JP2006340419A - Hybrid vehicle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To protect a maintenance worker against an electric shock during maintenance work and to prevent the waste of power stored in a secondary battery. <P>SOLUTION: Since an interruption switch 9 is turned off when a vehicle is stopped, a rated voltage VB (e.g. 400 V) of a secondary battery 6 is not applied to a smoothing capacitor 3 and the voltage across the smoothing capacitor 3 becomes zero. Consequently, a maintenance worker has no risk of an electric shock during maintenance work and power stored in a secondary battery 6 is not wasted. When operation is started, an interruption switch control means 12 receives detection signals from voltage detectors 10 and 11 and turns the interruption switch 9 on when the voltage of the smoothing capacitor 3 exceeds a voltage of the secondary battery 6. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a hybrid vehicle using a fuel cell as a power generation means and a secondary battery as a power storage means.

  A fuel cell is intended to generate electrical energy by power generation based on an electrochemical reaction between hydrogen and oxygen, and has recently attracted attention as a next-generation energy supply source. This is because the fuel cell discharges only water during power generation and does not generate vibration or noise, so it is environmentally friendly, and the fuel cell can be extracted from various sources such as natural gas and methanol. By having the merit of.

  There is a hybrid vehicle that uses a fuel cell as an energy supply source. A hybrid vehicle is a vehicle equipped with a plurality of types of energy supply sources, and a well-known hybrid vehicle is a hybrid vehicle using two types of energy supply sources, gasoline, a fuel cell, and a secondary battery. Furthermore, recently, the performance of fuel cells has been greatly improved, and the development of a hybrid system has been promoted not only for small vehicles such as automobiles, but also for large vehicles of the railway vehicle class.

  A hybrid vehicle according to such a large vehicle usually employs a configuration in which a fuel cell is a power generation means and a secondary battery is a power storage means (see, for example, Patent Document 1). Secondary batteries are used as power storage means because it is difficult to quickly obtain the required driving force when accelerating or climbing with a fuel cell alone, and it is necessary to save energy based on the storage of regenerative power Because there is.

  FIG. 10 is a configuration diagram of a conventional hybrid vehicle using a fuel cell as a power generation means and a secondary battery as a power storage means. In this figure, DC power generated by the fuel cell 1 as power generation means is output to the fuel cell converter 2. The fuel cell converter 2 is a step-up chopper type DC / DC converter, and includes a switching element (for example, IGBT) S1 in which a reactor L1, a diode D1, and a diode D2 are connected in antiparallel.

  The DC power output from the fuel cell converter 2 is supplied to the motor control inverter 4 via the smoothing capacitor 3 and is converted into AC power that has been subjected to variable voltage and variable frequency control. The AC power output from the motor control inverter 4 is supplied to the wheel driving motor 5.

  Further, the DC power from the secondary battery 6 as the power storage means is output to the secondary battery converter 7. The secondary battery converter 7 is a step-up / step-down chopper type DC / DC converter, and includes a reactor L2, a switching element S2 in which a diode D3 is connected in antiparallel, and a switching element S3 in which a diode D4 is connected in antiparallel. ing. The DC power output from the secondary battery converter 7 is also supplied to the motor control inverter 4 via the smoothing capacitor 3.

  Further, the operation control unit 8 outputs control signals (gate signals) to the switching elements S1 to S3 of the fuel cell converter 2 and the secondary battery converter 7 and the semiconductor switching elements constituting the motor control inverter 4. Then, the operation control of the motor 5 is performed.

  Next, the operation of FIG. 10 will be described. Now, the hybrid vehicle is stopped, and the switching elements S1 to S3 are turned off. At this time, if the secondary battery 6 is charged to the rated voltage VB (for example, 400 V), the voltage VB is applied to both ends of the smoothing capacitor 3 even though the hybrid vehicle is not operating.

  When an operator turns on an operation start button (not shown) on the operation panel, the fuel cell 1 starts an electrochemical reaction between hydrogen and oxygen based on a predetermined activation sequence program. As a result, DC power starts to be output from the fuel cell 1, and after a while, the voltage of the smoothing capacitor 3 exceeds the rated voltage VB of the secondary battery 6 and is supplied to the smoothing capacitor 3 side via the reactor L1 and the diode D1. The rated voltage VFC (for example, 500 V) of the fuel cell 1 is obtained.

