AC charging pile detection circuit and AC charging pile detection method

Abstract

The invention provides an AC charging pile detection circuit comprising a voltage following circuit which inputs a control guide signal which is from an AC charging pile and forms positive and negative voltage of a PWM signal when the AC charging pile is connected with an electric vehicle through the control guide circuit, a voltage following signal obtained after voltage following is carried out on the control guide signal is output; and the voltage division sampling circuit is used for performing voltage division on the voltage following signal output from the voltage following circuit, and outputting different voltage division sampling signals with positive voltage values obtained by voltage division so as to be sampled by a controller of the alternating current charging pile.

Description

Technical Field

[0001] The present invention relates to electric vehicle charging and discharging technology, and in particular to an AC charging pile detection circuit and an AC charging pile detection method. Background Art

[0002] In AC power supply equipment (i.e. AC charging pile), the CP signal is called Control Pilot Function signal (ControlPilot Function), which is mainly used to monitor the interaction function between electric vehicles and electric vehicle power supply equipment (i.e. AC charging pile). It is a communication method that uses PWM (pulse width) modulation and amplitude alternation.

[0003] When the charging gun of the AC charging pile is connected to the electric vehicle, due to the presence of the voltage divider resistor in the on-board charger, the CP signal will jump from +12V to +9V. This +9V signal is equivalent to the electric vehicle (or new energy vehicle) telling the charging gun that the electric vehicle has been connected to the charging gun. At this time, the MCU (which can be called a microcontroller unit or controller) of the AC charging pile detects that the CP signal jumps to 9V and switches the output to a PWM (pulse width modulation) signal. After the charging pile outputs the PWM signal, the electric vehicle confirms the charging signal and switches the voltage divider resistor in the on-board charger, so that the CP signal jumps to +6V. This +6V signal indicates that the electric vehicle is ready to charge and requests the charging pile to close. After the MCU of the AC charging pile detects that the CP signal jumps to +6V, the main relay closes and starts charging the electric vehicle. Therefore, it is particularly important to obtain the voltage corresponding to the CP control guide in time during the operation of the AC power supply equipment to determine the connection status between the AC power supply equipment and the vehicle.

[0004] In addition, the CP control pilot usually uses a CP signal modulated on the power supply sine wave. This modulation method is sometimes called frequency modulation, in which a 1kHz signal is modulated onto the power supply frequency. Since the CP control pilot signal is a sine wave, if the D1 diode is not placed on the CP control pilot, it is impossible to distinguish whether the charging device is connected to an electric vehicle, an electric simulator, or a load device. Therefore, when the charging device is connected to an electric vehicle, it is particularly important to detect the diode. In addition, the latest "General Requirements for Charging Systems GB / T 18487.1-2023" A.2.6 also requires the presence of a detection diode. That is, before energy is transmitted, the power supply equipment should be able to verify that an electric vehicle rather than a load device is connected by detecting the presence of D1 on the control pilot circuit. Summary of the invention

[0005] Technical problem to be solved by the invention

[0006] Among the conventional detection schemes for the PWM signal output from the AC charging pile, there is a detection scheme 1 that is composed of a diode detection circuit architecture consisting of a resistor, a capacitor, and an operational amplifier. The PWM signal is input to the operational amplifier through a capacitor, and a feedback network is formed through the resistor on the operational amplifier, and finally output to the ADC interface of the controller of the AC charging pile for sampling. When the +3.3V input signal provided by the auxiliary power supply is raised, since the supply voltage of the operational amplifier is 0-12V, and the operational amplifier has a head room voltage (also called voltage margin), the minimum value of the output signal (AC plus DC) is greater than 0V, resulting in bottom distortion.

[0007] In addition, there is a detection scheme 2, which is to divide the positive voltage of the CP signal and collect it through the op amp for voltage following, and then give it to an ADC interface of the AC charging pile controller for sampling. In addition, when the diode does not exist, the negative voltage of the CP signal -12V will change with the presence of the voltage divider resistor in the on-board charger. Therefore, the negative voltage -12V is made to follow the voltage through the op amp, and then the level signal is inverted after reverse operation amplification and then divided, and then given to another ADC interface of the AC charging pile controller for sampling.

[0008] In the above detection scheme 2, the voltage sampling of the CP signal and the voltage sampling of the diode require two ADC interfaces for sampling. This is because the voltage of the CP signal needs to be collected at the same time as the voltage of the diode after voltage division. According to the above conventional scheme, the positive voltage and the negative voltage need to be processed and collected, so two independent ADC interfaces are required. In addition, the detection of the existence of the diode D1 is to divide the negative voltage in the CP signal into a positive voltage through voltage inversion and then perform voltage division sampling. The devices used are complicated and costly.

[0009] Therefore, the purpose of the present invention is to provide an AC charging pile detection circuit and an AC charging pile detection method, which can not only detect different input voltages, but also use an ADC interface to detect the voltage of the control guide signal and the existence of these two different situations of the diode, and can simplify complex circuits, save circuit costs, and reduce ADC interfaces.

[0010] Technical solutions to technical problems

[0011] According to an embodiment of the present invention, there is provided an AC charging pile detection circuit, comprising: a voltage following circuit, which inputs a control guidance signal of positive and negative voltages from the AC charging pile formed as a PWM signal when the AC charging pile is connected to an electric vehicle through a control guidance circuit, and outputs a voltage following signal obtained by voltage following the control guidance signal; and a voltage dividing sampling circuit, which divides the voltage following signal output from the voltage following circuit, and outputs voltage dividing sampling signals of different voltages whose voltage values ​​obtained by voltage division are all positive for sampling by a controller of the AC charging pile.

