Insulation resistance detection circuit of direct current bus and electronic equipment

Abstract

The utility model discloses an insulation resistance detection circuit of a direct-current bus and electronic equipment. The insulation resistance detection circuit comprises a switching circuit, a first impedance circuit, a second impedance circuit, a voltage sampling circuit and a controller, a first end of the switching circuit is connected with a cathode DC bus of the DC bus, a second end of the switching circuit is connected to a first end of the first impedance circuit, and a second end of the first impedance circuit is connected to a first end of the voltage sampling circuit and is grounded; the first end of the second impedance circuit is connected with the positive DC bus of the DC bus, and the second end of the second impedance circuit is connected to the first end of the voltage sampling circuit and grounded; the controller is connected with the control end of the switching circuit and the second end of the voltage sampling circuit, and the controller is used for controlling the switching circuit to be switched off and switched on and obtaining the first voltage and the second voltage of the second end of the voltage sampling circuit; and obtaining an insulation resistance value of the DC bus according to the first voltage and the second voltage. The accuracy of insulation impedance detection can be improved.

Description

Technical Field

[0001] The present application relates to the technical field of insulation impedance detection, and in particular to an insulation impedance detection circuit and electronic equipment for a DC bus. Background Art

[0002] At present, for the detection of the insulation impedance of the DC bus, two switching circuits are generally set to control the connection of a certain amount of impedance between the positive DC bus and the ground, and to control the connection of a certain amount of impedance between the negative DC bus and the ground, so as to collect the voltage value when the positive DC bus is grounded, and the voltage value when the negative DC bus is grounded, and calculate the insulation impedance value of the DC bus based on these two voltage values.

[0003] However, the voltage value collected when the negative DC bus is grounded is often very small and is easily disturbed during transmission to the control chip, thereby affecting the accuracy of the final calculation of the insulation impedance value of the DC bus. Utility Model Content

[0004] In view of this, the present application provides a DC bus insulation impedance detection circuit and electronic equipment, which are used to improve the accuracy of calculating the insulation impedance value of the DC bus. The technical solution of the present application is as follows:

[0005] In a first aspect, the present application provides an insulation impedance detection circuit for a DC bus, the insulation impedance detection circuit comprising a switch circuit, a first impedance circuit, a second impedance circuit, a voltage sampling circuit and a controller; the first end of the switch circuit is connected to the negative DC bus of the DC bus, the second end of the switch circuit is connected to the first end of the first impedance circuit, the second end of the first impedance circuit is connected to the first end of the voltage sampling circuit and is grounded; the first end of the second impedance circuit is connected to the positive DC bus of the DC bus, the second end of the second impedance circuit is connected to the first end of the voltage sampling circuit and is grounded; the controller is connected to the control end of the switch circuit and the second end of the voltage sampling circuit, the controller is used to: control the switch circuit to turn off and obtain a first voltage through the voltage sampling circuit; control the switch circuit to turn on and obtain a second voltage through the voltage sampling circuit; obtain the insulation impedance value of the DC bus according to the first voltage and the second voltage.

[0006] In one embodiment of the present application, the switching circuit includes a relay unit and a relay control unit; the first end of the relay unit is connected to the negative DC bus, and the second end of the relay unit is connected to the first end of the first impedance circuit; the relay control unit is connected to the control end of the relay unit and the controller, and the relay control unit is used to receive a control signal from the controller and control the relay unit to be turned off or on according to the control signal.

[0007] In one embodiment of the present application, the relay unit includes a relay, a diode and a zener diode; the first switch pin of the relay is connected to the negative DC bus, the second switch pin of the relay is connected to the first end of the first impedance circuit, the negative pin of the relay is connected to the relay control unit, and the positive pin of the relay is used to receive the power supply voltage; the positive electrode of the diode is connected to the negative electrode pin of the relay, the negative electrode of the diode is connected to the negative electrode of the zener diode, and the positive electrode of the zener diode is connected to the positive electrode pin of the relay.

[0008] In one embodiment of the present application, the relay control unit includes a switch tube, a first resistor, a second resistor and a capacitor; the first end of the switch tube is connected to the relay unit, the second end of the switch tube is grounded, and the control end of the switch tube is grounded through the first resistor and the capacitor in parallel; the control end of the switch tube is also connected to the controller through the second resistor.

