WO2004049566A2

WO2004049566A2 - Device for electronically actuating a load element, assembly of said device and use of the device or assembly

Info

Publication number: WO2004049566A2
Application number: PCT/DE2003/003613
Authority: WO
Inventors: Heinz Mitlehner; Michael SCHRÖCK
Original assignee: Siemens Aktiengesellschaft
Priority date: 2002-11-27
Filing date: 2003-10-30
Publication date: 2004-06-10
Also published as: WO2004049566A3; DE10255373A1

Abstract

The invention relates to a device (1a) for electronically actuating a load element, an assembly of said device and the use of the device or assembly. The aim of the invention is to provide a device that is characterised by a low heat build-up, both during the initial operation and the nominal value operation of a load element (2) to be actuated. To achieve this, in addition to a first semiconductor switch element (3a) with a determinable power loss, the device is equipped with a second semiconductor switch element (4a) that is electrically connected on the load current side, in parallel to the first switch element, said second element having a determinable power loss that is different from that of the first semiconductor switch element (3a). During the initial operation of the load element (2), the power loss of the second semiconductor switch element (4a) falls short of that of the first semiconductor switch element and/or during the nominal value operation of the load element (2) the power loss of the first semiconductor switch element (3a) falls short of that of the second semiconductor switch element.

Description

description

Device for electronically switching a load element, arrangement of the device and use of the device or arrangement

The invention relates to a device for electronically switching a load element fed by a power source according to claim 1, to an arrangement of the device according to claim 10, 11 and to a use of the device or the arrangement according to claim 15, 16.

From DE 196 12 216 AI an electronic branch switching device for a three-phase source is known, which is made with semiconductor switching elements. The aforementioned branch switching device has, among other things, two semiconductor components which are electrically connected in series to form a hybrid power MOSFET. Such a hybrid power MOSFET is disclosed for example in DE 199 02 520 AI. Semiconductor switching or components used in this way are used, inter alia, in low-voltage and possibly also in medium-voltage switching technology and are used for contactless switching on and off of a power source-powered consumer, for example a motor.

When a consumer acting as a load element, for example a motor, is switched on, a starting current that is a multiple of the nominal current flows until the motor-specific nominal speed is reached. Transferred to a switching device with semiconductors for electronically switching the consumer, in particular the motor, there is a strong thermal load in said semiconductors during the start-up phase. Consequently, the load resulting from the start-up phase determines the dimensioning of the semiconductors. It is the object of the present invention to provide a device for electronic switching, an arrangement of the device and a use of the device or arrangement which are characterized by low heat development both in the start-up mode and in the rated mode of a load element to be switched.

The invention is based on the knowledge that the heat development is caused by power losses due to semiconductors - also called leakage losses.

This object is achieved with regard to the device according to the invention by the features of patent claim 1, with regard to the arrangement of the device according to the invention by the features of patent claims 11, 12 and in relation to the use of the arrangement or the device by the features of patent claims 16,17; Advantageous embodiments of the device, the arrangement and the use are each the subject of further claims.

Through the interconnection or the construction of the device with two semiconductor switching elements that are electrically connected in parallel to one another on the load current side and have different power losses depending on the respective component-specific current-voltage output characteristic curve, by means of which, in the current-carrying state, the power loss of the other semiconductor switching element is undercut by the second semiconductor switching element during start-up operation of the load element and / or given by the first semiconductor switching element during nominal operation of the load element, it is achieved that the load current flows during start-up operation essentially over the second semiconductor switching element or over both semiconductor switching elements, wherein the voltage drop across the second semiconductor switching element is based on its characteristic curve versus the characteristic curve characteristic of the first semiconductor switching element results in a lower ratio of the power losses based on the starting and nominal current.

Furthermore, depending on the control of the device, the load current essentially flows through the first semiconductor switching element during nominal operation, which is provided with a forward voltage that is lower than the forward voltage of the second semiconductor switching element, so that the forwarding losses are also kept low in this operating phase can be, which results overall in a favorable power loss balance through the synergy utilization of both semiconductor switching elements.

Low conduction losses or low power losses mean that the device for electronic switching heats up slightly, so that on the one hand a reduction in the necessary semiconductor material (chip area) or a reduction in the number of necessary heat sinks and thus also a reduction in the construction volume of the device with the same switching capacity is carried out or on the other hand Increasing the switching capacity of the device in the sense of an increase in efficiency can be achieved with the same heat sink size.

