Charging protection circuit, charging device and system

Abstract

The application provides a charging protection circuit, a charging device and a system, comprising: an input current sampling unit, a first signal generating unit, an input current control unit, a second signal generating unit; wherein the input current sampling unit is connected between an input circuit and a PSR circuit, the input current sampling unit is connected with the first signal generating unit and the input current control unit, the input current control unit is connected with the second signal generating unit, and the first signal generating unit and the second signal generating unit are connected with a control chip in the PSR circuit. The input pulse current input from the input circuit into the PSR circuit is detected pulse by pulse, the charging process is controlled by controlling the PSR circuit according to the input pulse current, overcurrent charging is avoided, and charging safety and charging efficiency are improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the electric vehicle charging technology field, and in particular to a charging protection circuit, a charging device and a system. BACKGROUND

[0002] As a safe, less pollution, low cost of use of new traffic, in recent years, electric vehicles have been rapid development, has been widely used in household, freight, logistics, passenger transport and other occasions. At present, the charging device of electric vehicle generally has a phase shift resonant full bridge circuit, namely PSR circuit, to realize ZVS (zero voltage switching).

[0003] Among them, in the PSR circuit, under the control of control chip such as UCC28950, UCC28951, NCP1399 and the like, according to the rated charging voltage and the rated charging current of the electric vehicle, one of the two power switch tubes on the same bridge arm is turned on and the other is turned off at the same time, and correspondingly, one of the two power switch tubes on the other bridge arm is turned on and the other is turned off, so as to convert the input DC into DC of rated charging voltage, realizing the conversion of DC-DC.

[0004] However, in the charging process, when the charging line fails, for example, short circuit and other faults cause the current in the charging circuit to be too large, thereby affecting the charging, resulting in low charging efficiency, and even causing safety accidents. SUMMARY

[0005] The present application provides a charging protection circuit, a charging device and a system to solve the problem of low charging efficiency and even safety hazards caused by charging line failure when charging the electric vehicle in the prior art.

[0006] In a first aspect, the present application provides a charging protection circuit, comprising: an input current sampling unit, a first signal generating unit, an input current control unit, a second signal generating unit; wherein the input current sampling unit is connected between the input circuit and the PSR circuit, the input current sampling unit is connected with the first signal generating unit, the input current control unit, the input current control unit is connected with the second signal generating unit, the first signal generating unit, the second signal generating unit is connected with the control chip in the PSR circuit;

[0007] The input current sampling unit is configured to collect the input pulse current input by the input circuit into the PSR circuit, and obtain a corresponding response pulse voltage according to the input pulse current.

[0008] The first signal generation unit is configured to obtain a first control signal according to the response pulse voltage, and send the first control signal to a first end of the control chip, so that the control chip adjusts the pulse of the PSR circuit according to the first control signal.

[0009] The input current control unit is configured to obtain a response direct current voltage according to the response pulse voltage, and obtain a charging control signal according to a first comparison result of the response direct current voltage and a first threshold value, the charging control signal being used to control the second signal generation unit to output a second control signal.

[0010] The second signal generation unit is configured to output the second control signal to a second end of the control chip according to the charging control signal, so that the control chip controls a charging state according to the second control signal, the charging state including charging and stopping charging.

[0011] Optionally, the device further comprises an output acquisition unit and an output control unit, the output acquisition unit being connected with the PSR circuit, the output acquisition unit being connected with the output control unit, and the output control unit being connected with the second signal generation unit.

[0012] The output acquisition unit is configured to obtain an output voltage and / or an output current of the PSR circuit.

[0013] The output control unit is configured to obtain the charging control signal according to the output voltage and / or the output current, and send the charging control signal to the second signal generation unit.

[0014] Optionally, the input current sampling unit comprises a current sensor, a first resistor, a second resistor and a first capacitor, the second resistor and the first capacitor being connected in parallel and then connected with the first resistor, the primary side of the current sensor being connected between the input circuit and the PSR circuit, the secondary side being connected with the first resistor, and the second resistor and the first capacitor being connected in parallel and then connected with the first signal generation unit in parallel.

[0015] The current sensor is configured to sample the current input by the input circuit through the primary side, and obtain the input pulse current through the secondary side.

[0016] The first resistor, the second resistor and the first capacitor are configured to obtain the response pulse voltage according to the input pulse current.

[0017] Optionally, the input current control unit comprises a first high-speed comparator, a voltage division filter subunit and a first threshold subunit, the positive input end of the first comparison channel of the first high-speed comparator is connected with the first threshold subunit, the negative input end is connected with the voltage division filter subunit, and the output end is connected with the second signal generation unit;

[0018] The voltage division filter subunit is configured to obtain a response direct current voltage according to the response pulse voltage.

[0019] The first threshold subunit is configured to obtain the first threshold.

[0020] The first comparison channel of the first high-speed comparator is configured to obtain the charging control signal according to a first comparison result of the response direct current voltage and the first threshold, and send the charging control signal to the second signal generation unit.

