JP2008259282A - Power supply device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To effectively use power loss by a discharge circuit in a power supply device where a smoothing capacitor is connected to a power line. <P>SOLUTION: The discharge circuit 30 is connected in parallel to a capacitor C2 between a power line LN1 and a ground line LN2. The discharge circuit 30 is constituted of an electric load driven by discharge power from the capacitor C2. The electric load comprises a cooling fan for cooling a power control unit 20. The cooling fan is driven by discharge power from the capacitor C2 at operation time of an AC motor M1 and is driven to consume charge accumulated in the capacitor C2 at operation stop time of the AC motor M1. Thus, power loss which is regularly generated in the discharge circuit 30 connected to the capacitor C2 in parallel is effectively used and cooling performance of the power supply device 100 can be improved while the power line LN1 is securely discharged and safety is secured. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a power supply device, and more particularly to a power supply device having a smoothing capacitor connected to a power line.

  There is a type of power supply apparatus in which DC power supplied from a DC power supply such as a battery is once converted by a semiconductor power converter, and the converted power is used for driving and controlling a load. In this type of power supply device, a configuration in which a smoothing capacitor for stabilizing an input voltage to a semiconductor power converter is connected between a power supply line and an earth line is common (see, for example, Patent Document 1). .

Therefore, in such a power supply device, for safety reasons, it is necessary to reliably discharge the power supply line in which the electric power stored in the smoothing capacitor is left when power supply to the load is stopped. Conventionally, for such a discharge process, a configuration in which a discharge path for residual charges of a smoothing capacitor is secured by connecting a discharge resistor in parallel to the smoothing capacitor has been studied.
JP-A-2-13266

  However, in the above-described discharge treatment using the discharge resistance, a discharge path due to the discharge resistance is always formed, so that steady power loss occurs. The generated power loss is merely converted to thermal energy by the discharge resistance as Joule heat due to the discharge current.

  Therefore, the present invention has been made to solve such a problem, and an object of the present invention is to effectively use power loss by a discharge circuit in a power supply device having a configuration in which a smoothing capacitor is connected to a power line. It is.

  According to the present invention, a power supply device includes a power source, a power line provided between the first electric load driven by power from the power source and the power source, a capacitor connected to the power line, and the capacitor in parallel. And a discharge circuit connected to form a discharge path for charges accumulated in the capacitor. The discharge circuit includes a second electric load driven by discharge power from the capacitor.

  According to the above-described power supply device, by configuring the discharge circuit with an electric load, it is possible to effectively use the power loss that is constantly generated in the conventional discharge resistor as a driving force source for the electric load.

  Preferably, the power supply device further includes a power converter for converting the power of the power line into power for driving and controlling the first electric load. The second load includes a cooling device configured to be able to supply a cooling medium to the power converter.

  According to the above power supply device, by configuring the discharge circuit with a cooling device, it is possible to effectively use the power loss that has been constantly generated in the conventional discharge resistance, and to improve the cooling capacity of the power supply device. it can.

  Preferably, the power supply device further includes a case for accommodating the capacitor and the power converter. The cooling device is configured to receive a discharge power from the capacitor and circulate the cooling medium in the case.

  According to the power supply device described above, the cooling capacity of the capacitor and the power converter that generate heat during operation can be improved.

  Preferably, the second electric load includes display means configured to display that the discharge process from the power line is completed in response to the discharge power from the capacitor being lower than a predetermined reference voltage.

  According to the power supply device described above, by configuring the discharge circuit with display means for displaying the completion of the discharge process, it is possible to effectively utilize the power loss that has been steadily generated in the conventional discharge resistance, and Safety can be improved.

  According to the present invention, in a power supply apparatus having a configuration in which a smoothing capacitor is connected to a power line, it is possible to effectively improve the cooling capacity and safety of the apparatus by effectively using power loss due to the discharge circuit.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In the drawings, the same reference numerals indicate the same or corresponding parts.

[Embodiment 1]
FIG. 1 is a schematic block diagram of a power supply device according to Embodiment 1 of the present invention. The power supply apparatus 100 controls driving of an AC motor M1 shown as a representative example of an electric load.

  Referring to FIG. 1, power supply device 100 includes a battery B, system relays SMR1 and SMR2, and a power control unit 20 for controlling driving of AC motor M1.

  AC motor M1 is a drive motor for generating torque for driving drive wheels of a hybrid vehicle or an electric vehicle. Alternatively, this motor has a function as a generator driven by an engine, and operates as an electric motor for the engine, for example, can be incorporated into a hybrid vehicle so that the engine can be started. May be.

