EP2499730A2

EP2499730A2 - Inverter with voltage clamping device

Info

Publication number: EP2499730A2
Application number: EP10774194A
Authority: EP
Inventors: Robert Januschevski; Kai Borntraeger
Original assignee: ZF Friedrichshafen AG
Current assignee: ZF Friedrichshafen AG
Priority date: 2009-11-11
Filing date: 2010-10-29
Publication date: 2012-09-19
Also published as: US20120229068A1; WO2011057900A3; JP2013511247A; CN102598491A; WO2011057900A2; DE102009046617A1

Abstract

The invention relates to an inverter, in particular for suppling energy to a three-phase motor (3) of a motor vehicle. Said inverter comprises a half-bridge (1a, 1b, 1c) for electrically connecting to the three-phase motor (3), characterised in that said half-bridge (1a, 1b, 1c) comprises a short-circuit element (8) which is connected in an electrically conductive manner to an inlet (6b) and an outlet (6c) of a power semi-conductor switch (5a; 5b) of the half-bridge (1a, 1b, 1c), said short-circuit element generating a short circuit in a defined manner between the inlet (6b) and outlet (6c) of the power semi-conductor switch (5a; 5b) in accordance with the voltage value of the voltage applied between an inlet (6b) and outlet (6c) of a power semi-conductor switch (5a; 5b).

Description

inverter

The present invention relates to an inverter according to the preamble of claim 1.

For driving electric machines, inter alia converters are used, the machines being used e.g. by means of a DC source, e.g. a battery, but require one or more AC phases to operate. Such machines, particularly in the automotive driveline art, e.g. Three-phase motors, e.g. permanently or externally excited synchronous motors.

An inverter has e.g. a motor-side inverter or a drive inverter, the DC voltage from e.g. a DC link of the inverter, in particular a DC link with DC link capacitor, converts into an AC voltage of the desired frequency for controlling the direction of rotation and the rotational speed of the three-phase motor to be driven. Such drive inverters are used in particular in motor vehicles, e.g. in electrically powered vehicles or in hybrid-powered vehicles, the three-phase motor e.g. is designed as a vehicle drive motor.

Such vehicle drive motors, in particular permanently excited synchronous motors, usually show the design-related behavior that during operation an increasing with increasing speed counter voltage or internal voltage is induced (pole wheel), at very high speeds in the DC link, in particular by means of freewheeling diodes of (drive) Inverter, is fed or fed back and can cause damage in the inverter or the inverter, the battery, and other components (voltage feedback). In order to avoid this, but still be able to operate the engine at high speeds, in the prior art, therefore, a field weakening is made above the rated speed to avoid such a harmful voltage feedback. Nevertheless, damage to the converter or other components is also possible when using the field weakening, in particular when a motor is operated above the rated speed (field weakening operation), and, for example, a field Weak current can no longer be sustained. The cause may be, for example, a failure of the control electronics.

In order to protect the inverter against harmful voltage feedback in the case of an unintended AC-side (ie emanating from the motor) voltage increase, various protective circuits are proposed in the prior art. Usually, e.g. Power semiconductor switch of the inverter or its motor-side inverter and thus the associated respective motor terminals shorted in case of failure. By short-circuiting via the bridge circuit, it can be prevented that e.g. the DC link capacitor, a battery, the circuit breaker, etc., and thus the inverter are damaged by the induced voltage due to the rotor rotation. However, a weak point of the known arrangements is usually that the short circuit must be actively carried out by a control electronics of the inverter. When the drive electronics fail, there is no protection mechanism against damage caused by the voltage induced in the synchronous machine or motor.

DE 102 51 977 A1 discloses a synchronous motor with inverter, wherein a complex protection device against voltage feedback is connected to the winding phases, wherein the protection device cooperates with the control logic of the inverter for detecting a fault or to protect against voltage feedback. DE 298 13 080 U1 shows a further, connected to the windings of a motor protection against voltage feedback, wherein the protection device in turn has an associated with the control logic electronics for producing the protective function. This system is also complex and expensive to manufacture. DE 198 35 576 A1 discloses a drive system for a permanent-magnet electric motor which contains an operating state detection unit in order to generate a short circuit of the power semiconductor switches by means of a drive arrangement of the inverter as required. Like the preceding, this arrangement is likewise complex, cost-intensive and can not be realized without the use of control logic.

