Electric vehicles

Abstract

An electrically driven vehicle according to the present invention includes: a battery; a DC / DC converter into which an output voltage of the battery is input; an inverter into which a voltage output from the DC / DC converter or a voltage output from an overhead wire is input to drive an electric motor; and a braking chopper device that includes a switching element, a resistor, and a diode and is connected to the DC side of the inverter. The electrically driven vehicle switches the conditions under which the switching element operates between when the electrically driven vehicle is connected to the overhead wire and when the electrically driven vehicle is not connected to the overhead wire.

Description

[Technical Field]

[0001] The present invention relates to electrically driven vehicles. [Background Art]

[0002] An electrically driven vehicle is known that travels using electric power supplied via a current collector such as a pantograph in a section where an overhead wire is laid, and travels using electric power stored in a battery mounted on the vehicle in a section where no overhead wire is laid. In such a vehicle, regenerative electric power generated when a brake operation is performed is stored in a battery mounted on the vehicle, or stored in an electricity storage facility on the ground via the overhead wire, or supplied to another vehicle traveling via the overhead wire.

[0003] Regarding electrically driven vehicles, Patent Document 1 is known. Patent Document 1 discloses a technique that improves regeneration efficiency and improves the stopping position accuracy of an ATO vehicle by securing a supply destination of regenerative power when using an electric brake, controlling the load of an in-vehicle load device, and maintaining the overhead wire voltage at a value suitable for regenerative operation. [Prior Art Literature] [Patent Literature]

[0004] [Patent Document 1] Japanese Unexamined Patent Application Publication No. 2013-70611 [Summary of the Invention] [Problem to be Solved by the Invention]

[0005] In Patent Document 1, as described above, the problem of improving regeneration efficiency can be solved. However, when there is no electricity storage facility on the ground or there is no other vehicle traveling on the overhead wire, supplying regenerative power to the overhead wire causes problems such as an increase in overhead wire voltage. In Patent Document 1, it is considered that sufficient consideration is not given to such a problem. In addition, when regenerating power while traveling in a section where no overhead wire is laid, a problem that the DC voltage of an inverter that drives the vehicle may increase may also occur.

[0006] To solve the above-mentioned problems, it is considered necessary to absorb all of the regenerated power generated by the vehicle's battery. However, depending on the battery's charge level, it is not always possible to absorb all of the regenerated power with the vehicle's battery. If excess power is generated that cannot be absorbed by the battery, reverse power flow to the overhead lines will occur in sections where overhead lines are installed, and the DC voltage of the inverter driving the vehicle will increase in sections where overhead lines are not installed.

[0007] Therefore, there are challenges in suppressing the adverse effects caused by reverse power flow resulting from regenerative power generated when an electric vehicle applies the brakes, and in suppressing the rise in the DC voltage of the inverter that drives the vehicle. [Means for solving the problem]

[0008] According to a first aspect of the present invention, the following electric-driven vehicle is provided. This electric-driven vehicle comprises a battery, a DC / DC converter that takes the output voltage of the battery as input, an inverter that drives an electric motor using the voltage output of the DC / DC converter or the voltage output of the overhead line as input, and a brake chopper device that includes a switching element, a resistor, and a diode and is connected to the DC side of the inverter. The electric-driven vehicle switches the operating conditions of the switching element depending on whether the electric-driven vehicle is connected to an overhead line or not.

[0009] Furthermore, according to a second aspect of the present invention, the following electric-driven vehicle is provided. This electric-driven vehicle comprises a generator, an AC / DC converter that takes the output voltage of the generator as input, an inverter that drives an electric motor using the voltage output of the AC / DC converter or the voltage output of the overhead line as input, and a brake chopper device that includes a switching element, a resistor, and a diode and is connected to the DC side of the inverter. The electric-driven vehicle switches the operating conditions of the switching element depending on whether the electric-driven vehicle is connected to an overhead line or not. [Effects of the Invention]

[0010] According to the present invention, it is possible to suppress adverse effects caused by reverse power flow resulting from regenerative power generated when an electric vehicle performs braking operations, and to suppress the rise in the DC voltage of the inverter that drives the vehicle. Other problems, configurations, and effects not mentioned above will be clarified by the following description of embodiments for carrying out the invention. [Brief explanation of the drawing]

