CN114362381A - Overvoltage protection device for wireless charging system and control method thereof - Google Patents
Overvoltage protection device for wireless charging system and control method thereof Download PDFInfo
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- CN114362381A CN114362381A CN202111514498.XA CN202111514498A CN114362381A CN 114362381 A CN114362381 A CN 114362381A CN 202111514498 A CN202111514498 A CN 202111514498A CN 114362381 A CN114362381 A CN 114362381A
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Abstract
The invention belongs to the technical field of wireless charging, and particularly relates to an overvoltage protection device for a wireless charging system and a control method thereof. According to the invention, the receiving end protection module is arranged for cutting off the energy transmission of VRECT in a mode of short-circuiting double lower tubes of the rectifier bridge when the overvoltage comparator outputs a high level, simultaneously converting overvoltage information into a current form and feeding back the current form to the transmitting end protection module, detecting an inverted full-bridge current signal through the transmitting end protection module, judging the inverted full-bridge current signal to be in an overvoltage state after the peak current exceeds a preset limit value, and actively turning off the full bridge to cut off the energy transmission. According to the invention, when the overvoltage occurs at the wireless charging receiving end, the energy transmission from the rectifier bridge to the VRECT is cut off, so that the further increase of the VRECT overvoltage is avoided; meanwhile, the overvoltage state of the receiving end can be quickly fed back to the transmitting end in a current form, the transmitting end can sense the abnormity of current change in dozens of us, energy transmission is cut off from the source, and overvoltage damage is avoided.
Description
Technical Field
The invention belongs to the technical field of wireless charging, and particularly relates to an overvoltage protection device for a wireless charging system and a control method thereof.
Background
The wireless charging equipment of volume production in the market at present mostly adopts the electromagnetic induction principle, and whole wireless charging system includes transmitting terminal inverter circuit, transmitting coil, transmitting terminal demodulation modulation circuit, transmitting terminal controller, receiving terminal coil, receiving terminal rectifier circuit, receiving terminal modulation demodulation circuit, receiving terminal controller etc. constitute, and the system block diagram is as shown in fig. 1. The power path is characterized in that a transmitting end converts direct current into alternating current energy through an inverter circuit, a time-varying magnetic field is generated through a transmitting coil, alternating electromotive force is induced on a receiving coil by the time-varying magnetic field, and the energy is transmitted to a rear stage after rectification; and in the communication path, a receiving end carries out information transmission with a transmitting end in a 2kHz frequency by a load modulation mode, the working state of the receiving end is fed back, and a time delay of more than millisecond level exists between the power path and the communication path. When the system works, the receiving end is in a role of passively receiving energy, and when the coupling degree of the receiving end and the transmitting end or the load is suddenly changed, the consumed amount of the receiving end is smaller than the received energy, so that the receiving end is in overvoltage. Due to the large time delay of the communication path, an overvoltage state cannot be fed back to the transmitting end quickly, the receiving end cannot cut off energy transmission actively, and redundant energy can only be released by the overvoltage protection circuit, so that the receiving end can be damaged if the releasing capacity is not enough or the releasing is not timely.
At present, wireless charging overvoltage protection is basically realized by adding a leakage path at a receiving end. As shown in fig. 2, method 1 is implemented by means of a bleed resistor, when the VRECT voltage exceeds the OVP threshold, the output of the over-voltage comparator is high, the NMOS Q9 is driven to open, and the resistor R1 intervenes to provide a discharge path for VRECT; method 2 is implemented by means of a current source load, when the VRECT voltage exceeds the OVP threshold, the output of the overvoltage comparator is high, the NMOS Q10 is driven to be turned on, and the current source load intervenes to provide a discharge path for VRECT. The method 2 has controllable magnitude of the discharge current, can set different discharge energies according to the overvoltage condition, and is more flexible than the method 1. At present, overvoltage protection of a receiving end is basically realized through the two modes or the combination.
