Method and device for the energy management of an electrically driven actuator

Abstract

Method for the energy management of an electrically driven actuator, which is to be supplied from a long-term energy storage device with a nominal voltage designed for normal operation and which is coupled to a mechanical component, the normal operation of which comprises alternating acceleration and braking phases, possibly with standstill phases between one braking phase and the next acceleration phase or vice versa, in particular for the energy management of a preferably mobile robot application, wherein in the method - an electrical system is provided which is equipped with - a long-term energy storage device (26), in particular a battery-based long-term energy storage device (26), - a short-term energy storage device (30), in particular a capacitive short-term energy storage device (30), - a bidirectional DC / DC switching regulator (12) having a current regulator (24) which is connected between the two energy stores, and - a coupling circuit (34) with an input connected to the short-term energy storage device (30) and with an output connected to the actuator (38), wherein the coupling circuit (34) can be a component of the actuator (38), characterized in that - the magnitude of the voltage at the input of the coupling circuit (34) is determined, - it is examined whether the voltage at the input of the coupling circuit (34) lies in a first voltage range below a predetermined minimum value or in a second voltage range above a predetermined maximum value or in a nominal voltage range designed for normal operation of the actuator (38), which lies between the minimum value and the maximum value and contains the value for the nominal voltage, and - by means of a PI controller with a multiplicatively connected non-linear function with a positive slope, the setpoint value for the current controller (24) of the DC / DC switching controller (12) is specified as a function of the difference between the voltage at the input of the coupling circuit (34) and the nominal voltage, wherein - the slope of the non-linear function is small when the voltage at the input of the coupling circuit (34) is within the nominal voltage range, - the slope of the non-linear function is large when the voltage at the input of the coupling circuit (34) is outside the nominal voltage range, and - the current specification generated by the PI controller for the current-controlled DC / DC converter is limited to an upper and lower maximum current in such a way that an acceptable current is achieved for the long-term energy storage device under all charging states.

Description

[0001] The invention relates to a method and a device for the energy management of an electrically driven actuator, which is, for example, a motor, and which is coupled to a mechanical component whose normal operation comprises alternating acceleration and deceleration phases and, if appropriate, standstill phases between the two. In particular, the invention relates to a method and a device for the energy management of a preferably mobile robot application.

[0002] In J. Cao, A. Emadi: “A New Battery / Ultra Capacitor Hybrid Energy Storage System for Electric, Hybrid, and Plug-In Hybrid Electric Vehicles”, in IEEE Transactions on Power Electronics, Volume: 27, Issue: 1, pp. 122-132, 2012, a method and an apparatus according to the preambles of claims 1, 2, 9 and 10 are described.

[0003] DE 10 2014 117 444 A1 describes a digital controller for a power switching converter which has a PI controller with a non-linear controller function that defines different gain levels for different threshold values.

[0004] From DE 33 41 344 A1 a longitudinal voltage regulator with a characteristic curve is known which has a small gradient within a medium voltage range and a large gradient outside this voltage range. Introduction and state of the art

[0005] In a variety of stationary and mobile robotic applications, or in the field of electrically powered vehicles, acceleration and deceleration (braking) of electrically driven actuators alternate in rapid succession. Energy is required for acceleration, while energy is recovered during braking. It is often desirable, particularly in battery-powered systems, not to convert the recovered electrical energy into heat, but to temporarily store it for the next acceleration process (recuperative systems with electrical energy recovery). Such temporary storage can be achieved directly in the connected battery, but this is of little use for frequently recurring load changes, as this would result in a high number of short charging and discharging cycles, often with high current peaks, which damage the battery and reduce its service life.It is therefore sensible to use energy storage devices that are more cycle-resistant for the short-term intermediate storage of circulating energy. In addition to electromechanical approaches such as flywheels, capacitors are also suitable for storage. However, it is usually not sufficient to simply connect the capacitor bank in parallel with the battery, since the small voltage swing during load changes means that only a small proportion of the power flows through the capacitor bank. Arrangements are therefore required which ensure that the load peaks (both positive and negative) are absorbed by the capacitors and, if possible, only the constant load component has to be borne by the battery. Various approaches exist for this, one of which is described in DE 10 2013 104 426 A1. The following explanations are limited to systems in which the actuator (e.g. a servo drive) is connected to the battery via a DC / DC switching regulator (see . Fig.1). For example, because the variation in battery voltage during the battery discharge process would exceed the operating range of the actuator, or the battery voltage is too high or too low for the actuator overall. The switching regulator

[0006] To get a suitable application Fig. To obtain an optimized switching regulator, the boundary conditions must first be defined. It is further assumed that the energy storage is provided in the DC circuit between the switching regulator and the actuator. It is also assumed that in this DC circuit, which has a nominal voltage of U nom should have a voltage fluctuation between U min and U maxis tolerable. Other variants are also technically feasible, but this variant is particularly simple because it requires less communication between the components involved. Each component can read the charge level of the energy buffer from the voltage of the DC circuit and – depending on the component's respective task – take appropriate actions. In the following, the combination of inverter and motor is referred to as the actuator.

