Power system
The power system uses a Y capacitor configuration with capacitors of differing heat resistance and capacitance to prevent simultaneous failures, enhancing reliability by staggered failure timing.
Patent Information
- Authority / Receiving Office
- JP · JP
- Patent Type
- Applications
- Current Assignee / Owner
- TOYOTA JIDOSHA KK
- Filing Date
- 2024-10-29
- Publication Date
- 2026-05-15
AI Technical Summary
Existing power systems face the challenge of simultaneous open failures in parallel-connected capacitors due to ground fault currents, which are not adequately addressed by conventional Y capacitors.
The power system employs a Y capacitor configuration with multiple first and second capacitors connected in parallel, where at least two capacitors in each group have different heat resistance and/or capacitance to stagger the timing of open-circuit failures, thereby suppressing simultaneous failures.
This configuration effectively delays and prevents simultaneous failures of capacitors by distributing the ground fault current unevenly among capacitors with varying heat resistance and capacitance, ensuring reliable operation.
Smart Images
Figure 2026078977000001_ABST
Abstract
Description
Technical Field
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[0001] The present disclosure relates to a power system.
Background Art
[0002] Conventionally, as a power system, there is known one including a battery, an inverter connected to the battery via a positive electrode side line and a negative electrode side line, and a Y capacitor connected to the positive electrode side, the negative electrode side line, and the ground (Patent Document 1). The Y capacitor has a first Y capacitor connected between the positive electrode side line and the ground, and a second Y capacitor connected between the negative electrode side line and the ground. The Y capacitor serves to remove noise components by allowing the noise components leaked from the inverter to flow to the ground.
Prior Art Documents
Patent Documents
[0003]
Patent Document 1
Summary of the Invention
Problems to be Solved by the Invention
[0004] By the way, in the Y capacitor described in Patent Document 1, it is conceivable to replace the first Y capacitor with a plurality of capacitors connected in parallel to each other, and replace the second Y capacitor with a plurality of capacitors connected in parallel to each other. In this case, there has been a desire to suppress the simultaneous open failure of the plurality of capacitors connected in parallel to each other due to the ground fault current.
[0005] The present disclosure has been made to solve such problems, and the main object is to suppress the occurrence of simultaneous failures of a plurality of capacitors connected in parallel to each other.
Means for Solving the Problems
[0006] This disclosure employs the following means to achieve the primary objectives described above.
[0007] The power system described in this disclosure is A power system comprising an energy storage device and power equipment connected to the energy storage device via a power line, A Y capacitor comprises a positive-side capacitor including a plurality of first capacitors connected in parallel to each other to the positive-side line of the power line and to ground, and a negative-side capacitor including a plurality of second capacitors connected in parallel to each other to the negative-side line of the power line and to ground, At least two of the plurality of first capacitors have different heat resistance and / or capacitance. At least two of the plurality of second capacitors have different heat resistance and / or capacitance. It is.
[0008] In the power system of this disclosure, at least two of the multiple first capacitors connected in parallel to each other, which are included in the positive electrode capacitor of the Y capacitor, have different heat resistance and / or capacitances. This makes it possible to stagger the timing of open-circuit failures for at least two of the multiple first capacitors when a ground fault current flows through the Y capacitor. Similarly, at least two of the multiple second capacitors connected in parallel to each other, which are included in the negative electrode capacitor, have different heat resistance and / or capacitances, so that they also stagger the timing of open-circuit failures for at least two of the multiple second capacitors. Therefore, it is possible to suppress the occurrence of simultaneous failures of multiple capacitors connected in parallel to each other. [Brief explanation of the drawing]
[0009] [Figure 1] This is a schematic diagram of the power system. [Figure 2] This is a schematic diagram of the positive electrode capacitor in a modified power system. [Modes for carrying out the invention]
[0010] Embodiments for implementing this disclosure will be described with reference to the drawings. Figure 1 is a schematic diagram of a power system 20 according to an embodiment of this disclosure. As shown in the figure, the power system 20 of the embodiment includes a motor 22, a three-phase power line 24, an inverter 26 as a power device, a battery 28 as an energy storage device, a DC power line 30, and a Y capacitor 40. The power system 20 is installed in vehicles such as electric vehicles, hybrid vehicles, and fuel cell vehicles.