[0012] Furthermore, when the sampled voltage-divided sampling signal is a relatively high voltage among the different voltages, the detected voltage of the control guidance signal is a positive voltage, thereby confirming the connection status between the AC charging pile and the electric vehicle.

[0013] Further, when the high voltage is a first sampling voltage, the detected voltage of the control guidance signal is a first detection voltage, and the AC charging pile is not yet connected to the electric vehicle end; or when the high voltage is a second sampling voltage lower than the first sampling voltage, the detected voltage of the control guidance signal is a second detection voltage lower than the first detection voltage, and the AC charging pile is connected to the electric vehicle end but has not started charging the electric vehicle; or when the high voltage is a third sampling voltage lower than the second sampling voltage, the detected voltage of the control guidance signal is a third detection voltage lower than the second detection voltage, and the AC charging pile is connected to the electric vehicle end and starts charging the electric vehicle.

[0014] Furthermore, when the sampled voltage-dividing sampling signal is a relatively low voltage among the different voltages, the control pilot signal is a negative voltage, thereby confirming the existence of the diode located at the electric vehicle end on the control pilot circuit.

[0015] Further, when the low voltage is a fourth sampling voltage close to 0V, the control guidance signal is -12V, and the diode located at the electric vehicle end on the control guidance circuit exists; or when the low voltage is a fifth sampling voltage close to 0V and higher than the fourth sampling, the diode located at the electric vehicle end on the control guidance circuit does not exist.

[0016] Furthermore, the voltage-divider sampling circuit includes: a first voltage-divider resistor, one end of which is connected to the output end of the voltage follower circuit; a second voltage-divider resistor, one end of which is connected to the other end of the first voltage-divider resistor to form a connection point, and the other end of the second voltage-divider resistor is connected to a power supply; and a third voltage-divider resistor, one end of which is connected to the connection point and the other end is grounded.

[0017] Furthermore, the first voltage-dividing resistor, the second voltage-dividing resistor and the third voltage-dividing resistor satisfy the conditions that the value of the current flowing into the connection point is equal to the value of the current flowing out of the connection point and the voltage difference of the different voltages of the voltage-dividing sampling signal is greater than a differential threshold.

[0018] Furthermore, the differential threshold is at least 1.5V.

[0019] Further, when the input control guidance signal is a positive voltage, the sum of the current flowing into the connection point through the first voltage-dividing resistor and the current flowing into the connection point through the second voltage-dividing resistor is equal to the current flowing out from the connection point through the third voltage-dividing resistor; or when the input control guidance signal is a negative voltage, the current flowing into the connection point through the second voltage-dividing resistor is equal to the sum of the current flowing out from the connection point through the first voltage-dividing resistor and the current flowing out from the connection point through the third voltage-dividing resistor.

[0020] According to another embodiment of the present invention, there is provided an AC charging pile detection method, comprising: using a voltage following circuit to input a control guidance signal of positive and negative voltages from the AC charging pile formed as a PWM signal when the AC charging pile is connected to an electric vehicle through a control guidance circuit, and outputting a voltage following signal obtained after voltage following the control guidance signal; and using a voltage dividing sampling circuit to divide the voltage following signal output from the voltage following circuit, and outputting voltage divided sampling signals of different voltages whose voltage values ​​obtained by voltage division are all positive for sampling by the controller of the AC charging pile.

[0021] Furthermore, when the sampled voltage-divided sampling signal is a relatively high voltage among the different voltages, the detected voltage of the control guidance signal is a positive voltage, thereby confirming the connection status between the AC charging pile and the electric vehicle.

[0022] Further, when the high voltage is a first sampling voltage, the detected voltage of the control guidance signal is a first detection voltage, and the AC charging pile is not yet connected to the electric vehicle end; or when the high voltage is a second sampling voltage lower than the first sampling voltage, the detected voltage of the control guidance signal is a second detection voltage lower than the first detection voltage, and the AC charging pile is connected to the electric vehicle end but has not started charging the electric vehicle; or when the high voltage is a third sampling voltage lower than the second sampling voltage, the detected voltage of the control guidance signal is a third detection voltage lower than the second detection voltage, and the AC charging pile is connected to the electric vehicle end and starts charging the electric vehicle.

[0023] Furthermore, when the sampled voltage-dividing sampling signal is a relatively low voltage among the different voltages, the control pilot signal is a negative voltage, thereby confirming the existence of the diode located at the electric vehicle end on the control pilot circuit.

[0024] Further, when the low voltage is a fourth sampling voltage close to 0V, the control guidance signal is -12V, and the diode located at the electric vehicle end on the control guidance circuit exists; or when the low voltage is a fifth sampling voltage close to 0V and higher than the fourth sampling, the diode located at the electric vehicle end on the control guidance circuit does not exist.

[0025] Furthermore, the current flowing into the connection point connecting one end of the first voltage-dividing resistor, the second voltage-dividing resistor and the third voltage-dividing resistor of the voltage-dividing sampling circuit is equal to the current flowing out of the connection point and the voltage difference of the different voltages of the voltage-dividing sampling signal is greater than the differential threshold.

[0026] Furthermore, the differential threshold is at least 1.5V.

