JPH02253129A - Temperature detecting circuit for semiconductor element - Google Patents

Abstract

PURPOSE:To surely protect a semiconductor element by calculating the momentary value of the temperature in a junction part in accordance with a preliminarily obtained loss characteristic, the flowing current to the semiconductor element, and the actual value of the voltage between the anode and the cathode. CONSTITUTION:Relations of the turn-on loss to a flowing anode current IA and a voltage VAK between the anode and the cathode, relations of the turn-off loss, and relations of the normal loss are stored in a turn-on loss arithmatic circuit 11, a turn-off loss arithmatic circuit 12, and a normal loss arithmatic circuit 13 respectively in accordance with preliminarily given characteristic data of the semiconductor element. Arithmatic circuits 11, 12, and 13 individually calculate the turn-on loss, the turn-off loss, and the loss during normal operation of the semiconductor element respectively in accordance with characteristic data peculiar to the semiconductor element, the flowing anode current IA, and the voltage VAK between the anode and the cathode, and they are added by an adder 14, and the momentary value of the temperature in the junction part is calculated by a junction part temperature arithmatic circuit 15, and it is detected by a comparator 16 that the temperature in the junction part reaches a maximum value for operation.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a circuit for detecting the junction temperature of a semiconductor switching element constituting a power conversion device.

[Conventional technology]

FIG. 4 is a general main circuit connection diagram of an inverter constructed by combining semiconductor elements.

In this FIG. 4, by using four sets of Kate turn-off silicon (hereinafter abbreviated as GTO silicon) 4 as a semiconductor element and a freewheeling diode 5 connected in anti-parallel, tli phase bridge connection is made. An inverter 3 is formed. By commands from a control device (not shown), the four GTO thyristors 4 are sequentially turned on and off, thereby converting the DC power from the direct type #2 into AC power, which can be supplied to the load 6. It is well known that

The GTO thyristor 4 used here is a self-extinguishing semiconductor element that can conduct or cut off the main current by gate control, and in order to obtain the characteristics specified in the rating, it must be within a specified junction temperature range. It is necessary to use it within. In addition, the GTO thyristor 4, like other semiconductor elements,
A loss occurs when current flows, and a large loss occurs for a short time during the transition between ignition and extinguishment.

Therefore, in order to keep the temperature rise due to these losses within the above-determined junction temperature range, some type of cooling device is required.

FIG. 5 is a schematic diagram of the cooling system of the known GTO Cyrisk.

FIG. 5 shows, as an example, a flat structure often used in large-capacity semiconductor devices. That is, the anode side cooling body 7 is attached to the anode 'electrode A of the GTO thyristor 4.
Further, a cathode side cooling body 8 is directly connected to the cathode electrode K, and by blowing cooling air in the direction of the arrow, the loss generated in the G TO thyristor 4 is absorbed by the cooling body 7.
and 8 into the surrounding atmosphere. 9 is a temperature sensor such as a thermostat.

By the way, in the inverter 3 as shown in FIG.
If the power of the load 6 is constant or the operating method is predetermined, the maximum loss generated by the GTO thyristor 4 is known in advance at the time of device design, so the loss of 1 to 4 The GTO Xyrista 4
It is okay to design the cooling system so that the temperature IW of the unit falls within the allowable range.

However, in a device where an arbitrary load is connected and the operating method changes significantly depending on the load, the current flowing through the GTO thyristor 4 will change significantly, and in this case, the expected maximum loss will be The cooling system must be designed with this in mind, but if the cooling system is designed to be able to handle even the rare occurrence of large losses, the cost will be high and the device will become uneconomical. .

Therefore, in such a case, design a cooling system that corresponds to the load that is normally used, and in the event of an abnormality such as an overload or incorrect operation, the temperature rise of GTO thyristor 4 will become abnormally large, so this should be detected. It is more economical to stop the equipment when

FIG. 6 is a rough view of the joint surface between the cathode electrode and the cathode side cooling body of the GTO SIRISK in the configuration diagram shown in FIG. 5.

As shown in FIG. 6, the cathode side cooling body 8 has a G
A thermostan I/9 is attached together with the TO thyristor 4 to monitor the case temperature of the GTO thyristor 4. That is, when the GTO thyristor 4 becomes overloaded for some reason and the junction temperature of the GTO thyristor 4 rises to a value that cannot withstand normal operation,
Since the case temperature also rises accordingly, the thermostat 9 detects this abnormal rise in case temperature and issues an alarm or attempts to stop the operation of the device.

