JP5861579B2 - Physical quantity detection device - Google Patents

Description

  The present invention includes a detection element that outputs a signal having a correlation with a predetermined physical quantity to be detected, and a modulation unit that outputs the output signal by performing pulse width modulation based on a comparison between the output signal of the detection element and a carrier wave. And a detecting means for detecting the physical quantity to be detected based on the time ratio of the pulse signal output from the modulating means.

  Conventionally, as seen in Patent Document 1 below, a temperature sensing diode that outputs a signal having a negative correlation with the temperature of a predetermined detection target (for example, a semiconductor switching element), and a pulse width modulation of the output signal of the temperature sensing diode Temperature detection comprising first and second differential amplifiers and first and second triangular wave generating circuits, and a CPU for detecting the temperature of the detection target based on the time ratio of the pulse signal output from the differential amplifier The device is known.

  This device will be described in detail. The output signal of the temperature sensitive diode is inputted to the non-inverting input terminals of the first and second differential amplifiers. The first triangular wave signal output from the first triangular wave generating circuit is input to the inverting input terminal of the first differential amplifier, and the second inverting input terminal of the second differential amplifier A second triangular wave signal output from the triangular wave generating circuit is input. Here, the amplitude of the first triangular wave signal is set in association with a predetermined temperature detection range, and the amplitude of the second triangular wave signal is related to the high temperature range in the predetermined temperature detection range. Attached and set. For this reason, the temperature detection width per unit time ratio of the pulse signal output from the second differential amplifier is smaller than the temperature detection width per unit time ratio of the pulse signal output from the first differential amplifier. . That is, the temperature detection accuracy based on the time ratio of the pulse signal output from the second differential amplifier is higher than the temperature detection accuracy based on the time ratio of the pulse signal output from the first differential amplifier.

  In such a configuration, when the temperature of the detection target becomes high, the output source of the signal transmitted to the CPU via the photocoupler is switched from the first differential amplifier to the second differential amplifier. This improves the temperature detection accuracy of the detection target when the temperature of the detection target becomes high.

JP 2011-27625 A

  Here, although the technique described in Patent Document 1 can improve the temperature detection accuracy of the detection target, two triangular wave generation circuits are provided for one detection target. Accordingly, there is a concern that the internal configuration of the temperature detection device is complicated.

  Not only the temperature detection device, but also a detection element that outputs a signal having a correlation with the physical quantity to be detected, and a physical quantity detection that detects the physical quantity based on the time ratio of the pulse width modulated signal of the detection element output signal. If it is a device, the above-mentioned problems can occur as well.

  The present invention has been made to solve the above problems, and an object of the present invention is to provide a new physical quantity detection device capable of increasing the physical quantity detection accuracy with a simple configuration.

In order to solve the above problems, the present invention provides a detection element (SD, SDp, SDq) that outputs a signal (Vf) correlated with a physical quantity (Tf) of a predetermined detection target (Sw, Swp, Swq), Modulation means (18, 30, 18p, 30p, 18q, 30q) that outputs the output signal by pulse width modulation based on the magnitude comparison between the output signal of the detection element and the carrier wave (tc), and output from the modulation means Detection means (40) for detecting the physical quantity of the detection target based on the time ratio (duty) of the detected pulse signal, and the detection target in each of the physical quantity detection ranges (Td1, Td2) of the detection target divided into a plurality of parts The physical ratio and the time ratio are continuously related and the time ratio ranges (Dmin to Dmax, Dmi) corresponding to each of the physical quantity detection ranges divided into a plurality of parts. To Dmax1, Dmin to Dmax2, Dmin1 to Dmax, Dmin2 to Dmax) correcting means (16, 42, 16p) for correcting the output signal of the detection element input to the modulating means so that at least some of them overlap each other , 16q).

  In the above invention, the output signal of the detection element input to the modulation means is corrected by the correction means so that at least a part of the time ratio ranges corresponding to each of the physical quantity detection ranges divided into a plurality overlap each other. For this reason, in each of the physical quantity detection ranges divided into a plurality, the physical quantity detection width per unit time ratio of the pulse signal output from the modulation means can be reduced, and the dynamic range of the physical quantity detected by the detection means can be reduced. Can be enlarged. That is, the detection accuracy of the physical quantity to be detected can be increased.

  Further, in the above invention, a configuration is adopted in which the output signal of the detection element is corrected by the correction means. For this reason, for example, it is a simple configuration to improve the detection accuracy of the physical quantity compared to the configuration in which the physical quantity detection width per unit time ratio of the pulse signal output from the modulation means is reduced by changing the amplitude of the carrier wave Can also be realized.

1 is a system configuration diagram according to a first embodiment. FIG. The figure which shows an example of the pulse width modulation concerning the embodiment. The figure which shows the correction method of the output signal of the temperature sensitive diode concerning the embodiment. The figure which shows the data arrangement | positioning in the flame | frame concerning the embodiment. The flowchart which shows the procedure of the temperature detection process concerning the embodiment. The system block diagram concerning 2nd Embodiment. The figure which shows the correction method of the output signal of the temperature sensitive diode concerning the embodiment. The figure which shows the correction | amendment method of the output signal of the temperature sensitive diode concerning 3rd Embodiment. The figure which shows the correction | amendment method of the output signal of the temperature sensing diode concerning 4th Embodiment. The system block diagram concerning 5th Embodiment. The figure which shows the data arrangement | positioning in the flame | frame concerning the embodiment. The figure which shows the correction | amendment method of the output signal of the temperature sensing diode concerning other embodiment. The figure which shows the correction | amendment method of the output signal of the temperature sensing diode concerning other embodiment. The figure which shows the correction | amendment method of the output signal of the temperature sensing diode concerning other embodiment.

