Asymmetric control method for modular brake adjuster
By employing an asymmetric control method that superimposes rectangular or trapezoidal voltage waveforms and DC components in a modular braking regulator, the problems of inaccurate power control and high cost in the energy conversion process of existing technologies are solved, achieving efficient energy conversion and improved equipment stability.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- INMONDA CO LTD
- Filing Date
- 2024-08-12
- Publication Date
- 2026-06-19
AI Technical Summary
Existing modular brake regulators have difficulty achieving precise control over the power to be converted into heat during the energy conversion process, and there are problems of energy waste and high equipment costs.
By employing rectangular or trapezoidal voltage waveforms in the modular braking regulator, combined with the superposition of DC and alternating components, the control device adjusts the sub-modules to achieve an asymmetrical voltage waveform, ensuring that electrical energy is converted into heat in the braking resistor, and achieving efficient energy management through the combination of modular multilevel converters.
It achieves precise control of the power converted into heat, reduces equipment costs and energy waste, improves the stability and reliability of the modular brake regulator, and adapts to different voltage requirements.
Smart Images
Figure CN122249988A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to a method for operating a modular brake regulator, wherein the modular brake regulator includes at least one submodule and a braking resistor, the submodule and the braking resistor being arranged in a series circuit. Furthermore, this invention relates to a control device and a modular brake regulator, wherein the modular brake regulator includes at least one submodule and a braking resistor, the submodule and the braking resistor being arranged in a series circuit. This invention also relates to a modular drive unit having a modular multilevel converter and such a modular brake regulator, wherein the modular brake regulator is electrically connected to the DC voltage side of the modular multilevel converter. Background Technology
[0002] A modular multilevel converter is disclosed in German patent publication DE 10 103 031 A1. Also known as M2C or MMC, this converter features a converter topology that, due to its submodule construction, is particularly suitable for medium and high voltage applications. The basic structure of this multiphase converter includes two converter arms per phase, each with its own series circuit of submodules. The two converter arms are connected to each other at the phase terminals. The other side of each converter arm is connected to the DC voltage side. The AC voltage side of the modular multilevel converter consists of one or more phase terminals. In this basic structure, energy can be transferred bidirectionally between the DC and AC voltage sides, or stored to some extent in between.
[0003] To achieve additional targeted energy dissipation, it is appropriate to install a brake regulator. A modular brake regulator is disclosed in international patent publication WO 2007 / 023061 A2. This modular brake regulator is typically connected to the DC voltage side of a modular multilevel converter, for example, between the DC+ and DC- terminals.
[0004] The resistance of a brake regulator device is often referred to as a brake resistor because it is suitable for converting the electrical energy generated by a motor during braking into heat. The use of brake regulators is not limited to applications of braking-type electric drives. Therefore, the energy converted into heat is not necessarily braking energy. The brake regulator can also be used, for example, to stabilize a power supply network, achieving the above function by converting electrical energy from the power supply network into heat. The term "brake resistor" is used to distinguish this type of resistor, which converts a given electrical energy or power into heat (or heat per unit time), from other resistors.
[0005] In the following text, the phrase "power to be converted into heat" means that the integral of power over time is converted into heat. In other words, the energy generated by power over time is converted into heat. Summary of the Invention
[0006] The purpose of this invention is to improve a modular brake regulator.
