Active discharge redundancy method for a crane

Abstract

The application discloses a kind of active discharge redundancy method for crane belongs to crane active discharge technical field, it is in to solve the problems of slow discharge speed, incomplete discharge, single discharge means and the voltage of fault branch and high-voltage system bus capacitor cannot be discharged when fault occurs existing in prior art.The application, reserve a branch driver as the system branch of system bus discharge, when the rest branch has fault and cannot discharge, discharge is carried out using system branch Km.When system branch discharges, to reduce the discharge amount of system branch driver, low-voltage DCDC and PTC are used to pre-discharge bus capacitor, and the voltage is reduced to the voltage in the working range, then active discharge is carried out using the driver, the time of active discharge of the driver is reduced, and the heating of branch cylinder driver is reduced.When the whole vehicle has serious fault, bus voltage is released using discharge resistance, which ensures that discharge is realized in fault state.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of crane active discharge, and particularly relates to a crane active discharge redundancy method. BACKGROUND

[0002] Traditional cranes mostly adopt hydraulic power sources, and realize the extension and retraction of horizontal or vertical outriggers through hydraulic cylinders, so as to prepare for the hoisting operation of the crane; the rotation, luffing, lifting and extension of the hoisting arm are realized through hydraulic motors and cylinders, so that the hoisted object can be accurately and stably placed at the specified position. With the development of electrification of crane operation, the electric cylinder which converts the rotary motion of the motor into linear motion can be applied to the outrigger, luffing and steering of the crane; the rotary motion of the motor can be applied to the rotation and lifting operation of the crane and the driving of the hydraulic pump through the use of a reduction mechanism, etc. The electrification of the crane operation is realized.

[0003] The crane system driven by the electric cylinder mainly consists of an electric cylinder, a driver, a power battery and high-voltage accessories. In the crane system driven by the electric cylinder, multiple electric cylinders realize the functions of luffing of the hoisting arm, extension and retraction of the hoisting arm, extension and retraction of the horizontal / vertical outrigger, steering of the vehicle, etc., which are respectively controlled by multiple drivers, and the DC bus of each driver is connected in parallel with a thin film energy storage capacitor. The power battery provides energy for the whole system, and the high-voltage level thereof is usually about 600V, which is much higher than the safe voltage of 36V that the human body can withstand. When the system enters the current-off process or enters the safety state due to a fault, the power battery needs to be disconnected from each driver and high-voltage component. After the relay is disconnected, the capacitor on the high-voltage bus of the DC input end of the driver will store a certain amount of electricity. In order to prevent harm to the human body, the electricity needs to be discharged in time.

[0004] After the driver is cut off from the power supply, passive discharge and active discharge can be used to realize the discharge of system energy. The passive discharge utilizes the self-loss of the motor driver and the friction of the motor transmission device to realize the consumption of energy. The disadvantage of this method is that the discharge speed is slow, and if the bus voltage cannot be quickly reduced to the safe voltage value in the event of an accident, the potential electric shock risk will cause secondary injury to passengers and rescue personnel. The active discharge generally adopts motor winding discharge or uses discharge resistors between buses to control the switching discharge by power switching devices. In general, the time required for active discharge should not exceed 3s.

[0005] After the system enters the discharge process or the emergency state, the relay of the driver is disconnected. If the active discharge of some or all drivers fails, the bus voltage will not be discharged quickly, and there will be a certain safety risk due to the existence of the bus voltage.

[0006] A large amount of work has been done by those skilled in the art for active discharge technology, but the main limitation is how to achieve the method of active discharge, specifically:

[0007] Chinese Patent CN119217983B discloses a kind of active discharge control method, electronic equipment and readable storage medium, in the case where the active discharge state of the motor winding of vehicle is detected to be abnormal, redundancy active discharge instruction is generated;Based on redundancy active discharge instruction, through pulse width modulation (PWM) signal control motor in vehicle to carry out active discharge.The scheme increases another control method from the controller when the active discharge of single controller exists exception, control is complex, if controller fails completely, then it cannot carry out active discharge or discharge is not complete.

