Cigarette lighter output circuit and control method thereof

Abstract

This invention discloses a cigarette lighter output circuit, comprising: a power circuit and a control circuit. The power circuit is connected to the control circuit and a power supply. The control circuit generates an adjustment signal and outputs it to the power circuit. The adjustment signal is generated based on the output current of the cigarette lighter output circuit after a load is connected, so that the adjustment signal is adjusted according to the load. The power circuit adjusts the operating current limit point according to the adjustment signal. The initial value of the operating current limit point is set to be greater than the normal operating value of the operating current limit point, so that the cigarette lighter output circuit can withstand the inrush current. The operating current limit point is adjusted according to the adjustment signal and can return to the normal operating value of the operating current limit point after the inrush current disappears, thereby ensuring that the device temperature rise meets the device operating specifications and that the power components operate stably and reliably, thereby enhancing product reliability and the normal load protection mechanism.

Description

Technical Field

[0001] This invention relates to the field of electronic cigarette lighter technology, and in particular to a cigarette lighter output circuit and control method. Background Technology

[0002] Portable energy storage power supplies are small energy storage devices with built-in lithium-ion batteries. They feature large capacity, high power, safety, and portability, providing a stable AC / DC voltage output. They also come with multiple output interfaces, including AC (AC input power interface), USB (DC charger interface), Type-C, and a cigarette lighter socket. Their applications are becoming increasingly widespread, with growing demands for functionality and continuously improving electrical performance. They can be used in various scenarios such as outdoor travel, emergency rescue, medical relief, and outdoor work. They can utilize photovoltaic power generation and storage, serving as a replacement for traditional fuel generators.

[0003] Current portable energy storage power supplies have weak overload capacity when starting up their cigarette lighters. To ensure the normal operation of the power supply equipment and electrical loads, the output current usually needs to be limited by the maximum battery capacity (e.g., 10 amps). However, this often fails to meet the power supply requirements of various types of loads, especially small electric loads, which may fail to start or repeatedly start because the output current of the battery device exceeds the maximum battery capacity after connection, thus preventing normal operation. Summary of the Invention

[0004] The purpose of this invention is to solve the problem of weak output overload capacity when the cigarette lighter of a portable energy storage power supply is started.

[0005] Therefore, the present invention proposes a cigarette lighter output circuit, comprising: a power circuit and a control circuit, wherein the power circuit is connected to the control circuit and a power supply respectively;

[0006] The control circuit is used to generate an adjustment signal and output it to the power circuit. The adjustment signal is generated based on the output current of the cigarette lighter output circuit after the load is turned on, so that the adjustment signal can be adjusted according to the load.

[0007] The power circuit adjusts the operating current limit point according to the adjustment signal. The initial value of the operating current limit point is set to be greater than the normal operating value of the operating current limit point, so that the cigarette lighter output circuit can withstand the inrush current. Furthermore, the operating current limit point can be further adjusted according to the adjustment signal, so that it can return to the normal operating value of the operating current limit point after the inrush current disappears.

[0008] In some embodiments, the control circuit outputs the following adjustment signal to the power circuit according to the magnitude of the output current;

[0009] When the output current is less than the operating current limit point during normal operation, the operating current limit point remains unchanged at its initial value; when the output current is greater than the operating current limit point during normal operation, the output adjustment signal lowers the operating current limit point to track and stabilize the output current within the operating current limit point during normal operation.

[0010] In some embodiments, the control circuit outputs the following adjustment signal to the power circuit according to the magnitude of the output current;

[0011] When the output current is less than the operating current limit point during normal operation, the output adjustment signal keeps the operating current limit point unchanged at its initial value; when the output current is greater than the operating current limit point during normal operation, the output adjustment signal lowers the operating current limit point, tracks and stabilizes the output current within the operating current limit point during normal operation.

[0012] In some embodiments, when the output current is greater than the operating current limit point during normal operation, after a predetermined period of time, the output adjustment signal is lowered to track and stabilize the magnitude of the output current within the operating current limit point during normal operation.

