Vehicle-mounted air-cooled brake resistor system with multiple protection

Abstract

The invention relates to a vehicle-mounted air-cooled brake resistor system with multiple protection, which comprises a brake resistor and a brake resistor controller, the brake resistor is mainly composed of a box body shell, a resistor unit and a cooling fan, the resistor unit is located in an air channel enclosed by the box body shell, the cooling fan is forced to cool a resistor disc, and the resistor disc is connected with the brake resistor controller. Two layers of insulation protection are formed in the resistor unit through an insulation structure, a high-voltage protection function is added to an internal circuit of the brake resistor controller, a main positive contactor and a main negative contactor are arranged to form electrical insulation protection, and meanwhile high-temperature protection is formed through a cooling fan fault feedback function and a temperature sensor. Through the three-layer insulation protection and high-temperature protection functions, the safety protection performance of an existing air-cooled brake resistor system is improved, the application requirements under the working conditions of multiple scenes are met, the product safety is improved, and the service life of the product is prolonged.

Description

Technical Field

[0001] The present invention relates to the technical field of new energy pure electric vehicles, and in particular to a vehicle-mounted air-cooled brake resistor system with multiple protections. Background Art

[0002] At present, new energy vehicles usually use regenerative braking, that is, during the braking process of the vehicle, the inertial energy of the vehicle is transferred to the motor through the transmission system. The motor runs in a power generation state to generate regenerative electric energy, which charges energy storage components such as power batteries, and realizes the regeneration of braking energy. At the same time, the motor torque generated can apply braking force to the drive wheels through the transmission system. Since regenerative braking utilizes the energy originally consumed by friction braking, it can reduce the energy consumption of new energy vehicles and improve the economy of the vehicle. However, during high-intensity braking or continuous braking, due to the capacity limitations of energy storage components such as batteries, the recovered electric energy cannot be fully absorbed. In this case, energy consumption braking is required. Based on economic cost considerations, air-cooled brake resistors can be installed to convert excess electric energy into heat energy for consumption, ensuring the safety and reliability of the entire vehicle.

[0003] There is currently no application of air-cooled brake resistor systems abroad. The water-cooled brake resistor BWD330 launched by Germany's Leo has a protection level of IP67 and can achieve the physical effect of being waterproof and dustproof; however, water-cooled resistors require an additional water cooling system. Due to the high price and long delivery time, there are currently no usage cases in China.

[0004] In China, devices similar to air-cooled brake resistors are maturely and widely used in electric-driven subways, trains and other rail vehicles and urban trolleybuses. The driving and braking methods of electric buses are similar to those of the above-mentioned electric locomotives, but the brake resistor system for electric buses is in the initial stage of exploration. At present, main manufacturers such as Shenzhen BYD, Xiamen Jinlong, Suzhou Jinlong, and Hengtian Lingrui are conducting research and development of vehicle-mounted brake resistor systems. New energy vehicles equipped with brake resistors have been exported in batches to many EU countries and the Middle East. Due to the promotion of test standards and price costs, domestic new energy vehicles are equipped with air-cooled brake resistor systems; because the main manufacturers focus on studying the matching solution of the brake resistor system and the whole vehicle, there is no targeted focus on the reliability protection of the entire brake resistor system.

[0005] At present, the auxiliary braking of pure electric buses is mainly electric regenerative braking. Under certain working conditions, there is a safety hazard of weakened or failed braking force. The solution is to install an air-cooled brake resistor system on pure electric vehicles. It is suitable for conditions such as high power battery SOC. When the battery cannot effectively absorb the regenerative braking energy, the air-cooled resistor absorbs the energy of vehicle deceleration and converts it into heat energy to dissipate. The traditional air-cooled brake resistor system has the following problems in use: 1. The air-cooled brake resistor is designed with an open structure to improve heat dissipation conditions. The protection level is IP20. The high-pressure spray test is in accordance with QC / T476-2007 "Limits and Test Methods for Rainproof Sealing of Passenger Vehicles". When tested at a higher severity level, the insulation performance of the unit is low or the insulation resistance value is unqualified. If the severity level is to be increased to meet the application scenarios of vehicles in harsh environments such as ice and snow rainstorms, sandstorms, dust, salt spray environments and other extreme working conditions, it is necessary to solve the problem of reduced system insulation protection performance; 2. The entire system does not have sufficient monitoring and protection against high temperature or over-temperature, and there is a risk of heat dissipation fan ablation; 3. The brake resistor controller does not have a high-voltage voltage collection function; if the IGBT is directly connected due to a fault, a large current will be generated at the moment the main contactor closes, causing the main contactor contacts to burn and stick, posing a safety hazard.

