Power supply pre-charging circuit
By designing a power supply pre-charge circuit in the motor power supply side circuit, and using the pre-charge module to charge the bus capacitor before the bidirectional switch is turned on, the problem of transient high current at the moment of charging of the bus capacitor in traditional circuits is solved, and the over-temperature damage of the MOS tube is avoided and the stable operation of the controller is ensured.
Patent Information
- Application Number
- CN202421133677.8
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-05-22
- Publication Date
- 2025-04-11
- Estimated Expiration
- 2034-05-22
AI Technical Summary
In the traditional motor power supply side circuit, the transient high current generated by the bus capacitor during the charging moment can easily cause the MOS tube to be overtemperature damage, and the power supply of the entire vehicle battery may be lowered, extending the controller power-on time.
Design a power supply power precharge circuit, including a bidirectional switch, an on-off drive module, a precharge module and a bus capacitor. Before the bidirectional switch is turned on, the precharge module draws power from the vehicle power supply through the body diode, charges the bus capacitor until the power is fully charged, thereby transferring charging power consumption to the precharge module.
It effectively avoids overtemperature damage to the bidirectional switch by the transient high current at the moment of charging of the bus capacitor, reduces the on-voltage drop of the bidirectional switch, reduces the power consumption and temperature rise, and ensures the stable operation of the controller.
Smart Images
Figure CN222750153U_ABST
Abstract
Description
Technical Field
[0001] The utility model relates to the technical field of integrated circuits, in particular to a power supply precharging circuit. Background Art
[0002] In traditional controller design, in order to isolate and disconnect the controller's power supply battery from the PMIC (power management chip) power supply, a back-to-back PMOS tube circuit solution is usually adopted, and the MCU controls the opening and closing of the bus side power supply. For details, see Figure 1 The motor power supply side circuit includes a vehicle power supply (Vbat), a bidirectional switch, a transistor (T3) and a bus capacitor (C). The bidirectional switch includes two PMOS tubes (T1 and T2) connected back to back (common drain connection). The MCU controls the on and off of the transistor, thereby controlling the on and off of the bidirectional switch. The vehicle power supply is connected to the motor through the bidirectional switch, and the bus capacitor is grounded between the bidirectional switch and the motor.
[0003] The power line between the motor and the bidirectional switch is the power bus (40). Since the power supply current of the power bus is usually small in practice and the ripple current is also small, only a single bus capacitor is required. During the power bus transmission process, when the power of the bus capacitor is 0, the transient charging current of the bus capacitor is large. In serious cases, the following three problems may occur: First, the PMOS tube connected to the motor in the bidirectional switch will be damaged; second, under the impact of large current, it is easy to cause the power supply of the whole vehicle battery to be instantly reduced, and the battery voltage of the whole vehicle is undervoltage; third, the chip powered by the power bus has an undervoltage function and needs to be repeatedly started, thereby extending the power-on time of the controller.
[0004] The traditional solution is to increase the parasitic capacitance (C GS ), thereby increasing the conduction time of the PMOS tube. This solution essentially transfers the transient power consumption of the bus capacitor to the PMOS tube connected to the motor in the bidirectional switch. The derivation formula is as follows:
[0005]
[0006] P MOSFET =I AVE ·V DS 0.5 (2);
[0007] ΔT=P MOSFET ·R thj (3);
[0008] From formula (1), we can see that the amount of electricity that C1 can store is CU. Prolonging the on-time T can reduce the average current I AVE, thus solving problems one and two; but R thj It is proportional to time. Prolonging the on-time T will increase the transient thermal resistance R thj , and increasing R thj According to formula (3), ΔT will still increase, so that the MOSFET is still at risk of damage in a high temperature and high voltage environment. Problem 1 cannot be solved, and the application scenarios of the controller of the whole vehicle are limited. Utility Model Content
[0009] The utility model aims to provide a power supply pre-charging circuit to solve the problem in the prior art that the transient large current generated by the bus capacitor charging moment of the motor power supply side circuit easily causes the MOS tube to be overheated and damaged.
