SE416435B - Traction - Google Patents

Description

The invention will be described in more detail below in connection with the accompanying figures 1-3. Fig. 1 shows an example of a traction equipment according to the invention. Fig. 2 shows an embodiment in which the stationary inductor axes in Fig. 1 are arranged. the vehicle. Fig. 5 shows an embodiment in which a transformer for adjusting the charging voltage is arranged on the vehicle.

Figure 1 shows a vehicle F (the units within the dashed box), which may be a battery-powered electric truck, electric car or the like. The vehicle has a drive motor M, which is a three-phase asynchronous motor. and an accumulator battery B. * A three-phase inverter VR has its two DC connections connected to the battery B and its AC connections connected to the motor M via a two-position electrical switch SW.

The inverter is self-commutated and can thus, independently, generate a three-phase gear shift. The inverter is of a per se known type and consists of a bridge coupling of six thyristors T1-T6 provided with extinguishing means.

Each thyristor is provided with a feedback valve, and these consist of diodes 131-136. The inverter has a control pulse device SPI) which emits control pulses to the thyristors and their extinguishing means in such a way that a three-phase alternating voltage is obtained at the output terminals R, S, T of the inverter.

During normal operation of the vehicle, the control pulse device controls the inverter so that the frequency and amplitude of the alternating voltage is variable for controlling the motor.

For example, the control pulse device may comprise a voltage controlled oscillator for controlling the frequency, and the amplitude of the output AC voltage is suitably controlled (for example by pulse width modulation) so that its amplitude is proportional to the frequency. The function of such an inverter and its structure and control circuits are previously well known. During normal operation, the switch SW is in the position shown in full in the figure and the battery B feeds the motor M via the inverter. By varying the frequency of the inverter, the lag and torque of the motor are affected. If the inverter frequency is lowered then. that the lag becomes negative, the engine returns power to the battery and regenerative braking is obtained. The control circuits and control means used in normal operation are previously well known and therefore not shown in more detail in the figure.

To charge the vehicle's battery, the switch SW ° is set in its position shown in the figure, whereby the motor is disconnected from the inverter and the latter is connected to the input device AM arranged in the vehicle. The socket AM is connected for charging the battery with the stationary socket Am.

The AC power source for charging the battery consists of a three-phase transformer TB. with connections BN, SN and TN for permanent connection to a 10 15 20 25 30 35 7902890-7 alternating voltage network. The transformer-n transforms the mains voltage to a level suitable for charging the battery, eg 50-100 V. The transformer's secondary voltage is supplied to the socket Am via the inductors Lm, L1s and LW 'The socket AM has, like the socket AF1, three main sockets (respectively pins) for connecting main circuits via. switch SW and inductors L1R, L1S and LW to the AC source (transformer TR).

In addition, the devices have three auxiliary sleeves and pins for connecting the phase control circuits of the inverter directly to the AC power source.

During charging, the inverter is controlled as follows. The inverter generates a rigid AC voltage. their terminals R, S, T. The transformer voltage of the transformer TR is also a rigid alternating voltage. These two. voltages are connected to each other via the inductors L1 R, L1S and LW. About the phase difference between the two. the voltages are small, with a good approximation that the flux of active power is proportional to the phase difference between the two voltages and that the flux of reactive power is proportional to the difference between the amplitudes of the two voltage gems. suitably, the amplitude of the inverter voltage is controlled so that it becomes approximately equal to the amplitude of the transformer's TH secondary voltage, which minimizes the reactive power flow between the mains and the inverter. For this purpose, the amplitude control input AC of the inverter control pulse generator SPD is supplied with an analog voltage matching signal SU, which is set by means of a potentiometer P so that the amplitude of the inverter output voltage has the desired value.

To control the phase position of the inverter output voltage, the three phase voltages UR, US and UT are supplied to amplifiers FH, FS and FT, where the voltages are cut as follows. that the amplifiers' voltages WR, IPS and U'T will be eliminated by UR, US and UT phase- and frequency-like square voltages. These signals are applied to the delay lines DR, DS and DT with a controllable time delay.

The outputs SR, SS and ST from the delay circuits are applied to the synchronization input SC of the inverter control pulse, which controls the inverter's output voltages to frequency and phase similarity with the signals SR, SS and ST.

