DE102017119271A1 - Method for limiting an air gap torque of a synchronous machine in the event of a fault - Google Patents

Abstract

The invention relates to a method for limiting an air gap torque of a synchronous machine (6) which is connected to the supply of alternating current in an inverter (2), wherein the inverter (2) comprises an inverter having a plurality of power transistors (4a, 4b) connected in half bridge circuits A controller (7) for controlling the power transistors, and comprising a DC section (3) connected to the inverter, wherein the DC section (3) is connected to a battery (1) and a contactor (9) is turned on in the connection between the inverter and the battery is. In order to avoid an air-gap torque in the event of a fault, a switching signal for opening the contactor (9) is generated by means of the control (7) or monitoring control (8) monitoring a proper operation of the control (7).

Description

The invention relates to a method for limiting an air gap torque of a synchronous machine in the event of a fault according to the preamble of patent claim 1.

According to the state of the art, permanent magnet-excited synchronous machines are generally known which are supplied with alternating current by means of a direct current source, for example a battery, with the interposition of an inverter and are consequently driven.

In particular, when using such a synchronous machine for driving a vehicle, it is necessary for safety reasons, in the event of a malfunction to slow down a rotational movement of the synchronous machine as little as possible. For this purpose, an inverter provided in the inverter is operated at a low speed of the synchronous machine, for example, less than 5,000 revolutions per minute (= UPM) in the so-called "pulse off" operation, in which all power semiconductors are placed in an open switching state. In the "pulse off" mode, no air-gap torque is generated at the low speeds mentioned, which counteracts the rotational movement of the synchronous machine and slows it down.

At high speeds greater than, for example, 5,000 rpm, the torque produced by the "pulse off" operation increases rapidly and causes undesired slowing of the synchronous machine. Above such speeds, the "pulse off" operation is turned off and instead generates a so-called "active short circuit" in which the first power transistors of the half-bridge circuits connected to a first pole of the DC section open and the second power transistors connected to a second pole of the DC section getting closed. The switching state of the "active short circuit" causes, especially at speeds in the range of, for example, 0 to 2,500 rpm, an air gap torque, which hardly counteracts the rotational movement of the synchronous machine.

The prior art modes of avoiding air gap torque of a synchronous machine in the event of a fault will only work properly if both the power semiconductors and the power semiconductor control controller are functioning properly. In particular, in the case of failure of one or more power semiconductors, the inverter u. U. no longer be placed in a switching state, which allows a "pulse off" operation or an "active short circuit". In conventional methods, it is therefore not possible to reliably and reliably guarantee unrestrained rotational movement of a synchronous machine in all cases of an accident.

The object of the invention is to eliminate the disadvantages of the prior art. In particular, an improved method for avoiding an air-gap torque of a synchronous machine in the event of a fault is to be specified. According to a further object of the invention, the method should be as simple and inexpensive to carry out.

This object is solved by the features of patent claim 1. Advantageous embodiments of the invention will become apparent from the features of the dependent claims.

According to the invention, it is proposed that in the case of failure by means of the controller or a monitoring operation monitoring the proper operation of the control, a switching signal for opening the contactor is generated.

According to the invention, in the event of a fault in the region of the DC section of the inverter or a DC source connected to the inverter, the circuit is interrupted by opening the contactor, an intermediate circuit voltage rises to a value of a rectified electromotive force. As a result, the diodes of the half-bridge circuits block. There is no rotation of the synchronous machine counteracting air gap torque generated.

The proposed method can be carried out without great expenditure on equipment. To interrupt the supply of the inverter with direct current, a contactor usually provided on the vehicle side may be used. In order to carry out the method in such a case, it is only necessary to effect a suitable activation of the contactor in the event of a fault.

The switching signal can be generated by the controller in the event of failure or malfunction of one or more power transistors. In case of failure or malfunction of the controller, the switching signal is advantageously generated by means of a monitoring controller which monitors the function of the controller.

The contactor proposed according to the invention may be part of the inverter. In this case, the inverter itself is suitable as a structural unit for carrying out the method according to the invention and prepared.

According to a further embodiment, the contactor and the monitoring control can also be provided on the vehicle side. The monitoring control can be in this case, for example, part of a vehicle-mounted vehicle control unit. The switching signal for opening the contactor is generated in this case in case of a disturbance of data communication between the monitoring controller and the controller by means of the monitoring controller. For example, in the event of an interruption of the data communication between the monitoring controller and the controller, the switching signal is generated and thus the contactor can be opened.

According to a further embodiment, in the case of failure or malfunction of the controller in the inverter, an "active short circuit" can be generated by opening first power transistors connected to a first pole of the DC section and closing second power transistors connected to a second pole of the DC section. The generation of the "active short circuit" is expediently carried out by means of the monitoring control.

