JP5900082B2 - Semiconductor device - Google Patents

Description

  The present invention relates to a semiconductor device, and in particular, a first operating voltage region in which an operating current flowing for the same operating voltage decreases as the temperature increases, and an operating current flowing for the same operating voltage increases as the temperature increases. The present invention relates to a semiconductor device including a semiconductor element having a second operating voltage region.

  Conventionally, a semiconductor device with reduced power loss is known (see, for example, Patent Document 1). This semiconductor device includes a bipolar transistor (IGBT) and a unipolar transistor (MOS) connected in parallel between a power supply and a load. In this semiconductor device, a driving element is selected according to a load state, and a transistor having a lower saturation voltage among bipolar transistors and unipolar transistors is used as a driving element, so that power loss can be reduced. .

JP 2010-279193 A

  However, in the device described in Patent Document 1, it is necessary to prepare different types of bipolar transistors and unipolar transistors that are connected in parallel in order to reduce power loss. As a result, the circuit scale becomes large and it is extremely difficult to find a cost advantage.

  The present invention has been made in view of the above-described points, and an object thereof is to provide a semiconductor device capable of improving power loss with a simple configuration.

The above object is a semiconductor device mounted on a vehicle equipped with a load, and the first operating voltage region where the operating current flowing with respect to the same operating voltage decreases as the temperature increases, and the same operating voltage flows. possess a second operating voltage region where the operating current is increased as the temperature becomes higher, the temperature characteristics including, the operated at the first operating voltage region during high-load running operation of the vehicle, while low in the vehicle A semiconductor element that operates in the second operating voltage region during a load operation operation and a temperature higher than that during the operation in the first operating voltage region during operation in the second operating voltage region. And a temperature control means for controlling the state.

  According to the present invention, power loss can be improved with a simple configuration.

It is a block diagram of the semiconductor device which is one Example of this invention. It is a figure showing the temperature characteristic about the relationship between the forward voltage and forward current of the semiconductor element with which the semiconductor device of a present Example is provided. It is a flowchart of an example of the control routine performed in the semiconductor device of the present embodiment. It is a flowchart of an example of the control routine performed in the semiconductor device which is the modification of this invention. It is a figure showing the relationship between temperature and loss in the semiconductor device of this modification.

  Hereinafter, specific embodiments of a semiconductor device according to the present invention will be described with reference to the drawings.

  FIG. 1 shows a configuration diagram of a semiconductor device 10 according to an embodiment of the present invention.

  The semiconductor device 10 of this embodiment is used for an in-vehicle power control unit 12 mounted on a vehicle such as a hybrid vehicle or a plug-in hybrid vehicle. In the present embodiment, as shown in FIG. 1, the vehicle is driven by a tire 22 using an engine 14, two motor generators (MG) 16 and 18, and a speed reducer 20, and the tire 22 It is a vehicle that is regenerated when the vehicle is decelerated. That is, the tire 22 is rotationally driven by the rotational torque of the engine 14 associated with the fuel supply and the rotational torque of the MGs 16 and 18 associated with the power supply from the in-vehicle battery 24, and the regenerative torque at the time of tire deceleration is MG16, 18 The in-vehicle battery 24 is charged by being converted into electric energy by the power generation.

  The in-vehicle power control unit 12 includes an in-vehicle battery 24, a boost converter 26, and two inverters 28 and 30. The in-vehicle battery 24 is a chargeable / dischargeable secondary battery that outputs a DC voltage of about 244 volts, for example. Boost converter 26 boosts the output DC voltage of in-vehicle battery 24 up to a predetermined DC voltage (for example, 650 volts) and can charge in-vehicle battery 24 with the DC voltage obtained by power generation by MGs 16 and 18. It is a converter that steps down to a DC voltage.

  The inverter 28 is a drive circuit that controls the MG 16, and is a power converter that converts a voltage from direct current to alternating current and converts from alternating current to direct current between the in-vehicle battery 24 and the MG 16. The inverter 30 is a drive circuit that controls the MG 18 and is a power converter that converts a voltage from direct current to alternating current and converts from alternating current to direct current between the in-vehicle battery 24 and the MG 18.

