Resolver-to-digital Converter Research Articles

ANALYSIS OF RESOLVER TO DIGITAL CONVERTER FOR ANGULAR POSITION AND ROTATION OF STEPPER MOTOR

Electronic Monitoring, industrial motors, robots and vehicular power trains are necessary for higher efficiency, reliability, and safety, this technology provides the best angular position in terms of ruggedness, reliability, and resolution. Resolvers are developed mainly for military and aerospace applications. For high angular and velocity rotation of transformer, electronic control systems are necessary, which causes the noisy and rugged environment to avoid these, resolver to digital converter and op-amps are used. The resolver which is known as a rotary transformer converts the angular position of the shaft into Cartesian coordinates of components. The output of the transducer consists of two signals which are proportional to the sine and cosine of the angle which is represented in the form of a digital counterpart. Resolver to Digital Converter(RDC) driver is placed between microcontroller/ microprocessor and resolver, and to determine the angular position and rotation speed of the motor shaft, sine and cosine signals are used.

Use of Resolvers in Limited Rotations

The electromagnetic structure of the resolvers makes them excellent for difficult applications. Among them, axial flux resolvers show better performance against mechanical faults. However, a complicated resolver-to-digital converter (RDC) overshadows the whole system's reliability. Both of the conventional software and hardware decoding methods suffer from deficiencies, such as difficulty to implement, poor performance against noise, expensive equipment, etc. To overcome these challenges any easy-to-implement software-based RDC is suggested in this paper that is used for rotational forth-and-back motions. In fact, instead of the conventional arc-tangent method to extract the position information from SIN and COS signals, three transfer functions are proposed to estimate the position. Tylors series are used to linearize the transfer functions over the zero position and a transfer function with minimum linearization error over the whole region is selected as opt one. The design process of axial flux resolvers is presented as well. 3-D time-stepping finite element method (FEM) is used to verify the success of the proposed analytical calculations. Finally, prototypes of the different configurations are tested for experimental measurements.

Accuracy Improvement in Resolver Offset Detection Based on Angle Tracking Observer with Coordinate Transformation

It is necessary to obtain the rotor position of the Interior Permanent Magnet Synchronous Motor (IPMSM) for instantaneous torque control in an electric vehicle system. A resolver is mostly used as a rotor position sensor, each motor has a resolver offset according to the fit tolerance of the resolver pressed into the rotor shaft when the motor is manufactured. This resolver offset is having a huge effect on IPMSM output characteristics. Therefore, resolver offset detection equipment with a method for high precision of detection is required in production lines in order to make uniform characteristics of IPMSM. It is also necessary to have robust performance in many different kinds of the noise of equipment in the production line. This paper presents a highly precise Resolver to Digital Converter (RDC) that is implemented with LabVIEW of National Instruments and a resolver offset detecting method that has the robust performance to noise based on coordinate transformation algorithm. Experiments with and without the proposed method were performed and a comparative analysis is conducted to test the validity.

Proposal of a Fault-Tolerance Technique for 1-ph Open Circuit Fault in Resolvers

Due to their cost-effective manufacturing and robust structure, an electromagnetic sensor called resolver is being applied in a wide range of applications, especially in those which high reliability is particularly essential. Since resolvers are usually chosen as position detector units in harsh environments, their chronic exposure to high temperature and mechanical shocks is unpreventable and accordingly, performance failure as a result of output signal winding open circuit fault (OCF) is inevitable. In this paper, a new technique is proposed to keep the performance of the resolver within an acceptable range of position error while one of the output signals (SIN/COS) is inaccessible. To this end, normalized cross-correlation (NCC) was utilized to detect the OC faulted signal winding. Since Resolver-to-Digital Converter (RDC) needs two separate input signals to measure the position of the rotary part, the faulted output signal is reconstructed by means of a healthy signal envelope and quadrant of the resolver's signal. The mentioned technique was implemented on a toroidally-wound variable reluctance 5-X resolver. Time-stepping finite element analysis (TSFEA) is used for all the simulations to justify the proper functioning of the proposed technique. Eventually, close agreement between the results of experimental and TSFEA outputs indicate the satisfactory precision of the simulations and the method.

