A relay switching protection circuit for digital power supply and charging control method thereof

Abstract

The present invention relates to a relay switching protection circuit for a digital power supply and a charging control method thereof. The power supply has a processor and a switching power supply topology circuit with a relay. The relay switching protection circuit includes a battery state sampling circuit and a relay protection control circuit, which are respectively connected to a rechargeable battery; the sampling circuit is connected to the processor and is used to collect the state information of the rechargeable battery according to the pulse signal generated by the digital power supply processor. The processor controls the opening of the switch tube in the relay protection control circuit through the battery state information to reduce the voltage difference between the two contacts of the relay, and then closes or disconnects the relay contacts, thereby effectively protecting the relay. The entire circuit structure is simple, safe and reliable, and has a long service life.

Description

Technical Field

[0001] The present invention relates to the technical field of digital power supply equipment, and in particular to a relay switching protection circuit for a digital power supply and a charging control method thereof. Background Art

[0002] With the continuous promotion of new energy technologies, lithium batteries have been widely used due to their advantages such as light weight, small size and fast charging compared to lead-acid batteries of the same capacity.

[0003] The popularity of lithium batteries has led to the rapid development of lithium battery chargers. How to make the charger work intelligently, safely and efficiently has become a top priority. As an efficient intelligent charger, it must include functions such as battery reverse connection protection and backflow protection. Therefore, a relay is usually added to the charger output to achieve this function to protect the safety of the charging equipment. At present, the lithium battery voltage module on the market can reach close to 60VDC. Since the charger output is connected to the battery, that is, one end of the relay contact is connected to the battery and the other end is connected to the charger main circuit output. When the charger output is plugged in and out of the rechargeable battery, there is a large voltage difference between the two contacts of the relay. When it is greater than the switching voltage specification allowed by the relay, it will cause damage to the relay, seriously affecting the charger's function and life.

[0004] However, existing charging products usually have overcurrent protection circuits and output overvoltage protection circuits, but no voltage protection measures for relays. For example, the invention patent application with publication number CN 111585157 A discloses a digital control drive power supply for mid-infrared ultrafast lasers, as described in paragraph 0060: The protection module is connected to a relay at the output end of the constant current module. When the voltage on the energy storage capacitor exceeds the specified value, the relay is energized, and then the power supply is cut off to protect the load ultrafast laser. At the same time, when the single-chip microcomputer gives no signal, the contacts are disconnected to protect the load, ensuring zero current in the initial non-working state of the circuit. At the same time, the large capacitance and delay effect of the relay itself fully avoid the current surge phenomenon, fully ensuring the safety of the circuit. This power supply mainly involves the closing or disconnection of the relay contacts when the operation is started for the relay circuit, and does not involve emergencies, such as suddenly pulling out the charging power supply, or frequently plugging and unplugging the charging. That is, the problem of voltage difference between the contacts during the aforementioned plug-in test still needs to be solved urgently. Summary of the invention

[0005] In view of this, a relay switching protection circuit for a digital power supply and a charging control method thereof are provided, which can accurately determine the access status of a battery, have a simple structure, and can reduce the voltage difference across a relay to protect the relay.

[0006] A relay switching protection circuit for a digital power supply, the digital power supply having a digital power supply processor and a switching power supply topology circuit, the switching power supply topology circuit having a relay, the relay switching protection circuit comprising a battery state sampling circuit and a relay protection control circuit, the switching power supply topology circuit, the battery state sampling circuit, and the relay protection control circuit are respectively connected to a rechargeable battery;

[0007] The battery status sampling circuit is connected to the digital power processor and is used to collect status information of the rechargeable battery according to the pulse signal generated by the digital power processor;

[0008] The relay protection control circuit includes a relay switching circuit and a relay coil control circuit. The relay switching circuit is used to reduce the voltage difference between the relay contacts to protect the relay switching contacts according to the information collected by the battery status sampling circuit. The relay switching circuit and the relay coil control circuit are respectively connected to the digital power processor and receive corresponding control signals respectively. The relay coil control circuit closes or opens the relay contacts according to the control signal of the digital power processor.

[0009] The relay switching circuit includes a ninth rectifier diode D9, a ninth switch MOS tube Q9, and an eleventh transistor Q11, wherein the substrate of the eleventh transistor Q11 is connected to the digital power processor, the emitter of the eleventh transistor Q11 is connected to the negative terminal of the charging output and to the positive terminal of the ninth rectifier diode D9, the negative terminal of the ninth rectifier diode D9 is connected to the drain of the ninth rectifier diode D9, the collector of the eleventh transistor Q11 is connected to the gate of the ninth switch MOS tube Q9 and is connected between the drain of the ninth switch MOS tube Q9 and the negative terminal of the ninth rectifier diode D9 through a resistor, the source of the ninth switch MOS tube Q9 is connected to the positive terminal of the charging output, and the ninth rectifier diode D9 is connected in series with the ninth switch MOS tube and connected in parallel with the relay to the positive terminal of the charging output;

[0010] An electrolytic capacitor E1 is connected in parallel between the positive and negative ends of the output of the switching power supply topology circuit, the positive electrode of the electrolytic capacitor E1 is connected to the positive electrode of the ninth rectifier diode D9 and the contact A of the relay, the negative electrode of the electrolytic capacitor E1 is connected to one end of at least one sampling resistor and grounded, and the other end of the sampling resistor is connected to the emitter of the eleventh transistor Q11 and the negative terminal of the charging output.

