Braking system and new energy automobile

Abstract

The embodiment of the invention provides a braking system and a new energy automobile, the braking system comprises a motor bus and a motor load connected with the motor bus, the motor load is set as a braking motor of a mobile device, the motor bus is provided with a power supply, a back-to-back MOS and a motor drive axle in series, and the motor bus is provided with a capacitance circuit in parallel; the back-to-back MOS is connected to the control module; the control module adopts a variable PWM signal to control the back-to-back MOS; when the motor bus is powered, the duty ratio of the variable PWM signal is equal to the preset duty ratio plus the motor bus voltage value / the power supply voltage value. Therefore, when the voltage value of the motor bus is low, a low duty ratio is kept, on one hand, the problem of power supply voltage loss caused by overlarge charging power is avoided, and on the other hand, the ripple problem caused by overlarge voltage change of the motor bus can be avoided. And moreover, the charging power of the power supply can be quickly improved under the stable condition, so that the motor bus can immediately respond after being electrified, and the safety of the braking system is improved.

Description

Technical Field

[0001] The present application relates to the technical field of brake systems, and in particular to a brake system and a new energy vehicle. Background Art

[0002] As a device that converts electrical energy into mechanical energy, electric motors have a wide range of uses. For example, in new energy vehicles, electric motors can be used as drive motors or brake motors in braking systems.

[0003] When a new energy vehicle is started, it is necessary to ensure that the braking system can be successfully powered on immediately so that the braking effect can be immediately exerted to ensure the safety of the vehicle. In the prior art, the brake motor of the braking system is usually connected to the motor bus and powered and driven by the motor bus.

[0004] In a common starting method, the battery KL30 in the vehicle's ECU (Electronic Control Unit) first supplies power to the motor bus. At the same time, since a large capacitor is connected in parallel to the motor bus, the battery KL30 first directly charges the large capacitor at the motor bus end at the moment the motor bus is powered, thereby pulling down the voltage of the battery KL30. After the voltage is pulled down, other components on the ECU (mainly the solenoid valve driver chip, EPB motor driver chip, and wheel speed driver chip, etc.) will falsely report an undervoltage fault, affecting the normal operation of the ECU. Furthermore, fast charging will also cause large ripples in the brake system, thereby affecting the stability of the motor bus voltage and increasing the difficulty of managing the motor bus voltage.

[0005] In another way, the ECU can avoid false alarm of undervoltage fault by reducing the power supplied by the battery KL30 to the motor bus. However, this way will extend the charging time when the power supply of the battery KL30 is set too low, and the motor bus voltage will take a long time to reach a steady state, thus affecting the time for the ECU to generate braking force after ignition. When the power supply of the battery KL30 is set too high, it is easy to have large ripples and difficult management problems.

[0006] At the same time, in one case, during the process of brake motor driving, the motor driving force, hydraulic reaction force, and transmission system acceleration meet the force balance. When a brake motor drive circuit failure occurs, resulting in the failure of the brake motor drive, this failure causes the brake motor to have no output torque. At this time, the hydraulic pressure of the brake system will push the brake motor to rotate in the opposite direction, and the brake motor can be used as both a motor and a generator. At this time, the brake motor phase line coil winding will generate electricity, and the brake motor will rotate faster and faster under the action of the reverse thrust until the brake motor moves and hits the end of the ECU mechanical assembly. In this process, the voltage of the brake motor as a generator will also cause damage to the electronic components in the brake system.

[0007] In order to prevent the voltage generated by the brake motor from harming the electronic components of the motor drive circuit, and to prevent the motor from hitting the bottom at high speed when moving backwards and damaging or even breaking the mechanical assembly components, the software needs to discharge and decelerate the motor to ensure that the system runs safely, smoothly and reliably and to avoid false fault alarms. Therefore, the motor bus discharge voltage needs to be managed.

[0008] In another scenario, in the case of some ECUs that are powered on and off quickly, there is residual voltage on the motor bus. This residual voltage comes from the electricity stored in the bus terminal capacitor itself that was not discharged in time during the previous ignition cycle or the back electromotive force of the motor's reverse rotation. It will be transmitted to the brake motor terminal voltage, which is used to perform initialization diagnosis on the motor drive bridge circuit and estimate the motor rotor position during normal operation. This can also lead to false alarms in the initialization diagnosis and large deviations in the position estimation during normal operation.

