Low radiation vehicle-mounted wireless charger

Abstract

A kind of low radiation vehicle-mounted wireless charger, including wireless charging circuit arranged in shell, the wireless charging circuit includes control chip and LC resonant circuit module connected with the control chip, the control chip is configured as: S101, in standby state, with 200-300ms transmission cycle, first signal is periodically sent to the LC resonant circuit module, make the LC resonant circuit module generate oscillation signal, the voltage of the first signal is 2-3.3V;S102, detect the energy loss of the oscillation signal in the preset time period, if the energy loss is greater than loss threshold, then send second signal to the LC resonant circuit module, make the LC resonant circuit module generate PING signal.The present application overcomes the prior art in standby state by PING signal detection is charged equipment and causes electromagnetic radiation to be seriously overproof, influence driving and personal safety problem, safe and reliable.

Description

Technical Field

[0001] This invention belongs to the field of vehicle wireless charging technology, and particularly relates to a low-radiation vehicle wireless charger. Background Technology

[0002] Currently, most car wireless chargers on the market continuously and periodically send PING signals through their transmitting coils when in standby mode to detect whether a device is being charged on the charger. Therefore, when the device is not being charged and is not placed on the wireless charger, the PING signal is not received by the receiving coil of the device, causing the energy of the PING signal to be directly emitted into the air, resulting in serious electromagnetic radiation exceeding the standard and affecting driving and personal safety. Summary of the Invention

[0003] Based on this, and to address the aforementioned technical issues, a low-radiation vehicle-mounted wireless charger is provided.

[0004] To solve the above-mentioned technical problems, the present invention adopts the following technical solution:

[0005] A low-radiation in-vehicle wireless charger includes a wireless charging circuit disposed within a housing. The wireless charging circuit includes a control chip and an LC resonant circuit module connected to the control chip. The control chip is characterized in that it is configured to:

[0006] S101. In standby mode, a first signal is periodically sent to the LC resonant circuit module with a transmission period of 200-300ms, so that the LC resonant circuit module generates an oscillation signal, and the voltage of the first signal is 2-3.3V.

[0007] S102. Detect the energy loss of the oscillation signal within a preset time period. If the energy loss is greater than the loss threshold, send a second signal to the LC resonant circuit module to make the LC resonant circuit module generate a PING signal.

[0008] This invention sends a first signal to the LC resonant circuit module only in standby mode. This signal has low energy (voltage of 2-3.3V) and a short transmission time (transmission period of 200-300ms). The first signal causes the LC resonant circuit module to generate an oscillation signal, which greatly reduces the electromagnetic radiation generated by the charger in standby mode. By detecting the energy loss of the oscillation signal within a preset time period, it can be determined whether a device is placed on the charger. When a device is placed on the charger, the LC resonant circuit module generates a PING signal to establish handshake communication with the device. This invention overcomes the problem of excessive electromagnetic radiation caused by detecting the device in standby mode using a PING signal, which affects driving and personal safety. It is safe and reliable. Attached Figure Description

[0009] Figure 1 This is a schematic diagram of the structure of the present invention;

[0010] Figure 2 This is a schematic diagram of the wireless charging circuit of the present invention;

[0011] Figure 3 This is a schematic diagram of the transmitting coil of the present invention. Detailed Implementation

[0012] The embodiments of the present invention will be described below with reference to the accompanying drawings. It should be noted that the embodiments described in this specification are not exhaustive and do not represent the only embodiments of the present invention. The corresponding embodiments below are only for clearly illustrating the inventive content of this patent and are not intended to limit its implementation. For those skilled in the art, different variations and modifications can be made based on the embodiments described. Any variations or modifications that fall within the technical concept and inventive content of this invention and are obvious are also within the protection scope of this invention.

[0013] like Figure 1 As shown, this embodiment provides a low-radiation vehicle-mounted wireless charger, including a housing 110 and a wireless charging circuit 120 disposed on a circuit board inside the housing 110.

[0014] like Figure 2 As shown, the wireless charging circuit 120 includes an anti-reverse filtering module 121, a Buck-Boost module 122, an LDO power supply module 123, a sampling resistor 124, a full-bridge inverter module 125, an LC resonant circuit module 126, a Qi authentication chip 127, an NTC resistor 128, a demodulation circuit module (not shown in the figure), and a control chip 129.

[0015] The anti-reverse filtering module 121 is connected to the Buck-Boost module 122 and the LDO power supply module 123. The Buck-Boost module 122 is connected to the full-bridge inverter module 125 via the sampling resistor 124. The LDO power supply module 123 is connected to the control chip 129. The two ends of the sampling resistor 124 are connected to the control chip 129. The full-bridge inverter module 125 is connected to the LC resonant circuit module 126. The Qi authentication chip 127 and the NTC resistor 128 are connected to the control chip 129. The demodulation circuit module is connected between the LC resonant circuit module 126 and the control chip 129. The control chip 129 is connected to the full-bridge inverter module 125.

[0016] Among them, the anti-reverse filtering module 121 is used to connect to the car battery and plays the role of anti-reverse connection and filtering.

