Modular brake actuator with hybrid design
Patent Information
- Application Number
- EP2023739162
- Authority / Receiving Office
- EP · EP
- Patent Type
- Applications
- Current Assignee / Owner
- Priority Date
- 2022-08-22
- Filing Date
- 2023-07-03
- Publication Date
- 2025-03-19
AI Technical Summary
Existing modular brake dividers lack the capability to efficiently convert energy into heat with high performance and flexibility across varying voltage levels and operating points, limiting their effectiveness in electric drive systems.
A modular brake divider with a hybrid design featuring a series connection of at least one full-bridge module and one double half-bridge module, allowing for the generation of both positive and negative voltages, with a control device regulating the alternating voltage component to exceed the direct voltage component, thereby enhancing energy conversion into heat.
This design achieves higher performance and adaptability by increasing the voltage range and current through the braking resistor, enabling efficient energy conversion into heat across a wide range of operating conditions, while maintaining stability and reducing wear in electric drive systems.
Smart Images
Figure 1.1
Abstract
Description
[0001] Description
[0002] Modular brake controller with hybrid design
[0003] The invention relates to a modular brake controller comprising a braking resistor and at least two submodules, wherein the braking resistor and the submodules are arranged in a series circuit. Furthermore, the invention relates to an electric drive comprising such a modular brake controller and a power converter, wherein the power converter is electrically connected to the modular brake controller on the DC voltage side. The invention further relates to a method for operating such a modular brake controller or such an electric drive.
[0004] A modular multilevel power converter is available from the
[0005] DE 10 103 031 A1 . This power converter, also known as M2C or MMC, has a converter topology which, due to its design with submodules, is particularly suitable for medium and high voltage applications. The basic design of the multi-phase converter comprises two converter arms per phase, each with a series connection of submodules. The two converter arms are connected to one another at the phase connection. The other side of the converter arms is connected to the DC side. The AC side of the modular multilevel power converter is formed by one or more phase connections. In the basic design, the converter can be used to transfer energy bidirectionally between the DC side and the AC side, or to temporarily store it to a certain extent.
[0006] To additionally enable targeted energy dissipation, the installation of a braking controller is advisable. A modular braking controller is known from WO 2007 / 023061 A2. The modular braking controller is typically connected to the DC side of the modular multilevel converter, for example, between a DC+ and a DC- connection.
[0007] The resistance of a brake actuator arrangement is often also referred to as a braking resistor, as it is suitable for converting electrical energy from an electrical machine, which is generated as a result of a braking process, into heat. The use of a braking actuator is not restricted to the application of a braking electric drive. It does not necessarily have to be braking energy that is converted into heat. The braking controller can, for example, also be used to stabilize a power supply network by converting electrical energy from the power supply network into heat. The term braking resistor was chosen in order to distinguish the resistor in which a given electrical energy or power is converted into heat or heat per unit of time from other resistors.
[0008] The term "power to be converted into heat" refers to the integral of the power over time being converted into heat. In other words, the amount of energy resulting from the power over time is converted into heat.
[0009] The invention is based on the object of improving a modular brake controller.
[0010] This object is achieved by a modular brake controller, wherein the modular brake controller has a braking resistor and at least two submodules, wherein the braking resistor and the submodules are arranged in a series circuit, wherein at least one submodule is designed as a full-bridge module and at least one submodule is designed as a double half-bridge module, wherein the modular brake controller has a control device which is designed to generate a voltage across the submodules arranged in series, wherein the voltage comprises a DC voltage component and an AC voltage component, wherein the control device is further designed to control or regulate the AC voltage component, in particular with regard to its amplitude, in such a way that the energy absorbed on average by the modular brake controller is converted into heat in the braking resistor,wherein at least temporarily the amplitude of the AC voltage component is greater than the DC voltage component. This object is further achieved by an electric drive, wherein the electric drive has such a modular brake controller and a power converter, wherein the power converter is electrically connected to the modular brake controller on the DC voltage side. This object is further achieved by a method for operating such a modular brake controller or such an electric drive, wherein the submodules generate a voltage across the series-arranged submodules, which at least temporarily comprise a negative and a positive voltage range, wherein the voltage comprises a DC voltage component and an AC voltage component, wherein the AC voltage component is controlled or regulated in such a way that the energy absorbed on average by the modular brake controller is converted into heat in the braking resistor,where at least temporarily the amplitude of the alternating voltage component is greater than the direct voltage component.,
[0011] Further advantageous embodiments of the invention are specified in the dependent claims.