[0007] This objective is achieved through a method for operating a modular brake regulator, wherein the modular brake regulator includes at least one submodule and a braking resistor, the submodule being arranged in series with the braking resistor; wherein a rectangular or trapezoidal voltage is generated at least periodically by means of the at least one submodule, wherein the rectangular or trapezoidal voltage has a DC component and an alternating component, wherein the alternating component has no DC component and is designed such that the electrical energy absorbed by the modular brake regulator over time is converted into heat in the braking resistor; wherein the alternating component consists of a sustained upper voltage value during a first time period and a sustained lower voltage value during a second time period, wherein the first time period and the second time period are not equal in length. Furthermore, this objective is achieved through a control device configured to execute the above method. This objective is also achieved through a modular brake regulator, wherein the modular brake regulator includes at least one submodule and a braking resistor, the submodule being arranged in series with the braking resistor, wherein a rectangular or trapezoidal voltage can be generated by means of the at least one submodule; wherein the modular brake regulator is equipped with such a control device for controlling or regulating the at least one submodule. This objective is also achieved by a modular drive unit having a modular multilevel converter and such a modular brake regulator, wherein the modular brake regulator is electrically connected to the DC voltage side of the modular multilevel converter.
[0008] Other advantageous designs of the invention are given in the dependent claims.
[0009] This invention is particularly based on the understanding that any operating voltage of a modular brake regulator can be achieved through its modular construction. The modular brake regulator is typically connected to the intermediate circuit of a converter to convert electrical energy from the drive system or power supply system into heat. With this modular structure, by employing a corresponding number of sub-modules, the modular brake regulator can be adapted to arbitrarily high intermediate circuit voltages.
[0010] All known types of submodules can be used here. For example, this includes half-bridge modules, dual half-bridge modules, or full-bridge modules. To generate a voltage, only the capacitor voltage of the respective submodule can be used. Alternatively, a voltage smaller than the voltage of the one or more capacitors can be generated by the submodule, for example, by employing pulse width modulation. Pulse width modulation has proven advantageous for generating different voltages, especially when using only one submodule.
[0011] Furthermore, the method for operating the modular brake regulator allows for precise control or adjustment of the power to be converted into heat. This heat is derived from the power integrated over time. The method is designed so that not all intermediate circuit voltage drops across the braking resistor during energy conversion. Its advantage lies in the ability to regulate the power to be converted into heat. Simultaneously, the energy content of one or more capacitors in the at least one or more sub-modules can be adjusted. Therefore, stable operation of the modular brake regulator can be achieved even over extended operating periods, particularly during continuous operation.
[0012] The braking resistor can be positioned anywhere in the series circuit. For example, the braking resistor can be positioned between one terminal of the modular brake regulator and a submodule, or anywhere between two submodules.
[0013] When the modular brake regulator is not activated, i.e. should not convert electrical energy into heat, the voltage applied to the at least one submodule or another series circuit of the submodule is the same as the voltage of the intermediate circuit, so there is no voltage drop across the resistor and therefore no current flows through it.
[0014] For control or regulation, a voltage is generated on at least one submodule; or, if multiple submodules are arranged in another series circuit, a voltage is generated on another series circuit of that submodule. A DC component of the voltage is provided for controlling or regulating the power to be converted into heat. An alternating component is superimposed on the DC component to regulate the capacitor voltage of one or more submodules or multiple capacitor voltages. The superposition of the DC and alternating components yields a rectangular waveform of the voltage. This rectangular waveform further requires that the voltage in the other series circuit can change arbitrarily rapidly. This results in an infinitely steep voltage gradient. Since these voltages generate corresponding currents, limiting the rate of change of the voltage has proven advantageous. Due to the currents accompanying voltage changes, the modular brake regulator is also suitable for brake regulators with inductance (e.g., parasitic inductance as a braking resistor). The rectangular waveform voltage then transforms into a trapezoidal waveform voltage.
[0015] The rectangular or trapezoidal waveform curve of the alternating component consists of a sustained upper voltage value during a first time period and a sustained lower voltage value during a second time period, wherein the first and second time periods are not equal. Therefore, the rectangular waveform curve is asymmetrical, and the corresponding method can also be called asymmetrical. To ensure that the alternating component contains no DC component, the product of the upper voltage value and the first time period, and the product of the lower voltage value and the second time period, must be equal in absolute value. The upper voltage value is positive, and the lower voltage value is negative. For a rectangular waveform curve, in a simple case, the sum of the first and second time periods equals the period of the repetitive drive. For trapezoidal signals, the rise and fall times must also be considered. However, since these durations are very short compared to the first and second time periods, they can be ignored in energy analysis.
