JP2012029481A - Power supply device for electric vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the performance of a power supply device for an electric vehicle in practical operating conditions by changing the protection set value of overcurrent according to the environmental conditions for using the power supply device for the electric vehicle.SOLUTION: The power supply device for the electric vehicle includes: an inverter for converting DC electric power into AC electric power; and a control part for controlling the inverter. The control part includes: means (S104, S105) for changing the overcurrent interruption and protection level of an inverter output current according to the input voltage of the inverter; and a means for stopping the inverter when the output current reaches the changed overcurrent interruption and protection level.

Description

  The present invention relates to a technique for protecting a power supply device for an electric vehicle.

  In general, in an electric vehicle power supply device, electric power is received from an overhead line, and electric power such as lighting and an air conditioner is supplied to the electric vehicle. This electric vehicle power supply device converts a DC voltage into an AC voltage by switching a semiconductor switching device such as an IGBT at a high frequency.

  Generally, the environmental conditions of the electric vehicle power supply device vary as follows.

-Fluctuation of input voltage When the 1500Vdc rating is used, the input voltage (overhead voltage) varies greatly from 900V to 2400V.

-Fluctuation of load (output current) For example, when rated load = 100%, there is a case where the load is almost 0% and a state where the load is 100%. Sometimes it is about 150% of the rating only for a short time when the load is applied.

-Fluctuation in ambient temperature Since the electric vehicle power supply device is generally mounted under the floor of the electric vehicle, it depends on the external environment temperature. That is, the temperature varies greatly, such as 40 ° C in summer and -10 ° C in winter.

  In general, when detecting the maximum voltage, maximum current, or maximum temperature to detect the input voltage, output current, ambient temperature + temperature due to self-heating, etc. as a power supply device for electric vehicles, Stop the device to avoid destruction.

  As a power supply device for an electric vehicle, it is common to determine a protection level such as a current in consideration of the case where all conditions are maximum (worst) values.

  Electric vehicle power supplies rarely operate at maximum / worst conditions. Therefore, it is possible to increase the protection level and expand the operating conditions (improvement of performance) as the electric vehicle power supply device by combining each condition.

  In the present invention, the use environment condition of the electric vehicle power supply device is used as an input condition, and the protection set value is changed and improved by the control unit according to the input condition. The purpose is to improve performance.

  An electric vehicle power supply device according to an embodiment of the present invention includes an inverter that converts DC power into AC power, and a control unit that controls the inverter, the control unit corresponding to an input voltage of the inverter. And means for changing the overcurrent cutoff protection level of the inverter output current and means for stopping the inverter when the output current reaches the changed overcurrent cutoff protection level.

  The protection set value is changed or improved in accordance with the use environment condition of the electric vehicle power supply device, and the performance of the electric vehicle power supply device in the actual operating condition is improved.

It is a figure which shows the main circuit structure of the power supply device for electric vehicles to which this invention is applied. It is a figure which shows the terminal voltage Vc and element current Ic at the time of switching IGBT17. 3 is a flowchart showing the operation of the first embodiment. 10 is a flowchart illustrating the operation of the third embodiment. 10 is a flowchart illustrating the operation of the fourth embodiment. It is a figure which shows an overload protection characteristic. 10 is a flowchart showing the operation of the fifth embodiment.

  Embodiments of an electric vehicle power supply apparatus according to the present invention will be described below with reference to the drawings.

  FIG. 1 is a diagram showing a main circuit configuration of an electric vehicle power supply device to which the present invention is applied. In the following description, the rated input voltage of this power supply apparatus is 1500 V.

  DC power is supplied from a substation (not shown) to the electric vehicle power supply device (SIV) 20 through the overhead line 1 and the pantograph 2. The electric vehicle power supply device 20 converts this DC power into, for example, 50 Hz, 440 V three-phase AC power, and supplies AC power to a load such as an air conditioner. The power supply device 20 is grounded via a wheel 21.