[0010] In order to solve the above technical problems, the utility model provides a power supply pre-charging circuit, which includes a bidirectional switch, an on-off drive module, a pre-charging module and a bus capacitor;
[0011] One end of the bidirectional switch is used to connect to the vehicle power supply, the other end of the bidirectional switch leads to the power bus, the driving end of the bidirectional switch is connected to the on-off driving module, and the bus capacitor is connected to the power bus;
[0012] The input end of the pre-charging module is connected to the midpoint of the bidirectional switch, and the output end of the pre-charging module is connected to the power bus. The pre-charging module is used to draw power from the vehicle power supply through the body diode of the bidirectional switch close to the vehicle power supply to charge the bus capacitor before the on-off driving module drives the bidirectional switch to turn on.
[0013] Optionally, the pre-charging module includes a switch chip and a first resistor, the input end of the switch chip is connected to the midpoint of the bidirectional switch, and the output end of the switch chip is connected to the power bus through the first resistor.
[0014] Optionally, the bidirectional switch includes a first MOS tube and a second MOS tube of the same type, the source of the first MOS tube is connected to the vehicle power supply, the drain of the first MOS tube is connected to the drain of the second MOS tube, the source of the second MOS tube is led out of the power bus, and the gate of the first MOS tube and the gate of the second MOS tube are connected as the driving end of the bidirectional switch.
[0015] Optionally, both the first MOS transistor and the second MOS transistor are NMOS transistors.
[0016] Optionally, the on-off driving module includes a charge pump and a second resistor, and the charge pump is connected to the driving end of the bidirectional switch through the second resistor.
[0017] Optionally, the on-off driving module further includes a first power switch tube and a driving unit, the first power switch tube is connected in series between the charge pump and the second resistor, and the driving unit is used to drive the first power tube to be turned on or off.
[0018] Optionally, the first power switch tube is a PMOS tube or a PNP transistor.
[0019] Optionally, the driving unit includes a second power switch tube, a driving end of the first power switch tube is grounded through the second power switch tube, and a driving end of the second power switch tube is externally connected to a driving signal.
[0020] Optionally, the second power switch tube is an NPN transistor or an NMOS tube.
[0021] Optionally, the bus capacitor is a hybrid capacitor.
[0022] In summary, in the power supply pre-charging circuit provided by the utility model, the power supply pre-charging circuit includes a bidirectional switch, an on-off driving module, a pre-charging module and a bus capacitor; one end of the bidirectional switch is used to connect the power supply, the other end of the bidirectional switch leads to the power bus, the driving end of the bidirectional switch is connected to the on-off driving module, and the bus capacitor is connected to the power bus; the input end of the pre-charging module is connected to the midpoint of the bidirectional switch, and the output end of the pre-charging module is connected to the power bus, and the pre-charging module is used to take power from the vehicle power supply through the body diode close to the power supply side in the bidirectional switch before the on-off driving module drives the bidirectional switch to turn on to charge the bus capacitor. In this way, the utility model can be configured with a pre-charging module, and before the bidirectional switch is turned on, that is, before the load on the power bus is powered by the vehicle power supply, the bus capacitor can be charged by taking power from the vehicle power supply through the pre-charging module until the bus capacitor is fully charged, so that the power consumption of the bus capacitor charging can be transferred to the pre-charging module, avoiding the transient large current generated at the moment of charging the bus capacitor causing over-temperature damage to the inside of the bidirectional switch. In addition, when the bus capacitor is fully charged, the on-off drive module turns on the bidirectional switch, which can reduce the on-state voltage drop inside the bidirectional switch, thereby reducing power consumption and temperature rise changes to a minimum. BRIEF DESCRIPTION OF THE DRAWINGS
[0023] Those skilled in the art should understand that the drawings provided are for a better understanding of the present invention and do not constitute any limitation on the scope of the present invention.
[0024] Figure 1 It is a schematic diagram of a motor power supply side circuit in the prior art;
[0025] Figure 2 It is a schematic diagram of a power supply pre-charging circuit according to an embodiment of the utility model.
