Wiper drive circuit

Abstract

The utility model provides a kind of wiper drive circuit, including first half bridge, second half bridge and electromotive force cut-off unit, by at least two MOS tubes of series connection between the output end of first half bridge and the low speed end of wiper motor is set, can cut off reverse induction electromotive force to reach power supply voltage, and at least two low voltage MOS tubes series connection replaces a high voltage MOS tube, even if the reverse induction electromotive force generated by wiper motor in high speed mode breaks through the MOS tube of low speed end close to wiper relay, but cannot break through the MOS tube of rear stage, still cut off to reverse induction electromotive force has played the effect.The utility model is applicable to all front windshield mechanical wiper application scene, the series connection design scheme of MOS tube can save area controller volume and weight, and no noise, response speed is faster, improve user driving experience;And at least two low voltage MOS tubes series connection replaces a high voltage MOS tube, can reduce overall scheme cost, improve the product competitiveness of area controller.

Description

Technical Field

[0001] This utility model relates to the field of automotive technology, and in particular to a windshield wiper drive circuit. Background Technology

[0002] Mechanical windshield wipers are active safety devices that provide windshield cleaning and washing functions in rainy or snowy weather, preventing obstruction of vision. They play an indispensable role in ensuring driving safety, improving the driving experience, and protecting the vehicle.

[0003] Front wiper drives are typically integrated into domain controllers. For windshield wiper drive designs, there's usually a requirement for the domain controller to activate the low-speed wipers after entering Limphome mode, regardless of the wiper motor's previous mode (brake / low speed / high speed). Furthermore, because the low-speed and high-speed windings inside the mechanical wiper motor are mechanically coupled, when the high-speed winding drives the front wiper motor at high speed, the low-speed winding acts as a generator. In this situation, the low-speed winding can generate a reverse induced electromotive force (EMF) greater than the power supply voltage. This induced EMF needs to be cut off to prevent it from being transmitted to the power supply voltage.

[0004] Therefore, for windshield wiper drive scenarios, a circuit is required to support the following requirements:

[0005] 1. Supports low-speed mode, high-speed mode, and braking mode;

[0006] 2. High-speed mode drive can cut off the induced electromotive force generated by the low-speed winding.

[0007] 3. After the domain controller enters Limphome mode, it can control the front wiper drive to enter low-speed mode.

[0008] 4. Low-cost solution. Utility Model Content

[0009] The purpose of this invention is to provide a wiper drive circuit that can cut off the reverse induced electromotive force generated by the wiper motor in high-speed mode.

[0010] To solve the above-mentioned technical problems, this utility model provides a wiper drive circuit, which includes:

[0011] The first half-bridge has its upper section connected to the power supply voltage and its lower section grounded.

[0012] The second half-bridge has its upper section connected to the power supply voltage and its lower section grounded. The output of the second half-bridge is used to connect to the high-speed end of the wiper motor.

[0013] The electromotive force cutoff unit includes at least two MOS transistors connected in series between the output terminal of the first half-bridge and the low-speed terminal of the wiper motor, and the parasitic diodes of the MOS transistors are directed from the output terminal of the first half-bridge to the low-speed terminal of the wiper motor.

[0014] Optionally, the first half-bridge includes a first power switch and a second power switch. One end of the first power switch is connected to the power supply voltage, and the other end of the first power switch and one end of the second power switch are connected as the output terminal of the first half-bridge. The other end of the second power switch is grounded.

[0015] The second half-bridge includes a third power switch and a fourth power switch. One end of the third power switch is connected to the power supply voltage, and the other end of the third power switch and one end of the fourth power switch are connected as the output terminal of the second half-bridge. The other end of the fourth power switch is grounded.

[0016] Optionally, the MOS transistor in the electromotive force cutoff unit is an NMOS transistor.

[0017] Optionally, the wiper drive circuit further includes a power drive unit, which is used to adjust the working state of the first half-bridge, the second half-bridge and the electromotive force cutoff unit respectively, so that the wiper motor works in braking mode, low speed mode or high speed mode.

