Non-invasive online monitoring circuit for on-state saturation voltage of power semiconductor

A non-invasive online monitoring circuit for an on-state saturation voltage of a power semiconductor, consisting of two basic units, wherein each of the two basic units comprises a normally-ON switching device, a diode and a clamping voltage supply;

• a gate of the normally-ON switching device is connected to a positive electrode of the clamping voltage supply;
• a positive electrode of the diode is connected to a source of the normally-ON switching device, and a negative electrode of the diode is connected to the gate of the normally-ON switching device;
• a drain of the normally-ON switching device and a negative electrode of the clamping voltage supply serve as input terminals of the non-invasive online monitoring circuit for accessing a power semiconductor under test;
• and the source of the normally-ON switching device and the negative electrode of the clamping voltage supply serve as output terminals of the non-invasive online monitoring circuit;
• when the power semiconductor under test in an on state, the diode is in an off state, the normally-ON switching device is in an on state, and the output terminals of the non-invasive online monitoring circuit are the on-state saturation voltage of the power semiconductor under test;
• when the power semiconductor under test in an off state, the diode is in an on state, the normally-ON switching device is in an off state, and an output voltage of the non-invasive online monitoring circuit is clamped at a voltage value of the clamping voltage supply;
• a rating voltage of the normally-ON switching device is higher than the highest rating voltage of the power semiconductor under test, and the voltage value of the clamping voltage supply is higher than the maximum value of the on-state saturation voltage of the power semiconductor under test;
• the two basic units are employed to implement a monitoring of the on-state saturation voltages of two power semiconductors of a half-bridge circuit, and the two basic units are marked as a first basic unit and a second basic unit;
• a positive electrode of a clamping voltage supply in the first basic unit is connected to a source of a normally-ON switching device in the second basic unit;
• a drain of a normally-ON switching device in the first basic unit and a drain of the normally-ON switching device in the second basic unit serve as the input terminals of the non-invasive online monitoring circuit for accessing a power semiconductor on an upper bridge arm of the half-bridge circuit, and a source of the normally-ON switching device in the first basic unit and a source of the normally-ON switching device in the second basic unit serve as the output terminals of the non-invasive online monitoring circuit for monitoring the on-state saturation voltage of the power semiconductor on the upper bridge arm of the half-bridge circuit of the half-bridge circuit;
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• the drain of the normally-ON switching device in the second basic unit and a positive electrode of a clamping voltage supply of the second basic unit serve as input terminals of the non-invasive online monitoring circuit for accessing a power semiconductor on a lower bridge arm of the half-bridge circuit, and the source of the normally-ON switching device in the second basic unit and a positive electrode of the clamping voltage supply of the second basic unit serve as the output terminals of the non-invasive online monitoring circuit for monitoring the on-state saturation voltage of the power semiconductor on the lower bridge arm of the half-bridge circuit.

A non-invasive online monitoring circuit for an on-state saturation voltage of a power semiconductor, consisting of four basic units, wherein each of the four basic units comprises a normally-ON switching device, a diode and a clamping voltage supply;

• a gate of the normally-ON switching device is connected to a positive electrode of the clamping voltage supply;
• a positive electrode of the diode is connected to a source of the normally-ON switching device, and a negative electrode of the diode is connected to the gate of the normally-ON switching device;
• a drain of the normally-ON switching device and a negative electrode of the clamping voltage supply serve as input terminals of the non-invasive online monitoring circuit for accessing a power semiconductor under test;
• and the source of the normally-ON switching device and the negative electrode of the clamping voltage supply serve as output terminals of the non-invasive online monitoring circuit;
• when the power semiconductor under test in an on state, the diode is in an off state, the normally-ON switching device is in an on state, and the output terminals of the non-invasive online monitoring circuit are the on-state saturation voltage of the power semiconductor under test;
• when the power semiconductor under test in an off state, the diode is in an on state, the normally-ON switching device is in an off state, and an output voltage of the non-invasive online monitoring circuit is clamped at a voltage value of the clamping voltage supply;
• a rating voltage of the normally-ON switching device is higher than the highest rating voltage of the power semiconductor under test, and the voltage value of the clamping voltage supply is higher than the maximum value of the on-state saturation voltage of the power semiconductor under test;
• the four basic units are employed to implement a converter-level on-state saturation voltage monitoring for six power semiconductors in a three-phase full-bridge power converter, and the four basic units are marked as a first basic unit, a second basic unit, a third basic unit, and a fourth basic unit;
• output terminals of the first basic unit are reversely connected to input terminals of the second basic unit;
• output terminals of the third basic unit are reversely connected to input terminals of the fourth basic unit;
• a positive electrode of the clamping voltage supply in the first basic unit is connected to a drain of the normally-ON switching device in the first basic unit;
• the drain of the normally-ON switching device in the first basic unit, the positive electrode of the clamping voltage supply in the first basic unit, and a positive electrode of the clamping voltage supply in the second basic unit serve as the input terminals of the non-invasive online monitoring circuit, and are connected to neutral points of three-phase half-bridge circuits in the three-phase full-bridge power converter;
• output terminals of the second basic unit serve as first output terminals of the non-invasive online monitoring circuit for acquiring information on the converter-level on-state saturation voltages of four power semiconductors in two-phase half-bridge circuit connected to input terminals of the first basic unit;
• and
• output terminals of the fourth basic unit serve as second output terminals of the non-invasive online monitoring circuit for acquiring information on the converter-level on-state saturation voltages of the four power semiconductors in the two-phase half-bridge circuit connected to input terminals of the third basic unit.