An apparatus and a method for driving power electronic switches

Abstract

An apparatus for driving a power electronic switch comprises a driver (101) for connecting an on-state control voltage (VGS_on) or an off-state control voltage (VGS_off) to a control terminal (G) of the power electronic switch depending on a state control signal (SC1). The apparatus comprises a supply circuitry (102) for forming the on-state and off-state control voltages and for supplying them to the driver. The supply circuitry comprises a controllable voltage converter (104) and a controller (103) for receiving information related to the power electronic switch and for controlling the controllable voltage converter to drive the on-state control voltage to a value dependent on the information. The apparatus is suitable for driving different power electronic switches which have different requirements concerning the on-state control voltage. Furthermore, the apparatus can be made adaptive to varying operating conditions, such as temperature, that may vary the requirements concerning the on-state control voltage.

Description

[0001] An apparatus and a method for driving power electronic switches

[0002] Field

[0003] The invention relates generally to control of power electronic switches such as silicon carbide “SiC” metal-oxide-semiconductor field-effect transistors “MOSFET” and gallium nitride “GaN” MOSFETs. More particularly, the invention relates to an apparatus and to a method for controlling at least one power electronic switch. Furthermore, the invention relates to a computer program for controlling a programmable apparatus to drive at least one power electronic switch.

[0004] Background

[0005] Wide band gap semiconductor components, such as for example silicon carbide “SiC” semiconductor components, are an advantageous choice in several upcoming applications, including electric vehicle “EV” chargers, energy storages, etc. Specifically, compared to traditional silicon “Si” semiconductor components, SiC semiconductor components can operate under higher temperatures, have lower switching losses thanks to fast switching transients, and have smaller threshold voltages and on-state resistances.

[0006] However, wide band gap semiconductor components from different component vendors may have different requirements concerning an on-state control voltage that is directed to a control terminal of a semiconductor component to drive the semiconductor component into a conductive state and to keep the semiconductor component in the conductive state. In conjunction with a SiC MOSFET, the on-state control voltage Vcs_on connected between the gate and source terminals of the SiC MOSFET has a significant effect on the drain-to-source on-resistance Ros_on of the SiC MOSFET. For example, about 5 % decrease in the on-state control voltage Vcs_on of a SiC MOSFET may cause about 15 % increase in the power losses in the SiC MOSFET. Therefore, operating a SiC MOSFET with an on-state control voltage that is sufficiently accurately an optimal on-state control voltage for the SiC MOSFET under consideration reduces thermal stresses and improves the efficiency of a system. The above-mentioned differences between semiconductor components from different component vendors leads to variation between requirements related to apparatuses for driving the semiconductor components from the different component vendors. This, in turn, causes additional costs related to product portfolio management, manufacturing, and storage.

[0007] Summary

[0008] The following presents a simplified summary to provide basic understanding of some aspects of various invention embodiments. The summary is not an extensive overview of the invention. It is neither intended to identify key or critical elements of the invention nor to delineate the scope of the invention. The following summary merely presents some concepts of the invention in a simplified form as a prelude to a more detailed description of exemplifying embodiments.

[0009] In accordance with the invention, there is provided a new apparatus for driving at least one power electronic switch such as a silicon carbide “SiC” metal-oxide- semiconductor field-effect transistor “MOSFET” or a gallium nitride “GaN” MOSFET.

[0010] An apparatus according to the invention comprises:

[0011] - a driver configured to receive a state control signal, to connect an on-state control voltage to a control terminal of the power electronic switch, e.g. a gate of a SiC MOSFET, when the state control signal has an on-value, and to connect an off-state control voltage to the control terminal of the power electronic switch when the state control signal has an off-value, and

[0012] - a supply circuitry configured to receive electric energy, to form the on-state control voltage and the off-state control voltage, and to supply the on-state control voltage and the off-state control voltage to the driver, wherein the supply circuitry comprises: a controllable voltage converter, and a controller configured to receive information related to the power electronic switch and to control the controllable voltage converter to drive the on-state control voltage to a value dependent on the information.