[0011] The motor 22 is configured as a synchronous generator motor having, for example, a rotor in which permanent magnets are embedded in a rotor core and a stator in which three-phase coils are wound around a stator core, with the three-phase coils connected to the inverter 26 via a three-phase power line 24. The motor 22 is rotationally driven by three-phase AC power from the inverter 26 via the three-phase power line 24 and outputs rotational driving force to, for example, the drive shaft of a vehicle.
[0012] The inverter 26 has multiple switching elements (not shown). The inverter 26 is connected to the battery 28 via a DC power line 30. The inverter 26 converts the DC power from the battery 28 into three-phase AC power by switching the multiple switching elements and outputs it to the motor 22.
[0013] The battery 28 is configured as, for example, a lithium-ion secondary battery or a nickel-metal hydride secondary battery, and as described above, is connected to the inverter 26 via the DC power line 30. A smoothing capacitor 33 and a Y capacitor 40 are connected to the DC power line 30. The smoothing capacitor 33 is connected to the positive side line 31 and the negative side line 32 of the DC power line 30, and smooths the voltage of the DC power line 30.
[0014] The Y capacitor 40 is connected to the positive terminal line 31, the negative terminal line 32, and ground 34. Ground 34 is connected, for example, to the vehicle's housing. The Y capacitor 40 has a positive terminal capacitor 40a connected to the positive terminal line 31 and ground 34, and a negative terminal capacitor 40b connected to the negative terminal line 32 and ground 34. The positive terminal capacitor 40a has a plurality of first capacitors (here capacitors 41-43) connected in parallel to each other to the positive terminal line 31 and ground 34. The negative terminal capacitor 40b has a plurality of second capacitors (here capacitors 44-46) connected in parallel to each other to the negative terminal line 32 and ground 34. The Y capacitor 40 reduces common-mode noise by removing high-frequency components leaking from the inverter 26 into the DC power line 30, thereby improving the EMC (Electro Magnetic Compatibility) performance of the power system 20 and the vehicle on which the power system 20 is installed.
[0015] Furthermore, capacitors 41 to 43 have the same heat resistance (e.g., heat resistance temperature) but different capacitances. Similarly, capacitors 44 to 46 have the same heat resistance but different capacitances. On the other hand, it is preferable that the positive electrode capacitor 40a and the negative electrode capacitor 40b have the same capacitance (combined capacitance). It is also preferable that the number of capacitors in the positive electrode capacitor 40a, their respective capacitances, and connection relationships are the same (symmetrical) as the number of capacitors in the negative electrode capacitor 40b. In this embodiment, as shown in Figure 1, the number of capacitors in the positive electrode capacitor 40a and the negative electrode capacitor 40b are the same and their connection relationships are also the same (symmetrical). In addition, in this embodiment, capacitors 41 and 44 have the same capacitance, capacitors 42 and 45 have the same capacitance, and capacitors 43 and 46 have the same capacitance.
