A brake system and motor drive system

Abstract

The application relates to a brake system and a motor driving system, and relates to the technical field of motor control. The brake system comprises an internal resistance branch and an external resistance switching circuit. The first end of the internal resistance branch is connected with a positive end of a direct-current bus, and the second end of the internal resistance branch is connected with a negative end of the direct-current bus. The first end of the external resistance switching circuit is connected with a first brake output end, and the second end of the external resistance switching circuit is connected with the positive end of the direct-current bus. The first end of an internal resistance of the internal resistance branch is connected with the first end of the internal resistance branch, the second end of the internal resistance is connected with the first end of a first switching module of the internal circuit branch, the second end of the first switching module is connected with the second end of the internal resistance branch, the first end of a second switching module of the external resistance switching circuit is connected with the first end of the external resistance switching circuit, and the second end of the second switching module is connected with the second end of the external resistance switching circuit. The first switching module can be turned on by a first conduction signal, and the second switching module can be turned on by a second conduction signal.

Description

Technical Field

[0001] This application relates to the field of motor control technology, specifically to a braking system and a motor drive system. Background Technology

[0002] In stepper motors and low-voltage servo control systems, when a motor brakes, decelerates, or reverses rapidly, the rotor continues to rotate due to inertia. The motor windings cut magnetic lines of force, generating a back electromotive force (EMF), or reverse voltage, thus putting the motor into a generating state. At this time, mechanical energy is converted into electrical energy and fed back to the drive circuit. Specifically, this manifests as a back EMF generated inside the motor driver, forming a pump-up voltage. The greater the mechanical inertia of the load or the motor rotor, the more kinetic energy is generated during braking, and the higher the back EMF, further exacerbating the pump-up voltage.

[0003] Ramp voltage can cause various problems for motor drivers. If the ramp voltage exceeds the driver's withstand voltage, it will trigger the protection mechanism and cause the machine to shut down. If the ramp voltage is too high, it may even damage power devices such as MOSFETs or filter capacitors. At the same time, excessive voltage fluctuations can also affect the control accuracy of the system, leading to missed steps or loss of control. Therefore, suppressing or eliminating ramp voltage is crucial for stepper and low-voltage servo control systems.

[0004] Currently, there are two common methods to suppress or eliminate pump-up voltage: regenerative braking and regenerative braking. Regenerative braking mainly uses energy-consuming devices such as high-power resistors (braking resistors) to convert excess electrical energy into heat energy for dissipation. Regenerative braking, on the other hand, inverts energy back to the grid. Each method has its advantages and disadvantages. Regenerative braking is simple and low-cost but has low energy utilization, while regenerative braking is more complex and expensive but has high energy utilization. From a practical and economical perspective, regenerative braking is more common in stepper and low-voltage servo control systems. Furthermore, due to the miniaturization requirements of stepper and low-voltage servo drivers, especially low-voltage servo drivers, the regenerative braking function circuit has been separated into a separate braking module.

[0005] The key to regenerative braking in braking modules lies in the selection of the braking resistor specifications. The size of the braking resistor directly affects the braking torque of the system, and the power of the braking resistor directly affects the system's regenerative energy dissipation capability. Therefore, control systems with different power ratings require different braking resistor specifications. Currently, there are two methods for connecting the braking resistor in braking module products on the market: such as... Figure 1 As shown, Option 1 uses only one braking resistor, whereby the manufacturer determines the resistor based on the operating conditions and connects it externally to the braking module. For example... Figure 2 As shown, R1 is a built-in resistor, R2 is an external resistor, and DC+ and DC- of the driver are the positive and negative terminals of the driver's DC bus, respectively.

[0006] Of the two solutions above, Solution 1 allows for the free replacement of the braking resistor to meet different working conditions, but it is complex and cannot be used immediately upon module connection. Moreover, it has too many external wiring terminals, which are easy to connect incorrectly, and the module is too large to be used in control systems with limited installation space. Solution 2 achieves module-to-use by building in a braking resistor, and also provides an external braking resistor interface to meet the working conditions that the built-in braking resistor cannot meet. However, the method of switching between internal and external braking resistors by using external connection wires is too cumbersome and complex, and it is easy to connect the wrong wires in actual use, which may cause accidents. Utility Model Content

[0007] This application provides a braking system that is easy to switch between internal and external resistors and applicable to more working conditions, as well as a motor drive system with the braking system.

