Motor Phase Voltage Research Articles

Analysis of the Phase Voltage of an Induction Motor of an Adjustable Electromechanical System

Analysis of the Phase Voltage of an Induction Motor of an Adjustable Electromechanical System

A Variable Speed Induction Motor Drive With 24-Stepped Voltage Waveform Throughout Modulation Range

Multi-level inverters produce low order harmonics in over-modulation region, which can be eliminated by generating polygonal space vector structure. A variable speed induction motor drive to generate 24-stepped voltage waveform throughout modulation range is proposed in this article. An open-end winding configuration induction motor (OEIM) is fed with primary and secondary inverter from both the ends of OEIM and generates a 24-stepped phase voltage. The proposed scheme also produces 96-stepped phase voltage waveform at extreme modulation index with highly suppressed higher order harmonics and excellent quality phase voltage. The motor terminal sees a 24-stepped waveform at all speeds, devoid of low order harmonics up to <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$19^{th}$</tex-math></inline-formula> order. The scheme does not require vector timing calculation due to availability of highly dense 24-sided polygonal structure. Primary and secondary inverters are derived by cascading flying capacitor and CHB cells. Experimental verifications are performed on in-house developed laboratory prototype. Motor phase voltage and phase current waveforms during steady state and transient conditions justifies performance of the proposed scheme. Dynamic performance and floating capacitors voltage balancing method are verified by experimental results.

Badania przyczyn niepożądanej synchronizacji prędkości obrotowej silnika z częstotliwością modulacji PWM w układzie napędowym PM BLDC

In a drive system comprising a high-speed PM BLDC motor and an inverter implementing motor phases commutation and phase voltages PWM modulation, a spontaneous synchronisation between the PWM modulation frequency and the motor rotational speed may occur. The drive behaves like an unintended phase-locked loop. The effect distorts mechanical characteristic of the drive by introducing flat segments where the rotational speed remains constant despite changing load torque. It makes the speed-torque relationship discontinuous, nonlinear, and non-unique. The phenomenon is closely related to the problem of phase current and motor torque ripples. The paper presents experimental results recorded with a laboratory test bench for drives for electric power tools where the phenomenon of the parasitic speed locking has been observed. A root cause of this effect is discussed, and the mechanism of unwanted synchronisation is investigated. Several mitigation techniques are proposed and verified with computer simulations.

Dual, Three-Level, Quasi-Z-Source, Indirect Matrix Converter for Motors With Open-Ended Windings

In this paper, a novel variable-voltage, variable-frequency, dual, three-level, quasi-Z-source, indirect matrix converter topology is proposed, including a detailed description of a modulation method and a control strategy for three-phase motors with open-ended windings. The proposed power drive system (PDS) supports bidirectional power flow and has a combined control of DC-link voltage and output AC voltage frequency. Experimentally validation was performed on a 4-kW PDS. For a given supply voltage amplitude and the same power switch voltage rating in the DC/AC converter, the proposed PDS can double the voltage output gain, thus being an interesting solution for high-power applications with motors designed for higher voltages. The proposed PDS topology, modulation method and motor control strategy can reduce the common-mode component, low-order harmonic content, peak values and d <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">v</i> /d <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">t</i> of the motor phase voltage, ultimately leading to lower winding insulation voltage stress at low-speed, low-voltage operation, lower harmonic losses in the motor, and ride-through capability over voltage sags in the mains, which are important advantages.

Modulating Wave-Based Timing Calculation for a Multilevel 24-Sided Polygonal Voltage Space Vector Structure With Similar Triangles

This article proposes a multilevel 24-sided polygonal voltage space vector structure (VSVS), eliminating lower order harmonics up to 19th order and suppressing higher order harmonics in motor phase voltage throughout the modulation range. Unlike switched average vectors in literature, the proposed scheme generates real active vectors that have the advantage of less switching frequency operation. The proposed VSVS consists of two concentric polygons divided into similar triangles resulting in a simple modulation algorithm. Instantaneous error in phase voltage reduces due to the multilevel property of the proposed VSVS. The proposed scheme extends the dc bus utilization and linear range of operation. The proposed scheme is implemented on an open-end winding induction motor fed with primary and secondary inverters from either end. This article also presents a modulating wave-based method to compute nearest vector timings using sampled reference waves only. Unlike conventional methods, the proposed timing calculation method does not require trigonometric operations, sorting algorithms, and iterative search algorithms. Experimental verification of the proposed scheme is performed to validate the concept. Switching loss and Fourier analysis comparison with some existing schemes is also presented.

