JP3477345B2 - Fault diagnosis device for power circuit using contactor - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a power circuit failure diagnosis device using a contactor, and is effectively applied to detect a short circuit failure of a diode used in a power circuit of a battery vehicle, for example.

[0002]

2. Description of the Related Art A battery forklift truck is a forklift truck of the type in which a battery is mounted as a power source, and a motor driven by the battery is used as a drive source for traveling.

A conventional power circuit for a battery forklift truck will now be described with reference to FIG. As shown in the same figure, the armature AM and the field coil FC constitute a direct current winding type motor. The armature AM is connected to the positive side of the battery B via the forward / reverse switching contactor C3, the regenerative contactor C2, and the line contactor C1. The battery forklift truck travels as the armature AM rotates. The field coil FC has one end side (armature side terminal) connected to the armature AM via the forward / reverse switching contactor C3, and the other end side (battery side terminal) is a main switching element (power transistor). It is connected to the negative polarity side of the battery B via SW1.

After all, the direct current winding type motor composed of the armature AM and the field coil FC is the regenerative contactor C2.
Then, power is supplied from the battery B via the line contactor C1.

The plugging diode PD has its anode side connected to one end side (armature side terminal) of the field coil FC, and its cathode side connected to the positive side of the battery B via the line contactor C1. . Therefore, the plugging diode PD is connected to the regenerative contactor C2.
And the armature AM are connected in antiparallel.

The anode side of the flywheel diode FD is the other end side of the field coil FC (battery side terminal).
The cathode side of the battery B is connected to the positive side of the battery B via the line contactor C1.
Therefore, the flywheel diode FD is connected in antiparallel to the circuit composed of the regenerative contactor C2, the armature AM, and the field coil FC.

The anode side of the regenerative diode RD is the output side (emitter side) of the main switching element SW1.
, And its cathode side is connected to the armature AM via the forward / reverse switching contactor C3.

The regenerative excitation switching element (power transistor) SW2 has its input side (collector side) connected to the positive side of the battery B via the regenerative excitation resistance r1 and the line contactor C1 and its output side (emitter). Side) is connected to one end side (armature side) of the field coil FC.

One end of the field weakening resistor r2 is connected to one end side (armature side terminal) of the field coil FC via a field weakening contactor C4, and the other end side is the other end of the field coil FC. Side (battery side terminal).

The contactors C1 to C4 and the switching elements SW1 and SW2 are turned on and off by a controller (not shown).

Next, the operation of the power circuit of the battery forklift having the above structure will be described for each operation mode.

[Normal traveling mode] In the normal traveling mode,
As shown in FIG. 4, the line contactor C1 and the regenerative contactor C2 are charged. The order of charging the contactors is that the line contactor C1 is charged and then the regenerative contactor C2 is charged. Then, during forward traveling, the forward / reverse switching contactor C3 is closed to the fixed contact F side, which is a contact for forward traveling, and during reverse traveling, the forward / rearward switching contactor C3 is closed to the fixed contact R side, which is a contact for backward traveling. . In this state, the main switching element SW
1 is turned on (ON) and opened (OFF) by PWM control
To be done.

In this normal running mode, the field weakening contactor C4 is kept in the OFF state, and the regenerative excitation switching element SW1 is also kept in the OFF state.

When the main switching element SW1 is turned on in the normal traveling mode, a current flows along the path K1 as shown in FIG. That is, battery B → line contactor C1 → regenerative contactor C2 → one of forward / reverse switching contactor 3 (contactor on the left side in the figure) → armature A
M → the other side of the forward / reverse switching contactor 3 (the contactor on the right side in the figure) → the field coil FC → the main switching element S
A current flows along the path of W1 → Battery B. Therefore, when the forward / reverse switching contactor C3 is closed to the fixed contact F side, the armature AM rotates normally and the forklift travels forward, and the forward / backward switching contactor C3 is closed to the fixed contact R side. The armature AM reverses and the forklift travels backward.

When the main switching element SW1 is turned off in the normal traveling mode, the current induced by the armature AM flows (returns) along the path K2 as shown in FIG. That is, a current flows along the path of the armature AM → the other side of the forward / reverse switching contactor C3 → the field coil FC → the flywheel diode FD → the regenerative contactor C2 → the one of the forward / backward switching contactor C3 → the armature AM.

In the normal traveling mode, when the main switching element SW1 is turned on, the current flowing along the path K1 increases and the current flowing through the field coil FC also increases. On the other hand, when the main switching element SW1 is turned off, the current flowing (refluxing) along the path K2 decreases, and the current flowing in the field coil FC also decreases. Therefore, when the traveling speed is increased, the PWM control is performed so that the current flowing through the field coil FC is reduced and the OFF period of the main switching element SW1 is lengthened.
When the traveling speed is reduced, the main switching element SW is set so as to increase the current flowing through the field coil FC.
PWM control is performed so that the ON period of 1 is lengthened.

