PWM Control Signal Research Articles

EMI Reduction Techniques in Digitally Controllable Power Supplies

Abstract The paper presents EMI reduction techniques in analog and digital power supplies, highlighting the role of each technique apart. There are also detailed some useful hardware and software design techniques in order to reduce or attenuate the EMI. Passive techniques focus on reducing the EMI level by filtering, shielding and proper PCB layout of the power components. Active techniques focus on modifying the PWM control signal shape in order to reduce EMI or spread the energy of the signal on wide frequency range. The paper also presents an implementation method of the spread frequency modulation on a low cost RISC MCU unit. The paper describes the mathematical and simulated relationship between a non-ideal PWM signal's main parameters and the spectral content of the signal. The experimental results are obtained by measurements performed on a multistage buck-boost converter, which uses two converters working in parallel and in phase-shift of 180° developed by the authors.

An Improved Synchronous Drive Control Platform of Multi-Servo Motor Based on DSP Used in Teaching

In order to demonstrate the synchronous driving capability of multi-servo motor, an improved synchronous drive control platform based on DSP used in teaching was established. The dedicated motor control chip ASIC-TMS320F2812A was adopted with a unique independent PWM control signal output function. The hardware components were introduced, resulting in principle and duty cycle of the PWM waveform calculation. The tests showed that the DSP servo control system has good performance of high reliability, fast dynamic response and low noise.

GaN Power Module with High Temperature Gate Driver and Insulated Power Supply

Emerging GaN power switches show advantages for integration in power modules at high temperature and/or high efficiency. These modules are good candidates for embedded power converters in harsh environment such as three phase inverters for Electro-Mechanical Actuators (EMA) in the vicinity of internal combustion engines. The power range is usually within 1 to 5 kW, extending sometimes up to 50 kW, using a high voltage DC bus (HVDC) that is usually comprised between 200 V and 600 V. For aeronautical applications, GaN power switches could challenge SiC transistors for their high switching speed, hence reduced switching losses, therefore lower embarked mass. For automotive applications, it is the relative promise for lower cost per Amp that is pushing this technology up. This is why a project joining GaN device conception, power module development and gate driver optimization using high temperature technologies was set-up. This paper presents the first practical results: a functional GaN power inverter-leg driven by a specific high temperature gate driver with signal and power insulation. This building block requires an auxiliary DC supply with a input voltage of 14 V or 28 V and an external PWM control signal. Current rating is 20 A and breakdown voltage is 200 V.

Design and Performance of a Three-Phase Fuzzy Logic Controlled Shunt Active Power Filter Control Hardware with a 400 kHz Switching PWM Implemented in FPGA

This paper presents a control strategy for harmonic compensation using a fuzzy logic controlled shunt active power filter generating a 400 kHz PWM control signal compatible with recent Silicon Carbide inverters. The designed controller uses the p-q Theory, a modified Fuzzy DC regulator instead of a PI Fuzzy and high speed current generation for the 400 kHz PWM control signal. This paper also describes and analyzes the improvement in increasing the switching frequency and its relation to the total harmonic distortion at the source and the filter inductors size. Such control presents a complexity in terms of speed which is solved by the use of a FPGA. The FPGA allows the Fuzzy DC controller to operate in parallel with the p-q Theory and the 400 kHz PWM generator, optimizing speed and hardware with the use of VHDL-2008 fixed-point libraries. The controller is synthesized in the Altera Cyclone $$^{\circledR }$$ IV EP4CE115 from DE2-115 board. The implementation is experimentally validated by “FPGA in the Loop” and compared with other similar solutions showing better performance and effectiveness.

2-Phase Symmetrical PWM Generator Using CPLD for Ultrasonic Motor Drive

Push-pull driving circuit is a type of commonly used driving circuit for ultrasonic motor. The symmetrical PWM signals are needed for the control of push-pull driver, and thus the motor. This paper introduces a novel 2-phase symmetrical PWM control signal generator that can be used with ultrasonic motor drive. The generator’s structure and operation is analyzed, and the actual realization using CPLD is also given out. The experimental results proved that, the design is correct.

The Leveling Position Control of a Four-Axial Active Pneumatic Isolation System Using PWM-Driving Parallel Dual-On/Off Valves

This study aims to develop a leveling position control of an active PWM-controlled pneumatic isolation table system. A novel concept using parallel dual-on/off valves with PWM control signals is implemented to realize active control and to improve the conventional pneumatic isolation table that supported by four pneumatic cushion isolators. In this study, the cushion isolators are not only passive vibration isolation devices, but also pneumatic actuators in active position control. Four independent closed-loop position feedback control system are designed and implemented for the four axial isolators. In this study, on/off valves are used, and PWM is realized by software. Therefore, additional hardware circuit is not required to implement PWM and not only cost down but also reach control precision of demand. In the controller design, the Fourier series-based adaptive sliding-mode controller with H∞ tracking performance is used to deal with the uncertainty and time-varying problems of pneumatic system. Finally, the experiments on the pneumatic isolation table system for synchronous position and trajectory tracking control, including no-load and loading conditions, and synchronous position control with master-slave method, are implemented in order to verify that the controller for each cushion isolator can realize good position and trajectory tracking performance.

