JPS6016804B2 - Electric car Chiyotupa protection device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a protection device for an electric vehicle chopper, and more particularly to an improvement in a braking circuit.

BACKGROUND OF THE INVENTION As shown in FIG. 1, a braking circuit for electric vehicle choppers has conventionally used a structure that combines regenerative braking and dynamic braking.

That is, the main smoothing IJ vector 2 is connected in series to the series circuit of the armature IA and the series coil IB of the main motor 1 to form a first electric path. A second electrical circuit that includes the chopper device 3 and constitutes a regenerative braking circuit is connected in parallel to this first open circuit. Further, a dynamic braking circuit including a series circuit of a braking resistor 4 and a thyristor-configured switchgear 5 constitutes a third military path, which is connected in parallel with the first open path. In FIG. 1, 6 is a current collector layer, 7 is a filter reactor, 8 is a filter capacitor, and 9 is a freewheeling diode. As is well known in the art, this electric vehicle chopper operates the chopper device 3 to perform regenerative braking, and also uses the braking resistor 4 via the opening/closing device 5 to perform regenerative braking.

During power running, the electric vehicle chopper with the braking method shown in Fig. 1 disconnects the series circuit of the armature IA and series-wound motor IB of the main motor 1 and operates as a freewheeling motor, as shown in Fig. 2. It is operated by a configuration similar to that connected in parallel to diode 9.

By the way, in an electric car chopper that uses both dynamic braking and regenerative braking as shown in Fig. 1, if the switching device 5 has a short-circuit failure, the main circuit will open and close regardless of whether it is running or braking. Braking resistor 4 through device 5
A current constantly flows through the braking resistor 4.
may become overloaded, resulting in burnout of the resistor and, in some cases, a fire accident in the vehicle.

As a countermeasure against this, conventionally, as shown in FIG. If there is a regenerative load during braking, that is, if current is flowing through the braking resistor 4 even though the normal signal to close the switchgear 5 is not output, this current detector 1 detects this.
1 and thereby detect a failure of the switchgear 5 to protect the pile resistor 4.

In the case of FIG. 3, parts corresponding to those in FIG.
3 and di/ of commutating capacitor 14 and main thyristor 12.
It is configured to include an air-core reactor 15 that serves both as an anode reactor for suppressing dt and as a commutation reactor. However, a current detector 16 is provided in series with the main thyristor 12 to detect commutation failure or short circuit failure. Note that a DCCT is generally used as this current detector 16. In the configuration shown in FIG. 3, the chopper circuit composed of the main thyristor 12, auxiliary thyristor 13, commutation capacitor 4, and air core reactor 15 is called a series arc-extinguishing repulsion pulse system, and its operation is known. be.

However, the current detector 16 for detecting commutation failure can quickly detect an unnecessary conducting state of the chopper 12 by detecting when current is flowing through the main thyristor circuit when the main thyristor 12 should be turned off. However, it is provided to protect the main circuit equipment from overcurrent. If it is configured as shown in FIG. 3, when a failure occurs in the switchgear 5, the detection output of the current detector 11 is used to connect the braking resistor 4.
However, the current detector 11 must be specially installed for this purpose.

However, if this is not specially installed, the overall configuration of the electric car chopper can be further simplified. Taking the above points into consideration, the present invention attempts to realize such a request, and in the present invention, a current detector 11 that detects the unnecessary conduction state of the switchgear 5 and an unnecessary conduction state of the chopper device 3 are provided. The current detector 16 is also used to detect the current, thereby making the current detector 11 unnecessary. An example of the present invention will be described below in detail with reference to the drawings. In the present invention, as shown in FIG. 4 with the same reference numerals assigned to corresponding parts as in FIG. The current detector 16 for commutation failure detection is omitted, and the current detector 11 connected in series to the switchgear 5 is omitted, and instead of this, an open path including the main thyristor 12 and a turtle path including the auxiliary thyristor 13 are used. An abnormality detection current detector 21 having a DCCT configuration is commonly connected to the parallel connection circuit of the switching device 5 and the braking resistor 4. In the case of this embodiment, the wiring on the parallel circuit side of the main thyristor 12 and the auxiliary thyristor 13 is a DCCT constituting the two-turn current detector 21.
It is designed to penetrate. In the configuration shown in FIG. 4, when the electric vehicle is running or under regenerative braking (that is, when no braking resistance is used), the main thyristor 12 should be turned off, similar to the operation of a conventional commutation failure detector. At times, if a current exceeding a set value flows through the current regulator 21, it is determined that there is unnecessary conduction of the main thyristor 12 or unnecessary conduction of the switchgear 5, and a protective operation is performed.

On the other hand, when switching from regenerative braking to dynamic braking and normally short-circuiting the switchgear 5, the short-circuit command changes the detection setting value of the current detector 21, and the main thyristor 12 The current detector 21 detects whether or not a current exceeding this set value is flowing when it should be turned off, and performs a protective operation. Next, the current detection set value at the time of commutation failure and the current detection set value at the time of switchgear failure are detected. The current detection setting value is selected as follows.

