Direct-current test safety power supply with power supply loop insulation troubleshooting function

Abstract

The invention provides a DC test safety power supply with a power supply loop insulation troubleshooting function, which is grounded through a grounding wire, and when the DC test safety power supply and specified DC equipment form a power supply loop to supply power to the DC equipment, whether a grounding loop exists between the DC test safety power supply and the power supply loop or not is automatically detected to troubleshoot the insulation fault existence condition on the DC equipment; wherein if the grounding loop is detected, it is determined that an insulation fault exists on the DC equipment; on the contrary, if it is detected that the grounding loop does not exist, it is determined that no insulation fault exists on the direct-current equipment. According to the invention, while the power supply is provided for the DC equipment, the DC insulation fault checking is carried out on the DC equipment, so that the safety coefficient of the DC system is improved.

Description

Technical Field

[0001] The invention relates to the technical field of electric power supply, and in particular to a DC test safety power supply with a power supply circuit insulation troubleshooting function. Background Art

[0002] The DC system is an important part of the substation. It provides a stable and reliable working environment for the substation secondary circuit equipment (such as relay protection, automatic devices, etc.), and is one of the fundamental guarantees for the stable operation of the substation. In order to protect the reliability of the DC system, before connecting new equipment to the DC system, an external DC test power supply is usually used to debug the new equipment, and the new equipment can only be connected to the DC system for operation after confirming that the new equipment is fully functional, safe and reliable.

[0003] However, the existing DC test power supply only provides power supply and does not have the function of checking the insulation of the power supply circuit. It cannot check the faults of DC grounding, AC-DC crosstalk, etc. of the newly connected equipment. When the equipment with these insulation faults is connected to the DC system, it may affect the normal operation of the DC system. In serious cases, it will cause accidents such as tripping of the operating equipment, malfunction or refusal of protection. In addition, the existing DC test power supply also has the problems of poor anti-interference ability, imperfect protection mechanism and poor output voltage stability.

[0004] Therefore, it is necessary to design a DC test power supply with power supply circuit insulation troubleshooting function and high safety. While providing power to DC equipment, it also performs DC insulation fault troubleshooting on DC equipment, thereby improving the safety factor of the DC system. Summary of the invention

[0005] The technical problem to be solved by the embodiments of the present invention is to provide a DC test safety power supply with a power supply circuit insulation troubleshooting function, which not only provides power to DC equipment but also performs DC insulation fault troubleshooting on the DC equipment, thereby improving the safety factor of the DC system.

[0006] In order to solve the above technical problems, the embodiment of the present invention provides a DC test safety power supply with a power supply circuit insulation troubleshooting function, which is grounded through a grounding wire and forms a power supply circuit with a specified DC device to supply power to the DC device. It automatically detects whether there is a grounding loop between it and the power supply circuit to troubleshoot the existence of insulation faults on the DC device; wherein,

[0007] If the existence of a grounding loop is detected, it is determined that an insulation fault exists on the DC device; conversely, if the absence of a grounding loop is detected, it is determined that no insulation fault exists on the DC device.

[0008] Among them, it includes: a main controller, a current sampling circuit, a signal source and a power conversion module; among them,

[0009] The positive input terminal of the power conversion module is connected to the positive pole of the external AC power supply, the negative input terminal is connected to the negative pole of the external AC power supply, the positive output terminal is connected to the positive pole of the DC device through the positive side line on the power supply circuit, the negative output terminal is connected to the negative pole of the DC device through the negative side line on the power supply circuit, and the control terminal is connected to the main controller, and is used to convert the AC power output by the external AC power supply into DC power, and provide the DC power to the DC device;

[0010] The input end of the signal source is connected to the main controller, and the output end is connected to both the positive and negative side lines of the power supply circuit, so as to generate a grounding test signal, and load the grounding test signal on the positive side line or the negative side line of the power supply circuit according to the loading instruction issued by the main controller;

[0011] The input end of the current sampling circuit is connected to the ground wire through a current transformer, and the output end is connected to the main controller, so as to collect the current signal on the ground wire in real time and forward it to the main controller;

[0012] The main controller is used to control the power conversion module to output direct current to the DC device, and generate the loading instruction and send it to the signal source; and if the current signal forwarded by the current sampling circuit is received, it is determined that a ground loop has been formed, and further determines that an insulation fault exists on the DC device; conversely, if the current signal forwarded by the current sampling circuit is not received, it is determined that the ground loop has not been formed, and further determines that no insulation fault exists on the DC device.