In the aforementioned embodiment, the switching signal can be generated when a current flowing in the short circuit exceeds a predetermined threshold. In this case, the current flowing in the short circuit is expediently determined from the sum of the individual currents flowing over each of the phases.

A second aspect of the invention relates to a computer program product comprising computer readable instructions on a computer readable program storage medium, the computer readable instructions causing at least one computer to perform the method of the invention when the instructions are read and executed by the computer. The program storage medium may be, for example, a hard disk, a CD-ROM, a floppy disk, a flash memory, or the like.

The control and / or the monitoring control is usually a microprocessor with a memory unit in which a computer program for monitoring and controlling a plurality of functions is stored. After a particularly simple and inexpensive feasible embodiment of the method, it is only necessary to supplement the computer program contained in the control and / or monitoring control to the computer program product according to the invention. When using a contactor provided on the vehicle, the method can therefore already be carried out by changing and / or supplementing the computer program contained in the control and / or monitoring control. The computer program product according to the invention can of course be part of a comprehensive computer program which also monitors or controls other functions of the inverter and / or a device provided with the inverter.

According to one embodiment, the computer program product according to the invention is also part of the monitoring control for monitoring the proper operation of the controller. The monitoring control is in this case part of the inverter.

Another aspect of the invention relates to an electric vehicle having a synchronous machine, an inverter for supplying a permanent magnet synchronous machine with AC, comprising an inverter having a plurality of power transistors connected in half-bridge circuits, a controller for controlling the power transistors, a DC section connected to the inverter, the DC section having a battery is connected, and in the connection between the inverter and the battery, a contactor is turned on, and connected to the contactor and the control monitoring control for monitoring the proper operation of the controller. In this case, the control and the monitoring control comprise the computer program product. In the proposed electric vehicle, the contactor, the battery and the monitoring control are provided on the vehicle side, d. H. the inverter forms a separate component, which is connected at least to the monitoring control.

The synchronous machine is preferably a permanent magnet synchronous machine.

The computer program product has the function of causing a switching signal to open the contactor in the presence of certain predetermined events. As far as the computer program product is part of the control, such an event may be, for example, a failure or failure of one or more power transistors. If the computer program is part of the monitoring control, a switching signal can be generated, for example, when the data communication with the controller is interrupted. The computer program product can thus be designed differently with regard to the events for triggering the switching signal. The computer program product may comprise a plurality of sub-computer programs, which on the one hand are part of the control and, on the other hand, are part of the monitoring control.

• 1 den Schaltzustand eines Inverters im „Puls-off“-Betrieb,
• 2 das Luftspaltdrehmoment über der Drehzahl beim „Puls-off“-Betrieb,
• 3 den Schaltzustand eines Inverters beim „aktiven Kurzschluss“,
• 4 das Luftspaltdrehmoment über der Drehzahl beim „aktiven Kurzschluss“ und
• 5 ein erfindungsgemäßes Schaltbeispiel.

The invention will be explained in more detail with reference to the drawings. Show it:

• 1 the switching state of an inverter in "pulse-off" mode,
• 2 air-gap torque versus speed during "pulse-off"operation;
• 3 the switching state of an inverter during the "active short circuit",
• 4 the air gap torque over the speed at the "active short circuit" and
• 5 an inventive switching example.

In the figures, 1, 3 and 5, a battery provided on the vehicle side with the reference numeral 1 designated. A generally by the reference numeral 2 designated inverter has a DC section 3 and a plurality of power transistors connected in half-bridge circuits 4a and 4b on. With the reference numerals 5a and 5b are parallel to the power transistors 4a . 4b designated diodes designated. inverter 2 is the output side with a generally with the reference drawing 6 designated synchronous machine, in particular a permanent magnet synchronous machine, connected.

In the in the 1 and 2 shown "pulse-off" operation are all power transistors 4a and 4b , which may be IGBTs, for example. In response to a speed of the synchronous machine, a rectified electromotive force, which is greater than one in the intermediate circuit or DC section, is formed during "pulse-off" operation 3 is applied DC voltage. As a result, a direct current is excited, which generates a regenerative power and consequently a braking torque. In 2 are different braking torque curves depending on the voltage of the battery 1 shown. It can be seen that significant brake or air-gap torques do not form in the region of more than 5,000 rpm from speeds above.

3 and 4 give the operating state in the so-called "active short circuit" again. In this case, the first power transistors connected to the one pole are 4a open, with the other pole of the battery 1 connected second power transistors 4b are closed. As in particular from 4 can be seen, formed at the "active short circuit" even at low speeds, a significant air gap torque. - When operating the "active short circuit", it is imperative that the power transistors operate and that in 3 shown switching state is switchable.

5 shows a switching example according to the invention. With the reference number 7 is a control called, with which the power transistors 4a . 4b are controllable. The control 7 is with a vehicle-mounted monitoring control 8th connected. With the reference number 9 is a contactor, which with the monitoring control 8th is switchable.

