阅读说明：本技术 用于运行电压转换器的方法、电压转换器 (Method for operating a voltage converter, voltage converter ) 是由 M.埃尔曼 于 2018-12-06 设计创作，主要内容包括：本发明公开一种用于运行双向电压转换器(SW)的方法,所述双向电压转换器包括输入侧半桥电路(H1),其分别具有彼此串联连接的正电压侧晶体管开关(S1)和负电压侧晶体管开关(S2)；输出侧半桥电路(H2),其分别具有彼此串联连接的正电压侧晶体管开关(S3)和负电压侧晶体管开关(S4)；以及具有电桥电感(L)的电桥支路(BZ)；-其中在相应的当前开关循环T0中针对晶体管开关(S1、S2、S3、S4)的相应的后续开关循环T1确定流过电桥支路(BZ)的电桥电流(IL)的电桥电流实际平均值IL_avg_mess;-其中利用所确定的电桥电流实际平均值IL_avg_mess来针对相应的后续开关循环T1确定相应的晶体管开关(S1、S2、S3、S4)的接通时间点和接通持续时间；-其中在相应的后续开关循环T1中在相应的所确定的接通时间点接通相应的晶体管开关(S1、S2、S3、S4)并且使其接通相应的所确定的接通持续时间。(The invention discloses a method for operating a bidirectional voltage converter (SW), which comprises an input side half-bridge circuit (H1) having a positive voltage side transistor switch (S1) and a negative voltage side transistor switch (S2) connected in series with each other, respectively; an output side half-bridge circuit (H2) having a positive voltage side transistor switch (S3) and a negative voltage side transistor switch (S4) connected in series with each other, respectively; and a bridge Branch (BZ) having a bridge inductance (L); -wherein a bridge current actual average value IL _ avg _ mess of the bridge current (IL) flowing through the bridge Branch (BZ) is determined for a respective subsequent switching cycle T1 of the transistor switches (S1, S2, S3, S4) in a respective current switching cycle T0, -wherein the determined bridge current actual average value IL _ avg _ mess is used to determine an on-time point and an on-time duration of the respective transistor switch (S1, S2, S3, S4) for a respective subsequent switching cycle T1; -wherein in a respective subsequent switching cycle T1 the respective transistor switch (S1, S2, S3, S4) is turned on at the respective determined on-time point and for the respective determined on-time duration.)

1. A method for operating a bidirectional voltage converter (SW) comprising an input side half-bridge circuit (H1) having a positive voltage side transistor switch (S1) and a negative voltage side transistor switch (S2), respectively, connected in series with each other; an output side half-bridge circuit (H2) having a positive voltage side transistor switch (S3) and a negative voltage side transistor switch (S4) connected in series with each other, respectively; and a bridge Branch (BZ) having a bridge inductance (L);

-wherein a bridge current actual average value IL avg mess of a bridge current (IL) flowing through said bridge Branch (BZ) is determined for a respective subsequent switching cycle T1 of the transistor switches (S1, S2, S3, S4) in a respective current switching cycle T0;

-wherein the on-time point and the on-time duration of the respective transistor switch (S1, S2, S3, S4) are determined for the respective subsequent switching cycle T1 using the determined bridge current actual average value IL _ avg _ mess;

-wherein in the respective subsequent switching cycle T1 the respective transistor switch (S1, S2, S3, S4) is switched on at the respective determined on-time point and for the respective determined on-time duration.

2. The method according to claim 1, characterized in that the on-time and the on-time duration are determined in addition by a predefined bridge current setpoint mean value IL avg soll.

3. Method according to claim 2, wherein a current difference Δ I is calculated between the determined actual bridge current average value IL _ avg _ mess and the predefined nominal bridge current average value IL _ avg _ soll, and a duty rate correction value Δ DC is calculated using the current difference I, and further the switch-on time point and the switch-on duration are determined using the calculated duty rate correction value Δ DC.

4. The method of any one of the preceding claims, wherein

-in the respective present switching cycle T0, furthermore determining a bridge current momentary value Istart1a, Istart1b of a bridge current (IL) that should flow through the bridge Branch (BZ) at a point in time at which one of the transistor switches (S1, S2, S3, S4) is switched from the on-state to the off-state; istart2a, Istart2b, Istart3a, Istart3b, and

-additionally using the determined bridge current transients Istart1a, Istart1b; istart2a, Istart2b, Istart3a, Istart3b determine the switch-on time point and the switch-on duration.

5. The method of claim 4, wherein the bridge current momentary values Istart1a, Istart1b are determined from the charge exchange capacitances of the transistor switches (S1, S2, S3, S4) and the bridge inductances (L); istart2a, Istart2b; istart3a, Istart3 b.