[0008] According to one aspect of this application, one embodiment provides a braking system, comprising: The braking unit includes a built-in resistor branch and an external resistor switching circuit. The first end of the built-in resistor branch is connected to the positive terminal of the DC bus of the braking system, and the second end of the built-in resistor branch is connected to the negative terminal of the DC bus of the braking system. The first end of the external resistor switching circuit is connected to the first braking output terminal of the braking system, and the second end of the external resistor switching circuit is connected to the positive terminal of the DC bus of the braking system. The built-in resistor branch includes a built-in resistor and a first switching module. The first end of the built-in resistor is connected to the first end of the built-in resistor branch, the second end of the built-in resistor is connected to the first end of the first switching module, and the second end of the first switching module is connected to the second end of the built-in resistor branch. The external resistor switching circuit includes a second switching module, the first end of the second switching module is connected to the first end of the external resistor switching circuit, and the second end of the second switching module is connected to the second end of the external resistor switching circuit. The first switching module can be turned on by a first conducting signal, so that the braking system is connected to the built-in resistor; the second switching module can be turned on by a second conducting signal, so that the braking system is connected to the external resistor connected to the external resistor switching circuit.

[0009] In one embodiment, the first brake output terminal of the braking system is used to connect to the first terminal of an external resistor, and the second brake output terminal of the braking system is used to connect to the second terminal of an external resistor.

[0010] In one embodiment, the first switching module includes a first switching transistor, a first end of which is connected to a first end of the first switching module, and a second end of which is connected to a second end of the first switching module; the second switching module includes a second switching transistor, a first end of which is connected to a first end of the second switching module, and a second end of which is connected to a second end of the second switching module.

[0011] In one embodiment, the braking system further includes a configuration unit that responds to a user operation to output a path selection signal, the path selection signal being used to specify whether the braking system is connected to the built-in resistor or to an external resistor connected to the external resistor switching circuit.

[0012] In one embodiment, the configuration unit includes a DIP switch, the first output terminal of which is connected to the first output terminal of the configuration unit to output the path selection signal; the second output terminal of which is connected to the second output terminal of the configuration unit to output a preset voltage threshold.

[0013] In one embodiment, the braking system further includes a voltage sampling unit, a first input terminal of which is connected to the positive terminal of the DC bus of the braking system, and a second input terminal of which is connected to the negative terminal of the DC bus of the braking system; the voltage sampling unit is used to acquire the bus voltage of the positive terminal of the DC bus and the negative terminal of the DC bus of the braking unit.

[0014] In one embodiment, the braking system further includes a comparator circuit. A first input terminal of the comparator circuit is connected to a first output terminal of the configuration unit. A second input terminal of the comparator circuit is connected to a second output terminal of the configuration unit. A third input terminal of the comparator circuit is connected to the output terminal of the voltage sampling unit. A first output terminal of the comparator circuit is connected to a first terminal of the first switching module. A second output terminal of the comparator circuit is connected to a second terminal of the second switching module. The comparator circuit outputs a first conduction signal for the built-in resistor connected to the braking system specified by the path selection signal, based on the voltage threshold and the bus voltage. Alternatively, the comparator circuit outputs a second conduction signal for the external resistor connected to the external resistor switching circuit of the braking system specified by the path selection signal, based on the voltage threshold and the bus voltage.

[0015] In one embodiment, the braking system further includes a temperature sampling unit for detecting the temperature of the braking unit.

[0016] In one embodiment, the temperature sampling unit includes thermistors R3, R4, and R5; The first end of the thermistor R3 is connected to the first end of the built-in resistor, and the second end of the thermistor R3 is connected to the second end of the built-in resistor; the first end of the thermistor R4 is connected to the first end of the first switching module, and the second end of the thermistor R4 is connected to the second end of the first switching module; the first end of the thermistor R5 is connected to the first end of the second switching module, and the second end of the thermistor R5 is connected to the second end of the second switching module.

