Patent Publication Number: US-2023160976-A1

Title: Detection circuit for on-board direct current/direct current (dc/dc) ground wire and on-board device

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation of under 35 U.S.C. § 120 International Application No. PCT/CN2020/101311, filed Jul. 10, 2020, the entire disclosure of which is incorporated herein by reference. 
    
    
     TECHNICAL FIELD 
     This disclosure relates to the field of electronic circuits technology, and in particular to a detection circuit for an on-board direct current/direct current (DC/DC) ground wire and an on-board device. 
     BACKGROUND 
     At present, new energy vehicles have been increasingly recognized due to requirements of environmental protection, and uses of the new energy vehicles are increasingly popular. Since a new energy vehicle uses a power lithium battery to drive a motor to obtain power, a direct current generator driven by an internal combustion engine through a belt is no longer used, but is replaced by an on-board DC/DC converter. 
     However, since a load of a low-voltage electric apparatus of the whole vehicle ranges from 1 KW to 3 KW, the on-board DC/DC converter also needs to have an ability to provide an output ranging from 1 KW to 3 KW, and an output current ranges from 70 A to 200 A. Due to a relatively large current, a required output copper cable also has a relatively large cross-sectional area, and is expensive. In order to save costs, a positive electrode of the on-board DC/DC converter is connected with a low-voltage storage battery generally through only one output wire, a negative electrode of the on-board DC/DC converter is directly connected with a vehicle frame through a nearby a ground wire, and the low-voltage storage battery is also connected with the vehicle frame through a nearby ground wire. An output current of the on-board DC/DC converter flows from the positive electrode of the on-board DC/DC converter to the low-voltage storage battery through the output wire, and then flows back to the on-board DC/DC converter through a ground wire of a negative electrode of the low-voltage storage battery, a vehicle body, and a DC/DC ground wire. 
     However, this wiring manner has a side effect as follows. The low-voltage storage battery is required to supply power for the on-board DC/DC converter. A standby circuit for the on-board DC/DC converter has a positive input and a negative input. The positive input of the standby circuit is controlled by an on-board controller to be on or off to control a DC/DC to be on or off, and the negative input of the standby circuit is connected with the vehicle body by being connected with the negative electrode of the low-voltage storage battery. If the DC/DC ground wire or the ground wire of the low-voltage storage battery is in poor contact with the vehicle body, a relatively large impedance or even a disconnection may occur between the DC/DC ground wire or the ground wire of the low-voltage storage battery and the vehicle body, thereby resulting in a current of hundreds of amperes flowing back to the DC/DC through a shielding layer or a negative wire of the standby circuit. Finally, a wiring harness will be heated seriously until the wiring harness is burned up. 
     SUMMARY 
     In a first aspect, a detection circuit for an on-board DC/DC ground wire is provided in implementations of the present disclosure. The detection circuit for the on-board DC/DC ground wire includes a digital signal process (DSP) controller, a detection circuit, a standby circuit for an on-board DC/DC converter, and a power-supply negative wire for the on-board DC/DC converter. The DSP controller is connected with the detection circuit. The detection circuit is connected with the standby circuit for the on-board DC/DC converter and the power-supply negative wire for the on-board DC/DC converter respectively. The detection circuit is further connected with an external input voltage. The detection circuit includes a comparator, a first conductive branch, a second conductive branch, and a third conductive branch. The comparator includes a positive input end and a negative input end. The positive input end is connected with the second conductive branch. The negative input end is connected with the first conductive branch. 
     In a second aspect, an on-board device is provided in the present disclosure. The on-board device includes a detection circuit for an on-board DC/DC ground wire. The detection circuit for the on-board DC/DC ground wire includes a DSP controller, a detection circuit, a standby circuit for an on-board DC/DC converter, and a power-supply negative wire for the on-board DC/DC converter. The DSP controller is connected with the detection circuit. The detection circuit is connected with the standby circuit for the on-board DC/DC converter and the power-supply negative wire for the on-board DC/DC converter respectively. The detection circuit is further connected with an external input voltage. The detection circuit includes a comparator, a first conductive branch, a second conductive branch, and a third conductive branch. The comparator includes a positive input end and a negative input end. The positive input end is connected with the second conductive branch. The negative input end is connected with the first conductive branch. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       In order to more clearly explain technical situations in implementations or the related art of the present disclosure, the following will briefly introduce accompanying drawings involved in implementations or the related art of the present disclosure. 