[0012] The invention is based, among other things, on the finding that the combination of at least one full-bridge module and one double half-bridge module makes it possible to apply a negative voltage across the series connection of submodules. This negative voltage is directed such that the voltage applied to the braking resistor is greater than the intermediate circuit voltage applied to the terminals of the modular braking controller. By increasing the voltage across the braking resistor, more power can be converted into heat by the modular braking controller. The heat corresponds to the power integrated over time.
[0013] The braking resistor can be arranged anywhere in the series circuit. For example, the braking resistor can be arranged between one of the terminals of the modular braking controller and a submodule, or anywhere between two submodules. The braking resistor can also be the sum of several partial resistors arranged in series. The partial resistors, which can be arranged at different positions in the series circuit, act together like a braking resistor in the series circuit.
[0014] The number of submodules allows the modular brake controller to be adapted to the intermediate circuit voltage of a power converter in such a way that it can be connected to any power converter, especially a modular multilevel power converter. For scaling to higher voltages and for operation at different operating points, any number of full-bridge modules, half-bridge modules, and resistors can be arranged or connected in series in any order.
[0015] With the help of the semiconductor switches arranged in the submodules, different voltages can be generated at the connections of the respective submodules. With a full-bridge module, voltages with different signs can also be generated. With the double half-bridge module, four defined switching states can be generated during active operation: zero voltage, the first capacitor voltage, the second capacitor voltage or the sum of the first and second capacitor voltages. Four switching states can also be achieved with the full-bridge module, two of which result in zero voltage at the connections of the switching module. In addition, the positive and negative capacitor voltages can be generated at the connections of the submodule. The switching states mentioned for the double half-bridge module and the full-bridge module are independent of the direction of current flow through the corresponding submodule.IGBT modules with antiparallel diodes are often used as semiconductor switches for medium and high voltage applications due to their blocking capability.
[0016] From the consideration of the switching states it can be seen that by using a double half-bridge module the voltage range of the modular braking controller can be extended by approximately twice the value compared to the full-bridge module, since in one of the switching states of the double half-bridge module the voltages on the two capacitors add up to an output voltage.
[0017] The current through the braking resistor is controlled or regulated with the help of the voltage across the series connection of the submodules. The current has a DC component and an AC component. The AC component has a periodic characteristic and an average value of zero. The DC component is used to control or regulate the power to be converted into heat by the modular braking controller, while the AC component is used to maintain the energy balance in the submodules and thus to stabilize the operation of the modular braking controller. The level of the AC component of the voltage across the series connection of the submodules and the current through the modular braking controller depends, among other things, on the resistance value of the braking resistor. By using full-bridge modules, a negative voltage can also be generated across the series connection of the submodules. This also enables operation in which the amplitude of the AC component exceeds the DC component.This increases the power range of the modular braking unit for a given resistance. The more full-bridge modules used, the greater the negative voltage generated across the series connection of the submodules.
