Abstract: A new current control method based on the internal model principle in control theory is proposed. It introduces a sinusoidal internal model into the control system. It does not use any coordinate transformations. The method can be used for tracking an arbitrary number of harmonics: a DC component or fundamental frequency component signal. It is applied to a single-phase pulsewidth modulation inverter and active filter. The validity is confirmed by simulation and experimental results.

Abstract: The voltage output is inevitably delayed in a full-digital implementation of a current regulator due to an arithmetic calculation and the pulsewidth modulation. In the case of the synchronous frame current regulator, the time delay is accompanied by a frame rotation. In some applications where the ratio of the sampling frequency to the output frequency is insufficient, such as a high-power drive or a super-high-speed drive, the effect of the frame rotation during the delay time causes a phase and magnitude error in the voltage output. The error degrades the dynamic performance and can cause instability in the current regulator at high speed. It is also intuitively known that advancing the phase of the voltage output can mitigate this instability. In this paper, the errors in the voltage output and the instability problems have been studied analytically and a compensation method for the error is proposed. Using a computer simulation and complex root locus analysis, a comparative study with conventional methods has been carried out and the utility of the proposed method has been verified experimentally.

Abstract: A control system for driving a power tool is provided comprising a power source, a motor adapted to drive a shaft, a power switching unit interconnecting the power source and the motor, and a controller The power switching unit applying a pulse width modulated (PWM) drive signal from the power source to the motor The controller monitoring at least one electrical characteristic of at least one of the power source, motor and power switching unit and adjusting the operating duty cycle of the PWM drive signal based on the electrical characteristics

Abstract: Control techniques for PWM rectifiers in AC adjustable speed drives are presented. In particular, the so-called virtual-flux oriented control (VFOC) and virtual-flux based direct power control (VF-DPC) schemes are described and compared with their voltage based counterparts, that is, the voltage oriented control (VOC) and voltage-based direct power control (V-DPC) techniques. Theoretical background is provided, and results of computer simulations and laboratory experiments are given, documenting advantages and disadvantages of the individual control strategies.

Abstract: The matrix converter is very simple in structure and has powerful controllability However, the commutation problem and complicated PWM method keep it from being utilized in industry This paper discloses a novel matrix topology with advantages over the usual matrix converter topology Firstly, it has the same performance as a conventional matrix converter in terms of voltage transfer ratio capacity, four quadrant operation, unity input power factor, no DC capacitor and pure sine waveforms with only high order harmonics in both line and load side Secondly, the PWM method utilized for the conventional inverter can be used, which can largely simplify its control complexity Thirdly, all the switches at the line side turn on and turn off at zero current; the converter does not have any commutation problems as required by the conventional matrix converter Theoretical analyses and simulation results are provided to verify its feasibility

Abstract: Apparatus and methods that control motor power in an electric motor such as a stepper motor, advantageously allow improved open-loop motor performance, allow reduced motor hunting, detect stalls, detect out-of-synchronization errors, control and synchronize multiple motors, and can automatically configure motor parameters to provide a motor with a power and load combination that gives an optimized performance. In one embodiment, an EMF commutation circuit detects a rotor position at which to sequence the motor to provide an optimized performance from the motor. In another embodiment, pulse width modulation (PWM) controls power, and the embodiment measures the rotor position within a detent position. Particular embodiments of the invention utilize a motor controller adapted to respond to a commutation signal, a pulse, or both in conjunction with a sensing device, such as an EMF detector or an optical encoder.

Abstract: An LED driver circuit and method are disclosed where an array of light emitting diodes have a transistor connected to each respective array of light emitting diodes. A PWM controller has an input for receiving a voltage reference and an output connected to selected transistors for driving selected transistors and setting a PWM duty cycle for the selected arrays of light emitting diodes to determine the brightness of selected light emitting diodes. An oscillator is connected to the PWM controller for driving the PWM controller.

Abstract: A dynamic voltage restorer (DVR) based on the voltage-space-vector pulsewidth-modulation algorithm is presented. Phase-jump compensation is achieved using a software phase-locked loop and a lead-acid battery energy store. A battery-charging control technique using the DVR itself is also described. To validate the control of the DVR, a three-phase prototype with a power rating of 10 kVA has been successfully developed. Simulation and experimental results are shown to validate the control methods.

Abstract: A space vector PWM technique is developed based on the combination of space vectors from dual inverters feeding the induction motor from both ends (open-end winding without neutral point). A total of 64 voltage space vector combinations are available for PWM voltage control of the inverter fed machine with open-end winding. A space phasor based PWM scheme is proposed with minimum number of switching in a cycle per inverter coupled with equal number of switching for each inverter.

