Power tube overcurrent protection circuit based on voltage monitoring reset chip
By introducing a protection delay recovery circuit with a voltage monitoring and reset chip into the power transistor overcurrent protection circuit, the problem of frequent cyclic damage to the power transistor due to short circuit faults is solved, thus simplifying the circuit and reducing costs.
Patent Information
- Application Number
- CN202423054080.7
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-12-11
- Publication Date
- 2025-12-12
- Estimated Expiration
- 2034-12-11
AI Technical Summary
Existing power transistor overcurrent protection circuits frequently cycle during short-circuit fault recovery, causing the power transistor to continuously operate in a high-frequency pulse high-current state, which is prone to damage due to continuous heat generation. In addition, the circuit structure is complex and costly.
A protection delay recovery circuit based on a voltage monitoring and reset chip is adopted. By delaying the recovery time of the power transistor, sufficient heat dissipation time is provided, reducing the probability of damage and simplifying the circuit structure.
It achieves short-circuit protection delayed recovery function, reduces the probability of power transistor damage, and keeps the circuit simple and low cost.
Smart Images
Figure CN223666025U_ABST
Abstract
Description
Technical Field
[0001] This utility model belongs to the field of vehicle drive circuit protection technology, specifically relating to a power transistor overcurrent protection circuit based on a voltage monitoring and reset chip. Background Technology
[0002] Vehicles use components such as relays, horns, and electromagnetic brakes. These components typically require a drive circuit to drive their coils to generate a magnetic field to operate. However, because the coils may overheat during operation, leading to insulation failure and short circuits, damage can occur. If the drive circuit lacks protection, this can exacerbate the damage. Therefore, overcurrent protection circuits are added to coil drive circuits to reduce the probability of damage.
[0003] Existing power transistor overcurrent protection circuits, such as Figure 1 As shown, the input signal is sent to the drive circuit via resistor R3 as a PWM signal. The drive circuit converts this signal into a drive signal for the power transistor, which is then input to the gate of Q1, causing Q1 to operate in a switching state. When Q1 is turned on, current flows through the load coil L1. If a short-circuit overcurrent occurs, the voltage across the sampling resistor R5 increases. This voltage is fed back to the voltage comparator U1 (input negative) via R4. If the voltage exceeds the protection value set by the voltage divider between R1 and R2 at the "input positive" terminal, the output of U1 will pull the PWM signal input to the drive circuit low to turn it off, thus achieving overcurrent protection.
[0004] Due to the structure of the protection circuit, the overcurrent condition disappears immediately after the drive is turned off. If the drive signal becomes effective again when a short circuit fault exists, the protection circuit enters the next cycle. Therefore, the power transistor continues to operate in a pulsed high current state, and the interval between each pulse is short. The power transistor will be damaged due to abnormal operation or continuous heating over a long period of time. Utility Model Content
[0005] To address the aforementioned problems in the existing technology, this utility model provides a power transistor overcurrent protection circuit based on a voltage monitoring and reset chip. After overcurrent protection, it has a delayed recovery time, allowing the power transistor in the drive circuit sufficient time to dissipate heat, reducing the probability of device damage, and thus ensuring the reliability of the drive circuit. In addition, it also has the advantages of simple circuit and low cost.
[0006] To achieve the above objectives, this utility model provides the following technical solution: a power transistor overcurrent protection circuit based on a voltage monitoring and reset chip, comprising a power transistor drive circuit, an overcurrent protection circuit, and a protection delay recovery circuit;
[0007] The power tube driving circuit is composed of a resistor R3, a driving circuit, a power tube Q1, a freewheeling diode D1 and a load inductor L1, the driving circuit is composed of discrete components or a driving chip, one end of the resistor R3 is connected to the input signal of the driving circuit, the other end of the resistor R3 is connected to the input of the driving circuit, the output of the driving circuit is connected to the gate of the power tube Q1, the anode of the freewheeling diode D1 is connected to the drain of the power tube Q1, the cathode of the freewheeling diode D1 is connected to the B+ power supply, and the load inductor L1 is connected in parallel with the freewheeling diode D1.
[0008] The overcurrent protection circuit is composed of a voltage comparator U1, a resistor R1, a resistor R2, a feedback resistor R4 and a sampling resistor R5, the resistor R1 and the resistor R2 are connected in series to form a voltage divider, the output of the voltage divider is connected to the positive input of the voltage comparator U1, one end of the sampling resistor R5 is connected to the source of the power tube Q1, the other end of the sampling resistor R5 is connected to the ground, one end of the feedback resistor R4 is connected to the source of the power tube Q1, and the other end of the feedback resistor R4 is connected to the negative input of the voltage comparator U1.
