TECHNIQUES FOR RESTRICTION-FREE PRELOADING

Abstract

Techniques that eliminate the need for a dedicated pre-charge resistor by utilizing the main power path of the AC / DC, DC / DC, or DC / AC converter. By eliminating the pre-charge resistor, these techniques increase the maximum permissible rated current of the converter, as well as its impedance and inductance.

Description

Technical field

[0001] This document generally concerns power conversion and, in particular, techniques for limiting inrush current. State of the art

[0002] Before switching begins, as used in DC / AC, DC / DC, or AC / DC converters, the capacitors in the converter are at a voltage close to zero. If switching is initiated without first pre-charging the capacitors, a very high inrush current can occur. This inrush current can be several times the normal operating current and damage components within the current path. Conventional approaches to solving the inrush current problem involve placing a pre-charge resistor in the current path to reduce the magnitude of the current. However, the pre-charge resistor is a lossy element that consumes power during normal operation.

[0003] US10230298 discloses a PFC boost converter comprising a rectifier, a converter, and an output stage with an output capacitor, the output DC voltage being supplied across the output capacitor. The rectifier comprises four rectifying elements connected in a full-bridge configuration, the upper two of these four rectifying elements being thyristors and the lower two being diodes. By controlling the thyristors to be open only for a portion of each half-cycle of the input voltage, the amount of current per half-cycle supplied to the output capacitor is controllable and can be made very small. Accordingly, the charging current for pre-charging the output capacitor can be controllably limited, thus eliminating the need for a bulky pre-charge resistor to avoid high inrush currents. Brief description

[0004] This disclosure describes techniques that eliminate the use of a dedicated pre-charge resistor by utilizing the main power path of the AC / DC, DC / DC, or DC / AC converter. By eliminating the pre-charge resistor, the techniques of this disclosure increase the maximum rated current, impedance, and inductance of the converter.

[0005] In one aspect, this disclosure relates to a power conversion circuit configured to limit the inrush current during startup without the use of resistors, the power conversion circuit comprising: a first terminal configured to couple with an energy storage device; a converter circuit coupled to the first terminal, the converter circuit comprising an electronic switch and a protection diode coupled via the electronic switch; a switching circuit configured to be coupled with an alternating voltage; a second terminal coupled with the circuit; a filter circuit coupled between the converter circuit and the second terminal and configured to filter the alternating voltage, the filter circuit comprising: a first inductor coupled with the converter circuit;and a capacitor coupled between the first inductor and the second terminal; and a protective inductor coupled to the first or the second terminal, the protective inductor being configured to saturate at a current lower than the rated current of the protective diode in order to limit the inrush current during startup without the use of resistors. In a further aspect, this disclosure relates to a method for limiting an inrush current in a power conversion circuit during startup without the use of resistors, the method comprising: coupling a first terminal of the power conversion circuit to an energy storage device; coupling the first terminal to a converter circuit, the converter circuit comprising an electronic switch and a protective diode coupled via the electronic switch; coupling a second terminal to the circuit;Coupling a filter circuit between the converter circuit and the second terminal, wherein the filter circuit is configured to filter the AC voltage; and saturating a protective inductor coupled to the first or the second terminal at a current less than the rated current of the protection diode in order to limit the inrush current during switch-on without the use of resistors.

[0006] In yet another aspect, this disclosure relates to a power conversion circuit configured to limit the inrush current during startup without the use of resistors, the power conversion circuit comprising: a first terminal configured to couple with an energy storage device; a converter circuit coupled to the first terminal, the converter circuit comprising an electronic switch and a protection diode coupled via the electronic switch; a switching circuit configured to be coupled with an alternating voltage; a second terminal coupled with the circuit; a filter circuit coupled between the converter circuit and the second terminal and configured to filter the alternating voltage, the filter circuit comprising: a first inductor coupled with the converter circuit;and a capacitor coupled between the first inductor and the second terminal; a 3-phase protective inductor coupled to the second terminal, the 3-phase protective inductor being configured to saturate at a current less than the rated current of the protection diode in order to limit the inrush current during startup without the use of resistors. Brief description of the drawings Fig. Figure 1 is a perspective view of an example of a battery-powered machine that can implement various techniques of this revelation. Fig. Figure 2 is a schematic representation of an example of a power conversion circuit designed to limit the inrush current during startup without the use of resistors according to this disclosure. Fig. Figure 3 is a schematic representation of another example of a power conversion circuit designed to limit the inrush current during startup without the use of resistors according to this disclosure. Fig. Figure 4 is a schematic representation of another example of a power conversion circuit designed to limit the inrush current during startup without the use of resistors according to this disclosure. Fig. Figure 5 is a flowchart of an example of a Method 500 for limiting the inrush current in a power conversion circuit during startup without the use of resistors. Detailed description

