CN219659449U - Pre-charging circuit, charging circuit and charging device - Google Patents

Abstract

The utility model provides a pre-charging circuit, a charging circuit and a charging device, wherein the pre-charging circuit comprises a current detection circuit, a pre-charging control circuit, a voltage reference circuit and a power supply output circuit, during pre-charging, the pre-charging current of a battery pack is detected through the current detection circuit and is compared with a preset current value in the pre-charging control circuit, a first PWM signal with corresponding magnitude is output, the first PWM signal is converted into a feedback reference voltage of the power supply output circuit through the voltage reference circuit, the power supply output circuit compares the feedback reference voltage with the preset reference voltage and adjusts and outputs the pre-charging voltage with corresponding magnitude, so that the pre-charging current of the battery pack is adjusted to reach the matched preset current value, dynamic matching adjustment of the pre-charging current is realized, the matched pre-charging current is used for charging the battery pack, and the pre-charging efficiency and the charging safety are improved.

Description

Pre-charging circuit, charging circuit and charging device

Technical Field

The present utility model relates to a precharge circuit, a charging circuit, and a charging device, and more particularly, to a precharge circuit, a charging circuit, and a charging device.

Background

In recent years, new energy is increasingly paid attention to with the shortage of petroleum resources and the increase of environmental pollution. The new energy electric automobile, the electric energy storage system and the like which are most paid attention to are rapidly developed.

As the market is expanding for lithium ion applications, many lithium batteries integrate a pre-charge circuit inside the battery to provide battery charging efficiency and safety.

At present, a pre-charging circuit generally samples constant current for pre-charging, and when the pre-charging circuit is applied to battery packs with different capacities, the battery packs are easy to charge too fast or too slow, so that the pre-charging efficiency is low and the charging safety is low.

Disclosure of Invention

The utility model aims to provide a pre-charging circuit which aims to improve the charging efficiency and the charging safety of a battery pack.

A first aspect of an embodiment of the present utility model proposes a precharge circuit including:

the detection circuit is used for detecting the pre-charging current of the battery pack and outputting a current detection signal representing the magnitude of the pre-charging current;

the precharge control circuit is connected with the detection circuit, receives the current detection signal, compares the current value of the precharge current with a preset current value, and outputs a first PWM signal with a duty ratio of a corresponding magnitude, wherein the difference value of the precharge current and the preset current value and the duty ratio value of the first PWM signal are in positive correlation change;

the voltage reference circuit is connected with the precharge control circuit, receives the first PWM signal and converts the first PWM signal into a feedback reference voltage, wherein the voltage value of the feedback reference voltage and the duty ratio value of the first PWM signal change in positive correlation;

and the power output circuit is respectively connected with the battery pack power end and the voltage reference circuit, receives the feedback reference voltage, compares the feedback reference voltage with a preset reference voltage, and outputs a precharge voltage with a corresponding magnitude to the battery pack so as to enable the precharge current to reach the preset current value, wherein the difference value between the preset reference voltage and the feedback reference voltage and the precharge voltage are in positive correlation change.

Optionally, the precharge control circuit is further connected to the power supply output circuit;

the precharge control circuit is also used for outputting a level enabling signal to control the power supply output circuit to be turned on or turned off.

Optionally, the current detection circuit comprises a sampling resistor and a detection chip;

the sampling resistor is connected with the battery pack in series, and the detection chip is correspondingly connected with two ends of the sampling resistor;

the battery pack comprises a plurality of single batteries connected in series;

the detection chip is correspondingly connected with two ends of the single batteries respectively and obtains the voltage value of each single battery.

Optionally, the precharge control circuit includes a precharge control chip;

the signal end of the precharge control chip is correspondingly connected with the voltage reference circuit and the current detection circuit respectively, and the enabling end of the precharge control chip is connected with the controlled end of the power supply output circuit.

Optionally, the voltage reference circuit includes a first resistor, a second resistor, a third resistor, a fourth resistor, a fifth resistor, a sixth resistor, a seventh resistor, a first capacitor, a second capacitor, and an operational amplifier;

the first end of the first resistor forms a signal input end of the voltage reference circuit, the second end of the first resistor, the first end of the first capacitor and the first end of the second resistor are commonly connected, the second end of the second resistor, the first end of the second capacitor and the first end of the third resistor are commonly connected, the second end of the third resistor is connected with a normal-phase input end of the operational amplifier, the inverting input end of the operational amplifier, the output end of the operational amplifier, the first end of the fourth resistor and the first end of the fifth resistor are commonly connected, the second end of the fifth resistor, the first end of the sixth resistor and the first end of the seventh resistor are commonly connected to form a signal output end of the voltage reference circuit, the second end of the seventh resistor, the output end of the power output circuit and the power supply end of the battery pack are commonly connected, and the second end of the first resistor, the second end of the second capacitor, the second end of the fourth resistor and the second end of the sixth resistor are all connected to the ground.

