Discharge circuit

Abstract

The utility model provides a discharge circuit, which comprises a first discharge circuit, a second discharge circuit, a control circuit, a change-over switch and an energy storage element, and is characterized in that one end of each of the first discharge circuit and the second discharge circuit is connected with one end of the energy storage element; the other end of the first discharge circuit and the control end of the change-over switch are both connected with the control circuit, the other end of the second discharge circuit is connected with one end of the change-over switch, and the other end of the change-over switch is grounded; one end of the control circuit is connected with control voltage, the other end of the control circuit is grounded, and one end of the energy storage element is also connected with direct-current bus voltage; when control voltage exists, the control circuit conducts a path between the first discharging circuit and the ground and controls the change-over switch to be switched off. And when the control voltage does not exist, the path between the first discharge circuit and the ground is disconnected, and the change-over switch is controlled to be closed. When the circuit is powered on, the energy storage element can discharge with small current, and when the circuit is powered off, the energy storage element can discharge quickly.

Description

Technical Field

[0001] The present application relates to the field of power electronics, and in particular to a discharge circuit. Background Art

[0002] In the actual application of circuits, energy storage elements, such as capacitors, are often connected in parallel on the DC bus for energy storage support and filtering. When the power is cut off, the capacitor still has energy and may release energy under the influence of external factors, damaging the circuit and causing accidental electric shock to the human body. Therefore, it is necessary to design a corresponding discharge circuit to discharge the energy storage element.

[0003] Currently, for low-voltage capacitors, resistors are often directly connected in parallel at both ends to automatically discharge as a load. However, for high-voltage capacitors connected in parallel to the DC bus, directly using parallel resistors to discharge affects the efficiency and standby power consumption of the circuit. Utility Model Content

[0004] The present application provides a discharge circuit to solve the above-mentioned problem.

[0005] The present application provides a discharge circuit, the discharge circuit comprising: a first discharge circuit, a second discharge circuit, a control circuit, a switch and an energy storage element, the first discharge circuit comprising a first resistor, the second discharge circuit comprising a second resistor;

[0006] One end of the first discharge circuit and the second discharge circuit are both connected to one end of the energy storage element; the other end of the first discharge circuit and the control end of the switch are both connected to the control circuit, the other end of the second discharge circuit is connected to one end of the switch, and the other end of the switch is grounded, wherein the resistance value of the first resistor is greater than the resistance value of the second resistor;

[0007] One end of the control circuit is connected to the control voltage, and the other end of the control circuit is grounded. The control voltage is taken from the DC bus voltage. One end of the energy storage element is also connected to the DC bus voltage, and the other end of the energy storage element is grounded. The control circuit is used to conduct the path between the first discharge circuit and the ground when the control voltage exists, and control the switching switch to be disconnected so that the energy storage element discharges through the first discharge circuit; when the control voltage does not exist, disconnect the path between the first discharge circuit and the ground, and control the switching switch to be closed so that the energy storage element discharges through the second discharge circuit.

[0008] In one example, the discharge circuit further includes: a third resistor:

[0009] One end of the third resistor is connected to the control voltage, and the other end of the third resistor is connected to one end of the control circuit.

[0010] In one example, the control circuit includes a fourth resistor and a photocoupler:

[0011] The first end of the photoelectric coupler is connected to one end of the fourth resistor, which is connected to the control voltage as one end of the control circuit; the second end of the photoelectric coupler is connected to the other end of the fourth resistor, which is grounded as the other end of the control circuit; the third end of the photoelectric coupler is connected to the other end of the first discharge circuit and the control end of the switching switch, and the fourth end of the photoelectric coupler is grounded; the photoelectric coupler is used to conduct the path between the first discharge circuit and the ground when power is supplied, and disconnect the path between the first discharge circuit and the ground when power is disconnected.

[0012] In one example, the control circuit includes a diode and a relay, a relay envelope coil and a normally open contact switch:

[0013] One end of the coil is connected to the anode of the diode and the control voltage, and the other end of the coil is connected to the cathode of the diode and grounded;

[0014] One end of the normally open contact switch is connected to the other end of the first discharge circuit and the control end of the switching switch, and the other end of the normally open contact switch is grounded. The normally open contact switch is used to close when the coil is energized to conduct the path between the first discharge circuit and the ground, and to open when the coil is de-energized to disconnect the path between the first discharge circuit and the ground.