The Realization of 16-Bit PWM for Lithium-Ion Battery Pack Charging by Using C8051F020 MCU

In the lithium-ion battery charging circuits, needs to solve the PWM signal and systems synthesis control item. Therefore, converting voltage feedback signal by C8051F020 MCU ADC0, the result which ADC0 converts delivers the Programmable Counter Array PCA0 module to realize 16-bit PWM trigger signal to control the charging circuit output. At the same time in producing the PWM signal, Use the ADC0 window detector to realize entering value surpassing range alarm and protection, Also, because 12-bit ADC0 is, therefore, Have carried out a recondition on the PCA0 value in program, have realized PWM control signal output, it's frequency is to set up, cause it's application to further nimble, control accuracy more highly.

Model Identification Dedicated to the Time-Optimal Control

A model identification procedure is applied to the well known benchmark problem of the pendulum hinged to a cart. There is a dynamical model of the entire system. The PWM control signal and DC motor impact introduced electrically by EMF are included. A concatenation of trajectories collected during several control experiments is used to fit the parameters of the pendulum-cart mathematical model. The identification of model parameters is dedicated to the control goal. Several collected points of trajectories are neglected. The model matching corresponds to intervals.

Multilevel single-phase rectifier–inverter with cascaded connection of two three-arm converters

The paper proposes a multilevel single-phase rectifier-inverter with the cascaded connection of two three-arm converters. A semisinusoidal PWM switching technique is developed to form a five-level switching pattern on the rectifier side and the inverter side simultaneously. The DC-link voltages of two converters are regulated with one voltage controller. Balance of two DC-link voltages is controlled with a feed-forward adjustment of the PWM control signal. Multiple-loop controller design of the system is presented. The feed-forward-plus-feedback control technique is employed for regulating both the rectifier current and the inverter voltage. A 2 kVA/220 V/60 Hz prototype system is set up and its control circuit is realised based on Matlab real-time control. Effectiveness of the proposed circuits is confirmed with some experimental results

A new microcontroller-based technique for generating variable voltage/frequency sinusoidal PWM signals

This paper presents a flexible and robust microcontroller-based technique for generating the control signals of any sinusoidal pulse width modulation (SPWM) scheme for variable voltage/frequency output. The proposed technique exploits the fully static design of a high-speed microcontroller and generates the PWM control signals by varying the controller's clock, while keeping the number of the algorithm processing states constant. As the experimental results show, the technique can be used for transient-free frequency and/or voltage changes with very good resolution and a wide range of applications.

Fuzzy PWM Control of the Positions of a Pneumatic Robot Cylinder Using High Speed Solenoid Valve.

In the study, instead of using expensive servo valves, three inexpensive high-speed solenoid valves were adopted and a fuzzy PWM controller was designed to control the linear and rotational positions of a pneumatic robot cylinder. The modified differential PWM method is proposed to eliminate the dead zone and to improve the nonlinear characteristics between the pressure difference of the cylinder and the duty ratio of the PWM control signal. The experimental results have shown that the servo pneumatic system with the proposed fuzzy PWM controller exhibits good performance.

Improvement of induction motor drive systems supplied by photovoltaic arrays with frequency control

The overall efficiency of an induction motor drive system, powered by a PV array, drops significantly when the insolation condition varies away from its nominal level. This problem can be overcame using a control method in which the frequency of the inverter's PWM control signal is adjusted according to the insolation and temperature conditions. The motor speed, and therefore, the power delivered to the load, are adjusted by controlling the inverter's frequency. This eliminates the mismatch between the maximum power that is available from the source and the power that is required by the load. Simulation results presented in this paper show that using the proposed control system allows the induction motor drive system to maintain its optimum efficiency and deliver consistently more power to the load when insolation and temperature vary from the nominal level. This method also offers an improvement in the system stability.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

A novel sine PWM scheme using waveform generators

The paper presents a novel circuit for generating the sine PWM control signals for a single phase inverter. Waveform generating ICs based on a JFET are used to generate the synchronized sine and triangular waveforms with a high accuracy and wide range of frequencies. Experimental waveforms and frequency spectra of inverter output voltage are presented.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Control Methods for Reduction of DC Link Capacitor and Restarting at Instantaneous Power Failure in PWM Converter.

Rectifiers composed of diodes or thyristors have many harmonics in line currents. Recently, PWM converters have been actively studied to reduce the harmonics. In order to put them into practical use, not only PWM control method but also the following control methods must be established.(1) Method for reducing the capacity of dc link capacitor.(2) Restarting method from instantaneous power interruption.For reducing the capacity of do link capacitor, it is necessary to suppress the fluctuation of dc link voltage at a sudden change of load. In this paper, the load is inverter for variable speed induction motor drives. The load current of converter, that is the inverter input current, is detected without delay time and ripple by multiplying the inverter output currents or motor currents and the inverter PWM signals. By adding the detected signal to do link voltage control loop as a compensating component, the fluctuation of dc link voltage at a sudden load change can be suppressed. As a result, the capacity of the dc link capacitor or can be reduced to smaller than one-fifth of that in the conventional diode rectifier. For restarting from instantaneous power interruption, the very simple control method is proposed. When the dc link voltage becomes low limitation value setted at a little bit lower than that obtained in diode rectifier in the period of power interruption, the PWM signals to converter are blocked. After recovery from power interruption, when the dc link voltage reaches the low limitation value, the PWM control signals are supplied to the converter again and it is restarted the operation. From the experimental results, it was confirmed that the PWM converter can be restarted from the instantaneous power interruption very smoothly.