Output LC Filter Research Articles

A New Voltage Control Method for Single-Phase PWM Inverters

A new voltage control method for single-phase full-bridge PWM inverters that having an output LC filter is proposed in this paper. The proposed voltage controller has a capability to realize a zero steady- state output voltage error with fast response. The zero steady-state output voltage error is achieved by using a controller that is derived by using the virtual LC resonant circuit. Fast response is obtained by using a virtual resistance that is connected in parallel with the filter capacitor. The validity of the proposed method is verified by experimental results. A new voltage control method for single-phase full-bridge PWM inverters is proposed in this paper. The proposed voltage controller has capability to realize a zero steady-state output voltage error with fast response without complicated transformation. To control the output voltage, a voltage control based on new virtual LC resonant circuit is proposed. By using the proposed control technique, a zero steady-state error can be achieved. In order to improve the output voltage response, a virtual resistor is connected in parallel with the output filter capacitor. Two types of virtual resistance are discussed in this

Design of a Photovoltaic Simulator With a Novel Reference Signal Generator and Two-StageLCOutput Filter

This paper presents a systematic design technique for a photovoltaic (PV) simulator. The proposed technique helps to improve control loop bandwidth and system response. The PV equivalent circuit is used to generate the current-voltage reference curves. A novel technique is proposed and implemented with analog controllers to simplify the reference signal generator, and to avoid computation time delays in digital controllers. A two-stage LC output filter is implemented to push the resonant frequency higher, and thus, allowing a higher bandwidth control loop design while keeping the same switching ripple attenuation as in the conventional one-stage LC output filter. Design procedures for both control and power stage circuits are explained. Experimental results verify the steady state and transient performance of the proposed PV simulator at 2.7 kW output.

Feedback Linearization Control of Three-Phase UPS Inverter Systems

In this paper, a feedback linearization technique is proposed to control the output voltage control of three-phase uninterruptible power supply systems. First, a nonlinear model including the output LC filters is derived from the power balance condition between the inverter output terminal and the load side. Then, input-output feedback linearization is applied to the nonlinear model to make it linear. The controller of the linearized model is designed by linear control theory. The tracking control law is obtained with a pole placement technique. It is shown experimentally that the proposed control scheme gives high dynamic responses in response to load variation as well as a zero steady-state error.

Synchronous control of indirect matrix converter for three-phase power conditioner

This paper describes an average model of indirect matrix converter (IMC) with an output LC filter in stationary and rotating reference frames. The developed model is non-linear and should be linearized in order to design linear controllers. Transient performance of the IMC is compared with that of conventional inverter in classic AC/DC/AC system. In order to make the IMC applicable for power conditioner applications a synchronous controller is designed. A power conditioner acts in one or more ways to deliver a voltage of the proper level and characteristics to enable load equipment to function properly. In order to afford the power conditioner requirements the controller has two segments. One segment controls the IMC with balanced input supply voltage and the other controls the system with unbalanced input supply voltage. The system can provide balanced output voltages with slight distortion of line side currents. Theory analyses, the model validation and simulation results are presented to verify the effectiveness of this control method.

Filterless class D amplifiers: power-efficiency and power dissipation

Filterless Class D amplifiers are based on the tri-state modulation architecture. In this study, the authors show that it is possible to employ the conventional Class D amplifier (that requires an LC output filter) as a filterless amplifier (hence not requiring the LC filter) if certain circuit conditions are satisfied – specifically a sufficiently high carrier frequency and a loudspeaker with sufficient inductance. As the high-frequency (beyond the audio range) components of the tri-state modulation and of the conventional modulation are dissipated in the loudspeaker, the rating of the loudspeaker would need to accommodate not only the audio signal power but also the power, Psw, due to the attenuation of the high-frequency components. By means of double-Fourier series analysis, the authors derive expressions for Psw and for power-efficiency of filterless Class D amplifiers based on the tri-state modulation and on the conventional modulation. These derived expressions provide meaningful insight into the design and application of these amplifiers, including practical means to improve their power-efficiency and the associated implications thereof. To determine the dissipation of the high-frequency components in the loudspeaker, the authors extend the well established loudspeaker model in the audio range to a high-frequency model, and the required added power rating of the loudspeaker is determined. The authors show, somewhat serendipitously, that if certain conditions are satisfied, the power-efficiency of the tri-state and the conventional filterless amplifiers are nearly comparable. The analyses herein are verified by experimental measurements.