Optionally, the power output circuit includes:

the signal conversion circuit is correspondingly connected with the precharge control circuit and is used for converting the level enabling signal into a voltage enabling signal with a corresponding magnitude;

the switching power supply circuit is correspondingly connected with the voltage reference circuit, the signal conversion circuit and the battery pack respectively, and is correspondingly turned on or turned off by the voltage enabling signal;

and receiving the feedback reference voltage when the battery pack is started, comparing the feedback reference voltage with a preset reference voltage, and outputting a precharge current with a corresponding magnitude to the battery pack so that the precharge current reaches the preset current value.

Optionally, the switching power supply circuit comprises an eighth resistor, a ninth resistor, an inductor, a diode, a first electronic switching tube and a switching power supply chip;

the first end of the eighth resistor forms a power input end of the switching power supply circuit, the second end of the eighth resistor is connected with the first end of the first electronic switching tube, the second end of the first electronic switching tube, the first end of the inductor and the cathode of the diode are connected together, the second end of the inductor forms a power output end of the switching power supply circuit, the anode of the diode is grounded, the controlled end of the first electronic switching tube is connected with the first end of the ninth resistor, the second end of the ninth resistor is connected with the signal output end of the switching power supply chip, the signal input end of the switching power supply chip is connected with the signal output end of the voltage reference circuit, and the controlled end of the switching power supply chip is connected with the signal output end of the signal conversion circuit.

Optionally, the signal conversion circuit includes a tenth resistor, an eleventh resistor, a twelfth resistor, a thirteenth resistor, a fourteenth resistor, a fifteenth resistor, a second electronic switching tube, and a third electronic switching tube;

the first end of the tenth resistor forms the signal input end of the signal conversion circuit, the second end of the tenth resistor, the first end of the eleventh resistor and the controlled end of the second electronic switching tube are connected, the first end of the second electronic switching tube and the second end of the eleventh resistor are grounded, the second end of the second electronic switching tube, the first end of the twelfth resistor, the first end of the thirteenth resistor and the controlled end of the third electronic switching tube are commonly connected, the second end of the twelfth resistor is connected with a positive power supply end, the second end of the thirteenth resistor and the first end of the third electronic switching tube are commonly connected with each other, the second end of the third electronic switching tube and the first end of the fourteenth resistor are commonly connected with each other to form the signal output end of the signal conversion circuit, and the second end of the fifteenth resistor is connected with the power supply end of the switching power supply circuit.

A second aspect of the embodiment of the present utility model proposes a charging circuit comprising a main charging circuit and a precharge circuit as described above, the main charging circuit being arranged in parallel with the precharge circuit and connected in series with the battery pack.

A third aspect of the embodiments of the present utility model proposes a charging device comprising a charging circuit as described above.

Compared with the prior art, the embodiment of the utility model has the beneficial effects that: the pre-charging circuit performs pre-charging operation on the battery pack through the power output circuit, during pre-charging, the pre-charging current of the battery pack is detected through the current detection circuit and compared with a preset current value in the pre-charging control circuit, a first PWM signal with corresponding size is output, the first PWM signal is converted into a feedback reference voltage of the power output circuit through the voltage reference circuit, the power output circuit compares the feedback reference voltage with the preset reference voltage and adjusts and outputs the pre-charging voltage with corresponding size, and therefore the pre-charging current of the battery pack is adjusted to reach the matched preset current value, dynamic matching adjustment of the pre-charging current is achieved, and accordingly the battery pack is charged through the matched pre-charging current, and pre-charging efficiency and charging safety are improved.

Drawings

Fig. 1 is a schematic diagram of a charging circuit according to an embodiment of the present utility model;

FIG. 2 is a schematic diagram of a first module of a precharge circuit according to an embodiment of the present utility model;

FIG. 3 is a schematic diagram of a second module of the precharge circuit according to the embodiment of the present utility model;

fig. 4 is a schematic circuit diagram of a precharge circuit according to an embodiment of the present utility model.

Detailed Description

In order to make the technical problems, technical schemes and beneficial effects to be solved more clear, the utility model is further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are for purposes of illustration only and are not intended to limit the scope of the utility model.

Furthermore, the terms "first," "second," and the like, are used for descriptive purposes only and are not to be construed as indicating or implying a relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defining "a first" or "a second" may explicitly or implicitly include one or more such feature. In the description of the present utility model, the meaning of "a plurality" is two or more, unless explicitly defined otherwise.

In a first aspect of the embodiment of the present utility model, as shown in fig. 1, a precharge circuit 100 is connected in parallel with a main charging circuit 300 to connect to a charging power supply and to connect to a battery pack 200, the precharge circuit 100 is used for precharging the battery to realize dynamic balance of different battery packs 200, after the precharge is finished, the main charging circuit 300 is turned on to operate, the precharge circuit 100 is turned off, and the main charging circuit 300 completes normal charging operation of the battery pack 200.