[0011] [Figure 1] Regarding the first embodiment, an example of the configuration of an electric vehicle is shown. [Figure 2] An example of the configuration of a brake chopper device is shown. [Figure 3] An example of the controller configuration of the first embodiment is shown. [Figure 4] An example of the configuration of the chopper controller of the first embodiment is shown. [Figure 5] An example of the operating waveform in the battery operation mode of the first embodiment is shown. [Figure 6] An example of the operating waveform in the trolley operation mode of the first embodiment is shown. [Figure 7] Regarding the second embodiment, an example of the configuration of an electric vehicle is shown. [Figure 8] An example of the controller configuration in the second embodiment is shown. [Figure 9] An example of the configuration of the chopper controller in the second embodiment is shown. [Figure 10] An example of the operating waveform in the trolley operation mode of the second embodiment is shown. [Figure 11] An example of the operating waveform in the trolley operation mode of the second embodiment is shown. [Figure 12] Regarding the third embodiment, an example of the configuration of an electric vehicle is shown. [Figure 13] Regarding the fourth embodiment, an example of the configuration of an electric vehicle is shown. [Modes for carrying out the invention]

[0012] Hereinafter, embodiments of the present invention will be described with reference to the drawings. The embodiments are exemplifications for explaining the present invention, and are appropriately omitted and simplified as necessary to clarify the description. The present invention can also be implemented in various other forms. Unless particularly limited, each component may be singular or plural. The position, size, shape, range, etc. of each component shown in the drawings may not represent the actual position, size, shape, range, etc. in order to facilitate understanding of the invention. Therefore, the present invention is not necessarily limited to the position, size, shape, range, etc. disclosed in the drawings. When there are a plurality of components having the same or similar functions, description may be given by adding different suffixes to the same reference numeral. In addition, when there is no need to distinguish between the plurality of components, the suffix may be omitted in the description.

[0013] Hereinafter, embodiments of an electrically driven vehicle according to the present invention will be described with reference to the drawings. An electrically driven vehicle is a vehicle that travels when supplied with electric power. In the embodiment, as an example, a technique for suppressing reverse power flow to an overhead line caused by regenerative power generated when an electrically driven vehicle performs a braking operation and an increase in DC voltage of an inverter that drives the vehicle will be described.

[0014] <First Embodiment> FIG. 1 shows an example of the configuration of an electrically driven vehicle according to the first embodiment. The electrically driven vehicle 1 of the present embodiment includes a pantograph, a reactor, an inverter, an electric motor, a DC / DC converter, a battery, a brake chopper device, a smoothing capacitor, a voltage sensor, a current sensor, and a controller.

[0015] When the electrically driven vehicle 1 travels in a section where an overhead line 2 that supplies DC voltage is laid, the pantograph 101 is connected to the overhead line 2, and the DC power supplied from the overhead line 2 to the electrically driven vehicle 1 is supplied to the DC side of the inverter 103 via the pantograph 101 and the reactor 102. Then, the inverter 103 converts the DC power into three-phase AC power, and supplies the three-phase AC power from the AC side of the inverter 103 to the electric motor 104. The electrically driven vehicle 1 travels when the electric motor 104 is driven by the three-phase AC power. The DC voltage of the inverter 103 is substantially 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 that controls the charging and discharging power of the battery 106. The DC / DC converter 105 normally charges the battery 106 with a constant current in preparation for future traveling in sections where the overhead line 2 is not laid, and charges the battery 106 with a constant voltage when the battery 106 approaches full charge.

[0016] On the other hand, when the electrically driven vehicle 1 travels in a section where the overhead line 2 is not laid, the DC / DC converter 105 supplies the electrical energy stored in the battery 106 as DC power to the DC side of the inverter 103. The inverter 103 converts the DC power into three-phase AC power, and supplies the three-phase AC power from the AC side of the inverter 103 to the electric motor 104. The electrically driven vehicle 1 travels when the electric motor 104 is driven by the three-phase AC power. In order to maintain the DC voltage of the inverter 103 at a predetermined value, the DC / DC converter 105 operates in a voltage control mode that controls 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.

[0017] 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 received from a controller 111 described later.

[0018] The smoothing capacitor 108 is connected to the DC side of the inverter 103, and the DC voltage sensor 109 detects the DC voltage of the inverter 103.

[0019] The current sensor 110 is connected in series with the reactor 102 and detects the current flowing through the reactor 102. In the following, the direction of the current flowing from the reactor 102 toward the overhead wire 2 is considered positive.

[0020] The controller 111 takes the voltage detection value detected by the voltage sensor 109 and the current detection value detected by the current sensor 110 as inputs and outputs a gate pulse signal to the brake chopper device 107. In this embodiment, only the controller 111 that controls the brake chopper device 107 is shown. In reality, controllers that control the inverter 103 and the DC / DC converter 105 are also required, but they are omitted from this embodiment.