[0007] Conventional approaches to solving the problem of inrush current in DC / AC, DC / DC, or AC / DC converters involve placing a pre-charge resistor in the current path to reduce the current level. However, the pre-charge resistor is a lossy element that consumes power during normal operation.

[0008] This disclosure describes techniques that eliminate the use of a dedicated pre-charge resistor by utilizing the main power path of the AC / DC, DC / DC, or DC / AC converter. By eliminating the pre-charge resistor, the techniques of this disclosure increase the maximum rated current, impedance, and inductance of the converter.

[0009] Fig. Figure 1 is a perspective view of an example of a battery-powered machine 100 that can implement various techniques of this revelation. Fig. Figure 1 shows a non-restrictive view of a battery-powered machine 100 in the form of a load-towing dump (LHD) vehicle, such as for mining, with a tipping bucket 102, wheels 104, 106, an operator control cabin 108 and a vehicle body 110.

[0010] The battery-powered machine 100, e.g., an electric mining truck, also includes an electrical architecture 112. The electrical architecture 112 can include a DC power source, including but not limited to a battery module, which can supply power to an electric motor, among other things. The electric motor can provide rotational power to one or more systems, such as a system configured to operate various hydraulics of the tipping bucket 102.

[0011] The techniques of this disclosure can be used by a power conversion circuit that converts between a DC power source, such as the DC power source (e.g., a battery module) of the electrical architecture 112 of the battery-powered machine 100. Fig. 1, and is coupled to an external component, such as a network (e.g., an electrical grid or a microgrid), a motor, or a generator. The techniques are generally applicable to direct current power sources, such as battery modules, and are not limited to those associated with a battery-powered machine. Additionally, the techniques of this disclosure are not limited to LHD vehicles and may instead be used for other industrial vehicles, including, but not limited to, continuous-drive mining vehicles, crushers, roof anchoring equipment, mining utility vehicles, underground mining loaders, articulated underground mining trucks, or any other vehicle used for industrial purposes such as transportation, excavation, drilling, loading, dumping, compaction, etc.Furthermore, although the techniques of this disclosure are particularly suitable for use in battery-powered vehicles, they can also be used in hybrid vehicles and vehicles with internal combustion engines.

[0012] Fig. Figure 2 is a schematic representation of an example of a power conversion circuit configured to limit the inrush current during startup without the use of resistors, according to this disclosure. In some examples, the power conversion circuit 200 may consist of Fig. 2 from the machine Fig. 1 can be used.

[0013] The power conversion circuit 200 is connected between an energy storage device 202, such as the DC power source (e.g., a battery module) of the electrical architecture 112 of the battery-powered machine 100. Fig. 1, and coupled to an external component 204, such as a network (e.g. an electrical network or a micronetwork), a motor or a generator.

[0014] The power conversion circuit 200 comprises a first terminal 206, which is configured to connect to the energy storage device 202, and a converter circuit 208, which is connected to the first terminal 206. The converter circuit 208 can be a bidirectional converter circuit capable of converting direct current to alternating current (converter) and alternating current to direct current (inverter). The converter circuit 208 includes electronic switches, such as transistors, represented as electronic switches S1-S6, with corresponding protection diodes D1-D6, which are connected via the electronic switches. A control circuit 210 is configured to generate control signals CS1-CS6, which are applied to corresponding electronic switches S1-S6, such as the gates of transistors, to control the switching operation of the converter circuit 208.

[0015] The power conversion circuit 200 further comprises a switching circuit 212, such as a circuit breaker, a contactor, or the like, which is coupled to the external component 204, e.g., an AC voltage, and to a second terminal 214. The switching circuit 212 is configured to electrically isolate the power conversion circuit 200 from the external component 204.