[0015] In one example, the switch is an NMOS transistor:

[0016] The source of the NMOS transistor is connected to the other end of the second discharge circuit as one end of the switching switch; the gate of the NMOS transistor is connected to the control circuit as the control end of the switching switch; and the drain of the NMOS transistor is grounded as the other end of the switching switch.

[0017] In one example, the discharge circuit further includes a voltage stabilization module:

[0018] One end of the voltage stabilizing module is connected to the control end of the switch, and the other end of the voltage stabilizing module is grounded.

[0019] In one example, the voltage stabilizing module includes a fifth resistor:

[0020] One end of the fifth resistor is connected to the control end of the switch, and the other end of the fifth resistor is grounded.

[0021] In one example, the voltage stabilizing module further includes: a voltage stabilizer:

[0022] One end of the voltage stabilizer is connected to one end of the fifth resistor, and the other end of the voltage stabilizer is grounded.

[0023] In one example, the energy storage element is a capacitor.

[0024] In one example, the first resistor is a chip resistor, and the second resistor is a cement resistor.

[0025] In the discharge circuit provided by the present application, one end of the first discharge circuit and the second discharge circuit are both connected to one end of the energy storage element; the other end of the first discharge circuit and the control end of the switch are both connected to the control circuit, the other end of the second discharge circuit is connected to one end of the switch, and the other end of the switch is grounded; one end of the control circuit is connected to the control voltage, and the other end is grounded, and one end of the energy storage element is also connected to the DC bus voltage, and the other end is grounded. When there is a DC bus voltage, that is, when there is a control voltage, the control circuit is turned on, and the switch is controlled to be disconnected, so that the energy storage element is grounded and discharged through the first discharge circuit, and when there is no DC bus voltage, that is, when there is no control voltage, the control circuit is disconnected, and the switch is controlled to be turned on, so that the control circuit controls the energy storage element to discharge through the second discharge circuit. Since the resistance value of the first resistor is large, when there is a DC bus voltage, the current discharged by the energy storage element through the first discharge circuit is small, thereby supporting the discharge of the energy storage element with extremely small power consumption, and since the resistance value of the second resistor is small, when there is no DC bus voltage, the current discharged by the energy storage element through the second discharge circuit is large, thereby realizing the rapid discharge of the energy storage element. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the present application and, together with the description, serve to explain the principles of the present application.

[0027] Figure 1 This is a schematic diagram of an application scenario for this application example;

[0028] Figure 2 A schematic diagram of a discharge circuit provided in Example 1 of the present application;

[0029] Figure 3 A schematic diagram of the structure of another discharge circuit provided in Embodiment 1 of the present application;

[0030] Figure 4 A structural schematic diagram of another discharge circuit provided in Embodiment 1 of the present application;

[0031] Figure 5 A schematic diagram of the structure of another discharge circuit provided in Embodiment 1 of the present application;

[0032] Figure 6 A structural schematic diagram of another discharge circuit provided in Embodiment 1 of the present application;

[0033] Figure 7 A schematic diagram of the structure of another discharge circuit provided in Embodiment 1 of the present application;

[0034] Figure 8 A schematic diagram of the structure of another discharge circuit provided in Embodiment 1 of the present application;

[0035] Fig. 9 A schematic diagram of the structure of another discharge circuit provided in Embodiment 1 of the present application;

[0036] Fig.10 This is a structural schematic diagram of another discharge circuit provided in Example 1 of the present application.

[0037] Description of reference numerals:

[0038] R1: first resistor;

[0039] R2: second resistor;

[0040] R3: the third resistor;

[0041] R4: the fourth resistor;

[0042] R5: the fifth resistor;

[0043] U1: optocoupler;

[0044] ZD1: voltage regulator;

[0045] T1: NMOS transistor;

[0046] C1: capacitor;

[0047] K1: relay;

[0048] D1: diode.

