Drive System Design for Small Autonomous Electric Vehicle: Topology Optimization and Simulation

High driving efficiency remains challenging in autonomous electric vehicles, especially in small electric vehicle subtype. Here, we reported investigation of the structure and requirements of the drive system for those vehicles, while the motor-drive axle combined integrated driving scheme has been chosen. In the study, the power matching of drive motor as well as transmission ratio has been calculated based on the performance of the small electric vehicles, and the total gear ratio of 8.124 was determined. For better comprehensive performance and efficiency, the two-stage retarder has been designed, in which elements including high-speed shaft, low-speed shaft, gears, and differential have been examined to ensure their proof strength when the motor outputs reached the maximum torque. Notably, by utilizing topology optimization, Gear 4, the transmission unit with the heaviest weight percentage has been modified in a lightweight way, achieving a 41% reduction of the mass in emulation analysis and turned up to the target of optimization eventually.

Coherent Photonic Terahertz Transmitters Compatible with Direct Comb Modulation

We present a novel approach to coherent photonic THz systems supporting complex modulation. The proposed scheme uses a single optical path avoiding the problems of current implementations, which include: phase decorrelation, 3-dB power loss, and polarization and power matching circuits. More importantly, we show that our novel approach is compatible with direct modulation of the output of an optical frequency comb (i.e., not requiring the demultiplexing of two tones from the comb), further simplifying the system and enabling an increase in the transmitted RF power for a fixed average optical power injected into the photodiode (PD).

Suppression of Acoustic Resonances in BST-Based Bulk-Ceramic Varactors by Addition of Magnesium Borate

This work presents a method for reducing acoustic resonances in ferroelectric barium strontium titanate (BST)-based bulk ceramic varactors, which are capable of operation in high-power matching circuits. Two versions of parallel-plate varactors are manufactured here: one with pure BST and one with 10 vol-% magnesium borate, Mg3B2O6 (MBO). Each varactor includes a 0.85-mm-thick ferroelectric layer. Acoustic resonances that are present in the pure BST varactor are strongly suppressed in the BST-MBO varactor and, hence, the Q-factor is increased over a wide frequency range by the addition of small amounts of a low-dielectric-constant (LDK) MBO. Although the tunability is reduced due to the presence of non-tunable MBO, the increased Q-factor extends the varactor’s availability for low-loss and high-power applications.

Radio-Frequency Power Harvest And Remote Clock Frequency Calibration Of Passive Wireless Microsystems

This thesis deals with radio frequency power harvest and remote calibration of system clock of passive wireless microsystems. The proposed method of RF power harvesting utilizes a step-up transformer inserted between the antenna and voltage multiplier of passive wireless microsystems to perform both impedance transformation for power matching and voltage amplification prior to rectification. The series resistance of the primary winding is minimized while in the secondary winding, the shunt capacitive losses are minimized. The detailed analysis of the proposed method and simulation results from Spectre of Cadence Design Systems are presented. The proposed power-matching and gain -boosting network, together with voltage multipliers, has been implemented in TSMC-0.18..m 1.8V6-meatl CMOS technology with thick metal options. For the purpose of comparison, a LC power-matching and gain-boosting network with the identical voltage multiplier has also been implemented on the same chip. Measurement results demonstrate that the proposed transformer power-matching and gain-boosting technique greatly improves the power sensitivity and efficiency as compared with widely used LC matching approaches. The proposed calibration method adjusts the frequency of the local oscillator of passive UHF wireless transponders to the desired values using an injection-locked phase-locked loop (IL-PLL). A new relaxation oscillator whose oscillation frequency is less sensitive to supply voltage fluctuation is also proposed. The power consumption of the proposed IL-PLL is minimized by operating it the sub-threshold. A detailed analysis of non-harmonic injection locking of relaxation oscillators including locking and pulling dynamics is presented. A new integrating feedback is proposed to increase the lock range and hold the locked frequency in the absence of the injection signal. The proposed ILL-PLL has been fabricated in TSMC-0.18.

Radio-Frequency Power Harvest And Remote Clock Frequency Calibration Of Passive Wireless Microsystems

This thesis deals with radio frequency power harvest and remote calibration of system clock of passive wireless microsystems. The proposed method of RF power harvesting utilizes a step-up transformer inserted between the antenna and voltage multiplier of passive wireless microsystems to perform both impedance transformation for power matching and voltage amplification prior to rectification. The series resistance of the primary winding is minimized while in the secondary winding, the shunt capacitive losses are minimized. The detailed analysis of the proposed method and simulation results from Spectre of Cadence Design Systems are presented. The proposed power-matching and gain -boosting network, together with voltage multipliers, has been implemented in TSMC-0.18..m 1.8V6-meatl CMOS technology with thick metal options. For the purpose of comparison, a LC power-matching and gain-boosting network with the identical voltage multiplier has also been implemented on the same chip. Measurement results demonstrate that the proposed transformer power-matching and gain-boosting technique greatly improves the power sensitivity and efficiency as compared with widely used LC matching approaches. The proposed calibration method adjusts the frequency of the local oscillator of passive UHF wireless transponders to the desired values using an injection-locked phase-locked loop (IL-PLL). A new relaxation oscillator whose oscillation frequency is less sensitive to supply voltage fluctuation is also proposed. The power consumption of the proposed IL-PLL is minimized by operating it the sub-threshold. A detailed analysis of non-harmonic injection locking of relaxation oscillators including locking and pulling dynamics is presented. A new integrating feedback is proposed to increase the lock range and hold the locked frequency in the absence of the injection signal. The proposed ILL-PLL has been fabricated in TSMC-0.18.

Design and Analysis of Thermal Management System of Power Matching Transmission in Energy Machinery

With the technical development of energy conservation and emission reduction technology, the internal structure of engineering machinery has become denser. The rising full-machine heat load that ensues challenges the effect of the cooling system. In the traditional thermal management system for the transmission in energy machinery, the cooling capacity does not fully match the load of each subsystem, and the thermal management components cannot adapt to the dynamic cooling demand of engineering machinery. To solve these problems, this paper designs and analyzes the thermal management system of power matching transmission in energy machinery. Firstly, the energy distribution among different components of engineering machinery, including, hydraulic system, transmission system, and cooling system, was described in each work section, and the dynamic matching method was detailed for hydraulic torque converter. Then, heat source engine, hydraulic torque converter, and hydraulic retarder were selected as the targets of thermal management for the power transmission system of loader. Next, the thermal management cycle was framed as a scheme in which the engine transmission system is independent with the cooling circulation system, and a heat transfer calculation model was constructed for loader transmission system. The proposed model was proved effective through experiments. The research results provide a reference for the thermal management of other subsystems of engineering machinery.