[0006] The reliability protection of air-cooled brake resistors is extremely important, as it is related to the safe operation of the entire vehicle and the service life of the brake resistor system. At this stage, the problem of improving the protection performance of the air-cooled brake resistor system needs to be solved. Summary of the invention

[0007] In view of the defects of the prior art, the present invention provides a vehicle-mounted air-cooled brake resistor system with multiple protections, which fully considers safety protection functions such as high temperature protection and insulation protection, so that the air-cooled brake resistor system can meet application requirements under multiple working conditions and improve product safety and service life.

[0008] In order to achieve the above object, the technical solution adopted by the present invention is: A vehicle-mounted air-cooled brake resistor system with multiple protections includes a brake resistor and a brake resistor controller. The brake resistor includes a box shell, a resistor unit and a cooling fan. The resistor unit is in an air duct surrounded by the box shell. The cooling fan is fixed on the box shell to force air cooling on the resistor unit in the air duct. The resistor unit includes a plurality of resistor rows, each of which is formed by a plurality of resistor sheets arranged on a string rod through insulators. Mica shields are respectively arranged on the upper and lower parts of the string rods. A plurality of resistor rows are installed in parallel to form the resistor unit. The resistor unit is supported on a frame inside the box through insulators. The brake resistor controller is connected to a motor controller and a vehicle controller. A main positive contactor and a main negative contactor are provided in the internal circuit of the brake resistor controller to achieve high-voltage protection.

[0009] Furthermore, in the internal circuit of the braking resistor controller, a main positive contactor is connected in series to the positive circuit of the braking resistor, a pre-charging resistor and a pre-charging contactor are arranged in parallel in series on the outside of the main positive contactor, an IGBT is connected to the negative circuit of the braking resistor and a main negative contactor is connected in series, a control board of the braking resistor controller controls the on and off of the IGBT through a driving board, a bus capacitor is provided between the positive and negative circuits at the rear ends of the main positive contactor and the main negative contactor, and when the braking resistor controller detects a system insulation failure, the main positive contactor and the main negative contactor are disconnected at the same time.

[0010] Furthermore, a control board of the braking resistor controller is connected to the cooling fan, and the cooling fan has a fault feedback function. When the cooling fan meets the operating conditions, the braking resistor controller monitors whether the cooling fan operates normally. When the cooling fan does not operate normally, a fault code is reported to the braking resistor controller, and the braking resistor controller immediately stops the unit from working.

[0011] Furthermore, the cooling fan is installed on the front plate of the box shell, and the rear plate of the box shell is covered with cooling holes, forming an air duct between the front plate and the rear plate.

[0012] Furthermore, the multiple resistor rows of the resistor unit are arranged in the box shell from front to back, and the resistor rows are parallel to the plane where the front plate is located. The cold air blown by the cooling fan passes through the gaps between the resistor sheets and is blown out from the heat dissipation holes on the rear plate.

[0013] Furthermore, the air-cooled brake resistor system is internally installed with multiple temperature sensors, which can monitor the temperature at different locations in real time and feed back to the brake resistor controller.

[0014] Furthermore, a temperature sensor extending into the resistance unit is installed on the front plate of the box shell to monitor the temperature at the air inlet; a temperature sensor is installed on the inner side of the rear plate of the box shell to monitor the temperature at the air outlet.

[0015] Furthermore, the frame inside the box shell includes a top frame and a bottom frame, both of which are "well"-shaped structures, and the resistance unit and the frame are insulated and isolated by insulators.

[0016] Furthermore, the resistor sheet is provided with pressure ribs for reducing deformation caused by thermal expansion of the resistor sheet.

[0017] Furthermore, the box shell is also provided with a cable plug and a connection terminal.