[Field weakening traveling mode] As described above,
When the traveling speed is increased, the main switching element SW is set so as to reduce the current flowing through the field coil FC.
Although the PWM control is performed so as to lengthen the OFF period of 1, the field weakening control is performed when the PWM control alone cannot deal with the problem. That is, as shown by the dotted line in FIG. 4, the field weakening contactor C4 is turned on so that the current flowing in the field coil FC is shunted to the field weakening resistor r2 side as well. It reduces the flowing current. By thus reducing the current flowing through the field coil FC, the traveling speed of the forklift can be increased.

[Regenerative Braking Mode] Next, a regenerative braking mode for electrically braking will be described. In the regenerative braking mode, the regenerative contactor C2 that was turned on in the traveling mode (normal traveling mode or field weakening traveling mode) is turned off.
FF.

As shown in FIG. 5, when the regenerative contactor C2 is turned off, the main switching element SW1 is turned on.
Set to 0% ON state (continue ON state without PWM control) and turn on regenerative excitation switching element SW2
To do. Then, as shown in FIG. 5, a current flows along the route K3. That is, battery B → line contactor C
1 → Regenerative excitation resistance r1 → Regenerative excitation switching element SW
2 → field coil FC → main switching element SW1 →
A current flows along the path of the battery B. Therefore, even if the regenerative contactor C2 is turned off, a current flows through the field coil FC, the field is established, and the self-power generation function of the armature AM is exhibited.

When the self-power generation function of the armature AM is surely exerted as described above, the regenerative excitation switching element SW2 is turned off this time. After the power generation function is reliably exhibited in this way, the regenerative excitation switching element SW2
Even when is turned off (the regenerative contactor C2 is also turned off), the current self-generated by the armature AM flows through the field coil F. In this state, the main switching element SW1 is PWM-controlled so that the current flowing through the field coil FC has a preset current value.

While the armature AM is exhibiting the self-power generation function, the main switching element SW1 is turned on.
Then, a current flows along the route K4 shown in FIG. That is, the armature AM → the other side of the forward / reverse switching contactor C3 → the field coil FC → the main switching element SW1 → the regenerative diode RD → the one side of the forward / reverse switching contactor C3 → the armature AM along the path of the armature AM Current flows.

While the armature AM is exhibiting the self-power generation function, the main switching element SW1 is turned off.
When F, a current flows along the route K5 shown in FIG. That is, armature AM → the other side of forward / reverse switching contactor C3 → field coil FC → flywheel diode FD → line contactor C1 → battery B → regeneration diode RD → one side of forward / backward switching contactor C3 → along the path of armature AM An electric current flows. Therefore, the electric power induced by the armature AM is regenerated in the battery B.

In the regenerative braking mode, when the main switching element SW1 is turned on, the current flowing along the path K4 increases, the current flowing through the field coil FC also increases, and the braking force increases. On the other hand, when the main switching element SW1 is turned off, the current flowing along the path K5 decreases and the current flowing in the field coil FC also decreases, and the braking force decreases. Therefore, the main switching element SW1 is PWM-controlled to make the current flowing through the field coil FC a preset constant value to keep the braking force constant.

In the regenerative braking mode described above, the braking force is reduced in the speed range where the traveling speed of the forklift is reduced and the rotation speed of the armature AM is reduced, so that the traveling speed of the forklift is less than a certain speed. Then, the operation shifts to the plugging braking mode described below.

[Plugging Braking Mode] In the plugging braking mode, the closing position of the forward / reverse switching contactor C3 is changed. That is, as shown in FIG. 6, when the forward / reverse switching contactor C3 is closed on the stator contact F side, the forward / reverse switching contactor C3 is closed on the stator contact R side. When the forward / reverse switching contactor C3 is closed on the stator contact R side, the forward / reverse switching contactor C3
Re-apply to the stator contact F side. Then, the regenerative contactor C2, which has been turned off due to the regenerative braking, is turned on.

In this plugging braking mode, when the main switching element SW1 is turned on, a current flows along the route K6 as shown in FIG. That is, battery B → line contactor C1 → regeneration contactor C2 → the other side of forward / reverse switching contactor C3 → armature AM → one of forward / backward switching contactor C3 → field coil FC → main switching element SW1 → current along the path of battery B Flows. Therefore, a current flows in the armature AM in the opposite direction to the previous one, and a sudden braking force is generated.

When the main switching element SW1 is turned off in the plugging braking mode, the current induced by the armature AM flows (returns) along the path K7 as shown in FIG. That is, armature AM → one of forward / reverse switching contactor C3 → plugging diode PD → regenerative contactor C2 → other side of forward / reverse switching contactor C3 →
An electric current flows along the path of the armature AM.

