DE102017220546A1 - Determining the voltage levels of actuation signals for actuating an electrical circuit breaker - Google Patents

Abstract

The invention relates to the determination of the voltage level (U, U) of one of at least two actuation signals for actuating an electrical circuit breaker. In this case, the first actuation signal has an electrical voltage with a first voltage level (U), and the second actuation signal has an electrical voltage with a second voltage level (U), wherein the second voltage level (U) is lower than the first voltage level (U) , Here, the at least two actuation signals are successively applied to an input (E +) of a measuring amplifier (4A), which is supplied with a supply voltage of the second voltage level (U). The at least two voltage values (U, U) successively applied to an output (A) of the measuring amplifier (4A) are determined. Based on these voltage values (U, U) and on the basis of known resistance values (R1, R2, R3, R4) of the measuring amplifier (4A), the voltage level (U, U) of the one of the at least two actuating signals is then determined.

Description

The invention relates to the determination of the voltage levels of actuation signals for actuating an electrical circuit breaker. The invention relates in detail to a corresponding method for determining the voltage levels of actuation signals for an electrical power switch and a method for monitoring the electrical circuit breaker. It also relates to a control device for actuating electrical circuit breakers of an inverter or inverter, which is designed to carry out these methods, as well as a vehicle drive system with such a control device.

Electrical power switches, such as MOSFETs (Metal Oxide Semiconductor Field Effect Transistors) or IGBTs (Insulated Gate Bipolar Transistors) are driven by actuation signals. The actuating signal is applied to a gate or base terminal of the circuit breaker. The actuation signal has a specific voltage level which determines whether the circuit breaker assumes the switching state "open" (electrically switched) or "closed" (electrically non-switched). For example, an actuation signal for opening the circuit breaker has a positive voltage level, and another actuation signal for closing the circuit breaker has a negative voltage level.

In safety critical applications of circuit breakers, it may be necessary to monitor the circuit breakers. This can be used to determine if the circuit breaker is not working properly, and if and which countermeasures need to be taken. Circuit-breaker monitoring also includes the monitoring of the circuit-breaker actuation signals. In particular, it is of interest whether the actuation signals each have the correct voltage level. For example, too low a voltage level can cause the circuit breaker to fail or not to assume the desired switching state with certainty. In addition, it can be concluded by observing a change in the voltage levels to a future malfunction or to certain causes of failure.

For measuring electrical voltages, electronic applications mainly use A / D converters (analog-to-digital converters, also called analog-to-digital converters). Such A / D converters convert a voltage applied to the input of the A / D converter into a digital value (digital value) corresponding to the voltage level. Via an output interface, this digital value is made available for further processing so that the voltage level can be further processed numerically.

However, normal A / D converters have a limited input signal range, also called measuring range. Such an A / D converter can therefore not be supplied with an arbitrary spectrum of different high input voltages, which then converts these into corresponding digital values. Therefore, if the input voltage is expected to be too low or too high, the A / D converter will be preceded by an analogue sense amplifier. Its task is to adapt the input voltage to the input signal range of the A / D converter.

Electrical circuit breakers require actuating signals having a positive voltage level for establishing the "open" switching state and "negative" voltage actuating signals for establishing the "closed" switching state. However, a normal single input A / D converter can convert either only positive or negative voltage levels to corresponding digital values, not both. In order to determine the voltage levels of positive and negative actuation signals, A / D converters having at least two inputs are required. These are more costly than A / D converters with only one input.

In addition, the determination of the actual voltage levels of circuit breaker actuation signals when using an A / D converter with an upstream amplifier is not trivial. This is due to the fact that the gain of the measuring amplifier depends on the voltage level of a supply voltage of the measuring amplifier. However, this voltage level is not always exactly known and may, for example, fluctuate.

The object of the present invention is to improve the state of the art.

This object is achieved by the features specified in the main claims. Preferred embodiments thereof are the dependent claims.

• • ein Verfahren zur Ermittlung der Spannungshöhe eines von zumindest zwei Betätigungssignalen zur Betätigung eines elektrischen Leistungsschalters, und
• • ein Verfahren zur Überwachung eines elektrischen Leistungsschalters, und
• • ein Steuergerät zur Betätigung elektrischer Leistungsschalter eines Wechselrichters oder Umrichters, das zur Durchführung dieser Verfahren ausgebildet ist, und
• • ein Fahrzeugantriebssystem mit einem solchen Steuergerät.

Proposed are therefore:

• A method for determining the voltage level of one of at least two actuation signals for actuating an electrical power switch, and
• • a procedure for monitoring an electrical circuit breaker, and
• A control unit for actuating electrical circuit breakers of an inverter or converter designed to carry out these methods, and
• • a vehicle drive system with such a controller.