In order to match different precharge current requirements of different battery packs 200 and improve precharge efficiency and charge safety, as shown in fig. 2, the precharge circuit 100 includes:

the current detection circuit 110 is correspondingly connected with the battery pack 200, and is used for detecting the precharge current of the battery pack 200 and outputting a current detection signal representing the magnitude of the precharge current;

the precharge control circuit 120 is connected with the detection circuit, the precharge control circuit 120 receives the current detection signal, compares the current value of the precharge current with a preset current value, and outputs a first PWM signal with a duty ratio of a corresponding magnitude, wherein the difference value of the precharge current and the preset current value and the duty ratio value of the first PWM signal are in positive correlation change;

the voltage reference circuit 130 is connected with the precharge control circuit 120, and the voltage reference circuit 130 receives the first PWM signal and converts the first PWM signal into a feedback reference voltage, wherein the voltage value of the feedback reference voltage and the duty ratio value of the first PWM signal change in positive correlation;

the power output circuit 140 is connected to the power terminal of the battery pack 200 and the voltage reference circuit 130, and the power output circuit 140 receives the feedback reference voltage, compares the feedback reference voltage with a preset reference voltage, and outputs a precharge voltage with a corresponding magnitude to the battery pack 200 so that the precharge current reaches a preset current value, wherein the difference between the preset reference voltage and the feedback reference voltage varies in positive correlation with the precharge voltage.

In this embodiment, the pre-charge control circuit 120 is provided with a preset current value matched with the battery pack 200, the preset current value can be determined by burning an external command, or the pre-charge control circuit 120 obtains each parameter of the battery pack 200 through a detection unit to determine specifically, and the specific setting mode is not limited.

Meanwhile, the power output circuit 140 is internally provided with a preset reference voltage corresponding to the precharge current of the battery pack 200, the preset reference voltage can be determined through external command burning, or the power output circuit 140 obtains each parameter of the battery pack 200 through the detection unit to be specifically determined, and the specific setting mode is not limited.

Before the corresponding battery pack 200 is connected and the precharge is started, the precharge control circuit 120 receives a precharge control instruction of the corresponding control unit and starts the precharge, the precharge control circuit 120 first outputs a first PWM signal of a duty cycle of an initial magnitude, for example, the duty cycle initial value is 40%, etc., the initial duty cycle is converted into a feedback reference voltage of a corresponding magnitude by the voltage reference circuit 130, the power output circuit 140 compares the feedback reference voltage with a preset reference voltage and outputs a precharge voltage of an initial magnitude to the battery pack 200, the battery pack 200 inputs a precharge current of an initial magnitude, at this time, the current detection circuit 110 detects the magnitude of the current precharge current of the battery pack 200 and feeds back a current detection signal to the precharge control circuit 120, the precharge control circuit 120 compares the current with a preset current value, and when the precharge current is detected to be smaller than the preset current value, the precharge control circuit 120 outputs the first PWM signal of a duty cycle value smaller than the initial duty cycle to the voltage reference circuit 130, for example, 30%, at this time, the feedback voltage to be converted and output a preset reference voltage is increased to the precharge current value corresponding to the precharge reference voltage of the preset voltage of the initial magnitude, and the precharge current is adjusted to be larger, and the precharge current is increased to reach the preset current value.

Similarly, when it is detected that the precharge current is greater than the preset current value, the precharge control circuit 120 outputs a first PWM signal having a duty ratio greater than the initial duty ratio to the voltage reference circuit 130, for example, 60%, at which time the feedback reference voltage outputted by the conversion becomes large, the difference between the preset reference voltage and the feedback reference voltage becomes small, and the power supply output circuit 140 outputs a precharge voltage smaller than the initial precharge voltage to the battery pack 200, and the corresponding precharge current becomes small in synchronization, thereby gradually adjusting the precharge current to reach the preset current value.

The real-time size of the duty ratio of the first PWM signal and the difference value between the current pre-charging current and the preset current value are in positive correlation, and may be changed in a proportional, a primary or a secondary function, or the like, optionally, the real-time size of the duty ratio of the first PWM signal is:

D1＝K1*(I1-I0)+D0；

wherein D1 is a duty ratio value of the current first PWM signal, K1 is a scaling factor, I1 is a current precharge current value, I0 is a preset current value, and D0 is a preset duty ratio value corresponding to the preset current value.

For example, when the current value of the current precharge current is detected to be 10A, the corresponding duty ratio is calculated to be 30%, that is, when the current value of the current precharge current is detected to be less than the preset current value, the duty ratio is reduced, and similarly, when the current value of the current precharge current is detected to be 30A, the calculated duty ratio is calculated to be 70%, that is, when the current value is detected to be greater than the preset current value, the duty ratio is increased, wherein the sizes of I0, D0 and K1 can be specifically determined according to actual adjustment.

