Control system in motor braking mode and unmanned charging vehicle

Abstract

The utility model discloses a control system in a motor braking mode and an unmanned charging vehicle, and the control system is characterized in that a first voltage output end of a DC power supply module is electrically connected with a first voltage input end of a motor control module and a first end of a braking current suppression module; a second voltage output end of the direct-current power supply module is electrically connected with a second voltage input end of the motor control module and a second end of the braking current suppression module respectively; the control signal output end of the motor control module is electrically connected with the control end of the braking current suppression module; the motor control module is used for controlling the motor to operate according to the direct-current voltage provided by the direct-current power supply module, and transmitting a braking current suppression control signal to the braking current suppression module when the motor is in a braking mode and detects that the direct-current voltage exceeds a preset threshold value; therefore, the braking current suppression module suppresses the braking current generated by the direct current side of the motor control module. According to the scheme, the situation that braking current is too large, and safe and stable operation of the whole vehicle is affected can be avoided.

Description

Technical Field

[0001] The utility model relates to the technical field of unmanned charging vehicles, and in particular to a control system in a motor braking mode and an unmanned charging vehicle. Background Art

[0002] When the charging vehicle is in braking mode, such as when passing a speed bump or a long downhill slope, the motor moves in the opposite direction (i.e., reverse rotation). The reverse movement of the motor generates a torque opposite to the forward movement (i.e., forward rotation), thereby generating braking. It can be understood that when the motor reverses, the direction of its internal magnetic field also changes, and according to electromagnetic induction, a reverse electromotive force and a reverse current are generated.

[0003] However, the current generated by the motor's reverse operation in braking mode is instantaneous and large, which can easily cause the motor controller to self-protect and enter a shutdown state, thereby causing the entire vehicle to stop driving and threatening the safety of the entire vehicle. Utility Model Content

[0004] The utility model provides a control system and an unmanned charging vehicle in a motor braking mode to suppress the braking current generated on the DC side of a motor control module, thereby preventing the motor control module from shutting down due to self-protection due to excessive braking current, thereby affecting the safe and stable operation of the entire vehicle.

[0005] In a first aspect, an embodiment of the utility model provides a control system in a motor braking mode, which is applied to an unmanned charging vehicle; the control system in the motor braking mode includes a DC power supply module, a motor control module, a braking current suppression module and a motor;

[0006] The first voltage output end of the DC power supply module is electrically connected to the first voltage input end of the motor control module and the first end of the brake current suppression module, and the second voltage output end of the DC power supply module is electrically connected to the second voltage input end of the motor control module and the second end of the brake current suppression module;

[0007] The control signal output terminal of the motor control module is electrically connected to the control terminal of the brake current suppression module, and the three-phase voltage output terminal of the motor control module is electrically connected to the motor;

[0008] The DC power supply module is used to provide a DC voltage to the motor control module;

[0009] The motor control module is used to control the operation of the motor according to the DC voltage, and transmit a braking current suppression control signal to the braking current suppression module through the control signal output terminal when the DC voltage is detected to exceed a preset threshold value when the motor is in a braking mode;

[0010] The braking current suppression module is used to suppress the braking current generated by the DC side of the motor control module when receiving the braking current suppression control signal.

[0011] Optionally, the braking current suppression module includes a braking current suppression unit, and the braking current suppression unit includes a braking resistor and a first switch component;

[0012] The first end of the braking resistor is electrically connected to the first voltage output end of the DC power supply module, and the second end of the braking resistor is electrically connected to the first end of the first switch component;

[0013] The second end of the first switch component is electrically connected to the second voltage output end of the DC power supply module;

[0014] The control end of the first switch assembly is electrically connected to the control signal output end of the motor control module;

[0015] The motor control module is used to transmit a braking current suppression control signal to the control end of the first switch component through the control signal output end when the motor is in a braking mode and detects that the DC voltage exceeds a preset threshold, so as to control the first switch component to be turned on.

[0016] Optionally, the first switch component is a MOS switch tube;

[0017] The first electrode of the MOS switch tube is electrically connected to the second end of the brake resistor, the second electrode of the MOS switch tube is electrically connected to the second voltage output end, and the gate of the MOS switch tube is electrically connected to the control signal output end of the motor control module.

[0018] Optionally, the resistance of the braking resistor is 1Ω and the power is 3kW.

