FI100023B - Method and apparatus for using an electric vehicle - Google Patents

Description

, 100023

The present invention relates to a method and apparatus for operating an electric vehicle, and more particularly to operating it in a manner in which the functions required in a high-performance electric vehicle, i.e., a 3-phase AC motor drive motor, a wide voltage and power charging device, The 12 V converter and the compressor controller of the heating and air conditioning unit are integrated into the same unit so as to achieve a cost-effective solution to minimize the complexity and cost of the equipment 10 and to minimize the need for mechanical switches.

The method according to the generally known technique is to implement said functions as separate devices. The procedure results in an unnecessarily complex structure. U.S. Patents 5,291,388 and 5,309,073 also disclose prior art methods for integrating some of said functions into the same entity to minimize complexity. It has not been possible to integrate all these functions in these systems either.

The circuit according to the invention implements all said functions with approximately the same number of power semiconductors, which would already be required for the drive motor drive and charger of a 3-phase AC motor alone as separate units.

An exemplary connection according to the invention for arranging the functions 25 of an electric vehicle is illustrated in the following Figure 1, which shows all the main basic functions arranged according to an embodiment of the invention. The components and their main functions are first listed and then the operation of the connection for different purposes is explained in more detail.

30 Electric machine 1 is in propulsion operation of an electric vehicle. This electric machine is a 3-phase and can be an asynchronous synchronous machine, a permanent magnet synchronous machine, a separately magnetized synchronous machine or a reluctance machine. This electric machine can act as both a motor and a generator in both directions of rotation. The electric machine 1 is controlled by 2 100023 inverter bridges consisting of six electrically controlled switches 2, which also have a resistance-connected diode 2 '. These switches 2 can be transistors, fetters, IGBTs or MCTs, or any other switches operating in a similar manner. The phase currents of the electric machine 1 are measured by two current sensors 3.

5 The DC filtering of the inverter bridge is performed by a capacitor 4, which forms a DC voltage circuit of the inverter bridge 2.

The current from the energy source of the electric vehicle, in particular the battery, to the device is measured, if desired, by a current sensor 5. This current sensor is not essential for the function of the invention, it can be located at different points in the circuit or even completely absent. The current from the energy source can be connected to or disconnected from the inverter bridge by a mechanical power switch 6. The current from the energy source is controlled by fuse 7. This fuse can be a wire fuse, a semiconductor fuse or any other component suitable for overcurrent protection. The fuse 7 is not critical to the operation of this invention, so it may be located at a different point in the circuit, or even completely missing.

The fuse 8 acts as a protection for the circuit of the second converter and is otherwise subject to the same considerations as the fuse 7. The switch 9 consists of two resistively connected 20 electrically controlled components. The switch 9 can be, for example, a relay contact, a thyristor, a triac or any other similar switch. The choke 10 acts as a choke for the charge switch. Diode 11 separates the DC voltage of the inverter circuit and the DC voltage of the second converter so that the DC voltage of the second converter may be higher than the DC voltage of the inverter, but current may flow from the DC voltage circuit of the inverter to the DC circuit of the second converter.

The two capacitors 13, 13 'and the resistor 14, 14' form a filter of the DC voltage circuit of the second converter, as well as an auxiliary voltage level between the DC voltage of the second converter and zero. The two capacitors 13,13 'also participated in generating the above-mentioned auxiliary voltage level in addition to acting on the energy reserve. A resistor can be placed to limit the current flowing between the auxiliary voltage levels formed by the capacitor pair 13,13 'or possibly two pairs of capacitors, if these auxiliary voltage levels are at different potentials. The resistor is not critical to the operation of this invention, but may also be replaced by a short circuit, or omitted altogether. The diode pair 15, 15 'acts as a path for the residual current of the half-bridge breaker transformer 16.

S The switch pair 17,17 'contains two electrically controlled switches with their resistance diodes 17 ". The same considerations apply to these switches as to the inverter bridge switches 2. The switch pair 18, 18' is of the same nature as the switch pair 17, 17 'and the same considerations apply, although the pairs of switches 17, 17 'and 18, 18' may be of different types, the pairs of switches 17, 17 'and 18, 18' together form the above-mentioned second converter 10.

The electric machine 19 is a motor of a heat pump compressor, which can be either a direct current motor or a so-called A 1-phase motor in which, for example, a second phase is formed by means of a capacitor in order to produce a rotating field. Switch 24 is e.g.

