JP2009171312A - Onboard information transfer apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve the problem that, when transferring information about the temperature of a temperature sensing diode SD that senses the temperature of an inverter to a microcomputer 20, if a port comprising a timer function or an A/D conversion function of the microcomputer 20 is used, its resources may be reduced. <P>SOLUTION: A signal frequency-modulated by a frequency modulation circuit 34 based on an output voltage of the temperature sensing diode SD is fetched into a photocoupler 36. An output of the photocoupler 36 is fetched into the microcomputer 20. In the microcomputer 20, processing is performed by hardware for recognizing a logic "H" when an output voltage of the photocoupler 36 is equal to or higher than a threshold voltage or for recognizing a logic "L" if it is lower than the threshold voltage. At the same time, demodulation processing for temperature information based on a period of time of the logic "H" or a period of time of the logic "L" is performed as software processing. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an in-vehicle information transmission device that transmits information related to a state of a specific part of a vehicle.

As this type of transmission device, for example, as seen in Patent Document 1 below, the voltage signal output from the detection means for detecting the temperature of the switching element composed of an insulated gate bipolar transistor (IGBT) or the like is converted into a frequency signal, A device that outputs to a frequency / voltage conversion circuit via a photocoupler has also been proposed. Thereby, the information about the temperature can be appropriately transmitted between two systems that are desired to be insulated through an insulating means such as a photocoupler.
JP 7-115354 A

  In the above case, it is necessary to provide a frequency / voltage conversion circuit on the output side of the photocoupler. Further, when the output of the frequency / voltage conversion circuit is processed in the microcomputer, it is necessary to assign a port for analog / digital conversion (A / D conversion) processing of the microcomputer to the output of the frequency / voltage conversion circuit. In such a case, when there is not one temperature detection means, a plurality of frequency / voltage conversion circuits or a plurality of ports for performing A / D conversion processing to which the output of the frequency / voltage conversion circuit is assigned are provided. Therefore, it is necessary to increase the number of parts and the consumption of microcomputer resources.

  Further, when the output of the photocoupler is directly taken into the microcomputer to avoid the increase in the number of parts, the output signal frequency is limited by the sampling period of the microcomputer. On the other hand, the time required to extract information (detected value) from the output signal depends on the frequency specific to the output signal. For this reason, when the output of the photocoupler is directly taken into the microcomputer, there arises a problem that the time required for the microcomputer itself to extract information from the taken signal is prolonged.

  In addition to the temperature of the switching element described above, in the case of transmitting information on the state of a specific part of the vehicle, the time required to extract information from the frequency signal is limited by the specific frequency of the signal. This situation that causes inconveniences such as an increase in points is also common.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to provide an in-vehicle information transmission device that can more appropriately transmit information on the state of a specific part of a vehicle.

  Hereinafter, means for solving the above-described problems and the operation and effects thereof will be described.

  According to the first aspect of the present invention, state detecting means for detecting the state of a specific part of the vehicle, transmitting means for transmitting a signal that is frequency-modulated based on information relating to the detected state, and receiving the transmitted signal Receiving means.

  In the above invention, since a signal frequency-modulated based on information is used, the time until the receiving side can grasp the information by demodulating the signal depends on the modulated frequency. . For this reason, in particular, in the case of information that is to be quickly grasped, by using a high frequency, it is possible to appropriately respond to a request to quickly grasp. For this reason, in the said invention, information can be transmitted more appropriately.

  According to a second aspect of the present invention, in the first aspect of the invention, the receiving means is a state in which the voltage level of the transmitted signal is greater than or equal to a predetermined level, and a state in which the voltage level is higher than or equal to the predetermined level. A timing means for measuring a required time from one of these two timings to the other with respect to a transition timing from a state less than a predetermined state to a state less than a predetermined state and a transition timing from a state less than the predetermined state to a state greater than or equal to the predetermined amount; It is characterized by providing.

  In the above invention, since the frequency can be grasped by the time measuring means, the information can be demodulated from the received signal.

  According to a third aspect of the present invention, in the second aspect of the present invention, the time measuring means is configured by software.

