Electrical circuit for controlling a power supply device in an electrical device and electrical device
Patent Information
- Application Number
- EP2023725174
- Authority / Receiving Office
- EP · EP
- Patent Type
- Applications
- Current Assignee / Owner
- Priority Date
- 2022-05-18
- Filing Date
- 2023-05-04
- Publication Date
- 2025-03-26
AI Technical Summary
Machine tools equipped with multiple power supply devices face issues when the state of charge (SOC) of these devices is uneven, leading to reduced performance and the need to stop work when one device is completely discharged, as the power available is determined by the device with the lowest SOC, even if other devices have remaining charge.
An electrical circuit with a coil and switching elements that allows for charge balancing and voltage boosting by connecting the coil in series with two energy supply devices, enabling unequal switch-on times to equalize SOC and provide a higher output voltage than the sum of individual voltages, allowing for dynamic energy extraction control.
The circuit effectively balances charge between energy supply devices, extends the machine tool's runtime by utilizing all stored energy, and provides a higher output voltage, ensuring consistent performance despite varying charge states.
Smart Images
Figure 1.1
Abstract
Description
[0001] ELECTRICAL CIRCUIT FOR CONTROLLING POWER SUPPLY DEVICE IN AN ELECTRICAL DEVICE AND ELECTRICAL DEVICE
[0002] The invention relates to an electrical circuit for controlling energy extraction from a first energy supply device and from a second energy supply device in an electrical device, in particular in a machine tool. The electrical circuit comprises a first energy supply device and a second energy supply device, as well as a first switching element, a second switching element and a third switching element, a coil, and two connection points. The coil is connected in series with the first energy supply device and the second energy supply device, and the first switching element is configured to bridge the first energy supply device and the coil, and the second switching element is configured to bridge the second energy supply device and the coil.In this case, an output voltage U_B of the electrical circuit, which is present at the connection points, is greater than the sum of the first voltage U1 of the first power supply device and the second voltage U2 of the second power supply device. The electrical circuit advantageously makes it possible to provide an output voltage that is greater than the sum of the voltages of the two power supply devices. In a second aspect, the invention relates to an electrical device, preferably a machine tool, with such an electrical circuit.
[0003] Background of the invention:
[0004] Electrical devices, such as machine tools, are known in the art and can be used to perform various tasks. Examples include hammer drills, chiseling tools, cut-off or angle grinders, screwdrivers, or core drills, each of which has a tool driven by a motor. Power can be provided via a mains connection or with power supply devices, batteries, or accumulators ("rechargeable batteries").
[0005] There are a number of known applications for such machine tools where high power levels are required to perform the corresponding work. For machine tools whose power supply is provided by a power supply device, it can happen that the power required for the work exceeds the maximum possible output of the power supply device. To meet this challenge, such machine tools are often equipped with an interface for two power supply devices, enabling the desired power to be provided by two power supply devices that can be connected in series.
[0006] However, when working with tools with two or more power supplies, the following problem can arise: situations can arise in which the state of charge (SOC) of the power supplies is not the same. A similar situation can also arise when different types of power supplies are used, for example a 5 ampere-hour (Ah) power supply and a 10 Ah power supply. If, for example, one of the power supplies is fully or partially discharged, the machine tool cannot deliver full power for the entire working period. Once one of the power supplies is fully discharged, no further power can be drawn from that power supply when the power supplies are connected in series.Work with the machine tool must then be stopped, despite any residual charge that may be present in the other power supply device.
[0007] In particular, the energy or power available for working with the machine tool is determined by the smallest amount of charge contained in one of the power supply devices when multiple power supply devices are used. In other words, the power supply device with the lowest SOC value determines the power available for the machine tool and the range at which work can be performed with the machine tool.
[0008] The object of the present invention is to overcome the above-described deficiencies and disadvantages of the prior art and to provide an improved electrical device and an electrical circuit for controlling energy extraction from a first energy supply device and from a second energy supply device in an electrical device, in particular in a machine tool, with which the energy extraction from the individual energy supply devices can be controlled differently.
