Voltage spike protection circuit and protection method for wireless power transmission inverter and application

Abstract

The invention provides a voltage spike protection circuit and protection method for a wireless power transmission inverter and application, belongs to the technical field of wireless power transmission, and solves the problems that when an existing wireless power transmission system deals with special working conditions, voltage spikes are likely to be generated, so that the pressure of a device is increased, and the inverter does not have the voltage spike protection function. The protection circuit comprises a high-frequency differential sampling module, a high-speed comparison module, a physical reset key, an optocoupler isolation module, a high-speed digital controller and a single-end driving module. The protection circuit can effectively detect peak voltage, hardware triggering and software triggering are combined, timely protection is achieved, equipment safety is guaranteed, the protection circuit is provided with an implementation path formed by a pure analog circuit, the overall response time is short, triggering is reliable, and the vacancy of inverter functions is filled.

Description

Technical Field

[0001] The invention relates to a voltage spike protection circuit, a protection method and an application of a wireless power transmission inverter, and belongs to the technical field of wireless power transmission. Background Art

[0002] Wireless Power Transfer (WPT) systems usually use inverters to generate high-frequency alternating current, which stimulates electromagnetic interaction in the coupling mechanism to achieve contactless energy transmission. With the advantages of safety and convenience, it has been widely used in electric vehicles, industrial automation, smart mines and other fields, and is developing towards high frequency, high power and high efficiency.

[0003] In wireless power transmission systems, the main function of high-frequency inverters is to convert direct current into high-frequency alternating current, thus playing a key role in improving transmission power and transmission efficiency in the system. However, inverters face some special challenges in the application process, such as high frequency, high voltage, high current and resonant load and other harsh working environments, which make it difficult to further improve the power and power density of the inverter. Existing power electronic devices have some limitations in high-frequency applications, such as low voltage and current withstand capacity at high frequency, significant reduction in voltage and current withstand capacity with increasing frequency, and high price of large-capacity power tubes. These factors restrict the performance improvement of wireless power transmission systems. Therefore, how to give full play to the performance of switching devices while ensuring the stability and reliability of the converter has become the current research focus. This requires the design of a protection circuit with fast response, high reliability and strong practicality to ensure that the switching devices do not exceed the limit conditions, give full play to the performance of the switching devices while ensuring the safe operation of the system.

[0004] The state of the inverter at the switching moment also has a direct impact on its performance. When in the soft switching state, the parasitic capacitance of the switch tube can be fully charged and discharged, and the di / dt at the switching moment is small, which is conducive to reducing the output voltage spike and further exerting the performance of the switch tube. However, as the soft switching depth increases or when it is in the hard switching state, the di / dt at the switching moment increases, resulting in an increase in the output voltage spike. Therefore, in the WPT system, the resonant cavity load is usually weakly inductive under ideal conditions. However, the resonant state of the resonant cavity load is highly sensitive, and it will fluctuate with changes in factors such as temperature and relative position, causing the output voltage spike to become larger, resulting in overvoltage breakdown of the inverter. At the same time, the high-frequency working environment will cause varying degrees of interference to the weak current circuit, increasing the difficulty of the protection circuit, further affecting the normal operation of the WPT system and even causing danger.

[0005] In response to these problems, the existing technology usually adopts additional series and parallel connection of switching devices and derating to ensure the normal operation of the system by expanding the margin. In order to further control costs and give full play to the performance of the switch tube, a protection measure based on the inverter output voltage platform to estimate the peak size has emerged. This method has expanded the scope of use of the switch tube to a certain extent, but its sampling circuit waveform restoration is poor and high-frequency spikes are easily lost. These methods have reduced the utilization rate of the switch tube to a certain extent, thereby limiting the power and power density improvement of the inverter, and hindering the further development of high-power wireless power transmission technology. Summary of the invention

[0006] The present invention aims to solve the problems that the existing wireless power transmission system is prone to generate voltage spikes when dealing with special working conditions, resulting in increased device pressure and the inverter does not have a voltage spike protection function, and further proposes a wireless power transmission inverter voltage spike protection circuit, protection method and application.