[0009] In one embodiment of the present application, the switch tube includes a MOS tube, the first end of the switch tube is the drain of the MOS tube, the second end of the switch tube is the source of the MOS tube, and the control end of the switch tube is the gate of the MOS tube.

[0010] In an embodiment of the present application, each of the first impedance circuit and the second impedance circuit includes at least two resistors, and the at least two resistors are connected in series.

[0011] In one embodiment of the present application, the insulation impedance detection circuit also includes a third impedance circuit, and the first end of the voltage sampling circuit is connected to the second end of the first impedance circuit and the second end of the second impedance circuit through the third impedance circuit; the third impedance circuit is used to divide the first voltage or the second voltage according to a preset ratio.

[0012] In an embodiment of the present application, the first end of the second impedance circuit is directly connected to the positive DC bus of the DC bus.

[0013] In an embodiment of the present application, the first end of the second impedance circuit is connected to the positive DC bus of the DC bus through a switch module; wherein the controller is connected to the switch module and is used to control the switch module to be normally turned on.

[0014] A second aspect of the present application further provides an electronic device, comprising a DC bus and the insulation impedance detection circuit.

[0015] In the insulation impedance detection circuit of the present application, the positive DC bus is directly connected to the controller through the second impedance circuit and the voltage sampling circuit, and the negative DC bus is connected to the controller through the switching circuit, the first impedance circuit and the voltage sampling circuit. When the insulation impedance test is performed on the DC bus, the controller can obtain the first voltage when the positive DC bus is grounded and the second voltage when the positive DC bus and the negative DC bus are grounded at the same time to calculate the insulation impedance value of the DC bus by controlling the conduction state of the switching circuit. Since the positive DC bus is also grounded when collecting the voltage value of the grounded negative DC bus, the positive DC bus is also grounded at the same time, which can avoid the situation where the collected voltage value is very small, thereby avoiding interference in the transmission process and improving the calculation accuracy of the insulation impedance value of the DC bus. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 It is a schematic block diagram of an insulation impedance detection circuit provided in an embodiment of the present application.

[0017] Figure 2 It is a schematic block diagram of another insulation impedance detection circuit provided in an embodiment of the present application.

[0018] Figure 3 It is a schematic block diagram of a third insulation impedance detection circuit provided in an embodiment of the present application.

[0019] Figure 4 It is a circuit diagram of an insulation impedance detection circuit provided in an embodiment of the present application. DETAILED DESCRIPTION

[0020] It should be noted that in the embodiments of the present application, "at least one" refers to one or more, and "more than one" refers to two or more than two. "And / or" describes the association relationship of associated objects, indicating that three relationships may exist. For example, A and / or B can represent: the existence of A alone, the existence of A and B at the same time, and the existence of B alone, where A and B can be singular or plural. The terms "first", "second", "third", "fourth", etc. (if any) in the specification, claims and drawings of this application are used to distinguish similar objects, rather than to describe a specific order or sequence.

[0021] It should also be noted that the method disclosed in the embodiments of the present application or the method shown in the flowchart includes one or more steps for implementing the method. Without departing from the scope of the claims, the execution order of multiple steps can be interchangeable with each other, and some of the steps can also be deleted.

[0022] At present, for the detection of the insulation impedance of the DC bus, two switching circuits are generally set to control the connection of a certain amount of impedance between the positive DC bus and the ground, and to control the connection of a certain amount of impedance between the negative DC bus and the ground, so as to collect the voltage value when the positive DC bus is grounded, and the voltage value when the negative DC bus is grounded, and calculate the insulation impedance value of the DC bus based on these two voltage values.

[0023] However, the voltage value collected when the negative DC bus is grounded is often very small and is easily disturbed during transmission to the control chip, thereby affecting the accuracy of the final calculation of the insulation impedance value of the DC bus.

[0024] The present application provides an insulation impedance detection circuit and an electronic device for improving the accuracy of calculating the insulation impedance value of a DC bus.

[0025] Please refer to Figure 1 , Figure 1 The present invention provides a schematic block diagram of an insulation impedance detection circuit provided in an embodiment of the present application, wherein the insulation impedance detection circuit 100 is applied to a DC bus, and the insulation impedance detection circuit 100 includes a switch circuit 110, a first impedance circuit 120, a second impedance circuit 130, a voltage sampling circuit 140 and a controller 150.

