电动汽车自动变速器设计 外文文献

1. Introduction
efficient 'feedback' control approach is taken. Concluding remarks on implementation are then made in Section 8.
2. The drive train model
ia(Rb + R°) = Vb -- Kfirtoot(n).
(6) (7)
and
K fi:i,
r.
t(n)~ls(n)
Equations (6), (7) [and (14)], and column two in Table 1 relate the armature and field currents to the torque at the wheels Ta, to the speed of the vehicle (which is determined by toa) and to the engaged gear n. In practice the speed of the vehicle co° is a state variable and its predetermined, so that the vehicle is actually controlled by the driver by adjusting the field current i: (via the accelerator) and by engaging the ('correct') gear n (in a manualdrive vehicle). Then, since the armature current is determined by (6), one has [in view of (7)] for the torque
TrtE National Electrical Engineering Research Institute of the CSIR, Pretoria, is engaged in the design of a battery powered electric car equipped with a gearbox. Under consideration is an experimental electric vehicle (Welz and Van Niekerk, 1979), which has a drive train that consists of a field-controlled d.c. traction motor (the field voltage of which is controlled by the driver via the accelerator) driving the input shaft, connected to the output shaft via a conventional automotive clutch and gearbox. Although in an electrically powered vehicle it is unconventional to use a gearbox instead of a chopper in the armature circuit Ilor direct control of the armature current: see Walz (1973); Bader and Plust (1973); Kahlen and Weigel (1973); Wagner (1973)), such a design was considered in Welz and Van Niekerk (1979) to be an advantage from the point of view of energy efficiency, and also for other reasons. Thus, in Pachter (1981) the specific problem of gearbox synchronization was considered (once the required gear change is known); namely the synthesizing of a feedback controller which controls the electric motor while the gearbox is disengaged (via the clutch) so as to synchronize the speed of the input (motor) and output (wheel) shafts prior to gear engagement, thereby achieving gearbox synchronization. It was then natural to consider a feedback controller for the field voltage, the input data being motor speed and field current. In this paper an additional step is taken and the design is discussed of the automatic gearbox controller for the vehicle, i.e. the synthesis is discussed of a control policy for automatic gear shift for instantaneous manoeuvrability or efficiency maximization in the drive system. Thus, we now add to the design in Pachter (1981) an outer control loop for the gearbox wherein the optimal required gear change is first to be decided on by the control logic. Specifically, Section 2 deals with a simplified quasi-stationary model of the drive train of the electric vehicle, and Section 3 contains a discussion of the technological constraints. The formulae for the losses in the drive train are given in Section 4, while the control model for the vehicle is described in Section 5. Section 6 contains the synthesis of the 'feedback' strategy for an automatic gearbox which strives to maximize the instantaneous manoeuvrability of the vehicle, while in Section 7 an energy-
Automatica. Vol. 19, No. 5. pp. 543 549. 1983
Printed in
I.Jreat Britain
0005-1098/83 $3.00 + 0.00 Pergamon Press Ltd. © 1983 International Federation of Automatic Control
Abstract--A quasi-stationary control model is developed of an electric vehicle design incorporating a drive train that includes a field-controlled d.c. motor and a gearbox. Optimal gear change strategies (in the form of feedback control laws) are then synthesized; in particular, feedback strategies that maximize the instantaneous energetic efficiency of the drive train.
7", = t~fift(nFlz(n~.
*Received 21 July 1981; revised 6 September 1982; revised 24 January 1983. The original version of this paper was not presented at any IFAC meeting. This paper was recommended for publication in revised form by associate editor T. Ba~ar under the direction of editor H. Kwakernaak. "l'National Research Institute for Mathematical Sciences, Council for Scientific and Industrial Research (CSIR), P.O. Box 395, Pretoria, Republic of South Africa. 543
to, = to°t(n)
(1)
Leabharlann Baidu
here t(n) is the transmission ratio of the gearbox when the nth gear is engaged; its values are given in the second column of Table 1
i°(Rb + R , ) = Vb - e e = K / i f tom
Brief Paper
Guidelines For Automatic Gearbox Design For an Electrically Propelled Vehicle*
M. PACHTER?
Key Words--Automatic gearbox; automatic transmission.
(2) (3)
where the motor constant (in the correct units) is
T m = K / i f i,
K/= 0.098
(4)
(5)
t/g(n) ~= to°To tomTm
where n8 is the gearbox efficiency factor and it is a known function ofthe engaged gear n [see equation (14)]. Thus, in view of (1)-(5)
The model shown in Fig. 1 for the drive train of the electric vehicle is considered (Pacheter, 1981). In Fig. 1, Vb = 144 V is the battery voltage; e(V) is the back electromotive force of the traction motor; i, and i f (A) are the armature circuit and field circuit currents respectively; Rb = 0.075 [l, R, = 0.060 fl and R f = 10 II are the battery, armature circuit and field circuit resistances, respectively; 7",, and T, (N m) are the motor torque and the torque at the wheels (or differential), respectively; and to,, and too (s -1) are the motor speed and the wheel speed, respectively. The equations of motion are