[0013] Among them, it also includes: a ground voltage sampling circuit; wherein,

[0014] The ground voltage sampling circuit comprises a positive ground variable resistor, a positive switching switch, a positive ground balanced bridge resistor, a positive ground voltage sampling amplifier, a negative ground variable resistor, a negative switching switch, a negative ground balanced bridge resistor and a negative ground voltage sampling amplifier; one end of the positive ground variable resistor is connected to the positive side line on the power supply circuit through a voltage transformer and is connected to one end of the positive ground balanced bridge resistor, and the other end is grounded through the positive switching switch and is connected to the other end of the positive ground balanced bridge resistor; the positive input end of the positive ground voltage sampling amplifier is connected to the positive input end of the positive ground voltage sampling amplifier. The other end of the positive-to-ground balanced bridge resistor is connected, the negative input end is connected to the output end, and the output end is connected to the main controller; one end of the negative-to-ground variable resistor is connected to the negative side line on the power supply circuit through a voltage transformer and is connected to one end of the negative-to-ground balanced bridge resistor, and the other end is grounded through the negative switching switch and connected to the other end of the negative-to-ground balanced bridge resistor; the positive input end of the negative-to-ground voltage sampling amplifier is connected to the other end of the negative-to-ground balanced bridge resistor, the negative input end is connected to the output end, and the output end is connected to the main controller;

[0015] Wherein, the ground voltage sampling circuit is used to turn off the positive switching switch and the negative switching switch when the ground test signal is loaded on the positive side line of the power supply circuit, and the positive ground voltage sampling amplifier outputs the corresponding positive ground voltage signal to the main controller; or when the ground test signal is loaded on the negative side line of the power supply circuit, turn off the positive switching switch and the negative switching switch, and the negative ground voltage sampling amplifier outputs the corresponding negative ground voltage signal to the main controller; or, when the ground test signal is loaded on the positive side line of the power supply circuit, turn on the positive switching switch to put the positive ground variable resistor into operation, and adjust the size of the positive ground variable resistor so that the ground test signal of the power supply circuit on the positive side line has a sinusoidal fluctuation; or, when the ground test signal is loaded on the negative side line of the power supply circuit, turn on the negative switching switch to put the negative ground variable resistor into operation, and adjust the size of the negative ground variable resistor so that the ground test signal of the power supply circuit on the negative side line has a sinusoidal fluctuation;

[0016] Wherein, the main controller is further used for, when the positive switching switch is turned on, if it is determined that the current signal collected by the current sampling circuit is a sine wave signal, then it is determined that the DC device has an insulation fault on the positive side; or, when the negative switching switch is turned on, if it is determined that the current signal collected by the current sampling circuit is a sine wave signal, then it is determined that the DC device has an insulation fault on the negative side; or, when both the positive switching switch and the negative switching switch are turned off, determining the positive-to-ground voltage of the power supply circuit based on the positive-to-ground voltage sampling amplifier outputting the corresponding positive-to-ground voltage signal, and determining the negative-to-ground voltage of the power supply circuit based on the negative-to-ground voltage sampling amplifier outputting the corresponding negative-to-ground voltage signal.

[0017] Among them, it also includes: an overvoltage protection circuit; among them,

[0018] The overvoltage protection circuit comprises a first voltage comparator and a first optocoupler; wherein the positive input terminal of the first voltage comparator is connected to the positive side line or the negative side line of the power supply circuit through a voltage transformer, the negative input terminal is grounded through a first voltage divider resistor, and the output terminal is connected to the light emitting diode of the first optocoupler; the photoresistor of the first optocoupler is connected to the main controller;

[0019] The overvoltage protection circuit is used to turn on the first optical coupler and output a low-level signal with a falling edge to the main controller when the output voltage of the power conversion module is greater than the voltage division value obtained by the first voltage-dividing resistor, so that the main controller stops the power conversion module from working.

[0020] Among them, it also includes: an overcurrent protection circuit; among them,

[0021] The overcurrent protection circuit includes a sampling resistor, a second voltage comparator and a second optical coupler; wherein one end of the sampling resistor is connected to the positive side line or the negative side line of the power supply circuit through a current transformer, and the other end is connected to the negative input end of the second voltage comparator; the positive input end of the second voltage comparator is grounded through a second voltage divider resistor, and the output end is connected to the light-emitting diode of the second optical coupler; the photoresistor of the second optical coupler is connected to the main controller;

[0022] The overcurrent protection circuit is used to turn off the second optical coupler and output a high-level signal to the main controller when the voltage value obtained by sampling the output current of the power conversion module through the sampling resistor is greater than the voltage divided value obtained by the second voltage divider resistor, so that the main controller stops the power conversion module from working.

