Electric drive vehicle

Abstract

To make further effective use of regenerative electric power.SOLUTION: This electric drive vehicle comprises: a battery; a DC / DC converter that receives an input of an output voltage of the battery; an inverter that drives a motor by receiving a voltage output from the DC / DC converter or a voltage input from an overhead wire; a brake chopper device connected to the DC side of the inverter; and an overhead wire load determination device that determines whether the overhead wire needs a load for consuming the power on the basis of a voltage detection value of the DC side of the inverter and a current detection value of current flowing through the overhead wire from the inverter.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to an electric vehicle that is powered from an overhead line and runs.

Background Art

[0002] There is known an electric vehicle that runs on power supplied through a current collector such as a pantograph in a section where an overhead line is laid, and runs on power stored in a battery mounted on the vehicle in a section where no overhead line is laid.

[0003] In such a vehicle, the regenerative power generated when a braking operation is performed is stored in a battery mounted on the vehicle, or stored in a ground power storage facility via an overhead line, or supplied to another vehicle running via an overhead line.

[0004] Patent Document 1 discloses a technique for improving the regeneration efficiency by securing a supply destination of regenerative power when using an electric brake, controlling the load amount of an in-vehicle load device, and maintaining the overhead line voltage at a value suitable for the regeneration operation.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0006] When regenerating power, problems such as an increase in the overhead line voltage occur when supplying regenerative power to the overhead line when there is no power storage facility on the ground or when there are no other vehicles running on the overhead line. In Patent Document 1, consideration for such problems is not sufficient. This is fine when the battery mounted on the vehicle can absorb all the regenerative power, but such problems occur when there is surplus power that cannot be absorbed by the battery.

[0007] When the overhead line voltage rises, measures are known to suppress the regenerative power supplied to the overhead line. This is because when regenerative power is supplied to the overhead line when there is no load consuming power on the overhead line, the overhead line voltage generally rises. However, the factors causing the overhead line voltage to rise are not limited to this. When the magnitude of the system voltage supplied from the power system to the substation increases, the magnitude of the overhead line voltage supplied by the substation also increases. If the regenerative power supplied to the overhead line is suppressed along with this increase, even if there is a load that can consume power on the overhead line, the regenerative power supplied to the overhead line is suppressed, and the problem occurs that the effective utilization of the regenerative power cannot be achieved.

[0008] An object of the present invention is to further effectively utilize regenerative power.

Means for Solving the Problem

[0009] In order to solve the above problems, an electric vehicle is provided with a battery, a DC / DC converter that takes the output voltage of the battery as an input, an inverter that drives an electric motor by taking the voltage output from the DC / DC converter or the voltage from the overhead line as an input, and a brake chopper device connected to the DC side of the inverter. Based on the detected value of the voltage on the DC side of the inverter and the detected value of the current flowing from the inverter to the overhead line, an overhead line load determination device that determines whether there is a load consuming power on the overhead line is provided in the electric vehicle.

Effect of the Invention

[0010] According to the present invention, when there is a load on the overhead line, power can be supplied to the overhead line, and the effective utilization of regenerative power can be achieved. When there is no load, power can be consumed by the brake chopper device, and an increase in the overhead line voltage can be suppressed. Thereby, the stability of the overhead line voltage and the further effective utilization of regenerative power can be achieved.

Brief Description of the Drawings

[0011]

Figure 1

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Mode for Carrying Out the Invention

[0012] Hereinafter, an embodiment of an electric vehicle according to the present invention will be described with reference to the drawings.

Embodiment

[0013] FIG. 1 shows the configuration of a first embodiment of an electric vehicle. The electric vehicle 1 of this embodiment includes pantographs 101A and 101B, a reactor 102, an inverter 103, an electric motor 104, a DC / DC converter 105, a battery 106, a brake chopper device 107, a smoothing capacitor 108, a voltage sensor 109, a current sensor 110, and a controller 111.

