A power switching circuit and method

Abstract

The present application relates to the field of power supply circuit technical field, particularly relates to a kind of power supply switching circuit and method.The circuit includes the first power supply subcircuit and the second power supply subcircuit in parallel, and the power supply of first power supply subcircuit and second power supply subcircuit is switched by control unit to realize switch unit.Control unit generates control logic by software programming, and the control instruction generated by control logic controls the on-off of switch unit, and realizes the switching of power supply subcircuit.The control mode of software hardware combination realizes the function of double-path battery intelligent switching for inductive load power supply, solves the deficiency of traditional scheme driving inductive load.In the control logic designed by the present application, the switching step is optimized, the time required for switching is reduced, and the response speed of system is improved.

Description

Technical Field

[0001] This invention relates to the field of power supply circuit technology, and in particular to a power switching circuit and method. Background Technology

[0002] With the increasing intelligence of driving systems, the requirements for functional safety are becoming more stringent. To meet the high-level safety requirements of driving and avoid controller failure due to battery failure, dual-power redundancy design is gradually being widely applied to vehicle systems. When one battery fails, it is necessary to seamlessly switch to the other battery to ensure the power supply needs of the controller and guarantee its normal operation.

[0003] like Figure 1 or Figure 2 As shown, the traditional design uses a diode or a MOS switch in the form of an ideal diode for switching. Utilizing the reverse turn-off characteristic of the diode, a rapid switch from a low-level battery to a high-level battery can be achieved. However, when driving inductive loads such as motors, a back electromotive force (EMF) can be generated under conditions such as motor reversal or a sudden drop in duty cycle. If a diode solution is used, the reverse cut-off characteristic of the diode will cause the power supply path to shut down. The energy from the inductive load, such as the motor, cannot charge the battery, resulting in an abnormal voltage rise, which could potentially damage internal components such as the controller's chips.

[0004] While diode-based switching solves the technical problem of rapid switching, its reverse turn-off function makes this solution unsuitable for power switching in inductive load control scenarios. Furthermore, when using MOSFETs for power switching, hardware circuitry compares voltages, utilizing the hardware's fast response to drive the MOSFET with the higher voltage. However, this traditional hardware circuitry can only compare high and low voltages and cannot accurately determine the voltage status. For example, if one battery has an overvoltage while another has a normal voltage, it cannot switch to the normal battery, thus failing to protect the hardware circuitry from damage. Moreover, traditional diode solutions cannot recover the reverse electromotive force (EMF) generated by the inductive circuit, i.e., charge the battery. Therefore, in the context of increasingly demanding smart technologies, these traditional solutions clearly have significant shortcomings. Summary of the Invention

[0005] This invention discloses a power switching circuit and method that can achieve safe power supply and power switching for inductive loads.

[0006] To achieve the above objectives, on the one hand, a power switching circuit is provided, the circuit including a first power supply circuit and a second power supply circuit connected in parallel, the input terminals of the first power supply circuit and the second power supply circuit being electrically connected to the output terminals of corresponding power supplies, and the output terminals of the first power supply circuit and the second power supply circuit being electrically connected to the same load.

[0007] The first power supply circuit includes a first switching unit and a first control unit, and the second power supply circuit includes a second switching unit and a second control unit;

[0008] The first switching unit executes the control commands sent by the first control unit to switch the first power supply circuit on and off; the second switching unit executes the control commands sent by the second control unit to switch the second power supply circuit on and off.

[0009] The first control unit and the second control unit determine control commands based on the input voltage of the first power supply circuit, the input voltage of the second power supply circuit, and the output voltage of the first or / and second power supply circuits.

[0010] Furthermore, both the first switching unit and the second switching unit include two N-channel MOSFETs connected in series back to back; the first switching unit corresponds to the first MOSFET and the second MOSFET, and the second switching unit corresponds to the third MOSFET and the fourth MOSFET.

[0011] The drain port of the first MOSFET is the corresponding power supply connection port, the source port of the first MOSFET is connected to the source port of the second MOSFET, and the drain port of the second MOSFET is the load connection port; the gate port of the first MOSFET and the gate port of the second MOSFET are both connected to the first control unit.

[0012] The drain port of the third MOSFET is the corresponding power supply connection port, the source port of the third MOSFET is connected to the source port of the fourth MOSFET, and the drain port of the fourth MOSFET is the load connection port; the gate ports of the third MOSFET and the gate ports of the fourth MOSFET are both connected to the second control unit.

