JPS5843361Y2 - electric car ammeter circuit - Google Patents

Description

[Detailed description of the invention] Many electric vehicles are equipped with a main circuit ammeter in the driver's cab, allowing the main motor current of the vehicle to be monitored.

In this case, if you insert an ammeter shunt into a circuit that reverses the current when moving and braking, by using a double-sided carved flow meter, the pointer will swing to the right from the zero point when moving, and when braking. By swinging time in the opposite direction, you can make it more tangible.

On the other hand, in recent years, from a safety standpoint, the main circuit current is converted to a low voltage proportional to the current using a direct current transformer (DCCT) in order to avoid running the main circuit (high voltage) line into the driver's cab as much as possible. However, a method is used in which this causes the DC voltmeter in the driver's cab (the scale is the main circuit ammeter) to swing.

However, the generally used DCCT uses an output obtained by full-wave rectification of the secondary side AC current that is proportional to the main circuit current, so even if the polarity of the main circuit current is reversed by driving or braking, the output polarity remains the same. Therefore, it is impossible to use a double-swing ammeter like the method using an ammeter shunt described above.

If it is necessary to force both swings, it is necessary to make the DCCT a special and complex one whose output polarity changes depending on the polarity of the main circuit current.

However, this Dα control is generally used in common with the DCCT for detecting the main motor current of an electric vehicle, and in a control device with a normal dynamic brake, the polarity of the output of the DCCT is different for control purposes.
There is no problem with brake co-polarity, and it is not a good idea to simply provide a sophisticated CCT for the main circuit ammeter in the driver's cab.

This invention was made to solve the above-mentioned drawbacks.
With a slight improvement, the output of the DCCT is used to cause the double-oscillation ammeter to swing.

Hereinafter, the present invention will be explained based on the drawings of the embodiments.

FIG. 1 shows an embodiment of the present invention, in which 1 is a detection coil of a DCCT, and 2/'i is an electric wire through which a main circuit current flows.

Current flows in the direction 2a when driving, and in the direction 2b when braking.

3 is a DCCT rectifier circuit, and the output is a voltage proportional to the main circuit current with the same polarity regardless of whether the motor is running or braking.

4 is a polarity conversion circuit related to the present invention, 5 is a double swing ammeter (
DC voltmeter).

An electric vehicle control device with a dynamic brake is provided with a converter for switching between power and brake, or a relay that operates in either power or brake.

The polarity conversion circuit 4 in FIG. 1 is intended to utilize the auxiliary contacts of these converter casings or relays.

FIG. 2 is an example of a circuit using the auxiliary contacts of a converter.

6a and 6b are contacts that close when moving, and 7a and 7b are contacts that close when braking.

As a result, a voltage with reversed polarity is applied to the ammeter at power/brake.

It can be easily inferred that a similar circuit can be formed using a relay that operates on either the power line or the brake.

As described above, according to the present invention, it is possible to provide a power and brake runout ammeter with high safety and low cost.

[Brief explanation of the drawing]

FIG. 1 is a connection diagram showing one embodiment of the present invention, and FIG. 2 is an example of a polarity conversion circuit. 1...DCCT detection coil, 2...Main circuit wire, 2a...Current direction during power running, 2b...
...Current direction during braking, 3...DCCT
Rectifier circuit, 4...Polarity conversion circuit, 5...
・Double swing ammeter, 6a, 6b...Contacts that close when moving, 7a, 7b...Contacts that close when braking.

Claims (1)

[Scope of utility model registration request] In an electric vehicle control device, the main motor current is detected by the output of a DC current transformer with a common polarity for the power line and brakes, and this is changed to the opposite polarity for the power line and brakes at the power line and brake switching contacts in the controller. An ammeter circuit for an electric car that is equipped with a polarity conversion circuit and uses the circuit output to cause a double-swing ammeter to swing.