Capacitive load pre-charging control module with reverse connection protection function

Abstract

The present invention discloses a capacitive load pre-charging control module with a reverse connection prevention function, comprising a single-chip microcomputer, a load switch control unit, and a charging threshold detection unit; the load switch control unit is used to receive a drive power supply connection signal sent by the single-chip microcomputer, and the charging threshold detection unit is used to set the threshold of the capacitive load charging voltage and judge the correctness of the positive and negative pole wiring of the drive power supply; when the capacitive load charging voltage reaches the threshold, a capacitive load charging completion signal is sent to the single-chip microcomputer; when the positive and negative pole wiring of the drive power supply is reversed, the single-chip microcomputer can judge by a preset time and send a positive and negative pole reverse connection signal of the drive power supply to an upper computer. The present invention prevents the reverse connection of the power supply during capacitive load pre-charging, and improves the safety and reliability of capacitive load pre-charging. At the same time, a prompt is given when the power supply is reversed.

Description

Technical Field

[0001] The invention relates to a capacitive load pre-charging control module, in particular to a capacitive load pre-charging control module with a reverse connection prevention function. Background Art

[0002] When controlling the power on of a high-power capacitive load, there will be a large current impact, causing the power supply to cut off for protection. Since the capacitive load circuit does not have a reverse connection protection function, once the positive and negative poles of the input power supply are reversely connected, the subsequent capacitive load will be reversely connected and damaged. In addition, due to the inconsistent capacitance of the capacitive load, the pre-charging time is different. If the charging time is too long, it will cause the thermistor and transistor temperature to rise unnecessarily, or even breakdown; if the charging time is too short, the load voltage is low, and the power-on impact problem cannot be effectively solved, and the pre-charging time cannot be accurately controlled. At the same time, the reverse connection of the power supply is not easy to be discovered, causing load damage and uncontrolled circuit switching. Summary of the invention

[0003] The present invention aims to provide a capacitive load pre-charging control module with an anti-reverse connection function, so as to improve the safety and reliability of capacitive load pre-charging.

[0004] To achieve the above object, the present invention adopts the following technical solutions:

[0005] The capacitive load pre-charging control module with anti-reverse connection function of the present invention comprises a single chip microcomputer, a load switch control unit, and a charging threshold detection unit;

[0006] The load switch control unit is used to receive the driving power supply connection signal sent by the single-chip microcomputer, and judge the correctness of the positive and negative poles of the input driving power supply. When the positive and negative poles of the driving power supply are connected correctly, the driving power supply is connected to the capacitive load, and when the positive and negative poles of the driving power supply are connected reversely, the driving power supply is disconnected;

[0007] The charging threshold detection unit is used to set the threshold of the capacitive load charging voltage and judge the correctness of the positive and negative poles of the driving power supply. When the capacitive load charging voltage reaches the threshold, a capacitive load charging completion signal is sent to the single-chip microcomputer. When the positive and negative poles of the driving power supply are reversely connected, the single-chip microcomputer can judge through a preset time and send a positive and negative pole reverse connection signal of the driving power supply to the upper computer.

[0008] The load switch control unit includes a first MOS tube Q1, a second MOS tube Q2 and a first photocoupler U1; the source of the first MOS tube Q1 is connected to the positive electrode of the driving power supply via the thermistor R1, the gate of the first MOS tube Q1 is connected to the positive electrode of the driving power supply via the resistor R4 and the thermistor R1, the drain of the first MOS tube Q1 is connected to the positive electrode of the capacitive load, and is connected to the source of the second MOS tube Q2 via the voltage-dividing resistors R6 and R7; the gate of the second MOS tube Q2 is connected to the positive electrode of the driving power supply via the resistor R9 and the thermistor R1, and the drain of the second MOS tube Q2 is connected to the negative electrode of the driving power supply; the positive electrode of the light-emitting diode of the first photocoupler U1 is connected to the output end of the single-chip computer via the resistor R2, and the The negative electrode of the capacitive load is connected to the positive electrode of the driving power supply via the emitter and collector of the phototransistor of the first photocoupler U1 and resistors R5, R4 and the thermistor R1; the charging threshold detection unit includes a second photocoupler U2 and a comparison amplifier U3; the comparison input end of the comparison amplifier U3 is connected to the low potential end of the voltage-dividing resistor R6, the high potential end of the comparison amplifier U3 is connected to the drain of the first MOS tube Q1 via the light-emitting diode of the second photocoupler U2 and the resistor R3, and the low potential end of the comparison amplifier U3 is connected to the negative electrode of the capacitive load; the collector of the phototransistor of the second photocoupler U2 is connected to the signal input end of the single-chip computer, and the emitter of the phototransistor of the second photocoupler U2 is connected to the digital ground.