[0013] The above-described apparatus according to the invention is suitable for driving different power electronic switches which have different requirements concerning the on-state control voltage. This facilitates a use of components from different vendors in mass production, reduces costs especially in mass production, and reduces a need for storage room for components of power electronic devices to be manufactured. Furthermore, the apparatus can be made adaptive to varying operating conditions, such as e.g. temperature, that may vary the requirements concerning the on-state control voltage. This improves efficiency of power electronic devices especially in cases where the operating conditions have significant variation, e.g. there is significant temperature variation.

[0014] In accordance with the invention, there is also provided a new method for controlling at least one power electronic switch. The method comprises:

[0015] - receiving information related to the power electronic switch,

[0016] - receiving electric energy, forming the on-state control voltage so that the on- state control voltage is driven to a value dependent on the information, and forming off-state control voltage,

[0017] - connecting the on-state control voltage to a control terminal of the power electronic switch when a state control signal has an on-value, and

[0018] - connecting the off-state control voltage to the control terminal of the power electronic switch when the state control signal has an off-value.

[0019] In accordance with the invention, there is also provided a new computer program for controlling a programmable apparatus that comprises:

[0020] - a driver configured to receive a state control signal, to connect an on-state control voltage to a control terminal of a power electronic switch when the state control signal has an on-value, and to connect an off-state control voltage to the control terminal of the power electronic switch when the state control signal has an off-value,

[0021] - a supply circuitry configured to receive electric energy, to form the on-state control voltage and the off-state control voltage, and to supply the on-state control voltage and the off-state control voltage to the driver, and

[0022] - a programmable data processing system configured to control the supply circuitry.

[0023] The computer program comprises computer executable instructions for controlling the programmable data processing system to:

[0024] - receive information related to the power electronic switch, and

[0025] - control the supply circuitry to drive the on-state control voltage to a value dependent on the information.

[0026] In accordance with the invention, there is also provided a new computer program product. The computer program product comprises a non-volatile computer readable medium, e.g. a compact disc “CD”, encoded with a computer program according to the invention.

[0027] Exemplifying and non-limiting embodiments are described in accompanied dependent claims.

[0028] Various exemplifying and non-limiting embodiments both as to constructions and to methods of operation, together with additional objects and advantages thereof, will be best understood from the following description of specific exemplifying and nonlimiting embodiments when read in connection with the accompanying drawings.

[0029] The verbs “to comprise” and “to include” are used in this document as open limitations that neither exclude nor require the existence of unrecited features.

[0030] The features recited in dependent claims are mutually freely combinable unless otherwise explicitly stated. Furthermore, it is to be understood that the use of “a” or “an”, i.e. a singular form, throughout this document does not exclude a plurality.

[0031] Brief description of figures

[0032] Exemplifying and non-limiting embodiments and their advantages are explained in greater detail below in the sense of examples and with reference to the accompanying drawings, in which: figure 1 shows a block-diagram of an apparatus according to an exemplifying and non-limiting embodiment for controlling power electronic switches, and figure 2 shows a flowchart of a method according to an exemplifying and non-limiting embodiment for controlling at least one power electronic switch.

[0033] Description of exemplifying embodiments

[0034] The specific examples provided in the description given below should not be construed as limiting the scope and / or the applicability of the invention. Lists and groups of examples provided in the description given below are not exhaustive unless otherwise explicitly stated.

[0035] Figure 1 shows a block-diagram of an apparatus according to an exemplifying and non-limiting embodiment for controlling power electronic switches 111 and 112. In this exemplifying case the power electronic switches 111 and 112 are N-channel MOSFETs, but apparatuses according to embodiments of the invention are not limited to control of any specific types of power electronic switches.

[0036] The apparatus comprises a driver 101 configured to receive a state control signal SCi that can be for example a control signal based on pulse width modulation “PWM”. The driver 101 is configured to connect an on-state control voltage VGS_on to a control terminal, i.e. a gate G, of the power electronic switch 111 when the state control signal SCi has an on-value i.e. a value corresponding to a conductive state of the power electronic switch 111. Correspondingly, the driver 101 is configured to connect an off-state control voltage VGS_off to the control terminal of the power electronic switch 111 when the state control signal SCi has an off-value i.e. a value corresponding to a non-conductive state of the power electronic switch 111. In this exemplifying case, the on-state control voltage VGS_on and the off-state control voltage VGS_off are values of a voltage VGS applied between the gate G and the source S of the power electronic switch 111. The power electronic switch 112 is controlled in a corresponding way based on a state control signal SC2. Without limiting the generality, the considerations presented below can be limited to the control of the power electronic switch 111.

