JPH07128399A - Inspection equipment for inverter circuit - Google Patents

Abstract

PURPOSE:To provide an inspection equipment for inverter circuit in which respective components constituting an inverter circuit can be inspected quickly in assembled state. CONSTITUTION:The inspection equipment 10 for inverter circuit comprises a DC power supply 14 for feeding DC power to an object to be inspected, i.e., an inverter circuit 12, a voltage detector 16 for measuring the voltage of the inverter circuit 12, a current detector 18 for measuring the current of the inverter circuit 12, a switching circuit 24 for switching between the DC supply position of the DC power supply 14 and the measuring position of the voltage detector 16 and the current detector 18, and a controller 26 for delivering a drive signal to the inverter circuit 12, the DC power supply 14 and the switching circuit 24 and reading out voltage from the voltage detector and current from the current detector 18 in order to decide pass/fail of each component constituting the inverter circuit 12.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an inverter circuit inspection device, and more particularly to inspecting the electrical characteristics of each of the components of an inverter circuit that generates high frequency alternating current from direct current in a state where assembly is completed. The present invention relates to an inverter circuit inspection device.

[0002]

2. Description of the Related Art Conventionally, in an apparatus such as a DC resistance welding machine for supplying a large current to a load, an inverter system provided with an inverter circuit for generating a high frequency large current from a DC based on a control pulse output from a controller. Is used.

This type of inverter circuit is composed of a plurality of power transistors, diodes and electrolytic capacitors, and these components are preliminarily inspected by a dedicated measuring instrument as a single component and extracted as non-defective products by this inspection. The above-mentioned inverter circuit was manufactured by combining the above components.

[0004]

However, in the above-mentioned conventional method of manufacturing an inverter circuit, each component is individually inspected, so that a lot of time is required for the inspection and the cost of the inverter circuit increases. There was a problem.

The present invention has been made in order to solve such a conventional problem, and it is possible to quickly inspect the electrical characteristics of each component constituting the inverter circuit in a state where the assembly is completed. It is an object of the present invention to provide a possible inverter circuit inspection device.

[0006]

In order to achieve the above object, the present invention provides an inverter circuit for inspecting the quality of each component of an inverter circuit composed of a plurality of transistors, electrolytic capacitors and diodes. In the inspection device, a direct current power source for supplying direct current to the inverter circuit, a voltage detection unit for detecting a voltage at a predetermined detection position in the inverter circuit, and a predetermined detection position in the inverter circuit are provided. Current detection means for detecting a flowing current, switching means for switching the DC supply position of the DC power supply and the detection positions of the voltage detection means and the current detection means, and switching control means for outputting a switching signal to the switching means. And an electrolytic capacitor that constitutes the inverter circuit based on the curve of the charging voltage of the electrolytic capacitor detected by the voltage detecting means. Calculates the combined capacitance of the capacitors,
Electrolytic capacitor determination means for determining whether or not the combined capacitance is within a preset combined capacitance range, collector-emitter voltage V _{CE of the} transistor detected by the voltage detection means, and the current detection V generated from the collector current I _{C of the} transistor detected by the means
Comprising a determining transistor determining means for determining whether _the extent _CE -I _C curve is set in advance, and the DC power supply DC supply position and the voltage detection based on the switching signal outputted from the switch controller Means and the detection position of the current detecting means are switched to judge whether the electrolytic capacitor is good or bad and the transistor is good or bad.

[0007]

In the inspection device for the inverter circuit according to the present invention,
The switching means is driven to switch the DC supply position of the DC power supply and the detection position of the voltage detection means, and the combined capacitance of the electrolytic capacitors forming the inverter circuit is calculated from the voltage across the electrolytic capacitor detected by the voltage detection means. The quality of the electrolytic capacitor is calculated by the electrolytic capacitor determination means based on the result of the calculation and the comparison of the combined electrostatic capacitance with the reference synthetic electrostatic capacitance.

Next, the switching means is driven to switch the DC supply position of the DC power supply and the detection positions of the voltage detecting means and the current detecting means, and the collector-emitter voltage of the transistor detected by the voltage detecting means. generates a V _CE -I _C curve and a collector current I _C of the transistor, which is detected by said current detecting means with V _CE, compared with V _CE -I _C curve made with the V _CE -I _C curve and reference Based on the result, the quality of the transistor is judged by the transistor judgment means.

Therefore, it becomes possible to inspect the electrical characteristics of the respective parts constituting the inverter circuit in the state of the completed unit without inspecting the individual parts.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, an inspection apparatus for an inverter circuit according to the present invention will be described in detail below with reference to the accompanying drawings with reference to preferred embodiments.

