Easy current slope detection for low cost implementation of the direct adaptive current control for DC-DC-converters

Abstract

Direct Adaptive Current Control" (DACC) is a completely adaptive current control scheme with excellent control quality and high dynamics. It is based on the detection of the current slopes during each switching state of the utilized inverter and identifies the system within one period. One method to measure the current slopes is fast oversampling of the current followed by a least squares estimator to filter the noise. This is well-proven but is difficult at high switching frequencies and implies the use of powerful hardware. In this paper a new algorithm for the detection of the current slopes in DC/DC-Converters is presented that does not need oversampling or a complex filter. Its simplicity allows for easy implementation in low-cost microcontrollers and operation at high switching frequencies. The presented algorithm enables the implementation of the DACC as a low-cost, high dynamic and completely adaptive current control scheme for fastswitching DC/DC-Converters.

Resource optimal FPGA implementation of a Least-Squares-Estimator for fast and robust online measurement of current slope and absolute value

“…To be able to do this, the necessary elements of the pseudoinverse (O) + N must be known. An online calculation of the needed elements of (O) + N according to (8) though is comparatively complex and generates huge computational effort due to the necessary matrix inversions. But since all elements of the observer matrix are known constants (see (5)), the pseudoinverse can be calculated prior to normal operation and stored in a lookup-table (LUT).…”

“…With an increasing N, the distance between two consecutive elements of a given pseudoinverse (O) + N gets smaller but remains constant within (O) + N . Hence each single row vector of the pseudoinverses can be calculated not only by complex matrix operations according to equation (8), but also by a simple linear equation…”

“…One possibility to get the current slope is direct measurement with specially designed current slope sensors (direct methods) [6]. Another possibility is to calculate the derivative of the absolute value of the measurement signals (indirect methods) [7,8,9]. Among the many mathematical possibilities to do this, the use of a Least-Squares-Estimator (LS-Estimator) has proven to be a good choice.…”

A Modular Converter- and Signal-Processing-Platform for Academic Research in the Field of Power Electronics

“…The converter was equipped with measuring systems for the output currents, the heatsink temperature, the DC-link voltage and the output voltages. The combination of switching frequencies in the range up to 100 kHz and new control methods like Direct Adaptive Current Control [5] leads to high demands on the current measurement. Therefore, CMS3000 family current sensors from SENSITEC with a bandwidth of 2 MHz were applied.…”

Direct flux linkage control scheme for highly utilized DC/DC converters with simple interleaving method

“…Even current control schemes like [16], [17], which are able to adapt for a varying inductance, are not necessarily applicable for high current ripples. These schemes make the assumption ∆i k = ∆i k+1 , which is violated, if the current trajectory is no straight line segment.…”