A high-power unmanned aerial vehicle power switch based on PMOS

Abstract

The utility model discloses a kind of high-power unmanned aerial vehicle power supply switches based on PMOS, including PMOS parallel circuit, parallel current control circuit, self-locking switch and overheat protection circuit, the PMOS parallel circuit is connected with power input end, PMOS parallel circuit is connected with self-locking switch and overheat protection circuit simultaneously;The PMOS parallel circuit contains several parallelly connected PMOS, the source S pole of each PMOS is connected to battery anode terminal after being connected with one sampling resistance in series, drain D pole is connected for connecting load anode terminal, one capacitor Cx is placed between the gate G pole and source of each PMOS, two voltage dividing resistors RA, RB are connected in series between power supply anode and cathode, self-locking switch S1 is placed between cathode and voltage dividing resistor RB.The utility model uses the way of PMOS parallel, can resist greater current, and the number of parallel PMOS can be selected according to actual current demand.

Description

Technical Field

[0001] This utility model relates to a high-power drone power switch based on PMOS, belonging to the field of drones. Background Technology

[0002] With the rapid development of the drone market, multi-rotor drones can meet the needs of various application scenarios due to their convenient operation and large payload. However, due to the large load current and battery voltage of light and small drones, ordinary switches cannot withstand high voltage and high load current scenarios. Directly using plug-and-play connectors to power on and off the drone can lead to problems such as connector arcing, aging and loosening.

[0003] Relays and other switching methods use a coil to generate a magnetic field that attracts the iron core or armature, thereby controlling the on / off state of the main circuit. Relays generally have a higher current carrying capacity than switches, but the iron core and armature are heavy, resulting in relays typically weighing over 100 grams. For weight-sensitive drones, this can reduce the drone's endurance and power performance.

[0004] Therefore, designing a lightweight, high-rated-current, and high-voltage-resistant power switch for drones has become an urgent technical challenge. Utility Model Content

[0005] Purpose of the utility model: In order to overcome the shortcomings of the existing technology, this utility model provides a high-power drone power switch based on PMOS. By using the parallel connection of PMOS, it can withstand a larger current, and the number of parallel PMOS can be selected according to the actual current requirements. The resistance value of the voltage divider resistor can be adjusted to adapt to the power supply voltage of different batteries and the Vth of different MOS transistors, making the solution selection flexible and diverse.

[0006] Technical solution: To solve the above technical problems, this utility model provides a high-power UAV power switch based on PMOS, including a PMOS parallel circuit, a parallel current sharing circuit, a self-locking switch, and an overheat protection circuit.

[0007] The PMOS parallel circuit includes several PMOS connected in parallel. The source and source of each PMOS are connected together and connected to the positive terminal of the battery. The drain and source are connected together and used to connect to the positive terminal of the load. A capacitor Cx is placed between the gate and source of each PMOS. Two voltage divider resistors RA and RB are connected in series between the positive and negative terminals of the power supply. A self-locking switch S1 is placed between the negative terminal and the voltage divider resistor RB.

[0008] The parallel current sharing circuit includes a sampling resistor Rx connected in series with the drain of each PMOS transistor, and a differential amplifier for acquiring the voltage drop across the sampling resistor Rx. The output of the differential amplifier is connected to the MCU circuit.

[0009] The overheat protection circuit includes a temperature sensor attached to the surface of a PMOS parallel circuit and a cooling fan controlled by an MCU circuit. The output signal of the temperature sensor is transmitted to the MCU circuit. When the detected temperature exceeds a preset threshold, the MCU circuit outputs a control signal to start the cooling fan.

[0010] The parallel current sharing circuit includes a differential amplifier, an MCU circuit, and a summation circuit. The differential amplifier samples the voltage drop V of Rx. DSX (Reaction corresponds to the PMOS current I) D The MCU circuit compares the V of each PMOS. DSX If the deviation exceeds the threshold, a voltage bias is output. The summation circuit adds the bias to the gate reference voltage and then dynamically adjusts the corresponding gate voltage.

[0011] Preferably, the overheat protection circuit includes a temperature sensor and a cooling fan. The temperature sensor is located on the upper surface of the PMOS parallel circuit, and the cooling fan is located on the lower surface of the PMOS parallel circuit. Its control signal is provided by the MCU main control circuit.

[0012] In this invention, the power switch circuit includes a parallel circuit of P-channel metal-oxide-semiconductor field-effect transistors (PMOS), a pull-up self-locking switch, and an overheat protection circuit. The parallel PMOS circuit includes parallel PMOS transistors, Qx (x = 1, 2, ...), connected in series in the positive terminal of the battery. The source (S) of each PMOS is connected in series with a sampling resistor Rx and then connected to the positive terminal of the battery. The drain (D) is connected to the positive terminal of the load. A capacitor Cx (x = 1, 2, ...) is placed between the gate (G) and source of each PMOS for soft starting. Two voltage divider resistors RA and RB are placed between the positive and negative terminals of the power supply. The resistance values ​​of RA and RB must meet the following requirements.