[0016] It has been proven to have beneficial effects: using rectangular or trapezoidal waveform voltages, even with relatively small voltage amplitudes in the other series circuit of the submodule and relatively small current amplitudes flowing through the modular braking regulator, high energy exchange can still be achieved; this is because energy is derived from the integral of current over time, or from the integral of the square of current over time. In other words, higher power can be achieved. This involves both the power to be converted into heat and the power used to stabilize the submodule. In other words, due to the relatively low absolute values of current and voltage, especially the small amplitudes or maximum values in the current and voltage waveforms, a high effective value can still be achieved, which is crucial for heat conversion through the braking resistor. Because of the lower voltage amplitude and fluctuation range resulting from the use of rectangular or trapezoidal waveform voltages and the resulting current, the semiconductor switches of the submodule can be designed for lower current loads. Alternatively, the modular braking regulator can also be used to convert higher power into heat.
[0017] A rectangular or trapezoidal waveform voltage can be easily generated by a control device that drives the semiconductor switches of a single or multiple submodules in the other series circuit. This rectangular or trapezoidal waveform voltage is then applied to the submodule or to another series circuit composed of the submodules.
[0018] A particularly advantageous approach is to combine a modular brake regulator with a modular multilevel converter (also known as an M2C converter) into a single modular drive unit. Submodules with identical structures can be used in both the modular multilevel converter and the modular brake regulator. Similarly, the same hardware can be used to control the submodules. By leveraging the modular structure of the converter and the modular brake regulator, and selecting the appropriate number of submodules from both, the modular drive unit can be easily adapted to the required power demands. The identical structural design of the submodules in both the modular brake regulator and the multilevel converter allows for a high percentage of common components. This has a positive impact on the reliability and production cost of such drive units.
[0019] This modular brake regulator can be connected to the DC voltage side of any converter and is not limited to use with modular multilevel converters.
[0020] The rectangular or trapezoidal waveform voltage generated by the submodule contains both DC and alternating components. To achieve the rectangular or trapezoidal waveform curve, the alternating component also has a rectangular or trapezoidal waveform curve.
[0021] A current, which also has a DC component, is generated by a modular brake regulator using the DC component of the voltage. This DC component flows through the modular brake regulator and then through the braking resistor. The current flowing through the braking resistor generates electrical losses. These losses are used to purposefully convert electrical energy into heat. The amount of power converted into heat (i.e., energy per unit time) can be controlled or adjusted by the magnitude of the DC component of the voltage; this directly yields the voltage drop across the resistor and, consequently, the magnitude of the other DC component of the current flowing through the modular brake regulator.
[0022] The intermediate circuit voltage is applied to the modular brake regulator because it is electrically connected to the intermediate circuit. Therefore, the intermediate circuit voltage is applied to the series circuit consisting of the braking resistor and another series circuit of the submodule. Alternatively, a single submodule can be used instead of the other series circuit of the submodule. Thus, the modular brake regulator, bearing the intermediate circuit voltage, absorbs active power.
[0023] All active power absorbed by the braking resistor should be converted into heat, because this modular braking regulator should not be designed to absorb and store a significant amount of energy.
