CN115771429A - Pre-charging circuit, control method thereof, battery management system and electric automobile - Google Patents
Pre-charging circuit, control method thereof, battery management system and electric automobile Download PDFInfo
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- CN115771429A CN115771429A CN202211579870.XA CN202211579870A CN115771429A CN 115771429 A CN115771429 A CN 115771429A CN 202211579870 A CN202211579870 A CN 202211579870A CN 115771429 A CN115771429 A CN 115771429A
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Abstract
The invention discloses a pre-charging circuit and a control method thereof, a battery management system and an electric automobile, wherein the circuit comprises: a capacitor; the positive electrode of the power battery is connected with the first end of the capacitor; the first end of the pre-charging inductor is connected with the first end of the capacitor, and the second end of the pre-charging inductor is connected with the second end of the capacitor; the pre-charging switch is connected between the negative electrode of the power battery and the first end of the pre-charging inductor in series; and the input end of the switch control module is connected with the negative electrode of the power battery, the output end of the switch control module is connected with the pre-charging switch and used for acquiring a circuit signal in the pre-charging circuit, comparing the circuit signal with a reference signal to obtain a voltage value comparison result, and controlling the on-off of the pre-charging switch according to the voltage value comparison result and a clock signal. According to the embodiment provided by the invention, the pre-charging efficiency, the safety of the battery system and the energy conservation can be improved.
Description
Technical Field
The invention relates to the technical field of charging, in particular to a pre-charging circuit, a control method of the pre-charging circuit, a battery management system and an electric automobile.
Background
With the vigorous development of new energy electric vehicles, various manufacturers increasingly attach importance to the safety performance and the energy-saving performance of an electric vehicle battery system, and meanwhile, more and more measures are used for improving the system performance and the reliability of the electric vehicle battery system, and a battery charging technology is an important item. In a conventional battery system, a passive pre-charging scheme is generally adopted, that is, a pre-charging resistor is arranged in a charging circuit, and a bus capacitor is pre-charged through the current limiting function of the pre-charging resistor. However, when the scheme is adopted for pre-charging, the pre-charging resistor generates more heat, which affects the service life of the pre-charging resistor on one hand, and on the other hand, the pre-charging resistor may be thermally disabled to cause fire. In addition, heat dissipated by the pre-charging resistor can also damage surrounding components, and the safety performance of the battery system is influenced; and the power consumption of the battery system is also increased, and the energy-saving performance of the battery system is poor.
Disclosure of Invention
The present invention is directed to solving at least one of the problems of the prior art. Therefore, the invention provides a pre-charging circuit, a control method thereof, a battery management system and an electric vehicle, which can improve pre-charging efficiency, reduce heat productivity in a pre-charging process, reduce power consumption of a battery system and improve safety and energy conservation of the battery system.
In a first aspect, an embodiment of the present invention provides a precharge circuit, including: a capacitor; the positive electrode of the power battery is connected with the first end of the capacitor; a first end of the pre-charging inductor is connected with a first end of the capacitor, and a second end of the pre-charging inductor is connected with a second end of the capacitor; the pre-charging switch is connected between the negative electrode of the power battery and the first end of the pre-charging inductor in series; and the input end of the switch control module is connected with the negative electrode of the power battery, the output end of the switch control module is connected with the pre-charging switch and used for acquiring a circuit signal in the pre-charging circuit, comparing the circuit signal with a reference signal to obtain a voltage value comparison result, and controlling the on-off of the pre-charging switch according to the voltage value comparison result and a clock signal.
According to the precharge circuit provided by the first aspect of the present invention, at least the following advantages are provided: in the pre-charging circuit, after acquiring a circuit signal in the pre-charging circuit, a switch control module compares the circuit signal with a reference signal to obtain a voltage value comparison result, controls the on-off of the pre-charging switch according to the voltage value comparison result and a clock signal, and forms a first current loop which is released by a power battery to pre-charge a capacitor under the condition that the pre-charging switch is switched on; when the pre-charging switch is turned off, a second current loop is formed to pre-charge the capacitor by discharging energy from the pre-charging inductor. According to the scheme of the embodiment of the invention, the on-off of the pre-charging switch is controlled through the voltage value comparison result and the clock signal, the first current loop and the second current loop are switched through the pre-charging switch, and the first current loop and the second current loop are enabled to alternately pre-charge the capacitor until the voltage values at two ends of the capacitor are the same as the voltage values at two ends of the power battery; in addition, the use of a pre-charging resistor is eliminated, so that the heat productivity in the pre-charging process is reduced, the power consumption of the battery system is reduced, and the safety and the energy saving performance of the battery system are improved; the integration level of the pre-charging circuit is improved, and the arrangement of a battery management system is facilitated.
According to some embodiments of the invention, the switch control module comprises: the signal detection and amplification module is connected between the negative electrode of the power battery and the pre-charging switch in series and used for acquiring the circuit signal and amplifying the circuit signal to output an amplified signal; the non-inverting input end of the comparator is connected with the output end of the signal detection amplification module, the inverting input end of the comparator is connected with a reference signal source, and the comparator is used for receiving and comparing the amplified signal and the reference signal and outputting a voltage value comparison result; and the two logic input ends of the NOR logic module are respectively connected with the output end of the comparator and the output end of the clock generation module, and the output end of the NOR logic module is connected with the pre-charging switch and used for controlling the on-off of the pre-charging switch according to the voltage value comparison result and the clock signal.
According to some embodiments of the invention, the pre-charge circuit further comprises: and the battery pack main negative switch is connected between the negative electrode of the power battery and the second end of the capacitor.