[0049] The above drawings have shown clear embodiments of the present application, which will be described in more detail later. These drawings and text descriptions are not intended to limit the scope of the present application in any way, but to illustrate the concept of the present application to those skilled in the art by referring to specific embodiments. DETAILED DESCRIPTION

[0050] Exemplary embodiments will be described in detail herein, examples of which are shown in the accompanying drawings. When the following description refers to the drawings, unless otherwise indicated, the same numbers in different drawings represent the same or similar elements. The implementations described in the following exemplary embodiments do not represent all implementations consistent with the present application. Instead, they are merely examples of systems and systems consistent with some aspects of the present application as detailed in the appended claims.

[0051] Figure 1This is a schematic diagram of the application scenario of the present application example. In the actual application of the circuit, energy storage elements, such as capacitors, are often connected in parallel on the DC bus for energy storage support and filtering. When the power is cut off, the capacitor still contains energy and may release energy under the influence of external factors, damaging the circuit. There is also a risk of accidental electric shock to the human body, so it is necessary to design a corresponding discharge circuit to discharge the energy storage element.

[0052] At present, for low-voltage capacitors, resistors are often directly connected in parallel at both ends to automatically discharge as a load. For high-voltage capacitors connected in parallel to the DC bus, directly using parallel resistors to discharge affects the efficiency and standby power consumption of the circuit. Therefore, a discharge circuit is designed in which when the DC bus is high voltage, the energy storage element can discharge with a very small current, and when the DC bus loses voltage, the energy storage element can discharge quickly with a large current.

[0053] In the discharge circuit provided by the present application, when there is a DC bus voltage, that is, when there is a control voltage, the control circuit conducts the path between the first discharge circuit and the ground, controls the switching switch to be disconnected to disconnect the second discharge circuit, so that the energy storage element is controlled to discharge through the first discharge circuit, and when there is no DC bus voltage, that is, when there is no control voltage, the control circuit disconnects the path between the first discharge circuit and the ground, controls the switching switch to be turned on to conduct the second discharge circuit, and the control circuit controls the energy storage element to discharge through the second discharge circuit. Since the resistance value of the first resistor is large, when there is a DC bus voltage, the current discharged by the energy storage element through the first discharge circuit is small, thereby supporting the discharge of the energy storage element with extremely small power consumption, and since the resistance value of the second resistor is small, when there is no DC bus voltage, the current discharged by the energy storage element through the second discharge circuit is large, thereby realizing the rapid discharge of the energy storage element.

[0054] It should be noted that the brief description of terms in this application is only for the convenience of understanding the embodiments described below, and is not intended to limit the embodiments of this application. Unless otherwise specified, these terms should be understood according to their ordinary and common meanings.

[0055] The technical solutions of the present application and the technical solutions of the present application are described in detail with specific embodiments below. The following specific embodiments can be combined with each other, and the same or similar concepts or processes may not be repeated in some embodiments. In the description of the present application, unless otherwise clearly specified and limited, each term should be understood in a broad sense in the art. The embodiments of the present application will be described below in conjunction with the accompanying drawings.

[0056] Embodiment 1

[0057] Figure 2 A schematic diagram of a discharge circuit provided in Example 1 of the present application is shown in FIG. Figure 2 As shown, the discharge circuit includes: a first discharge circuit, a second discharge circuit, a control circuit, a switch and an energy storage element, the first discharge circuit includes a first resistor R1, and the second discharge circuit includes a second resistor R2;

[0058] One end of the first discharge circuit and the second discharge circuit are both connected to one end of the energy storage element; the other end of the first discharge circuit and the control end of the switch are both connected to the control circuit, the other end of the second discharge circuit is connected to one end of the switch, and the other end of the switch is grounded, wherein the resistance value of the first resistor R1 is greater than the resistance value of the second resistor R2;

[0059] One end of the control circuit is connected to the control voltage, and the other end of the control circuit is grounded. The control voltage is taken from the DC bus voltage. One end of the energy storage element is also connected to the DC bus voltage, and the other end of the energy storage element is grounded. The control circuit is used to conduct the path between the first discharge circuit and the ground when the control voltage exists, and control the switching switch to be disconnected so that the energy storage element discharges through the first discharge circuit; when the control voltage does not exist, disconnect the path between the first discharge circuit and the ground, and control the switching switch to be closed so that the energy storage element discharges through the second discharge circuit.

