JP2010081713A - Calculator of temperature of bonding portion of semiconductor element in voltage type power conversion apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a calculator of a temperature of a bonding portion of a semiconductor element, capable of efficiently calculating the temperature of a bonding portion of a semiconductor element. <P>SOLUTION: The calculator includes: an input means 10 capable of inputting an output voltage command of a semiconductor element of the power converter in which the temperature of the bonding portion of the semiconductor element should be calculated in the voltage type power conversion apparatus, and an output current of the semiconductor element of the calculation target; a memory table (loss-voltage-current three-dimensional table) 8 for indicating the previously stored relation among the loss of the semiconductor element, output voltage command and output current; and an operation means (CPU) capable of reading and outputting the loss of the semiconductor element at a corresponding certain time stored in the memory table 8 on the basis of the output voltage command and the output current at a certain time inputted by the input means 10. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a semiconductor element junction temperature calculation device for calculating the temperature of a semiconductor element junction in a power converter including a voltage type self-excited power converter that converts DC power into AC power and a separately excited power converter. .

  For example, there is an upper limit on the semiconductor element junction temperature used in the voltage type self-excited power converter. For this reason, in designing the power converter, it is very important in design to calculate the semiconductor element junction temperature during operation.

  FIG. 6 shows a main circuit of the voltage type self-excited power converter, which is mainly composed of a DC power source 2, a power converter 3 and a load 4. The power converter 3 includes semiconductor elements 31a to 31f made of IGBT, GTO or the like that can be turned on / off by an ignition signal, and diodes 32a to 32f connected in antiparallel to the semiconductor elements 31a to 31f, respectively. . The ignition signals of the semiconductor elements 31a to 31f are given from the control device (PWM unit) 1.

  The control device 1 has various PWM (Pulse Width Modulation) methods, but here, a general triangular wave comparison method is shown. Specifically, the voltage commands Vrefu14a, Vrefv14b, and Vrefw14c generated by the voltage command generation unit 11 and the triangular wave modulation signal from the triangular wave modulation signal generation unit 12 are compared by the comparators 13a to 13c, so that the semiconductor element 31a. ˜31f is turned on / off.

  Next, an example of a specific ignition method for the U-phase semiconductor element 31a in FIG. 6 will be described with reference to FIG.

First, FIG. 7A shows the voltage command Vrefu 14 a generated by the voltage command generation means 11 and the triangular wave modulation signal generation means 12. FIG. 7B shows an ignition signal of the semiconductor element 31a obtained by comparison by the comparator 13a. FIG. 7C shows the U-phase output current 33a. FIG. 7D shows the current of the semiconductor element 31a determined by the ignition signal of the semiconductor element 31a and the U-phase output current 33a.

  As described in Non-Patent Document 1, the loss of a semiconductor element is a loss that occurs when the semiconductor element is turned on (turn-on loss), a loss that occurs in an on state (steady-on loss), and a time that is turned off. It consists of the loss that occurs (turn-off loss). The steady on-loss is due to the conduction resistance inherent in the semiconductor element and is mainly determined by the energization current. The turn-on loss and turn-off loss are mainly determined by the circuit configuration and circuit constants, the on-off current that is turned on or off, the DC voltage, etc., but the circuit configuration, circuit constants and DC voltage are device-specific. The turn-on loss and turn-off loss in the device are determined by the energization current at the moment of turning on or off. FIG. 7E shows the state of loss generated in the semiconductor element G31a.

  Next, a temperature calculation method of the semiconductor element will be described. In general, for cooling a semiconductor element, the semiconductor element is brought into close contact with the cooling fin, and heat generated in the semiconductor element is transmitted to the cooling fin. Air cooling or water cooling is often used for cooling the cooling fins.

  FIG. 8 is a simple thermal model 5 in the semiconductor element / cooling fin described in Non-Patent Document 2. The thermal model 5 includes a thermal resistance RJ52a [K / W] of a semiconductor element, a thermal capacity CJ52b [J / K], a thermal resistance RF53a [K / W] of a cooling fin, a thermal capacity CF53b [J / K], and a loss source 51. Become. By analyzing the thermal model 5 with respect to the ambient temperature To [° C.] 54, the semiconductor element junction temperature TJ [° C.] 55 is calculated. Since there is an upper limit temperature that can be used for a semiconductor element, the semiconductor element junction temperature TJ [° C.] 55 must be designed so as not to exceed a predetermined temperature.

