JPH0322821A - Fault diagnosis unit for power source electrolytic capacitor - Google Patents

Abstract

PURPOSE:To facilitate diagnosis by making judgement that a capacitor has degraded if the terminal voltage of the capacitor, measured upon elapse of time constant to be determined by an electrolytic capacitor and a resistor connected between a power source and a load after throw-in of power source, is higher than a predetermined value. CONSTITUTION:A current limiting resistor RO1 and an electrolytic capacitor CD1 are connected between a power source 7 and a load 1. A current limiting resistor RO2 and an electrolytic capacitor CO2 are connected between the power source 7 and a load 40. Upon elapse of a time constant, to be determined by the resistor RO1, the capacitor CD1, the resistor RO2, and the capacitor CD2, after throw-in of power source, voltages of the capacitors CD1, CD2 are detected 35, 35' and compared through comparators CP1, CP2 with a reference voltage. If they are higher than the reference voltage, diagnosis means 36, 36' make judgement that the capacitances of the capacitors CD1, CD2 are lowered. By such arrangement, degradation of capacitor can be judged in early stage and a load 1, e.g. a power transistor, can be protected against break down.

Description

[Detailed Description of the Invention] (Industrial Application Field) The present invention relates to a failure diagnosis device for electrolytic capacitors for power supply.
In particular, it relates to diagnosing deterioration failures.

(Prior Art) Conventionally, in an inverter that converts alternating current into alternating current of another frequency, a limited A current resistance and an electrolytic capacitor as a smoothing capacitor are arranged.

(Issue 8 to be Solved by the Invention) However, when the electrolytic capacitor deteriorates over its lifespan, the electrolyte disappears and its capacity decreases, often leading to an open circuit failure. In this case, overvoltage is applied to the power transistor module or diode module due to regenerative energy of the motor driven by the inverter, external surge, or switching surge of the power transistor, causing damage or abnormal current flowing and tripping the module. It turns out.

Although the case of the electrolytic capacitor disposed between the power supply and the power transistor section has been described above, the same applies to other electrolytic capacitors for power supply such as the electrolytic capacitor disposed before the switching regulator.

The present invention has been made in view of the above points, and its purpose is to detect deterioration failures of electrolytic capacitors in order to prevent secondary failures such as destruction of power transistor modules.

(Means for Solving the Problems) In order to achieve the above object, in the present invention, when a current limiting resistor is placed between a power source and a predetermined device together with the electrolytic capacitor as described above, when the power is turned on, the current limiting resistor is Focusing on the characteristic that the voltage increases with a time constant determined by both, using this characteristic, the terminal voltage of the electrolytic capacitor is compared with the characteristic of increasing terminal voltage according to this time constant, and deterioration failure of the electrolytic capacitor can be detected. I'm trying to diagnose.

In other words, the specific configuration of the invention according to claim (1) is, as shown in the drawing, a power source (7) and a predetermined device (1.40) to which voltage is applied from the power source (7). The present invention is directed to a failure diagnosis device for power supply electrolytic capacitors that diagnoses deterioration failures of electrolytic capacitors (Cos.CD2) disposed between them. And the electrolytic capacitor (Co1.c
terminal voltage detection means (3) for detecting the terminal voltage of o2);
5.35゜〉, the above power supply (7) and the prescribed equipment (1.4
0) and the current limiting resistor (Ro I.RO 2
) and the output of the terminal voltage detection means (35, 35'), the terminal voltage of the electrolytic capacitor (Co + .CD 2 ) after the set time has elapsed from the power-on is determined by the terminal voltage of the current limiting resistor (RO1, Ro2). and electrolytic capacitors (Co
＋． A diagnostic means (3B.38°) that diagnoses a deterioration failure of the electrolytic capacitor (Cos.CCl 2 ) when the voltage exceeds the set terminal voltage value to be charged after the elapse of the set time with a time constant determined by cD z ). The configuration is such that it is provided.

