A load pre-charging circuit applied to an intelligent power distribution box and a control method thereof

Abstract

The application provides a load pre-charging circuit applied to an intelligent power distribution box and a control method thereof. The load pre-charging circuit comprises: a general power supply circuit and a pre-charging circuit. The general power supply circuit comprises: a power supply, an eFuse circuit, a power-consuming device and a controller, and the eFuse circuit is connected between the power supply and the power-consuming device. The first end of the pre-charging circuit is connected to the power supply, the second end is connected between the eFuse circuit and the power-consuming device, and the pre-charging circuit comprises: a switching circuit and a pre-charging capacitor. The switching input end of the switching circuit is connected to the first end, the switching output end is connected to the second end, and the ground end is grounded, so as to realize the switching of the pre-charging circuit between the pre-charging state and the freewheeling state. The pre-charging capacitor is connected to the switching input end and the ground. The controller is electrically connected to the eFuse circuit and the switching circuit, respectively. The application solves the technical problems of shortened device life, false protection and insufficient battery impact resistance caused by excessive impact current when the intelligent power distribution box is used to supply power to the core components or systems of new energy vehicles.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of pre-charging circuit, in particular to a load pre-charging circuit applied to an intelligent power distribution box and a control method thereof. BACKGROUND

[0002] With the rapid popularization of new energy vehicles and the improvement of intelligent degree, the number of electric control modules and loads carried by vehicles has increased significantly, such as battery management module (BMS), vehicle control module (VCU), auxiliary driving system (ADAS), laser radar, etc. These loads not only have high power demand (the power of low-voltage electrical appliances of new energy vehicles is more than 3 times that of traditional fuel vehicles), but also have significantly increased impact current. For example, the impact current of electric power steering system (EPS) can reach hundreds of amperes, which poses a serious challenge to traditional power distribution boxes.

[0003] The traditional power distribution box adopts a fast-fuse fuse design, which is not sensitive to single impact current, but a large impact current can significantly shorten its service life (the number of pulses under normal impact is only within 100,000 times), and cannot meet the functional safety requirements of ASIL B and above. Therefore, it is necessary to use an intelligent power distribution box based on an intelligent power chip to supply power, so as to solve the problem of shortened service life caused by impact current, but excessive impact current can cause false protection of the intelligent chip.

[0004] However, at least one of the following problems exists in the related art: when the intelligent power distribution box is used to supply power to the core components or systems of new energy vehicles, there are problems of shortened device life, false protection, insufficient battery impact resistance, and excessive cost caused by excessive impact current. SUMMARY

[0005] The present application solves the technical problems of shortened device life, false protection, and insufficient battery impact resistance caused by excessive impact current when the intelligent power distribution box is used to supply power to the core components or systems of new energy vehicles.

[0006] To solve the above problems, the application provides a load pre-charging circuit applied to an intelligent power distribution box, which comprises a general power supply circuit, a pre-charging circuit and a controller.

[0007] Compared with the prior art, the technical effects achieved by the technical scheme are as follows: the pre-charging capacitor serves as an energy storage capacitor and can quickly charge the load when pre-charging is needed, thereby providing the electric device with instantaneous large-current pre-charging capacity; the switching circuit is used for pre-charging control, the switching circuit can control when pre-charging is performed and control the pre-charging time by adjusting the pre-charging current; one eFuse circuit and one electric device constitute a load circuit, the switching output end and the second end are designed along the original load freewheeling circuit, and the automatic isolation of each load circuit pre-charging can be automatically realized, that is, the pre-charging function is realized when power is turned on, the pre-charging is completed, and the freewheeling function can be automatically restored, and the freewheeling is used when the load is turned off; the pre-charging speed of the application is fast, the reliability is high, the scheme cost is low, the load freewheeling requirement is met, the pre-charging isolation can be realized, the normal working load circuit is not affected, the large-impact load circuit cannot be powered on due to the excessive impact current, a special pre-charging circuit is used, the channel driving capacity does not need to be improved, and the overall low-cost design is realized.

[0008] In an example of the application, the pre-charging circuit further comprises a current limiting circuit connected in series to the pre-charging circuit, and the current limiting circuit is provided with a current limiting input end and a current limiting output end, the current limiting input end is connected to the first end, and the current limiting output end is connected to the switching input end; wherein the controller is electrically connected to the current limiting circuit.

[0009] Compared with the prior art, the technical effects achieved by the technical scheme are as follows: the current limiting circuit can limit the pre-charging current, the load pre-charging circuit adopts a current limiting design, the current limiting value is adjustable, the pre-charging maximum voltage is lower than the normal working voltage, the pre-charging speed is fast, the effect is good, the scheme is simple, the cost is low, the topology mode is diversified, and the pre-charging circuit can be used for different load circuits; the current limiting circuit is connected to the pre-charging capacitor, and the load can be quickly charged when pre-charging is needed, thereby shortening the pre-charging time; the pre-charging circuit uses a current limiting circuit + pre-charging capacitor + switching circuit mode, simultaneously reuses the original load freewheeling circuit in the original circuit design, uses a current limiting mode to pre-charge the load circuit with a large impact current, has no influence on the normal working circuit, has a fast response speed when the pre-charging function is switched, has a good practical application effect, the circuit is simple, the pre-charging function can cover all circuits, and the pre-charging circuit can be used for new energy vehicles, automatic driving vehicles and other vehicles with a large load power impact.

[0010] In one example of the application, the number of eFuse circuits and electrical equipment is multiple, and a plurality of second ends are provided correspondingly; a freewheeling diode is arranged between each of the plurality of second ends and the switching output end, the anode of the plurality of freewheeling diodes is connected to the switching output end, and the cathode is connected to the second end.