[0011] Furthermore, the relay switching circuit also includes a second eighth current limiting resistor R28, a third zero resistor R30, a seventh zero resistor R70, a fifth ninth current limiting resistor R59, and a sixth ninth current limiting resistor R69. The positive electrode of the ninth rectifier diode D9 is connected to the contact A of the relay. The source of the ninth switch MOS tube Q9 is connected to the charging output positive terminal through the second eighth current limiting resistor R28. The output end of the second eighth current limiting resistor R28 is connected to the charging output positive terminal together with the contact A of the relay to connect the battery during charging. The third zero resistor One end of R30 is connected to the cathode of the ninth rectifier diode, and the other end is connected to the gate of the ninth switch MOS tube and the midpoint of the seventh zero resistor R70; the other end of the seventh zero resistor R70 is connected to the collector of the eleventh transistor Q11, the base of the eleventh transistor Q11 is connected to the midpoint of the fifth-ninth current limiting resistor R59 and the sixth-ninth current limiting resistor R69, the emitter of the eleventh transistor Q11 and the other end of the fifth-ninth current limiting resistor R59 are grounded and connected to the negative terminal of the charging output, and the other end of the sixth-ninth current limiting resistor R69 is connected to the digital power processor U1.

[0012] Furthermore, the battery status sampling circuit includes a second voltage-dividing resistor R206, and a second current-limiting resistor R193 and a first voltage-dividing resistor R204 connected in sequence, the free end of the first voltage-dividing resistor R204 is connected to the positive terminal of the charging output, that is, connected to the rechargeable battery, the midpoint of the second current-limiting resistor R193 and the second voltage-dividing resistor R206 is connected to the SMCU power supply through the other ends of the third filter capacitor C45 and the fourth filter capacitor C40 connected in parallel, the other end of the second voltage-dividing resistor R206 relative to the midpoint is grounded, and the other end of the second current-limiting resistor R193 relative to the midpoint is connected to the digital power processor U1.

[0013] Furthermore, one end of the third filter capacitor C45 and the fourth filter capacitor C40 in parallel with the second voltage-dividing resistor R206 is connected to the midpoint between the second current-limiting resistor R193 and the first voltage-dividing resistor R204, and the other end of the parallel connection is grounded together, and the other end of the parallel third filter capacitor C45 and the fourth filter capacitor C40 and the midpoint of the second current-limiting resistor R193 are connected to the SMCU power supply through a forward diode D20, and are grounded through a reverse diode.

[0014] Furthermore, the relay coil control circuit includes a first eighty-one current limiting resistor R181, a first ninety-eight current limiting resistor R198, a third four rectifier diode D34, a relay coil K1-A, a second five transistor Q25, a first eighty-two current limiting resistor R182, a ninth zero filter capacitor C90, a first ninety-seven current limiting resistor R197, and a first twenty-four current limiting resistor R124. The first eighty-one current limiting resistor R181 and the first ninety-eight current limiting resistor R198 are connected in parallel and one end of each is connected to the 12VS network. The other end of the first eighty-one current limiting resistor R181 is connected to the second foot of the relay coil K1-A, and the other end of the first ninety-eight current limiting resistor R198 is connected to the third four rectifier diode The negative pole of D34; the first foot of the relay coil K1-A and the anode of the 34th rectifier diode D34 are connected in parallel and commonly connected to the collector of the 25th transistor Q25, the base of the 25th transistor Q25 is connected to the midpoint of one end of the 182nd current limiting resistor R182, one end of the 197th current limiting resistor R197 and one end of the 90th filter capacitor C90: the emitter of the 25th transistor Q25 is connected to the ground: the other end of the 197th current limiting resistor R197 and the 90th filter capacitor C90 are connected in parallel to the ground: the other end of the 182nd current limiting resistor R182 is connected to one end of the 124th current limiting resistor R124, and the other end of the 124th current limiting resistor R124 is connected to the digital power processor U1.

[0015] Furthermore, the switching power supply topology circuit includes an isolation driver chip U3, a first MOS transistor Q1, a second MOS transistor Q2 and an isolation transformer T1, the output end of the digital power processor U1 is connected to the input end of the isolation driver chip U3, the two output ends of the isolation driver chip U3 are respectively connected to the gate of the first MOS transistor Q1 and the gate of the second MOS transistor Q2, the source of the first MOS transistor Q1 is connected to the drain of the second MOS transistor Q2, the drain of the first MOS transistor Q1 and the source of the second MOS transistor Q2 are respectively connected to the positive and negative electrodes of an external power supply, the midpoint of the source of the first MOS transistor Q1 and the drain of the second MOS transistor Q2 are connected to the primary coil of the isolation transformer T1 through a first resonant capacitor C1 and a first resonant inductor L1 connected in series, and the output end of the secondary coil of the isolation transformer T1 is respectively connected to the positive electrode of the first rectifier diode D1 and the positive electrode of the second rectifier diode D2.

[0016] Furthermore, the input end of the relay coil control circuit is connected to the output end of the digital power processor U1, the cathode of the first rectifier diode D1 and the cathode of the second rectifier diode D2 are connected in parallel to one end A of the relay K1, and the other end B of the relay K1 is connected to the rechargeable battery through a charging interface.

