WO2023135307A1

WO2023135307A1 - Safety circuit, power converter and power system

Info

Publication number: WO2023135307A1
Application number: PCT/EP2023/050901
Authority: WO
Inventors: Maxime POUYET
Original assignee: Punch Powertrain
Priority date: 2022-01-17
Filing date: 2023-01-16
Publication date: 2023-07-20

Abstract

A safety circuit for a plurality of power sources having respective ground terminals electrically connected to a common ground and to respective ground input terminals of a power converter is provided. The safety circuit comprises a detection node, detection lines, a detection unit, and resistors. The detection lines electrically connect respective ground input terminals of the power converter to the detection node. The detection unit is electrically connected to the detection node and detects an electrical disconnection between each of the respective ground terminals of the plurality of power sources and the respective ground input terminal of the power converter. At least one resistor is disposed in each detection line, such that, in case of an electrical disconnection between one of the ground terminals and the respective ground input terminal, a magnitude of a maximum current flowing through the detection node is below a predetermined threshold.

Description

Title: Safety Circuit, Power Converter and Power System

FIELD

The present invention relates to a safety circuit. The present invention further relates to a power converter comprising the safety circuit and a power system comprising the power converter.

BACKGROUND

Some systems may have different electrical output power requirements and therefore comprise multiple power sources, such as batteries. The multiple power sources may comprise high voltage power sources and low voltage power sources. Wires corresponding to the multiple power sources may have different ratings or specifications based on the corresponding power sources and expected levels of current flow. For example, the wires corresponding to the low voltage power sources may have low ratings (e.g., less than or equal to 3A) as compared to the wires corresponding to the high voltage power sources.

Some conventional systems may have isolated power sources. The isolated power sources may have isolated ground terminals. The isolated ground terminals may be intrinsically safe and may prevent dangerously high current to flow through wires with a low rating in an event of a fault or a failure which may otherwise lead to an unsafe condition, such as a fire. However, such conventional systems may require additional components, such as transformers. Further, the conventional systems comprising the additional components may have increased cost and complexity.

In some other conventional systems, the power sources may have respective ground terminals electrically connected to a common ground. Such conventional systems may not require the additional components to isolate the ground terminals. On the other hand, such conventional systems may require robust and complex algorithms to detect a fault or failure which may lead to the unsafe condition. However, the robust and complex algorithms of such conventional systems may also lead to increased risk of false alarms. Further, in case of any undetected fault or failure, there may be risk of the unsafe condition. Thus, such conventional systems may not be intrinsically safe and reliable.

Therefore, the conventional systems comprising the multiple power sources may either be expensive or may not intrinsically safe.

SUMMARY OF THE INVENTION

As noted above, there are a number of disadvantages associated with the currently available techniques for protection of systems comprising multiple power sources. For example, some of the currently available techniques may comprise isolated power sources and may be intrinsically safe but may require additional components and therefore may have increased cost and complexity. Further, some of the other currently available techniques may comprise a common ground and may be comparatively cheaper, but may require robust and complex algorithms to detect a fault or failure which may otherwise lead to an unsafe condition, such as a fire. Such currently available techniques may further be unreliable and may lead to the unsafe condition in case of an undetected fault or failure.

It is an object of the present invention to provide an improved safety circuit, an improved power converter, and an improved power system. In particular, it is an object of the present invention to provide an improved safety circuit, an improved power converter, and an improved power system which may be intrinsically safe and reliable. Further the improved safety circuit, the improved power converter, and the improved power system may not require additional components and may therefore have a lower cost than conventional isolated systems. According to a first aspect of the present invention, a safety circuit for a plurality of power sources having respective ground terminals electrically connected to a common ground and to respective ground input terminals of a power converter is provided. The safety circuit comprises a detection node, a plurality of detection lines, a detection unit, and a plurality of resistors. The plurality of detection lines electrically connect respective ground input terminals of the power converter to the detection node. The detection unit is electrically connected to the detection node and configured to detect an electrical disconnection between each of the respective ground terminals of the plurality of power sources and the respective ground input terminal of the power converter. The plurality of resistors is disposed in the plurality of detection lines. At least one resistor from the plurality of resistors is disposed in each detection line, such that, in case of an electrical disconnection between one of the ground terminals and the respective ground input terminal, a magnitude of a maximum current flowing through the detection node is below a predetermined threshold.

Optionally, the plurality of resistors may have a substantially equal resistance value.

Optionally, a resistance value of each resistor may be greater than about 20 ohms and less than about 200 ohms.

Optionally, the predetermined threshold may be less than or equal to 3 amperes.

Optionally, the detection unit may be configured to detect the electrical disconnection based on a detection of a non-zero current at the detection node.

According to a second aspect of the present invention, a power converter is provided. The power converter comprises a plurality of ground input terminals, a plurality of power input terminals, a plurality of power supply units, and the safety circuit according to the first aspect of the present invention. The plurality of ground input terminals is electrically connected to respective ground terminals of a plurality of power sources. The plurality of power input terminals is electrically connected to respective output terminals of the plurality of power sources. The plurality of power supply units is electrically connected to respective ground input terminals and respective power input terminals. Each power supply unit is configured to supply electric power from a respective power source from the plurahty of power sources to a respective load. Each detection line electrically connects a respective ground input terminal from the plurality of ground input terminals to the detection node.

Optionally, the power converter may further comprise a control unit communicably coupled to the detection unit and at least one power supply unit from the plurality of power supply units. The control unit may be configured to control the at least one power supply unit based, at least in part, on signals received from the detection unit.

Optionally, the at least one power supply unit from the plurality of power supply units may be further configured to convert direct current (DC) power to alternating current (AC) power for supply to the respective load.

Optionally, one power supply unit from the plurality of power supply units may be configured to provide electric power to the detection unit and the control unit.

Optionally, the one power supply unit may be further configured to provide DC power to the detection unit and the control unit.

Optionally, the power converter may further comprise a plurality of power lines electrically connecting a respective power input terminal from the plurality of power input terminals to a respective power supply unit from the plurality of power supply units.

Optionally, the power converter may further comprise a plurality of return lines electrically connecting a respective ground input terminal from the plurality of ground input terminals to a respective power supply unit from the plurality of power supply units.

According to a third aspect of the present invention, a power system is provided. The power system comprises a plurality of power sources, a common ground, the power converter of the second aspect of the present invention, a plurality of ground connection lines, and a plurality of power connection lines. Each power source comprises an output terminal and a ground terminal. The common ground is electrically connected to the ground terminal of each power source. Each ground connection line electrically connects the ground terminal of a respective power source from the plurality of power sources to a respective ground input terminal from the plurality of ground input terminals of the power converter. Each power connection line electrically connects the output terminal of a respective power source from the plurality of power sources to a respective power input terminal from the plurality of power input terminals of the power converter. The detection unit of the safety circuit of the power converter is configured to detect an electrical disconnection in each ground connection line.