[0017] According to another aspect of this application, one embodiment provides a motor drive system, including: A driver, used to drive a motor; The braking system has its positive DC bus terminal connected to the positive DC bus terminal of the driver, and its negative DC bus terminal connected to the negative DC bus terminal of the driver. The braking system is the braking system described in any of the above embodiments.

[0018] According to the braking system and motor drive system of the above embodiments, the braking system includes a built-in resistor branch and an external resistor switching circuit, which are independently controlled in conjunction with a first switching module and a second switching module, respectively, realizing flexible switching between built-in resistor mode and external resistor mode. Under normal operating conditions, the system can activate the first switching module through a first conduction signal, allowing the built-in resistor branch to participate in energy dissipation, thereby meeting the daily braking energy consumption requirements. When the bus energy is detected to be too high or the regenerative power exceeds the tolerance range of the built-in resistor, the second switching module is activated through a second conduction signal, causing the external resistor connected to the external resistor switching circuit to work, realizing high-power energy dissipation. This application enables rapid switching between internal and external resistors by setting a first switching module and a second switching module, without the need for additional external relays or manual wiring, improving system integration and ease of use. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of one method for connecting the braking resistor in the background art; Figure 2 This is a schematic diagram of the second method for connecting the braking resistor in the background technology; Figure 3 A schematic diagram of the braking system in one embodiment. Figure 1 ; Figure 4 A schematic diagram of the braking system in one embodiment. Figure 2 ; Figure 5 A schematic diagram of the braking system in one embodiment. Figure 3 ; Figure 6 A schematic diagram of the braking system in one embodiment. Figure 4; Figure 7 A schematic diagram of the braking system in one embodiment. Figure 5 ; Figure 8 A schematic diagram of the braking system in one embodiment. Figure 6 ; Figure 9 This is a schematic diagram of the circuit connection of the built-in resistor branch, the external resistor switching circuit, and the temperature sampling unit in one embodiment. Figure 10 This is a schematic diagram of a braking system in one embodiment; Figure 11 This is a connection diagram of the motor drive system in another embodiment. Detailed Implementation

[0020] The present application will now be described in further detail with reference to the accompanying drawings and specific embodiments. Similar elements in different embodiments are referred to by related similar element reference numerals. In the following embodiments, many details are described to facilitate a better understanding of the present application. However, those skilled in the art will readily recognize that some features may be omitted in different situations, or may be replaced by other elements, materials, or methods. In some cases, certain operations related to the present application are not shown or described in the specification. This is to avoid obscuring the core parts of the present application with excessive description. For those skilled in the art, detailed description of these related operations is not necessary; they can fully understand the related operations based on the description in the specification and general technical knowledge in the art.

[0021] Furthermore, the features, operations, or characteristics described in the specification can be combined in any suitable manner to form various embodiments, and the operational steps involved in each embodiment can also be rearranged or adjusted in a manner that is obvious to those skilled in the art. Therefore, the specification and drawings are only for clearly describing a particular embodiment and do not imply that they represent the necessary components and / or order.

[0022] The serial numbers assigned to components in this document, such as "first" and "second," are used only to distinguish the described objects and have no sequential or technical meaning. The terms "connection" and "linkage" used in this application, unless otherwise specified, include both direct and indirect connections (linkages).

[0023] Please refer to Figure 3 One embodiment provides a braking system 100, including a braking unit 110. The braking unit 110 includes a built-in resistor branch 111 and an external resistor switching circuit 112. The built-in resistor branch 111 and the external resistor switching circuit 112 are respectively used for braking energy consumption under different power levels or different heat dissipation conditions.

[0024] In one embodiment, the first end of the built-in resistor branch 111 is connected to the positive terminal of the DC bus of the braking system 100 (i.e., Figure 3 The second terminal of the built-in resistor branch 111 is connected to the negative terminal of the DC bus of the braking system 100 (i.e., DC+). Figure 3 DC-). The first terminal of the external resistor switching circuit 112 is connected to the first brake output terminal of the braking system 100 (i.e., DC-). Figure 3 The second terminal of the external resistor switching circuit 112 (RB+) is connected to the positive terminal of the DC bus of the braking system 100.

