Pulse Width Modulation Driver Research Articles

Switched-Capacitor-Based Current Compensator for Mitigating the Effect of Long Cable Between PWM Driver and LED Light Source

It is sometimes unavoidable to have light-emitting-diode (LED) light sources and their pulsewidth modulation (PWM) drivers connected by long cables in large-scale illuminations. However, long-cable inductance delays the rate of rise of the driving current pulses and thus leads to the reduction of luminous flux output. It also causes the off-state voltage across the light sources negative, which would deteriorate the life expectancy of the LEDs. A switched-capacitor-based current compensator for correcting the wave shape of the driving current pulses is presented. The methodology is based on transferring the energy stored in the cable to a capacitor at the end of the current pulse and then momentarily boosting the voltage with the capacitor applying to the cable at the beginning of the next current pulse. Thus, the rise time of the current pulses can be shortened. The topological states and operations of the compensator will be described. A simplified design procedure will be given. A prototype for a 12-V, 3-A PWM driver has been built and evaluated. Performance comparisons between the proposed current compensator and prior art and between the systems with and without the compensators will be conducted.

Dynamics Model and Vibration Control of Piezoelectric Feeder in Semiconductor Manufacturing Assembly

A piezoelectric vibration feeder is a necessary device for semiconductor manufacturing assembly. Its function is to automatically transport individual chip parts by precision vibration instead of by manual operation. In this paper, a mechanical structure for the piezoelectric feeder and electrical controller is designed and a prototype is developed. A vibration simulation model is established in ANSYS by the finite element method (FEM), and the frequency and vibration modal is attained. The mass-elastic model is established and the frequency is calculated by the numerical method. To drive and control the vibration feeder, a hardware driver consisting of an ARM microcontroller, a sinusoidal pulse width modulation driver module, an inverter circuit of insulated gate bipolar transistor modules, and an LC filter is designed. To achieve resonant vibration, a self-tuned proportional integral derivative (PID) controller for frequency tracking is investigated using MATLAB Simulink simulation. The dynamics and performance of vibration control are then verified through experimental testing using a laser Doppler vibrometer and an impedance analyzer. The mechanical frequencies of the piezoelectric feeder in the FEM, the numerical model, and the experimental measurement are found to agree well. The PID controller used for frequency tracking ensures the resonant vibration, which improves the efficiency and robustness of the piezoelectric feeder.

A 40–170 MHz PLL-Based PWM Driver Using 2-/3-/5-Level Class-D PA in 130 nm CMOS

A high-speed driver that provides a pulsewidth modulated output while using a class-D Power Amplifier (PA) is described. A PLL-based architecture is employed, which eliminates the requirement for a precise ramp or triangular signal generator, and a high-speed comparator, which are typically used in pulsewidth modulation (PWM) generation. Multilevel signaling is proposed to enhance back-off as well as peak efficiency, which is critical for signals with high peak-to-average power ratios (PAPRs). A differential folded PWM scheme is introduced to achieve highly linear operation. 3-level operation is achieved without the requirement for additional supply source or sink paths, while 5-level operation is achieved with an additional supply source/sink path compared with the 2-level operation. The PWM driver has been implemented in a 130 nm CMOS process and can operate with a switching frequency of 40–170 MHz. For the 2-/3-/5-level PA operation, with a 500 kHz sinusoidal input and 60 MHz switching frequency, the measured THD is −61/−62/−53 dB and the corresponding efficiency is 71%/83%/86% with 175/200/220 mW output power level, respectively. Performance has also been verified for 2-/3-level PA with a high PAPR signal with 500 kHz bandwidth. While intended as a general-purpose amplifier, the approach is well-suited for applications such as power-line communications.

Hybrid Speed Control of a DC Motor for Magnetic Wireless Manipulation Based on Low Power Consumption: Application to a Magnetic Wireless Blood Pump

This paper presents the magnetic properties and hybrid speed controls for low power consumption of a portable external driver based on a dc motor with a magnet to drive a magnetic wireless blood pump. Within a portable system, having low power consumption is the most important factor. In this paper, we propose a hybrid control method using the pulse width modulation (PWM) and the variable electromagnetic-load method (VEML) to extend the driving time of a rechargeable battery. The VEML method plays the role of a variable mechanical load. To reduce overall power consumption, the PWM and VEML methods were used at low and high rotations per minute, respectively. Hybrid-control of the VEML and PWM methods resulted in power consumption reduction of up to 67.52%. For the wireless operation, the external driver allowed a synchronous radial coupling. Moreover, the VEML structure, which acted as a magnetic power generator, produced the electrical power. The observed ac signal from VEML was used to check rotations per minute without having to use a motor encoder. The proposed external driver consisted of a dc-motor, Nd–Fe–B type of cylindrical permanent magnet, a wound coil, a variable resistor, and a PWM driver. In addition, we investigated the magnetic characteristics of the driver through various simulations and experiments.

Open-loop Force Control of A Three-finger Gripper Through PWM Modulated Pneumatic Digital Valves

This paper proposes an open-loop force control system for a three-finger gripper using small digital solenoid valves modulated using PWM (Pulse-Width-Modulation) technique. These valves are good candidates for this robotic application because of their small dimensions, low weight and cost, simple structure and easy operation by means of on/off signals. A linear model for pressure control in the pneumatic actuator's thrust chamber was developed and tested experimentally. A large dead-band was introduced in the PWM driver in order to investigate a suitable method for its correction. Good results were obtained by correcting the static characteristic curve of the three-way equivalent valve that controls the flow rate exchanged with the pneumatic cylinder thrust chamber. These results can be applied to similar solutions with larger digital valves. Gripping mechanism efficiency and the effects of friction forces were taken into account in developing the force control.