[0009] The object is achieved by the subject matter of the independent claims. Advantageous embodiments of the subject matter of the invention are described in the dependent claims. Description of the invention:
[0010] The object is achieved in a first aspect by an electrical circuit for controlling energy extraction from a first energy supply device and from a second energy supply device in an electrical device, in particular in a machine tool. The electrical circuit comprises a first energy supply device and a second energy supply device, as well as a first switching element, a second switching element and a third switching element, a coil, and two connection points. The coil is connected in series with the first energy supply device and the second energy supply device, and the first switching element is configured to bridge the first energy supply device and the coil, while the second switching element is configured to bridge the second energy supply device and the coil.In this case, an output voltage U_B of the electrical circuit, which is applied to the connection points, is greater than a sum of the first voltage U1 of the first energy supply device and the second voltage U2 of the second energy supply device.
[0011] The proposed electrical circuit is advantageously capable of balancing charges between the power supply devices when the switching elements are switched accordingly.
[0012] By closing the first switching element, the coil is charged with electrical energy from the first energy supply device. The amount of energy or charge increases essentially proportionally with the charging time t. Similarly, by closing the second switching element, the coil is charged with electrical energy from the second energy supply device. Here, too, the amount of energy or charge increases essentially proportionally with the charging time t. If the first and second switching elements are closed, the electrical energy stored in the coil can be discharged into the load circuit by closing the third switching element.Since the ratio of the switch-on times of the first and second switching elements preferably controls the discharge amount of the first and second energy supply devices, the charge state of the two energy supply devices can be equalized via unequal switch-on times and / or unequal discharge.
[0013] The electrical circuit is furthermore capable of boosting an output voltage U_B of the electrical circuit, which is preferably present at the connection points of the electrical circuit, or of increasing it to a value that is greater than the sum of the voltages of the two energy supply devices. The proposed circuit can preferably also be referred to as a "boost circuit" within the meaning of the invention, wherein the ability to boost the voltage within the proposed circuit is brought about in particular by the coil and its arrangement within the proposed circuit. The coil is arranged in series with the energy supply devices. The invention thus relates in particular to a boost converter for two energy supply devices with a charge balancing function, wherein the energy supply devices are preferably arranged in an electrical device, for example in a machine tool.The equalization of charges between energy supply devices or between the cells of an energy supply device is preferably referred to as “balancing” in the sense of the invention.
[0014] The invention makes it possible, in particular, to control the energy extraction from the energy supply devices in different ways. Within the meaning of the invention, this preferably means that different amounts of energy can be extracted from the energy supply devices per unit of time. This advantageously also makes it possible to compensate for different charge states in the energy supply devices in the sense of "balancing." Advantageously, this allows for better utilization of the energy or charge present or stored in the energy supply devices by making the energy and / or charge available to the electrical device at a higher voltage.
[0015] By arranging the coil between the two power supply devices and the two switching elements, it is possible to dynamically adjust and thus control the charging time of the coil. The inventor has recognized that the charging time of the coil essentially corresponds to the energy drawn from the power supply devices. By being able to adjust the charging time of the coil, the energy drawn from the power supply devices of the electrical circuit or electrical device can also be adjusted or controlled. In this way, it is possible to load the two power supply devices differently or to draw different amounts of electrical energy. The first and second switching elements can preferably be designed as MOS-FETs.It is preferred within the meaning of the invention that the first and second switching elements can each bridge a power supply device and the coil, so that the charging time of the coil can be changed or adjusted. Preferably, the coil within the meaning of the invention is also referred to as an "inductance," wherein the coil is particularly designed to be charged with electrical current. By varying the charging times of the coil, the power supply devices of the electrical circuit can advantageously be loaded differently, i.e., different amounts of electrical energy can be drawn from the power supply devices.
[0016] It is preferred in the sense of the invention that the electrical circuit is designed to load the two energy supply devices differently and thereby equalize the charge state.
[0017] The ability to increase the output voltage U_B of the electrical circuit is due in particular to the fact that the coil is connected in series with the first power supply device and the second power supply device and to the fact that the first switching element is configured to bridge the first power supply device and the coil, while the second switching element is configured to bridge the second power supply device and the coil.