[0018] A hybrid design of the modular braking unit has proven particularly advantageous. The number of full-bridge modules depends on the negative voltage required across the series connection of the sub-modules to generate a correspondingly high current through the modular braking unit. At the same time, the use of double-bridge modules results in a high operating voltage for the modular braking unit. Both types of sub-modules, i.e. the full-bridge module and the double-half-bridge module, take up almost the same amount of space due to the same number of semiconductors and the associated control circuitry. This means that a mechanical framework for accommodating sub-modules of a modular braking unit can be easily filled with double-half-bridge modules and full-bridge modules.The corresponding mounting locations for the sub-modules can be designed identically and are therefore suitable for accommodating both a double half-bridge module and a full-bridge module. This makes it particularly advantageous to have a modular, and therefore simple and cost-effective, design for a modular brake controller with high performance and a high operating voltage. Likewise, the same control circuit can be used to control a double half-bridge module and a full-bridge module, as both types of module have the same number of semiconductor switches (4 semiconductor switches). The hybrid design of the modular brake controller is therefore particularly simple and cost-effective to manufacture and covers a wide range of performance and operating voltage.
[0019] The modular brake controller is usually advantageously operated in combination with a power converter. The modular brake controller is part of a drive system in which non-regenerable energy, for example, from an electrical machine, is converted into heat during braking. Unlike braking with a mechanical brake, this process is wear-free.
[0020] In the method according to the invention, wherein the submodules generate a voltage across the series-arranged submodules, which at least temporarily comprise a negative and a positive voltage range, a negative voltage is generated at least temporarily by the submodules across the series-arranged submodules. This occurs in order to generate a current through the modular braking resistor that is greater than a current that could be generated if the intermediate circuit voltage of the electric drive or the operating voltage of the modular braking resistor were applied across the braking resistor.
[0021] In an advantageous embodiment of the invention, at least one of the submodules, in particular all submodules, each has a bypass switch which is designed to short-circuit the connections of the respective submodule. In order to be able to remain in operation even if a submodule fails, it has proven advantageous to create redundancy. Not all submodules contribute to generating the intermediate circuit voltage across the series connection of the submodules. If a submodule fails, the corresponding submodule can then be bridged by means of the bypass switch and thus does not disrupt the operation of the modular braking unit.
[0022] In a further advantageous embodiment of the invention, the power converter is designed as a modular multilevel power converter. It is particularly advantageous to combine the modular brake controller with the modular multilevel power converter, also known as an M2C power converter, to form an electric drive. Identical submodules can be used for the modular multilevel power converter and for the modular brake controller. The modular multilevel power converter can be constructed from double half-bridge modules, full-bridge modules or a combination of these two submodule types. The same hardware can also be used to control the submodules. Due to the modular design of both the power converter and the modular brake controller, the electric drive can be easily adapted to a required power requirement by selecting an appropriate number of submodules in the power converter and the modular brake controller.The identical design of the submodules in the modular brake controller and multilevel power converter allows for a high proportion of identical parts. This has a positive effect on the reliability and manufacturing costs of such a drive unit.
[0023] The modular brake controller can be connected to the DC side of converters of any design and is not limited to use with a modular multilevel converter.
[0024] The invention is described and explained in more detail below with reference to the exemplary embodiments shown in the figures. They show:
[0025] FIG 1 and FIG 2 Examples of the modular brake actuator,
[0026] FIG 3 a submodule as a full bridge module,
[0027] FIG 4 a submodule as a double half-bridge module,
[0028] FIG 5 and FIG 6 Examples of proposed electric drives,
[0029] FIG 7 Time courses of electrical quantities and
[0030] FIG 8 Working areas of the modular brake actuator.
[0031] FIG. 1 shows a modular brake controller 1. This has a series connection 4 of at least two submodules 2 and a braking resistor 3. The series connection 4 also includes a series connection of the submodules 2. In the case of the submodules 2, at least one submodule 2 is designed as a full-bridge module 21 and one submodule 2 as a double half-bridge module 22. The modular brake controller can also have a plurality of submodules 2, as shown in FIG. 2. The submodules 2 can be full-bridge modules 21 and double half-bridge modules 22. However, the use of all other previously known submodules 2 is also possible. The modular brake controller 1 is designed to be connected at its terminals 11 to an intermediate circuit 9 of a power converter 5, 51.
