JP2002118227A - Power semiconductor device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make junction temperatures nearly equal based on difference in cooling effect, and to increase current capacity as a whole in a power semiconductor device that fixes a plurality of semiconductor devices onto a radiation substrate for connecting in parallel. SOLUTION: This power semiconductor device fixes the plurality of semiconductor devices that accommodate bipolar transistors and field effect transistors Q1 to Qn into a package onto the radiation substrate, has a main control circuit MC that connects the plurality of semiconductors in parallel and at the same time detects current for controlling a sharing current, and circulates cooling air to the radiation substrate for cooling the semiconductor device. In this case, resistance values Rs1 to Rsn for detecting the current of each semiconductor device are set so that the amount of the current that is allowed to flow to the semiconductor device positioned at the suction side of the cooling air is larger than that of the current that is allowed to flow to the semiconductor device positioned at the exhaust side of the cooling air in order along the circulation direction of the cooling air of the semiconductor device fixed onto the radiation substrate.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a power semiconductor device in which a plurality of semiconductor devices such as bipolar transistors and field effect transistors are fixed to a heat dissipation substrate and connected in parallel.

[0002]

2. Description of the Related Art FIG. 4 is an explanatory view of a power semiconductor device.
41-1 to 41-n are semiconductor devices such as bipolar transistors and field effect transistors housed in a package, 42 is a heat dissipation substrate made of a metal such as aluminum,
Reference numeral 3 denotes a radiation fin, 44 denotes a printed wiring board, and 45 denotes a cooling fan.

Each of the semiconductor devices 41-1 to 41-n has a configuration in which a bipolar transistor, a field effect transistor, and the like are sealed in an insulating package and terminals are led out. The heat radiation board 42 is fixed to the printed wiring board 44, and the terminals of the semiconductor devices 41-1 to 41-n are connected to, for example, the printed wiring on the back surface of the printed wiring board 44. The cooling fan 45 allows cooling air to flow between the radiating fins 43 of the radiating substrate 42. In the illustrated case, the internal air is discharged to the outside by the cooling fan 45 and the cooling fan 4
5 shows a case in which air is sucked in from the side opposite to 5, and cooling air flows in the direction of the arrow to cool the semiconductor devices 41-1 to 41-n via the heat dissipation substrate 42.

The semiconductor devices 41-1 to 41-n are connected in parallel to shunt the current from a DC power supply.
Large current can be controlled by increasing the number of parallel connections. In addition, the flow of the current causes the semiconductor device 4
The temperature at the junction of 1-1 to 41-n increases. If this temperature exceeds a predetermined value, thermal runaway or burnout will occur. As described above, the semiconductor devices 41-1 to 41-n are fixed to the heat dissipation substrate 42 via a heat conductive insulating film or the like.
The heat generated by the semiconductor devices 41-1 to 41-n is transferred to the heat dissipation substrate 42.
And the heat dissipating substrate 42 is cooled by the cooling air.

FIG. 5 is an explanatory view of a conventional example, in which Q1-Qn
Is a field-effect transistor corresponding to the aforementioned semiconductor devices 41-1 to 41-n, Rs1 to Rsn are current detecting resistors, R1 to Rn are resistors, DA is an operational amplifier, Vr is a reference voltage, PW is a primary battery, Rechargeable batteries, large capacity capacitors,
1 shows a power supply device such as a switching power supply. In this case, a configuration as an electronic load device for testing the power supply device PW is shown.

The resistors Rs1 to Rsn have the same resistance value, and the resistors R1 to Rn also have the same resistance value. The reference voltage Vr is configured to be variable. Currents I1 to In flowing through the field effect transistors Q1 to Qn are detected by resistors Rs1 to Rsn, and the detected current values are input to the-terminal of the operational amplifier DA via the resistors R1 to Rn, and the reference voltage is input to the + terminal. A control voltage is applied to the gates of the field effect transistors Q1 to Qn in accordance with the difference from Vr, and currents I1 to I4 corresponding to the reference voltage Vr are applied.
Control is performed so that In flows into the field effect transistors Q1 to Qn.

Therefore, assuming that the current supplied from the power supply device PW is Ip, currents I1 to Ip of Ip / n flow through the respective field effect transistors Q1 to Qn, and the output voltage Vp of the power supply device PW at that time. Is measured, the characteristic of the output current versus the output voltage of the power supply device PW can be obtained.

