JPH01248901A - Generative brake controller for electric vehicle - Google Patents

Abstract

PURPOSE:To reduce the thermal capacity of a brake resistor, by providing a limiter to a field current control circuit while considering the increment of resistance of the brake resistor. CONSTITUTION:Field current 1f is compared with a field current pattern 1f0 corresponding to a speed (v) in a comparator 12, which provides a differential output DELTAif1 to a comparator 15. On the other hand, an armature current (ia) is compared with an armature current pattern (ia0) corresponding to the speed (v) in a comparator 14, which provides a differential output DELTAia1 to the comparator 15. The comparator 15 compares the differential outputs DELTAif<1> and DELTAia1 and provides a differential output DELTAif2 to a comparator 18. A field current limiter generator 17 outputs a limiter signal DELTAifm corresponding to the speed (v). The comparator 18 limits the differential output DELTAif2 below the limiter signal DELTAifm and provides a phase shift angle command alphaF to a phase shifter 16. By such arrangement, increase of the size of a brake resistor can be suppressed.

Description

DETAILED DESCRIPTION OF THE INVENTION OBJECTS OF THE INVENTION (Industrial Field of Application) The present invention relates to a dynamic brake control device for an electric vehicle that separately excites the field power of a main motor.

(Prior art) An armature circuit in which a resistor 4 is connected in parallel with the armature winding 1 of a driving DC motor, and a field winding 9 in series with an AC/DC power converter 6 that controls the power of the field winding. Fig. 2 shows an example of the main circuit of a separately excited electric vehicle equipped with an independent field circuit connected to the

When applying a two-generation brake using the main circuit configuration example shown in FIG. 2, the armature current 1aa and field current 1fo are controlled with the characteristics shown in FIG. 3 to obtain the required braking force BE. This braking force BE is obtained by constant power control between speeds A and B, and constant control of the field current to the maximum value between speeds B and C. FIG. 4 shows the configuration of a conventional power generation brake control section.

In FIG. 4, armature current detector 2. The field current detector 8 is the same as that shown in FIG. In this configuration, a field current pattern generator 11 commands a field current if corresponding to the field current if obtained by the field current detector 8 and the speed V.
The comparator 12 compares the reference current ife of , and the difference output ΔAft is input to the comparator 15 . On the other hand, an armature current pattern generator 1 commands an armature current i6 corresponding to the armature current 18 obtained by the armature current detector 2 and the speed V.
30 reference currents 1aa are compared by a comparator 14, and the difference output Δlax is input to a comparator 15. These respective difference outputs Δia□ and ΔifY are compared in a comparator 15, and the difference output Δitz is used in a field phase shifter 16 that controls the thyristor gate phase angle command αF of the field power converter 6 shown in FIG. is input.

Therefore, the field power converter 6 is controlled so as to obtain each reference armature current 1aa*field current 1fa, so that the target braking force BE can be obtained according to the speed.

(Problem to be Solved by the Invention) In such a dynamic brake, the armature current ia between speeds A and B is controlled to be the maximum constant current, so
The heat capacity of the brake resistor 4 is determined by this current value. If balanced operation is performed at a certain speed in this speed range (A-8), the maximum current will flow through the brake resistor for a long time, and the temperature of the brake resistor will be the maximum allowable value of the resistor. The temperature rises to near the same temperature. Generally speaking, in the case of electric vehicles, it is common knowledge to determine the heat capacity of the brake resistor and to downsize the resistor configuration so that the temperature of the brake resistor reaches close to the maximum allowable value when this maximum current is applied continuously. This is the technology of When this brake current is continuously applied, it is a common phenomenon that the resistance value increases as the temperature of the brake resistor increases. Therefore, in the prior art, when the armature current 18o is controlled to be constant at the maximum value shown in FIG. The field current is increased to compensate for this decrease, the induced voltage of the motor is increased, and the armature current is controlled to become the reference value.