         FIG.  1    is a schematic structural diagram of a wiring circuit for a ground wire of an on-board direct current/direct current (DC/DC) converter provided in implementations of the present disclosure. 
         FIG.  2    is a schematic structural diagram of a detection circuit for an on-board DC/DC ground wire provided in implementations of the present disclosure. 
         FIG.  3    is a schematic structural diagram of a detection circuit provided in implementations of the present disclosure. 
         FIG.  4    is a schematic structural diagram of a detection circuit for an on-board DC/DC ground wire provided in other implementations of the present disclosure. 
         FIG.  5    is a schematic diagram of an on-board device provided in implementations of the present disclosure. 
     
    
    
     DETAILED DESCRIPTION 
     In order to make those of ordinary skill in the art better understand technical solutions of the present disclosure, technical solutions of implementations of the present disclosure will be described clearly and completely with reference to accompanying drawings in implementations. Apparently, implementations described hereinafter are merely some implementations, rather than all implementations of the present disclosure. All other implementations obtained by those of ordinary skill in the art based on implementations without creative efforts shall fall within the protection scope of the present disclosure. 
     The terms “first”, “second”, and the like used in the specification, the claims, and the accompany drawings of the present disclosure are used to distinguish different objects rather than describe a particular order. The terms “include”, “comprise”, and “have” as well as variations thereof are intended to cover non-exclusive inclusion. For example, a process, system, product, or device including a series of steps or units is not limited to the listed steps or units, on the contrary, it can optionally include other steps or units that are not listed; alternatively, other steps or units inherent to the process, product, or device can be included either. 
     The term “implementation” referred to herein means that particular features, structures, or properties described in conjunction with implementations may be defined in at least one implementation of the present disclosure. The phrase “implementation” appearing in various places in the specification does not necessarily refer to the same implementation or an independent/alternative implementation that is mutually exclusive with other implementations. Those of ordinary skill in the art will understand expressly and implicitly that an implementation described herein may be combined with other implementations. 
     In order to better explain implementations of the present disclosure, a large current in implementations of the present disclosure may mean that an electronic component in a circuit consumes a larger current than normal, and a range of the large current has exceeded a standard current, which is an electronic fault phenomenon. 
     A detection circuit for an on-board direct current/direct current (DC/DC) ground wire is provided in implementations of the present disclosure, which is beneficial to detecting a disconnection of a ground wire and avoiding a wiring harness from being burned up due to a continuous output of an excessive current. 
     In a first aspect, a detection circuit for an on-board DC/DC ground wire is provided in implementations of the present disclosure. The detection circuit for the on-board DC/DC ground wire includes a digital signal process (DSP) controller, a detection circuit, a standby circuit for an on-board DC/DC converter, and a power-supply negative wire for the on-board DC/DC converter. The DSP controller is connected with the detection circuit. The detection circuit is connected with the standby circuit for the on-board DC/DC converter and the power-supply negative wire for the on-board DC/DC converter respectively. The detection circuit is further connected with an external input voltage. The detection circuit includes a comparator, a first conductive branch, a second conductive branch, and a third conductive branch. The comparator includes a positive input end and a negative input end. The positive input end is connected with the second conductive branch. The negative input end is connected with the first conductive branch. 
     In an implementation, the first conductive branch includes a first resistor, a second resistor, and a first capacitor. The first resistor has one end connected with the external input voltage. The first resistor has another end connected with the negative input end of the comparator, one end of the second resistor, and one end of the first capacitor. Another end of the second resistor and another end of the first capacitor are grounded. 
     In an implementation, the second conductive branch includes a third resistor, a fourth resistor, and a second capacitor. The third resistor has one end connected with the external input voltage. The third resistor has another end connected with one end of the fourth resistor, the positive input end of the comparator, and one end of the second capacitor. Another end of the fourth resistor and another end of the second capacitor are connected with the power-supply negative wire for the on-board DC/DC converter. 
     In an implementation, the third conductive branch includes a fifth resistor. The fifth resistor has one end connected with the standby circuit for the on-board DC/DC converter and grounded. The fifth resistor has another end connected with the power-supply negative wire for the on-board DC/DC converter. 
     In an implementation, the first conductive branch and the second conductive branch are connected with the external input voltage. The second conductive branch is connected with the third conductive branch and the power-supply negative wire for the on-board DC/DC converter. 
     In an implementation, the comparator is a voltage comparator. A positive input voltage of the comparator is supplied from the external input voltage via a third resistor and a fourth resistor, and a negative input voltage of the comparator is supplied from the external input voltage via a first resistor and a second resistor. 
     In an implementation, the DSP controller is configured to control the standby circuit for the on-board DC/DC converter to be on or off. 
     In an implementation, the DSP controller is further configured to control the standby circuit for the on-board DC/DC converter to increase or reduce an output current. 
     In a second aspect, an on-board device is provided in the present disclosure. The on-board device includes a detection circuit for an on-board DC/DC ground wire. The detection circuit for the on-board DC/DC ground wire includes a DSP controller, a detection circuit, a standby circuit for an on-board DC/DC converter, and a power-supply negative wire for the on-board DC/DC converter. The DSP controller is connected with the detection circuit. The detection circuit is connected with the standby circuit for the on-board DC/DC converter and the power-supply negative wire for the on-board DC/DC converter respectively. The detection circuit is further connected with an external input voltage. The detection circuit includes a comparator, a first conductive branch, a second conductive branch, and a third conductive branch. The comparator includes a positive input end and a negative input end. The positive input end is connected with the second conductive branch. The negative input end is connected with the first conductive branch. 
     In implementations of the present disclosure, the detection circuit for the on-board DC/DC ground wire includes the DSP controller, the detection circuit, the standby circuit for the on-board DC/DC converter, and the power-supply negative wire for the on-board DC/DC converter. The DSP controller is connected with the detection circuit. The detection circuit is connected with the standby circuit for the on-board DC/DC converter and the power-supply negative wire for the on-board DC/DC converter respectively. The detection circuit is further connected with the external input voltage. The detection circuit includes the comparator, the first conductive branch, the second conductive branch, and the third conductive branch. The comparator includes the positive input end and the negative input end. The positive input end is connected with the second conductive branch. The negative input end is connected with the first conductive branch. In this way, the detection circuit is connected between the DSP controller and the standby circuit for the on-board DC/DC converter, and the detection circuit is connected between the DSP controller and the power-supply negative wire for the on-board DC/DC converter. Once the ground wire of the DC/DC converter is in poor contact with or even disconnected with the vehicle body, or the ground wire of the low-voltage storage battery is in poor contact with or even disconnected with the vehicle body, a current of hundreds of amperes is generated, the detection circuit can detect a large current in the power-supply negative wire for the on-board DC/DC converter due to a disconnection or a poor contact of the ground wire of the DC/DC converter, thereby avoiding the wiring harness from being burned up due to the continuous output of the large current. 
     Reference can be made to  FIG.  1   , which is a schematic structural diagram of a wiring circuit for a ground wire of an on-board DC/DC converter provided in implementations of the present disclosure. The wiring circuit may include a power battery  101 , an on-board DC/DC converter  102 , a vehicle controller  103 , and a storage battery  104 . The power battery  101  is connected with the on-board DC/DC converter  102  through a high-voltage cable shielding layer. The on-board DC/DC converter  102  is connected with a negative electrode of the storage battery  104  through a power-supply negative wire for the on-board DC/DC converter. The on-board DC/DC converter  102  is connected with the vehicle controller  103  through a power-supply positive wire for the on-board DC/DC converter. The vehicle controller  103  is connected with a positive electrode of the storage battery  104 . The positive electrode of the storage battery  104  is connected with the on-board DC/DC converter  102  through an on-board DC/DC positive output wire. The negative electrode of the storage battery  104  is connected with a vehicle frame or a vehicle body through a storage-battery ground wire. The on-board DC/DC converter  102  is connected with the vehicle frame or the vehicle body through a DC/DC ground wire. The high-voltage cable shielding layer is connected with the vehicle frame or the vehicle body through a ground wire. The high-voltage cable shielding layer is connected with the vehicle frame or the vehicle body to keep a shielding effect. The storage battery  104  is configured to supply power for the on-board DC/DC converter  102 . The vehicle controller  103  is configured to control the on-board DC/DC converter  102  to be on or off. 