[0017] Furthermore, when the rechargeable battery is disconnected or the charging line is unplugged, the instantaneous voltage at the positive electrode of the electrolytic capacitor E1 rises to the set full charge voltage, and the digital power processor U1 simultaneously sends an instruction to turn on the MOS tube Q9. At this time, the voltage of the contact of relay B is close to the voltage of the contact of relay A, and the relay coil control circuit controls the contact to close under the instruction of the digital power processor U1; after the rechargeable battery is disconnected or the charging line is unplugged, when the rechargeable battery is connected again, the digital power processor U1 detects that the battery is connected, and sends an operation instruction to the relay switching circuit to turn on the MOS tube Q9, forming a loop through the body diode of the MOS tube Q9 inside the battery, and after lowering the voltage of the positive electrode of the electrolytic capacitor EI to near the voltage of the rechargeable battery, the relay contact is controlled to close through the relay coil circuit.

[0018] And, a charging control method of a relay switching protection circuit for a digital power supply is provided, which adopts the relay switching protection circuit for a digital power supply as described above, and the method comprises the following steps:

[0019] Initialize the program and connect the rechargeable battery;

[0020] Collect battery status information through a battery status sampling circuit;

[0021] The digital power processor U1 controls the ninth switch MOS tube Q9 in the relay switching protection circuit to turn on according to the battery status information collected by the battery status sampling circuit, so as to reduce the voltage difference between the relay contacts;

[0022] When the voltage difference between the relay contacts decreases to a predetermined voltage difference or the relay contacts are in a safe voltage state, the digital power processor U1 controls the relay coil control circuit to close or open the relay contacts.

[0023] Furthermore, the step of controlling the relay to switch the protection circuit includes the following process:

[0024] When the rechargeable battery is in place and the battery power is within the rechargeable range, the switching power topology circuit charges the rechargeable battery; the digital power processor U1 collects battery voltage information through the battery status sampling circuit, controls the LLC main circuit output to be consistent with it, and then controls the circuit through the relay coil to close the relay contacts. At this time, the voltage difference between the relay contacts A and B is within the allowable range of the specification;

[0025] When the rechargeable battery is disconnected or the charging cable is unplugged, the instantaneous voltage of the positive electrode of the electrolytic capacitor E1 rises to the set full voltage, and the digital power processor U1 simultaneously sends an instruction to the relay switching circuit to turn on the MOS tube Q9. At this time, the voltage of the relay B contact is close to the voltage of the relay A contact, and the relay coil control circuit controls the contact to be closed under the instruction of the digital power processor U1;

[0026] After the rechargeable battery is disconnected or the charging cable is unplugged, when the rechargeable battery is connected again, the digital power processor U1 detects that the battery is connected, sends an operation instruction to the relay switching circuit, turns on the MOS tube Q9, forms a loop through the body diode of the MOS tube Q9 inside the battery, pulls down the voltage of the positive electrode of the electrolytic capacitor EI to near the voltage of the rechargeable battery, and then controls the relay contacts to close through the relay coil circuit;

[0027] When the rechargeable battery is connected to the charging interface, the battery status sampling circuit sends the status information of the rechargeable battery to the digital power processor U1, and the digital power processor U1 obtains the in-place status information of the rechargeable battery. When the rechargeable battery is in place and the battery voltage is not within the rechargeable range, the digital power processor U1 sends a charging instruction to the switching power topology circuit, so that the switching power LLC topology circuit activates charging for the rechargeable battery, turns on the ninth switch MOS tube Q9, forms a loop through the body diode of the ninth switch MOS tube, and performs charging activation through the loop current until the charging output end returns to normal.

[0028] In the relay switching protection circuit and control method for digital power supply, the main power output of the power supply is transmitted through the topology circuit, and the charging state is monitored in real time through the battery status detection circuit, and the rechargeable battery is detected. After obtaining the status information such as whether the rechargeable battery is in place or whether the charging is disconnected, whether it is plugged in, etc., the digital power processor U1 sends instructions to the relay switching protection circuit to control the opening of the transistor and the switch tube in the relay switching protection circuit, so that the voltage difference between the two contacts of the relay reaches the required low voltage difference, that is, the relay coil control circuit is started, and the relay contacts are closed and disconnected, thereby effectively protecting the relay and allowing the charger to be plugged in and out at will, which not only meets the requirements of the plug-in test, but also protects the safety of the relay and effectively extends the service life of the relay. In addition, each circuit unit can be realized by the same integrated circuit chip, which is highly integrated, simple in circuit structure, safe and reliable, low in cost, easy to achieve the purpose of switching and protection, and convenient for application and promotion. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 The present invention provides a structural block diagram of a relay switching protection circuit for a digital power supply.

[0030] Figure 2 It is a schematic diagram of the main circuit structure of a relay switching protection circuit for a digital power supply according to an embodiment of the present invention.

[0031] Figure 3 Schematic diagram of the circuit structure of the secondary coil part in the embodiment of the present invention.

[0032] Figure 4 Schematic diagram of a battery status sampling circuit in an embodiment of the present invention.

[0033] Figure 5 Schematic diagram of a relay coil control circuit in an embodiment of the present invention.

[0034] Figure 6 Schematic diagram of the circuit structure of the digital power processor U1 in the embodiment of the present invention.