[0013] In some embodiments, the adjustment signal is a PWM signal; when the output current is less than the operating current limit point during normal operation, the duty cycle of the PWM signal is 100%; when the output current is greater than the operating current limit point during normal operation, after a predetermined time, the duty cycle of the PWM is reduced to track and limit the output current to the operating current limit point during normal operation.

[0014] In some embodiments, the cigarette lighter output circuit further includes a cigarette lighter input current sampling circuit connected between the power supply and the power circuit;

[0015] The cigarette lighter input current sampling circuit is used to collect the input current signal of the cigarette lighter and send the input current signal to the control circuit;

[0016] The output current is calculated by the control circuit based on the input current signal.

[0017] Furthermore, the cigarette lighter output circuit also includes a current sampling and amplification circuit; the cigarette lighter input current sampling circuit, the current sampling and amplification circuit, and the control circuit are connected in sequence.

[0018] The cigarette lighter input current sampling circuit includes a first sampling resistor connected to the cigarette lighter current input terminal, and the current sampling amplification circuit is connected in parallel with the first sampling resistor.

[0019] Furthermore, when the cigarette lighter output circuit calculates the output current of the power circuit based on the cigarette lighter input current, it considers the battery voltage, the cigarette lighter input current, the cigarette lighter output voltage, and the output efficiency of different percentage power ranges.

[0020] Furthermore, the control circuit calculates the output current of the power circuit according to the following formula:

[0021] I out =(V bat *I in *η N ) / V out

[0022] Among them, V bat Battery voltage; I in V is the input current of the cigarette lighter. out The voltage output by the cigarette lighter; η N Output efficiency for different percentage power ranges.

[0023] In some embodiments, the power circuit includes a power chip and a first differential sampling input terminal and a second differential sampling input terminal for the output current. The two pins of the first differential sampling input terminal and the second differential sampling input terminal are respectively connected to the two ends of the first differential sampling resistor and the second differential sampling resistor. By acquiring the output current, the circuit feeds it back to the power chip to achieve self-stabilizing control of the output voltage, so that the output voltage is stabilized at a preset voltage.

[0024] In some embodiments, the cigarette lighter output circuit further includes an input on / off control circuit, which includes a transistor and a switching transistor. The transistor is connected to the control circuit and receives a control signal from the control circuit to control its on / off state. The switching transistor is connected between the battery input and the cigarette lighter power circuit, and the control terminal of the switching transistor is connected to the output terminal of the transistor. When the control signal output by the control circuit is low, the transistor is in the off state, shutting off the cigarette lighter input and stopping the cigarette lighter from working. When the control signal is high, the transistor is turned on, causing the control terminal of the switching transistor to be pulled low, and the switching transistor is in the on state, allowing the battery input to the power circuit and starting the cigarette lighter to work.

[0025] In some embodiments, the cigarette lighter output circuit further includes an output voltage sampling circuit connected between the power circuit and the control circuit, including a first voltage sampling resistor and a second voltage sampling resistor connected in series between a reference voltage and ground, and the terminals connected to the two resistors are sampling terminals.

[0026] The present invention also proposes an energy storage power supply, including the cigarette lighter output circuit of any of the above embodiments.

[0027] The beneficial effects of this invention compared to the prior art include:

[0028] The cigarette lighter output circuit proposed in this invention uses a control circuit to output an adjustment signal to the power circuit based on the output current. The power circuit adjusts the operating current limit point according to the adjustment signal. The initial value of the operating current limit point is set to a normal operating value that is greater than the operating current limit point and can accommodate the inrush current, thereby ensuring that the device temperature rise meets the device operating specifications. This allows the power components to operate stably and reliably and withstand the impact load during startup, thus enhancing the product's reliability and the normal operation protection mechanism of the load.

[0029] In some embodiments, the cigarette lighter output circuit provided by the present invention also has the following beneficial effects:

[0030] This invention can calculate the output current from the input current, thereby saving an output current sampling I / O port and an output current sampling circuit, further simplifying the circuit structure.

