Control device and method for controlling a semiconductor switch, switching device and electrical power converter

Abstract

The invention relates to controlling a semiconductor switch. It is provided that the voltage level of the control signal is varied to control the semiconductor switch. In particular, the reference voltages for opening and closing the semiconductor switch can be varied. In this way, it is possible to set different configurations for the voltage level of the control signal for different operating states.

Description

Technical field

[0001] The present invention relates to a control device for a semiconductor switch and a method for controlling a semiconductor switch. The present invention further relates to a switching device and an electrical power converter with such a control device. background

[0002] In modern power electronic components, switching tasks are frequently performed using semiconductor switches, such as MOSFETs (metal oxide field-effect transistors) or insulated-gate bipolar transistors (IGBTs). A control signal can be applied to a control terminal of such a semiconductor switch, for example, a base or gate terminal, which then closes or opens an electrical connection between two power terminals, such as emitter and collector (or source and drain). The on-resistance of such a semiconductor switch can depend, among other things, on the control voltage applied to the control terminal.

[0003] Such semiconductor switches are used, for example, in power converters for electric drive systems. Here, the semiconductor switches of a full bridge circuit can be controlled in a suitable manner to generate a single- or multi-phase alternating voltage from an input DC voltage, which is suitable for driving an electric machine. Furthermore, such an electric power converter can also establish a safe operating state in which, for example, the phase terminals of an electric machine can be short-circuited via the semiconductor switches in the electric power converter by means of a so-called active short circuit.

[0004] The publication DE 10 2020 206 478 A1 describes, for example, a control device for such an electrical converter, in which, depending on the current speed of the electrical machine, either the described active short circuit or alternatively a freewheel can be set. Disclosure of the invention

[0005] The present invention provides a control device and a method for controlling a semiconductor switch, as well as a switching device and an electrical power converter with the features of the independent claims. Further advantageous embodiments are the subject of the dependent claims. Accordingly, the following is planned:

[0006] A control device for a semiconductor switch comprising a driver, a reference voltage device, and a control device. The driver is designed to provide a control signal for the semiconductor switch. The reference voltage device is designed to provide a first output voltage and, optionally, a second output voltage to the driver. The control device is designed to adjust the voltage level of the first output voltage and / or the voltage level of the second output voltage from the reference voltage device. In other words, the voltage level of the first output voltage or the second output voltage can be varied or adjusted by the control device.The driver device is specifically designed to provide the control signal for the semiconductor switch using the first output voltage and / or the second output voltage from the reference voltage device. For example, to close the semiconductor switch, the driver device can apply the control signal using the first output voltage, such as a positive or higher output voltage, to the control terminal of the semiconductor switch, and to open the semiconductor switch, it can provide a control signal using the second output voltage, such as a lower or negative output voltage, to the control terminal of the semiconductor switch. Furthermore, the following is planned:

[0007] A switching device comprising a semiconductor switch and a control device according to the invention, wherein the driver device of the control device is designed to provide the control signal at a control terminal of the semiconductor switch. Furthermore, the following is planned:

[0008] An electrical power converter with several semiconductor switches and several control devices according to the invention, wherein a driver circuit of a control device is designed to provide a control signal at a control terminal of a semiconductor switch. Finally, the following is planned:

[0009] A method for controlling a semiconductor switch, comprising a step for providing a first output voltage and a second output voltage. The first and second output voltages can be provided, in particular, by a reference voltage device, for example, the reference voltage device of the control device according to the invention. The method further comprises a step for providing a control signal for the semiconductor switch, wherein the control signal can be provided at a control terminal of the semiconductor switch. The control signal is provided, in particular, using the first output voltage and / or the second output voltage. The control signal can be provided, for example, by a driver device, in particular a driver device of a control device according to the invention.The voltage level of the first output voltage and / or the voltage level of the second output voltage can be set using an external signal. For example, the voltage level of the first and / or second output voltage can be set to a predetermined voltage value corresponding to such an external signal. Advantages of the invention