[0018] Beneficial effects: The whole set of air-cooled brake resistor system consists of two parts: brake resistor and brake resistor controller. The reliability protection function is mainly system insulation protection and high temperature monitoring protection. The present invention mainly improves the protection performance of the brake resistor system from two aspects: system insulation protection and high temperature detection protection, so that it can meet the application requirements of more severe environments.

[0019] 1. The present invention makes improvements in both physical insulation protection and electrical protection, and provides multiple insulation protection functions for the braking resistor system: industrial-grade insulators are used between the resistor sheets to achieve the insulation protection function physically, and the first layer of insulation protection is composed of the resistor sheets, insulators, and mica shields; the resistor row is supported and fixed in the air by insulators, and maintains a safe electrical gap with the external shell of the box, forming a second layer of insulation protection; the internal contactor protection of the braking resistor controller, when the system insulation failure is detected, the main positive and main negative contactors are disconnected at the same time, eliminating the phenomenon that the high voltage cannot be disconnected due to the adhesion of a single contactor, forming a third layer of electrical protection, and multiple physical insulation protection and electrical protection improve the insulation protection performance of the unit.

[0020] 2. Multiple temperature sensors are installed inside the brake resistor to monitor the temperature in real time at different positions and provide feedback to prevent single point failure and effectively monitor high temperature. At the same time, the high temperature alarm temperature threshold of the temperature sensor is set. When the temperature is too high, the controller will promptly command the brake resistor to work; the cooling fan has a fault feedback function; when the cooling fan meets the operating conditions, the brake resistor controller monitors whether the fan is operating normally. If the fan is not operating normally, it will report a fault code to the brake resistor controller, and the controller will immediately stop the unit to avoid fan ablation caused by high temperature, effectively improving the high temperature protection function of the system. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 Internal structure diagram of brake resistor; Figure 2 Schematic diagram of the first layer of insulation protection; Figure 3 Schematic diagram of the second layer of insulation protection; Figure 4 Schematic diagram of the third layer of electrical protection; Figure 5 Schematic diagram of temperature sensor monitoring.

[0022] Markings in the figure: 1 box shell, 2 resistor unit, 3 cooling fan, 4 cable plug, 5 terminal block, 6 resistor row, 7 resistor sheet, 8 insulator, 9 mica guard plate, 10 top frame, 11 bottom frame, 12 braking resistor, 13 main positive contactor, 14 main negative contactor, 15 pre-charging resistor, 16 pre-charging contactor, 17 bus capacitor, 18 temperature sensor. DETAILED DESCRIPTION

[0023] The present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0024] like Figure 1 As shown: The vehicle-mounted air-cooled brake resistor system of the present invention includes a brake resistor and a brake resistor controller. Figure 1 As shown, the brake resistor is mainly composed of a box shell 1, a resistor unit 2, a cooling fan 3, a cable plug 4 and a terminal 5. The resistor unit 2 is located in an air duct surrounded by the box shell 1. The cooling fan 3 is fixed on the box shell 1 to force air cooling on the resistor unit 2 in the air duct. The internal structure of the resistor unit 2 has the effect of gathering and isolating heat. The cable plug 4 and the terminal 5 are located on the box shell 1.

[0025] Specifically, the resistor unit 2 includes a plurality of resistor rows 6 arranged in parallel and spaced apart from each other. Figure 2 As shown, each resistor row 6 includes a plurality of resistor sheets 7, and ribs are provided on the resistor sheets 7 to facilitate ventilation and heat dissipation, thereby reducing deformation caused by thermal expansion of the resistor sheets 7; both ends of the plurality of resistor sheets 7 are spaced apart on a string rod through insulators 8 to form a resistor row 6, and mica shields 9 are provided on the upper and lower parts of the string rod, respectively. The plurality of resistor rows 6 are installed in parallel to form the resistor unit 2, and the first layer of insulation protection of the brake resistor is formed by the resistor sheets 7, insulators 8 and mica shields 9.

[0026] A frame is provided inside the box housing 1 for supporting and installing the resistor unit 2. Figure 3 As shown, the frame includes a top frame 10 and a bottom frame 11. The top frame 10 and the bottom frame 11 are respectively formed into a "well"-shaped structure by multiple mounting brackets. The bottom frame can also add another mounting bracket in the middle on the basis of the "well"-shaped structure. The resistor unit 2 is supported on the frame inside the box body by an insulator 8. The resistor unit 2 is insulated and isolated from the frame by the insulator 8, and a safe gap is maintained between the resistor unit 2 and the box shell 1, forming a second layer of insulation protection for the brake resistor system.