The feedback reference voltage and the duty ratio value of the first PWM signal change in a correlation manner, and may change in a proportional manner, a primary function, a secondary function, or the like, for example, the real-time magnitude of the feedback reference voltage is:

V1＝K2*D1；

wherein V1 represents a real-time voltage value of the feedback reference voltage, K2 is a proportionality coefficient, and for example, K2 may be a corresponding value of 20, 30, etc.

The precharge voltage outputted by the power output circuit 140 changes synchronously with the precharge current, when the precharge voltage increases, the precharge current received by the battery pack 200 increases synchronously, whereas when the precharge voltage decreases, the precharge current received by the battery pack 200 decreases synchronously, wherein the precharge voltage changes in positive correlation with the difference between the preset reference voltage and the feedback reference voltage, and may change in a proportional, a primary, a secondary, or the like, and optionally, the precharge voltage is as follows:

V2＝K3*(V11-V1)+V12；

wherein V2 is the current precharge voltage, V11 is the preset reference voltage, V12 is the rated precharge voltage matched with the rated precharge current of the battery pack 200, and K3 is the proportionality coefficient.

For example, when the matched rated precharge current of the battery pack 200 is 20A, the matched rated precharge voltage is 40V, and when the precharge current of the battery pack 200 is detected to be less than 20A, the matched precharge voltage is less than 40V, at this time, the difference between the preset reference voltage and the feedback reference voltage becomes large, the current precharge voltage pair becomes large, until the power output circuit 140 outputs the rated precharge voltage to the battery pack 200 when the preset reference voltage and the feedback reference voltage are equal, and the battery pack 200 is precharged correspondingly to the received rated precharge current.

For example, assuming that the preset duty ratio is 50%, K1 is equal to 0.02, the preset current value, i.e., the rated precharge current value, is 20A, the matched rated precharge voltage is 40v, K2 is 20, the preset reference voltage is 10v, K3 is 2, and the ratio of precharge current to precharge voltage is 0.5.

When the initial precharge voltage outputted from the power output circuit 140 is 20V, the corresponding initial precharge current is 10A, the calculated corresponding duty ratio is 30%, the calculated feedback reference voltage is 6V, the calculated precharge voltage is 48V, and the battery pack 200 corresponds to the received precharge current of 24A. At this time, it is detected that the precharge current of the battery pack 200 is greater than 20A, the output duty ratio value is 58%, the feedback reference voltage is 11.6V, the calculated precharge voltage is 36.8V, and the precharge current received by the battery pack 200 is 18.4A. At this time, when it is detected that the precharge current of the battery pack 200 is less than 20A, the duty ratio value after adjustment is calculated again to be 46.8%, the calculated feedback reference voltage is 9.36V, the precharge voltage calculated again is 41.28V, and the corresponding precharge current is 20.64V. At this time, it is detected that the precharge current of the battery pack 200 is greater than 20A, the output duty ratio is 51.28%, the feedback reference voltage is 10.258V, the calculated precharge voltage is 39.488V, and the precharge current received by the battery pack 200 is 19.744a. At this time, when it is detected that the precharge current of the battery pack 200 is less than 20A, the duty ratio value after adjustment is calculated again to be 49.4%, the calculated feedback reference voltage is 9.898V, and the precharge voltage calculated again is 40.2V, and the precharge current received by the battery pack 200 is 20.1A. At this time, when it is detected that the precharge current of the battery pack 200 is greater than 20A, the duty ratio value after adjustment is calculated again to be 50.2%, the calculated feedback reference voltage is 10.04V, and the precharge voltage calculated again is 39.92V, and the precharge current received by the battery pack 200 is 19.96A. Similarly, the output precharge voltage and precharge current are adjusted to gradually approach the rated precharge voltage and precharge current until they are equivalent to the rated precharge voltage and precharge current and then stabilize.

The parameters can be selected correspondingly according to the change relation, and through reasonable setting, when the corresponding precharge current is detected, the matched rated precharge voltage and precharge current can be regulated and output step by step or directly.

The current detection circuit 110 may adopt a corresponding sampling resistor RS structure, a transformer circuit, etc., the precharge control circuit 120 may adopt a corresponding controller, a corresponding comparator, etc., the voltage reference circuit 130 may adopt a corresponding amplifying circuit, a corresponding filtering circuit, etc., the power output circuit 140 may adopt a corresponding switching power supply circuit 142, each circuit structure may be specifically set according to the requirement, and the specific circuit structure is not limited.