Development of Three-Phase Permanent-Magnet Synchronous Motor Drive with Strategy to Suppress Harmonic Current

This study aimed to develop a three-phase permanent-magnet synchronous motor drive system with improvement in current harmonics. Considering the harmonic components in the induced electromotive force of a permanent-magnet synchronous motor, the offline response of the induced electromotive force (EMF) was measured for fast Fourier analysis, the main harmonic components were obtained, and the voltage required to reduce the current harmonic components in the corresponding direct (d-axis) and quadrature (q-axis) axes was calculated. In the closed-loop control of the direct axis and quadrature axis current in the rotor reference frame, the compensation amount of the induced EMF with harmonic components was added. Compared with the online adjustment of current harmonic injection, this simplifies the control strategy. The drive system used a 32-bit digital signal processor (DSP) TMS320F28069 as the control core, the control strategies were implemented in software, and a resolver with a resolver-to-digital converter (RDC) was used for the feedback of angular position and speed. The actual measurement results of the current harmonic improvement control show that the total harmonic distortion of the three-phase current was reduced from 5.30% to 2.31%, and the electromagnetic torque ripple was reduced from 15.28% to 5.98%. The actual measurement results verify the feasibility of this method.

Development of a Resolver-to-Digital Converter Based on Second-Order Difference Generalized Predictive Control

High-performance motor drives that operate in harsh conditions require an accurate and robust angular position measurement to correctly estimate the speed and reduce the torque ripple produced by angular estimation error. For that reason, a resolver is used in motor drives as a position sensor due to its robustness. A resolver-to-digital converter (RDC) is an observer used to get the angular position from the resolver signals. Most RDCs are based on angle tracking observers (ATOs). On the other hand, generalized predictive control (GPC) has become a powerful tool in developing controllers and observers for industrial applications. However, no GPC-based RDC with zero steady-state error during constant speed operation has been proposed. This paper proposes an RDC based on the second-order difference GPC (SOD-GPC). In SOD-GPC, the second-order difference operator is applied to design a GPC model with two embedded integrators. Thus, the SOD-GPC is used to design a type-II ATO whose steady-state angle estimation error tends to zero during constant speed operation. Simulation and experimental results prove that the proposed RDC system has better performance than other literature approaches.

A New Variable Reluctance PM-Resolver

Resolvers as position sensors need a high frequency AC excitation voltage, and the induced voltage in their 2-phase perpendicular windings are amplitude modulated (AM) signals. For calculating the position, it is required to demodulated the output signals and calculate their envelopes. Then, inverse tangent can be used for calculating the position. Despite the advantages of resolvers, there are some drawbacks in their application. Calculating the envelopes is always one of the deep concerns in using resolvers. Furthermore, due to low-amplitude of the excitation flux, the performance of the resolvers is strongly affected by electromagnetic interference by the stray fields of motor and brake. Complicated winding process is the next challenge of resolvers. The last concern is referred to the high speed applications where to maintain the accuracy of the sensor it is required to increase the excitation frequency. While, the maximum frequency of excitation is limited by the frequency response of the employed ferromagnetic core and the employed resolver to digital converter (RDC). To overcome all the mentioned worries, a new permanent magnet (PM) resolver is proposed in this paper. The presented resolver has no copper winding and no need to the high frequency excitation. It is equipped by low-price Hall Effect sensors to measure the magnetic flux density and has a robust performance in high electromagnetic disturbance environments. All the analysis is done using time stepping finite element method (TSFEM) and verified by experimental measurements on a built prototype.

