Method for operating an electrical switching unit having at least one charging coil of an inductive charging device for a mobile terminal device, which can thus be charged in a motor vehicle with radio receiver, and switching unit, charging device and motor vehicle

摘要

The invention relates to a method for operating an inductive charging device (11) for a mobile terminal device (12) in a motor vehicle (10) with radio receiver (13),wherein switches (38) are periodically switched by a control circuit of the switching unit in a switching pattern (53) for pulse width modulation. The invention provides that the switching pattern (53) per period (52) comprises several pulses (57), which are respectively limited by a rising and a falling pulse flank and in the control circuit a respective phase position (56) of the pulse flanks is set within the respective period (52) by means of a switching data set (47) and the switching data set (47) phase positions (56) of the pulse flanks, where a Fourier transformation (67) of the resulting switching pattern (53) at frequencies,represent the harmonics of the carrier base frequency and which lie within a broadcast channel received by the radio receiver (13), gives Fourier coefficients (65) having a value less than 10 percent of the value of the Fourier coefficient (65) at the carrier base frequency.