[0007] The technical solution adopted by the present invention to solve the above problems is: the voltage spike protection circuit of the wireless power transmission inverter proposed by the present invention comprises:

[0008] High-frequency differential sampling module, high-speed comparison module, physical reset button, optocoupler isolation module, high-speed digital controller and single-ended drive module;

[0009] The frequency differential sampling module is used to convert the inverter output voltage Vin+ and Vin- into a low-voltage high-frequency signal V out , and output the low-voltage high-frequency signal after proportional conversion as signal ①;

[0010] The high-speed comparison module has a self-locking function. The comparator compares the signal ① with the reference voltage V set Perform logical judgment, transmit the judgment information as signal ② to the optical coupling isolation module, and transmit the judgment result as signal ⑤ to the high-speed digital controller, wherein signal ② includes low level and high level states;

[0011] The physical reset button transmits the high-speed comparison module reset information as a signal ④ to the high-speed comparison module for a reset operation;

[0012] The optocoupler isolation module is used to remove the influence of signal ② on the driving circuit in the single-ended driving module and output signal ③;

[0013] The high-speed digital controller reads the judgment result of the high-speed comparison module by receiving signal ⑤, and transmits signal ⑥ to the high-speed comparison module to control the reset function of the high-speed comparison module after self-locking. At the same time, according to the read judgment result, the signal ⑦ is transmitted to the single-ended drive module to realize the detection and control of the single-ended drive module, so as to ensure that the information of signal ⑤ is accurately reflected;

[0014] The single-ended driver module controls the switching state of the switch tube by detecting the state of signal ③ to complete circuit protection.

[0015] Preferably, the high-frequency differential sampling module includes resistors R1 to R19, capacitors C1 to C10, diodes D1 to D4, and a first active voltage follower circuit, a second active voltage follower circuit, and a third active voltage follower circuit, and the high-speed comparison module is connected to the resistor R20;

[0016] A resistor R22 is provided on the connection circuit between the physical reset button and the high-speed digital controller;

[0017] The high-speed digital controller includes resistors R22 and R21, which are connected to a physical reset button through an emitter of an NPN transistor, a base stage is connected to a DSP through a current-limiting resistor R21, and is connected to a high-speed comparison module through a switch.

[0018] Preferably, the resistor R3 is a pull-up resistor, the resistor R15 is a pull-down resistor, and the resistor R21 is a current limiting resistor.

[0019] A voltage spike protection method for a wireless power transmission inverter, comprising:

[0020] Step 1: Input the inverter output voltage Vin+ and Vin- into the high-frequency differential sampling module to divide them into Vin1 and Vin2. Vin1 and Vin2 pass through the first active voltage follower circuit and the second active voltage follower circuit respectively and then merge into the third active voltage follower circuit. Combined with the target protection value and the weak current power supply range, the inverter output voltage is divided proportionally to determine V out1 , V out1 Transmitted as signal ① to the high-speed comparison module;

[0021] Step 2: According to the voltage division ratio and the frequency f of the inverter output voltage spike, adjust the capacitors C1-C10 of the passive device voltage division part to make the inverter internal circuit waveform before and after sampling consistent;

[0022] Step 3: Adjust resistor R3, resistor R15 and capacitors C2-C7 to eliminate the chip differences of the active voltage follower circuit provided by the DC power supply;

[0023] Step 4: According to the corresponding time requirements, select the corresponding high-speed comparison module with self-locking power supply, where the input voltage of the high-speed comparator meets

[0024] Step 5: Set the reference voltage V set , the high-speed comparison module compares the signal ① with the reference voltage V setPerform logical judgment, transmit the judgment information as signal ② to the optocoupler isolation module, and transmit the judgment result as signal ⑤ to the high-speed digital controller:;

[0025] Step 6: Connect the high-speed digital controller and the high-speed comparison module through the switch, and connect through the emitter of the NPN transistor and the physical reset button. The base is connected to the DSP through the current limiting resistor R21, and the resistor R20 and the hysteresis time are set by looking up the table;

[0026] Step 7: The physical reset button transmits signal ④ to reset the high-speed comparison module after self-locking, and the high-speed digital controller transmits signal ⑦ to the single-ended drive module according to the judgment result of reading the physical reset button to realize the detection and control of the single-ended drive module;

