Semiconductor module and power conversion device

Abstract

To perform miniaturization during assembly of a power conversion device, and improve assembly efficiency and the cooling effect of a discharge resistor in a semiconductor module.SOLUTION: Switching elements Su and Sx, switching elements Sv and Sy, and switching elements Sw and Sz are connected in series between the P pole and N pole. There are three phases of legs, each with two switching elements connected in series. Six switching elements Su to Sz (three-phase legs) make up a 6-in-1 type semiconductor module 1. A discharge resistor R is connected between the P pole and N pole within the semiconductor module 1.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a technology for discharging electric charge stored in a smoothing capacitor in a power conversion device by incorporating a discharge resistor inside a semiconductor module. [Background technology]

[0002] A common method for discharging the charge stored in a smoothing capacitor in a power conversion device (e.g., an inverter) is to install a discharge resistor in parallel with the smoothing capacitor. Figure 1 is a circuit diagram showing a conventional, typical power conversion device. Traditionally, the most commonly used discharge resistor R was an external discharge resistor R (constant discharge resistor) such as a cement resistor connected to the smoothing capacitor C, but in recent years, for the sake of miniaturization, a configuration has also become known in which multiple chip resistors are mounted in series on a circuit board to form the discharge resistor R.

[0003] Patent Documents 1 and 2 disclose a technique for mounting a discharge resistor inside a semiconductor module as a method for realizing miniaturization, improved productivity, and efficient cooling. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2009-71935 [Patent Document 2] WO2013 / 065182 Summary of the Invention [Problem to be solved by the invention]

[0005] When miniaturizing power conversion equipment (achieving high power density), downsizing and heat generation of individual items become issues. The same applies to heat generated by discharge resistors R. Conventional external discharge resistors (constant discharge resistors) and board-mounted discharge resistors required heat dissipation to the power conversion equipment housing via a thermally conductive sheet, for example.

[0006] As a method for solving this problem, Patent Documents 1 and 2 disclose a method in which a discharge resistor is disposed in a semiconductor module, thereby achieving both cooling of the semiconductor module and cooling of the discharge resistor.

[0007] However, Patent Documents 1 and 2 only describe double-sided cooling 1-in-1 and 2-in-1 card-type semiconductor modules, and do not describe single-sided cooling (flat pin fin, etc.) 6-in-1 flat-type semiconductor modules that are widely available on the market.

[0008] Meanwhile, in recent years, semiconductor modules 1 have begun to use SiC chips as the chips inside. SiC chips are smaller than conventional Si chips. However, from the perspective of installation compatibility when replacing parts, the external dimensions of the semiconductor module are often not changed from conventional products. In other words, semiconductor modules 1 equipped with SiC chips have excess space inside the semiconductor module 1.

[0009] In view of the above, when a power converter is assembled using semiconductor modules, it is necessary to reduce the size of the power converter, improve the ease of assembly, and improve the cooling effect of the discharge resistor. [Means for solving the problem]

[0010] The present invention was devised in view of the above-mentioned problems of the conventional technology, and one aspect of the present invention is a 6-in-1 type semiconductor module having three phases of legs, each leg having two switching elements connected in series between a positive pole and a negative pole, and characterized in that a discharge resistor is connected between the positive pole and the negative pole within the semiconductor module.

[0011] In one aspect, the discharge resistor is connected in parallel to only one leg of the three phases.

[0012] In one embodiment, the discharge resistors are connected in parallel to all three phase legs.

[0013] In one embodiment, the switching element is equipped with a SiC chip.

[0014] Another aspect is a 2-in-1 type semiconductor module having one phase of a leg in which two switching elements are connected in series between a P pole and an N pole, characterized in that the switching elements are equipped with SiC chips and a discharge resistor is connected between the P pole and the N pole within the semiconductor module.

[0015] Another aspect is a 1-in-1 type semiconductor module having a switching element connected to a P pole or an N pole, characterized in that the switching element is equipped with a SiC chip and a discharge resistor is connected in parallel to the switching element in the semiconductor module.

