Soft start circuit and active equalization system

Abstract

This application discloses a soft-start circuit and an active balancing system. The soft-start circuit includes a power generation module, a processing module, a first pre-charge control module, and a second pre-charge control module. The power generation module outputs a power supply voltage according to an enable signal when the pre-charge ready condition is established. The processing module generates a first drive signal and a second drive signal according to the power supply voltage. The first pre-charge control module controls whether to establish the pre-charge ready condition according to the first drive signal. The second pre-charge control module controls the start or end of its own pre-charge according to the second drive signal to establish the pre-charge end condition. This can control the establishment and end of pre-charge between the battery pack and the power converter, thereby avoiding the direct connection of the power converter to the battery pack port, reducing or eliminating the surge current generated during startup, and thus avoiding damage to circuit components and arcing.

Description

Technical Field

[0001] This application relates to the field of new energy technology, specifically to a soft-start circuit and an active balancing system. Background Technology

[0002] To increase battery system capacity and battery life, most battery energy management systems have a passive balancing function, which reduces the state of charge (SOC) by dissipating energy through resistors, so as to adjust the SOC of all series-connected cells to the same value.

[0003] In contrast to passive balancing, active balancing involves adding power converters between battery packs to achieve energy flow between them, thereby achieving SOC balancing between battery packs.

[0004] However, when the power converter is directly connected to the battery pack's port, it generates a large inrush current during startup, which can damage circuit components and even cause arcing. Utility Model Content

[0005] This application provides a soft-start circuit and an active balancing system to alleviate the technical problem of large inrush current between the power converter and the battery pack during startup.

[0006] In a first aspect, this application provides a soft-start circuit, which includes a power generation module, a processing module, a first pre-charge control module, and a second pre-charge control module. The power generation module is connected to a battery pack and a power converter, and is configured to output a power supply voltage according to an enable signal when a pre-charge ready condition is established. The processing module is connected to the power generation module and is configured to generate a first drive signal and a second drive signal according to the power supply voltage. The first pre-charge control module is connected to the processing module, the battery pack, and the power converter, and is configured to control whether a pre-charge ready condition is established according to the first drive signal. The second pre-charge control module is connected to the processing module and the power converter, and is configured to control the start or end of its own pre-charge according to the second drive signal.

[0007] Optionally, the first precharge control module includes a first resistor and a first transistor. The first terminal of the first transistor is connected to the first end of the first resistor and the first terminal of the battery pack. The second terminal of the first transistor is connected to the second end of the first resistor and the first transmission terminal of the power converter. The control terminal of the first transistor is connected to the processing module to receive the first drive signal.

[0008] Optionally, the first resistor is a negative temperature coefficient thermistor.

[0009] Optionally, the first transistor is in the off state, indicating the establishment of the precharge ready condition; or, the first transistor is in the on state, indicating that the precharge ready condition is not met.

[0010] Optionally, the power generation module includes a first capacitor, a diode, a second capacitor, and an auxiliary power supply. The first terminal of the first capacitor is connected to the second terminal of the battery pack and the second transmission terminal of the power converter. The anode of the diode is connected to the first terminal of the first capacitor. The first terminal of the second capacitor is connected to the cathode of the diode. The second terminal of the second capacitor is connected to the second terminal of the first transistor, the second terminal of the first resistor, the second terminal of the first capacitor, and the first transmission terminal of the power converter. The first input terminal of the auxiliary power supply is connected to the first terminal of the second capacitor and the cathode of the diode. The second input terminal of the auxiliary power supply is connected to the second terminal of the second capacitor. The output terminal of the auxiliary power supply is connected to the processing module. The enable terminal of the auxiliary power supply is connected to the control terminal of the battery pack.

[0011] Optionally, the battery pack includes a battery management system that outputs an enable signal. When the enable signal is valid, and the voltage across the second capacitor is greater than the turn-on voltage threshold of the auxiliary power supply, the auxiliary power supply outputs a power supply voltage to the processing module.