Optionally, the plurahty of power sources may comprise a first power source and a second power source. The first power source may comprise a first output terminal and a first ground terminal, the first power source being a voltage source configured to provide a first output voltage at the first output terminal. The second power source may comprise a second output terminal and a second ground terminal, the second power source being a voltage source configured to provide a second output voltage at the second output terminal different from the first output voltage.

Optionally, the first output voltage may be about 12 volts, and the second output voltage may be about 48 volts.

Optionally, the plurahty of ground input terminals may comprise a first ground input terminal and a second ground input terminal. The plurality of power input terminals may comprise a first power input terminal and a second power input terminal. The plurality of ground connection lines may comprise a first ground connection line electrically connecting the first ground input terminal with the first ground terminal of the first power source and a second ground connection line electrically connecting the second ground input terminal with the second ground terminal of the second power source. The plurality of detection lines may comprise a first detection line electrically connecting the first ground input terminal to the detection node and a second detection line electrically connecting the second ground input terminal to the detection node. The plurality of resistors may comprise a first resistor disposed in the first detection line and a second resistor disposed in the second detection line. The plurality of power connection lines may comprise a first power connection line electrically connecting the first output terminal of the first power source to the first power input terminal and a second power connection line electrically connecting the second output terminal of the second power source to the second power input terminal. The plurality of power supply units may comprise a first power supply unit and a second power supply unit. The first power supply unit is electrically connected to the first ground input terminal and the first power input terminal. The second power supply unit is electrically connected to the second ground input terminal and the second power input terminal.

Optionally, the first resistor and the second resistor may have a resistance value of about 100 ohms.

Optionally, in case of an electrical disconnection in the first ground connection line, the first power source may be configured to supply electric power to the first power supply unit via the first power connection line and the first power input terminal. Optionally, in case of the electrical disconnection in the first ground connection line, an electrical return path from the first power supply unit to the first ground terminal of the first power source may comprise the first detection line, the detection node, the second detection line, the second ground input terminal, the second ground connection line, the second ground terminal of the second power source, and the common ground.

Optionally, in case of an electrical disconnection in the second ground connection line, a magnitude of a maximum electric current flowing through the first ground connection line may be less than or equal to 3 amperes. Optionally, in case of the electrical disconnection in the second ground connection line, an electrical return path from the second power supply unit to the second ground terminal of the second power source may comprise the second detection line, the detection node, the first detection line, the first ground input terminal, the first ground connection line, the first ground terminal of the first power source, and the common ground.

As discussed above, the currently available techniques for protection of systems comprising multiple power sources have their respective disadvantages. Specifically, the currently available techniques may either be expensive or not intrinsically safe. The power converters and power systems comprising the safety circuit of the present disclosure may not require any additional components and complex algorithms to detect the faults or failures, such as an electrical disconnection, in order to prevent any undetected faults or failures. The safety circuit comprises the plurality of resistors which may be simple, robust, and cheap electrical components. The plurality of resistors in each detection line may naturally limit the maximum current flowing through the detection node in case of an electrical disconnection between one of the ground terminals and the respective ground input terminal, and may ensure that the magnitude of the maximum current flowing through the detection node is below the predetermined threshold. Hence, the power converters and the power systems comprising the safety circuit of the present disclosure may not require a quick detection of a failure or quick response upon detection of the failure to prevent the unsafe condition. Therefore, the power converter and the power system comprising the safety circuit may be intrinsically safe and reliable, and may have lower cost and complexity than conventional isolated systems.

The present invention will be further elucidated with reference to figures of exemplary embodiments. The embodiments may be combined or may be applied separately from each other.

BRIEF DESCRIPTION OF THE FIGURES

Same reference numerals refer to same elements or elements of similar function throughout the various figures. Furthermore, only reference numerals necessary for the description of the respective figure are shown in the figures. The shown embodiments represent only examples of how the invention can be carried out. This should not be construed as a limitation of the invention.

For a better understanding of the invention, and to show more clearly how it may be carried into effect, reference will now be made, by way of example only, to the accompanying drawings, in which:

Fig. 1 shows a schematic view of a power system in accordance with an embodiment of the present invention;

Fig. 2 shows a schematic view of a power system in accordance with another embodiment of the present invention;

Fig. 3 shows a schematic view of a safety circuit of the power system of Fig. 2 in accordance with an embodiment of the present invention;

Fig. 4 shows another schematic view of the power system of Fig 2 in a first electrical disconnection state;

Fig. 5 shows another schematic view of the safety circuit of Fig 3 in the first electrical disconnection state;

Fig. 6 shows another schematic view of the power system of Fig 2 in a second electrical disconnection state; and Fig. 7 shows another schematic view of the safety circuit of Fig 3 in the second electrical disconnection state.

DETAILED DESCRIPTION OF THE FIGURES

In this application similar or corresponding features are denoted by similar or corresponding reference signs. The description of the various embodiments is not limited to the examples shown in the figures and the reference numbers used in the detailed description and the claims are not intended to limit the description of the embodiments, but are included to elucidate the embodiments by referring to the example shown in the figures.

As noted above, there is provided an improved safety circuit for power converters and power systems comprising multiple power sources. In particular, there is provided a safety circuit for a power converter and a power system for ensuring that the power converter and the power system may be intrinsically safe and reliable, and may have a lower cost than conventional isolated systems.

As used herein, the term “lines”, unless otherwise indicated, refer to electrically conductive paths comprising various components, such as wires, cables, pads, traces, vias, junctions, connectors, etc. Such lines may be used to transmit electric current, electric signals, and so forth.

Fig. 1 shows a schematic view of a power system 300, according to an embodiment of the present disclosure. The power system 300 comprises a plurality of power sources 110-1 to 110N (collectively, the plurality of power sources 110). In some embodiments, the plurality of power sources 110 may comprise any number of power sources, for example, two power sources, three power sources, five power sources, ten power sources, and so forth.

The power system 300 may be located in a vehicle (not shown). In some embodiments, the vehicle may be an electric vehicle or a hybrid vehicle. In some examples, the vehicle may comprise cars, buses, trucks, offroad vehicles, motorcycles, aircrafts, bicycles, trams, locomotives, heavy- duty vehicles used in construction and earthworking, and so forth. In some cases, the vehicle may be equipped with tools, appliances, and/or other electrically powered equipment that may have a different power requirement from a single battery that is conventional on a vehicle. In some cases, the vehicle may have different electrical power demands. Therefore, such vehicles may be provided with batteries having different electrical power outputs. In some cases, at least one of the plurality of power sources 110 may be a main battery and at least one of the plurality of power sources 110 may be an auxiliary battery. The main battery may provide electrical power to a motor or a prime mover of the vehicle and the auxiliary battery may provide electrical power to various electronic components and devices disposed in the vehicle.

In some other examples, the power system 300 may be located in an electrical machine, an energy storage system, and the like.