Further, in the invention according to claim (2), the electrolytic capacitor (Cos
．． A time measuring means (38) is provided for measuring the elapsed time from when the terminal voltage of the CD 2) reaches the set voltage value from power-on to the set voltage value, and a diagnostic means (38) according to the invention of claim (1) above is provided.
8.38'), the above time measuring means (38')
) is the elapsed time measured by the current limiting resistor (Ro + .).
Ro2> and electrolytic capacitor (Co + .cD z
), the electrolytic capacitor (Co +
．． The configuration is such that a diagnostic means (39) is provided for diagnosing a failure due to deterioration of cD2>.

(Function) With the above configuration, in the invention described in claim (1), when the electrolytic capacitor (Co + .CD 2 ) deteriorates,
The voltage applied from the power supply (7) to the predetermined device (1.40), that is, the terminal voltage of the electrolytic capacitor (Co + .CD 2 ), rises rapidly, and the electrolytic capacitor (Co I, CD 2 Since the terminal voltage of 2) greatly exceeds the terminal voltage value determined by the time constant, this state is detected by the diagnostic means (3B.36°) and is detected when the electrolytic capacitor (Co + .CD 2 ) deteriorates and fails. is diagnosed.

Further, in the invention described in claim ('2J), when the electrolytic capacitor (Cos, CD 2 ) deteriorates, the degree of increase in the applied voltage is steeper than the time constant. 2) The time it takes for the terminal voltage to rise to the set voltage value is short and less than the set elapsed time.Therefore, this state is detected by the diagnostic means (39).
is detected in the power supply electrolytic capacitor (CD1, CC)
2) is diagnosed as a deterioration failure.

(Effects of the Invention) As explained above, according to the present invention, a current limiting resistor and an electrolytic capacitor are arranged between a power source and a predetermined device to which the voltage is applied, and a time constant determined by both of them is set. The system detects deterioration failures of electrolytic capacitors by comparing the degree of increase in the terminal voltage applied to the electrolytic capacitors when the power is turned on, using the rising characteristics of the applied voltage as a reference, so deterioration failures of electrolytic capacitors can be detected early. It is possible to detect and prevent secondary failures such as destruction of power transistors, etc.
It is possible to improve serviceability.

(Example) Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 shows an embodiment in which the present invention is applied to a diagnostic device for diagnosing deterioration failures in a power supply electrolytic capacitor used in an inverter that controls the rotation of a compressor of a separate air conditioner. In the figure, (4) is an indoor controller that controls the indoor unit, (5) is an outdoor controller that controls the outdoor unit, and (6) is an inverter controller.

The indoor controller (4) is connected to a power source (4l), a remote control device (hereinafter referred to as a remote control device) (42) via a signal line (4a), and an outdoor controller (5). Signal 1m! (4b
) are connected through.

On the other hand, the compressor motor (CM) is powered by a three-phase AC power source (7).
are connected via a motor drive circuit (7l), which includes a power switch (52e), a converter section (72) that converts three-phase AC into DC,
A filter circuit (having a DC reactor (73a) and a smoothing capacitor (Co
73) and a power transistor section (1) of an inverter that converts direct current into alternating current of an arbitrary frequency are connected in order, and are configured to supply control power to the compressor motor (CM). A shunt resistor (73C) is interposed on the motor (CM) side of the filter circuit (73), while a power switch (52C) is bypassed to limit the R and T phases of the three-phase FFII (7). A current circuit (75) is connected to the current limiting circuit (75), and a current limiting resistor (Ro+) and b
A contact opening/closing switch (84) is provided.

Further, a controller (6) consisting of a microcomputer for the inverter is connected to the power transistor section (1) of the inverter via a signal line (6a),
The inverter controller (6) includes a microcomputer (hereinafter referred to as microcomputer) and a drive circuit (39) that drives the power transistor section (1).
). The microcomputer (6") connects the R and S phases of the power supply (7) to a control power supply circuit (47) consisting of a transformer (45) and two three-terminal regulators (4B).
48).

