Digital Pulse Width Modulation Technique Research Articles

Design of Modified Counter based PWM generator for closed-loop DC-DC Voltage Regulation

This paper proposes the design of a novel Modified Counter based Digital Pulse Width Modulation generator to analyze the performance of the closed-loop DC-DC buck converter. The closed-loop DC-DC buck Converter uses the Proportional Integral controller to regularize the output voltage and the bio-inspired algorithms namely Particle Swarm Optimization and Ant Colony Optimization are considered for the generation of the optimal values for the PI gains namely KP and KI. Conventionally, the switching of the buck converter is controlled by the PWM signals that exhibit complexity in design. The updated Digital Pulse Width Modulation techniques were suitable for voltage regulation at the cost of high clock frequency requirement, increase in the design area for real implementation, and the trade-off between the switching frequency and the component size of the buck converter. To overcome these, the modified Counter based Digital Pulse width modulation that generates the high switching frequency DPWM is developed in HDL. Then the proposed technique is validated in the closed-loop PI-based DC-DC buck converter using the System Generator MATLAB SIMULINK. To regularize the voltage output, the PI controller is included along with the optimization algorithms such as Particle Swarm Optimization and Ant Colony Optimization to optimize the PI gains. The time transient analysis of the proposed method exhibits improvement in the ACO based design compared to the PSO based method. The power and area are manipulated by using the Cadence and Xilinx tools

A Multiphase Digital Pulsewidth Modulated Polar Transmitter Architecture With Reactive Combiner for Improved Efficiency

This paper presents a new method of reactive-combiner structure to be used as part of a multiphase digital pulsewidth modulated polar transmitter (DPWMPT). It overcomes the limitations of previous implementations of the multiphase pulse-modulated polar transmitter related to terminating pulsewidth modulation (PWM) harmonics located outside the passband, thereby improving both PWM harmonic suppression by using multiphase aliasing-free digital PWM technique and increasing overall efficiency by using reactive combining. For validation, a prototype transmitter was implemented and tested with a 64-QAM 20-MHz bandwidth long-term evolution (LTE) downlink signal with a 7.5-dB peak-to-average power ratio at 2140 MHz. The prototype dual-phase DPWMPT architecture achieved an output power level of 37 dBm and power-added efficiency of 33.5% while passing the stringent spectral requirements of the LTE standard for small-cell base stations using only simply memoryless predistortion correction.

Digital Controller for an Electric Wheelchair Based on a Low-Cost Hardware

This paper presents a digital motion controller of an electric wheelchair by using a low-cost real-time microcontroller unit (MCU) and an own developed power electronic drive. The speed control of the wheels is implemented through a digital pulse-width modulation technique which is varying with the reference generated by a low-cost joystick. Voltage regulators and power converters are implemented to supply correct voltage levels to control cards and to the DC motors from batteries. Experimental results which have been obtained by using the MCU, the mechanical structure of a used electric wheelchair and the developed electronic drive demonstrate that the proposed digital controller meets the user requirements in terms of reliability, good driving and fair economic cost.

Digital Pulsewidth Modulation Technique for a Synchronous Buck DC/DC Converter to Reduce Switching Frequency

It has been shown that the resolution of a digital pulsewidth modulator (DPWM) can be dramatically increased by either constant on-time modulation control or constant off-time modulation control as compared to that for constant frequency modulation. However, the switching frequency increases dramatically for the constant on/off-time modulation method under heavy/light load conditions, respectively. The increase of switching frequency results in more switching losses and requires a higher performance controller. The objective of this paper is to propose a new digital pulsewidth modulation (PWM) technique with constant on/off-time control for a synchronous buck dc/dc converter in order to reduce the switching frequency and switching losses. Moreover, the switching frequency can be limited to a certain range. Experimental results of the proposed new digital PWM technique are presented for confirmation. It will be shown that the proposed technique can significantly reduce the switching frequency of the converter, thereby improving DPWM resolution and the efficiency.

PWM rectifier with low DC voltage ripple for magnet supply

Control techniques that optimize the behaviour of pulse-width modulation (PWM) rectifiers for magnet supplies are examined. Different control strategies, both with preprogrammed and variable switching patterns, are examined and compared in terms of optimization of the system performance. Optimum digital PWM, multilevel delta modulation, and hybrid PWM/delta techniques are analyzed. The validity of the control methods was verified by simulation and experimental tests on a 60 kW prototype. It was observed that, in practice, digital PWM techniques are better suited for optimizing the AC converter performance, while delta modulation techniques give better results in terms of DC current and voltage distortion. >