High-voltage circuit discharging system based on alternating current monitoring

Abstract

The utility model relates to the technical field of electronic circuits, in particular to a high-voltage circuit discharge system based on alternating-current monitoring, which comprises a voltage division module, a discharge module and a discharge module. The first switch module is connected with the voltage dividing module, when the power supply is turned on, a first switch is turned on and forms an electrified loop with a high-voltage capacitor, and when the power supply is turned off, the first switch is turned off; and the discharging module is connected with the first switch module and the high-voltage capacitor, a second switch and the high-voltage capacitor correspondingly form a discharging loop according to the cut-off signal transmitted by the first switch, and a load discharges the high-voltage capacitor. According to the utility model, no extra power supply needs to be introduced, a simple circuit architecture is adopted to form an active dummy load, and the problem that the residual voltage is relatively high when the primary side high-voltage electrolytic capacitor stops working in the switching power supply is solved.

Description

Technical Field

[0001] The utility model relates to the technical field of electronic circuits, in particular to a high-voltage circuit discharge system based on AC monitoring. Background Art

[0002] In an isolated switching power supply circuit, a high-voltage electrolytic capacitor Vbus is generally present on the primary side of the power supply. In some power supply characteristic requirements (such as the design of working timing or the design of various protection circuits), it is required that the Vbus voltage quickly drop to below the safe voltage of 0 to 60Vdc when the power supply is disconnected.

[0003] The existing voltage reduction technology solutions are as follows:

[0004] 1) Directly connect resistors in parallel at both ends of the high-voltage capacitor. This solution can meet the needs of fast capacitor discharge, but the loss leads to reduced power efficiency, and excessive loss on the resistor will cause the resistor temperature to rise, thus affecting performance.

[0005] 2) Active dummy load is formed by monitoring a voltage source based on the mains characterization. When the characterization voltage source changes, the dummy load is turned on to quickly discharge the high-voltage capacitor. This solution solves the problem of normal resistance loss and the problem of high resistance temperature, but the construction of this characterization voltage is difficult and requires an additional voltage source to provide, which increases the cost of the circuit.

[0006] 3) The residual power on the high-voltage capacitor is consumed by the PWM conversion circuit behind the Vbus voltage. This solution is simple and has no additional cost, but it causes PWM to work at a lower voltage alone, the transformer will be saturated, and the voltage drop on the capacitor is difficult to control below the 0-60V level.

[0007] Therefore, there is an urgent need to provide a high voltage circuit discharge system based on AC monitoring to overcome the above defects. Utility Model Content

[0008] The main purpose of the utility model is to provide a high-voltage circuit discharge system based on AC monitoring, which does not require an additional power supply and adopts a simple circuit architecture to form an active dummy load, thereby solving the problem of high residual voltage of the primary-side high-voltage electrolytic capacitor in the switching power supply when it stops working.

[0009] In order to achieve the above purpose, the technical solution adopted by the utility model is:

[0010] High voltage circuit discharge system based on AC monitoring, including:

[0011] Voltage divider module, connected to the power supply, divides the voltage when the power is turned on;

[0012] A first switch module is connected to the voltage dividing module. When the power is turned on, the first switch is turned on to form a power-on loop with the high-voltage capacitor. When the power is turned off, the first switch is turned off.

[0013] The discharge module is connected to the first switch module and the high-voltage capacitor. The second switch forms a discharge loop with the high-voltage capacitor in response to the cut-off signal transmitted by the first switch, and the load discharges the high-voltage capacitor.

[0014] Preferably, the first switch is an Nmos transistor Q700, the second switch is an Nmos transistor Q701, and the gate of the Nmos transistor Q701 is connected to the drain of the Nmos transistor Q700 via a resistor R710.

[0015] Preferably, the cut-off signal is a voltage signal, and when the first switch is turned off, the second switch is turned on.

[0016] Preferably, the first switch module includes: an Nmos tube Q700 whose gate is connected to the voltage divider module, a resistor unit connected to the drain of the Nmos tube Q700 via a resistor R710 and connected in parallel to the discharge module and the high-voltage capacitor, and a voltage regulator tube D700 whose positive electrode is connected to the source of the Nmos tube Q700 and whose negative electrode is connected to the drain of the Nmos tube Q700 via the resistor R710.

[0017] Preferably, the resistance unit comprises a plurality of resistors connected in series.

[0018] Preferably, the discharge module comprises: an NMOS transistor Q701 having a gate connected to the first switch module and a source connected to the high-voltage capacitor, and a discharge load unit connected to the drain of the NMOS transistor Q701.

[0019] Preferably, the discharge load unit includes a resistor R708 and a resistor R709 connected in series.

[0020] Preferably, the voltage dividing module includes a diode D19 and a diode D18 connected in series and in parallel with the power supply, a plurality of voltage dividing resistors connected in series with the diode D19 and the diode D18, and a plurality of the voltage dividing resistors are connected in series.