Each power source 110-1 to 110N comprises an output terminal 114-1 to 114N (collectively, the output terminals 114) and a ground terminal 112-1 to 112N (collectively, the ground terminals 112). For example, the power source 110-1 comprises the output terminal 114-1 and the ground terminal 112-1, the power source 110-2 comprises the output terminal 114-2 and the ground terminal 112-2, and so forth.

In some embodiments, each power source 110 may be a voltage source or a current source. In further embodiments, each power source 110 may comprise a battery, an electrochemical cell, a fuel cell, a capacitor, a photovoltaic cell, or any other source of electrical energy. In some embodiments, each output terminal 114 corresponds to a positive terminal of the corresponding power source 110. Similarly, each ground terminal 112 corresponds to a negative terminal of the corresponding power source 110. For example, the output terminal 114-1 may be the positive terminal of the power source 110-1, while the ground terminal 112-1 may be the negative terminal of the power source 110-2. The power system 300 comprises a common ground 130. The common ground 130 is electrically connected to the ground terminal 112 of each power source 110. In other words, the common ground 130 is electrically connected to each ground terminal 112-1 to 112N. In some embodiments, the common ground 130 may correspond to a chassis of a vehicle associated with the power system 300.

The power system 300 further comprises a power converter 200. In some embodiments, the power converter 200 may be an inverter, a rectifier, a chopper, a cycloconverter, or any other power converter.

The power converter 200 comprises a plurality of ground input terminals 202-1 to 202-N (collectively, the plurality of ground input terminals 202) electrically connected to respective ground terminals 112-1 to 112-N of the plurality of power sources 110-1 to 110-N. For example, the ground input terminal 202-1 is electrically connected to the ground terminal 112-1 of the power source 110-1, the ground input terminal 202-2 is electrically connected to the ground terminal 112-2 of the power source 110- 2, and so forth.

Therefore, the plurality of power sources 110 has the respective ground terminals 112 electrically connected to the common ground 130 and to the respective ground input terminals 202 of the power converter 200.

The power converter 200 comprises a plurality of power input terminals 204-1 to 204-N (collectively, the plurality of power input terminals 204) electrically connected to respective output terminals 114-1 to 114-N of the plurality of power sources 110-1 to 110-N. For example, the power input terminal 204-1 is electrically connected to the output terminal 114-1 of the power source 110-1, the power input terminal 204-2 is electrically connected to the output terminal 114-2 of the power source 110-2, and so forth.

The power converter 200 further comprises a plurality of power supply units 206-1 to 206-N (collectively, the plurality of power supply units 206) electrically connected to respective ground input terminals 202-1 to 202-N and respective power input terminals 204-1 to 204-N. For example, the power supply unit 206-1 is electrically connected to the ground input terminal 202-1 and the power input terminal 204-1, the power supply unit 206-2 is electrically connected to the ground input terminal 202-2 and the power input terminal 204-2, and so forth.

Each power supply unit 206-1 to 206-N is configured to supply electric power from a respective power source from the plurality of power sources 110-1 to 110-N to a respective load 150-1 to 150-N (collectively, the loads 150). For example, the power supply unit 206-1 is configured to supply electric power from the power source 110-1 to the load 150-1, the power supply unit 206-2 is configured to supply electric power from the power source 110-2 to the load 150-2, and so forth.

The power converter 200 further comprises a safety circuit 100 for the plurality of power sources 110 having the respective ground terminals 112 electrically connected to the common ground 130 and to the respective ground input terminals 202 of the power converter 200.

The safety circuit 100 comprises a detection node 102, a plurality of detection lines 104-1 to 104-N (collectively, the plurality of detection lines 104), a detection unit 106, and a plurality of resistors 108-1 to 108-N (collectively, the plurality of resistors 108).

The plurality of detection lines 104 electrically connects the respective ground input terminals 202 of the power converter 200 to the detection node 102. In other words, each detection line 104 electrically connects the respective ground input terminal 202 from the plurality of ground input terminals 202 to the detection node 102. For example, the detection line 104-1 electrically connects the ground input terminal 202-1 of the power converter 200 to the detection node 102, the detection line 104-2 electrically connects the ground input terminal 202-2 of the power converter 200 to the detection node 102, and so forth. The detection unit 106 is electrically connected to the detection node 102 and configured to detect an electrical disconnection (for example, an electrical disconnection 533 or an electrical disconnection 535 shown in Figs. 4 and 6, respectively) between each of the respective ground terminals 112 of the plurality of power sources 110 and the respective ground input terminal 202 of the power converter 200.

The plurality of resistors 108 is disposed in the plurality of detection lines 104. Specifically, at least one resistor from the plurality of resistors 108 is disposed in each detection line 104. For example, the resistor 108-1 is disposed in the detection line 104-1, the resistor 108-2 is disposed in the detection line 104-2, and so forth.

In some embodiments, each resistor 108 may have a fixed value of resistance or a variable value of resistance. Further, each resistor 108 may comprise any suitable type of electrical resistor, for example, an axial-lead resistor, a printed resistor, a film -based resistor, and so forth. Each resistor 108 may comprise carbon, metal, ceramic, or combinations thereof.

In some embodiments, a resistance value of each resistor 108 is greater than about 20 ohms and less than about 200 ohms. In some embodiments, the plurality of resistors 108 has a substantially equal resistance value. For example, the plurality of resistors 108-1 to 108-N may have a substantially equal resistance value of about 100 ohms. In some cases, the resistance value of each resistor 108 may be selected such that the ground input terminals 202 of the power converter 200 are not electrically isolated from the detection node 102.

The at least one resistor from the plurality of resistors 108 is disposed in each detection line 104 such that, in case of an electrical disconnection between one of the ground terminals 112 and the respective ground input terminal 202, a magnitude of a maximum current flowing through the detection node 102 is below a predetermined threshold. In some embodiments, the predetermined threshold is less than or equal to 3 amperes. In some embodiments, the predetermined threshold is less than or equal to 2 amperes, less than or equal to 1 ampere, less than or equal to 0.5 ampere, or less than or equal to 0.25 ampere. In some cases, the resistance value of each resistor 108 may be selected based on the predetermined threshold.

In some embodiments, the detection unit 106 is configured to detect the electrical disconnection based on a detection of a non-zero current at the detection node 102. The non-zero current at the detection node 102 may indicate the electrical disconnection. A substantially zero current at the detection node 102 may indicate that there is no electrical disconnection. Therefore, during a normal operation (no electrical disconnection), a current value at the detection node 102 may be substantially zero.

In some embodiments, the power converter 200 further comprises a control unit 208 communicably coupled to the detection unit 106 and at least one power supply unit from the plurality of power supply units 206.

In some embodiments, the detection unit 106 may comprise a processor (not shown). The processor may be implemented as a single entity, such as a microcontroller or a field programmable gate array (FPGA), or may also be implemented as a distributed processing device comprising a plurality of separate processing entities or even a cloud-based solution. The processor may also be shared with other applications (e.g., of a vehicle associated with the power system 300). In some embodiments, the detection unit 106 may further include a memory (not shown). In some embodiments, the memory may be configured to store program codes that can be executed by the processor to perform the various control functions described herein. For example, the program codes may include a fault detection algorithm.