[0025] In one embodiment, the built-in resistor branch 111 includes a built-in resistor 1111 and a first switching module 1112. The first end of the built-in resistor 1111 is connected to the first end of the built-in resistor branch 111, the second end of the built-in resistor 1111 is connected to the first end of the first switching module 1112, and the second end of the first switching module 1112 is connected to the second end of the built-in resistor branch 111.

[0026] It should be noted that the built-in resistor 1111 is a pre-installed component of the braking system 100, used to absorb and release bus energy under normal braking energy conditions. The built-in resistor 1111 can be multiple resistors connected in series or parallel; the number of resistors and the connection method can be determined based on the actual engineering application and are not limited here.

[0027] In one embodiment, when the braking system 100 experiences significant pumping energy or high-frequency braking conditions during operation, a single built-in resistor 1111 may not be able to efficiently dissipate energy within a safe range. Therefore, the braking system 100 includes an external resistor switching circuit 112. The external resistor switching circuit 112 includes a second switching module 1122, with a first terminal connected to the first terminal of the external resistor switching circuit 112 and a second terminal connected to the second terminal of the external resistor switching circuit 112.

[0028] In one embodiment, the external resistor switching circuit 112 is connected to an external resistor. The first brake output terminal of the braking system is used to connect to the first terminal of the external resistor, and the second brake output terminal of the braking system is used to connect to the second terminal of the external resistor (i.e., Figure 3 (RB- in the text). The external resistor can be multiple resistors connected in series or parallel. The number of resistors and the connection method can be determined according to the actual use in the project, and are not limited here.

[0029] It should be noted that the external resistor is a resistor independent of the braking system 100, and its rated power, resistance value, and heat dissipation structure can be customized according to different application scenarios. Among them, the external resistor can be an aluminum shell wire-wound or water-cooled high-power resistor to ensure good thermal stability and power handling capacity under high voltage and high current braking conditions.

[0030] In one embodiment, during operation, the braking system 100 generates corresponding conduction signals based on parameters such as DC bus voltage, current, or temperature rise. Specifically: when a first conduction signal is generated, the first switching module 1112 is turned on, and the built-in resistor branch 111 forms a loop to absorb energy and complete the braking process; when a second conduction signal is generated, the second switching module 1122 is turned on, and the external resistor switching circuit 112 is put into operation, thereby connecting an external resistor to achieve external energy dissipation; when neither is turned on, the built-in resistor branch 111 and the external resistor switching circuit 112 are in an open state, and the braking system 100 does not perform energy feedback or braking consumption.

[0031] It should be noted that, in order to ensure the safety of the braking system 100, electrical isolation is provided between the built-in resistor branch 111 and the external resistor switching circuit 112, that is, only one of them is allowed to conduct in any working state.

[0032] In summary, by utilizing the aforementioned braking system 100 configuration, the braking system 100 can select an appropriate energy dissipation path according to different operating conditions. For example, under light load or short-term braking conditions, the built-in resistor branch 111 can complete energy absorption, with fast response and compact structure. Under heavy load or long-term braking conditions, the braking system 100 can activate the external resistor in the external resistor switching circuit 112 to enhance braking capability and improve heat dissipation efficiency. Furthermore, this application achieves the switching between the built-in resistor branch 111 and the external resistor switching circuit 112 through the first switching module 1112 and the second switching module 1122. Under normal operating conditions, only the first switching module 1112 needs to be activated to connect to the built-in resistor branch 111. If the operating conditions are more stringent, the second switching module 1122 is activated to connect to the external resistor connected to the external resistor switching circuit 112, thereby avoiding complex parallel or multi-stage connection structures and making the overall circuit layout simpler. Meanwhile, the start and stop of different branches can be realized through the switching control of the first switching module 1112 and the second switching module 1122, without the need to disassemble the main circuit, which facilitates the debugging and maintenance of the braking system 100.