[0019] Optionally, the braking current suppression module further includes a heat dissipation unit, and the heat dissipation unit is arranged close to the braking resistor;

[0020] The control signal output terminal of the motor control module includes a first control signal output terminal and a second control signal output terminal;

[0021] The first control signal output terminal is electrically connected to the control terminal of the first switch component, and the second control signal output terminal is electrically connected to the heat dissipation unit;

[0022] The motor control module is further configured to transmit a heat dissipation unit start-up control signal to the heat dissipation unit through the second control signal output terminal when the motor is in a braking mode and detects that the DC voltage exceeds a preset threshold.

[0023] Optionally, the heat dissipation unit includes a power supply component, a second switch component and a fan component;

[0024] The first end of the power supply assembly is electrically connected to the first end of the fan assembly, and the second end of the power supply assembly is electrically connected to the first end of the second switch assembly;

[0025] The second end of the fan assembly is electrically connected to the second end of the second switch assembly;

[0026] The second control signal output terminal of the motor control module is electrically connected to the control terminal of the second switch component.

[0027] Optionally, the second switch assembly is a contactor switch;

[0028] The first end of the contactor switch is electrically connected to the second end of the power supply assembly, the second end of the contactor switch is electrically connected to the second end of the fan assembly, and the control end of the contactor switch is electrically connected to the second control signal output end.

[0029] Optionally, the fan assembly includes a plurality of fans arranged in parallel.

[0030] Optionally, the DC power supply module includes a battery assembly and a DC-DC conversion unit; the DC-DC conversion unit is arranged in series between the battery assembly and the motor control module.

[0031] In a second aspect, an embodiment of the utility model provides an unmanned charging vehicle, including the control system in the above-mentioned motor braking mode.

[0032] The solution provided by the utility model is that the DC power supply module provides a DC voltage to the motor control module through the first voltage output terminal and the second voltage output terminal. However, when the unmanned charging vehicle brakes, the motor will reverse, thereby generating a reverse electromotive force and a reverse current, so that the voltage between the first voltage output terminal and the second voltage output terminal will increase instantaneously, and the current will also increase instantaneously. In this way, the motor control module can detect the DC voltage between the first voltage output terminal and the second voltage output terminal in real time, and then compare the DC voltage with the preset threshold value to determine whether the DC voltage exceeds the preset threshold value. If the DC voltage exceeds the preset threshold value, the motor control module will transmit a braking current suppression control signal to the braking current suppression module through the control signal output terminal, thereby controlling the braking current suppression module to start running, to suppress the braking current generated by the DC side of the motor control module, to avoid excessive braking current causing the motor control module to enter self-protection and shut down, thereby affecting the safe and stable operation of the entire vehicle.

[0033] It should be understood that the content described in this section is not intended to identify the key or important features of the embodiments of the utility model, nor is it intended to limit the scope of the utility model. Other features of the utility model will become easy to understand through the following description. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] In order to more clearly illustrate the technical solutions in the embodiments of the utility model or the prior art, the drawings required for use in the embodiments or the prior art descriptions are briefly introduced below. Obviously, although the drawings described below are some specific embodiments of the utility model, for those skilled in the art, the basic concepts of the device structure, driving method and manufacturing method disclosed and suggested by the various embodiments of the utility model can be expanded and extended to other structures and drawings. Undoubtedly, these should all be within the scope of the claims of the utility model.

[0035] Figure 1 A schematic diagram of the structure of a control system in a motor braking mode provided by an embodiment of the utility model;

[0036] Figure 2 A schematic diagram of the structure of another control system in a motor braking mode provided by an embodiment of the utility model;

[0037] Figure 3 A schematic diagram of the structure of a control system in a motor braking mode provided by an embodiment of the utility model;

[0038] Figure 4 A schematic diagram of the structure of a control system in a motor braking mode provided by an embodiment of the utility model;

[0039] Figure 5 A schematic diagram of the structure of a control system in a motor braking mode provided by an embodiment of the utility model;

[0040] Figure 6 A schematic diagram of the structure of a control system in another motor braking mode provided in an embodiment of the utility model. DETAILED DESCRIPTION

[0041] In order to make the purpose, technical solution and advantages of the utility model clearer, the following will refer to the drawings in the embodiments of the utility model to clearly and completely describe the technical solution of the utility model through the implementation method. Obviously, the described embodiments are part of the embodiments of the utility model, not all of the embodiments. Based on the basic concepts disclosed and suggested by the embodiments of the utility model, all other embodiments obtained by those skilled in the art are within the scope of protection of the utility model.