[0009] Therefore, in the prior art, there is an urgent need for a method for efficiently and safely managing the motor bus voltage to solve the problems caused by charging, discharging, and rapid power-on and power-off of the motor bus. Summary of the invention

[0010] The purpose of the present application is to solve the problem of slow response and poor stability caused by the motor bus in the prior art when charging, discharging, fast power on and off. Therefore, the present application provides a braking system, including a motor bus and a motor load connected to the motor bus, and a back-to-back MOS is arranged between the power supply and the motor bus, so that the duty cycle of the variable PWM signal that turns on the back-to-back MOS can be controlled to control whether the power supply to the motor bus and the charging efficiency of the power supply; and when the motor bus is powered, the duty cycle of the variable PWM signal = preset duty cycle + motor bus voltage value / power supply voltage value; so that when the motor bus voltage value is low, a low duty cycle is maintained, on the one hand, the problem of power supply loss caused by excessive charging power is avoided, and on the other hand, the ripple problem caused by excessive motor bus voltage change can be avoided. Further, when the motor bus voltage value rises, the charging power of the power supply can be quickly increased, so that the power supply can quickly make the motor bus reach the set value, thereby ensuring that the motor bus can respond immediately after power-on, and improving the safety of the braking system.

[0011] The embodiment of the present application provides a braking system, comprising: a motor bus and a motor load connected to the motor bus, wherein the motor load is configured as a braking motor of a mobile device; The motor bus is provided with a power supply, a back-to-back MOS and a motor drive bridge in series, and the motor bus is provided with a capacitor circuit in parallel; The motor drive bridge includes a motor load and a control circuit connected to the motor load; The back-to-back MOS is connected to a control module; and the control module uses a variable PWM signal to control the back-to-back MOS; The control module control process includes: The control module obtains the power supply voltage value and the motor bus voltage value, and when supplying power to the motor bus, calculates the duty cycle of the variable PWM signal to turn on the back-to-back MOS; The duty cycle of the variable PWM signal=preset duty cycle+motor bus voltage value / power supply voltage value, and the maximum duty cycle is 100%.

[0012] By adopting the above technical solution, when the power supply supplies power to the motor bus, the duty cycle of the variable PWM signal in the back-to-back MOS is the preset duty cycle + motor bus voltage value / power supply voltage value; thus, when the motor bus voltage value is low, a low duty cycle is maintained, which, on the one hand, avoids the problem of power supply voltage loss caused by excessive charging power, and on the other hand, avoids the ripple problem caused by excessive changes in the motor bus voltage. Furthermore, when the motor bus voltage value rises, the charging power of the power supply can be quickly increased, so that the power supply can quickly make the motor bus reach the set value, thereby ensuring that the motor bus can respond immediately after power-on, improving the safety of the braking system.

[0013] In some embodiments, the motor drive bridge further includes a discharge circuit, which is connected in parallel with the control circuit and includes a discharge load and a discharge MOS switch connected in series; The discharge MOS switch is connected to the control module; When the motor bus is powered on or off, the discharge load can discharge the motor bus and / or the motor load by turning on the discharge MOS switch of the discharge circuit.

[0014] By adopting the above technical solution, the discharge circuit can release the residual voltage of the motor bus before the motor bus is powered on. At the same time, it can also release the back electromotive force formed by the reversal of the motor load when the motor bus is suddenly powered off, thereby ensuring the safety of the braking system.

[0015] In some embodiments, when the motor bus is powered on, the back-to-back MOS is turned off and the discharge MOS switch is turned on at the same time, so that the residual electric energy in the motor bus and the capacitor circuit is released through the discharge load, and / or the electric energy generated during the electrical reversal under the motor load is released through the discharge load.

[0016] The above technical solution can release the electric energy generated during the reversal of the motor load in time, avoiding damage to other electronic components in the braking system caused by the additional power supply. At the same time, it can avoid the risk of false alarm faults caused by residual electric energy or back electromotive force in the motor busbar on the motor drive circuit detection.