(First embodiment)
Hereinafter, a first embodiment in which a physical quantity detection device according to the present invention is applied to a vehicle (for example, a hybrid vehicle) including a rotating machine as an in-vehicle main machine will be described with reference to the drawings.

  FIG. 1 shows a system configuration according to the present embodiment.

  The illustrated system includes an in-vehicle low voltage system using a vehicle body as a reference potential, and an in-vehicle high voltage system that is electrically insulated from the in-vehicle low voltage system. Here, a power card PC is mounted on the in-vehicle high voltage system. The power card PC is packaged with a power switching element Sw, a free wheel diode FWD, and a temperature sensitive diode SD. Here, the power switching element Sw constitutes an inverter connected to the rotating machine. The rotating machine plays the role of an in-vehicle main machine. Incidentally, an insulated gate bipolar transistor (IGBT) is used as the power switching element Sw in this embodiment. The temperature sensitive diode SD is a detection element that is disposed in the vicinity of the power switching element Sw and detects its temperature.

  The open / close control terminal (gate) of the power switching element Sw is connected to the integrated circuit 10. The integrated circuit 10 is a dedicated semiconductor device that constitutes a drive circuit for the power switching element Sw.

  The integrated circuit 10 further has a function of converting the output signal Vf (voltage drop amount) of the temperature sensitive diode SD into a binary signal. Specifically, the integrated circuit 10 includes a power supply 12, a constant current power supply 14 that is a power supply source of the power supply 12, an inverting amplifier circuit 16, a PWM comparator 18, and the like.

  The output side of the constant current power supply 14 is connected to the anode of the temperature sensitive diode SD, and the cathode of the temperature sensitive diode SD is grounded.

  The anode of the temperature sensitive diode SD is connected to the inverting input terminal side of the inverting amplifier circuit 16 configured to include an operational amplifier 16a, resistors 16b and 16c, and a power source 16d. In the present embodiment, hereinafter, the output signal of the inverting amplifier circuit 16 is represented by “Vα−a × Vf”. Here, “−a” indicates the amplification factor in the inverting amplifier circuit 16, and “Vα” indicates the shift amount of the output signal of the inverting amplifier circuit 16 with respect to the ground potential “0”. This shift amount “Vα” can be adjusted by adjusting the terminal voltage of the power supply 16 d connected to the non-inverting input terminal of the inverting amplifier circuit 16.

  The anode of the temperature sensitive diode SD is further connected to the non-inverting input terminal of the comparator 22. The inverting input terminal of the comparator 22 is connected to the positive side of the power source 24, and the negative side of the power source 24 is grounded.

  The output terminal of the inverting amplifier circuit 16 or the anode of the temperature sensitive diode SD can be connected to the non-inverting input terminal of the PWM comparator 18 via the switch 26. The switch 26 is a member for selectively connecting either the output terminal of the inverting amplifier circuit 16 or the anode of the temperature sensitive diode SD and the non-inverting input terminal of the PWM comparator 18.

  The switch 26 is operated by the operation unit 28. Specifically, when the operation unit 28 determines that the logic of the output signal of the comparator 22 is “H”, the operation unit 28 operates the switch 26 so as to connect the anode of the temperature sensitive diode SD and the non-inverting input terminal of the PWM comparator 18. When it is determined that the logic of the output signal of the comparator 22 is “L”, the switch 26 is operated so as to connect the output terminal of the inverting amplifier circuit 16 and the non-inverting input terminal of the PWM comparator 18.

  A carrier wave (triangular wave signal) output from the carrier wave generation circuit 30 is applied to the inverting input terminal of the PWM comparator 18. The PWM comparator 18 performs pulse width modulation on the input signal Vin by comparing the magnitude of the output signal Vf of the temperature sensitive diode SD or the input signal Vin which is the output signal of the inverting amplifier circuit 16 and the triangular wave signal tc. Here, FIG. 2A shows the transition of the input signal Vin and the triangular wave signal tc, and FIG. 2B shows the transition of the output signal of the PWM comparator 18. As a result, the output signal of the PWM comparator 18 is a time ratio duty (duty ratio), which is a ratio of the period Ton of the logic “H” to one period Tperiod of the logic “H” and the logic “L” in accordance with the input signal Vin. Becomes a pulse signal that changes.

  Incidentally, the output signal Vf of the temperature sensitive diode SD and the actual temperature of the power switching element Sw have a negative correlation. Further, the PWM comparator 18 and the carrier wave generation circuit 30 constitute modulation means.

  Returning to the description of FIG. 1, the pulse signal output from the PWM comparator 18 is input to the frame generation unit 32. The frame generation unit 32 generates and outputs a frame in which the pulse signal as temperature information of the power switching element Sw is arranged. The arrangement method for the temperature information and the like in the frame will be described in detail later.

  The output side of the frame generation unit 32 is connected to a power source 35 via a resistor 34. The output side of the frame generation unit 32 is connected to the primary side of the photocoupler 38 (the anode of the photodiode) via the resistor 36. Here, the photocoupler 38 is an insulation transmission means for transmitting a signal from the high voltage system to the low voltage system while insulating the high voltage system and the low voltage system.

  A microcomputer 40 is connected to the secondary side of the photocoupler 38. The microcomputer 40 is software processing means for performing various calculations by software processing. Specifically, the microcomputer 40 converts the temperature information of the power switching element Sw included in the information output from the frame generation unit 32 into digital data, and the power based on the time ratio duty calculated from the converted digital data. A temperature detection process for detecting the temperature of the switching element Sw is performed.