[0014] When the electric vehicle 1 travels in a section where the overhead lines 2A and 2B for supplying DC voltage are laid, the pantograph 101 connects to the overhead line 2. The DC power supplied from the overhead lines 2A and 2B to the electric vehicle 1 is supplied to the DC side of the inverter 103 via the pantograph 101 and the reactor 102. The inverter 103 converts the DC power into three-phase AC power and supplies it to the motor 104 from the AC side of the inverter 103. The motor 104 is driven by the three-phase AC power, and thus the electric vehicle 1 runs. The DC voltage of the inverter 103 becomes approximately equal to the DC voltage of the overhead line 2, and the DC voltage of the inverter 103 is maintained by the overhead line 2. The DC / DC converter 105 operates in a power control mode for controlling the charge and discharge power of the battery 106. To prepare for future travel in a section where the overhead lines 2A and 2B are not laid, usually the battery 106 is charged at a constant current, and when the battery 106 approaches full charge, it is charged at a constant voltage.

[0015] On the other hand, when the electric vehicle 1 travels in a section where the overhead lines 2A and 2B are not laid, the DC / DC converter 105 supplies the electrical energy stored in the battery 106 to the DC side of the inverter 103 as DC power. The inverter 103 converts the DC power into three-phase AC power and supplies it to the motor 104 from the AC side of the inverter 103. The motor 104 is driven by the three-phase AC power, and thus the electric vehicle 1 runs. To maintain the DC voltage of the inverter 103 at a predetermined value, the DC / DC converter 105 operates in a voltage control mode for controlling the DC voltage of the inverter 103. That is, the DC / DC converter 105 charges and discharges the battery 106 so as to maintain the DC voltage of the inverter 103.

[0016] The brake chopper device 107 is connected to the DC side of the inverter 103 and is a device for discharging the electrical energy stored on the DC side of the inverter 103. The brake chopper device 107 operates in response to a gate pulse signal from a controller 111 described later.

[0017] The smoothing capacitor 108 is connected to the DC side of the inverter 103, and the voltage sensor 109 detects the DC voltage of the inverter 103.

[0018] The current sensor 110 is connected in series with the reactor 102 to detect the current flowing through the reactor 102. Hereinafter, the direction of the current flowing from the reactor 102 toward the overhead line 2A is defined as positive.

[0019] The controller 111 takes the voltage detection value 36 detected by the voltage sensor 109 and the current detection value 37 detected by the current sensor 110 as inputs, and outputs a gate pulse signal 59 to the brake chopper device 107. Note that in this embodiment, only the controller 111 that controls the brake chopper device 107 is shown. In reality, controllers for controlling the inverter 103 and the DC / DC converter 105 are also required, but their descriptions are omitted in this embodiment.

[0020] FIG. 2 is a diagram showing the configuration of the brake chopper device 107 in FIG. 1. The brake chopper device 107 includes a resistor 21, a diode 22, a switching element 23 such as an IGBT or SiC, and a diode 24. The resistor 21 and the switching element 23 are connected in series, and the diode 22 and the diode 24 are connected to the resistor 21 and the switching element 23, respectively. When the switching element 23 receives the gate pulse signal from the controller 111 and conducts, a current flows through the resistor 21, discharging the electrical energy stored on the DC side of the inverter 103.

[0021] FIG. 3 is a diagram showing the configuration of the controller 111 in FIG. 1. The controller 111 includes an overhead line load determiner 31 and a chopper controller 32. The overhead line load determiner 31 determines whether there is a load on the overhead line 2 that consumes the power regenerated by the electric vehicle 1 on the overhead line 2, and outputs it as a load determination result. The chopper controller 32 takes the load determination result 35 output by the overhead line load determiner 31 and the voltage detection value 36 detected by the voltage sensor 109 as inputs, and outputs a gate pulse signal 59 to the brake chopper device 107.

[0022] FIG. 4 is a diagram showing the configuration of the overhead line load detector 31 in FIG. 3. The overhead line load detector 31 includes a voltage change rate calculator 41, a first sign detector 42, a second sign detector 43, and a multiplier 44.

[0023] The voltage change rate calculator 41 takes the voltage detection value 36 detected by the voltage sensor 109 as an input and calculates its change rate.