  The battery B is made of a secondary battery such as nickel metal hydride or lithium ion. Voltage sensor 10 detects battery voltage Vb output from battery B, and outputs the detected battery voltage Vb to control device 40.

  System relays SMR1 and SMR2 are connected between battery B and power supply line LN1 and ground line LN2, respectively. Control device 40 controls conduction / non-conduction of system relays SMR1 and SMR2.

  Power control unit 20 includes a boost converter 12, a capacitor C 2, a voltage sensor 13, an inverter 14, a current sensor 24, a control device 40, and a discharge circuit 30.

  Boost converter 12 includes a reactor L1, transistors Q1 and Q2, and diodes D1 and D2.

  Transistors Q1 and Q2 are connected in series between power supply line LN1 and ground line LN2. Between the collectors and emitters of the transistors Q1 and Q2, diodes D1 and D2 for flowing current from the emitter side to the collector side are respectively connected. Reactor L1 has one end connected to system relay SMR1 and the other end connected to an intermediate point between transistors Q1 and Q2.

  Capacitor C2 is connected between power supply line LN1 and ground line LN2, and smoothes the DC voltage on power supply line LN1. The DC voltage smoothed by the capacitor C2 becomes the input voltage of the inverter 14. Voltage sensor 13 detects the voltage across capacitor C2, that is, output voltage Vm of boost converter 12, and outputs the detected output voltage Vm to control device 40.

  Inverter 14 includes a U-phase arm 15, a V-phase arm 16, and a W-phase arm 17. U-phase arm 15, V-phase arm 16, and W-phase arm 17 are provided in parallel between power supply line LN1 and ground line LN2.

  U-phase arm 15 includes transistors Q3 and Q4 connected in series, V-phase arm 16 includes transistors Q5 and Q6 connected in series, and W-phase arm 17 includes transistors Q7 and Q8 connected in series. . Further, diodes D3 to D8 for flowing current from the emitter side to the collector side are connected between the collectors and emitters of the transistors Q3 to Q8, respectively.

  An intermediate point of each phase arm is connected to each phase end of each phase coil of AC motor M1. That is, AC motor M1 is a three-phase permanent magnet motor, and is configured by connecting three U, V, and W phase coils in common at the midpoint, and the other end of the U phase coil is intermediate between transistors Q3 and Q4. At the point, the other end of the V-phase coil is connected to an intermediate point between the transistors Q5 and Q6, and the other end of the W-phase coil is connected to an intermediate point between the transistors Q7 and Q8.

  Discharge circuit 30 is connected between power supply line LN1 and ground line LN2, and is provided to ensure a discharge path from power supply line LN1 to ground line LN2. The configuration of the discharge circuit 30 will be described later.

  The control device 40 includes a torque command value TR and a motor rotational speed MRN inputted from an externally provided ECU (Electronic Control Unit), a battery voltage Vb from the voltage sensor 10, an output voltage Vm from the voltage sensor 13, and a current. Based on the motor current MCRT from the sensor 24, a signal PWMC for driving the boost converter 12 and a signal PWMI for driving the inverter 14 are generated, and the generated signals PWMC and PWMI are respectively used for the boost converter 12 and the inverter. 14 to output.

  Boost converter 12 boosts the DC voltage supplied from battery B according to the period in which transistor Q2 is turned on by signal PWMC from control device 40, and supplies the boosted voltage to capacitor C2. Boost converter 12 steps down DC voltage supplied from inverter 14 and charges battery B according to the period in which transistor Q1 is turned on by signal PWMC.

  Thus, boost converter 12 boosts the DC voltage from battery B and steps down the DC voltage from inverter 14, and thus has a bidirectional converter function.

  When the DC voltage is supplied from the capacitor C2, the inverter 14 converts the DC voltage into an AC voltage based on the signal PWMI from the control device 40 and drives the AC motor M1. As a result, AC motor M1 is driven so as to generate torque specified by torque command value TR.

  The inverter 14 converts the AC voltage generated by the AC motor M1 into a DC voltage based on the signal PWMI from the control device 40 during regenerative braking of the hybrid vehicle or electric vehicle on which the power supply device 100 is mounted, and the conversion The DC voltage thus supplied is supplied to the boost converter 12 via the capacitor C2.

  In addition, the control device 40 generates a signal DRV for controlling the driving of the discharge circuit 30 by a method described later and outputs the signal DRV to the discharge circuit 30.

Next, the configuration of the discharge circuit 30 in FIG. 1 will be described.
First, for comparison, a discharge resistor provided for securing a discharge path for residual charges of a smoothing capacitor in a conventional power supply device will be described.