That is, assuming that the preset control current of the braking resistor is IRmin to IRmax, the setting value of the current detector 21 is R
．． (Setting value><Vine ‐‐・‐‐‐‐‐‐[11(
(Here, R is the resistance value of the braking resistor 4, and Ec is the voltage of the filter capacitor 8.) On the other hand, if a short circuit command for the switchgear 5 is issued, IR2 (set value) > 1.21
Rmax...{2} (here 1.
2 may be a margin value that also takes into account current ripple.

For example, the range of braking current during dynamic braking is 200A to 40A.
If Ec=1500V and R=30, then Ec/R=
1500V/30=500A...{3}IR
2=1.2×400=480A ・
...■ (Here, 1.2 is a margin value that also takes into account the current ripple), so in this case, the set value is 480
A can be fixed, thereby eliminating the need to change the set value depending on the presence or absence of a short circuit command for the switching device 5, and also simplifying the braking circuit of the current detector 21.

In other words, [3] above, [IR, < 500A, IR2480A is determined depending on the state, and IR, = IR2, so the set value (48
0A) may be the same.

Then, if the short circuit command for the switchgear 5 is not issued,
It is considered that this is an abnormality in the circuit of the switchgear 5 when the main thyristor 12 of the chopper is OFF and a current of Ec/R flows to the current detector 21. Therefore, the abnormality in the circuit of the switchgear 5 is determined by setting the setting value <Ec/R. It can be detected by

Further, it is also possible to confirm an abnormality in the circuit of the main thyristor 12 using the same set value. Further, when a short circuit command is issued to the switching device 5, when the main thyristor 12 is turned off, current is commutated to the switching device 5 side. However, if the main thyristor 12 is short-circuited, the current will not be commutated to the switchgear 5 side, and the current flowing through the main thyristor will further increase. This accident can be detected when the current that had been controlled until then exceeded IRm even though the main thyristor was turned FF. Furthermore, according to the circuit according to the embodiment of the present invention shown in FIG.
Since the CT21 is passed through, the current that actually flows is 2
Since the double value is detected by the DCCT 21, the reduction in protection ability can be made negligible compared to conventional protection.

In other words, in the above example, the setting value of the current detector 21 is set to 50, for example.
In this case, the actual detected current when commutation of the main thyristor 12 fails is 50 blood/2=250 A.

The current detection set value for the conventional commutation failure protection operation is set at 100A to 20 ships, taking into account the prevention of unnecessary operations, so the set value can be considered as having almost no difference.
The reduction in protection ability is negligible. As described above, according to the present invention, it is possible to obtain a protective device capable of detecting failure of commutation of the chopper device 3 and preventing burnout of the braking resistor 4 due to malfunction of the switching device 5. In this way, it is sufficient to provide only one current detector 21 for both functions, thereby further simplifying the configuration of the protection device as a whole.

Incidentally, for example, in the conventional device shown in FIG. 3, only the commutation failure detector 16 of the chopper is used.
It is also possible to prevent the braking resistor 4 from being burnt out due to malfunction of the brake resistor 4, thereby simplifying the construction in which the current detector 11 for detecting failure of the switchgear 5 can be omitted. In the above-described embodiment, the wiring of the main thyristor 12 was made to pass through the current detector 21 by two turns, but increasing the number of turns would be more effective in preventing the protection ability from deteriorating.

[Brief explanation of the drawing]

FIG. 1 is a connection diagram showing the main circuit of an electric vehicle Chobba control circuit that uses both regenerative braking and dynamic braking to which the present invention can be applied;
Fig. 2 is a connection diagram showing the main circuit during power running, Fig. 3 is a connection diagram showing the conventional thyristor chopper section and the dynamic braking circuit, and Fig. 4 shows the protection device according to the present invention in the thyristor chopper section. FIG. 3 is a connection diagram shown together with a dynamic braking circuit and a dynamic braking circuit. 1: Main motor, 2: Main smoothing reactor, 3: Chopper device, 4: Braking resistor, 5: Switchgear, 6: Current collector direct,
7: Filter reactor, 8: Filter capacitor, 9
:Freewheeling diode, 11, 16, 21:
Current detector, 12: Main thyristor, 13: Auxiliary thyristor, 14: Commutation capacitor, 15: Empty reactor. Figure 1 Figure 2 Figure 3 Figure 4

Claims (1)

[Claims] 1. A first electrical circuit in which the main motor and the main smoothing reactor are connected in series, a second electrical circuit that is connected in parallel to the first electrical circuit and includes a chopper device and constitutes a regenerative braking circuit; An electric vehicle chopper that is connected in parallel to the electrical circuit and includes a third electrical circuit that includes a series circuit of a braking resistor and a switchgear and constitutes a dynamic braking circuit, and is configured to use regenerative braking and dynamic braking in combination. An electric vehicle characterized in that a current detector for detecting an abnormality is provided in common in the second and third electric circuits, and the detection output of the current detector prevents burnout of the braking resistor. Chiyotupa's protection device.