[0032] A voltage U B R. With the voltage U B R can be a current iBR by the modular brake resistor 1. The current through the braking resistor 3 causes the conversion of electrical energy into heat. The operating voltage U is across the modular brake resistor 1. D If the modular brake controller 1 is connected to the intermediate circuit of a power converter, the intermediate circuit voltage is applied to the modular brake controller. In this case, the modular brake controller 1 is said to be connected to the DC side of the power converter.
[0033] Figures 3 and 4 show exemplary embodiments of submodules 2. Figure 3 shows a full-bridge module 21, and Figure 4 shows a double half-bridge module. These are part of the proposed design. Furthermore, the modular brake controller 1 can be expanded with previously known submodules 2. To avoid repetition, reference is made to the description of Figures 1 and 2 and to the reference symbols used there.
[0034] The illustrated embodiments of the submodules 2, 21, 22 comprise four semiconductor switches and at least one capacitor. By switching operations of the semiconductor switches, an output voltage U SU b are generated at the terminals of submodule 2. A control circuit transmits the control signals to the semiconductor switches of submodule 2.
[0035] To bridge the corresponding submodule 2, a bypass switch 6 can optionally be provided in the submodule 2.
[0036] FIG 3 shows a so-called full-bridge module. This has four semiconductor switches and a capacitor. The voltage U is applied to the capacitor. c , SU b . By switching operations of the semiconductor switches, the output voltage U SU b of zero, the positive or the negative capacitor voltage ±U C , sub are generated at the terminals 11 of the submodule 2 .
[0037] Figure 4 shows a so-called double bridge module. This has four semiconductor switches and two capacitors. The voltage U is applied to each capacitor. Ci , S U b or U C 2 , sub an . By switching operations of the semiconductor switches, the output voltage U SU b of zero , one of the capacitor voltages U ci , sub z U C 2 , sub or the sum of the capacitor voltages Uci , sub , U C 2 , sub are generated at the terminals 11 of the submodule 2 .
[0038] FIG. 5 shows an exemplary embodiment of an electric drive 10. An electrical device 7 is electrically connected to the AC side of a power converter 5. The modular brake controller 1 is connected to the DC side of the power converter 5 via the intermediate circuit 9. The electrical device 7 can be, for example, a power supply network or an electrical machine.
[0039] FIG 6 shows an electric drive 10 in which the power converter 5 is designed as a modular multilevel power converter 51. The modular brake controller 1 and the modular multilevel power converter 51 are connected via the intermediate circuit 9, at which the voltage U Dis applied, are connected to one another. The modular multilevel power converter 51 can, but not necessarily, have as submodules 2 the same submodules 2, i.e. full-bridge modules 21 and / or double half-bridge modules 22, as the modular braking controller 1. The series connection of the submodules 2 of the modular multilevel power converter 51 also has an inductance 8, which improves the control behavior of the modular multilevel power converter 51. The connections LI, L2, L3 represent the AC voltage side connections or, for short, the AC voltage side of the modular multilevel power converter 51. In this exemplary embodiment, the modular multilevel power converter 51 is of three-phase design. Alternatively, a single-phase design with a neutral conductor or any desired number of phases is possible by providing a corresponding number of phase modules in the modular multilevel power converter 51.
[0040] FIG 7 shows a typical time curve of the voltage U B R over the series connection of submodules 2 and the corresponding current i B R by the modular brake controller 1. To avoid repetition, reference is made to the description of Figures 1 to 6 and to the reference numerals introduced there. The proposed structure can be used with various methods for operating the modular brake controller 1. One possibility is the active current and voltage modulation with the modular brake controller 1. The submodules 2 can be viewed as a controllable voltage source. In simplified terms, the modular brake controller 1 modulates a voltage U B R across the series connection of submodules 2 and thus generates a current i B R through the modular brake controller 1 . This current i BR has a constant component 1 BR, DC and an alternating component 1BR, AC . The voltage u BR a DC component U B R, DC and an alternating voltage component u BR , A c , which each generate the DC and AC components in the current through the brake controller. It has been shown that the dynamics and the operating range of the brake controller can be increased by increasing the voltage u across the submodules. BR negative values . For this purpose, the voltage u BR controlled or regulated in such a way that the amplitude of the alternating voltage component U B R, AC is greater than the DC voltage component U BR, DC . To ensure stable operation of the brake controller at this operating point, the full-bridge modules are connected in series. The resulting freely selectable voltage amplitude, even with values beyond the DC voltage component, ensures energy balance between the capacitors of the individual submodules. This enables stable operation of the modular brake controller with a current through the brake controller, whereby this current can assume different polarities. In addition to stable operation, this also ensures high utilization of the operating range of the braking resistor.