According to the method of the invention are in the event of a fault by means of the controller 7 the first power transistors 4a opened and the second power transistors 4b closed, so that the switching state of the "active short circuit" results. At the same time the controller transmits 7 to the monitoring controller 8th a signal, whereby by means of the monitoring control 8th the contactor 9 is opened. As a result, the circuit becomes the battery 1 interrupted. The formation of a decelerating air gap torque is thus safely and reliably avoided.

According to a variant of the invention shown, it is also possible that by means of the monitoring control 8th independently the contactor 9 is opened, for example, when a signal transmission between the controller 7 and the monitoring controller 8th is disturbed.

According to a further variant of the invention, it is also conceivable that by means of the controller 7 immediately the switching signal to open the contactor 9 is produced.

The proposed method is particularly safe and reliable. Even if the switching state of the "active short circuit" due to a malfunction of a power transistor 4a . 4b can not be realized, because of the simultaneous opening of the contactor 9 also avoided in this case, the formation of an undesirable air gap torque. When opening the contactor 9 an intermediate circuit voltage increases in the DC section 3 electromotive force rectified to a value. As a result, the diodes lock up 5a . 5b , no longer conduct current, thereby avoiding the formation of an air gap torque.

LIST OF REFERENCE NUMBERS

1

battery

2

inverter

3

DC Section

4a

first circuit breaker

4b

second circuit breaker

5a

first diode

5b

second diode

6

synchronous machine

7

control

8th

supervisory control

9

contactor

Claims (12)

Method for limiting an air-gap torque of a synchronous machine (6) in the event of a fault, wherein the synchronous machine (6) is connected to an inverter (2) for supplying alternating current, wherein the inverter (2) comprises an inverter having a plurality of power transistors (4a) connected in half-bridge circuits 4b), a controller (7) for controlling the power transistors (4a, 4b), and a DC section (3) connected to the inverter, wherein the DC section (3) is connected to a battery (1) and connected to the connection between the Inverter and the battery (1) a contactor (9) is switched on, characterized in that in case of failure by the controller (7) or a proper operation of the controller (7) monitoring monitoring control (8) a switching signal to open the contactor (9) is generated. Method according to Claim 1 wherein the switching signal is generated by the controller (7) in the event of failure or malfunction of one or more power transistors (4a, 4b). Method according to one of the preceding claims, wherein the switching signal is generated by means of the monitoring control (8) in case of failure or malfunction of the controller (7). Method according to one of the preceding claims, wherein the contactor (9) is part of the inverter (2). Method according to one of the preceding claims, wherein the contactor (9) and the monitoring control (8) are provided on the vehicle side, and wherein the switching signal for opening the contactor (9) in the event of a malfunction of data communication between the monitoring controller (8) and the controller (7 ) is generated by the monitoring controller (8). Method according to one of the preceding claims, wherein in case of failure or malfunction of the controller (7) in the inverter, an active short circuit is generated by connected to a first pole of the DC section (3) connected first power transistors (4a) open and with a second pole of the DC section (3) connected second power transistors (4b) are closed. Method according to one of the preceding claims, wherein the switching signal is generated when a current flowing in the short circuit exceeds a predetermined threshold. Method according to one of the preceding claims, wherein the current flowing in the short circuit current from the sum of the individual currents flowing over each of the phases is determined. A computer program product comprising computer readable instructions on a computer readable program storage medium, the computer readable instructions causing at least one computer to perform the method of any one of the preceding claims when the instructions are read and executed by the computer. An inverter (2) for supplying AC power to a synchronous machine (6), comprising an inverter having a plurality of power transistors (4a, 4b) connected in half-bridge circuits, a controller (7) for controlling the power transistors (4a, 4b), and one connected to the inverter DC section, wherein the DC section (3) with a battery (1) connectable and in the connection between the inverter and the battery (1) a contactor (9) is turned on, characterized in that the controller after the computer program product Claim 9 includes. Inverter after Claim 10 , one of which is the computer program product Claim 9 comprehensive monitoring control (8) for monitoring a proper operation of the controller (7) is provided. Electric vehicle having a synchronous machine, an inverter (2) for supplying the synchronous machine (6) with alternating current, comprising an inverter having a plurality of power transistors (4a, 4b) connected in half-bridge circuits, a controller (7) for controlling the power transistors (4a, 4b), a DC section (3) connected to the inverter, wherein the DC section (3) is connected to a battery (1) and a contactor (9) is turned on in the connection between the inverter (2) and the battery (1); monitoring controller (8) connected to the contactor (9) and the controller (7) for monitoring the correct operation of the controller, characterized in that the controller (7) and the monitoring controller (8) simulate the computer program product Claim 9 includes.

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