JP6847697B2 - Electric vehicle control device - Google Patents

Description

Embodiments of the present invention relate to an electric vehicle control device.

Conventionally, in an electric vehicle control device mounted on an electric vehicle traveling by an AC overhead wire, a semiconductor element constituting a conversion unit such as a converter or an inverter is selected according to a current flowing through the semiconductor element. 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 driving operation, it becomes necessary to determine the rated current of the semiconductor element based on the current value during the regenerative operation. However, since the regenerative operation occurs less frequently than the power running operation, it is inefficient to determine the rated current based on this. That is, if the rated current of the semiconductor element is determined based on the current value during the regenerative operation, it may lead to a relative increase in the outer shape of the device and an increase in cost.

Japanese Unexamined Patent Publication No. 2006-08729

An object 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 device of the embodiment includes a first conversion unit, a second conversion unit, and a voltage control unit. The first conversion unit converts 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 so that the voltage of the DC link is increased when the current due to the regenerative operation of the electric vehicle exceeds a predetermined current. Further, the voltage control unit controls the voltage of the DC link so that the current due to the regenerative operation of the electric vehicle approaches the maximum current value due to the power running operation of the electric vehicle.

The schematic block diagram of the electric vehicle system 1 equipped with the electric vehicle control device of an embodiment. The functional block diagram of the control unit 30 in an embodiment. The figure which shows the relationship between the speed and the electric current at the time of power running operation and the regenerative operation of a converter 22. The figure which shows an example of the result when the voltage control unit 33 performs voltage control. FIG. 5 is a flowchart showing an example of a processing flow by the control unit 30 of the embodiment. The schematic block diagram of the electric vehicle system 1A equipped with the electric vehicle control device of an embodiment.

Hereinafter, the electric vehicle control device of the embodiment will be described with reference to the drawings.

FIG. 1 is a schematic configuration diagram of an electric vehicle system 1 equipped with an electric vehicle control device of the embodiment. The electric vehicle (railway vehicle) shown in FIG. 1 travels by receiving electric power from the overhead wire P when the collector 10 comes into contact with the overhead wire P which is a supply source of AC power. The electric vehicle system 1 includes a 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. A (second conversion unit) 25 and a control unit 30 are provided.

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

The first current detection unit 21 detects the alternating current input to the converter 22. The first current detection unit 21 is connected to the positive electrode 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. The converter 22 converts the AC power input from the transformer 14 into DC power.

The converter 22 is, for example, a power conversion circuit called a neutral point clamp method (NPC (Neutral-Point-Clamped) method). The output side (DC side) of the 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 conduct the converter 22 and the inverter 25. In FIG. 1, as an example of a DC link, first to third feeder lines are provided. The first feeder line P is maintained at, for example, a positive potential. The second feeder line C is maintained at a lower potential (intermediate potential) than the first feeder line P. The third feeder line N is maintained at a lower potential (negative potential) than the second feeder line C. The output side of the converter 22 may be a two-level circuit.

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

The voltage detection units 24-1 and 24-2 detect the output side voltage of the converter 22. Specifically, the voltage detection units 24-1 and 24-2 detect the voltages on the positive electrode side and the negative electrode side between the converter 22 and the inverter 25. For example, the voltage detection unit 24-1 detects the voltage between the first feeder line P and the second feeder line C. The voltage detection unit 24-2 detects the voltage between the second feeder line C and the third feeder line N. The voltage detection unit 24-1 and the voltage detection unit 24-2 output their respective voltage values to the control unit 30. Hereinafter, the 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 uses the DC power output from the converter 22 as a three-phase AC (three-phase AC) having a desired frequency, voltage, or the like based on a control signal (for example, a PWM (Pulse Width Modulation) control signal) input from the control unit 30. It is converted to U-phase, V-phase, W-phase), and the converted three-phase AC is output to the motor 16.

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

Further, 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 of an electric vehicle, a master controller for a driver to perform various operations, and the like. The master controller can adopt various measures, for example, it can instruct the regenerative operation of the electric vehicle by braking / deceleration by pushing it forward, and the power running operation by accelerating the electric vehicle by pulling it backward. It is a horizontal axis type 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 the instruction of 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 shown 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 controls, for example, an electric vehicle by regenerative operation or power running operation by using instruction information (for example, the number of notches) input from the operation panel 40. The regenerative operation is an operation operation in which the kinetic energy reduced by deceleration is recovered by the motor 16 and the recovered energy is converted into electric power and returned to the overhead wire P or stored in a storage battery or the like provided in the electric vehicle. Further, in the power running operation, the AC power from the overhead wire P is converted into DC power by the converter 22, and the converted DC power is converted into three-phase AC by the inverter 25 and output to the motor 16 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 motor. That is, in the regenerative operation, power is generated by generating torque in the direction opposite to the rotation direction, and in the power running operation, power is consumed by generating torque in the same direction as the rotation direction.