[0018] When the wiper motor is operating in braking mode, the lower segment of the first half-bridge and the MOSFET are both turned on, while the upper segment of the first half-bridge, the upper segment of the second half-bridge, and the lower segment are all turned off.

[0019] When the wiper motor is operating in low-speed mode, the upper segment of the first half-bridge and the MOSFET are both turned on, while the lower segment of the first half-bridge and the upper and lower segments of the second half-bridge are all turned off.

[0020] When the wiper motor is operating in high-speed mode, the upper segment of the second half-bridge is turned on, while the upper and lower segments of the first half-bridge, the lower segment of the second half-bridge, and the MOSFET are all turned off.

[0021] Optionally, the power drive unit is also used to drive the wiper motor from the low speed mode to the low speed continuous current mode;

[0022] When the wiper motor operates in low-speed freewheeling mode, the lower segment of the first half-bridge and the MOSFET are both turned on, while the upper segment of the first half-bridge and the upper and lower segments of the second half-bridge are all turned off.

[0023] Optionally, the power drive unit is also used to drive the wiper motor from the high-speed mode to the high-speed continuous current mode;

[0024] When the wiper motor operates in high-speed freewheeling mode, the lower segment of the second half-bridge is turned on, while the upper and lower segments of the first half-bridge, the upper segment of the second half-bridge, and the MOSFET are all turned off.

[0025] Optionally, the power drive unit has a first enable pin, a second enable pin, a third enable pin, and a fourth enable pin;

[0026] When the signal of the third enable pin is a first level signal and the signal of the first enable pin is a first level signal, the power drive unit drives the upper bridge segment of the first half-bridge to be turned on and drives the lower bridge segment of the first half-bridge to be turned off.

[0027] When the signal of the third enable pin is a first level signal and the signal of the first enable pin is a second level signal, the power drive unit drives the upper bridge segment of the first half-bridge to turn off and drives the lower bridge segment of the first half-bridge to turn on.

[0028] When the signal of the third enable pin is a second level signal, the power drive unit drives both the upper and lower bridge segments of the first half-bridge to turn off.

[0029] When the signal of the fourth enable pin is a first level signal and the signal of the second enable pin is a first level signal, the power drive unit drives the upper bridge segment of the second half-bridge to be turned on and drives the lower bridge segment of the second half-bridge to be turned off.

[0030] When the signal of the fourth enable pin is a first level signal and the signal of the second enable pin is a second level signal, the power drive unit drives the upper bridge segment of the second half-bridge to turn off and drives the lower bridge segment of the second half-bridge to turn on.

[0031] When the signal of the fourth enable pin is a second level signal, the power drive unit drives both the upper and lower segments of the second half-bridge to turn off.

[0032] Optionally, the wiper drive circuit further includes a signal transmission circuit. The input terminal of the signal transmission circuit acquires the bias signal output by the power drive unit. The output terminal of the signal transmission circuit is connected to the electromotive force cutoff unit. The drive terminal of the signal transmission circuit is connected to the third enable pin. The bias signal is used to turn on the MOS transistor of the electromotive force cutoff unit.

[0033] Specifically, the first level signal of the third enable pin drives the signal transmission circuit to form a path between its input and output terminals to transmit the bias signal to the electromotive force cutoff unit, and the second level signal of the third enable pin drives the signal transmission circuit to form an open circuit between its input and output terminals to isolate the bias signal from being transmitted to the electromotive force cutoff unit.

[0034] Optionally, the signal transmission circuit includes a fifth power switch, a sixth power switch, a first resistor, a second resistor, a third resistor, and a fourth resistor. The first terminal of the fifth power switch serves as the input terminal of the signal transmission circuit, and the second terminal of the fifth power switch serves as the output terminal of the signal transmission circuit. The first resistor is connected between the first terminal and the driving terminal of the fifth power switch. The first terminal of the sixth power switch is connected to the driving terminal of the fifth power switch through the second resistor. The second terminal of the sixth power switch is grounded. The fourth resistor is connected between the driving terminal and the second terminal of the sixth power switch. The driving terminal of the sixth power switch is connected to the third enable pin through the third resistor.

