Steering power system for electric vehicle and method controlling same

A steering power system for an electric vehicle and a method for controlling same are provided. The steering power system includes: a steering motor; a steering motor controller, configured to control the steering motor; a high voltage power battery, configured to output a first voltage; a low voltage storage battery, configured to output a second voltage; a buck DC-DC converter, configured to convert the first voltage into the second voltage for being supplied to the low voltage storage battery when a high voltage system works; and a boost DC-DC converter, configured to convert the second voltage into the first voltage. When the high voltage system has an abnormal power failure, the boost DC-DC converter converts the second voltage outputted from the low voltage storage battery into the first voltage for being supplied to the steering motor controller.

CROSS REFERENCE TO RELATED APPLICATION

This application is a national phase of International Application No. PCT/CN2015/094606 filed Nov. 13, 2015, which claims priority and benefits of Chinese Patent Application No. 201410653379.6, filed with State Intellectual Property Office, P.R.C. on Nov. 17, 2014, the entire content of which is incorporated herein by reference.

FIELD

Embodiments of the present disclosure generally relate to an electric vehicle, and more particularly, to a steering power system for an electric vehicle and a method for controlling a steering power system for an electric vehicle.

BACKGROUND

Nowadays, a steering power system for an electric vehicle is mostly provided with power by a high voltage system of the electric vehicle, which can improve a performance of the steering power system. However, a sudden power failure of the high voltage system of the electric vehicle may cause the steering power system to not work, and thus the user is difficult to turn the steering wheel, which can lead to some security risks.

SUMMARY

Embodiments of the present disclosure seek to solve at least one of the problems existing in the related art to at least some extent.

Embodiments of a first aspect of the present disclosure provide a steering power system for an electric vehicle. The steering power system includes: a steering motor; a steering motor controller, connected with the steering motor and configured to control the steering motor; a high voltage power battery, configured to output a first voltage value; a low voltage storage battery, configured to output a second voltage lower than the first voltage; a buck DC-DC converter, connected with the high voltage power battery and the low voltage storage battery respectively, and configured to convert the first voltage outputted from the high voltage power battery into the second voltage for being supplied to the low voltage storage battery when a high voltage system of the electric vehicle is working; and a boost DC-DC converter, connected with the low voltage storage battery and the steering motor controller respectively, and configured to convert the second voltage outputted from the low voltage storage battery into the first voltage, wherein when the high voltage system of the electric vehicle has an abnormal power failure, the boost DC-DC converter converts the second voltage outputted from the low voltage storage battery into the first voltage for being supplied to the steering motor controller.

With the steering power system for an electric vehicle according to embodiments of the present disclosure, when the high voltage system of the electric vehicle has the abnormal power failure, the boost DC-DC converter can convert the second voltage outputted from the low voltage storage battery into the first voltage for being supplied to the steering motor controller, such that the steering motor can still work for a short time when the abnormal power failure occurs to the high voltage system, thus avoiding a potential safety risk caused by a difficult turning for the steering wheel, improving a driving safety of the electric vehicle and meeting needs of users.

Embodiments of a second aspect of the present disclosure provide a method for controlling a steering power system for an electric vehicle. The method includes: providing a first voltage by a high voltage power battery; converting the first voltage provided by the high voltage power battery into a second voltage lower than the first voltage and supplying the second voltage to a low voltage storage battery by a buck DC-DC converter, when a high voltage system of the electric vehicle is working; and converting the second voltage provided by the low voltage storage battery into the first voltage and supplying the first voltage to a steering motor controller by a boost DC-DC converter.

With the method for controlling a steering power system for an electric vehicle according to embodiments of the present disclosure, when the high voltage system of the electric vehicle has the abnormal power failure, the boost DC-DC converter can convert the second voltage outputted from the low voltage storage battery into the first voltage for being supplied to the steering motor controller, such that the steering motor can still work for a short time when the power failure occurs to the high voltage system, thus avoiding a potential safety risk caused by a difficult turning for the steering wheel, improving a driving safety of the electric vehicle and meeting needs of users.