[0021] Optionally, the input current control unit further comprises a second threshold subunit and a charging voltage control subunit, the positive input end of the second comparison channel of the first high-speed comparator is connected with the second threshold subunit, the negative input end receives a charging output voltage, the output end is connected with the charging voltage control subunit, the second threshold subunit is connected with the first threshold subunit, and the charging voltage control subunit is connected with the third end of the control chip.

[0022] The second threshold subunit is configured to obtain a second threshold according to the first threshold.

[0023] The second comparison channel of the first high-speed comparator is configured to obtain an output control signal according to a second comparison result of the charging output voltage and the second threshold, the output control signal is used to control the charging voltage control subunit to output a current adjustment signal, and the current adjustment signal is used to enable the control chip to adjust the output current through the PSR circuit.

[0024] The charging voltage control subunit is configured to output the current adjustment signal according to the output control signal.

[0025] Optionally, the output collection unit comprises a third resistor and a second capacitor, and the third resistor and the second capacitor are connected in series at the output end of the PSR circuit.

[0026] Optionally, the output control unit comprises a second high-speed comparator, a first voltage division subunit and a third threshold subunit, the positive input end of the first comparison channel of the second high-speed comparator is connected with the third threshold subunit, the negative input end is connected with the first voltage division subunit, the output end is connected with the second signal generation unit, and the first voltage division subunit is connected with the output collection unit.

[0027] The first voltage dividing sub-unit is configured to divide the output voltage to obtain an output voltage division;

[0028] The third threshold sub-unit is configured to obtain a third threshold value;

[0029] The first comparison path of the second high-speed comparator is configured to obtain the charging control signal according to a comparison result of the output voltage division and the third threshold value, and output the charging control signal to the second signal generation unit.

[0030] Optionally, the output control unit further comprises a second voltage dividing sub-unit and a fourth threshold sub-unit, a positive input end of a second comparison path of the second high-speed comparator is connected with the fourth threshold sub-unit, a negative input end is connected with the second voltage dividing sub-unit, and an output end is connected with the second signal generation unit, the second voltage dividing sub-unit is connected with the output collecting unit, and the fourth threshold sub-unit is connected with the third threshold sub-unit.

[0031] The second voltage dividing sub-unit is configured to divide a voltage corresponding to the output current to obtain an output current division;

[0032] The fourth threshold sub-unit is configured to obtain a fourth threshold value according to the third threshold value;

[0033] The second comparison path of the second high-speed comparator is configured to obtain the charging control signal according to a comparison result of the output current division and the fourth threshold value, and output the charging control signal to the second signal generation unit.

[0034] In a second aspect, the present application provides a direct-current-direct-current charging device, comprising the charging protection circuit, the input circuit and the PSR circuit according to any one of the first aspect.

[0035] The input circuit is connected with the PSR circuit through the charging protection circuit, and the PSR circuit is connected with a load.

[0036] In a third aspect, the present application provides a charging system, comprising the direct-current-direct-current charging device and an alternating-current-direct-current charging device according to the second aspect.

[0037] The alternating-current-direct-current charging device is connected with the input circuit in the direct-current-direct-current charging device.

[0038] The alternating-current-direct-current charging device is configured to obtain alternating current and convert the alternating current into first direct current to deliver to the input circuit.

[0039] The direct-current-direct-current charging device is configured to receive the first direct current, convert the first direct current into second direct current according to the PSR circuit, and charge the load.

[0040] The charging protection circuit, the charging device and the system provided by the application comprise an input current sampling unit, a first signal generating unit, an input current control unit and a second signal generating unit. The input current sampling unit is connected between an input circuit and a PSR circuit. The input current sampling unit is connected with the first signal generating unit and the input current control unit. The input current control unit is connected with the second signal generating unit. The first signal generating unit and the second signal generating unit are connected with a control chip in the PSR circuit. The input pulse current input by the input circuit into the PSR circuit is detected pulse by pulse. When the input pulse current increases, the pulse duty cycle of the PSR circuit is adjusted to adjust the input current. When the input pulse current is large, the PSR circuit is controlled to turn off a preset number of pulses, so that the output current is rapidly reduced and the charging is not stopped. When the input pulse current is larger, the output of the PSR circuit is turned off and the charging is stopped, so that overcurrent charging is avoided and the charging safety is improved. After a preset time, the charging is restarted by soft start, so that the time of stopping charging is short. After the large peak current ends, the charging is restarted, so that the charging and supplying efficiency is improved. BRIEF DESCRIPTION OF DRAWINGS

[0041] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the drawings needed to be used in the embodiments or the prior art description will be briefly introduced. Obviously, the drawings in the following description are some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative labor.

[0042] Figure 1 The structural block diagram of the charging protection circuit provided by an embodiment of the present application is shown in the figure.

[0043] Figure 2 The structural block diagram of the charging protection circuit provided by another embodiment of the present application is shown in the figure.

[0044] Figure 3 The partial circuit schematic diagram of the charging protection circuit provided by an embodiment of the present application is shown in the figure.

[0045] Figure 4 The partial circuit schematic diagram of the charging protection circuit provided by another embodiment of the present application is shown in the figure.

