This application claims priority to German Application Number 102020123149.0 filed on Sep. 4, 2020, the entire content of which is incorporated herein by reference.
The present description relates to a control circuit for an electronic switch which can be used in so called smart power switches, for example, as well as to a corresponding method for controlling an electronic switch.
Electromechanical components such as relays and safety fuses, for example, are increasingly being replaced by electronic switches. In particular, this applies to automotive applications. Modern concepts make provision for supplying electrical loads via decentralized load distribution nodes (power distribution nodes), for example, rather than bringing together all lines centrally in a distribution box in which the fuses are conventionally also located.
Electronic switches usually comprise a switch element, such as, for example, a transistor (MOSFET, IGBT, BJT or the like) and a control circuit (driver circuit). The control circuit is usually constructed in such a way that the switch element disconnects the connection between on-board power supply and load if the supply voltage is too low (undervoltage shutdown). This serves the self-protection of the electronic switch and also serves to protect the on-board power supply. Various standards (in the automotive sector LV124, for example, a test standard of German automotive manufacturers since 2013) make provision for the fact that an electronic switch must be switched on again after an undervoltage shutdown, after the supply voltage has risen to a normal value again. There are also tests in which the behavior of electronic switches and electronic control units (ECUs) is tested in the case of very short interruptions in the supply voltage (so called “micro cuts”).
An undervoltage can have different causes. On the one hand, problems on the supply side (such as, for example, a weak battery, insufficient electrical contacts, etc.) can result in an undervoltage, on the other hand, a short circuit or an overload on the load side can also result in an undervoltage. A short circuit in the load usually results in a drop in the supply voltage at the supply pin of the electronic switch, via which the load is supplied. In a situation of this type, the control circuit of the electronic switch identifies an undervoltage and switches off the switch element, whereby the load is disconnected from the onboard power supply. As a result, the current flow through the (short circuited) load is interrupted and the supply voltage will rise to a normal value again, whereupon the electronic switch switches on again and an undervoltage occurs once again. The result of this is a toggling with high power dissipation in the switch element. In order to avoid the electronic switch overheating, conventional control circuits are usually constructed in such a way that the control circuit waits a specific delay time (e.g. 5 mins) before switching back on is attempted. This gives the switch sufficient time to cool down.
The aforementioned solution (delay before switching back on) is suitable for controlling simple loads but not for applications in the main power distribution system of a motor vehicle, in the case of which not one individual load but rather a subsystem or a group of subsystems with a multiplicity of loads is supplied via an electronic switch. In applications of this type, it is desirable for the electronic switch to be reactivated without significant delay (i.e. within a few microseconds) after a shutdown as a result of undervoltage, provided that the undervoltage was not caused by a short circuit. One underlying object of the invention can therefore be seen in improving and making more flexible the control circuit in electronic switches and corresponding methods.
The aforementioned object is achieved by way of the method according to Claim 1 as well as the circuit according to Claim 9. Various exemplary embodiments and developments are the subject matter of the dependent claims.
A method for operating an electronic switch is described hereinafter. According to one exemplary embodiment, the method (for an electronic switch in the switched on state) comprises detecting whether there is an undervoltage condition at a supply voltage node and providing an undervoltage signal which indicates an undervoltage condition. The method further comprises switching off the electronic switch if the undervoltage signal indicates an undervoltage condition and switching (back) on the electronic switch if the undervoltage signal no longer indicates an undervoltage condition. If the undervoltage signal indicates an undervoltage condition during a switch-on process of the electronic switch, the electronic switch is switched off again and switching back on is prevented for a defined period of time, irrespective of the undervoltage signal.
Moreover, a corresponding circuit is described which is designed to carry out the above mentioned method.
