No full-text available
To read the full-text of this research,
you can request a copy directly from the authors.
Accurate, high-speed simulation of transient response and frequency characteristics of switching converters
Abstract
This paper proposes a fast, precise transient response and frequency characteristics simulation method for switching converters. This method uses a behavioral simulation tool (MATLAB/Simulink) without using a SPICE-like analog simulator. The nonlinear operation of the circuit is considered, and the nonlinear function is realized by defining the formula based on the circuit operation and by applying feedback. The transient response and frequency characteristics of a current-mode boost DC-DC converter and a charge pump that were designed using a 0.18-um CMOS process were simulated by SPICE and the proposed program on a behavioral simulation tool, which we named NSTVR (New Simulation Tool for Voltage Regulators). Simulation results showed good agreement, yet NSTVR was more than 85 times faster than SPICE in CPU time in calculating frequency characteristics of a current-mode boost DC-DC converter.
... In [19], the fast method of estimation of transient response and frequency characteristics of switching converters is proposed. In the simulations performed with the use of MATLAB-Simulink, the nonlinearities of elements of the considered circuit were taken into account. ...
... This method requires formulating some analytical dependence describing the function realized by the considered circuit. Examples of the analysis results given in [19] show that the method described in the cited paper is faster than the classical transient method by SPICE. A very important phenomenon called self-heating, affecting the device characteristics shape, is not included in the methods mentioned previously. ...
In this paper, a new method for fast estimation of the characteristics of single-inductance dc-dc converters at the steady state with self-heating taken into account is proposed. This method is based on the special memoryless convolution algorithm. The method is described in detail. The theoretical considerations are illustrated with simulation results of buck and boost converters.
A current-mode control power convertor model that is accurate at
frequencies from DC to half the switching frequency is described for
constant-frequency operation. Using a simple pole-zero transfer
function, the model is able to predict subharmonic oscillation without
the need for discrete-time z -transform models. The accuracy of
sampled-data modeling is incorporated into the model by a second-order
representation of the sampled-data transfer function which is valid up
to half the switching frequency. Predictions of current loop gain;
control-to-output; output impedance; and audio susceptibility transfer
functions were confirmed with measurements on a buck converter. The
audio susceptibility of the buck converter can be nulled with the
appropriate value of external ramp. The modeling concentrates on
constant-frequency pulse-width modulation (PWM) converters, but the
methods can be applied to variable-frequency control and discontinuous
conduction mode
This paper introduces and proposes a transient and frequency-response simulation method for switching converters that is both fast and precise; this method uses a behavioral simulation tool without using a SPICE-like analog simulator. The behavioral model is constructed such that it is based on real circuit operation. The non-linear operation of the circuit is considered by splitting the circuit into two parts; the one for the linear part and another for the non-linear part. The nonlinear function is realized by defining the formula based on the circuit operation and by applying feedback. The transient and frequency-response characteristics of the designed and fabricated current-mode buck DC-DC converter using a 0.35-um CMOS process were simulated by SPICE and the proposed program on a behavioral simulation tool, which we named NSTVR (The New Simulation Tool for Voltage Regulators). Comparing the evaluation results of the chip as well, the three kinds of results showed good agreement even though NSTVR was more than 100 times faster than SPICE in CPU time.
Stability is the key requirement in designing switching converter ASIC. Achieving this requires an accurate loop gain design. Since DC-DC switching converters are time-varying system, traditional small signal analysis in SPICE cannot be directly used to simulate the loop gain of this kind of system. A new method named periodic small signal analysis is proposed to analyze and simulate DC-DC switching converter inside a SPICE like simulator without the need for averaging. This general method is suitable for any switching regulators. The results are accurate comparing with average modeling and experiment results even beyond half switching frequency. A general procedure to design loop gain is demonstrated in a peak current control buck.
Presented herein is a frequency-domain analysis approach using Matlab simulink models via fast Fourier transform (FFT) of DC-DC converter closed-loop systems without small-signal linearization. Two modeling techniques are used: 1) average large-signal model; 2) pulse-by-pulse switching. It is shown that the frequency response result obtained with the Matlab Simulink and PSPICE model using average large-signal technique is comparable. Moreover, contrary to using PSPICE, obtaining frequency response using FFT via the Matlab Simulink model with the pulse-by-pulse switching method is easy and straightforward. The reason is that Matlab can accommodate script files for repetitive simulation data processing, whereas PSPICE cannot. Frequency domain analysis on the dc-dc converter model using the pulse-by-pulse switching technique leads to a more accurate result since all nonlinear elements in the circuit are included. The proposed "software analyzer approach" is demonstrated and validated with a converter power system operating in the solar-array voltage regulation mode.
Performance comparison between SPICE and NSTVR. Fig. 6. Transient response of a charge pump (no load)
- Fig
Fig. 5. Performance comparison between SPICE and NSTVR.
Fig. 6. Transient response of a charge pump (no load).