WO2024051201A1

WO2024051201A1 - Control system for downhill working condition, and elevated work vehicle

Info

Publication number: WO2024051201A1
Application number: PCT/CN2023/093829
Authority: WO
Inventors: 任会礼; 钟懿; 张斌; 朱后; 熊路; 杨存祥; 沈裕强
Original assignee: 湖南中联重科智能高空作业机械有限公司
Priority date: 2022-09-07
Filing date: 2023-05-12
Publication date: 2024-03-14

Abstract

A control system for a downhill working condition, and an elevated work vehicle. The control system (1) comprises: a voltage measurement apparatus (10), which is used for measuring a direct-current bus voltage of a driver; a first current capture apparatus (20), which is used for capturing a feedback current delivered by the driver; a first switch apparatus (30), which is used for conducting a first circuit in which the first current capture apparatus (20) is located; and a control apparatus (40), which is used for conducting the first circuit by controlling the first switch apparatus (30) when the direct-current bus voltage is equal to or greater than a first preset voltage, such that the first current capture apparatus (20) captures the feedback current. The system can intervene in a control strategy to reduce a direct-current bus voltage of a driver by means of capturing a feedback current, so as to prevent the braking torque from becoming smaller, thereby effectively reducing the risk of downhill stalling.

Description

Control systems and aerial work vehicles for downhill conditions

Cross-references to related applications

This application claims the rights and interests of Chinese patent applications 202211091407.0, 202211090792.7, and 202211090793.1 submitted on September 7, 2022. The contents of this application are incorporated herein by reference.

Technical field

The invention relates to the technical field of engineering machinery, and specifically to a control system for downhill working conditions and an aerial work vehicle.

Background technique

The driving system of electric-driven aerial work vehicles (self-propelled) usually does not have service brakes. Its driving deceleration and parking rely on energy feedback regenerative braking technology, and parking relies on electromagnetic braking or hydraulic braking. There is a risk in this braking method: when going downhill, if the regenerative braking voltage exceeds the protection voltage of the driver, the braking torque will be limited (that is, the strength of the regenerative braking will be weakened), thereby putting the aerial work vehicle at risk of stalling. At this time, if the vehicle is stopped via the emergency stop switch, the parking brake will directly hold the brake, forcing the aerial work vehicle to slide. On the one hand, high-speed brakes cause greater damage to the brakes; on the other hand, the braking distance may become longer.

Contents of the invention

The object of the present invention is to provide a control system and aerial work vehicle for downhill working conditions, which can control when the DC bus voltage exceeds the first preset voltage (for example, a voltage smaller than the protection voltage of the driver) (i.e., The intervention control strategy (before overspeeding occurs on downhill slopes) reduces the DC bus voltage of the drive by capturing the feedback current, thereby preventing the braking torque from becoming smaller, thereby effectively suppressing the risk of stalling on downhill slopes.

In order to achieve the above object, a first aspect of the present invention provides a control system for downhill working conditions. The control system includes: a voltage detection device for detecting the DC bus voltage of the driver; a first current capture device for Capture the feedback current delivered by the driver; a first phase-opening device for conducting the first circuit where the first current capturing device is located; and a control device for when the DC bus voltage is equal to or greater than the first preset If the voltage is set, the first circuit is turned on by controlling the first phase-opening device, so that the feedback current is captured by the first current capturing device.

Preferably, the first preset voltage is less than the protection voltage of the driver.

Preferably, the first current capturing device is an energy storage device and/or an energy consumer.

Preferably, when the first current capture device is the energy storage device, the control device is also configured to control the current capture device when the DC bus voltage is less than or equal to the second preset voltage. The first phase-opening device is used to conduct the first circuit to power the driver from the energy storage device, wherein the first preset voltage is greater than the second preset voltage.

Preferably, the control system further includes: a second current capturing device; and a second phase opening device for conducting the second circuit where the second current capturing device is located.

Preferably, the second current capturing device is an energy storage device and/or an energy consumer.

Preferably, in the case where the first current capture device is the energy consumer and the second current capture device is the energy storage device, the control device is further configured to perform the following operations: when powered on , by controlling the second phase-opening device to conduct the second circuit to precharge the energy storage device from the battery; and when the DC bus voltage is less than or equal to the second preset voltage Next, the second circuit is turned on by controlling the second phase-opening device to power the driver from the energy storage device, wherein the first preset voltage is greater than the second preset voltage.