The invention is based on the assumption that at least two actuating signals are provided for actuating an electrical power switch. As explained above, such a circuit breaker can be, for example, a MOSFET or an IGBT or other types of electrical circuit breakers. The actuation signals are each used to cause a particular switching state at the circuit breaker, so to open or close it. For this purpose, the actuation signals are known to be applied to the gate or base terminal of the circuit breaker.

The actuation signals differ in their voltage levels from each other. A first actuation signal therefore has an electrical voltage with a first voltage level. A second actuation signal therefore has an electrical voltage with a second voltage level, this second voltage level being lower than the first voltage level. The first voltage level is, in particular, a positive voltage level (positive voltage, positive actuation signal). The second voltage level is then in particular a negative voltage level (negative voltage, negative actuation signal). The first actuation signal then serves in particular to effect the switching state "closed" in the circuit breaker. The second actuation signal then serves, in particular, to effect the "open" switching state in the circuit breaker.

In the proposed method, the at least two actuation signals with the respective voltage level are first applied successively to an input of a measuring amplifier. This means optionally that first the first actuating signal is applied thereto and then first the second actuating signal or first that the second actuating signal is applied thereto and only then the first actuating signal. In particular, the two signals are applied directly one after the other to the input of the measuring amplifier.

Characterized in that the actuating signals are applied sequentially to the measuring amplifier, a downstream A / D converter can be designed with only one input per circuit breaker. This (single) input is then preceded (per circuit breaker) by the measuring amplifier. This makes possible the use of low-cost A / D converters. The measuring amplifier is also used here in particular to adapt the voltage levels of the actuating signals to the input signal range of the A / D converter. The sequential application of the actuating signals takes place in particular by means of a driver circuit connected upstream of the measuring amplifier.

The measuring amplifier outputs an (analogue) voltage value which corresponds to the voltage level of the actuating signal currently present at the input. This voltage is then again at the input of the A / D converter. The A / D converter then outputs a corresponding digital value.

The supply voltage of the measuring amplifier normally depends on its amplification and thus also on the voltage value output by the measuring amplifier. However, the voltage level of the supply voltage of the measuring amplifier is not always the same in practice and it is also not always known. For example, it may fluctuate or undergo a gradual change. Thus, it may happen that the same actuation signal is amplified differently with the same voltage level by the measuring amplifier and thus outputs different voltage values. On the basis of the voltage value itself can therefore not be concluded directly on the voltage level of the currently applied to the input of the measuring amplifier actuation signal.

It is therefore proposed that during the sequential application of the actuating signals, first the at least two voltage values which are successively applied to the output of the measuring amplifier are determined. On the basis of these at least two voltage values and on the basis of (known) resistance values of the measuring amplifier, one of the voltage levels of the at least two actuating signals then becomes determined. Of course, it can be provided that the other (n) voltage level (s) of the at least two actuation signals are likewise determined in this case.

The resistance values are in particular ohmic resistances of the measuring amplifier. The resistance values may have been previously determined and may for example be provided in a memory or may already be integrated into corresponding calculation formulas. By including the resistance values, the gain characteristic of the measurement amplifier is taken into account.

The supply voltage of the measuring amplifier in this case has the voltage level of the (low) second actuation signal, that is, the second voltage level. This is especially a negative voltage. In particular, the voltage level of the supply voltage is chosen so low that there are no actuation signals with a lower voltage level. The voltage level of the supply voltage in this case forms in particular a reference voltage of the measuring amplifier for the actuation signals determined by means of it.

The measuring amplifier is preferably designed as a differential amplifier known per se. In such a differential amplifier, an operational amplifier is known to be connected so that it functions simultaneously as an inverting and a non-inverting amplifier. Such a measuring amplifier is characterized in that it amplifies the actuating signal differentially with respect to the most negative voltage to be measured, which is applied as a supply voltage to the measuring amplifier.

In addition to the already mentioned two actuation signals, it is also possible to provide at least or exactly a third actuation signal, likewise with a certain voltage level. The voltage level of the third actuation signal is then higher than the second voltage level, in particular it corresponds to the first voltage level. The third actuating signal then also serves in particular to effect the switching state "closed" in the circuit breaker. The third actuation signal may be provided as an emergency signal. In particular, the third actuation signal is generated by a device other than the first and second actuation signal, in particular by an emergency circuit for generating a safe state.

Optionally, further actuation signals may be provided. Preferably, however, only these two or three actuation signal for the circuit breaker are provided.

• • die Betätigungssignale nacheinander an den Eingang des Messverstärkers angelegt werden, und
• • die hierdurch an dem Ausgang des Messverstärkers nacheinander anliegenden drei Spannungswerte ermittelt werden, und
• • anhand dieser drei Spannungswerte und anhand der Widerstandswerte des Messverstärkers die Spannungshöhe des einen der drei Betätigungssignale ermittelt wird.