[0031] The circuit control of this invention is simple. By sampling the cigarette lighter input current and combining it with the battery voltage, the power consumed by the cigarette lighter can be directly sampled, allowing for more accurate calculation of the system's battery discharge energy and thus a more accurate determination of the system's remaining battery capacity. Attached Figure Description

[0032] Figure 1 This is a block diagram of the cigarette lighter output circuit in an embodiment of the present invention;

[0033] Figure 2 This is a circuit diagram of the cigarette lighter input on / off control circuit and the cigarette lighter input current sampling circuit in an embodiment of the present invention;

[0034] Figure 3 This is a circuit diagram of the power circuit in an embodiment of the present invention;

[0035] Figure 4 This is a circuit diagram of the cigarette lighter output voltage sampling circuit in an embodiment of the present invention;

[0036] Figure 5 This is a circuit diagram of the control circuit in an embodiment of the present invention;

[0037] Figure 6 This is a circuit diagram of the current sampling amplification circuit in an embodiment of the present invention. Detailed Implementation

[0038] The present invention will be further described below with reference to the accompanying drawings and preferred embodiments. It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other.

[0039] It should be noted that the directional terms such as left, right, up, down, top, and bottom used in this embodiment are only relative concepts or references to the normal use of the product, and should not be considered restrictive. When an element is said to be "fixed to" or "set on" another element, it can be directly on or indirectly on the other element. When an element is said to be "connected to" another element, it can be directly connected to or indirectly connected to the other element. Furthermore, a connection can be used for fixing, coupling, or communication.

[0040] As mentioned earlier, portable energy storage power supplies are widely used in existing technologies. The load types output by a cigarette lighter are not limited to a single type. Besides charging car batteries during outdoor travel, they may also output power to small electric tools or other impact loads. For mechanical loads, the starting current is much greater than 10A, while the maximum current limit of a typical cigarette lighter output is 10A. This would either cause small electric loads to repeatedly start and malfunction, or result in relatively high costs and complex control circuitry.

[0041] On the other hand, it is generally difficult for ARM control chips to achieve a switching frequency of >100kHz and stable control when outputting PWM (pulse width modulation), which results in the large size and high cost of inductive and capacitive components in the circuit.

[0042] To adapt to various application scenarios, this embodiment proposes a cigarette lighter circuit that features low cost, simplified control, and resistance to high starting current. It offers advantages such as simple functionality, simplified control, and low cost.

[0043] Example 1:

[0044] This embodiment discloses a cigarette lighter circuit, referencing... Figure 1 The circuit consists of five functional circuits: a cigarette lighter input on / off control circuit and a cigarette lighter input current sampling circuit 1 and a power circuit 2 connected thereto; a cigarette lighter output voltage sampling circuit 3 connected to the power circuit 2; a control circuit 4 connected to the cigarette lighter output voltage sampling circuit 3; and a current sampling amplification circuit 5 connected to the control circuit 4. The control circuit 4 is also connected to the cigarette lighter input on / off control circuit and the cigarette lighter input current sampling circuit 1 and the power circuit 2.

[0045] In this embodiment of the invention, the control circuit 4 employs an ARM control circuit 4, which outputs an adjustment signal to the power circuit 2 based on the output current. The adjustment signal is an IADJ signal. The power circuit 2 controls and adjusts the operating current limit point of the cigarette lighter output based on the IADJ signal, ensuring that the initial value of the operating current limit point is greater than the normal operating value, thus enabling it to withstand inrush current. The IADJ signal adjusts according to the load, allowing it to return to the normal operating value of the operating current limit point after the inrush current disappears. The operating current limit point refers to the maximum allowable output current of the cigarette lighter.

[0046] In this embodiment of the invention, the control circuit 4 outputs the following IADJ signal to the power circuit 2 based on the output current magnitude: when the output current is less than the normal operating value of the current limiting point, the current limiting point remains unchanged at its initial value of 20A; when the output current is greater than the normal operating value of the current limiting point, the IADJ signal is output to lower the current limiting point, tracking and stabilizing the output current within the normal operating value of the current limiting point. The current limiting point can also be maintained at its initial value of 20A by outputting the IADJ signal.

