JP2018133843A - Electric vehicle control device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electric vehicle control device which can suppress an increase in outer shape of the device and in cost.SOLUTION: An electric vehicle control device of one embodiment includes a first conversion part, a second conversion part and a voltage control part. The first conversion part converts an AC supplied from an overhead power line into a DC. The second conversion part is connected to the first conversion part via a DC link, and converts the DC converted by the first conversion part into a three-phase AC voltage for driving a motor. The voltage control part performs control so as to increase a voltage of the DC link when a current by regenerative operation of an electric vehicle exceeds a predetermined current.SELECTED DRAWING: Figure 1

Description

  Embodiments described herein relate generally to an electric vehicle control apparatus.

  2. Description of the Related Art Conventionally, in an electric vehicle control device that is mounted on an electric vehicle that runs on an AC overhead line, the semiconductor elements that constitute a conversion unit such as a converter and an inverter are selected according to the current flowing through them. If the maximum current flowing through the conversion unit during the regenerative operation of the electric vehicle is larger than the maximum current flowing during the power running operation, it is necessary to determine the rated current of the semiconductor element based on the current value during the regenerative operation. However, since the regenerative operation is less frequently generated than the power running operation, it is inefficient to determine the rated current based on this. In other words, when the rated current of the semiconductor element is determined based on the current value during the regenerative operation, there are cases where the outer shape of the device and the cost are relatively increased.

JP 2006-087299 A

  The problem to be solved by the present invention is to provide an electric vehicle control device capable of suppressing an increase in the outer shape of the device and an increase in cost.

  The electric vehicle control apparatus according to the embodiment includes a first conversion unit, a second conversion unit, and a voltage control unit. The first converter converts the alternating current supplied from the overhead wire into direct current. The second conversion unit is connected to the first conversion unit via a DC link, and converts the DC converted by the first conversion unit into a three-phase AC voltage for driving the motor. The voltage control unit controls the voltage of the DC link to be increased when the current due to the regenerative operation of the electric vehicle exceeds a predetermined current.

BRIEF DESCRIPTION OF THE DRAWINGS The schematic block diagram of the electric vehicle system 1 carrying the electric vehicle control apparatus of embodiment. The function block diagram of the control part 30 in embodiment. The figure which shows the relationship between the speed at the time of the power running operation of the converter 22, and the regenerative operation, and an electric current. The figure which shows an example of the result at the time of the voltage control part 33 performing voltage control. The flowchart which shows an example of the flow of the process by the control part 30 of embodiment. 1 is a schematic configuration diagram of an electric vehicle system 1A equipped with an electric vehicle control device of an embodiment.

  Hereinafter, an electric vehicle control apparatus according to an embodiment will be described with reference to the drawings.

  Drawing 1 is an outline lineblock diagram of electric car system 1 carrying an electric car control device of an embodiment. The electric vehicle (railway vehicle) shown in FIG. 1 travels by receiving power supply from the overhead line P when the current collector 10 comes into contact with the overhead line P that is a supply source of AC power. The electric vehicle system 1 includes a current collector 10, a circuit breaker 12, a transformer 14, a motor 16, and an electric vehicle control device 20 as main components. The electric vehicle control device 20 includes a first current detection unit 21, a converter (first conversion unit) 22, capacitors 23-1 and 23-2, voltage detection units 24-1 and 24-2, and an inverter. (Second conversion unit) 25 and a control unit 30 are provided.

  The current collector 10 acquires AC power from the overhead line P. The circuit breaker 12 is provided between the current collector 10 and the transformer 14. The circuit breaker 12 blocks the supply of AC power to the transformer 14 under predetermined conditions. The transformer 14 converts the voltage of the AC power output from the current collector 10 into a desired voltage.

  The first current detector 21 detects an alternating current input to the converter 22. The first current detector 21 is connected to the positive side of the bipolar terminal to which the transformer 14 and the converter 22 are connected. The first current detection unit 21 outputs the detected alternating current to the control unit 30. Converter 22 converts AC power input from transformer 14 into DC power.

  The converter 22 is a power conversion circuit called, for example, a neutral point clamp method (NPC (Neutral-Point-Clamped) method). The output side (DC side) of converter 22 forms a three-level circuit including capacitors 23-1 and 23-2.