[0027] Furthermore, the vehicle-mounted air-cooled brake resistor system of the present invention also improves electrical protection performance, and the brake resistor controller is connected to the motor controller and the vehicle controller, and the brake resistor controller also has current detection and high-voltage voltage collection functions.

[0028] like Figure 4As shown, the motor controller is connected to the motor. When the motor decelerates under the action of external force, the motor runs in a power generation state to generate regenerative energy. The three-phase AC electromotive force generated by the motor is rectified into a DC voltage by a frequency converter and connected to a battery to charge the battery. The positive and negative electrodes of the brake resistor 12 are respectively connected to the positive and negative electrodes of the battery, which is used to convert the energy that cannot be absorbed by the battery during high-intensity braking or continuous braking into heat energy for consumption. The positive circuit of the brake resistor 12 is connected in series with a main positive contactor 13, and the outer side of the main positive contactor 13 is connected in parallel with a pre-charge resistor 15 and a pre-charge contactor 16 connected in series. The negative electrode of the brake resistor 12 is connected to the collector of the IGBT, and the main negative contactor 14 is connected in series in the circuit between the emitter of the IGBT and the negative electrode of the battery. A bus capacitor 17 is provided between the positive and negative circuits at the rear ends of the main positive contactor 13 and the main negative contactor 14. The control board of the brake resistor controller controls the on and off of the IGBT through the drive board, and the control board can also detect the current output by the brake resistor 12.

[0029] When the brake resistor controller detects that the system insulation has failed and the brake resistor 12 is disconnected, the controller disconnects the main positive contactor 13 and the main negative contactor 14 at the same time, avoiding the situation where only the main positive contactor 13 is disconnected while the negative pole is still connected to the entire vehicle (when an IGBT failure causes a direct connection, a large current is generated at the instant the negative contactor closes, causing the contactor contacts to burn and adhere), resulting in reduced insulation performance and forming a third layer of electrical protection.

[0030] On the basis of the above insulation protection, the present invention also improves the high temperature protection function of the brake resistor system.

[0031] Under the control of the brake resistor controller, the brake resistor converts the feedback energy into heat energy and dissipates the heat through the cooling fan 3; the cooling fan 3 is installed on the front plate of the box shell 1, and at the same time, the rear plate of the box shell 1 is covered with heat dissipation holes, forming an air duct between the front plate and the rear plate. The multiple resistor rows 6 of the resistor unit 2 are arranged in the box shell 1 from front to back, and the resistor rows 6 are parallel to the plane where the front plate is located. The cold air blown by the cooling fan 3 passes through the gaps between the resistor sheets 7 and blows out from the heat dissipation holes on the rear plate. For example, the rated power of the brake resistor system is 100kW, and a large amount of heat needs to be dissipated by the cooling fan 3. If the cooling fan 3 fails to operate normally due to damage to the wiring harness, loose plug-in, etc., and the fault cannot be reported, the heat accumulation will cause high temperature and even fan ablation. Therefore, it is very important to monitor whether the fan is running. The brake resistor can only work when the fan is running normally; if the fan does not run for some reason, the brake resistor should be prohibited from working.

[0032] In the present invention, the control board of the braking resistor controller is connected to the cooling fan 3, and the cooling fan 3 has a fault feedback function. When the cooling fan 3 meets the operating conditions, the braking resistor controller monitors whether the cooling fan 3 operates normally. When the cooling fan 3 does not operate normally, the braking resistor controller reports a fault code to the braking resistor controller, and the braking resistor controller immediately stops the unit from working, effectively avoiding the occurrence of fan ablation.