A Single DC-Link Multilevel 42-Sided Polygonal Voltage Space Vector Generation With Lower Order Harmonic Suppression Using Switched-Capacitor Filter

In this work, a multilevel 42-sided polygonal space vector structure for suppression of lower order harmonics for open-end induction motor (OEIM) drive applications is proposed. The proposed power circuit topology consists of two inverters feeding an OEIM from either side. The main inverter fed with a single dc-link providing active power for motoring operation is switched at low switching frequency. The secondary inverter fed with a capacitive supply is switched at high frequency to suppress lower order harmonics upto 39th order, up to the base speed of operation allowing maximum utilization of the dc-link. The advantages of lower order harmonic suppression in motor phase voltage, for polygonal space vector structures, are combined with multilevel inverter topology. This offers various advantages like multilevel operation with low inverter switching for the main power delivery inverter and harmonic suppression throughout the modulation range. The low switching frequency primary inverter generates harmonics of the order <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$6*k \pm 1$</tex-math></inline-formula> , where <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$k = 1, 2, 3,{\ldots }$</tex-math></inline-formula> . The harmonics are suppressed by the capacitor-fed secondary inverter, which supplies only reactive power for suppression of lower order harmonics in motor phase voltage. Use of a single dc-link facilitates four-quadrant operation of the inverter. The proposed scheme is validated for steady-state and dynamic performance by experimental results.

A Fault-Tolerant Inverter Circuit to Generate Thirteen-Level 24-Sided Voltage Space Vector Structure for Open-End Winding Induction Motor Drive

An inverter circuit to generate a 13-level 24-sided polygonal voltage space vector structure (VSVS) comprised of 288 real active vectors and a zero vector is proposed in this article. The proposed scheme eliminates lower order harmonics up to 19th order and suppresses higher order harmonics from motor phase voltage in the full modulation range. The 48-step operation of the proposed scheme highly improves phase voltage quality at full speed. The dc bus utilization of the proposed scheme is improved to 99.42% compared to 90.6% multilevel hexagonal VSVS. The proposed topology has inherent capacitor balancing in every sampling interval at any loading condition using pole voltage redundancies. Multilevel property of the proposed scheme reduces instantaneous error in phase voltage compared to two-level 24-sided polygonal VSVS. Generation of real active vectors reduces instantaneous error in phase voltage and reduces switching frequency compared to switched average techniques existing in the literature. Fault-tolerant feature of the proposed scheme improves the availability of the drive system. Experimental results are provided to validate the steady-state operation, capacitor balancing, transient performance, and fault-tolerant capability of the proposed scheme. The comparison of switching loss and harmonic performance of the proposed scheme is performed with existing topologies.

A Fault-Tolerant 24-Sided Voltage Space Vector Structure for Open-End Winding Induction Motor Drive

This article proposes a method of generating 24-sided polygonal voltage space vector structure composed of 24 real active vectors and a zero vector. Each active vector is a real vector in contrast to switched average vectors in literature. Generation of real 24-sided vectors minimizes switching losses and improves quality of phase voltage compared to switched averaged vectors technique. An important feature of the presented scheme is elimination of lower order harmonics up to 19th order from motor phase voltage throughout the modulation range that gives reduction in torque pulsation and near sinusoidal phase current. The proposed scheme extends the linear modulation range till 99.42 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$\%$</tex-math></inline-formula> . Open-end winding induction motor is fed with primary and secondary inverters from either ends. Primary and secondary inverters are implemented by cascading two-level inverters. DC sources for both the inverters are realized using a simple star-delta transformer combination. The proposed concepts are verified with laboratory prototype and the respective results during the steady-state, transient, and fault scenario are presented. The supporting loss analysis and harmonic performance of the proposed drive is performed with existing topologies.

