A high flow rate thermal bubble-driven micropump with induction heating

A thermal bubble-driven micropump with magnetic induction heating is successfully demonstrated in this paper. Energy is transferred from the planar coil outside the microchamber to the metal heating plate inside the microchamber through the electromagnetic field, and Joule heat is induced by the eddy current in the heating plate. Sequential photographs of bubble nucleation, growth and shrink in open environment were recorded by a CCD camera. One advantage of the micropump is that there is no physical contact between the heating plate and the external power supply circuit, which resulted in an easy fabrication process. What’s more, compared with other thermal bubble-driven micropump with resistive microheater, the flow rate and the pump stroke have been improved significantly due to its larger dimension of the heating plate and larger bubbles volume. The experiments show that the maximum flow rate of this micropump is about 102.05 μL/min, which can expand the potential applications, especially for microfluidic system that requires higher flow rate.     

基于STM32的超音频感应加热电源设计

提出一种利用STM32作为控制芯片来控制实现超音频感应加热的电源方案。让STM32的高级定时器输出四路PWM控制逆变全桥的IGBT管门极,通过检测负载回路电压及电流波形的相位差实时调控输送给门极PWM的频率,使系统达到准谐振状态,从而将无功功率的消耗控制到最小,并且通过改变逆变电桥左右桥臂的IGBT门极输入的驱动波形的相位来改变电源的输出功率。     

Research on low-temperature anodic bonding using induction heating

A novel low-temperature anodic bonding process using induction heating is presented in this paper. Anodic bonding between silicon and glass (Pyrex 7740) has been achieved at temperature below 300 °C and almost bubble-free interfaces have been obtained. A 1 kW 400 kHz power supply is used to induce heat in graphite susceptors (simultaneously as the high-voltage electrodes of anodic bonding), which conduct heat to the bonding pair and permanently join the pair in 5 min. The results of pull tests indicate a bonding strength of above 5.0 MPa for induction heating, which is greater than the strength for resistive heating at the same temperature. The fracture mainly occurs inside the glass or across the interface other than in the interface when the bonding temperature is over 200 °C. Finally, the interfaces are examined and analyzed by scanning electron microscopy (SEM) and the bonding mechanisms are discussed.     

一种适合中频感应加热电源的IGBT驱动技术

为了满足感应加热电源中对IGBT驱动与保护功能的要求,采用北京落木源电子技术有限公司生产的专用于大功率单管MOSFET和IGBT的驱动芯片TX-KA101为核心器件设计一个驱动电路。该驱动芯片具备完善的三段式过流保护功能,工作频率高(可达80 kHz),延迟时间小,驱动能力强,保护功能完善,因而非常适合10⁵0 kW感应加热电源的应用。对此驱动电路的构成、工作原理、外围电路的设计和参数设置作了详细的描述并给出实验结果,最后经部分公司在中频感应加热电源上的成功应用进一步验证了由KA101驱动芯片构成的驱动电路运行稳定可靠,效率高,发热量小,可以经受工业环境中的严峻考验。     

Combining power and data lines in the heating control system of a thermal cover

The authors present the results of an experiment on transferring the control signals through the power supply line of a heating control system.     

基于带并联电抗器的大型火电机组核相新技术研究

针对出线侧带并联电抗器的大型火电机组进行并网核相试验时遇到的特殊问题,提出了以发电机作为核相电源,进行两待并系统核相的新方法。对试验方案进行仿真模拟,对试验过程中各电量的变化进行考查,并对各设备保护的定值整定和投入进行论证。最后在核相试验过程中采取综合措施顺利解决励磁系统参数配合问题,圆满完成核相试验。     

感应加热电源数字移相触发器设计

用数字触发器的设计思想设计其硬件结构并对软件算法进行了改进.改进后的数字移相触发器简单可靠,产生脉冲的对称性好,抗干扰能力强,能够保证捕获到每一个换相区并及时触发.     