[0027] Step 8: Isolate signal ② and signal ③ through the optocoupler isolation module, and output signal ③ to drive the single-ended drive module to complete circuit protection;

[0028] V out1 The calculation formula is:

[0029]

[0030] In formula (1), the passive device voltage divider specifically refers to the sum of the resistances in the passive device voltage divider module;

[0031] The reference voltage is calculated as:

[0032]

[0033] Applications of wireless power transmission inverter voltage spike protection circuits include:

[0034] A DC power supply, an inverter, a transmitting coil, a receiving coil, a rectifier, a DC converter and a load connected in sequence;

[0035] The DC power supply is used to provide active voltage for the inverter;

[0036] The inverter uses a voltage spike protection circuit to perform voltage inversion and convert active current into AC power. When the peak of the inverter output voltage exceeds the limit, the internal circuit is triggered to switch the switch tube to complete the circuit protection.

[0037] The AC power is transmitted through the transmitting coil after passing through the compensation topology, and the receiving coil receives the compensated AC power through the compensation topology and is received by the DC converter;

[0038] The DC converter converts the received AC power into AC power;

[0039] The DC converter is used to convert high voltage AC power into low voltage AC power and transmit it to the load.

[0040] The beneficial effects of the present invention are:

[0041] 1. The voltage spike protection circuit proposed in the present invention can effectively detect the spike voltage, and combines hardware triggering with software triggering to achieve timely protection and ensure equipment safety. At the same time, the voltage divider circuit in the present invention has a high degree of restoration at high frequency and no waveform distortion. The protection circuit has an implementation path composed of a pure analog circuit, with a short overall response time and reliable triggering, filling the gap in the inverter function.

[0042] 2. Based on the accurate sampling and fast response of the protection circuit in the present invention, the switching frequency, voltage and current levels can be improved, which is conducive to further improving the power level, power density and system efficiency of the wireless power transmission system.

[0043] 3. The present invention is based on analog circuit detection, a composite protection combining hardware triggering and software triggering, and has higher reliability.

[0044] 4. The voltage spike protection method of the present invention is based on system indicators and device selection, and is feasible and universal. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] Figure 1 An application circuit diagram of an inverter with voltage spike protection function provided by the present invention;

[0046] Figure 2 A voltage spike protection circuit diagram of a wireless power transmission inverter provided by the present invention;

[0047] Figure 3 A schematic diagram of a flow chart of a voltage spike protection method for a wireless power transmission inverter provided by the present invention;

[0048] Figure 4 A schematic diagram of the specific internal circuit of the inverter provided by the present invention;

[0049] Figure 5 This is the experimental test waveform diagram of the high-frequency sampling module circuit provided by the present invention. Figure 5 In the figure, (a) is the test waveform diagram, and (b) is the test waveform detail diagram;

[0050] Figure 6 This is a trigger waveform diagram of the protection circuit provided by the present invention. DETAILED DESCRIPTION

[0051] Combination Figure 1-Figure 6 This embodiment is described as follows. Figure 1 and Figure 2As shown, the structure of the voltage spike protection circuit of the wireless power transmission inverter described in this embodiment includes: a high-frequency differential sampling module, a high-speed comparison module, a physical reset button, an optical coupling isolation module, a high-speed digital controller and a single-ended drive module;

[0052] The high-frequency differential sampling module is used to convert the inverter output voltage Vin+ and Vin- into a low-voltage high-frequency signal V out , and output the low-voltage high-frequency signal after proportional conversion as signal ①;

[0053] The high-speed comparison module has a self-locking function. The comparator compares the signal ① with the reference voltage V set Perform logical judgment, transmit the judgment information as signal ② to the optical coupling isolation module, and transmit the judgment result as signal ⑤ to the high-speed digital controller, wherein signal ② includes low level and high level states;

[0054] The physical reset button transmits the high-speed comparison module reset information as a signal ④ to the high-speed comparison module for a reset operation;

[0055] The optocoupler isolation module is used to remove the influence of signal ② on the driving circuit in the single-ended driving module and output signal ③;

[0056] The high-speed digital controller reads the judgment result of the high-speed comparison module by receiving signal ⑤, and transmits signal ⑥ to the high-speed comparison module to control the reset function of the high-speed comparison module after self-locking. At the same time, according to the read judgment result, the signal ⑦ is transmitted to the single-ended drive module to realize the detection and control of the single-ended drive module, so as to ensure that the information of signal ⑤ is accurately reflected;

[0057] The single-ended driver module controls the switching state of the switch tube by detecting the state of signal ③ to complete circuit protection.