[0027] Further, when the input control guidance signal is a positive voltage, the sum of the current flowing into the connection point through the first voltage-dividing resistor and the current flowing into the connection point through the second voltage-dividing resistor is equal to the current flowing out from the connection point through the third voltage-dividing resistor; or when the input control guidance signal is a negative voltage, the current flowing into the connection point through the second voltage-dividing resistor is equal to the sum of the current flowing out from the connection point through the first voltage-dividing resistor and the current flowing out from the connection point through the third voltage-dividing resistor.

[0028] Effects of the Invention

[0029] According to the AC charging pile detection circuit and the AC charging pile detection method of the present invention, it is possible to detect voltage values ​​of different input voltages, and to utilize the ADC interface of a controller to detect the two different situations of the control guide signal and the diode, thereby simplifying complex circuits, saving circuit costs, and reducing ADC interfaces. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] The present disclosure may be better understood by describing exemplary embodiments of the present disclosure in conjunction with the accompanying drawings, in which:

[0031] Figure 1 It is a guiding schematic diagram showing the general requirements for charging systems GB / T 18487.1-2023.

[0032] Figure 2 It is a circuit structure diagram of an AC charging pile detection circuit involved in an embodiment of the present invention.

[0033] Figure 3A It is a diagram showing the current flow of the voltage-dividing sampling circuit when the input is a positive voltage in the AC charging pile detection circuit involved in the embodiment of the present invention.

[0034] Figure 3B The figure shows the current flow of the voltage-dividing sampling circuit when the input is a negative voltage in the AC charging pile detection circuit according to the embodiment of the present invention.

[0035] Figure 3C It means that Figure 3A , Figure 3B A graph of the voltage values ​​at the corresponding connection points and the voltage values ​​at the sampling points.

[0036] Figure 4 It is a flow chart of the AC charging pile detection method involved in the embodiment of the present invention.

[0037] Figure 5 It is a flowchart of detecting the voltage of the CP signal in the AC charging pile detection method involved in the embodiment of the present invention.

[0038] Figure 6 It is a flow chart of detecting the existence of a diode in the AC charging pile detection method involved in the embodiment of the present invention.

[0039] Description of labels:

[0040] 100 AC charging pile detection circuit; 1 voltage follower circuit; 3 voltage divider sampling circuit; U1 follower operational amplifier; C11 first capacitor; C22 second capacitor; C55 fifth capacitor; D1 diode; D22 second diode; D33 third diode; R11 first resistor; R22 second resistor; R33 third resistor; b connection point; Vb connection point voltage; a sampling point; Va sampling point voltage; GND grounding; VCC AC power supply; CP_IN input end of AC charging pile detection circuit; CP_ADC_D output end of AC charging pile detection circuit; C1, C2 contactors; S1, S2, S3 switches; R1, R2, R3, RC resistors. DETAILED DESCRIPTION

[0041] The embodiments of the present disclosure will be described in more detail below with reference to the accompanying drawings. Although certain embodiments of the present disclosure are shown in the accompanying drawings, it should be understood that the present disclosure can be implemented in various forms and should not be construed as being limited to the embodiments described herein, but rather these embodiments are provided for a more thorough and complete understanding of the present disclosure. It should be understood that the drawings and embodiments of the present disclosure are only for exemplary purposes and are not intended to limit the scope of protection of the present disclosure.

[0042] In the description of the present disclosure, it should be noted that, unless otherwise specified, "plurality" means more than two. In addition, the terms "first", "second", "third", etc. are used for descriptive purposes only and cannot be understood as indicating or implying relative importance. In the description of the present disclosure, it should also be noted that, unless otherwise clearly specified and limited, the terms "connected", "connected", "relative", "connected", and "connected" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be directly connected or indirectly connected through an intermediate medium. For those of ordinary skill in the art, the specific meanings of the above terms in the present disclosure can be understood according to the specific circumstances.

[0043] Reference to "embodiment" herein means that a particular feature, structure, or characteristic described in conjunction with the embodiment may be included in at least one embodiment of the present disclosure. The appearance of the phrase in various locations in the specification does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment that is mutually exclusive with other embodiments. It is explicitly and implicitly understood by those skilled in the art that the embodiments described herein may be combined with other embodiments.

[0044] Diode Presence Test Standard

[0045] Figure 1 It is a guiding schematic diagram showing the general requirements for charging systems GB / T 18487.1-2023. Figure 1As shown in the figure, the charging system consists of electric vehicle power supply equipment, vehicle sampling point a, and electric vehicles. Figure 1 The diode D1 on the electric vehicle side of the control pilot circuit is required to be tested for diode presence in A.2.6 of the above GB / T18487.1-2023, that is, before energy transmission, the power supply equipment should be able to verify that the connected device is an electric vehicle rather than a load device by detecting the presence of the diode D1 on the control pilot circuit; this test should be performed at least once from state X (X = 1, 2, 3, defined in Table A.5 (partial excerpt from the table below)) to state X' or during state X' before the power supply equipment turns on the AC power supply circuit. When the low-level state of the PWM signal is detected to be within the voltage range specified in Table A.5, it is determined that the diode D1 exists on the control pilot circuit and the connected device is an electric vehicle or an electric vehicle simulator.

[0046] Specifically, as shown in Table A.5 below, state X / state X' refers to the state of the charging process. When state X = 1 (state 1), it means that switch S1 is connected to the +12V of the power supply device, and switch S2 is in the disconnected state. At this time, the power supply device and the electric vehicle are not yet connected. Therefore, the voltage value detected at detection point 1 is expressed as +12V. When state X' = 1' (state 1'), it means that switch S1 in the power supply device is switched to PWM and generates a ±12V square wave, and switch S2 is in the disconnected state. At this time, the power supply device and the electric vehicle are still not connected. A PWM waveform signal with a voltage value of ±12V will be detected at detection point 1.

