Voltage detection circuit and charging pile

Abstract

The invention relates to the technical field of charging piles, in particular to a voltage detection circuit and a charging pile. The voltage detection circuit comprises a voltage sampling circuit, a non-linear amplification circuit and a control circuit, the voltage sampling circuit is configured to be electrically connected with the input end of the DC / DC circuit and used for sampling the DC bus voltage to output the sampling voltage, and the non-linear amplification circuit is electrically connected with the voltage sampling circuit and used for outputting the sampling voltage; the nonlinear amplification circuit is used for carrying out nonlinear amplification on the sampling voltage and then outputting target voltage, the target voltage and the sampling voltage are in a nonlinear proportional relation, and the control circuit is electrically connected with the nonlinear amplification circuit and used for detecting the direct-current bus voltage according to the target voltage. According to the embodiment of the invention, through non-linear amplification of the sampling voltage, when the DC bus voltage is different, the amplification times of amplification of the sampling voltage are also different, so that under the same quantization resolution, the voltage detection result of the target voltage section can be ensured to be closer to the actual value, thereby facilitating reduction of the voltage detection error and improvement of the voltage detection precision.

Description

Technical Field

[0001] The present invention relates to the technical field of charging piles, and in particular to a voltage detection circuit and a charging pile. Background Art

[0002] The rise of new energy vehicles and people's pursuit of convenience in life have promoted the emergence of high-power super charging piles. In practical applications, charging piles need to detect bus voltage and make corresponding adjustments and controls based on the bus voltage, and the bus voltage detection circuit needs to be able to meet the full range of voltage detection, that is, whether the bus voltage is low or high, it can be detected. In fact, users are more concerned about the voltage detection accuracy of a certain voltage segment in order to achieve more precise adjustment and control, while other voltage segments have no accuracy requirements, and only need to be able to detect the approximate voltage value. However, the current bus voltage detection circuit uses the same precision sampling in the entire voltage range, which will cause a large deviation between the detection result of a more concerned voltage segment and the actual value. When the bus voltage is in a voltage segment that requires precise measurement, the accuracy of voltage detection is low. Summary of the invention

[0003] An object of the present invention is to provide a voltage detection circuit and a charging pile to solve the technical problem of bus voltage detection accuracy in the prior art.

[0004] In a first aspect, an embodiment of the present invention provides a voltage detection circuit, comprising:

[0005] A voltage sampling circuit is configured to be electrically connected to an input terminal of the DC / DC circuit and is used to sample a DC bus voltage to output a sampled voltage;

[0006] a nonlinear amplifying circuit, electrically connected to the voltage sampling circuit, for performing nonlinear amplification on the sampling voltage and then outputting a target voltage, wherein the target voltage is in a nonlinear proportional relationship with the sampling voltage;

[0007] A control circuit is electrically connected to the nonlinear amplifier circuit and is used to detect the DC bus voltage according to the target voltage.

[0008] Optionally, the ratio of the target voltage to the sampling voltage increases as the sampling voltage increases; or,

[0009] The ratio of the target voltage to the sampling voltage decreases as the sampling voltage increases.

[0010] Optionally, the voltage sampling circuit includes:

[0011] A voltage pre-amplification circuit is configured to be electrically connected to the input end of the DC / DC circuit, and is used to sample the DC bus voltage, and pre-amplify the sampled DC bus voltage and then output a pre-amplified voltage;

[0012] The isolation amplifier circuit is electrically connected to the voltage pre-amplifier circuit and the nonlinear amplifier circuit respectively, and is used to amplify and electrically isolate the pre-amplifier voltage and then output a sampling voltage to the nonlinear amplifier circuit.

[0013] Optionally, the nonlinear amplification circuit includes a multiplier;

[0014] The multiplier is electrically connected to the voltage sampling circuit and the control circuit respectively, and is used for outputting a target voltage to the control circuit after multiplying the sampled voltage.

[0015] Optionally, the control circuit includes:

[0016] a voltage generating circuit, electrically connected to the nonlinear amplifying circuit, for generating a positive voltage and a negative voltage respectively according to the target voltage;

[0017] A controller is electrically connected to the differential voltage generating circuit and is used to detect the DC bus voltage according to the positive voltage and the negative voltage.

