No abstract

No abstract

Based on the back electromotive force (back-EMF) detection, a novel rotor position estimation strategy with adjustable turn on/off angle is proposed for the high-speed hybrid switched reluctance motor (SRM). The minimum back-EMF position is captured in every electrical cycle for rotor position estimation. The current comparator is employed to send out a turnoff signal for phase winding when the maximum inductance position is detected in the first electrical cycle. By providing sufficient current rise time to the phase winding, the proposed sensorless control system enables the motor to run in high-speed application. Besides the straightforward estimation principle, the proposed strategy has the implemental feasibility by eliminating extensive calculations and complicated look-up tables. The experimental results of a prototype are demonstrated to verify the proposed sensorless control system.

-This paper presents a novel scheme to estimate the rotor position of a single-phase hybrid switched reluctance motor (HSRM). The back-EMF generated by the permanent magnet (PM) field whose performance is motor parameter independent is adopted as an index to achieve the sensorless control. The differential value of back-EMF is calculated by hardware and processed by DSP to capture a fixed rotor position four times for every mechanical cycle. In addition, to accomplish the normal starting of HSRM, the determination method of the turn-off time position at the first electrical cycle is also proposed. In this way, a sensorless operation scheme with adjustable turn on/off angle can be achieved without substantial computation. The experimental verification using a prototype drive system is provided to demonstrate the viability of the proposed position estimation scheme.

No abstract

No abstract

No abstract

Accelerometers have a wide range application in many fields, such as airbag deployment system and electronic stability control system in vehicles, and inertial navigation system in aircrafts and rockets. As Micro-Electro-Mechanical System (MEMS) technology advances, accelerometers are made smaller and smaller, often integrated in a single chip, with lower implementation costs and power consumptions. Modern MEMS accelerometers can be used in portable devices such as cell phones, RFID tags and even integrated in other sensors. This paper presents chip-level design and implementation of a second order sigma-delta interface circuit used in capacitive microaccelerometers. The interface circuit provides 1-bit data stream and operates at a sampling frequency of 2.5MHz. The system model considers non-ideal factors in the circuit such as nonlinear distortion and noises. These non-ideal factors have been discussed through system level simulation in MATLAB. The micro-accelerometer, which is a highly integrated MEMS device, is then designed and implemented in silicon-on-insulator (SOI) substrate. Finally, the chiplevel layout of interface circuit is implemented. Results have shown the chip with area of 1.32mm 2 and power consumption of about 5mW.