Control and Resonance Damping of Voltage-Source and Current-Source Converters With $LC$ Filters

In this paper, the closed-loop control of both voltage-source converter (VSC) and current-source converter (CSC) systems with <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">LC</i> filters is investigated, with a focus being put on the damping of <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">LC</i> resonance. First, both single-loop and multiloop control schemes for a voltage-source inverter (VSI) with output <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">LC</i> filter are analyzed, where the design and tuning procedure can also be applied to a current-source inverter (CSI) with output <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">CL</i> filter. It is shown that both VSI and CSI systems are subject to <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">LC</i> resonance, even with multiloop control, while the CSI system is also subject to <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">LC</i> resonant frequency variations. On the other hand, the <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">LC</i> resonant frequencies in both current-source rectifier (CSR) and voltage-source rectifier (VSR) systems with input <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">LC</i> filter circuits are relatively fixed due to the small variation range of source impedance. To further dampen the <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">LC</i> resonance in these converter systems, active damping techniques such as virtual harmonic damper and control-signal-shaping methods are investigated, and their implementation into the converter systems is discussed in detail. Experimental results from both a VSC system and a CSC system are obtained.

ＰＤ制御と外乱補償を用いたＬＣフィルタ付インバータ駆動ＡＣモータの簡易な制御法

This paper presents a simple voltage control system of AC machines using PWM voltage source inverter with output LC filters. By assuming a motor as a current source, the voltage is controlled by a simple proportional differential (PD) control. The vector control and PD control can be separately controlled in this system. A method for disturbance rejection is also described. The effectiveness of the proposed method is verified by simulations and experiments.

Stacked-Chip Implementation of On-Chip Buck Converter for Distributed Power Supply System in SiPs

An on-chip buck converter which is implemented by stacking chips and suitable for on-chip distributed power supply systems is proposed. The operation of the converter with 3-D chip stacking is experimentally verified for the first time. The manufactured converter achieves a maximum power efficiency of 62% for an output current of 70 mA and a voltage conversion ratio of 0.7 with a switching frequency of 200 MHz and a 2 times2 mm on-chip LC output filter. The active part and the passive LC output filter are implemented on separate chips fabricated in 0.35-mum CMOS and connected with metal bumps. The use of glass epoxy interposer to increase the maximum power efficiency up to 71.3% is also discussed.

Digitally controlled output filters for improvement of temperature behavior of machine tool main spindle drives

Variable speed main spindle drives of machine tools are usually fed by three-phase two-level inverters. Because of the switching operating mode of these inverters, the motor voltages and currents contain harmonics which do not contribute to torque formation but solely to an undesirable warming of motor spindle elements. This warming results in thermal elongation of the spindle shaft and therefore to a deviation in dimensional accuracy. The increased wear of the spindle bearings through high temperature differences between the inner and outer rings of the bearings is another drawback. This paper proposes a novel high-performance control system of an interior permanent magnet synchronous motor (IPMSM) using an inverter with an LC output filter. The combination of inverter and filter reduces the motor losses by compensating the switching ripples and therefore leads to an evident improvement of the temperature behavior of the main spindle drive.