[0035] Optionally, when the power drive unit receives a limp-mode signal from the vehicle domain controller, it will drive the wiper motor to operate in low-speed mode.

[0036] Optionally, the power drive unit sets both the signal of the first enable pin and the signal of the third enable pin to a first level signal by the limp mode signal.

[0037] Optionally, the power drive unit includes a dual-channel pre-drive chip.

[0038] The wiper drive circuit described above, by connecting at least two MOSFETs in series between the output of the first half-bridge and the low-speed end of the wiper motor, can block the reverse induced electromotive force from reaching the power supply voltage. Furthermore, by replacing one high-voltage MOSFET with at least two low-voltage MOSFETs in series, even if the reverse induced electromotive force generated by the wiper motor in high-speed mode breaks down the MOSFET near the low-speed end of the wiper relay, it cannot break down the MOSFETs in subsequent stages, thus still effectively blocking the reverse induced electromotive force. This invention is applicable to all applications of mechanical windshield wipers. The series-connected MOSFET design saves on the size and weight of the domain controller, is noiseless, has a faster response speed, and improves the user's driving experience. Moreover, replacing one high-voltage MOSFET with at least two low-voltage MOSFETs in series reduces the overall solution cost and enhances the product competitiveness of the domain controller. Attached Figure Description

[0039] Those skilled in the art will understand that the accompanying drawings are provided to better understand the present invention and do not constitute any limitation on the scope of the present invention. Wherein:

[0040] Figure 1 This is a schematic diagram of a wiper drive circuit according to an embodiment of the present invention;

[0041] Figure 2 This is a schematic diagram of a power drive unit and a signal transmission circuit according to an embodiment of the present invention. Detailed Implementation

[0042] To make the objectives, advantages, and features of this utility model clearer, the present utility model will be further described in detail below with reference to 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 facilitate and clarify the explanation of the objectives of the embodiments of this utility model. Furthermore, the structures shown in the drawings are often part of the actual structure. In particular, different drawings may emphasize different aspects and sometimes use different scales.

[0043] As used in this invention, the singular forms “a,” “an,” and “the” include plural objects; the term “or” is generally used to include the meaning of “and / or”; the term “a number” is generally used to include the meaning of “at least one”; and the term “at least two” is generally used to include the meaning of “two or more”. Furthermore, the terms “first,” “second,” and “third” are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined with “first,” “second,” or “third” may explicitly or implicitly include one or at least two of that feature. “One end” and “the other end,” as well as “proximal end” and “far end,” generally refer to two corresponding parts, including not only endpoints. The terms “installed,” “connected,” and “joined” should be interpreted broadly; for example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal connection of two elements or the interaction between two elements. Furthermore, as used in this invention, the phrase "one element is disposed on another element" generally only indicates that there is a connection, coupling, cooperation, or transmission relationship between the two elements. This connection, coupling, cooperation, or transmission can be direct or indirect through an intermediate element, and should not be construed as indicating or implying a spatial positional relationship between the two elements. That is, one element can be located arbitrarily inside, outside, above, below, or to one side of the other element, unless otherwise explicitly stated. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0044] See Figure 1 This utility model schematically provides a wiper drive circuit, applicable to a wiper motor M. The wiper drive circuit includes a first half-bridge 10, a second half-bridge 20, and an electromotive force cutoff unit. The upper section of the first half-bridge 10 is connected to the power supply voltage VM, the lower section of the first half-bridge 10 is grounded, and the output terminal of the first half-bridge 10 is used to connect to the low-speed end of the wiper motor M. The upper section of the second half-bridge 20 is connected to the power supply voltage VM, the lower section of the second half-bridge 20 is grounded, and the output terminal of the second half-bridge 20 is used to connect to the high-speed end of the wiper motor M. The electromotive force cutoff unit includes at least two MOSFETs (e.g., MOSFETs) connected in series between the output terminal of the first half-bridge 10 and the low-speed end of the wiper motor M. Figure 1 The example demonstrates two MOSFETs (T1 and T2) connected in series, with the parasitic diodes of the MOSFETs pointing from the output of the first half-bridge 10 to the low-speed end of the wiper motor M. For example, the MOSFET in the electromotive force cutoff unit is an NMOS transistor. Understandably, the output of the first half-bridge 10 refers to its midpoint, and the output of the second half-bridge 20 refers to its midpoint. It should be noted that the operating speed of the wiper motor M when its high-speed end is enabled is greater than its operating speed when its low-speed end is enabled. Enabling the high-speed end of the wiper motor M means connecting it to the power supply voltage VM via the second half-bridge 20; enabling the low-speed end means connecting it to the power supply voltage VM via the first half-bridge 10.