Compared with the prior art, the embodiment of the utility model has the beneficial effects that: the above-mentioned precharge circuit 100 performs a precharge operation on the battery pack 200 through the power output circuit 140, during precharge, the current detection circuit 110 detects the precharge current of the battery pack 200, and compares the precharge current with a preset current value in the precharge control circuit 120, outputs a first PWM signal with a corresponding magnitude, converts the first PWM signal into a feedback reference voltage of the power output circuit 140 through the voltage reference circuit 130, and the power output circuit 140 compares the feedback reference voltage with the preset reference voltage, and adjusts and outputs the precharge voltage with the corresponding magnitude, thereby adjusting the precharge current of the battery pack 200 to reach the matched preset current value, and realizing a dynamic matching adjustment of the precharge current, thereby charging the battery pack 200 with the matched precharge current, and improving the precharge efficiency and the charge safety.

With continued reference to fig. 2, the precharge control circuit 120 is optionally also connected to the power supply output circuit 140;

the precharge control circuit 120 is further configured to output a level enable signal to control the power supply output circuit 140 to be turned on or off.

In this embodiment, when receiving the precharge control command, the precharge control circuit 120 first outputs the level enable signal to control the power output circuit 140 to be turned on, then outputs the first PWM signal with the corresponding magnitude to the voltage reference circuit 130, and converts and outputs the feedback reference voltage with the corresponding magnitude to the power output circuit 140 through the voltage reference circuit 130, so that the power output circuit 140 outputs the precharge voltage and the precharge current with the corresponding magnitude.

Further, as shown in fig. 4, optionally, the current detection circuit 110 includes a sampling resistor RS and a detection chip U1;

the sampling resistor RS is connected with the battery pack 200 in series, and the detection chip U1 is correspondingly connected with two ends of the sampling resistor RS;

the battery pack 200 includes a plurality of unit cells BAT connected in series;

the detection chip U1 is correspondingly connected with two ends of the plurality of single batteries BAT respectively and obtains the voltage value of each single battery BAT.

In this embodiment, the detection chip U1 detects the voltages at two ends of the sampling resistor RS and calculates the resistance value of the sampling resistor RS to determine the current flowing through the sampling resistor RS, so as to determine the precharge current of the battery pack 200.

Meanwhile, the detection chip U1 also detects the voltage value of each battery cell BAT, so as to feedback and output a corresponding voltage detection signal to the precharge control circuit 120 according to the voltage value of each battery cell BAT, thereby driving the precharge control circuit 120 to output a level enabling signal to control the power output circuit 140 to be turned on or off, and realizing precharge protection.

Optionally, the precharge control circuit 120 includes a precharge control chip U2;

the signal end of the precharge control chip U2 is correspondingly connected with the voltage reference circuit 130 and the current detection circuit 110, respectively, and the enable end of the precharge control chip U2 is connected with the controlled end of the power output circuit 140.

The detection chip U1 collects the BAT voltage and the pre-charging current of the single battery, and reports the current and the voltage to the pre-charging control chip U2 through a communication bus, wherein the communication bus can be realized in the modes of I2C, SPI and the like.

Meanwhile, the precharge control chip U2 also compares the voltage value and the current value corresponding to the received current detection signal and the voltage detection signal with the preset voltage value and the preset current value, and performs output control and on-off control of the power output circuit 140 according to the precharge current of the battery pack 200 and the battery cell BAT voltage after the precharge is started, for example, adjusts the output size of the precharge voltage and the precharge current, or controls the power output circuit 140 to be turned off by the output level enable signal when the abnormal voltage of one battery cell BAT is detected.

Corresponding to the control relationship between the precharge control chip U2 and the power supply output circuit 140, optionally, as shown in fig. 3, the power supply output circuit 140 includes:

a signal conversion circuit 141 correspondingly connected to the precharge control circuit 120, the signal conversion circuit 141 being configured to convert the level enable signal into a voltage enable signal of a corresponding magnitude;

the switching power supply circuit 142, the switching power supply circuit 142 is correspondingly connected with the voltage reference circuit 130, the signal conversion circuit 141 and the battery pack 200 respectively, and the switching power supply circuit 142 is correspondingly turned on or turned off by a voltage enabling signal;

and receiving the feedback reference voltage at the time of starting, comparing the feedback reference voltage with a preset reference voltage, and outputting a precharge current of a corresponding magnitude to the battery pack 200 so that the precharge current reaches a preset current value.

In this embodiment, the signal conversion circuit 141 is configured to convert the level enable signal into a voltage enable signal corresponding to the switching power supply circuit 142, so as to implement functions such as signal amplification and conversion.

The power input terminal of the switching power supply circuit 142 inputs the charging power, the power output terminal of the switching power supply circuit 142 is connected with the battery pack 200, and the switching power supply circuit 142 correspondingly turns on or off after receiving the voltage enabling signal, and at the same time, receives the feedback reference voltage output by the voltage reference circuit 130 when turned on, and completes the operations of voltage comparison and output adjustment, thereby outputting the rated precharge voltage and the rated precharge current matched with the battery pack 200.

