Modular brake actuator structure and method of operation

Abstract

The present invention relates to a modular brake actuator (1) having sub-modules (2). In order to improve the modular brake actuator (1), the present invention proposes that a first sub-module group (21), a second sub-module group (22) and a braking resistor (3) are arranged in a first series circuit (14) between two terminals (13) of the modular brake actuator (1), wherein the braking resistor (3) is electrically arranged between the first sub-module group (21) and the second sub-module group (22), wherein the first sub-module group (21) and the second sub-module group (22) respectively include at least one sub-module (2), another braking resistor (31) and a capacitor (7), wherein a second series circuit (15) including the other braking resistor (31) and the capacitor (7) is arranged to be electrically connected in parallel with at least one sub-module (2) of the at least one sub-module (2). The present invention also relates to a modular drive unit (10) comprising a modular multilevel power converter (11) and a modular brake actuator (1) of this type, wherein the multilevel power converter (11) is connected to the modular brake actuator (1) on the DC voltage side. The present invention further relates to an operating method for a modular brake actuator (1) of this type or for a modular drive unit (10) of this type, wherein a first AC voltage component (u) is generated by a submodule (2) of the first submodule group (21). BR,AC,1 ), and the second AC voltage component (u) is generated by the submodule (2) of the second submodule group (22). BR,AC,2 ), where the first AC voltage component (u BR,AC,1 ) and the second AC voltage component (u BR,AC,2 They are opposite in phase.

Description

Technical Field

[0001] This invention relates to a modular brake actuator, wherein a first submodule group and a braking resistor are arranged in series between two terminals of the modular brake actuator, and wherein the first submodule group includes at least one submodule. The invention further relates to a modular drive unit comprising a modular multilevel power converter and a modular brake actuator of this type. The invention further relates to a method of operation for such a modular brake actuator or for such a modular drive unit. Background Technology

[0002] The modular multilevel power converter is described in DE 10 103 031 A1. This converter (also known as M2C or MMC) includes a converter topology particularly suitable for medium and high voltage applications due to its submodule construction. The basic structure of the multiphase converter includes two converter arms for each phase, each converter arm comprising a series circuit of a submodule. These two converter arms are connected to each other at the phase terminals. The other side of the converter arm is connected to the DC voltage side of the multilevel power converter. The AC voltage side of the modular multilevel power converter is formed by one or more phase terminals. In its basic design, the modular multilevel power converter is capable of bidirectionally transferring energy between the DC and AC voltage sides or temporarily storing it to some extent.

[0003] To further achieve the target energy dissipation, it is advantageous to install a brake actuator. A modular brake actuator is known from WO 2007 / 023061A2. This modular brake actuator is typically connected to the DC voltage side of the modular multilevel power converter, for example, between the DC+ and DC- terminals.

[0004] The resistor in a brake actuator device is often referred to as a brake resistor because it is suitable for converting electrical energy from a motor generated during braking operations into heat. In this document, the use of brake actuators is not limited to applications involving electric brake drives. Therefore, it does not necessarily have to be braking energy that is converted into heat. For example, brake actuators can also be used to stabilize the power grid by converting electrical energy from the grid into heat. The term brake resistor is chosen to distinguish it from other resistors in which predefined electrical energy or power is converted into heat or heat per unit time.

[0005] Here, the power to be converted into heat refers to the integral of power over time that is converted into heat. In other words, the amount of energy generated by electricity over time is converted into heat.

[0006] A series circuit is defined as a circuit in which the same current flows through the same components. A series circuit with partial impedances acts as a single pair of poles with an impedance corresponding to the sum of the partial impedances. Summary of the Invention

[0007] This invention is based on the purpose of improving modular brake actuators.

[0008] This task is accomplished by a modular brake actuator, wherein a first submodule group, a second submodule group, and a braking resistor are arranged in a first series circuit between two terminals of the modular brake actuator. The braking resistor is electrically connected between the first and second submodule groups. Each of the first and second submodule groups includes at least one submodule, another braking resistor, and a capacitor. A second series circuit consisting of the additional braking resistor and the capacitor is arranged in electrical parallel with at least one of the at least one submodules. Furthermore, this task is accomplished by a modular drive unit, which includes a modular multilevel power converter and this type of modular brake actuator, with the multilevel power converter connected to the modular brake actuator on the DC voltage side. The problem is further addressed by an operating method for this modular brake actuator or for this modular drive unit, wherein the submodules of the first submodule group generate a first AC voltage component, and the submodules of the second submodule group generate a second AC voltage component, wherein the first and second AC voltage components are opposite in phase.

[0009] Other advantageous embodiments of the invention are described in the dependent claims.

