Power consumption reduction of a relay circuit for electric vehicles at high operating voltages

Abstract

Method for operating a relay (R1) by means of a device, wherein the device comprises a control signal (AS), a switching element (T1), a control input (Sig), a supply voltage line (VDD) at the supply voltage potential (VBat), a reference potential line (GND) at a reference potential, the relay (R1) having a relay coil (L), a relay switch (S), an armature, the relay coil (R1) controlling the relay switching state of the relay switch (S) as a function of a relay current (IRel) via its magnetic field and the resulting magnetic force on the armature, the relay (R1) being supplied with electrical energy by means of a supply voltage (Vbat), and the relay (R1) being in an on state.in which the relay coil (L) is energized with the relay current (IRel) and the relay switch (S) is closed, and wherein the relay (R1) has an off state in which the relay coil (L) is not energized with the relay current (IRel) and the relay switch (S) is open, and wherein the electrical relay current (IRel) depends on the switching state of the switching element (T1), and wherein the relay (R1) is supplied with a non-modulated relay voltage (VRel) when switched on if the magnitude of the supply voltage (Vbat) is below a first threshold (VNom), and wherein the relay (R1) is supplied with a relay voltage (VRel) modulated by a modulation signal when switched on if the magnitude of the supply voltage (Vbat) is above the first threshold (VNom).The process comprises the following steps: detecting a value of the supply voltage (VBat); generating the control signal (AS) depending on the state of the control input (Sig) and the detected value of the supply voltage (VBat) and / or a detected value of the relay current (IRel) through the relay coil (L); connecting the supply voltage line (VDD) at the supply voltage potential (VBat) to a first terminal of the relay coil (L) of the relay (R1) or disconnecting the supply voltage line (VDD) at the supply voltage potential (VBat) from the first terminal of the relay coil (L) of the relay (R1) by the switching element (T1) depending on the control signal (AS), wherein the second terminal of the relay coil (L) is connected to the reference potential line (GND).

Description

General term

[0001] The invention relates to a device for supplying the relay coil ( L ) of a relay ( R1 ) with a relay voltage ( V Rel ), where the supply voltage (V Bat ) into a first voltage range ( V NoPWM ) and a second voltage range (V PWM ) is divided and wherein the device supplies the relay voltage ( V Rel ) in the first voltage range ( V NoPWM ) not modulated and wherein the device controls the relay voltage ( V Rel ) in the second voltage range (V PWM ) modulated, in particular pulse-modulated and / or PWM-modulated and / or PDM-modulated. Corresponding methods and uses, as well as a test application of the proposed device, are also described. General Introduction

[0002] As electric vehicles become more widespread, the need to connect or disconnect lines at high voltages using suitable switches is becoming increasingly important. This requires meeting galvanic isolation requirements, which even today make the use of relays seem advisable.

[0003] This leads to a problem with power consumption, which is described in the Fig. 1, Fig. 2, and Fig.This is explained in section 5. To meet the requirements, the control circuit and the relay coil must be designed for both low and high supply voltages. To ensure a minimum holding force even at low supply voltages, the relay coil must generate a minimum magnetic field. However, to avoid excessive losses at very high operating voltages, the relay coil must not have too many turns. Consequently, the relay coil becomes large and therefore expensive. The same applies to the switching element of the relay's control circuit. This is typically a MOS transistor whose current-carrying capacity must be designed for the high currents at maximum supply voltage. Task

[0004] The proposal is therefore based on the task of creating a solution that avoids the aforementioned disadvantages of the prior art and offers further advantages. The aim is to reduce power losses in the switching element and the relay coil, which allows for a miniaturization of these two components and thus a reduction in costs.

[0005] This problem is solved by a device according to claim ... and a method according to claim .... Solution to the task

[0006] The core idea of ​​the proposal presented here is the use of a relay coil ( L ) as the choke inductance of a switching regulator and the use of the switching element ( T1 ), which was previously only used to switch the relay on and off ( R1 ) was used as a switching element of this switching regulator, so that the excessively high supply voltage on the supply voltage line ( VDD) can be reduced to an acceptable value by this virtual new switching regulator. That is, if the supply voltage ( V bat ) on the supply voltage line ( VDD ) above a first threshold ( V Nom ), so the switching control operation is initiated and the relay coil voltage is modulated by PWM ( V Rel ) by utilizing the smoothing of the relay current ( I Rel ) through the relay coil ( L ) the effective average relay coil voltage ( V Rel ) reduced, and thus also the relay current ( I Rel ) through the relay coil ( L ) reduced in size. This also reduces the size of the switching element ( T1 ), which is used to control the relay (r1), has a higher on-resistance ( R on ) exhibit, since the lower relay current ( I Rel ) to a lower power loss in the switching element ( T1 ) leads. Is the switching element ( T1For example, if a MOS transistor is used in a micro-integrated circuit, the chip area of ​​such a transistor can be greatly reduced, which provides a significant, competitive advantage. Voltage control