  In the above configuration, the engine 14 generates rotational torque that rotates the tire 22 by supplying fuel. In addition, when the tire 22 is rotationally driven, the in-vehicle power control unit 12 drives the boost converter 26 and the inverters 28 and 30 to boost the output DC voltage of the in-vehicle battery 24 and supply power to the MGs 16 and 18. In this case, the MGs 16 and 18 generate rotational torque that rotates the tire 22 by such power supply. When rotational torque is generated in the engine 14 and / or the MGs 16 and 18, the tire 22 is rotationally driven.

  Further, when the tire 22 is decelerated, the in-vehicle power control unit 12 drives the boost converter 26 and the inverters 28 and 30 to generate electric power of the MGs 16 and 18 to convert the rotational torque of the tire 22 into electric energy and to reduce the pressure. In this case, the electric energy obtained by converting the rotational torque of the tire 22 is stepped down and supplied to the in-vehicle battery 24, whereby the in-vehicle battery 24 is charged.

  In the present embodiment, the semiconductor device 10 includes a bipolar semiconductor element 40. The semiconductor element 40 is a power semiconductor that constitutes the boost converter 26 or a power semiconductor that constitutes the inverters 28 and 30, and includes a semiconductor switching element 42 and a semiconductor diode 44. The semiconductor switching element 42 is an IGBT (Insulated Gate Bipolar Transistor). The semiconductor diode 44 is a PIN diode or the like.

  FIG. 2 shows the relationship between the forward voltage and forward current of the semiconductor element 40 included in the semiconductor device 10 of this embodiment (for example, the collector-emitter voltage when the gate-emitter voltage of the semiconductor switching element 42 is constant). The figure showing the temperature characteristic about the relationship between VCE and collector current IC, ie, the on-voltage characteristic of the semiconductor switching element 42, is shown.

  The semiconductor element 40 has a relationship as shown in FIG. 2 between the forward voltage and the forward current. Regarding the relationship between the forward voltage and the forward current, the semiconductor element 40 has a first operating voltage region in which the operating current flowing for the same operating voltage decreases as the temperature increases, and the operating current flowing for the same operating voltage. Has a second operating voltage region that increases as the temperature increases, and has a point at which the temperature characteristic is switched to the reverse characteristic (hereinafter, referred to as a cross point as appropriate). The first operating voltage region is set on the high voltage side and the high current side with respect to the second operating voltage region.

  For example, in the semiconductor switching element 42 which is an IGBT, the first operating voltage region is smaller as the collector current Ic flowing with respect to the same collector-emitter voltage Vce is higher, and the second operation voltage region is the second operation voltage region. The voltage region increases as the collector current Ic flowing for the same collector-emitter voltage Vce increases. The semiconductor element 40 is generally operated in the first operating voltage region in order to ensure thermal stability.

  The in-vehicle power control unit 12 also includes a cooler 50. The cooler 50 is disposed in the vicinity of the boost converter 26 and the inverters 28 and 30 (particularly in the vicinity of the semiconductor switching element 42), and is a water-cooled cooling device that cools the boost converter 26 and the inverters 28 and 30. The cooler 50 may be an air cooling type. Heat generated by the boost converter 26 and the inverters 28 and 30 is transmitted to the medium (water) in the cooler 50.

  A water pump 54 and a radiator 56 are connected to the cooler 50 via a cooling passage 52. The water pump 54 is an electric pump that circulates a medium (water) between the cooler 50 and the radiator 56 via the cooling passage 52. An electronic control unit (hereinafter referred to as ECU) 60 is connected to the water pump 54. The ECU 60 circulates the medium (water) by operating the water pump 54 when the boost converter 26 and the inverters 28 and 30 are operated. The medium (water) to which heat has been transmitted in the cooler 50 is sent to the radiator 56 through the cooling passage 52 by the operation of the water pump 54. The radiator 56 radiates heat transferred to the medium (water).

  The ECU 60 is also connected with a temperature sensor 62 for detecting the temperature of the semiconductor element 40. The temperature sensor 62 outputs a signal corresponding to the temperature of the semiconductor element 40. The ECU 60 detects the temperature of the semiconductor element 40 based on the output signal of the temperature sensor 62.