  For example, a hardware function for digital processing such as a microcomputer usually has a timer function that performs a time measuring operation triggered by a transition timing between a state where the voltage level of an input signal is equal to or higher than a predetermined level and a state where the voltage level is lower than a predetermined level. Etc. are often provided as hardware, but such input terminals are limited. On the other hand, the number of input terminals to which only the function of detecting whether or not the voltage level applied to the input terminals is equal to or higher than a hardware level is relatively large. In the above invention, in view of this point, the time measuring means can be configured without using a valuable input terminal by configuring the time measuring means with software. For this reason, the types of usable hardware resources are abundant.

  According to a fourth aspect of the present invention, in the invention according to any one of the first to third aspects, the transmission unit is required to quickly acquire the information related to the state by the reception unit. The more the signal is transmitted, the higher the frequency.

  Information can be extracted more quickly when information is superimposed on a high-frequency signal than when information is superimposed on a low-frequency signal. In the above invention, in view of this point, it is possible to appropriately cope with such a request by modulating the carrier wave to a higher frequency as the information is required to be quickly acquired by the receiving unit.

  The invention according to claim 5 is the invention according to any one of claims 1 to 4, wherein the state detecting means is means for detecting a temperature at a predetermined location of the vehicle, and the transmitting means is the temperature. The higher the frequency, the higher the frequency.

  As for the detection result of the in-vehicle temperature detection means, generally, the higher the temperature is, the higher the demand for quickly transmitting the information to the receiving side. In the above invention, in view of this point, the higher the temperature, the higher the frequency, and the higher the temperature, the faster the information can be transmitted.

  The invention according to claim 6 is the invention according to claim 5, wherein the temperature detecting means detects a temperature of the in-vehicle power conversion circuit, and the in-vehicle power is based on a signal received by the receiving means. When the temperature of the conversion circuit is equal to or higher than a predetermined value, it includes a limiting unit that limits the operation of the in-vehicle power conversion circuit.

  In the said invention, when the temperature of a power converter circuit becomes more than predetermined, it becomes possible to restrict | limit operation quickly.

  The invention according to claim 7 is the invention according to any one of claims 1 to 6, wherein the state detection means detects a temperature in an in-vehicle high-pressure system, and the reception means The signal transmitted by the means is received through the insulating means.

  When the insulating means is provided, it is well known that an input signal to the insulating means is a frequency signal such as a binary signal because it is difficult to directly transmit an analog signal with high accuracy. In this regard, in the above invention, the means for performing the frequency modulation process can be a means for converting to a frequency signal.

  Hereinafter, an embodiment in which an in-vehicle information transmission device according to the present invention is applied to a parallel series hybrid vehicle will be described with reference to the drawings.

  FIG. 1 shows a portion related to one of two rotating machines mounted on a parallel series hybrid vehicle in the entire configuration of the motor generator control system according to the present embodiment.

  As shown in the figure, an inverter 12 is connected to three phases (U phase, V phase, and W phase) of the motor generator 10. The inverter 12 is a three-phase inverter, and appropriately applies the voltage of the high voltage battery 14 to the three phases of the motor generator 10. Specifically, the inverter 12 is a parallel connection body of the switching elements SW1, SW2, the switching elements SW3, SW4, and the switching elements SW5, SW6 so that each of the three phases and the positive electrode side or the negative electrode side of the high voltage battery 14 are electrically connected. It is configured with. A connection point for connecting switching element SW <b> 1 and switching element SW <b> 2 in series is connected to the U phase of motor generator 10. Further, a connection point for connecting switching element SW3 and switching element SW4 in series is connected to the V phase of motor generator 10. Furthermore, a connection point for connecting switching element SW5 and switching element SW6 in series is connected to the W phase of motor generator 10. Incidentally, these switching elements SW1 to SW6 are constituted by insulated gate bipolar transistors (IGBT) in this embodiment. The inverter 12 includes flywheel diodes D1 to D6 connected in antiparallel to the switching elements SW1 to SW6.

  The inverter 12 is further provided with a temperature sensitive diode SD for sensing the temperature.

  The switching elements SW <b> 1 to SW <b> 6 are operated by a microcomputer (microcomputer 20) using the low voltage battery 18 as a power source via the driver unit 16. At this time, the switching restriction processing unit 20a of the microcomputer 20 acquires the temperature sensed by the temperature sensing diode SD, and when this temperature is equal to or higher than a predetermined value, the switching element SW1 is used to limit the current flowing through the switching elements SW1 to SW6. The switching state of .about.SW6 is limited or the inverter 12 is shut down. FIG. 2 shows components of an information transmission path in the driver unit 16 that transmits temperature information sensed by the temperature sensitive diode SD to the microcomputer 20.

