Motor drive circuit and electric vehicle

Abstract

The device comprises an inverter circuit that controls the drive of the motor, a first power supply that supplies power to the inverter circuit, a second power supply that is charged from the first power supply when the first power supply is supplying power to the motor via the inverter circuit and that supplies power to the inverter circuit to start the inverter circuit when the first power supply has stopped supplying power to the motor, a third power supply that selectively supplies power to the inverter circuit to start the inverter circuit between the second power supply and the third power supply, and a switching unit that selectively switches the supply of power to the inverter circuit from either the third power supply or the second power supply. A motor drive circuit and an electric vehicle are provided that can improve convenience when restarting an inverter circuit.

Description

[Technical Field]

[0001] The present invention relates to a motor drive circuit and an electric vehicle, and more particularly to a motor drive circuit mounted on an electric vehicle and an electric vehicle equipped with the motor drive circuit. [Background technology]

[0002] BACKGROUND ART In recent years, as part of efforts to reduce carbon dioxide emissions, there has been a gradual shift from vehicles driven by internal combustion engines, i.e., engines, to electrically powered vehicles, primarily electric vehicles driven by a power source and a motor.

[0003] Patent Document 1 discloses that in a power supply device mounted on an electric vehicle that runs on batteries, the operation of the DC / DC converter is stopped when the remaining capacity of both the high-voltage battery and the low-voltage battery is greater than the minimum allowable capacity, thereby reducing the occurrence of conversion loss in the DC / DC converter. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2013-90486 A Summary of the Invention [Problem to be solved by the invention]

[0005] In the motor drive circuit mounted on this type of electric vehicle, when the inverter circuit stops driving the motor, it is necessary to control the circuit so that high voltage is not present inside the vehicle, in order to avoid electric shock accidents caused by the high voltage from the high-voltage power supply.

[0006] When the inverter circuit has stopped driving the motor and the inverter circuit is to be restarted to drive the motor again, a method may be used in which the inverter circuit is restarted by supplying power to the inverter circuit from a lead-acid battery.

[0007] However, there are cases where the inverter circuit cannot be restarted due to factors such as deterioration of the lead-acid battery. In such cases, it is necessary to connect the lead-acid battery installed in the electric vehicle whose motor has been stopped in parallel with the lead-acid battery of another electric vehicle in order to restart the electric vehicle, which raises concerns that the restarting process may require additional work.

[0008] The present invention has been made in consideration of the above circumstances, and an object of the present invention is to provide a motor drive circuit and an electric vehicle that can improve convenience when restarting an inverter circuit. [Means for solving the problem]

[0009] In order to achieve the above object, the motor drive circuit of the present invention comprises an inverter circuit that controls the drive of the motor, a first power supply that supplies power to the inverter circuit, a second power supply that is charged from the first power supply when the first power supply is supplying power to the motor via the inverter circuit and that supplies power to the inverter circuit to start the inverter circuit when the first power supply has stopped supplying power to the motor, a third power supply that selectively supplies power to the inverter circuit to start the inverter circuit between the second power supply and the third power supply, and a switching unit that selectively switches the supply of power to the inverter circuit from either the third power supply or the second power supply.

[0010] According to this, even if the inverter circuit cannot be restarted due to deterioration of the second power source or the like, by switching to the third power source via the switching unit, voltage can be applied to the inverter circuit from the third power source, thereby reducing the workload and improving convenience when restarting the inverter circuit.

[0011] The second power supply of this motor drive circuit may be configured by a lead storage battery, and the third power supply may be configured by a solar cell.

[0012] In order to achieve the above object, an electric vehicle according to the present invention is equipped with a motor drive circuit including: an inverter circuit that controls the drive of a motor; a first power source that supplies power to the inverter circuit; a second power source that is charged from the first power source when the first power source is supplying power to the motor via the inverter circuit, and that supplies power to the inverter circuit to start the inverter circuit when the first power source has stopped supplying power to the motor; a third power source that selectively supplies power to the inverter circuit to start the inverter circuit between the second power source and the third power source; and a switching unit that selectively switches the supply of power to the inverter circuit from either the third power source or the second power source. [Effects of the Invention]

[0013] According to the present invention, it is possible to improve the convenience when restarting the inverter circuit. [Brief explanation of the drawings]

[0014] [Figure 1] 1 is a block diagram illustrating an outline of the configuration of a motor drive circuit according to an embodiment of the present invention. [Figure 2] FIG. 2 is a block diagram for explaining an outline of the operation of the motor drive circuit according to the present embodiment. [Figure 3] FIG. 2 is a block diagram for explaining an outline of the operation of the motor drive circuit according to the present embodiment. [Figure 4] 1 is a block diagram illustrating an outline of the configuration of a conventional motor drive circuit to be compared with a motor drive circuit according to an embodiment of the present invention; [Figure 5] FIG. 10 is a block diagram illustrating an outline of the operation of a motor drive circuit of a comparative example. DETAILED DESCRIPTION OF THE INVENTION

[0015] Next, a motor drive circuit according to an embodiment of the present invention will be described with reference to FIGS.