[0007] This virtual switching regulator therefore typically has a control input ( One ) which is intended to control the state of the relay. Thus, this control input ( One ) typically has at least one first state, hereinafter referred to as the on state, and one second state, hereinafter referred to as the off state. The control input information is therefore preferably binary or digitally encoded. Analog encoding is uncommon, but conceivable. This virtual switching regulator has a supply voltage line ( VDD ) on a supply voltage ( V bat ) compared to a reference potential in a reference potential line ( GND) which supplies the virtual switching regulator with electrical energy. The virtual switching regulator also includes means ( World Cup ) to detect the supply voltage ( V bat ). where the switching regulator is in the off state except for the current ( I d ) through a freewheeling diode that may be present ( D1 ) the relay coil ( L ) not powered and where the switching regulator is connected to the relay coil in the on state ( L ) a relay coil voltage ( V Rel ) which is less than 25% and / or less than 10% of the supply voltage ( V bat ) deviates and is not modulated when the supply voltage ( V bat ) below a first threshold ( V Nom ) lies and where the switching regulator is connected to the relay coil in the on state ( L ) a relay coil voltage ( V Rel ) which in its maximum magnitude is less than 25% and / or less than 10% of the magnitude of the supply voltage ( V bat ) deviates and is modulated with a modulation signal, in particular a PWM and / or a PDM signal and / or a pulse-modulated signal, when the supply voltage ( V bat ) above the first threshold ( V Nom ) lies.

[0008] The proposed switching regulator with a relay coil ( L ) as a choke coil, in the on state it connects to the relay coil ( L ) a relay coil voltage ( V Rel ) which, at their maximum magnitude, are less than 25% and / or preferably less than 10% of the magnitude of the supply voltage ( V bat ) deviates and is modulated with a modulation signal, in particular a PWM and / or a PDM signal and / or another pulse-modulated signal, when the supply voltage ( V bat ) above the first threshold ( V Nom ). This causes the switching regulator to lower the effective relay voltage ( V Rel ) via the relay coil ( L ) or stabilizes them.

[0009] A PWM signal with a duty cycle is particularly preferred as the modulation signal, where the duty cycle then depends on the supply voltage ( V bat ) depends on the supply voltage ( V bat ) above the first threshold ( V Nom ) is to determine the effective relay voltage ( V Rel ) depending on the supply voltage (V Bat ) to regulate. Alternatively, the modulation signal can also be, for example, a PDM signal with a pulse density, where the pulse density depends on the supply voltage ( V bat ) depends on the supply voltage ( V bat ) above the first threshold ( V Nom ) is located, in order to then in this way determine the effective relay voltage ( V Rel ) depending on the supply voltage (V Bat ) to regulate.

[0010] Preferably, the duty cycle of a PWM modulation depends on the supply voltage ( V bat ) that the average relay current ( I Rel ) through the relay coil ( L ) is constant when the supply voltage ( V bat ) above the first threshold ( V Nom ). In the case of PDM modulation, the pulse density preferably depends on the supply voltage in such a way ( V bat ) that the average relay current ( I Rel ) through the relay coil ( L ) is essentially constant when the supply voltage ( V bat ) above the first threshold ( V Nom ) lies.

[0011] The modulation signal preferably has a PWM frequency ( f PWM ) and an associated PWM period ( T PWM =1 / f PWM ). At this point, it should be expressly noted that in this document, the term PWM frequency refers to the instantaneous frequency of the modulation. The term PWM frequency was chosen because PWM modulation is preferably used in switching regulators in the state of the art. Reference is also made to the glossary. The PWM frequency ( f PWM ), if the supply voltage ( V bat ) above the first threshold ( V Nom ) is chosen to be so high that the fluctuation of the relay current ( I Rel ) through the relay coil ( L ) and / or the fluctuation of a current ( I ) by a switching element ( T1 ) of the switching regulator less than 50% and / or better less than 25% and / or better less than 10% and / or better less than 5% and / or better less than 2% and / or better less than 1% and / or of the average relay current ( I Rel ) or the current ( I ) through the switching element ( T1) of the switching regulator in one PWM period ( T PWM ) is. The PWM frequency ( f PWM ) is when the supply voltage ( V bat ) above the first threshold ( V Nom ) is typically chosen to be so high in the on state of the relay that the fluctuation of the relay current ( I Rel ) through the relay coil ( L ) in one PWM period ( T PWM ) does not lead to the relay dropping into the off state and / or that the fluctuation of the relay current ( I Rel ) through the relay coil ( L ) in one PWM period ( T PWM ) does not result in a sound level that could be heard by a person at a distance of 10cm between the person's ear and the relay switch ( S ) and / or relay coil ( L ) can still be perceived. To achieve the latter, the amount of the PWM frequency ( f PWM ), if the supply voltage ( V bat ) above the first threshold ( V Nom ) is higher than the upper hearing threshold frequency ( f emax ) (see Fig. 3) and / or higher than 20kHz. Power control

[0012] When using a relay coil ( L Using the choke inductor of a switching regulator as a current control input is also conceivable, but less recommended. The switching regulator then has a control input ( One ) which has at least one first state, hereinafter referred to as the on-state, and one second state, hereinafter referred to as the off-state. The switching regulator also includes a supply voltage line ( VDD ) on a supply voltage ( V bat ) compared to a reference potential in a reference potential line ( GND ), which supplies the switching regulator with electrical energy. The switching regulator also has means ( IM ) for detecting the relay current ( I Rel ) Supply voltage ( V bat ). The switching regulator supplies power in the off state, except for the current ( I d ) through a freewheeling diode that may be present ( D1 ) the relay coil ( L ) no. The switching regulator applies current to the relay coil when it is on ( L ) a relay coil voltage ( V Rel ) that are less than 25% and / or preferably less than 10% of the supply voltage ( V bat ) deviates and is not modulated when the supply voltage ( V bat ) below a first threshold ( V Nom ). In contrast, and this is the key point, the switching regulator, when on, applies current to the relay coil ( L ) a relay coil voltage ( V Rel ) which, in their maximum magnitude, are less than 25% and / or less than 10% of the magnitude of the supply voltage ( V bat ) differs and is now modulated with a modulation signal, in particular a PWM and / or a PDM signal and / or a pulse-modulated signal, when the magnitude of the relay current ( I Rel ) above a current threshold ( I Nom ) lies.

