JPS5826274B2 - Mortanokai Sabre-kiseigiyosouchi - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an improvement of a control device for performing regenerative brake control of a DC motor such as an electric vehicle by chopper control.

For convenience, the case of an electric vehicle will be described below, but the present invention is not limited to this.

When regenerative braking of an electric motor such as an electric vehicle is performed by chopper control, there is a drawback that the regenerative braking force is insufficient in a high speed region.

This is because the motor is used as a DC series generator, but as a way to overcome this drawback, a resistor is inserted in series with the motor, and only the voltage valve of the current and resistance product of this resistor is used.
There is a way to eliminate the lack of braking power at high speeds by increasing the power generation pressure of a series-wound generator.

The present invention relates to a short-circuit control method for a resistor inserted in series with a motor.

In Figure 1, E is the power supply, LF is the filter reactor, CF is the filter capacitor, DF is the flywheel diode, CH is the chopper device, MSL is the main smoothing reactor for smoothing the motor current, F is the motor field, and A is the The armature of the motor, R represents a series resistance of the motor, and S represents a switch for short-circuiting this resistance R.

That is, when the electric car is in a high-speed region, the switch S is open and the motor current flows through the resistor R, so the motor generated voltage is controlled on and off by the chopper CH via the voltage drop of the resistor. Flywheel diode D
A regenerative current flows to the power source E through F and the filter reactor LF.

Then, when the speed is in the medium speed range, this resistance R is switched to the switch S.
is short-circuited, and regenerative braking is controlled with the resistor R not inserted.

In this main circuit diagram, the moment resistor R is short-circuited with switch S, the R voltage across resistor R suddenly drops to zero, so the current flow rate of the chopper changes, causing regenerative current flow.

is about to increase. However, filter reactor LF
Since the regenerative current I8 cannot be changed instantaneously due to the inductance, the regenerative current increased due to the change in conductivity is charged to the filter capacitor CF.

The voltage of the filter capacitor CF is this filter capacitor charging current■.

will be overcharged, and the overvoltage will be caused by the resistance R
If the voltage is large, it can reach 20 to 50 points higher than the normal voltage, which is dangerous.

It is most important to make this value small in the main circuit system shown in FIG. 1, and if this value is made small, the rated voltage of the chopper will be the same as the normal voltage, which is economical.

That is, in regeneration control using a chopper, the filter capacitor voltage can be expressed by the following equation.

VFc=(EM-R・1M)/(1-γcH)...[
1] Formula ■8=(1-γ.

H)・■Ya...[2] Formula [1] Formula and [2]
From the formula, VFc - (EM R・1M)・M/■8...[
3] Formula where, VFc: Filter capacitor voltage value EM
Motor voltage value 8: Regenerative current value M: Motor current value γcH: Chotsupa conduction rate R: Series resistance value Here, if the resistor R is instantaneously short-circuited by the switch S, the equation in the above [3] The term R・■□ disappears, and the motor current IM is kept constant through chopper control, and the regenerative current ■8 cannot change instantaneously due to the presence of the filter reactor, so the resistor R is short-circuited. Immediately after, the filter capacitor voltage ■,.

results in a sudden increase in the ratio of EM/(EM-R·1M).

The present invention has been made in view of these points, and relates to a device that suppresses overvoltage when a resistor is short-circuited.

That is, in this invention, R in the above formula [3]
□A reactor is inserted in series with the switch S to prevent the voltage indicated by □ from being short-circuited instantaneously.
), so that the voltage that becomes R・IM is gradually short-circuited, and during this time, the regenerative current I8 increases while resisting the filter reactor, thereby reducing the peak value of the filter capacitor voltage jump. It is something to suppress.

Here, the larger the inductance value of the actuator inserted in series with the switch S, the more the rapid rise peak value of the filter capacitor voltage VFC immediately after the resistor R is short-circuited will be suppressed to a small value, but the larger the inductance The weight and size of the Akudol are considerably large, making them impractical.

Therefore, in this invention, by using a saturable iron core with extremely high magnetic permeability and using an adle, a small and lightweight adle that exhibits a large inductance for a predetermined necessary time period is adopted. The feature is that it is possible to reset the magnetization of the iron core without the need for a special external power supply.

In order to ensure the reset of the saturable core, a current detector detects that the magnitude of the current flowing through the reverse excitation winding is greater than a predetermined value, and on this condition, switch S is activated.
It will be even more safe and secure if the

Hereinafter, one embodiment of the present invention will be described based on the drawings.

Fig. 2 is a main circuit diagram showing an embodiment of the present invention. Components with the same reference numerals as in Fig. 1 represent the same functions, so the explanation will be omitted. DCCT is a current transformer for current detection, and CD is a current transformer for current detection. The current detector converts the output of the DCCT to an appropriate level and uses it for motor current control and motor current detection.

R is the same resistance as shown in Figure 1, and AL has two windings or an actuator, one winding is connected in series with the resistor R, the other winding is connected in series with the switch S, and is connected to the iron core. are connected with opposite polarity to each other or indicate an accelerator.

However, if the reactor has one turn of winding, it is sufficient to just pass the electric wire through it, so the smallest reactor may be just an iron core.

The operation of a device configured in this way is that when the regenerative braking current initially rises, it starts up with the resistor R inserted (switch S is open), and the motor current is connected in series with the resistor R. The current is applied to the winding of the reactor AL (reverse excitation winding) to reset the excitation of the iron core of the reactor AL.

After a certain period of time, the resistor R is short-circuited, which is done by short-circuiting the switch S, and the reactor AL
A current flows through the winding in series with the switch S, and the current in the winding in series with the resistor R is attenuated.

Therefore, when the switch S is turned on, the current flowing through the switch S, that is, the resistor short-circuit current, does not increase rapidly due to the inductance of AL, but increases by di/dt due to the inductance of the reactor AL.

This means that the voltage across the parallel connection of the resistor R, switch S, and reactor AL gradually changes to zero from the moment the switch S is turned on, and the filter capacitor C
The drawback of the circuit of FIG. 1 of overcharging F will be eliminated.

Moreover, since the saturation direction of the iron core differs between the state in which the resistor R is inserted and the state in which it is short-circuited, the reactor AL uses an iron core that does not saturate for a certain period of time with respect to changes in current or voltage. It is often quantified into a very small size.

As described above, according to the present invention, it is possible to prevent the filter capacitor from becoming overvoltage when a resistor is short-circuited with a simple configuration.

[Brief explanation of drawings]

FIG. 1 is a main circuit diagram showing a conventional electric vehicle regenerative brake circuit, and FIG. 2 is a main circuit diagram showing an embodiment of the present invention. Note that the same reference numerals in the figures indicate the same or corresponding parts. In the figure, CH is the chopper, F is the motor field, A is the motor armature, LF is the filter reactor, CF is the filter capacitor, DF is the flywheel diode, R is the resistor, S is the switch, and CD is the current detector. , AL is a reactor.

Claims (1)

[Claims] 1. By controlling on/off a chopper connected in parallel to a motor provided in a circuit having a filter reactor and a filter capacitor, regenerative current is caused to flow through the flywheel diode and the filter reactor to the power source side. In a regenerative brake control device that has a resistor connected in series with the motor and a switch that short-circuits the resistor, a reactor is connected in series with the switch, and the reactor is connected in series with the resistor. A regenerative brake control device for a motor that is equipped with an excitation line that excites the iron core in the opposite direction. 2. A current detector is provided to detect the current of the motor, the chopper is operated with the resistor inserted, and after detecting that the current value has exceeded a certain value, the switch is operated. A regenerative brake control device for a motor according to claim 1.