According to some embodiments of the invention, the pre-charge circuit further comprises: a first freewheel protection module connected between a first terminal of the pre-charge inductance and a first terminal of the capacitor, the first freewheel protection module for freewheeling a first current flowing from the first terminal of the pre-charge inductance to the first terminal of the capacitor.
According to some embodiments of the invention, the pre-charge circuit further comprises: and the second follow current protection module is connected between a pre-charging switch and the first end of the pre-charging inductor and is used for follow current of a second current flowing from the first end of the pre-charging inductor to the pre-charging switch.
According to some embodiments of the invention, the signal detection and amplification module comprises a current detection resistor and a signal amplifier, the current detection resistor is connected in series between the negative pole of the power battery and the pre-charging switch, and the signal amplifier is connected in parallel with the current detection resistor.
In a second aspect, an embodiment of the present invention provides a method for controlling a precharge circuit, where the method is applied to the precharge circuit in the first aspect, and the method includes: acquiring a circuit signal in the pre-charging circuit; comparing the circuit signal with a reference signal to obtain a voltage value comparison result; controlling the on-off of a pre-charging switch according to a voltage value comparison result and a clock signal, wherein the pre-charging switch is controlled to be switched on under the condition that the voltage value of the circuit signal is smaller than the voltage threshold of the reference signal and the clock signal is at a low level according to the voltage value comparison result, and a first current loop for pre-charging a capacitor through energy release of a power battery is formed; and under the condition that the voltage value comparison result shows that the voltage value of the circuit signal is greater than the voltage threshold value of the reference signal, the pre-charging switch is controlled to be switched off, and a second current loop which can be discharged by a pre-charging inductor to pre-charge a capacitor is formed.
According to the control method of the pre-charging circuit provided by the second aspect of the invention, at least the following beneficial effects are achieved: under the condition that the voltage value of the circuit signal is smaller than the voltage threshold of the reference signal and the clock signal is at a low level as a result of the voltage value comparison, controlling the pre-charging switch to be conducted to form a first current loop for pre-charging the capacitor by releasing energy of the power battery; and under the condition that the voltage value comparison result shows that the voltage value of the circuit signal is greater than the voltage threshold of the reference signal, the pre-charging switch is controlled to be switched off, and a second current loop which can pre-charge the capacitor by releasing energy from the pre-charging inductor is formed. According to the scheme of the embodiment of the invention, the on-off of the pre-charging switch is controlled through the voltage value comparison result and the clock signal, the first current loop and the second current loop are switched through the pre-charging switch, and the first current loop and the second current loop are alternately pre-charged for the capacitor until the voltage value at the two ends of the capacitor is the same as the voltage value at the two ends of the power battery, namely: according to the scheme of the embodiment of the invention, the pre-charging efficiency can be improved while the pre-charging safety is ensured; in addition, by canceling the use of a pre-charging resistor, the heat productivity in the pre-charging process is reduced, the power consumption of the battery system is reduced, and the safety and the energy conservation of the battery system are improved; the integration level of the pre-charging circuit is improved, and the arrangement of a battery management system is facilitated.
According to some embodiments of the invention, the pre-charge circuit further comprises: a battery pack primary negative switch connected between the negative pole of the power cell and the second end of the capacitor, the method further comprising: and under the condition that the voltage values of the two ends of the capacitor are equal to the voltage value of the power battery, closing the main negative switch of the battery pack to finish the active pre-charging treatment.
In a third aspect, an embodiment of the present invention provides a battery management system, including: the pre-charge circuit as described in the first aspect.
In a fourth aspect, an embodiment of the present invention provides an electric vehicle, including: a battery management system according to the third aspect.
Additional aspects and advantages of the invention will be set forth in part in the description which follows and, in part, will be obvious from the description, or may be learned by practice of the invention.
Drawings
Additional aspects and advantages of the present invention will become apparent and readily appreciated from the following description of the embodiments, taken in conjunction with the accompanying drawings of which:
FIG. 1 is a schematic diagram of a pre-charge circuit according to an embodiment of the present invention;
FIG. 2 is a schematic diagram of a precharge circuit according to another embodiment of the present invention
FIG. 3 is a schematic diagram of a pre-charge circuit according to another embodiment of the present invention;
FIG. 4 is a truth table for a NOR logic block provided in accordance with one embodiment of the present invention;
FIG. 5 is a flowchart of a method for controlling a pre-charge circuit according to an embodiment of the present invention;
reference numerals: the power battery system comprises a power battery 100, a capacitor Cx, a precharge inductor L, a precharge switch 200, a switch control module 300, a signal detection amplification module 310, a current detection resistor 311, a signal amplifier 312, a comparator 320, a reference signal source 330, a NOR logic module 340, a clock generation module 350, a main positive switch K1 of a battery pack, a main negative switch K2 of the battery pack, a first follow current protection module 400, a first diode D1, a second short-circuit protection unit 410, a third short-circuit protection unit 420, a second follow current protection module 500, a second diode D2, a first short-circuit protection unit 600, a driving module 700 and an active disconnection protection module 800.
Detailed Description
Reference will now be made in detail to embodiments of the present invention, examples of which are illustrated in the accompanying drawings, wherein like or similar reference numerals refer to the same or similar elements or elements having the same or similar function throughout. The embodiments described below with reference to the accompanying drawings are illustrative only for the purpose of explaining the present invention, and are not to be construed as limiting the present invention.
In the description of the present invention, the meaning of a plurality of means is one or more, the meaning of a plurality of means is two or more, and larger, smaller, larger, etc. are understood as excluding the number, and larger, smaller, inner, etc. are understood as including the number. If there is a description of first and second for the purpose of distinguishing technical features only, this is not to be understood as indicating or implying a relative importance or implicitly indicating the number of technical features indicated or implicitly indicating the precedence of technical features indicated.