  As shown in the figure, the cathode side of the temperature sensitive diode SD is grounded, and the anode side is connected to the power source 30 via the constant current source 32. The voltage on the anode side of the temperature sensing diode SD is taken into the frequency modulation circuit 34 as a signal having a correlation with the temperature sensed by the temperature sensing diode SD. In the frequency modulation circuit 34, an AC signal frequency-modulated based on the input voltage signal is output to the photocoupler 36. As a result, the frequency-modulated AC signal is applied to the anode of the photodiode constituting the primary side of the photocoupler 36. Incidentally, the cathode side of the photodiode of the photocoupler 36 is grounded.

  The emitter of the phototransistor constituting the secondary side of the photocoupler 36 is grounded, and the collector is connected to the power supply 38 via the resistor 37. Further, the collector voltage of the photocoupler 36 is taken into the general-purpose port of the microcomputer 20 as an output signal of the photocoupler 36. Here, the general-purpose port recognizes, as hardware means, a function that recognizes a logic “H” if the applied voltage is equal to or higher than the threshold voltage and recognizes a logic “L” if the applied voltage is less than the threshold. However, it does not have a function of performing a timing operation or the like with the time of switching between logic “H” and logic “L” as a trigger. The reason for this is to avoid the use of such limited resources because the ones having the function of performing the above-mentioned timing operation (ports having a timer function) are limited among the ports of the microcomputer 20.

  In particular, in the case of a parallel series hybrid vehicle as in the present embodiment, since it is actually provided with two motor generators and provided with inverters for each of them, a port of the microcomputer 20 is provided for each piece of information regarding the temperature of each inverter. Need. For this reason, when a port having a timer function is used, the amount of consumption of these resources also increases.

  For this reason, in this embodiment, the process of demodulating the temperature information by measuring the period when the voltage level determined by the hardware in the microcomputer 20 is the logic “H” or the period of the logic “L”, Performed as software processing. Here, the demodulation accuracy of information depends on the sampling cycle of the voltage level to be taken in. In other words, the shorter the sampling cycle, the more the timing accuracy of the logic “H” period and the logic “L” period can be improved. On the other hand, in the case of software processing, the calculation load on the microcomputer 20 increases as the sampling period is shortened. For this reason, there is a limitation in shortening the sampling period.

  Therefore, in the present embodiment, the frequency modulation circuit 34 performs modulation such that the higher the temperature sensed by the temperature sensing diode SD, the higher the frequency, and the frequency at the highest sensed temperature is approximately the reciprocal of the sampling period. To do. As a result, since it is possible to accurately measure a certain period of the voltage level of the input port at the maximum temperature, temperature information below the maximum temperature can be demodulated with high accuracy. Furthermore, since the information superimposed on the higher frequency signal can be demodulated in a shorter time, the temperature information near the maximum temperature can be demodulated particularly quickly. Therefore, it is possible to quickly acquire temperature information in the vicinity of the maximum temperature while setting the sampling period from the viewpoint of reducing the load on the microcomputer 20.

  FIG. 3 shows a frequency modulation mode by the frequency modulation circuit 34. As illustrated, as the temperature transitions from a low temperature to a high temperature, the frequency is modulated to a frequency band of “several Hz” to “several hundred Hz”. This is related to the fact that the sampling period of the voltage level of the input port is set to about “several ms” from the viewpoint of the calculation load of the microcomputer 20. In this case, the upper limit of the frequency that can be accurately detected is “several hundred Hz”. On the other hand, what frequency is assigned to the lowest temperature sensed by the temperature sensitive diode SD depends on the required temperature accuracy. That is, the lowest frequency is a frequency that is approximately the reciprocal of the multiplication value obtained by dividing the value obtained by dividing the maximum temperature and the minimum temperature with the required temperature accuracy (resolution Td) by the sampling period.

Specifically, in the frequency modulation circuit 34, the modulation frequency f is defined by the following equation using the minimum period Smin of the output signal, the temperature T sensed by the temperature-sensitive diode SD, the maximum value Tmax, and the resolution Td.
f = 1 / [Smin · {(Tmax−T) / Td + 1}]
FIG. 4 shows a procedure of temperature information demodulation processing in the microcomputer 20. This process is defined by a program stored in the microcomputer 20, and this program is executed by the central processing unit (CPU) at a predetermined cycle.