[0047] When the state X=2 (state 2), it means that the switch S1 is connected to the +12V of the power supply device, and the switch S2 is in the disconnected state. At this time, the power supply device has been connected to the electric vehicle, that is, the power supply device is ready for charging, but the electric vehicle is not yet ready for charging. Due to the voltage divider effect of R3, the voltage detected at the detection point 1 is +9V. When the state X'=2' (state 2'), it means that the switch S1 in the power supply device is switched to PWM and generates a ±12V square wave, and the switch S2 is in the disconnected state. Due to the voltage divider effect of R3 and the diode D1 placed on the control pilot circuit can only allow the forward voltage to pass, therefore, a PWM waveform signal with a voltage value of +9V and -12V will be detected at the detection point 1, that is, the voltage value of the CP signal at the detection point 1 is a PWM waveform signal with a voltage value of +9V and -12V, indicating that the power supply device has been connected to the electric vehicle, but has not started to charge the electric vehicle.

[0048] When the state X=3 (state 3), it means that the switch S1 is connected to the +12V of the power supply device, and the switch S2 is in a closed state. At this time, the power supply device has been connected to the electric vehicle. The power supply device is not ready for charging, but the electric vehicle is ready for charging. Due to the voltage division effect of R2, the voltage detected at the detection point 1 is +6V. When the state X'=3' (state 3'), it means that the switch S1 in the power supply device is switched to PWM and generates a ±12V square wave, and the switch S2 is in a closed state. At this time, the power supply device and the electric vehicle are in a state where they can be charged. Due to the voltage division effect of R2 and the diode D1 placed on the control pilot circuit can only allow the forward voltage to pass, therefore, a PWM waveform signal with a voltage value of +6V and -12V will be detected at the detection point 1, that is, the voltage value of the CP signal at the detection point 1 is a PWM waveform signal with a voltage value of +6V and -12V, indicating that the power supply device has been connected to the electric vehicle and has started to charge the electric vehicle.

[0049] The detection of the existence of the diode D1 on the control conductive path needs to be performed at least once in the above state 1 to state 1', in state 2 to state 2', in state 3 to state 3', during state 1', during state 2', and during state 3'. The control pilot signal of the AC charging pile is called the CP signal (Control Pilot Signal). This signal plays a key communication and control function between the charging pile and the electric vehicle.

[0050] Table A.5 Voltage status of detection point 1 and corresponding charging process status

[0051]

[0052] In addition, according to the requirements of the above-mentioned diode existence detection, when the charging process is in state 1', state 2', and state 3', the voltage value at the detection point 1 always has a voltage value of -12V. This is because the diode D1 on the control steering circuit can only allow the positive voltage to pass but not the negative voltage value to pass. Therefore, when the ±12V PWM waveform is output from the power supply device, the positive PWM waveform will detect a PWM waveform with a voltage value of +12V, +9V or +6V at the detection point 1 due to the voltage division effect of R2 and R3 on the electric vehicle side, but the PWM waveform with a voltage value of -12V will not change due to the voltage division effect of R2 and R3, but always remain at -12V. Here, only the nominal value is used as an example for explanation, and the voltage detected at the detection point 1 can be within the range of the maximum and minimum values ​​shown in the above Table A.5.

[0053] "Implementation Methods of the Invention"

[0054] This embodiment provides an AC charging pile detection circuit, which can determine the connection status between the AC power supply device and the electric vehicle by detecting the voltage of the CP signal at the detection point 1, and can also determine whether there is a diode D1 on the control guidance circuit and whether the connected device is an electric vehicle or an electric vehicle simulator. In the present invention, the power supply device is sometimes referred to as an AC charging pile.

[0055] Next, the circuit structure of the present invention is described in detail. Figure 2 It is a circuit structure diagram of an AC charging pile detection circuit involved in an embodiment of the present invention.

[0056] The AC charging pile detection circuit of the present invention comprises a voltage follower circuit 1 and a voltage division sampling circuit 3. The input end is set as CP_IN, and the output end is set as CP_ADC_D.

[0057] Voltage follower circuit 1

[0058] The voltage follower circuit 1 inputs a control pilot signal of positive and negative voltages from the power supply device formed as a PWM signal when the power supply device is connected to the electric vehicle through the control pilot circuit, and outputs a voltage following signal obtained by voltage following the control pilot signal.

[0059] Specifically, the voltage follower circuit 1 includes a follower operational amplifier U1, a first capacitor C11, and a second capacitor C22. Among them, the positive input terminal (pin 1) of the follower operational amplifier U1 is connected to the input terminal CP_IN of the AC charging pile detection circuit, and the negative input terminal (pin 3) of the follower operational amplifier U1 is short-circuited to the output terminal (pin 4). One end of the first capacitor C11 is connected to the positive power supply VCC+12V of the follower operational amplifier U1, and the other end is grounded. One end of the second capacitor C22 is connected to the negative power supply VCC-12V of the follower operational amplifier U1, and the other end is grounded.

[0060] Thus, the PWM waveform signal of the detection point 1 input from the input terminal CP_IN is voltage followed by the voltage follower circuit 1 to obtain a signal of the same magnitude as the input PWM waveform signal, and at the same time, some noise signals caused by wiring, etc. accompanying the PWM waveform signal can be removed, so that the circuit described later is not affected by these noise signals. In addition, the first capacitor C11 and the second capacitor C22 are mainly used to filter the noise on the power supply, etc.