[0047] In this embodiment of the invention, the source and flow of the on / off control signal are as follows: The cigarette lighter achieves its rated output voltage and current through the above circuit combination. The battery input voltage BAT+ is input to the cigarette lighter input on / off control and cigarette lighter input current sampling circuit 1. The output VBAT-12V10A of the cigarette lighter input on / off control and cigarette lighter input current sampling circuit 1 is connected to the power circuit 2. After power amplification, the power circuit 2 outputs 12V10A-1 to the cigarette lighter output voltage sampling circuit 3. The sampled voltage VODC12V is input to the ARM control circuit 4. The ARM control circuit 4 sends an on / off control signal to the cigarette lighter input on / off control and cigarette lighter input current sampling circuit 1, thereby controlling the output of the cigarette lighter.

[0048] The ARM control circuit 4 calculates the output current based on the input current signal sampled from the cigarette lighter input on / off control and the cigarette lighter input current sampling circuit 1 and amplified by the current sampling amplifier circuit 5. The ARM control circuit 4 also sends the IADJ signal to the power circuit 2 to control the output of the cigarette lighter.

[0049] Power circuit 2 is controlled by a drive signal, and its output is 12V+ and 12V- terminals.

[0050] The cigarette lighter uses the above circuitry to achieve a stable output of 13.3V voltage and 10A current. Because rechargeable batteries have a relatively wide voltage fluctuation range, they are marked as 12V, but the voltage after full charge is 13.3V.

[0051] In this embodiment, the cigarette lighter input on / off control and cigarette lighter input current sampling circuit 1 are as follows: Figure 2 As shown, the circuit controls whether the input power of the cigarette lighter is turned on or off by outputting a high or low level control signal through the DC_EN (a pin of the ARM control circuit 4) of the ARM control circuit. The DC_EN is controlled by the ARM control circuit 4 and connected to the transistor Q9. In the cigarette lighter output circuit, the power supply, the switching transistor Q5, and the power circuit 2 are connected in sequence. The control terminal of the switching transistor Q5 is also connected to the output terminal of the transistor Q9.

[0052] When the system detects that the user has turned off the cigarette lighter or that the cigarette lighter has malfunctioned, the ARM control circuit 4 controls the DC_EN output control signal to be low, thereby turning off the on / off control transistor, which in turn turns off the switching transistor Q5, thus shutting off the cigarette lighter input and stopping the cigarette lighter from working.

[0053] When the ARM control circuit detects that the user has turned on the cigarette lighter, the DC_EN output control signal is high, which turns on the transistor Q9. When pin 4 of the Q5-MOSFET (Metal-Oxide-Semiconductor Field-Effect Transistor) is pulled low to near GND, the switching transistor Q5 is fully turned on and in the on state. Then the battery is input to the power circuit of the cigarette lighter, and the cigarette lighter starts to work.

[0054] The VBAT-12V10A terminal is connected to the power circuit 2, and the IDC12V+ and IDC12V- terminals are connected to the current sampling amplifier circuit 5 for current amplification.

[0055] At the same time, DC_EN can also control the shutdown of the cigarette lighter's input power, which can reduce the standby power consumption of the cigarette lighter and effectively save energy.

[0056] In addition, by setting the first sampling resistor R107 to be connected in parallel with the current sampling amplifier circuit 5, the voltage across R107 is collected, and the ARM chip collects the IDC12V voltage through the current sampling amplifier circuit 5 to calculate the input current, thereby realizing the sampling of the cigarette lighter input current.

