Duty cycle modulated universal binary input circuit with reinforced isolation

An intelligent electronic device (IED) of an electric power system, comprising:

• an input protection subcircuit to provide over-voltage protection from a received binary voltage input;
• a voltage rectification subcircuit to rectify the binary voltage input to provide a rectified supply voltage;
• a voltage regulation subcircuit to receive the rectified supply voltage and generate a regulated direct current (DC) voltage for pulse width modulation;
• a duty cycle modulation subcircuit to pulse width modulate the regulated DC voltage to generate a drive signal to drive an input of an optocoupler, wherein the drive signal is inversely and nonlinearly proportional to the regulated DC voltage to decrease power dissipation as the regulated DC voltage increases;
• and
• a controller to:
• receive an output signal from the optocoupler, and
• determine a protective action based on the received output signal from the optocoupler.

A method of providing an intelligent electronic device (IED) with reinforced isolation from a binary voltage input via a binary input circuit, comprising:

• receiving, via a binary input port of the binary input circuit, a binary input voltage between approximately 0 and 300 volts;
• protecting the binary input circuit from binary input over-voltages via an input protection subcircuit;
• rectifying the binary input voltage to produce a rectified DC voltage;
• regulating the rectified DC voltage to produce a regulated DC voltage;
• pulse width modulating the regulated DC voltage to generate a pulse width modulated drive signal;
• driving a light emitting diode of an optocoupler with the pulse-width modulated drive signal, wherein the drive signal is inversely and nonlinearly proportional to the regulated DC voltage to decrease power dissipation as the regulated DC voltage increases;
• and
• receiving, via a controller of the IED, an output signal from the optocoupler.