In some embodiments, the control unit 208 may comprise a processor (not shown). The processor may be implemented as a single entity, such as a microcontroller or a field programmable gate array (FPGA), or may also be implemented as a distributed processing device comprising a plurality of separate processing entities or even a cloud-based solution. The processor may also be shared with other applications (e.g., of a vehicle associated with the power system 300). In some embodiments, the control unit 208 may further include a memory (not shown). In some embodiments, the memory may be configured to store program codes that can be executed by the processor to perform the various control functions described herein. For example, the program codes may include a fault mitigation algorithm, a power supply unit control algorithm, etc.

In some embodiments, the control unit 208 is configured to control the at least one power supply unit based, at least in part, on signals 107 received from the detection unit 106. For example, upon detection of the electrical disconnection by the detection unit 106, the detection unit 106 may generate the signals 107. The control unit 208 may be configured to power off the at least one power supply unit based, at least in part, on the signals 107 received from the detection unit 106. The signals 107 may comprise, but not limited to, electrical signals, optical signals, electromagnetic signals, analog and/or digital signals, one or more computer instructions, a bit and/or bit stream, or the like.

In the illustrated embodiment of Fig. 1, the control unit 208 is communicably coupled to the detection unit 106 and the power supply unit 206-2 from the plurality of power supply units 206. Therefore, the control unit 208 may be configured to control the power supply unit 206-2 based, at least in part, on the signals 107 received from the detection unit 106.

In some embodiments, the at least one power supply unit from the plurality of power supply units 206 is further configured to convert direct current (DC) power to alternating current (AC) power for supply to the respective load 150. For example, the power supply unit 206-2 may be configured to convert DC power to AC power for supply to the load 150-2. In some embodiments, the load 150-2 may be one or more AC electric motors of the vehicle associated with the power system 300. In some embodiments, one power supply unit from the plurality of power supply units 206 is configured to provide electric power to the detection unit 106 and the control unit 208. In some embodiments, the one power supply unit is further configured to provide DC power to the detection unit 106 and the control unit 208. For example, the power supply unit 206-N from the plurality of power supply units 206 may be configured to provide electric power to the detection unit 106 and the control unit 208. Further, the power supply unit 206-N may be configured to provide DC power to the detection unit 106 and the control unit 208. In some embodiments, the one power supply unit is further configured to provide DC power to other electronic components of the power system 300. In some examples, the load 150-N may comprise one or more electronic components (such as control circuits) of the vehicle. In some examples, the power supply unit 206-N may supply an output DC voltage of about 12 volts (V) to the detection unit 106, the control unit 208, the other electronic components of the power system 300, and the load 150-N.

In some embodiments, the power converter 200 further comprises a plurality of power lines 210-1 to 210 -N (collectively, the plurality of power lines 210) electrically connecting a respective power input terminal from the plurality of power input terminals 204-1 to 204-N to a respective power supply unit from the plurality of power supply units 206-1 to 206-N. For example, the power line 210-1 electrically connects the power input terminal 204-1 to the power supply unit 206-1, the power line 210-2 electrically connects the power input terminal 204-2 to the power supply unit 206-2, and so forth.

In some embodiments, the power converter 200 further comprises a plurality of return lines 220-1 to 220 -N (collectively, the plurality of return lines 220) electrically connecting a respective ground input terminal from the plurality of ground input terminals 202-1 to 202-N to a respective power supply unit from the plurality of power supply units 206-1 to 206-N. For example, the return line 220-1 electrically connects the ground input terminal 202-1 to the power supply unit 206-1, the return line 220-2 electrically connects the ground input terminal 202-2 to the power supply unit 206-2, and so forth.

The power system 300 comprises a plurality of ground connection lines 230-1 to 230-N (collectively, the plurality of ground connection hnes 230). Each ground connection line 230 electrically connects the ground terminal 112 of a respective power source from the plurality of power sources 110 to a respective ground input terminal from the plurahty of ground input terminals 202 of the power converter 200. For example, the ground connection line 230-1 electrically connects the ground terminal 112-1 of the power source 110-1 to the ground input terminal 202-1 of the power converter 200, the ground connection line 230-2 electrically connects the ground terminal 112-2 of the power source 110-2 to the ground input terminal 202-2 of the power converter 200, and so forth.

The detection unit 106 of the safety circuit 100 of the power converter 200 is configured to detect an electrical disconnection in each ground connection line 230.

The power system 300 further comprises a plurality of power connection lines 240-1 to 240-N (collectively, the plurality of power connection lines 240). Each power connection line 240 electrically connects the output terminal 114 of a respective power source from the plurality of power sources 110 to a respective power input terminal from the plurality of power input terminals 204 of the power converter 200. For example, the power connection line 240-1 electrically connects the output terminal 114-1 of the power source 110-1 to the power input terminal 204-1 of the power converter 200, the power connection line 240-2 electrically connects the output terminal 114-2 of the power source 110-2 to the power input terminal 204-2 of the power converter 200, and so forth. An advantage of the invention is that the plurality of resistors 108 in each detection hne 104 may naturally limit the maximum current flowing through the detection node 102 in case of an electrical disconnection between one of the ground terminals 112 and the respective ground input terminal 202, and may ensure that the magnitude of the maximum current flowing through the detection node 102 is below the predetermined threshold. Hence, the power converter 200 and the power system 300 comprising the safety circuit 100 of the present disclosure may not require a quick detection of an electrical disconnection or quick response upon detection of the electrical disconnection to prevent an unsafe condition, such as a fire. Therefore, the power converter 200 and the power system 300 may be intrinsically safe. The power converter 200 and the power system 300 comprising the safety circuit 100 may not require any additional components and complex algorithms to detect the electrical disconnection in order to prevent unsafe conditions. This may further decrease a processing load on the processor of the control unit 208 of the power system 300. In some cases, the detection unit 106 may comprise the processor. Further, the plurality of resistors 108 may be simple, robust, and cheap electrical components. Therefore, implementation of the safety circuit 100 in the power converter 200 and the power system 300 may be cost-effective.

Fig. 2 shows a schematic view of a power system 600, according to another embodiment. In Fig. 2, thick solid lines denote high current lines (e.g., with currents greater than 100A). The other solid lines denote low current lines (e.g., with currents less than 2A). Dot-dash lines denote control or data lines. The power system 600 is substantially similar to the power system 300. The power system 600 also comprises a plurality of power sources. Specifically, the power system 600 comprises two power sources. The plurality of power sources comprises a first power source 410 and a second power source 420. The first power source 410 comprises a first output terminal 414 and a first ground terminal 412. In the illustrated embodiment of Fig. 2, the first power source 410 is a voltage source configured to provide a first output voltage at the first output terminal 414. In some embodiments, the first power source 410 may be the auxiliary battery.