[0021] Figure 2 shows an example configuration of the brake chopper device 107. The brake chopper device 107 includes a resistor 1071, a diode 1072, a switching element 1073 such as an IGBT (Insulated Gate Bipolar Transistor), and a diode 1074. The resistor 1071 and the switching element 1073 are connected in series, and the diodes 1072 and 1074 are connected in antiparallel to the resistor 1071 and the switching element 1073, respectively. When the switching element 1073 receives a gate pulse signal from the controller 111, it conducts, causing current to flow through the resistor 1071, and the electrical energy stored on the DC side of the inverter 103 is discharged.

[0022] Figure 3 shows an example of the configuration of the controller 111. The controller 111 comprises an operating mode determination unit 1111 and a chopper controller 1112. The operating mode determination unit 1111 determines whether the electric vehicle 1 is in a mode in which it runs while connected to the overhead line 2 and exchanging power with the overhead line 2 (hereinafter referred to as trolley operating mode), or in a mode in which the electric vehicle 1 runs by charging and discharging electrical energy stored in the battery 106 without being connected to the overhead line 2 (hereinafter referred to as battery operating mode), and outputs the determination result. The chopper controller 1112 takes the determination result output by the operating mode determination unit 1111, the voltage detection value detected by the voltage sensor 109, and the current detection value detected by the current sensor 110 as inputs and outputs a gate pulse signal to the brake chopper device 107.

[0023] Figure 4 shows an example configuration of the chopper controller 1112. The chopper controller 1112 comprises a subtractor 11121, a duty cycle calculator 11122, a subtractor 11123, a duty cycle calculator 11124, an output switch 11125, and a PWM calculator 11126.

[0024] The subtractor 11121 outputs a value obtained by subtracting the current threshold Ith from the current detection value output by the current sensor 110. Here, the current threshold Ith is the target upper limit of the current flowing in reverse to the overhead line 2, and is a positive value.

[0025] The duty cycle calculator 11122 takes the calculated value output by the subtractor 11121 and the operating mode determination result output by the operating mode determination unit 1111 as inputs to calculate the duty cycle that will serve as a command to turn the switching element 1073 ON / OFF. The duty cycle output by the duty cycle calculator 11122 is limited to a range of 0 to 1. The duty cycle calculator 11122 is configured, for example, using proportional-integral control. If the operating mode determination result output by the operating mode determination unit 1111 is the trolley operating mode, the duty cycle calculator 11122 performs the calculation and outputs the result as the duty cycle. On the other hand, if the operating mode determination result output by the operating mode determination unit 1111 is the battery operating mode, the duty cycle calculator 11122 stops the calculation and outputs 0 as the duty cycle.

[0026] The subtractor 11123 outputs a value obtained by subtracting the voltage threshold Vth from the voltage detection value output by the voltage sensor 109. Here, the voltage threshold Vth is the target upper limit of the DC voltage of the inverter 103 and is a positive value.

[0027] The duty cycle calculator 11124 takes the calculated value output by the subtractor 11123 and the operating mode determination result output by the operating mode determination unit 1111 as inputs to calculate the duty cycle that will serve as a command to turn the switching element 1073 ON / OFF. The duty cycle output by the duty cycle calculator 11124 is limited to a range of 0 to 1. The duty cycle calculator 11124 is configured, for example, using proportional-integral control. If the operating mode determination result output by the operating mode determination unit 1111 is battery operation mode, the duty cycle calculator 11124 performs the calculation and outputs the result as the duty cycle. On the other hand, if the operating mode determination result output by the operating mode determination unit 1111 is trolley operation mode, the duty cycle calculator 11124 stops the calculation and outputs 0 as the duty cycle.

[0028] The output switch 11125 takes the duty cycle output by the duty cycle calculator 11122, the operating mode determination result output by the operating mode determination unit 1111, and the duty cycle output by the duty cycle calculator 11124 as inputs. When the operating mode determination result is trolley operating mode, it outputs the duty cycle output by the duty cycle calculator 11122, and when the operating mode determination result is battery operating mode, it outputs the duty cycle output by the duty cycle calculator 11124.

[0029] The PWM calculator 11126 takes the duty cycle output by the output switch 11125 as input, compares the duty cycle with the carrier signal, and outputs a gate pulse signal to the switching element 1073.

[0030] Figure 5 shows an example of an operating waveform in the battery operation mode in the first embodiment. In battery operation mode, the DC / DC converter 105 operates in voltage control mode to control the DC voltage of the inverter 103, and normally controls the DC voltage of the inverter 103 to V1.

[0031] Next, when the inverter 103 starts regenerative operation at time T1, the regenerative power regenerated on the DC side of the inverter 103 begins to increase. Since the DC / DC converter 105 attempts to control the DC voltage of the inverter 103 to V1, the regenerative power regenerated on the DC side of the inverter 103 is input to the DC / DC converter 105 and charges the battery 106. Therefore, as the regenerative power regenerated on the DC side of the inverter 103 increases, the input power to the DC / DC converter 105 also increases accordingly.