In order to determine the exact voltage level of one of the at least or exactly three actuation signals is now proposed that

• • the actuating signals are applied one after the other to the input of the measuring amplifier, and
• • the three voltage values which are successively applied to the output of the measuring amplifier are determined, and
• • the voltage level of one of the three actuation signals is determined on the basis of these three voltage values and on the basis of the resistance values of the measuring amplifier.

It can of course also be provided here that the other voltage level (s) of the three actuating signals are likewise determined with.

• • erstes, zweites, drittes Betätigungssignal, oder
• • erstes, drittes, zweites Betätigungssignal, oder
• • zweites, erstes, drittes Betätigungssignal, oder
• • zweites, drittes, erstes Betätigungssignal, oder
• • drittes, erstes, zweites Betätigungssignal, oder
• • drittes, zweites, erstes Betätigungssignal.

The order of this procedure in determining the voltage levels of the actuating signals is less relevant. For example, this procedure can be performed first with the third and second actuation signal and then only with the first and second actuation signal, or vice versa. It makes sense that no double measurement takes place, ie each actuation signal is applied only once. The order can therefore be as follows:

• • first, second, third actuation signal, or
• • first, third, second actuation signal, or
• • second, first, third actuation signal, or
• • second, third, first actuation signal, or
• • third, first, second actuation signal, or
• • third, second, first actuation signal.

Preferably, the electrical circuit breaker is a circuit breaker of an inverter or inverter. Accordingly, the power switch then serves to convert an electrical input current into a corresponding electrical output current of the inverter or inverter. Such an inverter converts in a conventional manner a direct electrical current into an alternating current (DC-AC conversion), and possibly also vice versa (AC-DC conversion). Such a converter converts in a manner known per se, an alternating electrical current with a first frequency into an alternating current with a second frequency, and possibly also vice versa.

In this case, the first actuation signal is preferably a signal for closing the circuit breaker in the context of normal operation of the AC or converter. Such normal operation is the usual, intended operation of the AC or inverter. In contrast, then the third actuation signal is a signal for closing the circuit breaker in the context of an emergency operation of the AC or inverter. Such an emergency operation is a different operation from the normal operation, in which a certain disturbance has occurred, through which, for example, the normal operation is either no longer possible or is no longer possible with sufficient security. The second actuation signal is then a signal for opening the circuit breaker, which is used either only in normal operation or both in normal operation, as well as in emergency operation.

In such an emergency operation is in particular an operation of the AC or inverter, in which he is placed in a safe state and held there. For this purpose, the circuit breaker of the AC or inverter are controlled in particular so that they each have a predetermined switching state, which represents a safe operation of the AC or inverter.

In particular, the emergency operation is a short-circuit operation. In such a short circuit operation, certain AC or inverter circuit breakers are in an open state and certain other AC or inverter circuit breakers are in a closed state such that some or all of the outputs (phases) of the AC or inverter are electrically coupled together ( = short-circuited). The third actuation signal is then generated in particular by the emergency circuit for generating the safe state. In contrast, the first and the second actuation signal are generated, for example, by an ordinary driver circuit for the normal operation of the AC or inverter. The emergency circuit may be at least partially redundant to the driver circuit for normal operation.

The proposed method for monitoring the electrical circuit breaker provides that at least one of the voltage levels of the at least two actuation signals of the circuit breaker is determined by means of the proposed method. This determined voltage level is compared with a limit value. Alternatively or additionally, the determined voltage level is examined for a change. A signal is generated when the determined voltage level falls below or exceeds the (associated) limit value, and / or when the determined voltage level has undergone an unacceptable change. An impermissible change can be, for example, too rapid a change in the determined voltage level, which leads to a foreseeable undershooting or exceeding of the limit value. The signal can be expressed, for example, in that it becomes immediately recognizable to the outside and / or that a corresponding error is stored in a fault memory.

The also proposed control unit is used to actuate the electrical circuit breakers of an inverter or inverter. The control unit is designed to carry out one of the proposed methods. The control unit may, for example, comprise a data memory on which software codes with instructions for carrying out the respective proposed method are stored. The controller also has the necessary inputs and outputs.

• • die Treiberschaltung, die dazu ausgeführt ist, das erste und zweite Betätigungssignal zu erzeugen, und
• • den als Differenzverstärker ausgeführten Messverstärker, der mit der Treiberschaltung gekoppelt ist; der Messverstärker ist dazu ausgeführt, das aktuell daran anliegende Betätigungssignal in den entsprechenden (analogen) Spannungswert umzuwandeln, und
• • den A/D-Wandler, der mit dem Messverstärker gekoppelt ist; der A/D-Wandler ist dazu ausgebildet, den vom Messverstärker aktuell ausgegebenen Spannungswert in den entsprechenden Digitalwert umzuwandeln, und
• • ein Verarbeitungsmittel, das dazu ausgebildet ist, anhand der Digitalwerte und anhand der Widerstandswerte des Messverstärkers die Spannungshöhe des Betätigungssignals zu ermitteln; dies erfolgt also entsprechend der vorgeschlagenen Verfahren.