6. The method according to claim 4 or 5, wherein the bridge current transients Istart1a, Istart1b; istart2a, Istart2b; istart3a, Istart3b determines a period duration in the respective subsequent switching cycle T1 and turns the transistor switch (S1, S2, S3, S4) on or off for the determined period duration in the respective subsequent switching cycle T1.

7. Method according to claims 2 and 6, wherein said period duration is furthermore determined by means of said bridge current actual average value IL avg mess.

8. The method of any one of the preceding claims,

-measuring an input voltage U1 at the input side half-bridge circuit (H1) and an output voltage U2 at the output side half-bridge circuit (H2) in the respective present switching cycle T0;

-comparing the input voltage U1 and the output voltage U2 with each other; and

-determining the on-time point, the on-time duration and/or the cycle duration from the result of the comparison between the input voltage U1 and the output voltage U2.

9. Method according to claims 2, 4 and 8, wherein in case of the following relation between the measured input voltage U1 and the measured output voltage U2:

where applicable k1>1, in particular k1=1.2, and, in the subsequent switching cycle T1,

-the positive voltage side transistor switch (S1) of the input side half bridge circuit (H1) is continuously switched on (permanently switched "high");

-the negative voltage side transistor switch (S2) of the input side half bridge circuit (H1) is continuously turned off (permanently switched "low");

-a negative voltage side transistor switch (S4) of the output side half bridge circuit (H2) is turned on for a first on-duration time tein _ S4 from the start of a switching cycle T1 and turned off for the remaining time of a period duration Tper of the subsequent switching cycle T1; and

-the positive voltage side transistor switch (S3) of the output side half bridge circuit (H2) is turned off for the first on-duration time tein _ S4 from the start of the switching cycle T1 and turned on for the remaining time of the period duration Tper of the subsequent switching cycle T1;

-wherein applicable for the first on-duration tein _ S4 are:

in thatIn the case of an ampere, the current,

or

In thatIn the case of an ampere, the current,

。

10. the method of claim 9, wherein the period duration Tper for a respective subsequent switching cycle T1 is determined according to the following equation:

in thatIn the case of an ampere, the current,or is or

In thatIn the case of an ampere, the current,。

11. method according to claims 2, 4 and 8, wherein in case of the following relation between the measured input voltage U1 and the measured output voltage U2:

where applicable k2<=1, in particular k2= 0.8 and k1>=1, in particular k1=1.2, in the subsequent switching period T1,

-the positive voltage side transistor switch (S1) of the input side half-bridge circuit (H1) and the negative voltage side transistor switch (S4) of the output side half-bridge circuit (H2) are turned on for a second on-duration tein _ S4 from the beginning of a switching cycle T1 and turned off for the remainder of the period duration Tper of the subsequent switching cycle T1;

-the negative voltage side transistor switch (S2) of the input side half-bridge circuit (H1) and the positive voltage side transistor switch (S3) of the output side half-bridge circuit (H2) are turned off for the second on-duration tein _ S4 from the beginning of the switching cycle T1 and are turned on for the remainder of the period duration Tper of the subsequent switching cycle T1,

-wherein applicable for the second on-duration tein _ S4 are:

in thatIn the case of an ampere, the current,

，

or

In thatIn the case of an ampere, the current,

。

12. the method of claim 11, wherein the period duration Tper for the respective subsequent switching cycle T1 is determined according to the following equation:

in thatIn the case of an ampere, the current,or is or

In thatIn the case of an ampere, the current,。

13. method according to claims 2, 4 and 8, wherein in case of the following relation between the measured input voltage U1 and the measured output voltage U2:

where applicable k2<1, in particular k2= 0.8, in the subsequent switching cycle T1:

-the positive voltage side transistor switch (S3) of the output side half bridge circuit (H2) is continuously switched on (permanently switched "high");

-the negative voltage side transistor switch (S4) of the output side half bridge circuit (H2) is continuously turned off (permanently switched "low");

-the positive voltage side transistor switch (S1) of the input side half bridge circuit (H1) is turned on for a third on-duration tein — S1 starting from switching cycle T1 and is turned off for the remaining of the period duration Tper of the subsequent switching cycle T1; and

-a negative voltage side transistor switch (S2) of the input side half bridge circuit (H1) is turned off for the third on-duration time tein _ S1 from the start of the switching cycle T1 and is turned on for the remaining time of the period duration Tper of the subsequent switching cycle T1,