[0061] For example, in this embodiment, when the ±12V PWM waveform signal inputted from the input terminal CP_IN is passed through the voltage follower circuit 1, a voltage follower signal of the ±12V PWM waveform signal with noise removed is outputted.

[0062] Voltage divider sampling circuit 3

[0063] The voltage following signal outputted from the voltage following circuit 1 is divided, and voltage divided sampling signals of different voltages whose voltage values ​​are all positive are outputted for sampling by the controller of the power supply device.

[0064] Specifically, the voltage-dividing sampling circuit 3 includes a first voltage-dividing resistor R11 , a second voltage-dividing resistor R22 , a third voltage-dividing resistor R33 , a second diode D22 , a third diode D33 and a fifth capacitor C55 .

[0065] One end of the first voltage-dividing resistor R11 is connected to the output end (pin 4) of the voltage follower circuit 1. One end of the second voltage-dividing resistor R22 is connected to the other end of the first voltage-dividing resistor R11 to form a connection point b, and the other end of the second voltage-dividing resistor R22 is connected to the power supply Vcc+3.3V. One end of the third voltage-dividing resistor R33 is connected to the connection point b, and the other end is grounded (GND). The positive and negative voltage PWM waveform signals output from the voltage follower circuit 1 are divided by the first voltage-dividing resistor R11, the second voltage-dividing resistor R22 and the third voltage-dividing resistor R33 to obtain a voltage-dividing signal at the connection point b.

[0066] The cathode of the second diode D22 is connected to the connection point b, the anode of the second diode D22 is grounded, the anode of the third diode D33 is connected to the connection point b, and the cathode of the third diode D33 is connected to the voltage of VCC+3.3V. One end of the fifth capacitor C55 is connected to the output terminal CP_ADC_D to form a sampling point a, and the sampling point a is connected to the connection point b, so that the voltage of the connection point b is the same as the voltage of the sampling point a. The other end of the fifth capacitor C55 is grounded to filter out the clutter coupled into the circuit. The second diode D22 and the third diode D33 constitute a clamping diode, so that the voltage division signal obtained after voltage division is always clamped within the range of 0 to 3.3V, thereby protecting the microcontroller of the power supply device at the back end. The voltage signal at the sampling point a is called a voltage division sampling signal.

[0067] In addition, the output terminal CP_ADC_D is connected to an ADC interface (not shown) of a microcontroller of the power supply device, so that the voltage-divided sampling signal output from the output terminal CP_ADC_D is provided to the microcontroller of the power supply device for sampling.

[0068] The structure of the AC charging pile detection circuit of the present invention is described above. Figures 3A to 3C , how to detect the voltage of the CP signal and the existence of the diode D1 based on the voltage of the voltage-divided sampling signal. Figure 3A 1 is a diagram showing the current flow when the input to the AC charging pile detection circuit 100 is a positive voltage. Figure 3B 1 is a diagram showing the current flow when the input to the AC charging pile detection circuit 100 is a negative voltage.

[0069] For the connection point b in the voltage-dividing sampling circuit 3 , based on Kirchhoff's current law, it can be known that the sum of the currents flowing into the connection point b is equal to the sum of all the currents leaving the connection point b.

[0070] (1) Voltage detection of control pilot signal (CP signal)

[0071] like Figure 3A As shown, when the voltage flowing into the voltage-dividing sampling circuit 3 is a positive voltage, the sum of the current flowing into the connection point b through the first voltage-dividing resistor R11 and the current flowing into the connection point b through the second voltage-dividing resistor R22 is equal to the current flowing out from the connection point b through the third voltage-dividing resistor R33. That is, the following formula is satisfied:

[0072] (Vin-Vb) / R11+(3.3V-Vb) / R22=Vb / R33 (1)

[0073] Wherein, Vin is the voltage of the voltage follower signal output from the voltage follower circuit 1, Vb is the voltage of the connection point b, and the voltage Va of the sampling point a is equal to the voltage Vb of the connection point b, that is, Va=Vb. In addition, since the voltage-dividing sampling circuit inputs positive voltage and negative voltage, the voltage value of the connection point b (or sampling point a) when the positive voltage is input is as different from the voltage value when the negative voltage is input as possible, that is, the voltage difference of the different voltages of the voltage-dividing sampling signal is greater than a certain differential threshold. The differential threshold can be set according to the differential value of the different voltages at the connection point b calculated based on the above formula (1).

[0074] Therefore, the three voltage-dividing resistors are preferably R11 = 33 kΩ, R22 = 8.2 kΩ, and R33 = 10 kΩ, respectively.

[0075] According to the above formula (1), substituting R11=33kΩ, R22=8.2kΩ, R33=10kΩ into formula (1), we can get:

[0076] When Vin=+12V, Vb=3V, Va=3V,

[0077] When Vin=+9V, Vb=2.7V, Va=2.7V,

[0078] When Vin=+6V, Vb=2.3V, Va=2.3V.

[0079] Therefore, when the voltage-dividing sampling signal collected by the microcontroller of the power supply equipment is one of the above-mentioned high voltages (the voltage-dividing sampling signal obtained when the voltage flowing into the voltage-dividing sampling circuit 3 described later is a negative voltage, and the Vb (Va) voltage values ​​at this time are relatively high), it means that the voltage of the control guide signal detected at the detection point 1 is a positive voltage of +12V, +9V or +6V, and thus the connection status of the AC charging pile and the electric vehicle can be confirmed based on the positive voltage.