Based on this, the object of the present invention is to solve the above-described problems and to provide an inverter. strike, which allows short-circuiting the motor terminals of a three-phase motor to protect against voltage feedback easy and inexpensive without the inclusion of the control logic of the inverter.

This object is achieved by the features of claim 1.

According to the invention, an inverter is provided, in particular for supplying energy to a three-phase motor of a motor vehicle, wherein the inverter has a half-bridge for electrical connection to the three-phase motor, wherein the half-bridge has a short-circuit element which is electrically conductively connected to an input and an output of a power semiconductor switch of the half-bridge and which is dependent the voltage value (magnitude and sign) of a voltage applied between input and output of the power semiconductor switch defines a short circuit between input and output of the power semiconductor switch.

In one embodiment of the invention, a half-circuit element of the inverter is provided with an input and an output of a power semiconductor switch of the half-bridge electrically connected short-circuit element which defines a function of the voltage value (magnitude and sign) of an applied voltage between input and output of the power semiconductor switch voltage creates between the input and output of the power semiconductor switch of the respective half-bridge.

In yet another embodiment of the inverter according to the invention, the short circuit generates in each case a current flow possibility through the short-circuit element in the direction from input to output of the respective power semiconductor switch.

According to an embodiment of an inverter according to the invention, the short circuit generates in each case a current flow possibility through the respective short-circuit element opposite to the direction of current flow through one with the input and the output of the respective power semiconductor switch connected freewheeling diode.

Furthermore, an inverter is proposed, wherein the short-circuit element is arranged in the reverse direction between the input and the output, wherein the short-circuit element is conductive from reaching a defined voltage applied between input and output voltage value in the reverse direction by generating a short circuit.

In an embodiment of the inverter according to the invention, the short-circuit element may have a one-way short-circuit element and / or a reusable short-circuit element. In this case, the short-circuit element may comprise a comparator and / or a power switch, in particular a semiconductor switch or a mechanical switch. Furthermore, the short-circuit element may have a diode and / or a gas absorber and / or a varistor. In a further embodiment of the inverter, the short-circuit element can have an AC conductor and / or a semiconductor which conducts its destruction.

Further proposed is a drive arrangement, in particular of a motor vehicle, which has a three-phase motor, wherein a phase winding of the three-phase motor is electrically conductively connected to the half-bridge of an inverter according to the invention for supplying electrical energy.

In a further drive arrangement according to the invention, in each case one phase winding of the three-phase motor is electrically conductively connected to one half-bridge of the inverter each.

In still another drive arrangement according to the invention, the three-phase motor is a synchronous motor, in particular a permanent or third-excited synchronous motor. Further features and advantages of the invention will become apparent from the following description of embodiments of the invention, with reference to the figures of the drawings, which show details essential to the invention, and from the claims. The individual features can be realized individually for themselves or for several in any combination in a variant of the invention.

Preferred embodiments of the invention are explained below with reference to the accompanying drawings. It shows:

1 shows by way of example a bridge circuit of an inverter according to a possible embodiment of the invention.

In the following description and the drawing same reference numerals correspond to elements of the same or comparable function.

Fig. 1 shows a bridge circuit 1 of a drive inverter according to the invention or inverter with a short circuit arrangement 2, in particular for the protection against voltage feedback of a motor, e.g. a three-phase motor 3, in particular a separately excited or permanently excited synchronous motor. The (drive) inverter is for example part of a converter known in the art.

A converter has, for example, in a known manner a rectifier unit (not shown), which feeds a DC link in which, for example, an intermediate circuit capacitor is arranged. The intermediate circuit supplies, for example, an intermediate circuit voltage U _Z K, in particular as a DC voltage to the input 1 'of the inverter 2, for example for the bridge circuit 1 of the inverter, for generating the provided for motor operation AC voltage. The inverter generates, for example, an alternating voltage as an output voltage with variable voltage and frequency, for example to control the direction of rotation and speed of the three-phase motor 3 connected or connected thereto.