The controller preferably has

• The driver circuit configured to generate the first and second actuation signals, and
• The measuring amplifier designed as a differential amplifier, which is coupled to the driver circuit; the measuring amplifier is designed to convert the currently applied actuating signal into the corresponding (analogue) voltage value, and
• • the A / D converter coupled to the sense amplifier; the A / D converter is designed to convert the voltage value currently output by the measuring amplifier into the corresponding digital value, and
• • a processing means, which is designed to determine the voltage level of the actuating signal on the basis of the digital values and based on the resistance values of the measuring amplifier; This is done according to the proposed method.

• • die Treiberschaltung; diese ist dann zur Betätigung der Leistungsschalter in einem Normalbetrieb des Wechsel- oder Umrichters mittels des ersten und des zweiten Betätigungssignals ausgebildet,
• • eine Notschaltung, insbesondere Kurzschlussschaltung; diese ist dann zur Erzeugung des dritten Betätigungssignals und zur Betätigung der Leistungsschalter in dem Notfallbetrieb, insbesondere Kurzschlussbetrieb, des Wechsel- oder Umrichters mittels des dritten Betätigungssignals ausgebildet.

The control unit preferably still has,

• The driver circuit; this is then designed to actuate the circuit breaker in a normal operation of the AC or converter by means of the first and the second actuation signal,
• • an emergency circuit, in particular short-circuiting; this is then designed to generate the third actuation signal and to actuate the circuit breaker in the emergency mode, in particular short-circuit operation, of the AC or converter by means of the third actuation signal.

The short-circuit circuit is used to operate the circuit breaker in the short-circuit operation of the AC or inverter. The short circuit then serves to insert the safe state of the inverter or inverter, which in this particular case is the short circuit of some or all of the outputs (phases) of the inverter or inverter. Accordingly, the short-circuiting circuit is configured to output the said third actuation signal.

The processing means is designed to determine the voltage level of at least one of the three actuation signals, that is, the first and / or second actuation signal from the driver circuit and / or the third actuation signal from the short circuit. Accordingly, the processing means may be configured to determine the voltage levels of two or all three actuation signals

The also proposed vehicle drive system has an electric motor, as well as the inverter or inverter for electrical power to the electric motor, as well as the proposed control unit for actuating electrical circuit breakers of the AC or inverter.

The e-machine serves in particular as a traction drive. It then serves to generate a driving force of the vehicle. Such a drive system is used in particular in a motor vehicle which can be driven electrically at least for a time, such as, for example, a pure electric vehicle or a hybrid vehicle which has an additional combustion engine as a traction drive. Alternatively, the electric motor can also serve as an actuator, ie for actuating or adjusting a device of the vehicle, such as a vehicle steering or a vehicle chassis.

• 1 eine Schaltung zur Betätigung eines elektrischen Leistungsschalters,
• 2 einen als Differenzverstärker ausgeführten Messverstärker.

In the following the invention will be explained in more detail with reference to figures, from which further preferred embodiments and features of the invention can be removed. Here are shown in a schematic representation:

• 1 a circuit for actuating an electrical circuit breaker,
• 2 a measuring amplifier designed as a differential amplifier.

In the figures, identical or at least functionally identical components and elements are provided with the same reference numerals.

The circuit according to 1 Used to operate an electrical circuit breaker, such as a MOSFET or IGBT, AC or inverter. Such a converter or inverter has several circuit breakers, therefore, in particular per circuit breaker such a circuit is provided.

The circuit provides actuating signals with different voltage levels at an output 5 out. At the exit 5 a gate or base terminal of the associated circuit breaker is connected. Thus, the power switch, the actuating signals are supplied, whereby it assumes the corresponding switching state.

The circuit has a driver circuit 1 , This can optionally include a first actuation signal with a first, positive voltage level U _p output or a second actuation signal with a second, negative voltage level U _m ,

The driver circuit 1 is with a power supply 2 coupled. This includes a supply 2A for a positive supply voltage and a supply means 2 B for a negative supply voltage.

To generate the first actuation signal, the driver circuit is 1 the first actuation signal with the voltage level of the positive supply voltage (= first voltage level U _p ) to the circuit breaker. This leads the circuit breaker to assume its closed switching state.