[0060] Combined with the scenario example, when the DC bus is high voltage, that is, when the DC bus voltage exists, the DC bus is a conductive device for transmitting and distributing DC power. Since the control voltage is taken from the DC bus voltage, the control voltage also exists when the DC bus is high voltage. Since the conduction of the control circuit depends on whether the control voltage exists, when the control voltage exists, the control circuit is turned on, the first resistor R1 is grounded, and the path between the first discharge circuit and the ground is turned on. When the control circuit is turned on, the control circuit controls the switch to be disconnected to disconnect the second discharge circuit. Therefore, at this time, the energy storage element will discharge through the first discharge circuit and transmit the electric energy to the ground. Since the first discharge circuit includes the first resistor R1, the energy storage element will discharge through the first resistor R1 through the first discharge circuit. When the DC bus loses pressure, that is, when there is no DC bus voltage and control voltage, the control circuit is disconnected, the path between the first discharge circuit and the ground is disconnected, that is, the circuit between the first resistor R1 and the ground is disconnected, and the energy storage element cannot discharge through the first discharge circuit. At the same time, the control circuit controls the switching switch to be turned on. Since the second discharge circuit includes the second resistor R2, the second resistor R2 is grounded through the switching switch, that is, the second discharge circuit is turned on, so when there is no control voltage, the energy storage element is discharged through the second discharge circuit. Based on the circuit provided in this example, since the resistance value of the first resistor is large, when there is a DC bus voltage, the current discharged by the energy storage element through the first discharge circuit is small, thereby supporting the discharge of the energy storage element with extremely small power consumption, and since the resistance value of the second resistor is small, when there is no DC bus voltage, the current discharged by the energy storage element through the second discharge circuit is large, thereby realizing rapid discharge of the energy storage element.

[0061] Optional, Figure 3 This is a schematic diagram of another discharge circuit provided in Example 1 of the present application. Figure 3 As shown, the discharge circuit further includes: a third resistor R3:

[0062] One end of the third resistor R3 is connected to the control voltage, and the other end of the third resistor R3 is connected to one end of the control circuit.

[0063] Combined with the scenario example, when the DC bus is high voltage, that is, when there is a control voltage, if the control voltage is directly connected to the control circuit, it may cause the voltage received by the control circuit to be too large. A third resistor R3 can be connected between the control voltage and the control circuit. The third resistor R3 can divide the control voltage. The third resistor R3 with an appropriate resistance value can be selected so that the voltage obtained by the control circuit is sufficient to turn on the control circuit, and it is not too large to be damaged. The voltage obtained by the control circuit can be used as a turn-on signal for the control circuit. Based on the circuit provided in this example, a suitable resistance value can be selected for the third resistor so that the voltage connected to the control circuit is sufficient to turn on the control circuit, and it is not too large to be damaged.

[0064] Optional, Figure 4 A structural diagram of another discharge circuit provided in the first embodiment of the present application is shown in FIG. Figure 4 As shown, the control circuit includes a fourth resistor R4 and a photocoupler U1:

[0065] A first end of the photoelectric coupler U1 is connected to one end of the fourth resistor R4, which is connected to the control voltage as one end of the control circuit; a second end of the photoelectric coupler U1 is connected to the other end of the fourth resistor R4, which is grounded as the other end of the control circuit; a third end of the photoelectric coupler U1 is connected to the other end of the first discharge circuit and the control end of the switching switch; and a fourth end of the photoelectric coupler U1 is grounded; the photoelectric coupler U1 is used to conduct the path between the first discharge circuit and the ground when powered on, and to disconnect the path between the first discharge circuit and the ground when powered off.

[0066] Combined with the scenario example, the fourth resistor R4 can divide the control voltage together with the third resistor R3, and the resistance values ​​of the third resistor R3 and the fourth resistor R4 can be appropriately selected so that the voltage divided by the fourth resistor R4 is the turn-on voltage of the photoelectric coupler U1. When the voltage divided by the fourth resistor R4 is the turn-on voltage of the photoelectric coupler U1, the photoelectric coupler U1 is turned on. Specifically, the photoelectric coupler U1 is composed of a light-emitting end and a light-receiving end, and the light-emitting end can be a light-emitting diode. When the photoelectric coupler U1 is turned on, the light-emitting diode is turned on and works, so that the light-receiving end of the photoelectric coupler U1 receives the light energy emitted by the light-emitting diode and turns on. When the light-receiving end of the photoelectric coupler U1 is turned on, the first discharge circuit is grounded through the light-receiving end of the photoelectric coupler U1 to conduct the path between the first discharge circuit and the ground; similarly, when there is no control voltage, the light-emitting diode is turned on and does not work, and the light-receiving end of the photoelectric coupler U1 is disconnected when there is no light energy. At this time, the path between the first discharge circuit and the ground is disconnected to disconnect the path between the first discharge circuit and the ground. Based on the control circuit provided in this example, the on-voltage of the photocoupler U1 can be obtained based on the voltage division of the control voltage by the fourth resistor, and the photocoupler controls whether the path between the first discharge circuit and the ground is turned on.