[0012] Optionally, the power generation module also includes a fuse, with the first end of the fuse connected to the second terminal of the battery pack, and the second end of the fuse connected to the first end of the first capacitor, the positive terminal of the diode, and the second transmission terminal of the power converter.

[0013] Optionally, the second precharge control module includes a third capacitor and a second transistor. The first terminal of the third capacitor is connected to the first terminal of the first capacitor. The first electrode of the second transistor is connected to the second terminal of the third capacitor. The second electrode of the second transistor is connected to the second electrode of the first transistor and the first transmission terminal of the power converter. The control electrode of the second transistor is connected to the processing module to receive the second drive signal. The third capacitor is an aluminum electrolytic capacitor. When the processing module stops working, the second transistor is in the off state.

[0014] Optionally, the processing module is connected to the power converter and is configured to generate control signals for controlling the power converter based on the sampled signals obtained from the power converter.

[0015] Secondly, this application provides an active balancing system, which includes the aforementioned soft-start circuit.

[0016] The soft-start circuit and active balancing system provided in this application, through the power generation module, outputs a power supply voltage according to the enable signal when the pre-charge ready condition is established. The processing module generates a first drive signal and a second drive signal according to the power supply voltage. The first pre-charge control module controls whether to establish the pre-charge ready condition according to the first drive signal. The second pre-charge control module controls the start or end of its own pre-charge according to the second drive signal. It can control the establishment and end of pre-charge between the battery pack and the power converter, thereby avoiding the direct connection of the power converter to the battery pack port, reducing or eliminating the surge current generated during the start-up process, and thus avoiding damage to circuit components and arcing. Attached Figure Description

[0017] The technical solution and other beneficial effects of this application will become apparent from the following detailed description of specific embodiments in conjunction with the accompanying drawings.

[0018] Figure 1 This is a schematic block diagram of the soft-start circuit provided in an embodiment of this application.

[0019] Figure 2 The circuit diagram of the first precharge control module provided in the embodiments of this application.

[0020] Figure 3 The circuit schematic diagram of the power generation module provided in the embodiment of this application.

[0021] Figure 4 The circuit diagram of the second precharge control module provided in the embodiments of this application.

[0022] Figure 5 This is a schematic diagram of the first structure of the active balancing system provided in the embodiments of this application.

[0023] Figure 6 This is a schematic diagram of a second structure of the active balancing system provided in an embodiment of this application. Detailed Implementation

[0024] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of this application without creative effort are within the scope of protection of this application.

[0025] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Features thus defined as "first" or "second" may explicitly or implicitly include one or more of the stated features. In the description of this application, "multiple" means two or more unless otherwise explicitly specified.

[0026] To increase battery system capacity and battery life, most battery energy management systems employ passive balancing to reduce the state of charge (SOC) by dissipating energy through resistors, adjusting the SOC of all series-connected cells to the same value. Although the structure is simple, the adjustment cycle is long and it increases the heat of the battery module.

[0027] In contrast to passive balancing, active balancing involves adding power converters between battery packs to achieve energy flow between them, thereby achieving state-of-the-art (SOC) balance. This method can achieve higher balancing current, lower heat generation, faster balancing time, and higher energy efficiency.

[0028] To increase the anti-interference capability of the power converter's input voltage, a larger capacity input electrolytic capacitor is used. If the power converter is directly connected to the battery pack's port, a large surge current will be generated, damaging circuit components and even causing arcing.

[0029] When aluminum electrolytic capacitors are used as input capacitors, the aluminum film has a layer of water-based gel-like substance. When a voltage is applied across the two ends of the aluminum electrolytic capacitor, the oxide film will reform and repair, generating leakage current. This leakage current increases with the voltage applied across the aluminum electrolytic capacitor, thereby increasing the system's static power consumption. If the battery module is not charged for a long time, it may lead to battery depletion, affecting battery life.

