JP2008283840A - Power system, control method therefor, and vehicle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To eliminate damages in an inverter, in a power system equipped with: a motor, the inverter for driving the motor; and a step-up converter to boost a voltage from a battery and to supply it to a driving circuit. <P>SOLUTION: The power system 20 has: inverters 11, 12 for driving the motors MG1, MG2; a step-up converter 30 to boost the voltage of a battery 22 and to supply it to the inverters 11, 12; and a smoothing capacitor 42 connected in parallel with the inverters 11, 12 in sight of the step-up converter 30. In the power system 20, a resistor 43 is provided as connected in parallel with the inverters 11, 12. The voltage at the step-up side is thereby lowered by interrupting the step-up converter 30 and the inverters 11, 12 in gate to discharge the resistor 43 when the voltage at the step-up side of the converter 30 is turned to an overvoltage, resulting in eliminating the damages in the inverters 11, 12. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a power system, a control method therefor, and a vehicle.

Conventionally, this type of power system includes a first motor, a second motor, first and second inverters for driving the first and second motors, a DC power supply, two transistors and each transistor in parallel. A boost converter having two connected diodes and a coil attached between two transistors, and a smoothing capacitor for smoothing the boosted voltage, and power generated by the first motor and power from a DC power source Have been proposed to drive the second motor (see, for example, Patent Document 1).
JP 2004-112883 A

  In the power system described above, an overvoltage may occur in the power line connecting the boost converter and the inverter for some reason, and it is recognized as a general problem to protect the converter and the inverter from such an overvoltage. As a method of protecting the inverter from such an overvoltage, there is a method of lowering the voltage of the power line by temporarily shutting off the gate of the boost converter and driving the motor with the inverter. In this method, the allowable voltage is applied to the inverter for a short time. If a voltage exceeding is applied, the inverter may be damaged.

  A power system, a control method thereof, and a vehicle according to the present invention include a drive device, a drive circuit that drives the drive device, a DC power source that can be charged and discharged, and a booster that can boost the voltage of the DC power source and supply the voltage to the drive circuit. In a power system including a converter, a main object is to suppress damage to a drive circuit.

  The power system, the control method thereof, and the vehicle according to the present invention employ the following means in order to achieve the main object described above.

The power system of the present invention is
Driving equipment,
A drive circuit for driving the drive device;
A chargeable / dischargeable DC power supply,
A boost converter capable of boosting the voltage of the DC power supply and supplying the boosted voltage to the drive circuit;
A smoothing capacitor connected in parallel to the drive circuit as seen from the boost converter and smoothing the boost side voltage of the boost converter;
A discharge element capable of discharging the charge accumulated in the smoothing capacitor;
Step-up voltage detecting means for detecting the step-up voltage of the step-up converter;
When the boost side voltage detected by the boost side voltage detection means exceeds the allowable voltage allowed for the drive circuit, the drive circuit and the boost converter operate until the boost side voltage drops and reaches the allowable voltage. Control means for controlling the drive circuit and the boost converter to stop the operation,
It is a summary to provide.

  In the power system of the present invention, a discharge element capable of discharging the electric charge accumulated in the smoothing capacitor is provided. When the boost side voltage of the boost converter exceeds the allowable voltage allowed for the drive circuit, the boost side voltage is The drive circuit and the boost converter are controlled so that the drive circuit and the boost converter stop operating until they reach the allowable voltage. When the boost side voltage exceeds the allowable voltage allowed for the drive circuit and the operations of the drive circuit and the boost converter are stopped, the charge accumulated in the smoothing capacitor is discharged by the discharge element, and the boost side voltage drops. Since the voltage on the boost side can be lowered without operating the drive circuit, it is possible to prevent the drive circuit from being damaged by applying an excessive voltage to the drive circuit. Here, the “discharge element” includes a resistance element.

  In such a power system of the present invention, the control means is configured so that the drive circuit and the boost converter stop operating until the boost side voltage detected by the boost side voltage detection means reaches the normal operating voltage. And a means for controlling the boost converter.

  Further, in the power system according to the present invention, the control means may be configured such that when the predetermined time elapses after the boost side voltage detected by the boost side voltage detection means exceeds the allowable voltage, the boost side voltage is the normal operation. It may be a means for controlling the drive circuit and the boost converter when the voltage is reached. In this way, even when a failure occurs in the boost side voltage detecting means due to the boost side voltage exceeding the allowable voltage, it is possible to suppress damage to the drive circuit due to application of an excessive voltage.