[0017] In some embodiments, when the motor bus is powered on, it is first determined whether the voltage values ​​of the motor bus and the control circuit exceed a first threshold; When the voltage value of the motor bus and / or the control circuit exceeds a first threshold value, turning on the discharge MOS, so that the motor bus and / or the control circuit are discharged through the discharge load, until the voltage values ​​of the motor bus and the control circuit are both lower than the first threshold value; Then, the back-to-back MOS is controlled to supply power to the motor bus, and after the power supply is stable, the control module performs an initialization self-check; When the voltage values ​​of the motor bus and the control circuit are both lower than a first threshold, the control module controls the back-to-back MOS to supply power to the motor bus, and completes the initialization self-check after the power supply is stable.

[0018] In some embodiments, a motor pre-driver chip is provided in the control circuit; the first threshold is a reset voltage value of the motor pre-driver chip in the motor drive bridge, and the range of the first threshold is set to 3.5~4.5V.

[0019] With the above technical solution, when the bus voltage (i.e., the motor pre-driver chip power supply voltage) is lower than the first threshold, the motor pre-driver chip will be reset, and the fault information in the register of the motor pre-driver chip can be cleared by resetting, thereby avoiding the motor pre-driver chip from bringing the previous fault information into the current state. At the same time, the voltage value of the first threshold will not be too small, so as to avoid the discharge circuit taking too long in the later stage of discharge, affecting the response time of the brake system.

[0020] In some embodiments, the motor load is set as a three-phase brake motor, and the control circuit includes a motor pre-driver chip and a power drive bridge circuit connected in series, and the power drive bridge circuit is connected to the motor load through three phase lines, and each phase line is connected to two drive bridge MOS; the frequency of the variable PWM signal is the same as the chopping frequency of the motor load; The control module is connected to the motor pre-drive chip and controls the motor load; Furthermore, when the motor bus is powered on, the control module controls the two phase lines in the motor load to be short-circuited, and suppresses the reverse rotation of the motor load.

[0021] In some embodiments, the preset duty cycle of the variable PWM signal is determined according to the G-pole resistance, capacitance and internal capacitance parameters of the back-to-back MOS and the temperature, and is set to 2.5%; When the voltage difference between the motor bus voltage value and the power supply voltage value is equal to the voltage drop when the back-to-back MOS is turned on, the duty cycle of the variable PWM signal is set to 100%.

[0022] By adopting the above technical solution, when the preset duty cycle is set to 2.5%, the charging time of the motor bus can be shortened while ensuring that the ripple of the motor bus is small.

[0023] In some embodiments, the power supply is disposed in the control module and supplies power to the control module; The capacitive circuit includes a plurality of capacitors connected in parallel; The discharge load includes a plurality of resistors connected in parallel.

[0024] An embodiment of the present application also provides a new energy vehicle, comprising a braking system as described in any of the above embodiments.

[0025] By adopting the above technical solution, when the new energy vehicle is started, during the process of the power supply of the braking system to the motor bus, the duty cycle of the variable PWM signal in the back-to-back MOS is the preset duty cycle + motor bus voltage value / power supply voltage value; thus, when the motor bus voltage value is low, a low duty cycle is maintained, which, on the one hand, avoids the problem of power supply voltage loss caused by excessive charging power, and on the other hand, avoids the ripple problem caused by excessive changes in the motor bus voltage. Furthermore, when the motor bus voltage value rises, the charging power of the power supply can be quickly increased, so that the power supply can quickly make the motor bus reach the set value, thereby ensuring that the motor bus can respond immediately after power-on, improving the safety of the braking system. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 A simplified circuit diagram of a braking system according to an embodiment of the present application; Figure 2 A simplified circuit diagram of a motor drive bridge of a brake system according to an embodiment of the present application; Figure 3 A circuit diagram of a braking system in one embodiment of the present application; Figure 4 Schematic diagram of the charging effect of the motor busbar of an embodiment of the present application.