15 relay switch for disconnecting the electrical machine 19 from the circuit of the second converter. The 6-pulse bridge 21 acts as a rectifier for a 1-3 phase AC or DC power supply and as a connection unit to the device. This power source may be mains voltage (either 1- or 3-phase), quick charger output (DC or AC), generator or any other suitable power source, either internal or external to the electric vehicle, with a peak voltage higher than the power source of the electric vehicle.

The rectifier bridge 22 acts as a 1-phase or direct current connection unit to the device. In this connection, the supply voltage can be either higher or lower than the voltage of the electric vehicle's energy storage. A choke can also be connected in series with the conductor between the anode of the rectifier bridge 22 and the phase of the inverter unit if the design of the electrical machine used prevents its phase winding from being used as a choke (as is the case, for example, with certain permanent magnetization solutions).

The current sensor 23 measures the charging current in the charging mode, as well as the current of the heat pump compressor motor 19. This current sensor is not critical to the operation of the invention, it may be located at a different point in the circuit, or even be completely absent.

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Switch 24 separates the heat pump from the compressor motor 19 circuit when not in use. The switch can be, for example, a relay.

The system has the following functions: 5 1) Driving mode:

In the driving mode, the electric machine 1 is used for the propulsion operation of an electric vehicle. The inverter bridge switches 2 are controlled by a control unit (not shown) via a microprocessor, suitably pulsed so that the desired electromagnetic state is generated in the electric machine so that the motor operates optimally, producing the desired amount of torque. The microprocessor of the control system is able to directly influence the rotational speed and direction, torque and direction of the electric machine 1 and the efficiency of the electric machine by appropriately changing the pulsation of the inverter bridge switches 2, and measuring phase currents and voltages and other necessary quantities e.g. by means of current sensors 3.

The purpose of the capacitor 4 (which may consist of one or more physical capacitors) is to filter out the voltage spikes caused by the diffuse inductors of the inverter bridge, to act as an energy store and as a filter to assist the actual energy store of the electric vehicle. Capacitor 4 also attenuates the ripple formed in the current of the electric energy store of the electric vehicle due to the pulsation of the inverter bridge and the possible parasitic current requirement of the electric machine. The rectifier bridge 22 is disconnected from its feed source. The switch 25 6 is closed, the propulsion power of which can flow directly from the actual energy storage to the inverter bridge 2 with as little loss as possible.

2) 1-phase charging mode 30 In the 1-phase charging mode, switch 6 is opened, after which the 1-phase charging current is supplied to the rectifier bridge 22. From this, current is conducted to the phase winding of the electric machine 1 and to the inverter bridge. Due to the connection of the circuit, the voltage of the capacitor 4 is at least equal to the peak voltage of the 1-phase charging current. If the voltage of the capacitor 00023 5 rin 4 is lower than the peak voltage of the 1-phase charging current, a current limiting resistor can be added to the circuit, which can be short-circuited after the capacitor 4 is charged to the above voltage. It should be noted that the connection sets quite loose limits for the above-mentioned 1-phase charging current. This current can be either direct current or alternating current 5 up to a frequency of several kilohertz, it can contain harmonics and it can have a voltage peak value at most equal to the voltage resistance of the components of the inverter bridge and at least about 5 volts. Current flows from the DC circuit of the inverter bridge through the diode 11 to the DC circuit of the second converter.

10 The switch 9 is controlled to conduct current from the second converter to the energy storage of the electric vehicle. The switches 2 of the inverter bridge are pulsed so that current flows from the diode bridge 22 to the DC voltage circuit of the inverter bridge. In particular, this can take place by means of the current sensors 3 and the voltage measurement data, the current consumption from the rectifier bridge 22 is adjusted to occur by a power factor 1 (current and voltage in the same phase 15 and of the same shape). In this case, the phase winding of the electric machine 1 and the inverter bridge operate in a so-called step-up circuit breaker connection. As a result, the voltage in the DC circuit of the inverter bridge 2 is practically somewhat higher than the peak value of the 1-phase reverse current voltage.

As already mentioned, instead of or in addition to the phase winding of the electric machine, an inductance can be connected to the circuit between the rectifier bridge 22 and the inverter bridge 2, if the structure of the electric machine does not allow its phase winding to be used as a choke.