[0010] This invention is particularly based on the understanding that energy balance (and therefore the stability of the modular brake actuator) within the submodules can be achieved in a particularly simple manner. The basic structure includes the first submodule group, the second submodule group, and the braking resistor. Each submodule group includes at least one submodule. To extend the operating range relative to the operating voltage of the brake actuator, when used with a power converter, the brake actuator corresponds to the DC link voltage of the power converter; the corresponding submodule group can include multiple submodules, meaning at least two submodules. A parallel current path is arranged in parallel with the submodule or at least one of the submodules. Preferably, the parallel current path is arranged in parallel with the series circuit of all the submodules in the corresponding submodule group. The parallel current path is constructed such that it includes an additional braking resistor and is capable of suppressing the formation of DC current in the parallel current path. A capacitor is advantageously used to suppress the DC current.

[0011] By applying a DC voltage U across the two submodule groups SM,DC,1 / 2 It can generate a DC voltage U across the braking resistor R1.R It generates a DC current i through the modular brake actuator. DC Therefore, the following applies:

[0012] Advantageously, DC voltage U SM,DC,1 / 2 It can be evenly distributed across the two submodule groups; in this case, the DC voltage U across the respective submodule groups is calculated using the following formula. SM,DC,1 and U SM,DC,2 :

[0013] The DC current i flowing through the modular brake actuator DC For a given value, when multiplied by the DC link voltage or the voltage at the terminals of the modular brake actuator, this value equals the power to be converted into heat. DC current i DC It is calculated in the following way:

[0014] Therefore, the modular brake actuator can be controlled or adjusted so that a DC current i is generated by the modular brake actuator depending on the power to be converted into heat. DC The modular brake actuator is connected via this DC current (i DC Absorbed power.

[0015]

[0016] In this process, power

[0017] The power P absorbed by the brake actuator is converted into heat in the braking resistor R1. BS The power P that is converted into heat in the braking resistor R1 The difference between them must be dissipated in the other resistors. This ensures that the capacitors of the submodule (also referred to as submodule capacitors for clarity) maintain their charge evenly over time and do not charge or discharge to unacceptable levels. In other words, energy balance ensures the stable operating point of the modular brake actuator. The power P to be dissipated in these two additional resistors... R2a / b Therefore it is

[0018] This can, for example, be evenly distributed across two other resistors R. 2a R 2bIn this process, power is generated in an additional resistor through the AC voltage across the submodule group. Because the AC voltage is a component of the voltage across the submodule group, it is also called the AC voltage component. The same applies to the DC voltage across the submodule group, which is also called the DC voltage component. Advantageously, the phase difference between the AC voltage of the first submodule group and the AC voltage of the second submodule group is 180°. In other words, the AC voltages of the first and second submodule groups are opposite in phase. This ensures that no AC current appears at the terminals of the modular brake actuator. Therefore, only the DC current i DC The voltage applied to the brake actuator does not cause voltage fluctuations in the DC link. This allows the modular brake actuator to operate without loading harmonics into the DC link.

[0019] If the additional resistor has the same resistance value, the power consumed in the additional resistor is given by the following formula:

[0020] Because of the capacitor in the second series circuit, the higher the frequency of the AC voltage component, the larger the AC current through resistor R2. Current i R2 And therefore the power P R2 Therefore, control can be advantageously achieved using the frequency and / or additionally the amplitude of the AC voltage component. For example, this control can be based on the magnitude of the capacitor voltage of the submodule. Under energy balance, the DC link voltage remains constant on average. Therefore, for example, as the capacitor voltage increases, the frequency and / or amplitude of the AC voltage component can increase, and as the capacitor voltage decreases, the frequency and / or amplitude of the AC voltage component can decrease. Thus, a stable operating point can be achieved, for example, using a PI controller. This ensures that the energy absorbed by the submodule from the DC current is converted into heat by the additional resistors in each submodule group, such that, on average, the submodule does not absorb energy over time (minus electrical losses in the submodule).

[0021] The AC voltage component can be any AC signal, such as a sine wave, square wave, triangular wave, trapezoidal wave, etc.

[0022] For those with û SM，AC The amplitude of the AC voltage component is a sinusoidal waveform, and the amplitude of the current is...

[0023] Therefore, active power

[0024] Based on this formula, it is clear that the power consumed in other resistors can be controlled or regulated by the amplitude of the AC voltage and / or also by the frequency of the AC voltage components.