[0010] The present invention is based on the understanding that the switching behavior of a semiconductor switch, in particular the on-resistance or through-resistance of such a semiconductor switch between two power terminals, can depend on a control signal at a control terminal of the semiconductor switch, for example, the voltage level of such a control signal. Thus, for example, the through-losses through such semiconductor switches after the application of a control signal to close the semiconductor switch can depend on the provided control signal, for example, the voltage level of the control signal. The present invention is further based on the understanding that, depending on the operating point, a different on-resistance may be desirable.

[0011] For example, it may be desirable that, during the setting of an active short circuit or similar, the through-losses through the semiconductor switch are limited to such an extent when the semiconductor switch is closed that, in the event of a short circuit occurring, the short-circuit current cannot damage the semiconductor switch and it can therefore still safely switch off the short-circuit current.

[0012] Based on this understanding, the present invention aims to provide a concept for controlling a semiconductor switch that can achieve different switching behaviors in the simplest yet most reliable way possible. To this end, the invention provides for the supply of variable reference voltages for controlling the semiconductor switch, whereby these reference voltages can be adjusted depending on the switching behavior desired for the respective operating point. In this way, it is possible to provide a suitable control signal at the control terminal of the semiconductor switch, which corresponds to the desired requirements for the respective current operating point.

[0013] According to one embodiment, the reference voltage device comprises an adjustable voltage source. This adjustable voltage source can be configured to provide an adjustable first output voltage. Additionally or alternatively, the reference voltage device can include a reference voltage component. This reference voltage component can be configured to provide a second output voltage. Such a configuration of a reference voltage component and an adjustable voltage source enables the provision of both output voltages in a simple and reliable manner.

[0014] According to one embodiment, the adjustable voltage source comprises a low-dropout voltage regulator. However, any other suitable adjustable voltage sources, particularly adjustable linear voltage sources, are also possible. In particular, a low-dropout voltage regulator enables the simple provision of a variable, adjustable output voltage.

[0015] According to one embodiment, the reference voltage component comprises a Zener diode. The Zener diode can, in particular, be a programmable Zener diode. Such a programmable Zener diode is understood as a component across which an adjustable voltage drop occurs. In this way, the second output voltage can also be adjusted appropriately. However, depending on the application, any other suitable measures for adjusting the first or second output voltage are also possible. For example, a variable voltage source, such as a low-dropout voltage regulator, can be provided for both the first and second output voltages.

[0016] According to one embodiment, the control device includes a memory. This memory can be configured to store setpoints for the first output voltage and / or the second output voltage. In this case, the control device can be configured to adjust the first output voltage or the second output voltage using the setpoints stored in the memory. The memory can, for example, be non-volatile. Thus, the corresponding data for the output voltage setpoints can be provided by the memory directly after a restart or power-on process. Alternatively, it is also possible to store the setpoints in volatile memory, such as volatile RAM. In this case, the setpoints can be stored in the memory during an initialization phase, for example, during a restart.

[0017] According to one embodiment, the control unit includes a digital communication interface. This digital communication interface could, for example, be a UART (Universal Asynchronous Receiver / Transmitter) interface. However, any other suitable data interface is also possible. Digital control commands can be transmitted from an external component to the control unit via such digital data interfaces. In this way, for example, setpoints for the first and / or second output voltages can be transmitted during an initialization phase. Furthermore, it is also possible, for example, to transmit information via such a digital communication interface to vary the first and / or the second output voltage.For example, by transmitting a suitable control bit or data word, a selection can be made between two or more predefined setpoints for the first output voltage and / or the second output voltage. Furthermore, any other concepts for specifying and / or selecting the voltage level for the output voltages are of course also possible.