[0013] Furthermore, the first control unit includes a first charge pump and a first gate driver, and the second control unit includes a second charge pump and a second gate driver;

[0014] The first charge pump provides operating power to the first gate driver, and the output terminal of the first gate driver is connected to the gate port of the first MOSFET and the gate port of the second MOSFET.

[0015] The second charge pump provides operating power to the second gate driver, and the output of the second gate driver is connected to the gate port of the third MOSFET and the gate port of the fourth MOSFET.

[0016] Furthermore, the power supply includes a first battery and a second battery;

[0017] The first battery is connected to the load via the first power supply circuit;

[0018] The second battery is connected to the load via a second power supply circuit.

[0019] Furthermore, the load is an inductive load.

[0020] To achieve the above objectives, another method for power switching is provided, wherein when the voltages of the first battery and the second battery are within a preset range, the first battery supplies power to the inductive load; and when the voltage of the first battery is not within the preset range but the voltage of the second battery is within the preset range, the second battery is switched to supply power to the inductive load.

[0021] Furthermore, the inductive load is powered by the first storage battery, specifically as follows:

[0022] When powered on, the first charge pump and the second charge pump are turned on simultaneously. When it is determined that the voltage of the first battery and the second battery are within a preset range, the first gate driver is turned on and the second gate driver is turned off.

[0023] Furthermore, the second battery is switched to supply power to the inductive load, as follows:

[0024] Simultaneously, the first charge pump and the first gate driver are turned off, and a preset time is delayed to ensure that the first MOSFET and the second MOSFET are turned off completely.

[0025] While delaying for a preset time, the second charge pump is started to boost the voltage, and the second gate driver is turned on when the preset delay ends.

[0026] To achieve the above objectives, on the other hand, a storage medium is provided that stores several instructions, and a processor loads the instructions to execute the power switching method described above.

[0027] Due to the adoption of the above technical solutions, the present invention has the following beneficial effects:

[0028] 1. The control unit generates control logic through software programming. The control commands generated by the control logic control the switching unit to switch on and off, thereby switching the power supply circuit. This software and hardware combined control method realizes the intelligent switching function of dual-battery power supply to inductive loads, solving the shortcomings of traditional solutions for driving inductive loads.

[0029] 2. Two N-channel MOSFETs connected back-to-back in series can be controlled and driven by the same gate driver, which can effectively avoid power supply failures caused by reverse electromotive force generated by inductive loads.

[0030] 3. The control logic designed in this invention optimizes the switching steps, reduces the time required for switching, and improves the system's response speed.

[0031] It should be noted that the terms "first," "second," and similar terms used in this article are merely for describing the constituent elements of the technical solution and do not constitute a limitation on the technical solution, nor should they be interpreted as an indication or implication of the importance of the corresponding elements; elements with terms such as "first," "second," or similar terms indicate that at least one of the elements is included in the corresponding technical solution. Attached Figure Description

[0032] To more clearly illustrate the technical solution of the present invention and facilitate a further understanding of its technical effects, features, and objectives, the present invention will be described in detail below with reference to the accompanying drawings. The drawings constitute an essential part of the specification and are used together with Embodiment 1 of the present invention to illustrate the technical solution of the present invention, but do not constitute a limitation on the present invention.

[0033] The same reference numerals in the attached diagrams represent the same parts, specifically:

[0034] Figure 1 It is a traditional diode-type dual power supply switching circuit.

[0035] Figure 2 It is a traditional diode + MOS dual power supply switching circuit.

[0036] Figure 3 This is a schematic diagram of the power switching circuit structure in Example 1. Detailed Implementation

[0037] The present invention will be further described in detail below with reference to the accompanying drawings and embodiments. Of course, the specific embodiments described below are merely illustrative of the technical solutions of the present invention, and not intended to limit the invention. Furthermore, the parts described in the embodiments or drawings are merely illustrative examples of relevant parts of the present invention, and not the entirety of the invention.