Stability analysis and simulation of a single‐phase voltage source UPS inverter with two‐stage cascade output filter

AbstractThe primary role of an uninterruptible power supply (UPS) systems is to produce sinusoidal output voltage with minimum total harmonic distortion (THD) and fast dynamic response. This paper investigates the performance of two‐stage cascade output filter for single‐phase voltage source UPS inverter and it is compared with an LC output filter. The simulation result shows harmonic reduction of output voltage of the inverter due to using multiple‐filter. Both THD of the low output voltage and good voltage utilization can be achieved by the proposed filter scheme. The THD of the output voltage in various load condition are all less than 4%. A good agreement between the simulation and experimental results is achieved. Copyright © 2007 John Wiley &amp; Sons, Ltd.

Vector Control of an Induction Motor Fed by a PWM Inverter with Output LC Filter

This paper introduces a control method for an induction motor that is supplied by a PWM voltage source inverter through an LC filter. A cascade control structure is employed and a full-order observer is used to estimate the system states. Thus no additional voltage or current measurements are needed for the vector control of the motor. Two alternative methods are presented for the observer gain selection. Simulation and experimental results confirm the functionality of the proposed control method.

Sensorless Vector Control of an Induction Motor Fed by a PWM Inverter Through an Output LC Filter

The paper presents a speed sensorless vector control method for an induction motor that is supplied by a PWM inverter through an output LC filter. The system states are estimated by an adaptive full-order observer, and no additional voltage, current or speed measurements are needed. The rotor speed adaptation is based on the estimation error of the inverter output current. Quasi-steady-state analysis is used to illustrate the speed adaptation, and the stability is analyzed using a linearized model. Simulation and experimental results show that it is possible to achieve performance comparable to that of a drive without the LC filter.

An EMC evaluation of the use of unshielded motor cables in AC adjustable speed drive applications

The most common solution for modern adjustable speed drives (ASD) is the use of induction motors (IM) fed by voltage-source inverters (VSI). The inverter generates a pulsewidth modulated (PWM) voltage, with dv/dt values of about 6 kV//spl mu/s or even more. In three-leg inverters for three-phase applications the occurrence of common-mode voltage is inherent due to asymmetrical output pulses. As a result, for electromagnetic compatibility (EMC) reasons, in most applications shielded cables are used between the inverter and the motor, implying high installation costs. The present paper discusses the use of cheaper, unshielded cables from an EMC point-of-view. A new method for measuring electromagnetic interference (EMI) from unshielded cables is proposed and measurement results are presented. The level of EMI is evaluated in different situations: without an output filter, with a classical LC output filter and with an advanced output filter with dc link feedback. It is concluded that, from an EMC point of view, unshielded cables can give very good performance provided that a common-mode (CM) output filter is used.

Novel Vector Control System Using Deadbeat-Controlled PWM Inverter With Output LC Filter

This paper proposes a novel high-performance vector control system of an ac motor using a low-switching-frequency (2 kHz) pulsewidth-modulation voltage-source inverter with an output LC filter. Excellent high-speed response characteristics of the LC filter output voltage have been realized using a novel deadbeat control algorithm. As for the experimental results, the torque current response that is similar to the response of the conventional system without an LC filter has been obtained. In addition, it has been confirmed by simulation that errors of the LC filter constants within /spl plusmn/10% can be permitted.

Design and implementation of an inverter output LC filter used for dv/dt reduction

This paper presents the design and analysis of a LC output filter for use with IGBT-based motor drive inverters. The LC filter is used to limit the rate of rise of the inverter output voltage and reduce common mode noise to the motor. In typical applications where dv/dt is limited to 100-500 V//spl mu/s, the resonant frequency of the filter is above the switching frequency. A diode bridge must therefore be used to clamp the resonant voltage. Resistors are also used to help dissipate the energy stored in the resonant circuit. Crucial to the design of the filter is the handling of the additional losses in the filter. The paper describes the design considerations for such a filter for use in a 460 V induction motor drive. The losses in the circuit are estimated to show the limitations of the filter. Experimental results illustrate the control of dv/dt at the inverter terminals, and the reduced peak voltage at the motor end of a long cable.