[0067] Optional, Figure 5 A structural diagram of another discharge circuit provided in the first embodiment of the present application is shown in FIG. Figure 5 As shown, the control circuit includes a diode D1 and a relay K1, and the envelope coil of the relay K1 and a normally open contact switch:

[0068] One end of the coil is connected to the positive electrode of the diode D1 and the control voltage, and the other end of the coil is connected to the negative electrode of the diode D1 and is grounded;

[0069] One end of the normally open contact switch is connected to the other end of the first discharge circuit and the control end of the switching switch, and the other end of the normally open contact switch is grounded. The normally open contact switch is used to close when the coil is energized to conduct the path between the first discharge circuit and the ground, and to open when the coil is de-energized to disconnect the path between the first discharge circuit and the ground.

[0070] In combination with the scenario example, when there is a control voltage, and the control circuit opening signal is obtained by dividing the control voltage by the third resistor R3, the coil of the relay K1 is energized. At this time, the normally open contact switch is closed because the coil is energized, so that the first discharge circuit is grounded through the normally open contact switch to conduct the path between the first discharge circuit and the ground. When there is no control voltage, the control circuit has no opening signal, and the coil of the relay K1 is de-energized. At this time, the normally open contact switch is disconnected, and the path between the first discharge circuit and the ground is disconnected. If the current flowing through the control circuit is grounded through the diode D1, the normally open contact switch of the relay K1 may not be tightly closed, so the positive pole of the diode D1 is grounded, and the negative pole is connected to the other end of the third resistor R3, and a diode is reversely connected in parallel at both ends of the relay to prevent current from flowing through the diode D1, so that the current is all relay K1, so that the relay K1 can be tightly closed.

[0071] Optional, Figure 6 A structural diagram of another discharge circuit provided in the first embodiment of the present application is shown in FIG. Figure 6 As shown, the switch is an NMOS transistor T1:

[0072] The source of the NMOS transistor T1 is connected to the other end of the second discharge circuit as one end of the switch; the gate of the NMOS transistor T1 is connected to the control circuit as the control end of the switch; and the drain of the NMOS transistor T1 is grounded as the other end of the switch.

[0073] Combined with the scenario example, the switching switch can select a transistor switch of N-type metal-oxide-semiconductor (NMOS) structure. When there is a DC bus voltage, that is, when there is a control voltage, the control switch controls the path between the first discharge circuit and the ground to be turned on. At this time, the gate of the NMOS transistor T1 is grounded, and the voltage of the gate of the NMOS transistor T1 is extremely small, generally less than 1V, which does not meet the turn-on voltage of the NMOS transistor T1. Therefore, the source and drain of the NMOS transistor T1 are disconnected at this time to disconnect the second discharge circuit. At this time, the energy storage element will discharge through the first discharge circuit. When there is no DC bus voltage, that is, there is no control voltage, at this time, the path between the first discharge circuit and the ground is disconnected. At this time, the voltage of the gate of the NMOS transistor T1 depends on the voltage at the other end of the first resistor R1. When the voltage at the other end of the first resistor R1 meets the turn-on voltage of the NMOS transistor T1, the source and drain of the NMOS transistor T1 are turned on. At this time, the second conductive circuit is turned on, so the energy storage element is discharged through the second conductive circuit. Optionally, the NMOS transistor T1 can be replaced by a triode or an insulated-gate bipolar transistor (IGBT). Based on the circuit provided in this example, the on and off control of the second discharge circuit can be achieved by controlling the on and off of the source and drain of the NMOS transistor.