The second power source 420 comprises a second output terminal 424 and a second ground terminal 422. In the illustrated embodiment of Fig. 2, the second power source 420 is a voltage source configured to provide a second output voltage at the second output terminal 424 different from the first output voltage. In some embodiments, the second output voltage is greater than the first output voltage. In these embodiments, the second power source 420 may be the main battery.

In some embodiments, the first output voltage is about 12 volts, and the second output voltage is about 48 volts. However, in some other embodiments, the first and second output voltages may have any values of voltages such that the first and second output voltages are different from each other.

The power system 600 further comprises a common ground 430. The common ground 430 is electrically connected to the first ground terminal 412 of the first power source 410 and the second ground terminal 422 of the second power source 420.

The power system 600 further comprises a power converter 500. In some embodiments, the power converter 500 may be an inverter, a rectifier, a chopper, a cycloconverter, or any other power converter. In the illustrated embodiment of Fig. 2, the power converter 500 is an inverter.

The power converter 500 comprises a plurality of ground input terminals. Specifically, the plurality of ground input terminals comprises a first ground input terminal 512 and a second ground input terminal 522. The first ground input terminal 512 and the second ground input terminal 522 are electrically connected to the first and second ground terminals 412, 422, respectively.

Therefore, the first power source 410 has the first ground terminal 412 electrically connected to the common ground 430 and to the first ground input terminal 512 of the power converter 500. Further, the second power source 420 has the second ground terminal 422 electrically connected to the common ground 430 and to the second ground input terminal 522 of the power converter 500.

The power converter 500 further comprises a plurahty of power input terminals. Specifically, the plurahty of power input terminals comprises a first power input terminal 514 and a second power input terminal 524.

The first power input terminal 514 and the second power input terminal 524 are electrically connected to the first and second output terminals 414, 424, respectively.

The power converter 500 further comprises a plurahty of power supply units. Specifically, the plurality of power supply units comprises a first power supply unit 516 and a second power supply unit 526. The first power supply unit 516 is electrically connected to the first ground input terminal 512 and first power input terminal 514. Further, the second power supply unit 526 is electrically connected to the second ground input terminal 522 and the second power input terminal 524. The first power supply unit 516 is configured to supply electric power from the first power source 410 to a first load 440. The second power supply unit 526 is configured to supply electric power from the second power source 420 to a second load 450.

The power converter 500 further comprises a safety circuit 400 for the first and second power sources 410, 420 having the respective first and second ground terminals 412, 422 electrically connected to the common ground 430 and to the respective first and second ground input terminals 512, 522 of the power converter 500. The safety circuit 400 comprises a detection node 402. The safety circuit 400 further comprises a plurality of detection lines. Specifically, the plurality of detection lines comprises a first detection line 434 electrically connecting the first ground input terminal 512 to the detection node 402 and a second detection line 444 electrically connecting the second ground input terminal 522 to the detection node 402.

The safety circuit 400 further comprises a detection unit 406 electrically connected to the detection node 402. The detection unit 406 is configured to detect an electrical disconnection between the first ground terminal 412 of the first power source 410 and the first ground input terminal 512 of the power converter 500. Similarly, the detection unit 406 is further configured to detect an electrical disconnection between the second ground terminal 422 of the second power source 420 and the second ground input terminal 522 of the power converter 500.

The safety circuit 400 further comprises a plurality of resistors. Specifically, the plurality of resistors comprises a first resistor 418 disposed in the first detection line 434 and a second resistor 428 disposed in the second detection line 444. Therefore, the first resistor 418 is electrically disposed between the detection node 402 and the first ground input terminal 512. Similarly, the second resistor 428 is electrically disposed between the detection node 402 and the second ground input terminal 522.

In some embodiments, the power converter 500 further comprises a control unit 508 communicably coupled to the detection unit 406 and the second power supply unit 526. In some embodiments, the control unit 508 is configured to control the second power supply unit 526 based, at least in part, on signals 407 received from the detection unit 406. For example, upon detection of the electrical disconnection by the detection unit 406, the detection unit 406 may generate the signals 407. The control unit 508 may be configured to power off the at least one power supply unit based, at least in part, on the signals 407 received from the detection unit 406. The signals 407 may comprise, but not limited to, electrical signals, optical signals, electromagnetic signals, analog and/or digital signals, one or more computer instructions, a bit and/or bit stream, or the like.

In some embodiments, the second power supply unit 526 is further configured to convert DC power to AC power for supply to the second load 450. In some embodiments, the second load 450 may be one or more AC electric motors and/or prime movers of the vehicle associated with the power system 600.

In some embodiments, the first power supply unit 516 is configured to provide electric power to the detection unit 406 and the control unit 508. In some embodiments, the first power supply unit 516 is further configured to provide DC power to the detection unit 406 and the control unit 508. Therefore, in some embodiments, the first load 440 may comprise the detection unit 406 and the control unit 508. In some embodiments, the first load 440 of the first power supply unit 516 may further comprise other electronic components of the power system 600. For example, the first load 440 may further comprise one or more electronic components (such as control circuits) of the vehicle. In some examples, the first power supply unit 516 may supply an output DC voltage of about 12 volts (V) to the detection unit 406, the control unit 508, the other electronic components of the power system 600, and the first load 440.

In some embodiments, the power converter 500 further comprises a plurality of power lines. Specifically, the plurality of power lines comprises a first power line 510 and a second power line 520. The first power line 510 electrically connects the first power input terminal 514 to the first power supply unit 516. The second power line 520 electrically connects the second power input terminal 524 to the second power supply unit 526.

In some embodiments, the power converter 500 further comprises a plurality of return lines. Specifically, the plurality of return lines comprises a first return line 530 and a second return line 540. The first return line 530 electrically connects the first ground input terminal 512 to the first power supply unit 516. The second return line 540 electrically connects the second ground input terminal 522 to the second power supply unit 526.

The power system 600 comprises a plurality of ground connection lines. Specifically, the plurality of ground connection lines comprises a first ground connection line 532 and a second ground connection line 534. The first ground connection line 532 electrically connects the first ground input terminal 512 with the first ground terminal 412 of the first power source 410. The second ground connection line 534 electrically connects the second ground input terminal 522 with the second ground terminal 422 of the second power source 420.

The detection unit 406 of the safety circuit 400 of the power converter 500 is configured to detect an electrical disconnection in each of the first and second ground connection lines 532, 534. Specifically, the detection unit 406 of the safety circuit 400 of the power converter 500 is configured to detect an electrical disconnection (e.g., the electrical disconnection 533 shown in Fig. 4) in the first ground connection line 532 and an electrical disconnection (e.g., the electrical disconnection 535 shown in Fig. 6) in the second ground connection line 534.

The power system 600 further comprises a plurality of power connection lines. Specifically, the plurality of power connection lines comprises a first power connection line 542 and a second power connection line 544. The first power connection line 542 electrically connects the first output terminal 414 of the first power source 410 to the first power input terminal 514. The second power connection line 544 electrically connects the second output terminal 424 of the second power source 420 to the second power input terminal 524.