[0025] Therefore, the voltage across each submodule group includes a DC voltage component, which causes a DC current to flow through the modular brake actuator and the braking resistor. Additionally, the voltage across each submodule group includes an AC voltage component, which causes an AC current across the submodule group to flow through an additional resistor in the parallel current path of the second series circuit. A capacitor connected in series with the additional braking resistor prevents the DC voltage from affecting the current flowing through the additional braking resistor. The current flowing through the additional braking resistor can thus be controlled by the AC voltage, independent of the DC current and the power consumption of the modular brake actuator. Simultaneously, the opposite phase of the AC voltages from the first and second submodule groups reliably prevents current from flowing through the braking resistor and forming an AC current at the terminals of the modular brake actuator. This allows individual parameters to be controlled independently of each other. This allows the power dissipated by individual resistors to be controlled and regulated independently of each other, enabling the regulation of the power converted into heat by the brake actuator and the stable setting of the operating point. This results in a simple control structure for the modular brake actuator, enabling stable operation. The DC voltage component is used to control or regulate the power absorbed by the brake actuator. The AC voltage component is used to balance the energy budget, ensuring stable operation of the modular brake actuator.

[0026] The proposed design draws a pure direct current from the modular brake actuator. In other words, the current drawn by the modular brake actuator is free of harmonics, particularly at the frequencies of the AC voltage components generated by the submodule group. This reduces or eliminates feedback effects on other components of the drive or power system caused by the operation of the brake actuator. For example, this design and / or operating method reliably prevents unwanted fluctuations in drive torque or unwanted energy oscillations in the power grid, regardless of the operating point.

[0027] For this purpose, it is particularly advantageous that the modular brake actuator includes a control device configured to generate a first AC voltage component through submodules of the first submodule group and a second AC voltage component through submodules of the second submodule group, wherein the first AC voltage component and the second AC voltage component are out of phase with each other. Furthermore, it is advantageous that the control device is further configured to perform an operating method according to one of these advantageous embodiments of the operating method of the invention.

[0028] A specific advantage of the proposed design is that there is no current path parallel to the braking resistor in the modular brake actuator. This ensures that the entire current drawn by the brake actuator (which is a direct current) flows through the braking resistor and results in a corresponding conversion of electrical energy into heat.

[0029] In a preferred embodiment of the invention, the first submodule group and the second submodule group each include a plurality of submodules, wherein the submodules are arranged in series. It has been shown that it is also possible to arrange multiple submodules within each submodule group. In this case, not only does a single submodule generate a corresponding voltage with DC and AC voltage components across the respective submodule group, but multiple submodules also generate corresponding voltages with DC and AC voltage components across the respective submodule group. "Multiple submodules" refers to at least two submodules connected in series. Due to the series circuit, the voltages of the individual submodules are added together. These submodules do not necessarily carry the same current. For example, if only a portion of the submodules is connected in parallel to a second series circuit consisting of a capacitor and an additional braking resistor, or if the submodule group includes multiple such second series circuits, they can carry different currents.

[0030] The use of multiple submodules allows the modular brake actuator to be adapted to any voltage level. This makes the use of such a modular brake actuator particularly advantageous for applications in medium and / or high voltage systems. Furthermore, the use of multiple submodules allows for the increase of not only the operating voltage but also the power of the modular brake actuator as needed.

[0031] Because these submodule groups are designed to suppress AC current at the connection of the modular brake actuator by preferably generating the same DC voltage value and the same AC voltage amplitude, it has proven advantageous that the number of submodules in the first submodule group is equal to the number of submodules in the second submodule group. In other words, the first submodule group has the same number of submodules as the second submodule group. This allows for and ensures good and high utilization of the submodules in the respective submodule groups. Because the first and second submodule groups have the same number of submodules, it is easy to generate the same DC and AC voltages that are 180° phase-shifted relative to each other.

[0032] The number of submodules in the brake actuator depends on the operating voltage of the modular brake actuator, which corresponds to the DC link voltage of the power converter to which the modular brake actuator is connected on the DC voltage side. In general, only as many submodules as are needed to provide the total DC link voltage. This number of submodules can then be distributed across two submodule groups as needed. As mentioned above, the uniform distribution of submodules across the two submodule groups is advantageous in terms of submodule usage while preventing the formation of alternating current at the connections of the modular brake actuator. Therefore, the distribution of submodules across the two submodule assemblies does not require more submodules than that of brake actuators constructed from submodules known in the prior art.

[0033] In a further advantageous embodiment of the invention, the second series circuit is arranged in electrical parallel with a portion of the submodules of the respective submodule group. For low values ​​of the additional braking resistor, particularly those smaller than the resistance value of the braking resistor, only a lower amplitude is required for the AC voltage component, which can also be generated using a relatively small number of submodules. Therefore, it is not necessary to arrange all the submodules of the submodule group in parallel with the second series circuit. This reduces the load caused by the DC voltage component, particularly the load on the capacitor of the second series circuit, which drops across the capacitor and must be rated according to this load. Since only a portion of the submodules in each submodule group are connected in parallel with the second series circuit, the requirements for the capacitor are reduced without compromising control performance. Therefore, modular brake actuators can be implemented more cost-effectively.