[0026] In the attached figure:
[0027] 10-bidirectional switch; 20-on / off drive module; 21-charge pump; 30-pre-charge module; 31-switch chip; 40-power bus;
[0028] Q1-first MOS tube; Q2-second MOS tube; Q3-first power switch tube; Q4-second power switch tube; Vbat-vehicle power supply; C-bus capacitor; R1-first resistor; R2-second resistor. DETAILED DESCRIPTION
[0029] In order to make the purpose, advantages and features of the utility model clearer, the utility model is further described in detail below in conjunction with the accompanying drawings and specific embodiments. It should be noted that the drawings are all in a very simplified form and are not drawn to scale, and are only used to conveniently and clearly assist in explaining the purpose of the embodiments of the utility model. In addition, the structure shown in the drawings is often a part of the actual structure. In particular, the emphasis of each drawing is different, and sometimes different scales are used.
[0030] As used in the present invention, the singular forms "one", "an" and "the" include plural objects, the term "or" is usually used to include the meaning of "and / or", the term "several" is usually used to include the meaning of "at least one", and the term "at least two" is usually used to include the meaning of "two or more". In addition, the terms "first", "second" and "third" are only used for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Therefore, the features defined as "first", "second" and "third" may explicitly or implicitly include one or at least two of the features, "one end" and "the other end" and "the proximal end" and "the distal end" generally refer to two corresponding parts, which not only include the endpoints, and the terms "installed", "connected" and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral one; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements. In addition, as used in the present invention, an element disposed on another element generally only indicates that there is a connection, coupling, cooperation or transmission relationship between the two elements, and the connection, coupling, cooperation or transmission between the two elements may be direct or indirect through an intermediate element, and cannot be understood as indicating or implying the spatial position relationship between the two elements, that is, an element may be in any orientation such as inside, outside, above, below or on one side of another element, unless otherwise clearly indicated in the content. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.
[0031] Figure 2 Schematic diagram of a power supply pre-charging circuit of an embodiment of the utility model. Figure 2As shown, an embodiment of the utility model schematically provides a power supply pre-charging circuit, including a bidirectional switch 10, an on-off driving module 20, a pre-charging module 30 and a bus capacitor C; one end of the bidirectional switch 10 is used to connect to the vehicle power supply Vbat, and the other end of the bidirectional switch 10 leads to the power bus 40, the driving end of the bidirectional switch 10 is connected to the on-off driving module 20, the bus capacitor C is connected to the power bus 40, and the power bus 40 is connected to the load, and the load here can be, for example, the PMIC (power management chip) of the controller to supply power or charge the load. The on-off driving module 20 is used to drive the bidirectional switch 10 to turn on or off. The input end of the pre-charging module 30 is connected to the midpoint of the bidirectional switch 10, and the output end of the pre-charging module 30 is connected to the power bus 40. The pre-charging module 30 is used to take power from the power supply through the body diode of the bidirectional switch 10 close to the vehicle power supply Vbat before the on-off driving module 20 drives the bidirectional switch 10 to turn on to charge the bus capacitor C. It can be understood by those skilled in the art that the bidirectional switch 10 can realize bidirectional shutoff of input and output as well as output and input for the circuit in which it is located. In this way, the utility model can first charge the bus capacitor C by taking power from the vehicle power supply Vbat through the pre-charging module 30 before the bidirectional switch 10 is turned on, that is, before the load on the power bus 40 is powered by the vehicle power supply Vbat, until the bus capacitor C is fully charged, so that the power consumption of charging the bus capacitor C can be transferred to the pre-charging module 30, avoiding the transient large current generated at the moment of charging the bus capacitor C to cause over-temperature damage to the inside of the bidirectional switch 10. In addition, when the bus capacitor C is fully charged, the on-off drive module 20 turns on the bidirectional switch 10, which can reduce the on-state voltage drop inside the bidirectional switch 10, thereby reducing the power consumption and temperature rise changes to a minimum.