[0009] Preferably, the first MOS tube is a PMOS tube.

[0010] The present invention prevents the reverse connection of the power supply during the precharging of the capacitive load, thereby improving the safety and reliability of the precharging of the capacitive load. During the precharging process of the capacitive load, the charging voltage of the load is automatically detected, and after reaching the charging threshold, a signal is fed back to the single-chip microcomputer, thereby avoiding unnecessary increase in the temperature of the thermal sensitive and transistor or even breakdown due to the long charging time. At the same time, a prompt is given when the power supply is reversely connected. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Figure 1 It is a schematic diagram of the circuit principle of the present invention. DETAILED DESCRIPTION

[0012] The following is a detailed description of an embodiment of the present invention in conjunction with the accompanying drawings. This embodiment is implemented on the premise of the technical solution of the present invention, and a detailed implementation method and a specific operation process are given, but the protection scope of the present invention is not limited to the following embodiment.

[0013] like Figure 1 As shown, the capacitive load pre-charging control module with anti-reverse connection function of the present invention includes a single chip microcomputer, a load switch control unit 1, and a charging threshold detection unit 2.

[0014] The load switch control unit 1 is used to receive a signal sent by the single-chip microcomputer to connect the driving power supply 3, and to determine the correctness of the positive and negative poles of the input driving power supply 3. When the positive and negative poles of the driving power supply 3 are connected correctly, the driving power supply 3 is connected to the capacitive load, and when the positive and negative poles of the driving power supply 3 are connected reversely, the driving power supply 3 is disconnected.

[0015] The charging threshold detection unit 2 is used to set the threshold of the capacitive load charging voltage and determine the correctness of the positive and negative poles of the driving power supply 3; when the capacitive load charging voltage reaches the set threshold, a capacitive load charging completion signal is sent to the single-chip microcomputer; when the positive and negative poles of the driving power supply 3 are reversely connected, a positive and negative pole reverse connection signal of the driving power supply 3 is sent to the single-chip microcomputer after a delay of a set time.

[0016] The load switch control unit 1 comprises a first MOS tube Q1, a second MOS tube Q2 and a first photocoupler U1; the source of the first MOS tube Q1 is connected to the positive electrode of the driving power supply via the thermistor R1, the gate of the first MOS tube Q1 is connected to the positive electrode of the driving power supply via the resistor R4 and the thermistor R1, the drain of the first MOS tube Q1 is connected to the positive electrode of the capacitive load, and is connected to the source of the second MOS tube Q2 via the voltage-dividing resistors R6 and R7; the gate of the second MOS tube Q2 is connected to the positive electrode of the driving power supply 3 via the resistor R9 and the thermistor R1, and the drain of the second MOS tube Q2 is connected to the negative electrode of the driving power supply 3; the positive electrode of the light-emitting diode of the first photocoupler U1 is connected to the output end of the single-chip computer via the resistor R2, and the negative electrode of the capacitive load is connected to the positive electrode of the driving power supply 3 via the emitter and collector of the phototransistor of the first photocoupler U1 and the resistors R5, R4 and the thermistor R1.

[0017] The charging threshold detection unit 2 includes a second photocoupler U2 and a comparison amplifier U3; the comparison input terminal of the comparison amplifier U3 is connected to the low potential terminal of the voltage-dividing resistor R6, the high potential terminal of the comparison amplifier U3 is connected to the drain of the first MOS tube Q1 via the light-emitting diode of the second photocoupler U2 and the resistor R3, and the low potential terminal of the comparison amplifier U3 is connected to the negative electrode of the capacitive load; the collector of the phototransistor of the second photocoupler U2 is connected to the signal input terminal of the single-chip computer, and the emitter of the phototransistor of the second photocoupler U2 is connected to the digital ground.

[0018] Compared with the use of diodes to prevent reverse connection in high-power loads, the MOS tube selected in the present invention has a greater advantage. The MOS tube has an extremely small on-resistance and will not generate a large voltage drop at the load end in the working state.

[0019] When the driving power source 3 is positively connected, the second MOS tube Q2 is immediately turned on, and the GND end of the driving power source 3 is connected to the negative electrode of the capacitive load through the second MOS tube Q2.

[0020] When the single chip microcomputer outputs a high level, the first photocoupler U1 is turned on, the first MOS tube Q1 is turned on, and the +24V of the driving power supply 3 is connected to the positive electrode of the capacitive load through the thermistor R1, the source and drain of the first MOS tube Q1, and the capacitive load is charged. The principle of the setting of the thermistor R1 is that as the charging time of the capacitive load increases, the temperature of the thermistor R1 increases and the resistance decreases, thereby effectively controlling the slow rise of the charging current and reducing the current impact on the capacitive load.