[0046] Figure 5 The structural block diagram of the direct-current-direct-current charging device provided by an embodiment of the present application is shown in the figure.

[0047] Figure 6 The structural schematic diagram of the charging system provided by an embodiment of the present application is shown in the figure. DETAILED DESCRIPTION

[0048] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions in the embodiments of this application are described clearly and completely below. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments in this application, all other embodiments obtained by those skilled in the art without creative effort are also within the scope of protection of this application.

[0049] When charging an electric vehicle, the PSR circuit, under the control of control chips such as UCC28950, UCC28951, and NCP1399, adjusts the pulse duty cycle according to the electric vehicle's rated charging voltage and rated charging current to convert the input DC voltage into DC power suitable for charging the electric vehicle. However, during the charging process, faults may occur in the charging circuit, such as short circuits or component damage, leading to excessively high peak currents and affecting charging safety.

[0050] Therefore, to solve the technical problems existing in the prior art, this application proposes a charging protection circuit, charging device, and system. Since the control chip in the PSR circuit realizes DC-DC conversion by controlling the pulse duty cycle of the full-bridge module in the PSR circuit, and controls the output current and output voltage of the PSR circuit, this application acquires the current of the input pulsed DC power pulse by pulse, and uses the acquired current as a feedback signal to drive the control chip to adjust the pulse duty cycle, thereby controlling the peak current of the input DC power and realizing direct control of the current. This can improve the responsiveness and efficiency of current control, improve charging efficiency, and reduce safety hazards.

[0051] Figure 1 This is a structural block diagram of a charging protection circuit provided in one embodiment of this application. Figure 1 As shown, the charging protection circuit 100 includes: an input current sampling unit 110, a first signal generation unit 120, an input current control unit 130, and a second signal generation unit 140; wherein, the input current sampling unit 110 is connected between the input circuit 200 and the PSR circuit 300, the input current sampling unit 110 is connected to the first signal generation unit 120 and the input current control unit 130, the input current control unit 130 is connected to the second signal generation unit 140, and the first signal generation unit 120 and the second signal generation unit 140 are connected to the control chip in the PSR circuit 300;

[0052] The input current sampling unit 110 is used to collect the input pulse current input from the input circuit 200 to the PSR circuit 300, and obtain the corresponding response pulse voltage CS1 based on the input pulse current;

[0053] The first signal generation unit 120 is configured to obtain a first control signal CS according to the response pulse voltage CS1, and send the first control signal CS to a first end of the control chip, so that the control chip adjusts the pulse of the PSR circuit 300 according to the first control signal CS.

[0054] The input current control unit 130 is configured to obtain a response direct current voltage CSH according to the response pulse voltage CS1, and obtain a charging control signal OF according to a first comparison result of the response direct current voltage CSH and a first threshold value CSH1, the charging control signal OF being used to control the second signal generation unit 140 to output a second control signal.

[0055] The second signal generation unit 140 is configured to output the second control signal to a second end of the control chip according to the charging control signal OF, so that the control chip controls the charging state according to the second control signal, the charging state including charging and stopping charging.

[0056] In the embodiment, the input circuit 200 is configured to deliver the pulse direct current, and the input circuit 200 can be connected with other charging devices, for example, an alternating current-direct current charging device, to deliver the direct current output by the alternating current-direct current charging device to the PSR circuit 300, and the voltage of the pulse direct current is generally 440V.

[0057] The PSR circuit 300 is a phase-shifted resonant full-bridge circuit, and includes a control chip, a full-bridge module, a main transformer, a rectifier module and the like, the control chip is configured to control the on-off of active switches in the full-bridge module according to the rated charging voltage and the rated charging current of the electric vehicle battery, to adjust the pulse duty cycle, so as to adjust the output voltage and the output current, so that the output voltage and the output current are matched with the battery.

[0058] The specific structure and working process of the input circuit 200 and the PSR circuit 300 can refer to the prior art, and will not be described here.

[0059] The working principle of the charging protection circuit 100 provided in the embodiment is as follows:

[0060] When a short circuit, component damage or other fault occurs in the charging circuit, the pulse current input from the input circuit 200 to the PSR circuit 300 will suddenly increase, resulting in a large peak current. Since the input current sampling unit 110 is connected between the input circuit 200 and the PSR circuit 300, and is configured to sample the pulse current, when the pulse current increases, the input pulse current sampled by the input current sampling unit 110 also increases, so that the corresponding response pulse voltage CS1 also increases. Since the current is a pulse current, the input current sampling unit 110 samples the pulse current pulse by pulse, and the input pulse current and the response pulse voltage CS1 obtained are also pulse currents.

[0061] After obtaining the response pulse voltage CS1, the first signal generation unit 120 obtains the first control signal CS according to the response pulse voltage CS1. Since the response pulse voltage CS1 is pulse type, the first control signal CS is also pulse type. The amplitude of the first control signal CS is positively correlated with the pulse current, so when the pulse current increases, the amplitude of the first control signal CS also increases.