FIG. 1 is a block diagram showing the overall configuration of an inverter circuit inspection device 10 embodying the present invention.

The inverter circuit inspection device 10 includes a DC power supply 14 for supplying a direct current to the inverter circuit 12 as an inspection object, and a voltage detector 16 for measuring the voltage at a predetermined detection position of the inverter circuit 12. A current detector 1 for detecting a current at a predetermined detection position of the inverter circuit 12.
8 and a switching circuit 24 in which a plurality of switches for switching the DC supply position of the DC power supply 14 and the measurement positions of the voltage detector 16 and the current detector 18 are arranged in a matrix.

Further, the inverter circuit inspection device 10 is
Inverter circuit 12, DC power supply 14, and switching circuit 24
And outputs a drive signal to the voltage detector 16
The controller 26 is provided with a controller 26 that reads the voltage output from the inverter and the current output from the current detector 18 and determines whether each component of the inverter circuit 12 is good or bad. The controller 26 includes a display device 28 as a display unit. Connected.

FIG. 2 is a block diagram showing the configuration of the controller 26.

The controller 26 is a central processing unit (hereinafter,
A CPU 32 and a read / write free memory (hereinafter referred to as a RAM) in which the CPU 32 temporarily stores calculation results and the like.
34), a read-only memory (hereinafter referred to as ROM) 36 in which a program for the controller 26 to control the inverter circuit inspection device 10 is stored, and an interface (hereinafter referred to as I / F) circuit 38 with the inverter circuit 12. An I / F circuit 40 with the DC power supply 14 and an I / F circuit 42 with the switching circuit 24 are provided.

Further, the controller 26 is a voltage detector 1
An analog / digital (hereinafter referred to as A / D) conversion circuit 44 that converts the voltage output from 6 into a digital value, and an A / D conversion circuit 46 that converts the current output from the current detector 18 into a digital value. , A capacitance determination circuit 48 for determining the quality of the electrolytic capacitor based on the combined capacitance of a plurality of electrolytic capacitors arranged in the inverter circuit 12.
And an equivalent series resistance judgment circuit 50 for judging the quality of the electrolytic capacitor based on the equivalent series resistance R _ESR of the capacitor arranged in the inverter circuit 12, and the inverter circuit 12
Characteristics of the collector current I _C for the collector-emitter voltage V _CE of arranged transistors (hereinafter, V _CE -I
_A transistor determination circuit 52 for determining pass / fail of a transistor based on a _C curve), a diode determination circuit 54 for determining pass / fail of a diode arranged in the inverter circuit 12, and charging when the electrolytic capacitor is charged. And a charging time measuring circuit 56 for measuring time.

FIG. 3 shows an inverter circuit 12 which is an inspected product.
The electric circuit diagram of is shown.

The inverter circuit 12 is an electrolytic capacitor 6
0, 61, 62 and transistors 63, 64, 65, 6
6, 67, 68 and diodes 69, 70, 71, 72, 73, 74 as snubber circuits arranged between the collectors and emitters of the transistors 63 to 68.

In the inverter circuit inspecting apparatus 10 configured as described above, a method for sequentially determining pass / fail of the electrolytic capacitors 60 to 62, the transistors 63 to 68 and the diodes 69 to 74 which form the inverter circuit 12 will be described below. .

First, a method of judging the quality of the electrolytic capacitors 60 to 62 will be described with reference to the flowchart of FIG.

A switching signal is output from the CPU 32 to the switching circuit 24 via the I / F circuit 42, and each switch of the switching circuit 24 arranged in a matrix is switched based on the switching signal (step S1). ), The plus (+) terminal of the DC power supply 14 is connected to the terminal P of the inverter circuit 12 via the resistor R ₁ , and the voltage detector 16 is connected to both ends of the electrolytic capacitors 60 to 62 (see FIG. 5).

Next, from the CPU 32 to the transistor 63
The non-driving signal is output to -68, and the collectors and emitters of the transistors 63 to 68 are made non-conductive. In this state, the CPU 32 drives the DC power source 1
When a charging current is applied from the DC power supply 14 to the electrolytic capacitors 60 to 62 of the inverter circuit 12 via the resistor 75 and the switching circuit 24 based on the energization start signal output to the inverter 4 (step S2). The charging voltage E _CT due to this charging current is detected by the voltage detector 16 and output to the A / D conversion circuit 44 constituting the controller 26. The charging voltage E _CT is converted into a digital value by the A / D conversion circuit 44 and output to the capacitance determination circuit 48 (step S3).