[0008]

The semiconductor devices 41-1 to 41-n accommodating a bipolar transistor, a field effect transistor and the like in a package are fixed to a heat dissipation substrate 42.
In the configuration in which the heat dissipation substrate 42 is cooled by the cooling air and the semiconductor devices 41-1 to 41-n are cooled through the heat dissipation substrate 42, the semiconductor devices 41-1 to 41-41 are arranged in a direction along the flow of the cooling air. -N is generally arranged. In this case, the temperature of the cooling air is higher on the exhaust side than on the intake side. Therefore, the heat dissipation board 42 has a temperature distribution in which the temperature on the exhaust side is higher than the temperature on the intake side of the cooling air. Therefore, the temperature of the semiconductor devices 41-1 to 41-n arranged on the exhaust side of the cooling air from the intake side increases.

FIG. 6 shows a case where the semiconductor devices 41-1 to 41-n are fixed to the heat dissipation board 42 such that the semiconductor device 41-1 is on the cooling air intake side and the semiconductor 41-n is on the cooling air exhaust side. 3 shows junction temperatures of semiconductor portions of the semiconductor devices 41-1 to 41-n. That is, the semiconductor device 41
The temperature is in accordance with the arrangement order of -1 to 41-n. For that reason,
Semiconductor device 41-n disposed on the cooling air discharge side
Is limited to the current according to the junction temperature constraint. At this time, although the junction temperature of the semiconductor device 41-1 disposed on the cooling air intake side is a value that can withstand sufficiently, the semiconductor device 41-1 flows to the semiconductor device 41-n disposed on the cooling air discharge side. Limited to the current you get.
That is, there is a problem that the capabilities of all the semiconductor devices 41-1 to 41-n cannot be sufficiently utilized. An object of the present invention is to increase current capacity as a whole by performing current sharing control so that the junction temperature of a semiconductor device becomes substantially equal.

[0010]

According to the power semiconductor device of the present invention, a plurality of semiconductor devices accommodating a bipolar transistor or a field-effect transistor in a package are fixed to a heat dissipation substrate, and the plurality of semiconductor devices are connected in parallel to each other. A power semiconductor device that has a main control circuit that detects and controls a shared current and circulates cooling air to the heat dissipation substrate to cool the semiconductor device. In order along the flow direction, the current detection resistance of each semiconductor device is set so that the current flowing to the semiconductor device located on the intake side of the cooling air is larger than the current flowing to the semiconductor device located on the exhaust side of the cooling air. The configuration is such that a value is set.

[0011] Further, a plurality of semiconductor devices are fixed to a heat dissipation substrate,
A power semiconductor device having a main control circuit for connecting the plurality of semiconductor devices in parallel and detecting a current to control a shared current, and cooling the semiconductor device by flowing cooling air to the heat dissipation substrate. The resistance for detecting the current flowing through each of the plurality of semiconductor devices is set to the same resistance value, and a control signal for controlling the current flowing to the semiconductor device by the main control circuit is set based on the current detection value obtained by the current detection resistor. ,
The current flowing to the semiconductor device located on the intake side of the cooling air is larger than the current flowing to the semiconductor device located on the exhaust side of the cooling air in the order along the flow direction of the cooling air of the semiconductor device fixed to the heat dissipation substrate. Is provided.

The auxiliary control circuit includes a first voltage dividing circuit for dividing a current detection value by a current detection resistor flowing through the semiconductor device, and a value for commonly inputting the current detection value to the main control circuit via the resistor. And a operational amplifier that receives the voltage divided by the first and second voltage dividers and uses a value corresponding to the difference as a current control signal for the semiconductor device. I have.

[0013]

FIG. 1 is an explanatory view of a first embodiment of the present invention, wherein Q1 to Qn denote heat dissipation boards (not shown).
Field effect transistors constituting a semiconductor device (see FIG. 4) fixed to Rs1 to Rsn are resistors for detecting current,
1 to Rn are resistors, DA is an operational amplifier, Vr is a reference voltage,
MC is a main control circuit, PW is a power supply device such as a primary battery, a secondary battery, a large-capacity capacitor, a switching power supply, etc., AR is a flow direction of cooling air, and in this embodiment,
Current detection resistors Rs1 to Rsn of field effect transistors Q1 to Qn arranged along the direction of flow of cooling air
Is a resistance value in a relationship of Rs1 <Rs2 <... <Rsn.

A current detected by the current detecting resistors Rs1 to Rsn is input to the main control circuit MC via the resistors R1 to Rn, compared with a reference voltage Vr, and a control voltage corresponding to the difference is applied to a field effect transistor. It is applied to the gates of Q1 to Qn. Then, the same control voltage corresponding to the comparison difference is applied to the gate. The gate-source voltage of each of the field effect transistors Q1 to Qn is equal to the resistance Rs1 to Rs1.
The difference is caused by different values of Rsn. In this case, the gate-source voltage of the field-effect transistor Q1 located on the cooling air intake side becomes higher than the gate-source voltage of the field-effect transistor Qn located on the cooling air exhaust side, and the flowing current increases. .