-wherein applicable for the third on-duration tein _ S1 are:

in thatIn the case of an ampere, the current,

or

In thatIn the case of an ampere, the current,

。

14. the method of claim 13, wherein the period duration Tper for the respective subsequent switching cycle T1 is determined according to the following equation:

in thatIn the case of an ampere, the current,or is or

In thatIn the case of an ampere, the current,。

15. a voltage converter (SW) for bidirectional voltage conversion, comprising:

-an input side half-bridge circuit (H1) having a positive voltage side transistor switch (S1) and a negative voltage side transistor switch (S2), respectively, connected in series with each other;

-an output side half-bridge circuit (H2) having a positive voltage side transistor switch (S3) and a negative voltage side transistor switch (S4), respectively, connected in series with each other;

-a bridge Branch (BZ) having a bridge inductance (L);

-measuring means (A, V1, V2) which are set up for measuring the bridge current (IL) flowing through the bridge Branch (BZ) over the entire present switching cycle T0 for a respective subsequent switching cycle T1 of the transistor switches (S1, S2, S3, S4) over the respective present switching cycle;

-determining means (EA) set up for determining a bridge current actual average value IL _ avg _ mess from the measured bridge current (IL) and determining from said bridge current actual average value IL _ avg _ mess, for said respective subsequent switching cycle T1, an on-time point and an on-time duration of the respective transistor switch (S1, S2, S3, S4);

-control means (GT 1, GT2, GT3, GT 4) which are set up for switching on the respective transistor switch (S1, S2, S3, S4) and for switching it on for the respective determined on-time at the respective determined on-time point in the respective subsequent switching cycle T1.

The technical field is as follows:

the invention relates to a method for operating a bidirectional voltage converter and to a bidirectional voltage converter.

Background

Disclosure of Invention

This object is achieved by the subject matter of the independent claims. Advantageous embodiments are the subject matter of the dependent claims.

According to a first aspect of the invention, a method is provided for operating a bidirectional voltage converter, in particular a bidirectional dc voltage converter, comprising an input-side half-bridge circuit having a positive-side transistor switch and a negative-side transistor switch, respectively, which are connected in series with one another; an output side half-bridge circuit having a positive voltage side transistor switch and a negative voltage side transistor switch connected in series with each other, respectively; and a bridge branch having a bridge inductance L or in the form of a coil between the center taps of the two half-bridge circuits.

According to the method, the actual average value IL _ avg _ mess of the bridge current flowing through the bridge branch in the respective present switching cycle T0 is measured or determined for the respective subsequent switching cycle T1 of the transistor switches in the respective present switching cycle T0. The actual average value IL avg mess of the bridge current is here the arithmetic average of the bridge current measured in the current switching cycle T0.

The determined actual average value of the bridge current IL avg mess is then used (or based) to determine the on-time point and on-time duration of the respective transistor switch for the respective subsequent switching cycle T1. Then, in a respective subsequent switching cycle T1, the respective transistor switch is switched on at the respective determined on-time point and for the respective determined on-duration.

The invention is based on the idea that the switching losses at the transistor switches are the dominant part of the total power loss at the voltage converter.

In order to reduce the total power loss, the switching losses in all operating points of the voltage converter should be reduced or eliminated to the greatest extent possible. Since the operating point is in turn dependent on the bridge current, the bridge current is taken into account for determining the switch-on time point and the switch-on duration. Since the bridge current in turn varies over the switching cycle, the actual average value IL avg mess of the bridge current is taken into account for the determination. The on-time and the on-time determined on the basis of this bridge current actual average value IL _ avg _ mess ensure that: when one of the transistors is switched off, a bridge current with a predefined momentary current value, which ensures a natural commutation to the transistor switch that is opposite in potential to the transistor switch to be switched off, flows through the bridge inductance. If the voltage applied to the respective transistor switch to be switched on is approximately 0 volts ("zero voltage Switching"), then each of the transistor switches is always switched on after successful natural commutation. The method ensures "zero-voltage switching" independently of the input voltage, the output voltage, the current direction and the current value.

Thus, a possibility is provided to reduce the power loss of the bi-directional voltage converter.

In particular, the transistor switches are periodically turned on and off using a pulse width modulated signal and using a variable signal.

For example, the on-time and the on-time duration are also determined using a predefined nominal average value IL _ avg _ soll of the bridge current.

In this case, the nominal bridge current mean value IL _ avg _ soll is the mean value of the bridge current which should flow through the bridge branch, i.e. through the bridge inductance, during switching cycle T1. The bridge current setpoint mean value IL _ avg _ soll is predefined as a control variable or is determined and predefined from a control variable and a measured variable, in particular from the input and output voltages U1, U2 of the voltage regulator.