[0024] The first sign detector 42 takes the change rate output by the voltage change rate calculator 41 as an input, determines the sign of the change rate, and thereby determines whether the voltage detection value detected by the voltage sensor 109 is increasing or decreasing. When the sign of the change rate is positive and the voltage detection value is increasing, 1 is output as the determination result. When the sign of the change rate is zero or negative and the voltage detection value is constant or decreasing, 0 is output as the determination result.

[0025] Note that when the sign of the change rate is positive and exceeds a predetermined constant threshold value, 1 may be output as the determination result. In this case, it is possible to reduce the risk of false detection.

[0026] The second sign detector 43 takes the current detection value 37 detected by the current sensor 110 as an input, determines the sign of the current detection value, and thereby determines the direction of the current flowing through the reactor 102. When the sign is positive, that is, when current is flowing from the reactor 102 in the direction of the overhead line 2A, 1 is output as the determination result. When the sign is zero or negative, that is, when no current is flowing through the reactor 102 or when current is flowing from the reactor 102 in the direction of the DC side of the inverter 103, 0 is output as the determination result.

[0027] The multiplier 44 takes as input the determination results output by the first sign determination device 42 and the second sign determination device 43, calculates its multiplication value, and outputs it as a load determination result. The load determination result becomes 1 when the determination results output by both the first sign determination device 42 and the second sign determination device 43 are 1. Therefore, the load determination result becomes 1 only when the voltage of the overhead line 2 is rising and power is being regenerated to the overhead line 2, and the load determination result becomes 0 in other cases. Note that when the load determination result is 1, it means that there is no other load consuming the power being regenerated from the electric vehicle 1 to the overhead line 2, and when the load determination result is 0, it means that power is not being regenerated to the overhead line 2 or there is another load consuming the power being regenerated to the overhead line 2.

[0028] Figure 5 is a diagram showing the configuration of the chopper controller 32 in Figure 3. The chopper controller 32 includes a chopper operation determination device 51, a subtractor 52, a multiplier 53, a duty ratio calculator 54, and a PWM calculator 55.

[0029] The chopper operation determination device 51 takes as input the load determination result 35 output by the overhead line load determination device 31 and the voltage detection value 36 detected by the voltage sensor 109. Then, it outputs a chopper operation determination result 57 for determining whether to operate the brake chopper device 107 and a voltage command Vref58 when operating the brake chopper device 107. The chopper operation determination result 57 outputs 1 when operating the brake chopper device 107 and outputs 0 when not operating it.

[0030] The subtractor 52 outputs the difference value between the voltage detection value 36 detected by the voltage sensor 109 and the voltage command Vref58 output by the chopper operation determination device 51.

[0031] The multiplier 53 takes as input the chopper operation determination result 57 output by the chopper operation determination device 51 and the difference value output by the subtractor 52, and outputs its multiplication value.

[0032] The duty ratio calculator 54 calculates a duty ratio 71 which is a command for turning ON / OFF the switching element 23, using as an input the multiplication value output by the multiplier 53. The duty ratio output by the duty ratio calculator 54 is restricted within the range of 0 to 1. The duty ratio calculator 54 is configured by, for example, proportional integral control.

[0033] The PWM calculator 55 uses as an input the duty ratio output by the duty ratio calculator 54, compares the duty ratio with a carrier signal, and outputs a gate pulse signal 59 to the switching element 23.

[0034] FIG. 6 is a diagram showing the configuration of the chopper operation determiner 51 of FIG. 5. The chopper operation determiner 51 includes a comparator 61, a multiplier 62, a signal rising edge detector 63, and a sample hold calculator 64.

[0035] The comparator 61 takes as inputs a predetermined voltage threshold Vth66 and a voltage detection value 36 detected by the voltage sensor 109, and outputs the comparison result. When the voltage detection value is greater than the voltage threshold Vth, 1 is output as the comparison result, and when the voltage detection value is the same as or less than the voltage threshold Vth, 0 is output as the comparison result.

