Or Kirshenboim

Stability Analysis of Boundary and Hybrid Controllers for Indirect Energy Transfer Converters

In boost converters and other indirect energy transfer topologies, transient-oriented controllers are designed to facilitate a dynamic response that may range from minimum time up to minimum output voltage deviation. Since analytical definitions for these control laws can become quite complex, a large-signal stability verification is not immediate. This paper explores the existence of stability of indirect energy transfer converters that are controlled by either boundary or hybrid controllers and introduces a new simplified procedure for examination of large-signal stability of a given converter and load type using a graphical-analytical approach. The stability analysis and examination method are demonstrated on a boost converter loaded by resistive load and constant current load. The stability conditions are verified using a 30 W 3.3-to-12 V boost converter prototype, controlled by a programmable-deviation controller and time-optimal controller, verifying their large-signal stability.

ZCS resonant converter based parallel balancing of serially connected batteries string

This paper introduces a new topology for parallel balancing of serially connected batteries string. The main advantage of the balancing concept is that energy is transferred only when the cells are unbalanced. As a result, the power losses are significantly reduced since no current circulates through the system when balanced. This has been enabled by a modification of an isolated series-resonant converter operating in DCM and features zero current switching (ZCS). Another attractive feature is that one transformer for two cells is used, as opposed to conventional isolated topologies that require a transformer per cell. The realization is simple and requires simple current polarity detector. Experimental results have been obtained by a prototype of two series connected batteries, which demonstrates the balancing capabilities of the system.

Improving loading and unloading transient response of a voltage regulator module using a load-side auxiliary gyrator circuit

This paper introduces a new voltage regulator module (VRM) that hybrids a highly efficient switched-inductor converter as the main unit with a loadside switched-capacitor based converter to assist during load transient events. The resulting hybrid-VRM exhibits improved dynamic performance for both loading and unloading transient events, while maintaining a compact design with reduced stress of the components. The hybrid controller that has been developed allows operation based on output voltage measurement alone, further reducing the circuit complexity. The operation of the VRM is verified on a 30W, 12V-to-1.5V prototype, demonstrating a near-ideal transient recovery.

Minimum-time within a deviation-constrained hybrid controller for boost converters

This paper introduces a new transient-oriented controller for boost-type converters. The controller incorporates a peak current programmed mode control for steady-state operation and a non-linear, state-plane based transient-mode control for load transients. The new controller facilitate convergence from a loading transient to the new steady-state point within the minimum possible time while constraining the output voltage deviation to a desired (minimal) value. As a result, the loading transient performance of indirect energy transfer converters may be significantly improved since two control objectives (convergence time and undershoot) are simultaneously obtained. A detailed principle of operation of the controller is provided and explained through a state-plane analysis. The operation of the controller is experimentally verified on a 30W 3.3V-to-12V boost converter, demonstrating a significantly lower output voltage deviation and lower peak inductor current when compared to time-optimal control, allowing for volume reduction of the converter.

Plug-and-play electronic capacitor for VRM applications

This paper introduces a new plug-and-play transient suppression unit (TSU) to enhance the performance and reduce the overall volume of voltage regulator modules (VRMs). The TSU acts as an electronic capacitor that is realized by switched-capacitor technology, mimics an increased capacitance during load transients. The unit connects in parallel to any existing tightly-regulated power supply without affecting the performance, and does not require any changes or interference in the design of the VRM. The resultant dynamic performance for load transients is significantly improved while the steady-state precision of the original design is intact. Furthermore, the unit is fully independent and is connected at the load-side of the converter, and as a result does not affect the input filter. The operation of the electronic capacitor is verified on a 30W, 12V-to-5V commercial buck converter evaluation module, demonstrating a near-ideal transient recovery with reduced output voltage deviation and settling time.

Combined Multilevel and Two-Phase Interleaved LLC Converter With Enhanced Power Processing Characteristics and Natural Current Sharing

This paper introduces a new two-phase interleaved flying-capacitor LLC converter topology with high output current applications. Compared to a conventional two-phase LLC converter, the new converter adds a single capacitor that contributes to lower voltage stress on the primary sides switches, automatically balances the current distribution between the phases, and enhances the power processing capabilities. All the attractive features of LLC converters are preserved, such as zero-voltage switching on the primary sides mosfets, zero-current switching on the secondary sides power devices, narrow switching frequency range, and simple design. Full principle of operation and analysis of the converter are described, as well as the converters primary characteristics and the impact of nonideal components on the current sharing behavior. A 600 W, 400 V-to-12 V experimental prototype is used as a showcase of the attractive features of the new converter, demonstrating excellent current sharing, simple implementation, and high efficiency of up to 97.3%.

Fully Integrated Digital Average Current-Mode Control Voltage Regulator Module IC

This paper introduces a fully integrated 12-to-1.xV voltage regulator module IC. A fully synthesizable digital two-loop controller has been realized through hardware description language tools. Several new IP blocks have been developed and described in detail: a window delay-line-based analog to digital converter (DL-ADC), two independent PI compensators with shared hardware for calculations, high-resolution digital pulsewidth modulation (PWM), and a programmable dead-time module. To fully exploit the benefits of digital electronics, reduce power consumption, and save area, all units of the digital controller have been designed through asynchronous architecture, eliminating the need of high-speed clock. High-performance synchronized, fixed frequency, PWM operation is enabled by a digital programmable time-base generator and system governor, which has been developed as well. In addition, to extend the capabilities of the window DL-ADC to support the full range of the load with minimal hardware penalty, adaptive reference of the current compensation is introduced. The mixed-signal IC has been fabricated on a 0.18-

Two-phase LLC converter using a flying capacitor for high output current applications

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Hardware efficient digital auto-tuning average current-mode controller

5-V CMOS process. It incorporates the digital controller and periphery as well as a synchronous buck power stage, including a drive circuitry that enables operation up to several megahertz from a 12-V input. The digital core has been realized by an automated synthesis process and place-and-route tools, resulting in an effective silicon area of 0.16 mm2. Experimental results of the fabricated IC operating in closed loop are provided, demonstrating the performance and benefits of the new controller for meeting the requirements of tight output voltage regulation over wide load range.

Parallel balancing converter for serially connected batteries string

This paper introduces a new two-phase interleaved flying-capacitor LLC converter topology with high output current applications. Compared to a conventional two-phase LLC converter, the new converter adds a single capacitor that contributes to lower voltage stress on the primary sides switches, automatically balances the current distribution between the phases and enhances the power processing capabilities. All the attractive features of LLC converters are preserved, such as zero-voltage switching on the primary sides MOSFETs, zero-current switching on the secondary sides power devices, narrow switching frequency range and simple design. Full principle of operation and analysis of the converter is described, as well as the converters primary characteristics and the impact of non-ideal components on the current sharing behavior.