[0013] Preferably, the modulation signal is a PWM signal with a duty cycle. The duty cycle preferably depends on the magnitude of the relay current ( I Rel ) off when the relay current ( I Rel ) above a current threshold ( I Nom ). Alternatively, for example, the modulation signal can be a PDM signal with a pulse density, where preferably the pulse density is equal to the magnitude of the relay current ( I Rel ) depends on the magnitude of the relay current ( I Rel ) above a current threshold ( I Nom ). The duty cycle usually, but not always, depends on the magnitude of the relay current ( I Rel ) that the average relay current ( I Rel ) through the relay coil ( L ) is essentially constant when the magnitude of the relay current ( I Rel ) above a current threshold ( I Nom ) lies.

[0014] Alternatively, the pulse density can be determined, for example, by the magnitude of the relay current ( I Rel ) depend on the average relay current ( I Rel ) through the relay coil ( L ) is essentially constant when the magnitude of the relay current ( I Rel ) above a current threshold ( I Nom ) lies.

[0015] The modulation signal preferably has a PWM frequency ( f PWM ) and an associated PWM period ( T PWM =1 / f PWM ). Regarding the above statements on the PWM frequency ( f PWM ) is explicitly pointed out. The PWM frequency ( f PWM ) is when the magnitude of the relay current ( I Rel ) above a current threshold ( I Nom ) is typically chosen to be so high that the fluctuation of the relay current (I Rel ) through the relay coil ( L ) and / or the fluctuation of a current ( I ) by a switching element ( T1 ) of the switching regulator less than 50% and / or better less than 25% and / or better less than 10% and / or better less than 5% and / or better less than 2% and / or better less than 1% and / or of the average relay current ( I Rel ) or the current ( I ) through the switching element ( T1 ) of the switching regulator in one PWM period ( T PWM ) is.

[0016] Here too, as in the rest of the document presented here, the modulation signal preferably has a PWM frequency ( f PWM ) and an associated PWM period ( T PWM =1 / f PWM ) where the PWM frequency ( f PWM ), if the amount of the relay current ( I Rel ) above a current threshold ( I Nom ) is in the on state of the relay ( R1 ) is chosen to be so high that the fluctuation of the relay current ( I Rel ) through the relay coil ( L ) in one PWM period ( T PWM ) not to cause the relay to drop out ( R1 ) leads to the off state.

[0017] The PWM frequency is then ( f PWM ), if the amount of the relay current ( I Rel ) above a current threshold ( I Nom ) is usually chosen to be so high that the fluctuation of the relay current ( I Rel ) through the relay coil ( L ) in one PWM period ( T PWM ) does not result in a sound level that could be heard by a person at a distance of 10cm between the person's ear and the relay switch ( S ) and / or relay coil ( L ) can still be perceived.

[0018] For this purpose, it is advantageous if the amount of the PWM frequency ( f PWM ), in the event that the amount of the relay current ( I Rel ) above a current threshold ( I Nom ) is higher than the upper hearing threshold frequency ( f emax ) and / or is higher than 20kHz. Proceedings

[0019] Besides the idea of ​​using a relay coil as the choke coil of a switching regulator to prevent overcurrent when the relay is activated ( R1 ) in the case of high supply voltages (V Bat ) can also be a suitable method for operating a relay ( R1 ) are specified, where the relay ( R1 ) another relay coil ( L ) exhibits. The relay ( R1 ) is supplied by means of a supply voltage ( V bat ) supplied with electrical energy. The relay ( R1 ) exhibits an on state in which the relay coil ( L ) with a relay current ( I Rel ) is powered and the relay switch ( S ) is closed, and an off state in which the relay coil ( L ) the relay switch ( S ) is open. The relay ( R1) is, according to this procedure, in the switched-on state with a non-modulated relay voltage ( V Rel ) supplied when the amount of the supply voltage ( V Rel ) below a first threshold ( V Nom ) is located. The relay ( R1 ) is, according to the procedure, in the switched-on state with a relay voltage modulated by a modulation signal ( V Rel ) supplied when the amount of the supply voltage ( V bat ) above a first threshold ( V Nom The modulation signal is preferably a pulse modulation. See the Glossary section for further information.

[0020] The modulation signal can again be, for example, a PWM signal with a duty cycle, where the duty cycle depends on the supply voltage ( V bat ) depends on the supply voltage ( V bat ) above the first threshold ( V Nom ). However, the modulation signal can also be, for example, a PDM signal with a pulse density, where the pulse density depends on the supply voltage ( V bat ) depends on the supply voltage ( V bat ) above the first threshold ( V Nom ) lies.