[0033] Please refer to Figure 4In one embodiment, the first switching module 1112 includes a first switching transistor 11121, with a first end connected to the first end of the first switching module 1112 and a second end connected to the second end of the first switching module 1112. Similarly, the second switching module 1122 includes a second switching transistor 11221, with a first end connected to the first end of the second switching module 1122 and a second end connected to the second end of the second switching module 1122.

[0034] It should be noted that both the first switching transistor 11121 and the second switching transistor 11221 can be electronic switching devices such as transistors, field-effect transistors, or insulated-gate bipolar transistors. Please refer to Figure 5 In one embodiment, the braking system 100 further includes a configuration unit 120, which responds to a user operation to output a path selection signal, the path selection signal being used to specify whether the braking system selects to connect an internal resistor or an external resistor when braking is required.

[0035] Please refer to Figure 6 In one embodiment, the configuration unit 120 in this application adopts a DIP switch 121. The first output terminal of the DIP switch 121 is used to connect to the first output terminal of the configuration unit 120 to output a path selection signal; the second output terminal of the DIP switch 121 is used to connect to the second output terminal of the configuration unit 120 to output a preset voltage threshold.

[0036] In one embodiment, the DIP switch 121 has 7 valid DIP positions. Positions 1 to 5 are used by the user to set the voltage threshold for initiating braking. The user can select different voltage threshold levels through different DIP combinations, thereby flexibly adjusting the braking start point according to system characteristics or engineering application requirements. Position 6 is used to set the control mode. When position 6 is in the first state, the braking system 100 adopts a manual setting mode, where the user manually determines the braking voltage threshold. When position 6 is in the second state, the braking system 100 enters an automatic calculation mode, automatically calculating and setting the braking voltage threshold based on sampled motor data and motor operating status. Position 7 is used to switch the resistor configuration mode. When position 7 is in the first state, the output path selection signal causes the braking system 100 to use a built-in resistor when braking is required. When position 7 is in the second state, the output path selection signal causes the braking system 100 to use an external resistor when braking is required.

[0037] Please refer to Figure 7In one embodiment, the braking system 100 further includes a voltage sampling unit 130. A first input terminal of the voltage sampling unit 130 is connected to the positive terminal of the DC bus of the braking system 100, and a second input terminal of the voltage sampling unit 130 is connected to the negative terminal of the DC bus of the braking system 100. The voltage sampling unit 130 is used to acquire the real-time bus voltage between the positive and negative terminals of the DC bus of the braking unit 110.

[0038] Please refer to Figure 8 In one embodiment, the braking system 100 further includes a comparison circuit 140. A first input terminal of the comparison circuit 140 is connected to a first output terminal of the configuration unit 120 for acquiring a path selection signal. A second input terminal of the comparison circuit 140 is connected to a second output terminal of the configuration unit 120 for acquiring a voltage threshold. A third input terminal of the comparison circuit 140 is connected to the output terminal of the voltage sampling unit 130 for acquiring the bus voltage. The first output terminal of the comparison circuit 140 is connected to the control terminal of a first switching transistor, and the second output terminal of the comparison circuit 140 is connected to the control terminal of a second switching transistor.

[0039] In one embodiment, the comparator circuit 140 outputs a first conduction signal or a second conduction signal based on the path selection signal, according to a voltage threshold and a bus voltage. If the configuration unit 120, in response to the path selection signal output by the user operation, specifies that the braking system should connect to an internal resistor when braking is required, then the comparator circuit 140 compares the voltage threshold and the bus voltage. When the bus voltage is greater than the voltage threshold, the comparator circuit 140 outputs the first conduction signal, causing the first switch to close, thereby connecting the internal resistor. If the configuration unit 120, in response to the path selection signal output by the user operation, specifies that the braking system should connect to an external resistor when braking is required, then the comparator circuit 140 compares the voltage threshold and the bus voltage. When the bus voltage is greater than the voltage threshold, the comparator circuit 140 outputs the second conduction signal, causing the second switch to close, thereby connecting the external resistor connected to the external resistor switching circuit 112.

[0040] It should be noted that the comparator circuit can use any existing, publicly available circuit that can perform voltage comparison.