  In the electric vehicle power supply device 20, the electric power supplied from the overhead wire is supplied to the inverter 8 through the contactor 3, the DC filter reactor 4, and the charging switch (CHS) unit 16. A DC filter capacitor (FC) 7 is connected in parallel to the DC terminal of the inverter 8. The CHS unit 16 includes an FC charging resistor 5 and an FC charging resistor short-circuit switch CHS6. When charging the filter capacitor 7 at the time of startup, an overhead wire voltage is supplied to the filter capacitor 7 through the resistor 5 for a certain period of time in order to suppress an inrush current. After the filter capacitor 8 is charged, the resistor 9 is short-circuited by the short-circuit switch CHS6.

  The three-phase AC terminal of the inverter 8 is connected to the primary side of the transformer 10 via an AC filter reactor 9 and an AC filter capacitor 12, respectively. The secondary side of the transformer 10 is connected to a load. The control unit 11 controls the switching operation of the inverter 8 based on the detection value of the DC voltage detector 13, the temperature detector 14, or the output current detector 15, and executes the protection operation of the power supply device 20 according to the present invention. To do.

  Next, the switching surge voltage of the IGBT 17 constituting the inverter 8 will be described.

  FIG. 2 is a diagram showing a terminal voltage and an element current of the IGBT 17 when the IGBT 17 is switched from the ON state to the OFF state. As an example, the rated current Ia of the IGBT 17 is 800 A, the rated voltage Va is 3300 V, and the maximum value of the overhead wire voltage is 2400 V. In FIG. 2, it is assumed that the maximum overhead line voltage is 2400 V, and the IGBT 17 is in the ON state and the rated 800 A flows. The terminal voltage of the IGBT 17 is a voltage Vc detected by the voltage detector 13, and the IGBT element current is a current Ic detected by the current detector 15.

  When an OFF gate command (Vg = 0) is input at time t0, the device current Ic of the IGBT 17 becomes 0 at time t2 after a predetermined time. At this time, a surge voltage Vs is generated between the terminals of the IGBT 17 due to inductance components of the input circuit of the inverter 8 and the output circuit of the load. Accordingly, the terminal voltage Vc becomes a voltage Vsh (= 2400 V + Vs) that is higher than the input voltage 2400 V by the surge voltage Vs at time t1. The rated voltage Va of the IGBT 17 is selected to be equal to or higher than this voltage Vsh. At this time, the margin Vm in the off state is a difference between the element rated voltage Va and the input voltage, that is, 900 V (= 3300-2400). That is, when the IGBT 17 having a rated current of 800 A flows at the maximum input (overhead line) voltage of 2400 V, a surge voltage up to 900 V is allowed.

  For example, when the input voltage is 1500 V, the surge voltage Vs can be allowed up to 1800 V (= 3300 V-1500 V). In this case, the IGBT 17 can pass a rated current of 800 A or more. In this embodiment, the current limit value of the IGBT 17 is set to a large value in accordance with the decrease in the input voltage.

  Next, the operation of the electric vehicle power supply device 20 according to the present invention will be described.

  When the voltage of the overhead line 1 is high, that is, when the input voltage of the electric vehicle power supply device (SIV) 20 is high (2400V to 1800V), the overcurrent cutoff protection level is set to 100% of the rated current Ia (corresponding to the conventional protection level) ). The overcurrent cutoff protection level indicates the maximum cutoff current value with respect to the input voltage of each IGBT constituting the inverter 8. When the current value of the overcurrent cutoff protection level is Ibl, when the input voltage is 2400V to 1800V as described above, Ibl is a rated current (Ibl = Ia). The conventional overcurrent cutoff protection level is a constant value (rated current) over the entire input voltage. In the present embodiment, when the input voltage is in a normal continuous rating of 1800V to 900V, the overcurrent protection level is increased in inverse proportion to the input voltage.

  FIG. 3 is a flowchart illustrating the logical operation of the control unit 11 according to the first embodiment.

  When the input voltage detected by the voltage detector 13 is 1800 V or higher (Yes in step S101), the control unit 11 sets the protection level to 100%, that is, the rated current Ia as described above.

  When the input voltage is less than 1800 V and 900 V or more (Yes in step S103), the control unit 11 determines the overcurrent protection level as follows so that the protection level increases in inverse proportion to the input voltage.

[(1800−input voltage) / 900] × 20% + 100% (1)
This overcurrent cutoff protection level is represented by the current value Ibl as follows.

Ibl = [(1800−input voltage) / 900] × 0.2 + Ia (2)
When the input voltage is less than 900 V (No in step S103), the control unit 11 determines the protection level as 120% of the rated current Ia (Ibl = 1.2 × Ia).