[0080] Specifically, when the high voltage is the first sampling voltage, ie, Va=3V, the voltage of the CP signal detected at the detection point 1 is the first detection voltage, ie, +12V, thereby determining that the AC charging pile is not yet connected to the electric vehicle end.

[0081] When the above-mentioned high voltage is a second sampling voltage lower than the first sampling voltage, i.e., Va=2.7V, the voltage of the CP signal detected at the detection point 1 is a second detection voltage lower than the first detection voltage, i.e., +9V. Therefore, it can be judged that the AC charging pile is connected to the electric vehicle end but has not started charging the electric vehicle.

[0082] When the above-mentioned high voltage is a third sampling voltage lower than the second sampling voltage, i.e., Va=2.3V, the voltage of the CP signal detected at the detection point 1 is a third detection voltage lower than the second detection voltage, i.e., +6V. Therefore, it can be determined that the AC charging pile is connected to the electric vehicle end and starts to charge the electric vehicle.

[0083] (2) Detection of the presence of diode D1

[0084] like Figure 3B As shown, when the voltage flowing into the voltage-dividing sampling circuit 3 is a negative voltage, the current flowing into the connection point b through the second voltage-dividing resistor R22 is equal to the sum of the current flowing out of the connection point b through the first voltage-dividing resistor R11 and the current flowing out of the connection point b through the third voltage-dividing resistor R33. That is, the following formula is satisfied:

[0085] (3.3V-Vb) / R22=(Vb+Vin) / R11+Vb / R33 (2)

[0086] Therefore, according to the above formula (2), substituting R11=33kΩ, R22=8.2kΩ, R33=10kΩ into formula (2), we can get

[0087] When Vin=-12V, Vb=153mV, Va=153mV,

[0088] When Vin=-9V, Vb=514mV, Va=514mV,

[0089] When Vin=-6V, Vb=874mV, Va=874mV.

[0090] Therefore, when the voltage division sampling signal collected by the microcontroller of the power supply device is a low voltage lower than the above-mentioned high voltage, it means that the voltage of the CP signal detected at the detection point 1 is a negative voltage of -12V, -9V or -6V, and thus based on the negative voltage, it can be confirmed whether the diode D1 exists.

[0091] Specifically, when the low voltage is the fourth sampling voltage close to 0V, i.e., Va=153mV, it means that the voltage of the CP signal detected at detection point 1 is -12V, so it can be determined that the diode located at the electric vehicle end of the control guidance circuit exists and is connected to an electric vehicle.

[0092] On the other hand, when the diode D1 does not exist on the control pilot circuit, since the negative voltage signal of the PWM waveform output from the power supply device also passes through R2 and R3, after the voltage is divided by R2 and R3, the voltage that can be detected at the detection point 1 is not only -12V, but also -9V and -6V. Therefore, when the above-mentioned low voltage is not 153mV, but the fifth sampling voltage close to 0V and higher than 153mV, such as Va=514mV or 874mV, it can be judged that the diode located at the electric vehicle end on the control pilot circuit does not exist. In addition, for the fifth sampling voltage, since when the diode D1 does not exist on the control pilot circuit, the input voltage will fluctuate, it can be judged that the diode D1 does not exist when the voltage range of the fifth sampling voltage is approximately within the range of 514-554mV or 874-930mV. Alternatively, since when the diode D1 located at the electric vehicle end of the control pilot circuit exists, the negative voltage of the detection circuit can only input -12V, therefore, when Va=153.82mV is not detected at the sampling point a, it can also indicate that the diode does not exist.

[0093] As described above, in the AC charging pile detection circuit of the present invention, no matter whether the input voltage is a positive voltage or a negative voltage, the output at the connection point b is a positive voltage with a very large voltage difference. This can not only meet the needs of detecting voltage values ​​of different input voltages, but also use one ADC interface to detect two different states, thereby simplifying complex circuits, saving circuit costs, and reducing ADC interfaces.

[0094] In addition, since the selection of the three voltage-dividing resistors is based on making the difference between the voltage value of the connection point b when a positive voltage is input and the voltage value when a negative voltage is input as large as possible when positive voltage and negative voltage are input at the input terminal CP_IN, the different voltage values ​​of the connection point b calculated based on the above can be set to a differential threshold of at least about 1.5V (i.e., based on the value obtained by subtracting Vb=874mV when Vin=-6V from Vb=2.3V when Vin=+6V).

[0095] Figure 3C Shows the corresponding Figure 3A and Figure 3B The positive voltage and negative voltage are input respectively, and the voltage values ​​at the connection point b and the sampling point a are sampled. The upper diagram shows the voltage value at the connection point b, and the lower diagram shows the voltage value at the sampling point a. In the upper diagram, when the input is a positive voltage value such as +9V, the voltage Vb at the connection point b is 2.7V, and the corresponding voltage Va at the sampling point a is 2.7V. In addition, when the input is a negative voltage value such as -12V, the voltage Vb at the connection point b is 153mV, and the corresponding voltage Va at the sampling point a is 153mV.

[0096] Through the AC charging pile detection circuit of the present invention, the voltage of the CP signal and the existence of the diode set on the control guidance circuit can be detected while avoiding bottom distortion, and the acquisition of two voltages can be realized through an ADC interface without affecting the interaction between the PWM waveform output by the power supply device and the vehicle. The overall circuit structure is simple, the cost is reduced, and the circuit stability is high. In addition, by judging whether the connected device is a load or an electric vehicle and feeding back the state to the microcontroller, it is possible to provide a variety of charging application scenarios.