[0041] Please refer to Figure 9 In one embodiment, the built-in resistor 1111 is resistor R1, the first switching transistor 11121 is MOSFET G1, and the second switching transistor 11221 is MOSFET G2. A first turn-on signal controls the base of MOSFET G1, thereby controlling the on and off states of diode M1, and thus controlling the on and off states of the built-in resistor branch 111. A second turn-on signal controls the base of MOSFET G2, thereby controlling the on and off states of diode M2, and thus controlling the on and off states of the external resistor switching circuit 112.

[0042] In one embodiment, the braking system 100 further includes a temperature sampling unit 150 (not shown in the figure) for detecting the temperature of the braking unit 110 to achieve thermal safety monitoring of the operating status of the execution system. The temperature sampling unit 150 includes a thermistor R3, a thermistor R4, and a thermistor R5. The first end of the thermistor R3 is connected to the first end of the built-in resistor 1111, and the second end of the thermistor R3 is connected to the second end of the built-in resistor 1111; the first end of the thermistor R4 is connected to the first end of the first switching module 1112, and the second end of the thermistor R4 is connected to the second end of the first switching module 1112; the first end of the thermistor R5 is connected to the first end of the second switching module 1122, and the second end of the thermistor R5 is connected to the second end of the second switching module 1122.

[0043] In one embodiment, a thermistor can also be set for the external resistor R2 connected to the external resistor switching circuit 112 to detect the temperature of the external resistor.

[0044] In one embodiment, the output terminal of the temperature sampling unit 150 is connected to the fourth input terminal of the comparison circuit 140. The comparison circuit 140 receives the temperature sampling signals of each thermistor in real time. When the temperature sampling signal output by any thermistor exceeds the preset alarm temperature threshold of the braking system 100, the comparison circuit 140 outputs an alarm signal, and the display screen of the braking system 100 enters a flashing prompt mode to remind the user that the braking system 100 may be in an overuse state. If the temperature sampling signal continues to rise and exceeds the emergency stop alarm temperature threshold, the comparison circuit 140 will actively shut down the built-in resistor branch 111 and the external resistor switching circuit 112, thereby cutting off the energy consumption path to protect the power components and the braking system 100 itself from overheating damage.

[0045] Please refer to Figure 10 The terminals of the braking system 100 are, in sequence, the positive terminal of the DC bus, the negative terminal of the DC bus, the first braking output terminal of the braking system 100, and the second braking output terminal of the braking system 100. The built-in resistor 1111 is connected between the positive and negative terminals of the DC bus. An external resistor, which can be configured according to the usage scenario, is connected between the first and second braking output terminals of the braking system 100. The built-in resistor branch 111 and the external resistor switching circuit 112 can be quickly switched using the DIP switch 121, without the need for complex wiring. The braking system 100 also displays the operating status of the braking unit 110 through a display unit, allowing the user to promptly understand the operating status of the braking system 100.

[0046] Please refer to Figure 11Another embodiment provides a motor drive system 10, which includes a driver 200 and a braking system 100. The driver 200 is used to drive a motor; the positive terminal of the DC bus of the braking system 100 is connected to the positive terminal of the DC bus of the driver 200, and the negative terminal of the DC bus of the braking system 100 is connected to the negative terminal of the DC bus of the driver 200. The braking system 100 adopts the braking system 100 of any of the above embodiments. Since the braking system 100 has been clearly described in the above embodiments, it will not be described again here.

[0047] The above-described specific examples are for illustrative purposes only and are not intended to limit the scope of this invention. Those skilled in the art to which this invention pertains can make various simple deductions, modifications, or substitutions based on the concept of this invention.