[0011] Compared with the prior art, the technical effects achieved by the technical scheme are as follows: the cathode of the freewheeling diode is connected in parallel with the output of each eFuse circuit, multiple channels are pre-charged independently through the freewheeling diode, and the normal working load is not affected during pre-charging; the pre-charging circuit of the application can simultaneously support multiple load circuits, without the need to improve the driving capability of the eFuse circuit, without the need to design a separate pre-charging circuit for each load circuit, and the channel driving capability only needs to be able to drive the rated working current of the load, without the need to improve the impact resistance, thereby greatly reducing the cost of the eFuse circuit, and realizing the overall low-cost design.

[0012] In one example of the application, the switching circuit comprises: a control unit connected to a power supply and a controller; and a switching device connected to the current limiting output end, the second end and the ground.

[0013] Compared with the prior art, the technical effects achieved by the technical scheme are as follows: the control unit is connected to the controller, and is used to control the opening and closing of the switching device, thereby controlling the on-off of the switching circuit.

[0014] In one example of the application, the switching device is a relay, the relay is provided with a normally open contact, a normally closed contact and a switching contact, the normally open contact is connected to the pre-charging capacitor, the normally closed contact is grounded, and the switching contact is connected to the second end through the freewheeling diode; in the pre-charging state, the normally open contact is closed, the normally closed contact is opened, and the pre-charging current flows to the electrical equipment through the switching contact; in the freewheeling state, the normally open contact is opened, the normally closed contact is closed, and the second end is grounded through the normally closed contact.

[0015] Compared with the prior art, the technical effects reached by adopting the technical scheme are: the control can adopt a relay, for a channel with a small number of starting times, such as a normal power channel, a relay scheme can be adopted, the scheme is simple, and the cost is low; in a non-pre-charging state, the normally closed contact of the relay connects the original load freewheeling circuit to the ground, to realize a load freewheeling function; if the controller controls the normally open contact of the relay to connect the pre-charging loop, then the current limiting circuit passes through the normally open contact of the relay, and then passes through the freewheeling diode to pre-charge the load with a large current impact; after pre-charging is completed, the controller controls the current limiting circuit to be turned off, and the relay is also turned off.

[0016] In an example of the application, the switching device is a semiconductor device, comprising: a second field effect tube and a third field effect tube; the second field effect tube is provided with a second gate, a second source and a second drain, and the second source is connected to a current limiting output end, and the second drain is connected to the second end through a freewheeling diode; the third field effect tube is provided with a third gate, a third source and a third drain, and the third drain is connected to the second drain, and the third source is grounded; the control unit comprises: a first triode, the first triode is provided with a first base, a first collector and a first emitter, and the first base is connected to a controller, the first collector is connected to the second gate, the third gate and a power supply, and the first emitter is grounded; wherein, in a pre-charging state, the controller outputs a high level to drive the first triode and the second field effect tube to be turned on, and the third field effect tube is turned off, and a pre-charging current flows to a power utilization device through the second field effect tube; in a freewheeling state, the controller outputs a low level to make the first triode and the second field effect tube be turned off, and the third field effect tube is turned on, and the second end is grounded through the third field effect tube.

[0017] Compared with the prior art, the technical effects reached by adopting the technical scheme are: in the freewheeling state, the controller outputs a low level, the first triode is turned off, the gate of the second field effect tube is pulled high (turned off), the gate of the third field effect tube is pulled high (turned on), and the freewheeling diode is grounded through the third field effect tube; in the pre-charging state, the controller outputs a high level, the first triode is turned on, the gate of the second field effect tube is pulled low (turned on), the gate of the third field effect tube is pulled low (turned off), a pre-charging current flows to a load through the second field effect tube, and after pre-charging is completed, the second field effect tube is turned off and the third field effect tube is turned on, and freewheeling is restored; the second field effect tube and the third field effect tube form a switching circuit similar to a relay, in a default state (i.e. without a control signal), the freewheeling diode is automatically grounded, that is, the pre-charging loop function is a default freewheeling circuit, and when pre-charging control is effective, the pre-charging loop function is a pre-charging circuit.

[0018] In an example of the application, the switching circuit further comprises: a second resistor connected between the power supply and the first collector; a third resistor connected between the first collector and the second gate; and a fourth resistor connected between the first collector and the third gate.

[0019] Compared with the prior art, the technical effects achieved by adopting the technical scheme are as follows: one end of R2 is connected to the second gate of Q2, the third gate of Q3 and the first collector of Q1, and the other end of R2 is connected to the power supply, thereby providing pull-up for Q1, Q2 and Q3; R3 and R4 can ensure that the second field effect transistor and the third field effect transistor work normally.

[0020] In an example of the present application, the switching circuit further comprises: a first resistor, one end of the first resistor being connected to the first base, and the other end of the first resistor being grounded; and a fifth resistor, the fifth resistor being connected between the first base and the controller.

[0021] Compared with the prior art, the technical effects achieved by adopting the technical scheme are as follows: the first base is connected to the pull-down resistor R1, which is mainly used for preventing noise interference, providing a stable bias voltage, and ensuring that the first triode can be reliably cut off in the off state; R5 is connected in series between the first base and the controller, which is used for voltage division.

[0022] On the other hand, the embodiment of the present application also provides a control method applied to the intelligent power distribution box, the control method being applied to the load pre-charging circuit applied to the intelligent power distribution box as in the first embodiment, and the control method comprising: opening the pre-charging loop, controlling the pre-charging loop to be in a pre-charging state; opening the eFuse circuit as required, and detecting whether there is a faulty eFuse channel in the eFuse circuit; in the case that the pre-charging loop is pre-charged and it is detected that there is a faulty eFuse channel in the eFuse circuit, the faulty eFuse channel is opened again.