A Dense Multilevel 30-Sided Space Vector Generation Using a Single DC Link for an Induction Motor Drive

Modulation using a higher sided polygonal space vector structure (SVS) is an elegant method to increase the linear modulation range and to eliminate the undesired lower order harmonics from motor phase voltage. This article presents the generation of a dense 15-concentric 30-sided multilevel SVS using a single dc-link for an open end induction motor (OEIM) drive. The proposed scheme eliminates lower order harmonics till 25th order from motor phase voltage throughout the modulation range. The <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$dv/dt$</tex-math></inline-formula> stress in the phase voltage applied to the motor will also be highly reduced owing to the multilevel structure. The pulsewidth modulation scheme employed utilizes the denseness of SVS and avoids iterative searches to find the triangle, which encompasses the tip of reference voltage vector, which are typical in multilevel polygonal SVS. The topology consists of an active dc-link fed three-level primary inverter and a capacitor fed five-level secondary inverter connected to either end of an OEIM. The primary inverter acts as the active power supplier for the drive and the secondary inverter filters out the undesirable lower order harmonics from motor phase voltage. The proposed scheme is experientially validated and the results are included in this article.

Current Ripple Reduction of Predictive Torque-Controlled Induction Motor Drive Using Delta-Star Switchover

The current and torque ripple of inverter-fed induction motor drives is an inherent problem of control strategies working with switching frequencies in the range of multiple kilohertz, such as direct torque and, more recently, predictive torque control. If the drive operates in a wide-speed and wide-torque range and is equipped with a machine with an accessible terminal block whose winding is nominally connected in delta, then the current and torque ripple can be reduced by utilizing the delta-star winding changeover technique. When the winding configuration is switched from delta to star, the instantaneous motor phase voltage peak is lowered, and its total harmonic distortion is reduced. However, the control strategy must be adjusted according to the actual winding topology, mainly due to the difference in the coordinate transformations of the measured currents and the difference between the phase voltage vectors obtained from the inverter. This paper proposes a predictive torque control of an induction motor drive with a switchable delta-star winding configuration. The paper is supported by theoretical background, and the key idea is verified by simulations in MATLAB/Simulink and experiments conducted on a dSPACE-controlled 5.5-kW laboratory drive. The simulations validated the presented equations and show the effects of not respecting the actual winding topology. The experiments mainly focused on analyzing the total harmonic distortion of the currents and consumed electrical power in multiple operating points.

A Very High Resolution 30-Sided Space Vector Generation From a Single DC-Link for Induction Motor Drives

A voltage source inverter generating a polygonal voltage space vector structure (SVS) having 117- concentric 30-sided polygons of different radii are proposed. Modulation using a 30-sided SVS eliminates lower order harmonics till 25th order from motor phase voltage. The proposed scheme combines the advantages of a 30-sided SVS with that of a multilevel inverter. The topology consists of two cascaded five-level inverters feeding from either end of the open-end induction motor stator windings. One of the cascaded five-level inverter is connected to an active dc source and delivers the required active power for the scheme, while the other is capacitor fed and acts as a switched capacitive filter. In this article, nonaligned 30-sided polygons, i.e., regular 30-sided polygons that are not symmetric with respect to <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$\alpha$</tex-math></inline-formula> and <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$\beta$</tex-math></inline-formula> axis are also considered for inverter operation. The harmonic analysis of such nonaligned 30-sided polygons is investigated in this article. Nearest level switching is employed throughout the modulation range, enabling further reduction of switching loss in the system. Extensive hardware experimentations are carried out to validate the proposed scheme and the results are included in the article.

Improved Dynamic Performance of Permanent Magnet Synchronous Motor using Maximum Torque Per Ampere with reduced number of switches

To attain the excellent dynamic performance of any drive the torque ripples must be as minimum as possible. Otherwise which leads to oscillations in a speed profile and hence results in poor performance of a drive. The proposal of this work is to reduce as minimum as possible in torque ripples of a Permanent Magnet Synchronous Motor (PMSM) by means of a Five Level Space Vector Modulation (SVM). The SVM is used to generate gate pulses for an Inverter. Maximum Torque per Ampere (MTPA) is considered which ensures minimum ohmic losses. To reduce the reduces number of switching states and hence switching losses and to generate gate pulses to a five level inverter, three level inverter using SVM is taken as a reference. To verify the designed system, a simulator is implemented in MATLAB software environment and a comparison of results with and without MTPA control is being shown. Results clearly show that torque ripple, THD of motor phase voltage and current are greatly reduced under MTPA control.