FIG. 2 is a diagram for explaining a discharge resistance provided in a conventional power supply device.
Referring to FIG. 2, discharge resistor 32 is provided in parallel with capacitor C2 between power supply line LN1 and ground line LN2, and forms a discharge path for residual charges in capacitor C2.

  Specifically, when an operation stop command for AC motor M1, which is an electric load, is issued from an external ECU, system relays SMR1 and SMR2 are first rendered non-conductive by control device 40. Thereby, the power supply from the battery B to the power control unit 20 is stopped.

  Further, the discharge operation by the inverter 14 is started so as to consume the electric charge stored in the capacitor C2 at this time. In such a discharge operation, the control device 40 controls on / off of the transistors Q3 to Q8 so that current flows in a direction in which the inverter 14 does not generate torque in the AC motor M1.

  In parallel with the discharge operation by the inverter 14, the residual charge in the capacitor C2 is discharged by the discharge resistor 32 through the discharge resistor 32 provided between the power supply line LN1 and the ground line LN2. In addition, since the inverter 14 cannot operate normally, when the discharge operation by the inverter 14 is not performed normally, the residual charge of the capacitor C2 is discharged through the discharge resistor 32.

  As described above, when a problem such as abnormal operation of the inverter 14 or the control device 40 occurs by forming a discharge path between the power supply line LN1 to be discharged when the electric load is stopped and the ground line LN2. In addition, when the operation of the electric load is stopped, the power supply line LN1 can be reliably discharged to ensure safety.

  On the other hand, as shown in FIG. 2, in the power supply device having the configuration in which the discharge resistor 32 is connected in parallel to the capacitor C <b> 2, a discharge path is always formed by the discharge resistor 32. Flows. As a result, power loss in the discharge resistor 32 is steadily generated. The generated power loss is converted into thermal energy as Joule heat generated in the discharge resistor 32.

  That is, when the power supply device 100 drives the AC motor M1 in the power running mode, the inverter 14 receives a DC voltage from the capacitor C2 via the discharge resistor 32, so that a part of the electric power accumulated in the capacitor C2 is part of the discharge resistor 32. It is discharged by. Further, when the power supply device 100 drives the AC motor M1 in the regeneration mode, the inverter 14 converts the AC voltage generated by the AC motor M1 into a DC voltage, and the converted DC voltage is connected to the capacitor C2 via the discharge resistor 32. Therefore, a part of the generated power is consumed by the discharge resistor 32. Then, the discharge power when the AC motor M1 is driven in the power running mode or the regenerative mode is converted into thermal energy by the discharge resistor 32.

  Thus, in the power supply device in which the discharge circuit is configured by the discharge resistor 32, the power loss generated in the discharge circuit is simply converted into thermal energy by the discharge resistor 32. This power loss Does not have a way to use it effectively.

  Therefore, in the power supply device according to the present embodiment, as a means for effectively using the power loss generated in the discharge circuit, the discharge circuit is configured by an electric load that is driven by the discharge power from the capacitor C2.

  That is, the electric load is connected in parallel with the capacitor C2, and is driven by the discharge power from the capacitor C2 when the AC motor M1 is operated. When the operation of AC motor M1 is stopped, the electric load is driven so as to consume the electric charge stored in capacitor C2. As a result, the power supply line LN1 can be surely discharged to ensure safety.

  In the present embodiment, from the viewpoint of distinguishing between the electric load constituting the discharge circuit 30 and the electric load (for example, AC motor M1) driven by the power supply device described above, the above-described electric load is referred to as “first electric load”. The electrical load constituting the discharge circuit 30 is also referred to as a “second electrical load”.

FIG. 3 is a diagram for explaining the discharge circuit 30 according to the present embodiment.
Referring to FIG. 3, discharge circuit 30 includes a cooling fan 50 for cooling power control unit 20. The cooling fan 50 is not particularly limited as long as it generates cooling air. For example, in the present embodiment, a blower that generates wind power by rotation of a rotary blade is applied. The rotating blade is rotated by supplying electric power from a fan circuit 54 to a motor 52 having the rotating blade fixed to the rotating shaft.

  The motor 52 is made of, for example, a three-phase AC rotating electric machine. The fan circuit 54 has an inverter (not shown) for driving and controlling the motor 52. The inverter converts the DC power supplied from the capacitor C2 into AC power according to the signal DRV from the control device DRV, and supplies the AC power to the motor 52.

  Current sensor 58 detects a discharge current Id flowing through discharge circuit 30 and outputs the detected discharge current Id to control device 40. Voltage sensor 13 detects voltage Vm across capacitor C2 (corresponding to the output voltage of boost converter 12), and outputs the detected voltage Vm to control device 40.