[0042] Figure 1A schematic diagram of a control system in a motor braking mode provided by an embodiment of the utility model is shown in FIG. Figure 1 As shown, the control system is applied to an unmanned charging vehicle, and the control system includes a DC power supply module 10, a motor control module 20, a braking current suppression module 30 and a motor M;

[0043] The first voltage output terminal V1 of the DC power supply module 10 is electrically connected to the first voltage input terminal X1 of the motor control module 20 and the first terminal of the braking current suppression module 30, respectively. The second voltage output terminal V2 of the DC power supply module 10 is electrically connected to the second voltage input terminal X2 of the motor control module 20 and the second terminal of the braking current suppression module 30, respectively. The control signal output terminal Y of the motor control module 20 is electrically connected to the control terminal C of the braking current suppression module 30, and the three-phase voltage output terminal of the motor control module 30 is electrically connected to the motor M. The DC power supply module 10 is used to provide a DC voltage to the motor control module 20. The motor control module 20 is used to control the operation of the motor M according to the DC voltage, and when the DC voltage is detected to exceed a preset threshold value when the motor M is in the braking mode, the braking current suppression control signal is transmitted to the braking current suppression module 30 through the control signal output terminal Y. The braking current suppression module 30 is used to suppress the braking current generated by the DC side of the motor control module 20 when receiving the braking current suppression control signal.

[0044] Among them, the voltage output by the DC power supply module 10 through the first voltage output terminal V1 and the second voltage output terminal V2 is a DC voltage, and the specific voltage value can be set according to actual conditions. For example, the voltage difference between the first voltage output terminal V1 and the second voltage output terminal V2 is 48V.

[0045] The motor control module 20 can be composed of a conventional converter and a controller electrically connected to the converter. It can be understood that the DC side of the converter is electrically connected to the first voltage output terminal V1 and the second voltage output terminal V2 of the DC power supply module 10, and the AC side of the converter is electrically connected to the motor M through the three-phase voltage output terminal. The controller electrically connected to the converter can control the operation of the converter and the operation of the motor, and can also process and analyze other collected parameter information. Exemplarily, the motor control module 20 may include a microcontroller unit (MCU).

[0046] The motor M may be any type of motor, which is not specifically limited here. For example, the motor M is a permanent magnet synchronous motor.

[0047] The specific value of the preset threshold can be adaptively set according to actual conditions and is not specifically limited here.

[0048] In this embodiment, the DC power supply module 10 provides a DC voltage to the motor control module 20 through the first voltage output terminal V1 and the second voltage output terminal V2. However, when the unmanned charging vehicle brakes, the motor M will reverse, thereby generating a reverse electromotive force and a reverse current, so that the voltage between the first voltage output terminal V1 and the second voltage output terminal V2 will increase instantly, and the current will also increase instantly. In this way, the motor control module 20 can detect the DC voltage between the first voltage output terminal V1 and the second voltage output terminal V2 in real time, and then compare the DC voltage with the preset threshold to determine whether the DC voltage exceeds the preset threshold. If the DC voltage exceeds the preset threshold, the motor control module 20 will transmit a braking current suppression control signal to the braking current suppression module 30 through the control signal output terminal Y, thereby controlling the braking current suppression module 30 to start running, to suppress the braking current generated on the DC side of the motor control module 20, to avoid excessive braking current causing the motor control module to enter self-protection and shut down, thereby affecting the safe and stable operation of the entire vehicle.

[0049] It should be noted that the braking current suppression module 30 can quickly consume excessive braking current to ensure the stability of the DC voltage.