[0016] The power conversion circuit 200 comprises a filter circuit 216, which is coupled between the converter circuit 208 and the second terminal 214 and is configured to filter the AC voltage of the external component 204. The filter circuit 216 comprises a first inductor 218, which is coupled to the converter circuit 208, a capacitor 220, which is coupled between the first inductor 218 and the second terminal 214, and a second inductor 222. In the Fig. In the example shown, the second inductor 222 is coupled to the second terminal 214, and the first inductor 218 and the second inductor 222 are coupled in series.

[0017] Using the techniques of this disclosure, the second inductor 222 is a protective inductor configured to saturate at a current less than the rated current of at least one of the protective diodes D1-D6 in order to limit the inrush current during startup without the use of resistors. For example, the protective inductor may be configured to saturate at a current between 1 and 10 times, e.g., 5 times, the charging current of capacitor 220 in order to prevent damage to the protective diodes D1-D6 without the use of resistors. By using the techniques of this disclosure, the control circuit 210 does not need to close contacts, measure and confirm voltages, and the like to pre-charge capacitor 220, thereby simplifying the control scheme and eliminating the time required for pre-charging capacitor 220, e.g., 1 second to 5 minutes. In this case, the protective inductor saturates, e.g.,the second inductor 222, when the switch circuit 212 is closed, limits the inrush current without the use of pre-charge resistors.

[0018] In some examples, the protective inductors of this disclosure may include toroidal chokes. In other examples, the protective inductors of this disclosure may include silicon steel inductors or IE inductors. In some examples, the first inductor 218 includes a toroidal choke, a silicon steel inductor, or an IE inductor.

[0019] In some examples, the power conversion circuit 200 is a 3-phase converter circuit, as found in Fig. Figure 2 is shown. In some such examples, the protective inductor comprises a 3-phase inductor, such as a 3-phase toroidal choke, and the first inductor comprises a 3-phase inductor. In other examples, the power conversion circuit 200 may be a single-phase converter circuit with a single-phase protective inductor.

[0020] Fig. Figure 3 is a schematic representation of another example of a power conversion circuit designed to limit the inrush current during startup without the use of resistors, according to this disclosure. In some examples, the power conversion circuit 300 may consist of Fig. 3 from the machine Fig. 1. Some of the components of the power conversion circuit 300 are similar to those of the power conversion circuit 200. Fig. 2 and therefore use similar reference numbers. For the sake of brevity, similar components are not described in detail again.

[0021] The power conversion circuit 300 from Fig. 3 further comprises a third inductor 302, which is coupled to the second terminal 214. Additionally, the third inductor 302 is coupled between an input terminal 304 and an output terminal 306 of the switching circuit 212. In the power conversion circuit 300, the third inductor 302 is a protective inductor configured to saturate at a current less than the rated current of at least one of the protective diodes D1-D6, in order to limit the inrush current during startup without the use of resistors. In such an example, the second inductor 222 need not be a protective inductor.

[0022] Fig. Figure 4 is a schematic representation of another example of a power conversion circuit configured to limit the inrush current during startup without the use of resistors, according to this disclosure. In some examples, the power conversion circuit 400 may consist of Fig. 4 from the machine Fig. 1. Some of the components of the power conversion circuit 400 are similar to those of the power conversion circuit 200. Fig. 2 and therefore use similar reference numbers. For the sake of brevity, similar components are not described in detail again.

[0023] The power conversion circuit 400 from Fig. 4 further comprises a third inductor 402, which is coupled to the first terminal 206, wherein the third inductor 402 is the protective inductor. In some examples, as in Fig. As shown in Figure 4, the power conversion circuit 400 includes a further switching circuit 404, which is coupled between the energy storage device 202 and the first terminal 206. In some of these configurations, the third inductor 402 is coupled to 1) the first terminal 206 via the switching circuit 404 and 2) the energy storage device 202. In such an example, the second inductor 222 need not be a protective inductor.

[0024] Fig. Figure 5 is a flowchart of an example of Method 500 for limiting the inrush current in a power conversion circuit during startup without the use of resistors. In block 502, Method 500 includes coupling a first terminal of the power conversion circuit to an energy storage device. For example, the first terminal 206 can be connected to the energy storage device 202. Fig. 2 be coupled.