  When the microcomputer 40 determines that the temperature detection value of the power switching element Sw exceeds the threshold temperature, the microcomputer 40 performs a power saving process for prohibiting driving of the power switching element Sw. Thereby, the circulation of the collector current is prevented, and overheating of the power switching element Sw can be avoided.

  Subsequently, a correction method for the output signal Vf of the temperature-sensitive diode SD, which is a characteristic configuration according to the present embodiment, will be described with reference to FIG. 3A shows the relationship between the actual temperature Tf of the power switching element Sw and the input signal Vin of the non-inverting input terminal of the PWM comparator 18, and FIG. 3B shows the actual state of the power switching element Sw. The relationship between the temperature Tf and the duty ratio of the pulse signal output from the PWM comparator 18 is shown.

  As illustrated, in this embodiment, the temperature detection range of the power switching element Sw defined by the lower limit temperature Tmin (for example, 15 ° C.) and the upper limit temperature Tmax (for example, 175 ° C.) is set to the median value of the temperature detection range. The area is divided into a first detection range Td1 and a second detection range Td2 with Tctr (for example, 95 ° C.) as a boundary. Then, the terminal voltage of the power supply 24 is set to the output signal Vf of the temperature sensitive diode SD when the actual temperature Tf of the power switching element Sw becomes the median value Tctr. As a result, when the actual temperature Tf of the power switching element Sw becomes the first detection range Td1, the output signal Vf of the temperature sensitive diode SD becomes the input signal Vin of the non-inverting input terminal of the PWM comparator 18, and the power switching element Sw When the temperature Tf of the PWM comparator 18 falls within the second detection range Td2, the output signal “Vf−a × Vf” of the inverting amplifier circuit 16 becomes the input signal Vin of the non-inverting input terminal of the PWM comparator 18.

  In the present embodiment, in the first detection range Td1, as the actual temperature Tf of the power switching element Sw increases, the time ratio duty of the pulse signal output from the PWM comparator 18 changes from the upper limit value Dmax to the lower limit value Dmin. A triangular wave signal that continuously decreases toward the bottom is output from the carrier wave generation circuit 30. Specifically, the frequency and amplitude of the triangular wave signal are fixed values.

  Based on such a configuration, the output signal Vf of the temperature sensitive diode SD is corrected so as to satisfy the following conditions (A) and (B).

  (A) In the second detection range, as the actual temperature Tf of the power switching element Sw increases, the time ratio duty of the pulse signal output from the PWM comparator 18 continuously increases from the lower limit value Dmin to the upper limit value Dmax. The condition that the output signal Vf of the temperature sensitive diode SD is corrected so as to be higher.

  By satisfying the above condition (A), the time ratio duty ranges of the first detection range Td1 and the second detection range Td2 can be overlapped. Thereby, in each of these detection ranges Td1 and Td2, the temperature detection width per unit time ratio duty of the pulse signal output from the PWM comparator 18 can be reduced, and the dynamic range of the detection temperature of the power switching element Sw can be reduced. Can be enlarged. That is, the temperature detection accuracy of the power switching element Sw can be increased.

  In particular, in the present embodiment, the lower limit value Dmin is set to “0” (0%), and the upper limit value Dmax is set to “1” (100%). According to such setting, the temperature detection width per unit time ratio duty can be further reduced, and the temperature detection accuracy of the power switching element Sw can be further increased.

  Incidentally, in the present embodiment, the resistance values of the pair of resistors 16b and 16c constituting the inverting amplifier circuit 16 are set to be the same as each other, and the above condition (A) is satisfied by adjusting the terminal voltage of the power supply 16d. And By setting the resistance values of the resistors 16b and 16c to be the same, the absolute value of the slope of the input signal Vin in the first detection range Td1 and the slope of the input signal Vin in the second detection range Td2 are set. The absolute value of becomes equal.

  (B) The output signal Vf of the temperature sensitive diode SD is corrected so that the time ratio duty of the pulse signal output from the PWM comparator 18 becomes the lower limit value Dmin at the boundary between the first detection range Td1 and the second detection range Td2. Then the condition.

  This condition is a condition for avoiding a significant decrease in the temperature detection accuracy of the power switching element Sw. Hereinafter, after describing specific temperature detection processing in the present embodiment, the technical significance of the condition (B) will be described.

  First, the temperature detection process will be described with reference to FIG. Here, FIG. 4 is a diagram illustrating a frame data arrangement in the frame generation unit 32.

  In this embodiment, the structure which outputs the temperature information etc. of the power switching element Sw from the flame | frame production | generation part 32 per frame is employ | adopted. Then, detection range information for identifying whether the current temperature of the power switching element Sw is in the first detection range Td1 or the second detection range Td2 is arranged in the frame header. The detection range information is generated based on the output signal of the comparator 22. And the temperature information of the temperature sensing diode SD is arranged after the detection range information in the frame.

  The microcomputer 40 performs a temperature detection process based on the information output from the frame generation unit 32. Specifically, the microcomputer 40 first determines whether the actual temperature Tf of the power switching element Sw is in the first detection range Td1 or the second detection range Td2 based on the detection range information arranged in the frame header. Judging. When the microcomputer 40 determines that the current temperature of the power switching element Sw is in the first detection range Td1, the microcomputer 40 calculates the temperature detection value Tcal of the power switching element Sw lower as the duty ratio becomes higher. The temperature detection value Tcal may be calculated using, for example, a map in which the time ratio duty and the temperature detection value Tcal in the first detection range Td1 are associated with each other. .

