AC charger control circuit

Abstract

The utility model relates to an AC charger control circuit comprising a relay, an MCU module, an AC / DC module, a voltage sampling module and a relay driving control module. The AC / DC module comprises an industrial frequency transformer, a rectification unit and a voltage reduction unit, a primary winding of the industrial frequency transformer is connected with an alternating current power supply, a secondary winding of the industrial frequency transformer is connected with the input end of the rectification unit, and the output end of the rectification unit is connected with the input end of the voltage reduction unit. The output end of the voltage reduction unit provides working voltage for the MCU module, the voltage sampling module and the relay driving control module; a sampling input end of the voltage sampling module is connected with a secondary winding of the industrial frequency transformer, and a voltage feedback output end of the voltage sampling module is connected with the MCU module; and the relay driving control module is connected with the MCU module and the relay, and the relay driving control module receives an instruction sent by the MCU module and drives the relay to be connected or disconnected. On the premise of ensuring normal use, the product cost can be greatly reduced, and the market competitiveness is improved.

Description

Technical Field

[0001] This utility model relates to the field of AC charger technology, and in particular to an AC charger control circuit. Background Technology

[0002] As competition in the new energy vehicle charger market intensifies, chargers are becoming increasingly functional, integrating features such as power metering and leakage detection. Currently, most AC chargers on the market utilize isolation voltage transformers, metering chips, and EMC devices. While these improvements enhance safety and anti-interference capabilities, they also significantly increase costs, resulting in expensive products that are less competitive in the market. Utility Model Content

[0003] The purpose of this invention is to provide an AC charger control circuit that can significantly reduce product costs and increase market competitiveness while ensuring normal use.

[0004] To achieve the above objectives, this utility model discloses an AC charger control circuit, which includes a relay, an MCU module, an AC / DC module, a voltage sampling module, and a relay drive control module;

[0005] The input terminal of the relay is connected to an AC power supply;

[0006] The AC / DC module includes a power frequency transformer, a rectifier unit, and a step-down unit. The primary winding of the power frequency transformer is connected to an AC power source, the secondary winding of the power frequency transformer is connected to the input terminal of the rectifier unit, the output terminal of the rectifier unit is connected to the input terminal of the step-down unit, and the output terminal of the step-down unit provides operating voltage for the MCU module, the voltage sampling module, and the relay drive control module.

[0007] The sampling input terminal of the voltage sampling module is connected to the secondary winding of the power frequency transformer, and the voltage feedback output terminal of the voltage sampling module is connected to the MCU module.

[0008] The relay drive control module connects the MCU module and the relay. The relay drive control module receives instructions from the MCU module and drives the relay to engage or disengage.

[0009] Preferably, the secondary winding of the power frequency transformer includes a primary winding and a secondary winding; the rectifier unit includes a first rectifier subunit and a second rectifier subunit; and the step-down unit includes a first voltage regulator subunit, a second voltage regulator subunit, and a third voltage regulator subunit. The primary winding, the first rectifier subunit, the first voltage regulator subunit, and the second voltage regulator subunit are connected in sequence. The first voltage regulator subunit outputs a +12V voltage, and the second voltage regulator subunit outputs a +5V voltage. The secondary winding, the second rectifier subunit, and the third voltage regulator subunit are connected in sequence, and the third voltage regulator subunit outputs a -12V voltage.

[0010] Preferably, the first rectifier subunit includes a rectifier bridge DB1 and a resistor R1; the second rectifier subunit includes a resistor R2 and a diode D1; the first voltage regulator subunit includes a voltage regulator U2, a capacitor C1, and a capacitor C3; the second voltage regulator subunit includes a voltage regulator U1, a capacitor C2, and a capacitor C4; and the third voltage regulator subunit includes a voltage regulator U3, a capacitor C5, and a capacitor C6. The primary winding NS1 is connected to the input terminal of the rectifier bridge DB1. The positive output terminal of the rectifier bridge DB1 is connected to one end of the resistor R1, one end of the capacitor C3, and the input terminal of the voltage regulator U2. The cathode output terminal of the rectifier bridge DB1, the other end of the resistor R1, the other end of the capacitor C3, and the ground terminal of the voltage regulator U2 are grounded. The output terminal of the voltage regulator U2 is connected to the capacitor C1. One end of capacitor C4 and one end of capacitor C4 are connected to the input terminal of voltage regulator U1. The output terminal of voltage regulator U2 outputs a +12V voltage. The other end of capacitor C1, the other end of capacitor C4, and the ground terminal of voltage regulator U1 are grounded. The output terminal of voltage regulator U1 is grounded through capacitor C2 and outputs a +5V voltage. One end of the secondary winding NS2 is connected to the sampling input terminal of the voltage sampling module, one end of resistor R2, and the cathode of diode D1. The anode of diode D1 is connected to one end of capacitor C6 and the input terminal of voltage regulator U3. The other end of the secondary winding NS2, the other end of resistor R2, the other end of capacitor C6, and the ground terminal of voltage regulator U3 are grounded. The output terminal of voltage regulator U3 is grounded through capacitor C5 and outputs a -12V voltage.