[0036] The multiplier 62 takes as inputs the load determination result 35 output by the overhead line load determiner 31 and the comparison result output by the comparator 61, and outputs the multiplication value as the chopper operation determination result. The chopper operation determination result becomes 1 when the load determination result is 1 and the comparison result is 1. Otherwise, the chopper operation determination result is 0. When the load determination result is 1, it means that there is no other load that consumes the regenerated power on the overhead line 2 by the electric vehicle 1. In that state, if the voltage detection value 36 detected by the voltage sensor 109 exceeds a predetermined voltage threshold Vth, it is necessary to operate the brake chopper device 107 to suppress the voltage rise of the overhead line 2. Therefore, the chopper operation determination result is set to 1 at this time.

[0037] The rising-edge detector 63 detects the rising edge of the chopper operation determination result output by the multiplier 62, and outputs a pulse signal at the timing when the rising edge is detected.

[0038] The sample-and-hold arithmetic unit 64 takes as inputs the pulse signal output by the rising-edge detector 63 and the voltage detection value 36 detected by the voltage sensor 109, samples / holds the voltage detection value detected by the voltage sensor 109 at the timing when the pulse signal is input, and outputs it as the voltage command Vref69. When it is determined that it is necessary to operate the brake chopper device 107 and the chopper operation determination result changes from 0 to 1, the rising-edge detector 63 outputs a pulse signal, and at the timing when the pulse signal is output, the voltage detection value detected by the voltage sensor 109 is output as the voltage command Vref69. That is, since the voltage detection value at the time of starting to operate the brake chopper device 107 is set as the voltage command Vref69, the brake chopper device 107 discharges the electrical energy stored on the DC side of the inverter 103 so that the voltage detection value detected by the voltage sensor 109 does not rise any further.

[0039] FIG. 7 is a diagram showing an example of an operation waveform in an embodiment of the present invention. This case is an example when the load existing on the overhead line 2 decreases while regenerating power to the overhead line 2.

[0040] Until time T1, the current detection value 37 detected by the current sensor 110 is negative, and since current is flowing from the overhead line 2 to the DC side of the inverter 103, the electric drive vehicle 1 is in a state of running while receiving power supply from the overhead line 2.

[0041] Next, starting from time T1, the detected current value begins to change in the positive direction, and from time T2, the detected current value becomes positive. From time T2, power is being regenerated from the DC side of the inverter 103 to the overhead line 2, and at time T3, the increase in the regenerated power stops and becomes constant. However, since the detected voltage value 36 detected by the voltage sensor 109 does not change even though power is being regenerated to the overhead line 2 from time T2, the power regenerated to the overhead line 2 is consumed by the load existing on the overhead line 2.

[0042] Next, when the load existing on the overhead line 2 decreases from time T4 and the power consumed by the overhead line 2 decreases, the detected voltage value 36 detected by the voltage sensor 109 begins to rise. Since the detected voltage value rises while power is being regenerated to the overhead line 2, the overhead line load determination device 31 outputs 1 as the load determination result at time T5.

[0043] Next, at time T6, when the detected voltage value 36 reaches the voltage threshold value Vth, the chopper operation determination device 51 outputs 1 as the chopper operation determination result and sets the detected voltage value at that time as the voltage command Vref. Therefore, the chopper controller 32 adjusts the duty ratio so that the detected voltage value does not exceed the voltage command Vref, thereby suppressing the rise of the detected voltage value.

[0044] As described above, while power is being regenerated to the overhead line 2, if the load existing on the overhead line 2 decreases and the load cannot consume all the power being regenerated to the overhead line 2, the brake chopper device 107 operates to suppress the voltage rise of the overhead line 2.

[0045] FIG. 8 is a diagram showing another example of an operation waveform in an embodiment of the present invention. This case is an example where the voltage of the overhead line 2 has been rising from the beginning and the load existing on the overhead line 2 decreases while power is being regenerated to the overhead line 2.

[0046] Until time T1, the detected current value 37 detected by the current sensor 110 is negative, and since current is flowing from the overhead line 2 to the DC side of the inverter 103, the electric drive vehicle 1 is in a state of running while receiving power supply from the overhead line 2.