[0016] In another aspect, the power conversion device is characterized by comprising a semiconductor module and a smoothing capacitor connected between the P pole and the N pole. [Effects of the Invention]

[0017] According to the present invention, when a power converter is assembled using semiconductor modules, it is possible to reduce the size of the power converter, improve assembly efficiency, and improve the cooling effect of the discharge resistor. [Brief explanation of the drawings]

[0018] [Figure 1] FIG. 1 is a circuit diagram showing an example of a conventional power conversion device. [Figure 2] 1 is a circuit diagram showing a power conversion device using a 6-in-1 type semiconductor module according to an embodiment. [Figure 3] 1 is a circuit diagram showing a power conversion device using a 2-in-1 type semiconductor module according to an embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0019] An embodiment of the semiconductor module of the present invention will be described in detail below with reference to FIGS.

[0020] [Embodiment] A circuit diagram of a power conversion device (for example, an inverter: hereinafter referred to as an inverter) in this embodiment is shown in Fig. 2. Fig. 2 shows a configuration using one 6-in-1 type semiconductor module.

[0021] First, a typical inverter will be explained based on the electrical circuit diagram in Figure 2. As shown in Figure 2, a smoothing capacitor (for example, a film capacitor) C is connected between the P pole and N pole. The smoothing capacitor C serves to smooth the DC link voltage.

[0022] In addition, switching elements Su and Sx, switching elements Sv and Sy, and switching elements Sw and Sz are connected in series between the P pole and the N pole. In this way, there are three phases of legs, each with two switching elements connected in series. The six switching elements Su to Sz (three-phase legs) make up a 6-in-1 type semiconductor module 1.

[0023] A motor M is connected to the AC side (the connection point of the switching elements Su and Sx, the connection point of the switching elements Sv and Sy, and the connection point of the switching elements Sw and Sz) of the semiconductor module 1. A current sensor 2 is provided between the semiconductor module 1 and the motor M.

[0024] Furthermore, a discharge resistor R is connected between the P pole and the N pole in the semiconductor module 1. In Fig. 2, the discharge resistor R is connected in parallel to the legs (series circuits) of the switching elements Su and Sx. As shown in Fig. 2, in this embodiment, the discharge resistor R is connected to the legs rather than to each arm.

[0025] Here, FIG. 2 shows a configuration in which a discharge resistor R is connected to the leg (series circuit) of the switching element Su and the switching element Sx, but the discharge resistor R may also be connected to the leg (series circuit) of the switching element Sv and the switching element Sy or the leg (series circuit) of the switching element Sw and the switching element Sz.

[0026] Furthermore, in Fig. 2, a discharge resistor R is connected to one of the three-phase legs, but as shown by the dotted lines in Fig. 2, the discharge resistor R may be connected to all three phase legs or to two of the three phase legs. The discharge resistor R is provided to discharge the charge in the smoothing capacitor C when the input power of the inverter is turned off, thereby preventing electric shock accidents.

[0027] As shown in Figure 2, by connecting a discharge resistor R to one leg of a 6-in-1 type semiconductor module 1 at once, it is possible to reduce the size and improve assembly efficiency (reducing the number of mounted parts when assembling the inverter) because there is no need to provide a discharge resistor R outside the semiconductor module 1. Furthermore, the discharge resistor R can also benefit from the cooling effect of the semiconductor module 1.

[0028] When the discharge resistor R is connected to only one leg, only one discharge resistor R is required in the semiconductor module 1, and therefore the number of steps required to assemble the semiconductor module 1 can be reduced.

[0029] Furthermore, as shown by the dotted line in Figure 2, it is also possible to mount the discharge resistor R not only on one leg but also on two or three legs. By doing so, the discharge resistor R, which is a heat source, can be dispersed, making cooling (heat dissipation) easier than when the discharge resistor R is connected to only one leg.

[0030] Furthermore, as described above, the semiconductor module 1 using SiC chips has a large amount of spare space within the semiconductor module 1. Therefore, when this embodiment is applied, the work of attaching the discharge resistor R during assembly of the semiconductor module 1 becomes easier, and the number of steps in manufacturing the semiconductor module 1 can be reduced.

[0031] This effect applies not only to the 6-in-1 type semiconductor module 1, but also to a 1-in-1 type semiconductor module or a 2-in-1 type semiconductor module using a SiC chip.