[0018] Optionally, the voltage generating circuit comprises:

[0019] a positive voltage generating circuit, electrically connected to the nonlinear amplifying circuit and the controller, respectively, and configured to generate a positive voltage according to the target voltage;

[0020] The negative voltage generating circuit is electrically connected to the nonlinear amplifying circuit and the controller respectively, and is used to generate a negative voltage according to the target voltage.

[0021] Optionally, the positive voltage generating circuit comprises a non-inverting amplifier;

[0022] The in-phase amplifier is electrically connected to the nonlinear amplifier circuit and the controller respectively, and is used to generate a positive voltage after amplifying the target voltage.

[0023] Optionally, the in-phase amplifier comprises:

[0024] An operational amplifier, wherein a non-inverting input terminal of the operational amplifier is electrically connected to the non-linear amplification circuit, and an output terminal of the operational amplifier is electrically connected to the controller;

[0025] a first resistor, wherein a first end of the first resistor is electrically connected to the inverting input terminal of the operational amplifier, and a second end of the first resistor is grounded;

[0026] A second resistor, wherein a first end of the second resistor is electrically connected to a first end of the first resistor and an inverting input end of the operational amplifier respectively, and a second end of the second resistor is electrically connected to an output end of the operational amplifier.

[0027] Optionally, the negative voltage generating circuit comprises a subtractor;

[0028] The subtractor is electrically connected to the nonlinear amplifier circuit and the controller respectively, and is configured to input a reference voltage and generate a negative voltage according to a difference between the target voltage and the reference voltage.

[0029] In a second aspect, an embodiment of the present invention provides a charging pile, comprising the voltage detection circuit as described above.

[0030] Compared with the prior art, the embodiment of the present invention provides a voltage detection circuit and a charging pile. The voltage detection circuit includes a voltage sampling circuit, a nonlinear amplification circuit and a control circuit. The voltage sampling circuit is configured to be electrically connected to the input end of the DC / DC circuit, and is used to sample the DC bus voltage to output the sampling voltage. The nonlinear amplification circuit is electrically connected to the voltage sampling circuit, and is used to output the target voltage after nonlinearly amplifying the sampling voltage. The target voltage and the sampling voltage are in a nonlinear proportional relationship. The control circuit is electrically connected to the nonlinear amplification circuit, and is used to detect the DC bus voltage according to the target voltage. In this embodiment, the sampling voltage is nonlinearly amplified, and the amplification factor of the sampling voltage is different when the DC bus voltage is different. Therefore, under the same quantization resolution, it can ensure that the voltage detection result of the target voltage segment is closer to the actual value, which is conducive to reducing the voltage detection error and improving the voltage detection accuracy. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings required for use in the description of the embodiments of the present invention will be briefly introduced below. Obviously, the accompanying drawings in the following description are only some embodiments of the present invention. For ordinary technicians in this field, other accompanying drawings can be obtained based on these accompanying drawings without paying creative labor.

[0032] Figure 1 A schematic diagram of an application scenario of a charging pile provided by an embodiment of the present invention;

[0033] Figure 2 A schematic diagram of the structure of a charging pile provided by an embodiment of the present invention;

[0034] Figure 3 A schematic diagram of the structure of a voltage detection circuit provided by an embodiment of the present invention;

[0035] Figure 4A schematic diagram of the structure of a voltage detection circuit provided by another embodiment of the present invention;

[0036] Figure 5 A schematic diagram of the circuit structure of a voltage detection circuit provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0037] In order to make the purpose, technical scheme and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0038] It should be noted that, if there is no conflict, the various features in the embodiments of the present invention can be combined with each other, all within the scope of protection of the present invention. In addition, although the functional modules are divided in the device schematic diagram and the logical order is shown in the flow chart, in some cases, the steps shown or described can be performed in a different order from the module division in the device or the flow chart. Furthermore, the words "first", "second", "third", etc. used in the present invention do not limit the data and execution order, but only distinguish the same items or similar items with basically the same functions and effects.

[0039] See also Figure 1 , Figure 1 A schematic diagram of an application scenario of a charging pile is provided for an embodiment of the present invention, such as Figure 1 As shown, the application scenario includes a charging pile 100 , a power grid 200 and an electric vehicle 300 .