In the description of the present invention, unless otherwise explicitly limited, terms such as arrangement, installation, connection and the like should be understood in a broad sense, and those skilled in the art can reasonably determine the specific meanings of the above terms in the present invention in combination with the specific contents of the technical solutions.
The invention provides a pre-charging circuit and a control method thereof, a battery management system and an electric automobile, wherein the on-off of a pre-charging switch can be controlled through a voltage value comparison result and a clock signal, a first current loop and a second current loop are switched through the pre-charging switch, and the first current loop and the second current loop are enabled to alternately pre-charge a capacitor until the voltage values at two ends of the capacitor are the same as the voltage values at two ends of a power battery; in addition, the use of a pre-charging resistor is eliminated, so that the heat productivity in the pre-charging process is reduced, the power consumption of the battery system is reduced, and the safety and the energy saving performance of the battery system are improved; the integration level of the pre-charging circuit is improved, and the arrangement of a battery management system is facilitated.
The embodiments of the present invention will be further explained with reference to the drawings.
As shown in fig. 1, an embodiment of the present invention provides a precharge circuit, including: capacitor Cx, power battery 100, precharge inductor L, precharge switch 200, and switch control module 300. Wherein the positive electrode of the power battery 100 is connected with the first end of the capacitor Cx; the first end of the pre-charging inductor L is connected with the first end of the capacitor Cx, and the second end of the pre-charging inductor L is connected with the second end of the capacitor Cx; the pre-charging switch 200 is connected in series between the negative electrode of the power battery 100 and the first end of the pre-charging inductor L; the input end of the switch control module 300 is connected with the negative electrode of the power battery 100, the output end of the switch control module 300 is connected with the pre-charging switch 200, and the switch control module 300 is configured to obtain a circuit signal in the pre-charging circuit, compare the circuit signal with a reference signal to obtain a voltage value comparison result, and control the on-off of the pre-charging switch according to the voltage value comparison result and a clock signal.
In the pre-charging circuit shown in fig. 1, the switch control module 300 obtains a circuit signal in the pre-charging circuit, compares the circuit signal with a reference signal to obtain a voltage value comparison result, controls the on/off of the pre-charging switch 200 according to the voltage value comparison result and a clock signal, and forms a first current loop which is released by the power battery 100 to pre-charge the capacitor Cx when the pre-charging switch 200 is turned on; when the precharge switch 200 is turned off, a second current circuit is formed to precharge the capacitor Cx by discharging energy from the precharge inductance L. According to the scheme of the embodiment of the invention, the on-off of the pre-charging switch 200 is controlled through the voltage value comparison result and the clock signal, the first current loop and the second current loop are switched through the pre-charging switch 200, and the first current loop and the second current loop are alternately pre-charged for the capacitor Cx until the voltage value at the two ends of the capacitor Cx is the same as the voltage value at the two ends of the power battery 100; in addition, by canceling the use of a pre-charging resistor, the heat productivity in the pre-charging process is reduced, the power consumption of the battery system is reduced, and the safety and the energy conservation of the battery system are improved; the integration level of the pre-charging circuit is improved, and the arrangement of a battery management system is facilitated.
As shown in fig. 2, according to some embodiments of the invention, the switch control module 300 includes: the signal detection and amplification module 310, the comparator 320, the reference signal source 330, the nor logic module 340 and the clock generation module 350. The signal detection and amplification module 310 is connected in series between the negative electrode of the power battery 100 and the pre-charge switch 200, and is configured to acquire a circuit signal, amplify the circuit signal, and output an amplified signal; the non-inverting input end of the comparator 320 is connected to the output end of the signal detection amplifying module 310, and the inverting input end of the comparator 320 is connected to the reference signal source 330, and is configured to receive and compare the amplified signal with the reference signal, and output a voltage value comparison result; two logic input ends of the nor logic module 340 are respectively connected to the output end of the comparator 320 and the output end of the clock generation module 350, and an output end of the nor logic module 340 is connected to the precharge switch 200, and is configured to control on/off of the precharge switch 200 according to the voltage value comparison result and the clock signal.
In some embodiments, the pre-charge circuit further comprises: a battery pack main positive switch K1 and a battery pack main negative switch K2. The battery pack main positive switch K1 is connected between the positive electrode of the power battery 100 and the first end of the capacitor Cx, and the battery pack main negative switch K2 is connected between the negative electrode of the power battery 100 and the second end of the capacitor Cx.