[0062] The first control signal CS is input to the first end of the control chip, that is, the CS end of the control chip. The CS end of the control chip is a pulse current control end. After the CS end of the control chip receives the first control signal CS, the amplitude of the first control signal CS is used to control the pulse duty cycle of the PSR circuit 300, thereby adjusting the input current.

[0063] When the amplitude of the first control signal CS is less than 2V, it means that the output current of the PSR circuit 300 matches the rated charging current. When the amplitude of the first control signal CS is greater than 2V and less than 2.5V, it means that the pulse current is large at this time, so the control chip reduces the duty cycle to reduce the output current. When the amplitude of the first control signal CS is greater than 2.5V, it means that the pulse current is further increased, so the control chip controls the PSR circuit 300 to turn off a preset number of pulses, so that the output current is quickly reduced and the charging is not stopped, which can reduce the impact on the charging efficiency as much as possible on the basis of avoiding safety accidents caused by excessive current.

[0064] When the first signal generation unit 120 obtains the first control signal CS according to the response pulse voltage CS1, so that the control chip adjusts the output current by adjusting the duty cycle, the input current control unit 130 obtains the response DC voltage CSH according to the response pulse voltage CS1. The response DC voltage CSH is a continuous DC voltage. The input current control unit 130 compares the response DC voltage CSH with the first threshold CSH1, and obtains the charging control signal OF according to the first comparison result. The charging control signal OF is a pulse signal, and the high and low of the charging control signal OF is determined by the first comparison result. When the response DC voltage CSH is greater than the first threshold CSH1, the charging control signal OF is low.

[0065] The second signal generating unit 140 generates a second control signal SS according to a charging control signal OF, wherein the second control signal SS is at a low level when the charging control signal OF is at a low level, and the second control signal SS is transmitted to a second end, i.e., an SS end, of the control chip. The SS end of the control chip is an output off and soft start end of the PSR circuit 300, and thus the charging state can be controlled through the second control signal SS. When the pulsed current is large, i.e., the peak current is large, the output current will be large, and at this time, the second control signal SS is at a low level, and the charging needs to be stopped. Therefore, in the embodiment, the output of the PSR circuit 300 is turned off through the control chip to stop the charging, avoid high-current charging, and improve the charging safety. Moreover, after a preset time length (for example, 10 seconds), the charging is restarted through soft start, the time for stopping the charging is avoided to be long, the charging can be restarted after the large peak current ends, and the charging and power supply efficiency is improved.

[0066] In the charging circuit, when the line between the charging device and the battery fails, for example, overcurrent and overvoltage, the charging process is affected, and thus the output voltage and / or the output current need to be collected, and the charging state is controlled according to the output voltage and / or the output current.

[0067] Therefore, as shown in Figure 2 the charging protection circuit 100 further includes an output collecting unit 150 and an output control unit 160. The output collecting unit 150 is connected with the PSR circuit 300, and the output collecting unit 150 is connected with the output control unit 160. The output control unit 160 is connected with the second signal generating unit 140.

[0068] The output collecting unit 150 is configured to obtain the output voltage and / or the output current of the PSR circuit 300.

[0069] The output control unit 160 is configured to obtain a charging control signal OF according to the output voltage and / or the output current, and transmit the charging control signal OF to the second signal generating unit 140.

[0070] In the embodiment, the output voltage and the output current of the PSR circuit 300 are used to charge the electric vehicle, and thus the output collecting unit 150 is connected at the output end of the PSR to collect the output voltage and the output current of the PSR circuit 300. As shown in Figure 3 the output collecting unit 150 includes a third resistor R3 and a second capacitor C2. The third resistor R3 and the second capacitor C2 are connected in series at the output end of the PSR circuit 300, and the output voltage and the output current are collected and detected through the third resistor R3 and the second capacitor C2.

[0071] Then, the output control unit 160 judges the output voltage and judges the output current, obtains the charging control signal OF, and sends the charging control signal OF to the second signal generation unit 140, so that the second signal generation unit 140 generates the second control signal SS according to the charging control signal OF sent by the output control unit 160, realizes the control of whether the PSR circuit 300 is turned off, and thus realizes the control of the charging state according to the output voltage and / or the output current.

[0072] Optionally, as shown in Figure 3 The input current sampling unit 110 includes a current sensor CT, a first resistor R1, a second resistor R2 and a first capacitor C1, the second resistor R2 and the first capacitor C1 are connected in parallel and then connected with the first resistor R1, the original side of the current sensor CT is connected between the input circuit 200 and the PSR circuit 300, the secondary side is connected with the first resistor R1, and the second resistor R2 and the first capacitor C1 connected in parallel are connected in parallel with the first signal generation unit 120;

[0073] The current sensor CT is used to collect the current input by the input circuit 200 through the original side, and obtain the input pulse current through the secondary side;

[0074] The first resistor R1, the second resistor R2 and the first capacitor C1 are used to obtain the response pulse voltage CS1 according to the input pulse current.

[0075] In this embodiment, the original side of the current sensor CT is connected between the input circuit 200 and the PSR circuit 300, and the pulse current is collected pulse by pulse, and the secondary side obtains the input pulse current through the pulse current, so when the pulse current changes, the input pulse current also changes.