[0057] In this embodiment, power circuit 2 is as follows: Figure 3As shown, the circuit uses a VBAT-12V10A (power supply voltage) input voltage. The VBAT-12V10A terminal is connected to the cigarette lighter input on / off control and cigarette lighter input current sampling circuit 1. On one hand, the VBAT-12V10A input voltage acts on the subsequent cigarette lighter output circuit; on the other hand, it is connected to the EN pin of the U6 power chip through a voltage divider circuit. Therefore, when the VBAT-12V10A input voltage is applied, the power chip U6 starts up. The normal output drive signal controls Q6 through HG PL56001 at pin 17 of the power chip U6, and the output drive signal is through LG at pin 14 of the power chip U6. The PL56001 controls Q8, where U6 is a step-down control chip. The portable power supply has a built-in battery voltage between 18V and 26V, and a step-down circuit can be used to achieve a 13.3V output for the cigarette lighter. The power chip U6 uses the PL56001 chip (a DC-DC step-down chip). The switching frequency of the drive signal output by the power chip U6 is adjusted by R115 and R118. In this circuit, the switching frequency of the drive signal FREQ_PL56001 is set to 300kHz. Using high-frequency switching to achieve the power circuit results in a smaller L3 differential mode inductor and a smaller output filter capacitor EC7, thus reducing the overall size and significantly lowering component costs. Furthermore, the U6 (PL56001) achieves a stable output voltage of 13.3V with high accuracy and an error controllable within ±1%.

[0058] The maximum output current limit is achieved by adjusting the resistance values ​​of the first differential sampling resistor R66 and the second differential sampling resistor R91. The operating current limit point is:

[0059] Operating current limit point current = self-stabilized output voltage / sampling resistor value;

[0060] In this embodiment of the invention, both the first differential sampling resistor R66 and the second differential sampling resistor R91 are 4 mohm resistors, so the resistance of their parallel connection is 2 m ohms, and the calculated operating current limit is 20A. The first and second differential sampling input terminals are the CSP and CSN pins of the power chip PL56001, respectively. The CSP and CSN pins are connected to the two ends of R66 and R91, respectively. The CSP and CSN pins are the differential sampling inputs for the power circuit output current. By acquiring the power circuit output current and feeding it back to the CSP and CSN pins, the power chip PL56001 can achieve self-stabilized control of the output voltage at a preset voltage. The power circuit output current can also be used to control the adjustment of the operating current limit. In this embodiment, the self-stabilized output voltage is controlled at a preset voltage of 40mV.

[0061] The IADJ signal (a signal on a pin of the ARM control circuit) is controlled by ARM control circuit 4. ARM control circuit 4 controls and outputs the IADJ signal, which is a PWM signal. This signal is input to the PWM control circuit in chip U6.

[0062] The PWM signal has a frequency of 20kHz, a controllable duty cycle of 0-100%, and output voltages of 3.3V and 0V. This PWM signal can control and adjust the operating current limit of the cigarette lighter output. When the duty cycle is 100%, the operating current limit is maintained at its maximum value: 20A. When the cigarette lighter output is in a steady state, if the output current exceeds 10A, the output current is controlled by decreasing the duty cycle of the PWM signal.

[0063] When the output current is less than the operating current limit point during normal operation, the duty cycle of the PWM signal is 100%; when the output current is greater than the operating current limit point during normal operation, after a predetermined time, the duty cycle of the PWM is reduced to track and limit the output current to the operating current limit point during normal operation.

[0064] The duty cycle of the PWM signal is adjusted by the ARM control circuit 4 to lower the value of the operating current limit point, track and stabilize the output current at 10A. This ensures the maximum output current is 10A, i.e., the operating current limit point is stabilized at 10A, guaranteeing that the device temperature rise meets the device's operating specifications. This allows the power components to operate stably and reliably, thus achieving operating current limit point control.

[0065] The 12V10A-1 terminal is connected to the cigarette lighter output voltage sampling circuit 3.

[0066] The 12V+ / 12V- terminals are the output terminals of the entire cigarette lighter circuit.