The bridge circuit 1 of the inverter, to whose input terminals 1 ', for example, the intermediate circuit voltage U _Z K is applied, has, for example, a half-bridge 1 a or 1 b, 1 c, which each with a winding strand 3a and 3b, 3c of the three-phase motor 3 is electrically connected, for example via a respective center tap 4a and 4b, 4c in a known manner or connected. In the present case, the three-phase motor 3 is designed, for example, as a three-phase motor whose three winding phases 3a, 3b, 3c are each fed by a half-bridge 1 a, 1 b, 1 c. The respective strand 3a, 3b, 3c of the three-phase motor 3 is thereby supplied by the respective half-bridge 1 a, 1 b, 1 c, a voltage or a potential of predetermined polarity for a certain period of time. For this purpose, the respective power semiconductor switch 5a, 5b of the half-bridges 1 a, 1 b, 1 c are respectively controlled, for example by means of a control logic, in a known manner accordingly.

A half bridge 1 a, 1 b, 1 c has e.g. a first (lower) power semiconductor switch 5a and a second (upper) power semiconductor switch 5b, e.g. as an insulated gate bipolar transistor (IGBT) or as a field effect transistor (FET), e.g. are formed as a metal oxide semiconductor field effect transistor (MOSFET). The power semiconductor switches 5a, 5b are e.g. in particular designed or correspondingly dimensioned for the voltages occurring in the converter or in the drive inverter. Other power semiconductor switch types are also conceivable.

The power semiconductor switches 5a, 5b each have a control input 6a, e.g. in the form of a gate electrode and an input 6b in e.g. Form of a collector electrode (IGBT) or drain electrode (MOSFET) and an output 6c in e.g. Shape of an emitter electrode (IGBT) or source electrode (MOSFET). Between input 6b and output 6c, a free-wheeling diode 7, for example, is connected in parallel in a conventional manner, in particular in parallel in the reverse direction.

The power semiconductor switches 5a (lower row), 5b (upper row) are, as mentioned above, e.g. controlled via their respective control input 6a or control terminal in a known manner, e.g. from control electronics (not shown), between input 6b and output 6c due to the control e.g. a short circuit can be generated, i.e. the power semiconductor switch 5a and 5b turns on.

The inverter according to the invention has a short-circuit arrangement 2, which is formed by, for example, a short-circuit element 8, in particular, for example by a respective short-circuit element 8 per half-bridge 1 a and 1 b, 1 c is formed. Depending on a short-circuit element 8, for example, each arranged on a power semiconductor switch 5a of the lower row, wherein, for example, no short-circuit elements 8 are arranged on the power semiconductor switches 5b of the upper row.

In the present case, the short-circuit element 8 is in each case electrically connected in the associated half-bridge 1 a, 1 b, 1 c to the input 6 b of the power semiconductor switch 5 a and to the output 6 c thereof, and thus in the case of a

Short circuit suitable to bridge this. The input 6b is also e.g.

with the center tap 4a and 4b, 4c of the associated half-bridge 1 a, and 1 b, 1 c electrically connected. The short-circuit element 8 is so far in each case arranged in parallel or parallel to the input 6b and output 6c of the respective power semiconductor switch 5a and arranged so far parallel to the respective freewheeling diode 7 of the power semiconductor switch 5a, wherein the freewheeling diode also with the input 6b and 6c output the power semiconductor switch 5a and 5b is connected.

According to the invention, it is also provided to arrange a short-circuit element 8 parallel to a freewheeling diode 7 or to an input 6b and an output 6c of a power semiconductor switch 5b of the upper row, in particular for each half-bridge 1 a, 1 b, 1 c. With such an arrangement, the arrangement on the power semiconductor switches 5a of the lower row can be dispensed with.

According to the invention, the short-circuit element 8 of the short-circuiting arrangement 2 is provided for clamping the terminal voltage of the motor or the voltage of the three-phase motor 3 in the example of FIG. Case of a stress feedback, e.g. In case of inverter failure, set to substantially zero volts. The short circuit can be achieved solely by the short-circuit element 8 in the form of one or more suitably selected components and in particular without e.g. Interaction, e.g. be achieved with the control logic of the inverter, insofar as self-sufficient.

The selected components indicate, for example, in particular, for example due to their dimensioning or material properties, a voltage value as a threshold before, ie the voltage, from which a short circuit is generated. The short-circuit elements 8 are for this purpose, for example, as long as, in particular their intended reverse direction, eg from input 6b to output 6c, until the voltage applied to them or between input 6b and output 6c reaches the intended threshold voltage. Starting from the threshold voltage or exceeding the threshold voltage at the respective motor terminals or between input 6b and output 6c of the respective power semiconductor switch, the short-circuit elements 8 generate a short circuit between input 6b and output 6c, for example. They are so far in each case in their reverse direction conductive. In this respect, a short-circuit element 8 connects input 6b and output 6c of a respective power semiconductor switch 5a or 5b as a function of the voltage value of the voltage present between input 6b and output 6c in a high-impedance manner or by means of a generated short circuit.