The signal conversion circuit 141 may have a corresponding amplifying circuit, or a level conversion circuit, and the switching power supply circuit 142 may have a corresponding step-up/step-down circuit, such as a BUCK circuit, a BOOST circuit, or the like, and the specific structure is not limited.

Further, as shown in fig. 4, the voltage reference circuit 130 optionally includes a first resistor R1, a second resistor R2, a third resistor R3, a fourth resistor R4, a fifth resistor R5, a sixth resistor R6, a seventh resistor R7, a first capacitor C1, a second capacitor C2, and an operational amplifier U3;

the first end of the first resistor R1 constitutes a signal input end of the voltage reference circuit 130, the second end of the first resistor R1, the first end of the first capacitor C1 and the first end of the second resistor R2 are commonly connected, the second end of the second resistor R2, the first end of the second capacitor C2 and the first end of the third resistor R3 are commonly connected, the second end of the third resistor R3 is connected with a non-inverting input end of the operational amplifier U3, an output end of the operational amplifier U3, the first end of the fourth resistor R4 and the first end of the fifth resistor R5 are commonly connected, the second end of the fifth resistor R5, the first end of the sixth resistor R6 and the first end of the seventh resistor R7 are commonly connected to form a signal output end of the voltage reference circuit 130, and the second end of the seventh resistor R7, the output end of the power output circuit 140 and the power supply end of the battery pack 200 are commonly connected, and the second end of the first resistor C1, the second end of the second capacitor C2, the second end of the fourth resistor R4 and the second end of the sixth resistor R6 are all grounded.

In this embodiment, the first PMW signal input by the precharge control chip U2 is converted into a corresponding feedback voltage by a second RC filter circuit formed by the first resistor R1, the second resistor R2, the third resistor R3, the first capacitor C1 and the second capacitor C2, for example, the precharge control chip U2 outputs a first PWM signal of a square wave signal with a duty ratio of 50% and a peak value of 3.3V, and after the second PWM signal is filtered by the second RC filter circuit, the output voltage is converted to 50% ×3.3v=1.65v. The operational amplifier U3 constitutes a voltage follower and outputs the filtered feedback voltage to the switching power supply circuit 142.

The precharge voltage output by the switching power supply circuit 142 and the voltage output by the voltage reference circuit 130 are divided by the fifth resistor R5, the sixth resistor R6 and the seventh resistor R7 to form a feedback reference voltage, that is, the feedback reference voltage is:

the VREF is a feedback voltage output by the secondary filter circuit, and the magnitude of the feedback reference voltage can be equivalent to v1=k4×v2+k5×vref, where K4 and K5 are proportionality coefficients, and the magnitudes of the corresponding K4 and K5 are determined according to the selected corresponding resistance values.

Alternatively, as shown in fig. 4, the switching power supply circuit 142 includes an eighth resistor R8, a ninth resistor R9, an inductance L1, a diode D1, a first electronic switching tube Q1, and a switching power supply chip U4;

the first end of the eighth resistor R8 forms the power input end of the switching power supply circuit 142, the second end of the eighth resistor R8 is connected with the first end of the first electronic switching tube Q1, the second end of the first electronic switching tube Q1, the first end of the inductor L1 and the cathode of the diode D1 are commonly connected, the second end of the inductor L1 forms the power output end of the switching power supply circuit 142, the anode of the diode D1 is grounded, the controlled end of the first electronic switching tube Q1 is connected with the first end of the ninth resistor R9, the second end of the ninth resistor R9 is connected with the signal output end of the switching power supply chip U4, the signal input end of the switching power supply chip U4 is connected with the signal output end of the voltage reference circuit 130, and the controlled end of the switching power supply chip U4 is connected with the signal output end of the signal conversion circuit 141.

Alternatively, the signal conversion circuit 141 includes a tenth resistor R10, an eleventh resistor R11, a twelfth resistor R12, a thirteenth resistor R13, a fourteenth resistor R14, a fifteenth resistor R15, a second electronic switching tube Q2, and a third electronic switching tube Q3;

the first end of the tenth resistor R10 constitutes the signal input end of the signal conversion circuit 141, the second end of the tenth resistor R10, the first end of the eleventh resistor R11 and the controlled end of the second electronic switching tube Q2 are connected, the first end of the second electronic switching tube Q2 and the second end of the eleventh resistor R11 are grounded, the second end of the second electronic switching tube Q2, the first end of the twelfth resistor R12, the first end of the thirteenth resistor R13 and the controlled end of the third electronic switching tube Q3 are commonly connected, the second end of the twelfth resistor R12 is connected with the positive power supply end, the second end of the thirteenth resistor R13 and the first end of the third electronic switching tube Q3 are commonly connected, the second end of the third electronic switching tube Q3 and the first end of the fourteenth resistor R14 are commonly connected, the second end of the fourteenth resistor R14 and the first end of the fifteenth resistor R15 are commonly connected with the signal output end of the signal conversion circuit 141, and the second end of the fifteenth resistor R15 is connected with the power supply input end of the switching power supply circuit 142.