A charge regulator CR of a type known per se emits a setpoint IBC for the charge current. This setpoint can be controlled in a known manner depending on the battery voltage UB (obtained from a voltage divider SD) and depending on the time so that the charging current has the desired course. The actual value IB of the charge current is obtained from a measuring shunt SH and is compared with the setpoint in a JF of the comparator electricity SHF 10 7902860-7. The deviation AI is applied to a current regulator IR with PI characteristic mode, the output signal SP of which is applied to the delay networks DR, DS, DT and controls the delay in them.

The phase position of the control signals SR, SS, ST and thus of the inverter emf will therefore be automatically controlled so that the charging current IB follows the setpoint 150 emitted by the charging controller GR.

The invention offers significant advantages over the prior art. traction system. The vehicle itself offers all the per se known benefits of AC drive of the drive motor. This can be a cheap and practically maintenance-free synchronous motor. The control of the motor is done with the help of the inverter smoothly and quickly and with low losses. The vehicle can be braked regeneratively, which has been shown to give a significant increase in mileage at a given battery capacity or, conversely, a significant decrease in battery size at a given mileage.

The additions required for a vehicle according to the invention consist of the switch SW 'and of the control etchers for charging charged outside the inverter shown in the figure. The switch SW can, since it only needs to be operated in the de-energized state, be simple and cheap. The control circuits can consist of simple additions to the control equipment of the vehicle anyway. has. Therefore, neither the switch nor the control circuits cause any significant increase in the price or weight of the vehicle.

On the other hand, a very large simplification of the stationary charging equipment is obtained. This basically consists of only a single transformer. If several vehicles are to be able to be charged simultaneously, the transformer only needs to be equipped with several sockets. Another such device AFZ is shown in the figure. It's the same as the device Am. Its main louvers are connected via the inductor axis LZR, 1.28 and D21, (and its auxiliary sockets directly) to the secondary side of the transformer TR. The sockets can be located in different places within, for example, a factory area and be connected to a transformer arranged in a suitable place.

On. due to the total power output of the transformer, the type power of the transformer may be lower than the sum of the type effects of the terminals. If an alternator of a suitable size for the battery charge is already available, the transformer can be completely dispensed with and the stationary equipment then consists only of the sockets and their inductors.

The invention thus offers a very significant saving compared to previously known traction systems. It has been described above how the invention can be applied to an electric truck or electric car, but the invention can just as well be used with other types of electric vehicles.

A traction equipment according to the invention may consist of one or more vehicles and possibly also comprise the stationary equipment for charging the vehicles' batteries.

In the example described above, the motor fed from the battery via the inverter is a propulsion motor for the vehicle, but alternatively the motor can be a drive motor for, for example, the lifting movement of a forklift truck.

The battery charging control system described above can be designed in a large number of other ways within the scope of the invention. For example, instead of the simple control of the inverter supply shown, a closed regulator can be provided which regulates the inverter supply or the reactive power flow to the desired value.

Likewise, of course, the inverter itself can be designed in a large number of other ways than those shown above.

The control of the charging current can be performed on. other than those shown above. For example, the charging current can be controlled only after a time program and the sensing of the battery hum can then be eliminated.

It has been described above how the vehicle's battery is charged from a three-phase AC mains. Alternatively, the battery charge can be done from a single-phase veocel voltage network. The inverter is then operated during charging as a single-phase inverter, using only two of the inverter's three phase groups. The alternating current terminals of these two phase groups, eg R and S, are then connected to the AC mains via a single-phase connector. An inductor (eg L1R) is required only in one of the two phase lines.

Fig. 2 shows a traction equipment which corresponds to that shown in Fig. 1, but with the exception that the inductors Lm, L1S, LW are arranged on the vehicle between the input device AM and the switch SW. The voltages UR, U, UT for phase control of the inverter can then be taken out between the inductors and the socket. The sockets and inlets are thus significantly simplified, as no auxiliary nozzles / pins are needed to transmit the voltages UR, US, UT. Furthermore, as in Fig. 1, there is not a set of inductors at each socket, but only one on. vehicle inductor set. -1 7902800-7 10 15 20 25 30 55 6 Fig. 5 shows the hmm transformer-n TR can be placed on. the vehicle F. The sockets can then. connected to an existing AC network, such as an ordinary 580 V three-phase consumption network. The stationary. the part of the traction equipment then remains. only of conventional sockets A111, Am, AFB, which can be easily and cheaply placed in the desired number and on. desired places within, for example, a factory area. Often, sockets of this type are already arranged on. suitable places for charging vehicles. This embodiment provides, at no or low cost for the stationary part, maximum flexibility when it comes to charging an arbitrary number of vehicles in arbitrary locations.