[0024] The alternating component exhibits a rectangular or trapezoidal waveform, configured such that the electrical energy absorbed by the modular brake regulator over time is converted into heat in the braking resistor. The alternating component can influence the capacitor voltage of the submodule and stabilize the modular brake regulator. The alternating voltage component creates another alternating component in the current flowing through the modular brake regulator by generating a corresponding voltage drop across the braking resistor. Both this alternating component and the other alternating component have an average value of zero, thus only reactive power exchange occurs between this other alternating component of the current and the intermediate circuit voltage or the voltage on the modular brake regulator. Therefore, this alternating component contains no DC component. It has been advantageously demonstrated that this component can be used to exchange energy between the capacitor and resistor of the submodule. This energy exchange is advantageously controlled or regulated so that all active power across the resistor is converted into heat. The electrical energy absorbed by the modular brake regulator over time is converted into heat in the braking resistor. The relationship can be expressed as: , Among them, the current i flowing through the braking resistor BR From DC component i BR,DC With alternating component i BR,aDC According to the formula
[0025] Composition. Therefore, the alternating component can be determined based on the voltage waveform that affects the effective value.
[0026] By deviating the alternating component from the symmetrical waveform, energy exchange within the modular brake regulator can be improved. This allows for a reduction in the design size of capacitors in the submodules.
[0027] In this case, for example, the maximum chopper voltage, which is the sum of the upper voltage value and the DC component, can be limited to a preset limit. This limit is greater than the intermediate circuit voltage. Under the boundary condition of adhering to the above equations and keeping the effective value of the modular braking regulator current constant, the upper voltage value, the lower voltage value, and the corresponding values for the first and second time periods are obtained. This yields different current and voltage waveforms, which can also be called half-waves, even though the durations differ from one another. In other words, the maximum chopper voltage is the sum of the upper voltage value and the DC component.
[0028] During the first time period, the maximum chopper voltage is limited to a certain limit. Since the effective value remains constant, the power converted in the modular braking regulator is equal to the value obtained by multiplying the DC component and the intermediate circuit voltage. By limiting the voltage, a significantly higher current is generated during the second time period, which facilitates the conversion of electrical energy into heat.
[0029] In an advantageous design of the present invention, the modular brake regulator includes multiple sub-modules arranged in another series circuit; wherein, with the aid of the multiple sub-modules, a rectangular or trapezoidal waveform voltage is generated on the other series circuit. By employing multiple sub-modules in the other series circuit, the operating voltage of the modular brake regulator can be arbitrarily adapted to the intermediate circuit voltage of the converter. This allows for an arbitrarily high operating voltage, i.e., the intermediate circuit voltage in the drive unit.
[0030] In another preferred embodiment of the invention, the DC component is controlled or regulated based on the power to be converted into heat by the modular brake regulator, or based on the voltage applied to the modular brake regulator. The power to be converted into heat or the voltage applied to the modular brake regulator is preset by a setpoint. Regulation can be easily achieved by comparing the setpoint with the actual value, for example, using a PI regulator. Therefore, controlling or regulating the DC component based on the power to be converted into heat has proven advantageous. This power may in turn depend on other physical quantities, such as the voltage of the submodule capacitors in the modular multilevel converter. If the modular brake regulator operates on an intermediate circuit with intermediate circuit capacitors, for example, on a two-level or three-level converter, it has proven advantageous to control or regulate the DC component based on the intermediate circuit voltage. Using these regulation structures, dynamic regulation of the conversion of electrical power into heat can be achieved, which protects the electric drive unit from overload due to excessive energy. This energy may, for example, come from the braking process of the motor.
[0031] In another preferred embodiment of the invention, the DC component is controlled or regulated to generate a current with a further DC component via a modular braking regulator. The product of this further DC component and the voltage on the modular braking regulator corresponds to a predetermined power to be converted into heat by the modular braking regulator, specifically, a predetermined active power to be converted into heat by the modular braking regulator. The DC component of the voltage is controlled or regulated in terms of voltage amplitude such that the magnitude of the other DC component of the current satisfies that the product of the intermediate circuit voltage and this other DC component corresponds to the power value to be converted into heat by the modular braking regulator. The power to be converted into heat refers to the energy converted into heat within a specific time period. Alternatively, the active power can also be defined as the power to be converted into heat.