  On the other hand, when the microcomputer 40 determines that the current temperature of the power switching element Sw is in the second detection range Td2, the microcomputer 40 calculates the temperature detection value Tcal of the power switching element Sw higher as the duty ratio becomes higher. The temperature detection value Tcal may be calculated using, for example, a map in which the time ratio duty is input and the temperature detection value Tcal in the second detection range Td2 is related. .

  Next, the technical significance of the condition (B) will be described.

  In order to increase the temperature detection accuracy of the power switching element Sw, apart from the correction method shown in FIG. 3, for example, in the second detection range Td2, the higher the actual temperature Tf of the power switching element Sw, the higher the PWM. It is also conceivable to employ a method of correcting the output signal Vf of the temperature sensitive diode SD so that the duty ratio of the pulse signal output from the comparator 18 continuously decreases from the upper limit value Dmax toward the lower limit value Dmin. . When such a method is employed, the output signal Vf of the temperature sensitive diode SD is corrected so that the duty ratio becomes discontinuous at the boundary Tctr between the first detection range Td1 and the second detection range Td2. For this reason, when the actual temperature Tf of the power switching element Sw changes from one of the first detection range Td1 and the second detection range Td2 to the other, the time ratio duty of the pulse signal output from the PWM comparator 18 increases. A changing phenomenon (hereinafter, “duty skip”) occurs.

  Here, under the situation where the actual temperature Tf of the power switching element Sw changes from one to the other of the first detection range Td1 and the second detection range Td2, the frame generation unit 32 detects the temperature information of the temperature sensing diode SD and In addition, the detection range information arranged in the frame may be different from the information corresponding to the actual temperature of the power switching element Sw. This is because, for example, the time until the output signal Vf of the temperature sensing diode SD is transmitted to the frame generation unit 32 via the comparator 22 is the time when the output signal Vf of the temperature sensing diode SD is the inverting amplifier circuit 16, the switch 26 and the PWM. This may be caused by the time being longer than the time until it is transmitted to the frame generation unit 32 via the comparator 18.

  If the detection range information is different from the information corresponding to the actual temperature of the power switching element Sw under the situation where the duty skip occurs, the map to be referred to in the temperature detection process is erroneously selected. As a result, there is a concern that the temperature detection value Tcal of the power switching element Sw greatly deviates from the actual temperature Tf, and the temperature detection accuracy of the power switching element Sw is greatly reduced.

  On the other hand, when the output signal Vf of the temperature sensitive diode SD is corrected so as to satisfy the condition (B), the duty skip does not occur. For this reason, even when the detection range information is different from the information corresponding to the actual temperature of the temperature sensitive diode SD, it is possible to avoid a large decrease in temperature detection accuracy due to the duty skip. That is, fail safe when the detection range information is not appropriate information can be realized.

  Incidentally, in the present embodiment, the condition (B) is satisfied by adjusting the terminal voltage of the power supply 16d.

  As described above, in this embodiment, the correction target for increasing the temperature detection accuracy of the power switching element Sw is the output signal Vf of the temperature sensitive diode SD. This is to improve both the temperature detection accuracy and to realize the temperature detection accuracy with a simple configuration.

  That is, in order to reduce the temperature detection width per unit time ratio duty of the pulse signal output from the PWM comparator 18, for example, the triangular wave signal output from the carrier wave generation circuit 30 may be corrected by an inverting amplifier circuit or the like. . Here, there is a concern that the correction accuracy of the triangular wave signal may be lowered due to the very high frequency of the triangular wave signal and the response characteristics of the operational amplifier that configures the inverting amplifier circuit. On the other hand, since the frequency of the output signal Vf of the temperature sensitive diode SD is sufficiently lower than the frequency of the triangular wave signal, it is possible to avoid a decrease in the correction accuracy of the output signal Vf in the inverting amplifier circuit 16. In addition, the configuration shown in FIG. 1 for correcting the output signal Vf of the temperature sensitive diode SD can be realized simply as compared with the configuration for correcting the amplitude, peak value, etc. of the triangular wave signal. For these reasons, the correction target is the output signal Vf of the temperature sensitive diode SD.

  Next, FIG. 5 shows a procedure of the temperature detection process according to the present embodiment. This process is repeatedly executed by the microcomputer 40 at a predetermined cycle, for example.

  In this series of processes, first, in step S10, based on the detection range information arranged in the frame header, the current temperature of the power switching element Sw is in either the first detection range Td1 or the second detection range Td2. Determine whether.

  If an affirmative determination is made in step S10, it is determined that the current temperature Tf of the power switching element Sw is within the first detection range Td1, and the process proceeds to step S12. In step S12, as described above, the temperature detection value Tcal of the power switching element Sw is calculated to be lower as the duty ratio is higher.

  On the other hand, if a negative determination is made in step S10, it is determined that the current temperature Tf of the power switching element Sw is within the second detection range Td2, and the process proceeds to step S14. In step S14, as described above, the temperature detection value Tcal of the power switching element Sw is calculated higher as the duty ratio becomes higher.

  In addition, when the process of step S12, S14 is completed, this series of processes is once complete | finished.

  According to the embodiment described in detail above, the following effects can be obtained.

  (1) An inverting amplifier circuit 16 is provided to correct the output signal Vf of the temperature sensitive diode SD so as to satisfy the above conditions (A) and (B). For this reason, the temperature detection accuracy of the power switching element Sw can be increased. Thereby, since the detection error of the temperature of the power switching element Sw becomes small, for example, the threshold temperature in the power saving process can be set with high accuracy.