Here, the control operation for shifting the battery forklift from the stop mode to the traveling mode will be briefly summarized as follows. (1) First operation sequence: The line contactor C1 is turned on. (2) Second operation sequence: The regenerative contactor C2 is turned on. (3) Third operation sequence: ON / OFF operation of the main switching element SW1 is performed. (4) Fourth operation sequence: When the main switching element SW1 is turned on, a current flows along the path K1, and when the main switching element SW1 is turned off, a current flows along the path K2.

By the way, the flywheel diode FD
When a short circuit fault occurs in the battery, when a control operation for shifting the battery forklift from the stop mode to the traveling mode is to be executed, the third operation sequence, that is, the main switching element SW1 is turned on and off. However, since the flywheel diode FD is short-circuited, no current flows on the armature AM side. As a result,
The armature AM does not rotate and the battery forklift does not travel.

In the case of the above situation, the operator who is doing the cargo handling work on the site judges that some abnormality has occurred, although the cause is unknown, and returns the operation key to the stop side for the time being, and then the control device. The line contactor C1 and the regenerative contactor C2 are turned off by the control. However, the on-site work is not immediately stopped, and then the operation key is put in the operation side again to try to perform the control operations (1) to (4). In other words, if the driving key is put in the driving side again, the driving key is put in the driving side again in the expectation that the failure will be resolved naturally and the driving operation will be performed normally (depending on the type of failure, By doing such an operation, it may return to normal).

However, if the flywheel diode FD is short-circuited, even if the operation key is turned on again, no current flows to the armature AM side, the armature AM does not rotate, and the battery Do not drive the forklift. However, the operator hopes that the failure will be resolved naturally,
Return the operation key to the stop side and open the line contactor C1.
F is performed and the driving key is put in the driving side again, but like the previous time, the armature AM does not rotate and the battery forklift does not travel. Even if the operation key is once returned to the stop side and then the operation key is again inserted into the drive side, even if the operation is not repeated, the operator suffers a serious failure. Recognize that, and give up on driving.

As described above, when the flywheel diode FD has a short circuit fault, the contactor C
When the main switching element SW1 is turned on in the state where 1 and C2 are turned on, a large current flows into the main switching element SW1. In addition, since the operation key is once returned to the stop side and then the operation key is again inserted into the drive side many times, a large current flows through the main switching element SW1 many times. The main switching element SW1 may be damaged due to this.

When the flywheel diode FD has a short-circuit fault, the battery forklift does not run after the contactors C1 and C2 are turned on. Therefore, when the contactor C1 is turned off, the large current is cut off. Therefore, a large surge voltage is generated due to interruption, and this surge voltage causes contactor C1
Or, other elements may be damaged.

After all, when the flywheel diode FD has a short circuit failure, the operation key is once returned to the stop side and then the operation key is again inserted into the operation side, which is repeated many times. Then, not only the flywheel diode FD but also the main switching element SW1 and the contactor C1 may be propagated and expanded.

In this situation, the plugging diode PD
If a short-circuit failure occurs, the same problem will occur.

[0036]

When the flywheel diode FD or the plugging diode PD has a short circuit failure, the line contactor C1 is turned on in order to prevent the failure from spreading to other elements. However, the regenerative contactor C2 is not turned on yet and is turned off.
In the state (the first operation sequence is completed, but the second operation sequence is not yet executed), the failure of the diodes FD and PD is diagnosed,
If it is determined as a result of the diagnosis that there is a short-circuit failure, it suffices to be able to prohibit the regenerative contactor C2 from being turned on (not to proceed to the second operation sequence). By detecting the voltage based on such knowledge, the diode F
An attempt was made to diagnose a failure of D or PD, but in reality, there was a problem as described later, and it could not be adopted.

Here, a technique for diagnosing the failure of the diodes FD and PD by detecting the voltage will be described. In this technique, the diode F is detected by detecting the potential at the detection point P shown in FIGS.
I tried to diagnose the failure of D and PD. That is, when the temperatures of the diodes FD and PD are low and the diode leakage current is small, the potential at the detection point P is as follows.
In addition, H means a high level potential (for example, about 20 V or more), and L means a low level potential (approximately 0 V).

(I) The line contactor C1 is turned on, but the regenerative contactor C2 is turned off. When the diodes FD and PD are normal, the potential at the detection point P becomes L. (Ii) When the line contactor C1 is turned on, but the regenerative contactor C2 is turned off, and at least one of the diodes FD and PD is short-circuited, the potential at the detection point P becomes H. .

Therefore, by observing the potential of the detection point P, it seems that at least one of the diodes FD and PD is short-circuited.
That is, if the potential of the detection point P is L, there is no short circuit failure in the diodes FD and PD, and if the potential of the detection point P is H, it can be detected that at least one of the diodes FD and PD is short-circuited. Seem.