[0032] Next, let's assume that at time T2, the input power of the DC / DC converter 105 is limited by some condition, and the input power of the DC / DC converter 105 becomes constant at Plim. However, the regenerative power recovered to the DC side of the inverter 103 is increasing, so power equal to the difference between that regenerative power and the input power of the DC / DC converter 105 is generated, and this power is stored on the DC side of the inverter 103. As a result, the DC voltage of the inverter 103 begins to rise, and the voltage detection value detected by the voltage sensor 109 begins to rise.

[0033] Next, at time T3, when the detected DC voltage of the inverter 103 exceeds the voltage threshold Vth, the calculated value output by the subtractor 11123 becomes positive, and the duty cycle output by the duty cycle calculator 11124 begins to increase from 0. In battery operation mode, a gate pulse signal is created from the duty cycle output by the duty cycle calculator 11124 to the switching element 1073 via the output switch 11125 and the PWM calculator 11126. Therefore, as the duty cycle output by the duty cycle calculator 11124 increases, the power discharged by the brake chopper device 107 increases, and the rise in the DC voltage of the inverter 103 begins to be suppressed.

[0034] Next, at time T4, the increase in regenerative power regenerated on the DC side of inverter 103 stops, and the regenerative power becomes constant at P. As the increase in regenerative power stops, the rise in the DC voltage of inverter 103 is further suppressed, and the DC voltage of inverter 103 begins to decrease as the duty cycle output by duty cycle calculator 11124 increases.

[0035] Next, at time T5, the detected DC voltage of the inverter 103 matches the voltage threshold Vth, and the duty cycle output by the duty cycle calculator 11124 becomes constant at d. At this time, the power P-Plim, which is the difference between the power P regenerated on the DC side of the inverter 103 and the input power Plim of the DC / DC converter 105, is consumed by the brake chopper device 107.

[0036] As described above, in battery operation mode, the DC voltage of the inverter 103 can be suppressed to below the voltage threshold Vth by discharging the brake chopper device 107 as the DC voltage of the inverter 103 rises.

[0037] Figure 6 shows an example of the operating waveform in the trolley operation mode in the first embodiment. In trolley operation mode, the DC / DC converter 105 operates in a power control mode that controls the charging and discharging power of the battery 106, and controls the input power of the DC / DC converter 105 to Pch.

[0038] Next, when the inverter 103 starts regenerative operation at time T1, the regenerative power regenerated on the DC side of the inverter 103 begins to increase. The DC / DC converter 105 attempts to control its input power to Pch. Therefore, the power that is insufficient from the regenerative power regenerated on the DC side of the inverter 103 is received from the overhead line 2, and the total power of Pch, consisting of the regenerative power regenerated on the DC side of the inverter 103 and the power received from the overhead line 2, is input to the DC / DC converter 105, and the battery 106 is charged.

[0039] Next, at time T2, when the regenerated power recovered to the DC side of inverter 103 exceeds Pch, power is generated equal to the difference between that regenerated power and the input power of DC / DC converter 105, and this power is reverse-flowed to the overhead line 2 via reactor 102 and pantograph 101. As a result, the current flowing through reactor 102 begins to rise, and the current detection value detected by current sensor 110 begins to rise.

[0040] Next, at time T3, when the detected current value of the current flowing through reactor 102 exceeds the current threshold Ith, the calculated value output by subtractor 11121 becomes positive, and the duty cycle output by duty cycle calculator 11122 begins to increase from 0. In trolley operation mode, a gate pulse signal is created from the duty cycle output by duty cycle calculator 11122 to the switching element 1073 via output switch 11125 and PWM calculator 11126. Therefore, as the duty cycle output by duty cycle calculator 11122 increases, the power discharged by brake chopper device 107 increases, and the rise in current flowing through reactor 102 begins to be suppressed.

[0041] Next, at time T4, the increase in regenerative power regenerated on the DC side of inverter 103 stops, and the regenerative power becomes constant at P. As the increase in regenerative power stops, the rise in current flowing through reactor 102 is further suppressed, and the current flowing through reactor 102 begins to decrease as the duty cycle output by duty cycle calculator 11122 increases.

[0042] Next, at time T5, the detected current value of the current flowing through the reactor 102 matches the current threshold Ith, and the duty cycle output by the duty cycle calculator 11122 becomes constant at d. At this time, the power P-Pch, which is the difference between the power P regenerated on the DC side of the inverter 103 and the input power Pch of the DC / DC converter 105, is consumed by the brake chopper device 107.

[0043] As described above, in trolley operation mode, the brake chopper device 107 discharges as the current flowing through the reactor 102 increases, thereby suppressing the current flowing through the reactor 102 to below the current threshold Ith.