In this embodiment, the inductor L1, the diode D1 and the first electronic switching tube Q1 form a BUCK topology circuit, when the precharge control chip U2 outputs a high level to the signal conversion circuit 141, the second electronic switching tube Q2 is turned on, the gate of the third electronic switching tube Q3 becomes a low level, the third electronic switching tube Q3 is turned off, at this time, the controlled end of the switching power supply chip U4 is pulled up by the fifteenth resistor R15, the switching power supply chip U4 starts to operate, the switching power supply chip U4 receives a corresponding feedback reference voltage through the signal input end and compares the feedback reference voltage with a preset reference voltage, thereby outputting a precharge voltage and a precharge current of a corresponding magnitude,

when the feedback reference voltage is greater than the preset reference voltage, the switching power supply chip U4 decreases the duty ratio of the output second PWM signal, and decreases the on time of the first electronic switching tube Q1, thereby decreasing the output voltage, and correspondingly, the precharge current decreases synchronously, and when the feedback reference voltage is less than the preset reference voltage, the switching power supply chip U4 increases the duty ratio of the output second PWM signal, and increases the on time of the first electronic switching tube Q1, thereby increasing the output voltage, and correspondingly, the precharge current increases synchronously.

Meanwhile, when the precharge control chip U2 outputs a low level, the second electronic switching tube Q2 is turned off, the third electronic switching tube Q3 receives a high level turn on, the controlled end of the switching power supply chip U4 is pulled down to a low level by the fourteenth resistor R14, and the switching power supply chip U4 is turned off to stop working.

The first electronic switching tube Q1 is optionally a PMOS tube, and the second electronic switching tube Q2 and the third electronic switching tube Q3 are NMOS tubes.

As shown in fig. 1, the present utility model further provides a charging circuit, which includes a main charging circuit 300 and a precharge circuit 100, and the specific structure of the precharge circuit 100 refers to the above embodiment, and since the present charging circuit adopts all the technical solutions of all the embodiments, at least has all the beneficial effects brought by the technical solutions of the embodiments, which are not described herein again. Wherein the main charging circuit 300 is disposed in parallel with the precharge circuit 100 and connected in series with the battery pack 200.

In this embodiment, the precharge circuit 100 and the main charge circuit 300 are connected in parallel to the charge power supply and the battery pack 200, the precharge circuit 100 is used for precharging the batteries to realize dynamic balance of different battery packs 200, after the precharge is finished, the main charge circuit 300 is turned on, the precharge circuit 100 is turned off, the main charge circuit 300 completes the normal charge operation of the battery pack 200, and the main charge circuit 300 and the precharge circuit 100 are respectively connected with the battery pack 200 correspondingly and perform charge adjustment and/or charge protection during precharge and normal charge.

The utility model also provides a charging device, which comprises a charging circuit, and the specific structure of the charging circuit refers to the embodiment, and because the charging device adopts all the technical schemes of all the embodiments, the charging device at least has all the beneficial effects brought by the technical schemes of the embodiments, and the detailed description is omitted.

The above embodiments are only for illustrating the technical solution of the present utility model, and not for limiting the same; although the utility model has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: the technical scheme described in the foregoing embodiments can be modified or some technical features thereof can be replaced by equivalents; such modifications and substitutions do not depart from the spirit and scope of the technical solutions of the embodiments of the present utility model, and are intended to be included in the scope of the present utility model.

Claims (10)

1. A precharge circuit, comprising:

the detection circuit is used for detecting the pre-charging current of the battery pack and outputting a current detection signal representing the magnitude of the pre-charging current;

the precharge control circuit is connected with the detection circuit, receives the current detection signal, compares the current value of the precharge current with a preset current value, and outputs a first PWM signal with a duty ratio of a corresponding magnitude, wherein the difference value of the precharge current and the preset current value and the duty ratio value of the first PWM signal are in positive correlation change;

the voltage reference circuit is connected with the precharge control circuit, receives the first PWM signal and converts the first PWM signal into a feedback reference voltage, wherein the voltage value of the feedback reference voltage and the duty ratio value of the first PWM signal change in positive correlation;

and the power output circuit is respectively connected with the battery pack power end and the voltage reference circuit, receives the feedback reference voltage, compares the feedback reference voltage with a preset reference voltage, and outputs a precharge voltage with a corresponding magnitude to the battery pack so as to enable the precharge current to reach the preset current value, wherein the difference value between the preset reference voltage and the feedback reference voltage and the precharge voltage are in positive correlation change.