The invention and advantageous refinements according to the features of the further claims are explained in more detail below with reference to exemplary embodiments shown in the drawing; show in it:

1 shows a variant of the device for electronic switching;

2 shows an embodiment variant of the arrangement with two bidirectionally switched devices;

3 shows an embodiment variant of the arrangement with a plurality of devices connected in phase and / or bidirectionally; 4 shows a current-voltage diagram with the output characteristics of the first semiconductor switching element and the second semiconductor switching element, each for itself; and

5 shows a further current-voltage diagram with the output characteristic of the device or the respective arrangement for electronic switching.

1 shows the circuitry-specific or component-specific structure of a device la for the electronic switching of a load element 2 which is supplied or supplied by a current source on the basis of an embodiment variant which can advantageously be used, inter alia, as a single-phase DC switch. In the load current path of the device 1 a, the current source or the load element 2, in particular a motor, can be connected to one of the inflow or outflow connections S or D (source or drain ports).

The device la here has a first semiconductor switching element 3a and a second one electrically connected in parallel to the load current side, that is to say at the respectively provided or in the region of the inflow and outflow connections S and D (source and drain ports) Semiconductor switching element 4a in the sense of a hybrid circuit breaker. Depending on the application, the semiconductor switching elements 3a and 4a can be implemented as power semiconductors. Both the first and the second semiconductor switching elements 3a and 4a each have a characterizing current-voltage output characteristic curve K1 or K2 according to FIG. 4, by means of which semiconductor-specific power losses can be determined.

The power loss of the first semiconductor switching element 3a, however, differs from the power loss of the second semiconductor switching element 4a, such that the power loss of the respective other semiconductor switching element 3a or 4a by the second semiconductor switching element 4a im Start-up operation of the load element 2 and / or by the first

The semiconductor switching element 3 a falls below in the nominal operation of the load element 2, thereby giving an effect which increases the efficiency of the device 1 a in the sense of an improved transmission behavior.

The first semiconductor switching element 3a is designed on the basis of its current-voltage output characteristic curve K 1 for the nominal operation and possibly for the start-up operation of the load element 2, the second semiconductor switching element 4 a primarily for the start-up operation due to its current-voltage output characteristic curve K 2 of the load element 2 is characterized. The transmission behavior of the two semiconductor switching elements 3a and 4a is thus determined by the associated current-voltage output characteristic curve K1 or K2, which represents the power loss.

On the control current side, the first semiconductor switching element 3a and the second semiconductor switching element 4a each have a controllable connection G (gate), which is electrically connected here and thereby ensures simultaneous and interdependent activation of both semiconductor switching elements 3a and 4a. Advantageously, the load current can flow as a function of the characteristic of the respective current-voltage output characteristic curve during the start-up operation of the load element 2 via both semiconductor switching elements 3a and 4a and during nominal operation via the first semiconductor switching element 3a.

Furthermore, in an advantageous embodiment, at least one control element 5 is provided on the common connection G, in particular for controlling the first semiconductor switching element 3a and the second semiconductor switching element 4a β is used for potential-free, ie safety-oriented control by means of an optocoupler or the like. Of course, it is also possible to provide an individual, that is to say a time-shifted or independent control of the connections G with independent control elements which, if appropriate, communicate with one another in the sense of a dependent control. Advantageously, the second semiconductor switching element 4a in front of the first semiconductor switching element 3a is acted upon by a control voltage at the corresponding connection G, as a result of which a current-voltage output characteristic curve K3 according to FIG. 5 is provided, which in each case in start-up operation or in nominal operation is the pass behavior one of the two semiconductor switching elements 3a and 4a is determined.

In an advantageous embodiment, the first semiconductor switching element 3a is on the one hand as a transistor, in particular as a silicon carbide junction field-effect transistor 6a (SiC-J-FET) with a transistor electrically connected in series therewith, in particular silicon-metal oxide field-effect transistor 7a (Si-MOS-FET) or silicon carbide metal oxide field-effect transistor (SiC-MOS-FET), in the sense of a cascode with a low forward voltage. The Si-MOS-FET 7a in turn has an internal bipolar diode D1 which is connected antiparallel to this and is generally referred to as an inverse diode or internal freewheeling diode.