For the purpose of description, electric currents flowing through certain components and lines in the power system 600 are referred to by corresponding symbols. In the illustrated embodiment of Fig. 2, an electric current flowing through the first power source 410 is referred to as Ibatl. An electric current flowing through the second power source 420 is referred to as Ibat2. An electric current flowing through the detection node 402 is referred to as Idet. During normal operation of the power system 600 or a normal state without any electrical disconnection as shown in Fig. 2, Idet is substantially equal to zero (i.e., Idet = 0). An electric current flowing through the first power line 510 is referred to as Ipsl. An electric current flowing through the first return line 530 may be substantially equal to the electric current flowing through and first power line 510, and may also be referred to as Ipsl. An electric current flowing through the second power line 520 is referred to as Ip2. An electric current flowing through the first ground connection line 532 is referred to as Ipfl. An electric current flowing through the second ground connection line 534 is referred to as Ipf2.

Fig. 3 illustrates a schematic view of the safety circuit 400 of the power converter 500 shown in Fig. 2. Some components have been omitted for clarity purposes.

In some embodiments, each of the first resistor 418 and the second resistor 428 has a resistance value of greater than about 20 ohms and less than about 200 ohms. In some embodiments, each of the first resistor 418 and the second resistor 428 has a substantially equal resistance value. In some embodiments, each of the first resistor 418 and the second resistor 428 has a resistance value of about 100 ohms. In some cases, the resistance value of each of the first resistor 418 and the second resistor 428 may be selected such that the first and second ground input terminals 512, 522 of the power converter 500 (shown in Fig. 2) are not electrically isolated. In some embodiments, each of the first resistor 418 and the second resistor 428 may have a fixed value of resistance or a variable value of resistance. Further, each of the first resistor 418 and the second resistor 428 may comprise any suitable type of electrical resistor, for example, an axial-lead resistor, a printed resistor, a film -based resistor, and so forth. Each of the first resistor 418 and the second resistor 428 may comprise carbon, metal, ceramic, or combinations thereof.

The first resistor 418 and the second resistor 428 are disposed in the first and second detection lines 434, 444, respectively, such that, in case of an electrical disconnection between the first ground terminals 412 and the first ground input terminal 512 or in case of an electrical disconnection between the second ground terminals 422 and the second ground input terminal 522, a magnitude of a maximum current flowing through the detection node 402 is below a predetermined threshold. In some embodiments, the predetermined threshold is less than or equal to 3 amperes (A). In some embodiments, the predetermined threshold is less than or equal to 2 amperes, less than or equal to 1 ampere, less than or equal to 0.5 ampere, or less than or equal to 0.25 ampere. In some cases, the resistance value of the first resistor 418 and the second resistor 428 may be selected based on the predetermined threshold.

Specifically, in case of an electrical disconnection in the first ground connection line 532 or an electrical disconnection in the second ground connection line 534, the first and second resistors 428, 428 may ensure that a magnitude of a maximum value of the electric current Idet is less than or equal to a predetermined threshold Th, i.e., max( | Idet I ) < Th. In some cases, Th is less than or equal to 3 amperes, i.e., Th < 3A.

In some other cases, Th is less than or equal to 2 amperes, less than or equal to 1 ampere, less than or equal to 0.5 ampere, or less than or equal to 0.25 ampere. The predetermined threshold Th may be selected based on various parameters, e.g., a rating of wires forming the first and second ground connection lines 532, 534. Since the first power source 410 (shown in Fig. 2) may have a generally lower voltage output, the rating of the one or more wire forming the first ground connection line 532 may also be low, for example, less than or equal to 3A. In such cases, Th < 3A, such that in case of an electric disconnection in the second ground connection line 534, a maximum current flowing through the first ground connection line

532 is below the rating of the corresponding wires, i.e., less than or equal to 3A.

As discussed above, the detection unit 406 of the safety circuit 400 of the power converter 500 is configured to detect an electrical disconnection in the first ground connection line 532 and an electrical disconnection in the second ground connection line 534. Specifically, the detection unit 406 may be configured to detect the electrical disconnection (e.g., the electrical disconnection 533 or the electrical disconnection 535) based on a detection of a non-zero current at the detection node 402 (Idet 0). The non-zero current at the detection node 402 may indicate the electrical disconnection. In the illustrated embodiment of Figs. 2 and 3, there is no electrical disconnection in the first and second ground connection fines 532, 534. Therefore, a current value at the detection node 402 may be zero (Idet = 0).

Fig. 4 shows another schematic view of the power system 600 of Fig 2 in a first electrical disconnection state 536. Fig. 5 shows another schematic view of the safety circuit 400 of Fig 3 in the first electrical disconnection state 536. In the first electrical disconnection state 536, the electrical disconnection 533 is present in the first ground connection line 532.

Referring to Figs. 4 and 5, in case of the electrical disconnection

533 in the first ground connection line 532, the first power source 410 is configured to supply electric power to the first power supply unit 516 via the first power connection line 542 and the first power input terminal 514.

Further, in case of the electrical disconnection 533 in the first ground connection line 532, an electrical return path RP1 from the first power supply unit 516 to the first ground terminal 412 of the first power source 410 comprises the first detection line 434, the detection node 402, the second detection line 444, the second ground input terminal 522, the second ground connection line 534, the second ground terminal 422 of the second power source 420, and the common ground 430. The electrical return path RP1 further comprises the first return line 530. Further, as the first return line 530 may provide the electrical return path RP1 from the first power supply unit 516 to the first ground terminal 412 of the first power source 410, a separate return path for supplying current to the first power supply unit 516 may not be required in case of the electrical disconnection 533 in the first ground connection line 532. Therefore, the first power supply unit 516 may supply electric power from the first power source 410 to the first load 440 even in case of the electrical disconnection 533 in the first ground connection line 532. In other words, the first power supply unit 516 may supply electric power from the first power source 410 to the detection unit 406 and the control unit 508 even in case of the electrical disconnection 533 in the first ground connection line 532.

Fig. 6 shows another schematic view of the power system 600 of Fig 2 in a second electrical disconnection state 537. Fig. 7 shows another schematic view of the safety circuit 400 of Fig 3 in the second electrical disconnection state 537. In the second electrical disconnection state 537, the electrical disconnection 535 is present in the second ground connection line 534.

Referring to Figs. 4 and 5, in case of the electrical disconnection 535 in the second ground connection line 534, a magnitude of a maximum electric current flowing through the first ground connection line 532 is less than or equal to 3 amperes.

Further, in case of the electrical disconnection 535 in the second ground connection line 534, an electrical return path RP2 from the second power supply unit 526 to the second ground terminal 422 of the second power source 420 comprises the second detection line 444, the detection node 402, the first detection line 434, the first ground input terminal 512, the first ground connection line 532, the first ground terminal 412 of the first power source 410, and the common ground 430. The electrical return path RP2 further comprises the second return line 540.