[0021] The duty cycle of the PWM signal can thus be determined by the supply voltage ( V bat ) depend on the average relay current (l Rel ) through the relay coil ( L ) is essentially constant when the supply voltage ( V bat ) above the first threshold ( V Nom ). Similarly, the pulse density can be determined by the supply voltage ( V bat ) depend on the average relay current ( I Rel ) through the relay coil ( L ) is constant when the supply voltage ( V bat ) above the first threshold ( V Nom ) lies.

[0022] The modulation signal has a PWM frequency ( f PWM ) and an associated PWM period ( T PWM =1 / f PWM ) where the PWM frequency ( f PWM ), if the amount of the supply voltage (V Bat ) above a first threshold ( V Nom ) should preferably be chosen so high that the fluctuation of the relay current ( I Rel ) through the relay coil ( L ) and / or the fluctuation of a current ( I ) by a switching element ( T1 ), that the relay coil voltage ( V Rel ) modulated, less than 50% and / or less than 25% and / or less than 10% and / or less than 5% and / or less than 2% and / or less than 1% and / or of the average relay current ( I Rel ) or the current ( I ) through the switching element ( T1 ) in one PWM period ( T PWM ) is.

[0023] The PWM frequency ( f PWM ), if the amount of the supply voltage (V Bat ) above a first threshold ( V Nom ) is in the switched-on state of the relay ( R1 ) and, if the amount of the supply voltage ( V bat ) above the first threshold ( V Nom ) should preferably be chosen so high that the fluctuation of the relay current ( I Rel ) through the relay coil ( L ) in one PWM period ( T PWM ) does not lead to a change in the state of the relay ( R1 ) into the off state of the relay ( R1 ) leads.

[0024] The PWM frequency should also be ( f PWM ), if the amount of the supply voltage (V Bat ) above a first threshold ( V Nom ) is in the switched-on state of the relay ( R1 ) and, if the amount of the supply voltage ( V bat ) above the first threshold ( V Nom ) should be chosen so high that the fluctuation of the relay current ( I Rel ) through the relay coil ( L ) in one PWM period ( T PWM )) does not result in a sound development that could be heard by a person at a distance of 10cm between the person's ear and the relay switch ( S ) and / or relay coil ( L ) can still be perceived.

[0025] The amount of the PWM frequency ( f PWM ), if the amount of the supply voltage (V Bat ) above a first threshold ( V Nom ) should preferably be higher than the upper hearing threshold frequency ( f emax ) and / or be higher than 20kHz. device

[0026] In addition to using a relay as a choke coil and the associated method, a device for controlling a relay also results ( R1 ), which performs the above procedure. The device preferably comprises the relay ( R1 ) with the relay coil ( L ) and the relay switch ( S ), a switching element ( T1 ) and a control device ( TR ), which includes a tax receipt ( One ). The device is powered by a supply voltage ( V bat ) supplied with electrical energy. The device also includes a voltage measuring device ( World Cup ) to detect the voltage value of the supply voltage ( V bat ). The switching element ( T1 ) can assume an on-state and an off-state switching element. The control input ( One ) can have a first logical state and a second logical state. An electrical relay current ( I Rel ) flows through the relay coil ( L ), which can also have the current value OA. The electrical relay current ( I Rel ) depends on the switching state of the switching element ( T1 ) off. The relay switch ( S ) can be in an on relay switching state and in an off relay switching state. The relay coil ( R1) controls the relay switching state of the relay switch via its magnetic field and the resulting magnetic force on an armature not shown in the figures ( S ) depending on the relay current ( I Rel The control device (CTR) brings the switching element ( T1 ) into the off switching element state when the control input ( One ) exhibits the first logical state, and into the switched-on switching element state when the control input ( One ) exhibits the second logical state and the magnitude of the supply voltage ( V bat ) is smaller than a first threshold ( V Nom ). The control device (CTR) allows the switching element ( T1 ) between the switched-on state and the switched-off state of the switching element according to a modulation with the said PWM frequency ( f PWM ), which does not have to be constant, switch back and forth when the control input ( One ) exhibits the second logical state and the magnitude of the supply voltage ( V bat ) greater than a first threshold ( V Nom ) or directly a first threshold ( V Nom ) is. The modulation of the switching back and forth of the switching element state is preferably pulse modulation. Preferably, the pulse modulation of the switching back and forth of the switching element state has a duty cycle. The duty cycle preferably depends on the supply voltage ( V bat ) off when the supply voltage ( V bat ) above the first threshold ( V Nom ). Instead of PWM modulation, PDM modulation can also be used with a <Pulsdichte verwendet werden, wobei dann die Modulation eine PDM-Modulation mit einer Pulsdichte des Hin- und Her-Schaltens des Schaltelementzustands ist und wobei die Pulsdichte des Hin- und Her-Schaltens des Schaltelementzustands von der Versorgungsspannung ( V bat ) depends on the supply voltage ( V bat ) above the first threshold ( V Nom ) lies.

[0027] In the case of PWM modulation, the duty cycle of the switching back and forth of the switching element state preferably depends on the supply voltage in such a way that ( V bat ) that the average relay current ( I Rel ) through the relay coil ( L ) is essentially constant when the supply voltage ( V bat ) above the first threshold ( V Nom ) lies.