[0016] 1 is a block diagram illustrating the general configuration of a motor drive circuit according to this embodiment. As shown in the figure, motor drive circuit 10 includes motor 11, inverter circuit 12, first power supply 13, second power supply 14, charger 15, third power supply 16, constant voltage source 17, and switching unit 18 as its main components.

[0017] In this embodiment, the motor 11 drives the electric vehicle, and the inverter circuit 12 controls the driving of the motor 11 by converting DC power into AC power, and has a built-in CPU (not shown) that controls the motor 11, such as adjusting the rotation speed and torque of the motor 11.

[0018] In this embodiment, the first power source 13 includes a battery cell group 13A formed by connecting a plurality of lithium ion secondary battery cells 13a in series, and a current interrupter 13B connected in series with the battery cell group 13A, and is configured as a battery power source with a rated output voltage V.

[0019] In this embodiment, the current interruption unit 13B is illustrated in each drawing as being implemented as a contact switch, but may also be implemented as a semiconductor switch such as an FET.

[0020] In this embodiment, this first power source 13 may be configured as a battery power source with an output rated voltage of 2V by connecting multiple, for example two, first power sources 13 in series, and when the current interrupter 13B is turned on based on the insulation indication signal S transmitted from the inverter circuit 12, power based on a high voltage of 2V is output to the motor 11 via the inverter circuit 12.

[0021] Here, when two first power sources 13 are connected in series, the representative value of the output rated voltage of 2V as a battery power source is 360V.

[0022] In this embodiment, the second power source 14 is implemented as a lead-acid battery with a rated voltage of 12 V that is mounted on an engine-driven vehicle. A lead-acid battery is a secondary battery configured by connecting multiple battery cells in series, with the positive and negative electrodes facing each other in an electrolyte.

[0023] In this embodiment, the charger 15 is a device that charges the second power source 14 with power from the first power source 13, and the third power source 16 is implemented by a solar cell in this embodiment. Here, the solar cell is a device that converts light energy into electric power using the photovoltaic effect.

[0024] In this embodiment, constant voltage source 17 applies a constant voltage CV from first power source 13 to the CPU of inverter circuit 12 via charger 15. Here, a typical value of the constant voltage CV required when the CPU performs AC voltage output control for controlling the drive of motor 11 is 3V to 5V.

[0025] In this embodiment, the switching unit 18 is a device that selectively switches the supply of power to the inverter circuit 12 from either the second power source 14 or the third power source 16. In this embodiment, the drawings show an example in which the switching unit 18 is implemented as a contact switch, but it may also be implemented as, for example, a plurality of semiconductor switches.

[0026] This switching unit 18 may be a type that can be switched manually, or may be a type that can autonomously switch to the third power source 16 side when it detects that the second power source 14 is in a deteriorated state (when it detects that the voltage of the second power source 14 is below a preset value).

[0027] In this embodiment, it is assumed that the switching unit 18 is initially set to a state in which it is switched to the second power source 14 side.

[0028] In this embodiment, it is assumed that the motor drive circuit 10 having such a configuration is mounted on an electric vehicle, particularly an electric automobile.

[0029] Next, an outline of the operation of the motor drive circuit 10 of this embodiment when it is mounted on an electric vehicle will be described.

[0030] When the electric vehicle is running, the second power source 14 is charged from the first power source 13 via the charger 15, and a constant voltage CV is applied to the CPU of the inverter circuit 12 from the first power source 13 via the charger 15 and the constant voltage source 17.

[0031] 2 and 3 are block diagrams illustrating an outline of the operation of the motor drive circuit 10 of this embodiment. As shown in Fig. 2, when the current interruption unit 13B of the first power source 13 is brought into an interrupted state based on the insulation instruction signal S transmitted from the inverter circuit 12, the inverter circuit 12 stops driving the motor 11, and the electric vehicle stops.

[0032] When the current interruption unit 13B of the first power source 13 is brought into an interrupted state, the voltage of the first power source 13 drops, so that it is possible to avoid the burden of electric shock accidents and breakdowns caused by high voltage.

[0033] When the inverter circuit 12 is restarted to drive the motor 11 again after the electric vehicle has stopped, in this embodiment, as shown in FIG. 2, the switching unit 18 is set to a state in which it is switched to the contact a (second power source 14) side, so that a constant voltage CV is applied from the second power source 14 to the CPU of the inverter circuit 12, and the inverter circuit 12 is restarted.

[0034] When the inverter circuit 12 is restarted, the current interrupter 13B of the first power source 13 is energized based on the insulation instruction signal S transmitted from the inverter circuit 12, causing the inverter circuit 12 to drive the motor 11. This enables the electric vehicle to run.

[0035] On the other hand, if the second power supply 14 is deteriorated or broken and the constant voltage CV is not applied from the second power supply 14 to the CPU of the inverter circuit 12, the inverter circuit 12 will not restart, and the electric vehicle will become unable to run.