[0007] In a first step, it is assumed that the capacitor bank in the mentioned DC circuit is designed large enough to operate within the permissible voltage range between U max and U min to absorb or release the typically circulating energy. Here, ΔE is the circulating energy, C is the capacitor capacitance, R ESR the capacitor internal resistance, I peakpthe maximum current flowing into the actuator (positive sign) and I peakn The maximum current flowing back from the actuator (negative sign). The series inductance of the capacitor can be neglected for such slow processes as those expected in the applications considered here. This should also be understood as a "conservative" estimate, which assumes that the maximum charging or discharging current can still occur when the capacitor is already fully discharged or charged. In most cases, however, the capacitor can be somewhat smaller. ΔE=12C(Umax−Ipeakp⋅RESR)2−12C(Umin−Ipeakn⋅RESR)2 ⇒C=2⋅ΔE(Umax−Ipeakp⋅RESR)2−(Umin−Ipeakn⋅RESR)2

[0008] Due to the energy content of the capacitor being proportional to the square of the voltage, the nominal voltage U nomnot be placed exactly in the middle between maximum and minimum voltage, but (this time neglecting the internal resistances) on: ΔEUmax−Unom=ΔEUnom−Umin Unom=Umax2+Umin22

[0009] For small deflections, U nom but still well within the mean value of U max and U min .

[0010] Conventional switching regulators are not suitable for operation in this topology, namely in recuperative systems, because they do not have at least one of the required properties listed below: - Ability to feed energy back into the battery if larger amounts of energy are generated than those expected during typical cyclic movement, for example when driving downhill in an electric vehicle. - Constant current charging capability to charge the high-capacity buffer capacitor with possibly low internal resistance without stability problems. - Weak readjustment in the range between minimum and maximum voltage, but strong readjustment outside of this range, as well as adjustability of control parameters and voltage thresholds. - Differently adjustable current limit for forward and reverse operation. - Reconfigurability of parameters during operation.

[0011] The object of the invention is to provide a method and a device for the energy management of recuperating systems in which the energy storage devices (e.g. battery and capacitor) can be operated gently and in an optimized manner for their respective physical properties.

[0012] To achieve this object, the invention proposes a method according to claim 1 or 2 and a device according to claim 9 or 10 for the energy management of an electrically driven actuator to be supplied from a long-term energy storage device with a nominal voltage designed for normal operation, which actuator is coupled to a mechanical component whose normal operation comprises alternating acceleration and braking phases, optionally with standstill phases between one braking phase and the next acceleration phase or vice versa, in particular for the energy management of a preferably mobile robot application.

[0013] In the method according to the invention - an electrical system is provided which is equipped with - a long-term energy storage device, in particular a battery-based long-term energy storage device, - a short-term energy storage device, in particular a capacitive short-term energy storage device, - a bidirectional DC / DC switching regulator with a current regulator, which is connected between the two energy storage devices, and - a coupling circuit with an input connected to the short-term energy storage device and an output connected to the actuator, whereby the coupling circuit can be a component of the actuator, - determines the voltage at the input of the coupling circuit, - examines whether the voltage at the input of the coupling circuit lies in a first voltage range below a specified minimum value or in a second voltage range above a specified maximum value or in a nominal voltage range designed for normal operation of the actuator, which lies between the minimum value and the maximum value and contains the value for the nominal voltage, and - a PI controller with a multiplicative upstream non-linear function with a positive slope, which specifies the setpoint for the current controller of the DC / DC switching regulator as a function of the difference between the voltage at the input of the coupling circuit and the nominal voltage, by - the slope of the non-linear function is small when the voltage at the input of the coupling circuit is within the nominal voltage range, and - the slope of the non-linear function is large when the voltage at the input of the coupling circuit is outside the nominal voltage range, - whereby the current specification generated by the PI controller for the current-controlled DC / DC converter is limited to an upper and lower maximum current in such a way that an acceptable current is achieved for the long-term energy storage device under all charging states.