For example, the current difference I is calculated between the determined actual bridge current average value IL _ avg _ mess and the predefined nominal bridge current average value IL _ avg _ soll, where: . Then, the duty rate correction value Δ DC is calculated from the current difference Δ I. Then, the on-time point and the on-duration are determined from the calculated duty ratio correction value DC in addition.

For example, in the respective current switching cycle T0, the bridge current momentary values Istart1a, Istart1b of the bridge current which is to flow through the bridge branch at the point in time at which one of the transistor switches is switched from the on state to the off state are additionally measured or determined; istart2a, Istart2b, Istart3a, Istart3 b. Then, the determined bridge current transients Istart1a, Istart1b are additionally used; istart2a, Istart2b, Istart3a, Istart3b determine the point in time and the duration of the switch-on. In this case, the bridge current transient always has a different sign than the nominal mean value of the bridge current.

In this case, the bridge current transient is the transient reached in the present switching cycle T0 immediately before one of the transistor switches is turned off in order to ensure natural commutation.

For example, bridge current transients Istart1a, Istart1b; istart2a, Istart2b, Istart3a, Istart3b are determined from the charge exchange capacitance of the transistor switches and the bridge inductance L.

Using bridge current transients Istart1a, Istart1b; istart2a, Istart2b, Istart3a, Istart3b determine the on-time and off-time points of the transistor switches for the subsequent switching cycle T1.

In this case, the period duration Tper is the sum of the durations of the respective on-durations and off-durations of the respective individual transistor switches.

The period duration is determined, for example, also by the actual average value of the bridge current IL avg mess.

For example, in the respective current switching cycle T0, the input voltage U1 is measured at the input side half bridge and the output voltage U2 is measured at the output side half bridge. The measured input and output voltages U1, U2 are then compared with each other. The switch-on time point, the switch-on duration and/or the cycle duration are then determined, for example, as a function of the comparison between the input voltage U1 and the output voltage U2.

For example, in addition to the charge exchange capacitances of the transistor switches and the bridge inductances L, bridge current transients Istart1a, Istart1b are also determined, for example, from the input and output voltages U1, U2; istart2a, Istart2b, Istart3a, Istart3 b.

Case 1:

in the case of the following relationship between the measured input voltage U1 and the measured output voltage U2, namely where applicable:

wherein k1>1, in particular k1=1.2, in the subsequent switching cycle, for example:

the positive voltage side transistor switch of the input side half-bridge circuit is continuously switched on (i.e. permanently switched "high");

the negative voltage side transistor switch of the input side half-bridge circuit is continuously switched off (i.e. permanently switched "low");

the negative voltage side transistor switch of the output side half bridge circuit is switched on for a first on-time tein _ S4 from the beginning of the switching cycle T1 and is switched off for the remaining time of the period duration Tper of the subsequent switching cycle T1; and

the positive voltage side transistor switch of the output side half bridge circuit is switched off for a first on-duration tein _ S4 from the beginning of the switching cycle T1 and is switched on for the remaining time of the period duration Tper of the subsequent switching cycle T1.

Here, for the first on-time tein _ S4:

in thatIn the case of amperes (where the predetermined bridge current transient Istart1a is less than 0 amperes (or has a different sign than the predetermined bridge current nominal average value IL avg soll), and is reached when the positive voltage side transistor switches of the output side half bridge circuit are turned off),

or

In thatIn the case of amperes (where the predetermined bridge current transient Istart1b is greater than 0 amperes (or has a different sign than the predetermined nominal average bridge current value IL avg soll), and is reached when the negative voltage side transistor switches of the output side half bridge circuit are turned off),

。

in case 1, the period duration Tper for the respective subsequent switching cycle T1 is determined, for example, according to the following equation:

in thatIn the case of an ampere, the current,or is or

In thatIn the case of an ampere, the current,。

case 2:

in the case of the following relationship between the measured input voltage U1 and the measured output voltage U2, namely where applicable:

wherein k1>1, in particular k1=1.2, and k2<1, in particular k2= 0.8, in the following switching cycle, for example:

the positive voltage-side transistor switch of the input-side half-bridge circuit and the negative voltage-side transistor switch of the output-side half-bridge circuit are switched on for a second on-duration tein _ S4 from the beginning of the switching cycle T1 and are switched off for the remainder of the period duration Tper of the subsequent switching cycle T1; and

the negative voltage side transistor switch of the input side half-bridge circuit and the positive voltage side transistor switch of the output side half-bridge circuit are switched off from the beginning of the switching cycle T1 for a second on-duration tein _ S4 and are switched on for the remaining time of the period duration Tper of the subsequent switching cycle T1.