[0021] The beneficial effects of the utility model are as follows: when the power is turned on, the voltage divider module divides the voltage to conduct the first switch of the first switch module, the first switch module forms a loop with the high-voltage capacitor, and a cutoff signal is generated to the second switch, so that no discharge loop is formed between the discharge module and the high-voltage capacitor, and the load is not consumed. When the power is turned off, the first switch module is cut off, and the second switch is turned on to form a discharge loop with the high-voltage capacitor to discharge the high-voltage capacitor, thereby solving the problem of high residual voltage / slow discharge of the high-voltage capacitor without introducing an additional stable voltage source, and the design also has the characteristics of simple and reliable circuits and low cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 This is a module block diagram of an embodiment of a high voltage circuit discharge system based on AC monitoring of the present utility model.

[0023] Figure 2 The utility model is a circuit diagram of a high voltage circuit discharge system based on AC monitoring.

[0024] Description of the figure numbers in the manual:

[0025] 1-voltage dividing module, 2-first switch module, 3-discharging module. DETAILED DESCRIPTION

[0026] In order to make the technical means, creative features, objectives and effects achieved by the present invention easy to understand, the present invention is further described below in conjunction with specific implementation methods.

[0027] It should be noted that when an element is referred to as being “connected to” or “disposed on” another element, it can be directly on the other element or indirectly on the other element.

[0028] In the description of the present invention, it should be understood that the terms "upper", "lower", "front", "back", "left", "right", "top", "bottom", "inside", "outside", etc., indicating directions or positional relationships, are based on the directions or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific direction, be constructed and operated in a specific direction, and therefore should not be understood as a limitation on the present invention.

[0029] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the features. In the description of this application, "multiple" means two or more, unless otherwise clearly and specifically defined. "Several" means one or more, unless otherwise clearly and specifically defined.

[0030] In the description of this application, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0031] See also Figure 1 and Figure 2 The high-voltage circuit discharge system based on AC monitoring of this embodiment includes: a voltage divider module 1, a first switch module 2 and a discharge module 3, wherein the voltage divider module 1 is connected to the power supply and plays a voltage divider role when the power supply is turned on, the first switch module 2 is connected to the voltage divider module 1, when the power supply is turned on, the first switch is turned on, and forms a power-on loop with the high-voltage capacitor, when the power supply is turned off, the first switch is turned off, the discharge module 3 is connected to the first switch module 2 and the high-voltage capacitor, the second switch forms a discharge loop with the high-voltage capacitor according to the cut-off signal transmitted by the first switch, and the load discharges the high-voltage capacitor. Among them, the first switch is an Nmos tube Q700, the second switch is an Nmos tube Q701, the gate of the Nmos tube Q701 is connected to the drain of the Nmos tube Q700 through a resistor R710, the cut-off signal is a voltage signal, and when the first switch is turned off, the second switch is turned on. More specifically, when the power is turned on, the first voltage divider module 1 divides the voltage, the first switch is turned on, so that a path is formed between the switch module 2 and the high-voltage capacitor, and the voltage provided is not enough to turn on the second switch, the second switch is turned off, and the energy of the load is not consumed. However, when the power is turned off, the first switch is turned off, the second switch is turned on, and a discharge loop is formed with the high-voltage capacitor, and the load discharges the high-voltage capacitor, thereby achieving the problem of discharging the high-voltage capacitor without introducing an additional voltage-stabilized power supply.

[0032] Specifically, the voltage divider module 1 includes a diode D19 and a diode D18 connected in series and in parallel with the power supply, a plurality of voltage divider resistors connected in series with the diode D19 and the diode D18, and a plurality of the voltage divider resistors connected in series. The voltage divider resistors in this embodiment are resistors R700, resistors R701 and resistors R702, resistor R702 is connected to the gate of the Nmos tube Q700, the resistor 702 and the gate of the Nmos tube Q700 are also connected to capacitors C700, capacitors C701 and resistors R703 connected in parallel with each other, and the other ends of the capacitors C700, capacitors C701 and resistors R703 connected in parallel with each other are connected to the source of the Nmos tube Q700.

[0033] In a preferred embodiment, the first switch module 2 includes: an Nmos tube Q700 whose gate is connected to the voltage divider module 1, a resistor unit connected to the drain of the Nmos tube Q700 via a resistor R710 and connected in parallel to the discharge module 3 and the high-voltage capacitor, and a voltage regulator D700 whose positive electrode is connected to the source of the Nmos tube Q700 and whose negative electrode is connected to the drain of the Nmos tube Q700 via the resistor R710, wherein the resistor unit includes a plurality of resistors connected in series, including a resistor R705, a resistor R706 and a resistor R707 connected in series in this embodiment, the resistor R705 is connected to the discharge module 3 and the high-voltage capacitor C1, the resistor R707 is connected to the drain of the Nmos tube Q700 via the resistor R710, and is connected to the negative electrode of the voltage regulator D700.