  The electric vehicle control device 20 is provided with a DC link so as to connect the converter 22 and the inverter 25. In FIG. 1, first to third power supply lines are provided as an example of a DC link. The first power supply line P is maintained at a positive potential, for example. The second feeder C is maintained at a lower potential (intermediate potential) than the first feeder P. The third feeder line N is maintained at a lower potential (negative potential) than the second feeder line C. Note that the output side of the converter 22 may be a two-level circuit.

  Capacitors 23-1 and 23-2 smooth the power output from converter 22. The capacitor 23-1 is connected between the first power supply line P and the second power supply line C. Further, the capacitor 23-2 is connected between the second power supply line C and the third power supply line N.

  Voltage detectors 24-1 and 24-2 detect the output side voltage of converter 22. Specifically, voltage detection units 24-1 and 24-2 detect positive and negative voltages between converter 22 and inverter 25. For example, the voltage detection unit 24-1 detects a voltage between the first power supply line P and the second power supply line C. The voltage detection unit 24-2 detects a voltage between the second power supply line C and the third power supply line N. The voltage detection unit 24-1 and the voltage detection unit 24-2 output the respective voltage values to the control unit 30. Hereinafter, a value obtained by adding the voltage obtained from the voltage detection unit 24-1 and the voltage obtained from the voltage detection unit 24-2 is referred to as an intermediate DC voltage.

  The inverter 25 converts the DC power output from the converter 22 into a three-phase AC having a desired frequency, voltage, etc. based on a control signal (for example, a PWM (Pulse Width Modulation) control signal) input from the control unit 30. (U phase, V phase, W phase) and the converted three-phase alternating current is output to the motor 16.

  The motor 16 rotates the rotor by three-phase alternating current and outputs driving force. The driving force output from the motor 16 is transmitted to the wheel W through a coupling mechanism such as a gear (not shown), and the electric vehicle is caused to travel by rotating the wheel W with the transmitted driving force. The motor 16 is, for example, a cage type three-phase induction motor. The wheel W is grounded via the track R.

  The electric vehicle system 1 includes an operation panel 40 and a display panel 50. The operation panel 40 includes, for example, a master switch for turning on / off the main power supply of the electric vehicle, a master controller for performing various operations by the driver, and the like. The master controller can adopt various measures. For example, the master controller can instruct regenerative operation of the electric vehicle by braking / deceleration by pushing forward, and can instruct power running by acceleration of the electric vehicle by pulling backward. This is a horizontal axis master controller. A signal indicating the amount of operation performed on the master controller or a control signal determined based on the operation is input to the control unit 30. The display panel 50 displays various information including the speed of the electric vehicle based on instructions from the control unit 30.

  Next, the control unit 30 in the embodiment will be described. FIG. 2 is a functional configuration diagram of the control unit 30 in the embodiment. The control unit 30 illustrated in FIG. 2 includes an operation control unit 31, a determination unit 32, a voltage control unit 33, and an overvoltage determination unit 34.

  The operation control unit 31 performs, for example, control by regenerative operation or control by power running of an electric vehicle based on instruction information (for example, the number of notches) input from the operation panel 40. The regenerative operation is an operation operation in which kinetic energy that is reduced by deceleration is recovered by the motor 16, and the recovered energy is converted into electric power and returned to the overhead line P or stored in a storage battery or the like provided in the electric vehicle. Further, the power running operation means that the AC power from the overhead line P is converted to DC power by the converter 22, the converted DC power is converted to three-phase AC by the inverter 25, and output to the motor 16. This is a driving operation such as generating a driving force and transmitting the generated driving force to the wheels W to accelerate the electric vehicle. That is, in regenerative operation, power is generated by generating torque in the direction opposite to the rotation direction, and in powering operation, power is consumed by generating torque in the same direction as the rotation direction.

  When the regenerative operation control is performed on the electric vehicle, the operation control unit 31 outputs a signal (regeneration control signal) indicating that to the determination unit 32. The determination unit 32 determines whether or not the detection current input from the first current detection unit 21 exceeds a predetermined current when the regeneration control signal is input from the operation control unit 31. Here, since the detected current is obtained by detecting alternating current, the determination unit 32 may compare the instantaneous value with the predetermined current, or may compare the average value or the effective current with the predetermined current. . The predetermined current is, for example, an upper limit value determined as a control target value, and is a maximum current during powering operation of the electric vehicle. The control unit 30 performs control so that the detection current from the first current detection unit 21 does not exceed the maximum current during the regenerative operation. As a result, failure of the converter 22, the capacitor 23, the inverter 25, the motor 16, and the like, and a decrease in life can be suppressed.