[0018] According to one embodiment, the control device includes a trigger input. Such a trigger input can be designed, in particular, to receive a (binary) trigger signal. The trigger input can, for example, be electrically or communicatively coupled to a corresponding external component. In this way, the external component can easily signal a specific operating state to the control device. For example, it can signal to the control device that a safe operating state, such as an active short circuit in an electrical converter for an electric drive system, should be set. Accordingly, the control device can be designed to set the first output voltage and / or the second output voltage to a predetermined value if a trigger signal has been received at the trigger input.In particular, setting a predetermined first or second output voltage to predetermined values ​​upon receiving a trigger signal can be prioritized over other configurations, such as setpoint specifications via the digital communication interface.

[0019] The above embodiments and further developments can be combined with one another as appropriate. Further embodiments, further developments, and implementations of the invention also include combinations of features of the invention described previously or subsequently with regard to the exemplary embodiments, even if not explicitly mentioned. In particular, those skilled in the art will also add individual aspects as improvements or additions to the respective basic forms of the invention. Brief description of the drawings

[0020] Further features and advantages of the invention are explained below with reference to the figures. These show: Fig. 1: a schematic representation of a basic circuit diagram of an electrical power converter according to one embodiment; Fig. 2: a schematic representation of a basic circuit diagram of a control device for a semiconductor switch according to one embodiment; and Fig. 3: a flowchart such as may underlie a method for controlling a semiconductor switch according to one embodiment. Description of embodiments

[0021] Fig. Figure 1 shows a schematic representation of a basic circuit diagram for an electrical converter 1 according to one embodiment. Such an electrical converter 1 can, for example, be used to convert a DC voltage from a DC voltage source 2 into a single- or multi-phase AC voltage suitable for driving an electric machine 3. In the embodiment shown here, the electrical converter 1 comprises three half-bridges, each with two semiconductor switches M1 to M6 connected in series. The nodes at which two semiconductor switches M1 to M6 are connected are connected to a terminal of an AC voltage supply. The electric machine 3 can be connected to these terminals of the AC voltage supply.Furthermore, the two outer terminals of the series circuit, each consisting of two semiconductor switches M1 to M6, are connected to the positive and negative terminals of a DC voltage connection, respectively. This DC voltage connection can be connected to a DC voltage source 2, for example, the traction battery of an electric vehicle.

[0022] By appropriate control, the semiconductor switches M1 to M6 can be opened or closed. In this way, a desired alternating voltage can be generated from the DC voltage provided on the input side, which is suitable for controlling the electric machine 3.

[0023] Furthermore, by simultaneously closing all lower semiconductor switches M2, M4, M6 and simultaneously opening all upper semiconductor switches M1, M3, M5, an electrical short circuit can be established between the connection points of the AC voltage supply and thus the terminals of the electric machine 3. Alternatively, it is also possible to close the upper semiconductor switches M1, M3, M5 and open the lower semiconductor switches M2, M4, M6. These configurations correspond to an active short circuit for a connected electric machine 3. In addition, another safe operating state is possible, for example, in which all six semiconductor switches M1 to M6 are open. This operating state is referred to as freewheeling.

[0024] To control the semiconductor switches M1 to M6, a control device 10 can be provided for each semiconductor switch M1 to M6. This control device 10 can supply an electrical voltage or an electrical current at the corresponding control terminal of the respective semiconductor switch M1 to M6, for example a gate terminal or base terminal, in order to open or close the semiconductor switch M1 to M6. For better clarity, in Fig. Figure 1 shows such a control device 10 only for the first semiconductor switch M1. However, it is understood that such a control device is provided for each semiconductor switch M1 to M6. Furthermore, the electrical converter is not limited to a full bridge circuit with three half bridges, as shown in Figure 1. Fig. Figure 1 is shown. In principle, the electrical converter can also have any other number of half-bridges. Furthermore, the basic principle of the control device 10 according to the invention is also applicable to any other switching devices with a semiconductor switch.

