Surge current limiting circuit of solid state power controller

Abstract

The utility model discloses a surge current limiting circuit of a solid-state power controller, which comprises an input power supply end including Vi < n + > and Vi < n->; a main driving module, wherein the main driving module is provided with a SENSE pin, a GATE pin and an OUT pin; a drain electrode of the first MOSFET is connected to a load, a source electrode of the first MOSFET is connected to a current detection resistor, and a grid electrode of the first MOSFET is connected to a GATE pin of the main driving module; the current detection resistor is connected between the source electrode of the first MOSFET and Vi < n + >; the drain electrode of the pre-charging MOSFET is connected to a load, the source electrode of the pre-charging MOSFET is connected to the drain electrode of the first MOSFET, and the grid electrode of the pre-charging MOSFET is connected to the main driving module through a pre-charging driving circuit; the load is connected to an OUT pin of the main driving module, and the load is a capacitive load; and the capacitor is connected between the load and the Vi < n->. According to the solid-state power controller, the capacitor of the capacitive load is rapidly charged when the solid-state power controller is switched on, and no surge current is generated.

Description

TECHNICAL FIELD

[0001] The utility model relates to a surge current limiting circuit of solid state power controller belongs to the technical field of surge current limiting. BACKGROUND

[0002] With the development of intelligent direction, the traditional power supply and distribution control mode based on relay can not meet the requirements of power supply and distribution system configuration management, fault detection and diagnosis and reliability, and adopting solid state power control technology becomes the development trend.

[0003] The main function of solid state power control is to control the opening and closing of power MOS tube through the internal control circuit, realizing the opening and closing control of power supply to load of distribution system. Figure 1 When the solid state power controller works with capacitive load, if the main circuit is directly connected, according to the formula I=C*du / dt, when the voltage suddenly rises, the surge current will be generated in the main circuit, the voltage change rate and the connected capacitive load determine the surge current value through the power MOSFET, the greater the voltage change rate and the load capacity, the greater the surge current. Utility model content

[0004] The utility model discloses a surge current limiting circuit of solid state power controller, and the solid state power controller charges the capacitive load capacitor quickly when conducting and does not produce any surge current.

[0005] In order to solve the above technical problem, the technical scheme adopted by the utility model is:

[0006] The utility model discloses a surge current limiting circuit of solid state power controller, and the solid state power controller charges the capacitive load capacitor quickly when conducting and does not produce any surge current.

[0007] The input power supply end includes Vi n+ and Vi n-.

[0008] The main drive module has the SENSE pin, the GATE pin and the OUT pin.

[0009] The first MOSFET is connected to the load at the drain, connected to the current detection resistance at the source, and connected to the GATE pin of the main drive module at the gate.

[0010] a current detection resistor connected between the source of the first MOSFET and Vin+;

[0011] a pre-charge MOSFET with its drain connected to the load, its source connected to the drain of the first MOSFET, and its gate connected to the main drive module through a pre-charge drive circuit;

[0012] a load connected to the OUT pin of the main drive module, the load being a capacitive load;

[0013] a capacitor connected between the load and Vin-.

[0014] Further, the main drive module is configured to control the turn-on and turn-off of the first MOSFET and the pre-charge MOSFET, so that the current flows from Vin+ to the load through the first MOSFET or the pre-charge MOSFET.

[0015] Further, the main drive module acquires the voltage signal across the current detection resistor through the SENSE pin to monitor the current.

[0016] Further, the pre-charge drive circuit is configured to control the turn-on of the pre-charge MOSFET before the first MOSFET is fully turned on, so as to pre-charge the load.

[0017] The utility model has the advantages of:

[0018] The utility model combines the pre-charge MOSFET circuit and the constant current mode charging circuit, uses the pre-charge MOSFET circuit to charge the capacitive load capacitor quickly at the beginning of charging, and when the input and output voltage difference is small, the constant current mode charging circuit starts to work, and constant current charging is adopted, so no MOS tube over-power problem exists. The utility model enables the solid state power controller to charge the capacitive load capacitor quickly when turned on, and no surge current is generated. BRIEF DESCRIPTION OF DRAWINGS

[0019] The utility model will be explained further in detail in combination with the drawings and specific embodiments.

[0020] Figure 1 The figure is a schematic diagram of the solid state power controller with a capacitive load.

[0021] Figure 2 The figure is a schematic diagram of an embodiment of the utility model.

[0022] Figure 3 The figure is a schematic diagram of the pre-charge MOSFET circuit of an embodiment of the utility model.

[0023] Figure 4The charging curve diagram of the load voltage capacitor when the pre-charging MOSFET is turned on and the capacitive load is pure.

[0024] Figure 5 The current waveform diagram of the load side of the utility model one embodiment.

[0025] Figure 6 The constant current mode charging circuit schematic diagram of the utility model one embodiment. DETAILED DESCRIPTION

[0026] The technical solutions in the embodiments of the utility model will be clearly and completely described below with reference to the drawings in the embodiments of the utility model. Obviously, the described embodiments are only part of the embodiments of the utility model, rather than all the embodiments. The components of the embodiments of the utility model described and shown in the drawings can be arranged and designed in various different configurations. Therefore, the following detailed description of the embodiments of the utility model provided in the drawings is not intended to limit the scope of the claimed utility model, but only represents selected embodiments of the utility model. Based on the embodiments of the utility model, all other embodiments obtained by those skilled in the art without creative labor are within the scope of protection of the utility model.