[0034] Specifically, if the second series circuit is arranged in parallel with at least two of the multiple sub-modules, only a few additional braking resistors are required. If all the sub-modules in a sub-module group are arranged in parallel with the second series circuit, only one additional braking resistor is required for each sub-module group; that is, two additional braking resistors in total for a modular brake actuator. These additional braking resistors (especially when the modular brake actuator comprises only two additional braking resistors) can be arranged adjacent to the original braking resistor. This location can be designed to withstand the high temperatures generated near the original braking resistor and the additional braking resistors during operation of the modular brake actuator. Alternatively or additionally, the same cooling system, such as a shared cooling loop, can be provided for the original braking resistor and the additional braking resistors. This allows power losses to be dissipated to the coolant in a particularly efficient manner. The cooling loop can therefore be designed to be compact. This also results in a compact design and economical operation of the modular brake actuator.

[0035] In another advantageous embodiment of the invention, the second series circuit is arranged in electrical parallel with all the submodules of the corresponding submodule group. This arrangement allows all the submodules to contribute to the generation of the AC voltage component. Therefore, all the submodules are also able to transfer electrical energy to the additional braking resistor. This enables each submodule to transfer the energy it absorbs to the additional braking resistor, regardless of the operating point of the modular brake actuator. This ensures the stability of all the submodules within the modular brake actuator in a simple manner.

[0036] In another advantageous embodiment of the invention, the submodule group each includes a plurality of second series circuits, wherein each second series circuit is arranged in parallel with at least one of the submodules. Due to this arrangement, the second series circuits place significantly lower requirements on the capacitors (particularly regarding the dielectric strength of the capacitors) and on the additional braking resistors. Due to adaptability to any voltage level in the intermediate circuits, if all the submodules of a submodule group were arranged in parallel with the second series circuits, there would be an increased requirement for dielectric strength (particularly for the dielectric strength of the capacitors). As the voltage increases, the demand on the capacitors increases disproportionately. To meet these requirements directly, the submodule groups or individual submodules within each submodule group are configured to be arranged in parallel with the second series circuits. Furthermore, this allows the current flowing through these individual second series circuits to be controlled or regulated independently of each other. This improves redundancy performance in the event of failure of one or more submodules or capacitors in one of these second series circuits. This increases availability. Because modular brake actuators typically perform safety-critical tasks during deceleration of the drive system, the increased redundancy significantly improves the safety of the entire drive, thereby meeting reliability requirements.

[0037] In another advantageous embodiment of the invention, each submodule is arranged in parallel with one of these second series circuits. This embodiment allows the second series circuits to be integrated into the submodule. Therefore, since heat is distributed across multiple submodules, each individual resistor in the additional braking resistor generates very little heat. Due to the low heat generation, the additional braking resistor can be connected to the cooling system of the submodule. Thus, the additional resistor primarily contributes to the conversion of electrical energy into heat.

[0038] Furthermore, in the event of a failure, the entire submodule, including the second series circuit arranged in parallel, can be easily replaced. This minimizes maintenance time, thereby ensuring efficient operation of the drive.

[0039] Furthermore, by connecting the additional braking resistor to the capacitor of the submodule, the second series circuit consists of the capacitor and the additional braking resistor, enabling the submodule capacitor to be used in the second series circuit. Then, depending on the function of the submodule capacitor, the capacitor serves both as an energy storage device for the submodule and as a component to prevent the formation of DC current through the additional braking resistor.

[0040] In another advantageous embodiment of the invention, at least one submodule in the corresponding submodule group is configured as a full-bridge module. Configuring at least one submodule as a full-bridge module increases the control range of the brake actuator. Therefore, it is possible, at least for a short period, to apply a voltage higher than the DC link voltage of the power converter to the braking resistor. This allows the modular brake actuator to handle at least temporary overloads, during which power exceeding the rated or design power of the modular brake actuator can be converted into heat. Furthermore, the modular brake actuator is easier to control and regulate under its capacity limitations (especially at maximum power) because control reserves are available even when the submodule generates zero voltage across the submodule group (i.e., the DC link voltage is applied across the braking resistor). Among other things, this results in improved dynamic behavior of the modular brake actuator.

[0041] In a further advantageous embodiment of the invention, at least some of the submodules are configured as unipolar submodules, particularly half-bridge or dual half-bridge modules. The parallel arrangement of the second series circuit allows energy introduced into the submodule via DC current to be easily dissipated without requiring a reversal of voltage polarity at the submodule. For example, such polarity reversal can be achieved using bipolar submodules. However, bipolar submodules are more expensive than unipolar submodules due to the higher number of semiconductors. However, the second series circuit eliminates the need to change the voltage polarity at the submodule. Therefore, these submodules can be designed as unipolar submodules, such as half-bridge or dual half-bridge modules, particularly when these components form part of a parallel connection with a second series circuit, which includes a capacitor and an additional braking resistor.