[0032] Preferably, the bus capacitor C is a hybrid capacitor. A hybrid capacitor is a special capacitor that combines the characteristics of different types of capacitors and has higher performance and reliability. For example, it can be a conductive polymer solid hybrid patch electrolytic capacitor. A conductive polymer solid hybrid patch electrolytic capacitor is a capacitor with a conductive polymer solid electrolyte and a hybrid patch structure. It combines the high stability of the solid electrolyte and the convenience of the patch structure, so that the capacitor has higher performance and reliability.
[0033] Furthermore, the bidirectional switch 10 includes a first MOS tube Q1 and a second MOS tube Q2 of the same type, the source of the first MOS tube Q1 is connected to the vehicle power supply Vbat, the drain of the first MOS tube Q1 is connected to the drain of the second MOS tube Q2, that is, the drain of the first MOS tube Q1 and the drain of the second MOS tube Q2 are connected as the midpoint of the bidirectional switch 10, the source of the second MOS tube Q2 leads to the power bus 40, the gate of the first MOS tube Q1 and the gate of the second MOS tube Q2 are connected as the driving end of the bidirectional switch 10, and thus connected to the on-off driving module 20. It can be understood that the first MOS tube Q1 plays a role in preventing the power supply from being reversed. When the bus capacitor C is fully charged, the on-off driving module 20 turns on the bidirectional switch 10, which can reduce the V of the second MOS tube Q2. DS The voltage drop can be reduced to about 0V, thereby minimizing power consumption and temperature rise.
[0034] In this embodiment, the first MOS transistor Q1 and the second MOS transistor Q2 are both NMOS transistors. In some other embodiments, the first MOS transistor Q1 and the second MOS transistor Q2 may also be PMOS transistors. Compared with PMOS transistors, NMOS transistors have the characteristics of miniaturization and low cost, which better meets the development requirements of integrated circuits of future controllers.
[0035] Furthermore, for the bidirectional switch 10 composed of the first MOS tube Q1 and the second MOS tube Q2, the on-off driving module 20 includes a charge pump 21 and a second resistor R2, and the charge pump 21 is connected to the driving end of the bidirectional switch 10 through the second resistor R2. Specifically, the charge pump 21 can be turned on or off to control whether the charge pump 21 inputs a driving voltage to the driving end of the bidirectional switch 10, so as to control the on-off of the first MOS tube Q1 and the second MOS tube Q2. It should be noted that the on-off of the first MOS tube Q1 and the second MOS tube Q2 here specifically refers to the on-off between the source and the drain of the first MOS tube Q1, and the on-off between the source and the drain of the second MOS tube Q2.
[0036] Furthermore, the on-off driving module 20 also includes a first power switch tube Q3 and a driving unit, wherein the first power switch tube Q3 is connected in series between the charge pump 21 and the second resistor R2, and the driving unit is used to drive the first power tube to be turned on or off. The first power switch tube Q3 is a PMOS tube, the drain of the first power switch tube Q3 is connected to the charge pump 21, the source of the first power switch is connected to the second resistor R2, and the gate of the first power switch tube Q3 is connected to the driving unit. In some other embodiments, the first power switch tube Q3 can also be a PNP triode, the emitter of the first power switch tube Q3 is connected to the charge pump 21, the collector of the first power switch tube Q3 is connected to the second resistor R2, and the base of the first power switch tube Q3 is connected to the driving unit.
[0037] The driving unit includes a second power switch tube Q4, the driving end of the first power switch tube Q3 (the gate or base of the first power switch tube Q3) is grounded through the second power switch tube Q4, and the driving end of the second power switch tube Q4 is externally connected to a driving signal (MCU_V2). The driving signal is used to turn on or off the second power switch tube Q4, thereby controlling whether the driving end of the first power switch tube Q3 is grounded, and then controlling the on and off of the first power switch tube Q3. The second power switch tube Q4 is an NPN transistor, the collector of the second power switch tube Q4 is connected to the driving end of the first power switch tube Q3, the emitter of the second power switch tube Q4 is grounded, and the base of the second power switch tube Q4 is connected to the driving signal. In some other embodiments, the second power switch tube Q4 can also be an NMOS tube, the drain of the second power switch tube Q4 is connected to the driving end of the first pipeline power switch tube, and the gate of the second power switch tube Q4 is connected to the driving signal.