[0045] The operating mode of the wiper motor M can be changed by adjusting the operating states of the first half-bridge 10, the second half-bridge 20, and the electromotive force cutoff unit. For example, the wiper motor M can be driven to operate in braking mode, low-speed mode, or high-speed mode. Specifically, when the wiper motor M operates in braking mode, the lower segment of the first half-bridge 10 and the MOSFET of the electromotive force cutoff unit are both turned on, while the upper segment of the first half-bridge 10 and the upper and lower segments of the second half-bridge 20 are all turned off. When the wiper motor M operates in low-speed mode, the upper segment of the first half-bridge 10 and the MOSFET of the electromotive force cutoff unit are both turned on, while the lower segment of the first half-bridge 10 and the upper and lower segments of the second half-bridge 20 are all turned off. When the wiper motor M operates in high-speed mode, the upper segment of the second half-bridge 20 is turned on, while the upper and lower segments of the first half-bridge 10, the lower segment of the second half-bridge 20, and the MOSFET of the electromotive force cutoff unit are all turned off.

[0046] The wiper drive circuit described above, by connecting at least two MOSFETs in series between the output of the first half-bridge 10 and the low-speed end of the wiper motor M, can cut off the reverse induced electromotive force (EMF) generated in high-speed mode that reaches the power supply voltage VM. Furthermore, by replacing one high-voltage MOSFET with at least two low-voltage MOSFETs in series, even if the reverse induced EMF generated by the wiper motor M in high-speed mode breaks down the MOSFET near the low-speed end of the wiper relay, it cannot break down the subsequent MOSFETs, thus still effectively cutting off the reverse induced EMF. Since no current flows through the MOSFETs in the EMF cutoff unit, the power consumption is almost zero, preventing burnout due to excessive power consumption. This invention is applicable to all applications of mechanical windshield wipers. The series design of the MOSFETs saves on the size and weight of the domain controller, is noiseless, has a faster response speed, and improves the user's driving experience. Moreover, replacing one high-voltage MOSFET with at least two low-voltage MOSFETs in series reduces the overall cost of the solution and enhances the product competitiveness of the domain controller.

[0047] Continue reading Figure 1 The first half-bridge 10 includes a first power switch Q1 and a second power switch Q2. One end of the first power switch Q1 is connected to the power supply voltage VM, and the other end of the first power switch Q1 is connected to one end of the second power switch Q2 as the output terminal of the first half-bridge 10. The other end of the second power switch Q2 is grounded. Thus, the first power switch Q1 serves as the upper segment of the first half-bridge 10, and the second power switch Q2 serves as the lower segment of the first half-bridge 10. The second half-bridge 20 includes a third power switch Q3 and a fourth power switch Q4. One end of the third power switch Q3 is connected to the power supply voltage VM, and the other end of the third power switch Q3 is connected to one end of the fourth power switch Q4 as the output terminal of the second half-bridge 20. The other end of the fourth power switch Q4 is grounded. Thus, the third power switch Q3 serves as the upper segment of the second half-bridge 20, and the fourth power switch Q4 serves as the lower segment of the second half-bridge 20.

[0048] For example, the first power switch Q1, the second power switch Q2, the third power switch Q3, and the fourth power switch Q4 are all NMOS transistors, with the first terminal of each power switch being the drain and the second terminal being the source; or they are all NPN transistors, with the first terminal of each power switch being the collector and the second terminal being the emitter.