DETAILED DESCRIPTION

Reference will be made in detail to embodiments of the present disclosure. Embodiments of the present disclosure will be shown in drawings, in which the same or similar elements and the elements having same or similar functions are denoted by like reference numerals throughout the descriptions. The embodiments described herein according to drawings are explanatory and illustrative, not construed to limit the present disclosure.

Various embodiments and examples are provided in the following description to implement different structures of the present disclosure. In order to simplify the present disclosure, certain elements and settings will be described. However, these elements and settings are only by way of example and are not intended to limit the present disclosure. In addition, reference numerals may be repeated in different examples in the present disclosure. This repeating is for the purpose of simplification and clarity and does not refer to relations between different embodiments and/or settings. Furthermore, examples of different processes and materials are provided in the present disclosure. However, it would be appreciated by those skilled in the art that other processes and/or materials may be also applied. Moreover, a structure in which a first feature is “on” a second feature may include an embodiment in which the first feature directly contacts the second feature, and may also include an embodiment in which an additional feature is formed between the first feature and the second feature so that the first feature does not directly contact the second feature.

In the description of the present disclosure, unless specified or limited otherwise, it should be noted that, terms “mounted,” “connected” and “coupled” may be understood broadly, such as electronic connections or mechanical connections, inner communications between two elements, direct connections or indirect connections through intervening structures, which can be understood by those skilled in the art according to specific situations.

With reference to the following descriptions and drawings, these and other aspects of embodiments of the present disclosure will become apparent. In the descriptions and drawings, some particular embodiments are described in order to show the principles of embodiments according to the present disclosure, however, it should be appreciated that the scope of embodiments according to the present disclosure is not limited herein. On the contrary, changes, alternatives, and modifications can be made in the embodiments without departing from spirit, principles and scope of the attached claims.

In the following, a steering power system for an electric vehicle and a method for controlling a steering power system for an electric vehicle are described in detail with reference to drawings.

FIG. 1is a schematic diagram of a steering power system for an electric vehicle according to an embodiment of the present disclosure. As shown inFIG. 1, the steering power system includes a steering motor M, a steering motor controller10, a high voltage power battery20, a low voltage storage battery30, a buck DC-DC converter40, and a boost DC-DC converter50.

The steering motor controller10is connected with the steering motor M and is configured to control the steering motor M. The high voltage power battery20is connected with the steering motor controller10and is configured to output a high voltage for being supplied to the steering motor controller10. The low voltage storage battery30is configured to output a low voltage. The buck DC-DC converter40is connected with the high voltage power battery20, the low voltage storage battery30and the steering motor controller10respectively, and is configured to convert the high voltage outputted from the high voltage power battery20into the low voltage for being supplied to the low voltage storage battery30, when a high voltage system70of the electric vehicle is working. The boost DC-DC converter50is connected with the low voltage storage battery30and the steering motor controller10respectively, and is configured to convert the low voltage outputted from the low voltage storage battery30into the high voltage. When the high voltage system70of the electric vehicle has an abnormal power failure, the boost DC-DC converter50converts the low voltage outputted from the low voltage storage battery30into the high voltage for being supplied to the steering motor controller10.

In an embodiment, as shown inFIG. 1, the steering motor controller10includes: a direct current bus capacitor C i.e. a pre-charging capacitor, an inverter101, and a detecting unit102. The direct current bus capacitor C is connected with direct current input terminals of the inverter101in parallel, and the detecting unit102is configured to detect a voltage of the direct current bus capacitor C.

FIG. 2is a schematic diagram showing a communication network of a steering power system for an electric vehicle according to another embodiment of the present disclosure. The steering power system further includes a battery manager60. The battery manager60is connected with the steering motor controller10, the buck DC-DC converter40and the boost DC-DC converter50respectively via a CAN bus, and is configured to send a power off notification message to control the high voltage system70of the electric vehicle to stop working, and then the steering motor controller10detects that the voltage of the direct current bus capacitor steadily drops. The battery manager60is configured to detect state information of the high voltage power battery20. The state information of the high voltage power battery20includes a total voltage, a current and a temperature of the high voltage power battery20.

