[0020] Embodiment one:
[0021] figure 1 The structure of the protection circuit of the wireless charging device provided by Embodiment 1 of the present invention is shown. For the convenience of description, only the parts related to the embodiment of the present invention are shown. The details are as follows:
[0022] see figure 1 , a protection circuit 100 for a wireless charging device provided in an embodiment of the present invention is used for connecting with a wireless power receiving module of the wireless charging device. The above wireless charging device includes a wireless power sending module 200 and a wireless power receiving module 300, the wireless power sending module 200 includes a first control module 210 and a power supply module 220, the wireless power receiving module 300 includes a second control module 310 and a receiving module 320, receiving The output end of the module 320 is connected to the load (battery pack), and the first control module 210 is connected to the second control module 220 in communication.
[0023] The protection circuit 100 includes a voltage comparison module 110 , a switch module 120 and a thyristor freewheeling module 130 .
[0024] The input terminal of the voltage comparison module 110 is used to connect with the voltage output terminal of the receiving module 320, the control terminal of the switch module 120 is connected with the output terminal of the voltage comparison module 110, and the input terminal of the thyristor freewheeling module 130 is connected with the output terminal of the switch module 120 The terminal is connected, and the output terminal of the thyristor freewheeling module 130 is used to connect with the voltage output terminal of the receiving module 320 .
[0025] When there is an abnormal overvoltage, the voltage comparison module 110 outputs a turn-on signal to the switch module 120, and the switch module 120 is turned on, so that the thyristor freewheeling module 130 is turned on; when the thyristor freewheeling module 130 is turned on, The voltage of the voltage output terminal of the receiving module 320 drops, and the second control module 310 loses power and stops working, so that the communication between the second control module 310 and the first control module 210 is interrupted; when the first control module 210 detects that the first control module 210 When the communication with the second control module 310 is interrupted, an instruction to stop power supply is output to the power supply module 220 so that the power supply module 220 stops working.
[0026] In a specific application, the above-mentioned first control module 210 and second control module 310 may realize the communication connection through infrared wireless communication, or realize the communication connection through Bluetooth, which is not limited here.
[0027] In a specific application, the above-mentioned power supply module 220 transmits electric energy to the above-mentioned receiving module 320 through resonant electromagnetic induction, and the voltage output terminal of the receiving module 320 outputs a voltage to the load (battery pack) to charge the battery pack.
[0028] In a specific application, the above-mentioned overvoltage abnormality includes the open circuit of the wireless power receiving module under abnormal conditions (load open circuit), the abnormal overvoltage caused by the load becoming smaller due to poor contact, and the output voltage of the voltage output terminal of the receiving module caused by other reasons. Elevated exceptions are not limited here. It should be noted that since the wireless power receiving module works in a constant current state, when its load is open or in poor contact, the output voltage VDD of the voltage output terminal of the receiving module will increase, that is, there is an overvoltage abnormality.
[0029] In a specific application, the second control module 310 of the wireless power receiving module 300 is a working power source obtained by converting the output voltage VDD of the voltage output terminal of the receiving module 320 through a power conversion circuit, and the working power source is a 5V/3.3V DC power supply.
[0030] like figure 2 As shown, as an embodiment of the present invention, figure 2 An example circuit schematic diagram of the protection circuit 100 of this embodiment is shown.
[0031] see figure 2 , as an implementation manner, the voltage comparison module 110 includes a Zener diode ZD1 and a first resistor R1.
[0032] The negative pole of the Zener diode ZD1 is used to connect to the voltage output terminal of the receiving module 320, the positive pole of the Zener diode ZD1 is connected to the first end of the first resistor R1, and the second end of the first resistor R1 is the output end of the voltage comparison module .
[0033]In one embodiment, in order to achieve more accurate overvoltage protection, the above Zener diode ZD1 is replaced with a voltage comparator with a precision reference, the level signal is output through the voltage comparator, and output at the voltage output terminal of the receiving module 320 After the output voltage VDD is divided, it is compared with a precise reference voltage, and when the output voltage VDD is greater than the reference voltage, a conduction control signal (level signal) is output to the switch module to make the switch module conduct.
[0034] In a specific application, the above-mentioned voltage comparison module includes a voltage comparator and a first resistor; the first input terminal of the voltage comparator is connected to the voltage output terminal of the receiving module, the second input terminal of the voltage comparator inputs a reference voltage, and the voltage comparator The output terminal of the first resistor is connected to the first terminal of the first resistor, and the second terminal of the first resistor is the output terminal of the voltage comparison module.
[0035] As an implementation manner, the switch module 120 includes a second resistor R2, a first switch tube Q1, a third resistor R3, a fourth resistor R4, a second switch tube Q2, and a fifth resistor R5.