[0044] <Second Embodiment> Next, the second embodiment will be described. Some parts that are similar to those already described may be omitted. Figure 7 shows an example of the configuration of the electric drive vehicle 3 in the second embodiment. The difference from the configuration example of the first embodiment shown in Figure 1 is that a controller 112 is provided instead of controller 111. Aside from this, the configuration examples of the first and second embodiments are identical. The difference between controller 111 and controller 112 will be explained later.

[0045] Figure 8 shows an example configuration of controller 112. Controller 112 includes an operating mode determination unit 1111 and a chopper controller 1122. The difference between controller 111 and controller 112 shown in Figure 3 is that controller 1122 is included instead of chopper controller 1112. Controllers 111 and 112 have the same configuration except for this difference. The differences between chopper controller 1112 and chopper controller 1122 will be described later.

[0046] The operating mode determination unit 1111 determines whether the system is in trolley operation mode or battery operation mode and outputs the determination result. The chopper controller 1122 takes the determination result output by the operating mode determination unit 1111, the voltage detection value detected by the voltage sensor 109, and the current detection value detected by the current sensor 110 as inputs and outputs a gate pulse signal to the brake chopper device 107.

[0047] Figure 9 shows the configuration of the chopper controller 1122. The chopper controller 1122 includes a subtractor 11121, a duty cycle calculator 11122, a subtractor 11123, a duty cycle calculator 11124, an output switch 11125, a PWM calculator 11126, a comparator 11221, and a multiplier 11222. Compared to the configuration of the chopper controller 1112 shown in Figure 4, the comparator 11221 and multiplier 11222 are added.

[0048] The subtractor 11121 outputs a value obtained by subtracting the current threshold Ith from the current detection value output by the current sensor 110. Here, the current threshold Ith is the target upper limit of the current flowing in reverse to the overhead line 2, and is a positive value.

[0049] The comparator 11221 compares the voltage detection value detected by the voltage sensor 109 with the voltage threshold Vth2. It outputs 1 if the voltage detection value exceeds the voltage threshold Vth2, and 0 otherwise. Here, Vth2 is the upper limit of the voltage that the electric vehicle 3 can receive from the trolley overhead line 2, and is a positive value.

[0050] The multiplier 11222 outputs a value obtained by multiplying the output of the subtractor 11121 by the output of the comparator 11221.

[0051] The duty cycle calculator 11122 takes the calculated value output by the multiplier 11222 and the operating mode determination result output by the operating mode determination unit 1111 as inputs to calculate the duty cycle that will serve as a command to turn the switching element 1073 ON / OFF. The duty cycle output by the duty cycle calculator 11122 is limited to a range of 0 to 1. The duty cycle calculator 11122 is configured, for example, using proportional-integral control. If the operating mode determination result output by the operating mode determination unit 1111 is the trolley operating mode, the duty cycle calculator 11122 performs the calculation and outputs the result as the duty cycle. On the other hand, if the operating mode determination result output by the operating mode determination unit 1111 is the battery operating mode, the duty cycle calculator 11122 stops the calculation and outputs 0 as the duty cycle.

[0052] The subtractor 11123 outputs a value obtained by subtracting the voltage threshold Vth from the voltage detection value output by the voltage sensor 109. Here, the voltage threshold Vth is the target upper limit of the DC voltage of the inverter 103 and is a positive value.

[0053] The duty cycle calculator 11124 takes the calculated value output by the subtractor 11123 and the operating mode determination result output by the operating mode determination unit 1111 as inputs to calculate the duty cycle that will serve as a command to turn the switching element 1073 ON / OFF. The duty cycle output by the duty cycle calculator 11124 is limited to a range of 0 to 1. The duty cycle calculator 11124 is configured, for example, using proportional-integral control. If the operating mode determination result output by the operating mode determination unit 1111 is battery operation mode, the duty cycle calculator 11124 performs the calculation and outputs the result as the duty cycle. On the other hand, if the operating mode determination result output by the operating mode determination unit 1111 is trolley operation mode, the duty cycle calculator 11124 stops the calculation and outputs 0 as the duty cycle.

[0054] The output switch 11125 takes the duty cycle output by the duty cycle calculator 11122, the operating mode determination result output by the operating mode determination unit 1111, and the duty cycle output by the duty cycle calculator 11124 as inputs. When the operating mode determination result is trolley operating mode, it outputs the duty cycle output by the duty cycle calculator 11122, and when the operating mode determination result is battery operating mode, it outputs the duty cycle output by the duty cycle calculator 11124.