[0050] Optional, Figure 2 A schematic diagram of the structure of another control system in a motor braking mode provided by an embodiment of the utility model, such as Figure 2 As shown, the braking current suppression module 30 includes a braking current suppression unit 31, and the braking current suppression unit 31 includes a braking resistor R and a first switch component K1. The first end of the braking resistor R is electrically connected to the first voltage output terminal V1 of the DC power supply module 10, and the second end of the braking resistor R is electrically connected to the first end of the first switch component K1. The second end of the first switch component K1 is electrically connected to the second voltage output terminal V2 of the DC power supply module 10. The control end of the first switch component K1 is electrically connected to the control signal output terminal Y of the motor control module 20. The motor control module 20 is used to transmit a braking current suppression control signal to the control end of the first switch component K1 through the control signal output terminal Y when the DC voltage exceeds a preset threshold when the motor M is in the braking mode, so as to control the first switch component K1 to be turned on.

[0051] Specifically, when the unmanned charging vehicle brakes, the motor control module 20 can detect the DC voltage between the first voltage output terminal V1 and the second voltage output terminal V2 in real time, and then compare the DC voltage with the preset threshold value. If the DC voltage exceeds the preset threshold value, the motor control module 20 will transmit a braking current suppression control signal to the control end of the first switch component K1 through the control signal output terminal Y, thereby controlling the first switch component K1 to be turned on, so that a current loop is formed between the first voltage output V1 and the second voltage output terminal V2 through the braking resistor R and the turned-on first switch component K1. In this way, the braking resistor R can quickly consume the large braking current generated at this time, so that the DC voltage between the first voltage output V1 and the second voltage output terminal V2 quickly stabilizes within the normal range, thereby ensuring the stable operation of the motor control module 20 and further ensuring the stable operation of the entire vehicle.

[0052] In an optional embodiment, continue to refer to Figure 2 The first switch component K1 is a MOS switch tube, a first pole of the MOS switch tube is electrically connected to the second end of the braking resistor, a second pole of the MOS switch tube is electrically connected to the second voltage output end, and a gate of the MOS switch tube is electrically connected to the control signal output end of the motor control module.

[0053] Specifically, the type of the MOS switch tube can be N-type or P-type, which is not specifically limited here. It can be understood that when the type of the MOS switch tube is N-type, the braking current suppression control signal that controls the conduction of the MOS switch tube is a high level, and when the type of the MOS switch tube is P-type, the braking current suppression control signal that controls the conduction of the MOS switch tube is a low level.

[0054] It should be noted that the first switch component K1 may also be other switch devices, as long as the switch component has a high switching rate.

[0055] Optional, continue to refer to Figure 2 , the resistance of the braking resistor R is 1Ω and the power is 3kW.

[0056] Specifically, the resistance of the braking resistor R determines the consumption rate of the braking current. The smaller the resistance, the faster the consumption rate of the braking current. In this embodiment, the resistance of the braking resistor R is set to 1Ω and the power is 3kW, which can ensure that the braking current is quickly suppressed and prevent the braking resistor R from being burned out due to low power.

[0057] Optional, Figure 3 A schematic diagram of the structure of a control system in a motor braking mode provided by an embodiment of the utility model is shown as follows: Figure 3As shown, the braking current suppression module 30 also includes a heat dissipation unit 32, and the heat dissipation unit 32 is arranged near the braking resistor R. The control signal output terminal Y of the motor control module 20 includes a first control signal output terminal Y1 and a second control signal output terminal Y2. The first control signal output terminal Y1 is electrically connected to the control terminal of the first switch component K1, and the second control signal output terminal Y2 is electrically connected to the heat dissipation unit 32. The motor control module 20 is also used to transmit a heat dissipation unit start control signal to the heat dissipation unit 32 through the second control signal output terminal Y2 when the motor M is in the braking mode and detects that the DC voltage exceeds a preset threshold.

[0058] Specifically, when the unmanned charging vehicle brakes, the motor control module 20 can detect the DC voltage between the first voltage output terminal V1 and the second voltage output terminal V2 in real time, and then compare the DC voltage with the preset threshold value. If the DC voltage exceeds the preset threshold value, the motor control module 20 will transmit the braking current suppression control signal to the control end of the first switch component K1 through the first control signal output terminal Y1, thereby controlling the first switch component K1 to be turned on, so that the braking resistor R quickly consumes the large braking current generated at this time. Since the large braking current passing through the braking resistor R will generate heat, in order to avoid the braking resistor R from being damaged by overheating, the motor control module 20 also transmits the heat dissipation unit start control signal to the heat dissipation unit 32 through the second control signal output terminal Y2 to control the heat dissipation unit 32 to start running and dissipate the heat of the braking resistor R.