[0076] As shown in Figure 3 When the input pulse current flows through the first resistor R1, the second resistor R2 and the first capacitor C1, a voltage is generated on the first resistor R1 and the second resistor R2, and the abnormal interference is eliminated through the first capacitor C1, and there is a response pulse voltage CS1 between the first resistor R1 and the second resistor R2, so as to realize the purpose of obtaining the response pulse voltage CS1 through the pulse current, and due to the filtering of the first capacitor C1, the interference in the response pulse voltage CS1 is eliminated, which makes it more corresponding to the pulse in the input circuit 200, thereby improving the control accuracy of the peak current in the pulse current, and reducing the peak current in time when the peak current is large.

[0077] Optionally, as shown in Figure 4As shown, the input current control unit 130 comprises a first high-speed comparator U1, a voltage division and filtering subunit 131, and a first threshold subunit 132. The positive input end of the first comparison channel of the first high-speed comparator U1 is connected with the first threshold subunit 132, the negative input end is connected with the voltage division and filtering subunit 131, and the output end is connected with the second signal generation unit 140.

[0078] The voltage division and filtering subunit 131 is configured to obtain a response DC voltage CSH according to the response pulse voltage CS1.

[0079] The first threshold subunit 132 is configured to obtain a first threshold CSH1.

[0080] The first comparison channel of the first high-speed comparator U1 is configured to obtain a charging control signal OF according to the first comparison result of the response DC voltage CSH and the first threshold CSH1, and send the charging control signal OF to the second signal generation unit 140.

[0081] In the embodiment, as shown in Figure 4 The voltage division and filtering subunit 131 comprises a fourth resistor R4, a fifth resistor R5, and a third capacitor C3. The fourth resistor R4 and the fifth resistor R5 are connected in parallel, and the fifth resistor R5 and the third capacitor C3 are connected in series. The fourth resistor R4, the fifth resistor R5, and the third capacitor C3 perform voltage division and filtering on the response pulse voltage CS1 to obtain the response DC voltage CSH, and deliver the response DC voltage CSH to the negative input end of the first comparison channel of the first high-speed comparator U1.

[0082] The first threshold subunit 132 comprises a sixth resistor R6 and a seventh resistor R7. The sixth resistor R6 and the seventh resistor R7 are connected in series to divide a voltage of 15V to obtain the first threshold CSH1, and input the first threshold CSH1 to the positive input end of the first comparison channel of the first high-speed comparator U1. The voltage of 15V can be provided by the first high-speed comparator U1.

[0083] The first comparison channel of the first high-speed comparator U1 compares the response DC voltage CSH and the first threshold CSH1, and obtains the charging control signal OF according to the first comparison result, so that the second signal generation unit 140 obtains the charging control signal OF.

[0084] The structure of the second signal generation unit 140 is as shown in Figure 4As shown, when the charging circuit has a short circuit, component damage and other faults, resulting in excessive peak current, the response DC voltage CSH is greater than the first threshold CSH1. At this time, the charging control signal OF is low, thereby controlling the NMOS transistor M1 to turn on through the monostable trigger U3, thereby outputting the low-level second control signal SS, so that the control chip turns off the PSR circuit 300 and stops charging. After 10s, the soft start is restarted for the electric vehicle charging.

[0085] In the charging circuit, when the line between the charging device and the battery fails, for example, short circuit, under-voltage, or when starting charging, due to the influence of the electrolytic capacitor in the charging circuit, the output current is too large, the charging output voltage VOL is low, and the over-current charging is easy to cause safety accidents. Therefore, the input current into the electric vehicle battery needs to be controlled according to the charging output voltage VOL.

[0086] Therefore, optionally, as shown in Figure 4 As shown, the input current control unit 130 further includes a second threshold subunit 133 and a charging voltage control subunit 134. The positive input end of the second comparison path of the first high-speed comparator U1 is connected with the second threshold subunit 133, the negative input end receives the charging output voltage VOL, and the output end is connected with the charging voltage control subunit 134. The second threshold subunit 133 is connected with the first threshold subunit 132, and the charging voltage control subunit 134 is connected with the third end of the control chip;

[0087] The second threshold subunit 133 is configured to obtain a second threshold VOL1 according to the first threshold CSH1.

[0088] The second comparison path of the first high-speed comparator U1 is configured to obtain an output control signal according to the second comparison result of the charging output voltage VOL and the second threshold VOL1. The output control signal is used to control the charging voltage control subunit 134 to output a current adjustment signal. The current adjustment signal is used to make the control chip adjust the output current through the PSR circuit 300.

[0089] The charging voltage control subunit 134 is configured to output the current adjustment signal according to the output control signal.

[0090] In this embodiment, the second threshold subunit 133 includes an eighth resistor R8 and a ninth resistor R9. The eighth resistor R8 and the ninth resistor R9 are connected in series between the positive input end of the first comparison path of the first high-speed comparator U1 and the ground, thereby dividing the voltage of the first threshold CSH1. It can also be said that the sixth resistor R6 and the seventh resistor R7 are combined to divide the voltage of 15V, thereby obtaining the second threshold VOL1 and inputting it to the positive input end of the second comparison path of the first high-speed comparator U1. Among them, the second threshold VOL1 is the voltage corresponding to the charging output voltage VOL of 100V.