  The vehicle according to the present invention includes the power system according to any one of the above-described aspects, that is, basically the driving device, the driving circuit that drives the driving device, the DC power source that can be charged / discharged, and the DC A step-up converter capable of boosting the voltage of the power supply and supplying it to the drive circuit, a smoothing capacitor connected in parallel to the drive circuit as seen from the boost converter and smoothing the boost side voltage of the boost converter, and storing in the smoothing capacitor A discharge element capable of discharging the generated charge, a boost side voltage detecting means for detecting a boost side voltage of the boost converter, and an allowance for allowing the drive circuit to accept the boost side voltage detected by the boost side voltage detecting means When the voltage exceeds, the drive circuit and the boost converter stop the operation of the drive circuit and the boost converter until the boost side voltage drops to reach the allowable voltage. Control means for controlling the converter, is equipped with a power output system comprising, a gist further comprising a motor capable of outputting power for driving as the driving device.

  In the vehicle of the present invention, since the power system of the present invention according to any one of the aspects described above is mounted, the effect of the power system of the present invention, for example, the effect of suppressing damage to the drive circuit, etc. Similar effects can be achieved.

The power system control method of the present invention includes:
Drive device, drive circuit for driving the drive device, chargeable / dischargeable DC power supply, boost converter capable of boosting the voltage of the DC power supply and supplying it to the drive circuit, and the drive circuit as seen from the boost converter A smoothing capacitor connected in parallel to smooth the boost side voltage of the boost converter, and a discharge element capable of discharging the charge accumulated in the smoothing capacitor,
When the boost side voltage of the boost converter exceeds the allowable voltage allowed for the drive circuit, the drive circuit and the boost converter until the boost side voltage drops and reaches the normal operation voltage at which the drive circuit can normally operate. The gist is to control the drive circuit and the boost converter so as to stop the operation.

  In this power system control method of the present invention, when the boost side voltage of the boost converter exceeds the allowable voltage allowed for the drive circuit, the drive circuit and the boost converter operate until the boost side voltage drops to reach the allowable voltage. The drive circuit and the boost converter are controlled to stop. When the operation of the drive circuit and the boost converter is stopped when the boost side voltage exceeds the allowable voltage allowed for the drive circuit, the charge accumulated in the smoothing capacitor is discharged by the discharge element, and the boost side voltage drops. Since the voltage on the boost side can be lowered without operating the drive circuit, it is possible to prevent the drive circuit from being damaged by applying an excessive voltage to the drive circuit. Here, the “discharge element” includes a resistance element.

  Next, the best mode for carrying out the present invention will be described using examples.

  FIG. 1 is a configuration diagram showing an outline of a configuration of an in-vehicle power system 20 as an embodiment of the present invention. As shown in the figure, the power system 20 of the embodiment includes two motors MG1 and MG2 that output driving power, inverters 11 and 12 that drive the motors MG1 and MG2, a battery 22 as a DC power source, a battery The boosting converter 30 boosts the voltage 22 and supplies it to the inverters 11 and 12 side, or lowers the voltage on the inverters 11 and 12 side and supplies it to the battery 22 side. A smoothing capacitor 42 that is connected in parallel and smoothes the boost side voltage, a resistance element 43 that is connected in parallel to the inverters 11 and 12 as viewed from the boost converter 30 and can discharge the electric charge accumulated in the smoothing capacitor 42, and the boost converter 30 A smoothing capacitor 46 connected in parallel to the battery 22 and smoothing the voltage before boosting; Comprising an electronic control unit 50 which controls the a.

  Motors MG1 and MG2 are both configured as well-known synchronous generator motors that can be driven as generators and can be driven as motors, and exchange power with battery 22 via inverters 11 and 12 and boost converter 30. Do.

  The inverters 11 and 12 supply a phase current for forming a rotating magnetic field to the three-phase coils (U-phase, V-phase, and W-phase) of the motors MG1 and MG2 by switching transistors as gate type switching elements. The MG1 and MG2 are configured as known inverters that can be driven to rotate.

  The battery 22 is configured as a rechargeable secondary battery such as a lithium ion battery or a nickel metal hydride battery.

  Boost converter 30 includes two gate type switching elements (for example, transistors) Tr1 and Tr2 arranged in series so as to be parallel to smoothing capacitor 42 on the positive and negative buses of inverters 11 and 12, and each switching element Tr1, A known diode composed of two diodes D1 and D2 attached to hold a voltage in parallel with Tr2 and a coil 32 attached between the two switching elements Tr1 and Tr2 and the positive side of the battery 22 Boost converter.