However, the conventional overvoltage protection method has obvious defects: after the receiving end is in overvoltage, overvoltage information needs to be transmitted to the transmitting end through a modulation signal, tens of milliseconds to hundreds of milliseconds are needed in the process, and the response speed is low; before the transmitting end actively adjusts the transmitting energy, the receiving end can be in an overvoltage state for a long time, and an overvoltage discharge protection circuit needs to intervene for a long time and is seriously heated, even can be damaged due to overheating. As shown in fig. 3, when VRECT is over-voltage, the discharging resistor and the dummy load intervene in discharging energy, meanwhile, the receiving end transmits over-voltage information to the transmitting end in an ASK modulation mode, and the transmitting end disconnects energy transmission after receiving the information; because the ASK information transmission time is between 20ms and 200ms, when serious overvoltage occurs, the system cannot rapidly disconnect energy transmission from a source; the power consumption of the discharge resistor or the dummy load when the OVP voltage is discharged can reach 2W-4W, the size of a receiving end is limited, the area of a discharge passage is smaller, and therefore the long-time intervention can also cause the damage of a discharge channel.
Disclosure of Invention
The invention provides an overvoltage protection device for a wireless charging system and a control method thereof, aiming at the problems, the overvoltage protection device can cut off the energy transmission from a rectifier bridge to VRECT when the wireless charging receiving end is in overvoltage, and the VRECT overvoltage is prevented from being further increased; meanwhile, the overvoltage state of the receiving end can be quickly fed back to the transmitting end in a current form, the transmitting end can sense the abnormity of current change within dozens of microseconds, energy transmission is cut off from the source, and loss is avoided.
The technical scheme of the invention is as follows:
an overvoltage protection device for a wireless charging system is shown in fig. 4, wherein the wireless charging system comprises a transmitting end inverter circuit, a transmitting coil, a receiving coil and a receiving end rectifying circuit which are sequentially connected; the transmitting end inverter circuit comprises a first switch tube, a second switch tube, a third switch tube and a fourth switch tube which form an inverter bridge, wherein the first switch tube and the third switch tube are upper tubes of the inverter bridge, and the second switch tube and the fourth switch tube are lower tubes of the inverter bridge; the receiving end rectifying circuit comprises a fifth switching tube, a sixth switching tube, a seventh switching tube and an eighth switching tube which form a rectifying bridge, wherein the fifth switching tube and the seventh switching tube are upper tubes of the rectifying bridge, and the sixth switching tube and the eighth switching tube are lower tubes of the rectifying bridge; the device also comprises a transmitting end protection module and a receiving end protection module;
the receiving end protection module is used for carrying out overvoltage detection on the output voltage VRECT of the receiving end rectifying circuit, cutting off energy transmission of VRECT in a mode of short-circuiting double lower tubes of a rectifying bridge when an overvoltage signal is detected, and converting overvoltage information into a current form to be fed back to the transmitting end protection module;
the transmitting terminal protection module is used for receiving overvoltage information of a receiving terminal, actively turning off the full bridge and disconnecting energy transmission by detecting an inverted full bridge current signal and after a peak current exceeds a preset limit value.
The scheme is the general technical scheme of the invention, and is different from the traditional scheme in that the transmission of energy to VRECT can be cut off by directly controlling the working mode of a rectifier bridge through an overvoltage protection module at a receiving end, an overvoltage signal is converted into a current signal to be reflected to a transmitting end, and after the transmitting end senses the sudden change of the current, the energy output is cut off from the source; the scheme has higher response speed compared with the traditional scheme.
Furthermore, the receiving end protection module comprises an overvoltage detection unit and a protection action instruction control unit;
the overvoltage detection unit compares VRECT and VOP, and outputs a high level when VRECT exceeds VOP, wherein VOP is defined as a preset threshold voltage;
the protection action instruction control unit receives a signal output by the overvoltage detection unit, generates a rectifier bridge control instruction for controlling the rectifier bridge when the overvoltage detection unit outputs a high level, and is specifically connected to a lower tube of the rectifier bridge, namely a sixth switching tube and an eighth switching tube, and the sixth switching tube and the eighth switching tube are conducted according to the received rectifier bridge control instruction;
further, the overvoltage detection unit is an overvoltage comparator, and two input ends of the overvoltage detection unit are VRECT and VOP respectively.
The above scheme is a common implementation manner of the over-voltage detection unit.