[0025] Fig. Figure 2 shows a schematic diagram of a basic circuit diagram of a control device 10 according to one embodiment. The control device 10 comprises a control unit 11, a reference voltage unit 12, and a driver unit 13. A positive supply voltage VCC and a negative supply voltage VEE can be provided at the control device 10.

[0026] The control device 10, in particular the control unit 11, may be provided with a digital communication interface 11b. This digital communication interface 11b allows the control device 10 to be communicatively coupled with an external component, such as a microcontroller or similar device. In principle, any suitable digital communication protocol is possible for data exchange between the control device 10 and the external component. For example, the digital communication interface could be a UART (Universal Asynchronous Receiver Transmitter) interface.

[0027] Furthermore, a trigger input 11c can be provided on the control device 10, in particular the control unit 11. A trigger signal can be supplied to this trigger input 11c by another external component. This trigger signal can, for example, signal a predetermined operating state. The response to such a trigger signal will be explained in more detail below.

[0028] The reference voltage device 12 can provide a first output voltage V_pos and / or a second output voltage V_neg, particularly using an input voltage VCC-VEE. These output voltages V_pos and V_neg can be provided to a driver device 13, which uses the output voltages V_pos and V_neg to generate a control signal for a semiconductor switch. This control signal can be provided at a control terminal, such as the gate or base of a semiconductor switch. The positive output voltage V_pos and the negative output voltage V_neg can be generated, in particular, with respect to a reference potential HV_GND, also provided by the reference voltage device 12. This reference potential HV_GND can, for example, be connected to one of the power terminals of the semiconductor switch, such as a source terminal or an emitter terminal.In this way, the driver device 13 of the control device 10 can, for example, provide a defined gate-source or base-emitter voltage at the control terminal of the semiconductor switch.

[0029] The reference voltage device 12 can, as exemplified in Fig. Figure 2 shows, for example, a reference voltage component 12a and an adjustable voltage source 12b. The reference voltage component 12a can, for example, be arranged between the negative supply voltage VEE and the reference potential HV_GND. The reference voltage component 12a can, for example, be a Zener diode. In particular, it can also be an adjustable or programmable Zener diode. With such an adjustable or programmable Zener diode, a voltage drop across the reference voltage component 12a can be set, for example, using a suitable control signal. For this purpose, a suitable control signal can, for example, be provided to the reference voltage component 12a by the control unit 11.

[0030] Furthermore, a controllable voltage source 12b can be provided in the reference voltage device 12 between the positive supply voltage VCC and the reference potential HV_GND. The electrical voltage output by the controllable voltage source 12b, i.e., the positive output voltage V_pos, can also be controlled by the control device 11. The controllable voltage source can, in principle, be any suitable controllable voltage source. For example, a low-dropout voltage regulator can be used as the controllable voltage source.

[0031] The driver unit 13 can receive the first output voltage V_pos and / or second output voltage V_neg output by the reference voltage unit 12 and, according to control commands from the control unit 11, output the control signal for the semiconductor switch. For example, the driver unit 13 can output the first output voltage V_pos as a control signal to close the semiconductor switch, and the second output voltage V_neg to open the semiconductor switch.

[0032] The voltage level of the first output voltage V_pos can be adjusted by appropriately setting the adjustable voltage source 12b. Similarly, the second output voltage V_neg can be adjusted by the programmable voltage drop across the reference voltage component 12a. Based on this concept, it is therefore possible, for example, to vary the control signal, in particular the voltage level of the control signal for the semiconductor switch.