FIG. 3is a schematic diagram of a steering power system for an electric vehicle when a buck DC-DC converter is working according to an embodiment of the present disclosure. The battery manager60is configured to: control the high voltage power battery20to supply power to the steering motor controller10independently and control the buck DC-DC converter40to work when the high voltage system70of the electric vehicle is working; control the boost DC-DC converter50to be in a standby state. The battery manager60controlling the buck DC-DC converter40to work means that, the buck DC-DC converter40converts the high voltage outputted from the high voltage power battery20into the low voltage for being supplied to the low voltage storage battery30.

FIG. 4is a schematic diagram of a steering power system for an electric vehicle when a boost DC-DC converter is working according to an embodiment of the present disclosure. The battery manager60is configure to determine that the high voltage system70of the electric vehicle has the abnormal power failure when the voltage of the direct current bus capacitor C is less than a first predetermined voltage and the power off notification message is not sent by the battery manager60, and then control the boost DC-DC converter50to work. The battery manager60controlling the boost DC-DC converter50to work means that, the boost DC-DC converter50converts the low voltage outputted from the low voltage storage battery30into the high voltage for being supplied to the steering motor controller10, such that the steering motor controller10may keep working for a short time.

Specifically, the high voltage power battery20is a power storage device mounted on the electric vehicle for providing power to the electric vehicle and other high voltage electrical equipment on the electric vehicle, which can be recharged for many times. The low voltage storage battery30may be the low voltage storage component on the electric vehicle and is provided with power by the high voltage power battery20. When the abnormal power failure occurs to the high voltage power battery20, the voltage of the low voltage storage battery30is boost by the boost DC-DC converter50and is supplied to the steering motor M. In an embodiment, the low voltage storage battery30is further configured to supply power to a low voltage system of the electric vehicle.

In an embodiment, the steering motor controller10converts the direct current from the high voltage power battery20into three-phase alternating current so as to supply power to the steering motor M, thus controlling the steering motor M, and converts the direct current from the boost DC-DC converter50into three-phase alternating current so as to supply power to the steering motor M. The steering motor M is the electrical equipment for providing a steering power for the electric vehicle and is controlled and provided with power by the steering motor controller10. The battery manager60can sample a temperature, a voltage, a charging current and a discharging current for the high voltage power battery20, calculate a remaining capacity of the high voltage power battery20, and send control signals to related electrical components via the CAN bus, so as to manage the high voltage power battery20. In addition, when a serious failure occurs to the high voltage power battery20, the battery manager60can send the power off notification message. When the electric vehicle is normally powered off, the battery manager60also can send the power off notification message.

In an embodiment, as shown inFIG. 1, input terminals of the buck DC-DC converter40are connected with the high voltage power battery20in parallel via a first DC-DC connector K1, output terminals of the buck DC-DC converter40are connected with the low voltage storage battery30in parallel, input terminals of the boost DC-DC converter50are connected with the low voltage storage battery30in parallel, output terminals of the boost DC-DC converter50are connected with the direct current bus capacitor C in parallel, and the high voltage power battery30is connected with the direct current bus capacitor C in parallel. That is, a first input terminal of the buck DC-DC converter40is connected with a positive terminal of the high voltage power battery20via the first DC-DC connector K1, and a second input terminal of the buck DC-DC converter40is connected with a negative terminal of the high voltage power battery20; a first output terminal of the buck DC-DC converter40is connected with a positive terminal of the low voltage storage battery30, and a second output terminal of the buck DC-DC converter40is connected with a negative terminal of the low voltage storage battery30; a first input terminal of the boost DC-DC converter50is connected with the positive terminal of the low voltage storage battery30, and a second input terminal of the boost DC-DC converter50is connected with the negative terminal of the low voltage storage battery30; a first output terminal of the boost DC-DC converter50is connected with a first terminal of the direct current bus capacitor C, and a second output terminal of the boost DC-DC converter50is connected with a second terminal of the direct current bus capacitor C.