[0034] The discharge module 3 includes: an Nmos tube Q701 whose gate is connected to the first switch module 2 and whose source is connected to the high-voltage capacitor, and a discharge load unit connected to the drain of the Nmos tube Q701, wherein the discharge load unit includes a resistor R708 and a resistor R709 connected in series. Specifically, the gate of the Nmos tube Q701 is connected to the drain of the Nmos tube Q700 through the resistor R710, and is connected to the cathode of the voltage-stabilizing diode D700 and the high-voltage capacitor C1, the source of the Nmos tube Q701 is connected to the anode of the voltage-stabilizing diode D700, and the drain of the Nmos tube Q701 is connected to the high-voltage capacitor C1 after being connected in series with the resistor R708 and the resistor R709. Among them, the voltage-stabilizing diode D700 has a voltage stabilizing effect on the high-voltage capacitor C1 after discharge, so that the design can control the voltage value of the capacitor after discharge.

[0035] The working principle of the utility model is: when the power is turned on, the resistor R700, the resistor R701 and the resistor R703 divide the voltage so that the Nmos tube Q700 is turned on, thereby lowering the Vgs voltage of the Nmos tube Q701, the Nmos tube Q701 is cut off, and the loads R708 and R709 do not consume energy; when the power is turned off, the Nmos tube Q700 quickly changes to a low level, the Nmos tube Q701 is turned on, the high-voltage capacitor C1 and the loads R708 and R709 form a discharge loop to discharge the high-voltage capacitor, and the voltage regulator D700 controls the discharge amount of the high-voltage capacitor C1.

[0036] The utility model has a simple circuit and can solve the problem of residual voltage of the high-voltage capacitor without introducing an additional stable voltage source, has low cost, and the voltage value of the high-voltage capacitor after discharge is controllable.

[0037] The above shows and describes the basic principle and main features of the utility model and the advantages of the utility model. Those skilled in the art should understand that the utility model is not limited by the above embodiments. The above embodiments and descriptions are only for explaining the principle of the utility model. Without departing from the spirit and scope of the utility model, the utility model may have various changes and improvements, which fall within the scope of the utility model to be protected. The scope of protection claimed by the utility model is defined by the attached claims and their equivalents.

Claims

1. A high voltage circuit discharge system based on AC monitoring, characterized in that: include: Voltage divider module, connected to the power supply, divides the voltage when the power is turned on; A first switch module is connected to the voltage dividing module. When the power is turned on, the first switch is turned on to form a power-on loop with the high-voltage capacitor. When the power is turned off, the first switch is turned off. The discharge module is connected to the first switch module and the high-voltage capacitor. The second switch forms a discharge loop with the high-voltage capacitor in response to the cut-off signal transmitted by the first switch, and the load discharges the high-voltage capacitor.

2. The high voltage circuit discharge system based on AC monitoring according to claim 1, characterized in that: The first switch is an Nmos transistor Q700, the second switch is an Nmos transistor Q701, and the gate of the Nmos transistor Q701 is connected to the drain of the Nmos transistor Q700 via a resistor R710.

3. The high voltage circuit discharge system based on AC monitoring according to claim 1 or 2, characterized in that: The cut-off signal is a voltage signal, and when the first switch is turned off, the second switch is turned on.

4. The high voltage circuit discharge system based on AC monitoring according to claim 1, characterized in that: The first switch module includes: an Nmos tube Q700 whose gate is connected to the voltage divider module, a resistor unit connected to the drain of the Nmos tube Q700 via a resistor R710 and connected in parallel to the discharge module and the high-voltage capacitor, and a voltage regulator tube D700 whose positive electrode is connected to the source of the Nmos tube Q700 and whose negative electrode is connected to the drain of the Nmos tube Q700 via the resistor R710.

5. The high voltage circuit discharge system based on AC monitoring as claimed in claim 4, characterized in that: The resistance unit includes a plurality of resistors connected in series.

6. The high voltage circuit discharge system based on AC monitoring according to claim 1, 2, 4 or 5, characterized in that: The discharge module includes: an NMOS transistor Q701 whose gate is connected to the first switch module and whose source is connected to the high-voltage capacitor, and a discharge load unit connected to the drain of the NMOS transistor Q701.

7. The high voltage circuit discharge system based on AC monitoring as claimed in claim 6, characterized in that: The discharge load unit includes a resistor R708 and a resistor R709 connected in series.

8. The high voltage circuit discharge system based on AC monitoring according to claim 1, characterized in that: The voltage dividing module includes a diode D19 and a diode D18 connected in series and in parallel with the power supply, and a plurality of voltage dividing resistors connected in series with the diode D19 and the diode D18, and a plurality of the voltage dividing resistors are connected in series.

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