[0032] In another preferred embodiment of the invention, the sum of the upper voltage value and the DC component is limited to a limit independent of operation. This reduces the maximum voltage required to be generated by the submodule, thereby reducing the number of submodules. This enables a low-cost structural design for the modular brake regulator. Since energy fluctuations in the modular brake regulator are also reduced, the submodules can be implemented using capacitors with smaller capacitance values. This also contributes to low-cost expansion.
[0033] In another preferred embodiment of the invention, the alternating component is used as the manipulated variable for regulating the voltage of the submodule capacitor. To eliminate interference, it has proven advantageous to use the value of the alternating component, determined according to the formula, for feedforward control. The voltage across the capacitor is then regulated. Therefore, the modular braking regulator operates stably even in the presence of interference. Furthermore, this operation is unaffected by changing parameters. For example, changes in resistance caused by aging or temperature rise can be easily compensated for through adjustment.
[0034] In another preferred embodiment of the invention, the AC voltage side of the modular multilevel converter is connected to an energy source, particularly a power grid or a motor. The modular brake regulator, connected to the energy source, converts excess or unusable energy into heat. This energy source can be, for example, a motor that feeds back electrical energy during braking. If this electrical energy cannot be further utilized, it must be converted into heat using the modular brake regulator when the mechanical brake is no longer needed. Unlike mechanical brakes, the conversion of electrical energy into heat is wear-free, making the modular brake regulator more economical in operation.
[0035] Similarly, modular multilevel converters can also be used for energy transmission. In this case, it is reasonable to install a modular braking regulator when the transmitted energy cannot be absorbed. This modular braking regulator ensures that such energy transmission can continue to operate even in the event of a failure in energy reception. The energy transmission system can remain operational during this failure period and reliably avoid complex restarts and shutdowns that could lead to instability issues in the power grid. Therefore, the modular braking regulator also improves the reliability and availability of modular drive units designed for energy transmission.
[0036] In another preferred embodiment of the invention, the control device of the modular drive unit is configured to determine the power to be converted into heat based on the capacitor voltage of the modular multilevel converter submodule. In a modular multilevel converter, the energy stored within the converter is not necessarily reflected in the intermediate circuit voltage as in, for example, a 2-level or 3-level converter. For a modular multilevel converter, an increased energy content affects the stored energy, i.e., the voltage, of one or more capacitors in each submodule. To specifically reduce the energy content in a modular multilevel converter, it has proven advantageous to determine the power to be converted into heat for controlling or regulating the DC component based on the capacitor voltage of each submodule. A possible method for operating an electrical drive unit with a modular converter and the proposed modular brake regulator involves regulating or controlling the DC component of the voltage on another series circuit of a submodule of the modular brake regulator based on the voltage of one or more capacitors in a submodule of the modular multilevel converter.
[0037] The present invention will now be described and illustrated in more detail with reference to the embodiments shown in the accompanying drawings. Attached Figure Description
[0038] Figure 1 A modular brake regulator is shown. Figures 2 to 4 An example of a submodule is shown. Figure 5 and Figure 6 The voltage and current time curves are shown. Figure 7 and Figure 8 The effect of the control method on the maximum chopper voltage and energy swing is shown, as well as Figures 9 to 11 An embodiment of the modular drive unit is shown. Detailed Implementation
[0039] Figure 1 A modular brake regulator 1 is shown. This modular brake regulator has a series circuit 4 consisting of at least one sub-module 2 and a braking resistor 3. The series circuit 4 may include multiple sub-modules 2. These sub-modules are, in turn, arranged as part of another series circuit 41. The modular brake regulator 1 is configured to be connected to the intermediate circuit 9 of the converter at its terminals 11.
[0040] With the aid of control device 10, a voltage u can be generated on the other series circuit 41 of the submodule. BR Using voltage u BR This can make the current i BR Current i flows through modular brake regulator 1.BR It also flows through the braking resistor 3, converting electrical energy into heat. A working voltage U is applied to the modular brake regulator 1. D If the modular brake regulator 1 is connected to the intermediate circuit of the converter, then the intermediate circuit voltage is applied to the modular brake regulator. In this case, it is considered that the modular brake regulator 1 is connected to the DC voltage side of the converter.