Here, for the second on-time tein _ S4:

in thatIn the case of amperes (in which the predefined bridge current transient Istart2a is less than 0 amperes (or has a different sign than the predefined bridge current nominal average value IL avg soll), and is reached when the negative voltage side transistor switches of the input side half-bridge circuit and the positive voltage side transistor switches of the output side half-bridge circuit are turned off),，

or

In thatIn the case of amperes (in which the predetermined bridge current transient Istart2b is greater than 0 amperes (or has a different sign than the predetermined nominal average bridge current value IL avg soll), and is reached when the positive voltage side transistor switches of the input side half bridge circuit and the negative voltage side transistor switches of the output side half bridge circuit are turned off),

。

in case 2, the period duration Tper for the respective subsequent switching cycle T1 is determined, for example, according to the following equation:

in thatIn the case of an ampere, the current,or is or

In thatIn the case of an ampere, the current,。

case 3:

in the case of the following relationship between the measured input voltage U1 and the measured output voltage U2, namely where applicable:

wherein k2<1, in particular k2= 0.8, in the subsequent switching cycle, for example:

the positive voltage side transistor switch of the output side half-bridge circuit is continuously switched on (i.e. permanently switched "high");

the negative voltage side transistor switch of the output side half-bridge circuit is continuously switched off (i.e. permanently switched "low");

the positive voltage side transistor switch of the input side half bridge is switched on for a third on-duration time tein _ S1 starting from switching cycle T1 and is switched off for the remaining time of the period duration Tper of the subsequent switching cycle T1; and

the negative voltage side transistor switch of the input side half bridge is switched off for a third on-duration time tein _ S1 from the beginning of the switching cycle T1 and is switched on for the remaining time of the period duration Tper of the subsequent switching cycle T1.

Here, for the third on-time tein _ S1:

in thatIn the case of amperes (where the predetermined bridge current transient Istart3a is less than 0 amperes (or has a different sign than the predetermined nominal average bridge current value IL avg soll), and is reached when the negative voltage side transistor switches of the input side half bridge circuit are turned off),

or

In thatIn the case of amperes (in which the predetermined bridge current transient Istart3b is greater than 0 amperes (or has a different sign than the predetermined nominal average bridge current value IL avg soll), and is reached when the positive voltage side transistor switches of the input side half bridge circuit are turned off),

。

in case 3, the period duration Tper for the respective subsequent switching cycle T1 is determined, for example, according to the following equation:

in thatIn the case of an ampere, the current,or is or

In thatIn the case of an ampere, the current,。

according to a further aspect of the invention, a voltage converter for bidirectional voltage conversion, in particular a dc voltage converter, is provided.

The voltage converter includes an input side half-bridge circuit having a positive voltage side transistor switch and a negative voltage side transistor switch connected in series with each other, respectively.

The voltage converter furthermore comprises an output-side half-bridge circuit having in each case a further positive-side transistor switch and a further negative-side transistor switch which are connected in series with one another.

The voltage converter furthermore comprises a bridge branch having a bridge inductance L or in the form of a coil between the center taps of the two half-bridge circuits.

The voltage converter furthermore comprises a measuring device which is set up to measure the bridge current flowing through the bridge branch over the entire current switching cycle for a respective subsequent switching cycle of the four transistor switches (two half-bridge circuits) in the respective current switching cycle.

The voltage converter furthermore comprises a determination device which is set up to determine the bridge current actual average value IL _ avg _ mess from the measured bridge currents and to determine the on-time and the on-time of the respective transistor switch for the respective subsequent switching cycle T1 from the bridge current actual average value IL _ avg _ mess.

The voltage converter furthermore comprises a control device, which is set up to switch on the respective transistor switch at the respective determined switch-on time point and for the respective determined switch-on duration in the respective subsequent switching cycle T1.

The advantageous configuration of the method described above can be transferred to the voltage converter mentioned above whenever possible and is also considered to be an advantageous configuration of the voltage converter.

Description of the drawings:

exemplary embodiments of the present invention are explained in more detail below with reference to the attached drawings. The sole figure here shows a bidirectional H-bridge voltage converter SW according to an exemplary embodiment of the invention in a schematic diagram.

Detailed Description

The voltage converter SW is electrically connected on the current input side to an input voltage U1 via two current input terminals a11, a12 and on the current output side to an output voltage U2 via two current output terminals a21, a 22. The voltage converter SW is used for bidirectional voltage conversion between an input voltage and output voltages U1, U2.