According to the pre-charge circuit shown in fig. 2 provided by the embodiment of the present invention, when the main positive switch K1 of the battery pack is closed, first, the signal detection and amplification module 310 obtains a circuit signal in the pre-charge circuit, amplifies the circuit signal to output an amplified signal, and outputs the amplified signal to the non-inverting input terminal of the comparator 320. The inverting input terminal of the comparator 320 is connected to a reference signal source 330, wherein the reference signal source 330 is used for outputting a reference signal to the comparator 320, and the voltage value of the reference signal is the maximum voltage threshold allowed to pass through the pre-charge circuit. Then, the comparator 320 compares the voltage thresholds of the amplified signal and the reference signal after receiving the amplified signal and the reference signal, and outputs the voltage value comparison result to the nor logic module 340, specifically, the comparator 320 outputs a low level (logic value is 0) to the nor logic module 340 in a case where the voltage value of the amplified signal is smaller than the voltage threshold as the output voltage value comparison result, and the comparator 320 outputs a high level (logic value is 1) to the nor logic module 340 in a case where the voltage value of the amplified signal is greater than the voltage threshold as the output voltage value comparison result. Then, after the nor logic module 340 receives the level signal output by the comparator 320, that is, after receiving the voltage value comparison result, the nor logic module 340 controls the on/off of the precharge switch 200 according to the voltage value comparison result and the clock signal, specifically, when receiving the low level output by the comparator 320 (that is, the voltage value of the amplified signal is smaller than the voltage threshold value as the voltage value comparison result) and the clock signal is the low level, the nor logic module 340 outputs the high level (the logic value is 1), and the high level signal controls the precharge switch 200 to be closed and conducted, so as to form a first current loop that the power battery 100 can release the precharge of the capacitor Cx; when a high level is received from the comparator 320 (i.e., the voltage value of the amplified signal is greater than the voltage threshold as a result of the voltage value comparison), the low level signal controls the precharge switch 200 to turn off regardless of whether the clock signal outputs a high level or a low level or the nor logic block 340 outputs a low level (logic value is 0), so as to form a second current loop capable of precharging the capacitor Cx due to the precharge inductance L. According to the scheme of the embodiment of the invention, the on-off of the pre-charging switch 200 is controlled through the voltage value comparison result and the clock signal, the first current loop and the second current loop are switched through the pre-charging switch 200, and the first current loop and the second current loop are enabled to alternately pre-charge the capacitor Cx until the voltage value at the two ends of the capacitor Cx is the same as the voltage value at the two ends of the power battery 100. That is to say, through the scheme of the embodiment of the invention, the precharging efficiency can be improved while the precharging safety is ensured; in addition, by canceling the use of a pre-charging resistor, the heat productivity in the pre-charging process is reduced, the power consumption of the battery system is reduced, and the safety and the energy conservation of the battery system are improved; the integration level of the pre-charging circuit is improved, and the arrangement of a battery management system is facilitated.
Specifically, the battery pack main positive switch K1 is a battery pack main positive relay. The main positive switch K1 of the battery pack can be controlled by the battery management system, and the main positive switch K1 of the battery pack can be closed under the control of the battery management system to conduct a circuit between the positive electrode of the power battery 100 and the first end of the capacitor Cx.
It will be appreciated by those skilled in the art that the structural schematic diagrams of the pre-charge circuits shown in fig. 1 and 2 do not constitute a limitation on the embodiments of the present invention, and may include more or fewer components than those shown, or some components may be combined, or a different arrangement of components.
It should be noted that two logic input terminals of the nor logic module 340 are respectively connected to the output terminal of the comparator 320 and the output terminal of the clock generating module 350, and the output terminal of the nor logic module 340 is connected to the precharge switch 200. The output end of the comparator 320 outputs a logic value (value is 1 or 0) representing the comparison result of the voltage values, and the clock generation module 350 is configured to output a clock signal, where the clock signal periodically switches between a high level and a low level (i.e., switches between 1 and 0); after the logical operation of the nor logic module 340, the nor logic module 340 outputs a level signal with a logical value of 1 or 0 to control the on/off of the precharge switch 200.
Specifically, as shown in FIG. 4, FIG. 4 illustrates a truth table for a NOR logic block provided by one embodiment of the present invention; a represents a level value of the clock signal output from the clock generation block 350, a =1 represents that the clock generation block 350 outputs a high level, a =0 represents that the clock generation block 350 outputs a low level, B represents a logic value representing a voltage value comparison result output from the output terminal of the comparator 320, and Y represents a logic value output from the nor logic block 340. Y =1 if and only if a =0, b = 0; when B =1, y is always equal to 0, whether a =0 or a = 1. That is, the nor logic block 340 controls the precharge switch 200 to be turned on when the voltage value of the amplified signal is smaller than the voltage threshold and the clock signal outputs a low level, and the nor logic block 340 controls the precharge switch 200 to be turned off when the voltage value of the amplified signal is smaller than the voltage threshold and the clock signal outputs a high level. Under the condition that the voltage value of the amplified signal is smaller than the voltage threshold, the on-off of the pre-charge switch 200 is periodic due to the periodic clock signal, the average current of each switching period is the same, the inductive current ripple is the same, the capacitor voltage is increased linearly, and the system stability is improved. In addition, under the condition that the voltage value of the amplified signal is greater than the voltage threshold, no matter the clock signal outputs high level or low level, the nor logic module 340 controls the pre-charge switch 200 to be switched off, so as to ensure that a current loop in the active pre-charge circuit is smaller than a preset maximum pre-charge current, thereby reducing the heat productivity in the pre-charge process, reducing the power consumption of the battery system, and improving the safety and energy conservation of the battery system.
It should be noted that the clock generating module 350 fixedly outputs a clock signal with a certain frequency, and the frequency of the clock signal is between 10kHz and 60 kHz.
Referring to fig. 2 and 3, in particular, the precharge switch 200 employs a metal oxide semiconductor field effect transistor, i.e., a MOS transistor. The drain of the MOS transistor is connected to the first end of the precharge inductor L, the source of the MOS transistor is connected to the negative electrode of the power battery 100 through the signal detection and amplification module 310, and the gate of the MOS transistor is connected to the output end of the nor logic module 340 through the driving module 700. The pre-charge switch 200 is turned on or off under the control of the nor logic module 340, when the pre-charge switch 200 is turned on, a first current loop is formed, which is capable of releasing energy to pre-charge the capacitor Cx by the power battery 100, and current on the first current loop has a first flow direction, and the first flow direction sequentially flows from the positive pole of the power battery 100 to the capacitor Cx, the pre-charge inductor L, the pre-charge switch 200, the signal detection and amplification module 310 and the negative pole of the power battery 100; when the pre-charge switch 200 is turned off, a second current loop is formed to pre-charge the capacitor Cx by the energy released from the pre-charge inductor L, and the current in the second current loop has a second flow direction, and the second flow direction sequentially flows through the capacitor Cx and the second end of the pre-charge inductor L from the first end of the pre-charge inductor L. The first current loop and the second current loop are switched by switching on and off of the pre-charging switch 200, so that the first current loop and the second current loop alternately pre-charge the capacitor Cx until the voltage value at the two ends of the capacitor Cx is the same as the voltage value at the two ends of the power battery 100. It can be understood that the voltage value output across the power battery 100 is Vbat.