[0026] In the embodiment of the present application, the first end of the switch circuit 110 is connected to the negative DC bus BUS- of the DC bus, the second end of the switch circuit 110 is connected to the first end of the first impedance circuit 120, and the second end of the first impedance circuit 120 is connected to the first end of the voltage sampling circuit 140 and grounded. The first end of the second impedance circuit 130 is connected to the positive DC bus BUS+ of the DC bus, and the second end of the second impedance circuit 130 is connected to the first end of the voltage sampling circuit 140 and grounded. The controller 150 is connected to the control end of the switch circuit 110 and the second end of the voltage sampling circuit 140. Among them, the controller 150 is used to control the switch circuit 110 to turn off, and obtain the first voltage of the second end of the voltage sampling circuit 140, control the switch circuit 110 to turn on, and obtain the second voltage of the second end of the voltage sampling circuit 140, and obtain the insulation impedance value of the DC bus according to the first voltage and the second voltage. Among them, the first end of the second impedance circuit 130 is directly connected to the positive DC bus BUS+ of the DC bus.

[0027] In some embodiments, the controller 150 may first control the switch circuit 110 to turn off, thereby obtaining a first voltage when the positive DC bus BUS+ is grounded, and then control the switch circuit 110 to turn on, thereby obtaining a second voltage when the positive DC bus BUS+ and the negative DC bus BUS- are grounded at the same time, and then obtain the insulation impedance value of the DC bus according to the first voltage and the second voltage. Alternatively, the second voltage may be obtained first and then the first voltage may be obtained.

[0028] For example, the insulation resistance of the DC bus can be calculated according to the following formula:

[0029]

[0030]

[0031] R ISO =R m / / R n .

[0032] Among them, R m is the insulation resistance of the positive DC bus BUS+ to ground, R n is the insulation resistance value of the negative DC bus BUS- to ground, V 1 is the first voltage, V 2 is the second voltage, R 1 is the total resistance of the first impedance circuit 120, R 2 is the total resistance of the second impedance circuit 130, U BUS is the DC bus voltage value, R ISO The voltage sampling circuit 140 is used to proportionally reduce the voltage of the negative DC bus BUS- or the positive DC bus BUS+.

[0033] It can be understood that in the insulation impedance detection circuit of the present application, the positive DC bus BUS+ is directly connected to the controller through the second impedance circuit and the third impedance circuit, and the negative DC bus BUS- is connected to the controller through the switching circuit, the first impedance circuit and the third impedance circuit. When the DC bus is subjected to an insulation impedance test, the controller can obtain the first voltage when the positive DC bus BUS+ is grounded and the second voltage when the positive DC bus BUS+ and the negative DC bus BUS- are grounded at the same time by controlling the conduction state of the switching circuit to calculate the insulation impedance value of the DC bus. Since the positive DC bus BUS+ is also grounded when collecting the voltage value of the grounded negative DC bus BUS-, the positive DC bus BUS+ can be avoided from being very small, thereby avoiding interference during the transmission process and improving the calculation accuracy of the insulation impedance value of the DC bus.

[0034] In some embodiments, a first end of the second impedance circuit 130 is connected to the positive DC bus BUS+ through a switch module, and the controller 150 is connected to the switch module and is used to control the switch module to be normally turned on.

[0035] Please refer to Figure 2 , Figure 2 This is a schematic block diagram of another insulation impedance detection circuit 100a provided in an embodiment of the present application. Figure 2The insulation resistance detection circuit 100a shown in FIG. Figure 1 Compared with the insulation impedance detection circuit 100 shown in FIG. Figure 2 The switch circuit 110 of the insulation resistance detection circuit 100 a shown includes a relay unit 111 and a relay control unit 112 .

[0036] The first end of the relay unit 111 is connected to the negative DC bus BUS-, and the second end of the relay unit 111 is connected to the first end of the first impedance circuit 120. The relay control unit 112 is connected to the control end of the relay unit 111 and the controller 150, and the relay control unit 112 is used to receive a control signal from the controller 150, and control the relay unit 111 to be turned off or on according to the control signal.

[0037] Please refer to Figure 3 , Figure 3 This is a schematic block diagram of a third insulation impedance detection circuit 100b provided in an embodiment of the present application. Figure 3 The insulation impedance detection circuit 100b shown in FIG. Figure 2 Compared with the insulation impedance detection circuit 100a shown in FIG. Figure 3 The insulation impedance detection circuit 100 b shown further includes a third impedance circuit 160 .