[0033] like Figure 5 As shown, there are multiple temperature sensors 18 placed inside the air-cooled brake resistor system, which are connected to the brake resistor controller, and can monitor the temperature of different positions in real time and feed back to the brake resistor controller. At least the following positions are provided with temperature sensors 18: a temperature sensor 18 is installed on the front plate of the box shell 1, and the probe of the sensor extends into the resistor unit 2, which can monitor the temperature at the air inlet; a temperature sensor 18 is installed on the inner side of the rear plate of the box shell 1, which is used to monitor the temperature at the air outlet. The temperature sensor 18 is a probe-type sensor, and the probe absorbs a large range of heat radiation. Through multi-point temperature detection, the high temperature alarm temperature of the temperature sensor 18 is set to a threshold. When the temperature is higher than this temperature, the controller commands the brake resistor to stop working. When the temperature is lower than this threshold, the brake resistor continues to respond to the requirements of the vehicle, effectively preventing the occurrence of over-temperature.

[0034] In general, the reliability of the brake resistor system is mainly reflected in the insulation protection and high temperature protection performance. If the system has high temperature ablation or insulation failure, it will cause a greater safety hazard. The improvement of the system protection performance of the present invention is mainly reflected in the following aspects: 1. System insulation protection: For the existing brake resistor system, the high-voltage spray test is generally carried out in accordance with QC / T476-2007 "Limits and test methods for rainproof sealing of passenger cars". When the product is tested at a higher severity level, the system insulation performance is reduced or the insulation resistance value is unqualified, which is difficult to meet the application scenarios of vehicles in extreme working conditions such as snow and ice rainstorms, sandstorms, and salt fog environments. Therefore, it is necessary to improve the protection function of the brake resistor. The brake resistor of the present invention has multiple insulation structures inside: industrial-grade insulators are used between the resistor sheets to physically achieve the insulation protection function; the first layer of insulation protection is composed of the resistor sheets. , insulators, and mica guard plates; the second layer of insulation protection consists of three parts: the bottom frame, insulators and top frame. The resistor is fixed in the air by the insulator to maintain a safe electrical gap with the external shell; the third layer of electrical protection, the braking resistor controller is designed to increase the high-voltage voltage collection function, and the internal contactor protection of the braking resistor controller. When the system insulation failure is detected and the main positive and main negative contactors are disconnected at the same time, the phenomenon that the high voltage voltage cannot be disconnected due to the adhesion of a single contactor is eliminated. Through multiple physical insulation protection and electrical protection, the insulation protection performance of the unit is improved to meet higher severity level tests.

[0035] 2. High temperature monitoring protection: The brake resistor converts the feedback energy into heat energy under the control of the controller, and dissipates the heat through the cooling fan. The high temperature protection function is very important; through a large number of tests, the present invention sets multiple temperature sensors inside the brake resistor to monitor the temperature in real time and feedback at different positions to prevent single point failure; the cooling fan has a fault feedback function; when the cooling fan meets the operating conditions, the brake resistor controller monitors whether the fan is running normally. If the fan is not running normally, it will report the fault code to the brake resistor controller, and the controller will immediately stop the unit to prevent heat accumulation from causing high temperature and even fan ablation.

[0036] The present invention is developed around solving the safety protection problem during the use of air-cooled brake resistors. It can meet the application scenarios of vehicles in extreme multi-working conditions such as harsh environments such as ice and snow rainstorms, sandstorms and dust, salt spray environments, etc. It can significantly improve the safety of the vehicle's auxiliary braking system and has a positive role in promoting the healthy and stable development of new energy vehicles.

[0037] The present invention is an optimized and modified product based on the existing mature product air-cooled brake resistor. The key technologies such as hardware principles, control strategies, and software algorithms have been mastered, and the technology is feasible. In addition, on the market, major OEMs have begun to install and use air-cooled brake resistors, and the number of matching car models is also gradually increasing, which has a high market prospect.

[0038] The above description is only a preferred embodiment of the present invention and does not limit the present invention in any form. Although the present invention has been disclosed as a preferred embodiment as above, it is not used to limit the present invention. Any technician familiar with this profession can make some changes or modify the technical contents disclosed above into equivalent embodiments without departing from the scope of the technical solution of the present invention. However, any simple modification, equivalent change and modification made to the above embodiments according to the technical essence of the present invention without departing from the content of the technical solution of the present invention still fall within the scope of the technical solution of the present invention.

