JPH06245301A - Phase loss detection method for electric vehicle controller - Google Patents

Abstract

(57) [Abstract] [Purpose] In addition to detecting faults such as ground faults on the electric motor side where the main circuit current escapes, faults in the CT itself, and faults from the inverter controller input to the CT output. , The open phase in the inverter device, the open phase in the main circuit on the equipment side and the open phase in the main motor circuit can be detected. In an electric vehicle control device having an induction motor for driving an electric vehicle, an inverter device for controlling the induction motor, and a CT for detecting a phase current, a logic unit is provided and each of the three-phase alternating current output by the inverter device is provided. Average value of phase current I _U ,
I _V and I _W are taken, and the average value of these phase currents is further averaged to obtain a value I ₀ = (I _U + _IV + I _W ) / 3, and the difference between the average value of each phase current and the average value. | I _U −I ₀ |, | I _V
When −I ₀ |, | I _W −I ₀ | exceeds the reference value, it is detected that there is an open phase failure.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electric vehicle controller including an inverter controller for driving an induction motor, and more particularly,
The present invention relates to an open phase detection method for an electric vehicle control device.

[0002]

2. Description of the Related Art Conventionally, the open phase detection of this type of electric vehicle control device is performed in a monthly magazine "Rail Magazine" 1989.
As described in the August issue of the year, when the addition of the phase currents of the U, V, and W phases is no longer zero (normally, it is zero), a method of detecting that there is an imbalance in the phases is used. Had adopted. According to the conventional method, since the total current passing through the CT provided in the main circuit is viewed, a failure such that the main circuit current such as a ground fault on the motor side escapes somewhere,
Although the fault of CT itself and the fault from the input of VVVF inverter control device to the output of CT can be detected, one-phase disconnection in the inverter device, one-phase disconnection on the main circuit on the equipment side and one-phase disconnection on the main motor circuit can be detected. It was impossible to detect.

[0003]

SUMMARY OF THE INVENTION An object of the present invention is to provide a fault such that a main circuit current such as a ground fault on the electric motor side escapes to somewhere.
CT from failure of CT itself and inverter controller input
In addition to detecting the failure up to the output of, the one-phase disconnection in the inverter device, the one-phase disconnection on the main circuit on the equipment side, and the one-phase disconnection on the main motor circuit can be detected.

[0004]

The above object is to provide an induction motor for driving an electric vehicle, an inverter device for controlling the induction motor, and an electric vehicle controller having a CT for detecting a phase current, wherein a logic unit is provided. The average value of each phase current of the multi-phase alternating current output by the inverter device is taken, the average value of these phase currents is further calculated, and the difference between the average value of each phase current and the average value is the reference value. This is achieved by detecting that there is an open phase failure when the value exceeds.

[0005]

The average value of each phase of the output current of the inverter that outputs a three-phase alternating current is taken, and these are set as I _U , I _V , and I _W. These three values are further averaged to obtain I ₀ (I ₀ = (I _U + I _V
+ I _W ) / 3). Difference between average value of each phase current and I ₀ | I _U −
When I ₀ |, | _IV −I ₀ |, | I _W −I ₀ | exceeds the reference value ΔI, the phase is detected.

[0006]

EXAMPLE An example of the present invention will be described below. Figure 1
Shows an overall configuration of an open-phase detection system of the electric vehicle control device of the present invention. 1 is an induction motor for driving an electric vehicle, 2 is a VVVF inverter device for controlling the induction motor 1, 3 is a CT for detecting a phase current, 4 is a logic unit, 5 is an overhead wire, 6 is a pantograph, 7 is a circuit breaker, and 8 is A reactor, 9 is a condenser. Further, FIG. 2 shows the details of the logic section 4, and 4-1 shows the phase currents i _U , i _V , and i _W as absolute values | i _U |, | i _V |, | i _W.
Means for converting to |, means for calculating average values I _U , I _V , I _W of absolute values of the respective phase currents, and reference numeral 4-3 for these three average values I ₀ (= (I _U + I _V + I _W ) / 3) calculating means, 4-4 is the average value of each phase current and these three average values I
₀ of the difference _{| I U -I 0 |, |} I V -I 0 |, | I W -I 0 | means for computing, is 4-5 compares these differences with a reference value [Delta] I (4-5) Comparing means 4-7 represent logical means.

[0007] Normally, the overhead line 5 through the pantograph 6, the circuit breaker 7, the reactor 8 and the capacitor VVVF
A DC voltage is applied to the inverter device 2, and the three-phase AC converted by the VVVF inverter device 2 is supplied to the induction motor 1 to drive and control the electric vehicle. Now, for example, assume that a one-phase disconnection abnormality occurs at the W phase of the main circuit on the equipment side (point A), and no current flows. In this case, all the current flowing from the U phase returns to the V phase, so when normal, U,
The three-phase current flowing in the V and W phases becomes a single-phase current flowing only in U and V. The logic unit 4 takes in these phase currents and detects the difference. This relationship will be described with reference to FIGS. 3 and 4.