  FIG. 3 is a diagram illustrating the relationship between the speed and current during power running operation and regenerative operation of converter 22. In the example of FIG. 3, the horizontal axis indicates the speed M of the electric vehicle, and the vertical axis indicates the input / output current I of the converter 22. The input / output current I of the converter 22 is the maximum current during high-speed traveling during regenerative operation and powering operation of the electric vehicle. In the example of FIG. 3, the maximum current input / output to / from the converter 22 during the regenerative operation is I1_max, and the maximum current input / output to the converter 22 during the power running operation is I2_max. Here, in the power running operation, since the control target value is set, control is performed so as not to exceed I2_max. On the other hand, if no special contrivance is made in the regenerative operation, the input / output current I may increase to I1_max exceeding I2_max.

  Therefore, when the input / output current I during the regenerative operation becomes higher than the maximum current I2_max during the power running, the control unit 30 increases the intermediate DC voltage and decreases the input / output current I of the converter 22 during the regenerative operation. Take control. By raising the intermediate DC voltage, the input side potential of the inverter 25 also rises, so the current flowing from the output side of the inverter 25 to the input side becomes lower.

  The determination unit 32 determines whether or not the detection current from the first current detection unit 21 exceeds the maximum current I2_max during the power running operation of the electric vehicle during the regenerative operation, and the determination result is the voltage control unit 33. Output to. Based on the determination result input from the determination unit 32, the voltage control unit 33 generates and generates a voltage control signal for increasing the intermediate DC voltage V when the maximum current I2_max during powering operation is exceeded. The voltage control signal thus output is output to the converter 22 and the inverter 25. The increase width of the intermediate DC voltage V is set so that the current approaches the maximum current. In this case, when the intermediate DC voltage V is increased, the voltage control unit 33 may perform control so that the increased value approaches the maximum current value I2_max during powering operation. Thereby, at the time of regeneration operation, regeneration can be continued to near the maximum allowable limit.

  FIG. 4 is a diagram illustrating an example of a result when the voltage control unit 33 performs voltage control. The horizontal axis of FIG. 4 indicates the speed M of the electric vehicle, and the vertical axis indicates the intermediate DC voltage V. As shown in the figure, the intermediate DC voltage V is controlled to rise at a timing when the input / output current I during the regenerative operation exceeds the maximum current I2_max during the power running operation.

  In addition, when the intermediate DC voltage V is increased, the voltage control unit 33 performs control so that the increase value of the intermediate DC voltage V does not exceed a preset increase limit value. The increase value may be an increase value after it is determined that the input / output current I exceeds the maximum current I2_max during powering operation, may be an increase value from a predetermined time before, , May be defined by any criteria.

  For example, the voltage control unit 33 performs control so that the increased value of the intermediate DC voltage V to be increased is equal to or lower than the rated voltage of a member (such as the capacitor 23) connected between the converter 22 and the inverter 25, for example. The voltage control unit 33 may further control the increase value of the intermediate DC voltage V to be increased to be equal to or lower than the rated voltage of the semiconductor element included in the converter 22 or the inverter 25. As described above, by increasing the intermediate DC voltage V in a predetermined state during the regenerative operation, the intermediate DC voltage V during the power running operation that is more frequent than the regenerative operation can be reduced. Therefore, the electric vehicle control device 20 is not constantly applied with a high voltage, and can greatly reduce the input / output current I during the regenerative operation without significantly impairing the reliability and life of the member. This can contribute to downsizing of the apparatus.

  Further, when increasing the intermediate DC voltage V, the voltage control unit 33 obtains a threshold value for determining whether or not the voltage is an overvoltage from an overvoltage determination unit 34 to be described later, and uses the threshold value as an upper limit value. You may control so that the voltage V may become below a threshold value.

  The overvoltage determination unit 34 determines whether or not the intermediate DC voltage V detected by the voltage detection units 24-1 and 24-2 is an overvoltage. The overvoltage determination unit 34 determines that the intermediate DC voltage V is an overvoltage when the intermediate DC voltage V exceeds a preset threshold value.