[0074] Optional, Figure 7 A structural diagram of another discharge circuit provided in the first embodiment of the present application is shown in FIG. Figure 7 As shown, the discharge circuit also includes a voltage stabilization module:

[0075] One end of the voltage stabilizing module is connected to the control end of the switch, and the other end of the voltage stabilizing module is grounded.

[0076] Combined with the scenario example, when there is no DC bus voltage and control voltage, the control module is disconnected, and the energy storage element is first discharged through the first resistor R1 and the voltage stabilizing module. At this time, the voltage stabilizing module and the first resistor R1 divide the voltage of the energy storage element discharge to obtain the gate voltage of the NMOS transistor T1. At this time, the gate voltage of the NMOS transistor T1 is the voltage at the other end of the first resistor R1. Generally, when the energy storage element just starts to discharge, the voltage at the other end of the first resistor R1 is generally greater than the on-voltage of the NMOS transistor T1. Therefore, when the gate voltage is greater than the NMOS transistor T1, the gate voltage of the NMOS transistor T1 is greater than the on-voltage of the NMOS transistor T1. When the conduction voltage of the body tube T1 is reached, the source and drain of the NMOS transistor T1 are conducted, and the second discharge circuit is conducted at this time. Since the resistance of the first resistor R1 is greater than the resistance of the second resistor R2, when the second discharge circuit is conducted, the energy storage element will be discharged through the second discharge circuit until the voltage of the energy storage element drops to a voltage at which the voltage at the other end of the first resistor R1 is less than the conduction voltage of the NMOS transistor T1. The source and drain of the NMOS transistor T1 are disconnected, and the second discharge circuit is disconnected. The energy storage element is discharged again through the first resistor R1 and the voltage stabilizing module. Based on the circuit provided in this example, the voltage discharged by the energy storage element can be divided by the first resistor R1 and the voltage stabilizing module to obtain the gate voltage of the NMOS transistor T1, thereby controlling the conduction and shutdown of the NMOS transistor T1.

[0077] Optional, Figure 8 A structural diagram of another discharge circuit provided in the first embodiment of the present application is shown in FIG. Figure 8 As shown, the voltage stabilizing module includes a fifth resistor R5:

[0078] One end of the fifth resistor R5 is connected to the control end of the switch, and the other end of the fifth resistor R5 is grounded.

[0079] Combined with the scenario example, the voltage division of the energy storage element is realized by the fifth resistor R5. When the DC bus voltage and the control voltage do not exist, the control module is disconnected, and the energy storage element is first discharged through the first resistor R1 and the fifth resistor R5. At this time, the fifth resistor R5 and the first resistor R1 divide the voltage of the discharged energy storage element to obtain the gate voltage of the NMOS transistor T1. At this time, the gate voltage of the NMOS transistor T1 is the voltage at the other end of the first resistor R1. Generally, when the energy storage element just starts to discharge, the voltage at the other end of the first resistor R1 is generally greater than the on-voltage of the NMOS transistor T1. When the gate voltage of the NMOS transistor T1 is greater than the turn-on voltage of the NMOS transistor T1, the source and drain of the NMOS transistor T1 are turned on, and the second discharge circuit is turned on. Since the resistance of the first resistor R1 is greater than the resistance of the second resistor R2, when the second discharge circuit is turned on, the energy storage element will be discharged through the second discharge circuit until the voltage of the energy storage element drops to a voltage at which the voltage at the other end of the first resistor R1 is less than the turn-on voltage of the NMOS transistor T1. The source and drain of the NMOS transistor T1 are disconnected, and the second discharge circuit is disconnected. The energy storage element is discharged again through the first resistor R1 and the fifth resistor R5. Based on the circuit provided in this example, the voltage discharged by the energy storage element can be divided by the first resistor R1 and the fifth resistor R5 to obtain the gate voltage of the NMOS transistor T1, thereby controlling the on and off of the NMOS transistor T1.

[0080] Optional, Fig. 9 A structural diagram of another discharge circuit provided in the first embodiment of the present application is shown in FIG. Fig. 9 As shown, the voltage regulator module also includes: voltage regulator ZD1:

[0081] One end of the voltage stabilizer ZD1 is connected to one end of the fifth resistor R5 , and the other end of the voltage stabilizer ZD1 is grounded.