Various exemplary embodiments are explained in greater detail hereinafter using the examples represented in the illustrations. The representations are not necessarily to scale and the invention is not merely limited to the aspects represented. In fact, emphasis is placed on representing the underlying principles of the exemplary embodiments represented. In the illustrations:
The control signal VG is generated by the driver circuit 11 depending on an input signal SIN, wherein the function of the driver circuit 11 shall be explained in greater detail later on. The driver circuit 11 is also connected to the supply voltage node NSUP and a ground node GND.
The supply voltage node NSUP is connected to a voltage source, for example a vehicle battery, via a line. In the example, this line is symbolized by the inductance Ls and the resistance RS. In this case, inductance Ls and resistance RS do not refer to independent components but rather are parasitic properties of the line. In the present example, the source voltage VB (battery voltage) is assumed to be 13.8V. The supply voltage VS which is available at the supply voltage node NSUP can deviate from the source voltage VB. This is the case in particular with high load currents iL and fast current changes diL/dt.
The driver circuit 11 is designed to detect an undervoltage condition which is defined by the fact that the supply voltage VS falls below a specific threshold value VUV (i.e. VS<VUV), and to switch off the transistor TS in response to an undervoltage condition, provided that an undervoltage condition is present. If an undervoltage condition is no longer detected, the transistor (if applicable after an additional delay time) is switched on again. It is understood that in the case of a detected undervoltage condition, the transistor TS is switched off irrespective of the level of the input signal SIN. The input signal SIN is a logic signal which only indicates the nominal condition of the transistor TS (switched on or switched off). The actual condition can deviate from the nominal condition “switched on” depending on other influencing factors (among other things as a result of detecting an undervoltage condition). If the input signal SIN indicates that the transistor TS should be switched off, the driver circuit 11 will always switch off the transistor TS or prevent the transistor TS from being switched on. For further discussion, it is assumed that the input signal SIN signals a switched on condition of the transistor.
As mentioned at the outset, an undervoltage condition can have different causes. For example, problems on the supply side (such as, for example, a weak battery, loose connections, etc.) can result in a supply voltage which is too low (“too low” in this case means VS<VUV). Moreover, a short circuit or an overload on the load side can also result in an undervoltage condition. There are standardized test which check the behavior of electronic switches with regard to undervoltage conditions. One example of a test sample is represented in
In
As mentioned at the outset, switching off as a result of detecting an undervoltage condition (undervoltage shutdown) results in a toggling (continuously switching the transistor off and on again), provided that the cause of the undervoltage condition is a short circuit on the load side or an overload. After the undervoltage shutdown, the supply voltage VS will rise above the threshold value VUV again (since a load current no longer flows), which causes the driver circuit 11 to switch on the transistor again. After the transistor TS is switched on again, the short circuit or the overload will immediately result in an undervoltage condition again, and the next cycle begins. As mentioned, driver circuits are usually constructed in such a way that after an undervoltage shutdown, a delay time tDEL of a few milliseconds is waited before switching on again, in order to limit the frequency of the toggling and to prevent overheating of the electronic switch.
The aforementioned delay time tDEL does indeed protect the transistor TS against overheating in the event of a short circuit but it is mostly undesirable in other situations. For this reason, in the exemplary embodiments described herein, the driver circuit is constructed in such a way that after an undervoltage shutdown, a delay time before switching on again is only incorporated if an undervoltage condition was detected previously during a switch-on process (i.e. during the rise time tR, for example). One example of this concept is represented in
The timing diagrams from
In the third situation, a short circuit is the cause of the undervoltage condition. As soon as the signal SUV indicates an undervoltage condition (SUV=High), the transistor TS is switched off (VG=Low). As mentioned, switching off the transistor TS also results in the load current iL being switched off and thus in a “recovery” of the supply voltage VS. This means that the transistor TS is switched on again (VG=High) immediately. However, in the event of a short circuit, an undervoltage condition will be detected again already during the switch-on process. Therefore, if a further undervoltage condition is detected during the switch-on process, the transistor is switched off again (VG=Low) immediately and the transistor TS is prevented from switching back on again for a defined period of time (delay time tDEL). This delay time tDEL is significantly longer than the typical fall time tF or the rise time tR in normal switching processes of a transistor.