[0023] Compared with the prior art, the technical effects achieved by adopting the technical scheme are as follows: the control method of the load pre-charging circuit of the present application has two kinds, one of which has a whole strategy of pre-charging all loads first and then opening the loads; the other of which has a whole strategy of opening the loads first, and if a certain load cannot be opened due to excessive impact current, pre-charging the load alone.

[0024] In an example of the present application, before opening the pre-charging loop and controlling the pre-charging loop to be in a pre-charging state, the control method further comprises: after the initial power-on or wake-up of the intelligent power distribution box, controlling the pre-charging loop to be in a freewheeling state; controlling the pre-charging capacitor to charge until the pre-charging capacitor is charged to a certain voltage.

[0025] Compared with the prior art, the technical effects achieved by adopting the technical scheme are as follows: in the initial power-on state or wake-up, the eFuse circuit is in a closed state, at this time the pre-charging loop is in a freewheeling state by default, then the current limiting circuit is opened, and the pre-charging capacitor starts to charge; after a period of time, such as 30ms, the pre-charging capacitor is charged to a certain voltage.

[0026] After adopting the technical scheme of the present application, the following technical effects can be achieved:

[0027] (1) The pre-charging speed is fast, the reliability is high, the scheme cost is low, the load freewheeling requirement is met, pre-charging isolation can be realized, the normal working load circuit is not affected, and the large impact load circuit cannot be powered on due to excessive impact current;

[0028] (2) The pre-charging circuit of the application uses a current limiting circuit + pre-charging capacitor + switching circuit mode, simultaneously reuses the original load freewheeling circuit in the original circuit design, uses a current limiting mode to pre-charge the load circuit with a large impact current, has no effect on the normal working circuit, has a fast response speed when switching the pre-charging function, has good actual application effect, the circuit is simple, the pre-charging function can cover all circuits, and can be used for new energy vehicles, autonomous driving and other vehicles with large load current impact;

[0029] (3) The pre-charging circuit of the application can support multiple load circuits at the same time, without improving the driving capability of the eFuse circuit, without designing a separate pre-charging circuit for each load circuit, and the channel driving capability only needs to be able to drive the rated working current of the load, without improving the impact resistance, which can greatly reduce the cost of the eFuse circuit, and thus realize the overall low-cost design. BRIEF DESCRIPTION OF DRAWINGS

[0030] In order to more clearly illustrate the technical solutions of the embodiments of the application, the drawings to be used in the embodiment description will be briefly introduced. Obviously, the drawings in the following description are only some embodiments of the application, and other drawings can be obtained by those skilled in the art without creative labor.

[0031] Figure 1 FIG. 1 is a topology architecture diagram of a load pre-charging circuit applied to a smart power distribution box according to an embodiment of the application;

[0032] Figure 2 FIG. 2 is another topology architecture diagram of a load pre-charging circuit applied to a smart power distribution box according to an embodiment of the application;

[0033] Figure 3 FIG. 3 is a topology architecture diagram of a load pre-charging circuit applied to different power distribution properties according to an embodiment of the application;

[0034] Figure 4 FIG. 4 is a detailed flowchart of a control method applied to a load pre-charging circuit according to an embodiment of the application;

[0035] Figure 5 FIG. 5 is another detailed flowchart of a control method applied to a load pre-charging circuit according to an embodiment of the application.

[0036] Explanation of reference signs:

[0037] 10, intelligent power distribution box; 110, power supply; 120, eFuse circuit; 131, first power device; 132, second power device; 133, third power device; 134, fourth power device; 140, controller; 201, first end; 202, second end; 211, switching input end; 212, switching output end; 213, ground end; 220, current limiting circuit; 221, current limiting input end; 222, current limiting output end; 311, first control circuit; 312, second control circuit; 313, third control circuit; 314, fourth control circuit; 341, always-on part; 342, ACC part; 343, ON part; 344, switch part. DETAILED DESCRIPTION

[0038] In order to make the above objectives, characteristics and advantages of the present application more apparent, clear and easy to understand, the technical solutions in the embodiments of the present application are described clearly and completely. Obviously, the described embodiments are only part of the embodiments of the present application, not all. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor are within the scope of protection of the present application.

[0039] Embodiment one

[0040] Reference Figure 1 , which is a load pre-charging circuit applied to an intelligent power distribution box according to the first embodiment of the present application, in combination with Figures 2-3 , the load pre-charging circuit comprises: a normal power supply circuit and a pre-charging circuit. The normal power supply circuit comprises: a power supply 110, an eFuse circuit 120, a power device and a controller 140, and the eFuse circuit 120 is connected between the power supply 110 and the power device. The pre-charging circuit is provided with a first end 201 and a second end 202. The first end 201 is connected to the power supply 110, and the second end 202 is connected between the eFuse circuit 120 and the power device. The pre-charging circuit comprises: a switching circuit and a pre-charging capacitor. The switching circuit is provided with a switching input end 211, a switching output end 212 and a ground end 213, which is used to realize the switching of the pre-charging circuit between the pre-charging state and the freewheeling state. The switching input end 211 is connected to the first end 201, the switching output end 212 is connected to the second end 202, and the ground end 213 is grounded. One end of the pre-charging capacitor is connected to the switching input end 211, and the other end of the pre-charging capacitor is grounded. The controller 140 is electrically connected to the eFuse circuit 120 and the switching circuit respectively.