[0038] In the embodiment of the present application, the first end of the voltage sampling circuit 140 is connected to the second end of the first impedance circuit 120 and the second end of the second impedance circuit 130 through the third impedance circuit 160. The third impedance circuit 160 is used to detect the first voltage or the second voltage and divide it according to a preset ratio so that the first voltage or the second voltage is within the processable range of the controller 150, thereby preventing the first voltage or the second voltage from being too large and causing adverse effects on the controller 150.

[0039] Please refer to Figure 4 , Figure 4 4 is a circuit diagram of an insulation impedance detection circuit provided in an embodiment of the present application. The insulation impedance detection circuit 400 includes a switch circuit 410, a first impedance circuit 420, a second impedance circuit 430, a third impedance circuit 440, and a controller ( Figure 4 not shown).

[0040] The switch circuit 410 includes a relay unit 411 and a relay control unit 412. The relay unit 411 includes a relay RY1, a diode D1 and a voltage regulator diode ZD1. The first switch pin of the relay RY1 is connected to the negative DC bus BUS-, the second switch pin of the relay RY1 is connected to the first impedance circuit 420, the negative pin of the relay RY1 is connected to the relay control unit 412, and the positive pin of the relay RY1 is used to receive the power supply voltage. The positive electrode of the diode D1 is connected to the negative pin of the relay RY1, the negative electrode of the diode D1 is connected to the negative electrode of the voltage regulator diode ZD1, and the positive electrode of the voltage regulator diode ZD1 is connected to the positive pin of the relay RY1. The relay control unit 412 includes a switch tube Q1, a first resistor R1, a second resistor R2 and a capacitor C1. The first end of the switch tube Q1 is connected to the relay unit 411, the second end of the switch tube Q1 is grounded, and the control end of the switch tube Q1 is grounded through the first resistor R1 and the capacitor C1 respectively. The control end of the switch tube Q1 is also connected to the controller through the second resistor R2.

[0041] It can be understood that in the above embodiment, when the controller transmits a control signal to control the switch tube Q1 to turn on, the switch excitation coil of the relay RY1 receives the power supply voltage to obtain electric energy, so that the moving contact 3 and the moving contact 4 of the relay RY1 are pushed up, and then the moving contacts 3 and 4 are closed with the static contacts 5 and 6 respectively, so that the relay RY1 conducts the connection between the negative DC bus BUS- and the first impedance circuit 420. Similarly, when the controller transmits a control signal to control the switch tube Q1 to turn off, the switch excitation coil of the relay RY1 stops receiving the power supply voltage, so that the moving contacts 3 and 4 of the relay RY1 are reset, and then the contacts 3 and 4 are disconnected from the static contacts 5 and 6 respectively, so that the relay RY1 turns off the connection between the negative DC bus BUS- and the first impedance circuit 420.

[0042] In some embodiments, the switch tube Q1 includes a MOS tube, the first end of the switch tube Q1 is the drain of the MOS tube, the second end of the switch tube Q1 is the source of the MOS tube, and the control end of the switch tube Q1 is the gate of the MOS tube. The first resistor R1 and the capacitor C1 are used to provide a discharge path for the parasitic Miller capacitance of the MOS tube, thereby preventing the source and drain of the MOS tube from being broken down, or preventing the accumulation of charge from causing the MOS tube to be mis-conducted. The diode D1 is used to prevent the leakage inductance current of the relay RY1 from breaking down the MOS tube.

[0043] In the embodiment of the present application, the first impedance circuit 420 includes a third resistor R3 and a fourth resistor R4, and the third resistor R3 and the fourth resistor R4 are connected in series and respectively connected to the second end of the switch circuit 410 and the first end of the third impedance circuit 440. The second impedance circuit 430 includes a fifth resistor R5 and a sixth resistor R6, and the fifth resistor R5 and the sixth resistor R6 are connected in series and respectively connected to the positive DC bus BUS+ and the first end of the third impedance circuit 440. The third impedance circuit 440 includes a seventh resistor R7, an eighth resistor R8, a ninth resistor R9, a tenth resistor R10 and an eleventh resistor R11, and the seventh resistor R7, the eighth resistor R8, the ninth resistor R9, the tenth resistor R10 and the eleventh resistor R11 are connected in series and connected to the controller. It can be understood that the first impedance circuit 420, the second impedance circuit 430 and the third impedance circuit 440 use three groups of resistors to set separately to share the voltage value and power of the loop, thereby avoiding damage to the impedance circuit.

