High Frequency Voltage Signal Research Articles

Sensorless Position Control of Permanent-Magnet Motors With Pulsating Current Injection and Compensation of Motor End Effects

The sensorless position control of permanent-magnet motors is successfully implemented by superimposing a high-frequency voltage signal on the voltage reference or adding a high-frequency current signal to the current reference. The former approach is usually preferred because of its simplicity, although the latter one may allow better performance. This paper presents a new algorithm for the sensorless control of low-saliency permanent-magnet synchronous motors based on high-frequency sinusoidal current signal injection into the <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">d</i> -axis. Different from the related literature, the position information is derived by analyzing the measured high-frequency currents. The amplitude of the <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">d</i> -axis voltage reference is also exploited to improve performance. A proportional-integral (PI) controller plus a resonant term (PI-RES) is adopted to ensure the accurate tracking of both the dc and high-frequency components of the <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">d</i> -axis current reference. The main advantages of the proposed approach are the increased accuracy and sensitivity with respect to the approach based on voltage injection, the insensitiveness to inverter nonlinearities that are compensated by the current regulation loop, the actual control on the injected current value, and the practical absence of acoustic noise. Experiments on a linear tubular permanent-magnet synchronous motor prototype have been carried out to verify the aforementioned advantages. This paper also presents a discussion of the parameters of the PI-RES.

End Effects in Linear Tubular Motors and Compensated Position Sensorless Control Based on Pulsating Voltage Injection

The sensorless position control of permanent-magnet (PM) synchronous motors can be successfully implemented by superimposing a high-frequency voltage signal on the control voltage. In this paper, the position estimation is obtained by means of a high-frequency sinusoidal voltage signal injected along the estimated -axis. Several methods proposed in the literature obtain the position estimation by tracking the zero condition of the high-frequency current component. We propose a new approach that also exploits the -axis high-frequency current component and allows working with injected voltage signal of reduced amplitude, thus reducing noise and additional losses. The main contribution of this paper relies in the compensation of the motor end effects due to the finite length of the tubular motor armature. These effects must be taken into account in the motor modeling because they cause an error in the position estimation that varies with the motor position. The modeling of the phenomenon and a proper compensation technique are proposed in this paper. Last, a simplified integral-type controller is used to estimate motor position instead of the commonly adopted proportional-integral controller plus integrator, and this requires a low-effort design. Experiments on a linear tubular PM synchronous-motor prototype are presented to validate the theoretical analysis and evidence the feasibility of the proposed sensorless technique.

Low-noise real-time measurement of the position of movable structures in MEMS

A low-noise, low-perturbing electrostatic position measurement system for capacitive MEMS sensors is described. A small-amplitude, high-frequency voltage signal is applied between the movable and fixed plates of the sensing capacitance. The resulting current is modulated by the external forces applied to the structure. This high-frequency-shift makes it possible to filter low-noise contributes and minimize readout electrostatic perturbations on the device. Experimental results are reported for a comb-type MEMS test structure with quasi-static, sinusoidal, and impulsive forces. Resolution and long-term stability of nanometric values have been obtained.

Study on estimation of rotor position of self-sensing active magnetic bearings

The self-sensing principle of self-sensing active magnetic bearings(SSAMBs) is introduced, and a self-sensing configuration based on the current amplitude modulation is explored. The inductance coefficient is the function of rotor displacement, so the voltage of the electromagnetic coil is the function of rotor displacement too. Add a high-frequency signal to the input of linear power amplifier for amplitude modulation, and then let the coil voltage go through the syntony circuit to extract the high-frequency voltage signal containing the displacement signal and perform demodulation. After commutating the demodulated voltage signal, the pulsed DC voltage signal is gained. Lastly, through the lowpass, the smooth DC voltage signal reflecting the rotor displacement is gained. Convert this signal to feedback signal to control the rotor position. Simulations are completed, and the results show that this system is successful in sensing the rotor position and this approach is feasible.

Fault detection, classification and faulted phase selection approach based on high-frequency voltage signals applied to a series-compensated line

An approach to line protection that is based on fault characteristics extracted by means of wavelet transforms is presented. Analysis of the spectral energy of the phase voltage signals for different frequency bands enables faults to be detected, classified and faulted phases selected. The proposed approach points to the development of ultra-high-speed protective relaying and has been applied to a series-compensated line. The system has been simulated with MICROTRAN and the protection with MATLAB. The results show the feasibility of implementing this algorithm.

A Study of Sensorless Control of Induction Motor at Zero Speed Utilizing High Frequency Voltage Injection

A detailed investigation of sensorless control of induction motor at zero and very low speed based on injection of a pulsating high frequency voltage signal is presented. A sensing technique is based on the secondary effect of magnetic spatial non-linearity caused by saturation of the stator laminations. Experimental and finite element results are presented.