[0014] According to an alternative proposal of the invention, the method - an electrical system is provided which is equipped with - a long-term energy storage device, in particular a battery-based long-term energy storage device, - a short-term energy storage device, in particular a capacitive short-term energy storage device, - a bidirectional DC / DC switching regulator with a current regulator, which is connected between the two energy storage devices, and - a coupling circuit with an input connected to the short-term energy storage device and an output connected to the actuator, whereby the coupling circuit can be a component of the actuator, - determines the voltage at the input of the coupling circuit, - examines whether the voltage at the input of the coupling circuit lies in a first voltage range below a specified minimum value or in a second voltage range above a specified maximum value or in a nominal voltage range designed for normal operation of the actuator, which lies between the minimum value and the maximum value and the value for the nominal voltage, and - the setpoint for the current regulator of the DC / DC switching regulator is specified as a function of the difference between the voltage at the input of the coupling circuit and the nominal voltage according to a non-linear regulator function by, - when the voltage at the input of the coupling circuit is above the nominal voltage but within the nominal voltage range, a current up to a maximum of a first forward maximum current is fed from the long-term energy storage device into the coupling circuit through the DC / DC switching regulator, - when the voltage at the input of the coupling circuit is below the nominal voltage but within the nominal voltage range, a current up to a maximum of a first reverse maximum current flows through the DC / DC switching regulator to the long-term energy storage device, - when the voltage at the input of the coupling circuit is within the first voltage range, a current up to a maximum of a second forward maximum current, which is greater than the first forward maximum current, is fed from the long-term energy storage device into the coupling circuit by the DC / DC switching regulator, and - when the voltage at the input of the coupling circuit is within the second voltage range, a current up to a maximum of a second reverse maximum current, which is greater than the first reverse maximum current, flows through the DC / DC switching regulator to the long-term energy storage device.

[0015] The device according to the invention is provided with - a long-term energy storage device, in particular a battery-based long-term energy storage device, - a short-term energy storage device, in particular a capacitive short-term energy storage device, - a bidirectional DC / DC switching regulator with a current regulator, which is connected between the two energy storage devices, - an electrical coupling circuit with an input connected to the short-term energy storage device and an output connected to the actuator, whereby the coupling circuit can be a component of the actuator, and - a voltage regulator with a PI controller and an upstream non-linear function, to which the voltage difference between the input of the coupling circuit and the nominal voltage can be fed and which specifies a setpoint for the current regulator as a function of the voltage difference according to its control behavior and the upstream non-linear function by - when the voltage at the input of the coupling circuit is within a specified nominal voltage range, the regulator is weakly controlled, - when the voltage at the input of the coupling circuit is outside a specified nominal voltage range, the regulator is heavily controlled, - the current specification for the DC / DC converter is limited to a value permissible for the long-term energy storage.

[0016] In an alternative embodiment of the invention, the device according to the invention is provided with - a long-term energy storage device, in particular a battery-based long-term energy storage device, - a short-term energy storage device, in particular a capacitive short-term energy storage device, - a bidirectional DC / DC switching regulator with a current regulator, which is connected between the two energy storage devices, - an electrical coupling circuit with an input connected to the short-term energy storage device and an output connected to the actuator, whereby the coupling circuit can be a component of the actuator, and - a voltage regulator with a non-linear control function, to which the voltage difference between the input of the coupling circuit and the nominal voltage can be fed and which specifies a setpoint for the current regulator as a function of the voltage difference according to the non-linear control function by - when the voltage at the input of the coupling circuit is above the nominal voltage but within a specified nominal voltage range, a current up to a maximum of a first forward maximum current is fed from the long-term energy storage device into the coupling circuit through the DC / DC switching regulator, - when the voltage at the input of the coupling circuit is below the nominal voltage but within a specified nominal voltage range, a current up to a maximum of a first reverse maximum current flows through the DC / DC switching regulator to the long-term energy storage device, - when the voltage at the input of the coupling circuit is within a first voltage range above a predetermined nominal voltage range, a current up to a maximum of a second forward maximum current, which is greater than the first forward maximum current, is fed from the long-term energy storage device into the coupling circuit by the DC / DC switching regulator, and - when the voltage at the input of the coupling circuit is within a second voltage range below a predetermined nominal voltage range, a current up to a maximum of a second reverse maximum current, which is greater than the first reverse maximum current, flows through the DC / DC switching regulator to the long-term energy storage device.

[0017] The method according to the invention uses a long-term energy storage device, for example, a battery, and a short-term energy storage device, for example, a capacitor. A current-controlled, bidirectional DC / DC switching regulator is connected between the two. The long-term energy storage device supplies the DC / DC switching regulator and, via this, the actuator with a coupling circuit, for example, a motor with an inverter circuit. The actuator is supplied from the long-term energy storage device with a nominal voltage designed for its normal operation.

[0018] A voltage regulator is superimposed on the current-controlled DC / DC switching regulator. According to a nonlinear regulator function, this voltage regulator sets the setpoint for the current-controlled, bidirectional DC / DC switching regulator.

[0019] According to one aspect of the invention, it is provided that the non-linear control function connected upstream of the PI controller is continuous and has a positive slope, wherein the slope of the characteristic curve for voltages at the input of the coupling circuit above and below the nominal voltage is up to ten times to a thousand times greater than the slope of the characteristic curve for voltages at the input of the coupling circuit in the normal voltage range.