[0030] In view of this, this application adds a soft-start circuit between the battery pack and the power converter. This circuit pre-charges the aluminum electrolytic capacitors with limited current when the power converter is turned on, and prevents the battery pack voltage from being applied to the terminals of the aluminum electrolytic capacitors when the power converter stops operating. This not only reduces leakage current when the power converter stops operating, thus achieving low static power consumption, but also avoids the risk of excessive inrush current caused by directly connecting the power converter to the battery pack port, which could lead to component damage or arcing.

[0031] like Figure 1As shown, this embodiment provides a soft-start circuit 100, which includes a power generation module 10, a processing module 20, a first pre-charge control module 30, and a second pre-charge control module 40. The power generation module 10 is connected to the battery pack 210 and the power converter 220, and is configured to output a power supply voltage according to an enable signal EN when a pre-charge ready condition is established. The processing module 20 is connected to the power generation module 10 and is configured to generate a first drive signal DR1 and a second drive signal DR2 according to the power supply voltage. The first pre-charge control module 30 is connected to the processing module 20, the battery pack 210, and the power converter 220, and is configured to control whether to establish a pre-charge ready condition according to the first drive signal DR1. The second pre-charge control module 40 is connected to the processing module 20 and the power converter 220, and is configured to control the start or end of its own pre-charge according to the second drive signal DR2.

[0032] It is understood that the soft-start circuit 100 provided in this embodiment outputs a power supply voltage according to the enable signal EN when the pre-charge ready condition is established by the power supply generation module 10. The processing module 20 generates a first drive signal DR1 and a second drive signal DR2 according to the power supply voltage. The first pre-charge control module 30 controls whether to establish the pre-charge ready condition according to the first drive signal DR1. The second pre-charge control module 40 controls the start or end of its own pre-charge according to the second drive signal DR2. It can control the establishment and end of pre-charge between the battery pack 210 and the power converter 220, thereby avoiding the power converter 220 from being directly connected to the port of the battery pack 210, reducing or eliminating the surge current generated during the start-up process, and thus avoiding damage to circuit components and arcing.

[0033] It should be noted that the power converter 220 is connected between different battery packs 210 to realize energy flow between the battery packs 210, thereby achieving state of charge (SOC) balancing among the battery packs 210. The processing module 20 may include a processor, a first drive unit, and a second drive unit. The first drive unit is controlled by the processor to generate a first drive signal DR1, and the second drive unit is controlled by the processor to generate a second drive signal DR2. The processor may be, but is not limited to, a digital signal processing module 20 (DSP), or a microcontroller or programmable logic device. The drive units are used to improve drive capability to reliably control the switching on and off of transistors.

[0034] The precharge ready condition refers to a prerequisite for the second precharge control module 40 to start its own precharge. If the precharge ready condition is not met, the second precharge control module 40 will not start its own precharge.

[0035] In some embodiments, such as Figure 2 As shown, the first precharge control module 30 includes a first resistor R1 and a first transistor S1. The first terminal of the first transistor S1 is connected to the first end of the first resistor R1 and the first terminal of the battery pack 210. The second terminal of the first transistor S1 is connected to the second end of the first resistor R1 and the first transmission terminal of the power converter 220. The control terminal of the first transistor S1 is connected to the processing module 20 to receive the first drive signal DR1.

[0036] It should be noted that the first transistor S1 is, exemplarily, an N-channel field-effect transistor (MOS), with its first terminal, second terminal, and control terminal being the source, drain, and gate, respectively. When the first transistor S1 is in the off state, pre-charge current flows through the first resistor R1 to form a pre-charge circuit. The first resistor R1 limits the pre-charge current, indicating that the pre-charge ready condition has been established, and pre-charging can proceed. Alternatively, when the first transistor S1 is in the on state, it bypasses or short-circuits the first resistor R1, indicating that the pre-charge ready condition is not met, and pre-charging needs to be stopped.

[0037] In some embodiments, the first resistor R1 is a negative temperature coefficient thermistor. It should be noted that the resistance value of the negative temperature coefficient first resistor R1 decreases as the precharge progresses, which not only gradually increases the precharge current but also helps to reduce power consumption.