[0036] The first end of the second resistor R2 is the control end of the switch module, the second end of the second resistor R2 is grounded, the first end of the first switching tube Q1 is connected to the first end of the second resistor R2, and the first switching tube Q1 The second end of the third resistor R3 is connected to the first end of the third resistor R3, the third end of the first switch tube Q1 is grounded, the second end of the third resistor R3 is connected to the DC power supply, the first end of the fourth resistor R4 is connected to the third The first terminal of the resistor R3 is connected, the second terminal of the fourth resistor R4 is connected to the first terminal of the second switching tube Q2, the second terminal of the second switching tube Q2 is connected to the DC power supply, and the third terminal of the second switching tube Q2 end is connected to the first end of the fifth resistor R5 , and the second end of the fifth resistor R5 is the output end of the switch module 120 .
[0037] In a specific application, the above-mentioned DC power supply is a +12V DC power supply. In a specific application, the above-mentioned +12V DC power supply is a DC power supply obtained after the output voltage VDD is converted by a power conversion circuit.
[0038] The first switch Q1 is a first NPN transistor, the base of the first NPN transistor Q1 is the first end of the first switch Q1, and the collector of the first NPN transistor Q1 is the third end of the first switch Q1 , the emitter of the first NPN transistor Q1 and the third terminal of the first switching transistor Q1.
[0039] The second switch Q2 is a second PNP transistor, the base of the second PNP transistor Q2 is the first end of the second switch Q2, and the collector of the second PNP transistor Q2 is the third end of the second switch Q2 , the emitter of the second PNP transistor Q2 and the second end of the second switching transistor Q2.
[0040] As an implementation manner, the silicon controlled freewheeling module 130 includes a silicon controlled rectifier SCR1, a first capacitor C1 and a sixth resistor R6.
[0041] The first end of the first capacitor C1 is the input end of the thyristor freewheeling module 130, the second end of the first capacitor C1 is grounded, the first end of the silicon controlled rectifier SCR1 is connected to the first end of the first capacitor C1, The second end of the silicon controlled rectifier SCR1 is grounded, the third end of the silicon controlled rectifier SCR1 is connected to the first end of the sixth resistor R6, and the second end of the sixth resistor R6 is the output end of the thyristor freewheeling module 130 .
[0042] In a specific application, the above silicon controlled rectifier SCR1 is a unidirectional silicon controlled rectifier. Since the silicon controlled rectifier SCR1 adopts the one-way silicon controlled rectifier, as long as the conduction is triggered, the conduction state can be maintained all the time, and the trigger signal does not need to exist all the time. restore the voltage output, causing hiccups.
[0043] The following combines the working principle and figure 2 Further explanation of the above overcurrent protection circuit:
[0044] When the battery pack has abnormal conditions such as poor contact and open circuit during charging, since the wireless power receiving module works in constant current mode, the open circuit (or poor contact) of the subsequent load (battery pack) will cause the voltage output of the receiving module The output voltage VDD at the terminal rises, and then the Zener diode in the voltage comparison module is turned on (or the output control level of the voltage comparator), because the Zener diode is turned on (or the output control level of the voltage comparator) will make the first The switch tube Q1 is turned on, and then the second switch tube Q2 is turned on, so that the one-way silicon controlled rectifier SCR1 is in the conduction state, and then the output voltage VDD is reduced to below 2V. Since the second control module of the wireless power receiving module provides working power through the output voltage, the second control module 310 is powered off and does not work, and the wireless communication connection with the first control module 210 is interrupted. When the first control module of the wireless power transmitting module When the module 210 detects that its communication with the second control module 310 is interrupted, the first control module 210 will control the power supply module to turn off the output of the pulse width modulation signal (Pulse Width Modulation, PWM), and then turn off the power switch of the wireless power transmission module. cut off, and then stop supplying power to the wireless power receiving module to form a closed-loop control system. The pure hardware overvoltage protection is realized through a simple protection circuit, and the protection circuit has high reliability and low cost. The protection circuit of the wireless charging device provided in this embodiment will cause the receiving The output voltage of the voltage output terminal of the module suddenly increases, so that the voltage comparison module can output a conduction signal, so that the switch module is turned on, and then the thyristor freewheeling module is turned on, so that the output of the thyristor freewheeling module The terminal is in a state of high current and low voltage, which will cause the second control module to lose power and stop working, so that the communication between the wireless power transmitting module and the wireless power receiving module will be interrupted, and when the communication interruption is detected, the wireless power transmitting module will stop supplying power , and then form a closed-loop system to effectively protect the wireless power receiving module from damage to the battery pack (load) and wireless charging equipment caused by the open circuit or overvoltage caused by a small load under abnormal conditions. The circuit is safe and reliable, simple and easy to implement, and can effectively It effectively solves the problem that the voltage of the rear stage will rise and damage the battery pack and charging equipment in the case of an open load.
