Showing papers on "Temperature control published in 2016"

Three-Dimensional Printable High-Temperature and High-Rate Heaters

Abstract: High temperature heaters are ubiquitously used in materials synthesis and device processing. In this work, we developed three-dimensional (3D) printed reduced graphene oxide (RGO)-based heaters to function as high-performance thermal supply with high temperature and ultrafast heating rate. Compared with other heating sources, such as furnace, laser, and infrared radiation, the 3D printed heaters demonstrated in this work have the following distinct advantages: (1) the RGO based heater can operate at high temperature up to 3000 K because of using the high temperature-sustainable carbon material; (2) the heater temperature can be ramped up and down with extremely fast rates, up to ∼20 000 K/second; (3) heaters with different shapes can be directly printed with small sizes and onto different substrates to enable heating anywhere. The 3D printable RGO heaters can be applied to a wide range of nanomanufacturing when precise temperature control in time, placement, and the ramping rate are important.

A Temperature-Dependent Thermal Model of IGBT Modules Suitable for Circuit-Level Simulations

Abstract: A basic challenge in the insulated gate bipolar transistor (IGBT) transient simulation study is to obtain the realistic junction temperature, which demands not only accurate electrical simulations but also precise thermal impedance. This paper proposed a transient thermal model for IGBT junction temperature simulations during short circuits or overloads. The updated Cauer thermal model with varying thermal parameters is obtained by means of finite-element method (FEM) thermal simulations with temperature-dependent physical parameters. The proposed method is applied to a case study of a 1700 V/1000 A IGBT module. Furthermore, a testing setup is built up to validate the simulation results, which is composed of a IGBT baseplate temperature control unit, an infrared camera with a maximum of 3 kHz sampling frequency, and a black-painted open IGBT module.

New Applications of an Automated System for High-Power LEDs

Abstract: An automatic system based on thermoelectric cooler (TEC), a microfan, and microcontroller is first applied to thermal management of high-power light-emitting diodes (LEDs). Its hardware is composed of microcontroller as a control core, K-type thermocouples as acquisition devices, and TEC and a microfan with heatsink as cooling vehicles. The experiment confirms that the LEDs substrate temperature can be controlled effectively, and indicates that the LED chips are operating reliably. Specifically, in high-temperature environments of 43 °C, the system can automatically drop to the low set temperature (30 °C) due to thermoelectric effect driven by TEC. Heat transfer analysis shows that maximum LED power cooled by the system is 106.7 W, and the total power consumption of the automatic cooling system is only 8.85 W. The automatic cooling system has a high cooling efficiency.

A MEMS-based heating holder for the direct imaging of simultaneous in-situ heating and biasing experiments in scanning/transmission electron microscopes.

Abstract: The introduction of scanning/transmission electron microscopes (S/TEM) with sub-Angstrom resolution as well as fast and sensitive detection solutions support direct observation of dynamic phenomena in-situ at the atomic scale. Thereby, in-situ specimen holders play a crucial role: accurate control of the applied in-situ stimulus on the nanostructure combined with the overall system stability to assure atomic resolution are paramount for a successful in-situ S/TEM experiment. For those reasons, MEMS-based TEM sample holders are becoming one of the preferred choices, also enabling a high precision in measurements of the in-situ parameter for more reproducible data. A newly developed MEMS-based microheater is presented in combination with the new NanoEx™-i/v TEM sample holder. The concept is built on a four-point probe temperature measurement approach allowing active, accurate local temperature control as well as calorimetry. In this paper, it is shown that it provides high temperature stability up to 1,300°C with a peak temperature of 1,500°C (also working accurately in gaseous environments), high temperature measurement accuracy (<4%) and uniform temperature distribution over the heated specimen area (<1%), enabling not only in-situ S/TEM imaging experiments, but also elemental mapping at elevated temperatures using energy-dispersive X-ray spectroscopy (EDS). Moreover, it has the unique capability to enable simultaneous heating and biasing experiments.

Temperature Control for a Polymer Electrolyte Membrane Fuel Cell by Using Fuzzy Rule

Abstract: Temperature control for a polymer electrolyte membrane fuel cell (PEMFC) is important in improving power efficiency and increasing fuel cell lifetime. If the temperature of the cell is too low, then the electrochemical reaction response becomes slow, thereby preventing evaporations of liquid water in the membrane. As a result, cell performance is decreased. However, too high temperature leads to waste in catalyst and heat because of excessive chemical reactions and to liquid water evaporation, which decreases proton conductivity. This study develops an electrochemical dynamical model and a thermal model of a PEMFC using MATLAB/Simulink for simulation. Fuzzy control rules are also built to regulate the temperature of a PEMFC. The fuzzy inputs include temperature error, its derivative, and external load current. The cooling fan speed is chosen as an output variable to regulate the temperature of a fuzzy control because the fuel cell utilizes the air cooling method. After confirming that the designed fuzzy rules are effective for controlling cell temperature, a real experimental device is built using an H-100 fuel cell and a cooling fan to verify the effectiveness of the proposed method.