[0040] The power grid 200 is a power network that transmits city power to the charging pile 100 through a transmission line to supply power to the electric vehicle 300. The city power is industrial frequency alternating current, which is usually characterized by voltage, current and frequency. Generally, the city power transmitted from the power grid 200 to the charging pile 100 is three-phase alternating current.

[0041] The charging pile 100 is a device for charging the electric vehicle 300 to replenish the electric power of the electric vehicle 300. Its working principle is to receive electric energy from the power grid 200, and then transmit the electric energy to the electric vehicle 300 through the charging line to charge the electric vehicle 300. The charging pile 100 can be any type of charging pile that can support AC charging, such as a DC charging pile, an AC charging pile, an AC / DC integrated charging pile, etc.

[0042] The DC charging pile uses direct current to charge the power battery of the electric vehicle 300. This charging method is also called "fast charging". The DC charging pile is electrically connected to the power grid 200, and can receive three-phase 380V alternating current input from the power grid 200 and convert the alternating current into direct current, which is then transmitted to the power battery of the electric vehicle 300 for charging through a standard DC charging plug and charging socket, thereby achieving DC charging. The power supply characteristics of the DC charging pile itself determine that it can output sufficient charging power, and the adjustment range of voltage and current is relatively large, thereby achieving fast charging. The DC charging pile has a charger function, which can monitor and control the working status of the charged power battery in real time, and can also measure the charging power.

[0043] The AC charging pile generally uses a single or dual 220VAC / 380VAC AC output interface to provide power to the electric vehicle 300 so that the electric vehicle 300 can use the on-board charger to charge its power battery. This charging method is also called "slow charging". The output power of the AC charging pile is usually 5kW (220VAC) / 20kW (380VAC), but the actual charging power is restricted by the on-board charger. Generally, the on-board charging power of a small electric vehicle is between 2 and 3kW. The on-board charger of the electric vehicle 300 can convert the AC power into DC power by filtering and rectifying, and then store the DC power in the power battery of the electric vehicle 300, thereby charging the electric vehicle 300. This charging method is mainly used in small pure electric vehicles.

[0044] The input voltage of the AC / DC integrated charging pile is generally three-phase four-wire 380VAC±15%, with a frequency of 50Hz. The AC / DC integrated charging pile includes a DC output port and an AC output port, wherein the DC output port outputs adjustable DC power to charge the power battery of the electric vehicle 300, and the charging power is generally 10-40kW, and the AC output port outputs 220VAC (5kW) / 380VAC (20kW) AC power to provide charging power for the on-board charger of the electric vehicle 300. The AC / DC integrated charging pile can provide conventional charging through the AC output port and fast charging through the DC output port. When there are many charging services during the day, fast charging is used for fast charging. When there are few users at the charging station at night, conventional charging can be used for slow charging. The AC / DC integrated charging pile can realize both AC and DC charging at the same time, and interlocking charging. It adopts modular design for easy maintenance.

[0045] In some embodiments, the charging pile 100 is configured with one or more charging guns, which are interface devices connecting the charging pile and the electric vehicle 300, and are mainly used to transfer electric energy to charge the electric vehicle 300. The charging gun usually has a plug and a connecting wire, one end of which is connected to the charging pile and the other end is inserted into the charging interface of the electric vehicle 300. According to different charging requirements and technical standards, the charging gun can be divided into a fast charging gun and a slow charging gun.

[0046] Fast charging guns are also called DC fast charging guns. They are usually used in fast charging stations. They have a large power output and can quickly charge the vehicle's power battery.

[0047] Slow charging guns are also called AC charging guns. They are usually used in home charging piles, commercial charging piles and public charging piles. They have low power and are suitable for charging with ordinary household power supply. The charging speed is relatively slow.