[0041] In one specific embodiment, the power consuming device in the application is specifically a capacitive load, C1 is a pre-charge capacitor, which is a large-capacity electrolytic capacitor, C1 acts as an energy storage capacitor, which can quickly charge the load when pre-charging is required, providing a large current pre-charge capability for capacitive loads, and the capacitor capacity can be adjusted according to specific needs, improving the flexibility of the solution and meeting various application scenarios; The normal power supply circuit includes a plurality of load circuits, which are connected in parallel between the plurality of load circuits, each load circuit includes an eFuse circuit 120 and a power consuming device; The switching output end 212 and the second end 202 along with the original load freewheeling circuit, simplifying the circuit structure and reducing the cost; The switching circuit can also be called a pre-charge control circuit, which is used for pre-charge control, and the switching circuit can control when to pre-charge and control the pre-charge time by adjusting the pre-charge current; When the load circuit cannot start due to a large current impact, the switching circuit opens the pre-charge circuit to pre-charge the load, the pre-charge circuit is in a pre-charge state, and after reaching the pre-charge voltage, the pre-charge circuit is cut off, and the load can be normally started. The original load freewheeling circuit can be normally used for load freewheeling.

[0042] The application is used for an intelligent power distribution box 10, supports pre-charging of various loads and loads of each channel of the intelligent power distribution box 10, and can realize pre-charge isolation of multiple loads. When pre-charging a large-impact-current load, it does not affect other normal working loads. It can be used in new energy vehicles and high-level autonomous driving vehicles that require high reliability power distribution, low-voltage power distribution fields with large impact current loads, and especially in the technical field of intelligent power distribution boxes 10.

[0043] U3 is a controller 140, which is electrically connected with the eFuse circuit 120 and the switching circuit, and the controller 140 can control the switching circuit to switch between the pre-charge state and the freewheeling state, so as to control the pre-charge circuit to switch between the pre-charge state and the freewheeling state. When the eFuse circuit 120 needs to be opened, the controller 140 controls it to be opened. If the eFuse circuit 120 cannot be opened due to a large impact current at this time, it will report the fault to the controller 140, and the controller 140 will open the pre-charge circuit after detection.

[0044] Preferably, the number of pre-charge capacitors can be reserved, for example, 3 capacitor positions are designed, 1 capacitor position is used in a conventional design, and the remaining 2 capacitor positions are reserved. If the impact current is large, the other 2 pre-charge capacitors can also be connected in parallel to improve the pre-charge speed. The number of pre-charge capacitors can be adjusted according to the needs. For example, for conventional applications, a 2000 µF electrolytic capacitor can meet the needs, and for loads with a large impact, 2 2000 µF electrolytic capacitors can be connected in parallel.

[0045] Further, the pre-charging circuit further comprises: a current limiting circuit 220 connected in series to the pre-charging circuit, and the current limiting circuit 220 is provided with a current limiting input end 221 and a current limiting output end 222, the current limiting input end 221 is connected to the first end 201, and the current limiting output end 222 is connected to the switching input end 211; wherein the controller 140 is electrically connected with the current limiting circuit 220.

[0046] Specifically, the current limiting circuit 220 can limit the pre-charging current, the load pre-charging circuit adopts a current limiting design, the current limiting value can be adjusted, the pre-charging maximum voltage is lower than the normal working voltage, the pre-charging speed is fast, the effect is good, the scheme is simple, the cost is low, and the topology mode is diversified, and can be used for different load circuits; the current limiting circuit 220 is connected to the pre-charging capacitor, and the load can be quickly charged when pre-charging is needed, thereby shortening the pre-charging time. Since the current limiting circuit 220 is directly connected to the power supply 110, the maximum output voltage of the current limiting circuit 220 is the voltage of the power supply 110. Since the maximum output current of the current limiting circuit 220 is limited, the impact of the large charging current of C1 on the system at the initial power-on of the system can be avoided. For example, if the current limiting value is set to 5A, the charging current of C1 is limited to 5A by the current limiting circuit 220. At the same time, the current limiting value of the current limiting circuit 220 can be adjusted to adjust the pre-charging time. In a commercial vehicle 24V system, for example, C1 is 2000µF, and a 5A current can charge C1 to 63% of the voltage of the power supply 110, that is, 15.1V, in 4.8ms.

[0047] The current limiting circuit 220+pre-charging capacitor+pre-charging control circuit+original load freewheeling circuit of the present application replaces a special pre-charging circuit, the current limiting circuit 220 can limit the charging current, the pre-charging control circuit can control the opening of the pre-charging circuit when the load circuit cannot start due to a large current impact, or can open the pre-charging circuit in advance to charge the load. The pre-charging speed of the present application is fast, the reliability is high, the original load freewheeling circuit is reused, the scheme is simple, the cost is low, and the load pre-charging isolation of multiple paths can be realized while meeting the load freewheeling requirement. The scheme has no effect on the normal working circuit during pre-charging, and can avoid the problem that the load circuit cannot be powered on due to a large impact current, thereby reducing the system cost.

[0048] At the same time, the scheme uses an intelligent power chip as a load driver, which avoids the problem of shortened service life of a fuse in a traditional power distribution box due to a large impact current, and improves the reliability and service life of the intelligent power distribution box 10.

[0049] Further, the number of eFuse circuits 120 and the number of electric devices are multiple, and a plurality of second ends 202 are correspondingly provided; a freewheeling diode is arranged between each of the plurality of second ends 202 and the switching output end 212, the anode of the plurality of freewheeling diodes is connected to the switching output end 212, and the cathode is connected to the second end 202.