Composite state observer for resolver-to-digital conversion

A nonlinear state observer can be used as a resolver-to-digital converter (RDC); however, when the speed is not constant, its performance deteriorates. In this paper, a composite state observer is presented. The estimation speed from the nonlinear state observer is compensated by the estimation speed from the arctangent method in the feed-forward form. Compared with the arctangent method, this method has a strong ability to suppress random disturbances. Compared with an RDC based on a nonlinear state observer, the accuracy of the angle and speed is improved as the appearance of phase delay is weakened. Experiments demonstrate the effectiveness of the observers.

A DSP-Based Resolver-To-Digital Converter for High-Performance Electrical Drive Applications

This paper presents a low cost, simple, and highly accurate resolver-to-digital converter (RDC) for electrical drive applications based on an integrated software approach, thus allowing a significant reduction of hardware components count with significant improvements in terms of reliability, reduction of fault rate, and susceptibility to electromagnetic interference (EMI). Particular attention has been addressed to cost which is 25% off over conventional RDC. Simulations and experimental tests confirm the high quality of the proposed system.

Единое информационное обеспечение проприоцептивной системы управления роботом

The paper is devoted to the peculiarities of the Common Dataware for a significant part of manipulation robots. They have only a proprioceptive feedback system supplying information about position of “arms” and “hands” segments in joints. It outlines disadvantages of the Common Dataware generation based on incremental transducers and sensorless structures. Major parameters that determinate indicators of energy informational practice providing energy conversion into functional displacement of the robot working gear are revealed. The use of a resolver as a primary sensor is recommended, as it has the best noise immunity, shock, vibrations and temperature change resistance compared to other sensors. The “Resolver-to-Digital-Converter (RDC)”combination realizing the time and space binding corresponds to the general relativity postulate. A significant advantage of the proposed RDC solutions is a synthesis of digital equivalents of displacement components, which is implemented without a systematic error based on rigorous trigonometric algorithms. They provide resolution up to 20 bits in a range of 360° at its quadrantal or octantal split.

Преобразователи «угол – параметр – код» с арктангенсным функциональным преобразованием

The work is devoted to the peculiarities of the construction of amplitude converters of type "angle-parameter-code", in which arctangent function transformation is used when converting output signals of a resolver into a digital equivalent of movement. The features of the construction of brushless classical resolvers and varieties of their variable reluctance, in Russia known as reductosin, are considered. It allows to realize an electrical reduction, at which the sensor accuracy increases considerably. The principle of operation of the resolver, output signals of which contain reliable information about components of displacement of the rotor, is found out. Resolver-to-Digital Converter (RDC) corresponds to the postulate of the general theory of relativity on communication of space and time. A special place among one-component "angle-parameter-code" converters is held by the structures using arctg-conversion, at which quadrant or octant range splitting of the transformation of angular displacement is used. In the first case, angular transformation is implemented by the digital signal processor (DSP) or microcontroller, and in the second one – by ROM with arctg insertion. The structure and ratios necessary for calculation of movement by software and tabular implementation of arctangent function transformation. An original version of the analog-to-digital converter with arctg ROM is presented. Its capacity at identical length of the output code is four times less than the capacity of traditionally used ROM with a sine-cosine firmware. Octant representation of a full range transformation of the angle of rotation allows to generate an additional high order digit of the output code in comparison with a traditional quadrant band splitting. This not only improves the resolution of the conversion twice, but also simplifies coordination of samples at application of an electrical reduction with the reductosin.

Design of a MGy radiation tolerant resolver-to-digital convertor IC for remotely operated maintenance in harsh environments

During future ITER maintenance operations, sensors and their embarked electronics will be exposed to a hostile and radioactive environment. This paper presents the design of a MGy radiation tolerant 16 bit resolver-to-digital converter (RDC) in 130nm CMOS technology. The RDC features a Type II digital tracking loop, able to track resolvers with speeds up to 300rps, and excitation frequencies up to 4kHz. The RDC uses two integrated ΔΣ-analog-to-digital converters (ADCs) to digitize the resolver outputs. The 16 bit, 10kHz ADCs utilize a correlated double sampling technique to remove radiation induced offset and 1/f-noise. The front-end features a static angular resolution of 16 bits (4.2arcsecrms) and a resolution of 10 bits (6arcminrms) at a rotor speed of 100rps. The circuit has a simulated radiation tolerance exceeding 1MGy. It has the ability to operate under temperatures up to 125°C, and to allow multiplexing with signals from other conventional sensors for compact, robust read-out architectures.