[0067] Pin 1 of power chip U6 (PL56001) is connected to pin 20 of power chip U6 via VDD_PL56001. Pin 2 of power chip U6 is connected to ARM control circuit 4 via IADJ. Pin 7 of power chip U6 is connected to high-frequency switch via FREQ_PL56001. Pin 9 of power chip U6 is connected to the capacitor circuit after the first differential sampling resistor R66 and the second differential sampling resistor R91 and before cigarette lighter output voltage sampling circuit 3 via VBUS PL56001. Pin 10 of power chip U6 is connected to the input of the first differential sampling resistor R66 and the second differential sampling resistor R91 via CSN PL56001. Pin 11 of power chip U6 is connected to the output of the first differential sampling resistor R66 and the second differential sampling resistor R91 via CSP PL56001. Pin 14 of power chip U6 is connected to LG PL56001 is connected to Q8. Pin 17 of power chip U6 is connected to Q6 through HG PL56001. Pin 18 of power chip U6 is connected to VBAT PL56001 through VBAT PL56001. Pin 19 of power chip U6 is connected to EN PL56001 through EN PL56001. Pin 22 of power chip U6 is grounded.

[0068] In this embodiment, the cigarette lighter output voltage sampling circuit 3 is as follows: Figure 4 As shown, the output voltage sampling circuit is connected between the power circuit and the control circuit. It includes a first voltage sampling resistor and a second voltage sampling resistor connected in series between the reference voltage and ground. The terminals connecting the two are the sampling terminals. The first and second voltage sampling resistors are R128 and R136, respectively. This circuit samples the cigarette lighter output voltage. The sampled VODC 12V is output to the ARM control circuit 4, which uses R128 and R136 to calculate the cigarette lighter output voltage. If the voltage is higher than 14V, a fault is reported: cigarette lighter output overvoltage; if the voltage is lower than 9V, a fault is reported: cigarette lighter output undervoltage. A low level is output through the DC_EN pin to shut off the cigarette lighter input power, thus protecting the load and the entire cigarette lighter operating circuit.

[0069] Terminal 12V10A-1 is connected to power circuit 2 for voltage sampling. VODC12V is the sampling voltage, output to ARM control circuit 4. 3.3V in the diagram is the clamping voltage.

[0070] In this embodiment, the ARM control circuit 4 is as follows: Figure 5As shown, the circuit functions to adjust the output current IADJ (PWM signal), sample the cigarette lighter input current IDC12V, receive the sampling voltage VODC12V sent by the cigarette lighter output voltage sampling circuit 3, and the ARM control circuit 4 includes an ARM control chip. The ARM control chip of the whole machine samples and calculates the voltage, current and power of the cigarette lighter, realizing the intelligence of the cigarette lighter circuit, while saving one sampling IO port of the cigarette lighter output current.

[0071] In this embodiment, the ARM control chip is a microcontroller, model STM32F030C8T6.

[0072] The DC_EN terminal is connected to the cigarette lighter input on / off control and cigarette lighter input current sampling circuit 1, and is used to control whether the input power of the cigarette lighter is turned on or off by high or low level.

[0073] Combined with the magnitude of the battery voltage V bat (From the dedicated pin for battery operation mode) and the sampled input current signal I_DC12V from the cigarette lighter, the ARM control chip can calculate the input power of the cigarette lighter. The segmented output efficiency of the cigarette lighter, which can be obtained through actual testing, is divided into 10 levels. The efficiency η1 for a 10% output load rate is used as the output efficiency for the 0-10% load power range, the efficiency η2 for a 20% output load rate is used as the output efficiency for the 10-20% load power range, and so on, η... 10 The output efficiency is set at >90% of the load power range. The cigarette lighter output current is as follows:

[0074] I out =(V bat *I in *η N ) / V out

[0075] Where V bat Battery voltage; I in : Input current of the cigarette lighter; V out η: The voltage output by the cigarette lighter; NOutput efficiency at different percentage power levels. This principle can be used to calculate the actual output current of the cigarette lighter. When the calculated output current of the cigarette lighter is less than the normal operating current limit of 10A, the duty cycle of the IADJ signal is kept at 100%. At this time, the output current is determined by the load power. When the cigarette lighter output current is detected to be greater than the normal operating current limit of 10A and this continues for a predetermined time of 500ms, the operating current limit is initially set to 20A. After 500ms, the duty cycle of the IADJ output PWM signal is simultaneously reduced to continuously track the output current of the cigarette lighter until it is limited to the normal operating current limit of 10A. This function is compatible with impulsive loads, inductive loads, etc. The 500ms overload time can meet the starting power of most impulsive loads. After the impulsive load stabilizes, the current is generally 50%-70% lower than the starting current.