[0023] Among them, it also includes: an over-temperature protection circuit; among them,

[0024] The over-temperature protection circuit is connected to the main controller, and includes a temperature sampling resistor, a temperature control switch and a third optical coupler; wherein one end of the temperature sampling resistor is connected to an internal working voltage source, and the other end is connected to one end of the temperature control switch; the other end of the temperature control switch is connected to the light-emitting diode of the third optical coupler; the photoresistor of the third optical coupler is connected to the main controller;

[0025] The over-temperature protection circuit is used to control the temperature control switch to turn on the third optical coupler and output a low-level signal with a falling edge to the main controller when the temperature value collected by the temperature sampling resistor is greater than a preset temperature threshold, so that the main controller stops the power conversion module from working.

[0026] The power conversion module includes an electric voltage regulator, a rectifier, a filter and a DC / DC converter connected in sequence;

[0027] The electric voltage regulator is connected to the external AC power source and is used to adjust the output voltage of the external AC power source;

[0028] The rectifier is used to perform full-wave rectification on the regulated alternating current to convert it into direct current;

[0029] The filter is used to filter the clutter of the rectified direct current;

[0030] The DC / DC converter is connected to the main controller and is used to convert the filtered direct current to output direct current of corresponding voltage and current.

[0031] Among them, it also includes: an adaptive PID controller; wherein,

[0032] One end of the adaptive PID controller is connected to the main controller, and the other end is connected to the electric voltage regulator. It is used to compare the actual voltage fed back by the main controller with a preset reference voltage to obtain a deviation value, and to make inferences based on the obtained deviation value to adjust the size of the AC power output by the electric voltage regulator through a preset PID algorithm.

[0033] Among them, it also includes: an alarm circuit; among them,

[0034] The alarm circuit is connected to the main controller and is used to issue an alarm when the main controller determines that there is an insulation fault on the DC device.

[0035] Implementing the embodiments of the present invention has the following beneficial effects:

[0036] In the present invention, the DC test safety power supply is grounded via a grounding wire and forms a power supply loop with a designated DC device to supply power to the DC device. It automatically detects whether there is a grounding loop between it and the power supply loop to check for insulation faults on the DC device. Thus, while providing power to the DC device, it can also check for DC insulation faults on the DC device, thereby improving the safety factor of the DC system. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, without paying creative labor, other drawings obtained based on these drawings still belong to the scope of the present invention.

[0038] Figure 1 A schematic diagram of the connection between a DC test safety power supply with a power supply circuit insulation troubleshooting function provided by an embodiment of the present invention and a designated DC device when a power supply circuit is normal;

[0039] Figure 2 A schematic diagram of the connection between a DC test safety power supply with a power supply circuit insulation troubleshooting function provided by an embodiment of the present invention and a specified DC device when there is an insulation fault in the power supply circuit;

[0040] Figure 3 A schematic diagram of the structure of a DC test safety power supply with a power supply circuit insulation troubleshooting function provided by an embodiment of the present invention;

[0041] Figure 4 A schematic diagram of the structure of an overvoltage protection circuit in a DC test safety power supply with a power supply circuit insulation troubleshooting function provided by an embodiment of the present invention;

[0042] Figure 5 An application scenario diagram of an overvoltage protection circuit in a DC test safety power supply with a power supply circuit insulation troubleshooting function provided by an embodiment of the present invention;

[0043] Figure 6 A schematic diagram of the structure of an overcurrent protection circuit in a DC test safety power supply with a power supply circuit insulation troubleshooting function provided by an embodiment of the present invention;

[0044] Figure 7 An application scenario diagram of an overcurrent protection circuit in a DC test safety power supply with a power supply circuit insulation troubleshooting function provided by an embodiment of the present invention;

[0045] Figure 8A schematic diagram of the structure of an over-temperature protection circuit in a DC test safety power supply with a power supply circuit insulation troubleshooting function provided by an embodiment of the present invention;

[0046] Fig. 9 A diagram of an application scenario of an over-temperature protection circuit in a DC test safety power supply with a power supply circuit insulation troubleshooting function provided by an embodiment of the present invention;

[0047] Fig.10 A schematic diagram of the structure of a ground voltage sampling circuit in a DC test safety power supply with a power supply circuit insulation troubleshooting function provided by an embodiment of the present invention;

[0048] Fig.11 A diagram of an application scenario of a ground voltage sampling circuit in a DC test safety power supply with a power supply circuit insulation troubleshooting function provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0049] In order to make the objectives, technical solutions and advantages of the present invention more clear, the present invention will be further described in detail below with reference to the accompanying drawings.

[0050] like Figure 1 and Figure 2 As shown, a DC test safety power supply with a power supply circuit insulation troubleshooting function is proposed in an embodiment of the present invention. The DC test safety power supply is grounded through a grounding wire G and forms a power supply circuit with a designated DC device to supply power to the DC device. It can automatically detect whether there is a grounding circuit between it and the power supply circuit to troubleshoot the existence of insulation faults on the DC device; wherein,

[0051] If the existence of a grounding loop is detected, that is, the insulation fault point and the grounding point of the DC test safety power supply form a grounding loop, it is determined that there is an insulation fault on the DC equipment, including DC grounding, etc.; conversely, if the absence of a grounding loop is detected, it is determined that there is no insulation fault on the DC equipment.