[0027] Description of reference numerals: 11. Power supply; 12. Back-to-back MOS; 13. Motor bus; 14. Capacitor circuit; 2. Motor drive axle; 21. Motor load; 22. Control circuit; 23. Motor pre-driver chip; 3. Control module; 4. Discharge circuit. DETAILED DESCRIPTION

[0028] The following specific embodiments illustrate the implementation of the present application, and those skilled in the art can easily understand other advantages and effects of the present application from the contents disclosed in this specification. Although the description of the present application will be introduced in conjunction with some embodiments, this does not mean that the features of this application are limited to the implementation. On the contrary, the purpose of introducing the application in conjunction with the implementation is to cover other options or modifications that may be extended based on the claims of the present application. In order to provide a deep understanding of the present application, the following description will include many specific details. The present application can also be implemented without using these details. In addition, in order to avoid confusion or blurring the focus of the present application, some specific details will be omitted in the description. It should be noted that the embodiments in the present application and the features in the embodiments can be combined with each other without conflict.

[0029] It should be noted that in this specification, similar reference numerals and letters denote similar items in the following drawings, and therefore, once an item is defined in one drawing, it does not need to be further defined and explained in the subsequent drawings.

[0030] In the description of the present application, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc., indicating the orientation or positional relationship, are based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present application and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present application. In addition, the terms "first" and "second" are used for descriptive purposes only and cannot be understood as indicating or implying relative importance.

[0031] In the description of this application, it should be noted that, unless otherwise clearly specified and limited, 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 connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0032] In the description of the present application, it should be understood that in the present application, "electrical connection" can be understood as physical contact and electrical conduction between components; it can also be understood as a form in which different components in the circuit structure are connected through physical lines such as printed circuit board (PCB) copper foil or wires that can transmit electrical signals. "Coupled by..." can be understood as electrical conduction through air by indirect coupling. Indirect coupling can be understood as contactless coupling, in which it can be understood by those skilled in the art that the coupling phenomenon refers to the phenomenon that there is close cooperation and mutual influence between the input and output of two or more circuit elements or electrical networks, and energy is transmitted from one side to the other through interaction. In order to make the purpose, technical solution and advantages of the present application clearer, the implementation method of the present application will be further described in detail below in conjunction with the accompanying drawings.

[0033] See also Figure 1 , Figure 1 This is a simplified circuit diagram of the braking system of an embodiment of the present application. Figure 2 A simplified circuit diagram of a motor drive bridge of a brake system according to an embodiment of the present application.

[0034] like Figure 1 and Figure 2 As shown, an embodiment of the present application provides a braking system, comprising: A power supply 11, a back-to-back MOS 12, a motor bus 13 and a motor drive bridge 2 are arranged in series, and the motor bus 13 is provided with a capacitor circuit 14 in parallel; The motor drive bridge 2 includes a motor load 21 and a control circuit 22 connected to the motor load 21; The back-to-back MOS 12 is connected to the control module 3; and the control module 3 uses a variable PWM signal to control the back-to-back MOS 12; The control process of control module 3 includes: The acquisition control module 3 acquires the voltage value of the power supply 11 and the voltage value of the motor bus 13, and when supplying power to the motor bus 13, calculates the duty cycle of the variable PWM signal to turn on the back-to-back MOS 12; The duty cycle of the variable PWM signal = preset duty cycle + motor bus 13 voltage value / power supply 11 voltage value, and the maximum duty cycle is 100%.

[0035] It should be noted that the control process of the back-to-back MOS 12 by the variable PWM signal can be that when the variable PWM signal outputs a high level, the back-to-back MOS 12 is turned on, and the power supply 11 supplies power to the motor bus 13; when the variable PWM signal outputs a low level, the back-to-back MOS 12 is disconnected, and the power supply 11 stops supplying power to the motor bus 13; thereby, the power supply efficiency of the power supply 11 can be controlled by controlling the duty cycle of the variable PWM signal.