[0035] Figure 7 It is a schematic diagram of the working process of the charging control method of the relay switching protection circuit for digital power supply provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0036] The technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments; based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0037] See also Figures 1 to 6 , showing a relay switching protection circuit for a digital power supply provided by an embodiment of the present invention, the digital power supply has a digital power processor U1, a switching power supply topology circuit, the switching power supply topology circuit has a relay K1, the relay switching protection circuit includes a battery status sampling circuit and a relay protection control circuit, the switching power supply topology circuit, the battery status sampling circuit, and the relay protection control circuit are respectively connected to a rechargeable battery.

[0038] The battery status sampling circuit is connected to the digital power processor U1, and is used to collect the status information of the rechargeable battery according to the pulse signal generated by the digital power processor. Specifically, the digital power processor has a pulse generating circuit, and the pulse signal is sent by the processor. The model of the digital power processor U1 is IC-TAE32F5300ALF128-LQFP64L.

[0039] The relay protection control circuit includes a relay switching circuit and a relay coil control circuit. The relay switching protection circuit is used to reduce the voltage difference between the contacts of relay K1 according to the information collected by the battery status sampling circuit to protect the switching contacts of relay K1. The relay switching circuit and the relay coil control circuit are respectively connected to the digital power processor U1 and respectively receive corresponding control signals. The relay coil control circuit closes or opens the contacts of relay K1 according to the control signal of the digital power processor U1.

[0040] The relay switching circuit includes a ninth rectifier diode D9, a ninth switch MOS tube Q9, and an eleventh transistor Q11. The substrate of the eleventh transistor Q11 is connected to the digital power processor U1. The emitter of the eleventh transistor Q11 is connected to the negative terminal of the charging output and to the positive terminal of the ninth rectifier diode D9. The negative terminal of the ninth rectifier diode D9 is connected to the drain of the ninth rectifier diode D9. The collector of the eleventh transistor Q11 is connected to the gate of the ninth switch MOS tube Q9 and is connected between the drain of the ninth switch MOS tube Q9 and the negative terminal of the ninth rectifier diode D9 through a resistor. The source of the ninth switch MOS tube Q9 is connected to the positive terminal of the charging output. The ninth rectifier diode D9 is connected in series with the ninth switch MOS tube and connected in parallel with the relay K1 to the positive terminal of the charging output.

[0041] like Figure 1 , Figure 2 and Figure 3 As shown, an electrolytic capacitor E1 is connected in parallel between the positive and negative ends of the output of the switching power supply topology circuit, the positive electrode of the electrolytic capacitor E1 is connected to the positive electrode of the ninth rectifier diode D9 and the contact A of the relay K1, the negative electrode of the electrolytic capacitor E1 is connected to one end of at least one sampling resistor and grounded, and the other end of the sampling resistor is connected to the emitter of the eleventh transistor Q11 and the negative end of the charging output. The positive electrode of the electrolytic capacitor E1 is also connected to the positive end of the switching power supply topology circuit. Figure 2 and Figure 3 As shown, there are multiple sampling resistors, including sampling resistors RS1, RS2, and RS3. The three sampling resistors RS1, RS2, and RS3 are connected in parallel between the negative electrode of the electrolytic capacitor E1 and the emitter of the eleventh transistor Q11, and one end of the three sampling resistors RS1, RS2, and RS3 close to E1 is grounded.

[0042] Further, the relay switching circuit also includes a second eighth current limiting resistor R28, a third zero resistor R30, a seventh zero resistor R70, a fifth ninth current limiting resistor R59, and a sixth ninth current limiting resistor R69, the positive electrode of the ninth rectifier diode D9 is connected to the contact A of the relay K1, the source of the ninth switch MOS tube Q9 is connected to the charging output positive terminal through the second eighth current limiting resistor R28, and the output end of the second eighth current limiting resistor R28 is connected to the charging output positive terminal together with the contact A of the relay K1 to connect the battery during charging, and the third zero One end of the resistor R30 is connected to the negative electrode of the ninth rectifier diode, and one end is connected to the gate of the ninth switch MOS tube and the midpoint of the seventh zero resistor R70; the other end of the seventh zero resistor R70 is connected to the collector of the eleventh transistor Q11, the base of the eleventh transistor Q11 is connected to the midpoint of the fifth-ninth current-limiting resistor R59 and the sixth-ninth current-limiting resistor R69, the emitter of the eleventh transistor Q11 and the other end of the fifth-ninth current-limiting resistor R59 are grounded and connected to the negative terminal of the charging output, and the other end of the sixth-ninth current-limiting resistor R69 is connected to the digital power processor U1. As shown in the figure, the other end of the sixth-ninth current-limiting resistor R69 is connected in series to the digital power processor U1 through the resistor R112.

[0043] Furthermore, if Figure 4 As shown, the battery status sampling circuit includes a second voltage-dividing resistor R206, and a second current-limiting resistor R193 and a first voltage-dividing resistor R204 connected in sequence, the free end of the first voltage-dividing resistor R204 is connected to the positive terminal of the charging output, the midpoint of the second current-limiting resistor R193 and the second voltage-dividing resistor R206 is connected to the SMCU power supply through the other ends of the third filter capacitor C45 and the fourth filter capacitor C40 connected in parallel, the other end of the second voltage-dividing resistor R206 relative to the midpoint is grounded, and the other end of the second current-limiting resistor R193 relative to the midpoint is connected to the digital power processor U1.