When the operation control unit 31 controls the regenerative operation of the electric vehicle, the operation control unit 31 outputs a signal (regeneration control signal) to that effect 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 an alternating current detected, the determination unit 32 may compare the instantaneous value with the predetermined current, or may compare the average value, the effective current, or the like with the predetermined current. .. The predetermined current is, for example, an upper limit value determined as a control target value, and is the maximum current during power running of an electric vehicle. The control unit 30 controls so that the detected current from the first current detecting unit 21 does not exceed the maximum current during the regenerative operation. As a result, it is possible to suppress the failure of the converter 22, the capacitor 23, the inverter 25, the motor 16, etc., and the shortening of the life.

FIG. 3 is a diagram showing the relationship between the speed and the current during the power running operation and the regenerative operation of the converter 22. In the example of FIG. 3, the horizontal axis represents the speed M of the electric vehicle, and the vertical axis represents the input / output current I of the converter 22. The input / output current I of the converter 22 becomes the maximum current during high-speed driving during regenerative operation and power running operation of the electric vehicle. In the example of FIG. 3, the maximum current input / output to 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, it is controlled so as not to exceed I2_max. On the other hand, if no special measures are taken in the regenerative operation, the input / output current I may increase to I1_max, which exceeds 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 operation, 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 increasing the intermediate DC voltage, the potential on the input side of the inverter 25 also increases, so that the current flowing from the output side to the input side of the inverter 25 decreases.

The determination unit 32 determines whether or not the detected 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 determines whether or not the determination result exceeds the maximum current I2_max, 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 power running operation is exceeded. The voltage control signal 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, the voltage control unit 33 may control the intermediate DC voltage V so that the increase value approaches the maximum current value I2_max during power running operation when the intermediate DC voltage V is increased. As a result, during the regenerative operation, the regeneration can be continued to near the maximum allowable limit.

FIG. 4 is a diagram showing an example of the 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 represents the intermediate DC voltage V. As shown in the figure, the intermediate DC voltage V is controlled to increase at the timing when the input / output current I during the regenerative operation exceeds the maximum current I2_max during the power running operation.

Further, when the intermediate DC voltage V is increased, the voltage control unit 33 controls so that the increase value of the intermediate DC voltage V does not exceed the preset increase limit value. The increase value may be an increase value after the input / output current I is determined to exceed the maximum current I2_max during power running operation, an increase value from a predetermined time before, or the like. , May be defined by any criteria.

For example, the voltage control unit 33 controls so that the increase value of the intermediate DC voltage V to be increased is equal to or less than the rated voltage of the member (capacitor 23 or the like) 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 less than the rated voltage of the semiconductor element included in the converter 22 or the inverter 25. In this way, by increasing the intermediate DC voltage V in the predetermined state during the regenerative operation, the intermediate DC voltage V during the power running operation, which is more frequent than the regenerative operation, can be decreased. Therefore, in the electric vehicle control device 20, a high voltage is not constantly applied, the reliability and life of the member are not significantly impaired, the input / output current I during regenerative operation can be reduced, and the element rating can be reduced. It can contribute to the miniaturization of the device.

Further, the voltage control unit 33 acquires a threshold value for determining whether or not the voltage is overvoltage from the overvoltage determination unit 34, which will be described later, when the intermediate DC voltage V is increased, and the intermediate DC voltage is set as an upper limit value. The voltage V may be controlled to be equal to or less than the 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 lower 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 with reference to a flowchart. FIG. 5 is a flowchart showing an example of the processing flow by the control unit 30 of the embodiment. First, the operation control unit 31 determines whether or not the electric vehicle is in regenerative operation (step S100). When the regenerative operation is in progress, 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 sets 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 power running operation, the voltage control unit 33 controls 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 less than the rated voltage of the member such as the capacitor 23 (step S108). When the rising value of the intermediate DC voltage V is not equal to or lower than the rated voltage, the voltage control unit 33 controls so that the rising value of the intermediate DC voltage V is not equal to or lower 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 the threshold value for determining whether or not the intermediate DC voltage V is an overvoltage (step S112). When the intermediate DC voltage V is not equal to or less than the threshold value, the voltage control unit 33 controls so that the intermediate DC voltage V is not equal to or less than the threshold value (step S114). This completes the processing of this flowchart.

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. However, the processing of this flowchart ends. The processing of this flowchart is continuously and repeatedly executed during the operation control by the control unit 30.

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 intermediate DC voltage V is increased and the current of the converter 22 during the regenerative operation is decreased. As a result, the regenerative current can be reduced without significantly impairing the reliability and life, which can contribute to the reduction of the element rating and the miniaturization of the device. Therefore, it is possible to suppress an increase in the outer shape of the device and an increase in cost. Further, by controlling the intermediate DC voltage V to be increased to be equal to or lower than the threshold value which is a reference for determining the overvoltage, it is possible to prevent the occurrence of erroneous detection due to the increase of the intermediate DC voltage V. Therefore, it is possible to reduce the regenerative current without significantly impairing the reliability and life.