[0091] The acquisition method of the charging output voltage VOL can refer to the prior art, which will not be described here. After the charging output voltage VOL is acquired, the charging output voltage VOL is input to the negative input end of the second comparison path of the first high-speed comparator U1.

[0092] The second comparison path of the first high-speed comparator U1 compares the charging output voltage VOL and the second threshold VOL1. When a short circuit or other failure occurs between the charging device and the battery, or when the charging is just started, the charging output voltage VOL is less than the second threshold VOL1. At this time, the second comparison path of the first high-speed comparator U1 outputs a low-level output control signal to the charging voltage control subunit 134.

[0093] The charging voltage control subunit 134 includes an NMOS tube M2 and a first diode D1 connected to the third end of the control chip, wherein the third end of the control chip is an output voltage and output current control end. When the gate of the NMOS tube M2 receives a low-level output control signal, the NMOS tube M2 is turned on, thereby obtaining a low-level current adjustment signal. At this time, the current adjustment signal is pulled down to 0.25V by the first diode D1.

[0094] In the prior art, the MCU corresponding to the charging device acquires the rated charging voltage and the rated charging current of the battery of the electric vehicle, and then controls the charging device according to the rated charging voltage and the rated charging current, so that the output voltage and the output current of the PSR circuit 300 are respectively the rated charging voltage and the rated charging current, that is, the MCU sets the corresponding relationship between the rated charging current and the current voltage IOC, wherein IOC is used to control the output current. For example, when the rated charging current acquired by the MCU is 15A, that is, the output current is 15A, by setting the corresponding voltage IOC to 2.5V, setting IOC to 2.5V can make the output current be the rated charging current 15A; setting IOC to 1.25V can make the output current be 7.5A.

[0095] The MCU sets the correspondence between the rated charging current and the IOC, and adjusts the output current through the IOC. In fact, after determining the IOC according to the rated charging current, the current adjustment signal is also determined according to the correspondence between the IOC and the current adjustment signal, that is, the current adjustment signal changes with the IOC. That is, when the IOC is set to 2.5V, the current adjustment signal is 2.5V; when the IOC is set to 1.25V, the current adjustment signal is 1.25V. However, in the present application, when a short circuit fault occurs between the charging device and the battery, or when the charging is just started, the current adjustment signal is pulled down to 0.25V by the first diode D1. At this time, the IOC should be set to 2.5V according to the rated charging current, so at this time, the current adjustment signal does not keep consistent with the IOC, and the output current is adjusted according to the current adjustment signal. Therefore, when the current adjustment signal is pulled down to 0.25V by the first diode D1, the output current is 1.5A.

[0096] Therefore, in the embodiment, the second threshold subunit 133 and the charging voltage control subunit 134 are arranged to reduce the output current when the charging output voltage VOL is less than the second threshold VOL1, avoid low-voltage high-current charging, and realize small-current starting to improve charging safety.

[0097] Optionally, as shown in Figure 4 The output control unit 160 includes a second high-speed comparator U2, a first voltage division subunit 161, and a third threshold subunit 162. The positive input end of the first comparison path of the second high-speed comparator is connected with the third threshold subunit 162, the negative input end is connected with the first voltage division subunit 161, the output end is connected with the second signal generation unit 140, and the first voltage division subunit 161 is connected with the output collection unit 150.

[0098] The first voltage division subunit 161 is configured to divide the output voltage to obtain an output voltage division OUT-U.

[0099] The third threshold subunit 162 is configured to obtain a third threshold OUT-U1.

[0100] The first comparison path of the second high-speed comparator U2 is configured to obtain and output a charging control signal OF to the second signal generation unit 140 according to the comparison result of the output voltage division OUT-U and the third threshold OUT-U1.

[0101] In the embodiment, the first voltage division subunit 161 includes a tenth resistor R10, an eleventh resistor R11, and a twelfth resistor R12 connected in series. The negative input end of the first comparison path of the second high-speed comparator U2 is connected between the eleventh resistor R11 and the twelfth resistor R12, and is configured to obtain the output voltage division OUT-U.

[0102] The structure and working principle of the third threshold subunit 162 can refer to the first threshold subunit 132, which will not be described here. The third threshold OUT-U1 is obtained by the third threshold subunit 162 and input to the positive input end of the first comparison path of the second high-speed comparator U2.

[0103] The first comparison path of the second high-speed comparator U2 compares the output voltage division OUT-U and the third threshold OUT-U1. When an overvoltage fault occurs, it means that the output voltage is too high, so that the output voltage division OUT-U is greater than the third threshold OUT-U1. At this time, the output end of the first comparison path of the second high-speed comparator U2 outputs a low-level charging control signal OF, so that the second signal generation unit 140 outputs a low-level second control signal SS, so that the control chip closes the PSR circuit 300 and stops charging. After 10s, it is restarted to charge the electric vehicle, so as to realize the soft start after 10s of suspension of charging when overvoltage occurs. It can not only avoid the damage to the battery caused by overvoltage charging, but also can guarantee the charging efficiency.