[0011] Preferably, it also includes a CP communication module, which is connected to the output terminal of the first voltage regulator subunit and the output terminal of the third voltage regulator subunit for power supply.

[0012] Preferably, the voltage sampling module includes resistors R4, R5, and R6, capacitors C7, C8, and C9, diodes D31 and D32, and operational amplifier U4. One end of resistor R4 is the sampling input terminal of the voltage sampling module, and the other end of resistor R4 is connected to the non-inverting input terminal of operational amplifier U4, one end of resistor R6, one end of capacitor C8, the cathode of diode D31, and the anode of diode D32. The cathode of diode D32 is connected to the output terminal of the buck converter. The anode of diode D31, the other end of capacitor C8, and the other end of resistor R6 are grounded. The inverting input terminal and output terminal of operational amplifier U4 are connected to one end of resistor R5, and the other end of resistor R5 serves as the voltage feedback output terminal of the voltage sampling module. This voltage feedback output terminal is connected to one end of capacitor C9, and the other end of capacitor C9 is grounded. The negative terminal of the power supply of operational amplifier U4 is grounded, and the positive terminal of the power supply of operational amplifier U4 is connected to the output terminal of the buck converter and one end of capacitor C7. The other end of capacitor C7 is grounded.

[0013] Preferably, the relay is a magnetic latching relay, which has a first coil and a second coil; the relay drive control module includes a relay disconnect drive unit and a relay engage drive unit, and the MCU module has a relay engage control terminal and a relay disconnect control terminal; the relay disconnect drive unit is connected to the relay disconnect control terminal and the first coil of the magnetic latching relay, and receives a disconnect command from the relay disconnect control terminal and drives the magnetic latching relay to disconnect; the relay engage drive unit is connected to the relay engage control terminal and the second coil of the magnetic latching relay, and receives an engage command from the relay engage control terminal and drives the magnetic latching relay to engage.

[0014] Preferably, the relay disconnection drive unit includes a diode D6, a capacitor C12, resistors R13, R14, R18, and R19, transistors Q3 and Q4, and a PMOS transistor Q1. The anode of diode D6 is connected to the output terminal of the step-down unit, and the cathode of diode D6 is connected to one end of capacitor C12, one end of resistor R13, one end of resistor R14, and the source of PMOS transistor Q1. The other end of capacitor C12 is grounded, and the other end of resistor R14 is connected to the collector of transistor Q4, the base of transistor Q3, and the resistor R18. At one end, the base of transistor Q4 is connected to one end of resistor R19, one end of resistor R17, and one end of capacitor C13; the other end of resistor R17 is connected to the relay disconnect control terminal; the other end of capacitor C13, the other end of resistor R19, the emitter of transistor Q4, the other end of resistor R18, and the emitter of transistor Q3 are grounded; the collector of transistor Q3 is connected to one end of resistor R13 and the gate of PMOS transistor Q1; the drain of PMOS transistor Q1 is connected to one end of the first coil of the magnetic latching relay; the other end of the first coil of the magnetic latching relay is grounded.

[0015] The relay energizing drive unit includes resistors R15 and R16 and an NMOS transistor Q2. The relay energizing control terminal is connected to one end of resistor R16 and the gate of NMOS transistor Q2 via resistor R15. The other end of resistor R16 and the drain of NMOS transistor Q2 are grounded. The source of NMOS transistor Q2 is connected to one end of the second coil of the magnetic latching relay. The other end of the second coil of the magnetic latching relay is connected to the cathode of diode D6.

[0016] The first coil of the relay is connected in parallel with diode D5, and the anode of diode D5 is grounded. The second coil of the relay is connected in parallel with diode D4, and the cathode of diode D4 is connected to the cathode of diode D6.