  The electronic control unit 50 is configured as a microprocessor centered on the CPU 52. In addition to the CPU 52, a ROM 54 that stores processing programs, a RAM 56 that temporarily stores data, input / output ports and communication ports (not shown), and the like. Is provided. The electronic control unit 50 is input with a boost side voltage VH from a voltage sensor 44 attached between terminals of the smoothing capacitor 42 via an input port. Further, the electronic control unit 50 outputs a switching signal to the switching elements Tr1 and Tr2 of the boost capacitor 30 from the output port. The electronic control unit 50 also functions as a drive control unit for the two motors MG1 and MG2 for traveling. For this reason, the electronic control unit 50 is applied to the motor MG1 and MG2 from the rotational position of the rotor from the rotational position sensors 13 and 14 attached to the motors MG1 and MG2 and from a current sensor (not shown) attached to the inverters 11 and 12. The phase current to be applied is input through the input port, and the switching signal to the inverters 11 and 12 is output from the electronic control unit 50 through the output port.

  The power system 20 thus configured basically has an electronic control unit so that the capacitor voltage VH becomes the voltage command VH * in order to smoothly exchange power between the battery 22 and the two motors MG1, MG2. 50, the switching elements Tr1 and Tr2 of the boost converter 30 are on / off controlled.

  Next, the operation of the power system 20 of the thus configured embodiment, in particular, the boost side voltage VH of the boost converter 30 is slightly lower than the upper limit value or the upper limit value of the voltage that can be applied without damaging the inverters 11 and 12. The operation when an overvoltage state exceeding the allowable voltage Vhi as a value (for example, 750 [V] when the normal drive voltage Vo that can normally drive the inverters 11 and 12 is 650 [V]) will be described. FIG. 2 is a flowchart showing an example of an overvoltage control routine executed by the electronic control unit 50. This routine is executed when the boost side voltage VH of the boost converter 30 becomes equal to or higher than the allowable voltage Vhi.

  When the overvoltage control routine is executed, the CPU 52 of the electronic control unit 50 first executes a process of shutting down the operation of the boost converter 30 and the inverters 11 and 12 by cutting off the gates of the boost converter 30 and the inverters 11 and 12. (Step S100). Subsequently, the boost side voltage VH is input from the voltage sensor 44 (step S110), and the boost side voltage VH is waited for the normal drive voltage Vo (for example, 650 [V]) of the inverters 11 and 12 to become lower (step S110). S120, S110). When the boost converter 30 and the inverters 11 and 12 are shut off, the charge accumulated in the smoothing capacitor 42 is discharged by the resistance element 43. Therefore, here, the boost side voltage VH is decreased by the discharge of the resistance element 43, and the normal It will wait until it reaches the drive voltage Vo. Since the booster side voltage VH can be lowered by discharging the resistance element 43 while the inverters 11 and 12 are gate-cut off, a voltage exceeding the allowable voltage Vhi is applied to the inverters 11 and 12 to the inverters 11 and 12. The occurrence of damage can be suppressed.

  When the boost side voltage VH decreases and reaches the normal drive voltage Vo (for example, 650 [V]) of the inverters 11 and 12 (step S120), the boost converter 30 and the inverters 11 and 12 are returned to the gates. Boost converter 30 and inverters 11 and 12 are made operable (step S130), and this routine is terminated. FIG. 3 is an explanatory diagram showing an example of a time change of the boost side voltage VH. When boost side voltage VH exceeds allowable voltage Vhi at time t0 (time t0), this routine is executed, boost converter 30 and inverters 11 and 12 are shut off, and boost side voltage VH is discharged by resistance element 43. It decreases with a time constant determined by the capacitance value of the smoothing capacitor 42 and the resistance value of the resistance element 43. Thus, when the boost side voltage VH decreases and becomes equal to or lower than the normal drive voltage Vo (time t1), the boost converter 30 and the inverters 11 and 12 are returned to the gates, and the boost converter 30 and the inverters 11 and 12 become operable. . As described above, when the boost side voltage VH becomes equal to or lower than the normal drive voltage Vo of the inverters 11 and 12, the boost converter 30 and the inverters 11 and 12 are returned to the gates, so that the boost converter 30 and the inverters 11 and 12 are overvoltage. It is possible to suppress damage due to application of.

  According to the power system 20 of the embodiment described above, since the power system 20 includes the resistance element 43 connected in parallel to the smoothing capacitor 42, the boost converter 30 and the inverter 11 when the system is in an overvoltage state. , 12 can be reduced by discharging the resistance element 43 while the gates are cut off, compared with the case where the motors MG1, MG2 are driven by the inverters 11, 12 to reduce the boost side voltage VH. Further, damage due to an excessive voltage of the inverters 11 and 12 can be suppressed.