[0037] The apparatus comprises a supply circuitry 102 configured to receive electric energy. In this exemplifying case, the electric energy is received via an input connected to a supply voltage Vsp. The supply circuitry 102 comprises a controllable voltage converter 104 that is configured to form the above-mentioned on-state control voltage VGS_on and the above-mentioned off-state control voltage VGS_off, and to feed the on-state control voltage and the off-state control voltage to the driver 101 . The supply circuitry 102 comprises a controller 103 that is configured to receive information related to the power electronic switch 111 and to control the controllable voltage converter to drive the on-state control voltage VGS_on to a value dependent on the information. The information related to the power electronic switch 111 may comprise static information related to the power electronic switch 111 as such and independent of operating conditions of the power electronic switch 111. The static information may express for example a type of the power electronic switch 111 , and the static information can be available e.g. in a datasheet or the like provided by a vendor of the power electronic switch 111. The controller 103 is advantageously configured to control the controllable voltage converter to drive the on-state control voltage to a value dependent on the static information, e.g. the type of the power electronic switch 111.

[0038] The exemplifying apparatus illustrated in figure 1 comprises an identifier resistor 107 whose resistance represents the above-mentioned static information. The supply circuitry 102 comprises a measurement circuit 105 that is configured to produce a signal dependent on the resistance and representing the above-mentioned static information. Furthermore, it can be checked, e.g. by the controller 103, whether the measured signal belongs to one of predefined value-windows each corresponding to for example a given type of the power electronic switch 111. In this exemplifying case, the controller 103 is configured to control the controllable voltage converter 104 to drive the on-state control voltage VGS_on to a value associated with the one of the predefined value-windows to which the measured signal belongs. In exemplifying cases where the controller 103 is a digital controller, it is also possible that the static information is set as one or more digital configuration parameters of the digital controller. As an example, the one or more digital configuration parameters can be set during manufacturing, testing, or commissioning according to the assembled power electronic switch type. It is also possible, that the process of setting the one or more digital configuration parameters is done automatically based on switch type found from a Bill of Material “BOM” during manufacturing and / or assembly. Automation can be also designed to choose the identifier resistor 107 according to a switch type at the BOM for example in the case wherein it is needed to swap switch component from first source to second source, or vice versa.

[0039] Furthermore, the information related to the power electronic switch 111 may comprise dynamic information dependent on one or more operating conditions of the power electronic switch 111. Preferably, the dynamic information is dependent on one or more on-state operating conditions of the power electronic switch 111 i.e. on one or more operating conditions of the power electronic switch 111 when the power electronic switch 111 is in the conductive state. The dynamic information may express for example temperature of the power electronic switch 111 , electric current of the power electronic switch 111 , voltage over the power electronic switch 111 , and / or one or more other non-static quantities related to the power electronic switch 111. Preferably, the non-static quantities relate to directly or indirectly to the on-state behavior of the power electronic switch 111 , e.g. to the on-state resistance and / or effects of it to the system. In this exemplifying case, the controller 103 is configured to change the on-state control voltage VGS_on in response to a change of the dynamic information. The exemplifying apparatus illustrated in figure 1 comprises a temperature sensor 110 for producing a temperature signal indicative of the temperature of the power electronic switch 111. The temperature sensor 1 10 may have a mechanical contact with semiconductor material of the power electronic switch 111 in which case the temperature signal is directly indicative of the temperature of the power electronic switch 111 , or the temperature sensor 110 may have a mechanical contact with e.g. a cooling element attached to the power electronic switch 111 in which case the temperature signal is indirectly indicative of the temperature of the power electronic switch 111. In this exemplifying case, the controller 103 is configured to change the on-state control voltage VGS_on farther from zero in response to a change of the temperature signal indicative of an increase of the temperature of the power electronic switch 111. In the exemplifying case illustrated in figure 1 where the power electronic switch 111 is an N-channel MOSFET, the positive on-state control voltage VGS_on can be increased in response to an increase in the temperature in order to bring more charge carriers in the channel of the N-channel MOSFET and thereby to decrease the channel on- resistance. According to an exemplifying and non-limiting embodiment, the controller 103 adjusts the on-state control voltage VGS_on within an allowed adjustment window according to the dynamic information. For example, for an exemplary switch type it could be defined in a datasheet an allowed on-state control voltage VGS_on range from 20V to 28V, and the controller 103 would initially set the on-state control voltage VGS_on for example to 24V based on the static information, and would be allowed to adjust the on-state control voltage VGS_on between 20V and 28V depending on the received dynamic information, such as e.g. the temperature of the power electronic switch 111.