[0042] In another advantageous embodiment of the invention, the multilevel power converter is connected to the motor on the AC voltage side, wherein the control device is configured to convert at least partially of the electrical energy generated during the braking process of the motor into heat via the modular brake actuator. The motor generates electrical energy during braking. If the grid-side power converter is not designed to feed the electrical energy back into the grid, or if the grid cannot accommodate the electrical energy, the modular brake actuator can be used to convert the electrical energy into heat without causing wear. This ensures safe operation of the modular drive unit, particularly independent of the operating state of the grid. Furthermore, since the proposed modular brake actuator ensures a sufficiently fast response, the motor can operate in a highly dynamic manner (i.e., with rapid load changes).

[0043] In another advantageous embodiment of the invention, the multilevel power converter is connected to the power grid on the AC voltage side, wherein the control device is configured to convert electrical energy into heat to particularly improve the stability of the power grid. This makes the multilevel power converter particularly suitable for power transmission and distribution applications. For example, such a multilevel power converter can be used to connect remote energy sources (e.g., offshore wind farms) to feed points on land. If the power grid at the feed point is temporarily unable to accommodate the load, a braking actuator can be used to convert electrical energy into heat. This prevents the wind farm from having to shut down and undergo time-consuming restarts, for example, in the event of a short-term failure that results in limited grid capacity. This increases the stability of both the power grid and the energy-generating wind farm.

[0044] When two power grids are interconnected, a braking actuator can also be used to balance the unbalanced power flow between the power grids, and thus contribute to the stable operation of both power grids.

[0045] In another advantageous embodiment of the invention, the frequency and / or amplitude of the AC voltage component depends on the voltage of the submodule. The voltage across each submodule results in the voltage applied to the submodules across each submodule group. In other words, it is particularly advantageous that the frequency and / or amplitude of the AC voltage component depends on the voltage across the submodules of the respective submodule group. The voltage of the submodule, generated based on the voltage of the submodule capacitor, allows for the detection of unbalanced energy. If the submodules consume an average amount of electrical energy (which can be observed as an increase in the voltage across the capacitor), the increase in the amplitude and / or frequency of the AC voltage component offsets this increase. For example, using a PI controller, the amplitude and / or frequency of the AC voltage component can be set or changed according to the submodule voltage.

[0046] In another advantageous embodiment of the invention, the amplitude of each AC voltage component is smaller than that of the DC voltage component generated by one of the submodules in the submodule group. If the amplitude of the AC voltage component is smaller than that of the DC voltage, only a single-pole submodule is needed to generate the voltage because the polarity of the voltage is not reversed. Due to the parallel current path of the second series circuit, balanced energy can be achieved for all operating points, even when using a single-pole submodule. If more control reserve is needed when the amplitude corresponds to the DC voltage component, this can be achieved by increasing the frequency. In particular, in the high power range of the brake actuator, only a small amount of power needs to be consumed through an additional braking resistor due to the low voltage drop across the submodule. This is also possible at low amplitudes, potentially supported by an increase in the frequency of the AC voltage components. Attached Figure Description

[0047] The invention will now be described and explained in more detail with reference to the exemplary embodiments shown in the accompanying drawings. It illustrates: Figure 1 , Figure 2 This illustrates an implementation of a modular brake actuator. Figures 3 to 6 An exemplary implementation of the submodule is shown. Figure 7 The voltage and current waveforms are shown. Figures 8 to 10 Several exemplary implementations of the modular drive unit are shown. Detailed Implementation

[0048] Figure 1 An embodiment of a modular brake actuator 1 is shown. This modular brake actuator 1 includes a first series circuit 14 between its two terminals 13. This first series circuit includes a first submodule group 21, a second submodule group 22, and a braking resistor 3, wherein the braking resistor is disposed between the first submodule group 21 and the second submodule group 22, i.e., at the center of the first series circuit 14. The modular brake actuator 1 is configured to be connected at its terminals 13 to a DC link 9 of a power converter, particularly a modular multilevel power converter 11.