Study on the effect of heating plate thickness on the micro induction heater for thermal bubbles generation

This paper designed a micro planar induction heater for thermal bubbles generation. The micro heater which consists of a micro planar coil, a copper heating plate and a glass slide was fabricated with MEMS fabrication process. The relations between the heating performance and the thickness of heating plate were studied in the simulation with the software of COMSOL. The experimental system has been built and the experimental tests for thermal bubble generation have been also carried out with the prototype. The process of thermal bubbles generation was recorded by the video camera. The frequency of AC current applied in the experiment is 100 kHz and the heating time of 1 s. The experimental results indicated that the micro heater has the best heating performance with the heating plate thickness of 12–16 μm, and the minimum power for thermal bubbles generation was only 0.427 W. This micro heater can be applied to a variety of thermal bubble devices, such as micro actuator, micro ejector and micro pump.     

Solder bonding with a buffer layer for MOEMS packaging using induction heating

In this paper, the selective induction heating technology is applied to glass–glass and glass–silicon solder bonding for MOEMS (optical MEMS) packaging. The Ni bumping with a buffer layer is successful to release the thermal stress for avoiding delamination. The Au wetting layer must be thick enough to prevent from being solved entirely into Sn, and it will improve bonding strength. The bonding specimens are soaked into 25°C water and placed into 85°C/85% RH oven, respectively. No moisture penetrates into the cavity after 1 day in both test conditions. In the test condition of 125°C leakage-test liquid (Galden HS260), no bubble is observed. The lowest bonding strength is 3 MPa.     

Solder bonding with a buffer layer for MOEMS packaging using induction heating

In this paper, the selective induction heating technology is applied to glass–glass and glass–silicon solder bonding for MOEMS (optical MEMS) packaging. The Ni bumping with a buffer layer is successful to release the thermal stress for avoiding delamination. The Au wetting layer must be thick enough to prevent from being solved entirely into Sn, and it will improve bonding strength. The bonding specimens are soaked into 25°C water and placed into 85°C/85% RH oven, respectively. No moisture penetrates into the cavity after 1 day in both test conditions. In the test condition of 125°C leakage-test liquid (Galden HS260), no bubble is observed. The lowest bonding strength is 3 MPa.

     

具有防盗功能的热量表的研制

采用TI公司的MSP430F133混合信号处理器、Pt1000配对热电阻及脉冲电磁阀设计的热量表具有功耗低、精度高、稳定性好的特点：采用MOSFET芯片设计的断电自关闭功能电磁阀解决了防盗的难题。     

基于热路模型的充电机智能功率调节方法研究

车载充电机是电动汽车发展的关键设备。此类设备在高温环境下运行极易超过最大温升限制,同时车载设备因路况和空间等问题,器件温升不易直接测量,难以实现温度可靠保护。针对车载充电机在高温环境应用时易过温的问题,提出基于功率器件集中参数热路模型的智能功率调节方法。该方法首先探寻充电机内部温升最高的功率器件;随后针对该功率器件,建立可描述器件温度、输入功率及环境温度关联性的集中热路模型,并对模型参数进行估计;最后利用该热路模型,构建充电机输入功率闭环控制策略;实验结果表明,基于热路模型的功率控制方法,可有效限定充电机功率器件温升,提高充电机的热稳定性。     

Study on localized induction heating for wafer level packaging

Micro-electro-mechanical systems(MEMS)are being developed as a new multi-disciplinary technology,which will undoubtedly have a revolutionary impact on the future of human life.However,with the development of MEMS technology,the packaging has become the main technical obstacle to the commercialization of MEMS.An approach to MEMS packaging by high-frequency electromagnetic induction heating at wafer level is presented in terms of numerical simulation and experimental study.The structure of inductor is firstly...     