Abstract: The digital scalar pulse-width modulation (DSPWM) gathers the characteristics of simplicity of implementation found in the regular sampling with the flexibility of manipulation of the switching patterns in the space vector modulation (SVPWM). This paper establishes a correlation between the SVPWM and DSPWM techniques. It also shows how to make the DSPWM strategy equivalent to the SVPWM technique without losing its simplicity of implementation. By using such an equivalence concept a microprocessor-based scheme, which uses standard timer circuits and a simple software algorithm, is proposed to implement the DSPWM technique. The introduction of the "distribution ratio" in this technique, allows the development of a systematic approach for implementing either conventional or any modified vector strategies without changing the modulator scheme. This corresponds to generating any attractive nonsinusoidal modulating signals (NSMS) in the carrier-based modulation techniques. Furthermore, the simple digital blocks can be easily implemented as a specialized integrated circuit. Simulated and experimental results demonstrate the validity of the proposed methods.

Abstract: An active power filter (APF) is a device that is connected in parallel to and cancels the reactive and harmonic currents from a group of nonlinear loads so that the resulting total current drawn from the AC mains is sinusoidal. This paper presents a unified constant-frequency integration (UCI) APF control method based on one-cycle control. This method employs an integrator with reset as its core component to control the pulse width of an AC-DC converter so that its current draw is precisely opposite to the reactive and harmonic current draw of the nonlinear loads. In contrast to previously proposed methods, there is no need to generate a current reference for the control of the converter current, thus no need for a multiplier and no need to sense the AC line voltage, the APF current, or the nonlinear load current. Only one AC current sensor is used to sense the AC main current and one DC voltage sensor is used to sense the DC capacitor voltage. The control method features constant switching frequency operation, minimum reactive and harmonic current generation, and simple analog circuitry. It provides a low cost and high performance solution for power quality control. Steady-state and dynamic study is presented in this paper. Design example is given using a two-level AC-DC boost topology. A prototype was developed to demonstrate the performance of the proposed APF. This control method is generalized to control a family of converters that are suitable for APF applications. All findings are supported by experiments and simulation.

Abstract: This paper proposes a family of modulation strategies for PWM three-level (TL) converters. The modulation strategies can be classified into two kinds according to the turn-off sequence of the two switches of the pair of switches. The concept of the leading switches and the lagging switches is introduced to realize soft-switching for PWM TL converters. The realization of soft-switching for both the leading switches and the lagging switches is proposed, based on which, soft-switching PWM TL converters can be classified into two kinds: zero-voltage-switching (ZVS) and zero-voltage and zero-current-switching (ZVZCS), for which the suitable modulation strategies are pointed out respectively from the family of modulation strategies. A novel ZVZCS TL converter is proposed, its operation principle and parameter design are analyzed, and the experimental results are also included.

Abstract: In this paper, a functional simulation model for the voltage-source inverter (VSI) using the switching function concept is studied and the actual implementation of the model is proposed with the help of Matlab Simulink. Also, this concept is extended to the voltage-doubler-type pulse width-modulated (PWM) AC-DC rectifier and the PWM AC-DC-AC converter. With the developed functional model, the simplification of the static power circuits can be achieved so that the convergence and long run-time problems can be solved. Also, in the functional model, the design parameters, such as voltage and current ratings of the power semiconductor switches and load current, can be easily calculated. The general switching function concept is reviewed in brief and the proposed functional models for the VSI, voltage-doubler rectifier, and PWM AC-DC-AC converter and their implementations using Matlab Simulink are explained in detail. Also, several informative simulation results verify the validity of the proposed models.

Abstract: This paper presents the analysis and design of a single-phase voltage regulator (VR) and its multinodule parallel control. The VR employs the pulsewidth modulation three-arm rectifier-inverter topology. The inverter side adjusts the load voltage with the series regulating structure aiming to minimize converter capacity and attain higher efficiency. The rectifier side regenerates the load power and executes the active power filter function to achieve unity power factor. Based on such high-performance VR, a resistive droop method combined with the P-V droop and Q-/spl delta/ shift scheme is then proposed to control the current sharing such that multiple VRs can be paralleled directly without any control interconnection. The proposed parallel control technique possesses the features of fast response, precise voltage regulation, equal fundamental and harmonic current sharing, tolerance for parameter mismatch, and so on. Two prototype 1 KVA VRs are implemented, and the effectiveness is demonstrated by some simulation and experimental results.

Abstract: A DC-to-DC converter has a pulse width modulator PWM) and a hysteretic (ripple) modulator. For low current loads, the hysteretic modulator is selected; for high current loads, the PWM is selected. A mode selection switch senses the polarity of the switched output voltage at the end of each switching cycle. If the polarity changes from one cycle to the next, the mode may be instantly changed to the other mode. Counters are used to record the polarity at the end of each cycle and switching from one mode to another can be delayed by the counters to prevent changing modes based on spurious output voltage fluctuations.