[0044] Further, one end of the third filter capacitor C45 and the fourth filter capacitor C40 connected in parallel with the second voltage-dividing resistor R206 is connected to the midpoint between the second current-limiting resistor R193 and the first voltage-dividing resistor R204, and the other end connected in parallel is grounded together, and the other end of the third filter capacitor C45 and the fourth filter capacitor C40 connected in parallel and the midpoint of the second current-limiting resistor R193 are connected to the SMCU power supply through a forward diode D20, and grounded through a reverse diode. In this embodiment, the bidirectional diode D20 is used for clamping protection of the U1 access port level. When a rechargeable battery is connected, the digital power processor U1 can obtain an access signal, that is, the digital power processor U1 collects the battery voltage information through the battery status sampling circuit, that is, obtains the in-place status information of the rechargeable battery.

[0045] Furthermore, if Figure 5As shown, the relay coil control circuit includes a first eighty-one current limiting resistor R181, a first ninety-eight current limiting resistor R198, a third four rectifier diode D34, a relay coil K1-A, a second five transistor Q25, a first eighty-two current limiting resistor R182, a ninth zero filter capacitor C90, a first ninety-seven current limiting resistor R197, and a first twenty-four current limiting resistor R124. The first eighty-one current limiting resistor R181 and the first ninety-eight current limiting resistor R198 are connected in parallel and one end of each is connected to the 12VS network. The other end of the first eighty-one current limiting resistor R181 is connected to the second foot of the relay coil K1-A. The other end of the first ninety-eight current limiting resistor R198 is connected to the third four rectifier diode D The negative electrode of 34; the first foot of the relay coil K1-A and the anode of the 34th rectifier diode D34 are connected in parallel and commonly connected to the collector of the 25th transistor Q25, the base of the 25th transistor Q25 is connected to the midpoint of one end of the 182nd current limiting resistor R182, one end of the 197th current limiting resistor R197 and one end of the 90th filter capacitor C90: the emitter of the 25th transistor Q25 is connected to the ground: the other end of the 197th current limiting resistor R197 and the 90th filter capacitor C90 are connected in parallel to the ground: the other end of the 182nd current limiting resistor R182 is connected to one end of the 124th current limiting resistor R124, and the other end of the 124th current limiting resistor R124 is connected to the digital power processor U1. When the digital power processor U1 gives a high-level signal, for example, when the relay needs to be turned on, a high-level signal is given through pin 33. The high-level signal triggers the transistor Q25 to turn on, and current passes through the relay coil K1-A, which controls the closing of the relay K1 contacts to perform charging operations, otherwise the contacts are opened.

[0046] Furthermore, the switching power supply topology circuit includes an isolation driver chip U3, a first MOS transistor Q1, a second MOS transistor Q2 and an isolation transformer T1, the output end of the digital power processor U1 is connected to the input end of the isolation driver chip U3, the two output ends of the isolation driver chip U3 are respectively connected to the gate of the first MOS transistor Q1 and the gate of the second MOS transistor Q2, the source of the first MOS transistor Q1 is connected to the drain of the second MOS transistor Q2, the drain of the first MOS transistor Q1 and the source of the second MOS transistor Q2 are respectively connected to the positive and negative electrodes of an external power supply, the midpoint of the source of the first MOS transistor Q1 and the drain of the second MOS transistor Q2 are connected to the primary coil of the isolation transformer T1 through a first resonant capacitor C1 and a first resonant inductor L1 connected in series, and the output end of the secondary coil of the isolation transformer T1 is respectively connected to the positive electrode of the first rectifier diode D1 and the positive electrode of the second rectifier diode D2. The positive electrode of the electrolytic capacitor E1 is connected to the negative electrode of the positive electrode of the first rectifier diode D1 and the negative electrode of the second rectifier diode D2, and the negative electrode of the electrolytic capacitor E1 is connected to the other end of the secondary coil of the isolation transformer T1.

[0047] Furthermore, the input end of the relay coil control circuit is connected to the output end of the digital power processor U1, the cathode of the first rectifier diode D1 and the cathode of the second rectifier diode D2 are connected in parallel to one end A of the relay K1, and the other end B of the relay K1 is connected to the rechargeable battery through a charging interface.

[0048] Furthermore, when the rechargeable battery is disconnected or the charging cable is unplugged, the instantaneous voltage at the positive electrode of the electrolytic capacitor E1 rises to the set full charge voltage, and the digital power processor U1 simultaneously sends an instruction to turn on the MOS tube Q9. At this time, the voltage of the relay K1B contact is close to the voltage of the relay K1A contact, and the relay coil control circuit controls the contact to close under the instruction of the digital power processor U1; after the rechargeable battery is disconnected or the charging cable is unplugged, when the rechargeable battery is connected again, the digital power processor U1 detects that the battery is connected, and sends an operation instruction to the relay switching circuit to turn on the MOS tube Q9, forming a loop through the body diode of the MOS tube Q9 inside the battery, and after lowering the voltage of the positive electrode of the electrolytic capacitor EI to near the voltage of the rechargeable battery, the relay coil circuit controls the contact of the relay K1 to close.

[0049] See also Figure 7 On the other hand, an embodiment of the present invention further provides a charging control method for a relay switching protection circuit for a digital power supply, which adopts the relay switching protection circuit for a digital power supply as described above, and the method comprises the following steps:

[0050] Step S01, program initialization, connecting the rechargeable battery;

[0051] Step S02, collecting battery status information through a battery status sampling circuit;

[0052] Step S03, the digital power processor U1 controls the ninth switch MOS tube Q9 in the relay switching protection circuit to turn on according to the battery status information collected by the battery status sampling circuit, so as to reduce the voltage difference between the contacts of the relay K1;

[0053] Step S04: When the voltage difference between the contacts of the relay K1 decreases to a predetermined voltage difference or the contacts of the relay K1 are in a safe voltage state, the digital power processor U1 controls the relay coil control circuit to close or open the contacts of the relay K1.