[0055] The PWM calculator 11126 takes the duty cycle output by the output switch 11125 as input, compares the duty cycle with the carrier signal, and outputs a gate pulse signal to the switching element 1073.

[0056] In the second embodiment, the comparator 11221 and multiplier 11222 are additionally provided for the following reasons. In the first embodiment, when the current flowing through the reactor 102 exceeds the current threshold Ith, the brake chopper device 107 performs a discharge to suppress the current flowing through the reactor 102 to below the current threshold Ith, thereby suppressing the occurrence of reverse power flow from the electric drive vehicle 1 to the overhead line 2. This is because, if there is no load consuming power or energy storage system to store power beyond the overhead line 2, the voltage of the overhead line 2 will rise if reverse power flow occurs, which may cause failure of equipment connected to the overhead line 2.

[0057] However, if there is a power-consuming load or a power storage system at the end of the overhead line 2, it is more efficient to supply the power that would have been discharged to that load or power storage system rather than discharging it with the brake chopper device 107. Even if reverse power flow occurs, if that reverse power flow is supplied to the load or power storage system, the voltage of the overhead line 2 will not rise, and therefore the DC voltage of the inverter 103 will not rise either.

[0058] Therefore, in the second embodiment, a comparator 11221 and a multiplier 11222 are provided to allow reverse power flow to the overhead line 2 as long as the DC voltage of the inverter 103 does not rise. That is, the comparator 11221 determines whether or not the DC voltage of the inverter 103 exceeds the voltage threshold Vth2, and if the DC voltage of the inverter 103 does not exceed the voltage threshold Vth2, the output of the multiplier 11222 remains 0, which in turn causes the output of the duty cycle calculator 11122 to remain 0, thereby suppressing the discharge of the brake chopper device 107.

[0059] Based on the above, in the second embodiment, if there is a load that consumes power or a power storage system that stores power at the end of the overhead line 2, it becomes possible to supply power to them, thereby enabling the effective use of power.

[0060] Figure 10 shows an example of the operating waveform in trolley operation mode in the second embodiment. Note that in the second embodiment, the example of the operating waveform in battery operation mode is the same as the example of the operating waveform in battery operation mode in the first embodiment shown in Figure 5, so the explanation of the battery operation mode in the second embodiment is omitted.

[0061] In trolley operation mode, the DC / DC converter 105 operates in a power control mode that controls the charging and discharging power of the battery 106, and controls the input power of the DC / DC converter 105 to Pch.

[0062] Next, when the inverter 103 starts regenerative operation at time T1, the regenerative power regenerated on the DC side of the inverter 103 begins to increase. The DC / DC converter 105 attempts to control its input power to Pch. Therefore, the power that is insufficient from the regenerative power regenerated on the DC side of the inverter 103 is received from the overhead line 2, and the total power of Pch, consisting of the regenerative power regenerated on the DC side of the inverter 103 and the power received from the overhead line 2, is input to the DC / DC converter 105, and the battery 106 is charged.

[0063] Next, at time T2, when the regenerated power recovered to the DC side of inverter 103 exceeds Pch, power is generated equal to the difference between that regenerated power and the input power of DC / DC converter 105, and this power is reverse-flowed to the overhead line 2 via reactor 102 and pantograph 101. As a result, the current flowing through reactor 102 begins to rise, and the current detection value detected by current sensor 110 begins to rise. However, if there is a power-consuming load or a power storage system at the end of overhead line 2, the voltage of overhead line 2 does not rise, and the DC voltage of inverter 103 maintains the voltage of overhead line 2, which is Vtr.

[0064] Next, at time T3, if the detected current value of the current flowing through reactor 102 exceeds the current threshold Ith, the calculated value output by subtractor 11121 becomes positive. However, the detected DC voltage value of inverter 103 does not exceed the voltage threshold Vth2, maintaining the voltage of overhead line 2, Vtr. Therefore, the output of comparator 11221 is 0, and the output of multiplier 11222 is also 0, so the duty cycle output by duty cycle calculator 11122 remains 0. In trolley operation mode, a gate pulse signal to switching element 1073 is created from the duty cycle output by duty cycle calculator 11122 via output switch 11125 and PWM calculator 11126. Therefore, if the duty cycle output by duty cycle calculator 11122 remains 0, the power discharged by brake chopper device 107 remains 0, and the current flowing through reactor 102 continues to rise as the regenerative power regenerated to the DC side of inverter 103 increases.

[0065] Next, assume that at time T4, the increase in regenerative power regenerated on the DC side of inverter 103 stops, and the regenerative power becomes constant at P. As the increase in regenerative power stops, the increase in the current flowing through reactor 102 stops.

[0066] As described above, in trolley operation mode, if there is a power-consuming load or a power storage system at the end of the overhead line 2, power can be supplied to that load or power storage system without discharging at the brake chopper device 107 or suppressing the current flowing to the reactor 102.