The first current circuit is a current circuit in which the capacitor Cx is precharged by the power battery 100 when the precharge switch 200 is turned on during the precharge process, and the precharge inductance L is also charged during the precharge process of the capacitor Cx.
It should be noted that the second current loop is a current loop formed by the inductance self-inductance effect when the pre-charge switch 200 is turned off during the pre-charge process, and is an energy release loop formed by releasing energy from the pre-charge inductance L. The inductance value of the pre-charging inductor L is reasonably determined, and when the inductance value of the pre-charging inductor L is too small, the inductor is easily saturated due to switching delay, so that devices are easily burnt out due to overcurrent; when the inductance of the pre-charge inductor L is too large, the size of the pre-charge inductor L is large, and the occupied space and the manufacturing cost of the pre-charge circuit are increased.
Referring to fig. 3, according to some embodiments of the present invention, the active pre-charge protection circuit further includes a first short-circuit protection unit 600 connected in series between the second terminal of the pre-charge inductor L and the second terminal of the capacitor Cx, and the first short-circuit protection unit 600 is used for timely disconnecting the line to protect the circuit and the components in case of a short circuit of the circuit.
Referring to fig. 2-3, according to some embodiments of the present invention, the pre-charge circuit further includes: and the battery pack main negative switch K2 is connected between the negative electrode of the power battery 100 and the second end of the capacitor Cx. Specifically, the battery pack main negative switch K2 is a battery pack main negative relay. The battery pack main negative switch K2 is controlled by the battery management system, and the battery pack main negative switch K2 can be closed under the control of the battery management system to conduct a circuit between the negative electrode of the power battery 100 and the second end of the capacitor Cx. Under the condition that the voltage value of the two ends of the capacitor Cx is equal to the voltage value of the power battery 100, the battery pack main negative switch K2 is closed under the control of the battery management system, so that the active pre-charging processing is completed, and a complete path for charging the power battery 100 is formed.
Referring to fig. 2-3, according to some embodiments of the present invention, the pre-charge circuit further includes: a first freewheel protection module 400 connected between the first terminal of the pre-charge inductance L and the first terminal of the capacitor Cx, the first freewheel protection module 400 for freewheeling a first current flowing from the first terminal of the pre-charge inductance L to the first terminal of the capacitor Cx. Specifically, the first freewheel protection module 400 includes a first diode D1, a second short-circuit protection unit 410, and a third short-circuit protection unit 420, an anode of the first diode D1 is connected to the first end of the pre-charge inductor L, and a cathode of the first diode D1 is connected to the first end of the capacitor Cx through the second short-circuit protection unit 410 and the third short-circuit protection unit 420 connected in series. The second short-circuit protection unit 410 and the third short-circuit protection unit 420 are both used for timely disconnecting a line to protect a circuit and components in the case of a short circuit of the circuit. The direction of the current flowing from the first terminal of the pre-charge inductor L to the first terminal of the capacitor Cx is the conducting direction of the first diode D1, and the first diode D1 is used for freewheeling the current of the second current loop. In addition, the precharge circuit further includes: the active disconnection protection module 800 is connected between the power battery 100 and the battery pack main positive switch K1, and the active disconnection protection module 800 is used for actively disconnecting the circuit when the current is too large, so that the power battery 100 is protected, and the safety of the pre-charging circuit is further improved. Specifically, the active disconnect protection module 800 employs an active disconnect protection fuse.
It is understood that a plurality of short-circuit protection units may be disposed in the pre-charging circuit according to actual requirements, and the present invention is not particularly limited thereto.
Referring to fig. 2 and 3, according to some embodiments of the invention, the pre-charge circuit further comprises: and a second freewheeling protection module 500 connected between the pre-charge switch 200 and the first end of the pre-charge inductor L, wherein the second freewheeling protection module 500 is configured to freewheel a second current flowing from the first end of the pre-charge inductor L to the pre-charge switch 200. The second freewheel protection module 500 includes a second diode D2, an anode of the second diode D2 is connected to the first end of the pre-charge inductor L, and a cathode of the second diode D2 is connected to the pre-charge switch 200. The direction of the current flowing from the first end of the pre-charging inductor L to the pre-charging switch 200 is the conducting direction of the second diode D2, and the second diode D2 is used for freewheeling the current of the first current loop.
Referring to fig. 2 and 3, according to some embodiments of the present invention, the signal detection amplifying module 310 includes a current detection resistor 311 and a signal amplifier 312, the current detection resistor 311 is connected in series between the negative electrode of the power battery 100 and the pre-charge switch 200, and the signal amplifier 312 is connected in parallel with the current detection resistor 311. When the main positive switch K1 of the battery pack is closed, the first current loop has a current signal I, and the current signal is detected and amplified by the signal detection and amplification module 310 to obtain an amplified signal, where the voltage of the amplified signal is V = I × R × G, where R is the resistance value of the current detection resistor 311, and G is the amplification factor of the signal amplifier 312. The comparator 320 compares the voltage value of the amplified signal with the voltage threshold Vref of the reference voltage output by the reference signal source 330, and outputs the voltage value comparison result, so that the maximum inductor current Imax = Vref/(R × G) allowed to pass in a circuit that can be set by the voltage threshold Vref and the amplification factor G of the signal amplifier 312. It is understood that the amplification factor G of the signal amplifier 312 and the resistance R of the current detection resistor 311 are not particularly limited in the present invention, and may be determined according to the actual circuit design requirement.