Preferably, when the second phase-opening device includes a first contactor, a resistor and a second contactor, the second circuit includes: the first contactor and the resistor connected in series. the first subcircuit in; and the second subcircuit in which the second contactor is located, wherein both the first contactor and the resistor are connected in parallel with the second contactor, correspondingly, the The control device for conducting the second circuit by controlling the second phase-opening device to precharge the energy storage device from the battery includes: controlling the first contactor to close and the third The two contactors are disconnected to conduct the first sub-circuit to precharge the energy storage device by the battery, and the control device is used to conduct the second phase-opening device by controlling the second open-phase device. The second circuit to power the driver from the energy storage device includes: conducting the second sub-circuit by controlling the first contactor to open and the second contactor to close, so as to power the driver from the energy storage device. An energy storage device supplies the drive.

Preferably, the second preset voltage is greater than the minimum operating voltage of the driver.

Preferably, when the first current capturing device is the energy storage device, the control device is further configured to, when the energy storage device is in a saturated state, by controlling the first open phase A device is provided to cut off the first circuit, and to turn on the second circuit by controlling the second phase-opening device, so that the feedback current is captured by the second current capturing device.

Preferably, the first phase opening device is a first high frequency phase opening, and the second phase opening device is a second high frequency phase opening.

Preferably, the first high-frequency open phase and the second high-frequency open phase are field effect transistors.

Preferably, the control device for turning on the first circuit by controlling the first phase-opening device includes: turning on the first circuit by controlling a duty cycle of the first high-frequency phase-opening device. , to control the speed at which the feedback current is captured by the first current capturing device, and the control device is used to conduct the second circuit by controlling the second phase-opening device including: by controlling the first Two high-frequency open-phase duty cycles are used to conduct the second circuit to control the speed at which the feedback current is captured by the second current capture device.

Through the above technical solution, the present invention creatively first detects through the voltage detection device The DC bus voltage of the driver; then the feedback current delivered by the driver is captured through the first current capture device; and then the control device controls the first DC bus voltage when the DC bus voltage is equal to or greater than the first preset voltage. A phase opening device conducts the first circuit to capture the feedback current by the first current capturing device. Therefore, the present invention can intervene in the control strategy when the DC bus voltage exceeds the first preset voltage (for example, a voltage smaller than the protection voltage of the driver) (that is, before downhill overspeed occurs), and reduces the voltage of the driver by capturing the feedback current. The DC bus voltage can prevent the braking torque from becoming smaller, thereby effectively suppressing the risk of stalling on downhill slopes.

A second aspect of the present invention provides an aerial work vehicle, which includes: the control system for downhill working conditions.

Preferably, the aerial work vehicle further includes: a parking brake; and a driver for controlling the parking brake to brake when the rotational speed of the electric motor is less than a preset rotational speed.

Other features and advantages of the present invention will be described in detail in the detailed description that follows.

Description of the drawings

The drawings are used to provide a further understanding of the present invention and constitute a part of the specification. They are used to explain the present invention together with the following specific embodiments, but do not constitute a limitation of the present invention. In the attached picture:

Figure 1A is a schematic diagram of a control system for downhill conditions provided by an embodiment of the present invention;

Figure 1B is a schematic diagram of a control system for downhill conditions provided by an embodiment of the present invention;

Figure 2 is a schematic diagram of a driving system including a control system provided by an embodiment of the present invention;

Figure 3 is a schematic diagram of a control system for downhill conditions provided by an embodiment of the present invention;

Figure 4 is a schematic diagram of a control system for downhill conditions provided by an embodiment of the present invention;

Figure 5 is a schematic diagram of a control system for downhill conditions provided by an embodiment of the present invention; and

Figure 6 is a schematic diagram of a control system for downhill conditions provided by an embodiment of the present invention.

Detailed ways

Specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings. It should be understood that the specific embodiments described here are only used to illustrate and explain the present invention, and are not intended to limit the present invention.

Before introducing specific embodiments of the present invention, two concepts will be briefly explained.

Regenerative braking: When an electric vehicle brakes, the (traveling) motor can be controlled to operate as a generator, thereby converting the vehicle's kinetic or potential energy into electrical energy and storing it in the energy storage module.

Feedback current: During the regenerative braking process, the driver converts the electric energy generated by the (walking) motor into a current that can be used by the energy storage module or other energy-consuming components. This current is called feedback current.