[0052] It can be understood that the existence of a ground loop can be detected by using a current transformer to sense current on the ground line G of the DC test safety power supply; if a current signal is sensed, it is determined that a ground loop exists; otherwise, it is determined that a ground loop does not exist.

[0053] In the embodiment of the present invention, Figures 3 to 11 As shown, the DC test safety power supply includes: a main controller 1, a current sampling circuit 2, a signal source 3, a power conversion module 4, an overvoltage protection circuit 5, an overcurrent protection circuit 6, an overtemperature protection circuit 7, an alarm circuit 8 and a ground voltage sampling circuit 9; wherein,

[0054] The positive input terminal a1 of the power conversion module 4 is connected to the positive pole (+) of the external AC power source AC, the negative input terminal a2 is connected to the negative pole (-) of the external AC power source AC, the positive output terminal a3 is connected to the positive pole (+) of the DC device through the positive side line L1 on the power supply circuit, the negative output terminal a4 is connected to the negative pole (-) of the DC device through the negative side line L2 on the power supply circuit, and the control terminal a5 is connected to the main controller 1, and is used to convert the AC power output by the external AC power source AC into DC power, and provide the DC power to the DC device;

[0055] The input end of the signal source 3 is connected to the main controller 1, and the output end is connected to the positive and negative side lines L1 and L2 between the power supply circuit, so as to generate a grounding test signal, and load the grounding test signal on the positive side line L1 or the negative side line L2 of the power supply circuit according to the loading instruction issued by the main controller;

[0056] The input end of the current sampling circuit 2 is connected to the ground wire G through a current transformer, and the output end is connected to the main controller 1, for real-time acquisition of the current signal on the ground wire G and forwarding it to the main controller 1;

[0057] The main controller 1 is used to control the power conversion module 4 to output direct current to the direct current device, and generate a loading instruction to be sent to the signal source 3; and if the current signal forwarded by the current sampling circuit 2 is received, it is determined that the ground loop has been formed, and further it is determined that there is an insulation fault on the direct current device; on the contrary, if the current signal forwarded by the current sampling circuit 2 is not received, it is determined that the ground loop is not formed, and further it is determined that there is no insulation fault on the direct current device;

[0058] The overvoltage protection circuit 5 includes a first voltage comparator 51 and a first optical coupler 52 (such as Figure 4 As shown); wherein, the positive input terminal (+) of the first voltage comparator 51 is connected to the positive side line L1 or the negative side line L2 of the power supply circuit through a voltage transformer, the negative input terminal (-) is grounded through a first voltage dividing resistor 53, and the output terminal is connected to the light emitting diode 521 of the first optical coupler 52; the photoresistor 522 of the first optical coupler 52 is connected to the main controller 1; the overvoltage protection circuit 5 is used to turn on the first optical coupler 52 and output a low-level signal with a falling edge to the main controller 1 when the output voltage of the power conversion module 4 is greater than the voltage dividing value obtained by the first voltage dividing resistor 53, so that the main controller 1 stops the power conversion module 4 from working; in an example, as Figure 5As shown, U1 is the first voltage comparator 51, D1 is the first optical coupler 52, the V0 terminal is connected to the positive side line L1 or the negative side line L2 of the power supply circuit, and Rb1 is the first voltage-dividing resistor 53; at this time, the positive side line L1 or the negative side line L2 of the power supply circuit is connected to the V0 terminal, enters the first voltage comparator U1, and compares the input voltage with the set base value. When the value of the voltage at the V0 terminal is higher than the voltage at the negative input terminal of the first voltage comparator U1 (that is, the voltage obtained by dividing the voltage of the first voltage-dividing resistor Rb1), the first voltage comparator U1 will output a high level. At this time, the first optical coupler D1 is turned on and outputs a low level signal. The low level signal generates a falling edge, thereby controlling the power conversion module 4 to stop working;

