JPS6036713B2 - Chiyotupa protection method - Google Patents

Description

[Detailed description of the invention] The present invention relates to a chopper protection method.

In general, devices using choppers, such as electric cars, are becoming popular mainly in subway trains due to their reduced power costs, reduced maintenance costs, and high performance.For example, electric car chopper devices as shown in Figure 1 is used. 1st
The figure is a typical power running main circuit diagram of an electric vehicle chopper device, where 1 is a current collector, 2 is a first unit switch, 3 is a high-speed current reducer, 4 is a current reduction resistor, and 5 is a second unit switch. unit switch, 6
is a charging resistor for a filter capacitor, 7 is a filter reactor, 8 is a filter capacitor, 9A, 9B are traction motor electric windings, 10A, 10B are traction motor field windings, 11
A, 118 are main smoothing reactors, 12A, 12B are freewheeling diodes, 13A, 13B are choppers,
14A and 14B are main motor current detectors, and 17A and 17B are main smoothing reactor current (hereinafter referred to as phase current) detectors.

Second. The figure is a main circuit diagram during regenerative braking in such an electric vehicle.

That is, in FIG. 1, the main motor armature winding 9A,
By disconnecting and grounding the power supply side end of 9B, the series circuit of armature windings 9A, 9B, field windings 10A, 10B, and main smoothing reactors 11A, 11B is connected to chopper 13A,
The connection configuration is the same as when it is reconnected in parallel to 13B.
If there is no regenerative load such as another power vehicle during regenerative braking, there is no destination for the regenerative current, and the voltage value of the filter capacitor 8 increases, and when it eventually exceeds the overvoltage limit, the main circuit is opened and the regenerative braking is activated. It disappears. In this case, braking force must be secured using fair flakes. As a countermeasure to this problem, conventional resistors 15A, 15B and thyristors 16A, 16B are connected in parallel with the choppers 13A, 138 as shown in FIG.
A method has been adopted in which side fields are removed by igniting B.

In this way, when the choppers 13A and 13B are off, the current flows through the thyristors 16A and 16B and the bypass resistors 15A and 15B.
Since the electric current is attenuated through the electric current, constant current control is possible, and stable electric brake action can be continued. In this way, the bypass resistor 15A is connected in parallel with the choppers 13A and 13B.
, 15B, which enables stable electric braking even when the regenerative load disappears.When performing speed control on long-distance slope sections, this method reduces wear of brake shoes and wheels due to continuous use of air brakes. This is an effective method for preventing accidents caused by overheating.

On the other hand, conventional chopper devices as shown in Figures 1 and 2 are equipped with various protection functions such as overvoltage detection, overcurrent detection, and low voltage detection. Shunt resistors 15A, 15B and thyristors 16A, 16
When a series circuit B is provided, detection and protection in the event of these failures must also be taken into consideration.

First, considering the thyristors 16A and 16B, if they fail, current will flow through the resistors 15A and 15B even if a gate signal is applied to the thyristors 16A and 168 when the regenerative load disappears as shown in Figure 3. As a result, the voltage of the filter capacitor 8 continues to rise until an overvoltage is detected and the main circuit is opened to act as an air brake.

Therefore, there is no particular problem even if the thyristors 16A, 16B have an open failure, and since the overvoltage detection operates every time the regenerative load disappears, the failure can be detected. However, if the thyristors 16A and 16B are short-circuited, it cannot be directly recognized as a phenomenon, and when the main circuit is configured, the newly installed resistors 15A and 15B will Current will continue to flow.