  In addition, the condition (B) can prevent the temperature detection accuracy of the power switching element Sw from greatly decreasing due to the duty skip. Furthermore, according to the configuration according to the present embodiment, it is possible to improve the temperature detection accuracy of the power switching element Sw with a simple configuration.

  (2) The temperature detection range is divided into the first detection range Td1 and the second detection range Td2 with the median value Tctr as a boundary. For this reason, the temperature detection width in each of the first detection range Td1 and the second detection range Td2 can be made equal. Thereby, the temperature detection accuracy in each of these detection ranges Td1 and Td2 can be made equal.

(Second Embodiment)
Hereinafter, the second embodiment will be described with reference to the drawings with a focus on differences from the first embodiment.

  In this embodiment, the correction method of the output signal Vf of the temperature sensitive diode is changed.

  FIG. 6 shows a system configuration according to the present embodiment. In FIG. 6, the same members as those shown in FIG. 1 are denoted by the same reference numerals for the sake of convenience.

  As shown in the figure, the anode of the temperature sensitive diode SD is connected to the non-inverting input terminal side of the non-inverting amplifier circuit 42 including the operational amplifier 42a, the resistors 42b to 42e, and the power source 42f. The terminal side is grounded. In the present embodiment, hereinafter, the output signal of the non-inverting amplifier circuit 42 is represented by “Vβ + b × Vf”. Here, “b” indicates the amplification factor in the non-inverting amplifier circuit 42, and “Vβ” indicates the shift amount of the output signal of the non-inverting amplifier circuit 42 with respect to the ground potential “0”. This shift amount “Vβ” can be adjusted by adjusting the terminal voltage of the power supply 42 f connected to the non-inverting input terminal side of the non-inverting amplifier circuit 42.

  The output terminal of the inverting amplifier circuit 16 or the output terminal of the non-inverting amplifier circuit 42 can be connected to the non-inverting input terminal of the PWM comparator 18 via the switch 26. The switch 26 is operated by the operation unit 28 to selectively connect the output terminal of either the inverting amplifier circuit 16 or the non-inverting amplifier circuit 42 to the non-inverting input terminal of the PWM comparator 18. In the present embodiment, when the operation unit 28 determines that the logic of the output signal of the comparator 22 is “H”, the switch 28 connects the output terminal of the inverting amplifier circuit 16 and the non-inverting input terminal of the PWM comparator 18. 26, when the logic of the output signal of the comparator 22 is determined to be “L”, the switch 26 is operated to connect the output terminal of the non-inverting amplifier circuit 42 and the non-inverting input terminal of the PWM comparator 18. .

  Next, a method for correcting the output signal Vf of the temperature sensitive diode SD according to the present embodiment will be described with reference to FIG. Here, FIGS. 7A and 7B correspond to FIGS. 3A and 3B.

  As illustrated, in the present embodiment, the output signal Vf of the temperature sensitive diode SD is corrected so as to satisfy the following conditions (C) to (E).

  (C) In the first detection range Td1, the output of the temperature sensitive diode SD is such that the duty ratio continuously increases from the lower limit value Dmin to the upper limit value Dmax as the actual temperature Tf of the power switching element Sw increases. Conditions for correcting the signal Vf.

  (D) In the second detection range Td2, the output signal Vf of the temperature sensitive diode SD is set such that the duty ratio becomes lower from the upper limit value Dmax toward the lower limit value Dmin as the actual temperature Tf of the power switching element Sw increases. Condition to correct.

  These conditions are conditions set with the same meaning as the condition (A) of the first embodiment.

  (E) At the boundary Tctr between the first detection range Td1 and the second detection range Td2, the time ratio duty of the pulse signal output from the PWM comparator 18 is set to the upper limit value Dmax “1” so that the temperature sensing diode SD Conditions for correcting the output signal Vf.

  This condition is a condition set with the same purpose as the condition (B) of the first embodiment.

  Incidentally, in the present embodiment, the resistance values of the pair of resistors 16b and 16c and the terminal voltage of the power source 16d constituting the inverting amplifier circuit 16, and the resistance values and power sources of the resistors 42b to 42e constituting the non-inverting amplifier circuit 42 are described. The above conditions (C) to (E) are satisfied by adjusting the terminal voltage of 42f. Here, the inverting amplifier circuit 16 is configured such that the absolute value of the slope of the input signal Vin in the first detection range Td1 is equal to the absolute value of the slope of the input signal Vin in the second detection range Td2. The resistance values of the pair of resistors 16b and 16c are set to be the same, and the resistance values of the resistors 42b to 42e are set.

  Also by this embodiment described above, the same effects as those of the first embodiment can be obtained.

(Third embodiment)
Hereinafter, the third embodiment will be described with reference to the drawings with a focus on differences from the second embodiment.

  In this embodiment, the correction method of the output signal Vf of the temperature sensitive diode is changed. In the present embodiment, the terminal voltage of the power supply 24 is set to the output signal Vf of the temperature sensitive diode SD when the actual temperature Tf of the power switching element Sw becomes a specified temperature Tα described later. 6 determines that the output signal logic of the comparator 22 is “H”, the output terminal of the non-inverting amplifier circuit 42 and the non-inverting input terminal of the PWM comparator 18 are connected. When the switch 26 is operated so as to be connected and it is determined that the logic of the output signal of the comparator 22 is “L”, the switch is connected so as to connect the output terminal of the inverting amplifier circuit 16 and the non-inverting input terminal of the PWM comparator 18. 26 is operated.

  A method for correcting the output signal Vf of the temperature-sensitive diode SD according to the present embodiment will be described with reference to FIG. Here, FIGS. 8A and 8B correspond to FIGS. 7A and 7B.