[0059] The overcurrent protection circuit 6 includes a sampling resistor 61, a second voltage comparator 62 and a second optical coupler 63 (such as Figure 6 As shown); wherein, one end of the sampling resistor 61 is connected to the positive side line L1 or the negative side line L2 of the power supply circuit through a current transformer, and the other end is connected to the negative input end (-) of the second voltage comparator 62; the positive input end (+) of the second voltage comparator 62 is grounded through a second voltage divider resistor 64, and the output end is connected to the light-emitting diode 631 of the second optical coupler 63; the photoresistor 632 of the second optical coupler 63 is connected to the main controller 1; the overcurrent protection circuit 6 is used to turn off the second optical coupler 63 and output a high-level signal to the main controller 1 when the voltage value obtained by sampling the output current of the power conversion module 4 through the sampling resistor 61 is greater than the voltage divider value obtained by the second voltage divider resistor 64, so that the main controller 1 stops the power conversion module 4 from working; in an example, as Figure 7 As shown, R1 is a sampling resistor 61, U2 is a second voltage comparator 62, D2 is a second optical coupler 63, the V0 terminal is connected to the positive side line L1 or the negative side line L2 of the power supply circuit, and Rb2 is a second voltage-dividing resistor 64; at this time, the positive side line L1 or the negative side line L2 of the power supply circuit is connected to the I0 terminal, if the potential of the I0 terminal is higher than the voltage of the non-phase input terminal of the second voltage comparator U2 (that is, the voltage obtained by the voltage division of the second voltage-dividing resistor Rb2), then there is a low-level output at the output terminal of the second voltage comparator U2, so that the second optical coupler D2 is turned off and outputs a high-level signal to the main controller 1, thereby controlling the power conversion module 4 to stop working;

[0060] The over-temperature protection circuit 7 is connected to the main controller 1 and includes a temperature sampling resistor 71, a temperature control switch 72 and a third optical coupler 73 (such as Figure 8As shown); wherein, one end of the temperature sampling resistor 71 is connected to the internal working voltage source DC, and the other end is connected to one end of the temperature control switch 72; the other end of the temperature control switch 72 is connected to the light-emitting diode 731 of the third optical coupler 73; the photoresistor 732 of the third optical coupler 73 is connected to the main controller 1; the over-temperature protection circuit 7 is used to control the temperature control switch 72 to turn on when the temperature value collected by the temperature sampling resistor 71 is greater than the preset temperature threshold, so that the third optical coupler 73 is turned on and outputs a low-level signal with a falling edge to the main controller 1, so that the main controller 1 stops the power conversion module 4 from working; in an example, as Fig. 9 As shown, R11 is the temperature sampling resistor 71, K1 is the control switch 72, and D3 is the third optical coupler 73; at this time, when the temperature collected by the temperature sampling resistor R11 is too high, the temperature control switch K1 is closed, the circuit is connected, the third optical coupler D3 is turned on, and a low-level signal is output to the main controller 1, so that the power conversion module 4 stops working;

[0061] The alarm circuit 8 is connected to the main controller 1 and is used to issue an alarm when the main controller 1 determines that there is an insulation fault on the DC equipment;

[0062] The ground voltage sampling circuit 9 includes a positive ground variable resistor 91, a positive switching switch 92, a positive ground balanced bridge resistor 93, a positive ground voltage sampling amplifier 94, a negative ground variable resistor 95, a negative switching switch 96, a negative ground balanced bridge resistor 97 and a negative ground voltage sampling amplifier 98 (such as Fig.10As shown); wherein, one end of the positive-to-ground variable resistor 91 is connected to the positive side line L1 on the power supply circuit through a voltage transformer and is connected to one end of the positive-to-ground balanced bridge resistor 93, and the other end is grounded through a positive switching switch 92 and is connected to the other end of the positive-to-ground balanced bridge resistor 93; the positive input end (+) of the positive-to-ground voltage sampling amplifier 94 is connected to the other end of the positive-to-ground balanced bridge resistor 93, the negative input end (-) is connected to the output end, and the output end is connected to the main controller 1; one end of the negative-to-ground variable resistor 95 is connected to the negative side line L2 on the power supply circuit through a voltage transformer and is connected to one end of the negative-to-ground balanced bridge resistor 97, and the other end is grounded through a negative switching switch 96 and is connected to the negative-to-ground balanced bridge resistor The positive input terminal (+) of the negative-to-ground voltage sampling amplifier 98 is connected to the other end of the negative-to-ground balanced bridge resistor 97, and the negative input terminal (-) is connected to the output terminal, and the output terminal is connected to the main controller 1; wherein the ground voltage sampling circuit 9 is used to turn off the positive switching switch 92 and the negative switching switch 96 when the ground test signal is loaded on the positive side line L1 on the power supply circuit, and the positive-to-ground voltage sampling amplifier 94 outputs the corresponding positive-to-ground voltage signal to the main controller 1; or when the ground test signal is loaded on the negative side line L2 on the power supply circuit, the positive switching switch 92 and the negative switching switch 96 are turned off, and the negative-to-ground voltage sampling amplifier 98 outputs the corresponding negative-to-ground voltage signal to the main controller 1; or, when the grounding test signal is loaded on the positive side line L1 of the power supply circuit, the positive switching switch 92 is turned on to input the positive variable resistor 93, and the size of the positive variable resistor 93 is adjusted to make the grounding test signal of the positive side line L1 of the power supply circuit to fluctuate sinusoidally; or, when the grounding test signal is loaded on the negative side line L2 of the power supply circuit, the negative switching switch 96 is turned on to input the negative variable resistor 97, and the size of the negative variable resistor 97 is adjusted to make the grounding test signal of the negative side line L2 of the power supply circuit to fluctuate sinusoidally; at this time, when the positive switching switch 92 of the main controller 1 is turned on, if it is determined that the current sampling circuit 2 collects If the current signal obtained is a sine wave signal, it is determined that there is an insulation fault on the positive side of the DC device; or, when the negative switching switch 96 is turned on, if it is determined that the current signal collected by the current sampling circuit 2 is a sine wave signal, it is determined that there is an insulation fault on the negative side of the DC device; or, when the positive switching switch 92 and the negative switching switch 96 are both turned off, the positive-to-ground voltage of the power supply circuit is determined based on the positive-to-ground voltage sampling amplifier 94 outputting the corresponding positive-to-ground voltage signal, and the negative-to-ground voltage of the power supply circuit is determined based on the negative-to-ground voltage sampling amplifier 98 outputting the corresponding negative-to-ground voltage signal, so that it can be further distinguished that the insulation fault is located on a specific side of the positive or negative side of the DC device.