[0082] Combined with the scenario example, the voltage regulator ZD1 and the fifth resistor R5 are connected in parallel to form a voltage regulator module. The voltage regulator ZD1 exists to reduce the voltage division of the voltage regulator module, thereby increasing the voltage division of the first resistor R1, so as to prevent the voltage at the other end of the first resistor R1 from being too large when the energy storage element just starts to discharge, causing the gate of the NMOS transistor T1 to be over-voltage and breakdown. Selecting a suitable first resistor R1, fifth resistor R5 and voltage regulator ZD1 can ensure that when the energy storage element just starts to discharge, the voltage at the other end of the first resistor R1 is prevented from being too large, and when the energy storage element is discharged again through the first resistor R1 and the voltage regulator module, the voltage of the energy storage element discharge has dropped below the safe voltage for the human body, and will not cause harm to the human body when it is accidentally touched.

[0083] Optional, Fig.10 A structural diagram of another discharge circuit provided in the first embodiment of the present application is shown in FIG. Fig.10 As shown, the energy storage element is a capacitor C1.

[0084] Combined with the scenario example, capacitor C1 is connected in parallel with both ends of the DC bus. When the DC bus voltage exists, it can store the electric energy in the circuit and filter the electric energy signal of the DC bus. At this time, capacitor C1 will also discharge through the discharge circuit. Since the second discharge circuit is disconnected when the DC bus voltage exists, capacitor C1 will discharge through the first discharge circuit. Since the resistance of the first resistor R1 in the first discharge circuit is large, the current flowing through the first discharge circuit is extremely small. At this time, capacitor C1 will discharge through the first discharge circuit with an extremely small current.

[0085] When there is no DC bus voltage, there is generally a large amount of electrical energy in the capacitor, which may release energy under the influence of external factors, destroy the circuit, and there is also a hidden danger of causing accidental electric shock to the human body, so the electrical energy in the capacitor C1 needs to be discharged quickly. At this time, the first discharge circuit is disconnected and the second discharge circuit is closed, so at this time the capacitor C1 will be discharged through the first and second discharge circuits. Since the resistance value of the second resistor R2 in the second discharge circuit is small, the current flowing through the second discharge circuit is extremely large, and at this time the capacitor C1 will be discharged quickly through the second discharge circuit with an extremely large current. When the electrical energy in the capacitor is less than a certain threshold, the switching switch in the second discharge circuit will be disconnected when it fails to reach the conduction voltage. At this time, the second discharge circuit is disconnected and discharged through the first resistor and the voltage stabilizing module. However, at this time, the voltage discharged by the energy storage element has dropped below the safe voltage for the human body, and will not cause harm to the human body when it is accidentally touched by the human body.

[0086] Optionally, the first resistor R1 is a chip resistor, and the second resistor R2 is a cement resistor.

[0087] In combination with the scenario example, since the resistance of the first resistor R1 is relatively large, the first resistor R1 can be selected as a chip resistor, so that the first resistor R1 can meet the requirements of large resistance and small size. Since the resistance of the second resistor R2 is relatively small, the current passing through the second resistor R2 is large, so the second resistor R2 can be selected as a cement resistor, which is conducive to rapid heat dissipation.

[0088] In the discharge circuit provided in this embodiment, when there is a DC bus voltage, that is, when there is a control voltage, the control circuit conducts the path between the first discharge circuit and the ground, controls the switching switch to be disconnected to disconnect the second discharge circuit, so that the energy storage element is controlled to discharge through the first discharge circuit, and when there is no DC bus voltage, that is, when there is no control voltage, the control circuit disconnects the path between the first discharge circuit and the ground, controls the switching switch to be turned on to conduct the second discharge circuit, and the control circuit controls the energy storage element to discharge through the second discharge circuit. Since the resistance value of the first resistor is relatively large, when there is a DC bus voltage, the current discharged by the energy storage element through the first discharge circuit is small, thereby supporting the discharge of the energy storage element with extremely small power consumption, and since the resistance value of the second resistor is relatively small, when there is no DC bus voltage, the current discharged by the energy storage element through the second discharge circuit is large, thereby realizing rapid discharge of the energy storage element.