On the other hand, the drive circuit <39> obtains a DC voltage for controlling the power transistor section (L) of the inverter from the driver power supply (40) consisting of a switching regulator. ) is a current limiting resistor (RO2) on the input side.
and a smoothing capacitor (Co 2 ) are arranged.

The above inverter controller (6>) connects the power transistor section (1) of the inverter to its drive circuit (39).
The rotation speed of the compressor is controlled by controlling the compressor through the compressor, thereby controlling the capacity of the compressor.

Further, the inverter controller (6>) is connected to the outdoor controller (5) via a signal line (5a), and the outdoor controller (5> is connected to the indoor controller (4).
) and the inverter controller (6), and the inverter controller (6) detects a shortage of DC voltage supplied from the converter section (72) to the inverter (1). An undervoltage detection circuit (30) is provided. Deterioration failure of the smoothing capacitor (electrolytic capacitor) (Co 1) is diagnosed using the undervoltage detection circuit (30). That is, in the undervoltage detection circuit (30), the terminal voltage of the smoothing capacitor (Co + ) is applied to the ten terminals of the comparator (CP + ), and the resistors (1?5), (1?6) are connected to one terminal of the terminal. Input the reference voltage V1 corresponding to the voltage shortage determined by . As shown in FIG. 2, when the DC voltage applied to the power transistor section (1) decreases and becomes insufficient and becomes below the reference voltage V1, or when a momentary power outage occurs, the converter (ep + ) An output as shown in the figure is generated, and this output operates the photocoupler (PIIC+), and the output of this photocoupler (PMCI) as shown in Figure 4 is sent to the microcontroller (
6゛) is used manually to detect instantaneous power outages and undervoltage.

? As shown in FIG. 5, the reference voltage V1 is such that when the power is turned on, the terminal voltage of the smoothing capacitor (Co + ) is determined by the time constant τ determined by the current limiting resistor (Ro + ) and the smoothing capacitor (Cot), and the solid line in the diagram It is a value that exceeds the set terminal voltage value v■ that should be charged when the set time t1 has elapsed from power-on, and when the smoothing capacitor (Co + ) deteriorates and fails as shown by the broken line in the figure. The voltage is less than the voltage value v2 taken at the elapse of the set time t1.

Then, the microcomputer (6°) measures the elapsed time after the power is turned on, and when time t1 elapses, the output (
If the undervoltage detection signal> is not received, it has a function of determining that the smoothing capacitor (Co + ) has deteriorated and failed.

Similarly, (3B') is an undervoltage detection means for detecting a shortage of voltage supplied to the driver power supply (switching regulator) (40>), and is connected to the undervoltage detection circuit (30) for the inverter (1). Similarly, the converter (CP
2) and a photocoupler (PHC2), and has a function of determining deterioration failure of the smoothing capacitor (CD2).

Therefore, each smoothing capacitor (Co + ). (Co2
) are connected to the respective converters (CP1). <O
By connecting to the + terminal of P 2 ), it constitutes a terminal voltage detection means (35) (35°) for detecting the terminal voltage of each smoothing capacitor (Col), (Coz). Each undervoltage detection circuit (30). (
30゜> and a microcomputer (8゛>) receive the output of each terminal voltage detection means (35).
1). When the terminal voltage of each smoothing capacitor (Co 2 ) exceeds the set terminal voltage value Vo to be charged at the elapse of the set time t1 with the time constant τ, each smoothing capacitor (Co + ). (Co
2) Diagnostic means (3B) for diagnosing deterioration failure,
(3B).

In Fig. 1, (RYI) is the open/close switch (84).
Relay contact for N/OFF control, (1?Y2) is a relay contact for ON/OFF control of the power switch (52C), (55) is a microcomputer provided inside the outdoor controller (5), (56 ) is a protective device.