[0018] Within the meaning of the invention, it is preferred that the third switching element is configured to switch a state of the electrical circuit on or off, wherein in this state an output voltage U_B of the electrical circuit, which is applied to the connection points, is greater than a sum of the first voltage U1 of the first energy supply device and the second voltage U2 of the second energy supply device. The wording "greater than" includes the wording "greater than or equal to" within the meaning of the invention, so that the wording that an output voltage U_B of the electrical circuit, which is applied to the connection points, is greater than a sum of the first voltage U1 and the second voltage U2, can preferably also mean that the output voltage U_B corresponds to the sum U1 + U2 of the voltage of the two energy supply devices.In other words, the output voltage U_B of the electrical circuit applied to the connection points can be greater than or equal to the sum of the first voltage U1 of the first energy supply device and the second voltage U2 of the second energy supply device. This state is preferably also referred to as the “boost state” within the meaning of the invention. The third switching element is preferably designed to function as a boost switching element or boost diode. The increase in the output voltage U_B to a value that is greater than the sum of the voltages of the two energy supply devices is referred to as a “boost” within the meaning of the invention. The first energy supply device is preferably designed to provide the first voltage U1, while the second energy supply device is designed to provide the second voltage U2.The advantageous design of the proposed electrical circuit makes it possible to provide an output voltage U_B that is greater than the sum of the individual voltages. In this boost state, the following relation applies.
[0019] U_B > U1 + U2.
[0020] According to the invention, it is preferred that the first switching element and / or the second switching element is / are embodied as a metal oxide semiconductor field-effect transistor (MOSFET). The first switching element and / or the second switching element can preferably also be embodied as a field-effect transistor (FET) or an insulated gate bipolar transistor (IGBT). The third switching element can preferably be embodied as a diode. However, the third switching element can also be embodied as a MOSFET, as shown in the figures.
[0021] In a second aspect, the invention relates to an electrical device, in particular a machine tool, wherein the electrical device comprises a proposed electrical circuit. The definitions, technical effects, and advantages described for the electrical circuit apply analogously to the electrical device. The electrical device has, in particular, two energy supply devices, which can also be part of the electrical circuit. With the invention, the charge or electrical energy available in the energy supply devices can be utilized to a greater extent for the electrical device, so that the energy contained in the energy supply devices can be utilized better than in conventional electrical devices as known from the prior art.
[0022] It is preferred within the meaning of the invention that the energy supply devices whose charge levels are to be equalized have the same or substantially the same nominal voltages. However, it may also be preferred within the meaning of the invention that the energy supply devices have different nominal voltages. For example, in the context of the present invention, two different energy supply devices with voltages of 12 V and 36 V can be present together in a machine tool. With such combinations of energy supply devices with different equalization voltages, the aim can be for the energy supply devices to have the same or substantially the same charge levels after the equalization process. However, it may also be preferred for the charge levels to merely equalize.In the context of the invention, the term "equalize" preferably means that a difference in the charge levels between the energy supply devices is reduced. In the context of the invention, it is preferred that the power to be provided by the invention corresponds to the sum of the individual powers of the two energy supply devices.
[0023] The invention allows the entire energy stored in the power supply devices to be converted and used to operate the machine tool. This advantageously extends the operating time of the machine tool without the need to replace or recharge the power supply devices.
[0024] Further advantages will become apparent from the following description of the figures. The figures illustrate an exemplary embodiment of the present invention. The figures, the description, and the claims contain numerous features in combination. Those skilled in the art will also expediently consider the features individually and combine them into useful further combinations.
[0025] In the figures, identical and similar components are numbered with the same reference numerals.
[0026] It shows:
[0027] Fig. 1 schematic representation of an embodiment of the electrical circuit
[0028] Fig. 2 schematic representation of an embodiment of the electrical circuit
[0029] Implementation examples and figure descriptions:
[0030] Fig. 1 shows an exemplary embodiment of the proposed electrical circuit 10.
[0031] The electrical circuit 10 has a first power supply device 16 and a second power supply device 18, as well as a coil 26. In addition, the electrical circuit 10 comprises a first switching element 22, a second switching element 24, and a third switching element 28.