Furthermore, as shown inFIG. 1, the steering power system of the electric vehicle further includes a steering contactor K2and a diode D. The steering contactor K2has a first terminal connected with the positive terminal of the high voltage power battery20and a second terminal. The diode D has an anode connected with the second terminal of the steering contactor K2and a cathode connected with the first terminal of the direct current bus capacitor C, in which the second terminal of the direct current bus capacitor C is connected with the negative terminal of the high voltage power battery20. In addition, the steering power system of the electric vehicle further includes a steering pre-charging contactor K3and a pre-charging resistor R. The steering pre-charging contactor K3has a first terminal connected with the first terminal of the steering contactor K2and a second terminal. The pre-charging resistor R has a first terminal connected with the second terminal of the steering pre-charging contactor K3and a second terminal connected with the cathode of the diode D. In other words, the steering pre-charging contactor K3and the pre-charging resistor R are connected in series and then connected with the series-connected the diode D and the steering contactor K2in parallel.

In an embodiment, the diode D is high-power diode which can prevent the boost DC-DC converter50from supplying power to other high voltage electrical equipment, the pre-charging resistor R is used to restrict the pre-charging current in the process of supplying power to the steering motor M. The connectors K1, K2, K3which are controlled by the battery manager60via level signals are used to switch on or off a power supply loop.

In an embodiment, the direct current bus capacitor C, which is inside of the steering motor controller10and is connected with direct current input terminals of the inverter101in parallel, is used to indicate a voltage value of the input terminal of the steering motor M. The voltage of the direct current bus capacitor C is relatively lower, which indicates that the steering motor M is disconnected with the high voltage system70.

In an embodiment, as shown inFIG. 3, in a normal situation, once the electric vehicle is provided with a high voltage power, the battery manager60controls the steering pre-charging contactor K3to turn on, the high voltage power battery20charges the direct current bus capacitor C, and the steering motor controller10detects the voltage of the direct current bus capacitor C in a real time and sends the voltage information of the direct current bus capacitor C to the battery manager60via the CAN bus. The battery manager60determines whether the voltage of the direct current bus capacitor C is larger than a second predetermined voltage (such as 90% of the total voltage of the high voltage power battery20) after a time delay, if yes, the battery manager60controls the steering contactor K2to turn on, the steering motor M is working normally, at the same time, the steering pre-charging contactor K3is controlled to be turned off; if no, it is determined that the voltage of the direct current bus capacitor C of the steering motor controller10is too low, such that the steering motor controller10cannot work normally, i.e., the steering motor M cannot work normally.

In an embodiment, when the steering motor M is working normally, the battery manager60controls the first DC-DC connector K1to turn on, and after receiving turn-on information of the first DC-DC connector K1from the battery manager60, the buck DC-DC converter40starts to work, as shown inFIG. 3, the high-voltage system mainly includes two discharging loops: (1) the positive terminal of the high voltage power battery20→the steering contactor K2→the diode D→the positive terminal of the steering motor controller10→the negative terminal of the steering motor controller10→the negative terminal of the high voltage power battery20; (2) the positive terminal of the high voltage power battery20→the first DC-DC connector K1→the buck DC-DC converter40→the negative terminal of the high voltage power battery20. At this time, the high voltage power battery20supply power to the steering motor controller10, the steering motor M is working normally, at the same time, the battery manager60controls the buck DC-DC converter40to work, such that the high voltage power battery20can charge the low voltage storage battery30via the buck DC-DC converter40, the boost DC-DC converter is in the standby mode. In this process, if only the electric vehicle runs normally, the high voltage power battery20may keep charging the low voltage storage battery30via the buck DC-DC converter40, and the low voltage storage battery30provides low DC voltage (such as 24V) to the low voltage electrical equipment on the electric vehicle.