[0048] The electric vehicle 300 can receive AC or DC power provided by the charging pile 100. When the electric vehicle 300 receives DC power, the electric vehicle 300 can store the DC power in the power battery of the electric vehicle 300, thereby charging the power battery of the electric vehicle 300. When the electric vehicle 300 receives AC power, the electric vehicle 300 can convert the voltage, filter, and rectify the AC power to obtain DC power, and then store the DC power in the power battery of the electric vehicle 300, thereby charging the power battery of the electric vehicle 300. The electric vehicle 300 includes any vehicle that can be driven by electricity, including but not limited to pure electric vehicles, hybrid electric vehicles, fuel cell vehicles, etc.

[0049] In some embodiments, see Figure 2 The charging pile 100 includes an input filter circuit 10, an AC / DC circuit 20, a DC / DC circuit 30, an output filter circuit 40, an auxiliary power supply 50, a charging control module 60, a voltage detection circuit 70, a metering module 80 and a communication module 90.

[0050] The input filter circuit 10 is configured to be electrically connected to the power grid 200 . The input filter circuit 10 is used to filter out high-frequency interference signals, thereby reducing conducted interference.

[0051] The AC / DC circuit 20 is electrically connected to the input filter circuit 10, and is used to convert the AC power of the power grid 200 into DC power. The AC / DC circuit 20 may include any circuit for converting AC power into DC power, including but not limited to a three-phase active PFC (Power Factor Correction) circuit, a three-phase neutral-free Vienna circuit, etc.

[0052] The DC / DC circuit 30 is electrically connected to the AC / DC circuit 20, and is used to convert the direct current output by the AC / DC circuit 20 into a voltage waveform that meets the battery charging strategy. The DC / DC circuit 30 may include any circuit that is used to convert the direct current output by the AC / DC circuit 20 into a voltage waveform that meets the battery charging strategy, including but not limited to LLC resonant circuit, three-phase interleaved LLC resonant circuit, DAB (dual active bridge converter), bidirectional full-bridge CLLC resonant circuit, three-phase interleaved CLLC resonant circuit, phase-shifted full-bridge circuit, etc.

[0053] The output filter circuit 40 is electrically connected to the DC / DC circuit 30 and the electric vehicle 300 respectively. The output filter circuit 40 is used to filter out the electromagnetic interference generated by the charging pile 100 during operation, ensure stable communication between the charging pile 100 and the electric vehicle 300, and avoid charging errors or safety problems caused by interference.

[0054] The auxiliary power supply 50 is electrically connected to the AC / DC circuit 20 and is used to convert the direct current output by the AC / DC circuit 20 into a power supply, which is used to supply power to the charging control module 60 .

[0055] The charging control module 60 is electrically connected to the AC / DC circuit 20 , the DC / DC circuit 30 and the auxiliary power supply 50 , respectively, and is used to work under the power supply of the auxiliary power supply 50 and control the voltage conversion of the AC / DC circuit 20 and the DC / DC circuit 30 .

[0056] The voltage detection circuit 70 is electrically connected to the input end of the DC / DC circuit 30, and is used to detect the input end voltage (bus voltage) of the DC / DC circuit 30, and adjust and control according to the bus voltage, for example, feeding back the bus voltage to the charging control module 60, and the charging control module 60 controls the voltage conversion of the AC / DC circuit 20 according to the bus voltage, thereby realizing feedback adjustment of the bus voltage.

[0057] The metering module 80 is electrically connected to the charging control module 60. The metering module 80 includes metering function, monitoring function and management function. The metering function is responsible for accurately measuring parameters such as power, voltage, current, etc. during the charging process, and feeding back the data to the charging control module 60 to ensure accurate measurement of the charging power. The monitoring function is responsible for real-time monitoring of the operation of the charging pile 100, including power, time, cost, etc., to ensure the normal operation of the charging pile 100. The management function is responsible for managing the charging pile 100, such as setting charging prices, counting charging volume and costs, etc., to provide data support and business basis for operators.

[0058] The communication module 90 is electrically connected to the charging control module 60 and the electric vehicle 300 respectively, and is used to establish communication between the charging control module 60 and the electric vehicle 300. Based on the established communication, the charging pile 100 can interact with the electric vehicle 300. When the charging pile 100 interacts with the electric vehicle 300, various charging interaction information can be sent and received between the charging pile 100 and the electric vehicle 300. The interaction between the electric vehicle 300 and the charging pile 100 during the charging process can be roughly divided into a charging parameter configuration stage and a charging stage. The charging pile 100 is physically connected to the electric vehicle 300 and powered on, and enters the charging parameter configuration stage after checking that the voltage is normal. In the charging stage, the charging pile 100 adjusts the charging voltage and charging current according to the charging requirements of the battery management system of the electric vehicle 300 to ensure that the charging process proceeds normally.