Furthermore, the overvoltage protection device further comprises a rectification control module, wherein the rectification control module controls synchronous rectification logic of the receiving end rectifier bridge, receives an instruction of the receiving end overvoltage protection module, exits from a synchronous rectification mode when overvoltage occurs, and turns on the sixth switching tube and the eighth switching tube according to preset logic.
Further, the transmitting terminal protection module comprises a current detection unit and a protection logic unit;
furthermore, the overvoltage protection device further comprises a full-bridge control module, wherein the full-bridge control module is used for controlling a full-bridge inverter circuit composed of a first switch tube, a second switch tube, a third switch tube and a fourth switch tube, and is also controlled by the transmitting terminal protection logic unit.
A control method for an overvoltage protection device of a wireless charging system defines that a current signal of a connection point of a sixth switching tube and a receiving coil of a fifth switching tube and a lower tube of the fifth switching tube is AC2, and a current signal of a connection point of an eighth switching tube and the receiving coil of a seventh switching tube and a lower tube of the seventh switching tube is AC1, and specifically comprises the following steps:
after the overvoltage comparator outputs a high level, the receiving end protection module judges the levels of AC1 and AC2, if AC1 is low, the eighth switching tube is firstly opened and is kept in an open state, and when the AC2 is low in the next half cycle, the sixth switching tube is opened and is kept in the open state; if the AC2 is low, the sixth switch tube is firstly turned on and is maintained in the on state, and when the AC1 is low in the next half cycle, the eighth switch tube is turned on and is maintained in the on state;
the transmitting terminal protection module samples the currents of a first switching tube and a third switching tube of an inverter bridge, and the currents are defined as IQ1 and IQ3 respectively; the ILIM1 is defined as a primary threshold current for the transmit side to trigger the top-tube over-current protection, and the ILIM2 is defined as a secondary threshold current for the transmit side to trigger the top-tube over-current protection. If the ILIM1 is not less than IQ1 and not more than ILIM2, the first switch tube is turned off, the second switch tube is turned on, and the transmitting end inverter circuit is turned off when all four continuous periods are that the ILIM1 is not less than IQ1 and not more than ILIM 2; if the ILIM1 is not less than IQ3 and not more than ILIM2, turning off the third switch tube and turning on the fourth switch tube, and when the continuous four periods are all that the ILIM1 is not less than IQ3 and not more than ILIM2, turning off the transmitting end inverter circuit; if IQ1> ILIM2 or IQ3> ILIM2, the transmit side inverter circuit is turned off.
The invention has the beneficial effects that: the invention can accelerate the response speed of overvoltage protection of the receiving end and improve the reliability of the wireless charging system; when the receiving end is in a limit voltage-resistant scene, the energy transmission can be quickly cut off, overvoltage damage of the receiving end is avoided, and the response speed is increased from dozens of ms to dozens of us.
Drawings
Fig. 1 is a block diagram of a wireless charging system.
Fig. 2 is a schematic diagram of a conventional overvoltage protection.
Fig. 3 is a schematic diagram of a conventional overvoltage protection process.
Fig. 4 is a schematic diagram of the overvoltage protection of the present invention.
Fig. 5 is a schematic diagram of the overvoltage protection process of the present invention.
Detailed Description
The invention is further described below with reference to the accompanying drawings.
The structure of the device of the present invention is described in detail in the summary of the invention, the overvoltage protection process of the present invention is shown in fig. 5, and compared with the conventional overvoltage protection process shown in fig. 3, after overvoltage is detected, the present invention controls the rectifier bridge through the protection module to perform overvoltage protection, specifically:
the receiving end protection module comprises an overvoltage detection and overvoltage protection action control submodule, and the transmitting end protection module comprises a current detection and protection logic control submodule; when the receiving end outputs the rectified output voltage VRECT and generates overvoltage, the overvoltage detection module detects that the overvoltage state is transmitted to the receiving end protection action control module, and the protection action control module controls the rectifier to exit a synchronous rectification mode; then detecting the levels of AC1 and AC2, if AC1 is low, turning on a lower tube Q8 on the side of AC1, and waiting until AC2 is low, turning on a lower tube Q6 of AC2, wherein the lower tubes Q6 and Q8 of a rectifier are simultaneously in an on state, the levels of AC1 and AC2 are both low, a path for providing energy for VRECT is cut off, and the VRECT voltage starts to fall; the lower tubes are both in an open state by AC1 and AC2, and are similar to a short-circuit state output by a receiving end, the current of the coil at the receiving end rapidly rises, and the current of the coil at the transmitting end and the current of the full-bridge tube simultaneously rapidly rise; the emitting end current detection module detects the currents of the upper tubes Q1 and Q3, taking the current detection and protection action of Q1 as an example, the detection and protection logic of Q3 is the same as that of Q1; when the current ILIM1 of Q1 is more than or equal to IQ1 and more than or equal to ILIM2, turning off Q1 and turning on Q2, and when all four continuous periods are that ILIM1 is more than or equal to IQ1 and more than or equal to ILIM2, turning off the inverter circuit at the transmitting end; when IQ1> ILIM2, rapidly turning off the inverter circuit at the transmitting end; the energy transfer is closed and the overvoltage protection state is over.