On the other hand, the second semiconductor switching element 4a is designed as a transistor, in particular as a cost-effective silicon insulating layer bipolar transistor (Si-IGBT) with an inverse diode D2 connected antiparallel to it, which in turn is also connected antiparallel to the first semiconductor switching element 3a and the Current at negative Drain voltage leads past the Si-IGBT. The Si-IGBT is characterized by a favorable ratio of the power losses, which results from the quotient of the start-up operating power loss to the nominal operating power loss. At the same time, the Si-IGBT in the case of the aforementioned parallel connection with the cascode determines the short-circuit strength or the thermal short-circuit capacity - current that can be conducted by a semiconductor or semiconductor composite for a certain time, here about 10 μs, without damage - of the device la.

In view of the optimized power loss balance during start-up and nominal operation due to said synergy utilization, cost-intensive silicon carbide area can be saved. These device-economic advantages result from the fact that the SiC-J-FET 6a only has to be dimensioned with regard to its nominal current and this results in an optimization potential for reducing the power loss or the operating temperature. It is accordingly possible to reduce the silicon carbide area of the SiC-J-FET 6a approximately in accordance with the ratio of the nominal current to the starting current, so that a construction-space-saving and cost-saving construction of the device la can be achieved.

According to FIG. 2, an advantageous embodiment variant of an arrangement with two bidirectionally switched devices 1 a and 1 b is shown, which can be used, inter alia, as a single-phase AC switch. In this case, an additional device 1b of identical construction and electrically anti-serial connected on the load current side is connected in series with the device 1 a. given the load element 2. The device 1b, in accordance with the exemplary embodiment according to FIG. 1, is likewise provided on both semiconductor switching elements 3b or 4b with a connection G and with a diode D1, an inverse diode D2, a SiC J-FET 6b, a Si-MOS-FET 7b and a Si-IGBT equipped in the same way.

At least one control element 5 can in this case be electrically conductively connected to the corresponding connections G such that simultaneous and / or interdependent control of the two semiconductor switching elements 3b or 4b or of the two devices 1a, 1b is provided. Of course, the connections G are also staggered in time and / or can be controlled independently of one another with a plurality of control elements, in particular potential-free.

FIG. 3 shows an embodiment variant of the arrangement or the device la according to FIG. 1 or 2 with a plurality of devices connected in phase and / or bidirectional, which can advantageously be used, inter alia, as a multi-phase AC or three-phase switch. A first part of the arrangement relates to an arrangement in which the switching device la is electrically linked together with at least one identical switching device la, which is connected in phase parallel to the load current, for each phase of the current source, and the load element 4 arranged in series with it can be switched.

Furthermore, an expanded arrangement is shown, in which additional devices 1b are provided for the devices, shown in dashed lines. Said arrangement with devices bidirectionally connected electrically bidirectionally on the load current side per phase of the current source according to FIG. 2 serves in conjunction with at least one further device, connected structurally in parallel, in particular structurally identical, bidirectionally switched devices la or lb for switching the load element 2 on and off.

In this arrangement, a pair of anti-serial devices la, lb relates to one phase of a three-phase source, with a three-phase load element 2, in particular a three-phase motor, can be switched on or off depending on the activation of the control element 5. The embodiment variant shown has the same structure in the three phases, which is why the structure with the control element 5 is shown here in a simplified manner, based on one phase.

In an advantageous embodiment variant according to FIG. 4, the current-voltage output characteristic curve K 1 of the first semiconductor switching element 3 a is linear and the current-voltage output characteristic curve K 2 of the second semiconductor switching element 4 a is parabolic, as a result of which the device 1 a is superimposed on the respective characteristic curve profile of the corresponding one Semiconductor switching element 3a and 4a benefits. Here, the parabola-like current-voltage output characteristic curve K2 of the second semiconductor switching element 4a requires a lower voltage than the current-voltage output characteristic curve K1 of the first semiconductor switching element 3a at a higher current. Due to the voltage drop at the second semiconductor switching element 3a; 3b results in a low ratio of the power losses based on the starting and nominal current.

In addition to this, the current-voltage output characteristic curve K 1 of the first semiconductor switching element 3 a; 4a due to its low forward voltage compared to the current-voltage output characteristic K2 of the second semiconductor switching element 4a; 4b with a smaller current in nominal operation also a smaller voltage, so that the conduction losses can also be kept low in this operating phase, which results in an overall optimized power loss balance through the synergy utilization of both semiconductor components 3a, 3b; 4a, 4b according to the current-voltage output characteristic curve K3 shown in FIG. 4 and 5 are diagrams which are generated on the basis of the operating points of the device la or the arrangement with the devices la, lb as a function of an assumed starting and nominal current I _A or I _e . The Y axis typically represents the current axis I _D and the X axis the voltage axis U _DS .