[0028] In the case of an exemplary PDM modulation, the pulse density of the switching back and forth of the switching element state depends on the supply voltage ( V bat ) that the average relay current ( I Rel ) through the relay coil ( L ) is constant when the supply voltage ( V bat ) above the first threshold ( V Nom ) lies.

[0029] The modulation of the switching back and forth of the switching element state also exhibits a PWM frequency here ( f PWM ) and an associated PWM period ( T PWM =1 / f PWM ) where the PWM frequency ( f PWM ), if the supply voltage ( V bat ) above the first threshold ( V Nom ) is chosen to be so high that the fluctuation of the relay current ( I Rel ) through the relay coil ( L ) and / or the fluctuation of a current ( I ) through the switching element ( T1 ) less than 50% and / or better less than 25% and / or better less than 10% and / or better less than 5% and / or better less than 2% and / or better less than 1% and / or of the average relay current ( I Rel ) or the current ( I ) through the switching element ( T1 ) in one PWM period ( T PWM ) is.

[0030] Furthermore, the PWM frequency is preferred ( f PWM ) of switching the switching element state back and forth when the control input ( One ) exhibits the second logical state and the magnitude of the supply voltage ( V bat ) greater than the first threshold ( V Nom ) or equal to the first threshold ( V Nom ) is chosen so high that the fluctuation of the relay current ( I Rel ) through the relay coil ( L ) in one PWM period ( T PWM ) does not lead to a change in the relay's switching state ( R1 ) leads.

[0031] The PWM frequency ( f PWM ) of switching the switching element state back and forth when the control input ( One ) exhibits the second logical state and the magnitude of the supply voltage ( V bat ) greater than the first threshold ( V Nom ) or equal to the first threshold ( V Nom ) is preferably chosen to be so high that the fluctuation of the relay current ( I Rel ) through the relay coil ( L) in one PWM period ( T PWM )) the switching back and forth of the switching element state does not lead to a sound development that can be heard by a person at a distance of 10cm between the person's ear and the relay switch ( S ) and / or relay coil ( L ) can still be perceived.

[0032] The amount of the PWM frequency ( f PWM ) of switching the switching element state back and forth when the supply voltage ( V bat ) above the first threshold ( V Nom ) is preferably higher than the magnitude of the upper hearing threshold frequency ( f emax ) and / or higher than 20kHz.

[0033] A proposed vehicle, preferably an electric vehicle, preferably comprises at least one device as previously described. The relay switch ( S) can typically disconnect or connect a supply line of an electric motor of the vehicle to a power supply of the vehicle, in particular to a battery and / or a generator and / or another electric motor.

[0034] The relay switch ( S This device is preferably designed or used to electrically disconnect the power supply from a fault location or another faulty component of the vehicle in the event of a fault. Such a fault could be, for example, a short circuit detected somewhere in the wiring harness or another component of the vehicle. Test procedure

[0035] Based on this, a procedure for testing a relay ( R1 ) are specified, where the relay ( R1 ) a relay coil ( L ) for electromechanical actuation of the relay switch ( S) includes and wherein the relay switch ( S ) may be in an on-relay state or an off-relay state. The test procedure preferably includes the following steps: • Controlling the relay coil ( L ) with a modulated relay voltage ( V Rel ), where the modulation is a PWM frequency ( f PWM ) exhibits a value so high that the relay switch ( S ) changes from an off relay state to an on relay state; • Detection of the relay current ( I Rel ), in particular the modulated component of the relay current ( I Rel ), through the relay coil ( L ) or one of its dependent electric currents ( I ) in the form of a current value; • Conclusion regarding a state, in particular a fault state, of the relay ( R1), if the magnitude of the current value at one or more time points does not match an expected value or is not within an expected value range.

[0036] The modulation is again preferably pulse modulation, in particular PWM modulation or PDM modulation.

[0037] In an alternative test procedure, the relay includes ( R1 ) again the aforementioned relay coil ( L ) for electromechanical actuation of the relay switch ( S ), where the relay switch ( S ) can be in an on relay state or an off relay state. The alternative procedure includes the following steps: • Controlling the relay coil ( L ) with a modulated relay voltage ( V Rel ), • where the amplitude of the relay voltage modulation ( V Rel ), which is so low that the relay switch ( S) does not change its relay state during the test; • Detecting the modulated portion of the relay current ( I Rel ) through the relay coil ( L ) or one of its dependent electric currents ( I ) in the form of a current value; • Conclusion regarding a state, in particular a fault state, of the relay ( R1 ), if the magnitude of the current value at one or more time points does not match an expected value or is not within an expected value range.

[0038] Here too, the modulation is preferably pulse modulation, in particular PWM modulation or PDM modulation.

[0039] A corresponding vehicle, preferably an electric vehicle, then comprises at least one device with a relay ( R1 ) includes a device that performs or is intended to perform a test procedure as described above.

[0040] The relay ( R1 ) can preferably be done using a relay switch ( S ) disconnect or connect a supply line of an electric motor of the vehicle to a power supply, in particular to a battery and / or a generator and / or another electric motor.