Abstract: This paper presents a technique for reconstructing converter line currents using the information from a single current sensor in the DC link of a converter and comparative evaluation of the performance of single sensor control techniques in the DC link for voltage-source pulsewidth modulation (V-S PWM) converters. When 3/spl phi/ input currents cannot be reconstructed, three methods to acquire the DC-link current are compared. Two of them are methods of modifying the switching state (I, II), and another is a method of using the predictive state observer. Also, compensation of sampling delay, and a simultaneous sample value of input currents in the center of a switching period are included. Suitable criteria for the comparison are identified, and the differences in the performance of these methods are investigated through experimental results for a typical V-S PWM converter rated at 10 kVA.

Abstract: This paper presents a switching strategy for multilevel cascade inverters, based on the space vector theory. The proposed switching strategy generates a voltage vector with very low harmonic distortion and reduced switching frequency. This new control method is an attractive alternative to the classic multilevel PWM techniques considering the following aspects: (i) voltage and current THD, (ii) range of linear operation, and iii) number of commutations.

Abstract: An LED array is controlled by determining a constant relating the peak light output of an LED to the peak driving current of a PWM pulse driving the LED, and multiplying the average current of the PWM pulse by the constant to obtain a value of average light output for the LED. The constant may be determined by simultaneously measuring peak light output of the LED and peak current of a PWM pulse driving the LED. The constant is then calculated by dividing the peak light output by the peak current of the PWM pulse. By making the simultaneous measurements at a time during the duration of the PWM pulse where the pulse has reached its full magnitude, rise and fall times of the pulse do not affect the measurements. The average current of the PWM pulse may be determined by a variety of methods including integrating current in the PWM pulse over time, or passing the PWM current through a low pass filter configured for providing an average value of PWM current. Determining average current in this manner further reduces the effect of rise and fall time on determining the average light output of the LED.

Abstract: A voltage regulator ( 1 ) and includes a first switch (S 1 ) coupled between an input conductor ( 2 ) and a first terminal ( 4 ) of an inductor ( 5 ), a second switch (S 2 ) coupled between the first terminal of the inductor and a common conductor ( 3 ), a third switch coupled between an output conductor ( 7 ) and a second terminal ( 6 ) of the inductor, and a fourth switch (S 4 ) coupled between the second terminal of the inductor and the common conductor ( 3 ). The voltage regulator is operated in a mixed buck-boost mode by producing a first signal (V 32 ) representative of the difference between an output voltage (V OUT ) produced on the output conductor ( 7 ) by the voltage regulator and a reference voltage. A second signal (I MEAS ) is produced to represent the current through the inductor ( 5 ). A third signal (V 68 ) is produced to represent a combination of the first signal and the second signal. A pulse width modulated error signal (PWM) is produced by comparing the third signal (V 68 ) to a reference voltage. The first (S 1 ) and fourth (S 4 ) switches are controlled in response to the error signal (PWM) and first (Q 23 ) and second (Q 27 ) state signals representative of prior states of the first (S 1 ) and fourth (S 4 ) switches.

Abstract: An unified constant-frequency integration (UCI) control method based on one-cycle control employs an integrator with reset as its core component along with a few logic and linear components to control the pulse width of a three-phase recitifier, active power filter, or grid-connected inverter so that the all three phase current draw from or the current output to the utility line is sinusoidal. No multipliers and reference calculation circuitry are needed for controlling active power filters. The UCI control employs constant switching frequency and operates in continuous conduction mode (CCM). If in some cases a DSP is desired for some other purposes, the Unified Constant-frequency Control function can be realized by a low cost DSP with a high reliability, because no high speed calcutation, high speed A/D converter, and mutipliers are required.

Abstract: A new control scheme of a variable speed grid connected wind energy generation system is presented. The scheme uses a cage induction generator driven by an emulated wind turbine with two back-to-back voltage-fed PWM inverters to interface the generator and the grid. The machine currents are controlled using an indirect vector control technique. The generator torque is controlled to drive the machine to the speed for maximum wind turbine aerodynamic efficiency. The supply side converter currents are also controlled using a vector approach using a reference frame aligned with stator voltage vector. The DC link voltage of the power electronics interface is controlled acting upon the supply active power current component using a nonlinear control and a fuzzy based interpolation of linear PI controllers to improve the disturbance rejection and meet noise considerations in steady state. Experimental validation of the proposed control scheme on an emulated 3.2 kW wind energy system is shown.