Next, the operation of the above embodiment will be explained by taking as an example a deterioration failure of the smoothing capacitor (CD1) of the filter circuit (73). First, when the power is turned on, the relay 84) is controlled to be ON, thereby applying the voltage waveform shown in FIG. 5 to the converter section (72>).Then, the power transistor is As shown in the figure, the voltage waveform applied to section (1), that is, the terminal voltage of the smoothing capacitor (Co + ), is determined by the current limiting resistor (Ro +
) and the time constant τ determined by the smoothing capacitor (Co + )
Therefore, it gradually rises and remains below the set voltage V1 when the set time t1 has elapsed. Therefore, the undervoltage detection circuit (3
0> converter (CP1) is generating output,
Along with this, the photocoupler (PHC+) also operates, and its output is input to the microcomputer (B゛) as an undervoltage detection signal.Therefore, the microcomputer (6゛) detects the deterioration of the smoothing capacitor (Co +). It is considered normal when there is no.

After that, as shown in the figure, a smoothing capacitor (Co 1
) is completed, the relay (84) is turned off and the relay (52c) is turned on to start the operation of the power transistor section <1> of the inverter.

On the other hand, when the smoothing capacitor (CD1) deteriorates and fails, its terminal voltage rises rapidly with a slope greater than the time constant τ, as shown by the broken line in the figure, and exceeds the set voltage v1 when the set time t1 has elapsed. For this reason, the undervoltage detection circuit (
The converter (CP1) of 30) no longer generates an output, and the microcomputer (6') does not receive the undervoltage detection signal. Therefore, the microcomputer (B゜) has a smoothing capacitor (C
o + ) is judged to have deteriorated and failed, the operation of the power transistor section (1) is stopped, and the smoothing capacitor (C
DI) failure is displayed on the remote control device (42>).

Therefore, since deterioration failures of the smoothing capacitor (Co + ) can be automatically detected, secondary failures such as destruction of the power transistor section (1) due to overvoltage can be prevented, and serviceability can be improved.

Also, Figure 6 shows the diagnostic equipment! A modification of (3B) is shown.

The same diagnostic flow is for diagnosing a deterioration failure of the smoothing capacitor (Co + ) (the diagnostic flow for the smoothing capacitor (Co 2) is the same, so it will be omitted), and the power is turned on? Start at step S1 and turn on the relay (84) at $11.
Apply voltage to the 1L converter section <72>. and,
In step S2, a timer measures the elapsed time after the power is turned on, and in step S3, the terminal voltage VDC of the smoothing capacitor (C0+) is compared with the reference value v1. If VDC≠v1, the process returns to step S2 to measure the time. Continue with VDC-
V! If so, the elapsed time T1 up to that point is compared with the set elapsed time To in step S4. Here, the set elapsed time T
o is the smoothing capacitor (Co 1) and the current limiting resistor (Ro
This is the elapsed time until the voltage is charged to the set voltage value v1 with a time constant τ determined by t).

And in the case of T, ;a'ro, the smoothing capacitor (
It is determined that Co 1) is normal, and normal operation is started in step S5. On the other hand, if T,<"r■, it is determined in step S6 that the smoothing capacitor (Co
o + ) deterioration failure is displayed on the remote control device (42).

Therefore, in steps S2 and S3 of the above diagnostic flow, the output of the terminal voltage detection means (35) is received, and the elapsed time T1 from when the terminal voltage VOC of the smoothing capacitor (Co + ) reaches the set voltage value v1 from power-on is calculated. It constitutes a time measuring means (38) for measuring.

Further, in steps 84 and S6, the elapsed time T1 measured by the time measuring means (38) is changed to the current limiting resistance (Ro+
> and the time constant τ determined by the smoothing capacitor (Co + )
The set elapsed time To until charging to the set voltage value v1 is
A diagnostic device (39) is configured to diagnose a deterioration failure of the smoothing capacitor (Cot) when the value is less than 0.