[0038] In some embodiments, such as Figure 3 As shown, the power generation module 10 includes a first capacitor C1, a diode D1, a second capacitor C2, and an auxiliary power supply 11. The first terminal of the first capacitor C1 is connected to the second terminal of the battery pack 210 and the second transmission terminal of the power converter 220. The positive terminal of the diode D1 is connected to the first terminal of the first capacitor C1. The first terminal of the second capacitor C2 is connected to the negative terminal of the diode D1, and the second terminal of the second capacitor C2 is connected to the second terminal of the first transistor S1, the second terminal of the first resistor R1, the second terminal of the first capacitor C1, and the first transmission terminal of the power converter 220. The first input terminal of the auxiliary power supply 11 is connected to the first terminal of the second capacitor C2 and the negative terminal of the diode D1. The second input terminal of the auxiliary power supply 11 is connected to the second terminal of the second capacitor C2. The output terminal of the auxiliary power supply 11 is connected to the processing module 20, and the enable terminal of the auxiliary power supply 11 is connected to the control terminal of the battery pack 210.

[0039] It should be noted that during the power-on process, the battery pack 210 first charges the first capacitor C1 through the first resistor R1. When the voltage difference between the voltage across the first capacitor C1 and the voltage across the second capacitor C2 is greater than the voltage drop of the diode D1, the second capacitor C2 begins to be charged. When the voltage across the second capacitor C2 is greater than the turn-on voltage threshold of the auxiliary power supply 11, the auxiliary power supply 11, which receives the valid enable signal EN, turns on and slowly builds up the power supply voltage so that the processing module 20 can work normally and output the first drive signal DR1 and the second drive signal DR2.

[0040] Diode D1 is also used to prevent reverse current from flowing into the auxiliary power supply 11. Both the first capacitor C1 and the second capacitor C2 are multilayer ceramic capacitors (MLLC).

[0041] In some embodiments, such as Figure 3 As shown, the power generation module 10 also includes a fuse F1. The first end of the fuse F1 is connected to the second terminal of the battery pack 210, and the second end of the fuse F1 is connected to the first end of the first capacitor C1, the positive terminal of the diode D1, and the second transmission terminal of the power converter 220.

[0042] It should be noted that the first and second terminals of the battery pack 210 are the negative and positive terminals, respectively. The fuse F1 is connected in series in the positive main circuit of the battery pack 210. If the current exceeds the threshold, the fuse will heat up and melt, physically cutting off the high-voltage path and preventing the battery from thermal runaway, catching fire, or exploding due to short circuit / overload.

[0043] In some embodiments, such as Figure 4 As shown, the second precharge control module 40 includes a third capacitor C3 and a second transistor S2. The first terminal of the third capacitor C3 is connected to the first terminal of the first capacitor C1. The first terminal of the second transistor S2 is connected to the second terminal of the third capacitor C3. The second terminal of the second transistor S2 is connected to the second terminal of the first transistor S1 and the first transmission terminal of the power converter 220. The control terminal of the second transistor S2 is connected to the processing module 20 to receive the second drive signal DR2. The third capacitor C3 is an aluminum electrolytic capacitor. When the processing module 20 stops working, the second transistor S2 is in the off state.

[0044] It should be noted that the second transistor S2 can be an N-channel field-effect transistor, with its first terminal, second terminal, and control terminal being the drain, source, and gate, respectively. When the processing module 20 stops working, the second transistor S2 is in the off state, which prevents the voltage of the battery pack 210 from being applied to the two ends of the third capacitor C3, thereby reducing or avoiding leakage current in the third capacitor C3 and reducing static power consumption.

[0045] The conduction of the second transistor S2 corresponds to the start of the pre-charging of the second pre-charge control module 40 itself, and the cutoff of the second transistor S2 corresponds to the end of the pre-charging of the second pre-charge control module 40 itself.

[0046] In some embodiments, such as Figure 4 As shown, the battery pack 210 includes a battery module 211 and a battery management system 212 that outputs an enable signal EN. The battery module 211 can be a single battery or a series-parallel combination of multiple batteries.