  The operation control unit 8 outputs a control signal based on the operation of the operator, causes the motor control inverter 4 to perform variable voltage variable frequency control, and performs speed control of the motor 5. At this time, if the voltage of the smoothing capacitor 3 corresponding to the rated operating speed is larger than the rated voltage of the fuel cell 1 (for example, 600 V) and the operator performs an acceleration operation, the operation control unit 8 controls the fuel cell converter 2. To perform step-up chopper control. That is, the operation control unit 8 turns on and off the switching element S1, and discharges the electric energy accumulated in the reactor L1 when the switching element S1 is turned on through the diode D1 as a free-wheeling diode when the switching element S1 is turned off. The voltage of 3 is raised to 600V.

  Further, when the motor 5 is operated at a high output, the fuel cell output is insufficient, and the voltage of the smoothing capacitor 3 cannot be maintained at 600 V by the boost chopper control using only the fuel cell converter 2. No. 8 performs the step-up chopper control for the secondary battery converter 7 as well. That is, the operation control unit 8 turns on and off the switching element S3, and discharges the electric energy accumulated in the reactor L2 when the switching element S3 is turned on through the diode D3 as a freewheeling diode when the switching element S3 is turned off. The voltage of 3 is raised to 600V.

  Even when the load fluctuation is large, the reaction speed of the fuel cell 1 is slow, and the voltage of the smoothing capacitor 3 cannot be maintained at 600 V. Therefore, the same control as described above is performed.

  In addition, when performing regenerative operation when the vehicle is decelerating or traveling downhill, the operation control unit 8 performs step-down chopper control on the secondary battery converter 7. That is, the operation control unit 8 turns the switching element S2 on and off, and the electric energy accumulated in the reactor L2 when the switching element S2 is turned on passes to the secondary battery 6 side through the diode D4 as a reflux diode when the switching element S2 is turned off. By discharging, the regenerative power from the motor control inverter 4 side is stored in the secondary battery 6.

When the driver operates the operation start button on the operation panel to stop the operation of the hybrid vehicle, the supply of hydrogen to the fuel cell 1 is stopped, so that the output voltage of the fuel cell 1 gradually increases. It will eventually drop to zero. Therefore, the voltage of the smoothing capacitor 3 is also reduced to the voltage VB applied by the secondary battery 6, that is, 400V.
JP 2003-199203 A

  As described above, in the configuration of FIG. 10, the rated voltage VB of the secondary battery 6 is always applied to the smoothing capacitor 3 even when the operation of the vehicle is stopped. In the case of a small hybrid vehicle such as an automobile, the value of the voltage VB is such that the maintenance worker does not accidentally touch the charged portion because the system is configured as a unit. However, in the case of a large hybrid vehicle such as a railway vehicle, there are many charged parts because the parts are scattered and arranged in various places. Therefore, there is a risk that an electric shock accident may occur when the maintenance worker inadvertently touches the body where the voltage is applied during the maintenance work.

  In addition, even when the operation is stopped, the rated voltage VB of the secondary battery 6 is always applied to the smoothing capacitor 3 when the power stored in the secondary battery 6 is in some circuits. It means that it is wasted by electric parts. Although such power consumption is not large, it becomes a level that cannot be ignored over a long period of time, which is against the demand for energy saving.

  The present invention has been made in view of the above circumstances, and provides a hybrid vehicle capable of preventing an electric shock accident during maintenance work by a maintenance worker and preventing waste of stored power in a secondary battery. It is an object.

  As means for solving the above-mentioned problems, the invention according to claim 1 uses a fuel cell as a power generation means, a secondary battery as a power storage means, and direct current power from the fuel cell and the secondary battery is a fuel cell. In a hybrid vehicle that is DC / DC converted by a converter for a secondary battery and a converter for a secondary battery and then supplied to a motor control inverter via a smoothing capacitor, the connection state between the secondary battery and the smoothing capacitor is turned on. A shutoff switch for turning on or off, a smoothing capacitor voltage detecting means for detecting the voltage of the smoothing capacitor, a secondary battery voltage detecting means for detecting the voltage of the secondary battery, and the shutoff during operation stop Whether the level of the detection signal from the smoothing capacitor voltage detection means is the secondary battery voltage detection means during the operation with the switch turned off. Characterized in that and a cut-off switch control means for turning on state the blocking switch on condition that exceeds the level of the detection signal.