  As shown in the figure, in the present embodiment, the temperature detection range of the power switching element Sw defined by the lower limit temperature Tmin and the upper limit temperature Tmax is shifted to a higher temperature side than the median value Tctr of the temperature detection range. It is divided into a first detection range Td1 and a second detection range Td2 with Tα as a boundary. Then, in addition to the above conditions (A) and (B), the output signal Vf of the temperature sensitive diode SD is corrected so as to satisfy the following condition (F).

  (F) In the first detection range Td1, as the actual temperature Tf of the power switching element Sw increases, the time ratio duty of the pulse signal output from the PWM comparator 18 increases from the upper limit value Dmax “1” to the lower limit value Dmin “0”. The condition that the output signal Vf of the temperature-sensitive diode SD is corrected so as to be continuously lowered toward "."

  Incidentally, in this embodiment, the resistance values of the pair of resistors 16b and 16c constituting the inverting amplifier circuit 16, the terminal voltage of the power supply 16d, the resistance values of the resistors 42b to 42e constituting the non-inverting amplifier circuit 42, and the power supply 42f. These conditions (A), (B), and (F) are satisfied by adjusting the terminal voltage. As a result, the absolute value of the slope of the input signal Vin in the second detection range Td2 is set larger than the absolute value of the slope of the input signal Vin in the first detection range Td1.

  According to this embodiment described above, instead of the effect (2) of the first embodiment, it is possible to obtain an effect that the temperature detection accuracy on the high temperature side of the power switching element Sw can be further increased. .

(Fourth embodiment)
Hereinafter, the fourth embodiment will be described with reference to the drawings with a focus on differences from the second embodiment.

  In this embodiment, the correction method of the output signal Vf of the temperature sensitive diode is changed. In the present embodiment, when the operation unit 28 shown in FIG. 6 determines that the logic of the output signal of the comparator 22 is “H”, the output terminal of the non-inverting amplifier circuit 42 and the PWM comparator 18 When the switch 26 is operated to connect the non-inverting input terminal and the logic of the output signal of the comparator 22 is determined to be “L”, the output terminal of the inverting amplification circuit 16 and the non-inverting input terminal of the PWM comparator 18 are connected. The switch 26 is operated to connect.

  A method for correcting the output signal Vf of the temperature-sensitive diode SD according to the present embodiment will be described with reference to FIG. Here, FIGS. 9A and 9B correspond to the previous FIGS. 7A and 7B.

  In the present embodiment, the range of the duty ratio corresponding to each of the first detection range Td1 and the second detection range Td2 is changed. Specifically, while changing the lower limit value Dmin of the duty ratio duty to a value (for example, 7%) higher than “0” and the upper limit value Dmax to a value (for example, 93%) lower than “1”, the above condition is satisfied. The output signal Vf of the temperature sensitive diode SD is corrected so as to satisfy (C) to (E). Thus, the absolute value of the slope of the input signal Vin in the first detection range Td1 is equal to the absolute value of the slope of the input signal Vin in the second detection range Td2. Here, the change of the lower limit value Dmin and the upper limit value Dmax is to suppress a decrease in temperature detection accuracy of the power switching element Sw.

  That is, “0” or “1” due to the fact that the actual waveform deviates from the ideal waveform in the vicinity of the maximum value and the minimum value of the triangular wave signal output from the carrier wave generation circuit 30 and the response characteristics of the comparator 22. In some cases, the PWM comparator 18 cannot generate a pulse signal having a near duty ratio. In this case, there is a concern that the time ratio duty corresponding to the actual temperature Tf of the power switching element Sw deviates from the initially assumed time ratio duty, and the temperature detection accuracy of the power switching element Sw decreases.

  In order to cope with such a problem, in the present embodiment, the lower limit value Dmin and the upper limit value Dmax of the duty ratio duty are changed in the above manner. For this reason, according to this embodiment, the fall of the temperature detection precision of the power switching element Sw resulting from a triangular wave signal can be suppressed.

(Fifth embodiment)
Hereinafter, a fifth embodiment will be described with reference to the drawings, focusing on differences from the first embodiment.

  In the present embodiment, as shown in FIG. 10, temperature information of a pair of power switching elements (hereinafter referred to as a first power switching element Swp and a second power switching element Swq) is transferred from a single integrated circuit 10 to a microcomputer 40. Adopt a transmission structure. Note that these power switching elements Swp and Swq are actually connected in parallel to each other. This is to increase the maximum value of the output current of the inverter that constitutes the first and second power switching elements Swp and Swq.

  In FIG. 10, the configuration for transmitting signals from the high voltage system to the low voltage system and the configuration of the low voltage system are the same as those in FIG. The members shown in FIG. 10 are basically the same as the members shown in FIG. 1, but the subscript “p” is added to the configuration corresponding to the first power switching element Swp. In addition, the subscript “q” is attached to the configuration corresponding to the second power switching element Swq.

  As illustrated, the output signals of the PWM comparators 18p and 18q and the output signals of the comparators 22p and 22q are input to the frame generation unit 32. As shown in FIG. 11, the frame generation unit 32 detects the detection range information corresponding to the first power switching element Swp based on the output signal of the comparator 22p, and the first power switching that is the pulse signal output from the PWM comparator 18p. Temperature information of the element Swp, detection range information corresponding to the second power switching element Swq based on the output signal of the comparator 22q, and temperature information of the second power switching element Swq that is a pulse signal output from the PWM comparator 18q. These pieces of information are arranged in one frame. Here, the detection range information corresponding to the first power switching element Swp is arranged in the first frame header, and the detection range information corresponding to the second power switching element Swq is arranged in the second frame header. The In the present embodiment, the detection range information is used in which the time ratios are different from each other.