[0097] Below, refer to the attached Figure 4 To Attachment Figure 6 The AC charging pile detection method of the present invention is described. Figure 4 It is a flow chart of the AC charging pile detection method involved in the embodiment of the present invention. Figure 5 It is a flowchart of detecting the voltage of the CP signal in the AC charging pile detection method involved in the embodiment of the present invention. Figure 6 It is a flow chart of detecting the existence of a diode in the AC charging pile detection method involved in the embodiment of the present invention.

[0098] like Figure 4As shown, in step S1, the input terminal CP_IN of the AC charging pile detection circuit 100 of the present invention is connected to the detection point 1 of the power supply device. Then in step S2, the control pilot signal formed as a PWM signal (±12V) from the power supply device is input by the voltage follower circuit 1, and the voltage following signal obtained by voltage following the control pilot signal is output. In step S3, the voltage following signal output from the voltage following circuit 1 is divided by the voltage dividing sampling circuit 3, and the voltage divided sampling signals of different voltages whose voltage values ​​are all positive are output for sampling by the ADC interface of the controller of the AC charging pile.

[0099] like Figure 5 As shown, in step S41, it is confirmed whether the voltage-divided sampling signal sampled in step S3 is a relatively high voltage. When it is confirmed to be "yes", it proceeds to step S42. In step S42, it is confirmed whether the above high voltage is 3V. When it is confirmed to be "yes", it proceeds to step S421, and it is determined that the control guidance signal is +12V. In step S422, it is determined that the AC charging pile and the electric vehicle end are not yet connected.

[0100] When it is confirmed as "No" in step S42, proceed to step S43. In step S43, confirm whether the above-mentioned high voltage is 2.7V. When it is confirmed as "Yes", proceed to step S431, determine that the control guidance signal is +9V, and in step S432, determine that the AC charging pile is connected to the electric vehicle end but has not started charging the electric vehicle.

[0101] When it is confirmed as "No" in step S43, proceed to step S44. In step S44, confirm whether the above-mentioned high voltage is 2.3V, proceed to step S441, determine that the control guidance signal is +6V, and in step S442, determine that the AC charging pile is connected to the electric vehicle end but start charging the electric vehicle.

[0102] In addition, when the answer is "No" in the above step S41, the process proceeds to step S5.

[0103] exist Figure 6 In step S5, following step S51, it is confirmed whether the voltage-dividing sampling signal sampled in step S3 is a relatively low voltage, i.e., 153mV. When it is confirmed as "yes", it proceeds to step S52, and it is determined that the control pilot signal is -12V. In step S53, it is determined that the diode located at the electric vehicle end of the control pilot circuit exists. On the other hand, when it is confirmed as "no" in step S51, it proceeds to step S54, and it is confirmed that the voltage-dividing sampling signal sampled in step S3 is not 153mV but 514mV or 874mV. In step S55, it is determined that the diode located at the electric vehicle end of the control pilot circuit does not exist.

[0104] Through the AC charging pile detection method of the present invention, the voltage of the CP signal and the existence of the diode set on the control guidance circuit can be detected while avoiding bottom distortion, and the acquisition of two voltages can be realized through an ADC interface without affecting the interaction between the PWM waveform output by the power supply device and the vehicle. The overall circuit structure is simple, the cost is reduced, and the circuit stability is high. In addition, by judging whether the connected device is a load or an electric vehicle, and feeding back the state to the microcontroller, it is possible to provide a variety of charging application scenarios.

[0105] It should be understood that the above description is illustrative and not restrictive. For example, the above embodiments (and / or their various aspects) can be used in combination with each other. In addition, without departing from the scope of the present invention, many modifications can be made to adapt specific conditions or materials to the teachings of the various embodiments of the present invention. In the case of reading the above description, many other embodiments are obvious to those skilled in the art. Therefore, the scope of the various embodiments of the present invention should be determined with reference to the attached claims, and the full range of equivalent forms claimed by these claims.

Claims

1. An AC charging pile detection circuit, characterized in that: include: A voltage following circuit, which inputs a control guidance signal of positive and negative voltages formed as a PWM signal from the AC charging pile when the AC charging pile is connected to the electric vehicle through the control guidance circuit, and outputs a voltage following signal obtained by voltage following the control guidance signal; as well as A voltage-dividing sampling circuit divides the voltage following signal output from the voltage following circuit, and outputs voltage-dividing sampling signals of different voltages whose voltage values ​​obtained by voltage division are all positive for sampling by the controller of the AC charging pile.

2. The AC charging pile detection circuit according to claim 1, characterized in that: The connection state between the AC charging pile and the electric vehicle is confirmed by detecting that the voltage of the control guidance signal is a positive voltage when the sampled voltage division sampling signal is a relatively high voltage among the different voltages.

3. The AC charging pile detection circuit according to claim 2, characterized in that: When the high voltage is the first sampling voltage, the detected voltage of the control guidance signal is the first detection voltage, and the AC charging pile is not yet connected to the electric vehicle end; or When the high voltage is a second sampling voltage lower than the first sampling voltage, the detected voltage of the control guidance signal is a second detection voltage lower than the first detection voltage, and the AC charging pile is connected to the electric vehicle but does not start charging the electric vehicle; or When the high voltage is a third sampling voltage lower than the second sampling voltage, the detected voltage of the control guidance signal is a third detection voltage lower than the second detection voltage, and the AC charging pile is connected to the electric vehicle end and starts to charge the electric vehicle.