[0038] Example 1:

[0039] A power switching circuit, such as Figure 3As shown, the circuit includes a first power supply circuit and a second power supply circuit connected in parallel. The input terminals of the first power supply circuit and the second power supply circuit are electrically connected to the corresponding power supply output terminals, and the output terminals of both the first power supply circuit and the second power supply circuit are electrically connected to the same load. The first power supply circuit includes a first switching unit and a first control unit, and the second power supply circuit includes a second switching unit and a second control unit. The first switching unit executes the control commands sent by the first control unit to switch the first power supply circuit on and off. The second switching unit executes the control commands sent by the second control unit to switch the second power supply circuit on and off. The first control unit and the second control unit determine the control commands based on the input voltage of the first power supply circuit, the input voltage of the second power supply circuit, and the output voltage of the first or / and second power supply circuits.

[0040] Both the first and second switching units include two N-channel MOSFETs connected back-to-back in series; the first switching unit corresponds to the first MOSFET and the second MOSFET. Figure 3 The first MOSFET corresponds to T1, and the second MOSFET corresponds to T2; the second switching unit corresponds to the third and fourth MOSFETs. Figure 3 The third MOSFET corresponds to T3, and the fourth MOSFET corresponds to T4; the drain port of the first MOSFET is the corresponding power supply connection port, the source port of the first MOSFET is connected to the source port of the second MOSFET, and the drain port of the second MOSFET is the load connection port; the gate ports of the first MOSFET and the second MOSFET are both connected to the first control unit; the drain port of the third MOSFET is the corresponding power supply connection port, the source port of the third MOSFET is connected to the source port of the fourth MOSFET, and the drain port of the fourth MOSFET is the load connection port; the gate ports of the third MOSFET and the fourth MOSFET are both connected to the second control unit.

[0041] In this embodiment, when the voltages of both batteries are within the normal range (e.g., 9-16V) as obtained by the AD acquisition circuit, the first battery is selected for power supply by default. This means that the software controls the first gate driver to open circuits T1 and T2. In this case, even if an inductive load such as a motor generates a back electromotive force under specific operating conditions, the motor's power supply path will not be automatically cut off.

[0042] When the software detects an abnormal voltage in the first battery (either too high or too low), while the voltage of the second battery is within the normal range, it first stops the inductive load to prevent it from consuming power and causing the system voltage to drop too low. Then, it shuts down transistors T1 and T2, delaying T1 to ensure the MOSFETs are fully off. Next, it turns on transistors T3 and T4, delaying T2 again to ensure the MOSFETs are fully on. Once the software detects that the current system supply voltage equals the voltage of the second battery, indicating that the system has successfully switched to power from each of the two batteries, it restarts the inductive load.

[0043] In this embodiment, the charge pump raises the battery voltage to a level that enables the MOS to turn on, while the gate driver drives two external back-to-back N-channel MOSFETs to turn on, thereby achieving the dual functions of reverse polarity protection and disconnecting the system power supply.

[0044] Example 2:

[0045] A power supply switching method, wherein when the voltages of a first battery and a second battery are within a preset range, the first battery supplies power to the inductive load; when the voltage of the first battery is outside the preset range but the voltage of the second battery is within the preset range, the second battery is switched to supply power to the inductive load. The specific steps of the power supply switching are as follows:

[0046] S1. When power is applied, the first charge pump and the second charge pump are turned on simultaneously. When it is determined that the voltage of the first battery and the second battery are within a preset range, the first gate driver is turned on and the second gate driver is turned off.

[0047] S2. Determine whether it is necessary to switch to the second battery for power supply. If so, proceed to step S3.

[0048] S3. Simultaneously shut down Charge pump 1 and the first gate driver to shorten the turn-off time. When selecting a MOSFET, choose one that can turn off quickly to reduce the turn-off time.

[0049] S4. Delay a preset time to ensure that the first MOSFET and the second MOSFET are turned off. While delaying the preset time, start the second charge pump to boost the voltage. When the preset time ends, turn on the second gate driver.

[0050] To ensure that external MOSFETs can be driven above their specified turn-on threshold voltage, the voltage difference between the charge pump voltage and the battery must be higher than the undervoltage lockout threshold, typically 6.5V, before the internal gate driver is enabled. The initial gate driver enable delay, i.e., the time delay between the charge pump voltage boost and the MOSFET turn-on voltage, is calculated as follows:

[0051]

[0052] In the formula, C (VCAP) For the charge pump capacitor connected across the VS and VCAP pins, V (VCAP_UVLOR) = 6.5V (typical)

[0053] In this embodiment, C(VCAP) is configured as 470nF. The calculated charge pump start-up time T(DRV_EN) is approximately 75.01µs. Switching to the second battery power supply inevitably requires starting the charge pump. If the second charge pump's pumping process is initiated earlier, this step can be skipped when switching to the second battery, thus saving control time.

