JPH0793767B2 - Inverter type electric car braking circuit - Google Patents

Description

The present invention relates to a dynamic braking device for an inverter-controlled electric vehicle,
In particular, the present invention relates to a control device that extends the effective period of dynamic braking.

[Conventional technology]

For example, as disclosed in Japanese Patent Laid-Open No. 59-28802, the conventional device increases the excitation voltage of the main electric motor when applying a dynamic brake when the overhead line voltage of the main power supply in the inverter-controlled electric vehicle fails. It has been proposed to charge a filter capacitor from an auxiliary power source via a transformer and a rectifier (preliminary charging device).

[Problems to be solved by the invention]

The above-mentioned conventional technique has a problem that a preliminary charging device is required to charge the filter capacitor when the power generation brake is applied at the time of power failure of the overhead line.

An object of the present invention is to provide a regenerative braking device for an inverter train that can operate the regenerative braking satisfactorily even during a power failure of the overhead line without installing a preliminary charging device.

[Means for solving problems]

The above object is achieved by connecting a discharge blocking device, for example an avalanche element, to the discharge circuit of the filter capacitor.

[Action]

That is, the filter capacitor voltage charged during power running is held by the breakdown voltage of the avalanche element even during coasting, and the minimum excitation voltage of the main motor required to apply the dynamic braking can be maintained.

〔Example〕

The figure shows a simplified main circuit diagram of an inverter-controlled train with a generator brake according to the present invention.

1 is a current collector, 2 is a line breaker, 3 is a reactor reactor,
4 is a resistor for dynamic braking, 5 is a filter capacitor,
6 is an inverter device, 6U, 6V, 6W, 6X, 6Y, 6Z is a power switching element, 7 is a main induction motor, 8 is a power generation brake circuit configuration switch, 91 and 92 are discharge blocking means, and 10 is a filter capacitor voltage detection A transformer, 11 is a transformer for detecting an arm short circuit of the power switching element.

Now, it is assumed that the regenerative brake acts and the regenerative power is returned from the main induction motor 7 through the inverter device 6, the filter reactor 3, the line breaker 2, and the current collector 1 to the overhead line. At this time, if there is a power outage in the overhead line, there will be no regenerative power destination, so first close the switch 8.
Connect the brake resistor 4 to the inverter. As a result, electric power is consumed by the resistor 4, and the brake continues to operate. At this time, the excitation power source of the main motor is the filter capacitor 5, and the operation of charging the main motor with the regenerative power from the main motor is repeated while exciting the main motor. The disconnector 2 is opened after the switch 8 is closed, and the inverter device is electrically disconnected from the overhead line.

When the overhead line is out of power while the electric car is coasting, the charge of the filter capacitor charged in the power running state before that is as shown by the arrow, the transformer 10 for detecting the voltage of the filter capacitor,
An attempt is made to discharge the primary side coil of the transformer 11 for detecting arm short circuit. Here, when all the charges charged in the filter capacitor are completely discharged, the filter capacitor voltage becomes zero, and the excitation voltage of the main electric motor disappears. Therefore, no voltage is generated in the electric motor and the generator brake does not work. Therefore,
By disposing the discharge blocking devices 91 and 92 in all the filter capacitor voltage discharging circuits, the discharge of the filter capacitor voltage is blocked, and the voltage higher than the excitation voltage of the main motor is held, so that the power generation braking operation can be smoothly performed. it can.

In this embodiment, a zener diode is used as the discharge prevention means.
It is composed of 91, 92.

According to the principle of the present invention, the voltage of the filter capacitor charged during power running is not discharged to zero voltage, and the voltage is used to raise the brake current to perform the power generation braking.

The breakdown voltage of the Zener diodes 91, 92 is selected as a Zener diode having a minimum excitation voltage of the main motor or more. .

If the overhead line is interrupted while the electric car is coasting, the electric charge of the filter capacitor charged during the power running is discharged through the 10, 11 transformers. However, due to the zener diodes 91, 92, the filter capacitor voltage is
It becomes the same voltage as the breakdown voltage of 2 and keeps that state. Since this voltage is previously selected to be equal to or higher than the minimum excitation voltage of the main motor, the brake current rises by the subsequent braking operation, and the generated braking force acts. The braking force control at this time is exactly the same as the conventional regenerative braking.

As described above, according to the present embodiment, smooth power generation braking can be performed without the preliminary charging device, and the control device as a whole can be reduced in size and weight.

〔The invention's effect〕

ADVANTAGE OF THE INVENTION According to this invention, in the electric vehicle which operates a dynamic brake also at the time of a power failure of an overhead line, the preliminary charging device for main-motor excitation is unnecessary, and the whole apparatus can be made small and lightweight.

[Brief description of drawings]

FIG. 1 is a main circuit connection diagram of an inverter train showing an embodiment of the present invention. 1 ... Current collector, 2 ... Breaker, 3 ... Filter reactor, 4 ... Generator brake resistor, 5 ... Filter capacitor, 6 ... Inverter device, 7 ... Main induction motor, 8 ... … Switches, 91 and 92 …… Discharge prevention means (Zener diode).

Claims (2)

[Claims] 1. A transformer (10, 11) and a discharge blocking means (91, 9).
2) A braking circuit of an inverter type electric vehicle having and, in which the electric vehicle generates energy generated by an induction motor (7),
Braking control is performed by absorbing it in a brake resistor (4) via an inverter (6) to which a filter capacitor (5) is connected in parallel. The transformer (10, 11) is an inverter (6). The discharge prevention means (91, 92) is connected in series with the transformer (10, 11) to prevent discharge by the transformer (10, 11) Inverter type Braking circuit for electric cars. 2. The braking circuit for an inverter type electric vehicle according to claim 1, wherein the discharge prevention means (91, 92) is an avalanche element (91, 92).