inverter are analyzed. Second, based on the SiC/Si hybrid inverter, three improved space-vector-modulation (SVM) strategies are proposed. The core principle of the proposed SVM strategies is that most of the switching actions are transferred from the Si-IGBTs to the SiC-MOSFETs. The benefit from the low switching loss of the SiC device is that the total power loss can be significantly reduced. Besides, the SiC-MOSFETs can create the zero-voltage-switch condition for the Si-IGBTs, and then the switching loss of the Si-IGBTs can be almost eliminated. Finally, to verify the effectiveness of the proposed methods, sufficient simulations and experiments are implemented. The stator current ripple, total-harmonic-distortion, and the conversion efficiency of the inverter in the full power range are compared under the same condition based on the full-Si-IGBT inverter, the full-SiC-MOSFET inverter, and the SiC/Si hybrid inverter. The evaluated results sufficiently verify the superiority of the proposed SiC/Si hybrid inverter and the improved SVM strategies.

基于超高速微型永磁电机(UHSMPMM)受多物理场特性制约的问题,该文对超高速微型永磁电机支撑系统、电磁(热)设计、结构强度及动力学等方面进行综合设计研究.首先,结合超高速微型永磁电机的工作特性及微型转子结构特点设计整体式支撑系统及电机整机架构;其次,研究高频条件下的电磁-损耗-温升特性,其中重点分析温升特性对转子结构强度的影响,并给出基于温度场耦合下的超高速转子结构强度关键参数的优化方法;再次,探究整体支撑系统中转子临界转速的影响因素及变化规律;最后,依据多耦合特性分析及优化结果,研制一台550000(r/min)/110W原理样机,并对样机进行实验测试.结果显示,该样机实现了稳定运行,从而证明了所提设计方法的有效性.

针对传统桨叶风力发电系统体积庞大、不适用于微小型电子系统的问题,利用压电材料、钝体、接口电路,设计了一种微型风力发电系统.基于涡激振动原理改进了发电装置的能量回收电路,既可对风能进行有效回收,又能输出较高电压,解决了微电子器件的供能需求.分析了装置的固有频率,对两种接口电路进行了仿真分析,通过实验研究了装置使用VD接口电路后,在不同风速下的输出电压特性,以及在不同负载、不同风速的条件下的输出电压与输出功率特性.实验结果表明:输出电压、功率随风速增加而增加,在风速22 m/s时,最大开路电压有效值为36.2 V,存在最优负载使得输出功率最高,实测为560 kΩ,最高输出功率为375.5μW,相比标准(Standard)电路提升了7.07％,可独立对微电子器件供能.

为了高效回收环境中的声能,基于阵列式压电换能器、直管谐振腔以及能量回收电路提出了一种声能量回收系统.当声波进入直管谐振腔,管中产生谐振驻波作用于压电换能器,将声能转换为电能.本文设计了能量回收电路并且进行理论、仿真分析实验研究了压电振子数量、声波频率、声压级对输出电压的影响,分析了负载电阻对输出电压及功率的影响.实验结果表明,该装置可回收不同频率的声能量,在声波频率为96Hz时发电效果最优.当入射声压级为110dB时,不使用能量回收电路,输出交流电压有效值最高达12.9V,输出交流功率最高达到799μW;使用设计的能量回收电路,最高输出直流电压为64.2V,最高输出直流功率为473μW.该声能量回收系统不仅可以作为声能量采集器,还能对无线传感节点等独立工作的微型电子系统供能.

高速永磁同步电机(high-speed permanent magnet synchronous motor,HSPMSM)驱动性能与转子位置信号检测精度密切相关.基于反电动势滑模观测器(high-speed permanent magnet synchronous motor,EMF-SMO)的位置估计方案具有鲁棒性强的优势.然而高速运行条件下,观测器环路中的滤波器、零阶保持器、代数环等非理想环节将引起明显的相位估计误差.为了有效补偿相位估计误差,该文提出一种基于双重锁相环的新型EMF-SMO方案,其基本原理在于,通过主动引入前述非理想环节对电流信号进行延迟重构,将重构电流信号与估计位置信号进行二次锁相,构成双重锁相环,无需定量即可实现相位估计误差全补偿.该方法未引入任何敏感参数,鲁棒性强.该文针对一台400W/15000rpm高速永磁同步电机进行仿真与实验,仿真与实验结果验证了所提出双重锁相环方案的有效性.

To improve the micro-positioning accuracy of piezoelectric bimorph actuators, a driving power was designed with filter compensator. Amplifier modular was designed with high-voltage operational amplifier, and filter compensator modular is responsible for charge signal. Simulation results show that the output of filter compensator modular is proportional to the electric charge on the actuator. Experimental results indicate that the maximum error is 10μm without filter compensator modular, and reduced to 5μm with proposed driving power.