The voltage converter SW comprises an input side half-bridge circuit H1, the input side half-bridge circuit H1 having a positive and a negative voltage side transistor switch S1, S2, respectively, electrically connected in series with each other and between two current input terminals a11, a 12.

The voltage converter SW furthermore comprises an output-side half-bridge circuit H2 having a positive-side transistor switch and a negative-side transistor switch S3, S4, respectively, which are electrically connected in series with each other and between the two current output terminals a21, a 22.

The voltage converter SW furthermore comprises a bridge branch BZ, which electrically connects the two half-bridge circuits H1, H2 or their center taps to one another. A bridge inductance L in the form of a coil is electrically connected in the bridge branch BZ.

The voltage converter SW furthermore comprises two capacitors C1 and C2, which capacitors C1 and C2 are electrically connected between the two current input terminals a11, a12, respectively, and are therefore electrically connected in parallel with the input-side half-bridge circuit H1, or are electrically connected between the two current output terminals a21, a22, and are therefore electrically connected in parallel with the output-side half-bridge circuit H2. Capacitors C1 and C2 are used to smooth the input or output voltage U1, U2.

The voltage converter SW furthermore comprises a measuring device comprising a current meter a and two voltage meters V1, V2.

A current meter a is connected in series with the coil in the bridge branch BZ and is used to measure a bridge current IL flowing through the bridge branch BZ.

Two voltmeters V1, V2 are connected between the two current input terminals a11, a12 or between the two current output terminals a21, a22, respectively, and serve to measure the input or output voltages U1, U2, respectively.

The voltage converter SW furthermore comprises a determination device EA, which is connected on the signal input side to the signal output of the current meter/voltage meter A, V1, V2 in terms of signals. The determination means EA obtain the measurements of the bridge current IL and the two voltages U1, U2 from the current meter/voltmeter A, V1, V2 via a signal connection. The determination means EA are furthermore set up to determine the period duration, the on-time point and the on-time of the respective transistor switch S1, S2, S3, S4 for the respective subsequent switching cycle as a function of the measured current and voltage values.

The voltage converter SW furthermore comprises control means for controlling the four transistor switches S1, S2, S3, S4. The control means comprises four gate drivers GT1, GT2, GT3, GT4 for operating a respective one of four transistor switches S1, S2, S3, S4.

The gate drivers GT1, GT2, GT3, GT4 are each connected in signal terms on the signal input side to one of the four signal outputs of the determination means EA and on the control signal output side to the control terminals of the respective transistor switches S1, S2, S3, S4. The gate drivers GT1, GT2, GT3, GT4 are set up for switching on/off the respective transistor switches S1, S2, S3, S4 in a controlled manner in the respective switching cycle on the basis of the period duration, the point in time of switching on and the time of switching on determined by the determination means EA.

After describing the circuit topology of the voltage converter SW according to the figures, the method for manipulating the voltage converter SW or the four transistor switches S1, S2, S3, S4 will be described in more detail below:

first, the two voltage meters V1, V2 and the current meter a measure the input and output voltages U1, U2 and the bridge current IL flowing through the bridge branch in the respective current switching cycle T0. In this case, current meter a measures bridge current IL over the entire duration of current switching cycle T0.

The determination means EA determine the actual average value of the bridge current IL _ avg _ mess from the bridge current measurement values. The determination device EA determines, among other manipulated variables, the bridge current setpoint average IL _ avg _ soll from the measured input and output voltages U1, U2 and presets this as a manipulated variable.

According to the equation:the determining means EA calculates the current difference Δ I from the actual bridge current average IL _ avg _ mess and the predefined nominal bridge current average IL _ avg _ soll. Then, the determination device EA calculates a duty ratio correction value from the current difference I∆DC。

Furthermore, the determination means EA determine from the previously known charge exchange capacitances (Umladekapazit ä t) and bridge inductances L of the transistor switches S1, S2, S3, S4 and the input and output voltages U1, U2 bridge current momentary values Istart1a, Istart1b, Istart2a, Istart2b, Istart3a or Istart3b which should flow through the bridge branch BZ at the point in time when one of the transistor switches S1, S2, S3, S4 is switched from the on-state to the off-state.

Furthermore, the determination means EA compare the input and output voltages U1, U2 with one another. From the comparison of the two voltages U1, U2, the determination means EA determine the period duration, the on-time point and the on-time duration of all four transistor switches S1, S2, S3, S4 for the subsequent switching cycle T1 as described below.

The control means or gate drivers GT1, GT2, GT3 and GT4 control the respective transistor switches S1, S2, S3, S4 in the respective subsequent switching cycle based on the determined period duration, on-time point and on-time duration.