[0058] The AC power is transmitted through the transmitting coil after passing through the compensation topology, and the receiving coil receives the compensated AC power through the compensation topology and is received by the DC converter;

[0059] The DC converter converts the received AC power into AC power;

[0060] The DC converter is used to convert high voltage AC power into low voltage AC power and transmit it to the load.

[0061] The high-frequency differential sampling module includes resistors R1-R19, capacitors C1-C10, diodes D1-D4, and a first active voltage follower circuit, a second active voltage follower circuit, and a third active voltage follower circuit. The high-speed comparison module is connected to the resistor R20, wherein the resistor R3 is a pull-up resistor and the resistor R15 is a pull-down resistor.

[0062] A resistor R22 is provided on the connection circuit between the physical reset button and the high-speed digital controller;

[0063] The high-speed digital controller includes a resistor R22 and a current-limiting resistor R21, which are connected to a physical reset button through an emitter of an NPN transistor, a base stage is connected to a DSP through the current-limiting resistor R21, and is connected to a high-speed comparison module through a switch.

[0064] In addition, the specific application of the wireless power transmission inverter voltage spike protection circuit designed in this embodiment in the circuit is as follows: Figure 1 As shown, the application circuit includes a DC power supply, an inverter, a transmitting coil, a receiving coil, a rectifier, a DC converter and a load connected in sequence;

[0065] The DC power supply is used to provide active voltage for the inverter;

[0066] The inverter is used to invert the voltage and convert the active current into AC. When the peak of the inverter output voltage exceeds the limit, the internal circuit is triggered to switch the switch tube to complete the circuit protection.

[0067] The AC power is transmitted through the transmitting coil after passing through the compensation topology, and the receiving coil receives the compensated AC power through the compensation topology and is received by the DC converter;

[0068] The DC converter converts the received AC power into AC power;

[0069] The DC converter is used to convert high voltage AC power into low voltage AC power and transmit it to the load.

[0070] In summary, this embodiment completes the circuit topology. Next, this embodiment will use the wireless power transmission inverter voltage spike protection method to set the parameters of the inverter internal circuit components. The specific steps are as follows: Figure 3 As shown, including:

[0071] Step 1: Input the inverter output voltage Vin+ and Vin- into the high-frequency differential sampling module to divide them into Vin1 and Vin2. Vin1 and Vin2 pass through the first active voltage follower circuit and the second active voltage follower circuit respectively and then merge into the third active voltage follower circuit. Combined with the target protection value and the weak current power supply range, the inverter output voltage is divided proportionally to determine V out1 , V out1 As signal ①, it is transmitted to the high-speed comparison module, wherein the passive device voltage divider specifically refers to the sum of the resistors in the passive device voltage divider module;

[0072] Step 2: According to the voltage division ratio and the frequency f of the inverter output voltage spike, adjust the capacitors C1-C10 of the passive device voltage division part to make the inverter internal circuit waveform before and after sampling consistent;

[0073] Step 3: Adjust resistor R3, resistor R15 and capacitors C2-C7 to eliminate the chip differences of the active voltage follower circuit provided by the DC power supply;

[0074] Step 4: According to the corresponding time requirements, select the corresponding high-speed comparison module with self-locking power supply, where the input voltage of the high-speed comparator meets

[0075] Step 5: Set the reference voltage V set， The high-speed comparison module compares the signal ① with the reference voltage V set Perform logical judgment, transmit the judgment information as signal ② to the optocoupler isolation module, and transmit the judgment result as signal ⑤ to the high-speed digital controller:;

[0076] Step 6: Connect the high-speed digital controller and the high-speed comparison module through the switch, and connect through the emitter of the NPN transistor and the physical reset button. The base is connected to the DSP through the current limiting resistor R21, and the resistor R20 and the hysteresis time are set by looking up the table;