Claims

1. A braking system, characterized in that, include: The braking unit includes a built-in resistor branch and an external resistor switching circuit. The first end of the built-in resistor branch is connected to the positive terminal of the DC bus of the braking system, and the second end of the built-in resistor branch is connected to the negative terminal of the DC bus of the braking system. The first end of the external resistor switching circuit is connected to the first braking output terminal of the braking system, and the second end of the external resistor switching circuit is connected to the positive terminal of the DC bus of the braking system. The built-in resistor branch includes a built-in resistor and a first switching module. The first end of the built-in resistor is connected to the first end of the built-in resistor branch, the second end of the built-in resistor is connected to the first end of the first switching module, and the second end of the first switching module is connected to the second end of the built-in resistor branch. The external resistor switching circuit includes a second switching module, the first end of the second switching module is connected to the first end of the external resistor switching circuit, and the second end of the second switching module is connected to the second end of the external resistor switching circuit. The first switching module can be turned on by a first conducting signal, so that the braking system is connected to the built-in resistor; the second switching module can be turned on by a second conducting signal, so that the braking system is connected to the external resistor connected to the external resistor switching circuit.

2. The braking system as described in claim 1, characterized in that, The first brake output terminal of the braking system is used to connect to the first terminal of an external resistor, and the second brake output terminal of the braking system is used to connect to the second terminal of an external resistor.

3. The braking system as described in claim 2, characterized in that, The first switching module includes a first switching transistor, with a first end of the first switching transistor connected to a first end of the first switching module and a second end of the first switching transistor connected to a second end of the first switching module; the second switching module includes a second switching transistor, with a first end of the second switching transistor connected to a first end of the second switching module and a second end of the second switching transistor connected to a second end of the second switching module.

4. The braking system as described in claim 3, characterized in that, The braking system further includes a configuration unit that responds to a user operation by outputting a path selection signal, the path selection signal being used to specify whether the braking system is connected to the built-in resistor or to an external resistor connected to the external resistor switching circuit.

5. The braking system as described in claim 4, characterized in that, The configuration unit includes a DIP switch, the first output terminal of which is connected to the first output terminal of the configuration unit to output the path selection signal; the second output terminal of which is connected to the second output terminal of the configuration unit to output a preset voltage threshold.

6. The braking system as described in claim 5, characterized in that, The braking system further includes a voltage sampling unit. The first input terminal of the voltage sampling unit is connected to the positive terminal of the DC bus of the braking system, and the second input terminal of the voltage sampling unit is connected to the negative terminal of the DC bus of the braking system. The voltage sampling unit is used to acquire the bus voltage of the positive terminal of the DC bus and the negative terminal of the DC bus of the braking unit.

7. The braking system as claimed in claim 6, characterized in that, The braking system further includes a comparator circuit. The first input terminal of the comparator circuit is connected to the first output terminal of the configuration unit. The second input terminal of the comparator circuit is connected to the second output terminal of the configuration unit. The third input terminal of the comparator circuit is connected to the output terminal of the voltage sampling unit. The first output terminal of the comparator circuit is connected to the control terminal of the first switching transistor. The second output terminal of the comparator circuit is connected to the control terminal of the second switching transistor. The comparator circuit outputs a first conduction signal to activate the built-in resistor connected to the braking system specified by the path selection signal, based on the voltage threshold and the bus voltage. Alternatively, the comparator circuit outputs a second conduction signal to activate the external resistor connected to the external resistor switching circuit of the braking system specified by the path selection signal, based on the voltage threshold and the bus voltage.

8. The braking system as claimed in claim 7, characterized in that, The braking system also includes a temperature sampling unit for detecting the temperature of the braking unit.

9. The braking system as claimed in claim 8, characterized in that, The temperature sampling unit includes thermistor R3, thermistor R4 and thermistor R5; The first end of the thermistor R3 is connected to the first end of the built-in resistor, and the second end of the thermistor R3 is connected to the second end of the built-in resistor; the first end of the thermistor R4 is connected to the first end of the first switching module, and the second end of the thermistor R4 is connected to the second end of the first switching module; the first end of the thermistor R5 is connected to the first end of the second switching module, and the second end of the thermistor R5 is connected to the second end of the second switching module.

10. A motor drive system, characterized in that, include: A driver, used to drive a motor; A braking system wherein the positive terminal of the DC bus of the braking system is connected to the positive terminal of the DC bus of the driver, and the negative terminal of the DC bus of the braking system is connected to the negative terminal of the DC bus of the driver, and the braking system adopts the braking system as described in any one of claims 1-9.

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