FIG. 1A is a schematic diagram of a control system (ie, safety protection device) for downhill conditions provided by an embodiment of the present invention. As shown in Figure 1A, the control system 1 may include: a voltage detection device 10 for detecting the DC bus voltage of the driver; a first current capture device 20 for capturing the feedback current delivered by the driver; a first open phase The device 30 is used to conduct the first circuit in which the first current capturing device 20 is located; and the control device 40 is used to conduct the first circuit when the DC bus voltage is equal to or greater than the first preset voltage. The first phase-opening device 30 is controlled to conduct the first circuit, so that the first current capturing device 20 captures the feedback current.

When the aerial work vehicle goes downhill, the motor works in the generator state to keep the vehicle speed constant. At this time, the driver will generate a relatively high feedback electromotive force. Under normal circumstances, the driver will charge the battery, and the feedback electromotive force will not exceed the driver protection voltage.

The inventor's research found that during the operation of the aerial work vehicle, if the battery cannot be charged (battery is fully charged, battery power map (Map) limit, line failure, battery management system (BMS) failure, etc.), the feedback electromotive force will quickly reach the driver protection voltage. In order to prevent power electronic devices from being destroyed by high voltage, the driver reduces the feedback braking intensity, resulting in insufficient braking torque, the vehicle speed may become faster and faster, and there is a risk of the equipment losing control. If the operator uses the speed control handle to slow down at this time, the driver will not be able to achieve the deceleration effect due to the limited feedback braking strength of the driver. The driver will control the parking brake to apply the brake directly after a certain period of time (usually 5 seconds). If the operator stops the vehicle by opening the emergency stop at this time, the parking brake will directly hold the brake, forcing the equipment to slide. Both situations force the parking brake to apply the brakes at high speed. This high-speed brake braking method, on the one hand, causes greater damage to the brakes, causing the risk of the aerial work vehicle being unable to park on a slope; on the other hand, sliding may cause the braking distance to become longer and the lateral stability to deteriorate, making it difficult for aerial work vehicles to stop. The car is at risk of collision and skidding.

For example, when going downhill, the battery system may neither be able to supply power to the driver 2 and the motor 100 nor be charged. At this time, as shown in Figure 2, the vehicle controller (VCU) 90 and the battery management system (BMS) powered by the battery 110 can still operate normally. After receiving the status information provided by the BMS and performing fault diagnosis, the VCU 90 The parking instruction and warning information are issued, and the relay K1 that controls the enablement of driver 2 is still in the closed state. As a result, the motor 100 enters the regenerative braking state from the electric state. The electric energy generated by the regenerative braking can maintain the normal operation of the driver 2, and It is much greater than the energy consumption required by drive 2 for normal operation. Since the battery cannot be charged, the DC bus voltage of drive 2 will rise rapidly (i.e. the vehicle will stall when going downhill).

Therefore, when the aerial work vehicle is running, whether the battery is fully charged, the limit of the battery power map (Map), or battery failure, etc., the DC bus voltage of the driver may increase, causing the vehicle to go down. Slope stall.

Wherein, the first preset voltage is smaller than the protection voltage of the driver. If the protection voltage of the driver is 100V, the first preset voltage can be set to be less than 100V (for example, the first preset voltage is 95V).

The voltage detection device 10 may be a voltmeter 11, as shown in FIG. 3 .

Wherein, the first phase opening device 30 may be a first high frequency phase opening 31, as shown in FIG. 3 . Further, the first high-frequency open phase 31 may be a field effect transistor (for example, MoS transistor). Specifically, the control device 40 is used to conduct the first circuit by controlling the first phase-opening device 30 including: controlling the duty cycle of the first high-frequency phase-opening device 31 to conduct the first circuit. A first circuit to control the speed at which the feedback current is captured by the first current capturing device 20 .

Wherein, the control device 40 is a central processing unit (CPU) 41, as shown in Figure 3 or Figure 4 .

Specifically, when the DC bus voltage displayed by the voltmeter 11 is equal to or greater than the first preset voltage (for example, 95V), the CPU 41 controls the first high-frequency open phase by controlling the duty cycle of the first high-frequency open phase 31. The current capture device 20 (eg, energy storage device and/or energy consumer) captures the feedback current to control the speed at which the first current capture device 20 absorbs the feedback energy, thereby controlling the feedback energy absorbed by the first current capture device 20, thereby enabling The DC bus voltage of the control driver (that is, the feedback voltage) is lower than the protection voltage of the driver. At this time, since the driver will not limit the intensity of feedback braking, the speed of the aerial work vehicle can be controlled slower and slower.