Therefore, the field effect transistors Q1 to Qn
Currents I1 to In are I1>I2>... In. Thereby, each of the field effect transistors Q1 to Qn
Is not cooled, the junction temperature corresponding to the flowing currents I1 to In, that is, the junction temperature of the field effect transistor Q1 is high, and the field effect transistor Qn
Junction temperature decreases.

In this case, each of the field effect transistors Q1 to Q1
Qn is cooled through the heat dissipation substrate, and compared to the field effect transistor Qn, the field effect transistor Q1
The cooling effect of is increased. Therefore, since the cooling effect of the field effect transistor through which a large current flows is large, the junction temperatures of the field effect transistors Q1 to Qn can be made substantially the same. FIG. 2 shows the junction temperatures of the field effect transistors Q1 to Qn according to the present invention as compared with the conventional example. That is, in the conventional example (curve b), the junction temperature of the field-effect transistors Q1 to Qn is low on the intake side of the cooling air and high on the exhaust side according to the arrangement position along the flow direction of the cooling air. On the other hand, in the first embodiment (curve a), the junction temperatures of the field-effect transistors Q1 to Qn at the positions along the flow direction of the cooling air can be made substantially the same.

As described above, the increase in the junction temperature causes a restriction on the flowing current. However, by making the junction temperatures of the field effect transistors Q1 to Qn substantially the same, each of the field effect transistors Q1
To Qn can be supplied with the maximum current. That is, the current that can flow from the power supply device PW can be increased as compared with the conventional example by the field effect transistors Q1 to Qn connected in parallel. When the same output current is used, the amount of cooling air can be reduced. That is, a compact and economical configuration can be achieved.

FIG. 3 is an explanatory view of a second embodiment of the present invention. The same reference numerals as in FIG.
Cn is an auxiliary control circuit, OP1 to OPn are operational amplifiers, R
a1-Re1,... Ran1-Ren are resistors, Rg1-
Rgn indicates a gate resistance. Further, similarly to the first embodiment, a case is shown in which the field effect transistors Q1 to Qn are arranged on a heat dissipation substrate (not shown) in accordance with the cooling air distribution method indicated by the arrow AR.

The resistors Rs1 to Rsn for detecting current have the same resistance value, and the resistors Ra1, Rb1 to Ran, and Rbn have different resistance values. Also, the resistors Rc1, Rd1,
Re1 to Rcn, Rdn and Ren have the same resistance value,
R1 to Rn and Rg1 to Rgn have the same resistance value.

The auxiliary control circuits SC1 to SCn include resistors Ra
1, Rb1, Rc1, Rd1, Re1 to Ran, Rb
n, Rcn, Rdn, Ren and operational amplifiers OP1 to OP
Pn, and the current detection value by the current detection resistors Rs1 to Rsn corresponding to the field effect transistors Q1 to Qn,
The voltage is divided by a first voltage dividing circuit including resistors Ra1, Rb1 to Ran, and Rbn.
n are input to the resistors Rc1 and Rd1.
To Rcn, Rdn, Rdn, and Rdn, and input to operational amplifiers OP1 to OPn, respectively, and a signal corresponding to the difference between the divided voltage values is applied to the field effect transistors Q1 to Rn via resistors Re1 to Ren. Apply to the gate of Qn. Note that (Rc1, Rd1 to Rcn, Rdn) ≫ (R
1 to Rn).

The voltage dividing value of the first voltage dividing circuit consisting of the resistors Ra1 to Ran and Rb1 to Rbn is defined as Va1 to Van, and the second voltage dividing value comprising the resistors Rc1 to Rcn and Rd1 to Rdn.
Assuming that the voltage dividing values of the voltage dividing circuits are Vb1 to Vbn, the operational amplifiers OP1 to OPn provide Va1 = Vb1, Va2 =
The field effect transistors Q1 to Qn are controlled so that Vb2,... Van = Vbn. The main control circuit MC controls the current Ip from the power supply device PW corresponding to the reference voltage Vr.

The resistances Rc1 to Rcn are the same, and the resistance Rd1 is
To Rdn are the same, the divided voltage values Vb1 to Vbn of the second voltage dividing circuit have the same value. Therefore, Va1
<Va2 <... <Van
1 to Ran and Rb1 to Rbn are set. Thereby,
Currents I1-I flowing through field effect transistors Q1-Qn
When n is the same, Va1 <Va2 <... <Van, and Vb1 = Vb2 =... = Vbn. The auxiliary control circuits SC1 to SCn provide Va1 = Vb1,
..., the field effect transistors Q1 to Qn are controlled so that Van = Vbn, so that the current of the field effect transistors Q1 to Qn is I1>I2>.
> In.