[0059] It should be noted that, generally, the higher the temperature of the brake resistor R, the greater its resistance value, and thus the more unfavorable it is to suppress the brake current. Therefore, it is very necessary to use the heat dissipation unit 32 to dissipate heat and cool down the brake resistor R.

[0060] Optional, Figure 4 A schematic diagram of the structure of a control system in a motor braking mode provided by an embodiment of the utility model is shown as follows: Figure 4 As shown, the heat dissipation unit 32 includes a power supply component 321, a second switch component K2 and a fan component 322. The first end of the power supply component 321 is electrically connected to the first end of the fan component 322, the second end of the power supply component 321 is electrically connected to the first end of the second switch component K2; the second end of the fan component 322 is electrically connected to the second end of the second switch component K2. The second control signal output terminal Y2 of the motor control module 20 is electrically connected to the control end of the second switch component K2.

[0061] The power supply component 321 may be a dry cell battery, a mobile power supply, or any other power supply device that can supply power, which is not specifically limited here.

[0062] Specifically, when the unmanned charging vehicle is braking, when the motor control module 20 detects that the DC voltage exceeds the preset threshold, it will transmit the heat dissipation unit start control signal to the control end of the second switch component K2 through the second control signal output terminal Y2, thereby controlling the second switch component K2 to be turned on, so that the power supply component 321, the turned-on second switch component K2 and the fan component 322 form a closed current loop, that is, the power supply component 321 supplies power to the fan component 322, thereby controlling the fan component 322 to start and run, dissipate heat and cool the braking resistor R, and ensure the reliability of the braking resistor R.

[0063] In an optional embodiment, continue to refer to Figure 4 The second switch component K2 is a contactor switch; the first end of the contactor switch K2 is electrically connected to the second end of the power supply component 321, the second end of the contactor switch K2 is electrically connected to the second end of the fan component 322, and the control end of the contactor switch K2 is electrically connected to the second control signal output end Y2.

[0064] Specifically, the contactor switch K2 can be an electric contact switch, which is usually provided with a relay coil inside. After the contactor switch K2 receives the cooling unit start control signal, the relay coil inside can be controlled to be energized, thereby causing the contactor switch K2 to be electrically attracted.

[0065] It should be noted that the second switch component K2 includes but is not limited to a contactor switch K2, and may also be other switch devices, such as a MOS switch tube.

[0066] Optional, Figure 5 A schematic diagram of the structure of a control system in a motor braking mode provided by an embodiment of the utility model is shown as follows: Figure 5 As shown, the fan assembly 322 includes a plurality of fans 3220 arranged in parallel.

[0067] The specific number of fans 3220 connected in parallel in the fan assembly 322 can be set according to actual conditions and is not specifically limited here.

[0068] Specifically, when a fan in the fan assembly 322 fails, other fans connected in parallel can still operate normally, ensuring that the fan assembly 322 can always dissipate heat for the brake resistor R.

[0069] Optional, Figure 6 A schematic diagram of the structure of a control system in a motor braking mode provided by an embodiment of the utility model is shown as follows: Figure 6 As shown, the DC power supply module 10 includes a battery assembly 11 and a DC-DC conversion unit 12 , and the DC-DC conversion unit 12 is arranged in series between the battery assembly 11 and the motor control module 20 .

[0070] Among them, the battery assembly 11 can be a high-voltage battery pack, and the voltage output by the battery assembly 11 to the DC-DC conversion unit 12 is high voltage, and its specific voltage value is not specifically limited here, for example, 600V.

[0071] Specifically, the DC-DC conversion unit 12 can convert the high voltage provided by the battery assembly 11 to obtain any voltage value, for example, converting the 600V voltage output by the battery assembly 11 into 48V. It should be noted that the specific circuit structure of the DC-DC conversion unit 12 can adopt a conventional circuit in the prior art, and no specific limitation is made here.

[0072] Based on the same utility model concept, the embodiment of the utility model also provides an unmanned charging vehicle, which can be used in various occasions and is not specifically limited here.

[0073] Note that the above are only preferred embodiments of the present invention and the technical principles used. Those skilled in the art will understand that the present invention is not limited to the specific embodiments herein, and that various obvious changes, readjustments, combinations and substitutions can be made by those skilled in the art without departing from the scope of protection of the present invention. Therefore, although the present invention is described in more detail through the above embodiments, the present invention is not limited to the above embodiments, and may include more other equivalent embodiments without departing from the concept of the present invention, and the scope of the present invention is determined by the scope of the appended claims.