[0049] Submodule groups 21 and 22 each include at least one submodule 2. If there is more than one submodule 2, then there are multiple submodules 2. The term "multiple submodules 2" means at least two submodules 2. These submodules 2, or a portion thereof, are connected in series, for example, to increase the operating voltage of the modular brake actuator 1. A second series circuit 15, including a capacitor 7 and an additional braking resistor 31, is arranged in parallel with at least one submodule 2, connected in series with a submodule 2, or connected in series with a portion of a submodule 2. The capacitor 7 prevents the formation of a direct current through the additional braking resistor 31. By means of the voltage u generated via the submodule 2 SM1 u SM2 A voltage can be generated across the braking resistor 3. Since the active power is absorbed by the modular brake actuator 1 via DC current, u SM1 =U SM,DC,1 and u SM2 =U SM,DC,2 The DC voltage is generated via the corresponding submodule group. Therefore, u R =U R The DC voltage is also applied to the braking resistor, which causes a DC current i DC Through braking resistor 3. Except for U. SM,DC,1 and U SM,DC,2 In addition to the DC component, the AC component is also superimposed on the voltage u. SM1 u SM2 Above. This AC voltage component causes an AC current i through another braking resistor 31. R2 Therefore, the DC current i DC Open-loop or closed-loop control of power consumption for modular brake actuator 1, and through the AC current i of the second series circuit 15. R2 This is used to generate energy balance within the modular brake actuator 1, thereby preventing energy input or output within the time device in submodule 2. If the energy stored in the time device within submodule 2 remains the same, the modular brake actuator 1 can operate permanently at the corresponding operating point. The AC voltage components of the two submodule groups 21 and 22 are oriented to be opposite in phase, preventing the formation of AC current through the braking resistor 3. Therefore, under a constant DC link voltage U... D Under these conditions, there is no AC voltage drop across the braking resistor 3, which could result in AC current. Therefore, no AC current appears externally, i.e., at terminal 13 of the modular brake actuator 1. Consequently, the modular brake actuator 1 can operate on the power converter with particularly low feedback effect because it does not generate harmonics.

[0050] Figure 2An alternative implementation of the modular brake actuator 1 is shown. In this case, each sub-module 2 has a second series circuit 15 arranged in parallel, which includes a capacitor 7 and another braking resistor 31. Furthermore, according to... Figure 1 and Figure 2 Any combination of exemplary implementations is also possible, wherein only a portion of submodule 2 is arranged in parallel with the second series circuit 15, and another portion of submodule 2 is arranged in parallel with another second series circuit 15.

[0051] Figures 3 to 6 An exemplary implementation of submodule 2 is shown. All known submodule 2, particularly... Figures 3 to 6 The submodule 2 shown is suitable for the modular brake actuator 1. To avoid repetition, refer to... Figures 1 to 2 The relevant description and the accompanying reference numerals.

[0052] An exemplary implementation of submodule 2 includes at least two semiconductor switches 24. By switching the semiconductor switches 24, an output voltage U can be generated at the terminals of submodule 2. sub In this process, the drive module 16 sends control signals to the semiconductor switch 24 of the submodule 2. The drive module 16 is preferably located outside the submodule 2 and is therefore not part of the submodule 2. Alternatively, each submodule 2 can be equipped with its own drive module 16. However, it has proven advantageous to use a single drive module 16 to control all submodules 2 of the modular brake actuator 1. Furthermore, the drive module 16 can then perform the calculations necessary for controlling and regulating voltage and current. In particular, the drive module 16 can also be part of a control device for generating the DC and AC components of the voltage across submodule groups 21 and 22.

[0053] Figure 3 A half-bridge module is shown. This includes two semiconductor switches 24 and a submodule capacitor 25. Voltage U C，sub It is applied to the submodule capacitor 25. Through the switching operation of the semiconductor switch 24, a 0 or U value can be generated at the terminals of the submodule 2. C，sub Output voltage U sub The drive module 16 controls the semiconductor switch 24 to create a desired voltage between the submodule terminals 26. Because the polarity of the output voltage does not change, this submodule 2 is also called a unipolar submodule.

[0054] Figure 4An exemplary implementation of the half-bridge module is shown. If the second series circuit 15 is only electrically connected in parallel with the submodule 2, the submodule capacitor 25 is not required. In this case, the capacitor 7 of the second series circuit 15 can perform the function of energy storage in the submodule 2, a function additionally performed by the submodule capacitor 25. This extension is also possible for the submodule 2 described below by replacing the submodule capacitor 25 with the second series circuit 15, which consists of the capacitor 7 and an additional braking resistor 31.

[0055] The drive module 16 controls the semiconductor switch 24 to create a desired voltage at the submodule terminals 26. Since the polarity of the output voltage does not change in this exemplary embodiment, such a submodule 2 is also referred to as a unipolar submodule.