In an embodiment, the battery manager60receives the voltage information of the direct current bus capacitor C from the steering motor controller10and sends the power off notification message when the power-off condition is met. When the voltage value is less than the first predetermined voltage (such as 80% of the total voltage of the high voltage power battery20) and the power off notification message is not sent by the battery manager60, the battery manager60determines that the high voltage system70of the electric vehicle has the abnormal power failure, and then controls the boost DC-DC converter50to work. As shown inFIG. 4, a discharging loop is: the first terminal (i.e., the positive terminal) of the boost DC-DC converter50→the positive terminal of the steering motor controller10→the negative terminal of the steering motor controller10→the second terminal (i.e., the negative terminal) of the boost DC-DC converter50. At this time, the boost DC-DC converter50converts the low voltage outputted from the low voltage storage battery30into the high voltage for being supplied to the steering motor controller10, so as to control the steering motor M to work for a short time. When the received voltage value of the direct current bus capacitor C is less than the first predetermined voltage (such as 80% of the total voltage of the high voltage power battery20) and the battery manager60sends the power off notification message, the battery manager60determines the high voltage of the electric vehicle is powered off normally.

FIG. 5is a schematic diagram showing a working principle of a steering power system for an electric vehicle according to an embodiment of the present disclosure. As shown inFIG. 5, the boost DC-DC converter50and the buck DC-DC converter40work simultaneously, the high-voltage system mainly includes three discharging loops: (1) the positive terminal of the high voltage power battery20→the steering contactor K2→the diode D→the positive terminal of the steering motor controller10→the negative terminal of the steering motor controller10→the negative terminal of the high voltage power battery20; (2) the positive terminal of the high voltage power battery20→the first DC-DC connector K1→the buck DC-DC converter40→the negative terminal of the high voltage power battery20; (3) the first terminal (i.e., the positive terminal) of the boost DC-DC converter50→the positive terminal of the steering motor controller10→the negative terminal of the steering motor controller10→the second terminal (i.e., the negative terminal) of the boost DC-DC converter50. When the high voltage of the electric vehicle is working, the buck DC-DC converter40converts the high voltage from the high voltage power battery20into the low voltage for charging the low voltage storage battery30, at the same time, the boost DC-DC converter50converts the second voltage outputted from the low voltage storage battery30into the high voltage for supplying power to the steering motor controller10, such that the boost DC-DC converter50and the high voltage power battery20supply power to the steering motor controller10simultaneously. When the high voltage system70of the electric vehicle has the abnormal power failure, the boost DC-DC converter50provides power to the steering motor controller10independently. In this embodiment, the boost DC-DC converter50is in the working state without any judgment, and once the high voltage system70of the electric vehicle has the abnormal power failure, the boost DC-DC converter50may respond immediately, thus supplying power to the steering motor M without interruption.

FIG. 6is a schematic diagram of a steering power system for an electric vehicle according to another embodiment of the present disclosure. In this embodiment, the steering power system includes a steering motor M, a steering motor controller10, a high voltage power battery20, a low voltage storage battery30, a buck DC-DC converter40, and a boost DC-DC converter50. Input terminals of the buck DC-DC converter40are connected with the high voltage power battery20in parallel via a second DC-DC connector K4, output terminals of the buck DC-DC converter40are connected with the low voltage storage battery30in parallel, input terminals of the boost DC-DC converter50are connected with the low voltage storage battery30in parallel, and output terminals of the boost DC-DC converter50are connected with the steering motor controller10in parallel, and the steering motor controller10is connected with the steering motor M.

The steering power system further includes a battery manager. It should be noted that, a connecting relationship of the battery manager involved in this embodiment is similar to the embodiment described above with reference toFIG. 2, thus the battery manager is not shown inFIG. 6for purpose of simplicity. The battery manager is connected with the steering motor controller10, the buck DC-DC converter40and the boost DC-DC converter50respectively via a CAN bus, and is configured to send a power off notification message to control the high voltage system of the electric vehicle to stop working, and then the steering motor controller10detects that the voltage of the direct current bus capacitor steadily drops. The battery manager is configured to detect state information of the high voltage power battery20. The state information of the high voltage power battery20includes a total voltage, a current and a temperature of the high voltage power battery20.

