Dependencies of the Distortion Factor of the Sinusoidality of the Recovery Current on the Parameters of the Process When Controlling the Forced Discharge of Accumulator Batteries Into the Network by Signal With Single-Cycle One-Way Pulse-Width Modulation

Abstract

For modern remote and closed systems of uninterruptible power supply, a operation of forced discharge of accumulator batteries is in demand. It is advisable to carry out the specified process of forced discharge with recuperation into the network. This way of leads: firstly, to a decrease in the mass of charging and discharging devices due to the exclusion of powerful resistive loads from the latter; secondly, to noticeable energy savings for closed autonomous objects. At the same time, for the regenerative current, increased requirements are imposed on its sinusoidality, the distortion coefficient of which is significantly influenced by the relationship between the EMF of the battery and the amplitude of the mains voltage, the discharge current and the maximum current of the coil of the active rectifier. The influence the frequency of the PWM control signal and the frequency of the regeneration current (mains frequency) is also possible. In uninterruptible systems, storage batteries are used with different total EMF and capacity that determines the discharge current. In addition, the mentioned values change during operation, and at forced discharge, various technique can be used that differ in the ratio of the discharge current to the capacity of the battery and the law of its change. Therefore, in the development of a universal system for forced discharge of a battery into a network with pulse-width control of the regenerative current shape, is relevant information on the dependences of the distortion factor of the sinusoidality on the above ratios of the battery voltage and the amplitude of the mains voltage, the discharge current and the maximum current of the coil of the active rectifier coil, as well as from the number of pulses for the regeneration current period. The article presents the results of work on obtaining diagrams of these dependencies. To obtain the latter, the function of the output current of the active rectifier is formed – of the regeneration current, then its spectral function. Using the latter, the current waveform distortions are estimated based on the spectral approach. The results obtained are in demand in the development of program modules for microcontrollers of the pulse-width regulators of the regeneration current, which implement algorithms for the formation of a current curve with acceptable values of the distortion coefficient of the sinusoidality when changing the parameters of the battery, network and discharge current.