  When the inverter output current detected by the current detector 15 reaches the overcurrent protection level that changes corresponding to the input voltage even for a moment, the control unit 11 opens the contactor 3 and turns off all the IGBTs 17 of the inverter 8. The gate command is output and the device is stopped.

  As described above, according to the present embodiment, the overcurrent withstand capability is improved in the substantial normal operation range where the input voltage is less than 1800 V and 900 V or more, so that the performance of the apparatus is improved.

  Next, a second embodiment of the present invention will be described. The apparatus configuration of the second embodiment is the same as that of the first embodiment.

  In Example 2, the output current limit protection level is varied according to the input voltage (overhead voltage). The output current limit protection level corresponds to a current value that the IGBT can tolerate only for a predetermined short time such as 0.5 seconds, and is obtained based on the power loss of the IGBT. Thus, the output current limit protection level is represented by the current limit value and its duration, and is set to prevent the IGBT and circuit wiring from being destroyed by overheating. Assuming that the current limit value of the output current limit protection level is Icl, in the case of an IGBT with a rated current of 800 A as described above, Icl is conventionally a constant value over the entire input voltage, for example, about 720 A.

  Next, the operation of the second embodiment will be described with reference to FIG.

  As in the first embodiment, when the input voltage of the SIV 20 is high (2400V to 1800V) (Yes in step S201), the control unit 11 sets the output current limit protection level of the inverter 8 to 100% as in step S202 (conventional). The protection level). Let Iclh be the current limit value of the output current limit protection level when the input voltage is high (Icl = Iclh).

  When the input voltage is at a normal continuous rating of 1800 V to 900 V (Yes in step S203), the output current limit protection level is varied as follows in inverse proportion to the input voltage.

[(1800−input voltage) / 900] × 20% + 100% (3)
This is represented by the current limit value Icl as follows.

Icl = [(1800−input voltage) / 900] × 0.2 + Iclh (4)
When the inverter output current detected by the current detector 15 substantially maintains the current limit value Icl for 0.5 seconds, for example, the control unit 11 opens the contactor 3 and turns off all the IGBTs 17 of the inverter 8. The gate command is output and the device is stopped.

  As described above, according to the present embodiment, the load inrush current resistance is improved in the substantial normal operation range, and thus the performance of the apparatus is improved.

  Next, a third embodiment of the present invention will be described. The apparatus configuration of the third embodiment is the same as that of the first embodiment.

  In the third embodiment, the above-described output current limit protection level is changed according to the IGBT temperature of the inverter. As described above, the current limit protection level is represented by the current limit value and its duration. This current limit value is Idl here, and the current limit value Idl is changed according to the IGBT temperature. The duration is constant.

  FIG. 4 is a flowchart showing the operation of the third embodiment.

  The control unit 11 monitors the IGBT temperature in the inverter 8 detected by the temperature detector 14 of FIG. 1, and when the IGBT temperature is high (eg, 90 ° C. or higher) (Yes in Step 201), the output current as in Step S202. The limit protection level is set to 100% (corresponding to the conventional protection level). The current limit value when the temperature is high is Idlh (Idl = Idlh). The current limit value Idlh when this temperature is high is, for example, 720A as described above.

  When the IGBT temperature is lower than 90 ° C. and 40 ° C. or higher (Yes in step S203), the output current limit value protection level is raised as follows according to the temperature as in step S204.

[(90-IGBT temperature) / 50] × 20% + 100% (5)
This is represented by the current limit value Idl as follows.

Idl = [(90−IGBT temperature) / 900] × 0.2 + Idlh (6)
When the IGBT temperature is low (less than 40 ° C.) (No in step S203), the protection level is set to 120% (Idl = 1.2 × Idlh) as in step S205.

  When the inverter output current detected by the current detector 15 substantially maintains the current limit value Idl continuously for 0.5 seconds, for example, the control unit 11 opens the contactor 3 and turns off all the IGBTs 17 of the inverter 8. The gate command is output and the device is stopped.

  As described above, according to the present embodiment, the load inrush current resistance, that is, the current limit value of the IGBT is improved in the substantial operating temperature range, so that the performance of the apparatus is improved.