[Problems to be Solved by the Invention] However, the above-described conventional temperature detection method has several drawbacks as described below.

That is, the first problem is that when using the cooling bodies 7 and 8 as shown in FIG.
There is only a place to remove the fin part of 8, and the distance from the case of GTO thyristor 4 is longer, so accurate GT
Since the temperature of the O-thyristor 4 could not be monitored, reliable protection was difficult. The second problem is GTO Zyristor 4
When a large pulse-like load is applied for a time shorter than the thermal time constant of the cooling body 78 of So, because of the time delay,
Accurate temperature monitoring was not possible, and therefore reliable protection was difficult.

Due to these two problems mentioned above, the GTO thyristor 4 cannot be effectively utilized up to its temperature limit.
This resulted in the device becoming a doll, which had the disadvantage of increasing costs.

Therefore, an object of the present invention is to provide a cooling body for dissipating the generated loss, and to accurately and quickly detect the junction temperature of the semiconductor element to which the semiconductor element belongs, thereby reliably protecting the semiconductor element. It is.

(Means for Solving the Problems) In order to achieve the above object, the temperature detection circuit of the present invention includes a semiconductor element that performs power conversion and a cooling body that dissipates loss generated in this semiconductor element. turn-on loss calculation means for calculating the turn-on loss of the semiconductor element by inputting the loss characteristics of the semiconductor element, the current flowing through the semiconductor element, and the anode-cathode voltage; Input the above loss characteristics, conduction current, and anode-cathode voltage,
a turn-off one-member loss calculation means for calculating the loss at turn-off of the semiconductor element; a steady-state loss calculation means for calculating the steady-state loss of the semiconductor element by inputting the loss characteristics and current flowing; addition means for adding loss, turn-off loss, and steady state loss;
A junction temperature calculation means is provided for calculating the junction temperature of the semiconductor element from the result of this addition operation.

[Effect]

This invention calculates the junction temperature of a semiconductor element based on the loss characteristics of the semiconductor element and the characteristics of the cooling system, which have been determined in advance, as well as the actual values of the conduction current of the semiconductor element and the voltage between the anode and the cathode. By calculating the instantaneous value, the accurate junction temperature can be quickly determined in both steady state and transient state, which provides reliable protection.

[Embodiment] FIG. 1 is a front view showing an embodiment of the present invention.

Does the GTO thyristor 4 as a semiconductor element constituting the in-hark 3 shown in FIG. 4 convert power by on/off operation? There are three types of loss: turn-on loss that occurs when changing from on to on state, steady loss that occurs during steady operation in on state, and turn-off loss that occurs when moving from on to off state.

In FIG. 1, 11 is a turn-on loss calculation circuit that calculates the loss at turn-on of the GTO thyristor 4,
From the characteristic data of the GTO thyristor 4 given in advance, the relationship of turn-on loss to one anode current flowing through it and the anode-cathode voltage VAK is memorized, and the anode current IA and anode of this GTO thyristor 4 are stored. - It has a function to output the turn-on loss corresponding to the cathode voltage ■□.

12 is a turn-off loss calculation circuit that calculates the loss at turn-off of the GTO thyristor 4, and from the characteristic data of the GTO thyristor 4 given in advance, the anode current I flowing through it and the anode-cathode voltage ■AK The relationship between the turn-off loss and the anode current (4) and the anode-cathode voltage (2) of this GTO thyristor 4 is memorized. It has a function to output the turn-off loss corresponding to the

13 is a steady loss calculation circuit that calculates the loss of the GTO thyristor 4 during steady state, and stores the relationship between the steady state JR loss and the anode current I flowing through it from the characteristic data of the GTO thyristor 4 given in advance. Keep it
It has a function of outputting a steady loss corresponding to the anode current IA of this GTO iristor 4.

14 is an adder, which includes a turn-on loss calculation circuit 11;
By adding together the losses calculated by the turn-off loss calculation circuit 12) and the steady state 111 loss calculation circuit 13, the total sum of losses that occur when the GTO zyristor 4 operates on and off is determined.

15 is a junction temperature calculation circuit that calculates the junction temperature of this G"FO zyristor 4 from the generated loss of the G T 04J iristor 4 calculated by the adder 14, and the time equal to the thermal time constant of the cooling system. It is composed of a first-order lag filter having a constant, and its output corresponds to the junction temperature of the GTO thyristor 4.