     Optionally, an operation principle of the wiring circuit for the ground wire of the on-board DC/DC converter illustrated in  FIG.  1    is as follows. In normal cases, the on-board DC/DC converter  102  is connected with the vehicle frame or the vehicle body through one DC/DC ground wire, and the storage battery  104  is connected with the vehicle frame or the vehicle body through one storage-battery ground wire. An output current of the on-board DC/DC converter  102  flows from the positive electrode of the on-board DC/DC converter  102  to the storage battery  104  through the on-board DC/DC positive output wire, and then flows back to the on-board DC/DC converter  102  through the storage-battery ground wire, the vehicle body or the vehicle frame, and the DC/DC ground wire. 
     In the wiring circuit illustrated in  FIG.  1   , the storage battery  104  is required to supply power for the on-board DC/DC converter  102 . In the meanwhile, a standby circuit is inside the on-board DC/DC converter  102 , and the standby circuit has a positive input and a negative input. The positive input of the standby circuit is controlled by the vehicle controller  103  to be on or off, so as to control the on-board DC/DC converter  102  to be on or off. The negative input of the standby circuit inside the on-board DC/DC converter  102  is connected with the vehicle body by being connected with the negative electrode of the storage battery  104 . In abnormal cases, if the DC/DC ground wire is in poor contact with the vehicle body or the vehicle frame, or the storage-battery ground wire of the storage battery  104  is in poor contact with the vehicle body or the vehicle frame, a relatively large impedance or even a disconnection of the storage-battery ground wire may occur between the DC/DC ground wire or the storage-battery ground wire of the storage battery  104  and the vehicle body or the vehicle frame. Finally, a current of hundreds of amperes flowing back to the on-board DC/DC converter  102  through the high-voltage cable shielding layer or a negative wire of the standby circuit for the on-board DC/DC converter  102 , thereby resulting in severe heating of the wiring harness until the wiring harness is burned up. 
     Implementations of the present disclosure are described in detail below in combination with the accompanying drawings. 
     Reference can be made to  FIG.  2   , which is a schematic structural diagram of a detection circuit for an on-board DC/DC ground wire provided in implementations of the present disclosure. The detection circuit for the on-board DC/DC ground wire  200  includes a DSP controller  201 , a detection circuit  202 , a standby circuit for the on-board DC/DC converter  203 , and a power-supply negative wire for the on-board DC/DC converter  204 . The DSP controller  201  is connected with the detection circuit  202 . The detection circuit  202  is connected with the standby circuit for the on-board DC/DC converter  203  and the power-supply negative wire for the on-board DC/DC converter  204  respectively. The detection circuit  202  is also connected with an external input voltage. 
     In addition, the DSP controller  201  may be configured to control the standby circuit for the on-board DC/DC converter  203  to increase or reduce an output current and may be configured to control an on or off state of the standby circuit for the on-board DC/DC converter  203 . The detection circuit  202  may be configured to detect an operation of the standby circuit for the on-board DC/DC converter  203 . For example, the detection circuit  202  may be configured to detect the disconnection or the poor contact of the ground wire in the standby circuit for the on-board DC/DC converter  203 . 
     Optionally, the detection circuit for the on-board DC/DC ground wire  200  illustrated in the schematic structural diagram of  FIG.  2    can detect an abnormal case of the wiring circuit of the ground wire connected with the on-board DC/DC converter  102  illustrated in  FIG.  1   , such as, the disconnection or the poor contact of the ground wire. Specifically, in implementations of the present disclosure, the detection circuit  202  is connected between the DSP controller  201  and standby circuit for the on-board DC/DC converter  203 , and the detection circuit  202  is connected between the DSP controller  201  and the power-supply negative wire for the on-board DC/DC converter  204 . Once the ground wire of the DC/DC converter  102  is in poor contact with or even disconnected with the vehicle body, or the ground wire of the storage battery is in poor contact with or even disconnected with the vehicle body, a current of hundreds of amperes is generated, the above detection circuit  202  can detect a large current in the power-supply negative wire for the on-board DC/DC converter  204  or a shielding wire due to the disconnection or the poor contact of the ground wire of the DC/DC converter  102 , thereby avoiding the wiring harness from being burned up due to a continuous output of the large current and avoiding an electronic fault phenomenon of the large current. 