[0104] Optionally, as shown in Figure 4 The output control unit 160 further includes a second voltage division subunit 163 and a fourth threshold subunit 164. The positive input end of the second comparison path of the second high-speed comparator U2 is connected with the fourth threshold subunit 164, the negative input end is connected with the second voltage division subunit 163, the output end is connected with the second signal generation unit 140, the second voltage division subunit 163 is connected with the output collection unit 150, and the fourth threshold subunit 164 is connected with the third threshold subunit 162.

[0105] The second voltage division subunit 163 is configured to divide the voltage corresponding to the output current to obtain an output current division OUT-I.

[0106] The fourth threshold subunit 164 is configured to obtain a fourth threshold OUT-I1 according to the third threshold OUT-U1.

[0107] The second comparison path of the second high-speed comparator U2 is configured to obtain and output a charging control signal OF to the second signal generation unit 140 according to the comparison result of the output current division OUT-I and the fourth threshold OUT-I1.

[0108] In the embodiment, the second voltage division subunit 163 includes a thirteenth resistor R13, a fourteenth resistor R14 and a fourth capacitor C4. The thirteenth resistor R13 and the fourteenth resistor R14 are connected in series to divide the voltage corresponding to the output current to obtain the output current division OUT-I. The fourth capacitor is configured to filter to obtain a stable output current division. The second voltage division subunit 163 delivers the output current division OUT-I to the negative input end of the second comparison path of the second high-speed comparator U2.

[0109] The structure and working principle of the fourth threshold subunit 164 can refer to the second threshold subunit 133, which will not be described here.

[0110] The second comparison path of the second high-speed comparator U2 compares the output current voltage division OUT-I and the fourth threshold OUT-I1. When a short circuit, overcurrent, or other fault occurs, the output current is large, so that the output current voltage division OUT-I is greater than the fourth threshold OUT-I1. At this time, the output end of the second comparison path of the second high-speed comparator U2 outputs a low-level charging control signal OF, so that the second signal generation unit 140 outputs a low-level second control signal SS, so that the control chip closes the PSR circuit 300 and stops charging. After 10s, the soft start is restarted for the electric vehicle charging, so as to realize the soft start after 10s of suspension of charging when overcurrent occurs. This can not only avoid the damage to the battery caused by overcurrent charging, but also can guarantee the charging efficiency.

[0111] Figure 5 The structure block diagram of the direct-current-direct-current charging device provided by an embodiment of the present application is shown in the figure. Figure 5 As shown in the figure, the direct-current-direct-current charging device 1000 includes a charging protection circuit 100, an input circuit 200, and a PSR circuit 300.

[0112] The input circuit 200 is connected with the PSR circuit 300 through the charging protection circuit 100, and the PSR circuit 300 is connected with the load.

[0113] The input circuit 200 is used to provide a first direct current, for example, 440V direct current.

[0114] In the embodiment, the structure and working principle of the charging protection circuit 100 can refer to any of the above embodiments, which will not be described here.

[0115] Figure 6 The structure schematic diagram of the charging system provided by an embodiment of the present application is shown in the figure. Figure 6 As shown in the figure, the charging system includes a direct-current-direct-current charging device 1000 and an alternating-current-direct-current charging device 2000.

[0116] The alternating-current-direct-current charging device is connected with the input circuit 200 in the direct-current-direct-current charging device.

[0117] The alternating-current-direct-current charging device is used to obtain alternating current and convert the alternating current into a first direct current to be delivered to the input circuit 200.

[0118] The DC-DC charging device is used for receiving first DC power, converting the first DC power into second DC power according to the PSR circuit 300, and charging the load.

[0119] It should be noted that the AC-DC charging device 2000 can be a charging device with multiple household power connection ends, so that multiple household power connections can be simultaneously connected to improve the charging power.

[0120] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present application, and are not limited thereto; although the present application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that; it can still modify the technical solutions recorded in the foregoing embodiments, or make equivalent replacement for part or all of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present application.