[0067] Figure 11 shows another example of operating waveforms in trolley operation mode in a second embodiment. In trolley operation mode, the DC / DC converter 105 operates in power control mode to control the charging and discharging power of the battery 106, and controls the input power of the DC / DC converter 105 to Pch.

[0068] Next, when the inverter 103 starts regenerative operation at time T1, the regenerative power regenerated on the DC side of the inverter 103 begins to increase. The DC / DC converter 105 attempts to control its input power to Pch. Therefore, the power that is insufficient from the regenerative power regenerated on the DC side of the inverter 103 is received from the overhead line 2, and the total power of Pch, consisting of the regenerative power regenerated on the DC side of the inverter 103 and the power received from the overhead line 2, is input to the DC / DC converter 105, and the battery 106 is charged.

[0069] Next, at time T2, when the regenerated power recovered to the DC side of inverter 103 exceeds Pch, power is generated equal to the difference between that regenerated power and the input power of DC / DC converter 105, and this power is reverse-flowed to the overhead line 2 via reactor 102 and pantograph 101. As a result, the current flowing through reactor 102 begins to rise, and the current detection value detected by current sensor 110 begins to rise.

[0070] Next, at time T3, if the detected current value of the current flowing through reactor 102 exceeds the current threshold Ith, the calculated value output by subtractor 11121 becomes positive. However, the DC voltage of inverter 103 does not exceed the voltage threshold Vth2, maintaining the voltage of overhead line 2, Vtr. Therefore, the output of comparator 11221 is 0, and the output of multiplier 11222 is also 0, so the duty cycle output by duty cycle calculator 11122 remains 0. In trolley operation mode, a gate pulse signal to switching element 1073 is created from the duty cycle output by duty cycle calculator 11122 via output switch 11125 and PWM calculator 11126. Therefore, if the duty cycle output by duty cycle calculator 11122 remains 0, the power discharged by brake chopper device 107 remains 0, and the current flowing through reactor 102 continues to rise as the regenerative power regenerated to the DC side of inverter 103 increases.

[0071] Next, let's assume that at time T4, the voltage of overhead line 2 begins to rise from Vtr, and the DC voltage of inverter 103 also begins to rise.

[0072] At time T5, the increase in regenerative power regenerated on the DC side of inverter 103 stops, and the regenerative power becomes constant at P. As the increase in regenerative power stops, the increase in current flowing through reactor 102 also stops.

[0073] However, as the voltage of overhead line 2 continues to rise, and the DC voltage of inverter 103 exceeds the voltage threshold Vth2 at time T6, the output of comparator 11221 becomes 1, and the calculated value output by multiplier 11222 becomes positive. As a result, the duty cycle output by duty cycle calculator 11122 begins to increase from 0. In trolley operation mode, the gate pulse signal of switching element 1073 is created from the duty cycle output by duty cycle calculator 11122 via output switch 11125 and PWM calculator 11126. As a result, as the duty cycle output by duty cycle calculator 11122 increases, the power discharged by brake chopper device 107 increases, the current flowing to reactor 102 begins to decrease, the rise in voltage of overhead line 2 begins to be suppressed, and the rise in DC voltage of inverter 103 also begins to be suppressed.

[0074] Next, at time T7, the detected current value of the current flowing through the reactor 102 matches the current threshold Ith, the detected voltage value of the DC voltage of the inverter 103 matches the voltage threshold Vth2, and the duty cycle output by the duty cycle calculator 11122 becomes constant at d. At this time, the power P-Pch, which is the difference between the power P regenerated on the DC side of the inverter 103 and the input power Pch of the DC / DC converter 105, is consumed by the brake chopper device 107.

[0075] As described above, in trolley operation mode, if there is no power-consuming load or power storage system beyond the overhead line 2, the brake chopper device 107 discharges in response to the increase in current flowing through the reactor 102 and the increase in the DC voltage of the inverter 103. This suppresses the current flowing through the reactor 102 to below the current threshold Ith and the DC voltage of the inverter 103 to below the voltage threshold Vth2.

[0076] <Third Embodiment> Next, a third embodiment will be described. Content that is similar to what has already been described may be omitted. Figure 12 shows the configuration of the third embodiment of the electric drive vehicle. In this embodiment, instead of the DC / DC converter 105 and battery 106 in the configuration of the first embodiment shown in Figure 1, an AC / DC converter 113 and a generator 114 are provided; otherwise, the configuration is the same. Although not described in this embodiment, the generator 114 generates electricity when driven by an engine or the like. Even with this configuration, similar to the first embodiment, reverse power flow to the overhead line 2 can be suppressed when the electric drive vehicle 4 is connected to the overhead line 2, and the rise in the DC voltage of the inverter 103 can be suppressed when the electric drive vehicle 4 is not connected to the overhead line 2.