Case 1: the output voltage U2 is greater than the output voltage U1, where applicable:

wherein k1>1, in particular k1= 1.2.

In this case, the transistor switches S1, S2, S3, S4 are operated as follows in the subsequent switching cycle T1:

the positive voltage side transistor switch S1 of the input side half-bridge circuit H1 is continuously turned on (i.e. switched permanently "high").

The negative voltage side transistor switch S2 of the input side half bridge H1 is continuously turned off (i.e. permanently switched "low").

The negative voltage side transistor switch S4 of the output side half-bridge circuit H2 is switched on for a first on-duration time tein _ S4 from the beginning of the switching cycle T1 and is switched off for the remaining time of the period duration Tper of the subsequent switching cycle T1.

The positive voltage side transistor switch S3 of the output side half-bridge circuit H2 is switched off for a first on-duration tein _ S4 from the beginning of the switching cycle T1 and is switched on for the remaining time of the period duration Tper of the subsequent switching cycle T1.

Here, the first on-duration time tein _ S4 is determined according to the following equation:

in thatIn the case of amperes (i.e. the bridge current IL should flow from the input side half-bridge circuit H1 into the output side half-bridge circuit H2),

or

In thatIn the case of amperes (i.e. the bridge current IL should flow from the output side half-bridge circuit H2 into the input side half-bridge circuit H1),

。

the period duration Tper is determined according to the following equation:

in thatIn the case of an ampere, the current,or is or

In thatIn the case of an ampere, the current,。

case 2: the output voltage U2 is approximately the same size as the input voltage, where applicable:

wherein k1>1, in particular k1=1.2, and k2<1, especially k2= 0.8.

In this case, the transistor switches S1, S2, S3, S4 are operated as follows in the subsequent switching cycle T1:

the positive voltage-side transistor switch S1 of the input-side half-bridge circuit H1 and the negative voltage-side transistor switch S4 of the output-side half-bridge circuit H2 are switched on for a second on-duration tein _ S4 from the beginning of the switching cycle T1 and are switched off for the remainder of the period duration Tper of the subsequent switching cycle T1.

The negative voltage-side transistor switch S2 of the input-side half-bridge circuit H1 and the positive voltage-side transistor switch S3 of the output-side half-bridge circuit H2 are switched off from the beginning of the switching cycle T1 for a second on-duration tein _ S4 and are switched on for the remainder of the period duration Tper of the subsequent switching cycle T1.

Here, the second on-duration time tein _ S4 is determined according to the following equation:

in thatIn the case of amperes (i.e. the bridge current IL should flow from the input side half-bridge circuit H1 into the output side half-bridge circuit H2),

，

or

In thatIn the case of amperes (i.e. the bridge current IL should flow from the output side half-bridge circuit H2 into the input side half-bridge circuit H1),

。

the period duration Tper is determined according to the following equation:

in thatIn the case of an ampere, the current,or is or

In thatIn the case of an ampere, the current,。

case 3: the output voltage U2 is smaller than the input voltage U1, where applicable:

wherein k2<1, especially k2= 0.8.

In this case, the transistor switches S1, S2, S3, S4 are operated in the subsequent switching cycle T1 as follows:

the positive voltage side transistor switch S3 of the output side half-bridge circuit H2 is continuously turned on (i.e. permanently switched "high").

The negative voltage side transistor switch S4 of the output side half bridge circuit H2 is continuously turned off (i.e. permanently switched "low").

The positive voltage side transistor switch S1 of the input side half-bridge circuit H1 is switched on for a third on-duration tein _ S1 starting from the switching cycle T1 and is switched off for the remaining time of the period duration Tper of the subsequent switching cycle T1.

The negative voltage side transistor switch S2 of the input side half-bridge circuit H1 is switched off for a third on-duration tein _ S1 from the beginning of the switching cycle T1 and is switched on for the remaining time of the period duration Tper of the subsequent switching cycle T1.

Here, the third on-duration time tein _ S1 is determined according to the following equation:

in thatIn the case of amperes (i.e. the bridge current IL should flow from the input side half-bridge circuit H1 into the output side half-bridge circuit H2),

or

In thatIn the case of amperes (i.e. the bridge current IL should flow from the output side half-bridge circuit H2 into the input side half-bridge circuit H1),

。

the period duration Tper is determined according to the following equation:

in thatIn the case of an ampere, the current,or is or

In thatIn the case of an ampere, the current,。

thus, the three cases previously described cover three regions in which all possible relationships of the input and output voltages U1, U2 apply: u2 & lt U1 and U2U1 or U2 > U1.