[0047] In some embodiments, such as Figure 4 As shown, the processing module 20 is connected to the power converter 220, and the processing module 20 is configured to generate a control signal for controlling the power converter 220 based on the sampled signal obtained from the power converter 220.

[0048] It should be noted that the sampling signal may include at least one of the input voltage / current, output voltage / current, and temperature signals of the power converter 220. The input voltage / current can monitor the actual voltage and current of the battery pack 210, determine if there is overvoltage / overcurrent, prevent inrush current, and protect the input stage of the power converter 220. The output voltage / current can detect the target cell voltage for energy transfer and the magnitude of the balancing current, control the balancing current in a closed loop to avoid overcurrent damage to the cells, and calculate the SOC balancing efficiency. The temperature signal can monitor the temperature of the converter's power devices, such as MOSFETs and inductors, and reduce the balancing current or suspend operation when overheating occurs to prevent device damage.

[0049] The working principle of the soft-start circuit 100 described above is as follows:

[0050] Power-on working principle:

[0051] Step 1: The battery management system 212 of the battery pack 210 sends an enable command to the auxiliary power supply 11 (enable signal EN is valid, for example, high level), and the battery pack 210 charges the first capacitor C1 through the first resistor R1.

[0052] Step 2: When the voltage difference between the two ends of the first capacitor C1 and the two ends of the second capacitor C2 is greater than the voltage drop of the diode D1, the second capacitor C2 is charged. After the voltage across the second capacitor C2 is greater than the turn-on voltage threshold of the auxiliary power supply 11, the auxiliary power supply 11 is turned on, and the output voltage of the auxiliary power supply 11 is slowly established, thereby establishing the power supply voltage of the processing module 20, so that the processing module 20 can work normally.

[0053] Step 3: The processing module 20 sends out the second drive signal DR2 to turn on the second transistor S2, which charges the third capacitor C3 through the first resistor R1.

[0054] Step 4: When the voltage difference between the voltage across the third capacitor C3 and the output voltage of the battery pack 210 is less than a preset value, such as 2V, the processing module 20 sends a first drive signal DR1 to turn on the first transistor S1, short-circuit the first resistor R1, and end the pre-charging.

[0055] Shutdown working principle:

[0056] Step 1: The battery management system 212 of the battery pack 210 sends a shutdown command to the auxiliary power supply 11 (the enable signal EN is invalid, for example, low level), and the auxiliary power supply 11 shuts down.

[0057] Step 2: After the processing module 20 dissipates the voltage of the output capacitor in the auxiliary power supply 11, the processing module 20 stops working, shutting down the first driving unit that generates the first driving signal DR1 and the second driving unit that generates the second driving signal DR2. The second transistor S2 is turned off, and the third capacitor C3 is disconnected from the battery pack 210 to reduce leakage current and lower battery static power consumption; the first transistor S1 is turned off and connected to the first resistor R1 to prepare for the next power-on.

[0058] In some embodiments, such as Figure 5 As shown, this embodiment provides an active balancing system 200, which includes the soft-start circuit 100 described above.

[0059] It is understood that, since the active balancing system 200 provided in this embodiment includes the aforementioned soft-start circuit 100, it can also output a power supply voltage according to the enable signal EN when the pre-charge ready condition is established by the power supply generation module 10. The processing module 20 generates a first drive signal DR1 and a second drive signal DR2 according to the power supply voltage. The first pre-charge control module 30 controls whether to establish the pre-charge ready condition according to the first drive signal DR1, and the second pre-charge control module 40 controls the start or end of its own pre-charge according to the second drive signal DR2. It can control the establishment and end of pre-charge between the battery pack 210 and the power converter 220, thereby avoiding the power converter 220 from being directly connected to the port of the battery pack 210, reducing or eliminating the surge current generated during the startup process, and thus avoiding damage to circuit components and arcing.

[0060] In some embodiments, such as Figure 6 As shown, the active balancing system 200 also includes a battery pack 210 and a power converter 220, with a soft-start circuit 100 connected between the battery pack 210 and the power converter 220. This prevents the power converter 220 from being directly connected to the port of the battery pack 210, reducing or eliminating inrush current generated during startup, thereby preventing damage to circuit components and arcing.