Thermal Management-Oriented Multivariable Robust Control of a kW-Scale Solid Oxide Fuel Cell Stand-Alone System

Abstract: The aim of this paper is to develop an effective control system for a kW-scale solid oxide fuel cell (SOFC) stand-alone system based on our previous studies, where the dynamic model and the steady-state analysis and optimization of the system have been completed. The open-loop dynamic responses of the system are first conducted to gain insight on the system dynamics, and the results demonstrate that the system is a complicated multivariable system with strong coupling and nonlinear characteristics. Considering the complicated dynamics, a multivariable robust proportional-integral derivative (PID) control system is proposed with a multiloop feedforward/feedback control structure. The feedforward controllers are designed using the stack current based on the steady-state optimization results determined in the previous studies, and the feedback controllers are implemented by developing a single neuron adaptive PID algorithm. The adaptive PID combines the advantages of robust control and PID control, which can automatically adjust control parameters when system encounters uncertainties and disturbances, and is very easy for engineering practices because of its simple structure. Test results demonstrate that the multivariable robust PID control system has well robustness and stability for the SOFC system when operating point changes within the full operating range.

Experimental study on water-cooled thermoelectric cooler for CPU under severe environment

Abstract: In this paper, water-cooled thermoelectric cooler (TEC) for central processing unit (CPU) is developed. Two temperature controls for TEC are proposed and compared to prevent condensation on CPU and save energy. Performances of TEC with the two temperature controls are experimentally investigated under different operating conditions and environmental temperatures. Effects of air velocity and water mass flow rate for the heat sink are investigated under severe environment. Dynamic performance comparisons of three cooling methods, including TEC with and without temperature control and passive water cooling, are investigated under variable operating conditions at severe environment. Experimental results show that temperature of CPU (T cpu ) for SC is lower than that for OC when T cpu is lower than the set temperature. A higher COP can be kept when air velocity and water mass flow rate is 0.8 ms −1 and 0.042 kg s −1 , respectively. The largest temperature variation of T cpu s is lower than 1.5 °C under variable operating conditions at severe environment.

Recognition of the Temperature Condition of a Rotary Kiln Using Dynamic Features of a Series of Blurry Flame Images

Abstract: Maintaining a normal burning temperature is essential to ensuring the quality of nonferrous metals and cement clinker in a rotary kiln. Recognition of the temperature condition is an important component of a temperature control system. Because of the interference of smoke and dust in the kiln, the temperature of the burning zone is difficult to be measured accurately using traditional methods. Focusing on blurry images from which only the flame region can be segmented, an image recognition system for the detection of the temperature condition in a rotary kiln is presented. First, the flame region is segmented employing a region-growing method with a dynamic seed point. Seven features, comprising three luminous features and four dynamic features, are then extracted from the flame region. Dynamic features constructed from luminous feature sequences are proposed to overcome the problem of mis-recognition when the temperature of the flame region changes rapidly. Finally, classifiers are trained to recognize the temperature state of the burning zone using its features. Experimental results using real datasets demonstrate that the proposed image-based systems for recognizing the temperature condition are effective and robust.

Robust Motion Control of Ultrasonic Motors Under Temperature Disturbance

Abstract: This paper presents a practical robust controller that solves the problem of accurate motion control of ultrasonic motors (USMs) over prolonged durations, where temperature increases pose a significant challenge. This paper focuses on USMs with driver circuits that have a single user-controllable input. Prior to developing the robust controller, a nonlinear model of the system was identified by experimentally measuring the temporal relationship between motor speed and temperature to the applied input control signal. A linear approximation of this model was used to design two robust inverse dynamic controllers: one used temperature feedback and the other did not. Both control methods were implemented on a custom designed embedded control system and achieved highly consistent and accurate performance while under load over a range of working frequencies. Step-response experiments (1 rad) demonstrated a rise time of 0.1 s without any overshoot or steady-state error. A normalized RMSE below 3% with a delay of 25 ms was achieved for reference inputs with frequencies up to 1 Hz. This performance was maintained during prolonged continuous dynamic operation of several minutes, despite the great variation in the motor’s dynamics due to the temperature effects (over a range of 25 °C–45 °C) and modeling uncertainties.

Temperature measurement and control of bobbin tool friction stir welding

Abstract: Bobbin tool friction stir welding (BTFSW) is a relatively new, solid-state welding technology, but its control is not the same as the conventional friction stir welding (FSW) due to the unique welding tool structure. In this paper, closed-loop control system was developed and the Smith predictive proportional-integral-derivative (PID) control method was presented to assist the welding system in producing an appropriate interface temperature response. As it is difficult to accurately detect the temperature in full range of the welding zone, the tool-workpiece interface temperature is detected by thermocouple and wireless transmission technology. Initial experiments were conducted to derive a qualitative understanding of bobbin tool friction stir welding processes. Ziegler-Nichols setting method was adopted to determine parameters of the PID controller. While examining the capabilities of Smith predictive PID control in BTFSW, this paper focuses on the control effect of hysteretic characteristics of welding temperature during butt welding. A compensation strategy was setting gaps along the welding path, and the gap could affect the distribution of temperature. Through our experiments, we demonstrate that temperature control strategy is feasible, and the tensile properties of the weld are uniform along the welding direction.