[0049] See Figure 2 The wiper drive circuit also includes a power drive unit 30, which is used to adjust the working state of the first half-bridge 10, the second half-bridge 20 and the electromotive force cutoff unit so that the wiper motor M can work in braking mode, low speed mode or high speed mode.

[0050] Preferably, the power drive unit 30 is further used to drive the wiper motor M from a low-speed mode to a low-speed freewheeling mode, and the power drive unit 30 is also used to drive the wiper motor M from a high-speed mode to a high-speed freewheeling mode. Specifically, when the wiper motor M operates in low-speed freewheeling mode, the lower segment of the first half-bridge 10 and the MOSFET of the electromotive force cutoff unit are both turned on, while the upper segment of the first half-bridge 10, the upper segment of the second half-bridge 20, and the lower segment are all turned off. When the wiper motor M operates in high-speed freewheeling mode, the lower segment of the second half-bridge 20 is turned on, while the upper and lower segments of the first half-bridge 10, the upper segment of the second half-bridge 20, and the MOSFET of the electromotive force cutoff unit are all turned off.

[0051] Thus, the internal winding of the wiper motor M is an inductive load. When the output of the first half-bridge 10 or the second half-bridge 20 is turned off (i.e., the first power switch Q1 is turned off, or the third power switch Q3 is turned off), freewheeling will occur in the winding. A large current flows through the parasitic diode of the second power switch Q2 or the fourth power switch Q4, which will cause the junction temperature of the second power switch Q2 or the fourth power switch Q4 to become too high, thereby burning out the second power switch Q2 or the fourth power switch. This solution sets a low-speed freewheeling mode and a high-speed freewheeling mode. When the low-speed mode is off, the second power switch Q2 is turned on, and the freewheeling path of the current is: ground → second power switch Q2 → electromotive force cutoff unit → low-speed winding of wiper motor M → ground. When the high-speed mode is off, the fourth power switch Q4 is turned on. The freewheeling path of the current is: ground → fourth power switch Q4 → high-speed winding of wiper motor M → ground. The introduction of low-speed freewheeling mode and high-speed freewheeling mode can prevent the junction temperature of the second power switch Q2 or the fourth power switch Q4 from being too high and burning out.

[0052] As a further implementation detail, the power drive unit 30 has a first enable pin IN1, a second enable pin IN2, a third enable pin nHIZ1, and a fourth enable pin nHIZ2; when the signal of the third enable pin nHIZ1 is a first level signal and the signal of the first enable pin IN1 is a first level signal, the power drive unit 30 drives the upper bridge segment of the first half-bridge 10 to be turned on and drives the lower bridge segment of the first half-bridge 10 to be turned off; when the signal of the third enable pin nHIZ1 is a first level signal and the signal of the first enable pin IN1 is a second level signal, the power drive unit 30 drives the upper bridge segment of the first half-bridge 10 to be turned off and drives the lower bridge segment of the first half-bridge 10 to be turned on; when the signal of the third enable pin nHIZ .... When the signal is at the first level, the power drive unit 30 drives both the upper and lower segments of the first half-bridge 10 to turn off; when the signal of the fourth enable pin nHIZ2 is at the first level and the signal of the second enable pin IN2 is at the first level, the power drive unit 30 drives the upper segment of the second half-bridge 20 to turn on and the lower segment of the second half-bridge 20 to turn off; when the signal of the fourth enable pin nHIZ2 is at the first level and the signal of the second enable pin IN2 is at the second level, the power drive unit 30 drives the upper segment of the second half-bridge 20 to turn off and the lower segment of the second half-bridge 20 to turn on; when the signal of the fourth enable pin nHIZ2 is at the second level, the power drive unit 30 drives both the upper and lower segments of the second half-bridge 20 to turn off.