  FIG. 3 shows a flowchart of an example of a control routine executed by the ECU 60 in the semiconductor device 10 of the present embodiment.

  In this embodiment, the ECU 60 is supplied with information indicating whether or not a low load driving operation is requested in the vehicle. This information includes whether or not the vehicle driver has switched on for eco-mode driving, whether the vehicle continues to operate at low load without increasing its output, or whether the vehicle is operating at low load in cooperation with the navigation system. Information indicating whether or not expected. In addition, the “low load operation operation” means that the semiconductor element 40 of the semiconductor device 10 operates in a region below the cross point having a thermal margin, that is, the second operating voltage region, for example, the semiconductor switching element 42. Is turned on with a relatively low collector-emitter voltage Vce and a relatively low collector current Ic.

  The ECU 60 determines whether or not a low load driving operation is required in the vehicle (step 100). When the low load operation is performed in the vehicle, the semiconductor element 40 of the semiconductor device 10 operates in the second operating voltage region where the operating current flowing for the same operating voltage increases as the temperature increases. If the low load operation is not requested as a result of the above determination, the ECU 60 operates the water pump 54 so that a normal output is generated when the boost converter 26 and the inverters 28 and 30 are operated, and the cooler 50 Are operated so that the desired cooling performance is exhibited (step 102). In this case, the boost converter 26 of the semiconductor device 10 and the semiconductor elements 40 of the inverters 28 and 30 are cooled to a desired state.

  On the other hand, as a result of the above determination, the ECU 60 reduces the output of the water pump 54 from the normal output when the boost converter 26 and the inverters 28 and 30 are operated when the low load operation is required. The cooling performance of the cooler 50 is lowered below the desired cooling performance (step 104). In this case, the degree of decrease in the output of the water pump 54 from the normal time or the degree of decrease in the cooling performance of the cooler 50 from the normal time may be determined in advance, for example, the operation of the water pump 54 It may be a stop or a cooling stop of the cooler 50.

  In this case, that is, when the cooling performance of the cooler 50 is deteriorated, each semiconductor element 40 becomes difficult to be cooled by the cooler 50, so that each of the semiconductor elements 40 is in a higher temperature than the temperature due to the desired cooling. Become. When the semiconductor element 40 is in a high temperature state in the second operating voltage region, the operating current flowing in the semiconductor element 40 with respect to the same operating voltage is larger than that in the low temperature state. Becomes easier to flow.

  Therefore, according to the present embodiment, the steady loss of the semiconductor element 40 is reduced by operating the semiconductor element 40 at a high temperature by lowering the cooling performance of the cooler 50 in the low load operation operation as compared with the high load operation operation. be able to. For this reason, it is possible to reduce the power loss during the low load operation, and to improve the operation efficiency of the boost converter 26 and the inverters 28 and 30. As a result, the fuel consumption loss of the vehicle can be improved. It is. In particular, since the semiconductor element 40 of the upper arm of the boost converter 26 is on the power path between the in-vehicle battery 24 and the MGs 16 and 18, there is a possibility that a great power loss may occur. Since the power loss can be reduced, the power loss can be effectively reduced.

  Moreover, in said structure, when reducing a power loss at the time of low load driving | running operation | movement, the output of the water pump 54 is reduced rather than a normal output. For this reason, according to the present embodiment, the power itself consumed by the water pump 54 during the low load operation can be reduced, and the auxiliary machine loss in the water pump 54 can be reduced. It is possible to improve the reduction effect.

  In the above configuration, it is not necessary to prepare a plurality of different types of semiconductor elements connected in parallel in order to reduce power loss during low-load operation, so the number of parts is minimized and the circuit scale is reduced. The cost can be reduced and the cost can be reduced. Thus, according to the semiconductor device 10 of the present embodiment, it is possible to improve the power loss with a simple configuration.