However, when the temperatures of the diodes FD and PD rise and the diode leakage current increases, (iii) in the state where the line contactor C1 is turned on but the regenerative contactor C2 is turned off,
Even if the diodes FD and PD are normal (not short-circuited), the potential of the detection point P becomes H instead of L because the diode leakage current is large.

After all, in the above-mentioned technique of diagnosing the failure of the diodes FD and PD by detecting the voltage, the potentials (H, L) of the detection point P are as shown in Table 1 below.

[0042]

[Table 1]

Thus, even if the diodes FD and PD are normal (even if they are not short-circuited), the diodes FD and PD
Depending on the temperature of PD, the potential of the detection point P becomes L (when the temperature is low) or H (when the temperature is high), and the value becomes undefined. As described above, the determination of the detection voltage varies depending on the diode temperature (the value becomes indefinite). Therefore, even if the potential of the detection point P is simply monitored, the diode F cannot be accurately measured.
The failure (short circuit) of D and PD could not be detected. That is, if the potential of the detection point P is L while the line contactor C1 is ON but the regenerative contactor C2 is OFF, there is no short-circuit failure and the potential of the detection point P is H. If so, at least one of the diodes FD and PD is short-circuited. "

In view of the above-mentioned prior art, it is an object of the present invention to provide a failure diagnostic apparatus for a power circuit using a contactor capable of accurately determining a failure of an element based on voltage detection.

[0045]

The structure of the present invention for solving the above-mentioned problems is a power supply, a first contactor whose input side is connected to the positive side of the power supply, a second contactor and a power-supplied member. Is connected in series and the input side is connected to the output side of the first contactor, and the input side is connected to the output side of the power supplied circuit and the output side is the power supply. A switching element connected to the negative side of the power supply circuit, and an electronic member having one end connected to the input side of the fed circuit and the other end connected to the output side of the fed circuit. A first voltage dividing resistor whose one end side is connected to the positive side of the power source through the first contactor and the other end side is connected to the input side of the switching element; A second voltage dividing resistor connected to the input side of the switching element and the other end side of which is connected to the negative side of the power source, and the first contactor is turned on but the second contactor is turned on. When the switching element is in the cut-off state, the divided voltage applied to the second voltage dividing resistor is compared with the preset threshold voltage, and the divided voltage is the threshold voltage. If it becomes above, the diagnostic part which diagnoses that the said electronic member has failed, and the control apparatus which opens a 1st contactor when the said diagnostic part diagnoses that the said electronic member has failed. Moreover, the resistance value of the first voltage dividing resistor, the resistance value of the second voltage dividing resistor, and the threshold voltage value are such that the first contactor is turned on but the second contactor is opened. In addition, in the state where the switching element is in the cutoff state, even if the electronic member is normal and the leakage current is the maximum, the divided voltage has a value smaller than the threshold voltage. It is characterized by being set.

Further, the structure of the present invention comprises a battery, a first contactor whose input side is connected to the positive side of the battery, a second contactor and a motor which are connected in series. A fed circuit whose side is connected to the output side of the first contactor, and a switching element whose input side is connected to the output side of the fed circuit and whose output side is connected to the negative side of the power supply. A power circuit of a battery forklift having a cathode connected to an input side of the fed circuit and an anode connected to an output side of the fed circuit in a power circuit of a battery forklift, one end side of which is through the first contactor. A first voltage dividing resistor connected to the positive polarity side of the power source and the other end side connected to the input side of the switching element; and one end side A second voltage dividing resistor connected to the input side of the switching element and the other end of which is connected to the negative side of the power source, and the first contactor is turned on but the second contactor is turned on. In the state in which the switching element is in the cutoff state, the divided voltage applied to the second voltage dividing resistor is compared with the preset threshold voltage, and the divided voltage is the threshold voltage. When the voltage is equal to or higher than the voltage, a diagnosis unit that diagnoses that the diode has a short circuit failure, and a control device that opens the first contactor when the diagnosis unit diagnoses that the diode has a short circuit failure. Prepare,
Moreover, regarding the resistance value of the first voltage dividing resistor, the resistance value of the second voltage dividing resistor, and the value of the threshold voltage, the first contactor is turned on but the second contactor is opened, and In the state where the switching element is in the cutoff state, even if the diode is normal and the leakage current is the maximum, it is set to a value that makes the divided voltage smaller than the threshold voltage. Is characterized by.

[0047]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described in detail below with reference to the drawings. FIG. 1 shows a power circuit failure diagnosis device using a contactor in a battery forklift according to an embodiment of the present invention. As shown in the same figure, the armature AM and the field coil FC constitute a direct current winding type motor. The armature AM is connected to the positive side of the battery B via the forward / reverse switching contactor C3, the regenerative contactor C2, and the line contactor C1. The battery forklift truck travels as the armature AM rotates. The field coil FC has one end side (armature side terminal) connected to the armature AM via the forward / reverse switching contactor C3, and the other end side (battery side terminal) is a main switching element (power transistor). It is connected to the negative polarity side of the battery B via SW1.