  The microcomputer 40 performs a temperature detection process for detecting the temperature of the first power switching element Swp and the temperature of the second power switching element Swq based on the information output from the frame generation unit 32.

  According to the present embodiment described above, the temperature of the pair of power switching elements Swp and Swq can be accurately detected.

(Other embodiments)
Each of the above embodiments may be modified as follows.

  -"Correction means" is not restricted to what was illustrated to said each embodiment.

  For example, as shown in FIG. 12, time ratio ranges (Dmin to Dmax1, Dmin to Dmax2) corresponding to the first detection range Td1 (Tmin to Tβ) and the second detection range Td2 (Tβ to Tmax), respectively. The output signal Vf of the temperature-sensitive diode SD may be corrected so that a part of (Dmin to Dmax2) overlaps each other. 12 (a) and 12 (b) correspond to the previous FIGS. 8 (a) and 8 (b).

  Further, for example, as shown in FIG. 13, the output signal Vf of the temperature sensitive diode SD is corrected so that the time ratio duty becomes discontinuous at the boundary Tctr between the first detection range Td1 and the second detection range Td2. It may be a thing. Here, the range of the duty ratio of the first detection range Td1 is a range defined by the first lower limit value Dmin1 “0” and the upper limit value Dmax “1”, and the duty ratio duty of the second detection range Td2 Is a range defined by a second lower limit value Dmin2 and an upper limit value Dmax that are higher than the first lower limit value Dmin1. In this case, as the absolute value of the difference “Dmin1−Dmin2” in the duty ratio at the boundary is smaller, the degree of decrease in the temperature detection accuracy due to the duty skip becomes smaller. 13 (a) and 13 (b) correspond to the previous FIGS. 3 (a) and 3 (b).

  Furthermore, as a correction means for correcting the output signal Vf of the temperature sensitive diode SD so that the duty ratio becomes discontinuous, the correction means shown in FIG. 14 may be used. In this case, the output signal Vf of the temperature sensitive diode SD is corrected so that the time ratio ranges corresponding to the first detection range Td1 and the second detection range Td2 overlap each other. Even with such a configuration, the dynamic range of the detected temperature can be expanded.

  The number of divisions of the temperature detection range is not limited to two and may be three or more. Even in this case, it is possible to detect the temperature based on the detection range information regarding whether the current temperature of the power switching element Sw is in a plurality of divided temperature detection ranges and the time ratio.

  In the first embodiment, the configuration in which the detection range information is arranged in the frame header and is transmitted to the microcomputer 40 is not limited to this. For example, another insulation transmission unit (second photocoupler) different from the photocoupler 38 may be provided and the output signal of the comparator 22 may be transmitted to the microcomputer 40 via the second photocoupler.

  The insulation transmission means is not limited to the one provided with the optical insulation element, and may be provided with a magnetic insulation element (pulse transformer), for example.

  The temperature detection processing method is not limited to the one exemplified in the first embodiment. For example, after the inverter is started and the driving of the power switching element Sw is started, after the time assumed that the temperature of the power switching element Sw shifts from the first detection range Td1 to the second detection range Td2, A method may be used in which the map used in the temperature detection process is switched from the map corresponding to the first detection range Td1 to the map corresponding to the second detection range Td2. In this case, the detection range information is not essential.

  In FIG. 8 of the third embodiment, the upper limit value Dmax that defines the range of the time ratio is set to a value lower than “1”, and the lower limit value Dmin that defines the range is less than “0”. A high value may be set.

  The method for dividing the temperature detection range is not limited to the one exemplified in the third embodiment. For example, a technique may be employed in which the temperature detection range is divided into the first detection range Td1 and the second detection range Td2 with a value shifted from the median value Tctr as a lower temperature side as a boundary. Even in this case, it is possible to further increase the temperature detection accuracy of the first detection range Td1, which is the narrower detection range of the first detection range Td1 and the second detection range Td2.

  The carrier wave used in the “modulation means” is not limited to a triangular wave signal, and may be a sawtooth wave signal, for example.

  The execution subject of the temperature detection process is not limited to software processing means (microcomputer 40), but may be hardware processing means configured by hardware.

  The “detection element” is not limited to a temperature-sensitive diode, and may be, for example, a resistor (temperature measuring resistor). In this case, as a specific configuration of temperature detection, for example, in the first embodiment, one end of a resistor is connected to the output side of the constant current power supply 14 instead of the temperature sensitive diode, and the other end of the resistor is connected. A structure for grounding may be employed. In such a configuration, the resistor serves as a detection element that outputs a signal (voltage drop amount in the resistor) having a correlation with the temperature of the power switching element Sw. Here, the voltage drop amount increases as the temperature of the power switching element Sw increases.

  The detection element may be, for example, a MOS field effect transistor. This is because the voltage between the source and the drain in the case where the same current flows between the source and the drain of the MOS field effect transistor has temperature dependency.

  The power switching element Sw that is the “predetermined detection target” is not limited to the IGBT, and may be, for example, a power MOS field effect transistor. The detection target is not limited to the power switching element Sw. In this case, the “detection element” is not limited to one that outputs a signal having a correlation with the temperature of the detection target, but may be another detection element as long as it outputs a signal having a correlation with the physical quantity of the detection target. It may be.

  DESCRIPTION OF SYMBOLS 16 ... Inverting amplifier circuit, 18 ... PWM comparator, 30 ... Carrier wave generation circuit, 40 ... Microcomputer, Sw ... Power switching element, SD ... Temperature-sensitive diode.