[0017] Buck-Boost module 122 is used to regulate the output voltage to regulate the charging output power. Buck-Boost module 122 outputs DC voltage to full-bridge inverter module 125.

[0018] The LDO power supply module 123 provides a 5V operating voltage to the control chip 129.

[0019] The sampling resistor 124 is used to sample the output current and output voltage values ​​of the Buck-Boost module 122, and then input them to the control chip 129 to calculate the input power of the wireless charger.

[0020] The Qi authentication chip 127 uses the Q1.3 authentication chip. Based on this chip, the charger and the device being charged can authenticate each other before charging, ensuring that power transfer can only proceed after successful authentication. Multiple NTC resistors 128 are used to detect the temperature of the circuit board and the transmitting coil 126a of the LC resonant circuit module 126. When the temperature is too high, the control chip 129 stops charging to achieve over-temperature protection and improve safety.

[0021] In operation, the control chip 129 controls the full-bridge inverter module 125, causing the full-bridge inverter module 125 to chop the DC voltage output by the Buck-Boost module 122 into a 125kHz square wave, which is then input to the LC resonant circuit module 126. The transmitting coil 126a of the LC resonant circuit module 126 transmits energy to the receiving coil of the device being charged through a magnetic field.

[0022] The full-bridge inverter module 125 consists of four NMOS switches, such as... Figure 2 As shown, four NMOS switches generate square wave signals between the bridge arm nodes at SW1 and SW2. The square wave signals are applied across the two ends of the LC resonant circuit module 126 to generate an alternating current. The alternating current generates a magnetic field through the transmitting coil 126a.

[0023] To avoid magnetic leakage and improve charging efficiency, such as Figure 3 As shown, a magnetic shielding plate 126b is provided on the other side of the transmitting coil 126a opposite to its charging and transmitting surface, and the magnetic shielding plate 126b is bonded to the transmitting coil 126a.

[0024] To reduce the electromagnetic radiation emitted by the charger when in standby mode, the control chip 129 is configured as follows:

[0025] S101. In standby mode, a first signal is periodically sent to the LC resonant circuit module 126 with a transmission period of 200-300ms, so that the LC resonant circuit module 126 generates an oscillation signal. The voltage of the first signal is 2-3.3V.

[0026] In standby mode, the full-bridge inverter module 125 is turned off, and the first signal is generated autonomously by the control chip 129 and sent to the LC resonant circuit module 126 via pins SW1 and SW2.

[0027] S102. Detect and determine whether the energy loss of the oscillation signal within a preset time period is greater than the loss threshold. If so, send a second signal to the LC resonant circuit module 126 to cause the LC resonant circuit module 126 to generate a PING signal. The preset time period is less than the transmission period.

[0028] To avoid potential errors from a single sampling, the energy loss of the oscillation signal within a preset time period can be detected and determined in two consecutive transmission cycles. If both are true, a second signal is sent to the LC resonant circuit module to generate a PING signal.

[0029] The control chip 129 controls the full-bridge inverter module 125 to turn on via the DRVH and DRVL pins, so that the DC voltage output by the Buck-Boost module 122 generates a second signal through the full-bridge inverter module 125. The voltage of the second signal is usually around 6V, which exceeds the radiation standard.

[0030] The quality factor q can be used to characterize the energy loss of an oscillating signal. The larger the q value, the smaller the loss, and vice versa. When a device is placed on the charger, the q value decreases rapidly due to absorption by the receiving coil of the device. When no device is placed on the charger, the energy of the oscillating signal is slowly absorbed through the internal resistance of the components, and the q value decreases more slowly. Therefore, this invention can characterize the energy loss of the oscillating signal within the preset time period using the q value of the LC resonant circuit module 126, thereby determining whether the energy loss exceeds the loss threshold. The specific process is as follows:

[0031] First, the number of pulses (target pulses) with a pulse width greater than a specified voltage within a preset time period is detected, CountN, where pulse width refers to the maximum voltage that the pulse can reach.

[0032] Then, the q value of the LC resonant circuit module 126 within a preset time period is calculated using the following formula:

[0033]

[0034] Where t0 and t1 represent the start and end times of the preset time period, respectively, and V(t0) and V(t1) represent the voltages at the start and end times, respectively, which can be obtained through the demodulation circuit, specifying that the voltage is less than V(t0) and greater than or equal to V(t1). The above formula is derived based on the ratio of the inductive reactance to the equivalent resistance of the LC resonant circuit module 126 when it operates under an AC voltage at a certain frequency.

[0035] Finally, it is determined whether the q value is less than the threshold Q. If so, it means that the energy loss of the oscillation signal within the preset time period is greater than the loss threshold. Then, a second signal is sent to the LC resonant circuit module 126 to generate a PING signal. The PING signal can be used to communicate with the device being charged. After the handshake is successful, the brand information of the device being charged and the energy intensity transmitted are confirmed by transmitting the corresponding data packets, and the wireless charging stage is entered.

[0036] It should be noted that if the specified voltage is too large, the number of target pulses will be too small; if it is too small, the target pulse sampling will be inaccurate. Therefore, in a preferred embodiment, the specified voltage is equal to V(t1).