After all, the direct current winding type motor composed of the armature AM and the field coil FC is the regenerative contactor C2.
Then, power is supplied from the battery B via the line contactor C1. That is, the regenerative contactor C2 and the DC motor are connected in series to form a fed circuit, the input side of the line contactor C1 is connected to the positive side of the battery B, and the output side of the line contactor C1 is It is connected to the input side of the fed circuit, the input side of the main switching element SW1 is connected to the output side of the fed circuit, and the output side of the main switching element SW1 is connected to the negative side of the battery B. There is.

The plugging diode PD has its anode side connected to one end side (armature side terminal) of the field coil FC, and its cathode side connected to the positive side of the battery B via the line contactor C1. . Therefore, the plugging diode PD is connected to the regenerative contactor C2.
And the armature AM are connected in antiparallel.

The anode side of the flywheel diode FD is the other end side of the field coil FC (battery side terminal).
The cathode side of the battery B is connected to the positive side of the battery B via the line contactor C1.
Therefore, the flywheel diode FD is connected in antiparallel to the circuit composed of the regenerative contactor C2, the armature AM, and the field coil FC.

The anode side of the regenerative diode RD is the output side (emitter side) of the main switching element SW1.
, And its cathode side is connected to the armature AM via the forward / reverse switching contactor C3.

The regenerative excitation switching element (power transistor) SW2 has its input side (collector side) connected to the positive side of the battery B via the regenerative excitation resistance r1 and the line contactor C1 and its output side (emitter). Side) is connected to one end side (armature side) of the field coil FC.

One end of the field weakening resistor r2 is connected to one end side (armature side terminal) of the field coil FC via a field weakening contactor C4, and the other end side is the other end of the field coil FC. Side (battery side terminal).

The contactor C1 to C4 and the switching elements SW1 and SW2 are turned on and off by the control device 2.
It is performed based on the control of 0. The running / braking operation of the power circuit of the battery forklift is the same as the conventional one, and therefore the description of the running / braking operation is omitted.

Further, in the present embodiment, the first voltage dividing resistor R1, the second voltage dividing resistor R2 and the diagnostic section 10 are connected.

One end of the first voltage dividing resistor R1 is connected to the positive side of the battery B via the line contactor C1 and the other end thereof is connected to the main switching element SW.
It is connected to one input side (collector side) and one end side of the second voltage dividing resistor R2. One end of the second voltage dividing resistor R2 is connected to the other end of the first voltage dividing resistor R1 and the input side (collector side) of the main switching element SW1, and the other end thereof is the negative electrode of the battery B. Connected to the sex side.

Further, the diagnosis section 10 detects the divided voltage V2 applied to the voltage dividing resistor R2. A threshold voltage Vth is set in the diagnosis unit 10, and the divided voltage V2 is compared with the threshold voltage Vth.
When V2 ≧ Vth, it is determined that the divided voltage V2 is at the high level H, and when V2 <Vth, it is determined that the divided voltage V2 is at the low level L. And the diagnosis unit 10
The diagnostic logic shown in Table 2 below is stored, and the divided voltage V2 is stored.
Is determined to be high level H, the diodes FD and PD are both diagnosed to be normal, and when it is determined that the divided voltage V2 is low level L, the diode F is determined to be normal.
It is diagnosed that at least one of D and PD is short-circuited.

[0058]

[Table 2]

Moreover, the resistance value of the voltage dividing resistor R1 and the resistance value of the voltage dividing resistor R2 and the threshold voltage Vth are set so that the line contactor (first contactor) C1 is turned on when the diodes FD and PD are normal. However,
The regenerative contactor (second contactor) C2 is open, and the main switching element SW1 is off.
Is set to a value that always satisfies the following expression (1).

[0060]

[Equation 1]

The detailed reason will be described later using a calculation formula.
Since the line contactor C1 is turned on by setting so as to satisfy the above formula (1), the regenerative contactor C2 is not turned on and is turned off (the first operation sequence is In a state where the second operation sequence has not been executed yet, although the temperature of the diodes FD and PD is high and the leakage current of both the diodes FD and PD is maximum, the diode FD is completed. , If PD is not shorted,
The divided voltage V2 becomes smaller than the threshold voltage Vth. Of course, in a state where the temperatures of the diodes FD and PD are low and there is almost no leakage current of both the diodes FD and PD, the divided voltage V2 becomes smaller than the threshold voltage Vth when the diodes FD and PD are not short-circuited. . On the other hand, if one of the diodes FD and PD is short-circuited, regardless of the temperature of the diodes FD and PD,
The divided voltage V2 becomes higher than the threshold voltage Vth.