[0076] When the cigarette lighter output voltage is higher than 14V or lower than 9V, DC_EN outputs a low level, shutting off the cigarette lighter input power. Simultaneously, the system reports overvoltage or undervoltage protection for the cigarette lighter.

[0077] The aforementioned preset time can be set not only to 500ms, but also between 450 and 550ms depending on the actual situation, and can even be set to 0. When the cigarette lighter output current is detected to be greater than the normal operating current for the preset time, the maximum current at the operating current limiting point is twice the normal operating current. After the preset time, the duty cycle of the IADJ output PWM signal is simultaneously reduced to continuously track the magnitude of the cigarette lighter output current until the output current is limited to the normal operating current.

[0078] In this embodiment, the current sampling amplifier circuit 5 is as follows: Figure 6 As shown, this circuit functions as an amplifier for the cigarette lighter input current. The ARM control chip collects the I_DC12V voltage from this circuit and calculates the input current. The formula for the sampled voltage is as follows:

[0079]

[0080] Where I in The input current of the cigarette lighter circuit is calculated as follows: R111 = R113, R38 = R41, R33 = R44, with a safety margin of 0.5V.

[0081] D40 serves as a 3.3V clamping voltage to protect the ARM control chip from overvoltage breakdown, while 0.5V acts as a bias voltage for the sampling circuit, making low-current sampling more accurate.

[0082] The signals on terminals I DC12V+ and I DC12V- come from the cigarette lighter input on / off control and cigarette lighter input current sampling circuit 1.

[0083] This embodiment adjusts the cigarette lighter output current and overload time by controlling the maximum current of the circuit and the PWM signal output by the ARM control chip. When the start-up condition meets the requirements of an impulsive load, the overload capacity doubles. When the output voltage is over-voltage, undervoltage protection is implemented, enhancing product reliability and the normal operation protection mechanism of the load.

[0084] The embodiments of the present invention use a high-frequency switch at a frequency of 300KHz to achieve stable control, which greatly reduces the cost of differential mode inductors and filter capacitors. Compared with other switches controlled by ARM and used as driving MOSFETs, the cigarette lighter output circuit of the embodiments of the present invention has lower cost and simpler circuit.

[0085] The background section of this invention may include background information about the problems or environment in which the invention is being developed, and is not necessarily a description of prior art. Therefore, the content included in the background section does not constitute an admission of prior art by the applicant.

[0086] The above description provides a further detailed explanation of the present invention in conjunction with specific / preferred embodiments, and it should not be construed that the specific implementation of the present invention is limited to these descriptions. For those skilled in the art, various substitutions or modifications can be made to these described embodiments without departing from the concept of the present invention, and all such substitutions or modifications should be considered within the scope of protection of the present invention. In the description of this specification, the reference to terms such as "an embodiment," "some embodiments," "preferred embodiment," "example," "specific example," or "some examples," etc., indicates that the specific features, structures, materials, or characteristics described in connection with that embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described can be combined in any suitable manner in one or more embodiments or examples. Without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification and the features of different embodiments or examples. Although the embodiments of the present invention and their advantages have been described in detail, it should be understood that various changes, substitutions, and modifications can be made herein without departing from the scope of protection of the patent application.