[0063] In an example, Fig.11As shown, +KM is the access point of the positive side line L1 on the power supply circuit, -KM is the access point of the negative side line L2 on the power supply circuit, R3 is the positive variable resistor 91 to ground, K1 is the positive switching switch 92, resistors R2c, Rw1 and R42 constitute the positive balanced bridge resistor 93 to ground, U1A is the positive voltage sampling amplifier 94 to ground, R4 is the negative variable resistor 95 to ground, K2 is the negative switching switch 96, resistors R1c, Rw2 and R41 constitute the negative balanced bridge resistor 97 to ground, and U1B is the negative voltage sampling amplifier 98 to ground. ① When K1 is closed and K2 is disconnected, adjust the size of the variable resistor R3 so that the positive voltage to ground fluctuates sinusoidally. At this time, the positive voltage to ground U+ increases with the increase of R3, and the negative voltage U- decreases with the increase of R3. ② When K2 is closed and K1 is disconnected, adjust the size of the variable resistor R4 so that the negative voltage to ground fluctuates sinusoidally. At this time, the negative pole to ground voltage U- increases with the increase of R4, and the positive pole voltage U+ decreases with the increase of R4. At this time, in the well-insulated power supply circuit, there is no leakage current because there is no ground fault, and the CT connected to the current sampling circuit 2 cannot detect the changing leakage current. If the negative pole of the power supply circuit is grounded, and the negative pole to ground voltage fluctuates sinusoidally, there will be a sinusoidal leakage current on the ground wire G.

[0064] It is understandable that a signal tracker can be used to track the sinusoidal grounding test signal of the power supply circuit on the positive side line L1 or the negative side line L2 in real time. If the signal disappears once the insulation fault point is crossed, the insulation fault point can be accurately located.

[0065] In the embodiment of the present invention, the power conversion module 4 includes an electric voltage regulator 41, a rectifier 42, a filter 43 and a DC / DC converter 44 connected in sequence; wherein,

[0066] The electric voltage regulator 41 is connected to the external AC power source AC and is used to adjust the output voltage of the external AC power source AC;

[0067] The rectifier 42 is used to perform full-wave rectification on the regulated AC power to convert it into DC power;

[0068] The filter 43 is used to filter the clutter of the rectified DC power;

[0069] The DC / DC converter 44 is connected to the main controller 1 and is used to convert the filtered DC power to output DC power of corresponding voltage and current. It should be noted that the main controller 1 can control the working mode of the power conversion module 4, including stopping and working, by controlling the on and off of the DC / DC converter 44.

[0070] It should be noted that the output DC power of the power conversion module 4 can be closed-loop controlled by a PID controller to ensure the stability of the output voltage. Therefore, the DC test safety power supply also includes: an adaptive PID controller 10; wherein one end of the adaptive PID controller 10 is connected to the main controller 1, and the other end is connected to the electric voltage regulator 41, which is used to compare the actual voltage fed back by the main controller 1 with the preset reference voltage to obtain a deviation value, and to make inferences based on the obtained deviation value, and to adjust the AC power output by the electric voltage regulator 41 through a preset PID algorithm.