In this embodiment, when the high voltage system of the electric vehicle is working, the battery manager controls the buck DC-DC converter40to convert the first voltage outputted from the high voltage power battery into the second voltage to charge the low voltage storage battery30, and controls the boost DC-DC converter50to convert the second voltage outputted from the low voltage storage battery30into the first voltage for being supplied to the steering motor controller10. When the high voltage system of the electric vehicle has an abnormal power failure, the battery manager controls the boost DC-DC convertor to convert the second voltage outputted from the low voltage storage battery into the first voltage for being supplied to the steering motor controller.

In other words, the high voltage power battery20does not supply power to the steering motor controller10directly. When the high voltage system of the electric vehicle is working, the boost DC-DC converter50and the buck DC-DC converter40work simultaneously, the buck DC-DC converter40converts the high voltage from the high voltage power battery20into the low voltage (such as DC, 24V) for being supplied to the low voltage storage battery30. At the same time, the boost DC-DC converter50converts the low voltage outputted from the low voltage storage battery30into the high voltage for being supplied to the steering motor controller10. When the high voltage system70of the electric vehicle has the abnormal power failure, the low voltage storage battery30provides power to the steering motor controller10via the boost DC-DC converter50. In this embodiment, even the high voltage system70of the electric vehicle has the abnormal power failure, it does not affect the normal work of the steering motor controller10for a short time, and thus supplying power to the steering motor M without interruption.

With the steering power system for an electric vehicle according to embodiments of the present disclosure, when the high voltage system of the electric vehicle has the abnormal power failure, the boost DC-DC converter can convert the low voltage outputted from the low voltage storage battery into the high voltage for being supplied to the steering motor controller, such that the steering motor can still work for a short time when the abnormal power failure occurs to the high voltage system, thus avoiding a potential safety risk caused by a difficult turning for the steering wheel, improving the driving safety of the electric vehicle and meeting needs of users.

In the following, a method for controlling a steering power system for an electric vehicle is described in detail with reference to drawings.

FIG. 7is a flow chat of a method for controlling a steering power system for an electric vehicle according to an embodiment of the present disclosure. The steering power system involved in the method may refer to the embodiments described above with reference toFIGS. 1-6, which shall not be described again herein.

As shown inFIG. 7, the method includes following steps.

At step S01, a high voltage is provided by a high voltage power battery for the electric vehicle, that is, the electric vehicle begins to work with the high voltage.

At step S02, the high voltage provided by the high voltage power battery is converted into a low voltage, and the low voltage is supplied to the low voltage storage battery by a buck DC-DC converter. In an embodiment, the battery manager may control the buck DC-DC converter to work.

At step S03, the low voltage provided by the low voltage storage battery is converted into the high voltage and the high voltage is supplied to a steering motor controller by a boost DC-DC converter, when the high voltage system of the electric vehicle has an abnormal power failure. In an embodiment, the battery manager may control the boost DC-DC converter to work.

In an embodiment, the control method further includes: detecting a voltage of a direct current bus capacitor by the steering motor controller.

In an embodiment, if the voltage of the direct current bus capacitor is less than a first predetermined voltage and a power off notification message is not sent by a battery manager, the battery manager determines the high voltage system of the electric vehicle has the abnormal power failure, and then controls the boost DC-DC converter to convert the second voltage provided by the low voltage storage battery into the first voltage and to supply the first voltage to the steering motor controller.

In an embodiment, when the high voltage system of the electric vehicle is working, the method further includes: controlling the high voltage power battery to supply power to the steering motor controller independently; controlling the buck DC-DC converter to convert the first voltage provided by the high voltage power battery into the second voltage and to supply the second voltage to the low voltage storage battery; and controlling the boost DC-DC converter to be in a standby mode. That is, when the high voltage system of the electric vehicle is working, the battery manager controls the high voltage power battery to supply power to the steering motor controller independently and controls the buck DC-DC converter to work, i.e., the buck DC-DC converter converts the high voltage outputted from the high voltage power battery into the low voltage for charging the low voltage storage battery, and the boost DC-DC converter is in the standby mode.