When an electric vehicle stalls downhill, mechanical brakes are usually used to absorb the change in gravitational potential energy on the downhill slope. However, aerial work vehicles do not have mechanical brakes and can only rely on battery charging for absorption. The absorption mode of the current capture device designed in this plan solves the problem of battery system failure, etc. The reason cannot be absorbed. By stabilizing the DC bus voltage, it not only solves the problem of the driver losing power due to battery system failure and other reasons, but also prevents the driver from causing an overvoltage alarm due to excessive feedback braking electromotive force.

The following will respectively describe the first type of embodiment (the first current capturing device 20 is an energy storage device, for example, the capacitor 21 in FIG. 3) and the second type of embodiment (the first current capturing device 20 is an energy consumer). , for example, the angle of the resistor 25) in Figure 5 explains and illustrates the control system in detail respectively.

First type of embodiment

The first current capture device 20 may be an energy storage device. The energy storage device may be a capacitor 21 (as shown in Figure 3) or a battery.

Specifically, when the DC bus voltage displayed by the voltmeter 11 is equal to or greater than the first preset voltage (that is, there is a risk of stalling), the CPU 41 controls the duty cycle of the first high-frequency open phase 31 to conduct the circuit where the capacitor 21 is located. , to control the speed at which the feedback braking energy is absorbed by the capacitor, thereby controlling the feedback energy absorbed by the capacitor, thereby stabilizing the DC bus voltage to prevent it from exceeding the protection voltage. At this time, since the driver does not limit the intensity of regenerative braking (that is, it can provide sufficient braking torque), the corresponding vehicle speed becomes slower and slower, thereby avoiding the risk of stalling.

That is to say, when there is a risk of stalling, in this embodiment, the energy storage capacitor absorbs the feedback braking energy to stabilize the DC bus voltage.

When an electric vehicle stalls downhill, mechanical brakes are usually used to absorb the change in gravitational potential energy on the downhill slope. However, aerial work vehicles do not have mechanical brakes and can only rely on battery charging for absorption. The absorption method of the energy storage device designed in this embodiment solves the problem of failure of the battery system to absorb energy due to failure and other reasons. By stabilizing the DC bus voltage, it not only solves the problem of the driver losing power due to battery system failure and other reasons, but also prevents the driver from causing an overvoltage alarm due to excessive feedback braking electromotive force.

In the above embodiment, when the DC bus voltage displayed by the voltmeter 11 is equal to or greater than the first preset voltage (ie, there is a risk of stalling), the capacitor absorbs the feedback braking energy, thereby controlling the DC bus voltage of the driver (ie, there is a risk of stalling). Feedback voltage) is lower than the driver's protection voltage. At this time, since the driver will not limit the intensity of feedback braking, the speed of the aerial work vehicle can be controlled slower and slower. However, after the DC bus voltage decreases (that is, the vehicle speed decreases), the DC bus voltage may be lower than the minimum operating voltage of the driver, causing the parking brake to directly apply the brake, which will cause a certain degree of damage to the parking brake.

Embodiment 1

In view of the above defects, in the first embodiment, after the DC bus voltage decreases (that is, the vehicle speed decreases), the feedback braking energy absorbed by the energy storage device (such as the capacitor 21) can also be used to supply power to the driver, thereby avoiding the control of the driver. The parking brake directly applies the brake.

In the case where the first current capturing device 20 is the energy storage device, the control device is also configured to, when the DC bus voltage is less than or equal to a second preset voltage, by controlling the third A phase-opening device conducts the first circuit to power the driver from the energy storage device.

Wherein, the first preset voltage is greater than the second preset voltage.

Wherein, the second preset voltage is greater than the minimum operating voltage of the driver.

In practical applications, the second preset voltage can be reasonably set according to specific conditions, and it can be slightly larger than the minimum operating voltage (ie, the lowest voltage when the driver operates normally).