[0059] In some embodiments, see Figure 3 The voltage detection circuit 70 includes a voltage sampling circuit 71 , a nonlinear amplifier circuit 72 and a control circuit 73 .

[0060] The voltage sampling circuit 71 is configured to be electrically connected to the input terminal of the DC / DC circuit 30 and is used to sample the DC bus voltage to output a sampled voltage.

[0061] In some embodiments, see Figure 4 The voltage sampling circuit 71 includes a voltage pre-amplifier circuit 711 and an isolation amplifier circuit 712 .

[0062] The voltage pre-amplifier circuit 711 is configured to be electrically connected to the input end of the DC / DC circuit 30, and is used to sample the DC bus voltage, and pre-amplify the sampled DC bus voltage to output a pre-amplified voltage.

[0063] In some embodiments, the voltage pre-amplification circuit 711 includes a voltage divider unit and an amplification unit. The voltage divider unit is used to output the DC bus voltage after voltage division after voltage division. The amplification unit is electrically connected to the voltage divider unit, and is used to amplify the DC bus voltage after voltage division and output the pre-amplified voltage. The voltage divider unit may include one or more resistors. When the voltage divider unit includes multiple resistors, the multiple resistors may be connected together in series or in parallel. Since the DC bus voltage after voltage division is usually weak, the amplification unit is required to amplify the input voltage collected for subsequent processing. The amplification unit includes any suitable type of voltage amplifier, such as an inverting amplifier, a differential amplifier, an operational amplifier, etc.

[0064] The isolation amplifier circuit 712 is electrically connected to the voltage pre-amplifier circuit 711 and the non-linear amplifier circuit 72 respectively, and is used to amplify and electrically isolate the pre-amplifier voltage and then output the sampling voltage to the non-linear amplifier circuit 72 .

[0065] On the one hand, the isolation amplifier circuit 712 can re-amplify the pre-amplified voltage to ensure that the sampling voltage has sufficient amplitude for better processing and analysis in subsequent circuits. On the other hand, the isolation amplifier circuit 712 can electrically isolate the primary and secondary sides of the transformer to ensure electrical insulation between the input loop and the output loop, without direct electrical coupling, that is, the pre-amplified voltage and the sampling voltage have no common ground terminal, which is conducive to achieving voltage isolation between the pre-amplified voltage and the sampling voltage, avoiding electrical interference between the pre-amplified voltage as input and the sampling voltage as output, thereby helping to improve the accuracy and reliability of the sampling voltage and prevent errors caused by electrical interference.

[0066] The nonlinear amplifier circuit 72 is electrically connected to the voltage sampling circuit 71, and is used to output a target voltage after nonlinearly amplifying the sampling voltage. There is a nonlinear proportional relationship between the target voltage and the sampling voltage, that is, the target voltage is obtained after the sampling voltage is nonlinearly amplified. The gain (amplification factor) of the nonlinear amplifier circuit 72, that is, the ratio of the target voltage to the sampling voltage changes with the change of the sampling voltage. For example, when the sampling voltage is 1V, the gain of the nonlinear amplifier circuit 72 is 1, and the target voltage is 1V. When the sampling voltage is 5V, the gain of the nonlinear amplifier circuit 72 is 5, and the target voltage is 25V.

[0067] The control circuit 73 is electrically connected to the nonlinear amplifier circuit 72, and is used to detect the DC bus voltage according to the target voltage. In some embodiments, the control circuit 73 can convert the target voltage and output the conversion result, and the conversion result can be used to represent the voltage value of the DC bus voltage, wherein there is a corresponding relationship between the target voltage and the conversion result. It can be understood that, although the sampling voltage and the DC bus voltage are in a linear proportional relationship, the sampling voltage and the target voltage are in a nonlinear proportional relationship. When the DC bus voltage is different, the sampling voltage is also different, and the amplification factor of the sampling voltage amplified by the nonlinear amplifier circuit 72 is also different. Under the same quantization resolution, the larger the amplification factor of the sampling voltage amplified by the nonlinear amplifier circuit 72, that is, the larger the target voltage, the DC bus voltage value represented by the conversion result corresponding to the target voltage is also closer to the actual DC bus voltage value, thereby helping to reduce the detection error of the DC bus voltage in the target voltage segment and improve the detection accuracy.

