JP2011133420A - Temperature detection method for switching element - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a temperature detection method for switching element that detects the switching element temperature in a simple manner, at low cost and without fail, in the temperature detection of switching elements constituting a bridge circuit which has a plurality of heat generating spots. <P>SOLUTION: In the method for detecting each temperature of the switching elements 41a-43b, constituting the bridge circuit by a diode element 402 for temperature detection constituted on the same chip as each of the switching elements 41a-43b, the switching elements 41a-43b are arranged on the same radiator 40, and each diode element 402 for temperature detection of switching elements 41a, 42a, 43a selected from the switching elements 41a-43b is connected in series and detect the respective temperature of the switching elements 41a, 42a, 43a. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a temperature detection method for a switch element that controls energization of a multiphase motor, and more particularly to a temperature detection method for a semiconductor switch element that forms a bridge circuit having a plurality of heat generation points.

  In general, a switch element that is mounted on a vehicle and forms a bridge circuit that controls energization of a multiphase motor is often configured by combining a large number of individual switch elements. In this case, a large number of switch elements are configured. It is required to realize overheat protection of the switch element by reliably detecting the temperature of all of these at low cost.

  By the way, as a temperature detection method of a semiconductor switch, a diode element for temperature detection is configured on the same chip as a power MOS (field effect transistor), and detection is performed using the negative temperature-voltage characteristic of the diode element. There is known a technique in which a low-pass filter for removing external noise is configured on the same chip. (For example, see Patent Document 1)

  In addition, as temperature detection in a device having a plurality of heat generation points, a technique is known in which temperature detection is performed by connecting each thermistor in parallel using a thermistor whose resistance value changes according to temperature. (For example, see Patent Document 2)

Japanese Patent No. 3509623 Japanese Patent No. 3975809

  However, in Patent Document 1, a temperature detecting diode element is configured on the same chip as the power MOS that is a switching element, and the temperature characteristics of the forward voltage between the anode and the cathode of the diode element are used to determine the switching element. Although a technique for performing temperature detection is disclosed, a temperature detection method for an object to be detected having a plurality of heat generation points is not disclosed.

  In addition, Patent Document 2 discloses a temperature detection method for an object to be detected having a plurality of heat generation points. However, the technique disclosed in Patent Document 2 is temperature detection by a thermistor, and more Since a thermistor installed for detecting heat generation at a location is connected in parallel and detected by a combined resistor, the method of detecting the semiconductor chip temperature has a problem of low detection accuracy.

  The present invention has been made in order to solve the above-described problem. In the temperature detection of the switch element constituting the bridge circuit having a plurality of heat generation points, the temperature of the switch element for detecting the switch element temperature simply, inexpensively and reliably. A detection method is provided.

The switch element temperature detection method according to the present invention is a switch element for detecting temperatures of a plurality of switch elements constituting a bridge circuit by a temperature detection diode element configured on the same chip as each of the plurality of switch elements. The plurality of switch elements are arranged on the same heat radiator, and the temperature detecting diode elements of the switch elements selected from the plurality of switch elements are connected in series, and the temperature of the switch elements is set. it is intended to be detected.

  According to the temperature detection method of the switch element according to the present invention, the plurality of switch elements are arranged on the same heat radiator, the temperature detection diode elements of the switch elements selected from the plurality of switch elements are connected in series, Since the temperature of the switch element is detected, it is possible to detect the temperature of the switch element simply, inexpensively and reliably in the temperature detection of the switch element constituting the bridge circuit having a plurality of heat generation points.

FIG. 3 is a circuit block diagram illustrating a temperature detection method for a switch element according to Embodiment 1 of the present invention. It is a circuit block diagram which shows the structure of a switch element single-piece | unit. It is a chart which shows the characteristic of the temperature of a temperature detection diode, and a voltage. It is a figure which shows the layout of each switch element shown in FIG. It is a table | surface which shows the temperature state of a switch element, and the voltage state of a detection terminal.

  Preferred embodiments of a temperature detection method for a switch element according to the present invention will be described below with reference to the accompanying drawings. It should be noted that the present invention is not limited to this embodiment, and includes various design changes.

Embodiment 1 FIG.
FIG. 1 is a circuit block diagram illustrating a temperature detection method for a switch element according to Embodiment 1 of the present invention. In FIG. 1, a motor (here, a three-phase motor) 1 is connected to a power source 3 such as a battery via an electronic control device 2 that controls the motor 1.

  The electronic control unit 2 includes a power block 4 including semiconductor switch elements 41a, 41b, 42a, 42b, 43a, and 43b that constitute a bridge circuit that energizes each phase of the motor 1, and a radiator that will be described later, and a switch element 41a. The control block 5 which controls the energization timing of -43b is provided.

  The control block 5 includes a constant current circuit 51 that supplies a constant current to a temperature detection diode, which will be described later, a temperature detection diode voltage detection circuit 52 that detects a voltage supplied by the constant current circuit 51, and a voltage of the temperature detection diode voltage detection circuit 52. It includes a control device 53 composed of a microcomputer that controls energization of the motor 1 based on information and other various information (not shown), a pre-driver circuit 54 that drives the switch elements 41a to 43b, and a temperature sensor 55 composed of a thermistor. Yes.

  FIG. 2 is a circuit block diagram showing the configuration of the switch element 41a, and the other switch elements 41b, 42a, 42b, 43a, 43b are configured in the same manner. The switch element 41 a includes a switch element unit 401 and a temperature detection diode 402 configured on the same chip as the switch element unit 401. In FIG. 2, the temperature detection diode 402 is illustrated as a three-stage diode configuration, but the number of stages may be changed as appropriate depending on applications such as detectability.