[0054] This embodiment advances the second charge pump startup process to the system power-on stage, avoiding the charge pump startup time during power supply switching, and uses a driver with a strong gate current, which greatly speeds up the entire switching response time.

[0055] It should be noted that the above embodiments are only for more clearly illustrating the technical solution of the present invention. Those skilled in the art will understand that the implementation of the present invention is not limited to the above content. Any obvious changes, substitutions or replacements made based on the above content do not exceed the scope of the technical solution of the present invention. Other implementations will also fall within the scope of the present invention without departing from the concept of the present invention.

Claims

1. A power switching circuit, characterized in that, The circuit includes a first power supply circuit and a second power supply circuit connected in parallel. The input terminals of the first power supply circuit and the second power supply circuit are electrically connected to the output terminals of the corresponding power supplies, and the output terminals of the first power supply circuit and the second power supply circuit are both electrically connected to the same load. The first power supply circuit includes a first switching unit and a first control unit, and the second power supply circuit includes a second switching unit and a second control unit; The first switching unit executes the control commands sent by the first control unit to switch the first power supply circuit on and off; the second switching unit executes the control commands sent by the second control unit to switch the second power supply circuit on and off. The first control unit and the second control unit determine control commands based on the input voltage of the first power supply circuit, the input voltage of the second power supply circuit, and the output voltage of the first or / and second power supply circuits.

2. The power switching circuit as described in claim 1, characterized in that, The first switching unit and the second switching unit each include two N-channel MOSFETs connected in series back to back; the first switching unit corresponds to the first MOSFET and the second MOSFET, and the second switching unit corresponds to the third MOSFET and the fourth MOSFET; The drain port of the first MOSFET is the corresponding power supply connection port, the source port of the first MOSFET is connected to the source port of the second MOSFET, and the drain port of the second MOSFET is the load connection port; the gate port of the first MOSFET and the gate port of the second MOSFET are both connected to the first control unit. The drain port of the third MOSFET is the corresponding power supply connection port, the source port of the third MOSFET is connected to the source port of the fourth MOSFET, and the drain port of the fourth MOSFET is the load connection port; the gate ports of the third MOSFET and the gate ports of the fourth MOSFET are both connected to the second control unit.

3. The power switching circuit as described in claim 2, characterized in that, The first control unit includes a first charge pump and a first gate driver, and the second control unit includes a second charge pump and a second gate driver; The first charge pump provides operating power to the first gate driver, and the output terminal of the first gate driver is connected to the gate port of the first MOSFET and the gate port of the second MOSFET. The second charge pump provides operating power to the second gate driver, and the output of the second gate driver is connected to the gate port of the third MOSFET and the gate port of the fourth MOSFET.

4. The power switching circuit as described in claim 1, characterized in that, The power supply includes a first battery and a second battery. The first battery is connected to the load via the first power supply circuit; The second battery is connected to the load via a second power supply circuit.

5. The power switching circuit as described in claim 1, characterized in that, The load is an inductive load.

6. A method for power switching, characterized in that, When the voltages of the first and second batteries are within a preset range, the first battery powers the inductive load; when the voltage of the first battery is outside the preset range but the voltage of the second battery is within the preset range, the second battery powers the inductive load.

7. The power switching method as described in claim 6, characterized in that, The inductive load is powered by the first storage battery, and the specific method is as follows: When powered on, the first charge pump and the second charge pump are turned on simultaneously. When it is determined that the voltage of the first battery and the second battery are within a preset range, the first gate driver is turned on and the second gate driver is turned off.

8. The power switching method as described in claim 6, characterized in that, The specific method for switching the second battery to power the inductive load is as follows: Simultaneously, the first charge pump and the first gate driver are turned off, and a preset time is delayed to ensure that the first MOSFET and the second MOSFET are turned off completely. While delaying for a preset time, the second charge pump is started to boost the voltage, and the second gate driver is turned on when the preset delay ends.

9. A storage medium, characterized in that, The processor stores several instructions, which are loaded by the processor to execute the power switching method as described in claims 6 to 8.

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