[0020] According to the inventive concept, the target value for the current regulator of the DC / DC switching regulator is controlled via a PI controller with an upstream non-linear function, depending on the difference between the current voltage at the actuator or at the actuator's coupling circuit and the nominal voltage. If the difference is small (both negative and positive), the PI controller is only weakly controlled and the current flow through the DC / DC switching regulator remains approximately constant. However, with larger voltage differences, the PI controller is more strongly controlled and the current setpoint is preferably increased sharply, preferably suddenly, so that the necessary energy is either drawn from the long-term storage or stored in the long-term storage during recuperation.The short-term storage device is not designed for such high energy requirements; moreover, it would be damaged (degeneration of a capacitor normally used as a short-term storage device).

[0021] Preferably, the short-term energy storage device is designed to be energetically large enough that, in nominal operation, the energy circulating during acceleration and recuperation can be completely temporarily stored in the short-term energy storage device and thus the voltage at the actuator never leaves the nominal voltage range, which then leads to an almost constant current from the long-term energy storage device due to the inventive concept.

[0022] According to the invention, the DC / DC switching regulator operates in different operating modes, either at output voltages within the nominal voltage range or at output voltages either above or below the nominal voltage range. The modes in which the DC / DC switching regulator operates can be monitored. The frequency with which the DC / DC switching regulator switches between the individual modes can provide information about the condition of the components. For example, various error messages can be output indicating that components are degrading, that the switching regulator is not designed for the currently connected actuator system, or that this actuator system has changed its properties (e.g., due to wear). The diagnostic options are manifold.What is crucial is that the frequency with which the DC / DC switching regulator operates in the various modes can be used to determine whether the recuperating system or the electrical system is faulty, incorrectly designed, or similar.

[0023] Further advantageous embodiments and aspects of the invention are the subject of the subclaims.

[0024] The invention therefore proposes, in essence, to regulate the deviation of the actual voltage from the nominal voltage using a controller preceded by a nonlinear function. This can also be referred to as a multiplicative upstream controller function, in which the control deviation is processed according to a nonlinear function, and the resulting value is fed to the controller as the control deviation.

[0025] The invention is explained in more detail below using an exemplary embodiment and with reference to the drawings. In detail: Fig. 1 a circuit diagram of a conventional configuration of a recuperative system with a motor, a switching regulator and a battery, Fig. 2 the basic structure of a DC / DC switching regulator usable according to the invention, here in its design as a current-mode buck converter with voltage-controlled current regulator, Fig. 3 the structure of a recuperative system operating according to the invention with a voltage-controlled current limiter as a default for the current regulator of the DC / DC switching regulator, Fig. 4 a graphical representation of the course of the non-linear controller function that can be used according to the invention and Fig. 5 two diagrams showing the current and voltage curves when considering different operating scenarios of the recuperating system according to Fig. 3 (with non-linear controller function according to Fig. 4) show.

[0026] In the following, the technical implementations which enable the above-mentioned properties of the recuperative system 10 according to the invention according to an embodiment will now be explained.

[0027] The following systems are particularly suitable for the switching regulator topology, provided they are designed with synchronous rectification: - Boost converter - Buck converter - Buck-boost converter

[0028] To enable precise implementation of the current limits adjustable according to the invention, the switching regulator 12 must have a current control loop 14, in which the pulse width of the voltage at the coil (inductance 16) of the switching regulator 12 is controlled based on an external specification such that an average current is established according to the specification. Systems that can continuously measure the coil current, i.e., have a shunt resistor, a magnetic current sensor, or another current measuring device in series with the inductance 16 (for example, as shown in Fig. 2). Reversing the current is also easier to implement than in systems with peak measurement and slope compensation.

[0029] The special feature of the switching regulator 12 lies in the design of its control system. This must ensure that when the maximum voltage U maxor falling below the minimum voltage U min hard adjustment is made using the predefined current limits to prevent the voltage from leaving the permitted range (U nom -range). Nevertheless, only slight adjustment is allowed in the range between minimum and maximum voltage to allow the desired fluctuation of the DC circuit in this range, so that the circulating power is drawn predominantly from capacitors 18, 20. Likewise, the control must be able to adapt to the average current flow in order to keep the output voltage at the nominal voltage on average.

[0030] To achieve this functionality, a topology according to Fig. 3 is suggested. First, the measured output voltage U A of the nominal voltage U nomand the control deviation thus determined is subjected to a non-linear function. The result of this function is then applied to a voltage regulator 22 (e.g. PI controller 23 - if necessary with overflow limitation of the I component to I min and I max) and its output, after being limited to the currents permissible for the long-term energy storage device, is used as the control input for the current regulator 24 of the current control loop 14 (see 25). It should be noted that because the voltage at the long-term energy storage device varies with the state of charge, an output current of the DC / DC switching regulator results in different currents from the long-term energy storage device. Therefore, for the upper and lower limits of the current input, either values must be selected that are valid for all charge states of the long-term energy storage device, or the values are adaptively adjusted to the current voltage at the long-term energy storage device, which, however, usually results in an undesirable dependence of the system performance on the charge state of the long-term energy storage device. The additional implementation of a differential controller component is also possible to improve stability (PID instead of PI controller is therefore possible).The current regulator 24 can be designed according to the state of the art.