[0056] Figure 5 A so-called dual half-bridge module is shown. This dual half-bridge module has four semiconductor switches 24 and two sub-module capacitors 25. A voltage U exists at each of the sub-module capacitors 25. C1，sub and U C2，sub Through the switching operation of these semiconductor switches, an output voltage U of 0 can be generated at submodule terminal 26 of submodule 2. sub Capacitor voltage U C1，sub U C2，sub One of the capacitor voltages U C1，sub U C2，sub The sum of these. The drive module 16 (not shown here) is able to control these semiconductor switches 24 so that a desired voltage exists between the terminals 26 of these submodules. Submodule 2 is also a unipolar submodule.

[0057] Figure 6 This is shown as a so-called full-bridge module. The full-bridge module contains four semiconductor switches and a submodule capacitor 25. Voltage U C，sub It is applied to the submodule capacitor 25. By switching the semiconductor switch 24, the output voltage U can be... sub The capacitor voltage ±U of the submodule capacitor at submodule terminal 26 of submodule 2 is set. C，sub The values ​​can be zero, positive, or negative. The drive module 16 (not shown) controls these semiconductor switches 24 to create a desired voltage between the terminals 26 of these submodules. Because this submodule 2 can generate voltages of different polarities, this type of submodule 2 is also called a bipolar submodule.

[0058] Figure 7 The DC link voltage U generated by submodule groups 21 and 22 is shown. D The waveform of the relevant voltage u. The two submodules 21 and 22 together generate voltage U. SM，DC，1 / 2The voltage is preferably equally divided among the respective submodule groups 21, 22, such that each of the submodule groups 21, 22 has an equal share:

[0059] In this method, an AC voltage component is superimposed on two DC voltage components, wherein the AC voltage components are out of phase with each other (i.e., have a 180° phase shift), so that they do not cause a voltage drop across the braking resistor 3. These alternating components can have any time waveform, such as sine, rectangular, triangular, trapezoidal, etc. Figure 7 It shows that there is û SM，AC The corresponding amplitude of the sinusoidal waveform.

[0060] Figure 8 A modular drive unit 10 is shown, comprising a modular multilevel power converter 11 and a modular brake actuator 1. These are interconnected via a DC link 9, with a DC link voltage U. D It is applied to this DC link. In other words, the modular multilevel power converter 11 is connected to terminal 13 of the modular brake actuator 1 on the DC voltage side. To avoid repetition, refer to... Figures 1 to 6 The relevant description and the reference numerals introduced therein. The modular brake actuator 1 includes a first series circuit 14 of a first submodule group 21, a second submodule group 22, and a braking resistor 3. These submodule groups 21, 22 each have at least one submodule 2 and a second series circuit 15, which includes a capacitor 7 and another braking resistor 31, which are not explicitly shown for clarity. See [link to relevant documentation] for details. Figure 1 and Figure 2 This is an example of an embodiment. In this context, the modular multilevel power converter 11 can (though not necessarily) include submodules 2 identical to the submodule groups 21, 22 of the modular brake actuator 1. Furthermore, the series circuit of these submodules of the modular multilevel power converter 11 preferably also includes an inductor 8, which improves the control behavior of the modular multilevel power converter 11. Terminals L1, L2, L3 represent the AC side terminals of the modular multilevel power converter 11, or simply the AC voltage side. In this exemplary embodiment, the modular multilevel power converter 11 is configured as three-phase. Alternatively, a single-phase embodiment with a neutral conductor or any number of phases is also possible by arranging an appropriate number of phase modules in the modular multilevel power converter 11.

[0061] Figure 9 Another exemplary embodiment of the modular drive unit 10 is shown. The AC voltage side of the modular multilevel power converter 11 is connected to the power grid 6. Alternatively, it can be connected to any energy source or energy storage system.

[0062] exist Figure 10 In an exemplary embodiment, the modular drive unit 10 includes two modular multilevel power converters 11 and a modular brake actuator 1, which are electrically connected to each other at a DC link 9. The first of the two modular multilevel power converters 11 is connected to the motor 5 on its AC voltage side. The second of the two modular multilevel power converters 11 (i.e., another modular multilevel power converter 11) is connected to the power grid 6 on its AC voltage side. The motor 5 can be supplied with electrical energy, i.e., powered by the power grid 6. For example, during braking, energy from the motor 5 can also be fed back to the power grid 6 using the modular drive unit 10. If the power grid 6 cannot absorb energy temporarily or permanently, the electrical energy generated by the motor 5 can be converted into heat in a wear-free manner using the modular brake actuator 1. In this configuration, a wear-resistant mechanical brake can be omitted.