[0036] Therefore, when the power supply 11 supplies power to the motor bus 13, the duty cycle of the variable PWM signal in the back-to-back MOS 12 is the preset duty cycle + the voltage value of the motor bus 13 / the voltage value of the power supply 11; thus, when the voltage value of the motor bus 13 is low, a low duty cycle is maintained, which, on the one hand, avoids the problem of power supply 11 losing voltage due to excessive charging power, and on the other hand, avoids the ripple problem caused by excessive voltage changes of the motor bus 13. Furthermore, when the voltage value of the motor bus 13 rises, the charging power of the power supply 11 can be quickly increased, so that the power supply 11 can quickly make the motor bus 13 reach the set value, thereby ensuring that the motor bus 13 can respond immediately after power-on, thereby improving the safety of the braking system.

[0037] In one embodiment, the preset duty cycle of the variable PWM signal is determined according to the G-pole resistance, capacitance and internal capacitance parameters of the back-to-back MOS 12 and the temperature, and is set to 2.5%; When the voltage difference between the motor bus 13 voltage value and the power supply 11 voltage value is equal to the voltage drop when the back-to-back MOS 12 is turned on, the duty cycle of the variable PWM signal is set to 100%. And maintain this state until a power-off request occurs. In this way, the motor bus 13 voltage can be charged flexibly and smoothly.

[0038] In other alternative embodiments, the preset duty cycle can also be determined by direct debugging, with the aim of obtaining an optimal preset duty cycle so that when the charging time of the motor bus 13 is short, the ripple generated by the motor bus 13 is small.

[0039] In one embodiment, the power supply 11 is disposed in the control module 3 and supplies power to the control module 3 , the capacitor circuit 14 includes a plurality of capacitors connected in parallel, and the discharge load includes a plurality of resistors connected in parallel.

[0040] In other alternative embodiments, the capacitor circuit 14 may be other forms of energy storage circuits; the discharge load may be a simple electric heating wire to quickly release electrical energy; the discharge load may also be functional electronic components such as a timing unit, a signal transmission unit, and a light-emitting unit, so that when releasing electrical energy, the discharge time can be recorded, signal transmission can be performed, or light warnings can be emitted.

[0041] See also Figure 3 and Figure 4 , Figure 3 This is a circuit diagram of a braking system in one embodiment of the present application. Figure 4 The figure is a schematic diagram of the charging effect of the motor busbar in the embodiment of the present application. Figure 1 and Figure 2 It is understood that, in one embodiment, the braking system can be applied to mobile devices such as new energy vehicles, electric vehicles, battery vehicles, etc. A new energy vehicle applying the braking system is described in detail below by taking an example.

[0042] It should be noted that the braking system of new energy vehicles usually includes a transmission-connected brake motor, a hydraulic component, a brake pad and a brake disc, wherein the brake disc is fixed to the drive shaft of the vehicle wheel, and the brake motor drives the hydraulic component and drives the brake pad to generate braking force through friction with the brake disc.

[0043] Furthermore, when the motor drive axle 2 of the brake system is started, it will collect information of each start-up and perform initialization operations to ensure the stability and safety of each start-up of the brake system.

[0044] In one embodiment, the control module 3 may be configured as an ECU (Electronic Control Unit) of the vehicle, and the power source 11 may be a battery KL30 in the ECU of the vehicle.

[0045] In one embodiment, when the motor bus 13 is powered on, it is first determined whether the voltage values ​​of the motor bus 13 and the control circuit 22 exceed a first threshold; When the voltage value of the motor bus 13 and / or the control circuit 22 exceeds the first threshold value, the discharge MOS is turned on, so that the motor bus 13 and / or the control circuit 22 are discharged through the discharge load until the voltage values ​​of the motor bus 13 and the control circuit 22 are both lower than the first threshold value; Then, after the control module 3 completes the initialization self-check, it controls the back-to-back MOS 12 to supply power to the motor bus 13; When the voltage values ​​of the motor bus 13 and the control circuit 22 are both lower than the first threshold, the control module 3 directly completes the initialization self-check and then controls the back-to-back MOS 12 to supply power to the motor bus 13 .

[0046] In one embodiment, the first threshold is the lowest voltage value when the control circuit 22 in the motor drive bridge 2 is running. In other alternative embodiments, the first threshold may also be less than or greater than the lowest voltage value according to actual conditions.