[0071] Implementing the embodiments of the present invention has the following beneficial effects:

[0072] In the present invention, the DC test safety power supply is grounded via a grounding wire and forms a power supply loop with a designated DC device to supply power to the DC device. It automatically detects whether there is a grounding loop between it and the power supply loop to check for insulation faults on the DC device. Thus, while providing power to the DC device, it can also check for DC insulation faults on the DC device, thereby improving the safety factor of the DC system.

[0073] The above disclosure is only the preferred embodiment of the present invention, which certainly cannot be used to limit the scope of the present invention. Therefore, equivalent changes made according to the claims of the present invention are still within the scope of the present invention.

Claims

1. A DC test safety power supply with power supply circuit insulation troubleshooting function, characterized in that: When it is grounded through a grounding wire and forms a power supply loop with a designated DC device to supply power to the DC device, it automatically detects whether there is a grounding loop between it and the power supply loop to check for insulation faults on the DC device; wherein, If the existence of a grounding loop is detected, it is determined that an insulation fault exists on the DC device; conversely, if the absence of a grounding loop is detected, it is determined that no insulation fault exists on the DC device.

2. The DC test safety power supply with power supply circuit insulation troubleshooting function as claimed in claim 1, characterized in that: include: Main controller, current sampling circuit, signal source and power conversion module; wherein, The positive input terminal of the power conversion module is connected to the positive pole of the external AC power supply, the negative input terminal is connected to the negative pole of the external AC power supply, the positive output terminal is connected to the positive pole of the DC device through the positive side line on the power supply circuit, the negative output terminal is connected to the negative pole of the DC device through the negative side line on the power supply circuit, and the control terminal is connected to the main controller, and is used to convert the AC power output by the external AC power supply into DC power, and provide the DC power to the DC device; The input end of the signal source is connected to the main controller, and the output end is connected to both the positive and negative side lines of the power supply circuit, so as to generate a grounding test signal, and load the grounding test signal on the positive side line or the negative side line of the power supply circuit according to the loading instruction issued by the main controller; The input end of the current sampling circuit is connected to the ground wire through a current transformer, and the output end is connected to the main controller, so as to collect the current signal on the ground wire in real time and forward it to the main controller; The main controller is used to control the power conversion module to output direct current to the DC device, and generate the loading instruction and send it to the signal source; and if the current signal forwarded by the current sampling circuit is received, it is determined that a ground loop has been formed, and further determines that an insulation fault exists on the DC device; conversely, if the current signal forwarded by the current sampling circuit is not received, it is determined that the ground loop has not been formed, and further determines that no insulation fault exists on the DC device.

3. The DC test safety power supply with power supply circuit insulation troubleshooting function as claimed in claim 2, characterized in that: It also includes: a ground voltage sampling circuit; wherein, The ground voltage sampling circuit comprises a positive ground variable resistor, a positive switching switch, a positive ground balanced bridge resistor, a positive ground voltage sampling amplifier, a negative ground variable resistor, a negative switching switch, a negative ground balanced bridge resistor and a negative ground voltage sampling amplifier; one end of the positive ground variable resistor is connected to the positive side line on the power supply circuit through a voltage transformer and is connected to one end of the positive ground balanced bridge resistor, and the other end is grounded through the positive switching switch and is connected to the other end of the positive ground balanced bridge resistor; the positive input end of the positive ground voltage sampling amplifier is connected to the positive input end of the positive ground voltage sampling amplifier. The other end of the positive-to-ground balanced bridge resistor is connected, the negative input end is connected to the output end, and the output end is connected to the main controller; one end of the negative-to-ground variable resistor is connected to the negative side line on the power supply circuit through a voltage transformer and is connected to one end of the negative-to-ground balanced bridge resistor, and the other end is grounded through the negative switching switch and connected to the other end of the negative-to-ground balanced bridge resistor; the positive input end of the negative-to-ground voltage sampling amplifier is connected to the other end of the negative-to-ground balanced bridge resistor, the negative input end is connected to the output end, and the output end is connected to the main controller; Wherein, the ground voltage sampling circuit is used to turn off the positive switching switch and the negative switching switch when the ground test signal is loaded on the positive side line of the power supply circuit, and the positive ground voltage sampling amplifier outputs the corresponding positive ground voltage signal to the main controller; or when the ground test signal is loaded on the negative side line of the power supply circuit, turn off the positive switching switch and the negative switching switch, and the negative ground voltage sampling amplifier outputs the corresponding negative ground voltage signal to the main controller; or, when the ground test signal is loaded on the positive side line of the power supply circuit, turn on the positive switching switch to put the positive ground variable resistor into operation, and adjust the size of the positive ground variable resistor so that the ground test signal of the power supply circuit on the positive side line has a sinusoidal fluctuation; or, when the ground test signal is loaded on the negative side line of the power supply circuit, turn on the negative switching switch to put the negative ground variable resistor into operation, and adjust the size of the negative ground variable resistor so that the ground test signal of the power supply circuit on the negative side line has a sinusoidal fluctuation; Wherein, the main controller is further used for, when the positive switching switch is turned on, if it is determined that the current signal collected by the current sampling circuit is a sine wave signal, then it is determined that the DC device has an insulation fault on the positive side; or, when the negative switching switch is turned on, if it is determined that the current signal collected by the current sampling circuit is a sine wave signal, then it is determined that the DC device has an insulation fault on the negative side; or, when both the positive switching switch and the negative switching switch are turned off, determining the positive-to-ground voltage of the power supply circuit based on the positive-to-ground voltage sampling amplifier outputting the corresponding positive-to-ground voltage signal, and determining the negative-to-ground voltage of the power supply circuit based on the negative-to-ground voltage sampling amplifier outputting the corresponding negative-to-ground voltage signal.