[0017] Preferably, the system further includes a relay adhesion detection module, which comprises a diode D7, resistors R20, R21, R22, R24, R25, R26, and R27, a capacitor C14, and an optocoupler U5. The low-end output terminal of the relay is connected to the anode of the diode D7. The cathode of the diode D7 is connected to one end of the resistor R26 and the anode of the light emitter of the optocoupler U5 via resistors R25, R20, R21, and R22. The other end of the resistor R26 is connected to the cathode of the light emitter of the optocoupler U5 and the N-terminal of the AC power supply. The collector of the photodetector of the optocoupler U5 is connected to the output terminal of the step-down unit. The emitter of the photodetector of the optocoupler U5 is connected to one end of the resistor R24, one end of the resistor R27, and one end of the capacitor C14. The other ends of the resistor R24 ​​and the other end of the capacitor C14 are grounded. The other end of the resistor R27 is connected to the MCU module for relay adhesion feedback.

[0018] Preferably, the system further includes an ungrounded detection module. The MCU module has a power input terminal and an ungrounded feedback receiving terminal. The ungrounded detection module includes resistors R3, R7, R8, R9, R10, R11, R12, RD1, a ferrite bead L1, capacitors C10, C11, and CX1, diodes D21 and D22. The L terminal of the AC power supply is connected to one end of capacitor CX1 and one end of resistor R12 via resistor R11. The other end of resistor R12 is connected to the N terminal of the AC power supply. One end of capacitor CX1 is connected to one end of ferrite bead L1 and one end of capacitor C10 via resistors R10, R7, R9, R8 and R3. The other end of ferrite bead L1 is connected to one end of resistor RD1, one end of capacitor C11, the anode of diode D21, the cathode of diode D22 and the ungrounded feedback receiver. The other ends of capacitor C10, resistor RD1, capacitor C11 and the anode of diode D22 are grounded. The cathode of diode D21 is connected to the power input terminal of the MCU module.

[0019] Preferably, the device further includes a current detection module, an indicator light module, a leakage current detection module, and a temperature detection module. The current detection module is connected to the input or output terminal of the relay to sample the current and feed it back to the MCU module. The indicator light module receives the electrical signal from the MCU module to provide light indication. The temperature detection module is connected to the MCU module and feeds back the charger temperature. The leakage current detection module is connected to the MCU module and feeds back whether the charger is leaking current.

[0020] This utility model has the following beneficial effects:

[0021] 1. This utility model's AC / DC module uses a power frequency transformer, which can directly step down the 50Hz AC mains voltage. After rectification and step-down, it can supply power to relays and other modules requiring DC power, ensuring the charger can function normally. Compared with commercially available switching power supplies, this AC / DC module does not have high-frequency signals and eliminates the need for EMI and driver chips, significantly reducing product costs and increasing market competitiveness.

[0022] 2. The voltage sampling module acquires the lower 50Hz voltage output from the secondary winding of the power frequency transformer. This sampled voltage is then divided and stepped down, and negative voltage signals are filtered out by an operational amplifier, resulting in a 50Hz half-wave sine wave signal that is sent to the MCU module for input voltage calculation. Its advantage lies in eliminating the need for isolated voltage transformers and metering chips, thereby further reducing product costs and increasing market competitiveness. Attached Figure Description

[0023] Figure 1 This is a schematic diagram of the principle of this utility model.

[0024] Figure 2 This is a schematic diagram of an MCU module.

[0025] Figure 3 This is a schematic diagram of an AC / DC module.

[0026] Figure 4 This is a schematic diagram of a voltage sampling module.

[0027] Figure 5 This is a schematic diagram of a relay.

[0028] Figure 6 This is a schematic diagram of a relay disconnect drive unit.

[0029] Figure 7 This is a schematic diagram of a relay activation drive unit.

[0030] Figure 8 This is a schematic diagram of a relay adhesion detection module.

[0031] Figure 9 This is a schematic diagram of an ungrounded detection module.

[0032] Explanation of symbols for main components:

[0033] MCU module 1, AC / DC module 2, voltage sampling module 3, relay disconnection drive unit 41, relay engagement drive unit 42, relay sticking detection module 5, ungrounded detection module 6, CP communication module 7, current detection module 8, indicator light module 9, leakage current detection module 10, temperature detection module 11. Detailed Implementation

[0034] To make the objectives, technical solutions, and advantages of this utility model clearer, the present utility model will be further described in detail below with reference to the accompanying drawings and embodiments.