[0025] In block 504, the method comprises coupling the first terminal to a converter circuit, wherein the converter circuit includes an electronic switch and a protection diode coupled via the electronic switch. For example, the first terminal 206 can be connected to the converter circuit 208 consisting of Fig. 2 be coupled.

[0026] In block 506, the procedure 500 comprises coupling a circuit with an alternating voltage. For example, the switch circuit 212 can be connected to the external component 204. Fig. 2, such as a power grid, a microgrid, a motor or a generator.

[0027] In block 508, the procedure comprises 500 couplings of a second terminal to the circuit. For example, the second terminal 214 can be connected to the circuit 212 from Fig. 2 be coupled.

[0028] In block 510, the method comprises coupling a filter circuit between the converter circuit and the second terminal, wherein the filter circuit is configured to filter the AC voltage. For example, the filter circuit 216 can be connected between the converter circuit 208 and the second terminal 214. Fig. 2 be coupled.

[0029] In block 512, the method comprises saturating a protective inductor coupled to the first or second terminal at a current lower than the rated current of the protective diode to limit the inrush current during startup without the use of resistors. For example, the second inductor 222 can be made of Fig. 2 is coupled to the second terminal 214 and is the protective inductor. In another example, the third inductor 302 can be made of Fig. 3 is coupled to the second terminal 214 and is the protective inductor. In yet another example, the third inductor 402 can be made of Fig. 4 be coupled to the first terminal 206 and be the protective inductor. Commercial applicability

[0030] Conventional approaches to solving the problem of inrush current in DC / AC, DC / DC, or AC / DC converters involve placing a pre-charge resistor in the current path to reduce the current level. However, the pre-charge resistor is a lossy element that consumes power during normal operation.

[0031] The techniques described in this disclosure advantageously eliminate the need for a dedicated pre-charge resistor by utilizing the main power path of the AC / DC, DC / DC, or DC / AC converter. By eliminating the pre-charge resistor, these techniques increase the maximum rated current of the converter, as well as its impedance and inductance.

[0032] Unless expressly excluded, the use of the singular to describe a component, structure, or process does not preclude the use of multiple such components, structures, or processes, or their equivalents. The use of the terms "a," "one," "an," "a," and "the," "a," "a," and "at least one" or the term "one or more" and similar references in the context of the description of the invention (particularly in the context of the following claims) shall be interpreted as covering both the singular and the plural, unless otherwise indicated herein or clearly contradictory in the context.The use of the phrase "at least one" followed by a list containing one or more elements (for example, "at least one of A and B" or "one or more of A and B") is to be interpreted as meaning the selection of one element from the listed elements (A or B) or a combination of two or more of the listed elements (A and B, A, A and B; A, B and B), unless otherwise specified herein or clearly contradictory in context. Similarly, the word "or" as used herein refers to any possible permutation of a set of elements. For example, the phrase "A, B or C" refers to at least one of A, B, C or any combination thereof, such as any of the following: A; B; C; A and B; A and C; B and C; A, B and C; or multiples thereof, such as A and A; B, B and C; A, A, B, C and C; etc.

[0033] The foregoing detailed description is intended as an illustration and not as a limitation. The scope of disclosure should therefore be determined in relation to the attached claims together with the full scope of the equivalents claimed by the claims. QUOTES INCLUDED IN THE DESCRIPTION

[0000] This list of documents cited by the applicant was automatically generated and is included solely for the reader's convenience. The list is not part of the German patent or utility model application. The DPMA accepts no liability for any errors or omissions. Cited patent literature

[0000] US 10230298

[0003]