[0032] Fig. 3 shows a circuit diagram in which this embodiment is applied to a power conversion device using 2-in-1 type semiconductor modules. The same parts as in Fig. 2 are given the same reference numerals, and their explanations will be omitted. As shown in Fig. 3, three 2-in-1 type semiconductor modules are provided.

[0033] Specifically, the legs of switching elements Su and Sx constitute semiconductor module 1u, the legs of switching elements Sv and Sy constitute semiconductor module 1v, and the legs of switching elements Sw and Sz constitute semiconductor module 1w. In this way, in Fig. 3, a 2-in-1 type semiconductor module is configured in which one semiconductor module is made up of one phase leg in which two switching elements are connected in series between the P pole and the N pole.

[0034] A discharge resistor R is connected between the P pole and N pole in the semiconductor module 1u (in parallel to the legs of the switching element Su and the switching element Sx). The discharge resistor R is the same as in FIG. 2, and the discharge resistor R may be connected in the semiconductor module 1v or in the semiconductor module 1w.

[0035] Furthermore, although Figure 3 shows a configuration in which a discharge resistor R is provided in one semiconductor module 1u out of the three semiconductor modules 1u, 1v, and 1w, a discharge resistor R may also be provided in two of the three semiconductor modules 1u, 1v, and 1w, or in all three semiconductor modules.

[0036] Although not shown, a 1-in-1 type semiconductor module may be formed by mounting SiC chips on the switching elements Su to Sz connected to the P pole or N pole. In this case, a discharge resistor R is installed in the two semiconductor modules that make up the same phase. It is sufficient to provide a discharge resistor R for at least one phase, and discharge resistors R may be provided for two or three phases.

[0037] As described above, according to this embodiment, the discharge resistor R is built into the 6-in-1 type semiconductor module 1, so that the total number of parts for the semiconductor module 1 and the discharge resistor R is only one, the 6-in-1 type semiconductor module 1. This reduces the number of parts when assembling the power conversion device, thereby enabling the power conversion device to be made smaller and easier to assemble.

[0038] Furthermore, the cooling mechanism provided in the semiconductor module 1 can actively cool the discharge resistor R, thereby improving the cooling effect of the discharge resistor R.

[0039] Furthermore, while currently semiconductor modules 1 are mainly made of Si, using SiC creates more space for chip mounting within the semiconductor module 1, making it easier to manufacture the semiconductor module 1 and making it easier to apply this embodiment.

[0040] Although the present invention has been described in detail above only with respect to the specific examples, it will be apparent to those skilled in the art that various modifications and variations are possible within the scope of the technical concept of the present invention, and it is natural that such modifications and variations fall within the scope of the claims. [Explanation of symbols]

[0041] C: Smoothing capacitor R…discharge resistance Su~Sz...Switching elements 1, 1u, 1v, 1w... semiconductor modules 2...Current sensor M...Motor

Claims

1. A 6-in-1 type semiconductor module having three phase legs, each leg having two switching elements connected in series between a positive pole and a negative pole, a discharge resistor connected between the P pole and the N pole in the semiconductor module;

2. The discharge resistor is 2. The semiconductor module according to claim 1, wherein the semiconductor module is connected in parallel to only one leg of the three phases.

3. The discharge resistor is 2. The semiconductor module according to claim 1, wherein all three phase legs are connected in parallel.

4. 2. The semiconductor module according to claim 1, wherein the switching element is a SiC chip.

5. A 2-in-1 type semiconductor module having one phase leg in which two switching elements are connected in series between a positive pole and a negative pole, The switching element is equipped with a SiC chip, a discharge resistor connected between the P pole and the N pole in the semiconductor module;

6. A 1-in-1 type semiconductor module having a switching element connected to a P pole or an N pole, The switching element is equipped with a SiC chip, A semiconductor module, characterized in that a discharge resistor is connected in parallel to the switching element in the semiconductor module.

7. a semiconductor module according to claim 1, claim 5, or claim 6; a smoothing capacitor connected between the positive pole and the negative pole; A power conversion device comprising:

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