[0031] In addition to the switching regulator 12 designed according to the invention, the recuperating system 10 comprises a long-term energy storage device 26 (in this exemplary embodiment in the form of a battery 28), a short-term energy storage device 30 (in this exemplary embodiment as a capacitor 32), a coupling circuit 34 (in this exemplary embodiment an inverter circuit 36), and the actual actuator 38, for example, as a motor 40. Instead of the additional capacitor 32, the capacitor 18 of the switching regulator 12 can also be used as the short-term energy storage device 30. If an additional capacitor 32 is provided, both capacitors 18 and 32 ultimately form the short-term energy storage device 30.

[0032] The non-linear function used in the controller (in Fig. 3 shown at 42, see also Fig.4) is continuous. It has a positive slope over the entire curve and shows a positive slope for voltages between (U min - U nom ) and (U max -U nom ) (nominal voltage range) and a steep curve for voltages outside this range. Depending on the dimensioning of the PI controller 23, these section-wise gradients of the controller function are in the range of 0.1 to 10 for the flat part and in the range above 100 for the steep sections of the curve.

[0033] The transitions between the areas can be abrupt or smooth.

[0034] An implementation of the controller topology according to Fig.3, including the nonlinear function, is possible in both digital and analog formats. It is particularly advantageous if the current regulator 24 is constructed using analog circuitry, as it must have a high bandwidth to maintain stable current regulation at low inductances and high switching frequencies. The slower, higher-level voltage regulator 23 is implemented digitally to enable simpler parameterization and adaptation to the system, since—in contrast to conventional power supplies—more than just one parameter per power supply needs to be configured.

[0035] Fig. Figure 5 shows the voltage and current curves for an exemplary design that feeds a system with a recuperation period of 1 s, where the load consumes an average of 2 A and can produce load peaks of up to -3 and up to +7 A. Let a U nom of 12V, a U max of 13V and a U minof 11V. The capacitance of the buffer capacitor is 1F. The curve in the lower diagram shows the voltage across the DC circuit. In the upper diagram, the solid line shows the current during the periods when it flows from the switching regulator, while the dashed line shows the current during the periods when the load current flows.

[0036] The left part of the curves shows the charging of the short-term storage capacitor (capacitor 18 with additional capacitor 32) with a maximum coil current of 10 A. After charging, the voltage remains at U maxlimited and slowly decreases due to the now slowly acting I-component of the regulator (which ran up when the regulator was switched on). After approximately 5 seconds, the system's pulsed load current consumption begins, and the voltage at capacitor 32 fluctuates within the specified range. The current ripple, which is drawn from battery 28, remains small. After approximately 15 seconds, a current peak occurs as a disturbance variable, which exceeds the intended range of the capacitor design, and the DC circuit threatens to fall below U min to fall, but this is intercepted by the switching regulator 12 by drawing strong current from the battery 28. Likewise, an overshoot during the subsequent feedback is almost completely intercepted, whereby the maximum feedback current of 5A into the battery 28 is not exceeded, which is why the DC circuit maintains the voltage U maxThis type of overshoot can be compensated for with an additional unit, such as a so-called brake chopper. This can also be controlled from the power supply if the maximum regenerative current is exceeded. After this disturbance, the power supply requires a few cycles to find the optimal setting again.

[0037] If it is known whether the pulsating cycle begins with absorbed or regenerated power, a nominal voltage close to U can be achieved at the beginning and while maintaining maximum and minimum voltage. max or U min be commanded in order to achieve a faster regulation at start-up and then during the current cycle U nom to set to a medium value. Monitoring functions

[0038] The switching regulator 12, with its control characteristics and the short-term energy storage (capacitor 18 and / or 32), forms a tuned system. This should initially be dimensioned so that the positive and negative peaks after Fig.5 should not normally occur, as this can cause undesired feedback into the battery and brief over- or undervoltage. For system optimization and troubleshooting, the control of the overall system can record these events and prepare them for extended use. On the one hand, it can be checked during normal operation whether the system design was selected appropriately. Under normal conditions, the edge ranges of the switching regulator 12 should only be reached very rarely. A short-term energy storage device that is too small (capacitor 18 and / or 32), for example, leads to the system voltage reaching its limits more often than expected. The monitoring also serves to detect whether changes occur during operation. If, for example, a different load profile of the actuator 38 is used compared to the basic design, this can also be recognized from the reactions of the switching regulator 12.This allows, for example, aging or a future defect in downstream systems to be detected early. The aging of components and elements of the circuit itself can also be diagnosed, for example, if the capacity of the short-term energy storage device has decreased due to various influences and effects during operation. In this way, the switching regulator 12 can issue warnings before a complete system failure occurs, leading to greater reliability. The following monitoring information, for example, is obtained from the recorded system parameters: - Percentage time ratio over a moving average between normal operation, upper limit operation and lower limit operation (i.e., how long has the controller been operating outside of normal operation recently?) - Percentage time ratio over the entire operating time between normal operation, operation at the upper limit and operation at the lower limit (i.e., how long does the controller operate outside of normal operation on average?) - Number of rising edges per time unit over a moving average in the switching range between normal operation and operation in the upper limit (i.e., how often is the nominal case exited? This is relevant to know if the nominal range is exited frequently, but always only for very short periods.) - Number of falling edges per time unit over a moving average in the switching range between normal operation and operation in the lower limit - Number of rising edges per time unit over the entire operating time in the switching range between normal operation and operation in the upper limit - Number of falling edges per time unit over the entire operating time in the switching range between normal operation and operation in the lower limit Connection of the energy storage via a separate switching regulator