  In this way, by setting the upper limit value of the intermediate DC voltage V to be equal to or less than the threshold value of the overvoltage determination unit 34, the control unit 30 can prevent erroneous detection by the overvoltage determination unit 34.

  Here, the flow of processing by the control unit 30 of the embodiment will be described using a flowchart. FIG. 5 is a flowchart illustrating an example of a flow of processing by the control unit 30 according to the embodiment. First, the operation control unit 31 determines whether or not the electric vehicle is in a regenerative operation (step S100). When the regenerative operation is being performed, the determination unit 32 acquires the input / output current I of the converter 22 from the first current detection unit 21 (step S102), and the acquired input / output current I determines the maximum current I2_max during the power running operation. It is determined whether or not it exceeds (step S104).

  When the acquired current value exceeds the maximum current I2_max during powering operation, the voltage control unit 33 performs control to increase the intermediate DC voltage V (step S106). Further, the voltage control unit 33 determines whether or not the increased value of the increased intermediate DC voltage V is equal to or lower than the rated voltage of the member such as the capacitor 23 (step S108). When the increase value of the intermediate DC voltage V is not less than the rated voltage, the voltage control unit 33 controls the increase value of the intermediate DC voltage V to be less than the rated voltage (step S110).

  Further, the voltage control unit 33 determines whether or not the intermediate DC voltage V is equal to or less than a threshold value for determining whether or not it is an overvoltage (step S112). When the intermediate DC voltage V is not less than or equal to the threshold value, the voltage control unit 33 controls the intermediate DC voltage V to be equal to or less than the threshold value (step S114). Thereby, the processing of this flowchart is completed.

  Further, when the intermediate DC voltage V is equal to or lower than the rated voltage, when the regenerative operation is not performed in the process of step S100, or when the current value does not exceed the maximum current I2_max during the power running operation in the process of step S104. In addition, the processing of this flowchart is completed. In addition, the process of this flowchart is repeatedly performed continuously during the operation control by the control part 30. FIG.

  According to the embodiment described above, when the current during the regenerative operation exceeds the maximum current I2_max during the power running operation, the control is performed to increase the intermediate DC voltage V and decrease the current of the converter 22 during the regenerative operation. As a result, the regenerative current can be lowered without greatly impairing the reliability and life, which can contribute to reduction of element rating and downsizing of the apparatus. Therefore, an increase in the outer shape of the apparatus and an increase in cost can be suppressed. Further, by controlling the intermediate DC voltage V to be increased to be equal to or lower than a threshold value used as a reference for determining an overvoltage, it is possible to prevent erroneous detection due to the increase of the intermediate DC voltage V. Therefore, the regenerative current can be lowered without greatly impairing reliability and life.

(Modification of the embodiment)
Next, a modification of the embodiment will be described. In the embodiment described above, the current value on the input side of the converter 22 is acquired by the first current detection unit 21. However, in this modification, the current value on the output side of the inverter 25 is acquired and acquired. Determines whether the current exceeds a predetermined current.

  FIG. 6 is a schematic configuration diagram of an electric vehicle system 1A equipped with the electric vehicle control device of the embodiment. In the description of the electric vehicle system 1A, the same components as those in the electric vehicle system 1 shown in FIG. 1 are denoted by the same reference numerals, and detailed description thereof is omitted here. Compared to the electric vehicle system 1 described above, the electric vehicle system 1A includes second current detection units 26-1 and 26-2 instead of the first current detection unit 21 in the electric vehicle control device 20A. Yes.

  The second current detection units 26-1 and 26-2 are provided on the output side of the inverter 25, and any of the three-phase alternating currents (U phase, V phase, W phase) output from the inverter 25. Extract the current values of the two phases. Second current detection unit 26-1 detects U-phase current Iu. In addition, the second current detection unit 26-2 detects the V-phase current Iv. Second current detection units 26-1 and 26-2 output the detected current values to control unit 30. In the regenerative operation, the control unit 30 determines whether or not the value calculated by the determination unit 32 based on the U-phase current Iu and the V-phase current Iv exceeds the maximum current I2_max during powering operation. When the maximum current I2_max during operation is exceeded, the intermediate DC voltage V is increased by the voltage control unit 33, and control is performed to decrease the input / output current I of the converter 22 during regenerative operation. In this case, the calculation method, the upper limit current, or the like may be different as compared with the case where the current value on the input side of the converter 22 is used as a comparison target. Thereby, like the embodiment described above, it is possible to suppress an increase in the outer shape of the apparatus and an increase in cost.