Reference numeral 16 denotes a comparator for detecting that the junction temperature of the GTO zyristor 4 obtained as the output of the junction temperature calculation circuit 15 described above has reached the maximum operable value. This means that the maximum operable value of the junction temperature of the GTO thyristor 4, which is preset inside this comparator 16, and the actual value of the junction temperature of the GTO thyristor 4 obtained as the output of the junction temperature calculation circuit 15 are determined. In comparison, if the actual temperature value exceeds the above-mentioned set value, the output logic signal is inverted. Therefore, if GTO thyristor 4 is overloaded and comparator 1
When the logic output of No. 6 is inverted, a protection circuit (not shown) immediately stops the operation of the device to prevent damage due to overload.

Figure 2 shows the anode current IA flowing through the GTO Cyrisk.
This is a diagram showing the anode-cathode voltage V□.

Figure 3 is a waveform diagram showing the timing at which GTO Cyrisk generates loss, and Figure 3 (A) shows the anode current ■ of GTO Cyrisk. and the anode-cathode voltage ■. Figure 3 (b) shows the temporal changes in losses incurred by GTO Cyrisk.

In FIG. 3, 1' is the point in time when the GTO thyristor 4 in the off state starts turning on, T2 is the point in time when the turn on is completed, T is the point in time when the GTO thyristor 4 in the on state starts turning off, and T4 is the point in time when the GTO thyristor 4 in the on state starts turning off. This is the point of completion. Therefore, the period from T1 to T2 is the period in which turn-on loss occurs, the period from T2 to T3 is the period in which steady loss occurs, and the period from T:1 to T4 is the period in which turn-off loss occurs.

〔Effect of the invention〕

According to the present invention, the loss that occurs when a semiconductor element turns on, the loss that occurs when it turns off, and the loss that occurs during steady operation are calculated using characteristic data specific to the semiconductor element and current flow. Calculate separately from the anode current value and anode-cathode voltage value,
Since the circuit is configured so that the instantaneous value of the junction temperature of the semiconductor element can be calculated from the sum of these 1fi losses,
When detecting the junction temperature from the time when +1% loss occurs, the detection time delay that existed in the conventional method is eliminated. Therefore, even when a pulsed load is applied for a period shorter than the thermal time constant of the heat sink, the temperature can be immediately and accurately detected, making it possible to lower the rating of the semiconductor device or use a larger heat sink. This has the effect of eliminating waste and downsizing the device.

[Brief explanation of drawings]

Figure 1 is a block diagram showing an embodiment of the present invention, Figure 2 is a block diagram showing an embodiment of the present invention.
The figure shows the anode current flowing through GTO Cyrisk ■4,
Figure 3 is a diagram showing the anode-cathode voltage VAK, Figure 3 is a waveform diagram showing the timing at which GTO Cyrisk generates loss, Figure 4 is a general main circuit connection diagram of an inverter configured by combining semiconductor elements. , FIG. 5 shows the known G,
FIG. 6 is a schematic diagram showing the cooling system of the TO SIRISK. FIG. 6 is a schematic diagram showing the joint surface between the cathode electrode and the cathode-side cooling body of the GTO SIRISK in the configuration diagram shown in FIG. 5. 2... DC power supply, 3... Inverter, 4... GTO Cyrisk as a semiconductor element, 5... Freewheeling diode, 6... Load, 7... Anode side cooling body, 8...
... Cathode side cooling body, 9 ... Thermostat, 11
... Turn-on loss calculation circuit, 12... Turn-off loss calculation circuit, 13... Steady-state loss calculation circuit, 14...
・Adder, 15...Joint part diagram diagram diagram diagram ~78 \-4

Claims (1)

[Claims] 1) In a device configured with a semiconductor element that performs power conversion and a cooling body that dissipates loss generated in this semiconductor element, the loss characteristics of the semiconductor element and the Turn-on loss calculation means inputs the flowing current and the anode-cathode voltage and calculates the turn-on loss of the semiconductor element; hand,
a turn-off loss calculation means for calculating the turn-off loss of the semiconductor element; a steady-state loss calculation means for calculating the steady-state loss of the semiconductor element by inputting the loss characteristics and the conducting current; Temperature detection of a semiconductor element, comprising: an addition means for adding a turn-off loss and a steady state loss; and a junction temperature calculation means for calculating a junction temperature of the semiconductor element from the result of the addition operation. circuit. 2) In the temperature detection circuit according to claim 1, the junction temperature calculation means may be constituted by a first-order lag filter having a time constant equal to a thermal time constant of the semiconductor element and its cooling body. A temperature detection circuit for a semiconductor element characterized by: