This paper discusses the presence of steady-state limit cycles in digitally controlled pulse-width modulation (PWM) converters, and suggests conditions on the control law and the quantization resolution for their elimination. It then introduces single-phase and multi-phase controlled digital dither as a means of increasing the effective resolution of digital PWM (DPWM) modules, allowing for the use of low resolution DPWM units in high regulation accuracy applications. Bounds on the number of bits of dither that can be used in a particular converter are derived. Finally, experimental results confirming the theoretical analysis are presented.

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Quantization resolution and limit cycling in digitally controlled PWM converters

This paper describes a complete digital PWM controller IC for high-frequency switching converters. Novel architecture and configurations of the key building blocks are A/D converter, compensator, and digital pulse-width modulator, are introduced to meet the requirements of tight output voltage regulation, high-speed dynamic response, and programmability without external passive components. The implementation techniques are experimentally verified on a prototype chip that takes less than 1 mm/sup 2/ of silicon area in a standard 0.5 /spl mu/ digital complementary metal oxide semiconductor (CMOS) process and operates at the switching frequency of 1 MHz.

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High-frequency digital PWM controller IC for DC-DC converters

A control system and method for simultaneously regulating the operation of a plurality of different types of switching power converters. The system utilizes in regulating the power converters sampled data and nonlinear feedback control loops.

Power converter circuitry and method

In this paper, we discuss the impact of digital control in high-frequency switched-mode power supplies (SMPS), including point-of-load and isolated DC-DC converters, microprocessor power supplies, power-factor-correction rectifiers, electronic ballasts, etc., where switching frequencies are typically in the hundreds of kHz to MHz range, and where high efficiency, static and dynamic regulation, low size and weight, as well as low controller complexity and cost are very important. To meet these application requirements, a digital SMPS controller may include fast, small analog-to-digital converters, hardware-accelerated programmable compensators, programmable digital modulators with very fine time resolution, and a standard microcontroller core to perform programming, monitoring and other system interface tasks. Based on recent advances in circuit and control techniques, together with rapid advances in digital VLSI technology, we conclude that high-performance digital controller solutions are both feasible and practical, leading to much enhanced system integration and performance gains. Examples of experimentally demonstrated results are presented, together with pointers to areas of current and future research and development.

Impact of digital control in power electronics

A highly phased power regulation (converter) system having an improved control feature is provided. A controller, such as a digital signal processor or microprocessor, receives digital information from a plurality of power conversion blocks and transmits control commands in response to the information. The controller is able to change the mode of operation of the system and/or re-phase the power blocks to accommodate a dynamic load requirement, occasions of high transient response or detection of a fault. A compensation block within the controller is used to regulate the output voltage and provide stability to the system. In one embodiment, the controller is implemented as a PID compensator controller. In another embodiment, a microprocessor is able to receive feedback on its own operation thus providing enabling the controller to anticipate and predict conditions by analyzing precursor data.

System and method for highly phased power regulation using adaptive compensation control

Conventionally, controllers for DC/DC converters have relied on analog circuit techniques for implementation. While analog based systems have proven successful, several reasons make digital control attractive. Digital control allows for the implementation of more functional control schemes. Digital circuits are potentially less susceptible to noise and parameter variations. With the explosion of cheap computing power, and availability of advanced integrated circuit design and synthesis tools, a digital controller design can be ported to new integrated circuit technology generations with little additional effort. Current trends in microprocessor designs lead toward decreasing supply voltages and increasing current demands. Future microprocessors are projected to require between 30-60 Amps of static current and impose di/dt requirements on the power supply in the order of 5 A/ns. In this paper, we focus on the design of a digital controller for an interleaved DC/DC buck converter to supply power for microprocessor loads. Digital logic makes the generation of identical, but delayed, gate drive signals for the various phases of the interleaved converter simple.

A.M. Wu

Papers

Digital PWM control: application in voltage regulation modules