[0039] If the permissible swing on the DC circuit is small, the energy stored in the capacitor array using the topology presented so far (which has the advantage of low complexity) can also be small. Instead of increasing the array's capacitance, an additional switching regulator can be inserted, which artificially increases the swing on the capacitor, as described, among others, in O. Bomboir et al.'s "Little Box Challenge: Technical Approach Document," https: / / littleboxchallenge.com / pdf / finalists / 56568-Tech.pdf.

[0040] This is particularly interesting for systems that don't offer enough space for the capacitors otherwise required, as the regulator creates additional losses. To connect a corresponding energy storage device for the proposed system via a switching regulator, a similar topology is used as the one already proposed for the system. The capacitor bank is now connected via a boost converter, a buck converter, or a buck converter.

[0041] The use of a current-controlled power supply is again proposed, in which the coil current is pre-controlled by means of a P-controller depending on the DC circuit voltage and the capacitor voltage according to the following equation. iCAP=(uDC−UminUmax−Umin−uC2−UCmin2UCmax2−UCmin2)⋅G

[0042] U max and U min again the maximum and minimum voltages permitted on the DC bus, u DCis the current voltage on the bus, u C is the current voltage across the capacitor, U Cmax and U Cmin represent the maximum desired or permissible capacitor voltage (very small voltages on the capacitor no longer allow sufficient power consumption) and G is the slope factor of the P-controller.

[0043] A mandatory current limit to the maximum current the circuit can carry and, if necessary, overcharge protection for the capacitor must also be implemented. If aluminum electrolytic capacitors are used, it is recommended to design for the highest possible voltages, since the energy density increases with increasing voltage for the same design. The following table shows, as an example, the maximum available (nominal) capacitance of commercially available cylindrical capacitors with a diameter of 30 mm and a height of approximately 50 mm. Nominal voltage nominal capacity Energy content 16V 47mF 6J 25V 33mF 10J 35V 22mF 13J 50V 15mF 19J 63V 12mF 24J 80V 6.8mF 22J 100V 4.7mF 24J 160V 2.2mF 28J 180V 2.2mF 36J 200V 2.2mF 44J 250V 1.5mF 47J 350V 820µF 50J 400V 820µF 66J

[0044] The situation is similar with ceramic capacitors, as shown in the following table with capacitors of the 1812 format and X7R or X7S dielectric. The energy values are for comparison purposes only. Since the capacitance of ceramic capacitors drops sharply with voltage, the actual energy content is significantly lower. Nominal voltage nominal capacity Energy content 16V 33µF 4mJ 25V 22µF 7mJ 50V 6,8µF 9mJ 100V 4,7µF 24mJ 250V 1µF 31mJ 500V 0,47µF 59mJ

[0045] The volume capacity currently speaks in favor of electrolytic capacitors (0.720µF / mm 3 for the ceramic capacitor with 16V compared to 1.33µF / mm 3 for the 16V electrolytic capacitor). Likewise, the price per capacitance of aluminum electrolytic capacitors is significantly lower.

[0046] Double-layer capacitors are unbeatable in terms of capacitance per volume or weight. For comparison: Maxwell's BCAP0310 series, with acceptable drawable power, is 21 J / cm 3 compared to the above electrolytic capacitors with 1.9J / cm 3 (for the 400V type) LIST OF REFERENCE SYMBOLS 10 systems 12 switching regulators 14 Current control loop 16 Inductance 18 Filter capacitor 20 filter capacitor 22 voltage regulators 23 higher-level voltage regulator 24 current regulators 25 Current limit 26 long-term energy storage 28 battery 30 short-term energy storage 32 Short-term storage capacitor 34 Coupling circuit 38 Actuator 40 engine 42 Current limit 42 Controller function

