Apparatus for inspecting electric component for inverter circuit

• US 5,497,095 A
• Filed: 11/08/1994
• Issued: 03/05/1996
• Est. Priority Date: 11/08/1993
• Status: Expired due to Term

• Current Assignee: Honda Giken Kogyo Kabushiki Kaisha (Honda Motor Company)
• Original Assignee: Honda Giken Kogyo Kabushiki Kaisha (Honda Motor Company)
• Inventors: Takano, Fumitomo, Tsukada, Yoshinari, Ueyama, Atsushi
• Primary Examiner(s): Wieder, Kenneth A.
• Assistant Examiner(s): BROWN, GLENN WARNER
• Application Number:
  US08/337,479
• Time in Patent Office: 483 Days
• Field of Search: 324/522, 324/532, 324/535, 324/537, 324/548, 324/677, 324/678, 324/765, 324/766, 324/767, 324/768, 324/769, 324/158.1, 340/635, 340/653
• US Class Current: 324/537
• CPC Class Codes: G01R 27/2605 Measuring capacitance capacitive sensors G01D5/24
• CPC Class Codes: G01R 31/27 Testing of devices without physical removal from the circuit of which they form part, e.g. compensating for effects surrounding elements testing printed circuit boards G01R31/2801
• CPC Class Codes: G01R 31/2843 In-circuit-testing
• CPC Class Codes: G01R 31/40 Testing power supplies testing photovoltaic devices H02S50/10
• CPC Class Codes: G01R 31/42 AC power supplies
• CPC Class Codes: G01R 31/64 Testing of capacitors

Abstract

An apparatus for inspecting an electric component in an inverter circuit has a DC power supply for supplying a direct current to a given position in an inverter circuit, a voltage detector for detecting a voltage at a given position in the inverter circuit, a current detector for detecting a current flowing at a given position in the inverter circuit, a switching circuit for changing positions at which the direct current is supplied from the DC power supply, positions at which the voltage is detected by the voltage detector, and positions at which the current is detected by the current detector, and a controller for outputting a switching signal to the switching circuit. The switching circuit is controlled by the controller to charge an electrolytic capacitor in an inverter circuit with a current from the DC power supply. The electrolytic capacitor is determined as to its quality by determining whether the calculated electrolytic capacitance of the electrolytic capacitor falls within a preset range or not. Each of the transistors of the inverter circuit is determined as to its quality by determining whether an V_CE -I_C curve thereof falls in a preset range or not. The electrolytic capacitor, the transistors, and also diodes connected across the transistors can be determined as to whether they are acceptable or not while they are being connected in the inverter circuit.

Claims

1. An apparatus for inspecting an electric component in an inverter circuit composed of a voltage-smoothing electrolytic capacitor, a plurality of transistors, and a plurality of diodes coupled in inverse parallel connection to said transistors, respectively, comprising:

a DC power supply for supplying a direct current to the inverter circuit;

voltage detecting means for detecting a voltage at a predetermined position in the inverter circuit;

current detecting means for detecting a current flowing at a predetermined position in the inverter circuit;

switching means for changing positions at which the direct current is supplied from said DC power supply to the inverter circuit, positions at which the voltage is detected in the inverter circuit by said voltage detecting means, and positions at which the current is detected in the inverter circuit by said current detecting means;

switching control means for outputting a switching signal to said switching means;

electrolytic capacitor determining means for calculating an electrostatic capacitance of the electrolytic capacitor based on a time consumed after the electrolytic capacitor has started being charged by the direct current supplied from said DC power supply through a resistor until a voltage across the electrolytic capacitor as detected by said voltage detecting means reaches a predetermined voltage, and also on a resistance of said resistor, and determining whether the electrostatic capacitance falls within a preset range; and

transistor determining means for determining whether a V_CE -I_C, curve generated from a collector-to-emitter voltage V_CE of each of the transistors as detected by said voltage detecting means and a collector current I_C of the transistor as detected by said current detecting means, falls within a preset range;

the arrangement being such that the electrolytic capacitor and the transistors will be determined as to whether they are acceptable or not by changing said positions at which the direct current is supplied from said DC power supply to the inverter circuit, said positions at which the voltage is detected in the inverter circuit by said voltage detecting means, and said positions at which the current is detected in the inverter circuit by said current detecting means, based on the switching signal outputted from said switching control means.