[0035] like Figures 1-9As shown, this utility model discloses an AC charger control circuit, which includes a relay K1, an MCU module 1, an AC / DC module 2, a voltage sampling module 3, a relay drive control module, a CP communication module 7, a current detection module 8, an indicator light module 9, a leakage current detection module 10, and a temperature detection module 11. The CP communication module 7, current detection module 8, indicator light module 9, leakage current detection module 10, and temperature detection module 11 are existing technologies, and their specific structures will not be described in detail. The MCU module 1 is built based on a single-chip microcomputer U8 and its peripheral circuits. The CP communication module 7 communicates with the MCU module 1 and draws power (±12V) from the AC / DC module 2. The current detection module 8 is connected to the input or output terminal of the relay to sample the current and feed it back to the MCU module 1. The indicator light module 9 receives the electrical signal from the MCU module 1 to provide light indication. The temperature detection module 11 is connected to the MCU module 1 and provides feedback on the charger temperature. The leakage current detection module 10 is connected to the MCU module 1 and provides feedback on whether the charger is leaking current.

[0036] AC / DC module 2 includes a power frequency transformer T1, a rectifier unit, and a step-down unit. The step-down unit provides the DC operating voltage. The primary winding NP1 of the power frequency transformer is connected to the L and N poles of the AC power supply. A fuse and varistor are also provided on the primary side of the power frequency transformer for input voltage protection. The secondary winding of the power frequency transformer T1 includes a primary winding NS1 and a secondary winding NS2. The rectifier unit includes a first rectifier subunit and a second rectifier subunit. The step-down unit includes a first regulator subunit, a second regulator subunit, and a third regulator subunit. The primary winding NS1, the first rectifier subunit, the first regulator subunit, and the second regulator subunit are connected sequentially. The first regulator subunit outputs +12V (V+), and the second regulator subunit outputs +5V (VCC). The secondary winding NS2, the second rectifier subunit, and the third regulator subunit are connected sequentially. The third regulator subunit outputs -12V.

[0037] Specifically, the first rectifier subunit includes a rectifier bridge DB1 and a resistor R1, the second rectifier subunit includes a resistor R2 and a diode D1, the first voltage regulator subunit includes a voltage regulator U2, a capacitor C1 and a capacitor C3, the second voltage regulator subunit includes a voltage regulator U1, a capacitor C2 and a capacitor C4, and the third voltage regulator subunit includes a voltage regulator U3, a capacitor C5 and a capacitor C6. Voltage regulators U1, U2 and U2 are low dropout linear regulators (LDOs).

[0038] The primary winding NS1 is connected to the input terminal of rectifier bridge DB1. The positive output terminal of rectifier bridge DB1 is connected to one end of resistor R1, one end of capacitor C3, and the input terminal of voltage regulator U2. The cathode output terminal of rectifier bridge DB1, the other end of resistor R1, the other end of capacitor C3, and the ground terminal of voltage regulator U2 are grounded. The output terminal of voltage regulator U2 is connected to one end of capacitor C1, one end of capacitor C4, and the input terminal of voltage regulator U1. The output terminal of voltage regulator U2 outputs a +12V voltage (V+). The other end of capacitor C1, the other end of capacitor C4, and the ground terminal of voltage regulator U1 are grounded. The output terminal of voltage regulator U1 is grounded through capacitor C2. The output terminal of voltage regulator U1 outputs a +5V voltage (VCC). One end of the secondary winding NS2 is connected to the sampling input terminal of the voltage sampling module 3, one end of the resistor R2, and the cathode of the diode D1. The anode of the diode D1 is connected to one end of the capacitor C6 and the input terminal of the voltage regulator U3. The other end of the secondary winding NS2, the other end of the resistor R2, the other end of the capacitor C6, and the ground terminal of the voltage regulator U3 are grounded. The output terminal of the voltage regulator U3 is grounded through the capacitor C5, and the output terminal of the voltage regulator U3 outputs a -12V voltage.

[0039] A silicon steel power frequency transformer T1 directly converts the 50Hz AC mains voltage into dual positive and negative voltages. A voltage regulator U2 steps it down to +12V to power relay K1, and another voltage regulator U1 steps it down to +5V to power MCU module 1. A voltage regulator U3 outputs -12V to power the CP communication module 7-12V. Compared to commercially available switching power supplies, this AC / DC module 2 eliminates the need for EMI and driver chips due to the absence of high-frequency signals.

[0040] In this case, relay K1 is a magnetic latching relay, which has two sets of normally open contacts and two sets of coils. One end of the normally open contact is the input terminal, and the other end is the output terminal. One normally open contact is connected to the L pole of the AC power supply, and the other normally open contact is connected to the N pole of the AC power supply. The two sets of coils are defined as the first coil and the second coil, respectively. Energizing the first coil can drive relay K1 to open, and energizing the second coil can drive relay K1 to close, allowing the charger to charge. Choosing the magnetic latching relay K1 can reduce power consumption and effectively reduce the size of the power frequency transformer T1.