[0040] In conjunction with an apparatus according to an exemplifying and non-limiting embodiment, the off-state control voltage VGS_off can be constant or, alternatively, the off-state control voltage VGS_off can be controlled based on the abovediscussed static information and / or the dynamic information.

[0041] In an apparatus according to an exemplifying and non-limiting embodiment, the controllable voltage converter 104 comprises an isolating circuitry configured to provide galvanic isolation between an input of the controllable voltage converter 104 configured to receive the electric energy and an output of the controllable voltage converter 104 connected to the driver 101. The controllable voltage converter 104 may comprise for example a buck-boost converter 109 and a direct voltage isolated converter 108 that is between the controllable buck-boost converter 109 and the driver 101 . The direct voltage isolated converter 108 may comprise for example an inverter for converting a direct voltage Vi to an alternating voltage, a transformer for providing the galvanic isolation, and a rectifier for converting an alternating voltage of the secondary side of the transformer to a direct voltage. The transformer may comprise many secondary windings which are connected to many rectifiers, respectively, such that different ones of the secondary windings and rectifiers have different common mode voltage levels to provide control voltages for power electronic switches at different potential levels. For another example, the controllable voltage converter 104 can be a controllable flyback converter that can be like a buck-boost converter where an inductor is split to form a transformer to provide galvanic isolation. Depending on a case it is however also possible that an apparatus according to an exemplifying and non-limiting embodiment has no galvanic isolation of the kind discussed above.

[0042] In an apparatus according to an exemplifying and non-limiting embodiment, the supply circuitry 102 comprises a measurement circuitry 106 configured to measure the on-state control voltage Vcs_on at an output of the controllable voltage converter 104. The controller 103 is configured to form an error between a target value of the on-state control voltage and the measured on-state control voltage, and to control the controllable voltage converter 104 to drive the error towards zero. The abovedescribed feedback control improves the accuracy of the on-state control voltage Vcs_on compared to a mere direct-branch control of the on-state control voltage Vcs_on.

[0043] The implementation of the controller 103 can be based on one or more analogue circuits, one or more digital processing circuits, or a combination thereof. Each digital processing circuit can be a programmable processor circuit provided with appropriate software, a dedicated hardware processor such as for example an application specific integrated circuit “ASIC”, or a configurable hardware processor such as for example a field programmable gate array “FPGA”. Furthermore, the controller 103 may comprise one or more memory circuits each of which can be for example a random-access memory “RAM” circuit.

[0044] Figure 2 shows a flowchart of a method according to an exemplifying and nonlimiting embodiment for controlling at least one power electronic switch. The method comprises the following actions: action 201 : receiving information related to the power electronic switch,

[0045] - action 202: receiving electric energy, forming an on-state control voltage so that the on-state control voltage is driven to a value dependent on the information, and forming an off-state control voltage,

[0046] - action 203: connecting the on-state control voltage to a control terminal of the power electronic switch when a state control signal has an on-value, and

[0047] - action 204: connecting the off-state control voltage to the control terminal of the power electronic switch when the state control signal has an off-value.

[0048] In a method according to an exemplifying and non-limiting embodiment, the information related to the power electronic switch comprises static information related to the power electronic switch as such and independent of operating conditions of the power electronic switch, and the on-state control voltage is driven to a value dependent on the static information.

[0049] A method according to an exemplifying and non-limiting embodiment comprises producing a signal dependent on resistance of an identifier resistor whose resistance represents the static information.

[0050] In a method according to an exemplifying and non-limiting embodiment, the information related to the power electronic switch comprises dynamic information dependent on one or more operating conditions of the power electronic switch, and the on-state control voltage is changed in response to a change of the dynamic information.

