Browsing by Author "Meng, Che-Hao"

Now showing 1 - 8 of 8

120V/ns Output Slew Rate Enhancement Technique and High Voltage Clamping Circuit in High Integrated Gate Driver for Power GaN FETs
(2015)
Yang, Hsiang-An
;
Chiu, Chao-Chang
;
Lai, Shin-Chi
;
Chen, Jui-Lung
;
Chang, Chih-Wei
High power density is a key point that power converters endeavor to pursue. However, it is rare that gate driver of power converter can switch under high supply voltage with a fast operation frequency. In this paper, a half-bridge driver with the slew rate enhancement (SRE) technique is proposed and its switching frequency can be increased to 25MHz under a 700V supply voltage. Besides, the proposed high voltage clamping circuit ensures all circuits operating in a safe region without any overvoltage problems in the bootstrap operation. With specifically developed high voltage high speed (HVHS) process, high-side and low-side circuits can be well shielded by the isolation well which is embedded in the level shifter device to minimize chip size.
87% Overall High Efficiency and 11 mu A Ultra-Low Standby Current Derived by Overall Power Management in Laptops With Flexible Voltage Scaling and Dynamic Voltage Scaling Techniques
(2016-04-01)
Yang, Shang-Hsien
;
Chiu, Chao-Chang
;
Chang, Chih-Wei
;
Chen, Chen-Min
;
Meng, Che-Hao
The proposed overall power management in laptops can improve overall power conversion efficiency by the flexible voltage scaling (FVS) technique in cooperation with conventional dynamic voltage scaling (DVS) technique. The FVS technique separates the controller into two parts. One is a simple primary side controller and the other is emerged into the power management unit in the laptop for getting direct power control from the microprocessor. 12% light load efficiency and 7% peak efficiency are improved compared to conventional design with the DVS technique only but without the FVS technique. Furthermore, green mode is proposed to effectively reduce chip quiescent current to 11 mu A and to suppress power loss to 10 m W in ultra-light load, which is much smaller than 500 mW standby power defined by the restriction of Energy Star Standard and 40 mW of state-of-art commercial products.
94% Performance Improvement by Time-shift Control (TSC) Technique in Cloud Computing Voltage Regulator Module (VRM)
(2013)
Meng, Che-Hao
;
Su, Yi-Ping
;
Huang, Yu-Ping
;
Lee, Yu-Huei
;
Chen, Ke-Horng
the time-shift control (TSC) technique for voltage regulator module (VRM) is proposed to achieve high performance power supply for servers in cloud computing. Four power stages are adopted to provide high current driving capability and low output ripple. Besides, the power request, which includes the number of active phases and voltage identification (VID), is acknowledged by servers for high driving capability during high throughput and high efficiency during standby mode. Furthermore, to equally distribute the current in each phase, the proposed TSC technique improves the current balance performance and solves the stability problem. In the scale-down clouding computing prototype, the efficiency can be kept higher than 90% over a wide load current range of 2 A. Besides, the performance and operating frequency of the servers in stable operation are not limited by the VRM with the TSC.
A Buck Power Factor Correction Converter with Predictive Quadratic Sinusoidal Current Modulation and Line Voltage Reconstruction
(2016-09)
Yang, Shang-Hsien
;
Meng, Che-Hao
;
Chiu, Chao-Chang
;
Chang, Chih-Wei
;
Chen, Ke-Horng
A buck power factor correction (PFC) converter operating in continuous conduction mode (CCM) is influenced by the dead zone, which introduces distortion related to the input line voltage. Such phenomenon limits the maximum power factor (PF) and the minimum total harmonic distortion (THD) achievable. By deriving a methodology to achieve predictive line voltage reconstruction (PLVR), the influence of the dead zone is mitigated. With the prediction of quadratic sinusoidal current modulation ((PSCM)-C-2), the line current is shaped into sinusoid waveform that is in-phase with input line voltage, crucial for. Consequently, the proposed CCM buck PFC can achieve high PF, low THD, and efficiency simultaneously. A test chip was fabricated in 0.5-mu m Bipolar-CMOS-DMOS (BCD) process. The experimental results show a peak PF of 0.95 and a peak efficiency of 98% at 110 Vac.