Claims

1. A charging protection circuit, characterized in that, include: The system comprises an input current sampling unit, a first signal generation unit, an input current control unit, and a second signal generation unit; wherein the input current sampling unit is connected between the input circuit and the PSR circuit, the input current sampling unit is connected to the first signal generation unit and the input current control unit, the input current control unit is connected to the second signal generation unit, and the first signal generation unit and the second signal generation unit are connected to the control chip in the PSR circuit. The input current sampling unit is used to collect the input pulse current input from the input circuit to the PSR circuit, and obtain the corresponding response pulse voltage based on the input pulse current; The first signal generation unit is configured to obtain a first control signal based on the response pulse voltage and send the first control signal to a first terminal of the control chip, so that the control chip adjusts the pulse of the PSR circuit according to the first control signal; The input current control unit is used to obtain a response DC voltage based on the response pulse voltage, and to obtain a charging control signal based on a first comparison result between the response DC voltage and a first threshold. The charging control signal is used to control the second signal generation unit to output a second control signal. The second signal generation unit is used to output the second control signal to the second terminal of the control chip according to the charging control signal, so that the control chip controls the charging state according to the second control signal, the charging state including: charging and stopping charging; It also includes: an output acquisition unit and an output control unit, wherein the output acquisition unit is connected to the PSR circuit, the output acquisition unit is connected to the output control unit, and the output control unit is connected to the second signal generation unit; The output acquisition unit is used to obtain the output voltage and / or output current of the PSR circuit; The output control unit is configured to obtain the charging control signal based on the output voltage and / or output current, and send the charging control signal to the second signal generation unit; The input current control unit includes: a first high-speed comparator, a voltage divider filter subunit, and a first threshold subunit. The positive input terminal of the first comparison path of the first high-speed comparator is connected to the first threshold subunit, the negative input terminal is connected to the voltage divider filter subunit, and the output terminal is connected to the second signal generation unit. The voltage divider filter subunit is used to obtain the response DC voltage based on the response pulse voltage; The first threshold subunit is used to obtain the first threshold. The first comparison path of the first high-speed comparator is used to obtain the charging control signal based on the first comparison result between the response DC voltage and the first threshold, and send the charging control signal to the second signal generation unit; The input current control unit further includes: a second threshold subunit and a charging voltage control subunit. The positive input terminal of the second comparison path of the first high-speed comparator is connected to the second threshold subunit, the negative input terminal receives the charging output voltage, and the output terminal is connected to the charging voltage control subunit. The second threshold subunit is connected to the first threshold subunit, and the charging voltage control subunit is connected to the third terminal of the control chip. The second threshold subunit is used to obtain a second threshold based on the first threshold; The second comparison path of the first high-speed comparator is used to obtain an output control signal based on the second comparison result of the charging output voltage and the second threshold. The output control signal is used to control the charging voltage control subunit to output a current adjustment signal. The current adjustment signal is used to enable the control chip to adjust the output current through the PSR circuit. The charging voltage control subunit is used to output the current adjustment signal according to the output control signal.

2. The charging protection circuit according to claim 1, characterized in that, The input current sampling unit includes: a current sensor, a first resistor, a second resistor, and a first capacitor. The second resistor and the first capacitor are connected in parallel and then connected to the first resistor. The primary side of the current sensor is connected between the input circuit and the PSR circuit, and the secondary side is connected to the first resistor. The second resistor and the first capacitor are connected in parallel and then connected in parallel to the first signal generation unit. The current sensor is used to acquire the current input to the input circuit through the primary side and to obtain the input pulse current through the secondary side; The first resistor, the second resistor, and the first capacitor are used to obtain the response pulse voltage based on the input pulse current.

3. The charging protection circuit according to claim 1, characterized in that, The output acquisition unit includes a third resistor and a second capacitor, which are connected in series at the output terminal of the PSR circuit.

4. The charging protection circuit according to claim 1, characterized in that, The output control unit includes: a second high-speed comparator, a first voltage divider subunit, and a third threshold subunit. The positive input terminal of the first comparison path of the second high-speed comparator is connected to the third threshold subunit, the negative input terminal is connected to the first voltage divider subunit, and the output terminal is connected to the second signal generation unit. The first voltage divider subunit is connected to the output acquisition unit. The first voltage divider subunit is used to divide the output voltage to obtain a voltage divider output voltage; The third threshold subunit is used to obtain the third threshold. The first comparison path of the second high-speed comparator is used to obtain and output the charging control signal to the second signal generation unit based on the comparison result of the output voltage division and the third threshold.

5. The charging protection circuit according to claim 4, characterized in that, The output control unit further includes: a second voltage divider subunit and a fourth threshold subunit, wherein the positive input terminal of the second comparison path of the second high-speed comparator is connected to the fourth threshold subunit, the negative input terminal is connected to the second voltage divider subunit, the output terminal is connected to the second signal generation unit, the second voltage divider subunit is connected to the output acquisition unit, and the fourth threshold subunit is connected to the third threshold subunit; The second voltage divider unit is used to divide the voltage corresponding to the output current to obtain the output current voltage divider; The fourth threshold subunit is used to obtain the fourth threshold based on the third threshold; The second comparison path of the second high-speed comparator is used to obtain and output the charging control signal to the second signal generation unit based on the comparison result of the output current voltage division and the fourth threshold.

6. A DC-DC charging device, characterized in that, include: Input circuit, PSR circuit, and charging protection circuit as described in any one of claims 1-5; The input circuit is connected to the PSR circuit through the charging protection circuit, and the PSR circuit is connected to the load.

7. A charging system, characterized in that, include: AC-DC charging equipment and DC-DC charging equipment as described in claim 6; The AC-DC charging device is connected to the input circuit in the DC-DC charging device; The AC-DC charging device is used to acquire AC power and convert the AC power into a first DC power to be delivered to the input circuit; The DC-DC charging device is used to receive the first DC power and convert the first DC power into a second DC power according to the PSR circuit to charge the load.

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