Claims

1. A control system in motor braking mode, characterized in that: Applied to unmanned charging vehicles; the control system in the motor braking mode includes a DC power supply module, a motor control module, a braking current suppression module and a motor; The first voltage output end of the DC power supply module is electrically connected to the first voltage input end of the motor control module and the first end of the brake current suppression module, and the second voltage output end of the DC power supply module is electrically connected to the second voltage input end of the motor control module and the second end of the brake current suppression module; The control signal output terminal of the motor control module is electrically connected to the control terminal of the brake current suppression module, and the three-phase voltage output terminal of the motor control module is electrically connected to the motor; The DC power supply module is used to provide a DC voltage to the motor control module; The motor control module is used to control the operation of the motor according to the DC voltage, and transmit a braking current suppression control signal to the braking current suppression module through the control signal output terminal when the DC voltage is detected to exceed a preset threshold value when the motor is in a braking mode; The braking current suppression module is used to suppress the braking current generated by the DC side of the motor control module when receiving the braking current suppression control signal.

2. The control system in the motor braking mode according to claim 1, characterized in that: The braking current suppression module comprises a braking current suppression unit, and the braking current suppression unit comprises a braking resistor and a first switch component; The first end of the braking resistor is electrically connected to the first voltage output end of the DC power supply module, and the second end of the braking resistor is electrically connected to the first end of the first switch component; The second end of the first switch component is electrically connected to the second voltage output end of the DC power supply module; The control end of the first switch assembly is electrically connected to the control signal output end of the motor control module; The motor control module is used to transmit a braking current suppression control signal to the control end of the first switch component through the control signal output end when the motor is in a braking mode and detects that the DC voltage exceeds a preset threshold, so as to control the first switch component to be turned on.

3. The control system in the motor braking mode according to claim 2, characterized in that: The first switch component is a MOS switch tube; The first electrode of the MOS switch tube is electrically connected to the second end of the brake resistor, the second electrode of the MOS switch tube is electrically connected to the second voltage output end, and the gate of the MOS switch tube is electrically connected to the control signal output end of the motor control module.

4. The control system in the motor braking mode according to claim 2, characterized in that: The resistance of the braking resistor is 1Ω and the power is 3kW.

5. The control system in the motor braking mode according to claim 2, characterized in that: The braking current suppression module further includes a heat dissipation unit, and the heat dissipation unit is arranged close to the braking resistor; The control signal output terminal of the motor control module includes a first control signal output terminal and a second control signal output terminal; The first control signal output terminal is electrically connected to the control terminal of the first switch component, and the second control signal output terminal is electrically connected to the heat dissipation unit; The motor control module is further configured to transmit a heat dissipation unit start-up control signal to the heat dissipation unit through the second control signal output terminal when the motor is in a braking mode and detects that the DC voltage exceeds a preset threshold.

6. The control system in the motor braking mode according to claim 5, characterized in that: The heat dissipation unit includes a power supply component, a second switch component and a fan component; The first end of the power supply assembly is electrically connected to the first end of the fan assembly, and the second end of the power supply assembly is electrically connected to the first end of the second switch assembly; The second end of the fan assembly is electrically connected to the second end of the second switch assembly; The second control signal output terminal of the motor control module is electrically connected to the control terminal of the second switch component.

7. The control system in the motor braking mode according to claim 6, characterized in that: The second switch assembly is a contactor switch; The first end of the contactor switch is electrically connected to the second end of the power supply assembly, the second end of the contactor switch is electrically connected to the second end of the fan assembly, and the control end of the contactor switch is electrically connected to the second control signal output end.

8. The control system in the motor braking mode according to claim 6, characterized in that: The fan assembly includes a plurality of fans arranged in parallel.

9. The control system in the motor braking mode according to claim 1, characterized in that: The DC power supply module includes a battery assembly and a DC-DC conversion unit; the DC-DC conversion unit is arranged in series between the battery assembly and the motor control module.

10. An unmanned charging vehicle, characterized in that: Comprising a control system in a motor braking mode as described in any one of claims 1-9.

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