  Further, in the present embodiment, the ECU 60 determines whether or not the temperature of the semiconductor element 40 has exceeded the standard after the cooling performance of the cooler 50 is lowered in the above step 104 (step 106). This standard is an upper limit temperature that is predetermined as a range in which the semiconductor element 40 operates normally. When the temperature of the semiconductor element 40 has not exceeded the standard as a result of the above determination, the ECU 60 repeatedly executes the processing from step 100 onward.

  On the other hand, if the ECU 60 determines in step 106 that the temperature of the semiconductor element 40 has exceeded the standard, the semiconductor element 40 may not operate normally thereafter. Execute. That is, by canceling the decrease in the output of the water pump 54 and canceling the decrease in the cooling performance of the cooler 50, the water pump 54 is operated so that a normal output is generated when the boost converter 26 and the inverters 28 and 30 are operated. Then, the cooler 50 is operated so that a desired cooling performance is exhibited.

  If the cooling performance of the cooler 50 returns to a desired one, the semiconductor element 40 is cooled as usual, and normal operation of the semiconductor element 40 is ensured. Therefore, according to the present embodiment, the cooling performance of the cooler 50 is forcibly lowered to promote the temperature rise of the semiconductor element 40, thereby improving the power loss as much as possible, and the semiconductor element 40 is normal as the temperature rises. A situation in which the operation is not ensured can be avoided.

In the above embodiment, the ECU 60 executes the processing of steps 100 to 106 in the routine shown in FIG. 3 in the “ temperature control means” described in the claims, and the ECU 60 outputs the output signal of the temperature sensor 62. Detecting the temperature of the semiconductor element 40 based on the above corresponds to “temperature detection means” recited in the claims.

  In the above embodiment, the output of the water pump 54 is reduced or the cooling performance of the cooler 50 is lowered in order to reduce the overall power loss during the low load operation. The degree of decrease in the output of the pump 54 from the normal time or the degree of decrease in the cooling performance of the cooler 50 from the normal time may be set so that the semiconductor element 40 is adjusted to an optimum temperature.

  In the second operating voltage region, the semiconductor element 40 has a higher steady-state loss in the high-temperature state than the low-temperature state, but tends to increase the switching loss. Even if the value is lowered, there is a possibility that the power loss cannot be reduced as a whole. Therefore, a map that defines the characteristic relationship between the temperature and loss of the semiconductor element 40 is prepared in advance, and both the steady loss and switching loss of the semiconductor element 40 are taken into consideration, and the normal output of the water pump 54 is normal. It is good also as setting appropriately the fall degree from the normal time or the fall degree of the cooling performance of the cooler 50. According to such a modification, the temperature of the semiconductor element 40 is adjusted to the optimum temperature so that the overall power loss effect is most exhibited during the low load operation, so that the overall power loss can be reduced. It becomes.

  Further, when the output of the water pump 54 is lowered to a predetermined output or the cooling performance of the cooler 50 is lowered to a predetermined cooling performance during the low load operation, the output reduction or the cooling performance is reduced as a whole power loss. It is good also as canceling | releasing when it continues until the time when a reduction effect is acquired, and the power loss reduction effect is no longer acquired.

  That is, in such a modification, the ECU 60 first executes the routine shown in FIG. 4 instead of the routine shown in FIG. 3, and the operating states (for example, temperature, voltage, current) of the boost converter 26 and the inverters 28, 30. , Carrier), and a map that defines the relationship between each loss of steady loss, auxiliary machinery loss, switching loss, and overall loss.

  Then, after reducing the cooling performance of the cooler 50 in step 104, the ECU 60 monitors the operating state (for example, temperature, voltage, current, carrier) of the boost converter 26 and the inverters 28, 30 (step 200). Based on the monitored operation state, it is determined whether or not the effect of reducing the power loss generated when the semiconductor element 40 is operated can be obtained (step 202). If it is determined that the power loss reduction effect is obtained, it is next determined in step 106 whether or not the temperature of the semiconductor element 40 has exceeded the standard, and on the other hand, the power loss reduction effect is not obtained. If so, then in step 102, the cooling performance of the cooler 50 is returned to the desired one as usual.

  The monitoring in step 200 and the determination in step 202 are performed before determining in step 106 whether or not the temperature of the semiconductor element 40 has exceeded the standard. It may be performed when it is determined that the temperature does not exceed the standard.