[0053] Combination Figure 1 and Figure 2When the signal on the third enable pin nHIZ1 is at the first level and the signal on the first enable pin IN1 is at the first level, the signal output from pin GH1 of the power drive unit 30 drives the first power switch Q1 to turn on, and the signal output from pin GL2 drives the second power switch Q2 to turn off; when the signal on the third enable pin nHIZ1 is at the first level and the signal on the first enable pin IN1 is at the second level, the signal output from pin GH1 of the power drive unit 30 drives the first power switch Q1 to turn off, and the signal output from pin GL2 drives the second power switch Q2 to turn on; when the signal on the third enable pin nHIZ1 is at the second level, the signal output from pin GH1 drives the first power switch Q1 to turn off, and the signal output from pin GL2 drives the second power switch Q2 to turn on. When power switch Q2 is off; when the signal on the fourth enable pin nHIZ2 is at the first level and the signal on the second enable pin IN2 is at the first level, the signal output from pin GH2 drives the third power switch Q3 to turn on, and the signal output from pin GL2 drives the fourth power switch Q4 to turn off; when the signal on the fourth enable pin nHIZ2 is at the first level and the signal on the second enable pin IN2 is at the second level, the signal output from pin GH2 drives the third power switch Q3 to turn off, and the signal output from pin GL2 drives the fourth power switch Q4 to turn on; when the signal on the fourth enable pin nHIZ2 is at the second level, the signal output from pin GH2 drives the third power switch Q3 to turn off, and the signal output from pin GL2 drives the fourth power switch Q4 to turn off.

[0054] In one embodiment, the first level signal is high level and the second level signal is low level.

[0055] In one embodiment, the wiper drive circuit further includes a signal transmission circuit 40 for controlling the on / off state of the MOSFET in the electromotive force cutoff unit. The input terminal of the signal transmission circuit 40 receives the bias signal VCP output from the power drive unit 30. The output terminal of the signal transmission circuit 40 is connected to the electromotive force cutoff unit, and the drive terminal of the signal transmission circuit 40 is connected to the third enable pin nHIZ1. The bias signal VCP is used to turn on the MOSFET in the electromotive force cutoff unit. Here, the bias signal VCP can be, for example, a voltage signal output by the charge pump within the power drive unit 30. A first-level signal on the third enable pin nHIZ1 causes the signal transmission circuit 40 to form a path between its input and output terminals to transmit the bias signal VCP to the electromotive force cutoff unit. A second-level signal on the third enable pin nHIZ1 causes the signal transmission circuit 40 to form an open circuit between its input and output terminals to isolate the bias signal VCP from transmission to the electromotive force cutoff unit.

[0056] Regarding the structure of the signal transmission circuit 40, in one embodiment, the signal transmission circuit 40 includes a fifth power switch Q5, a sixth power switch Q6, a first resistor R1, a second resistor R2, a third resistor R3, and a fourth resistor R4. The first terminal of the fifth power switch Q5 serves as the input terminal of the signal transmission circuit 40, and the second terminal of the fifth power switch Q5 serves as the output terminal of the signal transmission circuit 40. The first resistor R1 is connected between the first terminal and the driving terminal of the fifth power switch Q5. The first terminal of the sixth power switch Q6 is connected to the driving terminal of the fifth power switch Q5 through the second resistor R2, and the second terminal of the sixth power switch Q6 is grounded. The fourth resistor R4 is connected between the driving terminal and the second terminal of the sixth power switch Q6. The driving terminal of the sixth power switch Q6 is connected to the third enable pin nHIZ1 through the third resistor R3. Thus, when the signal on the third enable pin nHIZ1 is at the first level, the voltage at the circuit node between the third resistor R3 and the fourth resistor R4 is pulled high, causing the sixth power switch Q6 to turn on. This, in turn, pulls low the voltage at the circuit node between the first resistor R1 and the second resistor R2, causing the fifth power switch Q5 to turn on. Consequently, the bias signal VCP is output to the electromotive force cutoff unit. Conversely, when the signal on the third enable pin nHIZ1 is at the second level, the voltage at the circuit node between the third resistor R3 and the fourth resistor R4 is pulled low to ground, causing the sixth power switch Q6 to turn off. The voltage at the circuit node between the first resistor R1 and the second resistor R2 is pulled high by the bias signal VCP, causing the fifth power switch Q5 to turn off. This isolates the bias signal VCP from being output to the electromotive force cutoff unit.