Claims

1. A cigarette lighter output circuit for an energy storage power supply, characterized in that, include: The system includes a power circuit and a control circuit, wherein the power circuit is connected to the control circuit and a power source respectively; it also includes a cigarette lighter input current sampling circuit connected between the power source and the power circuit; the cigarette lighter input current sampling circuit is used to collect the input current signal of the cigarette lighter and send the input current signal to the control circuit. The output current is calculated by the control circuit based on the input current signal; The control circuit generates an adjustment signal and outputs it to the power circuit. The adjustment signal is generated based on the output current of the cigarette lighter output circuit after the load is turned on, so that the adjustment signal can adjust according to the load. The adjustment signal is a PWM signal. When the output current is less than the working current limit point during normal operation, the duty cycle of the PWM signal is 100%. When the output current is greater than the working current limit point during normal operation, after a predetermined time, the duty cycle of the PWM is reduced to track and limit the output current to the working current limit point during normal operation. The control circuit calculates the output current of the power circuit according to the following formula: Among them, V bat Battery voltage; I in V is the input current of the cigarette lighter. out This refers to the voltage output by the cigarette lighter. Output efficiency for different percentage power ranges; The control circuit outputs the following adjustment signal to the power circuit according to the magnitude of the output current: when the output current is less than the working current limit point during normal operation, the adjustment signal is output to keep the working current limit point unchanged at the initial value; when the output current is greater than the working current limit point during normal operation, the adjustment signal is output to lower the working current limit point, track and stabilize the magnitude of the output current within the working current limit point during normal operation. The power circuit adjusts the operating current limit point according to the adjustment signal. The initial value of the operating current limit point is set to be greater than the normal operating value of the operating current limit point, so that the cigarette lighter output circuit can withstand the inrush current. Furthermore, the operating current limit point can be further adjusted according to the adjustment signal, so that it can return to the normal operating value of the operating current limit point after the inrush current disappears.

2. The cigarette lighter output circuit as described in claim 1, characterized in that, When the output current exceeds the operating current limit during normal operation, the output adjustment signal will lower the operating current limit after a predetermined time, tracking and stabilizing the output current within the operating current limit during normal operation.

3. The cigarette lighter output circuit as described in claim 1, characterized in that, It also includes a current sampling and amplification circuit; the cigarette lighter input current sampling circuit, the current sampling and amplification circuit, and the control circuit are connected in sequence. The cigarette lighter input current sampling circuit includes a first sampling resistor connected to the cigarette lighter current input terminal, and the current sampling amplification circuit is connected in parallel with the first sampling resistor.

4. The cigarette lighter output circuit as described in claim 1, characterized in that, The power circuit includes a power chip and a first differential sampling input terminal and a second differential sampling input terminal for the output current. The two pins of the first differential sampling input terminal and the second differential sampling input terminal are respectively connected to the two ends of the first differential sampling resistor and the second differential sampling resistor. By collecting the output current, the feedback is sent to the power chip to achieve self-stabilizing control of the output voltage, so that the output voltage is stabilized at a preset voltage.

5. The cigarette lighter output circuit as described in claim 1, characterized in that, It also includes an input on / off control circuit, which includes a transistor and a switching transistor. The transistor is connected to the control circuit and receives control signals from the control circuit to control its on / off state. The switching transistor is connected between the battery input and the cigarette lighter power circuit, and the control terminal of the switching transistor is connected to the output terminal of the transistor. When the control signal output by the control circuit is low, the transistor is in the off state, shutting off the cigarette lighter input and stopping the cigarette lighter from working. When the control signal is high, it controls the transistor to turn on, pulling the control terminal of the switching transistor low, turning the switching transistor on, allowing the battery input to the power circuit, and starting the cigarette lighter.

6. The cigarette lighter output circuit as described in claim 1, characterized in that, It also includes an output voltage sampling circuit connected between the power circuit and the control circuit. The output voltage sampling circuit includes a first voltage sampling resistor and a second voltage sampling resistor connected in series. The first voltage sampling resistor and the second voltage sampling resistor are connected between the reference voltage and ground. The terminal connected to the first voltage sampling resistor and the second voltage sampling resistor is the sampling terminal.

7. An energy storage power source, characterized in that, Includes the cigarette lighter output circuit as described in any one of claims 1 to 6.

Images