On the other hand, in step S2, the CPU
The charging time measurement start signal is output from the CPU 32 to the charging time measurement circuit 56 in synchronization with the energization start signal output from the DC power supply 32 to the DC power supply 14.

The capacitance determination circuit 48 supplies the sampled charging voltage E _CT to the supply voltage E supplied from the DC power supply 14.
_It is determined whether the value has reached 0.63 times ₁ (step S
4) If reached, 0.6 of supply voltage E ₁ from the start of energization
The charging time measuring circuit 56 measures the elapsed time τ until reaching three times
Is read (step S5), and the combined electrostatic capacitance C _T of the electrolytic capacitors 60 to 62 is obtained based on the formula C _T = τ / R ₁ (step S6).

The electrostatic capacitance determination circuit 48 determines whether the combined electrostatic capacitance C _T is within a preset setting range (step S7), and the determination result is output to the CPU 32. If the determination result is within the set range, the CPU 32 sends a signal for displaying non-defective products to the display device 28.
To the display device 2 (step S8), and when it is not within the set range, a signal for displaying defective products is displayed.
It outputs to 8 (step S9).

In this case, the charging voltage E _CT due to the electric charges charged in the electrolytic capacitors 60 to 62 is represented by the general formula E _CT = E ₁ (1-e ^{− (t / CR)} ) (1). Here, when C × R = t = τ is substituted, E _CT ≈0.63E ₁ , and when the charging voltage E _CT becomes approximately 0.63 times the supply voltage E ₁ , the above formula C _T = τ /
The combined electrostatic capacitance C _{T of the} electrolytic capacitors 60 to 62 is obtained by R ₁ .

Next, V of each transistor 63-68
By measuring the _CE -I _C curve, it will be described with reference to the flowchart of FIG. 6 method for determining the acceptability of the respective transistors 63 to 68.

A switching signal is output from the CPU 32 to the switching circuit 24 via the I / F circuit 42, and each switch of the switching circuit 24 is switched based on this switching signal (step S21), and the DC power supply 14 is switched. The plus (+) terminal is connected to the terminal P of the inverter circuit 12 via the resistor 75, the voltage detector 16 is connected between the collector and the emitter of the transistor 63, and the current detector 18 outputs the collector current I _C of the transistor 63. Connected to detect.

Next, based on the energization start signal output from the CPU 32 to the DC power source 14, the DC power source 14
From the controller 26, the electrolytic capacitors 60 to 62 of the inverter circuit 12 are charged by the charging current supplied via the resistor 75 from the controller 26 (step S22). By the drive signal output to the base terminals of and, the collectors and emitters of the transistors 63 and 66 become conductive (step S23), and the electric charges charged in the electrolytic capacitors 60 to 62 are discharged through the transistors 63 and 66. To be done.

At this time, the voltage detected by the voltage detector 16 is
Collector-emitter voltage V of the transistor 63_CEIs A /
Transistor converted to digital value by D conversion circuit 44
Output to the decision circuit 52, while the current detector 18
Collector current I detected in _CIs the A / D conversion circuit 46
Converted to a digital value and paired with the transistor determination circuit 52
And is output (step S24).

In this measurement, the collector-emitter voltage V _CE and the collector current I _C of the transistor 63 change based on the discharge of the electrolytic capacitors 60 to 62, and during this change, the collector-emitter voltage V _CE is changed every predetermined period. _CE
And the collector current I _C is measured.

The transistor determination circuit 52 generates a V _CE -I _C curve from the measured collector-emitter voltage V _CE and collector current I _C (step S25).
_CE -I _C curve to determine whether a range of a predetermined setting value width previously stored in the transistor determining circuit 52 (step S26), and outputs the determination result to the CPU 32.

When the judgment result is within the set range, C
The PU 32 outputs a signal for displaying a non-defective product to the display device 28 (step S27), and outputs a signal for displaying a defective product to the display device 28 when it is out of the set range (step S28). ).

[0034] This step S21~S28 are repeated until the determination of V _CE -I _C curves of all the transistors 63 to 68 is terminated (step S29).

Next, a method of judging the quality of each of the diodes 69 to 74 as a snubber circuit arranged between the collector and the emitter of each of the transistors 63 to 68 will be described with reference to the flowchart of FIG.

A switching signal is output from the CPU 32 to the switching circuit 24 via the I / F circuit 42, and each switch of the switching circuit 24 is switched based on this switching signal (step S41). The switch is changed over, the electrolytic capacitor 79 is connected between both terminals of the DC power supply 14, the voltage detector 16 is connected between the collector and the emitter of the transistor 63, and the current detector 18 is the forward current I of the diode 69. Connected to detect _f .