  According to at least one embodiment described above, the converter 22 that converts alternating current supplied from the overhead wire P into direct current, and the direct current converted by the converter 22 is converted into a three-phase alternating current voltage for driving the motor 16. And the voltage control unit 33 that controls the inverter 25 to increase the intermediate DC voltage V when the current due to the regenerative operation of the electric vehicle exceeds a predetermined current, An increase in cost can be suppressed.

  Specifically, control unit 30 increases intermediate DC voltage V when input / output current I during regenerative operation of converter 22 exceeds maximum current I2_max during powering operation. Further, the control unit 30 performs control so that the increase value of the intermediate current voltage V does not exceed the increase limit value which is a preset limit value of the intermediate current voltage V.

  Further, the control unit 30 performs control so that the increase value of the intermediate current voltage V to be increased is equal to or lower than the rated voltage of a member (such as the capacitor 23) connected between the converter 22 and the inverter 25, for example. As a result, the input / output current I during the regenerative operation can be reduced without greatly impairing the reliability and life of the member, which can contribute to a reduction in element rating and a reduction in the size of the apparatus.

  Further, when increasing the intermediate DC voltage V, the control unit 30 controls the input / output current I during the regenerative operation of the converter 22 so as to approach the maximum current value I2_max during the power running operation. It is possible to generate electricity close to the maximum allowable limit. Further, in each of the power running operation and the regenerative operation, the control can be performed based on the approximate or equivalent maximum current. Therefore, it is possible to improve the efficiency of the control by the power running operation or the regenerative operation of the electric vehicle.

  In addition, the control unit 30 performs control so that the intermediate DC voltage V to be increased is equal to or less than a threshold value for determining whether or not the voltage is an overvoltage, thereby generating an erroneous detection due to the increase of the intermediate DC voltage V. Can be prevented.

  Although several embodiments of the present invention have been described, these embodiments are presented by way of example and are not intended to limit the scope of the invention. These embodiments can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the spirit of the invention. These embodiments and their modifications are included in the scope and gist of the invention, and are also included in the invention described in the claims and the equivalents thereof.

  DESCRIPTION OF SYMBOLS 1, 1A ... Electric vehicle system, 10 ... Current collector, 12 ... Circuit breaker, 14 ... Transformer, 16 ... Motor, 20, 20A ... Electric vehicle control device, 21 ... First electric current detection part, 22 ... Converter (first) 1 ... conversion unit), 23 ... capacitor, 24 ... voltage detection unit, 25 ... inverter (second conversion unit), 26 ... second current detection unit, 30 ... control unit, 31 ... operation control unit, 32 ... determination Part, 33 ... voltage control part, 34 ... overvoltage determination part, P ... overhead wire, W ... wheel

Claims (5)

A first converter that converts alternating current supplied from an overhead wire into direct current;
A second converter connected to the first converter via a DC link and converting the direct current converted by the first converter into a three-phase AC voltage for driving a motor;
A voltage control unit that controls to increase the voltage of the DC link when the current due to regenerative operation of the electric vehicle exceeds a predetermined current; and
An electric vehicle control device. The predetermined current is an upper limit value of a current determined as a control target value.
The electric vehicle control device according to claim 1. The voltage control unit is configured to set an increase limit value, which is a limit value of a DC link voltage to be increased when a current due to regenerative operation of the electric vehicle exceeds a predetermined current, to the first conversion unit and the second conversion unit Control below the rated voltage of the member connected between
The electric vehicle control device according to claim 1. A voltage detector for detecting a voltage of a DC link between the first converter and the second converter;
An overvoltage determination unit that determines that the voltage detected by the voltage detection unit is an overvoltage when the voltage detected by the voltage detection unit exceeds a threshold;
The voltage control unit controls the upper limit value of the voltage of the DC link to be equal to or lower than a threshold used by the overvoltage determination unit.
The electric vehicle control device according to any one of claims 1 to 3. The voltage control unit controls the voltage of the DC link so that a current due to regenerative operation of the electric vehicle approaches a maximum current value due to power running operation of the electric vehicle.
The electric vehicle control device according to any one of claims 1 to 4.

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