JPS5918922B2 - electric car protection device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a protection device for an electric vehicle that protects a motor of an electric vehicle that performs regenerative brake control using chopper control.

Figure 1 is a circuit diagram showing the conventional regenerative brake chopper control system. In the diagram, Es is the power supply, FL is the filter reactor, Fc is the filter capacitor, FWD is the free polling diode, and CH is the ON/OFF switch. The chopper that controls the motor, MSL is the main smoothing reactor that smoothes the motor power supply, A1 to A4 and A5 to A8 are the motor armatures, Fll, F21, F31, and F41 are the series field windings of armatures A1 to A4. , F51, F61, F7
1. F81 is the series field winding of armatures A5 to A8, F12
~F82 is the shunt field winding which is the other field winding of each armature, FR is the shunt resistance for controlling the field rate, and FRD is the shunt field winding F12 when the chopper CH is turned off. ~F8
2, a freewheeling diode to prevent the current flowing to the channel from being interrupted, CFD is a commutation failure detector to detect when CH commutation has failed, and HB is a commutation failure detector that detects when commutation of the chopper fails, immediately upon receiving the CFD detection signal. BSL is a high-speed circuit breaker that interrupts the circuit to prevent accidents such as motor flashover, and BSL is a current-limiting reactor that suppresses the di/d of fault current when commutation fails.

The operation of this circuit will be explained next.

When chopper CH is turned on by the voltage generated in motor armatures A1 to A4 and A5 to A8, main smoothing reactor MSL → chopper CH → series field winding F12 to F
82→High-speed circuit breaker HB→Current limiting reactor BSL→Series field winding F51 to F81, L1, armature A5 to A8, L2 connected in parallel to armature A1 to A4, series field winding A current flows in the circuits Fll to F4l, and when the chopper is 0FF, the current is regenerated in the circuit of main smoothing reactor MSL→free polling diode FWD→filter reactor FL→power source Es. When regeneration is applied from high speed, conduction rate α
is controlled by the minimum current conductivity αMin, so the current 1f flowing through the shunt field windings Fl2 to F82 depends on αMin and is very small. Since the series field windings Fl1 to F81 and the shunt field windings Fl2 to F82 are wound in a harmonic manner, if If is small, weak field control is performed. When regeneration is applied from high speed and the speed decreases, the current flow rate α to compensate for the decrease in the induced voltage of the motor gradually expands, but as a result If also increases, the field weakening control is changed to the strengthening field control. transition to.

In other words, the field control during regenerative braking is performed continuously and automatically, making it possible to increase the speed range in which regenerative braking is effective without increasing the motor capacity.The above operation is well known. The commutation failure protection of this variable field chopper control is the same as the constant field control chopper.
As shown in the figure, when the commutation failure detection CFD is activated, the high-speed circuit breaker HB is instantly tripped to prevent motor flashover, but the tripping operation of the high-speed circuit breaker HB is due to mechanical operation. In order to protect the motor and other main circuit equipment even if commutation fails during high-speed regeneration, it is necessary to make the main smoothing reactor MSL air-core and increase the inductance value. In order to suppress the rise of current loss Di/Dt, it is necessary to arrange a current rise suppression reactor BSL or a limiting resistor to play an equivalent role, and the increase in these devices often results in a cost increase for the electric power unit. It has been raised as an issue.

This invention was made in view of these points,
The present invention provides a protection device for an electric vehicle that protects a motor and other main circuit devices without increasing the size of a smoothing reactor MSL or using a special ultra-high speed circuit breaker.

An embodiment of the present invention shown in FIG. 2 will be described below.

In the figures, the same reference numerals as in FIG. 1 indicate the same or corresponding parts. FTH1 and FTH2 are switching elements such as thyristors or switches that operate in response to a commutation failure detection signal or when the motor current becomes larger than the current flowing normally.