[0041] The relay switch ( S ) is preferably intended or preferably used to electrically disconnect the vehicle's power supply from a fault location or other faulty device of the vehicle in the event of a fault. Advantage

[0042] With the help of such a device, the current load on the relay coil ( L ) massively reduced and limited. At the same time, the necessary transistor area of ​​the switching element ( T1 ) can be reduced, since the maximum current load is at maximum operating voltage (V Bat) decreases. Furthermore, the device can then also be used to test the relay ( R1 ) can be used. If the relay is stuck, the resonant frequencies are detuned and this can be detected. In case of a fault, a signal is then sent or corresponding information is provided, for example via a data interface of the control device (CTR). List of characters Fig. Figure 1 shows a state-of-the-art relay control. Fig. Figure 2 shows the current input and power consumption curve of a device according to the state of the art. Fig. Figure 3 shows the hearing threshold for humans according to the current state of technology. Fig. Figure 4 shows a proposed device. Fig. Figure 5 shows a simplified schematic of the relay current for clarity ( I Rel ) a proposed device and the course of the average relay voltage (V Rel,av) and the dependence of the power loss primarily on the switching element ( T1 ) from the operating voltage (V Bat ). Fig. Figure 6 shows the course of the total power (P tot ) in the relay coil and in the switching element ( T1 ) depending on the supply voltage (V Bat ). Description of the figures: Figure 1

[0043] Fig. Figure 1 shows a state-of-the-art relay control. A driver ( TR ) generates depending on the control input ( One ) the control signal ( AS ), with which the switching element ( T1 ), which is preferably a MOS transistor or the like, is controlled. Depending on the control signal ( AS ) connects the switching element ( T1 ) the supply voltage line ( VDD ) on the supply voltage potential (V Bat ) with a first connection of the relay coil ( L ) of the relay (R1 ) or disconnects the supply voltage line ( VDD ) on the supply voltage potential (V Bat ) from the first terminal of the relay coil ( L ) of the relay ( R1 ). Since the second connection of the relay coil ( L ) with the reference potential line ( GND ) is connected to reference potential, thereby the relay coil ( L ) with a relay voltage ( V Rel ) is acted upon, which in the case of a closed switching element ( T1 ) essentially equal to the supply voltage (V Bat ) is. Is the switching element ( T1 ) opened, the freewheeling diode takes over ( D1 ), which is also a substrate diode of the switching element ( T1 ) can trade the current with a diode current (I D ). The switching element is powered by the current ( I ) flowed through it. The relay coil ( L ) is driven by a relay current ( I Rel ) flows through it. Is the relay current (I Rel ) of OA differ and are greater in magnitude than a minimum switching current. Thus, the relay switch ( S ) in the example of the Fig. 1 closed. Figure 2

[0044] shows the current draw and power consumption curve of a device according to the state of the art (see also Fig. 1) The relay current increases linearly with the supply voltage (V Bat ). Accordingly, the total power loss (P) increases. tot ) in the switching element ( T1 ) and the relay coil ( L ) square. However, even very low currents will activate the relay switch ( S) is reached. The corresponding operating voltage is therefore the minimum operating voltage and the corresponding relay current is the minimum relay current. It has now been recognized that higher power levels and relay currents offer no benefit and therefore require additional investment in increased robustness and current-carrying capacity of the switching element ( T1 ) and the relay coil ( L ) are wasted and only cause additional costs. Figure 3

[0045] Fig. Figure 3 shows the hearing threshold for humans according to the current state of technology. Figure 4

[0046] Fig. Figure 4 shows a proposed exemplary device in simplified schematic form. It largely corresponds to the Fig. 1. However, now the driver ( TR ) a control device is connected upstream. A voltage measuring device ( World Cup ) detects the value of the supply voltage (V Bat ) on the supply voltage line ( VDD) and forms a corresponding voltage measurement signal ( VMS For clarification, a current measuring device is shown here, although not actually necessary in parallel ( IM ) shown, which represent the value of the current I through the switching element ( T1 ) detected and a corresponding current measurement signal ( IMS ). Instead, although not actually necessary in parallel here either, a current measuring device ( IM ) can be drawn, which represent the value of the relay current ( I Rel ) through the relay inductance ( L ) is detected and forms a corresponding second current measurement signal that is not shown.

[0047] The control device (CTR) and the subsequent driver ( TR ) now generate depending on the state of the control input ( One ) and the recorded value of the supply voltage (V Bat ) and / or the recorded value of the current ( I) through the switching element ( T1 ) and / or the measured value of the relay current ( I Rel ) through the relay coil ( L ) the control signal ( AS For example, if the supply voltage (V) Bat ) above a first voltage threshold ( V Nom ), so the control device generates the control signal using the control signal ( AS ) for example, PWM modulation of the relay voltage ( V Rel This reduces the average relay current ( I Rel ) and the average relay voltage ( V Rel ) and thus the one in the relay coil ( L ) converted electrical power. Furthermore, the fact that the relay coil ( L ) keeps the current approximately constant and smooths it out. This ensures that a force continues to act on the relay switch ( S ) which therefore remains closed in this example when the PWM frequency ( f PWM ) the PWM modulation of the relay voltage exemplified here ( V Rel ) is high enough. Figure 5

[0048] Fig. Figure 5 shows again the course of the average relay voltage (V). Rel,av ) and the relay current ( I Rel ) depending on the supply voltage (V Bat ) The power loss (PDis, drv) of the switching element ( T1 ) would grow exponentially, quadratically. Figure 6