4. The AC charging pile detection circuit according to claim 1, characterized in that: When the sampled voltage-dividing sampling signal is a relatively low voltage among the different voltages, the control pilot signal is a negative voltage, thereby confirming the existence of the diode located at the electric vehicle end on the control pilot circuit.

5. The AC charging pile detection circuit according to claim 4, characterized in that: When the low voltage is a fourth sampling voltage close to 0V, the control guidance signal is -12V, and the diode located at the electric vehicle end on the control guidance circuit exists; or When the low voltage is a fifth sampling voltage close to 0V and higher than the fourth sampling voltage, the diode on the control steering circuit located at the electric vehicle end does not exist.

6. The AC charging pile detection circuit according to any one of claims 1 to 5, characterized in that: The voltage division sampling circuit comprises: A first voltage-dividing resistor, one end of which is connected to the output end of the voltage follower circuit; a second voltage-dividing resistor, one end of the second voltage-dividing resistor is connected to the other end of the first voltage-dividing resistor to form a connection point, and the other end of the second voltage-dividing resistor is connected to a power supply; A third voltage-dividing resistor, one end of which is connected to the connection point, and the other end of which is grounded.

7. The AC charging pile detection circuit according to claim 6, characterized in that: The first voltage-dividing resistor, the second voltage-dividing resistor and the third voltage-dividing resistor satisfy that a value of a current flowing into the connection point is equal to a value of a current flowing out of the connection point and a voltage difference between the different voltages of the voltage-dividing sampling signal is greater than a differential threshold.

8. The AC charging pile detection circuit according to claim 7, characterized in that: The differential threshold is at least 1.5V.

9. The AC charging pile detection circuit according to claim 7, characterized in that: When the input control guidance signal is a positive voltage, the sum of the current flowing into the connection point through the first voltage-dividing resistor and the current flowing into the connection point through the second voltage-dividing resistor is equal to the current flowing out of the connection point through the third voltage-dividing resistor; or, When the input control pilot signal is a negative voltage, the current flowing into the connection point through the second voltage-dividing resistor is equal to the sum of the current flowing out of the connection point through the first voltage-dividing resistor and the current flowing out of the connection point through the third voltage-dividing resistor.

10. A method for detecting an AC charging pile, characterized in that: include: A voltage following circuit is used to input a control guidance signal of positive and negative voltages from the AC charging pile formed as a PWM signal when the AC charging pile is connected to the electric vehicle through the control guidance circuit, and output a voltage following signal obtained by voltage following the control guidance signal; as well as The voltage following signal output from the voltage following circuit is divided by a voltage dividing sampling circuit, and voltage dividing sampling signals of different voltages whose voltage values ​​are all positive are output for sampling by the controller of the AC charging pile.

11. The AC charging pile detection method according to claim 10, characterized in that: The connection state between the AC charging pile and the electric vehicle is confirmed by detecting that the voltage of the control guidance signal is a positive voltage when the sampled voltage division sampling signal is a relatively high voltage among the different voltages.

12. The AC charging pile detection method according to claim 11, characterized in that: When the high voltage is the first sampling voltage, the detected voltage of the control guidance signal is the first detection voltage, and the AC charging pile is not yet connected to the electric vehicle end; or When the high voltage is a second sampling voltage lower than the first sampling voltage, the detected voltage of the control guidance signal is a second detection voltage lower than the first detection voltage, and the AC charging pile is connected to the electric vehicle but does not start charging the electric vehicle; or When the high voltage is a third sampling voltage lower than the second sampling voltage, the detected voltage of the control guidance signal is a third detection voltage lower than the second detection voltage, and the AC charging pile is connected to the electric vehicle end and starts to charge the electric vehicle.

13. The AC charging pile detection method according to claim 10, characterized in that: When the sampled voltage-dividing sampling signal is a relatively low voltage among the different voltages, the control pilot signal is a negative voltage, thereby confirming the existence of the diode located at the electric vehicle end on the control pilot circuit.

14. The AC charging pile detection method according to claim 13, characterized in that: When the low voltage is a fourth sampling voltage close to 0V, the control guidance signal is -12V, and the diode located at the electric vehicle end on the control guidance circuit exists; or When the low voltage is a fifth sampling voltage close to 0V and higher than the fourth sampling voltage, the diode on the control steering circuit located at the electric vehicle end does not exist.

15. The AC charging pile detection method according to any one of claims 10 to 14, characterized in that: The current flowing into the connection point connecting one end of the first voltage-dividing resistor, the second voltage-dividing resistor and the third voltage-dividing resistor of the voltage-dividing sampling circuit is equal to the current flowing out of the connection point and the voltage difference of the different voltages of the voltage-dividing sampling signal is greater than the differential threshold.

16. The AC charging pile detection method according to claim 15, characterized in that: The differential threshold is at least 1.5V.

17. The AC charging pile detection method according to claim 15, characterized in that: When the input control guidance signal is a positive voltage, the sum of the current flowing into the connection point through the first voltage-dividing resistor and the current flowing into the connection point through the second voltage-dividing resistor is equal to the current flowing out of the connection point through the third voltage-dividing resistor; or When the input control pilot signal is a negative voltage, the current flowing into the connection point through the second voltage-dividing resistor is equal to the sum of the current flowing out of the connection point through the first voltage-dividing resistor and the current flowing out of the connection point through the third voltage-dividing resistor.

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