[0054] In step S02, the battery status information is collected by the battery status sampling circuit mainly by collecting the charging battery status, for example, voltage information collection, and sampling is performed through at least one sampling resistor to determine whether the battery is in place, whether the battery is fully charged or overcharged, or inserted or removed, thereby providing a reference for the subsequent relay switching protection circuit to work.

[0055] In step S03, after receiving the battery status information collected by the battery status sampling circuit, the digital power processor U1 makes a judgment and analysis, and then sends a corresponding command signal to the control relay switching protection circuit.

[0056] Furthermore, the step of controlling the relay to switch the protection circuit in step S04 specifically includes the following process:

[0057] In the first case, when the rechargeable battery is in place and the battery power is within the rechargeable range, the switching power topology circuit charges the rechargeable battery; the digital power processor U1 collects battery voltage information through the battery status sampling circuit, controls the LLC main circuit output to be consistent with it, and then controls the circuit through the relay coil to close the relay K1 contact. At this time, the voltage difference between the relay K1 contacts A and B is within the specification allowable range. That is, the relay K1 is turned on and the charger is in normal charging state.

[0058] In the second case, when the charger is connected to the battery, and the battery voltage is within the chargeable range (far below the full voltage), the relay K1 is closed to charge the battery, and then the connection line between the battery and the charger is unplugged. Because the national standard of the charger is that there can be no voltage output at the output end in the standby state, the relay contacts must be disconnected, but at this time the LLC main topology has no current, and the digital power processor U1 will automatically return to the voltage loop control. That is, when the charging battery is disconnected or the charging line is unplugged, the connection line between the charging battery and the charger is disconnected. At this time, the instantaneous voltage of the positive electrode of the electrolytic capacitor E1 rises to the set full voltage, and the digital power processor U1 simultaneously sends an instruction to the relay switching circuit to turn on the MOS tube Q9. At this time, the voltage of the B contact of the relay K1 is close to the voltage of the A contact of the relay K1, and the relay coil control circuit controls the contact to close under the instruction of the digital power processor U1.

[0059] In the third case, when the charger is connected to the battery and the battery voltage is within the chargeable range (far below the full voltage), the relay is closed to charge the battery, and then the battery and charger connection line are unplugged. At this time, the LLC main topology has no current, and the digital power processor U1 will automatically return to the voltage loop control. The instantaneous voltage of the positive electrode of E1 rises to the set full voltage. At this time, if the charger and battery connection line are connected again and the relay is closed directly, the voltage difference between the two ends of the relay will be greater than the switching voltage specification allowed by the relay, causing a large current to form between the relay contacts and cause damage. At this time, when the battery and charger are connected again, the digital power processor U1 detects that the battery is connected, sends an operation instruction through the SW2 pin, turns on the MOS tube Q9, forms a loop through the body diode of the MOS tube inside the battery, pulls down the voltage of the positive electrode of EI to near the battery voltage, and then performs the relay coil circuit to control the contact closure action, thereby protecting the use of the relay. When the battery and charger connection line are plugged in and out again, this operation logic can be enabled again.

[0060] In the fourth case, when the rechargeable battery is connected to the charging interface, the battery status sampling circuit sends the status information of the rechargeable battery to the digital power processor U1, and the digital power processor U1 obtains the in-place status information of the rechargeable battery. When the rechargeable battery is in place and the battery voltage is not within the rechargeable range, for example, the battery is over-discharged and there is no voltage at the battery port. The digital power processor U1 sends a charging instruction to the switching power topology circuit, so that the switching power LLC topology circuit activates charging to the rechargeable battery, turns on the ninth switch MOS tube Q9, forms a loop through the body diode of the ninth switch MOS tube, and activates charging through the loop current until the charging output terminal returns to normal.

[0061] In the relay switching protection circuit and control method for digital power supply, the main power output of the power supply is transmitted through the topology circuit, and the charging state is monitored in real time through the battery state detection circuit, and the rechargeable battery is detected. After obtaining the state information such as whether the rechargeable battery is in place or whether the charging is disconnected, whether it is plugged in, etc., the digital power processor U1 sends instructions to the relay switching protection circuit to control the opening of the transistor and the switch tube in the relay switching protection circuit, so that the voltage difference between the two contacts of the relay K1 reaches the required low voltage difference, that is, the relay coil control circuit is started, and the relay K1 contact is closed and disconnected, thereby effectively protecting the relay K1 and allowing the charger to be plugged in and out at will, which not only meets the requirements of the plug-in test, but also protects the safety of the relay K1 and effectively extends the service life of the relay K1. In addition, each circuit unit can be realized by the same integrated circuit chip, which is highly integrated, simple in circuit structure, safe and reliable, low in cost, easy to achieve the purpose of switching and protection, and convenient for application and promotion.

[0062] It should be noted that the present invention is not limited to the above-mentioned embodiments. Based on the creative spirit of the present invention, those skilled in the art may also make other changes. These changes made based on the creative spirit of the present invention should be included in the scope of protection required by the present invention.