[0049] schematically simplified for clarity shows the relay current ( I Rel ) a proposed device, e.g., according to Fig. 3 and the course of the average relay voltage (V Rel,av ) and the dependence of the average power loss (P dis,drv ) primarily of the switching element ( T1 ) from the operating voltage (V Bat ). Is the magnitude of the operating voltage (V Bat ) greater in amount than a threshold value ( V Nom ), so the control device (CTR) begins with a pulse modulation of the relay voltage ( V Rel ). In the Fig. 6 are the maximum relay voltage values ​​( V Rel ) as linear with the supply voltage (V Bat ) shown increasing. The average relay voltage (V) not shown is Rel,av However, in this example, it remains constant, which can be achieved, for example, by changing the duty cycle depending on the supply voltage (V). Bat ) can be achieved.

[0050] This keeps the amount of relay current ( I Rel ) above this threshold ( V Nom ) for the supply voltage (V Bat ) in this example is also constant and does not follow the curve (I' Rel ) for the relay current without modulation.

[0051] This results in a voltage range ( V NoPWM ) the supply voltage (V Bat ), in which the relay voltage ( V Rel ) is not modulated and a voltage range (V PWM ) the supply voltage (V Bat ), in which the relay voltage ( V Rel ) is modulated. Figure 7

[0052] shows the course of the total power (P tot ) in the relay coil ( L ) and in the switching element ( T1 ) depending on the supply voltage (V Bat ) when using a proposed device. The drop in total power loss is noteworthy. Glossary: ​​Constant relay current ( I Rel )

[0053] The relay current ( I Rel ) is essentially constant within the meaning of this document if the magnitude of the relay current changes by no more than 25% due to modulation compared to the time-averaged value of the relay current ( I Rel ) and / or better by no more than 10% compared to the time-averaged value of the relay current ( I Rel ) and / or better by no more than 5% compared to the time-averaged value of the relay current ( I Rel ) and / or better by no more than 2% compared to the time-averaged value of the relay current ( I Rel ) and / or better by no more than 1% compared to the time-averaged value of the relay current ( I Rel A fluctuation of less than 1% compared to the time-averaged value of the relay current is particularly preferred ( I Rel ), in order to keep EMC loads low. Hearing threshold

[0054] The hearing threshold of a healthy person is approximately at the reference value of the sound pressure level scale, p0 = 20 µPa. The hearing threshold varies from person to person and is frequency-dependent. Here, let's focus on... Fig. 3. For the purposes of this document, a measuring distance of 10 cm to the relay coil is assumed. L or to the relay switch ( S ) assumed, whereby the loudest part of the order shall be used for the evaluation of the claims. Pulsmodulation

[0055] Pulse modulation, as used here, encompasses all modulation types in which the signal is switched between two values. These modulation types include, in particular, pulse amplitude modulation (PAM), a modulation type in which the amplitude of the signal is abruptly changed at specific time intervals; pulse code modulation (PCM), an extension of PAM in which, for the purposes of this document, the sequence of pulses reflects a binary code, preferably a pseudorandom number, in order to output a frequency band with a minimum and a maximum frequency instead of a single frequency, in order to optimize the EMC spectrum or audible perception; pulse frequency modulation (PFM), in which a square wave signal is modulated in its frequency, with the width of the pulses (their on-time or off-time) typically remaining constant; and pulse width modulation (PWM), which is a modulation of a square wave signal in its pulse width.where the frequency typically remains constant, pulse density modulation (PDM), where the pulse density of the pulses is modified within an equal time interval, pulse-pause modulation (PPM), where pauses of varying lengths occur between pulses of constant amplitude and length, pulse phase modulation (PPM), where pulses of the same amplitude and pulse length are transmitted with typically the same frequency, and pulse position modulation (PPM), where the pulse positions are modulated to modify the spectrum. This document also covers combinations of these modulation types. When referring here to PWM frequency (, f PWM When we talk about ), it is always the inverse of one period of such a pulse-modulated signal. The PWM frequency ( f PWM ) therefore explicitly refers not only to PWM-modulated pulse-modulated signals, but to all pulse-modulated signals listed here. The PWM frequency ( f PWM ) does not need to be constant, but can be changed during operation according to the requirements. For the control system to function fully, typically at least one modulation component must be a pulse modulation, which leads to a change in the average value of the relay voltage ( V Rel ) leads to the relay current ( I Rel ) to be able to regulate. Reference symbol list AS control signal of the driver ( TR ) for the switching element ( T1 ); D1 freewheeling diode; L relay coil; f emax upper hearing threshold frequency; f PWM Frequency of the PWM signal used for modulation; f S Sound frequency; GND reference potential line; I Current through the switching element ( T1 ); I d Current through the freewheeling diode ( D1 ); IMS current measurement signal; I NomCurrent threshold of the relay current (I Ref ); I' Nom Current through the switching element ( T1 ), which is usually approximately the current threshold ( I Nom ) of the relay current (l Ref ) corresponds and is assumed to be the same in this document for the sake of simplicity; I Rel Relay current; IM current measuring device; Pdis,drv Power loss of the switching element ( T1 ) and the control device (CTR); R1 relay; R on On-resistance of the switching element ( T1 ); S relay switch; State of the art (SdT); Sign control input; T1 Switching element. Typically, this is a transistor or thyristor. Preferably, it is a monolithic integrated MOS transistor; T PWM PWM period. The PWM period is the inverse of the PWM frequency ( f PWM ) of the relay coil voltage modulation ( V Rel ) use PWM signals. This is the period of a fluctuation of the PWM signal between two consecutive falling or two consecutive rising edges of the relay coil voltage ( V Rel ), if this is PWM-modulated, for example because the supply voltage ( V bat ) above the first threshold ( V Nom ) lies; TR driver for controlling the switching element ( TR ) by means of the control signal ( AS ) depending on the tax input ( One It is usually a simple power amplifier that amplifies the control signal ( One ) in power amplification to compensate for the parasitic input capacitance of the switching element ( T1 ) to compensate; V bat Supply voltage; VDD supply voltage line; VM voltage measuring device; VMS voltage measurement signal; V Nom first threshold; V NoPWM modulation-free range of the supply voltage (V Bat ); V Rel Relay coil voltage; V REL,av Average relay coil voltage;