  When control device 40 receives discharge current Id from current sensor 58 and voltage Vm across capacitor C2 from voltage sensor 13, discharge power calculated from the product of discharge current Id and voltage Vm is below a predetermined threshold. The discharge current Id is controlled so that The control device 40 generates a signal DRV for driving and controlling the inverter of the fan circuit 54 based on the power deviation between the discharge power and a predetermined threshold, and outputs the generated signal DRV to the fan circuit 54. Thus, the power control unit 20 is cooled by the cooling fan 50 while ensuring the power utilization rate of the power supply device 100.

FIG. 4 is a sectional view showing the power control unit 20 on which the discharge circuit 30 of FIG. 3 is mounted.
The case of the power control unit 20 is configured to be divided into a case 104 and a case 102. Case 104 is a part that mainly accommodates capacitor C <b> 2, and case 102 is a part that mainly accommodates boost converter 12 and inverter 14.

  The case 102 and the case 104 are integrated by fixing flanges provided at respective end portions with bolts or the like.

  The case 104 is provided with an opening for assembling the boost converter 12 and the inverter 14. A heat sink 114 is attached to the bottom surface of the case 104. Boost converter 12 and inverter 14 are arranged on the upper surface of heat sink 114. Each transistor and diode in boost converter 12 and inverter 14 are fixed to heat sink 222 (and insulating substrate) disposed on heat sink 114.

  The heat sink 114 has a plurality of cooling fins 106. A gap formed between the cooling fin 106 and the bottom surface of the case 104 constitutes a water passage for cooling water supplied to the power control unit 20. As the cooling water flows through the gaps in the direction perpendicular to the paper surface, the transistor and the diode are cooled via the heat sink 222.

  Case 102 accommodates capacitor C2, cooling fan 50 constituting discharge circuit 30, control board 110, capacitor bus bar 118, and inverter bus bar 116.

  A capacitor bus bar 118 is attached to the end of the capacitor C2 so as to ensure conduction with the capacitor element. The end of the capacitor bus bar 118 is fastened to the end of the inverter bus bar 116 with a bolt or the like. A control board 110 constituting the control device 40 (FIG. 1) is attached to the inverter bus bar 116.

  The cooling fan 50 is connected to the capacitor C <b> 2 by the bus bar 112. The cooling fan 50 is driven by receiving power from the capacitor C2 via the bus bar 112. At this time, the cooling air generated by the rotation of the motor 52 of the cooling fan 50 is sent to the inverter 14, the boost converter 12, and the capacitor C2. At this time, the heat exchange with the cooling air is performed to cool inverter 14, boost converter 12 and capacitor C2. The cooling air warmed by heat exchange is circulated through a gap in the case to be cooled with the case as a heat radiation destination, and then blown again to the inverter 14 and the like through the cooling fan 50.

  As described above, according to the first embodiment of the present invention, since the discharge circuit is configured by the cooling fan driven by the discharge power from the smoothing capacitor, the power loss that has been constantly generated in the discharge resistance is achieved. The cooling capacity of the power control unit can be improved by effectively using

[Modification]
FIG. 5 is a diagram for explaining a modification of the discharge circuit 30 shown in FIG.

  Referring to FIG. 5, discharge circuit 30A is obtained by adding resistance element 56 connected between fan circuit 54 and power supply line LN1 to discharge circuit 30 of FIG. Therefore, detailed description of overlapping portions will not be repeated.

  The resistance element 56 is provided to adjust the level of voltage supplied as a power source from the power supply line LN1 to the fan circuit 54 of the cooling fan 50. That is, since the voltage of the power supply line LN1 is boosted to a high voltage by the boost converter 12, the purpose is to step down to a voltage level appropriate for the power supply of the fan circuit 54 via the resistance element 56.

  Note that when a discharge current flows through the resistance element 56, Joule heat is generated in the resistance element 56 and the element temperature rises. However, the resistance element 56 is also cooled by heat exchange with the cooling air blown from the cooling fan 50. Therefore, the cooling capacity of the power control unit 20 is ensured.

[Embodiment 2]
FIG. 6 is a diagram for explaining a discharge circuit according to Embodiment 2 of the present invention.

  FIG. 7 is a cross-sectional view showing the power control unit 20 on which the discharge circuit 30B of FIG. 6 is mounted.

  Referring to FIG. 6, discharge circuit 30B includes a resistance element 62 and an indicator lamp 60 connected in series between power supply line LN1 and ground line LN2.