[0041] Figures 2 to 4 An embodiment of submodule 2 is shown. All known submodules, especially... Figures 2 to 4 The submodules shown are all applicable to implementing the proposed method. To avoid duplication, see [link to relevant documentation]. Figure 1 The description and the reference numerals introduced therein.
[0042] The illustrated embodiment of submodule 2 includes at least two semiconductor switches and at least one capacitor. By switching the semiconductor switches, an output voltage U can be generated at the terminals of submodule 2. sub During this process, the control device 10 transmits drive signals to each semiconductor switch of the submodule 2. The control device 10 is preferably located outside the submodule 2 and is therefore not part of the submodule. In practice, it has proven advantageous to use a single control device 10 to control all submodules 2 of the modular brake regulator 1. Furthermore, the control device 10 can perform calculations required for controlling and regulating voltage and current. Therefore, the control device 10 can determine the required current i flowing through the modular brake regulator based on a predetermined value of the power to be converted into heat. BR To generate this current i BR Through corresponding drive signals, voltages determined, controlled, or regulated by the control device 10 are generated on each sub-module of another series circuit 41. In the following embodiments, illustrations of the control device 10 are omitted for clarity.
[0043] Figure 2 This illustrates a so-called half-bridge module. The half-bridge module has two semiconductor switches and one capacitor. A voltage U is applied across the capacitor. C,sub By switching the semiconductor switch, a zero voltage or voltage U can be generated at the terminals of submodule 2. C,sub Output voltage U in form sub .
[0044] Figure 3 This diagram illustrates a so-called dual-bridge module. The dual-bridge module has four semiconductor switches and two capacitors. A voltage U is applied across each of the two capacitors. C1,sub with U C2,sub By switching the semiconductor switch, an output voltage U can be generated at the terminals of submodule 2. subIts value can be zero, and one of the capacitor voltages U C1,sub or U C2,sub Or it could be the capacitor voltage U. C1,sub with U C2,sub sum.
[0045] Figure 4 This illustrates a so-called full-bridge module. The full-bridge module has four semiconductor switches and one capacitor. A voltage U is applied across the capacitor. C,sub By switching the semiconductor switch, an output voltage U can be generated at the terminals of submodule 2. sub It can be zero, positive capacitor voltage, or negative capacitor voltage, i.e., ±U C,sub .
[0046] Figure 5 The voltage u on each sub-module 2 of another series circuit 41 in the proposed method is shown. BR The time-varying curve. To avoid repetition, see the section on... Figures 1 to 4 The description and the reference numerals used in the figures. Voltage u BR From DC component u BR,DC and alternating component u BR,aDC Composition. During the first time period τ1, the voltage u BR Take the maximum chopper voltage u BR,max This is due to the DC component U BR,DC With the upper voltage value u BR,AC1 Superimposed. For the braking resistor current i BR,eff To generate the required effective value, the first time period τ1 is greater than half a cycle T; since the second time period τ2 is shorter than the first time period τ1, the lower voltage value u BR,AC2 The absolute value is greater than the upper voltage value u. BR,AC1 This ensures that the alternating component does not contain a direct current component.
[0047] Due to the finite voltage steepness shown in the figure, the voltage waveform is a trapezoidal voltage curve. The figure also idealizes a curve with an infinite voltage steepness using dashed lines; this curve appears as a rectangular waveform time curve. Even if the individual trapezoidal or rectangular waveforms are not identical and exhibit differences, they can still be called trapezoidal or rectangular waveforms. However, the areas of each rectangle or trapezoid in the alternating component are equal.