In the inverter circuit inspection apparatus 10 connected in this way, the transistors 63 to 63
A non-driving signal is output to 68, and the collectors and emitters of the transistors 63 to 68 are made non-conductive. In this state, the CPU 32 directs the DC power supply 14
An energization start signal is output to, and the electrolytic capacitor 79 is charged by the charging current supplied from the DC power supply 14 by the energization start signal (step S42).

Next, by the switch signal output from the CPU 32, the switch 76 is opened and the switch 78 is closed, so that the electric charge charged in the electrolytic capacitor 79 is discharged through the diode 69 (step S43).

The voltage E _f across the diode 69 during this discharge is detected by the voltage detector 16 and the A / D
It is output to the diode determination circuit 54 via the conversion circuit 44. On the other hand, the forward current I _f during the discharge is
Is detected by the current detector 18, and the A / D conversion circuit 4
It is output to the diode determination circuit 54 via 6 (step S44).

The diode determination circuit 54 determines whether or not the forward current I _f at the detected voltage E _f is within a preset range stored in the diode determination circuit 54 (step S45), and the determination result is determined by the CPU 32. Is output to. When the determination result is within the set range, the CPU 32 outputs a signal for indicating that the diode 69 is a non-defective product to the display device 28 (step S46). A signal indicating that the product is defective is output to the display device 28 (step S47).

The steps S41 to S47 are repeatedly executed until the determination of all the diodes 69 to 74 is completed (step S48).

Next, the method of calculating the combined equivalent series resistance R _ESR of the electrolytic capacitors 60 to 62 constituting the inverter circuit 12 and determining the quality of the electrolytic capacitors 60 to 62 from the calculation result is shown in the flowchart of FIG. It will be described with reference to FIG.

In this case, each electrolytic capacitor 60-6
2 is known to be represented by the equivalent circuit of FIG.
In the figure, R _E represents the equivalent series resistance of each electrolytic capacitor 60-62.

A switching signal is output from the CPU 32 to the switching circuit 24 via the I / F circuit 42, and each switch of the switching circuit 24 is switched based on this switching signal (step S61), and the DC power supply 14 is switched. The plus (+) terminal is connected to the terminal P of the inverter circuit 12 via the resistor 75, and the voltage detector 16 is connected to both ends of the electrolytic capacitors 60 to 62, that is, between the terminal P and the terminal N of the inverter circuit 12, The current detector 18 is a transistor 63
Connected to detect the collector current I _C of the
2).

Then, based on the charging start signal output from the CPU 32 to the DC power supply 14 via the I / F circuit 40, the electrolytic capacitors 60 to 60 are supplied by the charging current supplied from the DC power supply 14 via the resistor 75. 62 is charged (step S62).

Then, the switch 80 is opened by the switching signal output from the CPU 32, and the CPU 3
A transistor, for example, the transistors 63 and 66, is driven by a signal output from the I / F circuit 38 from 2 and the respective charges charged in the electrolytic capacitors 60 to 62 are discharged via the transistors 63 and 66. (Step S63).

Electrolytic capacitor 60-during this discharge
The voltage E _Q across both ends of 62 is detected by the voltage detector 16 and output to the equivalent series resistance determination circuit 50 via the A / D conversion circuit 44. On the other hand, the collector current I _C during the discharge is detected by the current detector 18,
It is output to the equivalent series resistance determination circuit 50 via the / D conversion circuit 46 (step S64).

From the voltage E _Q and the collector current I _C , the synthetic equivalent series resistance R _{ESR of the} electrolytic capacitors 60 to 62 is calculated by the equivalent series resistance judging circuit 50 (step S
65), and further, the calculated equivalent equivalent series resistance R
_It is determined whether the _ESR is within the set range stored in the equivalent series resistance determination circuit 50 in advance (step S66), and the determination result is output to the CPU 32.

When the judgment result is within the set range, C
The PU 32 outputs a signal for indicating that the electrolytic capacitors 60 to 62 are nondefective to the display device 28 (step S67), and when the value is out of the set range, the electrolytic capacitors 60 to 62 are defective. A signal for displaying is output to the display device 28 (step S68).

As described above, according to this embodiment,
A switching circuit 24 having a plurality of switches arranged in a matrix is provided, and each switch of the switching circuit 24 is switched by a switching signal output from the controller 26 to form a desired electric circuit, thereby forming a unit. Electrolytic capacitor 60 in the inverter circuit 12
62, transistors 63 to 68 and diodes 69 to
The quality of 74 can be sequentially judged.

Further, the electrolytic capacitors 60 to 62 or the electrolytic capacitor 79 charged by the DC power supply 14
Is used as a DC power source, the maximum output current of the DC power source 14 can be suppressed, and the DC power source 14 can be downsized.