Abstract: An output isolated, switching power supply (100) has a transformer (73) with a primary (91) and two secondaries (92, 93), and electronic switch (75) in series with the primary, a first rectifier (87) and filter (88) on the first secondary (93) to provide bias power during both startup and operating modes, and a second rectifier (80) and filter (82) on the second secondary (92) to provide regulated output power. A resistor-capacitor network (78, 74) on the primary side provides an initial operating condition, such as a single control pulse, to the electronic switch which causes sufficient energy to be transferred through the first secondary to supply sufficient startup energy to operate a current control integrated circuit (89) on the secondary side in a staged fashion. After the initial operating condition, the current control integrated circuit generates and applies a control signal to the electronic switch through an isolation circuit (77) to cause the electronic switch to turn on and off in controlled fashion in order to deliver regulated power to the output of the supply. The low voltage, secondary side, current control integrated circuit provides a further aspect of the present invention.

Abstract: The pulse-width modulated (PWM) voltage-source converter (VSC) and current-source converter (CSC) are the building blocks of most of the switch-mode power electronic systems. Irrespective of the converter type, the controller is supposed to fulfill two objectives: (1) real power flow control which leads to the regulation of the DC quantity (DC voltage in VSC and DC current in CSC), and (2) reactive power flow control on the AC-side. The major difficulty in control is caused by the nonlinearities in the converter model. The existing control techniques are based on the design of the PI-controllers without the knowledge of the converter model, linearizing the nonlinear model, or splitting the original system into linear and nonlinear parts and dealing with them separately. In this paper, a power balance equation and nonlinear input transformation are used to derive a linear model from the original nonlinear model. Then, a decoupled state-feedback control method is applied to the new model. The accuracy of the new model and the performance of the applied control method are evaluated using the simulation results obtained from the PSCAD/EMTDC simulation package. It is shown that as a result of using the new model and applying the state-feedback control technique, the dynamics of the system are considerably improved resulting in short response times. It is also shown that the approach taken in modeling and control results in excellent results even at low switching frequencies making the scheme very suitable for high-power applications.

Abstract: This paper presents a method to damp transient oscillations on the output LC filter of PWM inverters by using a virtual resistor. A virtual resistor is an additional control algorithm that simulates the roles of a resistor in the output LC filters. Because no real resistor is used, the oscillations can be damped effectively without sacrificing the power efficiency. The implementation of the virtual resistor is determined by how the resistor is connected to the LC filter. Experimental results are included to verify the proposed method.

Abstract: A family of soft-switched, full-bridge pulse-width-modulated (FB PWM) converters provides zero-voltage-switching (ZVS) conditions for the turn-on of the bridge switches over a wide range of input voltage and output load. The FB PWM converters of this family achieve ZVS with the minimum duty cycle loss and circulating current, which optimizes the conversion efficiency. The ZVS of the primary switches is achieved by employing two magnetic components whose volt-second products change in the opposite directions with a change in phase shift between the two bridge legs. One magnetic component always operates as a transformer, where the other magnetic component can either be a coupled inductor, or uncoupled (single-winding) inductor. The transformer is used to provide isolated output(s), whereas the inductor is used to store the energy for ZVS.

Abstract: A space vector controlled channel state information (CSI) drive for multimotor applications is investigated The multimotor operation of the drive is achieved by integrating the proposed active damping control, inverter-side DC link voltage feedforward control and pulse width modulation (PWM) index control into the conventional V/f control The main function of the active damping control is to suppress possible LC resonances caused by the inverter filter capacitor and motor inductances This function is essential in achieving stable operation of the drive, especially in the multimotor drive where multiple LC resonant modes exist An additional advantage provided by the active damping control is that it makes the control system less sensitive to motor parameters The inverter-side DC link voltage feedforward control and the adjustable PWM modulation index control are developed to improve the dynamic performance of the drive system In addition, the proposed space vector PWM pattern features a low switching frequency (500 Hz), which makes the proposed drive system suitable for high power applications The system stability is investigated by means of eigenvalue analysis The theoretic analysis is verified by experiments on a digital signal processing (DSP) controlled CSI multimotor drive

Abstract: The speed control of ac-electric motors can be carried out efficiently by adjustable speed drives (ASD), which are constituted by an AC/DC conversion block, a DC filter and a DC/AC inverter representing the core of the whole power converter. A new generation of DC/AC converters for adjustable speed drives, the so-called PWM (Pulse Width Modulation) inverters, has been developed in recent years. It has significant advantages for motor speed control, but has been proved to overstress electrical insulation with respect to the sinusoidal supply. The increase of partial discharge (PD) activity seems to be mainly responsible for the degradation acceleration of motors fed by ASD. In order to investigate the aging behavior, the results of life tests carried out on twisted pairs subjected to 50 Hz and 10 kHz sinusoidal voltage, as well as unipolar and bipolar square pulses, are presented.

Abstract: A pulse width modulation driver for an organic light emitting diode display. One embodiment of a video display comprises a voltage driver for providing a selected voltage to drive an organic light emitting diode in a video display. The voltage driver may receive voltage information from a correction table that accounts for aging, column resistance, row resistance, and other diode characteristics.