US 5,515,258 A · Drive device for a push-pull stage

Abstract

A drive device for a push-pull stage includes a microcontroller in the form of a pulse-width modulator which, starting with a selected switching frequency, varies the pulse-duty ratio (modulation) of the pulse-width modulated output signal and which, with chronological delay, controls the push-pull stage. The push-pull stage has at least one upper and one lower power switch, and the microcontroller has three pulse-width modulation outputs. The actual pulse-width modulated output signal is delivered at the first output, the modulated signal plus a dead time is delivered at the second output and is supplied to the lower power switch as a drive signal, and the dead time by itself is delivered at the third output. The drive signal for the upper power switch is formed by the difference between the modulated signal and the inverted dead time is automatically decreased in the limit region of the modulation, i.e., when the modulation approaches 100% or 0%, and one power switch is continuously switched on, whereas the other power switch is switched off during the same time. Beginning with a specific limit value of the modulation, a power bit is regularly delivered at a fourth output, which effects a 100% modulation.

Claims16

Dependent claims

A drive device for a push-pull stage having a first power switch and a second power switch, said drive device comprising:

pulse-width modulator means for generating a plurality of pulse-width modulation signals including a first output at which an actual pulse-width modulation output signal is present, a second output at which a sum signal is present comprising the sum of said actual pulse-width modulation output signal and a dead time signal, said sum signal being supplied to one of said first or second power switches as a drive signal therefor, and a third output at which said dead time signal is present;
means for inverting said dead time signal to obtain an inverted dead time signal;
means for subtracting said inverted dead time signal from said actual pulse-width modulation output signal to obtain a drive signal supplied to the other of said first or second power switches;
said pulse-width modulator means including means for varying a pulse-duty ratio of said dead time signal for automatically shortening said dead time signal in a limit region of the modulation of said actual pulse-width modulation output signal for a time during which one of said first or second power switches is continuously switched on and the other of said first or second power switches is continuously switched off.

1 more element

Dependencies are inferred from the claim text.

Drive device for a push-pull stage

Life of this patent

Drive device for a push-pull stage

Life of this patent

Abstract

Claims16