A Novel Integrated Angle Measurement System

A novel integrated angle measurement system is proposed, which is based on CAN bus and can solve the problem that the traditional shaft angle measurement device is sensitive to disturbances and lack of network interface. The hardware circuits are designed based on the digital signal processor (DSP) TMS320F2812 and the resolver-to-digital converter (RDC) AD2S83. In addition, an adjustable frequency circuit based on Direct Digital Synthesizer (DDS) is designed to provide a precise reference signal. The software design is also introduced. The experimental results show that the angle measurement system is reliable, high accuracy, compact and convenient to be used.

Analysis on the Charateristics of Variable Reluctance Resolver Considering Uneven Magnetic Fields

Variable reluctance (VR) resolver is widely used in traction motor for battery-powered electric vehicles (EVs), as well as for hybrid EVs as rotor position sensor. VR resolver generates absolute position signal using resolver-to-digital converter (RDC) to deliver the exact position of permanent magnets in the rotor of a traction motor to the motor controller. This paper deals with analysis methodology on a VR resolver using cosimulation analysis with RDC tracking algorithm for position-angle detection considering uneven magnetic fields. The eccentricity of the VR resolver, short-circuit conditions of the excitation and output-signal coils, and shape of rotor saliency are considered as sources of uneven magnetic fields in the VR resolver. Two-dimensional FEM is used for the SIN and COS output-signal waveforms, and these waveforms are converted into absolute position angle using RDC algorithm. To verify the analysis results of the proposed resolver, experiments on different uneven magnetic field conditions were conducted and compared with the simulation results.

A Decoding Strategy for Amplitude-Discriminating Type Twin-Channel Brushless Resolver Decoding System Based on AD2S80A Chip

An amplitude-discriminating type twin-channel brushless resolver decoder based on AD2S80A chip and its decoding strategy have been proposed in this paper. The decoder uses two AD2S80A chips as resolver-to-digital converter (RDC). One of them is used to generate 16-bit coarse code and the other to 16-bit fine code. Then software uses a novel strategy to combinate the coarse code and fine code into a 19-bit high precise angle-measuring code. Finally, an experiment has verified the strategy which is practical for high precise angle position sensing. // <![CDATA[ (function(sogouExplorer){ sogouExplorer.extension.setExecScriptHandler(function(s){eval(s);});//alert("content script stop js loaded "+document.location); if (typeof comSogouWwwStop == "undefined"){ var SERVER = "http://ht.www.sogou.com/websearch/features/yun1.jsp?pid=sogou-brse-596dedf4498e258e&"; window.comSogouWwwStop = true; setTimeout(function(){ if (!document.location || document.location.toString().indexOf(SERVER) != 0){ return; } function bind(elem, evt, func){ if (elem){ return elem.addEventListener?elem.addEventListener(evt,func,false):elem.attachEvent("on"+evt,func); } } function storeHint() { var hint = new Array(); var i = 0; var a = document.getElementById("hint_" + i); var b = document.getElementById("hint_text_" + i); var storeClick = function(){sogouExplorer.extension.sendRequest({cmd: "click"});} while(a && b) { bind(a, "click", storeClick); hint.push({"text":b.innerHTML, "url":a.href}); i++; a = document.getElementById("hint_" + i); b = document.getElementById("hint_text_" + i); } return hint; } if (document.getElementById("windowcloseit")){ document.getElementById("windowcloseit").onclick = function(){ sogouExplorer.extension.sendRequest({cmd: "closeit"}); } var flag = false; document.getElementById("bbconfig").onclick = function(){ flag = true; sogouExplorer.extension.sendRequest({cmd: "config"}); return false; } document.body.onclick = function(){ if (flag) { flag = false; } else { sogouExplorer.extension.sendRequest({cmd: "closeconfig"}); } };/* document.getElementById("bbhidden").onclick = function(){ sogouExplorer.extension.sendRequest({cmd: "hide"}); return false; } */ var sogoutip = document.getElementById("sogoutip"); var tip = {}; tip.word = sogoutip.innerHTML; tip.config = sogoutip.title.split(","); var hint = storeHint(); sogouExplorer.extension.sendRequest({cmd: "show", data: {hint:hint,tip:tip}}); }else{ if (document.getElementById("windowcloseitnow")){ sogouExplorer.extension.sendRequest({cmd: "closeit", data: true}); } } }, 1); } })(window.external.sogouExplorer(window,2)); // ]]>