In an embodiment, the control method further includes: determining whether the voltage of the direct current bus capacitor is larger than a second predetermined voltage; if yes, controlling the high voltage power battery to supply power to the steering motor controller; if no, controlling the steering motor controller to stop working.

In an embodiment, as shown inFIG. 3,FIG. 4, andFIG. 5, in a normal situation, once the electric vehicle is provided with a high power, the battery manager controls the steering pre-charging contactor to turn on, the high voltage power battery charges the direct current bus capacitor, and the steering motor controller detects the voltage of the direct current bus capacitor in a real time and sends the voltage information of the direct current bus capacitor to the battery manager via the CAN bus. The battery manager determines whether the voltage of the direct current bus capacitor is larger than a second predetermined voltage (such as 90% of the total voltage of the high voltage power battery) after a time delay, if yes, the battery manager controls the steering contactor to turn on, the steering motor is working normally, at the same time, the steering pre-charging contactor is controlled to be turned off; if no, it is determined that the voltage of the direct current bus capacitor of the steering motor controller is too low, the steering motor controller cannot work i.e. the steering motor cannot work normally.

In an embodiment, when the steering motor is working normally, the battery manager controls the first DC-DC connector to turn on, and after receiving turn-on information of the first DC-DC connector from the battery manager, the buck DC-DC converter starts to work. As shown inFIG. 3, the high-voltage power battery supply power to the steering motor controller, the steering motor is working normally, at the same time, the battery manager controls the buck DC-DC converter to work, such that the high voltage power battery can charge the low voltage storage battery via the buck DC-DC converter, the boost DC-DC converter is in the standby mode. In this process, if only the electric vehicle runs normally, the high voltage power battery may keep charging the low voltage storage battery via the buck DC-DC converter, and the low voltage storage battery provides the power (such as 24V) to the low voltage electrical equipment on the electric vehicle.

In an embodiment, the battery manager receives the voltage information of the direct current bus capacitor C from the steering motor controller and sends the power off notification message when the power-off condition is met. When the voltage value is less than the first predetermined voltage (such as 80% of the total voltage of the high voltage power battery20) and the power off notification message is not sent by the battery manager60, the battery manager60determines that the high voltage system70of the electric vehicle has the abnormal power failure, and then controls the boost DC-DC converter50to work. As shown inFIG. 4, a discharging loop is: the first terminal (i.e., the positive terminal) of the boost DC-DC converter50→the positive terminal of the steering motor controller10→the negative terminal of the steering motor controller10→the second terminal (i.e., the negative terminal) of the boost DC-DC converter50. At this time, the boost DC-DC converter50converts the low voltage outputted from the low voltage storage battery30into the high voltage for being supplied to the steering motor controller10, so as to control the steering motor M to work for a short time. When the received voltage value of the direct current bus capacitor C is less than the first predetermined voltage (such as 80% of the total voltage of the high voltage power battery20) and the battery manager60sends the power off notification message, the battery manager60determines the high voltage of the electric vehicle is powered off normally.

FIG. 8is a flow chat of a method for controlling a steering power system for an electric vehicle according to another embodiment of the present disclosure. As shown inFIG. 8, the control method includes following steps.

At step S101, the high voltage system of the electric vehicle is provided a high power.

At step S102, the battery manager controls the steering pre-charging contactor to be turned on.

At step S103, the steering motor controller detects the voltage of the direct current capacitor.

At step S104, a predetermined time is delayed. The predetermined time may be calibrated according to practice.

At step S105, the battery manager determines whether the voltage of the direct current capacitor is larger than the second predetermined voltage (i.e. 90% of the total voltage of the high voltage power battery), if yes, execute step S107; if no, execute step S106.

At step S106, since the voltage of the direct current bus capacitor of the steering motor controller is too low, the steering motor controller cannot work normally, i.e., the steering motor cannot work normally.