A Compact Power Management for Next Generation Intensive Care Unit with 91% Conversion Efficiency
(2014-01-01)
Chiu, Chao-Chang
;
Yang, Hsiang-An
;
Su, Yi-Ping
;
Chang, Chih-Wei
;
Meng, Che-Hao
the proposed single-inductor dual-output (SIDO) converter with energy-conservation mode (ECM) control is designed for next generation intensive care unit. The energy-conservation mode (ECM) control generates two different energy delivery paths for dual buck outputs with only one inductor. In addition, the superposition technique is used to achieve a minimized inductor current level. The average inductor current is equal to the summation of two output loads. The measurement results shows the 91% peak efficiency can he derived.
High Efficiency and Total Harmonic Distortion Improvement by Zero Current Prediction Technique for Transformer-Free Buck Power Factor Corrector
(2014-01-01)
Meng, Che-Hao
;
Chang, Chih-Wei
;
Chiu, Chao-Chang
;
Chen, Ke-Horng
;
Lin, Ying-Hsi
Power factor correction (PFC) can shape the input current of off-line power supplies to be in-phase with the input AC voltage to maximize the available real power from the AC source for high power factor (PF). Boundary current mode (BCM) operation is the easiest way to get good power factor performance. However, the zero current detection in conventional PFC based on the voltage across the auxiliary winding which is suffer from the delay of zero current detection timing. Therefore, this paper proposed a high efficiency and total harmonic distortion (THD) improvement for transformer-free buck power factor corrector with zero current prediction mechanism. The chip fabricated in 0.5 mu m 800V ultra-high voltage (UHV) process can be powered on directly by the AC source owing to the 800V ultra-high voltage device. The output voltage of buck PFC is set at 80V and the PF is high to 0.98 without additional component compared with traditional buck PFC. The maximum efficiency of proposed buck PFC converter is 98.4% when input voltage is 110V AC.
Self-Adaptive Zero Current Prediction (SAZCP) Technique for Auxiliary Winding-free Boost Power Factor Correction Controller
(2013)
Chang, Chih-Wei
;
Meng, Che-Hao
;
Chen, Ke-Horng
;
資訊工程學系
;
Department of Computer Science
Power factor correction (PFC) can shape the input current of off-line power supplies to be in-phase with the input AC voltage to maximize the available real power from the AC source for high power factor (PF). Considering high PF and efficiency, the boundary conduction mode (BCM) control is more suitable for low-power applications such as the adapter and lighting. However, the zero current detector (ZCD) in conventional boost PFC suffers from high cost due to the need of auxiliary winding. The proposed self-adaptive zero current prediction (SAZCP) technique can accurately detect the zero current to implement an auxiliary winding-free boost PFC controller for low cost. Simulation results demonstrate that high PF of 0.998 and low THD of 3% can be achieved.
Self-Calibrated Knee Voltage Detector With 99.65% High Accuracy for AC Charger System in 0.5 mu m 500 V UHV Process
(2014-10-01)
Chiu, Chao-Chang
;
Lin, Moris
;
Chang, Chih-Wei
;
Meng, Che-Hao
;
Yang, Hsiang-An
The self-calibrated knee voltage detector (SC-KVD) for electrical isolation primary side charger applications is proposed. The removal of the feedback network which is used in conventional designs and occupies at least 30 mm(2) can save PCB area up to around 11%. Besides, the SC-KVD can dynamically adjust the detection point to improve the accuracy to 99.65% compared to the prior arts. The test chip fabricated in 0.5 mu m 500 V UHV process can be powered on directly by the AC source owing to the 500 V ultra-high voltage device. Hence, the battery charger can be made more compact and portable than it was and the battery life can be prolonged and guaranteed.