[0036] In this case, as shown in FIG. 3, when the switching unit 18 is switched to the b contact (third power source 16) side, a constant voltage CV is applied from the third power source 16 to the CPU of the inverter circuit 12, thereby restarting the inverter circuit 12.

[0037] When the inverter circuit 12 is restarted, the current interrupter 13B of the first power source 13 is energized based on the insulation instruction signal S transmitted from the inverter circuit 12, causing the inverter circuit 12 to drive the motor 11. This enables the electric vehicle to run.

[0038] The solar cell that implements the third power supply 16 only needs to supply the minimum amount of power necessary to restart the CPU of the inverter circuit 12, so it can be implemented as a small solar cell and installed in the electric vehicle, which contributes to reducing costs and saving space.

[0039] In this way, even if the inverter circuit 12 cannot be restarted due to deterioration of the second power source 14 or the like, by switching to the third power source 16 via the switching unit 18, voltage can be applied from the third power source 16 to the inverter circuit 12, thereby reducing the workload and improving convenience when restarting the inverter circuit 12.

[0040] (Comparative Example) Next, a comparative example of the motor drive circuit 10 of the present embodiment will be described with reference to FIGS.

[0041] 4 and 5, the same components as those in the motor drive circuit 10 are given the same reference numerals, and the description thereof will be omitted.

[0042] 4 is a diagram illustrating the outline of the configuration of a conventional motor drive circuit 100. As shown in the figure, motor drive circuit 100 mainly comprises motor 11, inverter circuit 12, first power supply 13, second power supply 14, charger 15, and constant voltage source 17, and is configured without third power supply 16 and switching unit 18 compared to motor drive circuit 10 of the present embodiment.

[0043] In an electric vehicle equipped with this motor drive circuit 100, as shown in Figure 5, when the inverter circuit 12 stops driving the motor 11 by switching the current interruption unit 13B of the first power source 13 to an interrupted state based on the insulation instruction signal S transmitted from the inverter circuit 12, the electric vehicle comes to a stop.

[0044] When the inverter circuit 12 is restarted and the motor 11 is driven again after the electric vehicle has stopped, a constant voltage CV is applied from the second power source 14 to the CPU of the inverter circuit 12, whereby the inverter circuit 12 is restarted and the motor 11 is driven.

[0045] On the other hand, if the second power supply 14 is deteriorated or broken and the constant voltage CV is not applied from the second power supply 14 to the CPU of the inverter circuit 12, the inverter circuit 12 will not restart, and the electric vehicle will become unable to run.

[0046] In this case, it is necessary to restart the second power source 14 mounted on the electric vehicle whose motor 11 has been stopped and the lead-acid battery of another electric vehicle or vehicle equipped with an engine by connecting them in parallel, for example, with a booster cable, which creates a workload for restarting the electric vehicle and, as a result, reduces the convenience of restarting the inverter circuit 12.

[0047] In contrast, as described above, the motor drive circuit 10 of this embodiment can apply voltage to the inverter circuit 12 from the switching unit 18 even when the inverter circuit 12 cannot be restarted due to deterioration of the second power source 14, etc., thereby reducing the workload and improving convenience when restarting the inverter circuit 12.

[0048] The present invention is not limited to the above-described embodiment, and various modifications are possible without departing from the spirit of the invention.

[0049] In the above embodiment, the motor drive circuit 10 is described as being mounted on an electric vehicle, but it may also be mounted on an electric vehicle other than an electric vehicle, for example, a hybrid vehicle. [Explanation of symbols]

[0050] 10 Motor drive circuit 12 Inverter circuit 13 1st power supply 14 2nd power supply 16 Third power supply 17 Constant voltage source 18 Switching section

Claims

1. an inverter circuit that controls the drive of the motor; a first power source that supplies power to the inverter circuit; a second power supply that is charged from the first power supply when the first power supply supplies power to the motor via the inverter circuit, and that supplies power to a CPU of the inverter circuit to start the inverter circuit when the first power supply stops supplying power to the motor; a third power supply that selectively supplies power to start the CPU of the inverter circuit via a constant voltage source, the third power supply being selective with the second power supply; a switching unit that selectively switches the supply of power from either the third power source or the second power source to the CPU of the inverter circuit; A motor drive circuit comprising:

2. The second power source is It is composed of lead-acid batteries, The third power source is Consists of solar cells, 2. The motor drive circuit according to claim 1.

3. an inverter circuit that controls the drive of the motor; a first power source that supplies power to the inverter circuit; a second power supply that is charged from the first power supply when the first power supply supplies power to the motor via the inverter circuit, and that supplies power to a CPU of the inverter circuit to start the inverter circuit when the first power supply stops supplying power to the motor; a third power supply that selectively supplies power to start the CPU of the inverter circuit via a constant voltage source, the third power supply being selective with the second power supply; a switching unit that selectively switches the supply of power from either the third power source or the second power source to the CPU of the inverter circuit; An electric vehicle equipped with a motor drive circuit including:

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