[0047] Next, starting from time T1, the detected current value begins to change in the positive direction, and from time T2, the detected current value becomes positive. From time T2, power is being regenerated from the DC side of the inverter 103 to the overhead line 2, and at time T3, the increase in the regenerative power stops and becomes constant. However, although power is being regenerated to the overhead line 2 from time T2, since the detected voltage value 36 detected by the voltage sensor 109 has not changed, the power regenerated to the overhead line 2 is consumed by the loads existing on the overhead line 2.

[0048] Next, when the load existing on the overhead line 2 decreases from time T4 and the power consumed by the overhead line 2 decreases, the detected voltage value 36 detected by the voltage sensor 109 begins to rise. Since the detected voltage value rises while power is being regenerated to the overhead line 2, the overhead line load determination device 31 outputs 1 as the load determination result at time T5. At this time, since the detected voltage value exceeds the voltage threshold Vth, the chopper operation determination device 51 outputs 1 as the chopper operation determination result and sets the detected voltage value at that time as the voltage command Vref. The chopper controller 32 adjusts the duty ratio 71 so that the detected voltage value does not exceed the voltage command Vref, thereby suppressing the rise of the detected voltage value.

[0049] As described above, in the case where the voltage of the overhead line 2 has been rising from the beginning, when other loads connected to the overhead line 2 decrease during the regeneration of power to the overhead line 2 and the other loads cannot consume all the power regenerated by the electric vehicle 1 to the overhead line 2, the brake chopper device 107 can operate to suppress the voltage rise of the overhead line 2.

Example

[0050] FIG. 9 is a modified example showing another configuration of the electric vehicle. The electric vehicle 1 of this embodiment basically has the pantographs 101A and 101B, the reactor 102, the inverter 103, the motor 104, the brake chopper device 107, the smoothing capacitor 108, the voltage sensor 109, the current sensor 110, and the controller 111 in the same manner as in Embodiment 1 and FIG. 1. The difference from the electric vehicle 1 in FIG. 1 is that it does not have the DC / DC converter 105 and the battery 106. Therefore, the electric vehicle 1 in this embodiment is always operated while connected to the overhead line 2. Otherwise, in the same manner as the electric vehicle 1 shown in the first embodiment, it is determined whether there is a load that can consume power from the overhead line 2. If there is a load, power is supplied to the overhead line, and if there is no load, the power can be consumed by the brake chopper device 107. Thus, even in an electric vehicle that does not have the DC / DC converter 105 and the battery 106, the same effects as the configuration of Embodiment 1 can be achieved.

Embodiment

[0051] FIG. 10 is a modified example showing another configuration of the electric vehicle. The electric vehicle 1 of this embodiment basically has the pantographs 101A and 101B, the reactor 102, the inverter 103, the motor 104, the brake chopper device 107, the smoothing capacitor 108, the voltage sensor 109, the current sensor 110, and the controller 111 in the same manner as in Embodiment 1 and FIG. 1. The difference from the electric vehicle 1 in FIG. 1 is that instead of the DC / DC converter 105 and the battery 106, it is provided with an AC / DC converter 112 and a generator 113. Although not described in detail in this embodiment, the generator 113 generates electricity by being driven by an engine or the like. Even in such a configuration, in the same manner as the electric vehicle 1 in FIG. 1, it is determined whether there is a load that can consume power from the overhead line 2. If there is a load, power is supplied to the overhead line, and if there is no load, the power can be consumed by the brake chopper device 107. Thus, even in an electric vehicle that has the AC / DC converter 112 and the generator 113 instead of the DC / DC converter 105 and the battery 106, the same effects as the configuration of Embodiment 1 can be achieved.

[0052] As described above, the invention of the present application described using Examples 1 to 3 can be widely applied to electric vehicles. Among them, as an example of a particularly suitable application destination, there is a dump truck that is centrally operated in a limited area such as a mine and can contribute to environmental response by efficiently utilizing regenerative power. Also, a trolleybus is a suitable example of an application destination, and a form in which a large number of electric vehicles are operated within a narrow operation route is also suitable.