[0052]

With the inverter circuit inspection apparatus according to the present invention, it is possible to inspect each component of the inverter circuit in the assembled state as an inverter circuit without inspecting each component individually. The effect that the time required can be reduced can be obtained.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of an inverter circuit inspection device embodying the present invention.

FIG. 2 is a block configuration diagram of a controller in the inverter circuit inspection device shown in FIG.

3 is an electric circuit diagram of an inverter circuit inspected by the inverter circuit inspection device shown in FIG.

FIG. 4 shows an inverter circuit inspection device shown in FIG.
It is a flow chart which shows operation which measures electrostatic capacity and judges quality of an electrolytic capacitor.

5 is a block diagram showing the configuration of an inverter circuit inspection device used when determining the quality of an electrolytic capacitor in the flowchart shown in FIG. 4. FIG.

FIG. 6 shows an inverter circuit inspection device shown in FIG.
8 is a flowchart showing an operation of determining pass / fail of a transistor.

FIG. 7 is a block diagram showing the configuration of an inverter circuit inspection device used when determining the quality of a transistor in the flowchart shown in FIG.

8 is a diagram showing the inverter circuit inspection device shown in FIG.
It is a flow chart which shows the operation which judges the quality of a diode.

9 is a block diagram showing the configuration of an inverter circuit inspection device used when determining the quality of a diode in the flowchart shown in FIG. 8. FIG.

10 is a flowchart showing an operation of measuring the combined equivalent series resistance and determining the quality of the electrolytic capacitor in the inverter circuit inspection device shown in FIG.

11 is a diagram illustrating an electrically equivalent circuit of each electrolytic capacitor arranged in the inverter circuit shown in FIG.

12 is a block diagram showing the configuration of an inverter circuit inspection device used when determining the quality of an electrolytic capacitor in the flowchart shown in FIG.

[Explanation of symbols]

10 ... Inverter circuit inspection device 12 ... Inverter circuit 14 ... DC power supply 16 ... Voltage detector 18 ... Current detector 24 ... Switching circuit 26 ... Controller 28 ... Display device 32 ... CPU 38, 40, 4
2 ... I / F circuit 44, 46 ... A / D conversion circuit 48 ... Capacitance determination circuit 50 ... Equivalent series resistance determination circuit 52 ... Transistor determination circuit 54 ... Diode determination circuit 56 ... Charging time measurement circuit 60-62, 79 ... Electrolytic capacitor 63-68 ... Transistor 69-74 ... Diode

Claims (3)

[Claims] 1. An inverter circuit inspection device for inspecting the quality of each component of an inverter circuit composed of a plurality of transistors, an electrolytic capacitor and a diode, the direct current power supply supplying direct current to the inverter circuit. A voltage detection unit that detects a voltage at a predetermined detection position in the inverter circuit; a current detection unit that detects a current flowing through a predetermined detection position in the inverter circuit; and a DC supply position of the DC power supply And a switching unit that switches detection positions of the voltage detection unit and the current detection unit, a switching control unit that outputs a switching signal to the switching unit, and a curve of the charging voltage of the electrolytic capacitor detected by the voltage detection unit. The composite capacitance of the electrolytic capacitor that constitutes the inverter circuit is calculated based on Electrolytic capacitor determining means for determining whether the order set total capacitance range, the detected in the current detecting means and a collector-emitter voltage V _CE of the transistor detected by said voltage detecting means and a transistor judging means for judging whether or not within the range generated V _CE -I _C curve is set in advance and a collector current I _C of the transistor, based on the switching signal outputted from the switch controller An inspection apparatus for an inverter circuit, characterized in that the DC supply position of the DC power supply and the detection positions of the voltage detection unit and the current detection unit are switched to judge the quality of the electrolytic capacitor and the quality of the transistor. 2. The apparatus according to claim 1, wherein the electrolytic capacitor determining means is generated by the voltage across the electrolytic capacitor detected by the voltage detecting means and the discharge current of the electrolytic capacitor detected by the current detecting means. Determination of whether or not the combined equivalent series resistance value of the electrolytic capacitor forming the inverter circuit is calculated based on the voltage-current curve and whether the equivalent series resistance value is within a preset equivalent series resistance value range An inspection apparatus for an inverter circuit, characterized by comprising: 3. The device according to claim 1, wherein the forward current value of the diode detected by the current detecting means in the voltage value across the diode detected by the voltage detecting means is within a preset value. An inverter circuit inspecting device, comprising: a diode determining means for determining whether or not the inverter circuit is inspected.