Therefore, regardless of whether the temperature of the diodes FD and PD is low or high, the diagnostic logic shown in Table 2, that is, when it is determined that the divided voltage V2 is at the high level H, the diodes are When it is diagnosed that both FD and PD are normal and it is determined that the divided voltage V2 is at the low level L, it can be accurately diagnosed that at least one of the diodes FD and PD is short-circuited.

Then, the diagnostic unit 10 causes the diode F
When it is diagnosed that at least one of D and PD is short-circuited, the line contactor C1 is turned on by the control of the control device 20 even if the operator turns on the driving key 21 on the driving side. The second operation sequence for turning on the regenerative contactor C2 and the third operation sequence for ON / OFF controlling the main switching element SW1 are prevented from proceeding from the above operation sequence.
That is, when it is diagnosed that at least one of the diodes FD and PD is short-circuited, the operator operates the drive key 2
1 is turned on, the regenerative contactor C2 is not turned on, and the main switching element SW1 is turned on.
Not done. Further, the controller 20 controls the diode F
A warning that at least one of D and PD has a short circuit fault is issued, and the line contactor C1 is forcibly turned off.

Because of this, even if at least one of the diodes FD and PD has a short-circuit fault, the main switching element SW1 will not be turned on, and a large current due to the short-circuit fault will generate a large current. The current does not flow to SW1 and the failure of the main switching element SW1 can be prevented. In addition, since a large current due to a short-circuit failure does not flow, the line contactor C1 does not cut off this large current, and the line contactor C1 is not damaged or other elements are damaged. The spread of consequential damage associated with

By satisfying the relation of the above expression (1), Table 2 shows whether the diodes FD and PD have a low temperature or a high temperature (especially high temperature). The reason why the short circuit fault of the diodes FD and PD can be accurately diagnosed by the diagnostic logic will be described with reference to FIG.

FIG. 2 shows that in FIG. 1, the line contactor C1 is turned on, but the regenerative contactor C2 is opened, and the main switching element SW1 is OF.
Battery B, diode F in the F state
An equivalent circuit of a circuit including D, PD and voltage dividing resistors R1, R2 is shown.

In FIG. 2, IC indicates the maximum leakage current which is the maximum value of the combined leakage current of the flywheel diode FD and the plugging diode PD. This maximum leakage current is when both diodes FD and PD are at high temperature. Occurs. Incidentally, the plugging diode PD is not provided,
In a model including only the flywheel diode FD (for example, a battery forklift using a DC shunt motor), the maximum leakage current of the flywheel diode FD becomes the maximum leakage current IC as it is. Also, V
B _max is the maximum voltage of the battery B, I1 is the current flowing through the voltage dividing resistor R1, and I2 is the current flowing through the voltage dividing resistor R2. Further, R1 indicates the resistance value of the voltage dividing resistor R1, and R2 indicates the resistance value of the voltage dividing resistor R2 (that is, for the voltage dividing resistor, the member number (reference numeral) and the resistance value thereof are indicated by the same reference numeral. ing).

In the circuit of FIG. 2, when the voltage of the battery B is the battery maximum voltage VB _max and V2 = Vth in the state where the diodes FD and PD are at high temperature and the maximum leakage current IC is flowing. The condition of is obtained as follows. First, the current I2 is the maximum leakage current I
Since it is the sum of C and the current I1, the following equation (11) is established. I2 = IC + I1 ... (11)

The current I1 is the maximum battery voltage VB
_Since the voltage obtained by subtracting the divided voltage V2 from _max is divided by the resistance R1, the following equation (12) is established. I1 = (VBm _max −V2) / R1 = (VBm _max −Vth) / R1 (12)

Further, the divided voltage V2 is the current I flowing through the resistor R2.
Since it is multiplied by 2, the following expression (13) is established.
The equation (13) is transformed by applying the equations (11) and (12). V2 = I2 × R2 = (IC + I1) × R2 = {IC + (VBm _max −Vth) / R1} × R2 ... (13)

The above equation (13) is the same as the left side of equation (1). Therefore, if the resistance value of the voltage dividing resistor R1 and the resistance value of the voltage dividing resistor R2 and the value of the threshold voltage Vth are set so that the equation (1) is satisfied, the line contactor C1 is turned on. The regenerative contactor C2 is not turned on but turned off (the first operation sequence is completed, but the second
Is not executed), the temperature of the diodes FD and PD is high and both diodes FD and P
Even when the leakage current of D is maximum, the divided voltage V2 becomes smaller than the threshold voltage Vth when the diodes FD and PD are not short-circuited. That is, even in such a case, the diagnosis unit 10 can diagnose that the divided voltage V2 is L.

Of course, in the state where the temperature of the diodes FD and PD is low and there is almost no leakage current of both the diodes FD and PD, the divided voltage V2 is lower than the threshold voltage Vth when the diodes FD and PD are not short-circuited. Is further reduced, and the diagnosis unit 10 diagnoses that the divided voltage V2 is L.