[0050] Specifically, referring to Figures 1-2 In the embodiment, there are four groups of load circuits, wherein U4-U7 are eFuse circuits 120, and D1-D4 are freewheeling diodes. The cathodes of the freewheeling diodes are connected in parallel with the outputs of the eFuse circuits 120. The freewheeling diodes are used to realize multi-channel independent pre-charging, and do not affect normal working loads during pre-charging. The pre-charging circuit of the application can support multiple load circuits at the same time, and does not need to improve the driving capability of the eFuse circuit 120. It does not need to design a separate pre-charging circuit for each load circuit. The channel driving capability only needs to be able to drive the rated working current of the load. The anti-impact capability does not need to be improved. The cost of the eFuse circuit 120 can be greatly reduced, thereby realizing the overall low-cost design.

[0051] Further, the switching circuit includes a control unit and a switching device. The control unit is connected to the power supply 110 and the controller 140. The switching device is connected to the current-limiting output end 222, the second end 202, and the ground, respectively.

[0052] Specifically, the control unit is connected to the controller 140, and is used to control the opening and closing of the switching device, thereby controlling the on-off of the switching circuit.

[0053] Further, referring to Figure 1 The switching device is a relay. The relay is provided with a normally open contact, a normally closed contact, and a switching contact. The normally open contact is connected to the pre-charging capacitor. The normally closed contact is connected to the ground. The switching contact is connected to the second end 202 through a freewheeling diode. In the pre-charging state, the normally open contact is closed, and the normally closed contact is opened. The pre-charging current flows to the electrical equipment through the switching contact. In the freewheeling state, the normally open contact is opened, and the normally closed contact is closed. The second end 202 is connected to the ground through the normally closed contact.

[0054] Specifically, K1 is a relay. The pre-charging control adopts a relay. The input of the power supply 110 is limited by the current-limiting circuit 220. The controller 140 can control the current-limiting value of the current-limiting circuit 220 and the switching of the circuit. The output of the current-limiting circuit 220 is connected to the normally open contact of the relay K1. The normally closed contact of K1 is connected to the ground. The switching contact is connected to different load output ends through a freewheeling diode, and is connected in parallel with the output of the eFuse circuit 120, thereby pre-charging different loads. The control of the application can adopt a relay. For channels with fewer start times, such as normal power channels, a relay scheme can be used. The scheme is simple and low in cost.

[0055] In the non-pre-charging state, the normally closed contact of the relay connects the original load freewheeling circuit to the ground, thereby realizing the load freewheeling function. If the controller 140 controls the normally open contact of the relay to connect the pre-charging circuit, the current-limiting circuit 220 passes through the normally open contact of the relay, and then passes through the freewheeling diode to pre-charge the high-current impact load. After the pre-charging is completed, the controller 140 controls the current-limiting circuit 220 to be turned off, and the relay is also turned off.

[0056] According to this wiring mode, the freewheeling diode is grounded in the default state, the freewheeling function is defaulted when pre-charging is not performed, and the pre-charging function is realized after the relay is actuated; the control signal of the current limiting circuit 220 is connected to the controller 140, the controller 140 can control the switch of the current limiting circuit 220 and adjust the current limiting value through the control signal; the output of the pre-charging loop is controlled by the controller 140, at the same time, the feedback signal of the eFuse circuit 120 is also connected to the controller 140, the controller 140 can monitor the switch state of the eFuse circuit 120, when the eFuse circuit 120 fails to open due to the impact current, pre-charging is performed first, and then restart is performed again.

[0057] Of course, the eFuse circuit 120 can also be pre-charged before being opened; because the pre-charging of each eFuse circuit 120 is isolated by the freewheeling diode, in actual application, the pre-charging of each output can be isolated from each other and not affect each other, that is, the eFuse circuit 120 of one road can be opened after the road is fully charged, and the pre-charging loop continues to pre-charge other load loops.

[0058] For example, the conversion contact of K1 is connected in parallel with the output terminals of eFuse circuits 120 U4, U5, U6 and U7 through D1, D2, D3 and D4 respectively, one end of the relay wire package is connected to the power supply 110, and the other end is controlled by U3; the feedback and control signals of all eFuse circuits 120 are connected to U3, U3 can control the switch of eFuse circuit 120, and monitor the switch state and fault state of eFuse circuit 120 in real time. In the figure, U4, U5, U6 and U7 are connected to the first to fourth power devices 131-134 respectively, and after power-on, U3 controls U4, U5, U6 and U7 to open at the same time, for example, if U5 fails to open due to excessive impact current, eFuse circuit 120 will be protected, U3 will detect the fault; at this time, the output voltage of U4, U6 and U7 has reached the voltage of power supply 110, for example, for a commercial vehicle, the voltage is 24V, and the output voltage of the protected channel U5 is 0V, since the original freewheeling circuit is connected to the output terminals of each eFuse circuit 120 through a freewheeling diode, based on the topology architecture in the figure, it can be ensured that each output is isolated from each other; at the same time, since the maximum output voltage of the current limiting circuit 220 is the voltage of the power supply 110, for example, 24V, the output voltage is reduced by one tube voltage drop after the freewheeling diode. For example, U5 protection, if the pre-charge loop is opened after 1 RC period, the output voltage of the current limiting circuit 220 is 15.1V, and the output terminals connected by D1, D3 and D4 are 24V, so D1, D3 and D4 will not be turned on; since the output voltage of U5 is 0V, D2 will automatically turn on to pre-charge the second power device 132, which does not affect the normal work of the first, third and fourth power devices 131, 133 and 134. After the pre-charge of the second power device 132 is completed, U5 can be opened again, for example, if the capacitance of the second power device 132 is 47µF, the voltage can be pre-charged to 12.2V, and the impact current will be reduced to less than 50% of the original. For example, U5 is a 3A channel, and the normal impact resistance of the second power device 132 is 50A, usually the channel needs to be upgraded to 10A to meet the demand of large impact current, and the cost will be doubled. After adopting the pre-charge loop, if the pre-charge is 12.2V, the impact current can be reduced to about 20A, and the 3A eFuse circuit 120 can withstand this impact current; that is, after pre-charge, the channel driving capacity does not need to be improved, and the effect of upgrading the original 10A eFuse circuit 120 can be realized, thereby realizing the overall low-cost design.