  According to such a modification, the temperature of the semiconductor element 40 can be adjusted to an optimum temperature at which the power loss is reduced to the maximum according to the temperature-loss characteristics as shown in FIG. It becomes possible to reduce the overall power loss considering the switching loss. Note that the execution of step 202 in the routine shown in FIG. 4 by the ECU 60 corresponds to the “loss reduction effect determining means” recited in the claims.

  Further, in the above embodiment, the medium is circulated in the cooling passage 52 using the water pump 54 and the heat of the boost converter 26 and the inverters 28 and 30 is radiated by the radiator 56, thereby the boost converter 26 and the inverter 28. , 30 is cooled, but the present invention is not limited to this, and the boost converter 26 and the inverters 28, 30 may be cooled using an air cooling fan.

  In the above embodiment, the semiconductor element 40 is operated at a high temperature by reducing the output of the water pump 54 and reducing the cooling amount by the cooler 50 during the low load operation. However, the present invention is not limited to this, and the semiconductor element 40 is heated by heating the semiconductor element 40 using a heating device that heats the semiconductor element 40 during a low load operation, that is, by increasing the heating amount of the semiconductor element 40. May be operated at a high temperature. Furthermore, in this case, the amount of heating for heating the semiconductor element 40 may be increased while the amount of cooling by the cooler 50 is reduced.

  Further, the above embodiment is an example in which the semiconductor switching element 42 which is an IGBT and the semiconductor diode 44 such as a semiconductor PIN diode are used as the semiconductor element 40, but the present invention is not limited to this. As described above, at least the first operating voltage region where the operating current flowing for the same operating voltage decreases as the temperature increases, and the operating current flowing for the same operating voltage increases as the temperature increases. A semiconductor element having an operating voltage region is sufficient.

  Furthermore, in the above embodiment, the semiconductor device 10 is mounted on a vehicle. However, the present invention is not limited to this and can be applied to other than the vehicle.

DESCRIPTION OF SYMBOLS 10 Semiconductor device 26 Boost converter 28,30 Inverter 40 Semiconductor element 42 Semiconductor switching element 44 Semiconductor diode 50 Cooler 54 Water pump 60 Electronic control unit (ECU)
62 Temperature sensor

Claims (6)

A semiconductor device mounted on a vehicle having a load,
A first operating voltage region in which the operating current flowing for the same operating voltage decreases as the temperature increases; and a second operating voltage region in which the operating current flowing for the same operating voltage increases as the temperature increases. have a temperature characteristic, said being operated in the first operating voltage region during high-load running operation of the vehicle, whereas, a semiconductor element is operated at the second operating voltage range at low load running operation in the vehicle,
Temperature control means for controlling the semiconductor element to a higher temperature state when operating in the second operating voltage region than when operating in the first operating voltage region;
A semiconductor device comprising:   The temperature control means reduces the amount of cooling by a cooler that cools the semiconductor element when operating in the second operating voltage region as compared to when operating in the first operating voltage region. The semiconductor device according to claim 1.   The temperature control means increases a heating amount by a heater that heats the semiconductor element when operating in the second operating voltage region as compared to when operating in the first operating voltage region. The semiconductor device according to claim 1 or 2. Temperature detecting means for detecting the temperature of the semiconductor element;
The temperature control unit cancels the control of the high temperature state of the semiconductor element when the temperature of the semiconductor element detected by the temperature detection unit exceeds a standard after controlling the semiconductor element to a high temperature state. The semiconductor device according to claim 1, wherein the semiconductor device is a semiconductor device. Loss reduction effect determining means for determining whether or not there is an effect of reducing power loss generated when operating the semiconductor element after the semiconductor element is controlled to a high temperature state by the temperature control means,
The temperature control means releases control of the high temperature state of the semiconductor element when it is determined that there is no loss reduction effect of the power loss after controlling the semiconductor element to a high temperature state. Item 5. The semiconductor device according to any one of Items 1 to 4.   The semiconductor device according to claim 1, wherein the semiconductor element is an element used in a boost converter.

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