  According to a second aspect of the present invention, in the first aspect of the present invention, the cutoff switch is interposed between the secondary battery converter and the smoothing capacitor.

  According to a third aspect of the invention, in the first aspect of the invention, the cutoff switch is interposed between the secondary battery and the secondary battery converter.

  According to a fourth aspect of the present invention, in the first aspect of the invention, the cutoff switch includes a first cutoff switch interposed between the secondary battery converter and the smoothing capacitor, and the secondary battery. And the secondary battery converter. The second cutoff switch is interposed between the secondary battery converter and the secondary battery converter.

  According to a fifth aspect of the invention, in the invention according to any one of the first to fourth aspects, an overcurrent prevention fuse is interposed between the secondary battery and the smoothing capacitor. To do.

  According to the present invention, since the shut-off switch control means turns off the shut-off switch while the operation is stopped, it is possible to prevent an electric shock accident during maintenance work of a maintenance worker and waste of stored power of the secondary battery. . When the operation is performed, the shutoff switch control means does not turn on the shutoff switch unless the voltage of the smoothing capacitor exceeds the voltage of the secondary battery. Therefore, an inrush current may flow into the smoothing capacitor when the shutoff switch is turned on. Can be avoided.

  FIG. 1 is a configuration diagram of a hybrid vehicle according to a first embodiment of the present invention. In addition, the same code | symbol is attached | subjected about the component similar to FIG. 10, and the overlapping description is abbreviate | omitted.

  The configuration of FIG. 1 differs from the configuration of FIG. 10 in that a cutoff switch 9 is inserted between the collector side of the switching element S2 and one end side of the smoothing capacitor 3, and the smoothing capacitor 3 has a smoothing capacitor voltage. The point that the voltage detector 10 as the detection means is connected in parallel, the point that the voltage detector 11 as the voltage detection means for the secondary battery is connected in parallel to the secondary battery 6, and the operation control unit 8A is the cutoff switch The control means 12 is provided. However, the voltage detectors 10 and 11 are also provided in a conventional hybrid vehicle, and are not shown in FIG.

  The shut-off switch control means 12 turns off the shut-off switch 9 during operation stop, and the level of the detection signal from the voltage detector 10 exceeds the level of the detection signal from the voltage detector 11 during operation. Control is performed to turn on the cutoff switch 9 only when the switch is on.

  Next, the operation of FIG. 1 will be described. Now, assuming that the hybrid vehicle is not operating, since the cutoff switch 9 is in an off state, the rated voltage VB (for example, 400 V) of the secondary battery 6 is not applied to the smoothing capacitor 3, and the voltage across the both ends Becomes zero. Therefore, there is no fear that the maintenance worker may cause an electric shock during the maintenance work, and the stored power of the secondary battery 6 is prevented from being wasted.

  Then, as already described in FIG. 10, when the operator operates the operation start button (not shown) on the operation panel to turn on, the fuel cell 1 starts to output DC power based on a predetermined activation sequence program, This is supplied to the smoothing capacitor 3 side via the reactor L1 and the diode D1. Therefore, the voltage across the smoothing capacitor 3 gradually increases.

  At this time, the cut-off switch control means 12 receives detection signals from the voltage detectors 10 and 11 and compares the voltage level of the smoothing capacitor 3 with the voltage level of the secondary battery 6. When the voltage level of the smoothing capacitor 3 exceeds the voltage level of the secondary battery 6, the cutoff switch control means 12 switches the cutoff switch 9 to the on state.

  Since the voltage of the smoothing capacitor 3 exceeds the voltage level of the secondary battery 6, the voltage of the smoothing capacitor 3 does not change even if the cutoff switch 9 is switched to the ON state. However, since the cut-off switch 9 is switched to the ON state, the voltage of the smoothing capacitor 3 can be rapidly increased based on the subsequent boost chopper control of the secondary battery converter 7 as in the case of FIG. Is in place.