  In this series of processing, first, in step S10, it is determined whether or not it is a sampling timing. This is a setting for sampling the voltage level of the port at a predetermined time period. The sampling period SP may be “several ms”, for example. And when it is judged that it is a sampling timing, it transfers to step S12. In step S12, it is determined whether or not the voltage level applied to the port by the photocoupler 36 is logic "H". If it is determined that the level is the logic “H” level, it is determined in step S14 whether or not the voltage level applied to the previous port is the logic “H” level. In this process, it is determined whether or not the voltage level applied to the port has changed from the logic “L” level to the logic “H” level. If it is determined in step S14 that the logic “H” level is present, it is considered that the logic “H” level is in a continuous state, and therefore the duration of the logic “H” level is counted. Therefore, the counter is incremented in step S16.

  Under these circumstances, if it is determined in step S12 that the level is not the logic “H” level, it is determined in step S18 whether or not the voltage level applied to the previous port is the logic “H” level. In this process, it is determined whether or not the voltage applied to the port has changed from the logic “H” level to the logic “L” level. If it is determined in step S18 that the level is the logic “H” level, it is determined that the timing has changed from the logic “H” level to the logic “L” level, and the process proceeds to step S20. In step S20, the temperature is calculated from the count value of the counter. Here, the count value of the counter has a correlation with the cycle of the output signal of the photocoupler 36. For this reason, the larger the count value, the lower the temperature. When the process of step S20 is completed, the counter is reset in step S22.

  On the other hand, when a negative determination is made in step S18, the voltage level applied to the port is considered to be in a state where the logic "L" level state continues. In order to measure time, the counter is incremented in step S24.

  Under these circumstances, when an affirmative determination is made at step S12 and a negative determination is made at step S14, in other words, when it is time to change from a logic "L" level to a logic "H" level, In S26, the temperature is calculated from the count value in the same manner as in Step S20. If the frequency of the output signal of the photocoupler 36 is the same, the logic “H” period and the logic “L” period are considered to be the same. Therefore, the relationship between the count value and the temperature is the same as that in step S20 and step S26. The process is exactly the same. When the process of step S26 is completed, the counter is reset in step S28.

  In addition, when the process of step S16, S22, S24, S28 is completed, or when negative determination is made in step S10, this series of processes is once complete | finished.

  FIG. 5 schematically shows an aspect of the above processing when the temperature sensed by the temperature sensitive diode SD rises. Specifically, FIG. 5A schematically shows the input waveform of the microcomputer 20 when the temperature continuously increases, and FIG. 5B shows the voltage applied to the port of the microcomputer 20. FIG. 5C shows the timing operation of the counter.

  As shown, the counter is frequently reset due to the frequent reversal of the voltage level applied to the port at higher temperatures. For this reason, the opportunity to acquire temperature information by the process of previous step S20, S26 of FIG. 4 increases, so that it becomes high temperature. For this reason, in the situation where the temperature of the inverter 12 becomes excessively high, the operation of the inverter 12 can be quickly restricted in the switching restriction processing unit 20a shown in FIG.

  5A shows the input waveform of the microcomputer 20 when the temperature of the temperature sensitive diode SD rises, the time ratio of the logic “H” to the period of the logic “H” and the logic “L”. Although it is described that (Duty) does not become “50%”, in this embodiment, when the temperature is constant, the input waveform is a frequency signal of Duty “50%”.

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

  (1) While the frequency-modulated signal is transmitted based on the information about the temperature sensed by the temperature sensitive diode SD, the microcomputer 20 determines whether the voltage level of the transmitted signal is a logic “H” level or a logic “L” level. The process of demodulating the frequency signal by measuring the duration of the logic “H” or the logic “L” is determined as a software process. For this reason, the demodulation process can be performed without using a valuable port to which a timer function or the like that performs a timing operation using a transition timing of a voltage level applied to the port as a trigger can be used.

  (2) The higher the temperature of the temperature sensitive diode SD, the higher the frequency. As a result, the information can be transmitted more quickly as the temperature is higher.