4. The DC test safety power supply with power supply circuit insulation troubleshooting function as claimed in claim 3, characterized in that: Also includes: Overvoltage protection circuit; wherein, The overvoltage protection circuit comprises a first voltage comparator and a first optocoupler; wherein the positive input terminal of the first voltage comparator is connected to the positive side line or the negative side line of the power supply circuit through a voltage transformer, the negative input terminal is grounded through a first voltage divider resistor, and the output terminal is connected to the light emitting diode of the first optocoupler; the photoresistor of the first optocoupler is connected to the main controller; The overvoltage protection circuit is used to turn on the first optical coupler and output a low-level signal with a falling edge to the main controller when the output voltage of the power conversion module is greater than the voltage division value obtained by the first voltage-dividing resistor, so that the main controller stops the power conversion module from working.

5. The DC test safety power supply with power supply circuit insulation troubleshooting function as claimed in claim 4, characterized in that: Also includes: Overcurrent protection circuit; wherein, The overcurrent protection circuit includes a sampling resistor, a second voltage comparator and a second optical coupler; wherein one end of the sampling resistor is connected to the positive side line or the negative side line of the power supply circuit through a current transformer, and the other end is connected to the negative input end of the second voltage comparator; the positive input end of the second voltage comparator is grounded through a second voltage divider resistor, and the output end is connected to the light-emitting diode of the second optical coupler; the photoresistor of the second optical coupler is connected to the main controller; The overcurrent protection circuit is used to turn off the second optical coupler and output a high-level signal to the main controller when the voltage value obtained by sampling the output current of the power conversion module through the sampling resistor is greater than the voltage divided value obtained by the second voltage divider resistor, so that the main controller stops the power conversion module from working.

6. The DC test safety power supply with power supply circuit insulation troubleshooting function as claimed in claim 5, characterized in that: Also includes: Over temperature protection circuit; wherein, The over-temperature protection circuit is connected to the main controller, and includes a temperature sampling resistor, a temperature control switch and a third optical coupler; wherein one end of the temperature sampling resistor is connected to an internal working voltage source, and the other end is connected to one end of the temperature control switch; the other end of the temperature control switch is connected to the light-emitting diode of the third optical coupler; the photoresistor of the third optical coupler is connected to the main controller; The over-temperature protection circuit is used to control the temperature control switch to turn on the third optical coupler and output a low-level signal with a falling edge to the main controller when the temperature value collected by the temperature sampling resistor is greater than a preset temperature threshold, so that the main controller stops the power conversion module from working.

7. The DC test safety power supply with power supply circuit insulation troubleshooting function as claimed in claim 6, characterized in that: The power conversion module includes an electric voltage regulator, a rectifier, a filter and a DC / DC converter connected in sequence; wherein, The electric voltage regulator is connected to the external AC power source and is used to adjust the output voltage of the external AC power source; The rectifier is used to perform full-wave rectification on the regulated alternating current to convert it into direct current; The filter is used to filter the clutter of the rectified direct current; The DC / DC converter is connected to the main controller and is used to convert the filtered direct current to output direct current of corresponding voltage and current.

8. The DC test safety power supply with power supply circuit insulation troubleshooting function as claimed in claim 7, characterized in that: Also includes: Adaptive PID controller; where, One end of the adaptive PID controller is connected to the main controller, and the other end is connected to the electric voltage regulator. It is used to compare the actual voltage fed back by the main controller with a preset reference voltage to obtain a deviation value, and to make inferences based on the obtained deviation value to adjust the size of the AC power output by the electric voltage regulator through a preset PID algorithm.

9. The DC test safety power supply with power supply circuit insulation troubleshooting function as claimed in claim 8, characterized in that: Also includes: Alarm circuit; wherein, The alarm circuit is connected to the main controller and is used to issue an alarm when the main controller determines that there is an insulation fault on the DC device.

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