Now referring to Figs. 2 to 7, Table 1 below provides exemplary values of current through different lines of the power system 600 in different states, i.e., a normal state (shown in Fig. 2), the first electrical disconnection state 536, and the second electrical disconnection state 537.

Table 1

It may be observed that at the normal state (no electrical disconnection in the first and second ground connection lines 532, 534), the current at the detection node 402 is zero. A value of current through the first power source (Ibatl) is 2 amperes. Therefore, a value of current through the first power line 510 and the first ground connection line 532 is also 2 amperes. In other words, Ipsl and Ipfl is 2 amperes. Therefore, the first power line 510 and the first ground connection line 532 may be configured for low current transmissions. In other words, a rating of wires forming the first ground connection fine 532 and the first power line 510 may be low.

A value of current through the first power source (Ibat2) is greater than 100 amperes. Therefore, a value of current through the second power line 520 and the second ground connection line 534 is also greater than 100 amperes. In other words, Ip2 and Ipf2 is greater than 100 amperes. Therefore, the second power line 520 and the second ground connection line 534 may be configured for high current transmissions. In other words, a rating of wires forming the second ground connection line 534 and the second power line 520 may be high.

In the first electrical disconnection state 536, there may be the electrical disconnection 533 in the first ground connection line 532. Therefore, the current Ipfl through the first ground connection line 532 is 0A. As discussed above, in the first electrical disconnection state 536, the electrical return path RP1 from the first power supply unit 516 to the first ground terminal 412 of the first power source 410 comprises the first detection line 434, the detection node 402, the second detection line 444, the second ground input terminal 522, the second ground connection line 534, the second ground terminal 422 of the second power source 420, and the common ground 430.

In the second electrical disconnection state 537, there may be the electrical disconnection 535 in the second ground connection line 534. Therefore, the current Ipf2 through the second ground connection line 534 is 0A. As discussed above, in the second electrical disconnection state 537, the electrical return path RP2 from the second power supply unit 526 to the second ground terminal 422 of the second power source 420 comprises the second detection line 444, the detection node 402, the first detection line 434, the first ground input terminal 512, the first ground connection fine 532, the first ground terminal 412 of the first power source 410, and the common ground 430.

Therefore, in both the first and second electrical disconnection states 536, 537, both the electrical return paths RP1, RP2 comprise the first detection line 434, the detection node 402, the second detection line 444. In both the first and second electrical disconnection states 536, 537, the detection unit 406 may detect the electrical disconnection (e.g., the first and second electrical disconnection 533, 535) based on the detection of the nonzero current at the detection node 402 (Idet 0). Specifically, in case of the electrical disconnection 533, the current through the detection node Idet may be > -2A, and in case of the electrical disconnection 535, the current through the detection node Idet may be > 0A.

Further, in the second electrical disconnection state 537, the current through the first ground connection line 532 is less than 3 amperes. This may be because the large currents from the second power line 520 are not directly transmitted to the first ground connection line 532. On the contrary, the first and second resistors 418, 428 in the first and second detection lines 434, 444, respectively, may limit the maximum current flowing through the first ground connection line 532. This may further decrease the current Ip2 through the second power line 520. However, this may ensure that the magnitude of the maximum current flowing through the first ground connection line 532, which may be configured for low current transmissions, is below the predetermined threshold (Th < 3A).

In an example, where the first power source 410 is a voltage source providing the first output voltage of 12V, the second power source 420 is providing the second output voltage of 48V, the first resistor 418 has a resistance value of 100Q, and the second resistor 428 has a resistance value of 100Q, a magnitude of Ipfl is calculated as (48V)/200Q, i.e., 240mA. Therefore, Ipfl has a low magnitude which is less than power ratings of wires used with the first power source 410.

Hence, the power converter 500 and the power system 600 comprising the safety circuit 400 of the present disclosure may not require a quick detection of the electrical disconnection 535 or quick response upon detection of the electrical disconnection 535 to prevent the unsafe condition. Therefore, the power converter 500 and the power system 600 may be intrinsically safe. The power converter 500 and the power system 600 comprising the safety circuit 400 may not require any additional components, and complex algorithms to detect the electrical disconnection in order to prevent unsafe conditions. This may further decrease a processing load on the processor of the control unit 508 of the power system 600. In some cases, the detection unit 406 may comprise the processor. Further, the first and second resistors 418, 428 may be simple, robust, and cheap electrical components. Therefore, implementation of the safety circuit 400 in the power converter 500 and the power system 600 may be cost-effective.

Therefore, the present invention provides an improved safety circuit, an improved power converter, and an improved power system which may be intrinsically safe and reliable, and may have a lower cost and complexity than conventional isolated systems.

An aspect of the present disclosure provides a safety circuit for a plurality of power sources having respective ground terminals electrically connected to a common ground and to respective ground input terminals of a power converter is provided. The safety circuit comprises a detection node, detection lines, a detection unit, and resistors. The detection lines electrically connect respective ground input terminals of the power converter to the detection node. The detection unit is electrically connected to the detection node and detects an electrical disconnection between each of the respective ground terminals of the plurality of power sources and the respective ground input terminal of the power converter. At least one resistor is disposed in each detection line, such that, in case of an electrical disconnection between one of the ground terminals and the respective ground input terminal, a magnitude of a maximum current flowing through the detection node is below a predetermined threshold.

The various embodiments which are described above may be used implemented independently from one another and may be combined with one another in various ways. The reference numbers used in the detailed description and the claims do not limit the description of the embodiments nor do they limit the claims. The reference numbers are solely used to clarify.

In the claims, the word “comprising” does not exclude other elements or steps, and the indefinite article “a” or “an” does not exclude a plurality. A single processor, element or other unit may fulfill the functions of several items recited in the claims. The mere fact that certain measures are recited in mutually different dependent claims does not indicate that a combination of these measures cannot be used to advantage.

In the present disclosure, the expression “at least one of A, B and C” means “A, B, and/or C”, and that it suffices if, for example, only B is present. A single element or other unit may fulfill the functions of several items recited in the claims. The mere fact that certain measures are recited in mutually different dependent claims does not indicate that a combination of these measures cannot be used to advantage.

Any reference signs in the claims should not be construed as limiting the scope.

