Method and apparatus for determining state of inverter capacitor in an electric drive
First Claim
1. A method of inverter capacitance diagnosis for detecting an imminent failure of one or more inverter capacitors in an electric power supply system for a machine having a prime mover and a generator receiving power from the prime mover and producing electrical power that is processed and made available on a DC link, the method comprising:
- detecting that the generator has ceased generating electrical power;
in response to detecting that the generator has ceased generating electrical power, waiting for a voltage of the DC link to reach a first predetermined voltage;
after the voltage of the DC link reaches the first predetermined voltage, taking a plurality of current samples on the DC link until a second predetermined voltage is reached on the DC link;
after the second predetermined voltage is reached on the DC link, integrating the plurality of current samples as a function of time to create a discharge integral;
comparing the discharge integral to a previously obtained discharge integral if a previously obtained discharge integral is available; and
setting a diagnostic flag to indicate an imminent failure of the one or more inverter capacitors if the discharge integral varies from the previously obtained discharge integral by more than a predetermined value.
1 Assignment
0 Petitions
Accused Products
Abstract
A method of inverter capacitance diagnosis for detecting an imminent failure of one or more inverter capacitors in an electric power supply system for a machine detects that the generator has ceased generating electrical power takes a plurality of current samples on the DC link between predetermined voltage points. The plurality of current samples are integrated as a function of time to create a discharge integral, which is compared to a previously obtained discharge integral if available. The process sets a diagnostic flag to indicate an imminent failure of the one or more inverter capacitors if the discharge integral varies from the previously obtained discharge integral by more than a predetermined value.
19 Citations
20 Claims
-
1. A method of inverter capacitance diagnosis for detecting an imminent failure of one or more inverter capacitors in an electric power supply system for a machine having a prime mover and a generator receiving power from the prime mover and producing electrical power that is processed and made available on a DC link, the method comprising:
-
detecting that the generator has ceased generating electrical power; in response to detecting that the generator has ceased generating electrical power, waiting for a voltage of the DC link to reach a first predetermined voltage; after the voltage of the DC link reaches the first predetermined voltage, taking a plurality of current samples on the DC link until a second predetermined voltage is reached on the DC link; after the second predetermined voltage is reached on the DC link, integrating the plurality of current samples as a function of time to create a discharge integral; comparing the discharge integral to a previously obtained discharge integral if a previously obtained discharge integral is available; and setting a diagnostic flag to indicate an imminent failure of the one or more inverter capacitors if the discharge integral varies from the previously obtained discharge integral by more than a predetermined value. - View Dependent Claims (2, 3, 4, 5, 6)
-
-
7. A computer-readable medium having thereon computer-executable instructions for performing a method of inverter capacitance diagnosis for detecting an imminent failure of one or more inverter capacitors in an electric power supply system for a machine having a prime mover and a generator receiving power from the prime mover and producing electrical power that is processed and made available on a DC link, the computer-executable instructions comprising:
-
instructions for detecting that the generator has ceased generating electrical power; instructions for waiting for waiting for a voltage of the DC link to reach a first predetermined voltage in response to detecting that the generator has ceased generating electrical power; instructions for taking a plurality of current samples on the DC link until a second predetermined voltage is reached on the DC link; instructions for integrating the plurality of current samples as a function of time to create a discharge integral after the second predetermined voltage is reached on the DC link; instructions for comparing the discharge integral to a previously obtained discharge integral if a previously obtained discharge integral is available; and instructions for setting a diagnostic flag to indicate an imminent failure of the one or more inverter capacitors if the discharge integral varies from the previously obtained discharge integral by more than a predetermined value. - View Dependent Claims (8, 9, 10, 11, 12, 13)
-
-
14. A controller for controlling one or more aspects of operation of an electric power supply system in a direct drive electric system having a prime mover and a generator receiving power from the prime mover and producing electrical power that is processed via one or more inverter capacitors and made available on a DC link, the controller embodying computer-executable instructions on a computer-readable medium to perform steps including:
-
detecting that the generator has ceased generating electrical power; in response to detecting that the generator has ceased generating electrical power, waiting for a first predetermined voltage to be reached on the DC link; after the predetermined voltage to be reached on the DC link, taking a plurality of current samples on the DC link until a second predetermined voltage is reached on the DC link; after the second predetermined voltage is reached on the DC link, integrating the plurality of current samples as a function of time to create a discharge integral; comparing the discharge integral to a previously obtained discharge integral if a previously obtained discharge integral is available; and setting a diagnostic flag to indicate an imminent failure of the one or more inverter capacitors if the discharge integral varies from the previously obtained discharge integral by more than a predetermined value. - View Dependent Claims (15, 16, 17, 18, 19, 20)
-
Specification