Therefore, in this embodiment as well, similar to the above embodiment, deterioration failures of the smoothing capacitors (Co I) and (Co z ) are automatically diagnosed, so that the power transistor section (1
) and driver power supply (switching regulator) (4
0) can be prevented from secondary failures such as destruction due to overvoltage, and serviceability can be improved.

[Brief explanation of the drawing]

The drawings show an embodiment of the present invention, and FIG. 1 is an overall configuration diagram, and FIGS. 2 to 4 are voltage waveform diagrams of main parts of the deterioration detection circuit.
FIG. 5 is an explanatory diagram of the operation of the invention according to claim (1), and FIG. 6 is a flow chart diagram showing deterioration diagnosis of a smoothing capacitor showing another embodiment. (1)--Power transistor section, (Ro 1). (
Ro 2)...Current limiting resistance, (Co 1), (Co 2)
)...Smoothing capacitor (electrolytic capacitor for power supply)
, (CP + ). (CP 2 )... Combination controller, (6°)... Microcomputer, (30)... Undervoltage detection circuit, (35). (35')...terminal voltage detection means, (3e). (ae')...Diagnostic means, (38)
...Elapsed time measuring means, (39)...Diagnosis means, (4
0)...Driver power supply (switching regulator). Two other people (1)... Power transistor section (RO + ), (Ro : )... Current limiting resistor (Co
+ ) - (Co!)... Smoothing capacitor (electrolytic capacitor for power supply) (CP + ). (CP ! >... Comparator (
B゜〉...-Microcomputer<30)...Undervoltage detection circuit (35), (35')...Terminal voltage detection means (3)i
). (36°)...Diagnostic means<38)...Elapsed time measuring means<39)...Diagnostic means (40)...Driver power supply (switching regulator) 4th

Claims (4)

[Claims] (1) For power supply for diagnosing deterioration failure of electrolytic capacitors (C_D_1, C_D_2) placed between power supply (7) and predetermined equipment (1, 40) to which voltage is applied from power supply (7) A failure diagnosis device for electrolytic capacitors (C_D_1, C_D_2), the electrolytic capacitors (C_D_
1, C_D_2) terminal voltage detection means (35, 35') for detecting the terminal voltage of
1, 40) and the current limiting resistor (R_O_1, R
_O_2) and the above terminal voltage detection means (35, 35')
In response to the output of When the set terminal voltage value to be charged is exceeded over time, the electrolytic capacitors (C_D_1, C_D
Diagnostic means (36, 36') for diagnosing deterioration failure of _2)
A failure diagnosis device for a power supply electrolytic capacitor, characterized by comprising: (2) For power supply for diagnosing deterioration failure of electrolytic capacitors (C_D_1, C_D_2) placed between power supply (7) and predetermined equipment (1, 40) to which voltage is applied from power supply (7) A failure diagnosis device for electrolytic capacitors, which includes terminal voltage detection means (35, 35') for detecting terminal voltages of the electrolytic capacitors (C_D_1, C_D_2), the power source (7), and predetermined equipment (1, 40). The terminal voltage of the electrolytic capacitor (C_D_1, C_D_2) reaches the set voltage value from the power-on by receiving the output of the forward flow resistance (R_O_1, R_O_2) placed between the The elapsed time measured by the time measuring means (38) is a time constant determined by the current limiting resistors (R_O_1, R_O_2) and the electrolytic capacitors (C_D_1, C_D_2). When the elapsed time is less than the set elapsed time until the voltage is charged to the above set voltage value, the electrolytic capacitors (C_D_1, C_D_
2) A failure diagnosis device for a power supply electrolytic capacitor, comprising a diagnostic means (39) for diagnosing a deterioration failure as described in 2). (3) The failure diagnosis device for a power supply electrolytic capacitor according to claim (1) or (2), wherein the predetermined device (1, 40) is a power transistor section (1) of an inverter. (4) The failure diagnosis device for a power supply electrolytic capacitor according to claim (1) or (2), wherein the predetermined device (1, 40) is a switching regulator (40).