Claims (7)
1. An overvoltage protection device for a wireless charging system comprises a transmitting end inverter circuit, a transmitting coil, a receiving coil and a receiving end rectifying circuit which are sequentially connected; the transmitting end inverter circuit comprises a first switch tube, a second switch tube, a third switch tube and a fourth switch tube which form an inverter bridge, wherein the first switch tube and the third switch tube are upper tubes of the inverter bridge, and the second switch tube and the fourth switch tube are lower tubes of the inverter bridge; the receiving end rectifying circuit comprises a fifth switching tube, a sixth switching tube, a seventh switching tube and an eighth switching tube which form a rectifying bridge, wherein the fifth switching tube and the seventh switching tube are upper tubes of the rectifying bridge, and the sixth switching tube and the eighth switching tube are lower tubes of the rectifying bridge; the device is characterized by also comprising a transmitting end protection module and a receiving end protection module;
the receiving end protection module is used for carrying out overvoltage detection on the output voltage VRECT of the receiving end rectifying circuit, cutting off energy transmission of VRECT in a mode of short-circuiting double lower tubes of a rectifying bridge when an overvoltage signal is detected, and converting overvoltage information into a current form to be fed back to the transmitting end protection module;
the transmitting terminal protection module is used for receiving overvoltage information of a receiving terminal, actively turning off the full bridge and disconnecting energy transmission by detecting an inverted full bridge current signal and after a peak current exceeds a preset limit value.
2. The overvoltage protection device for the wireless charging system according to claim 1, wherein the receiving end protection module comprises an overvoltage detection unit and a protection action instruction control unit;
the overvoltage detection unit compares VRECT and VOP, and outputs a high level when VRECT exceeds VOP, wherein VOP is defined as a preset threshold voltage;
the protection action instruction control unit receives a signal output by the overvoltage detection unit, generates a rectifier bridge control instruction for controlling the rectifier bridge when the overvoltage detection unit outputs a high level, and is specifically connected to a lower tube of the rectifier bridge, namely a sixth switching tube and an eighth switching tube, and the sixth switching tube and the eighth switching tube are conducted according to the received rectifier bridge control instruction.
3. The overvoltage protection device for the wireless charging system according to claim 2, wherein the overvoltage detection unit is an overvoltage comparator, and two input terminals of the overvoltage comparator are VRECT and VOP respectively.
4. The overvoltage protection device for the wireless charging system according to claim 2, wherein the overvoltage protection device further comprises a rectification control module, the rectification control module controls a synchronous rectification logic of the receiving-end rectifier bridge, and simultaneously receives an instruction of the receiving-end overvoltage protection module, when overvoltage occurs, the synchronous rectification mode is exited, and the sixth switching tube and the eighth switching tube are turned on according to a preset logic.
5. The overvoltage protection device for the wireless charging system according to claim 4, wherein the transmitting end protection module comprises a current detection unit and a protection logic unit;
the current detection unit is connected to the connection ends of the first switching tube and the third switching tube and external input voltage, so that an inverted full-bridge current signal is detected in real time;
the protection logic unit judges the output signal of the current detection unit in real time, when the current flowing through the first switching tube and the third switching tube exceeds a preset threshold value, the protection logic unit judges that an overvoltage signal appears at a receiving end, immediately controls the full-bridge control module to be closed, and stops energy transmission.