[0009] The protection delay recovery circuit is composed of a voltage monitoring reset chip U2 and a resistor R6, the monitoring pin VCC of the voltage monitoring reset chip U2 is connected to the output pin of the voltage comparator U1, one end of the resistor R6 is connected to the monitoring pin VCC of the voltage monitoring reset chip U2, the other end of the resistor R6 is connected to 5V, and the reset pin RST of the voltage monitoring reset chip U2 is connected to the input of the driving circuit.
[0010] As one of the preferred technical schemes of the power tube overcurrent protection circuit based on the voltage monitoring reset chip, the load inductor L1 provides a freewheeling loop for an inductive load.
[0011] As one of the preferred technical schemes of the power tube overcurrent protection circuit based on the voltage monitoring reset chip, the voltage divider provides a reference voltage for the voltage comparator U1.
[0012] As one of the preferred technical schemes of the power tube overcurrent protection circuit based on the voltage monitoring reset chip, 5V is a system power supply.
[0013] As one of the preferred technical schemes of the power tube overcurrent protection circuit based on the voltage monitoring reset chip, the input signal of the circuit is sent by an MCU.
[0014] Compared with the prior art, the power tube overcurrent protection circuit based on the voltage monitoring reset chip has the following beneficial effects:
[0015] The power tube overcurrent protection circuit based on the voltage monitoring reset chip has the short-circuit protection delay recovery function, can maintain the protection state for a period of time after a short circuit, reduces the working pressure of the power tube when the short-circuit fault lasts, and reduces the damage probability of the power tube, and has the characteristics of simple circuit and low cost. BRIEF DESCRIPTION OF DRAWINGS
[0016] The accompanying drawings are used to provide further understanding of the present application, and constitute a part of the specification, and are used to explain the present application together with embodiments of the present application, and do not constitute a limitation to the present application. In the drawings:
[0017] Figure 1 It is a structural schematic diagram of the power tube overcurrent protection circuit in the prior art;
[0018] Figure 2 It is a structural schematic diagram of the present application. DETAILED DESCRIPTION
[0019] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative work fall within the scope of protection of the present application. EMBODIMENT
[0020] Please refer to Figures 1-2 The present application provides the following technical solutions: a power tube overcurrent protection circuit based on a voltage monitoring reset chip, comprising a power tube driving circuit, an overcurrent protection circuit, and a protection delay recovery circuit.
[0021] Further, the power tube driving circuit is composed of a resistor R3, a driving circuit, a power tube Q1, a freewheeling diode D1, and a load inductor L1. The driving circuit is composed of discrete components or a driving chip. One end of the resistor R3 is connected to the input signal of the driving circuit, and the other end of the resistor R3 is connected to the input of the driving circuit. The output of the driving circuit is connected to the gate of the power tube Q1. The anode of the freewheeling diode D1 is connected to the drain of the power tube Q1, and the cathode of the freewheeling diode D1 is connected to the B+ power supply. The load coil L1 is connected in parallel with the freewheeling diode D1, and provides a freewheeling loop for the inductive load.
[0022] Further, the overcurrent protection circuit is composed of a voltage comparator U1, a resistor R1, a resistor R2, a feedback resistor R4, and a sampling resistor R5. The resistor R1 and the resistor R2 are connected in series to form a voltage divider. The output of the voltage divider is connected to the "positive input" of the voltage comparator U1, and provides a reference voltage for the voltage comparator U1. One end of the sampling resistor R5 is connected to the source of the power tube Q1, and the other end of the sampling resistor R5 is connected to the ground. One end of the feedback resistor R4 is connected to the source of the power tube Q1, and the other end of the feedback resistor R4 is connected to the "negative input" of the voltage comparator U1.
[0023] Further, the protection delay recovery circuit is composed of the voltage monitoring reset chip U2 and the resistor R6, the voltage monitoring reset chip U2 monitors the output pin of the voltage comparator U1, one end of the resistor R6 is connected with the voltage monitoring reset chip U2, the other end of the resistor R6 is connected with 5V, and the reset pin RST of the voltage monitoring reset chip U2 is connected with the input of the driving circuit.
[0024] Further, the circuit input signal is sent by the MCU, and 5V is the system power supply.