A Multilevel 30-Sided Space Vector Structure With Congruent Triangles and Timing Calculation Using Only Sampled Reference Voltages

In this article, a multilevel inverter scheme to generate a 30-sided space vector structure (SVS) with congruent triangles is proposed. The 30-sided SVS eliminates all the lower order harmonics till 25th order from motor phase voltage throughout the modulation range. The proposed scheme is implemented using a single dc-link on an open-end induction motor (OEIM). The OEIM is fed with primary inverter from one end and secondary inverter from the other end. Primary inverter is fed from an active dc-link and supplies all the required active power for the scheme. Secondary inverter is a capacitor fed inverter, which acts as the switched capacitive filter. In this work, a simple algorithm is proposed, which calculates the timings required for a 2-level 30-sided SVS from sampled reference voltages. The algorithm requires only simple operations such as addition, multiplication, and comparisons. From the obtained timing values, the space vector location of three nearest multilevel 30-sided vectors and its time duration can be identified. The feasibility of the proposed scheme is proved by experimental results.

Beat Phenomenon Suppression for Reduced DC-Link Capacitance IPMSM Drives With Fluctuated Load Torque

Beat phenomenon is an important concern in the reduced dc-link capacitance motor drive system. In previous research works, the topic is mainly concentrated on the beat phenomenon caused by the interaction of the fluctuated dc-link voltage and the motor phase voltage. In this paper, another form of the beat phenomenon generated by the fluctuated dc-link voltage and the severely fluctuated load torque is investigated. The effect of the beat phenomenon on the grid current and the motor speed is analyzed, which fluctuate with the low-frequency oscillation. In order to improve the drive system performance, a power balancing controller is proposed to suppress the grid current fluctuation, and a resonant controller is utilized to regulate the periodic power signals. Meanwhile, the applied fluctuated torque suppression method could improve the performance of the motor speed, which is only sensitive to the frequency of the fluctuated load torque. Experimental results are provided to verify the effectiveness of the proposed method.

A Switched Capacitive Filter-Based Harmonic Elimination Technique by Generating a 30-Sided Voltage Space Vector Structure for IM Drive

This paper proposes a novel polygonal voltage space vector structure (SVS) having 30 sides, for a star-connected induction motor drive. The SVS eliminates the presence of harmonics up to 25th order from motor phase voltage throughout the entire modulation range, providing a torque profile devoid of lower order pulsations. Linear modulation is extended till 99.63% of base speed without exceeding the motor phase voltage rating. Topology consists of a dc-link fed primary inverter and two equal low voltage modular capacitor fed secondary inverters. Here the harmonics generated by the primary inverter is canceled by the secondary inverter which acts as a switched capacitive filter. Detailed description of the SVS generation and timing calculations are provided in this paper. Effectiveness of the proposed scheme is validated using experimental results, inverter loss calculations, and harmonic analysis.

A Novel Wheel Skid Control Based On Motor Energy Distribution Model

How to realize wheel slip control with parameters that can be measured and not relying on hardware precision is a difficult problem in vehicle traction control. From the point of view of energy transfer, this paper uses the feature that the rotational kinetic energy of the wheel increases abnormally when slipping, and proposes a wheel slip control method based on the motor energy distribution model. This method only requires the motor phase voltage, phase current and wheel speed that are easy to measure. In this paper, a complete vector control model of permanent magnet synchronous motor is established, and a PI control algorithm framework is built based on one-wheel vehicle model. The simulation results verify the effectiveness of the proposed algorithm.