Therefore, the current I flowing through the field effect transistor Q1 located on the intake side of the cooling air having a large cooling effect is obtained.
1 is increased, the current In flowing through the field effect transistor Qn located on the exhaust side of the cooling air having a small cooling effect is reduced, and the respective junction temperatures of the field effect transistors Q1 to Qn are substantially the same. The currents I1 to In can be controlled. That is, since a current that rises to an allowable junction temperature can flow, the field-effect transistors Q1 to Qn
As a result, the overall control current capacity can be increased. Further, the control current capacity as a whole may be the same as that of the conventional example, and the cooling air may be reduced, so that a compact and economical configuration can be realized.

In general, the characteristics of the field effect transistors Q1 to Qn vary, and such variations in the characteristics are corrected by the auxiliary control circuits SC1 to SCn.
Can be compensated by adjusting the resistors Rb1 to Rbn constituting the first voltage dividing circuit.

The present invention is not limited to the above-described embodiments, but can be variously added or changed. Bipolar transistors can be used instead of the field effect transistors Q1 to Qn. It is. Further, the present invention can be applied as a control circuit of a current supplied from the power supply device PW to a load (not shown). Further, the cooling fan for circulating the cooling air may be provided on the intake side of the cooling air to blow air from the outside along the heat radiating substrate.

[0026]

As described above, the present invention relates to a configuration in which a plurality of semiconductor devices are connected in parallel to share and flow a current and are fixed to a radiating substrate, and the radiating substrate is cooled by cooling air. The current flowing to the semiconductor device located on the intake side of the cooling air is controlled to be large, and the current flowing to the semiconductor device located on the exhaust side of the cooling air is controlled to be small. Even if the current flows and the junction temperature rises, the semiconductor device is cooled even if the junction temperature rises.Therefore, by gradually reducing the current flowing through the semiconductor devices arranged along the flow direction of the cooling air, the junction temperature of all the semiconductor devices becomes substantially the same. It can be. As a result, the current value that can flow as a whole can be increased as compared with the conventional example. Further, if the current value is the same as that of the conventional example, control can be performed so as not to increase to a predetermined junction temperature even if the cooling capacity is reduced, so that there is an advantage that downsizing and economy can be achieved.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram of a first embodiment of the present invention.

FIG. 2 is an explanatory diagram of a junction temperature according to the embodiment of the present invention.

FIG. 3 is an explanatory diagram of a second embodiment of the present invention.

FIG. 4 is an explanatory diagram of a power semiconductor device.

FIG. 5 is an explanatory diagram of a conventional example.

FIG. 6 is an explanatory diagram of a junction temperature in a conventional example.

[Explanation of symbols]

Q1 to Qn Field effect transistors constituting a semiconductor device Rs1 to Rsn Current detection resistors MC Main control circuit Vr Reference voltage DA Operational amplifier PW power supply AR Cooling air flow direction

Continued on the front page F term (reference) 5E322 AA01 BB03 5H430 BB09 BB12 EE06 EE13 FF08 HH03 LA06 LA10 LA21 LB02 5H740 BA11 BB02 BB07 MM11 PP06

Claims (3)

[Claims] A plurality of semiconductor devices fixed to a heat dissipation substrate;
A power control device for connecting the plurality of semiconductor devices in parallel and detecting a current to control a shared current, and for cooling the semiconductor device by flowing cooling air to the heat dissipation substrate; Current flowing in the semiconductor device located on the intake side of the cooling air in the order along the flow direction of the cooling air of the semiconductor device fixed to the heat dissipation substrate, A power semiconductor device wherein a current detection resistance value of each semiconductor device is set so as to be larger than a current flowing through the semiconductor device. 2. A plurality of semiconductor devices are fixed to a heat dissipation board,
A power control device for connecting the plurality of semiconductor devices in parallel and detecting a current to control a shared current, and for cooling the semiconductor device by flowing cooling air to the heat dissipation substrate; Controlling the resistors for detecting the current flowing through each of the plurality of semiconductor devices to have the same resistance value, and controlling the current flowing through the semiconductor device by the main control circuit based on the current detection value obtained by the current detection resistor. The signal is supplied to the semiconductor device located on the intake side of the cooling air in the order along the flow direction of the cooling air of the semiconductor device fixed to the heat dissipation board, and the current flowing on the exhaust side of the cooling air is located on the exhaust side of the cooling air. An electric power semiconductor device, further comprising an auxiliary control circuit for setting the current to be larger than the current flowing through the semiconductor device. 3. The main control circuit according to claim 1, wherein the auxiliary control circuit is configured to divide a current detection value by a current detection resistor flowing through the semiconductor device into a first voltage-dividing circuit. A second voltage dividing circuit for dividing a value to be input to the circuit, and a voltage dividing value by the first and second voltage dividing circuits,
3. The power semiconductor device according to claim 2, further comprising: an operational amplifier that uses a value corresponding to the difference as a current control signal for the semiconductor device.