[0033] For example, the control unit 11 may include a memory 11a in which setpoints for the first output voltage V_pos and / or the second output voltage V_neg are stored. These setpoints can be stored as fixed setpoints in non-volatile memory. Alternatively, it is also possible to receive the setpoints from an external component, for example via the digital communication interface 11b, and then store them in read / write memory (RAM). For example, the setpoints can be received during startup or an initialization phase and stored in memory 11a.Furthermore, it is also possible, for example, for the control unit 11 to receive the setpoints for the first output voltage V_pos and / or the second output voltage V_neg via the digital communication interface 11b and then directly configure or control the corresponding components, in particular the adjustable voltage source 12b and / or the reference voltage component 12a. Of course, any other concepts for adjusting the first or second output voltage V_pos, V_neg are also possible.

[0034] For example, it is also possible to provide the control unit 11 with information via the digital communication interface 11b to switch between two or more different configurations for the first output voltage V_pos and / or the second output voltage V_neg. This can be implemented, for example, by a suitable bit or data word in a data frame. However, any other suitable concept is also possible.

[0035] Furthermore, the control device 10, in particular the control unit 11, can also be notified of a change to a specific operating state, and thus a change to predetermined setpoints for the first output voltage V_pos and / or the second output voltage V_neg, via a trigger signal provided at the trigger input 11c. Specifically, the change to these predetermined setpoints for the first and / or second output voltage V_pos, V_neg can be prioritized over other setpoint specifications upon receipt of a trigger signal at the trigger input 11c. In this way, for example, it can be implemented that in the event of a fault, such a trigger signal immediately sets a configuration for the first output voltage V_pos and / or the second output voltage V_neg that is to be used for switching behavior in this fault condition.Thus, for example, when setting up an active short circuit as mentioned above, a configuration can be set for the first and / or second output voltage V_pos, V_neg in which the through-resistance of the semiconductor is as low as possible.

[0036] Depending on the application, it is also possible to set several different configurations for the first and / or second output voltages V_pos, V_neg for operational use, i.e., operation in which no trigger signal is present at trigger input 11c. For example, depending on an operating state or operating point, a corresponding configuration for the first and / or second output voltages V_pos, V_neg can be set.

[0037] In a specific embodiment, the control unit 11, reference voltage unit 12, and / or driver unit 13 can be integrated into a common assembly, for example, an application-specific integrated circuit (ASIC). Furthermore, any other concepts for realizing the described concept for a control device of a semiconductor switch are also possible.

[0038] Fig.Figure 3 shows a flowchart illustrating a method for controlling a semiconductor switch according to one embodiment. The method can, in principle, comprise any steps suitable for realizing the previously described concept for a control device for a semiconductor switch or an electrical converter with such a control device. Similarly, the devices described above can also comprise any suitable components for implementing the method described below.

[0039] In step S1, a first output voltage V_pos and / or a second output voltage V_neg is provided. The first and second output voltages V_pos and V_neg, respectively, can be provided, for example, by means of a reference voltage device 12, in particular the reference voltage device 12 described above.

[0040] In step S2, a control signal is provided for the semiconductor switch. The control signal can, in particular, be provided to a control terminal of the semiconductor switch. The control signal is provided using the first output voltage and / or the second output voltage. The control signal can be provided, for example, by a driver device 13, in particular the driver devices 13 of the preceding control device 10.

[0041] The voltage level of the first output voltage and / or the voltage level of the second output voltage during the provision of the output voltages V_pos, V_neg can be set using external signaling. Such external signaling can be, for example, a bit or data word of a data frame received from a digital communication interface and / or a trigger signal at a trigger input.

[0042] In summary, the present invention relates to the control of a semiconductor switch. It is provided that the voltage level of the control signal is varied to control the semiconductor switch. In particular, the reference voltages for opening and closing the semiconductor switch can be varied. In this way, it is possible to set different configurations for the voltage level of the control signal for different operating states. QUOTES INCLUDED IN THE DESCRIPTION

[0000] This list of documents cited by the applicant was automatically generated and is included solely for the reader's convenience. The list is not part of the German patent or utility model application. The DPMA accepts no liability for any errors or omissions. Cited patent literature

[0000] DE 10 2020 206 478 A1

[0004]

Images