[0057] For example, the fifth power switch Q5 is an NPN transistor, and the sixth power switch Q6 is a PNP transistor. The first terminal of the fifth power switch Q5 is the collector, the second terminal of the fifth power switch Q5 is the emitter, and the driving terminal of the fifth power switch Q5 is the base; the first terminal of the sixth power switch Q6 is the emitter, the second terminal of the sixth power switch Q6 is the emitter, and the driving terminal of the sixth power switch Q6 is the base.

[0058] When the power drive unit 30 receives the limp mode signal from the vehicle domain controller, it will drive the wiper motor M to operate in low-speed mode to meet the vehicle design requirements. That is, regardless of the previous mode (brake / low speed / high speed) of the wiper motor M, the domain controller will activate the low-speed wipers after entering limp mode. In specific implementation, the power drive unit 30 is set to the first level signal by the limp mode signal output by the LIMPHOME module in the domain controller, which sets the signals of the first enable pin IN1 and the third enable pin nHIZ1 to the first level signal.

[0059] In this embodiment, the power drive unit 30 is preferably a dual-channel pre-driver chip. The main function of the dual-channel pre-driver chip is to improve memory bandwidth and data transfer speed, thereby improving the overall system performance. The dual-channel pre-driver chip is implemented by designing two independent memory controllers at the Northbridge (or MCH) chip level. These two memory controllers can perform operations in parallel and independently, with each controller responsible for one memory channel. The CPU can address and read data through these two channels respectively, thereby doubling the memory bandwidth and data access speed.

[0060] Although the present invention has been disclosed above with reference to preferred embodiments, these embodiments are not intended to limit the present invention. For any person skilled in the art, many possible variations and modifications can be made to the technical solutions of the present invention based on the disclosed technical content, or equivalent embodiments can be modified accordingly, without departing from the scope of the present invention. Therefore, any simple modifications, equivalent changes, and modifications made to the above embodiments based on the technical essence of the present invention, without departing from the content of the present invention, shall still fall within the protection scope of the present invention.

Claims

1. A wiper drive circuit, characterized in that, include: The first half-bridge has its upper section connected to the power supply voltage and its lower section grounded. The second half-bridge has its upper section connected to the power supply voltage and its lower section grounded. The output of the second half-bridge is used to connect to the high-speed end of the wiper motor. The electromotive force cutoff unit includes at least two MOS transistors connected in series between the output terminal of the first half-bridge and the low-speed terminal of the wiper motor, and the parasitic diodes of the MOS transistors are directed from the output terminal of the first half-bridge to the low-speed terminal of the wiper motor.

2. The wiper drive circuit according to claim 1, characterized in that, The first half-bridge includes a first power switch and a second power switch. One end of the first power switch is connected to the power supply voltage, and the other end of the first power switch and one end of the second power switch are connected to serve as the output terminal of the first half-bridge. The other end of the second power switch is grounded. The second half-bridge includes a third power switch and a fourth power switch. One end of the third power switch is connected to the power supply voltage, and the other end of the third power switch and one end of the fourth power switch are connected as the output terminal of the second half-bridge. The other end of the fourth power switch is grounded.

3. The wiper drive circuit according to claim 1, characterized in that, The MOS transistor in the electromotive force cutoff unit is an NMOS transistor.

4. The wiper drive circuit according to claim 1, characterized in that, The wiper drive circuit also includes a power drive unit, which is used to adjust the working state of the first half-bridge, the second half-bridge and the electromotive force cutoff unit respectively, so that the wiper motor works in braking mode, low speed mode or high speed mode. When the wiper motor is operating in braking mode, the lower segment of the first half-bridge and the MOSFET are both turned on, while the upper segment of the first half-bridge, the upper segment of the second half-bridge, and the lower segment are all turned off. When the wiper motor is operating in low-speed mode, the upper segment of the first half-bridge and the MOSFET are both turned on, while the lower segment of the first half-bridge and the upper and lower segments of the second half-bridge are all turned off. When the wiper motor is operating in high-speed mode, the upper segment of the second half-bridge is turned on, while the upper and lower segments of the first half-bridge, the lower segment of the second half-bridge, and the MOSFET are all turned off.