[0021] When the single chip microcomputer outputs a low level, the first photocoupler U1 and the first MOS tube Q1 are turned off, thereby disconnecting the positive electrode of the capacitive load from the +24V of the driving power supply 3.

[0022] When the driving power supply 3 is reversely connected, the gates of the first and second MOS tubes Q1 and Q2 are connected to the GND terminal of the driving power supply 3. Therefore, the first and second MOS tubes Q1 and Q2 are turned off, and the driving power supply 3 cannot supply power to the capacitive load; at the same time, the first MOS tube Q1 is no longer controlled by the first photocoupler U1, thereby achieving the purpose of preventing reverse connection.

[0023] Pre-charging completion detection: The voltage-dividing resistors R6 and R7 are connected in series and in parallel with the capacitive load. The low potential end of the voltage-dividing resistor R6 is connected to the comparison input end of the comparison amplifier U3. When the capacitive load charging voltage rises and reaches the threshold of the comparison amplifier U3, the comparison amplifier U3 is turned on to open the first photocoupler U2, and the level of the microcontroller input end will be pulled low. This level signal informs the microcontroller that the pre-charging is completed and the subsequent control action can be started.

[0024] Reverse connection detection of driving power supply 3: In the case of reverse connection of driving power supply 3, when the single-chip microcomputer outputs a high level, the first and second MOS tubes Q1 and Q2 are both in the off state, so the comparison input voltage of the comparison amplifier U3 cannot reach the threshold value, and the input level of the single-chip microcomputer cannot be pulled down. When the input terminal is still not pulled down after a set time after the single-chip microcomputer outputs a high level, the single-chip microcomputer sends a reverse connection or damage signal to the host computer.

Claims

1. A capacitive load pre-charging control module with anti-reverse connection function, characterized in that: It includes a single-chip microcomputer, a load switch control unit, and a charging threshold detection unit; the load switch control unit is used to receive a driving power supply connection signal sent by the single-chip microcomputer, and judge the correctness of the input positive and negative poles of the driving power supply. When the positive and negative poles of the driving power supply are correctly connected, the driving power supply is connected to the capacitive load, and when the positive and negative poles of the driving power supply are reversed, the driving power supply is disconnected; the charging threshold detection unit is used to set the threshold of the capacitive load charging voltage and judge the correctness of the positive and negative poles of the driving power supply; when the capacitive load charging voltage reaches the threshold, a capacitive load charging completion signal is sent to the single-chip microcomputer; when the positive and negative poles of the driving power supply are reversed, a positive and negative pole reverse connection signal of the driving power supply is sent to the single-chip microcomputer after a delay setting time; The load switch control unit includes a first MOS tube Q1, a second MOS tube Q2 and a first photocoupler U1; the source of the first MOS tube Q1 is connected to the positive electrode of the driving power supply via the thermistor R1, the gate of the first MOS tube Q1 is connected to the positive electrode of the driving power supply via the resistor R4 and the thermistor R1, the drain of the first MOS tube Q1 is connected to the positive electrode of the capacitive load, and is connected to the source of the second MOS tube Q2 via the voltage-dividing resistors R6 and R7; the gate of the second MOS tube Q2 is connected to the positive electrode of the driving power supply via the resistor R9 and the thermistor R1, and the drain of the second MOS tube Q2 is connected to the negative electrode of the driving power supply; the positive electrode of the light-emitting diode of the first photocoupler U1 is connected to the output end of the single-chip computer via the resistor R2, and the The negative electrode of the capacitive load is connected to the positive electrode of the driving power supply via the emitter and collector of the phototransistor of the first photocoupler U1 and resistors R5, R4 and the thermistor R1; the charging threshold detection unit includes a second photocoupler U2 and a comparison amplifier U3; the comparison input end of the comparison amplifier U3 is connected to the low potential end of the voltage-dividing resistor R6, the high potential end of the comparison amplifier U3 is connected to the drain of the first MOS tube Q1 via the light-emitting diode of the second photocoupler U2 and the resistor R3, and the low potential end of the comparison amplifier U3 is connected to the negative electrode of the capacitive load; the collector of the phototransistor of the second photocoupler U2 is connected to the signal input end of the single-chip computer, and the emitter of the phototransistor of the second photocoupler U2 is connected to the digital ground.

2. The capacitive load pre-charging control module with anti-reverse connection function according to claim 1, characterized in that: The first MOS tube is a PMOS tube.

Images