[0059] Further, referring to Figure 2The switching device is a semiconductor device, including: a second field-effect transistor (FET), a third field-effect transistor (FET), and a first transistor. The second FET has a second gate, a second source, and a second drain. The second source is connected to the current-limiting output terminal 222, and the second drain is connected to the second terminal 202 via a freewheeling diode. The third FET has a third gate, a third source, and a third drain. The third drain is connected to the second drain, and the third source is grounded. The first transistor has a first base, a first collector, and a first emitter. The first base is connected to the controller 140, the first collector is connected to the second gate, the third gate, and the power supply 110, and the first emitter is grounded. In the pre-charge state, the controller 140 outputs a high level to drive the first transistor and the second FET to conduct, and the third FET to turn off. The pre-charge current flows through the second FET to the electrical device. In the freewheeling state, the controller 140 outputs a low level to turn off the first transistor and the second FET, and the third FET to conduct. The second terminal 202 is grounded via the third FET.

[0060] Specifically, with Figure 1 The difference lies in the precharge control circuit, which uses semiconductor devices for design, improving the switching speed and lifespan of the circuit. The output of the current limiting circuit 220 is first connected to C1. The precharge control of this invention can also be performed by the controller 140 controlling the semiconductor devices. For channels that need frequent start-up, such as the ON position channel, the circuit may need to perform precharge frequently and requires a fast response speed. In this case, a semiconductor solution can be used. The solution has no lifespan limit, and the precharge switching response speed is fast, which can meet the system requirements. Q2 is the second field-effect transistor; Q3 is the third field-effect transistor; Q1 is the first transistor; the second gate of Q2 and the third gate of Q3 are connected in parallel, that is, Q2 and Q3 are simultaneously controlled by a control signal, but Q2 is a P-MOSFET and Q3 is an N-MOSFET, and the control method is opposite.

[0061] Q2 and Q3 form a relay-like switching circuit. In the default state (i.e., without a control signal), the freewheeling diode is automatically grounded, meaning the precharge circuit functions as the default freewheeling circuit. However, when the precharge control is active, the precharge circuit functions as the precharge circuit.

[0062] In the non-precharge state, Q3 is turned on, grounding the original freewheeling circuit and realizing the load freewheeling function; if the controller 140 controls the opening of the precharge circuit, then Q2 is turned on, and the current limiting circuit 220 passes through Q2 and then through the freewheeling diode to precharge the load with large inrush current; after the precharge is completed, the controller 140 controls the turning off of the current limiting circuit 220 and Q2, and Q3 will be turned on to realize the load freewheeling function.

[0063] Compared with the relay scheme, the pre-charge control is performed by using semiconductor devices, the reaction speed is faster, and the service life is longer. For example, the pull-in time of the relay is usually about 10 ms, and the electrical life is about 200,000 times. The semiconductor device can be 100 µs, which is 100 times faster. The switching of the semiconductor device has almost no service life limit, does not need to be replaced, has high reliability, and has low after-sales maintenance cost. In addition, the switching has no jitter when the semiconductor device is used for control, and the control effect is better.

[0064] Further, the switching circuit further comprises a second resistor, a third resistor and a fourth resistor, the second resistor is connected between the power supply 110 and the first collector, the third resistor is connected between the first collector and the second gate, and the fourth resistor is connected between the first collector and the third gate.

[0065] Specifically, R2 is the second resistor, R3 is the third resistor, and R4 is the fourth resistor. One end of R2 is connected to the second gate of Q2, the third gate of Q3 and the first collector of Q1, and the other end of R2 is connected to the power supply 110 to provide pull-up for Q1, Q2 and Q3. R3 and R4 can ensure that the second field effect tube and the third field effect tube work normally.

[0066] Further, the switching circuit further comprises a first resistor and a fifth resistor, one end of the first resistor is connected to the first base, and the other end of the first resistor is grounded. The fifth resistor is connected between the first base and the controller 140.

[0067] Specifically, R1 is the first resistor, and R5 is the fifth resistor. The first base is connected to the pull-down resistor R1, which is mainly used to prevent noise interference, provide a stable bias voltage, and ensure that the first triode can be reliably cut off in the off state. R5 is connected in series between the first base and the controller 140 for voltage division.

[0068] When the system is initially powered on or hibernates, the pre-charge control signal is invalid, R1 pulls the control signal low, i.e. the base of Q1 is pulled to a low level state, Q1 is in the off state; R2 pulls the gates of Q2 and Q3 through R3 and R4, because Q2 is a P-MOSFET, Q2 is in the off state, the current limiting circuit 220 is turned off, and the pre-charge circuit is in the closed state; Q3 is a N-MOSFET, Q3 is in the automatic conduction state, the anodes of the freewheeling diodes D1, D2, D3 and D4 are grounded, and a freewheeling path is provided for the load. When pre-charging is required, the controller 140 outputs a high level, Q1 is turned on, R2 is pulled low, Q1 pulls the gates of Q2 and Q3 low, Q2 is turned on due to the low gate, Q3 is turned off, and the original freewheeling circuit is cut off. Q2 is turned on, the current limiting circuit 220 pre-charges the load through the freewheeling diodes D1, D2, D3 and D4; after pre-charging is completed, the controller 140 outputs a low level, Q1 is turned off, R2 pulls the gates of Q2 and Q3 high through R3 and R4; Q2 is turned off, Q3 is turned on, and the freewheeling diodes D1, D2, D3 and D4 continue to freewheel for the load.