[0068] In this embodiment, the sampling voltage is amplified nonlinearly. When the DC bus voltage is different, the amplification factor of the sampling voltage is also different. Therefore, under the same quantization resolution, it can ensure that the voltage detection result of the target voltage segment is closer to the actual value, which is beneficial to reduce the voltage detection error and improve the voltage detection accuracy.

[0069] In some embodiments, the ratio of the target voltage to the sample voltage increases as the sample voltage increases.

[0070] For example, when the sampling voltage is 1V, the ratio of the target voltage to the sampling voltage is 1; and when the sampling voltage is 5V, the ratio of the target voltage to the sampling voltage is 5.

[0071] Therefore, when the DC bus voltage is larger, the detected DC bus voltage value is closer to the actual DC bus voltage value, which is beneficial to reduce the detection error when the DC bus voltage is near the rated voltage and improve the detection accuracy of the DC bus voltage near the rated voltage.

[0072] In some embodiments, the ratio of the target voltage to the sample voltage increases as the sample voltage decreases.

[0073] For example, when the sampling voltage and the target voltage are expressed as negative values, for example, when the sampling voltage is -1V, the ratio of the target voltage to the sampling voltage is -1, and when the sampling voltage is -5V, the ratio of the target voltage to the sampling voltage is -5.

[0074] Therefore, when the DC bus voltage is larger, the detected DC bus voltage value is closer to the actual DC bus voltage value, which is beneficial to reduce the detection error when the DC bus voltage is near the rated voltage and improve the detection accuracy of the DC bus voltage near the rated voltage.

[0075] It can be understood that if the sampling voltage and the target voltage are expressed as positive values, the smaller the DC bus voltage is, the closer the detected DC bus voltage value is to the actual DC bus voltage value, which is beneficial to reduce the detection error when the DC bus voltage is in a lower voltage segment, and improve the detection accuracy of the DC bus voltage in the lower voltage segment. It can be well applied to occasions with high requirements for small voltage detection accuracy.

[0076] In some embodiments, see Figure 5 , the nonlinear amplification circuit 72 includes a multiplier 721.

[0077] The multiplier 721 is electrically connected to the voltage sampling circuit 71 and the control circuit 73 respectively, and is used for multiplying the sampled voltages and then outputting a target voltage to the control circuit 73 .

[0078] In this embodiment, multiplying the sampled voltages is equivalent to squaring the sampled voltages, thereby obtaining a target voltage whose voltage value is the square of the sampled voltage. Therefore, this embodiment can quadratically amplify the sampled voltage so that the ratio of the target voltage to the sampled voltage increases with the increase of the sampled voltage. As mentioned above, this is conducive to reducing the detection error when the DC bus voltage is near the rated voltage, and improving the detection accuracy of the DC bus voltage near the rated voltage.

[0079] It is understandable that the multiplier 721 can also perform multiple power processing on the sampled voltage, for example, three times or more, or the multiplier 721 can also be combined with any other suitable device to amplify the sampled voltage, as long as the ratio of the target voltage to the sampled voltage increases with the increase of the sampled voltage.

[0080] In some embodiments, please refer to Figure 4 , the control circuit 73 includes a voltage generating circuit 731 and a controller 732 .

[0081] The voltage generating circuit 731 is electrically connected to the nonlinear amplifier circuit 72, and is used to generate positive voltage and negative voltage according to the target voltage. The positive voltage and the negative voltage are two voltages with equal amplitude and opposite phase. The positive voltage and the negative voltage are used to generate a differential voltage. The differential voltage is a voltage used to improve signal accuracy and remove common error interference. In an analog-to-digital converter (ADC), the differential voltage can be used to increase the dynamic range of the input signal and reduce nonlinear distortion.