2. An apparatus according to claim 1, further comprising diode determining means for determining whether a forward current of each of the diodes as detected by said current detecting means at a voltage across the diode as detected by said voltage detecting means, falls within a preset range.

3. An apparatus according to claim 1, wherein said electrolytic capacitor determining means comprises determining means for calculating an equivalent series resistance of the electrolytic capacitor based on a voltage across the electrolytic capacitor as detected by said voltage detecting means when the electrolytic capacitor which has been charged starts being discharged, a voltage across the electrolytic capacitor as detected by said voltage detecting means while the electrolytic capacitor which has been charged is being discharged, and a discharged current of the electrolytic capacitor as detected by said current detecting means, and determining whether said equivalent series resistance falls within a preset range.

4. An apparatus according to claim 3, wherein the electrolytic capacitor is discharged through at least one of the transistors of the inverter circuit.

5. An apparatus according to claim 3, wherein the electrolytic capacitor has been charged until a voltage across the electrolytic capacitor remains unchanged.

6. An apparatus according to claim 3, wherein the electrolytic capacitor is discharged through a current limiting resistor.

7. An apparatus according to claim 1, wherein said current detecting means has a current transformer at a detecting end thereof.

8. An apparatus for inspecting an electric component in an inverter circuit composed of a voltage-smoothing electrolytic capacitor, a plurality of transistors, and a plurality of diodes coupled in inverse parallel connection to said transistors, respectively, for protecting the transistors, comprising:

a DC power supply for supplying a direct current to the inverter circuit;

voltage detecting means for detecting a voltage at a predetermined position in the inverter circuit;

current detecting means for detecting a current flowing at a predetermined position in the inverter circuit;

switching means for changing positions at which the direct current is supplied from said DC power supply to the inverter circuit, positions at which the voltage is detected in the inverter circuit by said voltage detecting means, and positions at which the current is detected in the inverter circuit by said current detecting means;

switching control means for outputting a switching signal to said switching means;

electrolytic capacitor determining means for calculating an electrostatic capacitance of the electrolytic capacitor based on a time consumed after the electrolytic capacitor has started being charged by the direct current supplied from said DC power supply through a resistor until a voltage across the electrolytic capacitor as detected by said voltage detecting means reaches a predetermined voltage, and also on a resistance of said resistor, and determining whether the electrostatic capacitance falls within a preset range; and

transistor determining means for determining whether a difference between a collector-to-emitter voltage of each of the transistors as detected by said voltage detecting means when a given collector current is supplied from said DC power supply to the transistor as detected by said current detecting means, and a collector-to-emitter voltage of the transistor as detected by said voltage detecting means when said given collector current is supplied until a junction temperature of the transistor reaches a predetermined temperature, falls within a preset range;

the arrangement being such that the electrolytic capacitor and the transistors will be determined as to whether they are acceptable or not by changing said positions at which the direct current is supplied from said DC power supply to the inverter circuit, said positions at which the voltage is detected in the inverter circuit by said voltage detecting means, and said positions at which the current is detected in the inverter circuit by said current detecting means, based on the switching signal outputted from said switching control means.

9. An apparatus according to claim 8, further comprising diode determining means for determining whether a forward current of each of the diodes as detected by said current detecting means at a voltage across the diode as detected by said voltage detecting means, falls within a preset range.

10. An apparatus according to claim 8, wherein said electrolytic capacitor determining means comprises determining means for calculating an equivalent series resistance of the electrolytic capacitor based on a voltage across the electrolytic capacitor as detected by said voltage detecting means when the electrolytic capacitor which has been charged starts being discharged, a voltage across the electrolytic capacitor as detected by said voltage detecting means while the electrolytic capacitor which has been charged is being discharged, and a discharged current of the electrolytic capacitor as detected by said current detecting means, and determining whether said equivalent series resistance falls within a preset range.

11. An apparatus according to claim 10, wherein the electrolytic capacitor is discharged through at least one of the transistors of the inverter circuit.

12. An apparatus according to claim 10, wherein the electrolytic capacitor has been charged until a voltage across the electrolytic capacitor remains unchanged.

13. An apparatus according to claim 10, wherein the electrolytic capacitor is discharged through a current limiting resistor.

14. An apparatus according to claim 8, wherein said current detecting means has a current transformer at a detecting end thereof.