[0053] In addition, the various inventions disclosed in the specification of the present application described above can also be expressed as follows as an example. <Part 1> An electric vehicle comprising a battery, a DC / DC converter that takes the output voltage of the battery as an input, an inverter that drives an electric motor using the voltage output from the DC / DC converter or the voltage from an overhead line as an input, and a brake chopper device connected to the DC side of the inverter, wherein a catenary load determination unit is provided that determines whether there is a load that consumes power on the overhead line based on the voltage detection value on the DC side of the inverter and the current detection value of the current flowing from the inverter to the overhead line. <Part 2> The electric vehicle according to <Part 1>, wherein the catenary load determination unit determines that there is a load that consumes power on the overhead line when the rate of change of the voltage detection value is positive and the current detection value is positive. <Part 3> The electric vehicle according to <Part 2>, wherein the brake chopper device is operated based on the determination result of the catenary load determination unit and the voltage detection value. <Part 4> The electric vehicle according to <Part 1>, wherein the catenary load determination unit determines that there is a load that consumes power on the overhead line when the rate of change of the voltage detection value is positive, the value exceeds a predetermined threshold, and the current detection value is positive. <Part 5> The electric vehicle according to <Part 4>, wherein the brake chopper device is operated based on the determination result of the catenary load determination unit and the voltage detection value. <Part 6> An electric drive vehicle comprising an inverter that drives an electric motor with the voltage from an overhead line as an input, and a braking chopper device connected to the DC side of the inverter, wherein the electric drive vehicle is provided with an overhead line load determination device that determines whether there is a load that consumes power from the overhead line based on the detected voltage value on the DC side of the inverter and the detected current value of the current flowing from the inverter to the overhead line. <That 7> <In that 6>, the overhead line load determination device determines that there is a load that consumes power from the overhead line when the rate of change of the detected voltage value is positive and the detected current value is positive. An electric drive vehicle. <That 8> <In that 7>, an electric drive vehicle that operates the braking chopper device based on the determination result of the overhead line load determination device and the detected voltage value. <That 9> <In that 6>, the overhead line load determination device determines that the rate of change of the detected voltage value is positive, the value exceeds a predetermined threshold, and there is a load that consumes power from the overhead line when the detected current value is positive. An electric drive vehicle. <That 10> <In that 9>, an electric drive vehicle that operates the braking chopper device based on the determination result of the overhead line load determination device and the detected voltage value. <That 11> An electric drive vehicle comprising a generator, an AC / DC converter that takes the output voltage of the generator as an input, an inverter that drives an electric motor with the voltage output from the AC / DC converter or the voltage from an overhead line as an input, and a braking chopper device connected to the DC side of the inverter, wherein the electric drive vehicle is provided with an overhead line load determination device that determines whether there is a load that consumes power from the overhead line based on the detected voltage value on the DC side of the inverter and the detected current value of the current flowing from the inverter to the overhead line. <That 12> <In that 11>, the overhead line load determination device determines that there is a load that consumes power from the overhead line when the rate of change of the detected voltage value is positive and the detected current value is positive. An electric drive vehicle. <That 13> In <12>, an electric vehicle that operates the brake chopper device based on the determination result of the overhead line load detector and the voltage detection value. <14> In <11>, an electric vehicle in which the overhead line load detector determines that there is a load consuming power on the overhead line when the rate of change of the voltage detection value is positive, its value exceeds a predetermined threshold, and the current detection value is positive. <15> In <14>, an electric vehicle that operates the brake chopper device based on the determination result of the overhead line load detector and the voltage detection value.