[0025] The use process and working principle of the utility model are as follows: when the circuit works, the MCU sends a PWM signal, which is converted into a power tube driving signal by the driving circuit and is input into the gate of Q1, after the power tube is turned on, the current flows through the coil load from B+, if the load is short-circuited at this time, the voltage at the two ends of R5 rises, this voltage enters the voltage comparator U1 through the feedback resistor R4, and is compared with the 'input positive' voltage, if it is higher than the protection reference value set by R1 and R2, the U1 output will pull down the voltage monitoring pin of U2, and then U2 will actively pull down the RST reset pin, that is, the PWM signal input into the driving circuit, and then the corresponding power tube Q1 is closed, since U2 needs to wait for 200ms after the input voltage is restored to exit the low level state and return to normal work, Q1 is in the closed state in this time, and the power tube has enough heat dissipation and cooling time, so it will not be damaged due to the high-frequency pulse and large current state of the power tube in the prior art.
[0026] The utility model has the functions of short-circuit protection delay recovery, maintains the protection state for a period of time after short-circuit, reduces the working pressure of the power tube when the short-circuit fault exists, reduces the damage probability, and has the characteristics of simple circuit and low cost.
[0027] Other alternative schemes of the utility model: the power tube in the circuit can use MOS, triode, chips with similar functions or other components with switching properties, etc.; the voltage monitoring reset chip can use other devices or chips with similar functional properties, which can all complete the above technical solutions.
[0028] In addition, the contents not described in detail in the embodiment are all in the scope of prior art and common knowledge.
[0029] Finally, it should be noted that: the above only for the preferred embodiments of the present application, and is not intended to limit the present application, although the foregoing embodiments of the present application have been described in detail, for the skilled in the art, it still can be modified, or for the equivalent replacement of part of the technical features of the technical solutions recorded in the foregoing embodiments. Any modification, equivalent replacement, improvement, etc. made within the spirit and principles of the present application, shall be included within the scope of the present application.
Claims
1. A power transistor overcurrent protection circuit based on a voltage monitoring and reset chip, characterized in that: Includes power transistor drive circuit, overcurrent protection circuit, and protection delay recovery circuit; The power transistor drive circuit consists of resistor R3, drive circuit, power transistor Q1, freewheeling diode D1, and load inductor L1. The drive circuit is composed of discrete components or a drive chip. The input signal of the drive circuit is connected to one end of resistor R3, and the other end of resistor R3 is connected to the input of the drive circuit. The output of the drive circuit is connected to the gate of power transistor Q1. The anode of freewheeling diode D1 is connected to the drain of power transistor Q1, and the cathode of freewheeling diode D1 is connected to the B+ power supply. The load coil L1 is connected in parallel with freewheeling diode D1. The overcurrent protection circuit consists of a voltage comparator U1, resistors R1 and R2, a feedback resistor R4, and a sampling resistor R5. Resistors R1 and R2 are connected in series to form a voltage divider, and the output of the voltage divider is connected to the "positive input" of the voltage comparator U1. One end of the sampling resistor R5 is connected to the source of the power transistor Q1, and the other end of the sampling resistor R5 is grounded. One end of the feedback resistor R4 is connected to the source of the power transistor Q1, and the other end of the feedback resistor R4 is connected to the "negative input" of the voltage comparator U1. The protection delay recovery circuit consists of a voltage monitoring and reset chip U2 and a resistor R6. The monitoring pin VCC of the voltage monitoring and reset chip U2 is connected to the output pin of the voltage comparator U1. One end of the resistor R6 is connected to the monitoring pin VCC of the voltage monitoring and reset chip U2, and the other end of the resistor R6 is connected to 5V. The reset pin RST of the voltage monitoring and reset chip U2 is connected to the input of the drive circuit.
2. The power transistor overcurrent protection circuit based on a voltage monitoring and reset chip according to claim 1, characterized in that: The load coil L1 provides a freewheeling circuit for the inductive load.
3. The power transistor overcurrent protection circuit based on a voltage monitoring and reset chip according to claim 1, characterized in that: The voltage divider provides a reference voltage for the voltage comparator U1.
4. The power transistor overcurrent protection circuit based on a voltage monitoring and reset chip according to claim 1, characterized in that: 5V is the system power supply.
5. The power transistor overcurrent protection circuit based on a voltage monitoring and reset chip according to claim 1, characterized in that: The input signal for this circuit is generated by the MCU.