Galvanically isolated monitoring circuit

A system for monitoring a voltage developed by a component, the system comprising:

• a measurement circuit comprising a primary inductor, a voltage pulse generator for applying voltage pulses across the primary inductor, a first capacitor and a first resistance connected across the first capacitor;
• a galvanically isolated circuit including a secondary inductor, a second capacitor coupled to the secondary inductor, and the component connected across the second capacitor;
• and
• a measuring device for measuring a voltage across the first capacitor,
• wherein the primary and secondary inductors are inductively coupled by a magnetic core to form a flyback transformer;
• and
• wherein the galvanically isolated circuit is configured to prevent a current induced in the secondary inductor by the primary inductor during the voltage pulses from flowing in a first direction through the galvanically isolated circuit, so that energy from the voltage pulses is stored in the magnetic core, and
• configured to permit current to flow in a second direction through the galvanically isolated circuit between pulses, so that the energy stored in the magnetic core is released into the first and second capacitors, whereby after a plurality of the voltage pulses the system is in a substantially stable state, in which a substantially stable voltage VC1 across the first capacitor is proportional to a substantially stable voltage VC2 across the second capacitor, and VC1 is representative of the voltage developed by the component.

A method for calibrating a measurement circuit for use in measuring an environmental parameter experienced by a resistive component in a galvanically isolated circuit inductively coupled to the measurement circuit by a transformer, the method comprising:

• applying a known value of the environmental parameter to the resistive component;
• applying voltage pulses to the transformer from the measurement circuit;
• measuring a voltage across a capacitor in the measurement circuit;
• determining if the measured voltage is higher or lower than an expected value for the known value of the environmental parameter;
• adjusting a duty cycle of the voltage pulses applied to the transformer until the measured voltage matches the expected value;
• correlating the known value of the environmental parameter and the duty cycle at which the measured voltage matches the expected value;
• and
• storing the correlation.

A method for calibrating a measurement circuit for use in measuring a control parameter represented by a voltage developed by a component in a galvanically isolated circuit inductively coupled to the measurement circuit by a transformer, the method comprising:

• applying a known value of the control parameter to the component;
• applying voltage pulses to the transformer from the measurement circuit;
• measuring a voltage across a capacitor in the measurement circuit;
• determining if the measured voltage is higher or lower than an expected value for the known value of the control parameter;
• adjusting a duty cycle of the voltage pulses applied to the transformer until the measured voltage matches the expected value;
• and
• correlating the known value of the control parameter and the duty cycle at which the measured voltage matches the expected value;
• and
• storing the correlation.