Claims

1. A relay switching protection circuit for a digital power supply, wherein the digital power supply has a digital power supply processor U1 and a switching power supply topology circuit, wherein the switching power supply topology circuit has a relay, wherein: The relay switching protection circuit includes a battery state sampling circuit and a relay protection control circuit, and the switching power supply topology circuit, the battery state sampling circuit, and the relay protection control circuit are respectively connected to the rechargeable battery; The battery status sampling circuit is connected to the digital power processor U1, and is used to collect status information of the rechargeable battery according to the pulse signal generated by the digital power processor U1; The relay protection control circuit includes a relay switching circuit and a relay coil control circuit. The relay switching circuit is used to reduce the voltage difference between the relay contacts to protect the relay switching contacts according to the information collected by the battery status sampling circuit. The relay switching circuit and the relay coil control circuit are respectively connected to the digital power processor U1 and receive corresponding control signals respectively. The relay coil control circuit closes or opens the relay contacts according to the control signal of the digital power processor U1; The relay switching circuit includes a ninth rectifier diode D9, a ninth switch MOS tube Q9, and an eleventh transistor Q11, wherein the substrate of the eleventh transistor Q11 is connected to the digital power processor U1, the emitter of the eleventh transistor Q11 is connected to the negative terminal of the charging output, the negative terminal of the ninth rectifier diode D9 is connected to the source of the ninth switch MOS tube Q9, the drain of the ninth switch MOS tube Q9 is connected to the positive terminal of the charging output, and the ninth rectifier diode D9 is connected in series with the ninth switch MOS tube and then connected in parallel with the relay to the positive terminal of the charging output; An electrolytic capacitor E1 is connected in parallel between the positive and negative ends of the output of the switching power supply topology circuit, the positive electrode of the electrolytic capacitor E1 is connected to the positive electrode of the ninth rectifier diode D9 and the contact A of the relay, the negative electrode of the electrolytic capacitor E1 is connected to one end of at least one sampling resistor and grounded, and the other end of the sampling resistor is connected to the emitter of the eleventh transistor Q11 and the negative terminal of the charging output; The relay switching circuit also includes a second eighth current limiting resistor R28, a third zero resistor R30, a seventh zero resistor R70, a fifth ninth current limiting resistor R59, and a sixth ninth current limiting resistor R69. The positive electrode of the ninth rectifier diode D9 is connected to the contact A of the relay. The drain of the ninth switch MOS tube Q9 is connected to the charging output positive terminal through the second eighth current limiting resistor R28. The output end of the second eighth current limiting resistor R28 and the contact B of the relay are connected to the charging output positive terminal to connect the battery during charging. One end of the third zero resistor R30 is connected to the charging output positive terminal. It is connected to the cathode of the ninth rectifier diode, and the other end is connected to the gate of the ninth switch MOS tube and one end of the seventh zero resistor R70; the other end of the seventh zero resistor R70 is connected to the collector of the eleventh transistor Q11, the base of the eleventh transistor Q11 is connected to one end of the fifth-ninth current-limiting resistor R59 and one end of the sixth-ninth current-limiting resistor R69, the emitter of the eleventh transistor Q11 and the other end of the fifth-ninth current-limiting resistor R59 are grounded and connected to the negative terminal of the charging output, and the other end of the sixth-ninth current-limiting resistor R69 is connected to the digital power processor U1.

2. The relay switching protection circuit for digital power supply according to claim 1, characterized in that: The battery status sampling circuit includes a second voltage-dividing resistor R206, and a second current-limiting resistor R193 and a first voltage-dividing resistor R204 connected in sequence, wherein the free end of the first voltage-dividing resistor R204 is connected to the positive terminal of the charging output, the other end of the first voltage-dividing resistor R204 is connected to one end of the second voltage-dividing resistor R206 and one end of the second current-limiting resistor R193, the other end of the second voltage-dividing resistor R206 is grounded, and the other end of the second current-limiting resistor R193 relative to the first voltage-dividing resistor R204 is connected to the digital power processor U1.

3. The relay switching protection circuit for digital power supply according to claim 2, characterized in that: One end of the third filter capacitor C45 and the fourth filter capacitor C40 connected in parallel is grounded, and the other end is respectively connected to the other end of the first voltage-dividing resistor R204. The first voltage-dividing resistor R204 and the second current-limiting resistor R193 are connected to the SMCU power supply through a diode D20.

4. The relay switching protection circuit for digital power supply according to claim 1, characterized in that: The relay coil control circuit includes a first eighty-one current limiting resistor R181, a first ninety-eight current limiting resistor R198, a third four rectifier diode D34, a relay coil K1-A, a second five transistor Q25, a first eighty-two current limiting resistor R182, a ninth zero filter capacitor C90, a first ninety-seven current limiting resistor R197, and a first twenty-four current limiting resistor R124. The first eighty-one current limiting resistor R181 and the first ninety-eight current limiting resistor R198 are connected in parallel and one end of each is connected to the 12VS network. The other end of the first eighty-one current limiting resistor R181 is connected to the second foot of the relay coil K1-A. The other end of the first ninety-eight current limiting resistor R198 is connected to the third four rectifier diode D The negative electrode of 34; the first foot of the relay coil K1-A is connected to the anode of the 34th rectifier diode D34 and are commonly connected to the collector of the 25th transistor Q25, the base of the 25th transistor Q25 is connected to one end of the 182nd current limiting resistor R182, one end of the 197th current limiting resistor R197 and one end of the 90th filter capacitor C90: the emitter of the 25th transistor Q25 is connected to the ground: the other end of the 197th current limiting resistor R197 and the other end of the 90th filter capacitor C90 are grounded: the other end of the 182nd current limiting resistor R182 is connected to one end of the 124th current limiting resistor R124, and the other end of the 124th current limiting resistor R124 is connected to the digital power processor U1.