[0077] <Fourth Embodiment> Next, the fourth embodiment will be described. Some parts that are the same as those already described may be omitted. Figure 13 shows the configuration of the fourth embodiment of the electric drive vehicle. In this embodiment, instead of the DC / DC converter 105 and battery 106 in the configuration of the second embodiment shown in Figure 7, an AC / DC converter 113 and a generator 114 are provided, but the rest of the configuration is the same. Although not described in this embodiment, the generator 114 generates electricity when driven by an engine or the like. In this configuration as in the second embodiment, when the electric drive vehicle 5 is connected to the overhead line 2 and the voltage of the overhead line 2 rises, reverse power flow to the overhead line 2 can be suppressed, and when the electric drive vehicle 5 is not connected to the overhead line 2, the rise in the DC voltage of the inverter 103 can be suppressed. [Explanation of symbols]

[0078] 1: Electric vehicle 2: Overhead lines 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 1071: Resistor 1072: Diode 1073: Switching element 1074: Diode 1111: Operating mode determination device 1112: Chopper controller 11121: Subtractor 11122: Duty Cycle Calculator 11123: Subtractor 11124: Duty Cycle Calculator 11125: Output switch 11126:PWM calculator 112: Controller 1122: Chopper controller 11221: Comparator 11222: Multiplier 113: AC / DC converter 114: Generator

Claims

1. It is an electric vehicle, Battery and A DC / DC converter that takes the output voltage of the aforementioned battery as input, An inverter that drives an electric motor using the voltage output of the DC / DC converter or the voltage output of the overhead line as input, A brake chopper device comprising a switching element, a resistor, and a diode, connected to the DC side of the inverter, The aforementioned electric vehicle is The conditions under which the switching element operates are switched depending on whether the electric vehicle is connected to the overhead line or not. When the electric-driven vehicle is connected to the overhead line, the switching element operates when the current flowing from the DC side of the inverter to the overhead line exceeds a predetermined value. When the electric vehicle is not connected to the overhead line, the switching element operates when the DC voltage of the inverter is above a predetermined value. An electric vehicle characterized by the following features.

2. It is an electric vehicle, Battery and A DC / DC converter that takes the output voltage of the aforementioned battery as input, An inverter that drives an electric motor using the voltage output of the DC / DC converter or the voltage output of the overhead line as input, A brake chopper device comprising a switching element, a resistor, and a diode, connected to the DC side of the inverter, The aforementioned electric vehicle is The conditions under which the switching element operates are switched depending on whether the electric vehicle is connected to the overhead line or not. When the electric vehicle is connected to the overhead line, the switching element operates when the current flowing from the DC side of the inverter to the overhead line is greater than or equal to a predetermined value and the voltage on the DC side of the inverter is greater than or equal to a predetermined value. When the electric vehicle is not connected to the overhead line, the switching element operates when the DC voltage of the inverter is above a predetermined value. An electric vehicle characterized by the following features.

3. It is an electric vehicle, A generator and An AC / DC converter that takes the output voltage of the aforementioned generator as input, An inverter that drives an electric motor using the voltage output of the AC / DC converter or the voltage output of the overhead line as input, A brake chopper device comprising a switching element, a resistor, and a diode, connected to the DC side of the inverter, The aforementioned electric vehicle is The conditions under which the switching element operates are switched depending on whether the electric vehicle is connected to the overhead line or not. When the electric-driven vehicle is connected to the overhead line, the switching element operates when the current flowing from the DC side of the inverter to the overhead line exceeds a predetermined value. When the electric vehicle is not connected to the overhead line, the switching element operates when the DC voltage of the inverter is above a predetermined value. An electric vehicle characterized by the following features.

4. It is an electric vehicle, A generator and An AC / DC converter that takes the output voltage of the aforementioned generator as input, An inverter that drives an electric motor using the voltage output of the AC / DC converter or the voltage output of the overhead line as input, A brake chopper device comprising a switching element, a resistor, and a diode, connected to the DC side of the inverter, The aforementioned electric vehicle is The conditions under which the switching element operates are switched depending on whether the electric vehicle is connected to the overhead line or not. When the electric vehicle is connected to the overhead line, the switching element operates when the current flowing from the DC side of the inverter to the overhead line is greater than or equal to a predetermined value and the voltage on the DC side of the inverter is greater than or equal to a predetermined value. When the electric vehicle is not connected to the overhead line, the switching element operates when the DC voltage of the inverter is above a predetermined value. An electric vehicle characterized by the following features.

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