FIG. 3 describes the normal state. The phase currents i _U , i _V , and i _W flowing from the VVVF inverter device 2 through the U, V, and W phases are 12 as shown in (a).
The phase is shifted by 0 degrees. These phase currents i _U , i _V , i
_W is detected by the phase current detection CT3 and input to the logic unit 4. In the means 4-1 for converting each phase current into an absolute value, when these absolute values | i _U |, | i _V |, | i _W | are taken, it becomes as shown in (b). In the means 4-2 for calculating the average value of
As shown in (c), I _U , I _V , and I _W. Therefore, in the means 4-3 for calculating these three average values, the average value I ₀ = (I _U + _IV + I _W ) / 3 is calculated, and the average value of each phase current and these three average values I ₀ are calculated. In the means 4-4 for calculating the difference, the respective differences | I _U −I ₀ |, | I _V −I
_{When 0} |, | I _W −I ₀ | is calculated, its absolute value becomes zero. As a result, the comparing means 4-5 judges that the absolute value is smaller than the appropriately selected reference value ΔI (4-6), and the logic means 4-7 outputs the normal signal of the phase current.

FIG. 4 shows current waveforms when the W-phase has a one-phase disconnection abnormality as described above. The phase current is
Since the single-phase currents i _U and i _V that flow only in the U and V phases, U
The phase relationship between the phase and the V phase is 180 degrees as shown in (a). Therefore, as described with reference to FIG. 3, these absolute values | i _U |, | i _V |, | i _W |, and the average values I _U , I
_{When V} and I _W are taken, they become as shown in (b) and (c), respectively, and only the average value of the W phase becomes zero. Taking the difference between the average value of each phase and these three average values I ₀ (= (I _U + _IV + I _W ) / 3), the absolute values | I _U −I ₀ |, | _IV −I ₀ | , | I
_W- I ₀ | does not become zero but takes a certain value. At this time, since the reference value ΔI is selected as an appropriate value, a certain value is the reference value ΔI.
It becomes larger than I, and an abnormal signal of the phase current is output from the logic means 4-7 to detect the open phase of the phase current.

As described above, the one-phase disconnection failure in the W-phase of the main circuit on the equipment side has been described. A one-phase disconnection on the motor circuit can be detected as well. Similarly, when the CT itself fails, for example, when the CT cannot detect the W-phase current, the W-phase detected current becomes zero and the average value thereof also becomes zero. As a result, the absolute value of the difference between the average value of each phase and the average value I ₀ (= (I _U + _IV + I _W ) / 3) | I _U −I ₀ |, | _IV −I ₀ |, | I _W Since −I ₀ | does not become zero but takes a certain value and becomes larger than the reference value ΔI,
Output an abnormal signal. Similarly, it is also possible to detect a failure such as a ground fault on the electric motor side where the main circuit current escapes somewhere and a failure from the input of the inverter control device to the output of the CT. Note that the induction motor 1 ′ may be a parallel circuit as shown by the dotted line in FIG. 1 and a part of the line may be broken, but since the average value of each phase current is used, the phase current lacks. There is no inconvenience in detecting the phase. Further, the present invention can be applied to a three-level inverter,
It goes without saying that it can be applied to an inverter device that outputs a multi-phase alternating current.

[0011]

As described above, according to the present invention, there is a conventional fault such as a ground fault on the electric motor side where the main circuit current escapes to somewhere, a fault in the CT itself, and from the inverter controller input to the CT output. In addition to detecting the above-mentioned failure, it is possible to detect one-phase disconnection in the inverter device, one-phase disconnection on the main circuit on the equipment side, and one-phase disconnection in the main motor circuit. In this way, the present invention can provide an open-phase detection method for an electric vehicle control device that can immediately identify a faulty part.

[Brief description of drawings]

FIG. 1 is an embodiment of the present invention and shows an overall configuration of an open-phase detection system of an electric vehicle control device.

FIG. 2 shows details of the logic part of FIG.

FIG. 3 shows a waveform diagram in a normal state according to one embodiment of the present invention.

FIG. 4 shows a waveform chart of one embodiment of the present invention during an abnormality.

[Explanation of symbols]

 1 Induction motor driving an electric car 2 VVVF inverter device 3 CT 4 logic unit for phase current detection

Claims (3)

[Claims] 1. An induction motor for driving an electric vehicle, an inverter device for controlling the induction motor, and a CT for detecting a phase current.
In the electric vehicle control device having, the logic unit is provided, the average value of each phase current of the polyphase alternating current output by the inverter device is taken, and the average value of these phase currents is further averaged to obtain the average value of each phase current. A phase loss detection method for an electric vehicle control device that detects a phase failure when the difference between the average value and the average value exceeds a reference value. 2. An induction motor for driving an electric vehicle, an inverter device for controlling the induction motor, and a phase current detecting CT.
In the electric vehicle control device having the above, a logic unit is provided, the average values I _U , I _V , and I _W of the respective phase currents of the three-phase alternating current output by the inverter device are taken, and the average values of these respective phase currents are further averaged. The value I ₀ = (I _U + _IV + I _W ) / 3 is obtained, and the difference between the average value of each phase current and the average value | I _U −I ₀ |,
_{| I V -I 0 |, |} I W -I 0 | when exceeds the reference value, open phase detection method of the electric vehicle control apparatus detects that a phase failure fault. 3. The logic unit according to claim 1, wherein the logic unit converts each phase current into an absolute value, calculates an average absolute value of each phase current, and averages each phase current. An electric appliance comprising means for calculating a value obtained by further averaging values, means for calculating a difference between the average value of each phase current and further averaged value, and comparison means for comparing these differences with a reference value. Open phase detection method for vehicle control devices.