On the other hand, if one of the diodes FD and PD is short-circuited, the divided voltage V2 becomes higher than the threshold voltage Vth regardless of the temperature of the diodes FD and PD. , It is diagnosed that the divided voltage V2 is L.

Thus, regardless of whether the temperature of the diodes FD and PD is high or low, the diagnostic section Vth can accurately diagnose the short-circuit fault of the diodes FD and PD by the diagnostic logic shown in Table 2. Can be done.

When both the diodes FD and PD are disconnected, as shown in Table 3 below, the divided voltage V2
The voltage of is diagnosed as L, the diodes FD and PD are determined to be normal, the regenerative contactor C2 is turned on, and the main switching element SW1 is turned on and off. Even if it becomes a state, since power regeneration or plugging operation is not performed and the element is not destroyed, the present invention does not target such a defect, and such a defect is detected by another method. It is planned to be detected.

[0076]

[Table 3]

[0077]

As described above in detail with the embodiments, in the present invention, the power source, the first contactor whose input side is connected to the positive side of the power source, the second contactor and the contactor. A power-supplied circuit that is formed by connecting in series with a power-supplying member and has an input side connected to the output side of the first contactor; and an input side connected to the output side of the power-supplied circuit and an output side. Power consisting of a switching element connected to the negative side of the power source and an electronic member whose one end side is connected to the input side of the fed circuit and the other end side is connected to the output side of the fed circuit In the circuit, a first voltage dividing resistor whose one end side is connected to the positive polarity side of the power source through the first contactor and the other end side is connected to the input side of the switching element, and one end side A second voltage dividing resistor connected to the input side of the switching element and the other end of which is connected to the negative side of the power source, and the first contactor is turned on but the second contactor is turned on. In the state in which the switching element is in the cutoff state, the divided voltage applied to the second voltage dividing resistor is compared with the preset threshold voltage, and the divided voltage is the threshold voltage. When the voltage is equal to or higher than the voltage, a diagnosis unit that diagnoses that the electronic member has a failure, and a control device that opens the first contactor when the diagnosis unit diagnoses that the electronic member has a failure. Prepared and first
As for the resistance value of the voltage dividing resistor, the resistance value of the second voltage dividing resistor, and the threshold voltage value, the first contactor is turned on, but the second contactor is opened,
Moreover, in the state where the switching element is in the cutoff state, even if the electronic member is normal and the leakage current is the maximum, the divided voltage is set to a value smaller than the threshold voltage. It has a structure.

Further, according to the present invention, the battery, the first contactor whose input side is connected to the positive side of the battery, the second contactor and the motor are connected in series, and the input side is A fed circuit connected to the output side of the first contactor; a switching element having an input side connected to the output side of the fed circuit and an output side connected to the negative side of the power supply;
In a power circuit of a battery forklift truck, the cathode side being connected to the input side of the fed circuit and the anode side being a diode connected to the output side of the fed circuit, one end side of which is connected via the first contactor. A first voltage dividing resistor connected to the positive polarity side of the power source and the other end side connected to the input side of the switching element; and one end side connected to the input side of the switching element and the other end side of the power source. In a state in which the second voltage dividing resistor connected to the negative polarity side and the first contactor are turned on but the second contactor is not turned on and the switching element is in the cutoff state. ,
The divided voltage applied to the second voltage dividing resistor is compared with a preset threshold voltage, and when the divided voltage becomes equal to or higher than the threshold voltage, it is diagnosed that the diode has a short circuit failure. In the case of diagnosing that the diode has a short circuit failure by the diagnosis unit and the diagnosis unit,
And a control device for opening the first contactor, wherein the resistance value of the first voltage dividing resistor and the resistance value of the second voltage dividing resistor and the threshold voltage value are such that the first contactor is turned on. However, in the state where the second contactor is opened and the switching element is in the cut-off state, the divided voltage is kept at the above-mentioned divided voltage even when the diode is normal and the leakage current is maximum. The configuration is set to a value that is smaller than the threshold voltage.

Because of this structure, the second aspect of the present invention is used.
Before the contactor (regenerative contactor) is turned on, even if the electronic component (flywheel diode or plugging diode) becomes hot and the leakage current is maximum, the electronic component (flywheel diode or plugging diode) In the normal case, the divided voltage of the second voltage dividing resistor becomes lower than the threshold voltage. In addition, if the electronic member (flywheel diode or plugging diode) has a failure (short-circuit failure), the second
The divided voltage of the voltage dividing resistor becomes lower than the threshold voltage. Therefore, it is possible to accurately diagnose the failure (short-circuit failure) of the electronic member (flywheel diode or plugging diode).