5. The relay switching protection circuit for digital power supply according to claim 1, characterized in that: The switching power supply topology circuit includes an isolation driver chip U3, a first MOS transistor Q1, a second MOS transistor Q2 and an isolation transformer T1. The output end of the digital power processor U1 is connected to the input end of the isolation driver chip U3. The two output ends of the isolation driver chip U3 are respectively connected to the gate of the first MOS transistor Q1 and the gate of the second MOS transistor Q2. The source of the first MOS transistor Q1 is connected to the drain of the second MOS transistor Q2. The drain of the first MOS transistor Q1 and the source of the second MOS transistor Q2 are respectively connected to the positive and negative electrodes of the external power supply. The source of the first MOS transistor Q1 is connected to the positive electrode and the negative electrode of the external power supply. The connection point between the first and second MOS tube Q2 and the drain of the second MOS tube Q2 is connected to the primary coil of the isolation transformer T1 through a first resonant capacitor C1 and a first resonant inductor L1 connected in series with each other, the output end of the secondary coil of the isolation transformer T1 is respectively connected to the anode of the first rectifier diode D1 and the anode of the second rectifier diode D2, the input end of the relay coil control circuit is connected to the output end of the digital power processor U1, the cathode of the first rectifier diode D1 and the cathode of the second rectifier diode D2 are connected in parallel to a contact A of the relay K1, and the other contact B of the relay K1 is connected to the rechargeable battery through a charging interface.

6. The relay switching protection circuit for digital power supply according to claim 1, characterized in that: When the rechargeable battery is disconnected or the charging line is unplugged, the instantaneous voltage of the positive electrode of the electrolytic capacitor E1 rises to the set full charge voltage, and the digital power processor U1 simultaneously sends an instruction to turn on the MOS tube Q9. At this time, the voltage of the contact of relay B is close to the voltage of the contact of relay A, and the relay coil control circuit controls the contact to be closed under the instruction of the digital power processor U1; after the rechargeable battery is disconnected or the charging line is unplugged, when the rechargeable battery is connected again, the digital power processor U1 detects that the battery is connected, and sends an operation instruction to the relay switching circuit to turn on the MOS tube Q9, and a loop is formed through the body diode of the MOS tube Q9 inside the battery, and the voltage of the positive electrode of the electrolytic capacitor E1 is pulled down to near the voltage of the rechargeable battery, and then the relay contact is controlled to be closed through the relay coil circuit.

7. A charging control method for a relay switching protection circuit for a digital power supply, which uses the relay switching protection circuit for a digital power supply according to any one of claims 1 to 6, and the method comprises the following steps: Initialize the program and connect the rechargeable battery; Collect battery status information through a battery status sampling circuit; The digital power processor U1 controls the ninth switch MOS tube Q9 in the relay switching protection circuit to turn on according to the battery status information collected by the battery status sampling circuit, so as to reduce the voltage difference between the relay contacts; When the voltage difference between the relay contacts decreases to a predetermined voltage difference or the relay contacts are in a safe voltage state, the digital power processor U1 controls the relay coil control circuit to close or open the relay contacts.

8. The charging control method for a relay switching protection circuit for a digital power supply according to claim 7, characterized in that: The steps of controlling the relay to switch the protection circuit include the following process: When the rechargeable battery is in place and the battery power is within the rechargeable range, the switching power topology circuit charges the rechargeable battery; the digital power processor U1 collects battery voltage information through the battery status sampling circuit, controls the LLC main circuit output to be consistent with it, and then controls the circuit through the relay coil to close the relay contacts. At this time, the voltage difference between the relay contacts A and B is within the allowable range of the specification; When the rechargeable battery is disconnected or the charging cable is unplugged, the instantaneous voltage of the positive electrode of the electrolytic capacitor E1 rises to the set full voltage, and the digital power processor U1 simultaneously sends an instruction to the relay switching circuit to turn on the MOS tube Q9. At this time, the voltage of the relay B contact is close to the voltage of the relay A contact, and the relay coil control circuit controls the contact to be closed under the instruction of the digital power processor U1; After the rechargeable battery is disconnected or the charging cable is unplugged, when the rechargeable battery is connected again, the digital power processor U1 detects that the battery is connected, sends an operation instruction to the relay switching circuit, turns on the MOS tube Q9, forms a loop through the body diode of the MOS tube Q9 inside the battery, pulls down the voltage of the positive electrode of the electrolytic capacitor E1 to near the voltage of the rechargeable battery, and then controls the relay contacts to close through the relay coil circuit; When the rechargeable battery is connected to the charging interface, the battery status sampling circuit sends the status information of the rechargeable battery to the digital power processor U1, and the digital power processor U1 obtains the in-place status information of the rechargeable battery. When the rechargeable battery is in place and the battery voltage is not within the rechargeable range, the digital power processor U1 sends a charging instruction to the switching power topology circuit, so that the switching power topology circuit activates charging of the rechargeable battery, turns on the ninth switch MOS tube Q9, forms a loop through the body diode of the ninth switch MOS tube, and activates charging through the loop current until the charging output end returns to normal.

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