The inverter is designed in such a way that the voltage generated by the short-circuit element 8, e.g. As a result of reaching the threshold value, the short circuit generated in each case creates a current flow possibility through the respective short-circuit element 8 in the direction from the input 6b to the output 6c of the respective power semiconductor switch 5a or 5b. In other words, the short-circuit element 8 in the event of reaching the threshold voltage by means of the generated short circuit in its reverse direction is conductive. The reverse direction of the short-circuit element 8 arranged between the input 6b and the output 6c corresponds in this case to e.g. in particular the reverse direction of the freewheeling diode 7.

The short circuit, e.g. between input 6b and output 6c, generates in each case in particular a current flow possibility through the respective short-circuit element 8 opposite or antiparallel to the intended or intended current flow direction through the connected to the input 6b and the output 6c of the respective power semiconductor switch freewheeling diode 7. Thus, a current 9 of eg a winding strand 3a of the motor 3 by means of the short circuit across the short-circuit element 8 and a e.g. Freewheeling diode 7 e.g. to another winding strand 3b of the motor 3 flow.

In order to ensure this functionality, various components can be used as a short-circuit element 8, for example from the outside. bare elements or elements integrated in the inverter. A short-circuit element 8 can be an active (construction) element which, for example, permits control or has a passive (construction) element or can be designed as such. The short-circuit element 8 can be a disposable short-circuit element 8, which can be used only once, for example, or a reusable short-circuit element 8, which can be used several times, for example.

As a disposable element is for example a diode with a defined reverse voltage into consideration, which becomes conductive in the reverse direction as soon as the blocking voltage is exceeded by the terminal voltage of the motor 3. Until the reverse voltage is reached, the diode is e.g. in the reverse direction high impedance.

In addition, any semiconductors, e.g. as a result of their destruction, e.g. by the applied, fed-back voltage between input 6b and output 6c, become conductive and thus generate a short circuit between input 6b and output 6c. In such disposable short-circuit elements 8 in particular a permanent short circuit is generated. Normal operation of the electric vehicle drive, i. the three-phase motor 3 by means of the inverter is no longer possible. The short-circuit element 8 must be e.g. be replaced.

For example, a reusable shorting element 8 may have an array of multiple components, e.g. a device with e.g. a comparator, which detects an overvoltage or exceeding the threshold voltage, and consequently actuates a circuit breaker, whose permeability (on / off) can be controlled in dependence on the detected voltage value. The power switch may comprise a semiconductor switch, e.g. a transistor switch or a e.g. mechanical switch, e.g. a relay, his.

As repeatedly reusable short-circuit element 8, for example, a Gasabieiter can be used, for example, a Gasabieiter with a varistor connected in parallel. In addition, for example, any AC conductor can be used as a short-circuit element 8. The solution with reusable short-circuit elements 8 tends to be more complex. After the AC voltage has fallen to approximately zero volts, the electric drive or the three-phase motor 3 can continue to be operated. It is conceivable within an inverter, for example, different types of short-circuit elements 8, for example, each half bridge 1 a, 1 b, 1 c different types, to provide a short circuit arrangement 2. All of the short-circuit elements 8 according to the invention or the short-circuit arrangement 2 generate the short-circuit independently or independently, ie solely as a function of the voltage applied to the short-circuit element 8. In that regard, an inventive short-circuit element 8 and the short-circuit arrangement 2 of a controller of or by the inverter (s), inverter (s) or motor), etc. independent. Other components, in particular a wiring with external signal sources such as those of a control logic of the inverter or inverter, which controls, for example, the power semiconductors, are not provided for short-circuit generation according to the invention next to it.

The generation according to the invention of a short circuit, in which a short circuit between each two terminals of the motor 3 is created by a short-circuit element 8, in each case in conjunction with one freewheeling diode 7 at least from potentially harmful voltage feedback or from a defined threshold value, causes e.g. a short-circuit braking torque which, in a motor decoupled from the powertrain, may cause the engine to decelerate, i. the speed goes back to zero. In a motor connected to the drive train, e.g. the entire drivetrain braked.