[0013]

[0014] Among them, V DD Vth is the input voltage of the switching circuit, and Vth is the threshold voltage for the PMOS to turn on.

[0015] In this invention, the pull-up self-locking switch S1 is placed between the negative terminal and the low-side voltage divider resistor RB. The number of PMOS transistors x in the PMOS parallel circuit depends on the load current required by the application scenario. All PMOS transistors should have the same model and on-resistance, and the sum of the rated currents of the PMOS transistors should be twice the maximum load current of the UAV.

[0016] In this invention, the PMOS circuit is an integrated circuit composed of a P-channel metal-oxide-semiconductor field-effect transistor as the core component, using N-type silicon as the substrate material. The formation of the P-type inversion layer conductive channel is controlled by applying a voltage to the gate. When the gate-source voltage Vgs is lower than the threshold voltage Vth, the gate electric field induces the formation of a P-type inversion layer on the surface of the N-type substrate, forming a conduction channel between the source and drain. The magnitude of the conduction current is affected by both the gate voltage and the drain-source voltage Vds.

[0017] In this invention, when the pull-up self-locking switch S1 is open, there is no voltage difference between the gate and source, and the drain and source are two back-to-back PN junctions without a conductive channel. Therefore, there is no drain current, the PMOS transistor is in the off state, and the drone is powered off. When the pull-up self-locking switch S1 is closed, the voltage divider resistors RA and RB form a voltage divider circuit. At this time, the gate voltage Vg of the PMOS transistor can be expressed as:

[0018]

[0019] At this time, the gate-source voltage Vgs of the PMOS is:

[0020]

[0021] Vgs is pulled down below Vth by the voltage divider resistor, the P-type inversion layer conductive channel of the PMOS is formed, and the drain and source are connected. Current flows from the positive terminal of the battery through the PMOS to the load, and the drone is powered on.

[0022] After power-on, the MCU collects the output voltage V of all differential amplifiers in real time. DSX And take the average of all output voltages as V DSX and The difference is Error X After the PID algorithm, the gate voltage adjustment V of each PMOS is output. gx_adj Then the final gate drive voltage is V. g +V gx_adj V gx_adj It will adjust in real time according to the load current of each PMOS, thereby achieving dynamic current sharing.

[0023] In this invention, when switch S1 is closed, the surge current will cause the PMOS and subsequent circuits to lose power due to the impact, resulting in system instability. In severe cases, it may even damage the circuit components. The voltage across capacitor Cx cannot change abruptly. The potential of the gate rises slowly as the capacitor charges, which prolongs the time for Vgs to increase from 0 to more than Vth, thereby limiting the surge current at the moment of startup and avoiding impact on the PMOS and subsequent circuits.

[0024] In this invention, the pull-type self-locking switch can self-lock after closing or opening, and the circuit state can only be changed by pulling it up again. This ensures that the drone will not be in danger of crashing due to changes in the switch state caused by vibration or other factors during flight. The overheat protection circuit includes a temperature sensor and a cooling fan. When the PMOS temperature exceeds the alarm threshold, the temperature sensor alarms the drone's main control circuit and activates the cooling fan for active cooling.

[0025] Beneficial effects: Compared with the prior art, the present invention has the following advantages:

[0026] Compared to directly plugging and unplugging connectors to control the power supply of a drone, this invention avoids the danger of connector arcing and extends the lifespan of the connectors, thereby extending the lifespan of the battery and the drone.

[0027] Compared to previous high-current switches or relays, this invention is smaller and lighter. The circuit design contains only pure analog devices, making the circuit simple and the number of electronic components small. It is easy to integrate into various circuits, further reducing the weight and size of the drone, which is beneficial for the miniaturization of the drone and the improvement of its endurance.

[0028] Compared to traditional switches, this invention, by using parallel PMOS transistors, can withstand larger currents. The number of parallel PMOS transistors can be selected according to actual current requirements. The resistance of the voltage divider resistor can be adjusted to adapt to the power supply voltage of different batteries and the Vth of different MOS transistors, making the solution selection flexible and diverse.

[0029] This invention incorporates a parallel current sharing circuit, which ensures current balance when multiple PMOS transistors are used in parallel through source current sampling and PID regulation, thus avoiding local overheating.

[0030] This utility model also includes overheat protection and active heat dissipation solutions, which can be used in conjunction with UAV flight control or mission controllers to achieve circuit temperature management and prevent PMOS damage caused by current overload and heat generation. Attached Figure Description

[0031] Figure 1 This is a schematic diagram of the structure of this utility model.

[0032] Figure 2 This is a schematic diagram of the PMOS parallel circuit structure of this utility model.

