Power converter, diagnostic system of power converter, and power converter diagnostic method using current change

A power converter comprising:

• a current change amount calculation section which includes a current change amount calculation circuit configured to calculate a current change amount within a predetermined time period in a switching operation between conduction and interruption of a principal current flowing through a main circuit constituted by a power semiconductor, or a time needed for transition of a predetermined current change amount,
• wherein the current chance amount calculation section is configured to make a comparative determination of whether or not the current change amount or the time needed for transition deviates from a reference value,
• wherein at least one of operations to display a determination result, output the determination result, and control an operation condition of a switching element as the power semiconductor in accordance with the determination result is conducted,
• wherein the current change amount calculation section includes a voltage output circuit for outputting a voltage, value proportional to a current change, rate of the principal current per unit time, or corresponding to the current change rate with a function,
• wherein the output is integrated for a predetermined time period in the switching operation, and the current change amount is calculated using a result of the integration,
• wherein the current change amount calculation section further comprises an integration circuit including a resistor, a capacitor, and an operational amplifier, which integrates and input voltage value proportional to the current change rate or corresponding to the current change rate in accordance with a function, and a circuit which discharges a charge of the capacitor of the integration circuit for a specified time period for resetting, and
• wherein the reset is released within a predetermined time period in the switching operation.

A diagnostic method of a power converter which includes a semiconductor switching element for a switching operation between conduction and interruption of a principal current, the method comprising:

• a first step of detecting a current change amount of the principal current per unit time;
• a second step of integrating the current change amount through a digital circuit or an analog circuit for a predetermined time period;
• and
• a third step of determining a state of the power converter based on a result of the integration,
• wherein the second step of integrating further comprises integrating an input voltage, value proportional to a current change, rate or corresponding to the current change rate in accordance with a function, using an integration circuit which includes a resistor, a capacitor, and an operational amplifier, and a circuit which discharges a charge of the capacitor of the integration circuit for a specified time period for resetting, and
• wherein the reset is released within a predetermined time period in the switching operation.