  In consideration of this, for example, when attention is paid to the semiconductor element 31a in FIG. 6, the semiconductor device junction temperature calculation apparatus is as shown in FIG. That is, as shown in FIG. 6, the output voltage command 14a is given to the PWM unit 1 to obtain an ignition signal of the semiconductor element 31a. From this, the energization current of the semiconductor element 31a is calculated and its loss is calculated. The state of the loss is as shown in FIG.

  Since the loss of the semiconductor element depends on the current flowing through the semiconductor element at that time as described above, it is necessary to grasp the characteristics in advance, for example, as shown in FIG. . More specifically, as shown in FIG. 10A, a loss that occurs when the semiconductor element is on (steady ON loss), as shown in FIG. 10B, a loss that occurs when the semiconductor element turns on (turn-on) Loss), which is a loss (turn-off loss) generated when the semiconductor element is turned off as shown in FIG.

  A semiconductor element junction temperature (TJ) 55 is obtained by giving the semiconductor loss thus obtained as the loss source 51 of the thermal model 5.

  The purpose is to obtain the maximum value of the semiconductor element junction temperature, and the period of the semiconductor element generation loss determined by the operating frequency of the apparatus is determined by the thermal resistances 52a and 53a and the thermal capacities 52b and 53b of the thermal model 5. If it is sufficiently shorter than the thermal time constant, or if the operating frequency of the apparatus is a direct current, it may be calculated with a simple model as shown in FIG. That is, the average loss during one operation cycle of the loss calculator 6 is obtained, and the semiconductor element junction temperature is obtained by multiplying the average loss by the thermal resistance of the thermal model 5 (the sum of 52a and 53a). In a device used at a commercial frequency or a device with a DC output, such a simple semiconductor element junction temperature calculation method is generally employed.

  Patent Document 1 aims to measure the temperature of the joint during operation by using one measurement terminal. This is done by connecting two or more diode auto elements in series with one or more diode elements connected in parallel in opposite directions, one end connected to the power supply terminal and the other end connected to a dedicated terminal for measuring the junction temperature. And a junction temperature measuring device for obtaining a difference voltage between positive and negative forward voltage drops.

In Patent Document 2, a defective semiconductor device can be surely found. A first constant current source that applies a predetermined current to a transistor chip and a sufficiently large current to the chip are disclosed. 2 constant current sources, the second constant current source is operated periodically, the PN junction voltage of the chip is periodically sampled and held, and this is displayed on an oscilloscope. .
Introduction to Power Electronics (Ohm, 4th revised edition, page 9) Thyristor device (Maruzen, page 81, Figure 3.1) JP 05-299487 A JP 08-111446 A

  The conventional semiconductor element junction temperature calculation method described above can obtain a sufficiently accurate value by a simple calculation method as shown in FIG. 11 for a device with a relatively high operating frequency or a device with a DC output. It was.

  However, when the operating frequency of the power conversion device is low and the period of the generated loss of the semiconductor element is not shorter than the thermal time constant of the cooling system obtained from the thermal resistances 52a and 53a and the thermal capacities 52b and 53b of the thermal model 5, It is necessary to calculate the semiconductor element junction temperature with an apparatus as shown in FIG. Since the frequency of the triangular wave modulation signal reaches several kHz, it is necessary to perform the calculation step in about several μs when PWM is simulated.

  On the other hand, the thermal time constant of the cooling system can range from several seconds to several hundred seconds. For this reason, enormous time will be required if the calculation is performed by the apparatus as shown in FIG. If even one of the output current, output voltage, operating power factor, and operating frequency of the power converter changes, it will be necessary to repeat this calculation under different calculation conditions, greatly increasing the number of calculation cases. However, there was a problem of requiring calculation time.

  The present invention has been made in order to solve the above-described problems, and an object of the present invention is to provide a semiconductor element junction temperature calculation apparatus capable of efficiently calculating a semiconductor element junction temperature.