  Next, output characteristics of the temperature detection diode 402 will be described. FIG. 3 is a chart showing the output characteristics of the temperature detecting diode 402 described with reference to FIG. 2, in which the horizontal axis represents temperature and the vertical axis represents voltage. The chart shows three characteristic lines for each of the two systems of Group A and Group B, but the temperature detection diode 402 is indicated by lines B, B1, and B2 located on the lower side of FIG. ing. Since the temperature detecting diode 402 is composed of three stages of diodes, voltage characteristics corresponding to three diodes between the terminals indicated by B in FIG. 2 are output. The B line indicates the median value, the B1 line indicates the upper limit value, and the B2 line indicates the lower limit value.

  Further, the A, A1, and A2 lines located on the upper side of FIG. 3 are the total voltage characteristics of three temperature detection diodes 402 connected in series, and the B line and B1 at one detection terminal indicated by A in FIG. Line A and line B2 are each three times the output, line A indicates the median value, line A1 indicates the upper limit value, and line A2 indicates the lower limit value. The temperature detection is performed by detecting the total voltage of three temperature detection diodes 402 connected in series, that is, the voltage of the group A by the control device 53 including a microcomputer via the temperature detection diode voltage detection circuit 52 in the control block 5. .

  In order to detect the temperature of the switch elements 41a to 43b, it is necessary to reliably detect an abnormal temperature of 150 ° C. or higher and protect it from overheating. However, in consideration of variations in the temperature detection diode 402, FIG. It can be seen that even when the detection voltage varies between the A1 line and the A2 line by setting the voltage to 3.45 V, it can be reliably detected between 150 ° C. and 200 ° C.

  FIG. 4 is a diagram showing a layout state of the switch elements 41a to 43b described with reference to FIG. Here, among the switch elements 41a to 43b, the temperature detection diodes 402 in FIG. 2 are connected in series so that only the switch elements 41a, 42a, and 43a arranged at spaced positions are detected. This connection state is shown in FIG.

  According to this connection method, the temperature is not directly detected for the switch elements 41b, 42b, and 43b. Is reflected and is detected indirectly.

  As a switch element to be temperature-detected, an element having a high probability of failure or an element having priority on detection sensitivity is selected. In the present embodiment, among the six switch elements 41a to 43b constituting the bridge circuit for energizing the three-phase motor 1, 41a, 42a and 43a corresponding to the upper arm of each phase are selected as targets for direct monitoring. However, this gives priority to the detection and protection of ground faults at the output terminals.

FIG. 5 is a table showing the temperature state of the switch element and the voltage state of the detection terminal, and shows the detectability when the element temperature is different between the switch elements 41a, 42a and 43a that perform temperature detection. The case where the temperature of each of the elements 41a, 42a and 43a varies between 125 ° C. and 200 ° C. with a temperature difference within 50 ° C. is verified, but the overheat determination voltage <3.45V in FIG. If so, it is shown that detection is possible reliably under the conditions of No. 4 or lower in FIG. 5 (all elements are 150 ° C. or any element is 200 ° C.).

  In this embodiment, as described with reference to FIG. 3, the characteristics of the temperature detection diode 402 are as follows: 0 ° C. = 2.1 V (0.7 V × 3 stages), temperature coefficient = −6 mV / ° C. (− However, depending on the configuration method and manufacturing conditions of the temperature detection diode 402, the initial variation and the temperature coefficient may be slightly deviated from the ideal values. It is necessary to set the overheat determination voltage according to the characteristics.

  In addition, as a calibration method when the characteristics of the temperature detection diode 402 are deviated from the ideal values, a means for correcting by a separate temperature sensor 55 as shown in FIG. 1 is also effective.

As described above, according to the temperature detection method of the switch element according to the first embodiment, the three-phase motor is provided by the bridge circuit having the plurality of switch elements 41a to 43b in which the temperature detection diode 402 is configured on the same chip. 1, a plurality of switch elements 41 a to 43 b are arranged on the same heat radiator 40, and a temperature detecting diode element 402 of the switch elements 41 a, 42 a, 43 a selected from the plurality of switch elements 41 a to 43 b is provided. By adopting a method of detecting the total voltage of the diodes 402 connected in series and energized by the constant current circuit 51, the abnormal temperature of the switch elements 41a to 43b can be detected simply and inexpensively.

DESCRIPTION OF SYMBOLS 1 Motor 2 Electronic controller 3 Power supply 4 Power block 40 Radiator 41a, 41b, 42a, 42b, 43a, 43b Switch element 401 Switch element part 402 Temperature detection diode 5 Control block 51 Constant current circuit 52 Temperature detection diode voltage detection circuit 53 Control device 54 Pre-driver circuit 55 Temperature sensor

Claims (2)

A temperature detection method for a switch element, wherein the temperature of the switch element of a bridge circuit configured by a plurality of switch elements is detected by a temperature detection diode element configured on the same chip as each of the plurality of switch elements. ,
A temperature detection method for a switch element, wherein the plurality of switch elements are arranged on the same heat radiation plate, and the temperature detection diode elements of the switch elements selected from the plurality of switch elements are connected in series to detect the temperature of the switch elements. .   2. The temperature detecting method for a switch element according to claim 1, wherein a constant current is applied to the temperature detecting diode elements connected in series, and the temperature is detected by a total voltage of the temperature detecting diode elements.

Images