  Here, let us consider a case where the cutoff switch 9 is turned on before the voltage of the smoothing capacitor 3 exceeds the voltage of the secondary battery 6. For example, when the power generation of the fuel cell 1 has just started, the voltage of the smoothing capacitor 3 is significantly lower than the voltage of the secondary battery 6, so the inrush current from the secondary battery 6 is on the smoothing capacitor 3 side. Therefore, the semiconductor elements such as the diode D3 are destroyed. In addition, after a certain amount of time has passed since the power generation of the fuel cell 1 is started, the difference between the voltage of the smoothing capacitor 3 and the voltage of the secondary battery 6 becomes small, so that a large inrush current from the secondary battery 6 is smoothed. Although it does not flow into the capacitor 3 side and the semiconductor element is not destroyed, a certain amount of current still flows in, so that the stored power of the secondary battery 6 is still wasted.

  However, in the configuration of FIG. 1, the cutoff switch control means 12 performs control to turn on the cutoff switch 9 when the voltage level of the smoothing capacitor 3 exceeds the voltage level of the secondary battery 6 as described above. Therefore, it is possible to reliably prevent an inrush current from flowing into the smoothing capacitor 3 from the secondary battery 6 and waste of the stored power of the secondary battery 6.

  As described above, the voltage of the smoothing capacitor 3 becomes the rated voltage VFC (for example, 500 V) of the fuel cell 1 after a while after the cutoff switch 9 is switched to the ON state. The subsequent operation is the same as that in FIG.

  Then, when the driver operates the operation start button on the operation panel to turn off the vehicle to stop driving, the cutoff switch control means 12 performs switching so that the cutoff switch 9 is turned off again. Moreover, since the supply of hydrogen to the fuel cell 1 is stopped by turning off the operation start button, the output voltage of the fuel cell 1 gradually decreases to zero. Therefore, the voltage of the smoothing capacitor 3 is also zero.

  As described above, according to the configuration of FIG. 1, the shutoff switch control means 12 turns off the shutoff switch 9 while the operation is stopped. Therefore, an electric shock accident during maintenance work by the maintenance worker and accumulation of the secondary battery 6 are performed. It is possible to prevent waste of electric power. When the operation is performed, the cutoff switch control means 12 does not turn on the cutoff switch 9 unless the voltage of the smoothing capacitor 3 exceeds the voltage of the secondary battery 6. It is possible to prevent the electric power from flowing into the third side and the stored power of the secondary battery 6 from being wasted during operation.

  FIG. 2 is a configuration diagram of a hybrid vehicle according to the second embodiment of the present invention. 2 differs from FIG. 1 in that the cutoff switch 13 is interposed between the positive side of the secondary battery 6 and one end side of the reactor L2 constituting the secondary battery converter 7. .

  In the configuration of FIG. 1, the shut-off switch 9 is in an off state during operation stop, so the secondary battery 6 and the secondary battery converter 7 are completely disconnected from the main circuit side. However, since the voltage of the secondary battery 6 is applied to the reactor L2, the switching element S3, and the diode D4, the stored power of the secondary battery 6 is wasted although it is small. Therefore, in this second embodiment, such a waste of stored power can be prevented by inserting the cutoff switch 13 between the secondary battery 6 and the secondary battery converter 7. A possible configuration is adopted. The operation in FIG. 2 is substantially the same as that in FIG.

  FIG. 3 is a configuration diagram of a hybrid vehicle according to the third embodiment of the present invention. The configuration shown in FIG. 3 includes two switches, a cutoff switch 9 in FIG. 1 and a cutoff switch 13 in FIG. In the configuration of FIG. 1 or FIG. 2, when a short-circuit failure in which contacts are welded to the cutoff switch 9 or the cutoff switch 13, it is possible to ensure safety during maintenance work and prevent waste of stored power. It becomes impossible.