[0047] The first threshold is set because: if the voltage does not drop below this value, the control circuit 22 can still work normally under the power supply of the motor bus 13, so that the control circuit 22 will bring the fault information of the previous ignition cycle into the current ignition cycle. In addition, in order to shorten the discharge time, it is not necessary to drop to 0V, because the discharge speed is slower in the second half of the discharge, so there is no need to spend time to drop to 0V.

[0048] In one embodiment, a motor pre-driver chip 23 is provided in the control circuit 22; the first threshold is a reset voltage value of the motor pre-driver chip 23 in the motor drive bridge 2, and the range of the first threshold is set to 3.5-4.5 V. In other alternative embodiments, the first threshold may also be less than or greater than the minimum voltage value according to actual conditions.

[0049] When the motor bus 13 voltage (i.e., the motor pre-driver chip 23 power supply voltage) is lower than the first threshold, the motor pre-driver chip 23 will be reset, and the fault information in the register of the motor pre-driver chip 23 can be cleared by resetting, thereby preventing the motor pre-driver chip 23 from bringing the previous fault information into the current state. At the same time, the voltage value of the first threshold will not be too small, so as to avoid the discharge circuit 4 taking too long in the later stage of discharge, thereby affecting the response time of the brake system.

[0050] In one embodiment, the motor load 21 is set as a three-phase brake motor, and the control circuit 22 includes a motor pre-driver chip 23 and a power drive bridge circuit connected in series, and the power drive bridge circuit is connected to the motor load 21 through three phase lines, and each phase line is connected to two drive bridge MOS; the frequency of the variable PWM signal is the same as the chopping frequency of the motor load 21; The control module 3 is connected to the motor pre-drive chip 23 and controls the motor load 21; Furthermore, when the motor bus 13 is powered off, the control module 3 controls the two phase lines in the motor load 21 to be short-circuited, and prevents the motor load 21 from reversing.

[0051] It should be noted that the minimum voltage value of the control circuit 22 during operation is mainly determined by the operating voltage of the motor pre-drive chip 23 .

[0052] In one embodiment, the motor drive bridge 2 further includes a discharge circuit 4, which is connected in parallel with the control circuit 22 and includes a discharge load and a discharge MOS switch connected in series; The discharge MOS switch is connected to the control module 3; When the motor bus 13 is powered on or off, the discharge MOS switch of the discharge circuit 4 can be turned on to allow the discharge load to discharge the motor bus 13 and / or the motor load 21. The discharge circuit 4 can release the residual voltage of the motor bus 13 before the motor bus 13 is powered on, and at the same time, when the motor bus 13 is suddenly powered off, the back electromotive force formed by the reverse rotation of the motor load 21 can be released, thereby avoiding the false alarm of the fault during the initialization diagnosis of the motor drive bridge 2 due to the existence of the back electromotive force, and also avoiding the damage to the motor components due to excessive back electromotive force, thereby ensuring the safety of the braking system.

[0053] It should be noted that when the motor bus 13 suddenly loses power (for example, the drive circuit fails, causing the brake motor to lose driving force), at this time, the original driving force of the brake motor rotor and the hydraulic component achieve force balance. When the brake motor suddenly loses power and loses driving force, the thrust of the hydraulic component will cause the rotor of the brake motor to reverse, thereby causing the brake motor to be converted from an electric motor to an engine, thereby forming a power supply 11 in the brake system. In addition, the rotor is only subject to small magnetic field resistance and friction resistance during the reversal process, while the reverse thrust of the hydraulic component is extremely large, resulting in the rotor reversal speed becoming faster and faster, and the power generation and voltage increase rapidly, which can easily cause safety hazards.

[0054] Therefore, in one embodiment, when the motor bus 13 is powered off, the back-to-back MOS 12 is turned off and the discharge MOS switch is turned on at the same time, so that the residual electric energy in the motor bus 13 and the capacitor circuit 14 is released through the discharge load, and / or the electric energy generated during the power-on reversal process of the motor load 21 is released through the discharge load.

[0055] Thus, the electric energy generated during the reversal of the motor load 21 can be released in time, and the damage to other electronic components in the brake system caused by the additional power supply 11 can be avoided. At the same time, the residual electric energy of the motor bus 13 can be prevented from affecting the circuit detection.