[0032] The proposed electrical circuit 10 can be described using an upper half 40 and a lower half 42. These halves 40, 42 of the electrical circuit 10 are represented in Figure 1 by the rectangles with dashed side lines. The upper half 40 and the lower half 42 of the electrical circuit 10 are separated from each other by the coil 26, wherein the coil 26 is arranged in series with the energy supply devices 16, 18 of the electrical circuit 10. Each of the two halves 40, 42 of the electrical circuit 10 comprises a energy supply device 16, 18 and a switching element 22, 24. For example, the upper half 40 of the electrical circuit 10 can comprise the first energy supply device 16 and the first switching element 22, wherein the first energy supply device 16 and the first switching element 22 are connected to each other via the coil 26 and an electrical line 20.In this case, the electrical line 20 is arranged in particular between the positive pole "+" of the first energy supply device 16 and the first switching element 22, while the coil 26 is arranged between the negative pole of the first energy supply device 16 and the first switching element 22. On the other side of the electrical circuit 10, the lower half 42 of the electrical circuit 10 can comprise the second energy supply device 18 and the second switching element 24, wherein the second energy supply device 18 and the second switching element 24 are connected to one another via the coil 26 and an electrical line 20. In this case, the electrical line 20 is arranged in particular between the negative pole of the second energy supply device 18 and the second switching element 24, while the coil 26 is arranged between the positive pole "+" of the second energy supply device 18 and the second switching element 24.
[0033] The upper half 40 and the lower half 42 of the electrical circuit 10 are separated from one another by the coil 26. The third switching element 28 can be arranged either in the upper half 40 or in the lower half 42 of the electrical circuit 10. In the exemplary embodiment of the invention shown in the figures, the third switching element 28 is arranged in the upper half 42 of the electrical circuit 10. The proposed electrical circuit 10 can also be described as being composed of a front branch 50 and a rear branch 52. These branches 50, 52 of the electrical circuit 10 are represented in Figure 2 by the rectangles with the dashed side lines. The front branch 50 of the electrical circuit 10 comprises the first energy supply device 16 and the second switching element 24, while the rear branch 52 comprises the second energy supply device 18 and the first switching element 22.The coil 26 is arranged between the two strands 50, 52 and separates the strands 50, 52 of the electrical circuit 10 from each other. The first power supply device 16 and the first switching element 22 are located on the top side 40 of the electrical circuit 10, i.e., above the coil 26, while the second power supply device 18 and the second switching element 24 are arranged on the bottom side 44 of the electrical circuit 10, i.e., below the coil 26.
[0034] List of reference symbols
[0035] 10 electrical circuit
[0036] 16 first power supply device
[0037] 18 second power supply device 20 electrical line
[0038] 22 first switching element
[0039] 24 second switching element
[0040] 26 coil
[0041] 28 third switching element 30 first connection point
[0042] 32 second connection point
[0043] 40 upper half of the electrical circuit
[0044] 42 lower half of the electrical circuit
[0045] 50 front strand of the electrical circuit 52 rear strand of the electrical circuit
Claims
Patent claims 1. Electrical circuit (10) for controlling energy withdrawal from a first power supply device (16) and from a second power supply device (18) in an electrical device, in particular in a machine tool, characterized in that the electrical circuit (10) comprises a first power supply device (16) and a second power supply device (18), as well as a first switching element (22), a second switching element (24) and a third switching element (28), a coil (26) and two connection points (30, 32), wherein the coil (26) is connected in series with the first power supply device (16) and the second power supply device (18) and wherein the first switching element (22) is configured to bridge the first power supply device (16) and the coil (26), and the second switching element (24) is configured to bridge the second power supply device (18) and the coil (26).where an output voltage U_B of the electrical circuit (10), which is applied at the terminals (30, 32), is greater than the sum of the first voltage U1 of the first power supply device (16) and the second voltage U2 of the second power supply device (18).
2. Electrical circuit (10) according to claim 1 characterized in that the first switching element (22) and / or second switching element (24) is / are designed as a MOSFET.
3. Electrical circuit (10) according to claim 1 or 2 characterized in that the third switching element (28) is designed as a diode.
4. Electrical circuit (10) according to one of the preceding claims characterized in that the third switching element (28) is configured to switch a state of the electrical circuit (10) on or off. An electrical device characterized in that the electrical device comprises an electrical circuit (10) according to one of the preceding claims. An electrical device according to claim 5 characterized in that the electrical device is a machine tool.