[0041] The relay drive control module includes a relay disconnect drive unit 41 and a relay engage drive unit 42. The MCU module 1 has a relay engage control terminal k1 and a relay disconnect control terminal k2. The relay disconnect drive unit 41 is connected to the relay disconnect control terminal k2 and the first coil of the magnetic latching relay K1. The relay disconnect drive unit 41 receives the disconnect command issued by the relay disconnect control terminal k2 and drives the magnetic latching relay K1 to disconnect. The relay engage drive unit 42 is connected to the relay engage control terminal k1 and the second coil of the magnetic latching relay K1. The relay engage drive unit 42 receives the engage command issued by the relay engage control terminal k1 and drives the magnetic latching relay K1 to engage.

[0042] Specifically, the relay disconnect drive unit 41 includes a diode D6, a capacitor C12, resistors R13, R14, R18, and R19, transistors Q3 and Q4, and a PMOS transistor Q1. The anode of diode D6 is connected to V+, and the cathode of diode D6 is connected to one end of capacitor C12, one end of resistor R13, one end of resistor R14, and the source of PMOS transistor Q1. The other end of capacitor C12 is grounded. The other end of resistor R14 is connected to the collector of transistor Q4, the base of transistor Q3, and one end of resistor R18. The base of transistor Q4 is connected to one end of resistor R19, one end of resistor R17, and one end of capacitor C13. The other end of resistor R17 is connected to the relay disconnect control terminal k2. The other ends of capacitor C13, resistor R19, the emitter of transistor Q4, the other end of resistor R18, and the emitter of transistor Q3 are grounded. The collector of transistor Q3 is connected to one end of resistor R13 and the gate of PMOS transistor Q1. The drain of PMOS transistor Q1 is connected to one end of the first coil of magnetic latching relay K1. The other end of the first coil of magnetic latching relay K1 is grounded.

[0043] When the control circuit is powered on, AC / DC module 2 outputs DC voltage, which is stored through diode D6 and capacitor C12. This turns on transistor Q3 and PMOS transistor Q1, thus providing a turn-off signal to the magnetically latched relay K1, ensuring that relay K1 is not disconnected. After MCU module 1 is working normally, it outputs a high level through the relay activation control terminal k2 (IO port) of the MCU module, controlling transistor Q4 to conduct, thereby controlling transistor Q3 and PMOS transistor Q1 to be cut off, reducing standby power consumption. If it is necessary to control relay K1 to open, MCU module 1 outputs a low-level signal from the relay activation control terminal k2 until relay K1 is opened, and then outputs a high level.

[0044] The relay energizing drive unit 42 includes resistors R15 and R16 and an NMOS transistor Q2. The relay energizing control terminal k1 is connected to one end of resistor R16 and the gate of NMOS transistor Q2 via resistor R15. The other end of resistor R16 and the drain of NMOS transistor Q2 are grounded. The source of NMOS transistor Q2 is connected to one end of the second coil of magnetic latching relay K1. The other end of the second coil of magnetic latching relay K1 is connected to the cathode of diode D6. When relay K1 needs to be energized, MCU module 1 outputs a high-level signal from the relay energizing control terminal k1. At this time, NMOS transistor Q2 is turned on, K1-OUT is grounded, thereby energizing relay K1.

[0045] Additionally, a diode D5 is connected in parallel with the first coil of relay K1, with the anode of diode D5 grounded; a diode D4 is connected in parallel with the second coil of relay K1, with the cathode of diode D4 connected to the cathode of diode D6. By using diodes D5 and D4, voltage spikes can be absorbed when relay K1 is disconnected, thus preventing interference with the normal operation of other circuits.

[0046] The sampling input terminal of voltage sampling module 3 is connected to the secondary winding NS2 of the power frequency transformer, and the voltage feedback output terminal (V-SENSE) of voltage sampling module 3 is connected to MCU module 1 for voltage feedback. Specifically, voltage sampling module 3 includes resistors R4, R5, and R6, capacitors C7, C8, and C9, diodes D31 and D32, and operational amplifier U4. One end of resistor R4 is the sampling input terminal of voltage sampling module 3, and the other end of resistor R4 is connected to the non-inverting input terminal of operational amplifier U4, one end of resistor R6, one end of capacitor C8, the cathode of diode D31, and the anode of diode D32. The cathode of diode D32 is connected to VCC, and the anode of diode D31, the other end of capacitor C8, and the other end of resistor R6 are grounded. The inverting input and output terminals of operational amplifier U4 are connected to one end of resistor R5. The other end of resistor R5 serves as the voltage feedback output (V-SENSE) of voltage sampling module 3. This voltage feedback output (V-SENSE) is connected to one end of capacitor C9, and the other end of capacitor C9 is grounded. The negative terminal of the power supply of operational amplifier U4 is grounded, and the positive terminal of the power supply of operational amplifier U4 is connected to VCC and one end of capacitor C7, the other end of capacitor C7 being grounded. Operational amplifier U4 is a voltage follower and can filter out negative voltages. Figure 4 In the circuit, the non-inverting input is pin 3, the inverting input is pin 4, the output is pin 1, the negative power supply is pin 2, and the positive power supply is pin 6.