The invention explained above can be summarized as follows:

In order to achieve a device 1 a for the electronic switching of a load element, an arrangement of the device and a use of the device or the arrangement, which are to be characterized by low heat development both in the start-up mode and in the rated mode of a load element 2 to be switched, with regard to FIG Device provided that in addition to a first semiconductor switching element 3a with a determinable power loss, there is a second semiconductor switching element 4a which is electrically connected in parallel on the load current side and has a determinable but different power loss for the first semiconductor switching element 3a, the power loss of the respective other semiconductor Switching element by the second semiconductor switching element 4a in the start-up mode of the load element 2 and / or by the first semiconductor switching element 3a in the nominal mode of the load element 2.

Claims

claims

1. Device (la) for electronically switching a load element (2) fed by a current source,

- With a first semiconductor switching element (3a) with a power loss determined by its current-voltage output characteristic (Kl);

- With a second semiconductor switching element (4a) which is electrically connected in parallel with the load current on the load current side and has a power loss which can also be determined by its current-voltage output characteristic (K2) but is different for the power loss of the first semiconductor switching element (3a) ;

- If the power loss of the respective other semiconductor switching element (3a or 4a) is undershot by the second semiconductor switching element (4a) during start-up operation of the load element (2) and / or by the first semiconductor switching element (3a) in the nominal operation of the load element (2).

2. Device (la) according to claim 1, with a linear profile of the current-voltage output characteristic (Kl) of the first semiconductor switching element (3a) and / or a parabolic-like profile of the current-voltage output characteristic (K2) of the second semiconductor switching element (4a).

3. Device (la) according to claim 1 and / or 2, each having a control current side electrically controllable connection (G) of the first semiconductor switching element (3a) and the second semiconductor switching element (4a).

4. The device (la) according to claim 3, with a simultaneous and / or interdependent control of the connections (G).

5. The device (la) according to claim 4, with an electrically conductive connection between the terminals (G).

6. The device (la) according to claim 3, with a staggered and / or mutually independent control of the connections (G).

7. The device (la) according to claim 5, with a control of only the second semiconductor switching element (4a) in the start-up mode and a control of only the first semiconductor switching element (3a) in the rated mode,

8. The device (la) according to claim 1 to 3 and 7, with a transistor, in particular silicon carbide junction field-effect transistor (6a), and one, in the sense of a cascode, electrically connected in series transistor, in particular silicon-metal oxide Field effect transistor (7a), as the first semiconductor switching element (3a).

9. The device (la) according to claim 8, with a series circuit of the silicon carbide barrier layer field effect transistor and a silicon carbide metal oxide field effect transistor as the first semiconductor switching element (3a).

10. The device (la) according to claim 1 to 3 and 7, with a transistor, in particular silicon insulating layer bipolar transistor, as a second semiconductor switching element (4a).

11. The device (la) according to claim 1, with at least one control element (5) for control, in particular for potential-free control, of the semiconductor components (3a, 3b) via the connections (G).

12. Arrangement with a device (la) according to claim 1, together with at least one load current side electrically connected in phase parallel, further device (la) for electronic switching per phase of the current source and in each case in series with the load element (2).

13. Arrangement with a device (la) according to claim 1, together with a load current side electrically bidirectionally connected, further device (lb) for electronic switching per phase of the current source in series with the load element (2).

14. Arrangement according to claim 13, together with at least one load current side electrically connected in phase parallel, further device (la, lb) for electronic switching per phase of the current source and in each case in series with the load element (2).

15. Arrangement according to one of claims 12 to 14, with a to the respective device (la; la, lb) identical devices (la; la, lb).

16. The arrangement according to claim 12 or 13, with at least one control element (5) for control, in particular for potential-free control, of the semiconductor components

(3a, 3b; 4a, 4b) via the connections (G).

17. Use of the device (la) according to claim 1 or the arrangement according to claim 12, in the sense of a single-phase or multi-phase DC switch.

18. Use of the arrangement according to one of claims 13 or 14, in the sense of a single-phase or multi-phase AC switch.

19. Use of the device (la; la, lb) or the arrangement according to one of the preceding claims in a Wechselbzw. Three-phase system.

20. Use of the device (la; la, lb) or the arrangement according to one of the preceding claims for switching an electric motor on and off.