[0069] In another embodiment of the present application, for the intelligent power distribution box 10, the topology architecture can also share the current limiting circuit 220 for the same type of power distribution demand for different power distribution properties and different load control needs. For example, one control circuit is used for the always-on part 341, pre-charging is performed for all always-on channels when the always-on part 341 is powered on, and then the ACC part 342 is switched, followed by the ON part 343, and finally the switch part 344. This switching strategy is based on the power distribution timing characteristics of the vehicle application, and meets the pre-charging needs of all load circuits while independently pre-charging through different control circuits, sharing the current limiting circuit 220, which not only meets the pre-charging needs of different power distribution properties of the load, but also reduces the system cost and improves the flexibility of the system solution.

[0070] Referring to Figure 3For the pre-charge topology architecture of the application for different power distribution properties, in vehicle application, because the whole vehicle usually has multiple power distribution properties, such as normal power, ACC power, IGN1 power, IGN2 power, etc., the timing of each power supply 110 power-on is different; in order to meet this application, this topology architecture can be used: in the figure, a current limiting circuit 220 can be used, and the control circuit can be designed according to the actual application requirements, for example in the figure, there are four control circuits, which are the first control circuit 311 to the fourth control circuit 314, the timing of each power supply 110 power-on is different, so a current limiting circuit 220 can be shared. Take the first control circuit 311 as an example, the function is to control the pre-charge of the normal power part 341, and the specific working principle is as before; for example in vehicle application, the normal power part 341 is powered on first, then the first control circuit 311 can be used to pre-charge the normal power part 341, after the normal power part 341 is powered on, the first control circuit 311 is turned off, and the second control circuit 312 starts to work to pre-charge the ACC part 342, and so on.

[0071] Generally speaking, the normal power part 341, the ACC part 342, the ON part 343, and the switch part 344 are used in the electrical appliances, the controller 140 and the large current load are more, so the impact current is large, and the load that needs to be pre-charged is more. In addition, these electrical appliances are powered on together, so the impact current will be larger, so pre-charging is usually required. After the whole vehicle is powered on, only some switch type loads need to be pre-charged, these loads usually have small power and small impact current, but there may be some loads that need to be pre-charged, then a separate control circuit can be used to pre-charge the load, sharing the original current limiting circuit 220.

[0072] At the same time, for new energy vehicles with more control modules and complex thermal management systems, because the control modules such as intelligent driving controllers and thermal management systems such as cooling fans have large impact current when powered on, and the battery capacity of new energy vehicles is small, too large impact current when powered on can easily cause DC / DC overcurrent protection; after using the pre-charge circuit, the impact current problem when powered on can be solved, effectively avoiding the DC / DC false protection problem caused by power-on impact, and meeting the requirements of various new energy vehicles on the safety and reliability of the power supply 110 of the intelligent power distribution box 10 to the whole vehicle.

[0073]

Embodiment Two

[0074] Referring to Figures 4-5 The embodiment also provides a control method applied to the load pre-charge circuit of the first embodiment, the control method comprising:

[0075] Turn on the pre-charge circuit, control the pre-charge circuit to be in a pre-charge state;

[0076] The eFuse circuit is opened according to the demand, and whether there is a fault eFuse channel in the eFuse circuit is detected;

[0077] In the case that the pre-charging circuit is pre-charged and it is detected that there is a fault eFuse channel in the eFuse circuit, the fault eFuse channel is controlled to open again.

[0078] In one specific embodiment, Figure 4 The control method of the load pre-charging circuit is as follows: first, all loads are pre-charged, and then the loads are opened: after the pre-charging capacitor is charged to a certain voltage, the pre-charging circuit is opened, the pre-charging circuit is in a pre-charging state, and the load is pre-charged; after a period of time, after the pre-charging capacitor is pre-charged, the eFuse circuit is opened, and it is detected whether the eFuse circuit cannot be opened due to excessive impact, if the controller confirms that the eFuse circuit fails to open (then the eFuse circuit is a fault eFuse channel), then after a period of time, the controller attempts to open again; if the controller confirms that all eFuse circuits have been opened, the pre-charging control is closed, and the pre-charging circuit returns to a freewheeling state.

[0079] In another specific embodiment, Figure 5 The control method of the load pre-charging circuit is as follows: first, all loads are pre-charged, and then the loads are opened: after the pre-charging capacitor is charged to a certain voltage, the eFuse circuit is opened, and it is detected whether the eFuse circuit cannot be opened due to excessive impact, if the controller confirms that the eFuse circuit fails to open (then the eFuse circuit is a fault eFuse channel), then after a period of time, the controller attempts to open again; if the controller confirms that all eFuse circuits have been opened, the pre-charging control is closed, and the pre-charging circuit returns to a freewheeling state.

[0080] The determination condition of the eFuse circuit being a fault eFuse channel can be that the eFuse circuit output voltage is 0V and the duration exceeds 1ms, or the eFuse circuit feeds back a fault signal to the controller.

[0081] Further, before the pre-charging circuit is opened and the pre-charging circuit is controlled to be in a pre-charging state, the control method further includes:

[0082] After the smart power distribution box is initially powered on or wakes up, the pre-charging circuit is controlled to be in a freewheeling state;

[0083] The pre-charging capacitor is controlled to be charged until the pre-charging capacitor is charged to a certain voltage.