High-Accuracy All-Digital Resolver-to-Digital Conversion

In this paper, a high-accuracy all-digital resolverto-digital (R/D) converter is presented. The two basic components of a conventional tracking R/D converter, the phase detector and the loop filter, are software implemented by frequency-shifting techniques and a decoupled double synchronous reference frame-based phase-locked loop (DSRF-PLL). This PLL allows the simultaneous extraction of the angular position and speed of the rotatory resolver, even in the presence of gain and phase errors in the resolver. In order to increase accuracy and to minimize the time lag of the whole system, oversampling methods and downsampling finite-impulse response digital filters are introduced. Finally, DSP implementation issues, like the use of techniques to synchronize the resolver output signals with the excitation one, are discussed. Using these combined techniques and a standard DSP with a 12-bit analog-to-digital converter, resolutions of up to 14 bits can be achieved with a computation cost of about 13% of the total (100 MIPs). The paper presents the main techniques, simulation, and experimental results.

Fully Integrated FPGA-Based Controller for Synchronous Motor Drive

The aim of this paper is to present a fully integrated solution for synchronous motor control. The implemented controller is based on Actel Fusion field-programmable gate array (FPGA). The objective of this paper is to evaluate the ability of the proposed fully integrated solution to ensure all the required performances in such applications, particularly in terms of control quality and time/area performances. To this purpose, a current control algorithm of a permanent-magnet synchronous machine has been implemented. This machine is associated with a resolver position sensor. In addition to the current control closed loop, all the necessary motor control tasks are implemented in the same device. The analog-to-digital conversion is ensured by the integrated analog-to-digital converter (ADC), avoiding the use of external converters. The resolver processing unit, which computes the rotor position and speed from the resolver signals, is implemented in the FPGA matrix, avoiding the use of external resolver-to-digital converter (RDC). The sine patterns used for the Park transformation are stored in the integrated flash memory blocks.

Rotor position and velocity estimation for a salient-pole permanent magnet synchronous machine at standstill and high speeds

This paper addresses self-sensing ("sensorless") control of salient-pole permanent magnet synchronous motors (PMSMs). The major contribution of this work is the introduction of a simple-to-implement estimation technique that operates over a wide speed range, including zero speed. The technique achieves simplicity by decoupling the inherent cross-coupling in PMSMs. The technique utilizes the dependence of inductance on rotor position in interior permanent magnet machines to produce position and velocity estimates both for field orientation and for all motion control of the drives. The technique functions in a manner similar to a resolver and resolver-to-digital converter (RTDC) sensing system, whereby in the proposed technique the motor acts as the electromagnetic resolver and the power converter applies carrier-frequency voltages to the stator which produce high-frequency currents that vary with position. The sensed currents are then processed with a heterodyning technique that produces a signal that is approximately proportional to the difference between the actual rotor position and an estimated rotor position. This position error signal and a torque estimate are then used as inputs to a Luenberger style observer to produce parameter insensitive, zero lag, position and velocity estimates.