[0047] Voltage sampling module 3 acquires a lower 50Hz voltage from the secondary winding NS2 of the power frequency transformer T1. This voltage is then divided by resistors R4 and R6 to reduce the AC signal. The signal is then followed by operational amplifier U4, which filters out negative voltage signals, resulting in a 50Hz half-wave sine wave signal that is fed to microcontroller U8 for AD calculation. The main advantage of this voltage sampling module 3 is the absence of an isolated voltage transformer and metering chip.

[0048] The relay sticking detection module 5 includes diode D7, resistors R20, R21, R22, R24, R25, R26, and R27, capacitor C14, and optocoupler U5. The L-terminal (LO) of the relay is connected to the anode of diode D7. The cathode of diode D7 is connected sequentially through resistors R25, R20, R21, and R22 to one end of resistor R26 and the anode of the light emitter of optocoupler U5. The other end of resistor R26 is connected to the cathode of the light emitter of optocoupler U5 and the N-terminal of the AC power supply. The collector of the light receiver of optocoupler U5 is connected to VCC. The emitter of the light receiver of optocoupler U5 is connected to one end of resistor R24, one end of resistor R27, and one end of capacitor C14. The other ends of resistor R24 ​​and capacitor C14 are grounded. The other end (NL) of resistor R27 is connected to MCU module 1 for relay sticking feedback. If the live wire of relay K1 is stuck, the charger is not allowed to charge. A diode D7, resistors R25, R20, R21, and R22, and optocoupler U5 are connected in series. One end is connected to the power output terminal LO, and the other end is connected to the power input terminal N. This system can detect the continuity and closure of the live wire of relay K1. If the L phase of relay K1 is stuck, optocoupler U5 is on, and a high level is output to MCU module 1 through resistor R27. If relay K1 is off, optocoupler U5 is off, and a low level is output to MCU module 1 through resistor R27, indicating that relay K1 is not stuck.

[0049] The ungrounded detection module 6 includes resistors R3, R7, R8, R9, R10, R11, R12, RD1, a ferrite bead L1, capacitors C10, C11, and CX1, and diodes D21 and D22. The L terminal of the AC power supply is connected to one end of capacitor CX1 and one end of resistor R12 via resistor R11. The other end of resistor R12 is connected to the N terminal of the AC power supply. The other end of capacitor CX1 is connected to one end of ferrite bead L1 and one end of capacitor C10 via resistors R10, R7, R9, R8, and R3. The other end of ferrite bead L1 is connected to one end of resistor RD1, one end of capacitor C11, the anode of diode D21, the cathode of diode D22, and the ungrounded feedback receiver (UG-7) of MCU module 1. The other ends of capacitor C10, resistor RD1, capacitor C11, and the anode of diode D22 are grounded. The cathode of diode D21 is connected to the power input terminal VDD of MCU module 1. The power input terminal VDD of MCU module 1 is connected to VCC through the power processing unit (capacitor C31, capacitor C33, capacitor C34 and inductor L2) to provide power protection for the microcontroller U8.

[0050] The voltage is divided by resistors R11 and R12, and power is drawn from the L and N terminals of the input power supply. The voltage is then stepped down by capacitor CX1, resistors R3, R7, R8, R9, R10 and RD1 to sample the AD signal, which is then sent to MCU module 1 for judgment. If a relatively high sine wave signal is detected, it indicates that the grounding is good; otherwise, it indicates that the grounding is not good.

[0051] The above description is only a preferred embodiment of the present utility model, but the protection scope of the present utility model is not limited thereto. Any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present utility model should be included within the protection scope of the present utility model.

Claims

1. An AC charger control circuit, characterized in that: Includes relays, MCU modules, AC / DC modules, voltage sampling modules, and relay drive control modules; The input terminal of the relay is connected to an AC power supply; The AC / DC module includes a power frequency transformer, a rectifier unit, and a step-down unit. The primary winding of the power frequency transformer is connected to an AC power source, the secondary winding of the power frequency transformer is connected to the input terminal of the rectifier unit, the output terminal of the rectifier unit is connected to the input terminal of the step-down unit, and the output terminal of the step-down unit provides operating voltage for the MCU module, the voltage sampling module, and the relay drive control module. The sampling input terminal of the voltage sampling module is connected to the secondary winding of the power frequency transformer, and the voltage feedback output terminal of the voltage sampling module is connected to the MCU module. The relay drive control module connects the MCU module and the relay. The relay drive control module receives instructions from the MCU module and drives the relay to engage or disengage.