Specifically, the CPU 41 controls the duty cycle of the first high-frequency open phase 31 to turn on the circuit where the capacitor 21 is located to control the speed at which the capacitor absorbs feedback braking energy, thereby controlling the feedback energy absorbed by the capacitor. When the DC bus voltage decreases (that is, the vehicle speed decreases), when the DC bus voltage displayed by the voltmeter 11 is less than or equal to the second preset voltage, the first high-frequency phase opening 31 (which is equivalent to contactor) to conduct the circuit where the capacitor 21 is located, so that the capacitor 21 supplies power to the driver 2, thereby smoothly reducing the corresponding vehicle speed. When the 100 rpm of the motor is lower than a certain value (such as 30 rpm), the parking brake Actuator holding brake.

Embodiment 2

The control system may further include: a second current capturing device 20'; and a second phase opening device 30' for conducting the second circuit where the second current capturing device 20' is located, as shown in Figure 1B.

Wherein, the second current capturing device may be an energy consumer (for example, the resistor 50 in FIG. 3) and/or an energy storage device (for example, the capacitor 24 in FIG. 5); and the second phase opening device may be is the second high-frequency open phase 32 (which may be a field effect transistor, that is, a MoS transistor), as shown in FIG. 3 .

In the case where the first current capturing device 20 is the energy storage device, the control device is further configured to control the first phase-opening device when the energy storage device is in a saturated state. The first circuit is turned off, and the second circuit is turned on by controlling the second phase-opening device, so that the feedback current is captured by the second current capturing device.

Specifically, when the capacitor 21 is in a saturated state, the first circuit is cut off by controlling the first high-frequency open phase 31 , and the duty cycle of the second high-frequency open phase 32 is controlled by to conduct the second circuit in which it is located to control the speed at which the resistor 50 captures the feedback current, thereby controlling the feedback energy absorbed by the resistor, as shown in FIG. 3 . Therefore, the resistor 50 is activated only after the energy storage capacitor is saturated to consume excess feedback braking energy.

Second type of embodiment

The first current capture device 20 may be an energy consumer. The energy consumer may be a resistor 25 (as shown in Figure 4) or the like.

Specifically, when the DC bus voltage displayed by the voltmeter 11 is equal to or greater than the first preset voltage (that is, there is a risk of stalling), the CPU 41 controls the duty cycle of the first high-frequency open phase 31 to turn on the circuit where the resistor 25 is located. , to control the feedback braking energy consumed by resistor 25 speed, thereby controlling the feedback energy absorbed by the resistor, thereby stabilizing the DC bus voltage to prevent it from exceeding the protection voltage. At this time, since the driver does not limit the intensity of regenerative braking, the corresponding vehicle speed becomes slower and slower, thereby avoiding the risk of stalling.

Embodiment 3

Wherein, the second current capturing device may be an energy consumer (for example, the resistor 50 in FIG. 3) and/or an energy storage device (for example, the capacitor 24 in FIG. 5); and the second phase opening device may be is the second high-frequency open phase 32 (which may be a field effect transistor, that is, a MoS transistor).

When the first current capture device 20 is the energy consumer (eg, resistor 25 in FIG. 5 ) and the second current capture device 20 ′ is the energy storage device (eg, capacitor 24 in FIG. 5 ), the control device is also used to perform the following operations: when powered on, by controlling the second phase-opening device 30' to conduct the second circuit to store energy from the battery. The energy storage device is precharged; and when the DC bus voltage is less than or equal to the second preset voltage, the second circuit is turned on by controlling the second phase-opening device 30' to use the energy storage device Power the drive.

Wherein, the first preset voltage is greater than the second preset voltage.

In view of the defects mentioned in the first embodiment, an energy storage device, an energy consumer and a corresponding circuit are added in the third embodiment to precharge the energy storage device when power is turned on. Therefore, after the DC bus voltage decreases (that is, the vehicle speed decreases), the energy precharged by the energy storage device can be used to supply power to the driver, thereby preventing the parking brake controlled by the driver from directly holding the brake.

When the second phase-opening device 30' is the second high-frequency phase-opening device 32, the control The means for conducting the second circuit by controlling the second phase-opening device 30' to precharge the energy storage device from the battery includes: by controlling the second high-frequency phase-opening device 32 The second circuit is turned on according to a duty cycle to control the speed at which the energy storage is precharged by the battery.

The second phase-opening device 30' may be a second high-frequency phase-opening device 32 or a contactor (as shown in Figure 5). Specifically, the second high-frequency open phase 32 may be a field effect transistor (ie, MoS transistor).