Referring to fig. 2 and 3, according to some embodiments of the present invention, the precharge circuit further includes: a driver module 700 connected between the nor logic module 340 and the precharge switch 200. Specifically, the driving module 700 is used for driving the precharge switch 200 to be turned on or off under the control of the nor logic module 340.
Referring to fig. 5, fig. 5 is a flowchart illustrating a method for controlling a pre-charge circuit according to an embodiment of the present invention, where the method for controlling a pre-charge circuit is applied to the pre-charge circuit shown in fig. 1, and the method for controlling a pre-charge circuit according to the embodiment of the present invention includes, but is not limited to, steps S510 to S530.
Step S510: a circuit signal in the precharge circuit is acquired.
Step S520: and comparing the circuit signal with the reference signal to obtain a voltage value comparison result.
Step S530: controlling the on-off of the pre-charging switch according to the voltage value comparison result and the clock signal, wherein the pre-charging switch is controlled to be switched on under the condition that the voltage value of the circuit signal is smaller than the voltage threshold of the reference signal and the clock signal is at a low level according to the voltage value comparison result, and a first current loop for pre-charging the capacitor through energy release of the power battery is formed; and when the voltage value comparison result shows that the voltage value of the circuit signal is greater than the voltage threshold value of the reference signal, the pre-charging switch is controlled to be switched off, and a second current loop which can be discharged by the pre-charging inductor to pre-charge the capacitor is formed.
Through steps S510 to S530, in the precharge circuit, when the voltage value comparison result is that the voltage value of the circuit signal is smaller than the voltage threshold and the clock signal is at the low level, the precharge switch 200 is controlled to be turned on, so as to form a first current loop for precharging the capacitor Cx by the power battery 100; when the voltage value comparison result indicates that the voltage value of the circuit signal is greater than the voltage threshold, the precharge switch 200 is controlled to be turned off, thereby forming a second current loop capable of precharging the capacitor Cx by discharging the precharge inductance L. According to the scheme of the embodiment of the invention, the on-off of the pre-charge switch 200 is controlled by the voltage value comparison result and the clock signal, the first current loop and the second current loop are switched by the pre-charge switch 200, and the first current loop and the second current loop are alternately pre-charged for the capacitor Cx until the voltage value at the two ends of the capacitor Cx is the same as the voltage value at the two ends of the power battery 100, that is to say: according to the scheme of the embodiment of the invention, the pre-charging efficiency can be improved, the heat productivity in the pre-charging process is reduced, the power consumption of the battery system is reduced, and the safety and the energy saving performance of the battery system are improved.
According to some embodiments of the invention, the pre-charge circuit further comprises: a battery pack main negative switch K2 connected between the negative electrode of the power battery 100 and the second end of the capacitor Cx, the method further comprising: and under the condition that the voltage value of the two ends of the capacitor Cx is equal to the voltage value of the power battery 100, closing the main negative switch K2 of the battery pack to finish the active pre-charging treatment. Specifically, in the case that the voltage value of the two ends of the capacitor Cx is equal to the voltage value of the power battery 100, the battery pack main negative switch K2 and the battery pack main positive switch K1 are closed, and a complete path for charging the power battery 100 is formed.
According to some embodiments of the invention, step S520: the step of comparing the circuit signal with the reference signal to obtain a voltage value comparison result comprises the following steps: acquiring a circuit signal; amplifying the circuit signal to output an amplified signal; comparing the amplified signal with a reference signal, and outputting a voltage value comparison result; and controlling the on-off of the pre-charging switch according to the voltage value comparison result and the clock signal.
In addition, an embodiment of the present invention provides a battery management system, including: such as the precharge circuit shown in fig. 1. It is understood that the battery management system includes a control unit for controlling the closing and opening of the battery pack main negative switch K2 and the battery pack main positive switch K1. Specifically, when the battery management system works, the pre-charging circuit controls the on-off of the pre-charging switch 200 through the comparison result of the voltage values and the clock signal, and switches the first current loop and the second current loop through the pre-charging switch 200 to enable the first current loop and the second current loop to alternately pre-charge the capacitor Cx until the voltage values at two ends of the capacitor Cx are the same as the voltage values at two ends of the power battery 100; in addition, the use of a pre-charging resistor is eliminated, so that the heat productivity in the pre-charging process is reduced, the power consumption of the battery system is reduced, and the safety and the energy saving performance of the battery system are improved; the integration level of the pre-charging circuit is improved, and the arrangement of a battery management system is facilitated.