  In the power system 20 of the embodiment, the boost converter 30 and the inverters 11 and 12 are returned to the gate when the boost side voltage VH reaches the normal drive voltage Vo of the inverters 11 and 12, but the inverters 11 and 12 are gated. The voltage to be restored is not limited to the normal drive voltage Vo, and may be any voltage that can drive the inverters 11 and 12 without being damaged when the inverters 11 and 12 are returned to the gate. For example, the normal drive voltage A voltage slightly higher than Vo and lower than the allowable voltage Vhi may be used.

  In the power system 20 of the embodiment, the boost converter 30 and the inverters 11 and 12 are gated until the boost side voltage VH becomes equal to or lower than the normal drive voltage Vo, but the capacitance value of the smoothing capacitor 42 and the resistance of the resistance element 43 are Based on the value or the like, the time until the boost side voltage VH decreases and reaches the normal drive voltage Vo after the gate of the boost converter 30 and the inverters 11 and 12 is determined in advance as the gate cutoff time ts. The gates may be shut off until the elapsed time after the gates 11 and 12 are turned off reaches the gate cutoff time ts. In this way, even when the voltage sensor 44 fails, the inverters 11 and 12 can be gated until the boost side voltage VH drops to the normal drive voltage Vo, and an excessive voltage is applied to the inverters 11 and 12. Can be suppressed.

  The power system 20 of the embodiment has been described as being connected to the two motors MG1 and MG2 via the inverters 11 and 12, but may be connected to one motor and connected to three or more motors. It does not matter if it is done. Further, the connection destination is not limited to a motor or a generator, and any device that consumes power or any device that generates or regenerates power may be used.

  In the power system 20 of the embodiment, power is exchanged with the motors MG1 and MG2 for traveling on the vehicle. However, the power system 20 may be mounted on other devices without being mounted on the vehicle, or the power system alone. It does not matter if it is used.

  Moreover, it is not limited to what is applied to such a power system, It is good also as a form of the control method of such a power output system.

Here, the correspondence between the main elements of the embodiment and the main elements of the invention described in the column of means for solving the problems will be described. In the embodiment, the motors MG1 and MG2 correspond to “drive devices”, the inverters 11 and 12 correspond to “drive circuits”, the battery 22 corresponds to “DC power supply”, and the boost converter 30 corresponds to “boost converter”. The smoothing capacitor 42 corresponds to the “smoothing capacitor”, the resistance element 43 corresponds to the “discharge element”, the voltage sensor 44 corresponds to the “boost side voltage detection means”, and the boost side voltage VH corresponds to the allowable voltage Vhi. The CPU 52 of the electronic control unit 50 that executes the processing of steps S100 to S120 that gates the boost converter 30 and the inverters 11 and 12 until the boost side voltage VH becomes equal to or lower than the normal drive voltage Vo when the voltage exceeds the “control means”. It corresponds to. Also, the CPU 52 of the electronic control unit 50 that executes the process of gate-blocking the boost converter 30 and the inverters 11 and 12 until the elapsed time after the gate-off of the boost converter 30 and the inverters 11 and 12 reaches the gate cutoff time ts. It corresponds to “control means”. Here, the “drive device” is not limited to the motors MG1 and MG2 configured as the synchronous generator motor, and may be any type of motor such as an induction motor. Further, the “drive device” is not limited to the electric motor, and any device that is driven by electric power may be used.
The “drive circuit” is not limited to the inverters 11 and 12 and may be any circuit as long as it can drive a drive device. The “DC power supply” is not limited to the battery 50 as a secondary battery, and any capacitor, such as a capacitor, can be used. The “boost converter” is not limited to boosting using the counter electromotive force of the coil 32, but boosts the voltage of the DC power supply to the drive circuit by boosting the voltage by charging a capacitor. Anything can be used as long as it can be supplied. Any “smoothing capacitor” may be used as long as it is connected in parallel to the drive circuit as viewed from the boost converter and smoothes the boost side voltage of the boost converter. The “discharge element” is not limited to the resistance element 40 and may be any element as long as it can discharge the charge accumulated in the smoothing capacitor. The “boost-side voltage detection means” is not limited to the voltage sensor 44, but is a boost converter that calculates the boost-side voltage VH based on the current flowing through the resistance element 43 and the resistance value of the resistance element 43. Any voltage can be used as long as it can detect the boost side voltage. The “control means” is not limited to the electronic control unit 50, and may be configured by combining a plurality of electronic control units. Further, the “control means” is limited to the one that gates the boost converter 30 and the inverters 11 and 12 until the boost side voltage VH becomes equal to or lower than the normal drive voltage Vo when the boost side voltage VH exceeds the allowable voltage Vhi. Instead, the booster side voltage VH is reduced to the normal drive voltage Vo after the boost converter 30 and the inverters 11 and 12 are shut off based on the capacitance value of the smoothing capacitor 42, the resistance value of the resistance element 43, and the like. The time to reach the gate cut-off time ts is determined in advance by the boost-side voltage detection means, such as the gate cut-off time until the gate cut-off time ts has elapsed since the boost converter 30 and the inverters 11 and 12 are gate cut off. When the boosted voltage exceeds the allowable voltage allowed for the drive circuit, the boost voltage drops and the drive circuit operates normally. As long as it controls the drive circuit and the boost converter such that the drive circuit and the boost converter up to the possible normal operating voltage to stop the operation may be any ones. The correspondence between the main elements of the embodiment and the main elements of the invention described in the column of means for solving the problem is the same as that of the embodiment described in the column of means for solving the problem. It is an example for specifically explaining the best mode for doing so, and does not limit the elements of the invention described in the column of means for solving the problem. That is, the interpretation of the invention described in the column of means for solving the problems should be made based on the description of the column, and the examples are those of the invention described in the column of means for solving the problems. It is only a specific example.