  As shown in FIG. 7, the indicator lamp 60 is outside the cases 102 and 104 that house the power control unit 20, and is turned on / off by an operator who performs maintenance and inspection of the vehicle on which the power supply device 100 is mounted. It is provided at an identifiable position. In FIG. 7, the indicator lamp 60 is installed on the outer surface of the case 102. However, the indicator lamp 60 may be installed near the driver's seat in the passenger compartment.

  The indicator lamp 60 is lit by receiving a voltage from the power supply line LN1 via the resistance element 62. Then, in response to the voltage of the power supply line LN1 being lower than a predetermined reference voltage at which the operation of the indicator lamp 60 is guaranteed, the indicator lamp 60 is switched from the on state to the off state.

  Therefore, in the discharge process of the power supply line LN1, when the residual charge of the capacitor C2 is discharged through the discharge circuit 30 and the voltage of the power supply line LN1 falls below a predetermined reference voltage, the indicator lamp 60 is turned off.

  By making the predetermined reference voltage at this time coincide with a predetermined voltage level indicating that the residual charge of the capacitor C2 has been discharged, the operator identifies that the indicator lamp 60 has been turned off, and discharges. It can be determined that the processing has been completed. Thereby, the safety | security with respect to the high voltage of the operator who maintains and inspects the power control unit 20 can be improved further.

  In addition, the indicator lamp 60 is kept in the lighting state by receiving the voltage from the power supply line LN1 during the operation of the AC motor M1. Therefore, even when the AC motor M1 is in operation, when the indicator lamp 60 is turned off, it can be determined that a failure such as disconnection has occurred in the discharge circuit 30B.

  As described above, according to the second embodiment of the present invention, the discharge circuit is constituted by the indicator lamp that is turned on / off according to the voltage level of the power supply line, so that the discharge resistance is constantly generated. The power loss can be effectively utilized to improve the safety of the power control unit.

  In the first and second embodiments, the cooling fan and the indicator lamp are disclosed as the electric loads constituting the discharge circuit. However, in the unlikely event that the cooling fan and the indicator lamp fail, the discharge process of the power line LN1 is performed. In order to ensure, as shown in FIG. 8, it is good also as a structure which further provides the discharge resistance 320 in parallel with the discharge circuit 30 (or 30A, 30B). In this configuration, the discharge resistor 320 has a sufficiently higher resistance value than the discharge circuit 30.

  The embodiment disclosed this time should be considered as illustrative in all points and not restrictive. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

It is a schematic block diagram of the power supply device by Embodiment 1 of this invention. It is a figure for demonstrating the discharge resistance provided in the conventional power supply device. It is a figure for demonstrating the discharge circuit by Embodiment 1 of this invention. It is sectional drawing which shows the power control unit carrying the discharge circuit of FIG. It is a figure for demonstrating the modification of the discharge circuit shown in FIG. It is a figure for demonstrating the discharge circuit by Embodiment 2 of this invention. It is sectional drawing which shows the power control unit carrying the discharge circuit of FIG. It is a figure for demonstrating the modification of the discharge circuit by Embodiment 1 and 2 of this invention.

Explanation of symbols

  10, 13 Voltage sensor, 12 Boost converter, 14 Inverter, 15 U-phase arm, 16 V-phase arm, 17 W-phase arm, 20 Power control unit, 24 Current sensor, 30, 30A, 30B Discharge circuit, 32, 320 Discharge resistance , 40 control device, 50 cooling fan, 52 motor, 54 fan circuit, 56, 62 resistance element, 58 current sensor, 60 indicator light, 100 power supply device, 102, 104 case, 106 cooling fin, 110 control board, 112 bus bar, 114 heat sink, 116 inverter bus bar, 118 capacitor bus bar, 222 heat sink, B battery, C2 capacitor, D1-D8 diode, L1 reactor, LN1 power line, LN2 ground line, M1 AC motor, Q1-Q8 transistor SMR1, SMR2 system relay.

Claims (4)

Power supply,
A power line provided between a first electrical load driven by power from the power source and the power source;
A capacitor connected to the power line;
A discharge circuit connected in parallel with the capacitor and forming a discharge path for the charge accumulated in the capacitor;
The discharge circuit includes a second electric load driven by discharge power from the capacitor. A power converter for converting the power of the power line into power for driving and controlling the first electrical load;
The power supply device according to claim 1, wherein the second load includes a cooling device configured to be able to supply a cooling medium to the power converter. A case for accommodating the capacitor and the power converter;
The power supply device according to claim 2, wherein the cooling device is configured to receive the discharge power from the capacitor and circulate the cooling medium in the case.   The second electrical load includes display means configured to display that the discharge process from the power line is completed in response to the discharge power from the capacitor being lower than a predetermined reference voltage. The power supply device according to claim 1.

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