2. The precharge circuit of claim 1 wherein said precharge control circuit is further connected to said power supply output circuit;

the precharge control circuit is also used for outputting a level enabling signal to control the power supply output circuit to be turned on or turned off.

3. The precharge circuit of claim 1 wherein said current sense circuit comprises a sampling resistor and a sense die;

the sampling resistor is connected with the battery pack in series, and the detection chip is correspondingly connected with two ends of the sampling resistor;

the battery pack comprises a plurality of single batteries connected in series;

the detection chip is correspondingly connected with two ends of the single batteries respectively and obtains the voltage value of each single battery.

4. The precharge circuit of claim 2, wherein the precharge control circuit comprises a precharge control chip;

the signal end of the precharge control chip is correspondingly connected with the voltage reference circuit and the current detection circuit respectively, and the enabling end of the precharge control chip is connected with the controlled end of the power supply output circuit.

5. The precharge circuit of claim 1, wherein the voltage reference circuit comprises a first resistor, a second resistor, a third resistor, a fourth resistor, a fifth resistor, a sixth resistor, a seventh resistor, a first capacitor, a second capacitor, and an operational amplifier;

the first end of the first resistor forms a signal input end of the voltage reference circuit, the second end of the first resistor, the first end of the first capacitor and the first end of the second resistor are commonly connected, the second end of the second resistor, the first end of the second capacitor and the first end of the third resistor are commonly connected, the second end of the third resistor is connected with a normal-phase input end of the operational amplifier, the inverting input end of the operational amplifier, the output end of the operational amplifier, the first end of the fourth resistor and the first end of the fifth resistor are commonly connected, the second end of the fifth resistor, the first end of the sixth resistor and the first end of the seventh resistor are commonly connected to form a signal output end of the voltage reference circuit, the second end of the seventh resistor, the output end of the power output circuit and the power supply end of the battery pack are commonly connected, and the second end of the first resistor, the second end of the second capacitor, the second end of the fourth resistor and the second end of the sixth resistor are all connected to the ground.

6. The precharge circuit of claim 2, wherein said power supply output circuit comprises:

the signal conversion circuit is correspondingly connected with the precharge control circuit and is used for converting the level enabling signal into a voltage enabling signal with a corresponding magnitude;

the switching power supply circuit is correspondingly connected with the voltage reference circuit, the signal conversion circuit and the battery pack respectively, and is correspondingly turned on or turned off by the voltage enabling signal;

and receiving the feedback reference voltage when the battery pack is started, comparing the feedback reference voltage with a preset reference voltage, and outputting a precharge current with a corresponding magnitude to the battery pack so that the precharge current reaches the preset current value.

7. The precharge circuit of claim 6, wherein the switching power supply circuit comprises an eighth resistor, a ninth resistor, an inductor, a diode, a first electronic switching tube, and a switching power supply chip;

the first end of the eighth resistor forms a power input end of the switching power supply circuit, the second end of the eighth resistor is connected with the first end of the first electronic switching tube, the second end of the first electronic switching tube, the first end of the inductor and the cathode of the diode are connected together, the second end of the inductor forms a power output end of the switching power supply circuit, the anode of the diode is grounded, the controlled end of the first electronic switching tube is connected with the first end of the ninth resistor, the second end of the ninth resistor is connected with the signal output end of the switching power supply chip, the signal input end of the switching power supply chip is connected with the signal output end of the voltage reference circuit, and the controlled end of the switching power supply chip is connected with the signal output end of the signal conversion circuit.

8. The precharge circuit of claim 6, wherein the signal conversion circuit comprises a tenth resistor, an eleventh resistor, a twelfth resistor, a thirteenth resistor, a fourteenth resistor, a fifteenth resistor, a second electronic switching tube, and a third electronic switching tube;

the first end of the tenth resistor forms the signal input end of the signal conversion circuit, the second end of the tenth resistor, the first end of the eleventh resistor and the controlled end of the second electronic switching tube are connected, the first end of the second electronic switching tube and the second end of the eleventh resistor are grounded, the second end of the second electronic switching tube, the first end of the twelfth resistor, the first end of the thirteenth resistor and the controlled end of the third electronic switching tube are commonly connected, the second end of the twelfth resistor is connected with a positive power supply end, the second end of the thirteenth resistor and the first end of the third electronic switching tube are commonly connected with each other, the second end of the third electronic switching tube and the first end of the fourteenth resistor are commonly connected with each other to form the signal output end of the signal conversion circuit, and the second end of the fifteenth resistor is connected with the power supply end of the switching power supply circuit.

9. A charging circuit comprising a main charging circuit and a pre-charging circuit according to any one of claims 1 to 8, the main charging circuit being arranged in parallel with the pre-charging circuit and being connected in series with the battery pack.

10. A charging device comprising the charging circuit of claim 9.