To generate the second actuation signal, the driver circuit is 1 instead the second actuation signal with the voltage level of the negative supply voltage (= second voltage level U _m ) to the circuit breaker. This leads the circuit breaker to assume its open switching state.

In addition, for some or all of the circuit breaker of the inverter or inverter can be an emergency circuit 3 be provided. The emergency circuit 3 serves to make the circuit breaker at least partially redundant to the driver circuit 1 in a safe condition to transfer and keep. The emergency circuit 3 this outputs a third actuation signal to the circuit breaker.

The emergency circuit 3 can with the supply means 2A be coupled for the positive supply voltage. The voltage level of the third actuation signal is thereby at the voltage level of the positive supply voltage (= first voltage level U _p ). Alternatively, the emergency circuit 3 have their own power supply. Then, the voltage level of the third operation signal may deviate from that of the second operation signal.

The third actuating signal also causes the circuit breaker to assume its closed switching state. In particular, this is intended to bring about a safe state in the AC or converter, in particular an active short circuit. In such an active short circuit some or all of the outputs (phases) of the AC or inverter are electrically connected to each other, so shorted together. Then the emergency circuit 3 also be referred to as a short circuit.

In the 1 shown circuit also has means 4 for determining the voltage levels U _p and U _m the two or three actuation signals. The middle 4 is with the exit 5 electrically connected and thus accesses the actuating signals for the circuit breaker.

The middle 4 has a measuring amplifier 4A on. This one is in 2 shown in more detail. The middle 4 also has an A / D converter. This is the measuring amplifier 4A upstream. The middle 4 also has a processing means for numerical determination of voltage levels U _p and U _m from the voltage supplied by the A / D converter. The driver circuit 1 and the means 4 and possibly the emergency circuit 3 are in particular components of a control unit for actuating the electrical circuit breakers of the inverter or inverter.

At the measuring amplifier 4A (please refer 2 ) is a known differential amplifier. The measuring amplifier 4A therefore has an operational amplifier O and ohmic resistances R1 . R2 . R3 . R4 on that with the op amp O are interconnected to form the differential amplifier. The measuring amplifier 4A has a positive input e + and a negative input e - on. At each of these an electrical voltage (input voltage) can be applied. He also has an exit A over which then a corresponding electrical voltage (output voltage) with a certain voltage level ( U _a1 . U _a2 . U _a3 ), here referred to as "voltage value", is output.

mit

U_A =

Spannungshöhe der Ausgangsspannung,

U_E+ =

Spannungshöhe der Eingangsspannung am Eingang E+,

U_E- =

Spannungshöhe der Eingangsspannung am Eingang E-,

R₁... R₄ =

Widerstandswerte der ohmschen Widerstände R1 ... R4.

The relationship between input voltages and output voltage is known to be based on the resistance values of the ohmic resistors R1 . R2 . R3 . R4 of the measuring amplifier 4A dependent. The context is as follows: $$U_A=\frac{\left({\mathrm{<figure-callout\; id="1"\; label="R"\; filenames="DE102017220546A1\_0007.png"\; state="\{\{state\}\}">R</figure-callout>}}_1+R_2\right)R_4}{\left({\mathrm{<figure-callout\; id="3"\; label="R"\; filenames="DE102017220546A1\_0007.png"\; state="\{\{state\}\}">R</figure-callout>}}_3+R_4\right)R_1}{U}_{e+}-\frac{R_2}{R_1}{U}_{e-}$$

With

U _A =

Voltage level of the output voltage,

U _{E +} =

Voltage level of the input voltage at the input e + .

U _E =

Voltage level of the input voltage at the input e -

R ₁ ... R ₄ =

Resistance values of the ohmic resistors R1 ... R4 ,

The resistance values R ₁ ... R ₄ are assumed to be known in the present case. For example, they may have been measured in advance or selected accordingly.

At the entrance e - Here is the negative supply voltage of the supply 2 B created, so the second voltage level U _m , The entrance e + is with the in 1 visible output 5 electrically connected. Thus lies at the entrance e + the respective actuation signal.

In the case of the first actuation signal is therefore the voltage level U _p the positive supply voltage at the input e + on. In the case of the second actuation signal is therefore the voltage level U _m the negative supply voltage at the input e + on. And in the case of the third operating signal is therefore the voltage level of the third actuating signal at the input e + that, in particular, the voltage level U _p the positive supply voltage is or in the range.

At the exit A of the measuring amplifier 4A the A / D converter is connected. This receives accordingly from the amplifier 4A output voltage value U _a1 . U _a2 . U _a3 , The currently applied voltage value U _a1 . U _a2 . U _a3 In turn, the A / D converter converts to a corresponding digital value.