[0048] Figure 6 The generated voltage u is shown BR For the current i flowing through the braking resistor BR The relatively low voltage during the first time period τ1 results in a smaller current during that time interval. Therefore, to achieve the desired effective value, the current during the second time period τ2 is significantly higher.
[0049] If the first time interval τ1 and the second time interval τ2 are chosen to be equal in order to form an alternating component, a symmetrical time-varying curve will be generated. This yields the maximum chopper voltage u, which depends on the partial load factor α. BR,max The corresponding values for energy fluctuation ΔE, these values are in Figure 7 The diagram is presented in normalized form. Energy fluctuations will cause energy fluctuations on the capacitors of submodule 2.
[0050] Energy fluctuation ΔE is a measure of the amount of energy required to be stored in the capacitor of submodule 2. Therefore, it determines the capacitor's size design in terms of capacitance. The partial load factor α indicates how much of the maximum power the modular brake regulator 1 converts into heat at its current operating point.
[0051] The advantages of the proposed method are: Figure 8 As shown in the diagram, the first time period τ1 and the second time period τ2 are different. This is achieved by adjusting the maximum chopper voltage u. BR,max Limiting the voltage to 1.05 times the intermediate circuit voltage reduces the voltage generated by the submodules. Therefore, fewer submodules are required for operation, making the implementation of the modular brake regulator simpler and less costly. Furthermore, the asymmetric waveform offers another advantage: a significantly reduced energy fluctuation ΔE allows for smaller capacitance designs in the submodule capacitors. This simplifies the submodule design and makes the modular brake regulator more cost-effective and economical.
[0052] As can be seen, by employing the proposed method, the number of sub-modules to be installed can be reduced by approximately 20%, and the energy storage capacity of the capacitors to be installed can be reduced by approximately 65%, for the modulation scheme illustrated in the example. This method can also be applied analogously to other modulation schemes of modular brake regulators. The proposed method can also be used to reduce the limit of the maximum chopper current by increasing the maximum modulation chopper voltage.
[0053] Figure 9A modular drive unit 20 with a modular multilevel converter 21 and a modular brake regulator 1 is shown. The modular multilevel converter 21 and the modular brake regulator 1 are interconnected via an intermediate circuit 9 to which a voltage UD is applied. The modular multilevel converter 21 may, but does not necessarily, have the same sub-module 2 as the modular brake regulator 1. Furthermore, the series circuit of the sub-module 2 of the modular multilevel converter 21 includes an inductor 8, which improves the regulation characteristics of the modular multilevel converter 21. Terminals L1, L2, and L3 represent the AC voltage side terminals of the modular multilevel converter 21, or simply its AC voltage side. In this embodiment, the modular multilevel converter 21 is designed as a three-phase structure. Alternatively, a single-phase structure with a neutral line, or a structure with any number of phases, is also feasible, provided that a matching number of phase modules are appropriately provided in the modular multilevel converter 21.
[0054] Figure 10 An embodiment of the modular drive unit 20 is shown. In this embodiment, the energy source 5 is electrically connected to the AC voltage side of the modular multilevel converter 21. This energy source can be, for example, a power grid 6 or a motor 7.
[0055] exist Figure 11 In this embodiment, the modular drive unit 20 has two modular multilevel converters 21 and a modular brake regulator 1, which are electrically connected to each other at an intermediate circuit 9. The first of the two modular multilevel converters (21) is connected to the power grid (6) on its AC voltage side, and the second of the two modular multilevel converters (21) is connected to the motor (7) on its AC voltage side. The motor 7 can be powered by the power grid 6. Using the modular drive unit 20, energy can also be fed back from the motor 7 to the power grid 6 during braking, for example. If the power grid 6 does not have absorption capacity, the electrical energy obtained by the motor 7 can be advantageously converted into heat by the modular brake regulator 1. In this structure, the easily worn mechanical brake can be omitted.