In order to achieve the above object, the invention corresponding to claim 1 converts a DC voltage from a DC voltage source into an AC voltage, and is constituted by a plurality of semiconductor elements that are turned on and off by an output voltage command given to a gate. In the voltage type power conversion device comprising: the power converter, and a control device that outputs an output voltage command to be applied to the gate of the semiconductor element.
An input means capable of inputting an output voltage command and an output current of the power converter to which the temperature of the junction is to be calculated;
A memory table indicating the relationship between the loss of the semiconductor element stored in advance, the output voltage command, and the output current;
Arithmetic means capable of reading out and outputting the loss of the semiconductor element at the corresponding time stored in the memory table based on the output voltage command and output current of the power converter at the certain time input by the input means;
A device for calculating a junction temperature of a semiconductor element in a voltage type power conversion device.

  ADVANTAGE OF THE INVENTION According to this invention, the calculation apparatus of the semiconductor element junction temperature which can implement efficiently calculation of a semiconductor element junction temperature can be provided.

(First embodiment)
FIG. 1 is a block diagram for explaining a semiconductor device junction temperature calculation apparatus according to a first embodiment of the present invention. In the present invention, for example, a voltage type self-excited power converter as shown in FIG. 9 has the following configuration.

That is, an input means 10 capable of inputting an output voltage command and an output current of the power converter to which the temperature of the semiconductor element junction is to be calculated;
A memory table (loss-voltage-current three-dimensional table) 8 showing a relationship of loss-output voltage command-output current of the semiconductor element stored in advance, and output voltage command of the semiconductor element at a certain time inputted by the input means And a calculation means (not shown) capable of reading out and outputting the loss of the semiconductor element at a corresponding time stored in the memory table 8 based on the output current.

  The semiconductor element junction temperature calculation apparatus described above is configured by hardware including a computer input / output means, a calculation means (CPU), and a memory, or calculates the semiconductor element junction temperature in the computer memory. It is also possible to store a program for performing and execute the program.

  As described above, the voltage type power conversion device converts a DC voltage from the DC voltage source 2 into an AC voltage as shown in FIG. 6, and has a plurality of on / off operations according to an output voltage command given to the gate. And a control device 1 that outputs an output voltage command to be applied to the gate of the semiconductor element.

  FIG. 1 shows the semiconductor element 31a in FIG.

The output voltage command 14a and the output current 33a are given to the loss-one-voltage-one-current three-dimensional table 8 to obtain the semiconductor element loss generated in the semiconductor element 31a. The rest is the same as the conventional example shown in FIG.

  Here, the memory table 8 will be described. This memory table 8 is, for example, a memory table as shown in FIG. In FIG. 2, black dots indicate data constituting the memory table. Each piece of data corresponds to average loss data when a DC operation is performed at an output voltage / output current corresponding to a black spot. In order to construct the loss-voltage-current-three-dimensional table 8, it is necessary to calculate a number of losses during DC operation. The density of the table data may be determined according to the necessity of accuracy required for the semiconductor element junction temperature calculation. Each loss value in the table data can be easily determined by calculating the turn-on loss / turn-off loss with the current corresponding to the data and multiplying the number of switching times per second, and the current corresponding to the data. If the steady on loss is obtained and the on period is multiplied by the voltage corresponding to the data, the steady loss can be easily obtained. Therefore, the operation of constructing the data of the memory table 8 can be performed relatively easily. What is necessary is just to interpolate from table data about the loss value between table data.

  Next, an example of the locus of voltage / current when the output voltage command 14a and the output current 33a are given to the loss-one-voltage-one-current three-dimensional table 8 will be described. FIG. 3 is a locus of voltage and current when the apparatus is operated at a power factor of 1,0. The loss value on this locus becomes the output of the loss-voltage-current-three-dimensional table 8. If the operating frequency is high, the trajectory moves quickly, and if the operating frequency is low, the trajectory moves slowly.

  FIG. 4 is a locus of voltage and current when the apparatus is operated at a power factor of 0 (the current phase is 90 ° behind the voltage). The loss value on this locus becomes the output of the loss-voltage-current-three-dimensional table 8. If the operating frequency is high, the trajectory moves quickly, and if the operating frequency is low, the trajectory moves slowly.

  In the first embodiment of the present invention, as described above, by inputting the output voltage command 14a and the output current 33a in the input means 10, the loss generated in the semiconductor element can be easily obtained from the memory table 8 prepared in advance. Can do. Thereby, for example, if the operating frequency is 5 Hz (cycle 200 ms), the process of obtaining the loss through the loss-one-voltage-one-current three-dimensional table 8 is sufficient in the calculation step of several ms, and the semiconductor element junction portion is compared with the conventional case. The temperature can be calculated efficiently.