[0033] In the diagram: 1. Pull-up self-locking switch; 2. PMOS parallel circuit; 3. Cooling fan; 4. Temperature sensor; 5. MCU circuit. Detailed Implementation

[0034] The present invention will be further described below with reference to the accompanying drawings.

[0035] like Figure 1 and Figure 2 As shown, the power switch circuit of this utility model is mainly used for power management of high-reliability equipment such as drones. Its core functions include: achieving stable power supply to high-current loads through a parallel PMOS circuit and a parallel current sharing circuit; ensuring the self-locking characteristic of the switch state using a pull-up self-locking switch to prevent accidental activation due to vibration during flight; suppressing inrush current through a soft-start capacitor; and achieving active heat dissipation protection in conjunction with an overheat protection circuit. The overall circuit structure is as follows. Figure 1 As shown, the circuit comprises three parts: a parallel PMOS circuit, a parallel current sharing circuit, a pull-up self-locking switch S1, and an overheat protection circuit. The parallel PMOS circuit includes several PMOS transistors connected in parallel. The source (S) of each PMOS is connected to the positive terminal of the battery, and the drain (D) is connected to the positive terminal of the load. A capacitor Cx is placed between the gate (G) and source of each PMOS. Two voltage divider resistors RA and RB are connected in series between the positive and negative terminals of the power supply. The self-locking switch S1 is placed between the negative terminal and the voltage divider resistor RB. The parallel current sharing circuit includes a sampling resistor Rx connected in series with the drain of each PMOS transistor, and a differential amplifier for acquiring the voltage drop across the sampling resistor Rx. The output of the differential amplifier is connected to the MCU circuit. The overheat protection circuit includes a temperature sensor attached to the surface of the parallel PMOS circuit and a cooling fan controlled by the MCU circuit. The output signal of the temperature sensor is transmitted to the MCU circuit. When the detected temperature exceeds a preset threshold, the MCU circuit outputs a control signal to start the cooling fan.

[0036] I. Parallel Configuration of PMOS

[0037] A parallel PMOS circuit consists of multiple PMOS transistors, denoted as Qx (x = 1, 2, ...). The source is connected in series with a sampling resistor Rx, which is then connected to the positive terminal of the battery. The drain is connected in series and then connected to the positive terminal of the load. All PMOS transistors must be of the same type and have the same on-resistance to ensure uniform current distribution.

[0038] The number of PMOS transistors connected in parallel (x) is determined based on the required load current for the application scenario. For example, if the maximum load current of a drone is I_max, then the sum of the rated currents of all PMOS transistors must be greater than 2I_max to provide sufficient current margin and ensure reliability. Using PMOS transistors of the same model and parameters can avoid uneven current distribution caused by differences in devices and prevent local overheating damage.

[0039] II. Gate Control and Turn-On Logic

[0040] See Figure 2, a sampling resistor Rx is connected in series with the source electrode, and after being connected, it is connected to the positive terminal of the battery. A capacitor Cx is connected between the gate and the source of each PMOS to limit the surge power supply when the power is started. Two voltage dividing resistors Ra and Rb are connected in series between the positive and negative poles of the power supply, and each gate uses a summing operation circuit to combine the gate reference voltage Vg and the gate voltage adjustment amount V output by the MCU. gx_adj They are added together, and the pull-up self-locking switch S1 is connected between the negative terminal and the ground voltage dividing resistor RB.

[0041] When the pull-up self-locking switch S1 is disconnected, there is no voltage difference between the gate and the source. At this time, between the drain and the source of the PMOS are two back-to-back PN junctions, and a conductive channel cannot be formed, and the drain current is almost 0, and the PMOS is in the off state, and the drone is powered off. When the pull-up self-locking switch S1 is closed, the voltage dividing resistors RA and RB form a voltage dividing circuit, pulling down the potential of the gate to be lower than the threshold voltage Vth of the PMOS (that is, Vgs < Vth). At this time, the P-type inversion layer conductive channel of the PMOS is formed, and the drain and the source are导通, and the current flows from the positive pole of the battery through the PMOS to the load, and the drone is powered on.

[0042] During the power-on operation process, the MCU continuously collects the output voltage V of all differential amplifiers. DSX , and takes the average value of all output voltages as V DSX The difference from is Error X , after passing through the PID algorithm, the gate voltage adjustment amount V of each PMOS is output. gx_adj , then the final gate drive voltage is V g +V gx_adj . V gx_adj will be adjusted in real time according to the load current magnitude of each PMOS, so as to achieve dynamic current sharing.

[0043] At the moment when the switch S1 is closed, the surge current will cause the PMOS and the subsequent circuit to be impacted and powered off, resulting in system instability. In severe cases, it may even damage the circuit components. The voltage across the capacitor Cx cannot change suddenly, and the potential of the gate rises slowly during the capacitor charging process, so that the time for Vgs to increase from 0 to exceed Vth is extended, thereby limiting the surge current at the starting moment and avoiding impact on the PMOS and the subsequent circuit.