[0082] In some embodiments, Figure 4 As shown, the voltage generating circuit 731 includes a positive voltage generating circuit 7311 and a negative voltage generating circuit 7312 .

[0083] The positive voltage generating circuit 7311 is electrically connected to the nonlinear amplifier circuit 72 and the controller 732 , respectively, and is configured to generate a positive voltage according to a target voltage and output the positive voltage to the controller 732 .

[0084] In some embodiments, the positive voltage generating circuit 7311 includes a common-phase amplifier, which is electrically connected to the nonlinear amplifier circuit 72 and the controller 732, respectively, and is used to generate a positive voltage after amplifying the target voltage. It is understandable that the positive voltage generating circuit 7311 can also use any other suitable type of amplifier such as a non-feedback operational amplifier, and is not limited to the common-phase amplifier, as long as it can generate a positive voltage after amplifying the target voltage.

[0085] In some embodiments, please refer to Figure 5 The common-mode amplifier includes an operational amplifier EA, a first resistor R1 and a second resistor R2.

[0086] The non-inverting input terminal of the operational amplifier EA is electrically connected to the non-linear amplifier circuit 72, the inverting input terminal of the operational amplifier EA is electrically connected to the first end of the first resistor R1 and the first end of the second resistor R2 respectively, the second end of the first resistor R1 is grounded, and the second end of the second resistor R2 is electrically connected to the output terminal of the operational amplifier EA and the controller 732 respectively.

[0087] In this embodiment, the first resistor R1 is a primary resistor or a sampling resistor, and the second resistor R2 is a feedback resistor for forming negative feedback. The working principle of the common-mode amplifier is: the input signal (target voltage) is input to the common-mode input terminal, and the output terminal amplifies the output with a specific gain, and the gain depends on the resistance values ​​of the first resistor R1 and the second resistor R2. Since the system has negative feedback, it has high stability.

[0088] The negative voltage generating circuit 7312 is electrically connected to the nonlinear amplifier circuit 72 and the controller 732 , respectively, and is configured to generate a negative voltage according to a target voltage and output the negative voltage to the controller 732 .

[0089] In some embodiments, Figure 5 As shown, the negative voltage generating circuit 7312 includes a subtractor 73121. The subtractor 73121 is electrically connected to the nonlinear amplifier circuit 72 and the controller 732 respectively, and is configured to input a reference voltage VREF to generate a negative voltage according to the difference between the target voltage and the reference voltage VREF.

[0090] In order to reduce the error of the differential signal, in some embodiments, the gain of the common-mode amplifier is equal to the gain of the subtractor 73121.

[0091] The controller 732 is electrically connected to the voltage generating circuit 731 and is used to detect the DC bus voltage according to the positive voltage and the negative voltage.

[0092] In this embodiment, the controller 732 includes an analog-to-digital converter supporting a differential signal mode, and the input voltage of the analog-to-digital converter is sampled through a pair of input pins, one of which is a positive input pin and the other is a negative input pin, the positive input pin is input with a positive voltage, the negative input pin is input with a negative voltage, and the actual input voltage is the voltage difference (differential voltage) between the positive voltage and the negative voltage. The analog-to-digital converter can convert the differential voltage and output a conversion result, and the conversion result can be used to determine the DC bus voltage. The analog-to-digital converter can be configured with any suitable resolution, including but not limited to 16 bits, 12 bits, etc. It can be understood that the resolution of the analog-to-digital converter determines the degree of fineness of the analog range being quantized into a digital value.

[0093] In some embodiments, the controller 732 may include any general purpose processor, digital signal processor (DSP), application specific integrated circuit (ASIC), field programmable gate array (FPGA), single chip microcomputer, ARM (Acorn RISC Machine) or other programmable logic device, discrete gate or transistor logic, discrete hardware components or any combination of these components. In addition, the controller 732 may also include any conventional processor, controller, microcontroller or state machine. The controller 732 may also be implemented as a combination of computing devices, for example, a combination of a DSP and a microprocessor, a plurality of microprocessors, one or more microprocessors in combination with a DSP and / or any other such configuration.