Hot embossing of microstructure with moving induction heating and gas-assisted pressuring

A new apparatus for a moving induction heating and gas-assisted hot embossing apparatus has been developed. A mechanism was designed and implemented to move the platform in and out the wrapped coil, on which the sealed box for substrate/mold was placed. A chamber of 195 mm diameter and 221 mm length was machined. The movable platform, the sealed box with substrate/mold stack, wrapped coil and cooling fan were all implemented in the high pressure chamber. The nine-point thermocouples attached on the mold, thus, a temperature history of the moving induction heating can be obtained and study the influence of the moving path and power on the heating rate and temperature distribution. The micro V-cut structure hot embossing experiment were performed to prove the potential of this moving induction heating and gas-assisted pressuring hot embossing for fast fabrication of microstructure onto polymeric substrates. As a results, replication rates were all above 95% at 200 °C and 5 kgf/cm² and the cycle time was less than 4 min and the optic measurement shows the replicated V-cut film can enhance the 36.8% illuminance. The experiment results show the manufacturing potential of this apparatus.

     

基于热调度消纳风电的户式相变蓄热电采暖热容量研究

传统研究方法在研究户式相变蓄热电采暖热容量时,准确性很低。为了解决这一问题,基于热调度消纳风电提出了一种新的户式相变蓄热电采暖热容量研究方法,首先通过系统备用功率分析了热电模式下户式相变蓄热系统接纳风电能力,进而给出了风电供热调度模型,该模型根据显热蓄热热容量,潜能蓄热热容量和化学反应蓄热三种户式相变蓄热方式进行电采暖热容量研究。与传统研究方法进行实验对比,结果表明,给出的方法准确率可以达到99.82%,传统的研究方法准确率为90.53%,所提方法误差率更小,具有更广阔的发展空间。     

感应加热过程调频锁相-移相调功复合控制

串联谐振感应加热过程包括调频锁相和移相调功两个控制环节,二者具有较强的非线性和耦合性;在分析逆变频率、输出功率同锁相角、移相角关系的基础上,提出了基于频率分离原理的调频锁相-移相调功复合控制方案,将锁相-调功过程分解为快-慢子系统,并对两个过程分别设计了具有鲁棒稳定性的锁相控制器和移相控制器,解决了感应加热电源的调频锁相-移相调功环节的协调控制问题;将调频锁相-移相调功复合控制方案应用于额定功率20kW,输出电流40A的超音频串联谐振感应电源中,验证了该控制方案在确保逆变过程开关器件安全可靠的同时,提高了功率输出的效率;在保证了调功灵活性的同时,又实现了电源的阻抗自匹配。     

基于Matlab热路模型的变压器绕组温度场研究

通过Matlab仿真分析,建立变压器绕组热路模型,得到绕组的热点位置和温升范围,将一种聚四氟乙烯材料作底板的光纤Bragg光栅(FBG)传感器通过匝间的垫片安装于绕组的热点位置.通过光栅窄带滤波反射后,解调拟合出光波长,通过数学模型计算得到热点温度.采集数据显示,测得绕组热点温度在额定功率实测为71℃,仿真结果为71.8℃;1.3倍功率实测温度为73℃,仿真结果为73.6℃.通过对比,能够及时在线反映出绕组的热点温度,为变压器的安全运行提供重要的参考数据.     

基于历史数据挖掘和劳斯判据的某火电机组功率振荡机理分析

当汽轮机阀门流量特性恶化时,会引起发电机组功率振荡,进而可能引发电网低频振荡。本文以发生过功率振荡的某660MW超临界机组为例,通过数据挖掘和劳斯稳定判据原理,挖掘机组历史数据得到实际阀门流量特性,同时建立有功调节系统综合模型,定性、定量地分析汽轮机阀门流量特性对系统稳定性的影响,计算得到使系统失稳的阀门流量特性曲线曲率（k）的临界值为3.3438,当k大于临界值时,系统将失稳。同时,通过数据挖掘分析发现机组在92.7%～96.6%综合阀位指令段的阀门流量特性恶化严重,k值最大达到了7.771,远大于临界值,这是导致机组在该指令区间内发生多次功率振荡事件的根本原因。本文的分析方法对今后类似功率振荡事件的分析诊断,有一定的借鉴作用。