JPH11341821A - Inverter device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To accurately detect the welding of a contactor by transmitting a contactor welding signal, when the difference between the voltage value of an inverter before a contactor which controls the power of a battery is turned on, and the off-voltage value of the inverter when the contactor is turned off, is smaller than the welding voltage of the contactor. SOLUTION: When the power supply key of an electric vehicle is turned on/off, abnormality occurs in the vehicle, and so on, a controller 6 detects it and turns on/off the current supply to an inverter 5 by issuing an order to a contactor 2. The welding of the contactor 2 is detected by measuring the voltage values of a battery and the inverter 5 for monitoring the normal/ abnormal operation of the contactor 2. The voltage value of the inverter 5 at the moment the contactor 2 is turned off is detected and stored in an off- inverted voltage value storing means. Then the contactor 2 is again turned on and the on-inverter battery voltage difference which is the difference between the voltage value of the inverter 5 immediately before the contactor 2 is turned on, and the voltage value of a battery is found. When the on-inverter battery voltage difference is smaller than the welding voltage of the contactor 2, the contactor 2 is welded.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an inverter device for detecting welding of a contactor for controlling power supply from a power supply unit.

[0002]

2. Description of the Related Art An inverter device for controlling a motor serving as a power source of an electric vehicle includes a battery 1 as shown in FIG.
A contactor 2 for controlling the current from the contactor 2, an inverter 5 to which a voltage is supplied via the contactor 2, and a motor 7 driven by the voltage of the inverter 5.
Note that a capacitor 3 for smoothing the inverter current and a resistor 4 for discharging the electric charge charged in the capacitor 3 are connected in parallel with the capacitor 3 between the contactor 2 and the inverter 5. With this configuration, turn on the power key.
When the power is turned off or when an abnormality occurs inside the electric vehicle, the control device 6 senses it, issues a contactor 2 command, and turns on / off the current supply to the inverter 5.

[0003] As a method of detecting the welding of the contactor 2 of the inverter device configured as described above, immediately before the contactor 2 is turned on, a voltage difference between the battery voltage and the inverter voltage is obtained, and this voltage difference is smaller than the contactor welding voltage. In such a case, a method of detecting that the contactor 2 has been welded has been adopted.

[0004]

However, in the above-described conventional configuration, the electric charge charged in the capacitor is discharged in a time constant time determined by the capacitance of the capacitor and the resistance value in the circuit. If the detection timing from when the contactor is turned on is short, the battery-inverter voltage difference may be smaller than the welding voltage even though the contactor is normal. Further, the battery voltage value is not stable before the contactor is inserted and at the moment when the contactor is inserted. If the difference welding voltage between the battery voltage value and the inverter voltage value is compared, erroneous detection may occur.

An object of the present invention is to solve the above-mentioned conventional problems, and an object of the present invention is to provide a protection device capable of detecting welding accurately.

[0006]

According to the present invention, there is provided a contactor for controlling power from a battery, an inverter connected via the contactor, a capacitor for smoothing a current input to the inverter, and a voltage value of the inverter. And an off-inverter storage means for storing an off-inverter voltage value at the moment when the contactor is turned off, and a difference between the inverter voltage value before turning on the contactor and the off-inverter voltage value. If the contactor welding voltage is lower than the contactor welding voltage, the contactor monitoring means for transmitting a contactor welding signal is provided.The contactor welding detection can be performed by monitoring the off-inverter voltage value and the on-inverter voltage value. In addition, erroneous detection due to instability of the battery voltage can be prevented.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention relates to a contactor for controlling electric power from a battery, an inverter connected via the contactor, a capacitor for smoothing a current input to the inverter, and detecting a voltage value of the inverter. Inverter voltage detecting means, off-inverter storage means for storing an off-inverter voltage value at the moment when the contactor is turned off, and a difference between the inverter voltage value before the contactor is turned on and the off-inverter voltage value. An inverter device having a contactor monitoring means for transmitting a contactor welding signal if the welding voltage is lower than the welding voltage, wherein an inverter voltage value for detecting the welding of the contactor is turned off and an inverter voltage value which is an inverter voltage value before the contactor is turned on. It can be performed by monitoring the voltage value.

Further, a battery voltage detecting means for detecting a battery voltage value is provided. When the contactor is turned on, the difference between the battery voltage value and the inverter voltage value is lower than the contactor welding voltage. If the difference from the value is lower than the contactor welding voltage, a contactor welding signal is transmitted.

Further, if the contactor is turned on within a specified time after the contactor is turned off, the contactor welding signal is not transmitted, so that when the inverter voltage value is not reduced by the capacitor, the contactor welding detection is not performed. .