Claims

[1] Method for the energy management of an electrically driven actuator, which is to be supplied from a long-term energy storage device with a nominal voltage designed for normal operation and which is coupled to a mechanical component, the normal operation of which comprises alternating acceleration and braking phases, possibly with standstill phases between one braking phase and the next acceleration phase or vice versa, in particular for the energy management of a preferably mobile robot application, wherein in the method - an electrical system is provided which is equipped with - a long-term energy storage device (26), in particular a battery-based long-term energy storage device (26), - a short-term energy storage device (30), in particular a capacitive short-term energy storage device (30), - a bidirectional DC / DC switching regulator (12) having a current regulator (24) which is connected between the two energy stores, and - a coupling circuit (34) having an input connected to the short-term energy storage device (30) and an output connected to the actuator (38), wherein the coupling circuit (34) may be a component of the actuator (38), characterized by , that - the magnitude of the voltage at the input of the coupling circuit (34) is determined, - it is examined whether the voltage at the input of the coupling circuit (34) lies in a first voltage range below a predetermined minimum value or in a second voltage range above a predetermined maximum value or in a nominal voltage range designed for normal operation of the actuator (38), which lies between the minimum value and the maximum value and contains the value for the nominal voltage, and - by means of a PI controller with a multiplicatively connected non-linear function with a positive slope, the setpoint value for the current controller (24) of the DC / DC switching controller (12) is specified as a function of the difference between the voltage at the input of the coupling circuit (34) and the nominal voltage, wherein - the slope of the non-linear function is small when the voltage at the input of the coupling circuit (34) is within the nominal voltage range, - the slope of the non-linear function is large when the voltage at the input of the coupling circuit (34) is outside the nominal voltage range, and - the current specification generated by the PI controller for the current-controlled DC / DC converter is limited to an upper and lower maximum current in such a way that an acceptable current is achieved for the long-term energy storage device under all charging states. [2] Method for the energy management of an electrically driven actuator, which is to be supplied from a long-term energy storage device with a nominal voltage designed for normal operation and which is coupled to a mechanical component, the normal operation of which comprises alternating acceleration and braking phases, possibly with standstill phases between one braking phase and the next acceleration phase or vice versa, in particular for the energy management of a preferably mobile robot application, wherein in the method - an electrical system is provided which is equipped with - a long-term energy storage device (26), in particular a battery-based long-term energy storage device (26), - a short-term energy storage device (30), in particular a capacitive short-term energy storage device (30), - a bidirectional DC / DC switching regulator (12) having a current regulator (24) which is connected between the two energy stores, and - a coupling circuit (34) having an input connected to the short-term energy storage device (30) and an output connected to the actuator (38), wherein the coupling circuit (34) may be a component of the actuator (38), characterized by , that - the magnitude of the voltage at the input of the coupling circuit (34) is determined, - it is examined whether the voltage at the input of the coupling circuit (34) lies in a first voltage range below a predetermined minimum value or in a second voltage range above a predetermined maximum value or in a nominal voltage range designed for normal operation of the actuator (38), which lies between the minimum value and the maximum value and the value for the nominal voltage, and - the setpoint value for the current regulator (24) of the DC / DC switching regulator (12) is specified as a function of the difference between the voltage at the input of the coupling circuit (34) and the nominal voltage according to a non-linear regulator function, by - when the voltage at the input of the coupling circuit (34) is above the nominal voltage but within the nominal voltage range, a current up to a maximum of a first forward maximum current is fed from the long-term energy storage device (26) through the DC / DC switching regulator (12) into the coupling circuit (34), - when the voltage at the input of the coupling circuit (34) is below the nominal voltage but within the nominal voltage range, a current up to a maximum of a first reverse maximum current flows through the DC / DC switching regulator (12) to the long-term energy storage device (26), - when the voltage at the input of the coupling circuit (34) is within the first voltage range, a current up to a maximum of a second forward maximum current, which is greater than the first forward maximum current, is fed from the long-term energy storage device (26) into the coupling circuit (34) through the DC / DC switching regulator, and - when the voltage at the input of the coupling circuit (34) is within the second voltage range, a current up to a maximum of a second reverse maximum current, which is greater than the first reverse maximum current, flows through the DC / DC switching regulator (12) to the long-term energy storage device (26). [3] Method according to claim 2, characterized by that the second forward maximum current is up to ten to a thousand times greater than the first forward maximum current. [4] Method according to claim 2 or 3, characterized bythat the second reverse maximum current is up to ten to a thousand times greater than the first reverse maximum current. [5] Method according to one of claims 2 to 4, characterized by that the non-linear control function is continuous and has a positive gradient, wherein the gradient of the characteristic curve for voltages at the input of the coupling circuit (34) in the first or second voltage range is up to ten times to a thousand times greater than the gradient of the characteristic curve for voltages at the input of the coupling circuit (34) in the normal voltage range. [6] Method according to one of claims 1 to 5, characterized by that the coupling circuit (34) is an inverter circuit. [7] Method according to one of