In addition, an embodiment of the present invention provides an electric vehicle, including: a battery management system. Wherein the battery management system includes a pre-charge circuit as shown in fig. 1. It is understood that the electric vehicle further includes a master controller. Specifically, when the electric vehicle needs the battery management system to operate, the main controller of the electric vehicle sends a command of closing the main positive switch K1 of the battery pack to the battery management system, that is, a command of closing P + Relay, and after the main positive switch K1 of the battery pack is closed, the pre-charging circuit operates to pre-charge the capacitor Cx. The signal detection amplifying module 310 obtains a circuit signal, amplifies the circuit signal to obtain an amplified signal, and outputs the amplified signal to the non-inverting input terminal of the comparator 320; the comparator 320 compares the voltage value of the amplified signal with the voltage threshold of the reference signal and outputs the comparison result to the nor logic block 340; the nor logic module 340 controls the on/off of the pre-charge switch 200 according to the voltage value comparison result and the clock signal, and controls the pre-charge switch 200 to be turned on under the condition that the voltage value of the amplified signal is smaller than the voltage threshold and the clock signal is at a low level as the voltage value comparison result, so as to form a first current loop for pre-charging the capacitor Cx by the energy released by the power battery 100; when the voltage value comparison result indicates that the voltage value of the amplified signal is greater than the voltage threshold, the precharge switch 200 is controlled to be turned off, thereby forming a second current loop for precharging the capacitor Cx by discharging energy from the precharge inductor L. According to the scheme of the embodiment of the invention, the on-off of the pre-charging switch 200 is controlled by the voltage value comparison result and the clock signal, the first current loop and the second current loop are switched by the pre-charging switch 200, the first current loop and the second current loop are enabled to alternately pre-charge the capacitor Cx until the voltage value at the two ends of the capacitor Cx is the same as the voltage value at the two ends of the power battery 100, and the pre-charging processing of the capacitor Cx is completed. After the pre-charging process of the capacitor Cx is completed, the main controller of the electric vehicle sends a pack main negative switch K2 closing command to the battery management system to close the pack main negative switch K2, so as to form a complete path for charging the power battery 100. According to the scheme of the embodiment of the invention, the first current loop and the second current loop are used for precharging the capacitor Cx alternately, so that the precharging efficiency is improved while the precharging safety is ensured; by canceling the use of the pre-charging resistor, the heat productivity in the pre-charging process is reduced, the power consumption of the battery system is reduced, and the safety and the energy conservation of the battery system are improved; the integration level of the pre-charging circuit is improved, and the battery management system and the electric automobile can be assembled in a simpler whole automobile.
In one embodiment, when the electric vehicle needs the battery management system to work, the main controller of the electric vehicle sends a main positive switch closing command of the battery pack to the battery management system, the battery management system closes the main positive switch K1 of the battery pack according to the main positive switch closing command of the battery pack, and the pre-charging circuit pre-charges the capacitor Cx.
Next, the precharge step is further described with reference to the truth table of the NOR logic block 340 shown in FIG. 4 and the structure diagram of the precharge circuit shown in FIG. 3.
First, when the main positive switch K1 of the battery pack is closed, the current I =0 in the precharge circuit, and the voltage amplified by the detection of the signal detection amplifying module 310 is 0. Therefore, the comparator 320 compares the voltage amplified by the signal detection and amplification module 310 with the output voltage of the reference signal source 330 and outputs a low level.
Secondly, the clock generation module 350 fixedly outputs a clock signal with a certain frequency, the clock signal and the signal output by the comparator 320 are input into the nor logic module 340 together, when the output of the clock generation module 350 is 0 and the output of the comparator 320 is 0, the output of the nor logic module 340 is 1; when the output of the nor logic module 340 is 1, the precharge switch 200 is controlled to be closed, the inductor current of the precharge inductor L is increased, the output voltage of the signal detection amplifying module 310 is also increased, and the current loop in the precharge circuit is the first current loop of the power battery 100 which can release the precharge of the capacitor Cx.
Then, when the output voltage of the signal detection amplifying module 310 increases to be greater than the output voltage of the reference signal source 330, the comparator 320 outputs a high level, no matter the clock generating module 350 outputs a high level or a low level, the nor logic module 340 outputs 0, when the nor logic module 340 outputs 0, the precharge switch 200 is controlled to be turned off, the inductive current of the precharge inductor L decreases, the output voltage of the signal detection amplifying module 310 becomes 0, and the current loop in the precharge circuit is a second current loop capable of precharging the capacitor Cx by the precharge inductor L.
Then, when the output of the clock generation module 350 is 1 and the output of the comparator 320 is 0, the nor logic module 340 outputs 0, which controls the pre-charge switch 200 to be still turned off, the inductor current of the pre-charge inductor L is reduced, the output voltage of the signal detection amplifying module 310 becomes 0, and the current loop in the pre-charge circuit is still not released by the pre-charge inductor L to perform the second current loop for pre-charging the capacitor Cx.
Then, after 2/T time, when the output of the clock generation module 350 is 0 and the output of the comparator 320 is 0, the output of the nor logic module 340 is 1, the precharge switch 200 is controlled to be closed and conducted, the inductive current of the precharge inductor L is increased, the output voltage of the signal detection amplification module 310 is also increased, and the current loop in the precharge circuit is switched to the first current loop of the power battery 100 which can release energy to precharge the capacitor Cx; by controlling the on/off of the pre-charge switch 200, the first current loop and the second current loop alternately charge the capacitor Cx until the voltage of the capacitor Cx reaches the output voltage value Vbat of the power battery.
And finally, after the voltage of the capacitor Cx reaches Vbat, indicating that the pre-charging is finished, sending a main negative switch closing command of the battery pack to the battery management system by the electric automobile, closing and conducting the main negative switch K2 of the battery pack by the battery management system according to the main negative switch closing command of the battery pack, and forming a complete path for charging the power battery.
While the preferred embodiments of the present invention have been described in detail, it is to be understood that the invention is not limited to the precise embodiments disclosed, and that various equivalent changes and modifications may be effected therein by one skilled in the art without departing from the spirit and scope of the invention.
Claims (10)
1. A pre-charge circuit, comprising:
a capacitor;
the positive electrode of the power battery is connected with the first end of the capacitor;
a first terminal of the pre-charge inductor is connected to a first terminal of the capacitor, and a second terminal of the pre-charge inductor is connected to a second terminal of the capacitor;
the pre-charging switch is connected between the negative electrode of the power battery and the first end of the pre-charging inductor in series;
and the input end of the switch control module is connected with the negative electrode of the power battery, the output end of the switch control module is connected with the pre-charging switch and used for acquiring a circuit signal in the pre-charging circuit, comparing the circuit signal with a reference signal to obtain a voltage value comparison result, and controlling the on-off of the pre-charging switch according to the voltage value comparison result and a clock signal.