Although the invention has been elucidated herein with reference to figures and embodiments, these do not limit the scope of the invention as defined by the claims. The skilled person having the benefit of the present disclosure shall appreciate that many variations, combinations and extensions are possible within said scope. Legend 0 Safety Circuit 2 Detection Node 4 Detection Lines 6 Detection Unit 7 Signals 8 Resistors 0 Power Sources 2 Ground Terminals 4 Output Terminals 0 Common Ground 0 Loads 0 Power Converter 2 Ground Input Terminals4 Power Input Terminals6 Power Supply Units 8 Control Unit 0 Power Lines 0 Return Lines 0 Ground Connection Lines0 Power Connection Lines0 Power System 0 Safety Circuit 2 Detection Node 4 First Detection Line 4 Second Detection Line6 Detection Unit 7 Signals 8 First Resistor 8 Second Resistor First Power Source Second Power Source First Ground Terminal Second Ground Terminal First Output Terminal Second Output Terminal Common Ground First Load Second Load Power Converter First Ground Input Terminal Second Ground Input Terminal First Power Input Terminal Second Power Input Terminal First Power Supply Unit Second Power Supply Unit Control Unit First Power Line Second Power Line First Return Line Second Return Line First Ground Connection Line Electrical Disconnection Second Ground Connection Line Electrical Disconnection First Electrical Disconnection State Second Electrical Disconnection State First Power Connection Line Second Power Connection Line Power System Ibatl Current Through First Power Source

Ibat2 Current Through Second Power Source

Idet Current Through Detection Node

Ipsl Current Through First Power Line

Ip2 Current Through Second Power Line

Ipfl Current Through First Ground Connection Line

Ipf2 Current Through Second Ground Connection Line

RP1 Electrical Return Path

RP2 Electrical Return Path

Claims

36 Claims

1. A safety circuit for a plurality of power sources having respective ground terminals electrically connected to a common ground and to respective ground input terminals of a power converter, the safety circuit comprising: a detection node; a plurality of detection lines electrically connecting respective ground input terminals of the power converter to the detection node; a detection unit electrically connected to the detection node and configured to detect an electrical disconnection between each of the respective ground terminals of the plurality of power sources and the respective ground input terminal of the power converter; and a plurality of resistors disposed in the plurality of detection lines, wherein at least one resistor from the plurality of resistors is disposed in each detection line, such that, in case of an electrical disconnection between one of the ground terminals and the respective ground input terminal, a magnitude of a maximum current flowing through the detection node is below a predetermined threshold.

2. The safety circuit of claim 1, wherein the plurality of resistors has a substantially equal resistance value.

3. The safety circuit of claim 1 or 2, wherein a resistance value of each resistor is greater than about 20 ohms and less than about 200 ohms. 37

4. The safety circuit of any one of the preceding claims, wherein the predetermined threshold is less than or equal to 3 amperes.

5. The safety circuit of any one of the preceding claims, wherein the detection unit is configured to detect the electrical disconnection based on a detection of a non-zero current at the detection node.

6. A power converter comprising: a plurality of ground input terminals electrically connected to respective ground terminals of a plurality of power sources; a plurality of power input terminals electrically connected to respective output terminals of the plurality of power sources; a plurality of power supply units electrically connected to respective ground input terminals and respective power input terminals, wherein each power supply unit is configured to supply electric power from a respective power source from the plurality of power sources to a respective load; and the safety circuit of any one of the preceding claims, wherein each detection line electrically connects a respective ground input terminal from the plurality of ground input terminals to the detection node .

7. The power converter of claim 6, further comprising a control unit communicably coupled to the detection unit and at least one power supply unit from the plurality of power supply units, wherein the control unit is configured to control the at least one power supply unit based, at least in part, on signals received from the detection unit.

8. The power converter of claim 7, wherein the at least one power supply unit from the plurality of power supply units is further configured to convert direct current (DC) power to alternating current (AC) power for supply to the respective load.

9. The power converter of claim 7 or 8, wherein one power supply unit from the plurality of power supply units is configured to provide electric power to the detection unit and the control unit.

10. The power converter of claim 9, wherein the one power supply unit is further configured to provide DC power to the detection unit and the control unit.

11. The power converter of any one of claims 6 to 10, further comprising a plurahty of power lines electrically connecting a respective power input terminal from the plurality of power input terminals to a respective power supply unit from the plurality of power supply units.

12. The power converter of any one of claims 6 to 11, further comprising a plurahty of return lines electrically connecting a respective ground input terminal from the plurality of ground input terminals to a respective power supply unit from the plurality of power supply units.

13. A power system comprising: a plurality of power sources, wherein each power source comprises an output terminal and a ground terminal; a common ground electrically connected to the ground terminal of each power source; the power converter of any one of claims 6 to 12; a plurality of ground connection lines, wherein each ground connection line electrically connects the ground terminal of a respective power source from the plurality of power sources to a respective ground input terminal from the plurality of ground input terminals of the power converter; and a plurality of power connection lines, wherein each power connection line electrically connects the output terminal of a respective power source from the plurality of power sources to a respective power input terminal from the plurality of power input terminals of the power converter; wherein the detection unit of the safety circuit of the power converter is configured to detect an electrical disconnection in each ground connection line.

14. The power system of claim 13, wherein: the plurality of power sources comprises a first power source and a second power source; the first power source comprises a first output terminal and a first ground terminal, the first power source being a voltage source configured to provide a first output voltage at the first output terminal; and the second power source comprises a second output terminal and a second ground terminal, the second power source being a voltage source configured to provide a second output voltage at the second output terminal different from the first output voltage.

15. The power system of claim 14, wherein the first output voltage is about 12 volts, and wherein the second output voltage is about 48 volts.

16. The power system of any one of claims 13 to 15, wherein: the plurality of ground input terminals comprises a first ground input terminal and a second ground input terminal; the plurality of power input terminals comprises a first power input terminal and a second power input terminal; the plurality of ground connection lines comprises a first ground connection line electrically connecting the first ground input terminal with the first ground terminal of the first power source and a second ground connection line electrically connecting the second ground input terminal with the second ground terminal of the second power source; the plurality of detection lines comprises a first detection line electrically connecting the first ground input terminal to the detection node and a second detection line electrically connecting the second ground input terminal to the detection node; the plurality of resistors comprises a first resistor disposed in the first detection line and a second resistor disposed in the second detection line; the plurality of power connection lines comprises a first power connection line electrically connecting the first output terminal of the first power source to the first power input terminal and a second power connection line electrically connecting the second output terminal of the second power source to the second power input terminal; and the plurality of power supply units comprises a first power supply unit and a second power supply unit, wherein the first power supply unit is electrically connected to the first ground input terminal and the first power input terminal, and wherein the second power supply unit is electrically connected to the second ground input terminal and the second power input terminal. 41

17. The power system of claim 16, wherein each of the first resistor and the second resistor has a resistance value of about 100 ohms.

18. The power system of claim 16 or 17, wherein, in case of an electrical disconnection in the first ground connection line: the first power source is configured to supply electric power to the first power supply unit via the first power connection line and the first power input terminal; and an electrical return path from the first power supply unit to the first ground terminal of the first power source comprises the first detection line, the detection node, the second detection line, the second ground input terminal, the second ground connection line, the second ground terminal of the second power source, and the common ground.

19. The power system of any one of claims 16 to 18, wherein, in case of an electrical disconnection in the second ground connection line, a magnitude of a maximum electric current flowing through the first ground connection line is less than or equal to 3 amperes.

20. The power system of claim 19, wherein, in case of the electrical disconnection in the second ground connection line, an electrical return path from the second power supply unit to the second ground terminal of the second power source comprises the second detection line, the detection node, the first detection line, the first ground input terminal, the first ground connection line, the first ground terminal of the first power source, and the common ground.