Micro wind harvesting system with piezoelectric structure is an attractive method to power micro electric devices in outdoor field work. Interface circuit is one of the keys to improve the efficiency of harvested energy. A SECE interface circuit is design with microcontroller, which monitors the voltage and generates pulse signal. A simulation is performed in Multisim software to validate the proposed circuit. Results show that the maximum output power of classic interface circuit is 128.118μW at 110KΩ, and it increases to 390μW with proposed SECE interface circuit. It indicates that the efficiency of harvested energy is improved by 200%.

In order to harvest the acoustic energy in the environment, an electromagnetic acoutic energy harvest system is proposed based on Helmholtz resonator, coil, permanent magnet and interface circuit. When the sound wave is injected into the resonator, it causes the upper surface permanent magnet to vibrate and outputs electrical energy from the coil. The resonant frequency of the resonator is simulated and analysed by finite element method, the interface circuit is simulated and analysed, the acousto-electric conversion principle is analysed theoretically. The output characteristics of the system under different frequencies and sound pressure levels are studied by experiments, and the output characteristics of the system after using the interface circuit are studied. The experimental results show that the system can harvest the acoustic energy of different frequencies, and the power generation effect is better when the acoustic frequency is near 98Hz and 140Hz, which is close to the first two resonant frequencies of the system. The output voltage and power of the system increase with the increase of the sound pressure level. When the sound pressure level is lower than 105dB, the output voltage and power of the system under the acoustic frequency of 95Hz is higher, and when the sound pressure level is greater than 105dB, the output voltage and power of 140Hz acoustic frequency is higher. After using the interface circuit, the maximum open-circuit voltage is 13.65V when the sound pressure level is 110dB and the frequency is 98Hz, and the maximum output power of the system can reach 0.625mW when the sound pressure level is 110dB and the frequency is 140Hz.

This article focuses on the issue of the rotor position estimation error correction for high-speed permanent magnet synchronous motor sensorless drive system. First, a rotor position estimator is designed. Then the estimation error caused by different kinds of nonideal factors is analyzed in detail. Estimation error results in larger amplitude of the stator current, the larger loss, and the degradation of the output torque. To eliminate the estimation error, a novel correction method based on the "minimu-current-tracking (MCT)" method is proposed in this article. The main idea of the proposed method is to obtain the minimum amplitude of the stator current adaptively through the MCT algorithm. The estimation error can be reduced to zero by correcting the compensation factor of the designed position estimator and observing the amplitude of stator current until the amplitude converges to the minimum value. The proposed method has two advantages: 1) the estimation error caused by no matter which kind of nonideal factor can be completely corrected; 2) no sensitive parameters are required in the proposed method. Finally, sufficient simulated results and experimental results verify the effectiveness of the proposed MCT-based method.

A control strategy without current and rotor-position sensors is proposed to drive the ultra-high-speed permanent magnet synchronous motor (UHSPMSM) fed by current source inverter (CSI), which is beneficial to the simplification of control structure as well as the reduction of system size and cost. In the proposed control strategy, command currents of the CSI are obtained by mathematical calculation with reference currents of the motor stator, leading to the removal of current sensors. In addition, an improved sliding- mode-observer (SMO) is used to calculate rotor position, allowing the rotor position sensor to be eliminated. A prototype and the control system were built and the control strategy simulation by utilizing the actual parameters of the prototype was conducted, which verify the effectiveness of the proposed control strategy under 550000rpm.

The output current ripple of the three-level (3-L) inverter is important to the performance of the 3-L permanent magnetic synchronous motor (PMSM) drive system, but the neutral point (NP) balance for the 3-L T-type inverter is not considered in the analysis of current ripple up to this point. The NP balance algorithms change the current ripple distribution and it is necessary to develop novel methods for current ripple analysis. In this study, the sinusoidal pulse width modulation with zero-order voltage injection and virtual space vector PWM (VSV-PWM) are utilised to balance the NP potential of the 3-L inverter in the PMSM drive system. The analytical methods of current ripple under these two modulation methods are proposed and the effects of these two NP balance methods on the output current ripple are investigated, respectively. Based on the analysis of current ripple, two variable switching frequency PWM (VSF-PWM) methods considering the NP balance are proposed. The proposed VSF-PWM methods can not only reduce the switching loss but also suppress the electro-magnetic interference noise while keeping the NP potential balanced. Especially, the proposed variable switching frequency VSV-PWM (VSF-VSV-PWM) can effectively alleviate the intrinsic problem of high switching loss of VSV-PWM.