JP2013042604A - Temperature detection circuit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a temperature detection circuit using a plurality of thermal reed switches mounted on a heat sink of a power converter which can specify operating thermal reed switches in a minimum configuration.SOLUTION: A resistor is connected in parallel with a thermal reed switch configured to open at a set temperature or greater, such units are connected in series by the number of measuring points, and each resistor is provided with a different resistance value. Opening thermal reed switches change the impedance of the series, so that a resistance value or a divided voltage value can be determined to specify the operating thermal reed switches. An operating region of the plurality of thermal reed switches can be determined in a simple circuit configuration.

Description

  The present invention is applied to, for example, a temperature detection circuit that detects the temperature of a heat sink on which a semiconductor element is mounted in a power converter.

  In a power converter, a semiconductor element such as a transistor is mounted on a heat sink, and a thermal reed relay is installed near the semiconductor element of the heat sink to detect a temperature rise due to heat generation of the semiconductor element and perform a protection operation such as operation stop. Is done.

  FIG. 3 is a diagram in which a semiconductor element is mounted on a heat sink and a thermal reed switch is disposed in the vicinity thereof. In FIG. 3, module semiconductor elements 81, 82, and 83 are mounted on a heat sink 7, and thermal reed switches 11, 12, and 13 are disposed in the vicinity of each module semiconductor element. Cooling air is sent to the heat sink 7 by the fan motor 91, and the air flows as shown by arrows. The thermal reed switch is arranged on the leeward side of the cooling air in order to detect the temperature rise of the heat sink, which has risen due to the heat generated by the module semiconductor element.

  FIG. 4 is an example of a detection circuit. The thermal reed switch 11, 12, 13 uses a type that opens the contact when the temperature rises above the set temperature.If any of the thermal reed switches 11, 12, 13 is activated, It can be determined that the voltage of the power source 5 is not supplied to the detection unit 6 and the thermal reed switch is operated due to the temperature rise.

JP-A-5-316746 (FIG. 1)

Since the thermal reed switch performs the short circuit and open operation of the contacts at the set temperature, it is impossible to determine which part of the thermal reed switch has been operated in the case of the detection circuit as shown in FIG. If we do not know where the temperature rise occurred, we will not be able to obtain indicators for inspection and repair.
FIG. 5 shows a detection circuit for specifying the operated thermal reed switch. Each of the three thermal reed switches is provided with detectors 61, 62, 63 so that the operation can be individually detected. In general, the digital interface of the power converter control unit is used as the detection circuit. However, when the thermal reed switch is individually connected as shown in FIG. The problem is that the interface of the control unit has increased.

  The present invention has been made to cope with the above-described situation, and the problem is that in a temperature detection circuit using a plurality of thermal reed switches, the portion of the thermal reed switch that operates while suppressing an increase in the control unit interface. It is an object of the present invention to provide a detection circuit capable of specifying the above.

  According to invention of Claim 1, in the temperature detection circuit of the power converter which has a heat sink, the parallel body which consists of the thermal reed switch opened | released more than preset temperature, and the resistor connected in parallel with this thermal reed switch Forming a series body in which a plurality of the parallel bodies are connected in series, connecting the series body in series with a power supply circuit, and determining a resistance value connected in series with the series body on the opposite side of the power supply circuit It has a circuit, and the resistors of the parallel body have different resistance values.

  According to the invention of claim 2, instead of the resistance value determination circuit connected in series according to claim 1, a new resistor is connected in series between the series body and the power supply circuit, and the series body A voltage discriminating circuit is connected to a connection point between the resistor and the new resistor.

  That is, in the temperature detection circuit according to claim 1, a thermal reed switch that opens at a set temperature or higher, a resistor connected in parallel with the thermal reed switch, and a parallel body of the thermal reed switch and a resistor. The resistors connected in parallel to the thermal reed switch are configured to have different resistance values.

  In the temperature detection circuit according to claim 2, a thermal reed switch that is opened at a set temperature or higher, a resistor connected in parallel with the thermal reed switch, and a parallel body of the thermal reed switch and the resistor. The resistance value of the resistor connected in parallel to the thermal reed switch is configured to be different in each series body, and the resistor connected in series to the series body of the thermal reed switch and the DC power supply series body Then, a voltage discrimination circuit is connected to a connection point between the series body of the thermal reed switch and the series body of the resistor and the DC power source.

  According to the temperature detection circuit of the present invention, it is possible to determine the operation part of a plurality of used thermal reed switches with a simple circuit configuration.

It is a temperature detection circuit diagram related to the present invention. Example 1 It is a temperature detection circuit diagram related to the present invention. (Example 2) It is an example of a temperature detection circuit configuration of a semiconductor device using a plurality of thermal reed switches according to the present invention. This is an example of a temperature detection circuit using a plurality of conventional thermal reed switches. This is an example of a temperature detection circuit using a plurality of conventional thermal reed switches.