     Reference can be made to  FIG.  3   , which is a schematic structural diagram of a detection circuit provided in implementations of the present disclosure. The detection circuit  202  includes a comparator  202 U, a first conductive branch  202   a , a second conductive branch  202   b , and a third conductive branch  202   c.    
     Optionally, the first conductive branch  202   a  includes first resistor R 1 , second resistor R 2 , and first capacitor C 1 . First resistor R 1  has one end connected with external input voltage VREF. First resistor R 1  has another end connected with a negative input end (i.e., a port  6 ) of the comparator  202 U, one end of second resistor R 2 , and one end of first capacitor C 1 . Another end of second resistor R 2  and another end of first capacitor C 1  are grounded. 
     Optionally, the second conductive branch  202   b  includes third resistor R 3 , fourth resistor R 4 , and second capacitor C 2 . Third resistor R 3  has one end connected with external input voltage VREF. Third resistor R 3  has another end connected with one end of fourth resistor R 4 , a positive input end (i.e., a port  5 ) of the comparator  202 U, and one end of second capacitor C 2 . Another end of fourth resistor R 4  and another end of second capacitor C 2  are connected with the power-supply negative wire for the on-board DC/DC converter. 
     Optionally, the third conductive branch  202   c  includes fifth resistor R 5 . Fifth resistor R 5  has one end connected with the standby circuit for the on-board DC/DC converter and grounded. Fifth resistor R 5  has another end connected with the power-supply negative wire for the on-board DC/DC converter. 
     Optionally, the first conductive branch  202   a  and the second conductive branch  202   b  are connected with the external input voltage. The second conductive branch  202   b  is connected with the third conductive branch  202   c  and the power-supply negative wire for the on-board DC/DC converter. 
     Optionally, the comparator  202 U in the above detection circuit for the on-board DC/DC ground wire  200  may include a voltage comparator, which is not specifically limited herein. A positive input voltage of the comparator  202 U is supplied from the external input voltage via third resistor R 3  and fourth resistor R 4 , and a negative input voltage of the comparator  202 U is supplied from the external input voltage via first resistor R 1  and second resistor R 2 . 
     Reference can be made to  FIG.  4   , which is a schematic structural diagram of a detection circuit for an on-board DC/DC ground wire provided in other implementations of the present disclosure. The detection circuit for the on-board DC/DC ground wire  200  includes a DSP controller  201 , a detection circuit  202 , a standby circuit for an on-board DC/DC converter  203 , a power-supply negative wire for the on-board DC/DC converter  204 , a storage battery  104 , a vehicle frame  205 , and a housing  206 . The detection circuit  202  includes a comparator  202 U, a first conductive branch  202   a , a second conductive branch  202   b , and a third conductive branch  202   c.    
     Optionally, the DSP controller  201  is connected with a port  7  of the comparator  202 U in the detection circuit  202 . The second conductive branch  202   b  of the detection circuit  202  is connected with an external input voltage. The third conductive branch  202   c  of the detection circuit  202  is connected with the standby circuit for the on-board DC/DC converter. The second conductive branch  202   b  of the detection circuit  202  and the third conductive branch  202   c  each are connected with the power-supply negative wire for the on-board DC/DC converter. The above detection circuit  202  can be connected with the housing  206  and the vehicle frame  205  through a second ground wire  208 . In implementations of the present disclosure, since the housing  206  and the vehicle frame  205  are connected with ground in a vehicle system, a connection with the housing or the vehicle frame is equivalent to grounding. 