[0038] In this embodiment, the pre-charge module 30 includes a switch chip 31 and a first resistor R1. The input end of the switch chip 31 is connected to the midpoint of the bidirectional switch 10, that is, the drain of the first MOS tube Q1 and the drain of the second MOS tube Q2. The output end of the switch chip 31 is connected to the power bus 40 through the first resistor R1. The switch chip 31 is externally connected to the control signal (MCU_V1) to control the on-off. Before the bidirectional switch 10 is turned on, the switch chip 31 is in the on state. The switch chip 31 takes power from the vehicle power supply Vbat through the body diode of the first MOS tube Q1, and charges the bus capacitor C after passing through the first resistor R1. The voltage output by the switch chip 31 charges the bus capacitor C after passing through the first resistor R1. The generated impact current is the voltage output by the switch chip 31 divided by the value of the first resistor R1, so as to limit the impact current to the greatest extent through the first resistor R1, and transfer the power consumption of charging the bus capacitor C to the first resistor R1, which can reduce the design difficulty.
[0039] Although the utility model is disclosed as above with preferred embodiments, the above embodiments are not intended to limit the utility model. For any technician familiar with the art, without departing from the scope of the technical solution of the utility model, the above disclosed technical content can be used to make many possible changes and modifications to the technical solution of the utility model, or modified into equivalent embodiments with equivalent changes. Therefore, any simple modification, equivalent change and modification made to the above embodiments based on the technical essence of the utility model without departing from the content of the technical solution of the utility model still falls within the scope of protection of the technical solution of the utility model.
Claims
1. A power supply pre-charging circuit, characterized in that: It includes a bidirectional switch, an on-off drive module, a pre-charge module and a bus capacitor; One end of the bidirectional switch is used to connect to the vehicle power supply, the other end of the bidirectional switch leads to the power bus, the driving end of the bidirectional switch is connected to the on-off driving module, and the bus capacitor is connected to the power bus; The input end of the pre-charging module is connected to the midpoint of the bidirectional switch, and the output end of the pre-charging module is connected to the power bus. The pre-charging module is used to draw power from the vehicle power supply through the body diode of the bidirectional switch close to the vehicle power supply to charge the bus capacitor before the on-off driving module drives the bidirectional switch to turn on.
2. The power supply precharge circuit according to claim 1, wherein The pre-charging module includes a switch chip and a first resistor, the input end of the switch chip is connected to the midpoint of the bidirectional switch, and the output end of the switch chip is connected to the power bus through the first resistor.
3. The power supply precharge circuit according to claim 1, wherein The bidirectional switch includes a first MOS tube and a second MOS tube of the same type, the source of the first MOS tube is connected to the vehicle power supply, the drain of the first MOS tube is connected to the drain of the second MOS tube, the source of the second MOS tube leads to the power bus, and the gate of the first MOS tube and the gate of the second MOS tube are connected as the driving end of the bidirectional switch.
4. The power supply precharge circuit according to claim 3, wherein The first MOS tube and the second MOS tube are both NMOS tubes.
5. The power supply precharge circuit according to claim 1, wherein The on-off driving module includes a charge pump and a second resistor, and the charge pump is connected to the driving end of the bidirectional switch through the second resistor.
6. The power supply precharge circuit according to claim 5, characterized in that, The on-off driving module further includes a first power switch tube and a driving unit, wherein the first power switch tube is connected in series between the charge pump and the second resistor, and the driving unit is used to drive the first power switch tube to be turned on or off.
7. The power supply precharge circuit according to claim 6, wherein The first power switch tube is a PMOS tube or a PNP transistor.
8. The power supply precharge circuit according to claim 6, wherein The driving unit includes a second power switch tube, a driving end of the first power switch tube is grounded through the second power switch tube, and a driving end of the second power switch tube is externally connected to a driving signal.
9. The power supply precharge circuit according to claim 8, characterized in that, The second power switch tube is an NPN transistor or an NMOS tube.
10. The power supply pre-charging circuit according to claim 1, characterized in that: The bus capacitor is a mixed capacitor.