[0077] Step 7: The physical reset button transmits signal ④ to reset the high-speed comparison module after self-locking, and the high-speed digital controller transmits signal ⑦ to the single-ended drive module according to the judgment result of reading the physical reset button to realize the detection and control of the single-ended drive module;

[0078] Step 8: Isolate signal ② and signal ③ through the optocoupler isolation module, and output signal ③ to drive the single-ended drive module to complete circuit protection;

[0079] Through the above content, this embodiment constructs Figure 4 The specific inverter voltage spike protection circuit shown in the figure, the component parameters of the high-frequency differential sampling module in the circuit are shown in Table 1:

[0080] Table 1

[0081]

[0082] The internal component parameters of the high-speed comparison module, physical reset button, optocoupler isolation module, high-speed digital controller and single-ended drive module are shown in Table 2:

[0083] Table 2

[0084]

[0085] In order to verify the technical effect of the present invention, this embodiment performs simulation verification on the high-frequency sampling module circuit. The simulation verification result of the high-frequency sampling module circuit is as follows: Figure 5 (a) and Figure 5(b) Figure 5 (a) and Figure 5 In (b), channel 1 shows the voltages at the Vin1 and Vin2 ports, channel 2 shows the voltage at the Vout1 port, the proportional circuit is 2 / 1000, and the inverter protection circuit trigger waveform is as follows: Figure 6 As shown, channel 1 shows the inverter output voltage, channel 2 shows the inverter output current, and channel 3 shows the action level, which changes from low level to high level during action. It is obvious from the figure that when the peak exceeds a certain value, the circuit is immediately triggered to complete the protection.

[0086] To sum up, the voltage spike protection circuit proposed in the present invention can effectively detect spike voltage, and combines hardware triggering with software triggering to achieve timely protection and ensure equipment safety. At the same time, the voltage divider circuit in the present invention has high restoration degree at high frequency and no waveform distortion. The protection circuit has an implementation path composed of pure analog circuits, with short overall response time and reliable triggering, which fills the gap in the inverter function. In addition, the protection circuit in the present invention can achieve accurate sampling and fast response, which can improve the switching frequency and voltage and current levels, and is conducive to further improving the power level, power density and system efficiency of the wireless power transmission system.

[0087] The above is only a preferred embodiment of the present invention and does not limit the present invention in any form. Although the present invention has been disclosed as a preferred embodiment as above, it is not used to limit the present invention. Any technician familiar with this profession can make some changes or modify the technical contents disclosed above into equivalent embodiments without departing from the scope of the technical solution of the present invention. However, any simple modification, equivalent replacement and improvement made to the above embodiments without departing from the content of the technical solution of the present invention, based on the technical essence of the present invention, within the spirit and principles of the present invention, still fall within the protection scope of the technical solution of the present invention.

Claims

1. A voltage spike protection circuit for a wireless power transmission inverter, characterized in that: The wireless power transmission inverter voltage spike protection circuit includes: a high-frequency differential sampling module, a high-speed comparison module, a physical reset button, an optical coupling isolation module, a high-speed digital controller and a single-ended drive module; The high-frequency differential sampling module is used to convert the output voltages Vin+ and Vin- of the inverter into low-voltage high-frequency signals V out , and output the low-voltage high-frequency signal after proportional conversion as signal ①; The high-speed comparison module has a self-locking function, and the comparator compares the signal ① with the reference voltage V set Perform logical judgment, transmit the judgment information as signal ② to the optical coupling isolation module, and transmit the judgment result as signal ⑤ to the high-speed digital controller, wherein signal ② includes low level and high level states; The physical reset button transmits the high-speed comparison module reset information as a signal ④ to the high-speed comparison module for a reset operation; The optical coupling isolation module is used to remove the influence of signal ② on the driving circuit in the single-ended driving module and output signal ③; The high-speed digital controller reads the judgment result of the high-speed comparison module by receiving signal ⑤, and transmits signal ⑥ to the high-speed comparison module to control the reset function of the high-speed comparison module after self-locking, and at the same time transmits signal ⑦ to the single-ended drive module according to the read judgment result to realize the detection and control of the single-ended drive module, so as to ensure that the information of signal ⑤ is accurately reflected; The single-ended driving module controls the switching state of the switch tube by detecting the state of the signal ③ to complete circuit protection.