     Optionally, the above standby circuit for the on-board DC/DC converter  203  is connected with a positive electrode of the storage battery  104 . The second conductive branch  202   b  and the third conductive branch  202   c  of the above detection circuit  202  are connected with a negative electrode of the storage battery  104  through the power-supply negative wire for the on-board DC/DC converter  204 . The negative electrode of the storage battery  104  is connected with the vehicle frame  205  through a first ground wire  207 , and the housing  206  is connected with the vehicle frame  205  through the second ground wire  208 . 
     The comparator  202 U includes a positive input end and a negative input end. The positive input end is connected with the second conductive branch  202   b , and the negative input end is connected with the first conductive branch  202   a.    
     Optionally, the first conductive branch  202   a  includes first resistor R 1 , second resistor R 2 , and first capacitor C 1 . First resistor R 1  has one end connected with external input voltage VREF. First resistor R 1  has another end connected with the negative input end (i.e., a port  6 ) of the comparator, one end of second resistor R 2 , and one end of first capacitor C 1 . Another end of second resistor R 2  and another end of first capacitor C 1  are connected with the vehicle frame. 
     Optionally, the second conductive branch  202   b  includes third resistor R 3 , fourth resistor R 4 , and second capacitor C 2 . Third resistor R 3  has one end connected with external input voltage VREF. Third resistor R 3  has another end connected with one end of fourth resistor R 4 , the positive input end (i.e., a port  5 ) of the comparator  202 U, and one end of second capacitor C 2 . Another end of fourth resistor R 4  and another end of second capacitor C 2  are connected with the power-supply negative wire for the on-board DC/DC converter  204 . 
     Optionally, the third conductive branch  202   c  includes fifth resistor R 5 . Fifth resistor R 5  has one end connected with the standby circuit for the on-board DC/DC converter  203  and the housing  206 . Fifth resistor R 5  has another end connected with the power-supply negative wire for the on-board DC/DC converter  204 . 
     Optionally, the first conductive branch  202   a  and the second conductive branch  202   b  are connected with the external input voltage. The second conductive branch  202   b  is connected with the third conductive branch  202   c  and the power-supply negative wire for the on-board DC/DC converter  204 . 
     Optionally, the comparator  202 U in the above detection circuit for the on-board DC/DC ground wire  200  may include a voltage comparator, which is not specifically limited herein. A positive input voltage of the comparator is supplied from the external input voltage via third resistor R 3  and fourth resistor R 4 , and a negative input voltage of the comparator  202 U is supplied from the external input voltage via first resistor R 1  and second resistor R 2 . 
     Optionally, the above fifth resistor R 5  has a resistance at a level of milliohm, such that a normal operation of the standby circuit for the on-board DC/DC converter will not be affected, and an abnormal operation of the DC/DC standby circuit will not occur. 
     Optionally, the above DSP controller  201  is configured to control the standby circuit for the on-board DC/DC converter  203  to be on or off, such that if the DC/DC ground wire is detected to be abnormal, the DSP controller  201  can directly control the DC/DC converter to be off, thereby avoiding the wiring harness in the circuit from being burned out or burned up. 
     Optionally, the DSP controller circuit is further configured to control the standby circuit for the on-board DC/DC converter to increase or reduce an output current, such that the DSP controller can control the DC/DC converter to reduce the output current if an excessive current flowing through the DC/DC ground wire or the high-voltage cable shielding layer is detected, thereby avoiding the wiring harness from being burned up due to the continuous output of the excessive current. 
     Optionally, an operation principle of the detection circuit for the on-board DC/DC ground wire illustrated in  FIG.  4    is as follows. During normal operation, the standby circuit for the on-board DC/DC converter has a very small supply current, such that a voltage drop across the power-supply negative wire for the on-board DC/DC converter is also very low, which can be regarded as the same as a low level of the vehicle body. In implementations of the present disclosure, by setting resistances of first resistor R 1 , second resistor R 2 , third resistor R 3 , and fourth resistor R 4 , a voltage of the negative input end of the comparator is higher than a voltage of the positive input end of the comparator, such that the comparator outputs a low level. The power-supply negative wire for the on-board DC/DC converter and the negative electrode of the storage battery are connected with the vehicle frame through the first ground wire. If the first ground wire is in poor contact with or disconnected with the vehicle frame, a relatively large current will be generated and flow back to the standby circuit for the on-board DC/DC converter through the power-supply negative wire for the on-board DC/DC converter. When the relatively large current flows through fifth resistor R 5  with the resistance at the level of milliohm, a relatively large voltage drop can be generated, such that a voltage of the power-supply negative wire for the on-board DC/DC converter is higher than a voltage of the vehicle body or the vehicle frame. Finally, the positive input voltage of the comparator is higher than the negative input voltage of the comparator, and the comparator outputs a high level to the DSP controller. Here, the DSP controller controls the DC/DC converter to reduce the output current or turns off the DC/DC converter, thereby avoiding the wiring harness in the vehicle system from being burned up due to the continuous output of the large current. 