[0041] The main task of the modular brake controller 1 is to convert a defined power over time in the braking resistor 3 or the sum of all braking resistors arranged in series into heat. The power to be converted into heat is distributed over the DC component 1 BR, DC controlled or regulated. To ensure the energy balance and stability of the modular brake controller 1, the current 1 B R through the modular brake controller an alternating component i BRf AC The amplitude of the alternating component of the current i BR is started with I AC designated .
[0042] With unipolar submodules, such as half-bridge modules or double half-bridge modules 22, no negative voltages can be generated. The realization of the time curve shown in FIG 7 with values of the voltage u BR of less than zero therefore requires the use of bipolar submodules such as full-bridge modules 21 .
[0043] Operation at higher power levels increases the proportion of modulated, negative voltages across the series connection of the submodules 2, necessitating the use of additional full-bridge modules 21. Likewise, the realization of higher power levels leads to a reduction of the modulated negative current through the modular brake controller. Since unipolar submodules can only provide a positive terminal voltage, the negative portion of the current through the modular brake controller is required to maintain energy balance. This limits the use of unipolar submodules. The possible operating range of the modular brake controller 1 can be determined using the specific resistance R spe c and the constant component i BR , B c of the current i BR by the modular brake controller. This operating range is shown in FIG 8. The specific resistance R spec is the resistance value R related to the intermediate circuit voltage U D , i.e. the operating voltage of the modular brake unit 1 . For a given system configuration, the DC component 1BR, DC of the current i B R by the modular brake controller 1 equivalent to the power converted by the modular brake controller 1 .
[0044] Braking unit variants that are only equipped with unipolar submodules can only be operated in the hatched operating range marked I . Only in this range is the voltage U to be generated B R across the series connection of submodules 2 is always positive. For example, if the system is equipped with a specific resistance R spec = 0 , 5Q / kV , the structure can achieve a maximum DC component 1BR, DC=0 , 5 I Nom can be achieved. I describes Nom is the nominal current of the semiconductor switches used. The proposed modular brake controller 1 can also be operated in this operating range I. If higher power levels, i.e. DC components with 1 B R, DC>0.5 I Nom , can be realized, is a negative voltage u BRacross the series connection of the submodules 2. This is characterized by operating range II, in which operation of the proposed modular braking unit 1 is also possible. Compared with operating range I with only unipolar submodule types, the performance of the proposed modular braking unit 1 is doubled. Operating range III can only be used with a design that exclusively has full-bridge modules 21. Due to the lower voltage that can be generated by a full-bridge module 21 compared to a double half-bridge module 22, the design of a modular braking unit 1 exclusively with submodules 2 of the full-bridge module 21 type has proven to be uneconomical. In comparison, the proposed modular braking unit 1 offers a significantly cheaper and more economical solution.