When the off-inverter voltage value is not stored in the off-inverter storage means, no welding signal is transmitted.

A contactor for controlling power from a battery, an inverter connected via the contactor, a capacitor for smoothing a current input to the inverter, and an inverter voltage detecting means for detecting a voltage value of the inverter. A battery voltage detecting means for detecting a battery voltage value, and a contactor monitoring means for transmitting a contactor welding signal when a difference between the inverter-voltage value and the battery voltage value is larger than a contactor welding voltage, wherein the contactor is turned off. Thereafter, when the contactor is turned on within a specified time, the inverter device may not transmit the contactor welding signal.

Further, a resistor for discharging the electric charge charged in the capacitor may be provided. Further, the electric vehicle may be provided with the inverter device.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS As shown in FIG. 1, the present invention includes a contactor 2 for controlling a current from a battery 1 as shown in FIG. An inverter 5 to which a current is supplied via the inverter 2 and a motor 7 driven by the current of the inverter 5 are provided. A capacitor 3 for smoothing the inverter current is provided between the contactor 2 and the inverter 5.
Are connected in parallel with the inverter, and a resistor 4 for discharging the electric charge charged in the capacitor 3 is connected in parallel with the capacitor 3. With such a configuration, when the power key is turned on / off, or when an abnormality occurs inside the electric vehicle, the control device 6 senses and issues a command to the contactor 2 to supply current to the inverter 5. Turn on / off.

The inverter device having such a configuration measures a battery voltage value and an inverter voltage value in order to monitor whether or not the contactor 2 is operating normally.
Detects contactor welding.

FIG. 2 shows a change in the inverter voltage value due to ON / OFF of the contactor. When the contactor 2 is turned on (1) with the capacitor 3 discharged from the contactor 2, the inverter voltage increases and is maintained at a certain inverter voltage value. When the contactor 2 is turned off (2), the inverter voltage gradually decreases. As described above, the reason for the gradual decrease is that the voltage accumulated in the capacitor 3 is discharged, so that a time constant time is generated. During the end of this time constant time (time for discharging the voltage stored in the capacitor 3), the contactor 2
Is turned on (3), the inverter voltage increases again,
It is kept at a certain voltage value.

The method of detecting welding is as follows. The inverter voltage value at the moment when the contactor 2 is turned off (off (2)) is detected and stored in the off-inverter voltage value storage means. When the contactor is turned on again (3), the difference between the on-inverter voltage value and the battery voltage value immediately before turning on the contactor (3), and the on-inverter-battery voltage difference are obtained. If the inverter-battery voltage difference is greater than the contactor welding voltage, it is determined that the contactor is not welded. However, if the inverter-battery voltage difference is smaller than the contactor welding voltage, the on-inverter-off-inverter voltage difference is obtained from the off-inverter voltage value and the on-inverter voltage value stored in the inverter voltage value storage means. If the voltage difference is smaller than the contactor welding voltage indicating that the contactor has turned off, it indicates that the contactor has welded and generates a welding signal. If it is larger, it is determined that the contactor is not welded. Thus, the OFF inverter voltage value and the ON
The reason for comparing with the inverter voltage value is that the battery voltage value may be different when the contactor is not turned on and when the contactor is turned on.The inverter voltage value at the moment when the contactor is turned off, It is more reliable to detect the welding of the contactor from the difference from the inverter voltage value.

In the above description, the off-inverter voltage value at the moment of turning off is stored. Since the inverter voltage value and the battery voltage value are the same when the power is supplied for a certain period of time, the battery voltage value at the moment of turning off is stored. An off battery voltage value may be used. Also, after comparing the difference between the battery voltage value and the inverter voltage value, without comparing the difference between the off-inverter voltage value and the on-inverter voltage value and the difference between the contactor welding voltage value, the off-inverter voltage value can be obtained. Alternatively, only the contactor welding voltage may be compared with the difference between the value and the ON inverter voltage value.

As shown in FIG. 3, when the switch is continuously turned on and off between the time when the contactor is turned off (4) and the time when the contactor is turned on (5), the on / off time is very short ( (Less than 0.1 second), no welding detection is performed.
The reason is that if the time when the power is turned on and off is very small, the inverter voltage value gradually decreases due to the time constant time in the circuit. This is because the voltage value has not dropped. Even if the comparison is made, no welding signal is generated. This is because the inverter voltage value does not drop sufficiently due to the capacitors in the circuit, etc., so that both the ON-inverter-battery voltage difference and the ON-inverter-OFF inverter voltage difference have small voltage differences. Actually, it is assumed that the contactor is not welded, so that the contactor is welded and erroneously detected. That is, the welding signal is not generated for a very short time to prevent erroneous detection and does not burden the circuit.