When the voltage level at the input e - of the measuring amplifier 4A constant and known can be determined by the known resistance values R ₁ ... R ₄ of the measuring amplifier 4A and simply numerically the voltage levels based on the digital value output from the A / D converter U _p and U _m the actuation signals at the input e + be determined. However, that is at the entrance e - Applied negative supply voltage is not always known exactly, for example, it may fluctuate or change gradually.

It is therefore suggested that the driver circuit 1 the first and the second actuation signal and optionally also the emergency circuit 3 output the third actuation signal immediately after one another. This can be done for example by means of a buffer, the driver circuit 1 accordingly controls as soon as the voltage levels U _p and U _m the actuation signals are to be determined. This can be done, for example, in the context of monitoring the circuit breaker. This also includes a diagnosis of the circuit breaker, for example during commissioning of the inverter or inverter.

As a result, the two or three actuation signals are successively applied to the input e + of the measuring amplifier 4A created. The measuring amplifier 4A thus converts the actuation signals successively into corresponding analog voltage values U _a1 . U _a2 . U _a3 at its exit A around. These voltage values are then successively converted by the A / D converter into corresponding digital values.

Based on these digital values of the voltage values U _a1 . U _a2 . U _a3 and from the known resistance values R ₁ ... R ₄ of the measuring amplifier 4A Then, in the downstream processing means, the individual voltage levels U _p and U _m of the first and second actuation signal and optionally also the third actuation signal.

Due to the sequential application of the actuating signals, a customary fluctuation or creeping change of the negative supply voltage does not matter, because this usually takes place comparatively slowly. Therefore, during the described application of the actuation signals, a constant, albeit unknown, negative supply voltage can be assumed.

For determining the voltage levels U _p and U _m is preferred first a voltage level U _g a full supply voltage of the power supply 2 determined. On the basis of these can then the voltage levels U _p and U _m be determined.

mit $$g=\frac{R_1{R}_3+R_1{R}_4}{R_1{R}_4+R_2{R}_4},$$

• U_g = Spannungshöhe der vollen Versorgungsspannung der Spannungsversorgung 2,
• U_a1 = (mittels des A/D-Wandlers bestimmter) Spannungswert am Ausgang des Messverstärkers 4A, wenn das ersten Betätigungssignal am Messverstärker 4A anliegt,
• U_a2 = (mittels des A/D-Wandlers bestimmter) Spannungswert am Ausgang des Messverstärkers 4A, wenn das zweite Betätigungssignal am Messverstärker 4A anliegt,
• U_p = Spannungshöhe des ersten Betätigungssignals = Spannungshöhe der positiven Versorgungsspannung,
• U_m = Spannungshöhe des zweiten Betätigungssignals = Spannungshöhe der negativen Versorgungsspannung.

The voltage level of the full supply voltage is determined in particular based on the following equation: $$U_G=U_p-U_m=G\left(U_{a1}-U_{a2}\right)$$

With $$G=\frac{R_1{\mathrm{<figure-callout\; id="3"\; label="R"\; filenames="DE102017220546A1\_0007.png"\; state="\{\{state\}\}">R</figure-callout>}}_3+R_1{R}_4}{R_1{\mathrm{<figure-callout\; id="4"\; label="R"\; filenames="DE102017220546A1\_0007.png"\; state="\{\{state\}\}">R</figure-callout>}}_4+R_2{\mathrm{<figure-callout\; id="4"\; label="R"\; filenames="DE102017220546A1\_0007.png"\; state="\{\{state\}\}">R</figure-callout>}}_4}.$$

• U _g = Voltage level of the full supply voltage of the power supply 2 .
• U _a1 = (determined by the A / D converter) voltage value at the output of the measuring amplifier 4A when the first actuating signal at the measuring amplifier 4A is applied,
• U _a2 = (determined by the A / D converter) voltage value at the output of the measuring amplifier 4A when the second actuating signal at the measuring amplifier 4A is applied,
• U _p = Voltage level of the first actuating signal = voltage level of the positive supply voltage,
• U _m = Voltage level of the second actuating signal = voltage level of the negative supply voltage.

$$Up=-\frac{R_2{R}_3{U}_g+R_2{R}_4{U}_g-R_1{R}_3{U}_{a1}-R_1{R}_4{U}_{a1}}{R_1{R}_4-R_2{R}_3}.$$