Claims

1. A vehicle-mounted air-cooled brake resistor system with multiple protections, comprising a brake resistor and a brake resistor controller, characterized in that: The brake resistor comprises a housing (1), a resistor unit (2) and a cooling fan (3); the resistor unit (2) is located in an air duct surrounded by the housing (1); the cooling fan (3) is fixed to the housing (1) to force air cooling on the resistor unit (2) in the air duct; the resistor unit (2) comprises a plurality of resistor rows (6); each resistor row (6) is formed by a plurality of resistor sheets (7) arranged on a string rod at intervals through insulators (8); a mica shield (9) is provided at the upper and lower parts of the string rod respectively; a plurality of resistor rows (6) are installed in parallel to form the resistor unit (2); the resistor unit (2) is supported overhead on a frame inside the housing (1) through insulators (8); the brake resistor controller is connected to a motor controller and a vehicle controller; a main positive contactor (13) and a main negative contactor (14) are provided in the internal circuit of the brake resistor controller to achieve high voltage protection.

2. The vehicle-mounted air-cooled brake resistor system with multiple protections according to claim 1 is characterized in that: In the internal circuit of the braking resistor controller, a main positive contactor (13) is connected in series to the positive circuit of the braking resistor (12), a pre-charging resistor (15) and a pre-charging contactor (16) are arranged in parallel on the outside of the main positive contactor (13), an IGBT is connected to the negative circuit of the braking resistor (12) and a main negative contactor (14) is connected in series, a control board of the braking resistor controller controls the on and off of the IGBT through a driving board, a bus capacitor (17) is arranged between the positive and negative circuits at the rear ends of the main positive contactor (13) and the main negative contactor (14), and when the braking resistor controller detects that the system insulation fails, the main positive contactor (13) and the main negative contactor (14) are disconnected at the same time.

3. The vehicle-mounted air-cooled brake resistor system with multiple protections according to claim 2 is characterized in that: A control panel of the brake resistor controller is connected to the cooling fan (3), and the cooling fan (3) has a fault feedback function. When the cooling fan (3) meets the operating conditions, the brake resistor controller monitors whether the cooling fan (3) is operating normally. When the cooling fan (3) is not operating normally, a fault code is reported to the brake resistor controller, and the brake resistor controller immediately stops the operation of the unit.

4. The vehicle-mounted air-cooled brake resistor system with multiple protections according to claim 1 is characterized in that: The cooling fan (3) is installed on the front plate of the box shell (1), and the rear plate of the box shell (1) is covered with cooling holes, forming an air duct between the front plate and the rear plate.

5. The vehicle-mounted air-cooled brake resistor system with multiple protections according to claim 4 is characterized in that: The plurality of resistor rows (6) of the resistor unit (2) are arranged in a spaced relationship from front to back in the housing (1), and the resistor rows (6) are parallel to the plane where the front plate is located, and the cold air blown out by the cooling fan (3) passes through the gaps between the resistor sheets (7) and is blown out from the cooling holes on the rear plate.

6. The vehicle-mounted air-cooled brake resistor system with multiple protections according to claim 4, characterized in that: The air-cooled brake resistor system has multiple temperature sensors (18) installed inside it, which can monitor the temperature at different locations in real time and provide feedback to the brake resistor controller.

7. The vehicle-mounted air-cooled brake resistor system with multiple protections according to claim 6, characterized in that: A temperature sensor (18) extending into the interior of the resistance unit (2) is installed on the front plate of the box shell (1) for monitoring the temperature at the air inlet; and a temperature sensor (18) is installed on the inner side of the rear plate of the box shell (1) for monitoring the temperature at the air outlet.

8. The vehicle-mounted air-cooled brake resistor system with multiple protections according to claim 1, characterized in that: The frame inside the box shell (1) comprises a top frame (10) and a bottom frame (11); the top frame (10) and the bottom frame (11) are both of a "well"-shaped structure; the resistance unit (2) and the frame are insulated and isolated via an insulator (8).

9. The vehicle-mounted air-cooled brake resistor system with multiple protections according to claim 1, characterized in that: The resistor sheet (7) is provided with a compression rib for reducing deformation caused by thermal expansion of the resistor sheet (7).

10. The vehicle-mounted air-cooled brake resistor system with multiple protections according to claim 1, characterized in that: The box housing (1) is also provided with a cable plug (4) and a wiring terminal (5).

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