[0016] Next, we will explain the operation of the power system 20 configured in this way, particularly its operation in the event of a failure. For example, if a ground fault occurs in the three-phase power line 24 between the inverter 26 and the motor 22, the current from the inverter 26 to the three-phase power line 24 may flow as a ground fault current through the ground fault point and the earth 34 to the positive-side capacitor 40a and the negative-side capacitor 40b. In this case, as a comparative example, let's first consider the case where the heat resistance and capacitance of capacitors 41 to 43 of the positive-side capacitor 40a are the same. In this case, the ground fault current flowing from the earth 34 to the positive-side capacitor 40a is equally divided among capacitors 41 to 43. Therefore, the heat generated by capacitors 41 to 43 due to the divided ground fault current will be about the same, and there is a risk that capacitors 41 to 43 will open up and fail almost simultaneously due to the temperature rise. In contrast, in this embodiment, by making the capacitances of capacitors 41 to 43 different, the ground fault current flowing from earth 34 to the positive electrode capacitor 40a can be divided according to the capacitances of capacitors 41 to 43, and the ground fault current flowing through each of capacitors 41 to 43 can be made to be different values. Specifically, since capacitors 41 to 43 are connected in parallel, a larger ground fault current flows through the capacitor with the larger capacitance. As a result, the amount of heat generated by capacitors 41 to 43 is also different, so even if the heat resistance performance of capacitors 41 to 43 is the same, the timing of failure of capacitors 41 to 43 due to temperature rise can be staggered. More specifically, the capacitor with the larger capacitance among capacitors 41 to 43 will fail first. Therefore, simultaneous failure of capacitors 41 to 43 can be suppressed. In addition, for capacitors with smaller capacitance among capacitors 41 to 43, heat generation can be suppressed, delaying the timing of failure due to temperature rise. Similarly, for capacitors 44 to 46, the timing of open-circuit failure can be staggered by having different capacitances, and simultaneous failure can be suppressed.
[0017] In the power system 20 of the embodiment described above, the capacitances of capacitors 41 to 43 connected in parallel to each other and included in the positive electrode side capacitor 40a of the Y capacitor 40 are different. This makes it possible to make the timing of open-circuit failures for capacitors 41 to 43 different when a ground fault current flows through the Y capacitor 40. Similarly, since the capacitances of capacitors 44 to 46 connected in parallel to each other and included in the negative electrode side capacitor 40b are different, the timing of open-circuit failures for capacitors 44 to 46 can be made different. Therefore, it is possible to suppress the occurrence of simultaneous failures of multiple capacitors connected in parallel to each other among capacitors 41 to 46.
[0018] The positive electrode capacitor 40a in the embodiment had capacitors connected in parallel one by one, but is not limited to this. For example, the positive electrode capacitor 140a of the Y capacitor 140 in the modified power system 120 of Figure 2 includes a plurality of capacitors 141, 42, and 43 connected in parallel with each other. Capacitor 141 has a plurality (in this case, two) of capacitors 141a and 141b connected in series. In this case, the combined capacitance of capacitors 141a and 141b corresponds to the capacitance of capacitor 141, and the capacitances of capacitors 141, 42, and 43 are different from each other. One or more of capacitors 42 to 46 may also have a plurality of capacitors connected in series, similar to capacitor 141.
[0019] In the embodiment, the capacitors 41 to 43 had different capacitances, but this is not limiting. For at least two of the plurality of capacitors connected in parallel with each other that the positive electrode side capacitor 40a has, it is sufficient if their capacitances are different from each other. For example, if the capacitances of capacitor 41 and capacitor 42 are different from each other, the capacitance of capacitor 43 may be the same as the capacitance of capacitor 41 or capacitor 42. The same applies to the negative electrode side capacitor 40b and the positive electrode side capacitor 140a in FIG. 2. The same also applies when making the heat resistance performance different. In addition to or instead of the capacitance, the heat resistance performance may be different from each other. Even if the capacitances of the capacitors 41 to 43 are the same, by making the heat resistance performance different from each other, it is possible to adjust so that the capacitor with the lower heat resistance performance among the capacitors 41 to 43 fails first. Also in this case, by shifting the timing of failure of the capacitors 41 to 43, it is possible to suppress simultaneous failure. Even when both the capacitance and the heat resistance performance of the capacitors 41 to 43 are made different, similarly, by shifting the timing of failure of the capacitors 41 to 43, it is possible to suppress simultaneous failure. When both the capacitance and the heat resistance performance of the capacitors 41 to 43 are made different, the heat resistance performance may be made lower for capacitors with larger capacitances. Similarly, for the capacitors 44 to 46, in addition to or instead of the capacitance, the heat resistance performance may be different from each other. The same applies to the capacitors 141, 142, 143 in FIG. 2. When there are a plurality of capacitors (capacitors 141a, 141b in FIG. 2) connected in series like the capacitor 141 in FIG. 2, the lowest heat resistance performance among them is used as the reference. For example, if the heat resistance performances of the capacitors 141a and 141b are different, the lower heat resistance performance is taken as the heat resistance performance of the capacitor 141, and if the heat resistance performances of the capacitors 141a and 141b are the same, that heat resistance performance is taken as the heat resistance performance of the capacitor 141.