[0084] Specifically, in the initial power-on state or wake-up, the eFuse circuit is in the closed state, at this time the pre-charge circuit is in the freewheeling state by default, then the current limiting circuit is opened, and the current limiting circuit starts to pre-charge the pre-charge capacitor; after a period of time, the controller needs to wait for a period of time, for example, 2 RC periods (for example, 30 ms), and then pre-charge the load by controlling the pre-charge circuit after the pre-charge capacitor is charged to a certain voltage (for example, the pre-charge capacitor voltage is charged to more than 80%).

[0085] Finally, it should be noted that: the above embodiments are only used to illustrate the technical solutions of the present application, and not to limit them; although the present application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that: it can still modify the technical solutions recorded in the foregoing embodiments, or make equivalent replacement for part of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present application.

Claims

1. A load pre-charging circuit applied to a smart distribution box, characterized in that, The load pre-charging circuit includes: A normal power supply circuit includes: a power supply (110), an eFuse circuit (120), an electrical device, and a controller (140), wherein the eFuse circuit (120) is connected between the power supply (110) and the electrical device; A pre-charge circuit is provided, the pre-charge circuit having a first end (201) and a second end (202), the first end (201) being connected to the power supply (110), and the second end (202) being connected between the eFuse circuit (120) and the electrical device, and the pre-charge circuit includes: The switching circuit is provided with a switching input terminal (211), a switching output terminal (212) and a ground terminal (213) to realize the switching of the precharge circuit between the precharge state and the freewheeling state. The switching input terminal (211) is connected to the first terminal (201), the switching output terminal (212) is connected to the second terminal (202), and the ground terminal (213) is grounded. A pre-charge capacitor, one end of which is connected to the switching input terminal (211), and the other end of which is grounded; The controller (140) is electrically connected to the eFuse circuit (120) and the switching circuit, respectively. The pre-charge circuit also includes: A current limiting circuit (220) is connected in series to the pre-charge circuit, and the current limiting circuit (220) is provided with a current limiting input terminal (221) and a current limiting output terminal (222). The current limiting input terminal (221) is connected to the first terminal (201), and the current limiting output terminal (222) is connected to the switching input terminal (211). The controller (140) and the current limiting circuit (220) are electrically connected.

2. The load pre-charging circuit according to claim 1, characterized in that, The number of the eFuse circuit (120) and the electrical device is multiple, and each device is provided with multiple second terminals (202). A freewheeling diode is provided between the plurality of second terminals (202) and the switching output terminal (212), with the anode of the plurality of freewheeling diodes connected to the switching output terminal (212) and the cathode connected to the second terminal (202).

3. The load pre-charging circuit according to claim 1, characterized in that, The switching circuit includes: A control unit, which is connected to the power supply (110) and the controller (140); The switching device is connected to the current-limiting output terminal (222), the second terminal (202), and ground, respectively.

4. The load pre-charging circuit according to claim 3, characterized in that, The switching device is a relay, which has a normally open contact, a normally closed contact and a switching contact. The normally open contact is connected to the pre-charge capacitor, the normally closed contact is grounded, and the switching contact is connected to the second terminal (202) through a freewheeling diode. In the pre-charge state, the normally open contact is closed and the normally closed contact is open, and the pre-charge current flows to the electrical equipment through the switching contact; in the freewheeling state, the normally open contact is open and the normally closed contact is closed, and the second terminal (202) is grounded through the normally closed contact.

5. The load pre-charging circuit according to claim 3, characterized in that, The switching device is a semiconductor device, including: a second field-effect transistor and a third field-effect transistor; The second field-effect transistor has a second gate, a second source, and a second drain, and the second source is connected to the current-limiting output terminal (222), and the second drain is connected to the second terminal (202) via a freewheeling diode; The third field-effect transistor has a third gate, a third source, and a third drain, and the third drain is connected to the second drain, while the third source is grounded; The control unit includes: a first transistor, the first transistor having a first base, a first collector and a first emitter, the first base being connected to the controller (140), the first collector being connected to the second gate, the third gate and the power supply (110), and the first emitter being grounded; In the pre-charge state, the controller (140) outputs a high level to drive the first transistor and the second field-effect transistor to conduct, and the third field-effect transistor to turn off, and the pre-charge current flows through the second field-effect transistor to the electrical device; in the freewheeling state, the controller (140) outputs a low level to turn off the first transistor and the second field-effect transistor, and the third field-effect transistor to conduct, and the second terminal (202) is grounded through the third field-effect transistor.

6. The load pre-charging circuit according to claim 5, characterized in that, The switching circuit further includes: A second resistor is connected between the power supply (110) and the first collector; A third resistor is connected between the first collector and the second gate; A fourth resistor is connected between the first collector and the third gate.

7. The load pre-charging circuit according to claim 6, characterized in that, The switching circuit further includes: A first resistor, one end of which is connected to the first base, and the other end of which is grounded; A fifth resistor is connected between the first base and the controller (140).

8. A control method applied to an intelligent power distribution box, characterized in that, The control method is applied to the load pre-charging circuit of a smart distribution box as described in any one of claims 1-7, and the control method includes: Open the pre-charge circuit and control the pre-charge circuit to be in the pre-charge state; The eFuse circuit is opened as needed, and the presence of a faulty eFuse channel is detected within the eFuse circuit. If the precharge circuit is precharged and the faulty eFuse channel is detected in the eFuse circuit, the faulty eFuse channel is controlled to open again.

9. The control method according to claim 8, characterized in that, Before opening the pre-charge circuit and controlling the pre-charge circuit to be in the pre-charge state, the control method further includes: After the smart power distribution box is initially powered on or woken up, the pre-charge circuit is controlled to be in the freewheeling state; The pre-charge capacitor is controlled to charge until it reaches a certain voltage.

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