[0045] Overall, fewer sub-modules are required to construct the modular braking unit. As can be seen from the curves for the voltage to be generated, a higher proportion of positive voltage than negative voltage must be generated. With the double half-bridge modules 22, twice the positive output voltage can be achieved compared to the full-bridge module 21 with the same amount of material. Another key advantage of using a combination of double half-bridge modules 22 and full-bridge modules 21 is the possible mechanical construction of these two variants. The same components are required to construct the two sub-modules in a system. Only the busbar connection of the individual modules between the semiconductors and the sub-module capacitors is different. However, they offer the same dimensions, cooling water connections, electrical connections for the busbar connection, controls, etc.For such a system, there is no need to adapt the structure, such as a cabinet system, and the surrounding peripherals to the specific design of the submodules. Rather, the structure or cabinet system contains mounting devices that can accommodate full-bridge modules and double half-bridge modules without modification. The number and ratio of the installed full-bridge modules 21 and double half-bridge modules 22 can thus be freely varied and scaled within a structure.
[0046] In summary, the invention relates to a modular brake controller 1, comprising a braking resistor 3 and at least two submodules 2, wherein the braking resistor 3 and the submodules 2 are arranged in a series circuit 4. To improve the modular brake controller 1, it is proposed that at least one submodule 2 is designed as a full-bridge module 21 and at least one submodule 2 is designed as a double-half-bridge module 22, wherein the modular brake controller 1 has a control device which is designed to generate a voltage U B R across the series-arranged submodules 2, whereby the voltage U B R a DC voltage component UBR, DC and an AC voltage component U B R, AC, wherein the control device is further configured to control the AC voltage component U BR,AC / in particular with regard to its amplitude, in such a way that the energy absorbed on average by the modular brake resistor 1 is converted into heat in the brake resistor 3, wherein at least temporarily the amplitude of the alternating voltage component UBR,AC is greater than the direct voltage component U B R, DC - The invention further relates to an electric drive 10, comprising such a modular brake controller 1 and a power converter 5, wherein the power converter 5 is electrically connected on the DC voltage side to the modular brake controller 1. The invention further relates to a method for operating such a modular brake controller 1 or such an electric drive 10, wherein the submodules 2 have such a voltage U B R across the submodules 2 arranged in series.
Claims
Patent claims 1. Modular brake controller (1) comprising a brake resistor (3) and at least two submodules (2), wherein the brake resistor (3) and the submodules (2) are connected in series (4) are arranged, wherein at least one submodule (2) is designed as a full-bridge module (21) and at least one submodule (2) is designed as a double half-bridge module (22), wherein the modular brake controller (1) has a control device which is designed to generate a voltage (U B R) across the series-arranged submodules (2), whereby the voltage (U B R) a DC voltage component (U B R,DC) and an alternating voltage component (U B R,AC), wherein the control device is further configured to control the AC voltage component (u BR , Ac) , in particular with regard to its amplitude, in such a way that the energy absorbed on average by the modular brake resistor (1) is converted into heat in the brake resistor (3), wherein at least temporarily the amplitude of the alternating voltage component (u BR , A c) is greater than the DC voltage component (u BR , D c) • 2. Modular brake controller (1) according to claim 1, wherein at least one of the submodules (2), in particular all submodules (2), each has a bypass switch (6) which is designed to short-circuit the terminals (25) of the respective submodule (2).
3. Electric drive (10) comprising a modular brake controller (1) according to one of claims 1 or 2 and a power converter (5), wherein the power converter (5) is electrically connected to the modular brake controller (1) on the DC voltage side.
4. Electric drive (10) according to claim 3, wherein the power converter (5) is designed as a modular multilevel power converter (51).
5. Method for operating a modular brake actuator (1) according to one of claims 1 or 2 or an electric drive (10) according to one of claims 3 or 4, wherein the submodules (2) have a voltage (U B R) across the series-arranged submodules (2), which at least temporarily comprise a negative and a positive voltage range, wherein the voltage (U B R) a DC voltage component (u BRfD c) and an alternating voltage component (u BR , AC ), whereby the alternating voltage component (U BR ,AC) is controlled or regulated in such a way that the energy absorbed on average by the modular brake resistor (1) is converted into heat in the brake resistor (3), wherein at least temporarily the amplitude of the alternating voltage component (u BR , AC) is greater than the DC voltage component (U BR ,DC) •
Citation Information
Patent Citations
Control circuit
EP2777127B1