Next, the operation will be explained. The normal chopper operation is the same as that shown in FIG. 1 above, so a description thereof will be omitted. When an overcurrent phenomenon occurs, the switching element FTHl is ignited to transfer the voltage 4Ea of the armatures A5 to AA8 of the motor to the series field windings F5l to F8l via the switching element FTHl.
is applied to cause a reverse excitation current to flow, and the motor armature A5~
While rapidly decreasing the voltage of A8, armatures A1 to A4
→Series field windings Fll~F4l →L2 →Switching element FTHl circuit also applies a reverse excitation current to the series field windings Fll~F4l depending on the 4Ea voltage, and armatures A1~
The voltage of A4 is also rapidly reduced. This makes it possible to reduce the excessive current flowing through the main smoothing reactor MSL and chopper CH of the motor. However, according to the author's simulations, in the automatic variable field magnet u control system shown in Figure 1, if commutation fails, an overcurrent flows through the shunt field windings Fl2 to F82, causing the motor to have a stronger field. , the effect of reverse excitation is weak, and overcurrent phenomena cannot be suppressed instantaneously. Therefore, at the same time as switching element FTHl is ignited, switching element FTH2 connected in parallel with shunt field windings Fl2 to F82 is ignited, and the commutation failure current is caused to flow to the switching element FTH2 side. Eliminate the influence of the field due to windings Fl2 to F82,
This enhances the effect of reverse excitation. In this way, after igniting the switching elements FTHl and 2, it is only necessary to slowly open Ll and L2 after the motor current decreases, so there is no need to enlarge the main smoothing reactor MSL or install an extra current suppressing reactor BSL. Since there is no need to use a special ultra-high-speed circuit breaker HB, it is advantageous in terms of being an economical and non-contact protection method. FIG. 3 shows another embodiment of the present invention, in which the voltage Ea of the motor armature A8 reversely excites the series field F5l to F8l to rapidly reduce the voltage of the motor armatures A5 to A8. At the same time, depending on the voltage difference between the armatures A1-A4 and the armatures A5-A7, a reverse excitation current is caused to flow through the series field windings Fll-F4l, thereby rapidly reducing the voltage of the armatures A1-A4. In addition, in this method, since the voltage of one motor is applied to the field, good results can be obtained in terms of motor commutation.
Switching element FTH2 to switching element FTHl
It goes without saying that simultaneous ignition must be carried out in the same manner for the reasons stated above. In the above description, the control of eight motors has been described, but the gist of the invention does not differ from the gist of the invention no matter how many motors there are as long as the method provides reverse excitation using the armature voltage of one or more motors.

In addition, an example of the main circuit of variable field control in which the present invention is implemented is shown in the first section.
As shown in Figures to Figure 3, even in other main circuits that perform field control, if the rolling current strengthens the motor and creates a field, or otherwise short-circuits the field at the same time, which has an adverse effect on reverse excitation. However, this does not differ from the gist of the present invention. As described above, according to the present invention, there is no need to enlarge the raw smoothing reactor or provide an extra current control reactor.
Moreover, there are various effects such as no need for a special ultra-high-speed circuit breaker, making it more economical than conventional circuit breakers.

[Brief explanation of the drawing]

FIG. 1 is a circuit diagram showing a conventional device, FIG. 2 is a circuit diagram showing one embodiment of the invention, and FIG. 3 is a circuit diagram showing another embodiment of the invention. In the figure, A1 to A8 are armatures, Fl1 to F8l are series field windings, Fl2 to F82 are shunt field windings, MSL is a main smoothing reactance, CH is a chopper, CFD is a commutation failure detector, FTH1 and FTH2 are switching elements.

Claims (1)

[Scope of Claims] 1. A DC motor comprising at least two DC series motors connected in parallel, each having a series field winding and another field winding wound harmonically around the series field winding. A motor group, a chopper control device for controlling the operation of the DC motor group, and a series circuit of the other field winding and the chopper control device, and field control continuously and automatically changes from weak field control to strong field control. In a system that performs regenerative braking operation using an automatic variable field system, an abnormality detection device is installed to detect an abnormality due to commutation failure of the chopper, and the electric motor of the first DC series motor of the two DC motors is installed. The series field winding of the second DC series motor is connected to the low voltage side to form a first electric circuit, and the first DC series field winding is connected to the high voltage side. The armature of the second DC series motor is connected to the low voltage side to form a second electric path, and the first electric path is connected between the first and second electric circuits.
A first short-circuit device is provided so that the armature of the electric circuit and the series field winding of the second electric circuit constitute a closed circuit, and a second short-circuit device is provided in parallel with the other field winding. A protection device for an electric vehicle, characterized in that the first and second shorting devices are short-circuited by the detection signal of the abnormality detection device. 2. The electric vehicle protection device according to claim 1, wherein the short circuit device is a thyristor.