GB529625A - Improvements in and relating to electric inverting systems - Google Patents

Abstract

529,625. Converting. FRIEDLANDER, E. June 5, 1939, No. 16456. Convention date, June 4, 1938. [Class 38 (ii)] In an electric converter system such as an inverter system wherein (1) the alternating voltage is variable with the wattless current flowing between the inverter and the A.C. network so that the capacitative wattless power taken by the A.C. circuit decreases with rising alternating voltage and (ii) energy storing devices depending on frequency-i.e., rotating machines-are connected on the A.C. side, the means for effecting commutation from one anode or contact to the next in the inverter are arranged to advance the instant of commutation as the frequency of the output increases thereby preventing a " short circuit" effect through the energy storing device. For self excited inverters it may be arranged to vary the advance rapidly with increased frequency. In one form a saturated grid transformer T, Fig. 4, is connected through resistances R to the A.C. voltage of the inverter, condensers are arranged in parallel with the series resistances. Variation in voltage between the grid and anode voltages may be compensated; a rectifier system M, Fig. 5, is connected to the resistances R which all have condensers in parallel as in Fig. 4, the system being shunted by a choke C. To correct independently controlled inverters for temporary differences between the anode and grid frequencies, a grid transformer G, Fig. 6, is supplied from a source f through ah intermediate transformer z energized from the A.C. side of the inverter system. Frequency changing from one A.C to another may be similarly controlled.