At step S107, the battery manager controls the steering contactor to be turned on and controls the steering pre-charging contactor to be turned off.

At step S108, the steering motor starts to work.

At step S109, the battery manager controls the first DC-DC connector to be turned on.

At step S110, the buck DC-DC converter receives the turn-on information of the first DC-DC connector from the battery manager.

At step S111, the buck DC-DC converter works in a buck mode, and the high voltage power battery charges the lower voltage battery via the buck DC-DC converter.

At step S112, the boost DC-DC converter works in the standby mode.

At step S113, the battery manager receives the voltage information of the direct current capacitor from the steering motor controller.

At step S114, the battery manager determines whether the voltage of the direct current capacitor is less than the first predetermined voltage (i.e. 80% of the total voltage of the high voltage power battery), if yes, execute step S115; if no, execute step S112.

At step S115, the battery manager determines whether the power off notification message is sent, if yes, execute step S116; if no, execute step S117.

At step S116, the electric vehicle enters a normal power-off process.

At step S117, the boost DC-DC converter works in the boost mode, and the low voltage storage battery supplies power to the steering motor controller via the boost DC-DC converter.

At step S118, the battery manager determines whether a vehicle speed is less than a predetermined speed such as 5 km/h, if yes, execute step S119; if no, execute step S117.

At step S119, the boost DC-DC converter is controlled to stop working.

Furthermore, in the driving process of the electric vehicle, the battery manager detects state information of the high voltage power battery, for example a detecting content may include whether the temperature of the high voltage power battery is too high, whether the voltage of the high voltage power battery is too low and whether the charging current is too large and so on. When a serious failure of the high voltage power battery is detected, the battery management sends the failure information of the high voltage power battery20to a display, controls the electric vehicle to drive in a limit speed, and sends the power-off notification message after a short delay, such as 15 seconds, so as to leave certain time for emergency treatment for the user. When the off button is pressed by the user, the battery manager also sends the power-off notification message such that the electric vehicle enters the normal power-off process.

In an embodiment, when the high voltage system of the electric vehicle is working, the method further includes: controlling the boost DC-DC converter and the buck DC-DC converter to work simultaneously so as to control the boost DC-DC converter and the high voltage power battery to supply power to the steering motor controller simultaneously.

In an embodiment, when the high voltage system of the electric vehicle is working, the method further includes: controlling the boost DC-DC converter and the buck DC-DC converter to work simultaneously, so as to control the boost DC-DC converter to supply power to the steering motor controller, and to control the buck DC-DC converter to supply power to the low voltage storage battery.

With the method for controlling a steering power system for an electric vehicle according to embodiments of the present disclosure, when the high voltage system of the electric vehicle has the abnormal power failure, the boost DC-DC converter can convert the second voltage outputted from the low voltage storage battery into the first voltage for being supplied to the steering motor controller, such that the steering motor can still work for a short time when the power failure occurs to the high voltage system, thus avoiding a potential safety risk caused by a difficult turning for the steering wheel, improving a driving safety of the electric vehicle and meeting needs of users.

Any procedure or method described in the flow charts or described in any other way herein may be understood to comprise one or more modules, portions or parts for storing executable codes that realize particular logic functions or procedures. Moreover, advantageous embodiments of the present disclosure comprises other implementations in which the order of execution is different from that which is depicted or discussed, including executing functions in a substantially simultaneous manner or in an opposite order according to the related functions. This should be understood by those skilled in the art which embodiments of the present disclosure belong to.

The logic and/or step described in other manners herein or shown in the flow chart, for example, a particular sequence table of executable instructions for realizing the logical function, may be specifically achieved in any computer readable medium to be used by the instruction execution system, device or equipment (such as the system based on computers, the system comprising processors or other systems capable of obtaining the instruction from the instruction execution system, device and equipment and executing the instruction), or to be used in combination with the instruction execution system, device and equipment.

The storage medium mentioned above may be read-only memories, magnetic disks or CD, etc.