2. The pre-charge circuit of claim 1, wherein the switch control module comprises:
the signal detection and amplification module is connected between the negative electrode of the power battery and the pre-charging switch in series and used for acquiring the circuit signal and amplifying the circuit signal to output an amplified signal;
the non-inverting input end of the comparator is connected with the output end of the signal detection amplification module, the inverting input end of the comparator is connected with a reference signal source, and the comparator is used for receiving and comparing the amplified signal with the reference signal and outputting a voltage value comparison result;
and two logic input ends of the NOR logic module are respectively connected with the output end of the comparator and the output end of the clock generation module, and the output end of the NOR logic module is connected with the pre-charging switch and used for controlling the on-off of the pre-charging switch according to the voltage value comparison result and the clock signal.
3. The pre-charge circuit of claim 1, further comprising: and the battery pack main negative switch is connected between the negative electrode of the power battery and the second end of the capacitor.
4. The pre-charge circuit of claim 1, further comprising: a first freewheel protection module connected between a first terminal of the pre-charge inductance and a first terminal of the capacitor, the first freewheel protection module for freewheeling a first current flowing from the first terminal of the pre-charge inductance to the first terminal of the capacitor.
5. The pre-charge circuit of claim 4, further comprising: and the second follow current protection module is connected between a pre-charging switch and the first end of the pre-charging inductor and is used for follow current of a second current flowing from the first end of the pre-charging inductor to the pre-charging switch.
6. The pre-charge circuit of claim 2, wherein the signal detection and amplification module comprises a current detection resistor and a signal amplifier, the current detection resistor is connected in series between the negative pole of the power battery and the pre-charge switch, and the signal amplifier is connected in parallel with the current detection resistor.
7. A control method of a precharge circuit, applied to the precharge circuit according to claim 1, the method comprising:
acquiring a circuit signal in the pre-charging circuit;
comparing the circuit signal with a reference signal to obtain a voltage value comparison result;
controlling the on-off of a pre-charging switch according to a voltage value comparison result and a clock signal, wherein the pre-charging switch is controlled to be switched on under the condition that the voltage value of the circuit signal is smaller than the voltage threshold of the reference signal and the clock signal is at a low level according to the voltage value comparison result, and a first current loop for pre-charging a capacitor through energy release of a power battery is formed; and under the condition that the voltage value comparison result shows that the voltage value of the circuit signal is greater than the voltage threshold of the reference signal, the pre-charging switch is controlled to be switched off, and a second current loop capable of pre-charging the capacitor through the energy released by the pre-charging inductor is formed.
8. The method of controlling a precharge circuit according to claim 7, wherein the precharge circuit further comprises: a battery pack primary negative switch connected between the negative pole of the power cell and the second end of the capacitor, the method further comprising:
and under the condition that the voltage values of the two ends of the capacitor are equal to the voltage value of the power battery, closing the main negative switch of the battery pack to finish the active pre-charging treatment.
9. A battery management system, comprising: the pre-charge circuit of any of claims 1 to 6.
10. An electric vehicle, comprising: the battery management system of claim 9.
Priority Applications (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202211579870.XA CN115771429A (en) | 2022-12-09 | 2022-12-09 | Pre-charging circuit, control method thereof, battery management system and electric automobile |
| PCT/CN2023/117722 WO2024119932A1 (en) | 2022-12-09 | 2023-09-08 | Pre-charging circuit and control method therefor, battery management system, and electric vehicle |
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| Application Number | Priority Date | Filing Date | Title |
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| CN202211579870.XA CN115771429A (en) | 2022-12-09 | 2022-12-09 | Pre-charging circuit, control method thereof, battery management system and electric automobile |
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| CN115771429A true CN115771429A (en) | 2023-03-10 |
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| CN202211579870.XA Pending CN115771429A (en) | 2022-12-09 | 2022-12-09 | Pre-charging circuit, control method thereof, battery management system and electric automobile |
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| WO (1) | WO2024119932A1 (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2024119932A1 (en) * | 2022-12-09 | 2024-06-13 | 欣旺达动力科技股份有限公司 | Pre-charging circuit and control method therefor, battery management system, and electric vehicle |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2012120267A (en) * | 2010-11-29 | 2012-06-21 | Toshiba Corp | Charge controller |
| CN206432703U (en) * | 2016-11-30 | 2017-08-22 | 比亚迪股份有限公司 | Super-charge super-discharge protection circuit, protection device, battery management system and electric automobile |
| CN108539839A (en) * | 2018-05-02 | 2018-09-14 | 深圳市博德科创新能源技术有限公司 | The preliminary filling device of electric machine controller |
| CN110962679B (en) * | 2018-12-04 | 2020-11-06 | 宁德时代新能源科技股份有限公司 | Pre-charging circuit and pre-charging method |
| CN110789368B (en) * | 2019-11-12 | 2022-11-29 | 奇瑞汽车股份有限公司 | Electric automobile pre-charging circuit and control method thereof |
| CN115771429A (en) * | 2022-12-09 | 2023-03-10 | 欣旺达电动汽车电池有限公司 | Pre-charging circuit, control method thereof, battery management system and electric automobile |
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2022
- 2022-12-09 CN CN202211579870.XA patent/CN115771429A/en active Pending
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| Publication number | Priority date | Publication date | Assignee | Title |
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| WO2024119932A1 (en) * | 2022-12-09 | 2024-06-13 | 欣旺达动力科技股份有限公司 | Pre-charging circuit and control method therefor, battery management system, and electric vehicle |
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