TRANSISTOR SWITCH CONTROL PROCESS Russian patent published in 1998 - IPC

FIELD: automatic control of power transistor switches built around bipolar transistors and used for contactless switchgear and protective gear. SUBSTANCE: transistor switch base current is produced to maintain minimal level of dissipated power and not to maintain constant voltage drop across transistor switch. Process involves current supply to and regulation in base circuit. Regulated ac current is supplied to base circuit simultaneously with DC current and its amplitude is lower than DC current level; non-regulated ac current is also supplied to base circuit, its amplitude being as low as possible to ensure reliable discrimination of this component on background of noise. Total ac current components are measured in base and power circuits of transistor switch, and they are compared. Differential signal DC component is discriminated and used for regulation. Low-magnitude ac component fed to transistor switch base circuit followed by comparing response of transistor switch to this component enables determination of transistor switch state. EFFECT: minimized unwanted heat loss across transistor switch; improved control accuracy. 1 dwg