A current flowing in the three-phase motor 3 and inverter 9 thus flows when generated short circuit, for example, from a first, connected to the center tap 4a terminal of the three-phase motor 3 through the short-circuit element 8 of the short circuit arrangement 2 via the freewheeling diode 7 back to another, connected to the center tap 4b terminal of the engine 3. REFERENCE CHARACTERS

bridge circuit

'Input terminals

a, 1 b, 1 c half-bridge

Short circuit arrangement

engine

a, 3b, 3c winding strand

a, 4b, 4c center tap

a Power semiconductor switch (lower row) b Power semiconductor switch (upper row) a Control input Power semiconductor switchb Input Power semiconductor switchc Output Power semiconductor switch

Freewheeling diode

Short-circuit element

electricity

Claims

claims

1 . Inverter, in particular for supplying energy to a three-phase motor (3) of a motor vehicle, the inverter having a half-bridge (1 a, 1 b, 1 c) for electrical connection to the three-phase motor (3), characterized in that the half-bridge (1 a, 1 b, 1 c) has a short - circuit element (8) connected in an electrically conductive manner to an input (6b) and an output (6c) of a power semiconductor switch (5a, 5b) of the half bridge (1a, 1b, 1c) Voltage value of a voltage applied between input (6b) and output (6c) of the power semiconductor switch (5a; 5b) defines a short circuit between input (6b) and output (6c) of the power semiconductor switch (5a; 5b).

2. Inverter according to claim 1, characterized in that each half-bridge (1 a, 1 b, 1 c) of the inverter with an input (6 b) and an output (6 c) of a power semiconductor switch (5 a, 5 b) of the half-bridge (1 a , 1 b, 1 c) electrically conductively connected short-circuit element (8) is provided, which in dependence on the voltage value of an input (6b) and output (6c) of the power semiconductor switch (5a, 5b) voltage defines a short circuit between Input (6b) and output (6c) of the power semiconductor switch (5a, 5b) of the respective half-bridge (1 a, 1 b, 1 c) creates.

3. Inverter according to claim 1 or 2, characterized in that the short circuit each provides a Stromflussmöglichkeit by the short-circuit element (8) in the direction of input (6b) to output (6c) of the respective power semiconductor switch (5a, 5b).

4. Inverter according to one of the preceding claims, characterized in that the short circuit in each case a current flow through the respective short-circuit element (8) opposite to the direction of current flow through a with the input (6b) and the output (6c) of the respective power semiconductor switch (5a; 5b) connected freewheeling diode (7) creates.

5. Inverter according to one of the preceding claims, characterized in that the short-circuit element (8) in the reverse direction between the input (6b) and the output (6c) is arranged, wherein the short-circuit element (8) from reaching a defined between input (6b) and output (6c) voltage in the reverse direction by generating a short circuit becomes conductive.

6. Inverter according to one of the preceding claims, characterized in that the short-circuit element (8) comprises a disposable short-circuit element and / or a reusable short-circuit element.

7. Inverter according to one of the preceding claims, characterized in that the short-circuit element (8) comprises a comparator and / or a power switch, in particular a semiconductor switch or a mechanical switch.

8. Inverter according to one of the preceding claims, characterized in that the short-circuit element (8) has a diode and / or a Gasablei- ter and / or a varistor.

9. Inverter according to one of the preceding claims, characterized in that the short-circuit element (8) has an AC conductor and / or a semiconductor which causes its destruction.

10. Drive arrangement, in particular of a motor vehicle, comprising a three-phase motor (3), characterized in that a winding strand (3a, 3b, 3c) of the three-phase motor (3) with the half-bridge (1 a, 1 b, 1 c) of an inverter after a of claims 1 to 9 is electrically conductively connected to the supply of electrical energy.

1 1. Drive arrangement according to claim 10, characterized in that each one winding strand (3a, 3b, 3c) of the three-phase motor (3) is electrically conductively connected to one half-bridge (1 a, 1 b, 1 c) of the inverter.

12. Drive arrangement according to claim 10 or 1 1, characterized in that the three-phase motor (3) is a synchronous motor, in particular a permanent or third-excited synchronous motor.