[0051] A method according to an exemplifying and non-limiting embodiment comprises receiving a temperature signal expressing temperature of the power electronic switch, the temperature signal representing at least a part of the above-mentioned dynamic information. The method according to this exemplifying embodiment comprises changing the on-state control voltage farther from zero in response to a change of the temperature signal indicative of an increase of the temperature of the power electronic switch. In a method according to an exemplifying and non-limiting embodiment, galvanic isolation is provided between an input and an output of a controllable voltage converter that forms the on-state control voltage (Vcs_on) and the off-state control voltage (Vcs_off).

[0052] In a method according to an exemplifying and non-limiting embodiment, the above- mentioned controllable voltage converter comprises a controllable buck-boost converter and a direct voltage isolated converter connected to an output of the buckboost converter.

[0053] A method according to an exemplifying and non-limiting embodiment comprises measuring the on-state control voltage, forming an error between a target value of the on-state control voltage and the measured on-state control voltage, and controlling the controllable voltage converter to drive the error towards zero.

[0054] A computer program according to an exemplifying and non-limiting embodiment comprises computer executable instructions for controlling a programmable data processing system to carry out actions related to a method according to any of the above-described exemplifying and non-limiting embodiments.

[0055] A computer program according to an exemplifying and non-limiting embodiment comprises software modules for controlling a programmable apparatus to drive at least one power electronic switch, the programmable apparatus comprising:

[0056] - a driver configured to receive a state control signal, to connect an on-state control voltage Vcs_on to a control terminal of the power electronic switch when the state control signal has an on-value, and to connect an off-state control voltage Vcs_off to the control terminal of the power electronic switch when the state control signal has an off-value,

[0057] - a supply circuitry configured to receive electric energy, to form the on-state control voltage and the off-state control voltage, and to supply the on-state control voltage and the off-state control voltage to the driver, and a programmable data processing system configured to control the supply circuitry. The software modules comprise computer executable instructions for controlling the programmable data processing system to:

[0058] - receive information related to the power electronic switch, and

[0059] - control the supply circuitry to drive the on-state control voltage to a value dependent on the information.

[0060] The software modules can be for example subroutines or functions implemented with programming tools suitable for the programmable data processing system.

[0061] A computer program product according to an exemplifying and non-limiting embodiment comprises a computer readable medium, e.g. a compact disc “CD”, encoded with a computer program according to an exemplifying embodiment of invention.

[0062] A non-volatile computer readable medium according to an exemplifying and nonlimiting embodiment is encoded with a computer program according to an exemplifying embodiment of invention.

[0063] A signal according to an exemplifying and non-limiting embodiment is encoded to carry information defining a computer program according to an exemplifying embodiment of invention.

[0064] The specific examples provided in the description given above should not be construed as limiting the applicability and / or the interpretation of the invention. Lists and groups of examples provided in the description given above are not exhaustive unless otherwise explicitly stated.

Claims

What is claimed is:

1. An apparatus for controlling at least one power electronic switch (111 , 112), the apparatus comprising:- a driver (101 ) configured to receive a state control signal (SCi), to connect an on-state control voltage (Vcs_on) to a control terminal (G) of the power electronic switch when the state control signal has an on-value, and to connect an off-state control voltage (Vcs_off) to the control terminal of the power electronic switch when the state control signal has an off-value, and- a supply circuitry (102) configured to receive electric energy, to form the on- state control voltage and the off-state control voltage, and to supply the on- state control voltage and the off-state control voltage to the driver, characterized in that the supply circuitry comprises:- a controllable voltage converter (104), and- a controller (103) configured to receive information related to the power electronic switch (111 ) and to control the controllable voltage converter (104) to drive the on-state control voltage to a value dependent on the information.

2. An apparatus according to claim 1 , wherein the information related to the power electronic switch comprises static information related to the power electronic switch as such and independent of operating conditions of the power electronic switch, and the controller is configured to control the controllable voltage converter to drive the on-state control voltage to the value dependent on the static information.

3. An apparatus according to claim 2, wherein the apparatus comprises an identifier resistor (107) whose resistance represents the static information, and the supply circuitry comprises a measurement circuit (105) configured to produce a signal dependent on the resistance.