  Next, a fourth embodiment of the present invention will be described. The apparatus configuration of the fourth embodiment is the same as that of the first embodiment.

  In the fourth embodiment, the current limit protection detection time Tal is varied according to the IGBT temperature of the inverter. The current limit protection detection time element Tal indicates an allowable duration of the output current limit value. In Examples 2 and 3, the current limit protection detection time element Tal is, for example, constant for 0.5 seconds, but in Example 4, this time element Tal is extended as the IGBT temperature decreases. The output current limit value is a constant value (for example, 720 A) over the entire temperature range of the IGBT.

  FIG. 5 is a flowchart showing the operation of the fourth embodiment.

  Similarly to the third embodiment, when the IGBT temperature is high (90 ° C. or higher) (Yes in Step S301), the control unit 11 sets the current level when detecting the current limit protection to 100% as in Step S302 (conventional protection level). Hits). The value of the protection detection time element at this time is Talh [seconds] (Tal = Talh). The protection detection time Talh when the temperature is high is, for example, 0.5 seconds.

  When the IGBT temperature is lower than 90 ° C. and 40 ° C. or higher (Yes in step S303), the protection detection time level is extended as follows according to the temperature drop as in step S304.

[(90-IGBT temperature) / 50] × 50% + 100% (7)
This is represented by the protection detection time element Tal as follows.

Tal = [(90−IGBT temperature) / 50] × 0.5 + Talh (8)
When the IGBT temperature is low (less than 40 ° C.) (No in step S303), the protection level is set to 150% (= 1.5 × Talh) as in step S305.

  When the inverter output current detected by the current detector 15 substantially maintains the output current limit value continuously during the protection detection time Tal, the control unit 11 opens the contactor 3 and all the IGBTs 17 of the inverter 8. An off gate command is output to, and the device is stopped.

  As described above, according to the present embodiment, the load inrush current resistance is improved in the substantial operating temperature range, so that the performance of the apparatus is improved.

  Next, a fifth embodiment of the present invention will be described. The apparatus configuration of the fifth embodiment is the same as that of the first embodiment.

  In the fifth embodiment, the overload protection detection time element is varied according to the IGBT temperature of the inverter. FIG. 6 is a diagram showing overload protection characteristics. The vertical axis is the allowable duration (element when detecting overload protection), and the horizontal axis is the load capacity. The inverter has an allowable duration corresponding to the load capacity. 100% of the horizontal axis indicates the rated load capacity, for example, 200 kVA. The allowable duration at this time is infinite. In this example, the allowable duration is 50 seconds when the rating is 110%, 25 seconds when the rating is 120%, and 10 seconds when the rating is 150%. This allowable duration is referred to as overload protection detection time element. In the present embodiment, as the IGBT temperature of the inverter is changed from a high temperature to a low temperature, this overload protection detection time element is extended.

  The operation of the fifth embodiment will be described with reference to FIG.

  As in the case of the fourth embodiment, when the IGBT temperature is high (90 ° C. or higher) (Yes in step S301), the raw level during overload protection detection is set to 100% (corresponding to the conventional protection level) as in step S302. FIG. 6 shows the element characteristic at the time of overload protection detection at this time. That is, when the load capacity is 110%, 120%, and 150% of the rating, the overload protection detection time is 50 seconds, 25 seconds, and 10 seconds, respectively.

  When the IGBT temperature is lower than 90 ° C. and 40 ° C. or higher (Yes in step S303), the overload protection detection time level is extended as follows according to the temperature drop as in step S304.

[(90-IGBT temperature) / 50] × 50% + 100% (9)
When the IGBT temperature is low (less than 40 ° C.) (No in step S303), the raw level during detection of overload protection is set to 150% as in step S305. That is, when the load capacity is 110%, 120%, and 150% of the rating, the overload protection detection time is set to 75 seconds, 37.5 seconds, and 15 seconds, respectively.

  The control unit 11 detects the current load capacity and IGBT temperature, and when the inverter load capacity exceeds the rating and the state exceeds the corresponding overload protection detection time, the contactor 3 is opened and the inverter An OFF gate command is output to all 8 IGBTs 17 and the apparatus is stopped.

  As described above, according to the present embodiment, the overload capability is improved in the substantial operating temperature range, so that the performance of the apparatus is improved.