Claims (11)

A detection element (SD, SDp, SDq) that outputs a signal (Vf) correlated with a physical quantity (Tf) of a predetermined detection target (Sw, Swp, Swq);
Modulation means (18, 30, 18p, 30p, 18q, 30q) for performing pulse width modulation on the output signal based on the magnitude comparison between the output signal of the detection element and the carrier wave (tc);
Each physical quantity detection range of the detection target is divided into multiple and duty ratio of the detection target physical quantity and a pulse signal outputted from said modulating means is associated continuously in (Td1, Td2), a plurality At least a part of the time ratio ranges (Dmin to Dmax, Dmin to Dmax1, Dmin to Dmax2, Dmin1 to Dmax, Dmin2 to Dmax) corresponding to each of the physical quantity detection ranges divided into two overlap each other. Correction means (16, 42, 16p, 16q) for correcting the output signal of the detection element input to the modulation means;
Output means (32) for outputting detection range information for identifying which one of the physical quantity detection ranges divided into a plurality of the current physical quantities to be detected and a time ratio of the pulse signal in units of frames; ,
Equipped with a,
Among the frames, the detection range information is arranged in a frame header, the pulse signal is arranged after the detection range information,
Based on said time ratio of the detection range information outputted from the output means and said pulse signal, said detecting means for detecting a physical quantity to be detected (40) a physical quantity detecting device according to claim Rukoto equipped with. Physical quantity detecting device according to claim 1, wherein the frequency of said carrier, wherein a fixed value der Rukoto. A detection element (SD, SDp, SDq) that outputs a signal (Vf) correlated with a physical quantity (Tf) of a predetermined detection target (Sw, Swp, Swq);
Modulation means (18, 30, 18p, 30p, 18q, 30q) for performing pulse width modulation on the output signal based on the magnitude comparison between the output signal of the detection element and the carrier wave (tc);
In each of the detection target physical quantity detection ranges (Td1, Td2) divided into a plurality, the physical quantity of the detection target and the time ratio (duty) of the pulse signal output from the modulation means are continuously related and , At least some of the time ratio ranges (Dmin to Dmax, Dmin to Dmax1, Dmin to Dmax2, Dmin1 to Dmax, Dmin2 to Dmax) corresponding to each of the physical quantity detection ranges divided into a plurality overlap each other. Correction means (16, 42, 16p, 16q) for correcting the output signal of the detection element input to the modulation means,
Output means (32) for outputting detection range information for identifying which one of the physical quantity detection ranges divided into a plurality of current physical quantities to be detected is;
Detection means (40) for detecting a physical quantity of the detection target based on the duty ratio of the pulse signal output from the modulation means and the detection range information output from the output means;
With
The correction means detects the time ratio related to the physical quantity to be detected at a boundary (Tctr, Tα, Tβ) of detection ranges adjacent to each other among the physical quantity detection ranges divided into a plurality of detection ranges. physical quantity detecting device thing you and corrects the output signal of the element. The physical quantity detection range is divided into a first detection range (Td1) and a second detection range (Td2) having a physical quantity larger than the first detection range,
The correcting means reduces the time ratio as the physical quantity of the detection target increases in the first detection range, and increases the time ratio as the physical quantity increases in the second detection range. The physical quantity detection device according to claim 3, wherein the output signal of the detection element is corrected. The physical quantity detection range is divided into a first detection range (Td1) and a second detection range (Td2) having a physical quantity larger than the first detection range,
The correcting means increases the time ratio as the physical quantity of the detection target increases in the first detection range, and decreases the time ratio as the physical quantity increases in the second detection range. The physical quantity detection device according to claim 3, wherein the output signal of the detection element is corrected. The physical quantity detection range is divided into the first detection range and the second detection range with a median value (Tctr) of the physical quantity detection range as a boundary,
In the first detection range and the second detection range, the correction unit is configured such that the duty ratio related to the physical quantity to be detected is a first specified value (Dmin) and the first specified value. 6. The physical quantity detection device according to claim 4, wherein an output signal of the detection element is corrected so as to be in a range of the duty ratio defined by a second specified value (Dmax) higher than the threshold value. The physical quantity detection range is divided into the first detection range and the second detection range with a value (Tα, Tβ) deviated from the median value (Tctr) of the physical quantity detection range as a boundary,
In the first detection range and the second detection range, the correction unit is configured such that the duty ratio related to the physical quantity to be detected is a first specified value (Dmin) and the first specified value. 6. The physical quantity detection device according to claim 4, wherein an output signal of the detection element is corrected so as to be in a range of the duty ratio defined by a second specified value (Dmax) higher than the threshold value. The first specified value is set to a value higher than “0”;
The physical quantity detection device according to claim 6 or 7, wherein the second specified value is set to a value lower than "1". The first specified value is set to “0”;
The physical quantity detection device according to claim 6, wherein the second specified value is set to “1”. The detection target is plural (Swp, Swq),
The modulation means (18p, 30p, 18q, 30q) performs pulse width modulation on each of the output signals based on the magnitude comparison between the output signals of the plurality of detection targets and the carrier wave, and outputs them,
A second output means (32) for outputting a pulse signal corresponding to each of the plurality of detection objects output from the modulation means as a group of information;
The second output means includes, in the group of information, information that identifies which of the plurality of detection objects each of the pulse signals included in the group of information corresponds to.
The said detection means detects each physical quantity of the said several detection target based on the said identification information output from the said 2nd output means, and the said time ratio. The physical quantity detection device according to any one of the above.   The physical quantity detection device according to claim 1, wherein the detection element outputs a signal having a correlation with the temperature of the detection target.

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