[0037] In one example, the transmission period is 260ms, the voltage of the detection signal is 3.3V, t0 is the start time of the oscillation signal, V(t0) is 3.3V, and V(t1) and the specified voltage are both 0.2V.

[0038] As can be seen from the above, in the standby state, the present invention only sends a first signal to the LC resonant circuit module 126. This signal has low energy (voltage of 2-3.3V) and short transmission time (transmission period of 200-300ms). The first signal causes the LC resonant circuit module to generate an oscillation signal, which greatly reduces the electromagnetic radiation generated by the charger in the standby state. By detecting the energy loss of the oscillation signal within a preset time period, it can be determined whether there is a device to be charged on the charger. When there is a device to be charged on the charger, the LC resonant circuit module generates a PING signal to establish handshake communication with the device to be charged. This overcomes the problem in the prior art that the electromagnetic radiation caused by detecting the device to be charged by the PING signal in the standby state is seriously excessive, affecting driving and personal safety. It is safe and reliable.

[0039] Obviously, those skilled in the art should recognize that the above embodiments are only used to illustrate the present invention and are not intended to limit the present invention. Any changes or modifications to the above embodiments that are within the essential spirit of the present invention will fall within the scope of the claims of the present invention.

Claims

1. A low-radiation vehicle-mounted wireless charger, comprising a wireless charging circuit disposed within a housing, the wireless charging circuit including a control chip and an LC resonant circuit module connected to the control chip, characterized in that, The control chip is configured as follows: S101. In standby mode, a first signal is periodically sent to the LC resonant circuit module with a transmission period of 200-300ms, so that the LC resonant circuit module generates an oscillation signal, and the voltage of the first signal is 2-3.3V. S102. Detect and determine whether the energy loss of the oscillation signal within a preset time period is greater than the loss threshold. If so, send a second signal to the LC resonant circuit module to make the LC resonant circuit module generate a PING signal. The step of detecting and determining whether the energy loss of the oscillation signal within a preset time period is greater than a loss threshold further includes: The number of pulses with a pulse width greater than a specified voltage, CountN, is detected within the preset time period of the oscillation signal, where the pulse width is the maximum voltage that the pulse can reach. The q value of the LC resonant circuit module during the preset time period is calculated using the following formula: Wherein, t0 and t1 represent the start and end times of the preset time period, respectively, and V(t0) and V(t1) represent the voltage of the oscillation signal at the start and end times, respectively, and the specified voltage is less than V(t0) and greater than or equal to V(t1); Determine whether the q value is less than the threshold Q. If it is, it means that the energy loss of the oscillation signal within the preset time period is greater than the loss threshold.

2. The low-radiation vehicle-mounted wireless charger according to claim 1, characterized in that, S102 further includes: In two consecutive transmission cycles, it is detected and determined whether the energy loss of the oscillation signal within a preset time period is greater than the loss threshold. If both are true, a second signal is sent to the LC resonant circuit module to generate a PING signal.

3. A low-radiation vehicle-mounted wireless charger according to claim 2, characterized in that, The specified voltage is equal to V(t1).

4. A low-radiation vehicle-mounted wireless charger according to claim 3, characterized in that, The transmission period is 260ms, the voltage of the first signal is 3.3V, t0 is the start time of the oscillation signal, V(t0) is 3.3V, and V(t1) and the specified voltage are both 0.2V.

5. A low-radiation vehicle-mounted wireless charger according to any one of claims 1-4, characterized in that, The wireless charging circuit further includes an anti-reverse filtering module, a Buck-Boost module, an LDO power supply module, a sampling resistor, a full-bridge inverter module, a Qi authentication chip, an NTC resistor, and a demodulation circuit module. The anti-reverse filtering module is connected to the Buck-Boost module and the LDO power supply module. The Buck-Boost module is connected to the full-bridge inverter module via the sampling resistor. The LDO power supply module is connected to the control chip. The two ends of the sampling resistor are connected to the control chip. The full-bridge inverter module is connected to the LC resonant circuit module. The Qi authentication chip and the NTC resistor are connected to the control chip. The demodulation circuit module is connected between the LC resonant circuit module and the control chip. The control chip is connected to the full-bridge inverter module.

6. A low-radiation vehicle-mounted wireless charger according to claim 5, characterized in that, S101 includes: The first signal is generated autonomously.

7. A low-radiation vehicle-mounted wireless charger according to claim 6, characterized in that, S102 further includes: The full-bridge inverter module is turned on, so that the DC voltage output by the Buck-Boost module is used to generate the second signal through the full-bridge inverter module.

8. A low-radiation vehicle-mounted wireless charger according to claim 7, characterized in that, The LC resonant circuit module has a magnetic shielding plate on the other side of its emitting surface opposite to the emitting coil, and the magnetic shielding plate is bonded to the emitting coil.

9. A low-radiation vehicle-mounted wireless charger according to claim 8, characterized in that, The Qi authentication chip used is the Q1.3 authentication chip.

Images