Claims

[1] Method for operating a relay (R1) wherein the relay (R1) has a relay coil (L) and where the relay (R1) is powered by a supply voltage (V bat ) with electrical energy is provided for and wherein the relay (R1) has an on state in which the relay coil (L) is connected to a relay current (I Rel ) is powered and the relay switch (S) is closed, and wherein the relay (R1) is in an off state in which the relay coil (L) the relay switch (S) is open and where the relay (R1) is switched on with a non-modulated Relay voltage (V Rel ) is supplied when the amount of the supply voltage (V Rel ) below a first threshold (V Nom ) lies and where the relay (R1) is switched on with a modulating signal modulated relay voltage (V Rel ) is supplied when the amount of the supply voltage (V bat ) above a first threshold (V Nom ) lies. [2] Method according to claim 1 wherein the modulation signal is a pulse modulation. [3] Method according to claim 2 where the modulation signal is a PWM signal with a duty cycle. and where the duty cycle depends on the supply voltage (V bat depends on when the Supply voltage (V bat ) above the first threshold (V Nom ) lies. [4] Method according to claim 2 where the modulation signal is a PDM signal with a pulse density and where the pulse density depends on the supply voltage (V bat ) depends on the supply voltage (V bat ) above the first threshold (V Nom ) lies. [5] Method according to claim 3 where the duty cycle depends on the supply voltage (V bat ) depends on the average Relay current (I Rel ) through the relay coil (L) is essentially constant when the supply voltage (V bat ) above the first threshold (V Nom ) lies. [6] Method according to claim 4 where the pulse density depends on the supply voltage (V) bat ) depends on the average Relay current (l Rel ) through the relay coil (L) is constant when the supply voltage (V bat ) above the first threshold (V Nom ) lies. [7] Method according to claim 3 to 5 where the modulation signal is a PWM frequency (f PWM ) and an associated PWM- Period (T PWM =1 / f PWM ) exhibits and where the PWM frequency (f PWM ), if the amount of the supply voltage (VBat ) above a first threshold (V Nom ) is chosen to be so high that the fluctuation of the relay current (I) Rel ) through the relay coil (L) and / or the fluctuation of a current (I) through a switching element (T1) that changes the relay coil voltage (V) Rel ) modulated, less than 50% and / or less than 25% and / or less than 10% and / or less than 5% and / or less than 2% and / or less than 1% and / or of the average relay current (I Rel ) or the current (I) through the switching element (T1) in one PWM period (T PWM ) is. [8] Method according to claim 3 to 7 where the modulation signal is a PWM frequency (f PWM ) and an associated PWM- Period (T PWM =1 / f PWM ) exhibits and where the PWM frequency (f PWM ), if the amount of the supply voltage (V Bat ) above a first threshold (VNom ) is in the switched-on state of the relay (R1) and when the magnitude of the supply voltage (V bat ) above the first threshold (V Nom ) is chosen to be so high that the fluctuation of the relay current (I) Rel ) through the relay coil (L) in one PWM period (T PWM ) does not lead to a change in the state of the relay (R1) to the switched-off state of the relay (R1). [9] Method according to claim 3 to 8 where the modulation signal is a PWM frequency (f PWM ) and an associated PWM- Period (T PWM =1 / PWM ) exhibits and where the PWM frequency (f PWM ), if the amount of the supply voltage (V Bat ) above a first threshold (V Nom ) is in the switched-on state of the relay (R1) and when the magnitude of the supply voltage (V bat ) above the first threshold (V Nom) is chosen to be so high that the fluctuation of the relay current (I) Rel ) through the relay coil (L) in one PWM period (T PWM )) does not result in a sound development that can still be perceived by a person at a distance of 10cm between the person's ear and the relay switch (S) and / or relay coil (L). [10] Method according to claim 3 to 9 where the modulation signal is a PWM frequency (f PWM ) and an associated PWM period (T PWM =1 / f PWM ) exhibits and where the magnitude of the PWM frequency (f PWM ), if the amount of the supply voltage (V Bat ) above a first threshold (V Nom ) is higher than the magnitude of the upper hearing threshold frequency (f emax ) and / or is higher than 20kHz.

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