[0008] Chinese Patent CN118413155A discloses a kind of plug-in operation system, device and active discharge method, through motor controller, the open state of bus is judged by judging the open phase state of three-phase electricity of bus through internal open phase detection module, in the case where bus is judged to be disconnected, control bus capacitor active discharge.That is, in the plug-in operation system that takes electricity directly from front-end power grid through circuit breaker, motor controller can control bus capacitor active discharge in motor controller by judging the open state of three-phase electricity of bus through open phase detection module, so that plug-in crane with circuit breaker for high-voltage switch can realize active discharge, and the active discharge instruction issued by vehicle controller is cancelled, the process of active discharge is simplified, the efficiency of active discharge is improved, and the problem that voltage threshold is difficult to determine when judging the open state of front-end power grid through voltage detection, so as to accurately judge whether bus is disconnected is avoided.The technical scheme mainly solves the source of active discharge instruction, simplifies the process of active discharge, but if active discharge fails, there is a safety hazard.

[0009] A hydrogen energy automobile pre-charging and discharging system and its charging and high voltage lowering method are disclosed in Chinese Patent Publication No. CN112977069B. The high voltage auxiliary power supply, the first pre-charging circuit and the motor controller of the invention form a closed circuit in series, the fuel cell boost FCDC is connected in parallel across the high voltage auxiliary power supply, and the voltage reducing DCL is connected in parallel across the motor controller; the second pre-charging circuit, the fuel cell air compressor controller and the high voltage components are connected in series in turn to form a branch, which is connected in parallel across the high voltage auxiliary power supply; the heater PTC is connected in parallel across the high voltage auxiliary power supply; and the fuel cell PTC is connected in parallel across the high voltage auxiliary power supply. In the case where the fuel cell air compressor controller and the high voltage components do not have an active discharging function, the invention discharges by the heater PTC or the fuel cell PTC of the whole vehicle, shortens the discharging time of the support capacitor, and makes the drive motor of the whole vehicle lower the voltage first without waiting for the purging process of the fuel cell system, and the pre-charging is performed separately. In this scheme, only PTC is used to shorten the discharging time of the support capacitor, and the discharging means is single.

[0010] Reference Figure 1 In the prior art, the power battery is connected to the high voltage power distribution system through a relay Kbat, the high voltage power distribution system is connected to the drive of the electric cylinder through relays K1 to Kn, connected to the high voltage accessory-low voltage DCDC through a relay Kf1, and connected to the high voltage accessory-air conditioner PTC through a relay Kf2. When receiving a high voltage power-off command, each electric component is first shut down, the K1 to Kn and Kf1 and Kf1 relays connected to the drive of the electric cylinder are disconnected, the power battery is ensured to have no current output, and the relay Kbat is disconnected. After disconnecting the relays K1 to Kn and Kf1 and Kf1, the drive of the electric cylinder enters an active discharging process to discharge the bus capacitor voltage. This active discharging method has the following technical problems:

[0011] 1) During power-off, K1 to Kn are closed, and the drive of each branch discharges the bus capacitor voltage of the branch. If the active discharging of the drive of the branch fails or the drive itself fails, the branch cannot be discharged, and there is a high voltage safety risk in the branch.

[0012] 2) No redundant discharging device is provided for the entire high voltage system. If a serious fault occurs in the system, all drives cannot discharge, and the voltage of the bus capacitor of the high voltage system cannot be discharged. SUMMARY

[0013] The purpose of the present invention is to provide an active discharging redundancy method for cranes to solve the problems of slow discharging speed, incomplete discharging, single discharging means and inability to discharge the voltage of the fault branch and the bus capacitor of the high voltage system when a fault occurs in the prior art.

[0014] To achieve the above object, the application is a kind of active discharge redundancy method for crane, which is specifically as follows:

[0015] Step one: after the high-voltage power distribution system receives the vehicle power-off command, the electric cylinder and high-voltage accessories are stopped;

[0016] Step two: disconnect the relay Kbat connecting the power battery and the high-voltage power distribution system;

[0017] Step three: determine whether the drive system of the vehicle has a serious fault, if yes, enable the discharge resistor to discharge the bus capacitor; if no, execute step four;

[0018] Step four: determine whether DCDC and PTC have all faults, if no, enable DCDC and PTC in a cycle and execute step five; if yes, execute step six;

[0019] Step five: determine whether the bus voltage is less than the set voltage, if no, continue to enable DCDC and PTC; if yes, disable DCDC and PTC and execute step six;

[0020] Step six: select a branch of the electric cylinder driver without fault as the system branch, close the system branch relay Km and execute step eight; at the same time, disconnect the electric cylinder driver relays K1-Kn of other branches except the system branch and execute step seven;

[0021] Step seven: respectively determine whether the active discharge of the electric cylinder driver of other branches except the system branch is faulty, the branch driver active discharge of which is not faulty; the relay corresponding to the branch with fault is closed, and step eight is executed;

[0022] Step eight: system branch active discharge.

[0023] The serious fault in step three refers to that all branch electric cylinder drivers cannot work.

[0024] In the process of enabling the discharge resistor to discharge the bus capacitor in step three, the system bus voltage discharge is completed when the bus voltage is less than the safety voltage.

[0025] The set voltage in step five is 300V.

[0026] The system branch in step six uses different branch electric cylinder drivers as the system branch in a cycle each time the power is turned off.

[0027] In the process of active discharge of the branch driver without fault in step seven, the bus discharge of each driver is completed when the bus voltage of each branch driver without fault is less than the safety voltage.

[0028] In step eight, during the active discharge process of the system branch, when the discharge of the system bus voltage is less than the safe voltage, the discharge of the system bus voltage is completed.

[0029] The safe voltage is 60V.

[0030] The beneficial effects of the present application are as follows: the active discharge redundancy method for the crane reserves a branch driver as a system branch for discharging the system bus, the system branch cyclically uses different branches at each power-off, stores branch information, and uses the system branch Km to discharge when the remaining branches have faults and cannot discharge. When the system branch discharges, in order to reduce the discharge amount of the system branch driver, the DCDC and PTC are used to pre-discharge the bus capacitor, and after the voltage is reduced to the working range voltage, the driver is actively discharged, the time of the driver active discharge is reduced, and the heat of the branch cylinder driver is reduced. When the vehicle has a serious fault, the bleed resistor is used to release the bus voltage, so that the discharge can be realized in the fault state. The active discharge redundancy device and system of the present application change the loop of the high-voltage system by controlling the high-voltage relay of the high-voltage distribution system, so that different active discharge methods are used to quickly release the bus voltage in different states of the vehicle. BRIEF DESCRIPTION OF DRAWINGS

[0031] Figure 1 It is a schematic diagram of the active discharge redundancy device in the prior art;

[0032] Figure 2 It is a schematic diagram of the corresponding active discharge redundancy device of the present application;

[0033] Figure 3 It is a flowchart of the active discharge redundancy method for the crane of the present application. DETAILED DESCRIPTION

[0034] The embodiments of the present application will be further described below with reference to the accompanying drawings.

[0035] Referring to Figure 2 The device corresponding to the active discharge redundancy method for the crane of the present application adds a bleed resistor compared with the prior art, and the high-voltage distribution system is connected with the bleed resistor through the relay Kz. The drivers of the electric cylinders and the high-voltage accessories are connected with the high-voltage distribution system through the high-voltage relay, and various connection configurations of the high-voltage system can be realized, and the high-voltage loop can be flexibly configured.

[0036] Referring to Figure 3 The active discharge redundancy method for the crane of the present application is specifically as follows:

[0037] Step one: after the high-voltage distribution system receives the vehicle power-off command, the electric cylinders and high-voltage accessories are stopped;

[0038] Step two: disconnect the relay Kbat connected between the power battery and the high voltage distribution system;

[0039] Step three: determine whether the drive system of the whole vehicle has a serious fault, if yes, enable the discharge resistor to discharge the bus capacitor; if no, execute step four;

[0040] Step four: determine whether the DCDC and PTC have all faults, if no, enable the DCDC and PTC in circulation and execute step five; if yes, execute step six;

[0041] Step five: determine whether the bus voltage is less than 300V, if no, continue to enable the DCDC and PTC; if yes, cancel the enable of the DCDC and PTC and execute step six;

[0042] Step six: select one branch of the electric cylinder driver without fault as the system branch, close the system branch relay Km and execute step eight; at the same time, disconnect the electric cylinder driver relays K1-Kn of other branches except the system branch and execute step seven;

[0043] Step seven: respectively determine whether the active discharge of the electric cylinder driver of other branches except the system branch has a fault, the active discharge of the branch driver without fault; the relay corresponding to the branch with fault is closed, and step eight is executed.

[0044] Step eight: the active discharge of the system branch.

[0045] The serious fault in step three refers to that all branch electric cylinder drivers cannot work.

[0046] In the process of enabling the discharge resistor to discharge the bus capacitor in step three, the discharge of the system bus voltage is completed when the bus voltage is less than the safety voltage.

[0047] The system branch in step six uses different branch electric cylinder drivers as the system branch in circulation each time the power is turned off.

[0048] In the process of the active discharge of the branch driver without fault in step seven, the bus discharge of each driver is completed when the bus voltage of each branch driver without fault is less than the safety voltage.

[0049] In the process of the active discharge of the system branch in step eight, the discharge of the system bus voltage is completed when the bus voltage of the system branch is less than the safety voltage.

[0050] The relay of the application can also be replaced by a power switch. The application can be applied to other high voltage systems of engineering machinery.

[0051] The application reserves a certain branch driver of K1-Kn as a system branch Km to discharge the system bus voltage, and the system branch adopts different branches as Km in each power-off cycle, and stores the information of each branch Km used in the controller.

[0052] When the remaining branches have faults and cannot be discharged, the relay corresponding to the fault branch is closed and the system branch Km is used for discharging. When the system branch is discharged, if the DCDC and PTC are fault-free, in order to reduce the discharge amount of the system and the branch driver, the DCDC and PTC are used to pre-discharge the bus capacitor, and the voltage is reduced to the minimum value of the working range voltage, and then the system branch is actively discharged. When the vehicle has a serious fault, the discharge resistor is used to release the bus voltage.

Claims

1. An active discharge redundancy method for a crane, characterized in that: Specifically: Step 1: After the high-voltage power distribution system receives the vehicle power-off command, the electric cylinder and high-voltage accessories shut down; Step 2: Disconnect the relay Kbat connecting the power battery and the high-voltage power distribution system; Step 3: Determine whether the vehicle's drive system has a serious fault. If so, enable the bleeder resistor to discharge the bus capacitor; if not, proceed to step 4. Step 4: Determine whether both the DCDC and PTC are faulty. If not, cycle to enable the DCDC and PTC and proceed to step 5. If so, proceed to step 6. Step 5: Determine whether the bus voltage is less than the set voltage. If not, continue to cycle to enable DCDC and PTC. If so, cancel DCDC and PTC and execute step 6. Step 6: Select a branch circuit with no faults in the electric cylinder driver as the system branch circuit, close the system branch relay Km and proceed to step 8; at the same time, disconnect the electric cylinder driver relays K1-Kn in other branches except the system branch circuit and proceed to step 7; Step 7: Determine whether the active discharge of the electric cylinder drivers of other branches except the system branch is faulty. The drivers of the branches without faults actively discharge. The relays corresponding to the branches with faults are closed, and step 8 is executed. Step 8: Active discharge of system branches.

2. The active discharge redundancy method for a crane according to claim 1, characterized in that: The serious fault described in step 3 means that all branch electric cylinder drivers cannot work.

3. The active discharge redundancy method for a crane according to claim 1, characterized in that: During the process of discharging the bus capacitor by enabling the discharge resistor as described in step 3, when the bus voltage is discharged to be lower than the safety voltage, the system bus voltage discharge is completed.

4. The active discharge redundancy method for a crane according to claim 1, characterized in that: The set voltage in step 5 is 300V.

5. The active discharge redundancy method for a crane according to claim 1, characterized in that: The system branches described in step 6 will cyclically use different branch electric cylinder drivers as system branches each time the power is turned off.

6. The active discharge redundancy method for a crane according to claim 1, characterized in that: In step seven, during the active discharge process of the branch drivers without faults, when the voltage of each bus of the branch drivers without faults is lower than the safety voltage, the discharge of each driver bus is completed.

7. The active discharge redundancy method for a crane according to claim 1, characterized in that: In step eight, during the active discharge process of the system branch, when the system branch bus voltage is discharged to be lower than the safety voltage, the system bus voltage discharge is completed.

8. The active discharge redundancy method for a crane according to claim 3, 6 or 7, characterized in that: The safety voltage is 60V.

Images