Relationships betweenAmpere orThe amperes indicate the nominal current direction of the bridge current IL.

The two factors k1 and k2 must be selected such that, with a given voltage measurement accuracy at the input and output voltages U1 and U2, it is furthermore ensured that the equation in case 2 applies in the case of U1= U2.

The above described method has the following advantages: in all cases, where one of the following relationships applies, the voltage converter SW can be switched (bi-directionally) and with low power loss:

-atOrWhile, U1>U2 (case 1);

-atOrWhen, U1= U2 (case 2);

-atOrWhile, U1<U2 (case 3);

the method ensures that: the Voltage converter SW can be operated in ZVS Mode (Zero Voltage Switching Mode), independently of the operating point, i.e. independently of the Voltage dependence, the current direction and the current magnitude, the Switching losses of the transistor switches S1, S2, S3 and S4 being largely eliminated in all operating points of the Voltage converter SW and the total power loss being reduced to a minimum.

Since the gate drivers GT1, GT2, GT3, GT4, the current/voltage meter A, V1, V2, which perform part of the method, already exist as components for regulating the voltage converter SW themselves, only the determination means EA are required in addition to performing the method. Since the determination means EA can also be implemented functionally as an already existing regulator of the voltage converter SW, the voltage converter SW can be implemented without additional circuit components and therefore without additional installation space.

Since the total power loss is reduced, a low cooling effort is required, and a correspondingly small dimensioned cooling device for the voltage converter SW is therefore required.

The described method is used in particular in motor vehicles, in particular hybrid/electric vehicles, in which electric power is to be transmitted with low losses by means of one or more inexpensive H-bridge voltage converters SW.

Examples of such applications are:

a step-up Converter ("Boost Converter") for adapting the battery voltage to the inverter voltage (dc-dc application, i.e. converting the output voltage of a dc voltage source into a charging voltage for a dc voltage sink (gleichspans-Senke));

a Buck-Boost Converter (Buck-Boost Converter, english) for adapting the battery voltage to the voltage of the dc charging station (dc-dc application, i.e. converting the output voltage of the dc charging station into a charging voltage for the battery;

a buck-boost converter (rectification, ac-dc application) for adapting the ac charging station ac voltage to the battery voltage;

buck-boost converters (e.g. electric machines, dc-AC applications) for adapting the battery voltage to the nominal voltage of an AC-operated device.

In particular, a reduction in the switching power loss is achieved, wherein, depending on the operating point (input voltage U1, output voltage U2, actual bridge current and rated bridge current), for the respectively following switching cycle T1, the transistor switches S1, S2, S3, S4 of the half-bridge circuits H1, H2 are switched on for the calculated on-duration and switched off for the calculated off-duration. In this case, the respective calculation is carried out such that, when one of the transistor switches S1, S2, S3, S4 is switched off, a previously defined bridge current flows through the bridge inductance, which bridge current ensures a natural commutation to the potential-opposing transistor switch S1, S2, S3, S4. In this case, if a voltage of approximately 0 volt is applied to the transistor switches S1, S2, S3, S4 ("Zero volt switching" in english), the transistor switches S1, S2, S3, S4 are always switched on after a successful natural commutation, in particular a switching action is carried out such that, when one of the transistor switches S1, S2, S3, S4 is switched off, the bridge current at the bridge inductance L has a flow direction and a minimum amplitude, so that the voltage is commutated by just this bridge current and not by switching on the complementary transistor (transistor S3 is here complementary to transistor S4, transistor S4 is complementary to transistor S3, transistor S1 is complementary to transistor S2, transistor S2 is complementary to transistor S1).

The described method has decisive advantages: ZVS operation can be maintained not only in all fixed operating points but also in the case of a change in operating point ("zero-voltage switching" operation), but also in three possible relationships between input voltage and output voltage: with U1< U2, U1= U2, U1> U2, ZVS operation is maintained for all operating states.

As already mentioned, the input and output voltages U1, U2 are measured. The nominal average value of the bridge current IL _ avg _ soll and the instantaneous values of the bridge current Istart1a, Istart1b, Istart2a, Istart2b; istart3a, Istart3b are predefined. From these values the cycle duration, the on-time point and the on-time are determined and thereby the duty cycle is determined. The bridge current nominal average value IL _ avg _ soll and bridge current transients Istart1a, Istart1b may be utilized using the methods described above; istart2a, Istart2b; istart3a, Istart3b remove the unreliability with respect to the resulting bridge current variation process parallel offset by an arbitrary offset over the switching period of the current triangle resulting from the period duration, the on-time point and the on-time.