Claims
1. A method for operating a modular brake regulator (1), the modular brake regulator (1) comprising at least one submodule (2) and a braking resistor (3), the submodule (2) and the braking resistor (3) being arranged in a series circuit (4), wherein, At least in stages, rectangular or trapezoidal waveform voltages (u) are generated using at least one of the aforementioned submodules (2). BR ), wherein the rectangular waveform voltage or trapezoidal waveform voltage (u BR It has a DC component (u) BR,DC ) and alternating components (u BR,aDC ), wherein the alternating component (u BR,aDC ) by the upper voltage value (u BR,AC1 ) and the lower voltage value (u BR,AC2 The structure consists of an upper voltage value that persists during a first time period (τ1) and a lower voltage value that persists during a second time period (τ2), wherein the first time period (τ1) and the second time period (τ2) are not equal, and wherein the DC component (u) is used to... BR,DC The power to be converted into heat is controlled or regulated, wherein the power is controlled or regulated by means of the DC component (u) superimposed on the DC component. BR,DC The alternating component (u) above BR,aDC ), to adjust the capacitor voltage of the submodule (2) or each submodule (2).
2. The method according to claim 1, wherein, The modular brake regulator (1) includes multiple sub-modules (2), wherein the multiple sub-modules are arranged in another series circuit (41), wherein the rectangular waveform voltage or trapezoidal waveform voltage (u) is generated on the other series circuit (41) of the sub-modules (2) by means of the multiple sub-modules (2). BR ).
3. The method according to any one of claims 1 or 2, wherein, The DC component (u) BR，DC The power to be converted into heat by the modular brake regulator (1), or the voltage (U) applied to the modular brake regulator (1) D To control or regulate.
4. The method according to claim 3, wherein, For the DC component (u) BR，DC ) to control or regulate, so as to generate a DC component (i) through the modular brake regulator (1). BR，DC The current (i) BR ), wherein the other DC component (i BR，DC ) and the voltage (U) applied to the modular brake regulator (1) D The product of ) is equal to the predetermined power to be converted into heat by the modular brake regulator (1), especially the predetermined active power to be converted into heat by the modular brake regulator (1).
5. The method according to any one of claims 3 or 4, wherein, The upper voltage value (u) BR，AC1 ) and the DC component (u BR，DC The sum of these values is limited to a limit independent of the operation (u). BR，max ).
6. The method according to any one of claims 1 to 5, wherein, The alternating component (u) BR，aDC ) is used to regulate the capacitor voltage (U) of each submodule (2). C，sub The amount of manipulation.
7. A control device (10) configured to perform the method according to any one of claims 1 to 6.
8. A modular brake regulator (1), wherein, The modular brake regulator (1) includes at least one submodule (2) and a braking resistor (3), the submodule (2) and the braking resistor (3) being arranged in a series circuit (4), wherein a rectangular or trapezoidal waveform voltage (u) can be generated by means of at least one of the submodules (2). BR In order to control or adjust at least one of the sub-modules (2), the modular brake regulator (1) has a control device (10) according to claim 7.
9. The modular brake regulator (1) according to claim 8, wherein, The modular brake regulator (1) includes multiple sub-modules (2) arranged in another series circuit (41), wherein, by means of the multiple sub-modules (2), a rectangular or trapezoidal waveform voltage (u) can be generated on the other series circuit (41). BR ).
10. A modular drive unit (20) having a modular multilevel converter (21) and a modular brake regulator (1) according to any one of claims 8 or 9, wherein, The modular brake regulator (1) is electrically connected to the DC voltage side of the modular multilevel converter (21).
11. The modular drive unit (20) according to claim 10, wherein, The AC voltage side of the modular multilevel converter (21) is connected to an energy source (5), especially to a power grid (6) or a motor (7).
12. The modular drive unit (20) according to any one of claims 10 or 11, wherein, The control device (10) is configured to determine the power to be converted into heat based on the voltage of the capacitors of the sub-modules of the modular multilevel converter (21).