Power Net Research Articles

Parametric Approach for Routing Power Nets and Passive Transmission Lines as Part of Digital Cells

In design and layout of rapid single flux quantum circuits, multiple independent biases are often desired to provide flexibility in timings of critical paths. In absence of automated power routing, power nets are often included as part of the layout cells. Multiple variants of each cell need to be manually created to support different biasing configurations. The parametric approach for routing power nets provides the flexibility to dynamically change biasing configurations, based on the same parametric cell. Multiple cells in a circuit block can be configured to be connected to a single power net or can be biased using several independent power nets. With the goal of minimizing the cell size, it is often difficult to maintain rotational symmetry for the power and passive transmission line (PTL) tracks. The parametric approach also enables rotating the cell while avoiding misalignment of the tracks. In addition, our implementation can dynamically add moat bridges to connect ground planes isolated by moats. This is especially useful to bridge very long moats that span two or more adjacent cells. Furthermore, this approach of dedicated tracks for power and PTL routing is also more amenable to design automation.

Experimental Investigations on Voltage Stability in Multilevel Power Nets

In recent years, more and more components in vehicles have been electrified in order to improve the safety and comfort of the passengers as well as the driving performance. Owing to these developments, it has become increasingly difficult to guarantee the voltage stability within the 12V as well as the high voltage power bus. However, a new degree of freedom arises, as the two power nets are connected in order to exchange energy. As a consequence, they are able to stabilize their voltage reciprocally. This paper deals with the analysis of how two voltage levels can be coupled actively in order to stabilize their voltages in power demanding situations. A power net test bench consisting of a 12V power net and a high voltage power net is built. In the 12V power net, original chassis and wiring harness are used in order to achieve the most realistic behavior. Furthermore, there are two control modes presented. In the power control mode, the power flow is increased preventively when the prediction model detects a critical situation that is likely to occur in the near future. In the voltage control mode, the voltage controller of the DC chopper converter is used to stabilize the power net voltage in real time. Both control methods can easily be implemented into a universal power distribution management system. The voltage control mode is experimentally investigated at the power net test bench and it is shown that the minimum voltage in very power-consuming driving situations is increased by about 1.5V per 1000W of applied power supplied by the DC chopper converter.

Voltage Stability and System Behavior of Cybernetic Loads in Vehicular Power Nets

Voltage stability has to be ensured within automotive power buses in order to reliably supply all components with sufficient energy. Especially in modern vehicles (conventional, hybrid electric, or electric), the stability is endangered due to electric loads with high dynamics, for example chassis control systems. In this paper, a power distribution management based on cybernetic principles is described. To manage the power flow efficiently, it is reasonable to distribute some intelligence from the central control unit to the system’s components such as loads. A load’s control algorithm is presented that is able to fulfill the power management functions autonomously. Its stability is examined both in theory and in real cases. Therefore, evaluation criterions are derived from the component’s system behavior. Based on the algorithm’s equations, the transfer function is defined in order to proof the stability. Furthermore, over 200 test cases had been conducted and analyzed at a power net test bench that contains the whole vehicular power net, including wiring harness and chassis ground. The impact of all variables and influence factors on the stability is checked and, likewise, malfunctions are examined, such as measurement errors or data transfer with long dead times. By this means, the most critical variables could be detected. Based on the results, some improvements of the control algorithm are made and, as a result, a stable implementation is realized.

Simulation of Frequency Converters Operation in Industrial Power Net

Frequency converters, used for induction motors regulation, cause higher voltage harmonic in power net. Level of harmonic depends upon inverter and power net parameters; sometimes power net parameters make more influence for electric energy quality than frequency converter parameters. In this research some models of frequency converters were analyzed, comparing simulation results each with other and with real converter voltages and currents measurement results. Analysis of voltage harmonics in power nets with frequency inverters was done in this article, analyzing influence of power net parameters to power quality. Ill. 14, bibl. 7, tabl. 2 (in English; abstracts in English and Lithuanian).DOI: http://dx.doi.org/10.5755/j01.eee.117.1.1055

Full-chip multilevel routing for power and signal integrity

Conventional physical design flow separates the design of power network and signal network. Such a separated approach results in slow design convergence for wire-limited deep sub-micron designs. In this paper, we present a novel design methodology that simultaneously considers global signal routing and power network design under integrity constraints. The key part to this approach is a simple yet accurate power net estimation formula that decides the minimum number of power nets needed to satisfy both power and signal integrity constraints prior to detailed layout. The proposed design methodology is a one-pass solution to the co-design of power and signal networks in the sense that no iteration between them is required in order to meet design closure. Experiment results using large industrial benchmarks show that compared to the state-of-the-art alternative design approach, the proposed method can reduce the power network area by 19.4% on average under the same signal and power integrity constraints with better routing quality, yet use less runtime.

Automatic Variable-Width Routing for VLSI

Some of the essentials for layout of complex VLSI circuits are hierarchical design based on macrocells of arbitrary size and shape, power nets with local varying width, signal nets with individual width and very compacted layouts which still have to guarantee all geometrical design rules. This paper is devoted to the problem of automatic routing with real geometries. VWROUT, a Variable Width Routing System is presented. This includes planar power net routing with variable width on a single layer, loose and final routing of signal nets with variable width on two layers (H-V routing), and layout compaction with design-rule verification. Though automatic routing systems have been developed successfully, the intention of this paper is to demonstrate that layout programs of today have not yet become perfect. A lot of effort in software development is necessary in order that automatic layouts can compared with manual designs.