Temperature control in a solar collector field using Filtered Dynamic Matrix Control.

Abstract: This paper presents the output temperature control of a solar collector field of a desalinization plant using the Filtered Dynamic Matrix Control (FDMC). The FDMC is a modified controller based on the Dynamic Matrix Control (DMC), a predictive control strategy widely used in industry. In the FDMC, a filter is used in the prediction error, which allows the modification of the robustness and disturbance rejection characteristics of the original algorithm. The implementation and tuning of the FDMC are simple and maintain the advantages of DMC. Several simulation results using a validated model of the solar plant are presented considering different scenarios. The results are also compared to nonlinear control techniques, showing that FDMC, if properly tuned, can yield similar results to more complex control algorithms.

A hierarchical distributed MPC for HVAC systems

Abstract: In this paper a hierarchical distributed model predictive control scheme is proposed for heating, ventilation and air-conditioning (HVAC) systems in buildings. The building consists in multiple connected rooms and zones. The control objective is to keep the temperature of each room and zone at a given comfortable level with minimal energy consumption. This control scheme is divided into two levels. The upper level controller collects temperature and predictive information of all rooms and zones to generate reference trajectories while a lower level controller only uses local information to track the reference and optimize energy efficiency and thermal comfort. By using a contraction property of building's dynamics, recursive feasibility of the proposed algorithm is guaranteed. Simulation results are given to show the performance of our proposed control strategy.

Temperature Uniformity Control of Large-Scale Vertical Quench Furnaces for Aluminum Alloy Thermal Treatment

Abstract: The thermal treatment of aluminum alloy workpieces requires strict temperature uniformity in large-scale vertical quench furnaces. To achieve the desired temperature uniformity in a large-scale spatial setting, a temperature uniformity control strategy combining workpiece temperature compensation and intelligent proportional–integral–derivative (PID) decoupling control is presented. The temperature compensation of the workpiece is realized by establishing an air heat conduction model. Moreover, an intelligent PID decoupling control system based on a novel self-growing radial basis function neural network (SGRBFNN) is developed to eliminate the strong coupling effects of multiheating zones. SGRBFNN, with the structure being dynamically adjusted by a hybrid semifuzzy Gustafson–Kessel clustering algorithm, is proposed to realize the online tuning of the parameters of the PID controller. Both the simulation and industrial experiment results demonstrate that the proposed temperature control system can effectively achieve smooth regulations and significantly improve temperature uniformity. The application also demonstrates the validity and better control performance of the proposed system compared with conventional control systems.

Computational light junction temperature estimator for active thermal control

Abstract: The junction temperature of power semiconductors in power converters must not exceed its maximum limits and it is of major importance for several failure mechanisms. But still, the junction temperature is hard to access. Direct measurement is not practical for industrial applications, indirect measurements require substantial effort and available junction temperature models have high calculation effort. This work develops a simple junction temperature estimator, which is applied for a maximum junction temperature limitation and the capability to be applied for further algorithm relying on the junction temperature, referring to active thermal control. It is experimentally shown, that a second order estimator is sufficient to achieve high bandwidth estimation.

Blanking system with constant-temperature control function

Abstract: The invention discloses a blanking system with a constant-temperature control function. The blanking system comprises a combustion cavity, a first detection device, a second detection device, a blanking device and a control device, wherein a charge port for charge is arranged in the top of the combustion cavity, and a blanking port for blanking is arranged in the bottom of the combustion cavity; the first detection device is used for detecting a temperature value T1 at a first position in the combustion cavity; the second detection device is used for detecting a temperature value T2 at a second position in the combustion cavity; the blanking device is used for starting or stopping working according to an instruction of the control device; the control device is in communication connection with the first detection device, the second detection device and the blanking device; an ideal temperature difference value t is preset in the control device, and the control device is used for obtaining T1 and T2 trough the first detection device and the second detection device, and calculating an actual temperature difference value T according to T1 and T2; and the control device is used for calculating an error value X according to the ideal temperature difference value t and the actual temperature difference value T, and controlling the blanking device to work according to the error value X.

Method and apparatus for power and temperature control of compartments within a personal communication structure (pcs)

Abstract: Techniques and apparatus for controlling the distribution of power (eg, current) and the temperature to individually accessible compartments enclosing subsystems of a personal communication structure (PCS) is described The PCS includes a power distribution and temperature controller subsystem, including thermal sensors adapted to generate and transmit temperature measurement data to the temperature controller, which controls fans/blowers The power distribution subsystem senses and controls the current delivered to the individually accessible compartments