As can be seen in
The concept represented in
Examples of possible implementations are explained hereinafter using simplified circuit diagrams.
As explained above with reference to
The condition “during a switch-on process of the transistor” is detected in the example represented in
Alternatively to the drain source voltage VDS, the gate source voltage VGS can also be supplied to the window comparator. In this case, the window comparator 104 is designed in such a way that it outputs a high level if and as long as the condition VL<VGS<VH is met. In this case, the threshold values VL and VH are between 0V and a maximum gate voltage VGS,max.
The example in
The example from
It is understood that the function of the circuits from
Moreover, it is understood that the functions described herein may also be provided by a processor which is designed to execute software instructions. A combination of software (firmware) that must be executed by a processor and hard-wired logic circuitry is also possible. An implementation as a hard-wired logic circuit without a processor is also possible. In this case, the functions described herein are provided by a finite state machine, for example. This can be realized in an FPGA (Field Programmable Gate Array) or also as an ASIC (Application Specific Integrated Circuit), for example.
Number | Date | Country | Kind |
---|---|---|---|
102020123149.0 | Sep 2020 | DE | national |
Number | Name | Date | Kind |
---|---|---|---|
5517379 | Williams et al. | May 1996 | A |
5719509 | Chan | Feb 1998 | A |
5862390 | Ranjan | Jan 1999 | A |
5877647 | Vajapey et al. | Mar 1999 | A |
6060792 | Pelly | May 2000 | A |
6144085 | Barker | Nov 2000 | A |
6166502 | Pattok et al. | Dec 2000 | A |
6924669 | Itoh et al. | Aug 2005 | B2 |
7279765 | Ahn et al. | Oct 2007 | B2 |
7489855 | Kraus | Feb 2009 | B2 |
8018245 | Sohn | Sep 2011 | B2 |
8155916 | Baginski et al. | Apr 2012 | B2 |
9293907 | Ueta et al. | Mar 2016 | B2 |
9413352 | Lim | Aug 2016 | B2 |
9672201 | Uszkoreit et al. | Jun 2017 | B1 |
9705394 | Ohshima | Jul 2017 | B2 |
9887532 | Djelassi et al. | Feb 2018 | B2 |
9954548 | Illing et al. | Apr 2018 | B2 |
10170905 | Illing et al. | Jan 2019 | B2 |
10305363 | Chen et al. | May 2019 | B1 |
10868418 | Djelassi-Tscheck et al. | Dec 2020 | B2 |
10897247 | Marques Martins et al. | Jan 2021 | B2 |
10972088 | Barrenscheen et al. | Apr 2021 | B1 |
11018664 | Bernardoni et al. | May 2021 | B2 |
11177644 | Mayer et al. | Nov 2021 | B2 |
20020024376 | Sander | Feb 2002 | A1 |
20030001533 | Kleinau et al. | Jan 2003 | A1 |
20050007711 | Liu | Jan 2005 | A1 |
20050184715 | Kidokoro et al. | Aug 2005 | A1 |
20050270869 | Krischke et al. | Dec 2005 | A1 |
20060016891 | Giebel | Jan 2006 | A1 |
20070008744 | Heo et al. | Jan 2007 | A1 |
20070194009 | Seger | Aug 2007 | A1 |
20100103705 | Fang | Apr 2010 | A1 |
20120194119 | Kroeze et al. | Aug 2012 | A1 |
20130082627 | Ichikawa et al. | Apr 2013 | A1 |
20130301175 | Posat | Nov 2013 | A1 |