Claims

[1] Power conversion circuit (400) (300) (200) which is configured to limit inrush current during startup without the use of resistors, comprising the power conversion circuit (400) (300) (200): a first connection (206) which is configured to couple with an energy storage device (202); a converter circuit (208) coupled to the first terminal (206), wherein the converter circuit (208) comprises an electronic switch and a protection diode coupled via the electronic switch; a circuit (404) (212) which is designed to be coupled to an alternating voltage; a second terminal (214) which is coupled to the circuit (404) (212); a filter circuit (216) which is coupled between the converter circuit (208) and the second terminal (214) and is configured to filter the alternating voltage, the filter circuit (216) comprising: a first inductor (218) coupled to the converter circuit (208); and a capacitor (220) coupled between the first inductor (218) and the second terminal (214); and a protective inductor coupled to the first terminal (206) or the second terminal (214), wherein the protective inductor is configured to saturate at a current less than a rated current of the protection diode in order to limit the inrush current during startup without the use of resistors. [2] Power conversion circuit (400) (300) (200) according to claim 1, wherein the protective inductor is coupled to the second terminal (214), and wherein the filter circuit (216) further comprises: a second inductor (222) coupled between the capacitor (220) and the second terminal (214), wherein the first inductor (218) and the second inductor (222) are connected in series. [3] Power conversion circuit (400) (300) (200) according to claim 2, wherein the protective inductor is further coupled between an input terminal (304) and an output terminal (306) of the switch circuit (404) (212). [4] Power conversion circuit (400) (300) (200) according to claim 1, wherein the protective inductor is coupled to the second terminal (214), and wherein the filter circuit (216) further comprises: a second inductor (222) coupled in series with the first inductor (218), wherein the second inductor (222) comprises the protective inductor. [5] Power conversion circuit (400) (300) (200) according to claim 1, wherein the protective inductor comprises a toroidal choke. [6] Power conversion circuit (400) (300) (200) according to claim 1, wherein the protective inductor is coupled to the second terminal (214), and wherein the first inductor (218) comprises a toroidal choke. [7] Power conversion circuit (400) (300) (200) according to claim 1, wherein the converter circuit (208) is a 3-phase converter circuit (208). [8] Power conversion circuit (400) (300) (200) according to claim 1, wherein the protective inductor comprises a 3-phase toroidal choke, and wherein the first inductor (218) comprises a 3-phase inductor. [9] Power conversion circuit (400) (300) (200) according to claim 1, wherein the switching circuit (404) (212) is a first switching circuit (404) (212) the circuit further comprising: a second switching circuit (404) (212) which is coupled between the energy storage device (202) and the first terminal (206), wherein the protective inductor is coupled via the second switch circuit (404) (212) to 1) the first terminal (206) and 2) the energy storage device (202). [10] Power conversion circuit (400) (300) (200) according to claim 1, wherein the protective inductor is configured to saturate at a control time between 1 and 10 times the charging current of the capacitor (220). [11] Method (500) for limiting the inrush current in a power conversion circuit (400) (300) (200) during startup without the use of resistors, the method (500) comprising: Coupling a first terminal (206) of the power conversion circuit (400) (300) (200) with an energy storage device (202); Coupling the first terminal (206) with a converter circuit (208), wherein the converter circuit (208) comprises an electronic switch and a protection diode, which is coupled via the electronic switch; Coupling a circuit (404) (212) to an alternating voltage; Coupling a second terminal (214) with the circuit (404) (212); Coupling a filter circuit (216) between the converter circuit (208) and the second terminal (214), wherein the filter circuit (216) is configured to filter the alternating voltage; and Saturating a protective inductor coupled to the first terminal (206) or the second terminal (214) at a current less than the rated current of the protective diode in order to limit the inrush current during switch-on without the use of resistors. [12] Method (500) according to claim 11, wherein the filter circuit (216) comprises a capacitor (220), a first inductor (218) and a second inductor (222), the method (500) comprising: Coupling the protective inductor to the second terminal (214); and Coupling a second inductor (222) between the capacitor (220) and the second terminal (214), wherein the first inductor (218) and the second inductor (222) are coupled in series. [13] Method (500) according to claim 12, comprising: Coupling the protective inductor between an input terminal (304) and an output terminal (306) of the switch circuit (404) (212). [14] Method (500) according to claim 11, wherein the filter circuit (216) comprises a capacitor (220), a first inductor (218) and a second inductor (222), the method (500) comprising: Coupling the protective inductor to the second terminal (214); and Coupling a second inductor (222) between the capacitor (220) and the second terminal (214), wherein the first inductor (218) and the second inductor (222) are coupled in series, and wherein the second inductor (222) comprises the protective inductor. [15] Method (500) according to claim 11, wherein the filter circuit (216) comprises a capacitor (220), a first inductor (218) and a second inductor (222), the method (500) comprising: Coupling the protective inductor to the second terminal (214), wherein the first inductor (218) comprises a toroidal choke.

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