2. The AC charger control circuit according to claim 1, characterized in that: The secondary winding of the power frequency transformer includes a primary winding and a secondary winding. The rectifier unit includes a first rectifier subunit and a second rectifier subunit. The step-down unit includes a first voltage regulator subunit, a second voltage regulator subunit, and a third voltage regulator subunit. The primary winding, the first rectifier subunit, the first voltage regulator subunit, and the second voltage regulator subunit are connected in sequence. The first voltage regulator subunit outputs a +12V voltage, and the second voltage regulator subunit outputs a +5V voltage. The secondary winding, the second rectifier subunit, and the third voltage regulator subunit are connected in sequence, and the third voltage regulator subunit outputs a -12V voltage.

3. The AC charger control circuit according to claim 2, characterized in that: The first rectifier subunit includes a rectifier bridge DB1 and a resistor R1; the second rectifier subunit includes a resistor R2 and a diode D1; the first voltage regulator subunit includes a voltage regulator U2, a capacitor C1, and a capacitor C3; the second voltage regulator subunit includes a voltage regulator U1, a capacitor C2, and a capacitor C4; and the third voltage regulator subunit includes a voltage regulator U3, a capacitor C5, and a capacitor C6. The primary winding NS1 is connected to the input terminal of the rectifier bridge DB1. The positive output terminal of the rectifier bridge DB1 is connected to one end of the resistor R1, one end of the capacitor C3, and the input terminal of the voltage regulator U2. The cathode output terminal of the rectifier bridge DB1, the other end of the resistor R1, the other end of the capacitor C3, and the ground terminal of the voltage regulator U2 are grounded. The output terminal of the voltage regulator U2 is connected to one end of the capacitor C1. One end of capacitor C4 is connected to the input terminal of voltage regulator U1, and the output terminal of voltage regulator U2 outputs a +12V voltage. The other end of capacitor C1, the other end of capacitor C4, and the ground terminal of voltage regulator U1 are grounded. The output terminal of voltage regulator U1 is grounded through capacitor C2, and the output terminal of voltage regulator U1 outputs a +5V voltage. One end of the secondary winding NS2 is connected to the sampling input terminal of the voltage sampling module, one end of resistor R2, and the cathode of diode D1. The anode of diode D1 is connected to one end of capacitor C6 and the input terminal of voltage regulator U3. The other end of the secondary winding NS2, the other end of resistor R2, the other end of capacitor C6, and the ground terminal of voltage regulator U3 are grounded. The output terminal of voltage regulator U3 is grounded through capacitor C5, and the output terminal of voltage regulator U3 outputs a -12V voltage.

4. The AC charger control circuit according to claim 2 or 3, characterized in that: It also includes a CP communication module, which is connected to the output terminal of the first voltage regulator subunit and the output terminal of the third voltage regulator subunit for power supply.

5. The AC charger control circuit according to claim 1, characterized in that: The voltage sampling module includes resistors R4, R5, and R6, capacitors C7, C8, and C9, diodes D31 and D32, and operational amplifier U4. One end of resistor R4 is the sampling input terminal of the voltage sampling module. The other end of resistor R4 is connected to the non-inverting input terminal of operational amplifier U4, one end of resistor R6, one end of capacitor C8, the cathode of diode D31, and the anode of diode D32. The cathode of diode D32 is connected to the output terminal of the buck converter. The anode of diode D31, the other end of capacitor C8, and the other end of resistor R6 are grounded. The inverting input terminal and output terminal of operational amplifier U4 are connected to one end of resistor R5. The other end of resistor R5 serves as the voltage feedback output terminal of the voltage sampling module. This voltage feedback output terminal is connected to one end of capacitor C9, and the other end of capacitor C9 is grounded. The negative terminal of the power supply of operational amplifier U4 is grounded, and the positive terminal of the power supply of operational amplifier U4 is connected to the output terminal of the buck converter and one end of capacitor C7. The other end of capacitor C7 is grounded.