FIG. 4 is a flowchart showing the control method of the electric vehicle described above.

First, it is checked whether a very short time (0.1 second or less) has elapsed since the contactor was turned off. This is because if a certain period of time has not elapsed after the contactor has been turned off, the electric charge of the capacitor is not discharged, the inverter voltage value becomes close to the battery voltage value, and it is difficult to detect welding of the contactor. Therefore, if the minute time has not elapsed, welding detection is not performed, and if the minute time has elapsed, the process proceeds to the next step.

Here, the ON inverter-battery voltage is calculated and compared with the contactor welding voltage value. If the on-inverter-battery voltage is greater than the contactor welding voltage value, there is no welding and the process proceeds to the first step.
If the on-inverter-battery voltage is smaller than the contactor welding voltage value, it is checked whether the off-inverter-battery voltage value stored in the inverter-battery voltage value storage means is not zero. If it is 0, it proceeds to the first step, and if it is not 0, it proceeds to the next step.

Here, based on the off-inverter voltage value and the battery voltage value stored in the inverter voltage value storage means,
The off-inverter-battery voltage value is obtained. And
The voltage difference between the OFF inverter-battery voltage value and the ON inverter-battery voltage value is determined. If the voltage difference is larger than the contactor drop welding voltage value, the process returns to the first step. On the other hand, if this voltage difference is smaller than the contactor drop welding voltage value, it is determined that the contactor is welding and a welding signal is generated.

As described above, the voltage difference between the off-inverter-battery voltage value and the on-inverter-battery voltage value is determined and compared with the contactor drop welding voltage value. Contactor welding can be detected without malfunction.

[0024]

According to the first, fourth and sixth aspects of the present invention, the ON / OFF state is changed instead of the battery voltage value when the contactor is turned ON.
Since the inverter voltage value is used, even if the battery voltage is unstable, the contactor welding can be accurately detected.

Furthermore, the contactor voltage is compared with the voltage difference between the battery voltage value and the inverter voltage value, so that the contactor welding can be reliably detected.

Further, according to the third and fifth aspects of the present invention, when the contactor switch is continuously turned on and off, detection of contactor welding is not performed, so that erroneous detection can be prevented.

Further, the invention according to the seventh aspect is applied to an electric vehicle requiring a large current, so that the safety of the electric vehicle is enhanced.

[Brief description of the drawings]

FIG. 1 is a diagram showing an inverter device of the present application.

FIG. 2 is a diagram showing a relationship between an inverter voltage and time according to the embodiment of the present application;

FIG. 3 is a diagram showing a relationship between the inverter voltage and time.

FIG. 4 is a flowchart of contactor welding detection.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Battery 2 Contactor 3 Capacitor 4 Resistance 5 Inverter

Claims (7)

[Claims] 1. A contactor for controlling power from a battery, an inverter connected via the contactor,
A capacitor for smoothing a current input to the inverter, an inverter voltage detecting means for detecting a voltage value of the inverter, an off-inverter storing means for storing an off-inverter voltage value at the moment when the contactor is turned off, and a contactor. An inverter device comprising: contactor monitoring means for transmitting a contactor welding signal if a difference between an inverter voltage value before being turned on and the off-inverter voltage value is smaller than a contactor welding voltage. 2. A battery voltage detecting means for detecting a battery voltage value, wherein before the contactor is turned on, a difference between the battery voltage value and the inverter voltage value is lower than a contactor welding voltage. The inverter device according to claim 1, wherein a contactor welding signal is transmitted when the difference from the value is lower than a contactor welding voltage. 3. The inverter device according to claim 1, wherein the contactor welding signal is not transmitted when the contactor is turned on within a specified time after the contactor is turned off. 4. The inverter device according to claim 1, wherein a welding signal is not transmitted when the off-inverter voltage value is not stored in the off-inverter storage means. 5. A contactor for controlling electric power from a battery, an inverter connected via the contactor,
A capacitor for smoothing the current input to the inverter, an inverter voltage detecting means for detecting a voltage value of the inverter, a battery voltage detecting means for detecting a voltage value of the battery, and a difference between the inverter voltage value and the battery voltage value. A contactor monitoring means for transmitting a contactor welding signal if the contactor welding voltage is lower than the contactor welding voltage, and not transmitting a contactor welding signal when the contactor is turned on within a specified time after the contactor is turned off. 6. The inverter device according to claim 1, further comprising a resistor for discharging the electric charge charged in the capacitor. 7. An electric vehicle comprising the inverter device according to claim 1.