20140078629 | Cortigiani et al. | Mar 2014 | A1 |
20140091384 | Petruzzi et al. | Apr 2014 | A1 |
20140167827 | Hernandez-Distancia | Jun 2014 | A1 |
20150226787 | Mankel et al. | Aug 2015 | A1 |
20150285843 | Michal | Oct 2015 | A1 |
20150381152 | Choi et al. | Dec 2015 | A1 |
20170063077 | Donath et al. | Mar 2017 | A1 |
20170063367 | Tsurumaru | Mar 2017 | A1 |
20170294772 | Illing et al. | Oct 2017 | A1 |
20170294918 | Illing et al. | Oct 2017 | A1 |
20170294922 | Illing et al. | Oct 2017 | A1 |
20170338737 | Kohama | Nov 2017 | A1 |
20170358512 | Kakimoto | Dec 2017 | A1 |
20170366116 | Ogawa et al. | Dec 2017 | A1 |
20180048140 | Takuma et al. | Feb 2018 | A1 |
20180102774 | Leong et al. | Apr 2018 | A1 |
20180138904 | Nagase | May 2018 | A1 |
20180219543 | Komo et al. | Aug 2018 | A1 |
20180248351 | Vail et al. | Aug 2018 | A1 |
20180287365 | Djelassi-Tscheck et al. | Oct 2018 | A1 |
20190043969 | Wood | Feb 2019 | A1 |
20190131863 | El Markhi et al. | May 2019 | A1 |
20190204889 | Kaeriyama et al. | Jul 2019 | A1 |
20190356161 | Wakazono et al. | Nov 2019 | A1 |
20200021207 | Donat et al. | Jan 2020 | A1 |
20200132725 | Krummenacher et al. | Apr 2020 | A1 |
20210028780 | Mayer et al. | Jan 2021 | A1 |
20210028781 | Mayer et al. | Jan 2021 | A1 |
20210050718 | Djelassi-tscheck et al. | Feb 2021 | A1 |
20210050848 | Bernardoni et al. | Feb 2021 | A1 |
20210050850 | Djelassi-tscheck et al. | Feb 2021 | A1 |
Number | Date | Country |
---|---|---|
102004063946 | Mar 2006 | DE |
102016100498 | Jul 2016 | DE |
102015144460 | Mar 2017 | DE |
102017107520 | Nov 2017 | DE |
102017107523 | Nov 2017 | DE |
102017106896 | Oct 2018 | DE |
2549934 | Nov 2017 | GB |
2004023846 | Jan 2004 | JP |
20150141404 | Dec 2015 | KR |
101807300 | Dec 2017 | KR |
0169784 | Sep 2001 | WO |
Entry |
---|
Machine Translation of JP-2004023846-A. (Year: 2004). |
Infineon Technologies AG, “BTN8962TA High Current PN Half Bridge NovalithIC™,” Data Sheet, Rev. 1.0, May 17, 2013, 26 pp. |
Jain et al., “Analysis and Design of Digital IIR Integrators and Differentiators Using Minimax and Pole, Zero, and Constant Optimization Methods,” accepted May 2013, 15 pp. |
Oppeheim et al., “Discrete-Time Signal Processing,” Sec. 6.3, Second Edition, ISBN 0-13-754920.2, 1999, 5 pp. (Applicant points out, in accordance with MPEP 609.04(a), that the year of publication, 1999, is sufficiently earlier than the effective U.S. filing date, so that the particular month of publication is not in issue.). |
U.S. Appl. No. 17/009,718, filed Sep. 1, 2020, naming inventors Barrenscheen et al. |
International Standard ISO 7637-2, Third Edition, Mar. 1, 2011, entitled “Road vehicles-Electrical disturbances from conduction and coupling-Part 2: Electrical transient conduction along supply lines only,” 48 pp. |
International Standard ISO 26262-1, Second Edition, Dec. 2018, entitled “Road vehicles-Functional safety-Part 1: Vocabulary,” 42 pp. |
Number | Date | Country | |
---|---|---|---|
20220077674 A1 | Mar 2022 | US |