Explanation of Signs

[0054] 1: Electric vehicle 2: Overhead line 21: Resistor 22: Diode 23: Switching element 24: Diode 31: Overhead line load detector 32: Chopper controller 35: Load determination result 36: Voltage detection value 37: Current detection value 41: Voltage change rate calculator 42: First sign detector 43: Second sign detector 44: Multiplier 51: Chopper operation detector 52: Subtractor 53: Multiplier 54: Duty ratio calculator 55: PWM calculator 61: Comparator 62: Multiplier 63: Signal rising edge detector 64: Sample and hold calculator 101: Pantograph 102: Reactor 103: Inverter 104: Electric motor 105: DC / DC converter 106: Battery 107: Brake chopper device 108: Smoothing capacitor 109: Voltage sensor 110: Current sensor 111: Controller 112: AC / DC converter 113: Generator

Claims

1. An electrically powered vehicle comprising a battery, a DC / DC converter which receives as its input the output voltage of the battery, an inverter which receives as its input the voltage output by the DC / DC converter or the voltage from an overhead line to drive an electric motor, and a brake chopper device connected to the DC side of the inverter, characterized in that the electrically powered vehicle further comprises an overhead line load determiner which determines whether or not there is a load consuming power on the overhead line, based on a voltage detection value on the DC side of the inverter and a current detection value of the current flowing from the inverter to the overhead line.

2. 2. The electrically powered vehicle according to claim 1, wherein the overhead line load determiner determines that a load consuming power is present on the overhead line when the rate of change of the detected voltage value is positive and the detected current value is positive.

3. 3. The electrically powered vehicle according to claim 2, wherein the brake chopper device is operated based on the result of determination by the overhead line load determiner and the voltage detection value.

4. 2. The electrically powered vehicle according to claim 1, wherein the overhead line load determiner determines that there is a load consuming power on the overhead line when the rate of change of the voltage detection value is positive, the value of the voltage detection value exceeds a predetermined threshold, and the current detection value is positive.

5. 5. The electrically powered vehicle according to claim 4, wherein the brake chopper device is operated based on the result of determination by the overhead line load determiner and the voltage detection value.

6. An electrically powered vehicle equipped with an inverter that drives an electric motor using voltage from an overhead line as input, and a brake chopper device connected to the DC side of the inverter, further comprising an overhead line load determiner that determines whether or not there is a load consuming power on the overhead line, based on a voltage detection value on the DC side of the inverter and a current detection value of a current flowing from the inverter to the overhead line.

7. 7. The electrically powered vehicle according to claim 6, wherein the overhead line load determiner determines that a load consuming power is present on the overhead line when the rate of change of the detected voltage value is positive and the detected current value is positive.

8. 8. The electrically powered vehicle according to claim 7, wherein the brake chopper device is operated based on the determination result of the overhead line load determiner and the voltage detection value.

9. 7. An electrically powered vehicle according to claim 6, wherein the overhead line load determiner determines that there is a load consuming power on the overhead line when the rate of change of the voltage detection value is positive, the value of the voltage detection value exceeds a predetermined threshold, and the current detection value is positive.

10. 10. The electrically powered vehicle according to claim 9, wherein the brake chopper device is operated based on the determination result of the overhead line load determiner and the voltage detection value.

11. An electrically powered vehicle comprising a generator, an AC / DC converter which receives as input the output voltage of the generator, an inverter which receives as input the voltage output by the AC / DC converter or the voltage from an overhead line to drive an electric motor, and a brake chopper device connected to the DC side of the inverter, the electrically powered vehicle further comprising an overhead line load determiner which determines whether or not there is a load consuming power on the overhead line, based on a detected voltage value on the DC side of the inverter and a detected current value of the current flowing from the inverter to the overhead line.

12. 12. The electrically powered vehicle according to claim 11, wherein the overhead line load determiner determines that a load consuming power is present on the overhead line when the rate of change of the detected voltage value is positive and the detected current value is positive.

13. 13. The electrically powered vehicle according to claim 12, wherein the brake chopper device is operated based on the determination result of the overhead line load determiner and the voltage detection value.

14. 12. The electrically powered vehicle according to claim 11, wherein the overhead line load determiner determines that there is a load consuming power on the overhead line when the rate of change of the voltage detection value is positive, the value of the voltage detection value exceeds a predetermined threshold, and the current detection value is positive.

15. 15. The electrically powered vehicle according to claim 14, wherein the brake chopper device is operated based on the determination result of the overhead line load determiner and the voltage detection value.

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