     It can be seen that in implementations of the present disclosure, the detection circuit is connected between the DSP controller and the standby circuit for the on-board DC/DC converter, and the detection circuit is connected between the DSP controller and the power-supply negative wire for the on-board DC/DC converter. Once the ground wire connected with the power-supply negative wire for the on-board DC/DC converter is in poor contact with or even disconnected with the vehicle body, or the ground wire of the low-voltage storage battery is in poor contact with or even disconnected with the vehicle body, a current of hundreds of amperes is generated, the above detection circuit can detect a large current in the power-supply negative wire for the DC/DC converter or a shielding wire due to the disconnection or the poor contact of the ground wire of the standby circuit for the DC/DC converter, such that the DSP controller controls the standby circuit for the on-board DC/DC converter to reduce the output current or controls the standby circuit for the on-board DC/DC converter to be off. The above large current may mean that a device in the circuit consumes a larger current than normal, thereby avoiding the electronic fault phenomenon of the large current. 
     In a possible implementation, an on-board device is provided in implementations of the present disclosure. Reference can be made to  FIG.  5   , which is a schematic diagram of an on-board device provided in implementations of the present disclosure. The on-board device  300  includes the detection circuit for the on-board DC/DC ground wire  200  provided in any of the above implementations. The detection circuit for the on-board DC/DC ground wire  200  in the on-board device  300  is the same as the detection circuit for the on-board DC/DC ground wire  200  described in any of the above implementations, and will not be repeated herein. 
     It should be noted that for the sake of simplicity, the above implementations of the present disclosure are described as a series of action combinations. However, it will be appreciated by those of ordinary skill in the art that implementations are not limited by the sequence of actions described. According to implementations, some steps or operations may be performed in other orders or simultaneously. Besides, it will be appreciated by those of ordinary skill in the art that implementations described in the specification are exemplary implementations, and the actions and modules involved are not necessarily essential to the present disclosure. 
     In the above implementations, the description of each implementation has its own emphasis. For the parts not described in detail in one implementation, reference may be made to related descriptions in other implementations. 
     In implementations of the present disclosure, it should be understood that the apparatus disclosed in implementations provided in the present disclosure may be implemented in other manners. For example, the device/apparatus implementations described above are merely illustrative; for instance, the division of the unit is only a logical function division and there can be other manners of division during actual implementations, for example, multiple units or assemblies may be combined or may be integrated into another system, or some features may be ignored, omitted, or not performed. In addition, coupling or communication connection between each illustrated or discussed component may be direct coupling or communication connection, or may be indirect coupling or communication among devices or units via some interfaces, and may be electrical connection or other forms of connection. 
     The units described as separate components may or may not be physically separated, the components illustrated as units may or may not be physical units, that is, they may be in the same place or may be distributed to multiple network elements. Part or all of the units may be selected according to actual needs to achieve the purpose of the technical solutions of implementations. 
     In addition, the functional units in various implementations of the present disclosure may be integrated into one processing unit, or each unit may be physically present, or two or more units may be integrated into one unit. The above unit integrated may be implemented in the form of hardware or in the form of a software functional unit. 
     The above implementations in the present disclosure are described in detail. Principles and implementations of the present disclosure are elaborated with specific implementations herein. The above illustration of implementations is only used to help to understand methods and core ideas of the present disclosure. In the meanwhile, for those of ordinary skill in the art, according to ideas of the present disclosure, there will be changes in specific implementation manners and application scope. To sum up, contents of this specification should not be understood as limitation on the present disclosure.