Research on Energy Efficiency System of New Energy Vehicle Electric Drive

The motors of new energy vehicles adopt the built-in permanent magnet synchronous motor (PMSM) with high system efficiency. The mainstream control method of electric drive system is space vector PWM (SVPWM) algorithm. The SVPWM algorithm has higher low-order harmonic content in the low-speed segment voltage waveform, large asynchronous motor torque, and large motor iron loss, which makes the electric drive system less efficient in the low-speed segment system. This paper creatively proposes to change the modulation ratio M of the SVPWM waveform by adjusting the bus voltage, switching frequency and different control angles to reduce the harmonic content of the system to improve the overall efficiency of the electric drive system. In this paper, a theoretical model is established for the motor phase voltage harmonics, and various factors and components affecting the harmonic content are analyzed. Combined with the digital signal processor (DSP) based SVPWM vector control algorithm, the motor control SIMULINK simulation system is built. The voltage harmonic analysis of the simulation system is carried out by using the FFT tool in POWERGUI. The electric drive system bench is established for testing, the electric drive system simulation and the test bench test data are analyzed, and a clear method and means are proposed to reduce the harmonic content.

Discontinuous decoupled SVPWM schemes for a four‐level open‐end winding induction motor drive with waveform symmetries

A four-level open-end winding induction motor drive (OEWIMD) is realised by feeding the open stator windings of a three-phase induction motor from either end with two-level voltage source inverters (VSIs). These VSIs are operated with unequal DC-link voltages, which are in the ratio of 2:1. This circuit configuration has the disadvantage of overcharging the DC-link capacitor of the inverter operated with the lower input voltage. Decoupled space vector pulse-width modulation (DSVPWM) schemes, which were suggested in the previous literature to circumvent this problem, result in higher switching power loss in the dual-inverter topology. It is known that the discontinuous pulse-width modulation (PWM) schemes reduce the switching power loss. However, lack of structural symmetry of the power circuit renders it unwieldy to devise these PWM schemes. This study explores the applicability of discontinuous decoupled SVPWM (DDPWM) techniques for the four-level OEWIMD, without compromising on the waveform symmetries. With the aid of an improvised loss model, it is shown that these PWM schemes achieve the reduction of the overall loss of the four-level OEWIMD compared to the DSVPWM schemes. It has also been observed that one of the proposed DDPWM schemes result in reduced dv⁄dt in the motor phase voltages.

A Voltage Space Vector Diagram Formed by Nineteen Concentric Dodecagons for Medium-Voltage Induction Motor Drive

In this paper, a multilevel dodecagonal voltage space vector structure with nineteen concentric dodecagons is proposed for the first time. This space vector structure is achieved by cascading two sets of asymmetric three-level inverters with isolated H-bridges on either side of an open-end winding induction motor. The dodecagonal structure is made possible by proper selection of dc link voltages and switching states of the inverters. The proposed scheme retains all the advantages of multilevel topologies as well as the advantages of dodecagonal voltage space vector structure. In addition to that, a generic and simple method for calculation of pulsewidth modulation timings using only sampled reference values ( $v_\alpha$ and $v_\beta$ ) is proposed. This enables the scheme to be used for any closed-loop application such as vector control. In addition, a new method of switching technique is proposed, which ensures minimum switching while eliminating the fifth- and seventh-order harmonics and suppressing the eleventh and thirteenth harmonics, eliminating the need for bulky filters. The motor phase voltage is a 24-stepped waveform for the entire modulation range thereby reducing the number of switchings of the individual inverter modules. Experimental results for steady-state operation, transient operation, including start-up have been presented and the results of fast Fourier transform analysis is also presented for validating the proposed concept.

Benefits of Direct Phase Voltage Measurement in the Rotor Initial Position Detection for Permanent-Magnet Motor Drives

This paper shows how the problem of estimating the initial rotor position in permanent-magnet sensorless drives can benefit from the availability of a direct measurement of motor phase voltages. Two different estimation methods are presented for this purpose. The first is a readjustment of a classic procedure based on the detection, by means of the injection of voltage test pulses, of inductance variations due to motor saliencies, from which it is then possible to infer the position of the rotor. Since the application of irregular test pulses may increase the estimation uncertainties, the available voltage measurement is exploited to implement a closed-loop amplitude control of the test pulses. The second method is introduced both to overcome an issue related to the digital measurement approach adopted in this paper and to allow position estimation even in a motor with no relevant saliency, a case for which the first method is inappropriate. The effectiveness of the proposed solutions is validated by several experimental tests, which are carried out on two motors with different saliency properties.