The determination of voltage levels U _p and U _m is done in particular based on the following equations: $$U_m=-\frac{\left({\mathrm{<figure-callout\; id="3"\; label="R"\; filenames="DE102017220546A1\_0007.png"\; state="\{\{state\}\}">R</figure-callout>}}_3+R_4\right)\left({\mathrm{<figure-callout\; id="2"\; label="R"\; filenames="DE102017220546A1\_0007.png"\; state="\{\{state\}\}">R</figure-callout>}}_2^2{R}_4{U}_G-{\mathrm{<figure-callout\; id="1"\; label="R"\; filenames="DE102017220546A1\_0007.png"\; state="\{\{state\}\}">R</figure-callout>}}_1^2{R}_4{U}_{a2}+R_1{R}_2{R}_4{U}_G-R_1{R}_2{R}_3{U}_{a1}+R_1{R}_2{R}_3{U}_{a2}-R_1{R}_2{R}_4{U}_{a1}\right)}{R_4\left(R_1{R}_4-R_2{R}_3\right)\left({\mathrm{<figure-callout\; id="1"\; label="R"\; filenames="DE102017220546A1\_0007.png"\; state="\{\{state\}\}">R</figure-callout>}}_1+R_2\right)}.$$

$$Up=-\frac{R_2{R}_3{U}_G+R_2{R}_4{U}_G-R_1{R}_3{U}_{a1}-R_1{R}_4{U}_{a1}}{R_1{R}_4-R_2{R}_3},$$

Here, the above-mentioned equation for determining the voltage level of the full supply voltage U _g also in the two equations for determining the voltage levels U _p and U _m be used directly.

ermittelt werden, die dann entsprechend mathematisch umgestellt ist.When first the full supply voltage U _g and then one of the two voltage levels U _p and U _m is determined, the other of the two voltage levels U _p and U _m also based on the equation $$U_G=U_p-U_m$$

be determined, which is then converted according to mathematical.

In the manner described, the voltage level of the third actuation signal can also be determined. For this purpose, in the equations mentioned simply instead of the voltage value U _a1 the voltage value U _a3 used. This is output by the A / D converter when the third actuating signal at the measuring amplifier 4A is applied. The voltage level determined in this case by means of the equations U _m forms the voltage level of the third actuation signal.

The thus determined voltage levels U _g . U _p . U _m can then be used to monitor the associated circuit breaker. This can be a monitoring of the driver circuit 2 include. For this purpose, the determined voltage levels U _g . U _p . U _m be compared with corresponding limits and / or a temporal change can be determined. When the voltage levels U _g , U _p . U _m then impermissibly high or low or an impermissible change has taken place, it can be concluded that an error and possibly the cause of the error in the generation of the actuation signals. If this is the case, a corresponding signal can be generated. This can be expressed by the fact that it is immediately recognizable to the outside or that a corresponding error is stored in a fault memory.

1. 1. Schalten des Gate- oder Basis-Anschlusses des Leistungsschalters auf die positive Versorgungsspannung mit der Spannungshöhe U_p (= Anlegen des ersten Betätigungssignals an den Leistungsschalter),
2. 2. Bestimmen des hierbei vom Messverstärker 4A ausgegebenen zugehörigen Spannungswertes U_a1 mittels des A/D-Wandlers,
3. 3. Schalten des Gate- oder Basis-Anschlusses des Leistungsschalters auf die negative Versorgungsspannung mit der Spannungshöhe U_m (= Anlegen des zweiten Betätigungssignals an den Leistungsschalter),
4. 4. Bestimmen des hierbei vom Messverstärker 4A ausgegebenen zugehörigen Spannungswertes U_a2 mittels des A/D-Wandlers,
5. 5. Ermittlung der Spannungshöhe U_g der vollen Versorgungsspannung der Spannungsversorgung 2,
6. 6. Ermittlung der Spannungshöhen U_p und U_m der positiven und negativen Spannungsversorgung 2A, 2B (= Ermittlung der Spannungshöhen des ersten und zweiten Betätigungssignals).

An embodiment of the proposed procedure is as follows:

1. 1. Switch the gate or base terminal of the circuit breaker to the positive supply voltage with the voltage level U _p (= Application of the first actuation signal to the circuit breaker),
2. 2. Determine the case of the measuring amplifier 4A output associated voltage value U _a1 by means of the A / D converter,
3. 3. Switch the gate or base terminal of the circuit breaker to the negative supply voltage with the voltage level U _m (= Application of the second actuation signal to the circuit breaker),
4. 4. Determine the case of the measuring amplifier 4A output associated voltage value U _a2 by means of the A / D converter,
5. 5. Determination of the voltage level U _g the full supply voltage of the power supply 2 .
6. 6. Determination of voltage levels U _p and U _m the positive and negative voltage supply 2A . 2 B (= Determination of the voltage levels of the first and second actuation signal).

Subsequently or previously, the voltage level of the third actuation signal can be determined analogously thereto. This will be done in step 1 , the gate or base terminal of the circuit breaker switched to the voltage level of the third actuating signal (= applying the third actuation signal to the circuit breaker).

Specifically, the first operation signal and the second operation signal and the third operation signal are successively output to the power switch (in this order or in a different order). As a result, all the voltage values required for determining the associated voltage levels ( U _a1 . U _a2 . U _a3 ) successively to the A / D converter, which converts them into corresponding digital values. Subsequently, the numerical calculation of the corresponding voltage levels U _p . U _m occur.