6. The overvoltage protection device for the wireless charging system according to claim 5, further comprising a full bridge control module, wherein the full bridge control module is configured to control a full bridge inverter circuit formed by the first switch tube, the second switch tube, the third switch tube and the fourth switch tube, and is also controlled by the transmit end protection logic unit.
7. The control method of the overvoltage protection device for the wireless charging system as claimed in any one of claims 1 to 6, defining the connection point current signal of the sixth switching tube and the receiving coil of the fifth switching tube and its lower tube as AC2, and the connection point current signal of the eighth switching tube and the receiving coil of the seventh switching tube and its lower tube as AC1, wherein:
when an overvoltage signal is detected, the receiving end protection module judges the levels of AC1 and AC2, if AC1 is low, the eighth switching tube is turned on, and when the AC2 in the next half cycle is low, the sixth switching tube is turned on; if the AC2 is low, the sixth switch tube is turned on, and when the AC1 is low in the next half cycle, the eighth switch tube is turned on;
the transmitting terminal protection module samples the currents of a first switching tube and a third switching tube of an inverter bridge, and the currents are defined as IQ1 and IQ3 respectively; defining ILIM1 as a primary threshold current of the transmitting terminal triggering the over-current protection, and ILIM2 as a secondary threshold current of the transmitting terminal triggering the over-current protection; if the ILIM1 is not less than IQ1 and not more than ILIM2, the first switch tube is turned off, the second switch tube is turned on, and the transmitting end inverter circuit is turned off when all four continuous periods are that the ILIM1 is not less than IQ1 and not more than ILIM 2; if the ILIM1 is not less than IQ3 and not more than ILIM2, turning off the third switch tube and turning on the fourth switch tube, and when the continuous four periods are all that the ILIM1 is not less than IQ3 and not more than ILIM2, turning off the transmitting end inverter circuit; if IQ1> ILIM2 or IQ3> ILIM2, the transmit side inverter circuit is turned off.
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Citations (6)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN105071551A (en) * | 2015-07-28 | 2015-11-18 | 奇瑞汽车股份有限公司 | Wireless energy transmission device |
| CN109314408A (en) * | 2016-07-27 | 2019-02-05 | 曼珀斯有限公司 | Control the wireless power receiver of signal of communication size |
| CN109494840A (en) * | 2018-12-21 | 2019-03-19 | 中惠创智无线供电技术有限公司 | A kind of dynamic radio charging system and its receiving terminal circuit and protection control method |
| CN110518706A (en) * | 2019-08-09 | 2019-11-29 | 深圳智链物联科技有限公司 | A kind of wireless charging device and its protection circuit |
| CN111211591A (en) * | 2018-11-22 | 2020-05-29 | 美芯晟科技（北京）有限公司 | Overvoltage protection method, overvoltage protection circuit and wireless charging system |
| CN112542899A (en) * | 2019-09-23 | 2021-03-23 | 意法半导体亚太私人有限公司 | Advanced overvoltage protection strategy for wireless power transfer |
-
2021
- 2021-12-13 CN CN202111514498.XA patent/CN114362381B/en active Active
Patent Citations (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN105071551A (en) * | 2015-07-28 | 2015-11-18 | 奇瑞汽车股份有限公司 | Wireless energy transmission device |
| CN109314408A (en) * | 2016-07-27 | 2019-02-05 | 曼珀斯有限公司 | Control the wireless power receiver of signal of communication size |
| CN111211591A (en) * | 2018-11-22 | 2020-05-29 | 美芯晟科技（北京）有限公司 | Overvoltage protection method, overvoltage protection circuit and wireless charging system |
| CN109494840A (en) * | 2018-12-21 | 2019-03-19 | 中惠创智无线供电技术有限公司 | A kind of dynamic radio charging system and its receiving terminal circuit and protection control method |
| CN110518706A (en) * | 2019-08-09 | 2019-11-29 | 深圳智链物联科技有限公司 | A kind of wireless charging device and its protection circuit |
| CN112542899A (en) * | 2019-09-23 | 2021-03-23 | 意法半导体亚太私人有限公司 | Advanced overvoltage protection strategy for wireless power transfer |
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