  Next, a sixth embodiment of the present invention will be described. The apparatus configuration of the sixth embodiment is the same as that of the first embodiment.

  In the sixth embodiment, the standby time Tbl of the FC resistor 5 is varied according to the operating time of the power supply device. The standby time Tbl of the FC resistor 5 indicates a waiting time for preventing the FC resistor from being heated when the power supply device is restarted.

  The FC charging resistor 5 has a high temperature immediately after startup because a current flows at startup. However, after the startup, the FC charging resistor 5 is short-circuited by the CHS 6, so that no current flows and the temperature is lowered by radiating heat. Go. In addition, when some protection operation occurs in the SIV 20 and the apparatus stops, the FC charging resistor 5 becomes high temperature again at the time of restart.

  When a protective operation occurs immediately after startup, a certain standby time is provided before restarting so that the heat resistance range of the FC charging resistor 5 is not exceeded, and this standby time is set to 100% (conventional standby) Time). The value of the standby time at this time is defined as a standby time Talh [min] at a high temperature.

  FIG. 7 is a flowchart showing the operation of the sixth embodiment.

  If the power supply device 20 is activated and its operating time is, for example, less than 30 minutes (No in step S401), the standby time Tal is set to 100%, that is, Talh (Tal = Talh). When a certain time (for example, 30 minutes) has elapsed since the start (Yes in Step S401), and when it is assumed that the temperature of the FC charging resistor 5 has decreased, standby is performed when protection occurs as in Step S402. The time is shortened to 20%, for example (Tal = Talh × 0.2).

  According to the present embodiment, the power supply stop time to the load is shortened in the substantial operation range, so that the performance of the apparatus is improved.

  The above description is an embodiment of the present invention, and does not limit the apparatus and method of the present invention, and various modifications can be easily implemented. The present invention can be applied not only to a power supply device but also to a VVVF inverter for driving an electric motor. Further, the detectors such as the voltage detector 13, the current detector 15, and the inverter temperature detector 14 can all be those provided in the conventional power supply device.

  DESCRIPTION OF SYMBOLS 1 ... Overhead wire, 2 ... Pantograph, 3 ... Contactor, 4 ... DC filter reactor, 5 ... FC charging resistor, 6 ... FC charging resistor short circuit switch (CHS), 7 ... DC filter capacitor (FC), 8 ... Inverter Part (main circuit), 9 ... AC filter reactor, 10 ... Transformer, 20 ... Electric vehicle power supply (SIV), 12 ... AC filter capacitor.

Claims (5)

Comprising an inverter for converting DC power to AC power, and a control unit for controlling the inverter;
The controller is
Means for changing an overcurrent cutoff protection level of the inverter output current according to an input voltage of the inverter;
An electric vehicle power supply device comprising means for stopping the inverter when the output current of the inverter reaches the changed overcurrent cutoff protection level. Comprising an inverter for converting DC power to AC power, and a control unit for controlling the inverter;
The controller is
Means for changing the current limit value of the output current limit protection level of the inverter represented by a current limit value and its duration according to the input voltage of the inverter;
An electric vehicle power supply device comprising means for stopping the inverter when the output current of the inverter reaches the changed output current limit protection level. Comprising an inverter for converting DC power to AC power, and a control unit for controlling the inverter;
The controller is
Means for changing the current limit value of the output current limit protection level of the inverter represented by a current limit value and its duration according to the switching element temperature of the inverter;
An electric vehicle power supply device comprising means for stopping the inverter when the output current reaches the changed output current limit protection level. Comprising an inverter for converting DC power to AC power, and a control unit for controlling the inverter;
The controller is
Means for changing the duration of the output current limit protection level of the inverter represented by a current limit value and its duration according to the switching element temperature of the inverter;
An electric vehicle power supply device comprising means for stopping the inverter when the output current of the inverter reaches the output current limit protection level. Comprising an inverter for converting DC power to AC power, and a control unit for controlling the inverter;
The controller is
Means for changing an overload protection time element indicating an allowable duration at the time of overload according to the switching element temperature of the inverter;
An electric vehicle power supply device comprising means for stopping the inverter when a load capacity of the inverter reaches the changed overload protection detection time.

Images