Specifically, taking the energy storage device as a capacitor 24 as an example for illustration, when powered on, the CPU 41 conducts the circuit in which it is located by controlling the duty cycle of the second high-frequency open phase 32, so that the circuit in which it is located is switched on. The battery precharges the capacitor 24 . Then, when the DC bus voltage displayed by the voltmeter 11 is equal to or greater than the first preset voltage (ie, there is a risk of stalling), the energy consumption resistor consumes the feedback braking energy, thereby controlling the DC bus voltage of the driver (ie, the feedback voltage ) is lower than the driver’s protection voltage. At this time, since the driver will not limit the intensity of feedback braking, the speed of the aerial work vehicle can be controlled slower and slower. Therefore, when the DC bus voltage displayed by the voltmeter 11 is less than or equal to the second preset voltage (that is, the feedback voltage is close to the minimum operating voltage of the driver), the CPU 41 controls the second high-frequency open phase 32 (which Equivalent to a contactor) to conduct the circuit in which it is located, so that the capacitor 24 supplies power to the driver 2 (as shown in Figure 5). Therefore, the capacitor 24 can provide assistance for the driver 2 to complete the braking process. Power supply (especially when the power system loses power). However, if the energy absorbed by the capacitor is insufficient, after the voltage decreases (that is, the vehicle speed decreases), the driver may cause a serious under-voltage alarm, and the parking brake will directly apply the brake.

That is to say, when powered on, the CPU 41 controls the duty cycle of the second high-frequency open phase 32 to complete the precharge of the energy storage capacitor 24 . The function of precharge is to provide backup energy to driver 2 to complete the deceleration process. When there is a risk of stalling, the energy consumption resistor 25 still absorbs the feedback braking energy to stabilize the DC bus voltage. After the voltage is reduced, the CPU controls the high-frequency phase opening to control the energy storage capacitor 24 to supply power to the driver, thereby smoothly reducing the corresponding vehicle speed. when When the motor speed is lower than a certain value (such as 30rpm), the parking brake is applied, as shown in Figure 5.

More specifically, as shown in FIG. 6 , when the second phase-opening device 30 ′ may include a first contactor 34 , a resistor 60 and a second contactor 35 , the second circuit may include: The first sub-circuit in which the first contactor 34 and the resistor 60 are connected in series; and the second sub-circuit in which the second contactor 35 is located, wherein both the first contactor 34 and the resistor 60 It is connected in parallel with the second contactor 35 .

Correspondingly, the control device 40 (for example, CPU 41) is used to conduct the second circuit by controlling the second phase opening device to precharge the energy storage device by the battery including: by Control the first contactor 34 to close and the second contactor 35 to open to conduct the first sub-circuit to precharge the energy storage device from the battery, and the control device 40 (for example, CPU 41) for conducting the second circuit by controlling the second phase-opening device to power the driver from the energy storage device includes: by controlling the first contactor 34 to open The second contactor 35 is closed to conduct the second sub-circuit to power the driver from the energy storage device.

Specifically, when the battery is powered on, the contactor 34 is controlled to close and the contactor 35 is disconnected to conduct the circuit in which it is located, so that the capacitor 24 is precharged by the battery. Then, when the DC bus voltage displayed by the voltmeter 11 is equal to or greater than the first preset voltage (ie, there is a risk of stalling), the energy consumption resistor consumes the feedback braking energy, thereby controlling the DC bus voltage of the driver (ie, the feedback voltage ) is lower than the driver’s protection voltage. At this time, since the driver will not limit the intensity of feedback braking, the speed of the aerial work vehicle can be controlled slower and slower. Therefore, when the DC bus voltage displayed by the voltmeter 11 is less than or equal to the second preset voltage (that is, the feedback voltage is close to the minimum operating voltage of the driver), the CPU 41 disconnects the contactor 35 by controlling the contactor 34 It is closed to conduct the circuit in which it is located, so that the capacitor 24 supplies power to the driver 2, as shown in FIG. 6 . Therefore, the capacitor 24 can provide auxiliary power for the driver 2 to complete the braking process (especially is when the power system loses power). Therefore, the function of precharging is to provide backup energy to the driver 2 to complete the deceleration process.

Compared with the embodiment shown in FIG. 5 , the embodiment shown in FIG. 6 uses a precharge circuit composed of a contactor 34 and a resistor 60 to precharge the capacitor 24 , and uses a contactor 35 to conduct the connection between the capacitor 24 and the capacitor 24 . Another circuit is used to power the driver using capacitor 24. Since the precharge circuit is separated from the power supply circuit, this embodiment can achieve a more reliable power supply purpose; and since this embodiment uses a simpler phase opening device (ie, contactor), it can use a simpler method to achieve control purposes.