LIST OF REFERENCE NUMBERS

1

driver circuit

2

power supply

2A

positive voltage supply

2 B

negative voltage supply

3

emergency command

4

medium

4A

measuring amplifiers

5

connection

A

exit

e +

positive input

E-

negative input

O

operational amplifiers

R1 ... R4

ohmic resistances

Claims (10)

Method for determining the voltage level (U _p , U _m ) of one of at least two actuation signals for actuating an electrical circuit breaker, wherein • the first actuation signal has an electrical voltage having a first voltage level (U _p ), and • the second actuation signal comprises an electrical voltage a second voltage level (U _m ), wherein the second voltage level (U _m ) is lower than the first voltage level (U _p ), and wherein in the process: • the at least two actuation signals successively to an input (E +) of a measuring amplifier ( 4A), which is supplied with a supply voltage of the second voltage level (U _m ), and • the thereby at an output (A) of the measuring amplifier (4A) successively applied at least two voltage values (U _a1 , U _a2 ) are determined, and Based on these at least two voltage values (U _a1 , U _a2 ) and on the basis of known resistance values (R1, R2, R3, R4) of the measuring amplifier (4A), the voltage level (U _p , U _m ) of the one of the at least two actuating signals are determined. Method according to Claim 1 , wherein the electrical circuit breaker is a circuit breaker of an inverter or inverter. Method according to Claim 1 or 2 for determining the voltage level (U _p , U _m ) of one of three actuation signals for actuating the electrical circuit breaker, wherein • the third actuation signal has an electrical voltage with a voltage level (U _p ), this voltage level (U _p ) being higher than that second voltage level (U _m ), in the context of the method: • the three actuating signals are applied successively to the input (E +) of the measuring amplifier (4A), and • the three thereby successively applied to the output (A) of the measuring amplifier (4A) Voltage values (U _a1 , U _a2 , U _a3 ) are determined, and • based on these three voltage values (U _a1 , U _a2 , U _a3 ) and based on the resistance values (R1, R2, R3, R4) of the measuring amplifier (4A), the voltage level (U _p , U _m ) of the one of the three actuating signals is determined. Method according to Claim 2 and 3 in which • the first actuation signal is a signal for closing the circuit breaker in the context of normal operation of the AC or inverter and • the second actuation signal is a signal for opening the circuit breaker, and • the third actuation signal is a signal for closing the circuit breaker in the context of an emergency operation , in particular a short circuit operation, the AC or inverter is. Method for monitoring an electrical circuit breaker, in particular a circuit breaker of an inverter or converter, wherein • a voltage level (U _p , U _m ) of one of at least two actuation signals of the circuit breaker by means of the method according to one of the preceding claims are determined, and • the determined voltage level ( U _p , U _m ) is compared with at least one limit value and / or the determined voltage level (U _p , U _m ) is examined for a change, and • a signal is generated when the determined voltage level (U _p , U _m ) Limit value below or exceeds, and / or the determined voltage level (U _p , U _m ) has undergone an impermissible change. Control unit for actuating electrical circuit breakers of an inverter or inverter, in particular a vehicle drive system, characterized in that the control device is designed to carry out the method according to one of the preceding claims. Control unit after Claim 6 comprising: a driver circuit (1) configured to generate the first and second actuation signals; a differential amplifier amplifying amplifier (4A) coupled to the driver circuit (1) and adapted to apply the actuation signals in in each case converting a corresponding voltage value (U _a1 , U _a2 , U _a3 ), an A / D converter which is coupled to the measuring amplifier (4A) and which is designed to measure the voltage values (U _a1 , U _a2 , U _a3 ) to a respective digital value, • a processing means, which is designed, on the basis of these digital values and on the basis of the resistance values (R1, R2, R3, R4) of the measuring amplifier (4A), the voltage level (U _p , U _m ) of at least one of To determine actuation signals. Control unit after Claim 7 , with • the driver circuit (1), which is designed to actuate the circuit breaker in a normal operation of the AC or inverter by means of the first and second actuation signal, • an emergency circuit (3) for generating a third actuation signal and for actuating the circuit breaker in an emergency operation of the AC or inverter is formed by means of the third actuating signal. Control unit after Claim 8 in which the emergency circuit (3) is a short-circuit circuit which is designed to generate the third actuation signal and to actuate the power switches in a short-circuit operation of the AC or converter by means of the third actuation signal. Vehicle drive system with an electric motor, in particular as a traction drive or as an actuator, and with an inverter or inverter for electrical energization of the electric motor, characterized by a control device for actuating electrical circuit breakers of the inverter or inverter according to one of Claims 6 to 9 ,

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