Further, when the failure diagnosis is performed, the first contactor (line contactor) is opened by the control of the control device, so that the switching element (main switching element) is damaged or the first contactor is damaged. It is possible to prevent the spread of damage and damage.

[Brief description of drawings]

FIG. 1 is a circuit diagram showing a power circuit failure diagnosis device using a contactor in a battery forklift according to an embodiment of the present invention.

FIG. 2 is a circuit diagram showing an equivalent circuit used to determine the value of the voltage dividing resistor and the value of the threshold voltage.

FIG. 3 is a circuit diagram showing a conventional power circuit of a battery forklift.

FIG. 4 is a circuit diagram showing a conventional power circuit of a battery forklift truck in a normal traveling mode and a field weakening traveling mode.

FIG. 5 is a circuit diagram showing a conventional power circuit of a battery forklift truck in a state of a regenerative braking mode.

FIG. 6 is a circuit diagram showing a conventional power circuit of a battery forklift truck in a state of plugging braking mode.

[Explanation of symbols]

AM armature FC field coil B battery C1 line contactor (first contactor) C2 regenerative contactor (second contactor) C3 forward / reverse switching contactor C4 weakening field contactor FD flywheel diode PD plugging diode RD regenerative diode SW1 main switching Element SW2 Regenerative excitation switching element r1 Regenerative excitation resistance r2 Field weakening resistance R1 First voltage dividing resistance R2 Second voltage dividing resistance V2 Voltage dividing voltage Vth Threshold voltage IC maximum leakage current VB _max Battery maximum voltage 10 Diagnostic unit 20 Control Device 21 Run key

─────────────────────────────────────────────────── ─── Continuation of the front page (56) Reference JP-A-5-126888 (JP, A) JP-A-4-210701 (JP, A) JP-A-7-67387 (JP, A) (58) Field (Int.Cl. ⁷ , DB name) B60L 3/04 B60L 15/20 B66F 9/24 G01R 31/00 H02P 7/29

Claims (2)

(57) [Claims] 1. A power source, a first contactor whose input side is connected to the positive side of the power source, a second contactor and a power-supplied member, which are formed in series, and whose input side is the first contactor. A fed circuit connected to the output side of the first contactor; a switching element having an input side connected to the output side of the fed circuit and an output side connected to the negative side of the power supply; In a power circuit comprising an electronic member connected to the input side of the fed circuit and having the other end connected to the output side of the fed circuit, one end side of which is the positive electrode of the power source via the first contactor. A first voltage dividing resistor connected to the input side of the switching element and the other end of which is connected to the input side of the switching element, and the other end of which is connected to the input side of the switching element. The is connected to the negative polarity side of the serial power supply 2
And the second contactor is turned on while the first contactor is turned on but the second contactor is not turned on and the switching element is turned off. Comparing the divided voltage that is present and a preset threshold voltage, and when the divided voltage becomes equal to or higher than the threshold voltage, a diagnosis unit that diagnoses that the electronic member has a failure; A control device for opening the first contactor when it is diagnosed that the member is out of order, and further, the resistance value of the first voltage dividing resistor and the resistance value of the second voltage dividing resistor, and the threshold voltage. Of the electronic member in the state where the first contactor is turned on, the second contactor is opened, and the switching element is in the cutoff state. Even and when the leakage current of the maximum normal, fault diagnosis device of a power circuit using a contactor, characterized in that said divided voltage is set to a value smaller than the threshold voltage. 2. A battery, a first contactor whose input side is connected to the positive side of the battery, a second contactor and a motor are connected in series, and the input side is the first contactor. A fed circuit connected to the output side of the contactor, a switching element having an input side connected to the output side of the fed circuit and an output side connected to the negative side of the power supply, and a cathode side In a power circuit of a battery forklift truck, which comprises a diode connected to an input side of a power supply circuit and having an anode side connected to an output side of the power supplied circuit, one end side of which has a positive polarity of the power source via the first contactor. A first voltage dividing resistor connected to the input side of the switching element and connected to the other side of the switching element; The other end side is connected to the input side of the child which is connected to the negative polarity side of the power supply 2
And the second contactor is turned on while the first contactor is turned on but the second contactor is not turned on and the switching element is turned off. Comparing the divided voltage that is present and a preset threshold voltage, and when the divided voltage is equal to or higher than the threshold voltage, a diagnostic unit that diagnoses that the diode has a short circuit failure; And a control device for opening the first contactor when it is diagnosed that there is a short circuit failure, and the resistance value of the first voltage dividing resistor and the resistance value of the second voltage dividing resistor and the threshold voltage. The value of is such that in the state where the first contactor is turned on, the second contactor is opened, and the switching element is in the cutoff state, Even if the diode is normal and its leakage current is maximum, the fault diagnosis of a power circuit using a contactor is set to a value that makes the divided voltage smaller than the threshold voltage. apparatus.