claims 1 to 6, characterized bythat over a predeterminable observation period it is detected whether the frequency of the deviation of the voltage at the input of the coupling circuit (34) from the nominal voltage range exceeds a predeterminable threshold value, and that an error message is output if the threshold value is exceeded. [8] Method according to claim 7, characterized bythat over a predeterminable observation period it is recorded how often the voltage at the input of the coupling circuit (34) is in the first voltage range and / or in the second voltage range in relation to the normal voltage range, and that if the frequency with which the voltage at the input of the coupling circuit (34) is in the first voltage range exceeds a first threshold value, a first error message is output and / or if the frequency with which the voltage at the input of the coupling circuit (34) is in the second voltage range exceeds a second threshold value, a second error message is output. [9] Device for the energy management of an electrically driven actuator (38) to be supplied from a long-term energy storage device (26) with a nominal voltage designed for normal operation, which actuator is coupled to a mechanical component whose normal operation comprises alternating acceleration and braking phases, optionally with standstill phases between one braking phase and the next acceleration phase or vice versa, in particular for the energy management of a preferably mobile robot application, wherein the device is provided with - a long-term energy storage device (26), in particular a battery-based long-term energy storage device (26), - a short-term energy storage device (30), in particular a capacitive short-term energy storage device (30), - a bidirectional DC / DC switching regulator (12) having a current regulator (24) which is connected between the two energy stores, and - an electrical coupling circuit (34) having an input connected to the short-term energy storage device (30) and an output connected to the actuator (38), wherein the coupling circuit (34) may be a component of the actuator (38), characterized by - a voltage regulator (22) with a PI controller and a pre-connected non-linear function, to which the voltage difference between the input of the coupling circuit (34) and the nominal voltage can be supplied and which predetermines a setpoint for the current regulator (24) as a function of the voltage difference in accordance with its control behavior and the pre-connected non-linear function, in that - when the voltage at the input of the coupling circuit (34) is within a predetermined nominal voltage range, the regulator is weakly controlled, - when the voltage at the input of the coupling circuit (34) is within a predetermined nominal voltage range, the current specification for the DC / DC converter is limited to a value permissible for the long-term energy storage device. [10] Device for the energy management of an electrically driven actuator (38) to be supplied from a long-term energy storage device (26) with a nominal voltage designed for normal operation, which actuator is coupled to a mechanical component whose normal operation comprises alternating acceleration and braking phases, optionally with standstill phases between one braking phase and the next acceleration phase or vice versa, in particular for the energy management of a preferably mobile robot application, wherein the device is provided with - a long-term energy storage device (26), in particular a battery-based long-term energy storage device (26), - a short-term energy storage device (30), in particular a capacitive short-term energy storage device (30), - a bidirectional DC / DC switching regulator (12) having a current regulator (24) which is connected between the two energy stores, and - an electrical coupling circuit (34) having an input connected to the short-term energy storage device (30) and an output connected to the actuator (38), wherein the coupling circuit (34) may be a component of the actuator (38), characterized by - a voltage regulator (22) with a non-linear control function, to which the voltage difference between the input of the coupling circuit (34) and the nominal voltage can be fed and which prescribes a setpoint for the current regulator (24) as a function of the voltage difference according to the non-linear control function, in that - when the voltage at the input of the coupling circuit (34) is above the nominal voltage but within a predetermined nominal voltage range, a current up to a maximum of a first forward maximum current is fed from the long-term energy storage device through the DC / DC switching regulator (12) into the coupling circuit (34), - when the voltage at the input of the coupling circuit (34) is below the nominal voltage but within a predetermined nominal voltage range, a current up to a maximum of a first reverse maximum current flows through the DC / DC switching regulator (12) to the long-term energy storage device, - when the voltage at the input of the coupling circuit (34) is within a first voltage range above a predetermined nominal voltage range, a current up to a maximum of a second forward maximum current, which is greater than the first forward maximum current, is fed from the long-term energy store (26) into the coupling circuit (34) through the DC / DC switching regulator (12), and - when the voltage at the input of the coupling circuit (34) is within a second voltage range below a predetermined nominal voltage range, a current up to a maximum of a second reverse maximum current, which is greater than the first reverse maximum current, flows through the DC / DC switching regulator (12) to the long-term energy store (26). [11] Device according to claim 10, characterized bythat the non-linear control function is continuous and has a positive gradient, wherein the gradient of the characteristic curve for voltages at the input of the coupling circuit (34) in the first or second voltage range is up to ten times to a thousand times greater than the gradient of the characteristic curve for voltages at the input of the coupling circuit (34) in the normal voltage range. [12] Device according to claim 10 or 11, characterized by that the second forward maximum current is up to ten to a thousand times greater than the first forward maximum current. [13] Device according to one of claims 10 to 12, characterized by that the second reverse maximum current is up to ten to a thousand times greater than the first reverse maximum current. [14] Device according to one of claims 9 to 12, characterized by that the coupling circuit (34) is an inverter circuit.

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