[0020] In the embodiment, the capacitors 41 to 43 had different capacitances, but this is not limited thereto. For at least two of the plurality of capacitors connected in parallel with each other that the positive electrode side capacitor 40a has, it is sufficient if their capacitances are different from each other. For example, if the capacitances of capacitor 41 and capacitor 42 are different from each other, the capacitance of capacitor 43 may be the same as the capacitance of capacitor 41 or capacitor 42. The same applies to the negative electrode side capacitor 40b and the positive electrode side capacitor 140a in FIG. 2. The same also applies when making the heat resistance performance different.
[0021] In the embodiment, the number of capacitors in parallel of the positive electrode side capacitor 40a was 3, but it is not limited thereto, and the number of capacitors in parallel may be 2 or 4 or more. The same applies to the negative electrode side capacitor 40b and the positive electrode side capacitor 140a in FIG. 2.
[0022] The power system 20 of the embodiment includes the battery 28, but it is not limited thereto, and any power storage device may be provided. Specific examples of power storage devices other than the battery 28 include, for example, capacitors.
[0023] In the embodiment, the inverter 26 is regarded as the power device, but it is not limited thereto. For example, as the power device, at least one of a charger or a DC / DC converter (DDC) connected to the DC power line 30 may be applicable.
[0024] 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 battery 28 corresponds to the "power storage device", the DC power line 30 corresponds to the "power line", the inverter 26 corresponds to the "power device", the Y capacitor 4o corresponds to the "Y capacitor", the positive electrode side capacitor 40a corresponds to the "positive electrode side capacitor", the capacitors 41 to 43 correspond to the "first capacitor", the negative electrode side capacitor 40b corresponds to the "negative electrode side capacitor", and the capacitors 44 to 46 correspond to the "second capacitor".
[0025] Note that 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 is an example for specifically explaining the form for implementing the invention described in the column of means for solving the problems in the embodiment, and does not limit the elements of the invention described in the column of means for solving the problems. That is, the interpretation of the invention described in the column of means for solving the problems should be made based on the description in that column, and the embodiment is merely a specific example of the invention described in the column of means for solving the problems.
[0026] The above describes the forms for implementing this disclosure using embodiments, but this disclosure is not limited in any way to these embodiments, and can of course be implemented in various forms without departing from the gist of this disclosure. [Industrial applicability]
[0027] This disclosure can be used in industries such as the manufacturing of power systems and vehicles equipped with them. [Explanation of Symbols]
[0028] 20 Power system, 22 Motor, 24 Three-phase power line, 26 Inverter, 28 Battery, 30 DC power line, 31 Positive side line, 32 Negative side line, 33 Smoothing capacitor, 34 Ground, 40 Y capacitor, 40a Positive side capacitor, 40b Negative side capacitor, 41-46 Capacitors, 120 Power system, 140 Y capacitor, 140a Positive side capacitor, 141 Capacitor, 141a, 141b Capacitors.
Claims
[Claim 1] A power system comprising an energy storage device and power equipment connected to the energy storage device via a power line, A Y capacitor comprises a positive-side capacitor including a plurality of first capacitors connected in parallel to each other to the positive-side line of the power line and to ground, and a negative-side capacitor including a plurality of second capacitors connected in parallel to each other to the negative-side line of the power line and to ground, At least two of the plurality of first capacitors have different heat resistance and / or capacitance. At least two of the plurality of second capacitors have different heat resistance and / or capacitance. Power system.