[0089] Those skilled in the art will readily appreciate other embodiments of the present application after considering the specification and practicing the utility model applied for herein. The present application is intended to cover any modification, use or adaptation of the present application, which follows the general principles of the present application and includes common knowledge or customary technical means in the art that are not applied for by the present application. The specification and examples are to be regarded as exemplary only, and the true scope and spirit of the present application are indicated by the following claims.

[0090] It should be understood that the present application is not limited to the precise structures that have been described above and shown in the drawings, and that various modifications and changes may be made without departing from the scope thereof. The scope of the present application is limited only by the appended claims.

Claims

1. A discharge circuit, characterized in that: The discharge circuit comprises: a first discharge circuit, a second discharge circuit, a control circuit, a switch and an energy storage element, the first discharge circuit comprises a first resistor, and the second discharge circuit comprises a second resistor; Wherein, one end of the first discharge circuit and the second discharge circuit are both connected to one end of the energy storage element; the other end of the first discharge circuit and the control end of the switch are both connected to the control circuit, the other end of the second discharge circuit is connected to one end of the switch, and the other end of the switch is grounded, wherein the resistance value of the first resistor is greater than the resistance value of the second resistor; One end of the control circuit is connected to a control voltage, and the other end of the control circuit is grounded. The control voltage is taken from a DC bus voltage. One end of the energy storage element is also connected to the DC bus voltage, and the other end of the energy storage element is grounded. The control circuit is used to, when the control voltage is present, conduct the path between the first discharge circuit and the ground, and control the switching switch to be disconnected so that the energy storage element discharges through the first discharge circuit; when the control voltage is not present, disconnect the path between the first discharge circuit and the ground, and control the switching switch to be closed so that the energy storage element discharges through the second discharge circuit.

2. The discharge circuit according to claim 1, characterized in that: The discharge circuit further includes: a third resistor: One end of the third resistor is connected to the control voltage, and the other end of the third resistor is connected to one end of the control circuit.

3. The discharge circuit according to claim 2, characterized in that: The control circuit includes a fourth resistor and a photocoupler: The first end of the photoelectric coupler is connected to one end of the fourth resistor, and is connected to the control voltage as one end of the control circuit; the second end of the photoelectric coupler is connected to the other end of the fourth resistor, and is grounded as the other end of the control circuit; the third end of the photoelectric coupler is connected to the other end of the first discharge circuit and the control end of the switching switch, and the fourth end of the photoelectric coupler is grounded; the photoelectric coupler is used to conduct the path between the first discharge circuit and the ground when powered on, and disconnect the path between the first discharge circuit and the ground when powered off.

4. The discharge circuit according to claim 2, characterized in that: The control circuit includes a diode and a relay, and the relay envelope coil and a normally open contact switch: One end of the coil is connected to the anode of the diode and the control voltage, and the other end of the coil is connected to the cathode of the diode and is grounded; One end of the normally open contact switch is connected to the other end of the first discharge circuit and the control end of the switching switch, and the other end of the normally open contact switch is grounded. The normally open contact switch is used to close when the coil is energized to conduct the path between the first discharge circuit and the ground, and to open when the coil is de-energized to disconnect the path between the first discharge circuit and the ground.

5. The discharge circuit according to claim 3, characterized in that: The switch is an NMOS transistor: The source of the NMOS transistor is connected to the other end of the second discharge circuit as one end of the switching switch; the gate of the NMOS transistor is connected to the control circuit as the control end of the switching switch; and the drain of the NMOS transistor is grounded as the other end of the switching switch.

6. The discharge circuit according to claim 5, characterized in that: The discharge circuit also includes a voltage stabilization module: One end of the voltage stabilizing module is connected to the control end of the switch, and the other end of the voltage stabilizing module is grounded.

7. The discharge circuit according to claim 6, characterized in that: The voltage stabilizing module includes a fifth resistor: One end of the fifth resistor is connected to the control end of the switch, and the other end of the fifth resistor is grounded.

8. The discharge circuit according to claim 7, characterized in that: The voltage stabilizing module further includes: a voltage stabilizer: One end of the voltage stabilizer is connected to one end of the fifth resistor, and the other end of the voltage stabilizer is grounded.

9. The discharge circuit according to claim 1, characterized in that: The energy storage element is a capacitor.

10. The discharge circuit according to any one of claims 1 to 9, characterized in that: The first resistor is a chip resistor, and the second resistor is a cement resistor.

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