Novel three-controller average current mode control of DC-DC PWM converters with improved robustness and dynamic response

This paper presents a novel average current mode control (ACC) strategy for the control of pulse width modulated (PWM) DC-DC converters, which represents a drastic improvement over conventional ACC. This new method consists of the addition of an auxiliary controller into the control loop, besides the current and voltage regulators. The model-based auxiliary controller can increase the closed loop small-signal bandwidth of Buck derived converters, preserving loop gain crossover frequency and stability margins over significant changes of the power stage passive elements values, the load and the line voltage. Moreover, this control scheme shows much better disturbance rejection properties, i.e., closed loop impedance and audiosusceptibility, than conventional ACC. From a control theory point of view, robust performance is achieved preserving stability. A Buck prototype has been experimentally tested with different LC output filters, line and load conditions, including discontinuous conduction mode. Measurements of the small signal frequency response of the converter have been carried out, showing the improvement achieved by the proposed control scheme. The empirical large signal response of the converter under load steps is also shown in order to validate the concept.

Power calibrator using switched mode voltage source

The paper is focused on a sophisticated switched mode power supply with a pure sinusoidal output voltage waveform with frequency (40-65 Hz) and voltage range (30-500 V). In order to cope with stringent voltage (10.2%) and distortion constraint (THD<0.7%) in a modern calibration system, traditional inverter design with an output LC filter is upgraded with a feedback-feedforward control principle. The paper presents the voltage source topology, analyzes its steady-state response and gives its comprehensive evaluation. Using a simple sensor that is capable to detect a small voltage asymmetry at the presence of a high AC component (500 VRMS), the parasitic DC component is limited below 5 mV. Experimental results demonstrate exceptional voltage accuracy (<0.2%) and low total harmonic distortion (THD).

White Paper on the New ABB Medium Voltage Drive System, Using IGCT Power Semiconductors and Direct Torque Control

This paper describes the new medium voltage PWM converter developed by ABB for driving medium voltage squirrel cage induction motors in a power range of 500 kVA to 6000 kVA. The role of the author was to witness, as an academic party, the different features that the developer-manufacturer included to come to a competitive product. The paper is built up around the technical features that the developer’s team selected to reach their objectives: three level converter topology with LC output filter and input isolation transformer, advanced thyristor technology (IGCT-Integrated Gate Commutated Thyristor), advanced control principles (DTC = Direct Torque Control) and fuseless design. The author asked the manufacturer to provide comprehensive experimental data, which are reported in this paper, to evaluate the statements and the benefits of the drive.

Deadbeat control of a three-phase inverter with an output LC filter

The discrete-time control of a three-phase inverter with an output LC filter is described based on space vectors. The mathematical model of the inverter-filter system is first obtained by using space vectors to represent three-phase quantities. Deadbeat control laws are derived for no-load and resistive-load cases. Then, a deadbeat control law is obtained for the case when the load draws current of any waveshape from the inverter-filter. It is shown that deadbeat control of output voltage can be achieved in two control steps. The manipulated variable, which is the voltage vector demanded from the inverter, is implemented using the space vector modulation technique. Simulation results for various operating conditions are presented.

Digital control of three-phase PWM inverter with LC filter

A digital control algorithm for the three-phase sinusoidal voltage inverter with an output LC filter has been developed. To take the transient of the LC filter during the discretization time into consideration, a fourth-order matrix state equation of the current and the voltage on the d-q frame is discretized. Precise discrete equations for the inverter are introduced. Using these equations, a deadbeat controller consisting of a d-g current minor loop and a d-q voltage major loop, with precise decoupling of the d-q components, was developed. The voltage major loop controller assures the sinusoidal output voltage and stabilizes the system. A deadbeat controller is used because both the current minor loop and the voltage major loop can used one sampling response. The validity of these techniques is confirmed by simulation studies. This method is expected to be useful for direct digital control of large-capacity sinusoidal voltage inverters using low-switching-frequency devices. >