Abstract
In this work, an idea of a wideband, precision, power electronics programmable voltage source (PVS) is presented. One of the basic elements of the converter, the control section, contains a continuous-time sigma-delta modulator (SDM) with a pair of interconnected complementary comparators, which represents a new approach. In this case, the SDM uses comparators with a dynamic hysteresis loop (DHC) that includes an AC circuit rather than an R-R network. Dynamic hysteresis is a very effective way of eliminating parasitic oscillation during the signal transition at the input of the comparator; it also affects the frequency characteristics and, especially, the phase properties of the comparator, and this phenomenon is exploited in the proposed converter. The main disadvantage of all pulse-modulated converters is the presence of a ripple component in the output voltage (current), which reduces the quality of the output signal and may cause high-frequency disturbances. A basic feature of PVS is a lower RMS value for the pulse modulation component in the output voltage of the converter, compared to the typical value. Another important feature of the proposed converter is the ability of precise mapping of the output voltage to the reference (input) signal. The structure of the control circuit is relatively simple—no complex, digital components are used. Due to the high frequency of the SDM output bit-stream, the simulation model of the power stage of PVS is based on the power modules with gallium-nitride field effect transistors (GaN FETs). The work discusses the rules of PVS operations and the results from PVS simulation model studies as well as highlights the possible application fields for systems with a PVS.
Highlights
Nonlinearities in loads, limited frequency responses for power electronics converters, and the wide-band nature of both signal sampling and pulse modulation processes are some of the possible reasons for inaccurate mapping of a converter’s output voltage to a reference signal
The values given for the relationship between the time constants of the riod varies with the magnitude of the input signal to the sigma-delta modulator (SDM) (i.e., modulation index integrator and dynamic hysteresis comparators (DHCs) are exemplary ones, but they indirectly result from (4) and (5)
The values of parameters are related to application of the programmable voltage source (PVS) as a medium presented
Summary
Nonlinearities in loads, limited frequency responses for power electronics converters, and the wide-band nature of both signal sampling and pulse modulation processes are some of the possible reasons for inaccurate mapping of a converter’s output voltage to a reference signal. To address this problem, advanced converter solutions are necessary, in terms of both hardware and control algorithms. The proposal of a self-exciting, continuous-time SDM with a pair of interconnected dynamic hysteresis comparators (DHCs) to control the output stage of a power electronics programmable voltage source (PVS) [17,18] is presented.
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