[0094] Finally, it should be noted that the present invention can be implemented in many different forms and is not limited to the embodiments described in this specification. These embodiments are not intended to be additional limitations on the content of the present invention. The purpose of providing these implementations is to make the understanding of the disclosure of the present invention more thorough and comprehensive. And under the idea of ​​the present invention, the above-mentioned technical features continue to be combined with each other, and there are many other changes in different aspects of the present invention as described above, which are all considered to be within the scope of the present invention. Further, for those of ordinary skill in the art, improvements or changes can be made according to the above description, and all these improvements and changes should belong to the scope of protection of the claims attached to the present invention.

Claims

1. A voltage detection circuit, characterized in that: include: A voltage sampling circuit is configured to be electrically connected to an input terminal of the DC / DC circuit and is used to sample a DC bus voltage to output a sampled voltage; a nonlinear amplifying circuit, electrically connected to the voltage sampling circuit, for performing nonlinear amplification on the sampling voltage and then outputting a target voltage, wherein the target voltage is in a nonlinear proportional relationship with the sampling voltage; A control circuit is electrically connected to the nonlinear amplifier circuit and is used to detect the DC bus voltage according to the target voltage.

2. The voltage detection circuit according to claim 1, characterized in that: The ratio of the target voltage to the sampling voltage increases as the sampling voltage increases; or, The ratio of the target voltage to the sampling voltage decreases as the sampling voltage increases.

3. The voltage detection circuit according to claim 1, characterized in that: The voltage sampling circuit comprises: A voltage pre-amplification circuit is configured to be electrically connected to the input end of the DC / DC circuit, and is used to sample the DC bus voltage, and pre-amplify the sampled DC bus voltage and then output a pre-amplified voltage; The isolation amplifier circuit is electrically connected to the voltage pre-amplifier circuit and the nonlinear amplifier circuit respectively, and is used to amplify and electrically isolate the pre-amplifier voltage and then output a sampling voltage to the nonlinear amplifier circuit.

4. The voltage detection circuit according to claim 1, characterized in that: The nonlinear amplification circuit includes a multiplier; The multiplier is electrically connected to the voltage sampling circuit and the control circuit respectively, and is used for outputting a target voltage to the control circuit after multiplying the sampled voltage.

5. The voltage detection circuit according to claim 1, characterized in that: The control circuit comprises: a voltage generating circuit, electrically connected to the nonlinear amplifying circuit, for generating a positive voltage and a negative voltage respectively according to the target voltage; A controller is electrically connected to the voltage generating circuit and is used to detect the DC bus voltage according to the positive voltage and the negative voltage.

6. The voltage detection circuit according to claim 5, characterized in that: The voltage generating circuit comprises: a positive voltage generating circuit, electrically connected to the nonlinear amplifying circuit and the controller, respectively, and configured to generate a positive voltage according to the target voltage; The negative voltage generating circuit is electrically connected to the nonlinear amplifying circuit and the controller respectively, and is used to generate a negative voltage according to the target voltage.

7. The voltage detection circuit according to claim 6, characterized in that: The positive voltage generating circuit comprises a common-phase amplifier; The in-phase amplifier is electrically connected to the nonlinear amplifier circuit and the controller respectively, and is used to generate a positive voltage after amplifying the target voltage.

8. The voltage detection circuit according to claim 7, characterized in that: The non-inverting amplifier comprises: An operational amplifier, wherein a non-inverting input terminal of the operational amplifier is electrically connected to the non-linear amplification circuit, and an output terminal of the operational amplifier is electrically connected to the controller; a first resistor, wherein a first end of the first resistor is electrically connected to the inverting input terminal of the operational amplifier, and a second end of the first resistor is grounded; A second resistor, wherein a first end of the second resistor is electrically connected to a first end of the first resistor and an inverting input end of the operational amplifier respectively, and a second end of the second resistor is electrically connected to an output end of the operational amplifier.

9. The voltage detection circuit according to claim 6, characterized in that: The negative voltage generating circuit comprises a subtractor; The subtractor is electrically connected to the nonlinear amplifier circuit and the controller respectively, and is configured to input a reference voltage and generate a negative voltage according to a difference between the target voltage and the reference voltage.

10. A charging pile, characterized in that: The method comprises the voltage detection circuit as claimed in any one of claims 1 to 9.

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