  Therefore, in the present embodiment, a configuration in which the possibility of falling into the above situation is reduced by providing the two cutoff switches 9 and 13 is adopted. According to the present embodiment, even if a short-circuit failure occurs in one of the cutoff switches 9 and 13, if the other is normal, safety during maintenance work is ensured and waste of stored power is prevented. It is possible.

  FIG. 4 is a configuration diagram of a hybrid vehicle according to the fourth embodiment of the present invention. 4 differs from FIG. 1 in that an overcurrent prevention fuse F1 is connected to the cutoff switch 9. FIG. According to the configuration shown in FIG. 4, it is possible to prevent the secondary battery 6 from being destroyed by an overcurrent when a short circuit failure occurs in the switching element S2.

  As described above, the configuration in which the overcurrent prevention fuse is added to the configuration of FIG. FIGS. 5 to 9 are configuration diagrams of hybrid vehicles according to fifth to ninth embodiments of the present invention. Compared to the configuration of FIG. 1 in which the cutoff switch 9 is provided, at least one of the fuses F1 to F3. One or more are added.

  4 to 9 show various modes in which the overcurrent prevention fuses F1 to F3 are added to the configuration of FIG. 1 in which the cutoff switch 9 is provided. Of course, the cutoff switch 13 is provided. The overcurrent prevention fuse may be added in various manners to the configuration of FIG. 2 or the configuration of FIG. 3 in which two cutoff switches 9 and 13 are provided.

1 is a configuration diagram of a hybrid vehicle according to a first embodiment of the present invention. The block diagram of the hybrid vehicle which concerns on the 2nd Embodiment of this invention. The block diagram of the hybrid vehicle which concerns on the 3rd Embodiment of this invention. The block diagram of the hybrid vehicle which concerns on the 4th Embodiment of this invention. The block diagram of the hybrid vehicle which concerns on the 5th Embodiment of this invention. The block diagram of the hybrid vehicle which concerns on the 6th Embodiment of this invention. The block diagram of the hybrid vehicle which concerns on the 7th Embodiment of this invention. The block diagram of the hybrid vehicle which concerns on the 8th Embodiment of this invention. The block diagram of the hybrid vehicle which concerns on the 9th Embodiment of this invention. The block diagram of the conventional hybrid vehicle.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Fuel cell 2 Fuel cell converter 3 Smoothing capacitor 4 Motor control inverter 5 Motor 6 Secondary battery 7 Secondary battery converter 8, 8A Operation control part 9 Cutoff switch 10 Voltage detector (voltage detection means for smoothing capacitor)
11 Voltage detector (secondary battery voltage detection means)
12 Shut-off switch control means 13 Shut-off switch L1, L2 Reactor S1-S3 Switching element D1-D4 Diode

Claims (5)

A fuel cell is used as a power generation means, a secondary battery is used as a storage means, and direct current power from the fuel cell and the secondary battery is DC / DC converted by a fuel cell converter and a secondary battery converter, respectively, and then smoothed. In a hybrid vehicle that is supplied to an inverter for motor control via a capacitor,
A cutoff switch for turning on or off the connection state between the secondary battery and the smoothing capacitor;
Smoothing capacitor voltage detecting means for detecting the voltage of the smoothing capacitor;
Secondary battery voltage detection means for detecting the voltage of the secondary battery;
The shut-off switch is turned off during operation stop, and the level of the detection signal from the smoothing capacitor voltage detection means exceeds the detection signal level from the secondary battery voltage detection means during operation. As a cutoff switch control means for turning on the cutoff switch as
A hybrid vehicle characterized by comprising: The cut-off switch is interposed between the secondary battery converter and the smoothing capacitor.
The hybrid vehicle according to claim 1. The cutoff switch is interposed between the secondary battery and the secondary battery converter.
The hybrid vehicle according to claim 1. The cutoff switch includes a first cutoff switch interposed between the secondary battery converter and the smoothing capacitor, and a first cutoff switch interposed between the secondary battery and the secondary battery converter. It consists of two cutoff switches,
The hybrid vehicle according to claim 1. An overcurrent prevention fuse is interposed between the secondary battery and the smoothing capacitor.
The hybrid vehicle according to claim 1, wherein the hybrid vehicle is a vehicle.

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