  Embodiments of the present invention will be described below with reference to FIGS.

  FIG. 1 shows a temperature detection circuit according to the first embodiment of the present invention.

  In the temperature detection circuit according to the first embodiment of the present invention, the thermal reed switches 11, 12, and 13 that are opened at a set temperature or more and the resistors 21, 22, and 23 having different resistance values are connected to each other. The resistance value determination circuit 3 and the power source 5 are connected.

Next, the operation of the embodiment of the present invention will be described.
Table 1 shows an example of resistance values of resistors connected in parallel with the three thermal reed switches 11, 12, and 13, respectively.
Since the thermal reed switch is in a conductive state below the set temperature, the resistance value of the series body is 0 unless all the thermal reed switches are operating. This state is state 1 in Table 1.

Next, for example, if it is detected that the thermal reed switch 13 has reached the set temperature or more and the circuit is opened, the resistance value of the resistors connected in parallel appears. This state is the state 2 in Table 1, and the other thermal reed switches 11 and 12 are in a conductive state, so the total resistance value of the series body is 1 kΩ.
The three thermal reed switches have eight states as shown in Table 1. However, by changing the resistance value of the parallel resistance of the thermal reed switch, the total resistance values are all different in the eight combinations. Therefore, it is possible to specify which thermal reed switch is operating by detecting this resistance value.

  In FIG. 1, a power source 5 and a resistance value determination circuit 3 are connected to a series body of a thermal reed switch and a resistor. For example, the resistance value discriminating circuit 3 is supplied from the power source 5 and is a circuit that discriminates the current value that has passed through the series body of the thermal reed switch and the resistor, whereby a desired operation can be obtained.

Further, as the operation of the power conversion device after the temperature detection by the temperature detection circuit is operated, the device operation is generally stopped and the protection information at that time is recorded.
Therefore, since it is important to record the first part that exceeds the set temperature, even if there are a large number of thermal reed switches in the temperature detection circuit according to the present invention, all the parallel resistors have different resistance values. If this is the case, the parallel resistance value of the thermal reed switch that has been operated by first detecting a temperature rise (opening) appears, so that it is possible to identify that part.

  FIG. 2 shows a temperature detection circuit according to the second embodiment of the present invention.

  In FIG. 2, three thermal reed switches 11, 12, 13 and resistors 21, 22, 23 connected to each of them, a series of thermal reed switches, a power source 5, a resistor 25, and a thermal reed switch are connected in series. The voltage discrimination circuit 4 is connected to the connection point of the resistor 25.

In FIG. 2, the operation of the serial body portion of the thermal reed switch is the same as that of the first embodiment described in FIG. The input voltage of the voltage discriminating circuit 4 is a value obtained by dividing the voltage of the power source 5 by the resistance value of the resistor 25 and the resistance value of the series body of the thermal reed switch.
Table 2 shows the voltage discrimination circuit voltage under the conditions shown in Table 1, in which the resistance of the series resistor 25 and the voltage of the power source 5 are specifically set. In each state, the resistance value of the thermal reed switch series body is different, so of course the voltage discrimination circuit voltage divided by each resistance also has a different value. Can be specified.

  As the voltage discriminating circuit, if one analog interface of the power converter control unit is used and digital-to-analog conversion is performed and voltage discrimination is performed on software, an increase in the input interface of the power converter control unit is prevented. Even when a large number of thermal reed switches are used, the operated thermal reed switch part can be specified by performing detailed voltage discrimination.

  The application to the power conversion device semiconductor element portion to which the temperature detection circuit using a plurality of thermal reed switches is applied is as described above. Similarly, the industrial equipment using the temperature detection circuit using a plurality of thermal reed switches is used. It is clear that it contributes to circuit simplification.

11, 12, 13 ... Thermal reed switch 21, 22, 23, 25 ... Resistor 3 ... Resistance value discriminating circuit 4 ... Voltage discrimination circuit 5 ... Power supply 6, 61, 62, 63 ... Detection (Digital input circuit)
7 ... Heatsink 81, 82, 83 ... Transistor module 91 ... Fan motor

Claims (2)

In a temperature detection circuit of a power converter having a heat sink, the power converter has a parallel body composed of a thermal reed switch that opens at a set temperature or higher and a resistor connected in parallel with the thermal reed switch. Forming a series body connected in series, connecting the series body in series with a power supply circuit, and having a resistance value determining circuit connected in series with the series body on the opposite side of the power supply circuit, A power converter temperature detection circuit, wherein the resistors have different resistance values.
A new resistor is connected in series between the series body and the power supply circuit instead of the resistance value determination circuit connected in series according to claim 1, and the connection between the series body and the new resistor A power converter temperature detection circuit, wherein a voltage discrimination circuit is connected to the point.

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