Sensorless drive of surface-mounted permanent-magnet motor by high-frequency signal injection based on magnetic saliency

This paper presents a new sensorless control scheme of a surface-mounted permanent-magnet (SMPM) motor using high-frequency voltage signal injection method based on the high-frequency impedance difference. In the SMPM motor, due to the flux of the permanent magnet, the stator core around the q-axis winding is saturated. This makes the magnetic saliency in the motor. This magnetic saliency has the information about the rotor position. The high-frequency voltage signal is injected into the motor in order to detect the magnetic saliency and estimate the rotor position. In this paper, the relationship between the high-frequency voltages and high-frequency currents is developed using the voltage equations at the high frequency, and the high-frequency impedance characteristics are analyzed experimentally under various conditions. The proposed sensorless control scheme makes it possible to drive the SMPM motor in the low-speed region including zero speed, even under heavy load conditions. The experimental results verify the performance of the proposed sensorless algorithm.

Controller Design of Sensorless Induction Machine by High Frequency Voltage Injection

This paper describes a new sensorless induction motor drive scheme by injecting high frequency voltage signal. The signal is not a rotating one, but a fluctuating one at a synchronous rotating reference frame with the fundamental stator frequency. The difference of impedance between the flux axis and the quadrature axis at high frequency signal injection on the rotor flux angle is used to track the rotor flux angle. Since the injection signal is independent on the stator frequency, the monitoring of the differences of impedance can be done even at stand still condition of motor. Speed and current controller suitable for high frequency voltage injection are designed and verified by experiments.

A novel non-unit protection for series compensated EHV transmission lines based on fault generated high frequency voltage signals

A new high-speed protection technique based on fault generated high frequency (HF) voltage signals is developed and applied to the protection of EHV series compensated power transmission lines. It is a nonunit protection technique as it relies totally on locally derived information, but it has the discriminative properties normally associated with unit protection schemes. The protection scheme has been designed using CAD techniques including emulation of analogue interfaces and hardware. It is shown that the new relay scheme is able to overcome many difficult protection problems encountered on such EHV power lines using conventional methods, and discriminates clearly between internal and external faults, producing a fast trip output.

Preventive Equipment for Urinary Incontinence: A Device Employing Lower Abdominal Impendance Changes

The object of this work was to develop a monitoring device for measuring the volume of urine in the bladder to signal, in advance, the need to urinate and thus help prevent urinary incontinence. A high-frequency electric current of 50 KHz transmitter was applied to a pair of terminals placed on the surface of a human body. The constant current was 2mA (p-p). A pair of voltage electrodes was placed in the path of the electric current to pick up high-frequency voltage signals. The best position for current electrodes was found to be on the surface of both femoral joints. Positioning the voltage electrode above the bladder on the lower abdomen was most efficient for detecting the volume of urine. New current electrodes sutured onto underpants were fitted on the surface above the femoral joints, which did not shift in the case of movement by the subjects. The reproducibility and stability were remarkably good with this electrode. The alarm level which foretold both maximum storage volume and maximum desire to void was examined. After that, when the alarm level was set within the range of impedance charge, 60% to 70%, the possibility of prediction of urination exists.

Digitally simulated test performance of the Pramod scheme for UHS protection of EHV transmission lines

The author describes a digital simulation technique for the signal processing of the Pramod scheme and studies the digitally simulated test performance of the scheme for satisfactory operation under different fault conditions. The Pramod scheme is based on the detection of high-frequency voltage signals through stack tuners. It is assumed that the digitally simulated stack tuner output signals are available for the purpose of the signal processing under different fault conditions. The Pramod scheme has been investigated for the discrimination feature of reverse fault, faults at different points of the transmission line, and different types of faults, and the performance has been found satisfactory.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

An investigation into a method of detecting the fault induced high frequency voltage signals of EHV transmission lines for protection applications

A method is investigated for detecting the fault-induced high-frequency voltage signals of the EHV transmission lines for protection applications. The method is based on the principle of a power line carrier communication system using a stack tuner for detecting the high-frequency voltage signals in a particular frequency bandwidth. The digitally simulated fault responses of different frequency bandwidths in the kilohertz range and at different fault inception angles of the voltage waveform are studied.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

An Investigation into a Method of Detecting the Fault Induced High Frequency Voltage Signals of EHV Transmission lines for Protection Applications

An Investigation into a Method of Detecting the Fault Induced High Frequency Voltage Signals of EHV Transmission lines for Protection Applications

The use of current amplifiers for high performance voltage applications

A current amplifier is used to realize a voltage amplifier having an improved high frequency response and slew rate capability. It is shown that the closed loop bandwidth is independent of the closed loop voltage gain. The design and application of a unity gain and a high gain current amplifier to voltage signal processing circuits are given. The results demonstrate an efficient use of the inherent frequency response capabilities of the active devices in the circuit to achieve the amplification of high frequency and large amplitude voltage signals.