[0056] Obviously, those skilled in the art can make various changes and modifications to the present application without departing from the spirit and scope of the present application. Thus, if these modifications and modifications of the present application fall within the scope of the claims of the present application and their equivalents, the present application is also intended to include these modifications and modifications.

Claims

1. A braking system, characterized in that: include: A motor bus and a motor load connected to the motor bus, wherein the motor load is configured as a brake motor of a mobile device; The motor bus is provided with a power supply, a back-to-back MOS and a motor drive bridge in series, and the motor bus is provided with a capacitor circuit in parallel; The motor drive bridge includes a motor load and a control circuit connected to the motor load; The back-to-back MOS is connected to a control module; and the control module uses a variable PWM signal to control the back-to-back MOS; The control module control process includes: Obtaining the control module power supply voltage value and the motor bus voltage value, and when supplying power to the motor bus, calculating the duty cycle of the variable PWM signal to turn on the back-to-back MOS; The duty cycle of the variable PWM signal=preset duty cycle+motor bus voltage value / power supply voltage value, and the maximum duty cycle is 100%.

2. The braking system according to claim 1, characterized in that: The motor drive bridge further comprises a discharge circuit, which is connected in parallel with the control circuit and comprises a discharge load and a discharge MOS switch connected in series; The discharge MOS switch is connected to the control module; When the motor bus is powered on or off, the discharge load can discharge the motor bus and / or the motor load by turning on the discharge MOS switch of the discharge circuit.

3. The braking system according to claim 2, characterized in that: When the motor bus is powered on, the back-to-back MOS is turned off and the discharge MOS switch is turned on at the same time, so that the residual electric energy in the motor bus and the capacitor circuit is released through the discharge load, and / or the electric energy generated during the electrical reversal under the motor load is released through the discharge load.

4. The braking system according to claim 2, characterized in that: When the motor bus is powered on, first determine whether the voltage values ​​of the motor bus and the control circuit exceed a first threshold; When the voltage value of the motor bus and / or the control circuit exceeds a first threshold value, turning on the discharge MOS, so that the motor bus and / or the control circuit are discharged through the discharge load, until the voltage values ​​of the motor bus and the control circuit are both lower than the first threshold value; Then, the back-to-back MOS is controlled to supply power to the motor bus, and after the power supply is stable, the control module performs an initialization self-check; When the voltage values ​​of the motor bus and the control circuit are both lower than a first threshold, the control module controls the back-to-back MOS to supply power to the motor bus, and completes the initialization self-check after the power supply is stable.

5. The braking system according to claim 4, characterized in that: A motor pre-driver chip is provided in the control circuit; the first threshold is a reset voltage value of the motor pre-driver chip in the motor drive bridge, and the range of the first threshold is set to 3.5~4.5V.

6. The braking system according to claim 2, characterized in that: The motor load is set as a three-phase brake motor, and the control circuit includes a motor pre-drive chip and a power drive bridge circuit connected in series, and the power drive bridge circuit is connected to the motor load through three phase lines, and each phase line is connected to two drive bridge MOS; the frequency of the variable PWM signal is the same as the chopping frequency of the motor load; The control module is connected to the motor pre-drive chip and controls the motor load; Furthermore, when the motor bus is powered on, the control module controls the two phase lines in the motor load to be short-circuited, and suppresses the reverse rotation of the motor load.

7. The braking system as claimed in claim 1, characterized in that The preset duty cycle of the variable PWM signal is determined according to the G-pole resistance, capacitance and internal capacitance parameters of the back-to-back MOS and the temperature, and is set to 2.5%; And when the voltage difference between the motor bus voltage value and the power supply voltage value is equal to the voltage drop when the back-to-back MOS is turned on, the duty cycle of the variable PWM signal is set to 100%.

8. The brake system according to any one of claims 1 to 7, characterized in that: The power supply is arranged in the control module and supplies power to the control module; The capacitive circuit includes a plurality of capacitors connected in parallel; The discharge load includes a plurality of resistors connected in parallel.

9. A new energy vehicle, characterized in that: Comprising a braking system as claimed in any one of claims 1 to 8.

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