[0027] As shown in the figure, the utility model discloses a kind of surge current limiting circuit of solid-state power controller, comprising:

[0028] Input power supply end, including Vi n+ and Vi n-;

[0029] Main drive module, the main drive module has SENSE pin 1, GATE pin 2 and OUT pin 3;

[0030] First MOSFET Q1, drain is connected to load, source is connected to current detection resistance Rsns, gate is connected to the GATE pin of the main drive module;

[0031] Current detection resistance Rsns is connected between the source of the first MOSFET Q1 and Vi n+;

[0032] Pre-charging MOSFET Q2, drain is connected to load, source is connected to the drain of the first MOSFET, gate is connected to the main drive module by pre-charging drive circuit;The main road drive in the figure is main drive module.

[0033] Load, connected to the OUT pin of the main drive module, the load is capacitive load, load is connected with Vi n-.

[0034] The utility model actually is the fusion pre-charging MOSFET circuit and constant current mode charging circuit.

[0035] Pre-charge MOSFET circuit, such as Figure 2 As shown, for turning on the pre-charge of the capacitive load, the current is not greater than U / R, the current is limited, and the inrush current problem can be avoided.

[0036] Figure 4 When the load is capacitive, the load voltage Vc(t) = Vin(1-e -t / RC ), in the figure, τ = RC, t = 2.3 when charged to 90%, τ = 2.3RC.

[0037] In solid-state power control, the pre-charge drive circuit precedes the main drive circuit, and the interval time is short. Once the load starts working after the load starting process is completed, if the load current is large, the power resistor will be damaged due to over-power. Assuming that the main MOSFET is turned on when the capacitor is charged to 90%, due to the voltage difference between the input end and the capacitor is 10% Vin, there will also be an inrush current, such as Figure 5 However, compared with not pre-charging, the inrush current is greatly reduced, and the MOSFET will not be damaged.

[0038] As shown in Figure 5 , the first inrush current is generated when the main MOSFET is turned on, and the second inrush current is generated when the load starts working.

[0039] As shown in Figure 6 , when the MOSFET Q1 current reaches the current limiting value, it is limited, so there will be no inrush current. When the MOSFET Q1 is limited, its power consumption is ICL*(Vin-Vout), and when the input and output voltage difference is large, its power consumption is also large. In order to not exceed the SOA, power limiting is required, that is, the charging current value is reduced. The reduction of the charging current means that the charging voltage rises slowly. This measure is not suitable for loads with large capacitance.

[0040] The utility model discloses a pre-charge MOSFET circuit is used when charging starts to make capacitive load capacitor fast charging, when the input and output voltage difference is small, constant current mode charging circuit starts working, adopts constant current charging, and therefore there will be no MOSFET over-power problem. The utility model makes solid-state power controller when turning on to capacitive load capacitor fast charging, and no inrush current is generated.

[0041] In an embodiment of the utility model, the main drive module is used for controlling the turn-on and turn-off of the first MOSFET and the pre-charge MOSFET, so that the current flows from Vin+ to the load through the first MOSFET or the pre-charge MOSFE.

[0042] In an embodiment of the utility model, the main drive module acquires the voltage signal between the current detection resistance through the SENSE pin 1 to monitor the current.

[0043] In an embodiment of the utility model, still include pre -fill drive circuit, pre -fill drive circuit here is the pre -fill drive of figure, pre -fill drive circuit is used in control pre -fill MOSFET conduction before first MOSFET complete conduction, to the load pre -charge.

[0044] The load includes a capacitor C and a resistor RL.

[0045] The above only is the preferred implementation manner of the utility model and is not used for limiting the utility model, for the person skilled in the art, the utility model can have various changes and changes. Any modification, equivalent replacement, improvement etc. that is made within the spirit and principle of the utility model should be included in the protection scope of the utility model.

Claims

1. A surge current limiting circuit for a solid state power controller, characterized by, Comprising: input power terminals, including Vin+ and Vin-; a main drive module, having a SENSE pin, a GATE pin and an OUT pin; a first MOSFET, having its drain connected to a load, its source connected to a current detection resistor, and its gate connected to the GATE pin of the main drive module; a current detection resistor, connected between the source of the first MOSFET and Vin+; a pre-charge MOSFET, having its drain connected to the load, its source connected to the drain of the first MOSFET, and its gate connected to the main drive module through a pre-charge drive circuit; a load, connected to the OUT pin of the main drive module, the load being a capacitive load.

2. The inrush current limiting circuit of a solid state power controller of claim 1, wherein, The main drive module is used to control the conduction and cut-off of the first MOSFET and the pre-charge MOSFET.

3. The inrush current limiting circuit of a solid state power controller of claim 1, wherein, The main drive module acquires a voltage signal across the current detection resistor through the SENSE pin.

4. The inrush current limiting circuit of a solid state power controller of claim 1, wherein, A pre-charge drive circuit is further included, which is used to control the conduction of the pre-charge MOSFET before the first MOSFET is fully on, and pre-charge the load.

5. The inrush current limiting circuit of a solid state power controller of claim 1, wherein, The load includes a capacitor and a resistor.

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