2. The wireless power transmission inverter voltage spike protection circuit according to claim 1, characterized in that: The high-frequency differential sampling module includes resistors R1 to R19, capacitors C1 to C10, diodes D1 to D4, and a first active voltage follower circuit, a second active voltage follower circuit, and a third active voltage follower circuit, and the high-speed comparison module is connected to the resistor R20; A resistor R22 is provided on the connection circuit between the physical reset button and the high-speed digital controller; The high-speed digital controller includes resistors R22 and R21, which are connected to a physical reset button through an emitter of an NPN transistor, a base stage is connected to a DSP through a current-limiting resistor R21, and is connected to a high-speed comparison module through a switch.

3. The wireless power transmission inverter voltage spike protection circuit according to claim 2, characterized in that: The resistor R3 is a pull-up resistor, the resistor R15 is a pull-down resistor, and the resistor R21 is a current limiting resistor.

4. A method for protecting a wireless power transmission inverter from voltage spikes, applied to a wireless power transmission inverter from voltage spikes protection circuit as claimed in any one of claims 1 to 3, characterized in that: include: Step 1: Input the inverter output voltage Vin+ and Vin- into the high-frequency differential sampling module to divide them into Vin1 and Vin2. Vin1 and Vin2 pass through the first active voltage follower circuit and the second active voltage follower circuit respectively and then merge into the third active voltage follower circuit. Combined with the target protection value and the weak current power supply range, the inverter output voltage is divided proportionally to determine V out1 , V out1 Transmitted as signal ① to the high-speed comparison module; Step 2: According to the voltage division ratio and the frequency f of the inverter output voltage spike, adjust the capacitors C1-C10 of the passive device voltage division part to make the inverter internal circuit waveform before and after sampling consistent; Step 3: Adjust resistor R3, resistor R15 and capacitors C2-C7 to eliminate the chip differences of the active voltage follower circuit provided by the DC power supply; Step 4: According to the corresponding time requirements, select the corresponding high-speed comparison module with self-locking power supply, where the input voltage of the high-speed comparator meets Step 5: Set the reference voltage V set , the high-speed comparison module compares the signal ① with the reference voltage V set Perform logical judgment, transmit the judgment information as signal ② to the optocoupler isolation module, and transmit the judgment result as signal ⑤ to the high-speed digital controller:; Step 6: Connect the high-speed digital controller and the high-speed comparison module through the switch, and connect through the emitter of the NPN transistor and the physical reset button. The base is connected to the DSP through the current limiting resistor R21, and the resistor R20 and the hysteresis time are set by looking up the table; Step 7: The physical reset button transmits signal ④ to reset the high-speed comparison module after self-locking, and the high-speed digital controller transmits signal ⑦ to the single-ended drive module according to the judgment result of reading the physical reset button to realize the detection and control of the single-ended drive module; Step 8: Isolate signal ② and signal ③ through the optocoupler isolation module, and output signal ③ to drive the single-ended drive module to complete circuit protection; V out1 The calculation formula is: In formula (1), the passive device voltage divider specifically refers to the sum of the resistances in the passive device voltage divider module; The reference voltage is calculated as:

5. Application of voltage spike protection circuit for wireless power transmission inverter, characterized in that: include: A DC power supply, an inverter, a transmitting coil, a receiving coil, a rectifier, a DC converter and a load connected in sequence; The DC power supply is used to provide active voltage for the inverter; The inverter uses a voltage spike protection circuit to perform voltage inversion and convert active current into AC power. When the peak of the inverter output voltage exceeds the limit, the internal circuit is triggered to switch the switch tube to complete the circuit protection. The AC power is transmitted through the transmitting coil after passing through the compensation topology, and the receiving coil receives the compensated AC power through the compensation topology and is received by the DC converter; The DC converter converts the received AC power into AC power; The DC converter is used to convert high voltage AC power into low voltage AC power and transmit it to the load.

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