  The best mode for carrying out the present invention has been described with reference to the embodiments. However, the present invention is not limited to these embodiments, and various modifications can be made without departing from the gist of the present invention. Of course, it can be implemented in the form.

  The present invention is applicable to a power system and a manufacturing industry of a vehicle on which the power system is mounted.

It is a block diagram which shows the outline of a structure of the vehicle-mounted power system 20 as one Example of this invention. 3 is a flowchart showing an example of an overvoltage control routine executed by an electronic control unit 50. It is explanatory drawing which shows an example of the time change of the boost side voltage VH.

Explanation of symbols

  11, 12 Inverter, 13, 14 Rotational position sensor, 20 Power system, 22 Battery, 30 Boost converter, 32 Coil, 42 Smoothing capacitor, 43 Resistance element, 44 Voltage sensor, 50 Electronic control unit, 52 CPU, 54 ROM, 56 RAM, Tr1, Tr2 switching elements.

Claims (5)

Driving equipment,
A drive circuit for driving the drive device;
A chargeable / dischargeable DC power supply,
A boost converter capable of boosting the voltage of the DC power supply and supplying the boosted voltage to the drive circuit;
A smoothing capacitor connected in parallel to the drive circuit as seen from the boost converter and smoothing the boost side voltage of the boost converter;
A discharge element capable of discharging the charge accumulated in the smoothing capacitor;
Step-up voltage detecting means for detecting the step-up voltage of the step-up converter;
When the boost side voltage detected by the boost side voltage detection means exceeds the allowable voltage allowed for the drive circuit, the boost side voltage decreases until the drive circuit reaches a normal operation voltage at which the drive circuit can normally operate. Control means for controlling the drive circuit and the boost converter so that the drive circuit and the boost converter stop operating;
Power system with   The control means controls the drive circuit and the boost converter so that the drive circuit and the boost converter stop operating until the boost side voltage detected by the boost side voltage detection means reaches the normal operating voltage. The power system according to claim 1, which is a means.   The control means controls the drive circuit and the boost converter when a predetermined time has elapsed after stopping the operation of the drive circuit and the boost converter when the boost side voltage reaches the normal operating voltage. The power system according to claim 1, which is means for   A vehicle equipped with the electric power system according to any one of claims 1 to 3 and having an electric motor capable of outputting driving power as the driving device. Drive device, drive circuit for driving the drive device, chargeable / dischargeable DC power supply, boost converter capable of boosting the voltage of the DC power supply and supplying it to the drive circuit, and the drive circuit as seen from the boost converter A smoothing capacitor connected in parallel to smooth the boost side voltage of the boost converter, and a discharge element capable of discharging the charge accumulated in the smoothing capacitor,
When the boost side voltage of the boost converter exceeds the allowable voltage allowed for the drive circuit, the drive circuit and the boost converter until the boost side voltage drops and reaches the normal operation voltage at which the drive circuit can normally operate. Controlling the drive circuit and the step-up converter so as to stop the operation of the power system.

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