The switch pair 18 of the second converter is pulsed so that together with the inductance 25 10 they form a so-called step-down circuit breaker. This makes it possible to adjust the charging current to the energy source of the electric vehicle, even if its voltage is lower than the voltage of the DC voltage circuit of the inverter bridge 2. If the peak value of the 1-phase charging voltage is clearly lower than the voltage of the electric vehicle's energy source, the upper switch 30 of the switch pair 18 of the second converter is controlled completely conductive, and the charging current is regulated entirely by the inverter bridge 2 switches. If the peak value of the 1-phase charging voltage is close to or higher than the voltage of the electric vehicle's power source, the switches of the inverter bridge 2 are controlled so that the DC voltage of the inverter bridge 2 remains constant and 6 100023 charging current is regulated by pulses of the second converter switches 18.

It should be noted that the control modes presented herein are not the only alternatives for achieving similar operation with the apparatus of the invention, and that changes in control modes do not make a substantial difference to the present invention.

During 1-phase charging mode, electric machine 1 cannot be used for propulsion operation.

3) 3-phase charging mode 10 In the 3-phase charging mode, the charging current is connected via a diode bridge 21 to the DC voltage circuit of the second converter. The diode 11 prevents current from flowing to the inverter bridge 2. The capacitors 13 act as filter capacitors and energy stores. Switch 9 is controlled to conduct current from another converter to the energy storage of the electric vehicle. The switch pair 18 is pulsed in the same way as in the 1-phase charging mode, i.e. the so-called

15 in step-down circuit breaker together with inductance 10. In the 3-phase charge mode, the voltage connected to the rectifier bridge 21 can also be a DC voltage just as well as a 1-, 2- or 3-phase voltage at different frequencies. If the charging current is DC, it can also be connected directly to the DC circuit of the second converter past the rectifier bridge 21.

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The peak value of the charging voltage shall be higher than the voltage of the energy source of the electric vehicle, but not more than the maximum permissible voltage of the components of the second converter. If it is desired to use a lower charging voltage, this is possible by connecting an inductance between the rectifier bridge 21 and the DC circuit of the second converter 25, and to use it together with the switch pair 18 of the second converter in a so-called step-up circuit breaker. The 3-phase charging mode is possible simultaneously with the driving mode, so in addition to the external source, the 3-phase charging current can also alternatively come from an internal source of the electric vehicle, such as an internal combustion engine driven generator.

Furthermore, if the electric vehicle has a low voltage energy source, it can be connected via inductance to the DC circuit of another converter, further changing the connection so that instead of the diode 11 a controllable switch is used instead of diode 11, and it is controlled to the closed state. In this case, by means of the switch pair 18 of the second converter, the voltage of the above-mentioned low-voltage energy source can be raised to a level which is most optimal for the operation of the inverter bridge 2 and the propulsion electric machine 1.

5 4) Demolition mode

In the discharge mode, the switch 9 is controlled to conduct from the power source of the electric vehicle in the direction of the second converter. The switch pair 18 is controlled together with the inductance 10 in a so-called step-up circuit breaker, whereby current flows from the energy source of the electric vehicle 10 to the DC circuit of the second converter. The capacitors 13 of the DC voltage circuit of the second converter can be used as an energy store. If the electric vehicle has a low voltage rechargeable energy source, this space can be used to charge the above energy store when the electric machine 1 acts as a generator, when the same changes mentioned in connection with the 3-phase charging mode are implemented.

5) DC converter mode

The switch pair 17 of the second converter, the transformer 16, the diode pair 15,15 'and the capacitors 20 13,13' together form a half-bridge type DC voltage converter. At the center of the capacitors 13, 13 'there is a voltage which is lower than the DC voltage of the second converter, for example half of it. When the switches of the switch pair 17 are alternately pulsed by the transformer, the power can be transferred to the secondary side. On the secondary side, an electric vehicle electrical auxiliary system 25 (normally a 12V system) and, for example, a battery electric vehicle energy storage balancing system are typically fed, where an optional individual battery module in a lower charge state is charged separately, if necessary while driving. The secondary outputs are galvanically isolated from the primary and from each other.

The purpose of the diodes 15,15 'is to stabilize the operation of the DC voltage converter by preventing the voltage at the center of the capacitors 13,13' from drifting away from the set point. The DC converter mode can operate regardless of whether the drive mode, 1-phase charge mode, 3-phase charge mode or discharge mode is simultaneously in use.