Of course, in another embodiment, the first current capture device 20 can be configured as an energy storage device and an energy consumer, and the respective control functions of the energy storage device and the energy consumer can be controlled through corresponding control strategies. A phase-opening device is used to conduct the corresponding circuit to effectively capture the feedback current.

In one embodiment, the control system further includes: a digital-to-analog converter 70 for converting the analog signal of the DC bus voltage detected by the voltage detection device 10 into a digital signal, and converting the converted DC bus voltage into a digital signal. The digital signal is output to the control device 40, as shown in Figure 2.

The overspeed control method based on the DC bus voltage in each of the above embodiments can realize downhill control of the vehicle. The above control method has a stall protection function. It does not need to detect the speed of the vehicle or participate in speed control. Instead, it ensures that the driver can maximize the braking capacity of the motor by stabilizing the DC bus voltage, thereby preventing the vehicle from overspeeding. . Since the vehicle cannot speed, it is less likely to stall. Therefore, during the operation of the aerial work vehicle, whether the battery is fully charged, the limit of the battery power map (Map), or the DC bus voltage of the driver is high (or stalls downhill) caused by battery failure, etc. Overspeed control based on DC bus voltage is suppressed from the source, thereby effectively preventing the risk of stalling on downhill slopes.

To sum up, the present invention creatively first detects the DC bus voltage of the driver through the voltage detection device; then captures the feedback current delivered by the driver through the first current capture device; and then uses the control device to detect the DC bus voltage when the DC bus voltage is equal to or greater than In the case of the first preset voltage, the first circuit is turned on by controlling the first phase-opening device, so that the feedback current is captured by the first current capturing device. Therefore, the present invention can intervene in the control strategy when the DC bus voltage exceeds the first preset voltage (for example, a voltage smaller than the protection voltage of the driver) (that is, before downhill overspeed occurs), and reduces the voltage of the driver by capturing the feedback current. The DC bus voltage can prevent the braking torque from becoming smaller, thereby effectively suppressing the risk of stalling on downhill slopes.

An embodiment of the present invention also provides an aerial work vehicle. The aerial work vehicle may include: the control system (ie, safety protection device) 1 for downhill conditions.

The aerial work vehicle may also include: a parking brake 120; and a driver 2 for controlling the parking brake 120 to brake when the rotational speed of the motor is less than a preset rotational speed.

In one embodiment, the aerial work vehicle may also include: a battery 80, a vehicle controller (VCU) 90, a motor 100, a reducer 130, wheels 140, a DC/DC converter 150, etc., as shown in Figure 2 . The battery 80 is configured with a battery management system (BMS), and the vehicle controller (VCU) 90 exchanges information with the BMS through the CAN bus. The VCU 90 can adjust the target speed of the electric motor 100 based on the battery status and fault information sent by the BMS.

Specifically, the control system for downhill conditions is used to capture the feedback current generated by regenerative braking. Since the driver 2 does not limit the intensity of the regenerative braking, the motor 100 can achieve control through the reducer 130 . The deceleration of the wheels 140 is controlled, whereby the vehicle speed becomes lower and lower. Moreover, when the rotation speed of the electric motor 100 is less than the preset rotation speed, the parking brake is controlled to perform braking to achieve parking. Therefore, in this embodiment, when the driving system fails, the method of first reducing the speed and then holding the brake can be adopted to reduce damage to the parking brake as much as possible. harm, thereby extending its lifespan.

The above embodiment can absorb the energy generated by feedback braking through the resistor/capacitor and control the vehicle speed reduction in a timely manner. When the feedback energy is insufficient, the energy storage capacitor is used to replenish the power in time to maintain the normal operation of the drive until it completely stops. This can ensure that the parking brake is not damaged by dynamic impact energy, can greatly reduce the probability of high-speed braking, is conducive to extending the life of the parking brake, and reduces the risk of parking on a slope, thereby achieving safer and more efficient parking. Reliable downhill.

For specific details and benefits of the aerial work vehicle provided by the embodiments of the present invention, please refer to the above description of the feedback current control device, and will not be described again here.