4. An apparatus according to any one of claims 1 -4, wherein the information related to the power electronic switch comprises dynamic information dependent on one or more operating conditions of the power electronic switch, and the controlleris configured to change the on-state control voltage in response to a change of the dynamic information.

5. An apparatus according to claim 4, wherein the controller is configured to receive a temperature signal indicative of temperature of the power electronic switch and representing at least a part of the dynamic information, and to change the on- state control voltage farther from zero in response to a change of the temperature signal indicative of an increase of the temperature of the power electronic switch.

6. An apparatus according to any one of claims 1 -5, wherein the controllable voltage converter (104) comprises an isolating circuitry configured to provide galvanic isolation between an input of the controllable voltage converter configured to receive the electric energy and an output of the controllable voltage converter connected to the driver.

7. An apparatus according to claim 6, wherein the controllable voltage converter comprises a controllable buck-boost converter (109) and a direct voltage isolated converter (108) between the controllable buck-boost converter and the driver.

8. An apparatus according to any one of claims 1 -7, wherein the controllable voltage converter comprises a measurement circuitry (106) configured to measure the on-state control voltage (Vcs_on) at an output of the controllable voltage converter (104), and the controller (103) is configured to form an error between a target value of the on-state control voltage and the measured on-state control voltage, and to control the controllable voltage converter to drive the error towards zero.

9. A method for controlling at least one power electronic switch, the method comprising:- receiving (202) electric energy and forming (202) an on-state control voltage (Vcs_on) and an off-state control voltage (Vcs_off),- connecting (203) the on-state control voltage to a control terminal (G) of the power electronic switch when a state control signal (SCi) has an on-value, andconnecting (204) the off-state control voltage to the control terminal of the power electronic switch when the state control signal has an off-value, characterized in that the method comprises:- receiving (201 ) information related to the power electronic switch,- driving (202) the on-state control voltage to a value dependent on the information.

10. A method according to claim 9, wherein the information related to the power electronic switch comprises static information related to the power electronic switch as such and independent of operating conditions of the power electronic switch, and the on-state control voltage is driven to a value dependent on the static information.

11. A method according to claim 10, wherein the method comprises producing a signal dependent on resistance of an identifier resistor whose resistance represents the static information.

12. A method according to any one of claims 9-11 , wherein the information related to the power electronic switch comprises dynamic information dependent on one or more operating conditions of the power electronic switch, and the on-state control voltage is changed in response to a change of the dynamic information.

13. A method according to claim 12, wherein the method comprises receiving a temperature signal expressing temperature of the power electronic switch and representing at least a part of the dynamic information, and the method comprises changing the on-state control voltage farther from zero in response to a change of the temperature signal indicative of an increase of the temperature of the power electronic switch.

14. A method according to any one of claims 9-13, wherein galvanic isolation is provided between an input and an output of a controllable voltage converter that forms the on-state control voltage (Vcs_on) and the off-state control voltage (VGs_off).

15. A method according to claim 14, wherein the controllable voltage converter comprises a controllable buck-boost converter and a direct voltage isolated converter connected to an output of the buck-boost converter.

16. A method according to any one of claims 9-15, wherein the method comprises measuring the on-state control voltage, forming an error between a target value of the on-state control voltage and the measured on-state control voltage, and controlling a controllable voltage converter to drive the error towards zero.

17. A computer program for controlling a programmable apparatus to drive at least one power electronic switch, the programmable apparatus comprising:- a driver configured to receive a state control signal (SCi), to connect an on- state control voltage (Vcs_on) to a control terminal (G) of the power electronic switch when the state control signal has an on-value, and to connect an off- state control voltage (Vcs_off) to the control terminal of the power electronic switch when the state control signal has an off-value,- a supply circuitry configured to receive electric energy, to form the on-state control voltage and the off-state control voltage, and to supply the on-state control voltage and the off-state control voltage to the driver, and- a programmable data processing system configured to control the supply circuitry, characterized in that the computer program comprises computer executable instructions for controlling the programmable data processing system to:- receive information related to the power electronic switch, and- control the supply circuitry to drive the on-state control voltage to a value dependent on the information.

18. A non-volatile computer readable medium encoded with a computer program according to claim 17.

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