6. The AC charger control circuit according to claim 1, characterized in that: The relay is a magnetic latching relay, which has a first coil and a second coil; the relay drive control module includes a relay disconnect drive unit and a relay engage drive unit, and the MCU module has a relay engage control terminal and a relay disconnect control terminal; the relay disconnect drive unit is connected to the relay disconnect control terminal and the first coil of the magnetic latching relay, and receives a disconnect command from the relay disconnect control terminal and drives the magnetic latching relay to disconnect; the relay engage drive unit is connected to the relay engage control terminal and the second coil of the magnetic latching relay, and receives an engage command from the relay engage control terminal and drives the magnetic latching relay to engage.

7. The AC charger control circuit according to claim 6, characterized in that: The relay disconnection drive unit includes diode D6, capacitor C12, resistors R13, R14, R18, and R19, transistors Q3 and Q4, and PMOS transistor Q1. The anode of diode D6 is connected to the output terminal of the step-down unit, and the cathode of diode D6 is connected to one end of capacitor C12, one end of resistor R13, one end of resistor R14, and the source of PMOS transistor Q1. The other end of capacitor C12 is grounded, and the other end of resistor R14 is connected to the collector of transistor Q4, the base of transistor Q3, and one end of resistor R18. The base of transistor Q4 is connected to one end of resistor R19, one end of resistor R17, and one end of capacitor C13. The other end of resistor R17 is connected to the relay disconnect control terminal. The other end of capacitor C13, the other end of resistor R19, the emitter of transistor Q4, the other end of resistor R18, and the emitter of transistor Q3 are grounded. The collector of transistor Q3 is connected to one end of resistor R13 and the gate of PMOS transistor Q1. The drain of PMOS transistor Q1 is connected to one end of the first coil of the magnetic latching relay. The other end of the first coil of the magnetic latching relay is grounded. The relay energizing drive unit includes resistors R15 and R16 and an NMOS transistor Q2. The relay energizing control terminal is connected to one end of resistor R16 and the gate of NMOS transistor Q2 via resistor R15. The other end of resistor R16 and the drain of NMOS transistor Q2 are grounded. The source of NMOS transistor Q2 is connected to one end of the second coil of the magnetic latching relay. The other end of the second coil of the magnetic latching relay is connected to the cathode of diode D6. The first coil of the relay is connected in parallel with diode D5, and the anode of diode D5 is grounded. The second coil of the relay is connected in parallel with diode D4, and the cathode of diode D4 is connected to the cathode of diode D6.

8. The AC charger control circuit according to claim 1, characterized in that: It also includes a relay adhesion detection module, which comprises a diode D7, resistors R20, R21, R22, R24, R25, R26, R27, capacitor C14, and optocoupler U5. The L-terminal output of the relay is connected to the anode of diode D7. The cathode of diode D7 is connected to one end of resistor R26 and the anode of the light emitter of optocoupler U5 via resistors R25, R20, R21, and R22. The other end of resistor R26 is connected to the cathode of the light emitter of optocoupler U5 and the N-terminal of the AC power supply. The collector of the photodetector of optocoupler U5 is connected to the output of the step-down unit. The emitter of the photodetector of optocoupler U5 is connected to one end of resistor R24, one end of resistor R27, and one end of capacitor C14. The other ends of resistor R24 ​​and capacitor C14 are grounded. The other end of resistor R27 is connected to the MCU module for relay adhesion feedback.

9. The AC charger control circuit according to claim 1, characterized in that: It also includes an ungrounded detection module. The MCU module is equipped with a power input terminal and an ungrounded feedback receiving terminal. The ungrounded detection module includes resistors R3, R7, R8, R9, R10, R11, R12, RD1, a ferrite bead L1, capacitors C10, C11, and CX1, diodes D21 and D22. The L terminal of the AC power supply is connected to one end of capacitor CX1 and one end of resistor R12 via resistor R11. The other end of resistor R12 is connected to the N terminal of the AC power supply. The other end of capacitor CX1 is connected to one end of ferrite bead L1 and one end of capacitor C10 via resistors R10, R7, R9, R8 and R3 in sequence. The other end of ferrite bead L1 is connected to one end of resistor RD1, one end of capacitor C11, the anode of diode D21, the cathode of diode D22 and the ungrounded feedback receiving end. The other ends of capacitor C10, resistor RD1, capacitor C11 and the anode of diode D22 are grounded. The cathode of diode D21 is connected to the power input end of the MCU module.

10. The AC charger control circuit according to claim 1, characterized in that: It also includes a current detection module, an indicator light module, a leakage current detection module, and a temperature detection module. The current detection module is connected to the input or output terminal of the relay to sample the current and feed it back to the MCU module; the indicator light module receives the electrical signal from the MCU module to provide light indication; the temperature detection module is connected to the MCU module and feeds back the charger temperature; the leakage current detection module is connected to the MCU module and feeds back whether the charger is leaking current.

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