[0044] It can be understood that each of the first impedance circuit 420 , the second impedance circuit 430 , and the third impedance circuit 440 includes at least two resistors, and the at least two resistors are connected in series.

[0045] The present application also provides an electronic device, wherein the electronic device includes a DC bus and the insulation impedance detection circuit in any of the above embodiments. It can be understood that the beneficial effects of the electronic device can refer to the beneficial effects of the insulation impedance detection circuit in the above embodiments, which will not be repeated here.

[0046] The embodiments described above are merely preferred embodiments of the present application and are not intended to limit the scope of the present application. Without departing from the design spirit of the present application, various modifications and improvements made to the technical solutions of the present application by ordinary technicians in this field should fall within the protection scope determined by the claims of the present application.

Claims

1. A DC bus insulation impedance detection circuit, characterized in that: The insulation impedance detection circuit includes a switch circuit, a first impedance circuit, a second impedance circuit, a voltage sampling circuit and a controller; The first end of the switch circuit is connected to the negative DC bus of the DC bus, the second end of the switch circuit is connected to the first end of the first impedance circuit, the second end of the first impedance circuit is connected to the first end of the voltage sampling circuit and is grounded; the first end of the second impedance circuit is connected to the positive DC bus of the DC bus, the second end of the second impedance circuit is connected to the first end of the voltage sampling circuit and is grounded; The controller is connected to the control end of the switch circuit and the second end of the voltage sampling circuit, and the controller is used for: Controlling the switch circuit to turn off, and acquiring a first voltage through the voltage sampling circuit; Controlling the switch circuit to be turned on, and obtaining a second voltage through the voltage sampling circuit; An insulation resistance value of the DC bus is obtained according to the first voltage and the second voltage.

2. The insulation impedance detection circuit according to claim 1, characterized in that: The switch circuit includes a relay unit and a relay control unit; A first end of the relay unit is connected to the negative DC bus, and a second end of the relay unit is connected to the first end of the first impedance circuit; The relay control unit is connected to the control end of the relay unit and the controller. The relay control unit is used to receive a control signal from the controller and control the relay unit to be turned off or on according to the control signal.

3. The insulation impedance detection circuit according to claim 2, characterized in that: The relay unit includes a relay, a diode and a voltage stabilizing diode; The first switch pin of the relay is connected to the negative DC bus, the second switch pin of the relay is connected to the first end of the first impedance circuit, the negative pin of the relay is connected to the relay control unit, and the positive pin of the relay is used to receive the power supply voltage; The anode of the diode is connected to the cathode pin of the relay, the cathode of the diode is connected to the cathode of the voltage stabilizing diode, and the anode of the voltage stabilizing diode is connected to the anode pin of the relay.

4. The insulation impedance detection circuit according to claim 2, characterized in that: The relay control unit includes a switch tube, a first resistor, a second resistor and a capacitor; The first end of the switch tube is connected to the relay unit, the second end of the switch tube is grounded, and the control end of the switch tube is grounded through the first resistor and the capacitor connected in parallel; The control end of the switch tube is also connected to the controller through the second resistor.

5. The insulation impedance detection circuit according to claim 4, characterized in that: The switch tube comprises a MOS tube, the first end of the switch tube is the drain of the MOS tube, the second end of the switch tube is the source of the MOS tube, and the control end of the switch tube is the gate of the MOS tube.

6. The insulation impedance detection circuit according to claim 1, characterized in that: Each of the first impedance circuit and the second impedance circuit includes at least two resistors, and the at least two resistors are connected in series.

7. The insulation impedance detection circuit according to claim 1, characterized in that: The insulation impedance detection circuit further includes a third impedance circuit, and the first end of the voltage sampling circuit is connected to the second end of the first impedance circuit and the second end of the second impedance circuit through the third impedance circuit; The third impedance circuit is used to divide the first voltage or the second voltage according to a preset ratio.

8. The insulation impedance detection circuit according to any one of claims 1 to 7, characterized in that: The first end of the second impedance circuit is directly connected to the positive DC bus of the DC bus.

9. The insulation impedance detection circuit according to any one of claims 1 to 7, characterized in that: The first end of the second impedance circuit is connected to the positive DC bus of the DC bus through a switch module; Wherein, the controller is connected to the switch module and is used to control the switch module to be normally turned on.

10. An electronic device, characterized in that: The invention comprises a DC bus and an insulation impedance detection circuit as claimed in any one of claims 1 to 9.

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