(Modified example of the embodiment)
Next, a modified example of the embodiment will be described. In the above-described embodiment, the current value on the input side of the converter 22 is acquired by the first current detection unit 21, but in this modification, the current value on the output side of the inverter 25 is acquired and the acquired current is acquired. However, it is determined whether or not the predetermined current is exceeded.

FIG. 6 is a schematic configuration diagram of the 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 of the electric vehicle system 1 shown in FIG. 1 are designated by the same reference numerals, and specific description thereof will be omitted here. Compared with the electric vehicle system 1 described above, the electric vehicle system 1A includes the second current detection units 26-1 and 26-2 in the electric vehicle control device 20A instead of the first current detection unit 21. There is.

The second current detection units 26-1 and 26-2 are provided on the output side of the inverter 25, and are arbitrary 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. The second current detection unit 26-1 detects the U-phase current Iu. Further, the second current detection unit 26-2 detects the V-phase current Iv. The second current detection units 26-1 and 26-2 output the current values detected by each to the control unit 30. In the regenerative operation, the control unit 30 determines whether or not the value calculated based on the U-phase current Iu and the V-phase current Iv by the determination unit 32 exceeds the maximum current I2_max during the power running operation, and determines whether the power running When the maximum current I2_max during operation is exceeded, the voltage control unit 33 controls to increase the intermediate DC voltage V and 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 from the case where the current value on the input side of the converter 22 is used for comparison. As a result, it is possible to suppress an increase in the outer shape of the device and an increase in cost, as in the above-described embodiment.

According to at least one embodiment described above, the converter 22 that converts the alternating current supplied from the overhead wire P into direct current, and the direct current converted by the converter 22 are converted into a three-phase alternating voltage for driving the motor 16. By having the inverter 25 and the voltage control unit 33 that controls the inverter 25 so as to raise the intermediate DC voltage V when the current due to the regenerative operation of the electric vehicle exceeds a predetermined current, the outer shape of the device can be increased. The cost increase can be suppressed.

Specifically, the control unit 30 raises the intermediate DC voltage V when the input / output current I during the regenerative operation of the converter 22 exceeds the maximum current I2_max during the power running operation. Further, the control unit 30 controls so that the rising value of the intermediate current voltage V does not exceed the rising limit value which is the preset limit value of the intermediate current voltage V.

Further, the control unit 30 controls so that the increase value of the intermediate current voltage V to be increased is, for example, the rated voltage of a member (capacitor 23 or the like) connected between the converter 22 and the inverter 25. As a result, the input / output current I during the regenerative operation can be reduced without significantly impairing the reliability and life of the member, which can contribute to the reduction of the element rating and the miniaturization of the device.

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

Further, the control unit 30 controls so that the intermediate DC voltage V to be increased is equal to or less than the threshold value for determining whether or not the intermediate DC voltage V is overvoltage, so that false detection occurs due to the increase in the intermediate DC voltage V. Can be prevented.

Although some embodiments of the present invention have been described, these embodiments are presented as examples 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 gist of the invention. These embodiments and modifications thereof are included in the scope and gist of the invention, as well as in the scope of the invention described in the claims and the equivalent scope thereof.

1, 1A ... electric vehicle system, 10 ... current collector, 12 ... circuit breaker, 14 ... transformer, 16 ... motor, 20, 20A ... electric vehicle control device, 21 ... first current detector, 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 Unit, 33 ... Voltage control unit, 34 ... Overvoltage determination unit, P ... Overhead wire, W ... Wheel

Claims (4)

The first conversion unit that converts alternating current supplied from the overhead line to direct current,
A second conversion unit connected to the first conversion unit via a DC link and converting the direct current converted by the first conversion unit into a three-phase AC voltage for driving the motor.
A voltage control unit that controls to raise the voltage of the DC link when the current due to the regenerative operation of the electric vehicle exceeds a predetermined current is provided .
The voltage control unit controls the voltage of the DC link so that the current due to the regenerative operation of the electric vehicle approaches the maximum current value due to the power running operation of the electric vehicle.
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 sets the rising limit value, which is the limit value of the voltage of the DC link to be raised when the current due to the 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 detection unit that detects the voltage of the DC link between the first conversion unit and the second conversion unit, and
Further, an overvoltage determination unit for determining that the voltage detected by the voltage detection unit is an overvoltage when the voltage detected by the voltage detection unit exceeds a threshold value is provided.
The voltage control unit controls the upper limit value of the voltage of the DC link to be equal to or lower than the threshold value used by the overvoltage determination unit for determination.
The electric vehicle control device according to any one of claims 1 to 3.

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