[0061] In the above embodiments, the descriptions of each embodiment have different focuses. For parts not described in detail in a certain embodiment, please refer to the relevant descriptions in other embodiments.

[0062] The soft-start circuit 100 and active balancing system 200 provided in the embodiments of this application have been described in detail above. Specific examples have been used to illustrate the principles and implementation methods of this application. The description of the above embodiments is only for the purpose of helping to understand the technical solutions and core ideas of this application. Those skilled in the art should understand that they can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. These modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this application.

Claims

1. A soft start circuit, characterized by, The soft-start circuit includes: The power generation module, connected to the battery pack and power converter, is configured to output a power supply voltage based on an enable signal when a precharge ready condition is established. The processing module, connected to the power generation module, is configured to generate a first drive signal and a second drive signal based on the power supply voltage. The first pre-charge control module, connected to the processing module, the battery pack, and the power converter, is configured to control whether to establish the pre-charge ready condition according to the first drive signal. The second pre-charge control module, connected to the processing module and the power converter, is configured to control the start or end of its own pre-charge according to the second drive signal.

2. The soft start circuit of claim 1, wherein, The first precharge control module includes: First resistor; A first transistor, the first terminal of which is connected to the first terminal of the first resistor and the first terminal of the battery pack, the second terminal of which is connected to the second terminal of the first resistor and the first transmission terminal of the power converter, and the control terminal of which is connected to the processing module to receive the first drive signal.

3. The soft start circuit of claim 2, wherein, The first resistor is a negative temperature coefficient thermistor.

4. The soft start circuit of claim 2, wherein, The first transistor is in the off state, indicating that the precharge ready condition has been established; or, the first transistor is in the on state, indicating that the precharge ready condition is not met.

5. The soft start circuit of claim 2, wherein, The power generation module includes: A first capacitor, wherein a first terminal of the first capacitor is connected to a second terminal of the battery pack and a second transmission terminal of the power converter; A diode, wherein the anode of the diode is connected to the first terminal of the first capacitor; The second capacitor has its first terminal connected to the negative terminal of the diode, and its second terminal connected to the second terminal of the first transistor, the second terminal of the first resistor, the second terminal of the first capacitor, and the first transmission terminal of the power converter. An auxiliary power supply is provided, wherein the first input terminal of the auxiliary power supply is connected to the first terminal of the second capacitor and the negative terminal of the diode, the second input terminal of the auxiliary power supply is connected to the second terminal of the second capacitor, the output terminal of the auxiliary power supply is connected to the processing module, and the enable terminal of the auxiliary power supply is connected to the control terminal of the battery pack.

6. The soft start circuit of claim 5, wherein, The battery pack includes a battery management system that outputs the enable signal. When the enable signal is valid, and the voltage across the second capacitor is greater than the turn-on voltage threshold of the auxiliary power supply, the auxiliary power supply outputs the supply voltage to the processing module.

7. The soft start circuit of claim 5, wherein, The power generation module also includes a fuse, the first end of which is connected to the second terminal of the battery pack, and the second end of which is connected to the first terminal of the first capacitor, the positive terminal of the diode, and the second transmission terminal of the power converter.

8. The soft start circuit of claim 5, wherein, The second precharge control module includes: A third capacitor, wherein the first terminal of the third capacitor is connected to the first terminal of the first capacitor; The second transistor has its first terminal connected to the second terminal of the third capacitor, its second terminal connected to the second terminal of the first transistor and the first transmission terminal of the power converter, and its control terminal connected to the processing module to receive the second drive signal. The third capacitor is an aluminum electrolytic capacitor, and the second transistor is in the off state when the processing module stops working.

9. The soft start circuit of any of claims 1-8, wherein, The processing module is connected to the power converter and is configured to generate control signals for controlling the power converter based on the sampled signals obtained from the power converter.

10. An active equalization system characterized by, The active balancing system includes the soft-start circuit as described in any one of claims 1-9.

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