As a result, as shown in the following equation (2), the brake resistor is loaded with excessive power and applies excessive braking force. Generally, the armature current 1ao is determined by the following formula.

As the temperature of the brake resistor increases, the resistance value increases by R. Therefore, in order to keep iao at a constant value, it is necessary to control i to φ1. As a result, the power consumption of the resistor PR□, the brake force BE engineering is Pv=ia:X (Re+ΔR), BEacigXk
φ, (kφ1>kφo) −...■, and each exceeds the reference value.

As mentioned above, the resistor is connected to the reference maximum power (=i xR
Since the heat capacity is determined by a), if such control is used, it will lead to excessive power consumption and damage to the resistor itself.Also, if the resistor is configured with a heat capacity commensurate with this power, one device This has the disadvantage of increasing the external size and increasing cost.

Also, it will apply more braking force than necessary, so
When applying a braking force close to the adhesion limit, there is a drawback that it may cause skidding.

In the present invention, considering the drawbacks of the prior art, each current l
The control of a, The present invention provides a brake control device that achieves the following.

[Structure of the invention]

(Means for solving the problem) In order to achieve this objective, only between speed A and B where the maximum brake current is controlled, the increase in resistance value ΔR accompanying this current is taken into consideration when adjusting the field current if. The control device is configured with a limiter. In other words, in equations ■ and ■, kφ, = φ
6 to F71111- is set as a limit for the i1 pattern.

(Function) As a result, when the resistance value increases by ΔR, the armature current ia
The reference values for both the power PR and the brake power BE can be obtained from equation 0.

(Embodiment) FIG. 1 shows a specific configuration of a control section according to an embodiment of the present invention. The main circuit configuration is the same as the prior art shown in FIG. In FIG. 1, the difference from the prior art is that a field current limiter generator 17 and a comparator 18 are provided. With this configuration, the control system for Δalfa, which is the input signal of the field phase shifter 16, is
Same as the figure. In other words, the limiter signal Δlf from the field current limiter generator is
m is compared by a comparator 18, and the phase angle command αF of the field phase shifter is controlled so that Δ10 does not exceed Δlfm.

〔Effect of the invention〕

According to the present invention, the required braking power and braking force can be secured without changing a part of the control unit, that is, without significantly changing the brake resistor, which is the main circuit equipment, and the increase in resistor equipment can be suppressed. Therefore, it is possible to provide a power generation brake control device that is cost-reduced.

[Brief explanation of the drawing]

FIG. 1 is a control block diagram showing one embodiment of the present invention, and FIG.
Figure 3 is a diagram showing the configuration of a dynamic brake circuit; Figure 3 is a diagram showing the relationship between armature current, field current, and braking force with respect to the speed at which the required braking performance is achieved; Figure 4 is a control block diagram showing the configuration of a conventional device. It is. 1... Main motor armature winding 2... Armature current detector 4... Brake resistor 5
... Field AC/DC power converter 8... Field current detector 9... Main motor field winding 1
1... Field current pattern generator 12, 14.15.18... Comparator 13... Armature current pattern generator 16... Field phase shifter 17... Field current limiter generation Agent Patent Attorney Nori Ken Yudo Daishimaru Ken Figure 1 S2 Figure 3 L Figure 4

Claims (1)

[Claims] An armature circuit in which a brake resistor is connected in parallel with the armature winding of a driving DC motor, a field circuit in which an AC/DC power converter is connected in series with the field winding of the motor, and an independent dynamic brake circuit. In the AC electric vehicle, there is provided a means for detecting the field current of the electric motor, a function generating means for generating a function of the speed of the electric vehicle and the field current determined from the braking force of the electric motor, and a function generating means for generating a function of the field current and the speed of the electric vehicle determined from the braking force of the electric motor. 1. A power generation brake control device for an electric vehicle, comprising a function generating means for multiplying a field current value for a current speed by a constant coefficient determined from a power limit value of the brake resistor.