6) Heat pump compressor operating mode 5 In this mode, switch 24 is closed to connect the heat pump compressor motor 19 to the circuit. Switch 9 is kept in the closed state in both directions. The switch pair 18 is pulsed so that the current of the heat pump compressor motor is sinusoidal alternating current of the desired frequency and amplitude. The center of the condenser lines 13 and 13 'acts as a second supply point for the heat pump compressor motor 19 10, against which alternating current is generated by means of a pair of switches 18. Due to the additional torque that may be required during the start-up phase of the compressor motor 19, a pair of switches 17 can be used to maintain the center voltage of the capacitors 13 through the primary winding of the transformer 16 and possible resistance. This may be necessary because the instantaneous value of the current drawn by the compressor-15 motor 19 causes the voltage at the center of the capacitors 13 to vary with the AC voltage controlled by the motor 19, which reduces the peak value of the voltage controllable to the motor 19.

In addition, before starting, it is possible to use the discharge mode (point 4) to charge the capacitors 13 to a high voltage just before starting, whereby the energy of the capacitors during start-up ensures a sufficiently high voltage peak for the motor 19 despite the current variation of the capacitor 13.

The resistor limits the current caused by the voltage difference between the centers of the capacitors 13 and the second pair of capacitors when used as such. However, this resistor is not essential for the connection.

Operation of the heat pump compressor motor 19 limits the use of the charging and discharging functions (items 2-4). These functions can be used simultaneously, but in such a way that the charging and unloading functions only work for a short time »! HH l i rl 4 »30 9 100023 by switching the switch 9 at a suitable point to the instantaneous value of the AC voltage applied to the motor 19. In this case, only charging or discharging at low current is possible.

5 Numerous variations of the system can be made.

«The motor of a heat pump compressor can also be a DC motor, in which case the other pole of the motor is connected to either + or voltage instead of the center of the capacitors 13 and the switch pair 18 is pulsed so that the motor current is 10 DC.

The heat pump compressor motor can also be 3-phase, in which case a switch pair similar to a switch pair 18 is added to the connection and the three phase conductors of the compressor motor are connected to the centers of the added switch pair, switch pair 18 and capacitors 15 den 13.

Likewise, the diode bridge 21 can be removed by adding the above-mentioned switch pair and switching the three phases of the 3-phase voltage as well as the connection of the motor of the 3-phase heat pump compressor as described in the previous paragraph.

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Claims (9)

A method for combining the functions of an electric vehicle's electric drive system into a single unit to minimize equipment complexity and component costs in a system comprising an inverter (2) of an electric machine (1) acting as a traction motor. voltage supply of auxiliaries operating at the voltage level, as well as the supply of the heat pump compressor motor (19) and 10 possible resistive auxiliary heaters, two pairs of electrically controlled switches (17,17; 18,18), a pair of capacitors (13,13 '), auxiliary transformer (16), electrically controlled switch (9) for selecting the charging / discharging mode, and a mechanical switch (6), characterized in that the charging and discharging of the traction power supply and the motor (19) of the heat pump compressor are operated at the same time. 1a with a pair of switches (18,18) and that the pair of switches (17,17) used as an inverter of the transformer of the auxiliary electrical system is used to help increase the torque of the motor (19) of the heat pump compressor. A method according to claim 1, characterized in that the energy of the discharge cycles associated with the charging of the traction power source 20 in the pulse charging is stored in a pair of capacitors (13, 13) and then reused in the next charging cycle. Method according to claim 1, characterized in that the discharge operation of the traction power supply charging system is used to increase the starting torque of the heat pump compressor motor by charging a pair of capacitors (13,13) to a high voltage by the traction power supply discharge operation before starting the compressor motor. A method according to claim 1, characterized in that the charging system of the traction power supply is provided with power factor correction. 100023 π Method according to Claim 1, characterized in that the phase windings of the electric machine (1) acting as a traction electric motor are used in the charging state as a choke required for correcting the power factor of the charging current. Method according to one of the preceding claims, characterized in that only one mechanical switch (6) is used in the high-current circuits, which is also used as a main switch for the vehicle. Method according to one of the preceding claims, characterized in that the clutch pairs (17, 17; 18, 18) are used as essential components in all operating modes of the electric vehicle's electric drive system, with the exception of traction motor operation alone. A method according to claim 1, characterized in that the diode (11) 15 is used to enable a higher voltage of the rest of the electrical system from the DC circuit of the inverter (2). Apparatus for operating an electric vehicle in a system comprising at least an electric source, in particular a battery, a motor (1), an electrically controlled inverter bridge (2) motor for controlling the motor and charging means for the traction source and a possible source of various lower voltage devices, characterized in that it has a pair of switches (18, 18) for operating the charging and discharging of the traction power source and the heat pump compressor motor (19) and a pair of switches (17, 17) to act as an inverter for the auxiliary power system 25 transformer and to increase the torque of the heat pump compressor motor (19). 100023