[0044] The mechanical structure of the switch S1 enables it to maintain its position unchanged after being toggled to the "closed" or "open" position, and will not switch its state automatically even under the vibration or external force interference during the flight of the drone, avoiding power-off or abnormal power-on of the drone due to accidental touch of the switch during flight, and preventing safety accidents such as crashing.

[0045] III. Overheat protection circuit design and function

[0046] The overheat protection circuit is used to monitor the temperature of the PMOS in real time and trigger the heat dissipation protection mechanism when the temperature exceeds the preset alarm value. Its core consists of a temperature sensor and a cooling fan.

[0047] A temperature sensor is mounted close to the PMOS surface to collect the PMOS's operating temperature in real time. When the PMOS temperature rises to the alarm threshold due to prolonged high-current conduction or poor heat dissipation, the temperature sensor sends an alarm signal to the main control circuit. Upon receiving the alarm signal, the main control circuit activates the cooling fan to accelerate heat dissipation from the PMOS surface through air cooling, bringing the PMOS temperature back to a safe range. This prevents the PMOS from being damaged by overheating and extends the device's lifespan. Combined with the temperature threshold alarm, timely intervention can be provided in the early stages of temperature abnormalities to prevent further escalation of the fault.

[0048] Taking the process of a drone starting up, flying, and then losing power upon landing as an example, the working process of the power switch of this utility model is as follows:

[0049] 1. Start-up Phase

[0050] The operator manually pulls and moves the pull-type self-locking switch S1 to the "closed" position, and S1 closes.

[0051] The voltage divider resistors RA and RB pull Vgs down to below Vth, turning on the PMOS. The battery current flows through the PMOS to the load, and the drone is powered on and started.

[0052] The soft-start capacitor Cx slows down the rise rate of Vgs, limits inrush current, and protects the PMOS and subsequent circuitry.

[0053] 2. Flight Phase

[0054] The pull-type self-locking switch S1 remains in a self-locking state to ensure power supply stability.

[0055] The MCU collects the output voltage of all differential amplifiers in real time and adjusts the gate control voltage through a PID algorithm to achieve dynamic current sharing. The MCU circuit is preferably an STM32F103 or an STM32L051.

[0056] The temperature sensor monitors the PMOS temperature in real time. If the temperature is normal, the cooling fan will not start to reduce the power consumption of the drone; if the temperature exceeds the threshold, the main control circuit will trigger the cooling fan to work.

[0057] 3. Landing power outage phase

[0058] After the drone lands, the operator manually pulls the toggle switch S1 to the "off" position. Switch S1 is disconnected, the voltage divider circuit is cut off, the PMOS is disconnected, and the drone is powered off.

[0059] The above description is only a preferred embodiment of the present utility model. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present utility model, and these improvements and modifications should also be considered within the protection scope of the present utility model.

Claims

1. A high-power UAV power switch based on PMOS, characterized in that: This includes PMOS parallel circuits, parallel current sharing circuits, self-locking switches, and overheat protection circuits; The PMOS parallel circuit includes several PMOS connected in parallel. The source and source of each PMOS are connected together and connected to the positive terminal of the battery. The drain and source are connected together and used to connect to the positive terminal of the load. A capacitor Cx is placed between the gate and source of each PMOS. Two voltage divider resistors RA and RB are connected in series between the positive and negative terminals of the power supply. A self-locking switch S1 is placed between the negative terminal and the voltage divider resistor RB. The parallel current sharing circuit includes a sampling resistor Rx connected in series with the drain of each PMOS transistor, and a differential amplifier for acquiring the voltage drop across the sampling resistor Rx. The output of the differential amplifier is connected to the MCU circuit. The overheat protection circuit includes a temperature sensor attached to the surface of the PMOS parallel circuit and a cooling fan controlled by the MCU circuit. The output signal of the temperature sensor is transmitted to the MCU circuit. When the detected temperature exceeds a preset threshold, the MCU circuit outputs a control signal to start the cooling fan.

2. The high-power UAV power switch based on PMOS according to claim 1, characterized in that: The number of PMOS is: Among them, I MAX I is the maximum load current of the drone. D This represents the typical value of the continuous drain current allowed by PMOS. This indicates the rounding up operation.

3. The high-power UAV power switch based on PMOS according to claim 1, characterized in that: The MCU circuit uses an STM32F103 or an STM32L051 MCU.

4. The high-power UAV power switch based on PMOS according to claim 1, characterized in that: The resistance values ​​of RA and RB must meet the following requirements. Among them, V DD Vth is the input voltage of the switching circuit, and Vth is the threshold voltage for the PMOS to turn on.

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