JPS6155321B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an automatic variable field type electric vehicle control device using a chopper type DC power controller.

DC electric cars using Chiyotsupa do not have losses due to resistors like conventional cars, and can easily perform regenerative braking control, making them ideal for subways as electric cars that can significantly reduce power consumption. It is rapidly becoming popular in the center. Among them, a chopper controls the voltage applied to the motor by dividing the field winding of the DC series motor being driven into two, and inserting one in series with the armature and the other in a chopper current intermittent circuit. Many automatic variable field methods that simultaneously control the field itself have also been put into practical use.

This automatic variable field method will be explained first. Figure 1 shows the main circuit during power running, where PAN is a pantograph, FL is a filter reactor, FC is a filter capacitor, A is the armature of the motor, _F1 is the first series field winding, and MSL is the main smoothing field winding. Reactor, CH is chiyotsupa, FWD is freewheeling diode,
F ₂ is the second field winding, AFWD is the second field winding
Freewheeling diode for _F2 , SHR
is an extraordinary resistance. The currents in the armature and the first series field are accelerated by constant current control by the chopper, and the current flow rate of the chopper increases as the speed increases.

Here, the current flowing through the second field winding _F2 returns from the armature circuit when the chopper is OFF, so the magnetic flux of this second field winding _F2 decreases as the conductivity increases. Become. Therefore, in an electric motor in which the magnetic fluxes of F ₁ and F ₂ are harmonized, the field itself gradually weakens, and when the conductivity reaches 1.0, the field becomes weakest only for F ₁ . In this way, field control is automatically performed as the speed increases.

Also, during regenerative braking, the second field winding _F2 is connected in series with the chopper CH, as in the main circuit shown in FIG. Since the conductivity is small in the high speed range, the magnetic flux of the field winding _F2 is small and the field is in a weak state, but as the speed decreases, the conductivity increases and the field is strengthened.

This type of automatic variable field system can automatically control the field using a single chopper, eliminating the need for conventional field shunt resistance, induction shunts, and field weakening switches. The feature is that it is suitable for autonomous driving because it is controlled.

However, the following points remain to be improved.

(1) In order to switch the position of the rotating magnetic winding _F2 between power running and regenerative braking, many switches P and B of the power running braking converter as shown in Fig. 3 are required. Note that switch P closes the circuit during power running, and switch B closes the circuit during braking.

(2) Due to motor design issues, the first field winding F ₁
It is not possible to greatly reduce the magnetic flux at
A relatively large amount of magnetic flux was applied to the second field winding F ₂ , the amount of magnetic flux of the motor did not weaken significantly, and there was an upper limit to the speed range in which regenerative braking was effective. To give an example using specific numerical values, when expressed in terms of magnetic flux, or ampere-turn ratio, the direct winding field component is generally greater than 35% due to motor constraints, and in addition to this, it is necessary to operate at a minimum current flow rate. However, considering the added field component of the second field winding _F2 , the weakest field rate during regenerative braking is
Generally, it is around 45-50%.
The magnetic flux due to the second field winding _F2 is determined by the conductivity and the fourth
This is because the relationship is not linear as shown in the figure, and even if the conductivity is small, it becomes relatively large.

The present invention has been made in view of this point, and is designed to reduce and simplify the main circuit, especially the power running/braking switching section as much as possible, and to enable regenerative braking to operate from higher speeds.

Hereinafter, one embodiment of the present invention will be described based on the drawings. FIG. 5 shows the main circuit according to the invention. Note that the same reference numerals as in FIG. 1 indicate the same parts, so the explanation will be omitted, but the number of switches P and B of the converter has been reduced. That is, during braking, the second field is short-circuited by switch B. By doing this, the number of switches for changing the position of the second field winding _F2 is only one for this short circuit, and the main circuit becomes very simple.

In addition, since only the direct winding field is used during regeneration, field weakening control of about 35% is also possible, greatly improving the speed range in which regeneration is possible. Furthermore, this second field winding F ₂
Since the field by F1 and the series-wound field by the first field winding _F1 have windings at the same pole, the degree of coupling is large and the coupling rate reaches about 90%. By short-circuiting the field generated by this second field winding F ₂ as described above, the first series field winding F ₁ used for control is changed to the short-circuited winding for each motor. Since the direct winding characteristic is diluted and approaches the shunt winding characteristic, control can be extremely stable. This is because, in a winding circuit configured as described above, if it is short-circuited externally, if a large current suddenly tries to flow through the first series field winding _F1 , the Change is the second series field winding
An attempt is made to induce a voltage in _F2 , but since the load is short-circuited, a large current flows immediately. This current is of opposite polarity to the first series field winding F ₁ current due to its inducing principle. Therefore, this again influences the first series field winding F ₁ side and acts in a direction to suppress the current in the first series field winding F ₁ . Therefore, it is in a form that makes it difficult for the field to change transiently. That is, it has a shunt characteristic. Like the shunt characteristic, even if the armature current increases, as long as the field, that is, the induced voltage, does not change, the current will not increase further, so it is easy to control.

In other words, in regenerative control using a chopper, when the chopper is turned on, a short circuit is created for the motor, causing the current and voltage to rise, and then attenuated when the chopper is turned off. However, since it is a series-wound generator, once normal operation is disrupted, It has the potential for instability that causes self-excitation and divergence phenomena at once.

Therefore, when the shunt characteristic is emphasized, it is difficult to diverge, and with fast response control such as chopper control, a sufficiently stable system can be maintained even against disturbances. In the conventional automatic variable field system as shown in Fig. 2, when the magnetic flux of the first field winding F _{1 is about to increase, the flux of the second field winding F 2 flowing} in the direction to suppress this increase is Since the current is through the parallel resistor SHR and AFWD is in the opposite direction, the effect is not large.

On the other hand, as shown in FIG. 5, the present invention short-circuits the brake converter switch, so the first field winding
This is highly effective because the second field winding short-circuit current that suppresses the increase in the magnetic flux of _F1 flows.

As described above, in the present invention, while taking advantage of the features of the automatic variable field system, it is possible to further simplify the circuit, greatly improve the high-speed characteristics of the regenerative brake, and increase the stability of the regenerative control.

[Brief explanation of the drawing]

Figures 1 and 2 are power running and regenerative brake main circuit diagrams of a conventional automatic variable field type chopper control vehicle, and Figure 3 is a diagram of a conventional automatic variable field type chopper control vehicle including a power running/braking switch. Main circuit diagram, 4th
The figure is a field characteristic diagram of an automatically variable magnetic field, and FIG. 5 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, A is the armature, F ₁ is the first series field winding, F ₂ is the second series field winding, CH is the chopper,
FWD is a freewheeling diode, MSL is a main smoothing reactor, and P and B are power running/braking converter switches.

Claims (1)

[Claims] 1. In a control device that performs speed control of a DC motor via a Chiyotsuba type DC power control device between a DC power source, a first field winding connected in series to the armature as a field winding of the motor. and a second field winding connected in series to the intermittent electric circuit of the Chiyotsuba type DC power control device and wound around the same magnetic pole as the first field winding, An electric vehicle control device further comprising a switch that short-circuits the second field winding during braking.