However, although the resistors 15A and 15B generally have a sufficient capacity to absorb braking energy over the entire braking period, if a short circuit failure occurs during power running,
In this case, a current exceeding the capacity will flow, and there is a danger that the resistors 15A and 15B will be burnt out, which may lead to a fire accident in the vehicle. Therefore, during power running, short-circuit failures in the thyristor must be detected. As this detection method, resistor 15A,
A current detector is installed in the series circuit of thyristor 158 and thyristor 16A, 168. A possible method is to detect a short-circuit failure in the thyristors 16A and 16B when current flows when it should not. However, this method requires the provision of a new current detector, which inevitably increases the complexity and size of the overall configuration. The present invention has been made in consideration of the above points, and it is possible to protect the shunt resistor by detecting a short-circuit failure of the thyristor at the start of power running using the conventional device without installing a new current detector. The purpose of this invention is to provide a chopper protection method. The present invention will be explained below based on the illustrated embodiments.

FIG. 4 shows a circuit diagram to which the present invention is applied. In the figure, when starting power running, thyristors 16A, 16
A series circuit of B and bypass resistors 15A and 15B is connected in parallel with choppers 13A and 13B. In the connection state shown in Fig. 4, when a power running switch command is given,
As shown in FIG. 5A, the unit switch 2 receives an interlock signal s. is applied and turned on, and the voltage s2 across the filter capacitor 8 is charged as shown in FIG. 5C. When the charging of the filter capacitor 8 is completed, as shown in FIG. 5B, . switch 5
An interlock signal s3 is applied to the choppers 13A and 13B, and the choppers 13A and 13B start turning on and off. Chotsupa 13A and 13B from the time point et al.
On and off operations start, but in order to prevent inrush current to the main motor during power running, the phase shift of the choppers 13A and 13B is minimized until a certain point t3, so that the phases do not open. During the time up to time t3, the chopper frequency is lower than the rated frequency. With such measures,
The voltage applied to the main electric machine is reduced and inrush current can be prevented.

However, if the thyristors 16A, 16B are short-circuited, current flows through the main smoothing rectors 11A, 11B and the bypass resistors 15A, 15B, regardless of the on/off operation of the choppers 13A, 13B.

This current is determined by the impedance of the bypass resistors 15A and 158 and the impedance of the circuit, and is determined from t2 to [
The current is much larger than the current that normally flows between 3 and 3.

This current is detected by the phase current detectors 17A and 17B, which normally detect it for phase current imbalance correction, and is detected from t2 to t.
If a certain current or more flows for three hours, the thyristors 16A and 16B detect a short-circuit failure. FIG. 6 shows the state of the outputs from the phase current detectors 17A and 17B.

The solid line shows the rise in phase current under normal conditions, but if the thyristor 16A or 16B causes a short-circuit failure as described above, it will show a rise as shown in the dotted line, which is detected between L and t3 and the circuit By outputting an opening command, the problem that has been entrusted to you can be prevented.

As described above, according to the present invention, in a chopper system in which a series circuit of a thyristor and a bypass resistor is connected in parallel with the chopper, regenerative current is distributed to each side.
By making it possible to reliably detect this short-circuit failure of the thyristor at the start of power running, it is possible to prevent burnout of the resistor and fire accidents in the vehicle. This can be easily achieved without adding anything.

[Brief explanation of drawings]

1 to 4 are connection diagrams of an electric car chopper device to which the present invention can be applied, and FIGS. 5 and 6 are signal waveform diagrams for explaining an example of the chopper protection method according to the present invention. 1... Current collector calendar, 8... Filter capacitor, 11A, 11B... Main smoothing reactor, 13A, 13B... Chotsupa, 15A, 15
B...Shunt resistor, 16A, 16B...thyristor, 17A, 17B...phase current detector. Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6

Claims (1)

[Claims] 1 Connect the controlled motor and chopper in series with the switch that turns on and off the power via a filter capacitor and a smoothing reactor, and connect the chopper with a control rectifier and attenuate the electric brake control current when the regenerative load disappears. In the device, the charging voltage of the filter capacitor reaches a predetermined value at the start of power running. When the current flowing through the current detector reaches a reference value or more within a predetermined time after the current detection, this is detected as a short-circuit failure of the control rectifier, and the switch is immediately disconnected to close the shunt resistor. A chip protection method characterized by protection from overcurrent.