It has been described above how the mains AC voltage (UR, US, UT) is sensed and used as a reference for controlling the phase position of the AC voltage and thus the flow of active power (charging current). It is previously known to control a converter by means of a freely oscillating oscillator with controllable frequency which (possibly via auxiliary circuits) emits control pulses to the valves of the converter. If the inverter in the vehicle has or is equipped with such an oscillator, it can be used to control the inverter even during the charging process. The difference between, for example, the setpoint and actual values of the charging current is then arranged to affect the frequency of the oscillator and thus its phase position, whereby a closed control system is formed which controls the actual value of the charging current in accordance with its setpoint. The sensing of the mains voltage UR, US, UT then shown in Figs. 1-3 then becomes. superfluous, as well as the auxiliary sleeves / pins shown in Fig. 1 on the inlets and outlets AM, Am, Am.

A vehicle with an inverter and a drive motor M has been described above. The invention can of course also be applied to. vehicles with several drive motors, for example one for each wheel, which are fed by a common inverter or by separate inverters. The inverter (or one or more of the inverters) can then. on. the method described above can be used to charge the vehicle's battery.

In oral vehicles, a contactor is often required to disconnect the supply voltage to the motor. This contacts can then be designed as a switch and used as the switch SW shown in Figs. 1-5.

In Fig. 3, the transformer is arranged on. the vehicle. The transformer can then be designed so that its leakage inductance is so high that: The inductors Dm, D18 and Lu, can be eliminated. The same can be done with the embodiments. according to Figs. 1 and 2 if only one stationary socket, eg Am, is provided for charging the vehicle.

Claims (9)

7902800-7 The embodiments according to Figs. 1 and 2 can be modified as follows. that part of the required inductance is arranged in the vehicle and the rest in series with the respective sockets. CLAIMS 1. Traction equipment comprising a vehicle with at least one electric motor and with an accumulator battery (IB) for supplying the motor via an inverter (VR), the battery being arranged for charging from a stationary power source, characterized in that the vehicle is provided with the coupling means (SW) for connecting the motor to the AC side of the inverter during operation of the vehicle and for disconnecting the motor from the AC side of the inverter while charging the battery, with means (SW, for connecting the AC side of the inverter to a stationary AC power source) TR) for charging the battery via the inverter and with control means (CR, JF, IR, FR-F, IDR-ID, P) for controlling the inverter and thus the charging current while charging the battery. 2. Traction equipment according to claim 1, characterized in that the inverter is a self-co-mutated inverter and that the control means comprise means (DR, DS, DT) for controlling the phase position of the inverter voltage relative to the AC voltage source (TR). voltage. 5. Traction equipment according to patent claim 2, characterized in that voltage control means (P, SPD) are arranged for controlling the output voltage of the inverter so that the flow of reactive power between the inverter and the AC voltage source during charging of the battery is minimized. 4. Traction equipment according to claim 1, characterized in that the stationary alternating current source (TR) is provided with at least one connecting means (Am, A132) for connecting the inverter in a vehicle for charging the vehicle battery. 5. A tralionic equipment according to claim 4, characterized in that the alternating voltage source comprises a transformer (TR) having a primary side arranged for connection to an alternating voltage network and having a secondary winding connected to said connecting means; (Am, 6. Traction equipment according to claim 1, characterized in that it comprises a transformer (TR) arranged on the vehicle (F) between the connection means of the vehicle and the inverter. u v 79023ÛG ~ 7 7. characterized in that the alternating voltage source consists of an ordinary low-voltage network. Tralchion equipment according to patent lcav 6, B. Traction equipment according to claim 4, characterized in that the alternating voltage source: comprises an inductor coupling arranged in series with each connecting member (L1 R-L fl, Left-LW). 9. Traction equipment according to claim 1, characterized in that it comprises an inductor coupling (L1R-L1T) arranged on the vehicle (F) between the connecting means (AM) and the inverter (VR).