[0063] List of reference numerals

[0064] 1 Modular brake actuator

[0065] 2 Submodules

[0066] 3 Braking Resistor

[0067] 5 motors

[0068] 6. Power Grid

[0069] 7. Capacitors

[0070] 8 Inductors

[0071] 9 DC Link

[0072] 10 Modular drive units

[0073] 11 Multi-stage converter

[0074] 13 Brake actuator terminal (1)

[0075] 14 First Series Circuit

[0076] 15 Second Series Circuit

[0077] 16 Driver Modules

[0078] 21 First Submodule Group

[0079] 22 Second Submodule Group

[0080] 24 Semiconductor Switches

[0081] 25 Submodule Capacitors

[0082] 26 Sub-module terminals

[0083] 31. Additional braking resistor.

Claims

1. A modular brake actuator (1), wherein, A first submodule group (21), a second submodule group (22), and a braking resistor (3) are arranged in a first series circuit (14) between two terminals (13) of the modular brake actuator (1), wherein the braking resistor (3) is electrically arranged between the first submodule group (21) and the second submodule group (22), wherein the first submodule group (21) and the second submodule group (22) respectively include at least one submodule (2), another braking resistor (31) and a capacitor (7), wherein a second series circuit (15) including the other braking resistor (31) and the capacitor (7) is arranged to be electrically connected in parallel with at least one submodule (2) of the at least one submodule (2).

2. The modular brake actuator (1) according to claim 1, wherein, The first submodule group (21) and the second submodule group (22) each include multiple submodules (2), and the submodules (2) are connected in series.

3. The modular brake actuator (1) according to claim 2, wherein, The second series circuit (15) is electrically connected in parallel with a portion of the sub-module (2) of the corresponding sub-module group (21, 22), particularly with at least two of the multiple sub-modules (2).

4. The modular brake actuator (1) according to claim 2, wherein, The second series circuit (15) is electrically connected in parallel to all sub-modules (2) of the corresponding sub-module group (21, 22).

5. The modular brake actuator (1) according to any one of claims 2 to 4, wherein, Submodule groups (21, 22) each include a plurality of second series circuits (15), wherein the second series circuits (15) are arranged in parallel with at least one of the submodules (2).

6. The modular brake actuator (1) according to claim 5, wherein, Each submodule (2) is arranged in parallel with one of the second series circuits (12).

7. The modular brake actuator (1) according to any one of claims 1 to 6, wherein, At least one submodule (2) in the corresponding submodule group (21, 22) is configured as a full-bridge module.

8. The modular brake actuator (1) according to any one of claims 2 to 7, wherein, At least some of the submodules in the submodule (2) are configured as unipolar submodules, particularly half-bridge modules or dual half-bridge modules.

9. A modular drive unit (10) comprising a modular multilevel power converter (11) and a modular brake actuator (1) according to any one of claims 1 to 8, wherein, The multilevel power converter (11) is connected to the modular brake actuator (1) on the DC voltage side.

10. The modular drive unit (10) according to claim 9, wherein, The multilevel power converter (11) is connected to the motor (5) on the AC side, and wherein the control device (4) is configured to convert at least part of the electrical energy from the braking process of the motor (5) into heat via the modular brake actuator (1).

11. The modular drive unit (10) according to any one of claims 9 or 10, wherein, The multilevel power converter (11) or another multilevel power converter is connected to the power grid (6) on the AC side, wherein the control device (4) is configured to convert electrical energy into heat in order to improve the stability of the power grid (6) in particular.

12. A method of operation for a modular brake actuator (1) according to any one of claims 1 to 8 or for a modular drive unit (10) according to any one of claims 9 to 11, wherein, A first alternating voltage component (u BR,AC,1 ) is generated by the submodules (2) of the first submodule group (21), and a second alternating voltage component (u BR,AC,2 ) is generated by the submodules (2) of the second submodule group (22), wherein the first alternating voltage component (u BR,AC,1 ) and the second alternating voltage component (u BR,AC,2 ) are opposite to each other in phase.

13. The operating method according to claim 12, wherein, AC voltage component (u BR,AC,1 u BR,AC,2 The frequency (f) and / or amplitude (û) of the submodule (2) depend on the voltage of the submodule (2), and in particular on the voltage applied by the submodule (2) across the corresponding submodule group (21, 22).

14. The operating method according to any one of claims 12 or 13, wherein, AC voltage component (u BR,AC,1 u BR,AC,2 The amplitude (û) of each AC voltage component in the submodule group (21, 22) is smaller than the DC voltage component (u) generated by submodule (2) of one of the submodule groups (21, 22). BR,DC,1 u BR,DC,2 ).

15. The operating method according to any one of claims 12 to 14, wherein, AC voltage component (u BR,AC,1 u BR,AC,2 The frequency (f) and / or amplitude (û) of the brake actuator (1) are selected such that the electrical energy absorbed by the modular brake actuator (1) is completely converted into heat by the brake resistor (3) and the other brake resistor (31).

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