(Second Embodiment)
FIG. 5 is a block diagram for explaining a semiconductor device junction temperature calculation apparatus according to the second embodiment of the present invention. The protection means, for example, the protection circuit 9 is provided with a comparator 92, and performs the protection operation when the semiconductor element junction temperature of the above-described embodiment exceeds the protection set value 91. The configuration of the apparatus for calculating the semiconductor element junction temperature is the same as in the first embodiment.

  Next, the operation will be described. The semiconductor element temperature calculation method shown in the first embodiment is mounted on a protection circuit of a power converter. Therefore, the semiconductor element junction temperature is always calculated during operation of the power converter. Then, when the semiconductor element junction temperature obtained in this way exceeds the protection set value 91, a protection stop signal is output and an operation protection operation is performed. Since the semiconductor element junction temperature is always estimated and protected by this, there is an effect that unnecessary protection and avoidance of insufficient protection can be avoided.

BRIEF DESCRIPTION OF THE DRAWINGS Schematic block diagram for demonstrating 1st Embodiment of the calculation apparatus of the semiconductor element junction temperature of this invention. The figure for demonstrating the memory table of FIG. The figure for demonstrating the locus | trajectory of the voltage and electric current in the case of drive | operating by the power factor 1.0 in the voltage type self-excitation power converter of FIG. The figure for demonstrating the locus | trajectory of a voltage and an electric current at the time of driving | operating by the power factor 0 in the voltage type self-excitation power converter of FIG. The block diagram for demonstrating 2nd Embodiment of the calculation apparatus of the semiconductor element junction temperature of this invention. The main circuit block diagram of the voltage type self-excited power converter explaining the conventional and embodiment of this invention. The figure for demonstrating the ignition method of the U-phase semiconductor element 31a of FIG. The figure for demonstrating the simple thermal model in the semiconductor element and cooling fin shown by the nonpatent literature 2. FIG. FIG. 7 is a diagram for explaining a method for calculating a junction temperature in the U-phase semiconductor element 31 a of FIG. 6. The figure for demonstrating the loss calculation method in the conventional semiconductor element of FIG. The block diagram for demonstrating the subject of the loss calculation method in the conventional semiconductor element.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Control apparatus, 2 ... DC power supply, 3 ... Power converter, 4 ... Load, 5 ... Thermal model, 6 ... Loss calculation apparatus, 8 ... Memory table, 9 ... Protection circuit, 10 ... Input means, 11 ... Voltage command Generation means, 12 ... Triangular wave modulation signal generation means, 13a to 13c ... Comparator, 14a ... Output voltage command, 31a-31f ... Semiconductor element, 31a ... Semiconductor element.

Claims (2)

A power converter for converting a DC voltage from a DC voltage source into an AC voltage, which is configured by a plurality of semiconductor elements that are turned on and off by an output voltage command applied to the gate, and an output voltage applied to the gate of the semiconductor element In a voltage type power converter provided with a control device that outputs a command,
An input means capable of inputting an output voltage command and an output current of the power converter to which the temperature of the junction is to be calculated;
A memory table indicating the relationship between the loss of the semiconductor element stored in advance, the output voltage command, and the output current;
Arithmetic means capable of reading out and outputting the loss of the semiconductor element at the corresponding time stored in the memory table based on the output voltage command and output current of the power converter at the certain time input by the input means;
A device for calculating a junction temperature of a semiconductor element in a voltage type power conversion device. A power converter for converting a DC voltage from a DC voltage source into an AC voltage, which is configured by a plurality of semiconductor elements that are turned on and off by an output voltage command applied to the gate, and an output voltage applied to the gate of the semiconductor element In a voltage type power converter provided with a control device that outputs a command,
An input means capable of inputting an output voltage command and an output current of the power converter to which the temperature of the junction is to be calculated;
A memory table indicating the relationship between the loss of the semiconductor element stored in advance, the output voltage command, and the output current;
Arithmetic means capable of reading out and outputting the loss of the semiconductor element at the corresponding time stored in the memory table based on the output voltage command and output current of the power converter at the certain time input by the input means;
Protection means for performing a protection operation of the power converter by a semiconductor element junction temperature obtained from the calculation means;
A device for calculating a junction temperature of a semiconductor element in a voltage type power conversion device in the voltage type power conversion device.

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