The preferred embodiments of the present invention are described in detail above with reference to the accompanying drawings. However, the present invention is not limited to the specific details of the above embodiments. Within the scope of the technical concept of the present invention, various simple modifications can be made to the technical solution of the present invention. These simple modifications all belong to the protection scope of the present invention.

In addition, it should be noted that the specific technical features described in the above-mentioned specific embodiments can be combined in any suitable manner as long as there is no contradiction. In order to avoid unnecessary repetition, various possible combinations are not further described in the present invention.

In addition, any combination of various embodiments of the present invention can also be carried out. As long as they do not violate the idea of the present invention, they should also be regarded as the disclosed content of the present invention.

Claims

A control system for downhill conditions, characterized in that the control system includes:

Voltage detection device, used to detect the DC bus voltage of the driver;

a first current capture device, configured to capture the feedback current delivered by the driver;

a first switching device for conducting the first circuit in which the first current capturing device is located; and

A control device configured to conduct the first circuit by controlling the first switching device to be captured by the first current capturing device when the DC bus voltage is equal to or greater than a first preset voltage. the feedback current.
The control system according to claim 1, wherein the first preset voltage is less than the protection voltage of the driver.
The control system according to claim 1, characterized in that the first current capturing device is an energy storage device and/or an energy consumer.
The control system according to claim 3, characterized in that, when the first current capturing device is the energy storage device, the control device is further configured to: when the DC bus voltage is less than or equal to the first In the case of two preset voltages, the first circuit is turned on by controlling the first switching device so that the energy storage device supplies power to the driver, wherein the first preset voltage is greater than the Second preset voltage.
The control system according to claim 3, characterized in that the control system further includes:

a second current capture device; and

The second switching device is used to conduct the second circuit in which the second current capturing device is located.
The control system according to claim 5, characterized in that the second current capturing device is an energy storage device and/or an energy consumer.
The control system according to claim 6, wherein when the first current capture device is the energy consumer and the second current capture device is the energy storage device, the control device Also used to do the following:

When powered on, the second circuit is turned on by controlling the second switching device to precharge the energy storage device by the battery; and

When the DC bus voltage is less than or equal to the second preset voltage, the second circuit is turned on by controlling the second switching device to power the driver from the energy storage device,

Wherein, the first preset voltage is greater than the second preset voltage.
The control system according to claim 7, wherein when the second switching device includes a first contactor, a resistor and a second contactor, the second circuit includes: the first contactor the first subcircuit in series with the resistor; and the The second subcircuit in which the second contactor is located, wherein both the first contactor and the resistor are connected in parallel with the second contactor,

Correspondingly, the control device for conducting the second circuit by controlling the second switching device to precharge the energy storage device from the battery includes: by controlling the first contactor to close Disconnecting the second contactor to conduct the first sub-circuit to precharge the energy storage device from the battery, and

The control device for conducting the second circuit by controlling the second switching device to power the driver from the energy storage device includes: controlling the first contactor to disconnect from the third contactor. The two contactors are closed to conduct the second sub-circuit so that the energy storage device supplies power to the driver.
The control system according to claim 4 or 7, characterized in that the second preset voltage is greater than the minimum operating voltage of the driver.
The control system according to claim 5, characterized in that, when the first current capturing device is the energy storage device, the control device is further configured to: when the energy storage device is in a saturated state, In this case, the first circuit is turned off by controlling the first switching device, and the second circuit is turned on by controlling the second switching device, so that the feedback is captured by the second current capturing device. current.
The control system of claim 10, wherein the first switching device is a first high-frequency switch, and the second switching device is a second high-frequency switch.
The control system according to claim 11, wherein the first high-frequency switch and the second high-frequency switch are field effect transistors.
The control system according to claim 11, wherein the control device is configured to conduct the first circuit by controlling the first switching device including: controlling a duty cycle of the first high-frequency switch. to turn on the first circuit to control the speed at which the feedback current is captured by the first current capture device, and

The control device for conducting the second circuit by controlling the second switching device includes: conducting the second circuit by controlling the duty cycle of the second high-frequency switch to control the second circuit by controlling the duty cycle of the second high-frequency switch. The second current capturing device captures the speed of the feedback current.
An aerial work vehicle, characterized in that the aerial work vehicle includes: a control system for downhill working conditions according to any one of claims 1-13.
The aerial work vehicle according to claim 14, characterized in that the aerial work vehicle further includes:

parking brake; and

A driver is used to control the parking brake to brake when the rotation speed of the electric motor is less than the preset rotation speed.