5. The wiper drive circuit according to claim 4, characterized in that, The power drive unit is also used to drive the wiper motor from the low speed mode to the low speed continuous mode. When the wiper motor operates in low-speed freewheeling mode, the lower segment of the first half-bridge and the MOSFET are both turned on, while the upper segment of the first half-bridge and the upper and lower segments of the second half-bridge are all turned off.

6. The wiper drive circuit according to claim 4, characterized in that, The power drive unit is also used to drive the wiper motor from the high-speed mode to the high-speed continuous flow mode. When the wiper motor operates in high-speed freewheeling mode, the lower segment of the second half-bridge is turned on, while the upper and lower segments of the first half-bridge, the upper segment of the second half-bridge, and the MOSFET are all turned off.

7. The wiper drive circuit according to claim 4, characterized in that, The power drive unit has a first enable pin, a second enable pin, a third enable pin, and a fourth enable pin; When the signal of the third enable pin is a first level signal and the signal of the first enable pin is a first level signal, the power drive unit drives the upper bridge segment of the first half-bridge to be turned on and drives the lower bridge segment of the first half-bridge to be turned off. When the signal of the third enable pin is a first level signal and the signal of the first enable pin is a second level signal, the power drive unit drives the upper bridge segment of the first half-bridge to turn off and drives the lower bridge segment of the first half-bridge to turn on. When the signal of the third enable pin is a second level signal, the power drive unit drives both the upper and lower bridge segments of the first half-bridge to turn off. When the signal of the fourth enable pin is a first level signal and the signal of the second enable pin is a first level signal, the power drive unit drives the upper bridge segment of the second half-bridge to be turned on and drives the lower bridge segment of the second half-bridge to be turned off. When the signal of the fourth enable pin is a first level signal and the signal of the second enable pin is a second level signal, the power drive unit drives the upper bridge segment of the second half-bridge to turn off and drives the lower bridge segment of the second half-bridge to turn on. When the signal of the fourth enable pin is a second level signal, the power drive unit drives both the upper and lower segments of the second half-bridge to turn off.

8. The wiper drive circuit according to claim 7, characterized in that, The wiper drive circuit also includes a signal transmission circuit. The input terminal of the signal transmission circuit acquires the bias signal output by the power drive unit. The output terminal of the signal transmission circuit is connected to the electromotive force cutoff unit. The drive terminal of the signal transmission circuit is connected to the third enable pin. The bias signal is used to turn on the MOS transistor of the electromotive force cutoff unit. Specifically, the first level signal of the third enable pin drives the signal transmission circuit to form a path between its input and output terminals to transmit the bias signal to the electromotive force cutoff unit, and the second level signal of the third enable pin drives the signal transmission circuit to form an open circuit between its input and output terminals to isolate the bias signal from being transmitted to the electromotive force cutoff unit.

9. The wiper drive circuit according to claim 8, characterized in that, The signal transmission circuit includes a fifth power switch, a sixth power switch, a first resistor, a second resistor, a third resistor, and a fourth resistor. The first terminal of the fifth power switch serves as the input terminal of the signal transmission circuit, and the second terminal of the fifth power switch serves as the output terminal of the signal transmission circuit. The first resistor is connected between the first terminal and the driving terminal of the fifth power switch. The first terminal of the sixth power switch is connected to the driving terminal of the fifth power switch through the second resistor. The second terminal of the sixth power switch is grounded. The fourth resistor is connected between the driving terminal and the second terminal of the sixth power switch. The driving terminal of the sixth power switch is connected to the third enable pin through the third resistor.

10. The wiper drive circuit according to claim 8, characterized in that, When the power drive unit receives the limp mode signal from the vehicle domain controller, it will drive the wiper motor to operate in low speed mode.

11. The wiper drive circuit according to claim 10, characterized in that, The power drive unit sets the signals of both the first enable pin and the third enable pin to the first level signal by the limp mode signal.

12. The wiper drive circuit according to claim 4, characterized in that, The power drive unit includes a dual-channel pre-drive chip.

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