  (3) When the temperature of the inverter 12 is equal to or higher than a predetermined temperature, the switching restriction processing unit 20a that restricts the operation of the inverter 12 is provided. Here, the higher the temperature of the temperature sensitive diode SD, the higher the frequency of the signal, the higher the temperature of the inverter 12, the faster the operation can be restricted.

  (4) Information on the temperature sensed by the temperature sensitive diode SD is transmitted to the microcomputer 20 via the photocoupler 36. Here, since it is difficult for the photocoupler 36 to directly transmit an analog signal with high accuracy, the photocoupler 36 is required to be a frequency signal in advance. In this regard, in the present embodiment, the frequency modulation circuit 34 can be a frequency signal generating means that should be provided in the preceding stage of the photocoupler 36.

(Other embodiments)
The above embodiment may be modified as follows.

  In the above embodiment, the output of the frequency modulation circuit 34 is an AC waveform signal. However, the output is not limited to this, and may be a binary signal, for example. At this time, the time ratio (Duty) of the logic “H” time for one cycle is not limited to “50%”. However, if the duty is not “50%”, the microcomputer 20 converts the measured value into temperature when measuring the logic “H” period and when measuring the logic “L” period. It is desirable to make the processing to be different. Alternatively, the temperature conversion target may be limited to one of a logic “H” period and a logic “L” period.

  The frequency modulation mode by the frequency modulation circuit 34 is not limited to that based on the above formula. For example, the frequency may be proportional to the square root of the temperature T.

  The information to be transmitted is not limited to the temperature of the inverter 12. For example, in a configuration in which each of the switching elements SW1 to SW6 of the inverter 12 is provided with a temperature-sensitive diode independently, the temperature of each of the switching elements SW1 to SW6 may be information to be transmitted. In the case where the inverter 12 is connected to the high voltage battery 14 via the booster circuit, the temperature of the switching element constituting the booster circuit may be information to be transmitted.

  In the above-described invention, the clocking process for clocking the interval between the logic inversion timings of the input signal of the microcomputer 20 is realized by software, but is not limited thereto. For example, the clock processing may be realized by hardware by taking the output of the photocoupler 36 from an input port having a timer function of the microcomputer 20. Even in this case, by increasing the frequency as the temperature sensed by the temperature sensitive diode SD is higher, the time required for the microcomputer 20 to grasp the temperature can be shortened as the temperature is higher.

  -Information to be transmitted is not limited to the temperature information of the high-pressure system. Whatever the information, if the degree to which the microcomputer needs to acquire the value quickly differs depending on the value, the necessary information can be acquired quickly by using a frequency-modulated signal based on this. The application of the present invention is effective because a signal modulated through a general-purpose input port that does not have a timer function can be taken into the microcomputer.

  -The in-vehicle power conversion circuit is not limited to an inverter. For example, a DCDC converter that steps down the voltage of the high voltage battery 14 and outputs it to the low voltage battery 18 may be used.

  The hybrid vehicle is not limited to a parallel series hybrid vehicle, and may be a series hybrid vehicle, for example. Moreover, you may apply the information transmission apparatus of this invention not only to a hybrid vehicle but to an electric vehicle, for example.

The system block diagram concerning one Embodiment. The figure which shows the transmission path | route of the temperature information concerning the embodiment. The figure which shows the relationship between the temperature and the frequency in the modulation process of the embodiment. 5 is a flowchart showing a procedure of temperature information demodulation processing according to the embodiment; The time chart which shows the aspect of the demodulation process of the temperature information concerning the embodiment.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10 ... Motor generator, 12 ... Inverter, 14 ... High voltage battery, 20 ... Microcomputer, 34 ... Frequency modulation circuit, 36 ... Photocoupler, SD ... Temperature sensitive diode.

Claims (7)

State detection means for detecting the state of a specific part of the vehicle;
Transmitting means for transmitting a frequency-modulated signal based on information on the detected state;
An in-vehicle information transmission device comprising: reception means for receiving the transmitted signal.   The receiving means determines whether or not the voltage level of the signal to be transmitted is equal to or higher than a predetermined level, a transition timing from a state that is equal to or higher than the predetermined level to a state that is lower than a predetermined level, and the predetermined level. 2. The in-vehicle information transmission device according to claim 1, further comprising a timing unit that counts a required time from one of the two timings to the other of the transition timings from the state to the predetermined state. .   The in-vehicle information transmission apparatus according to claim 2, wherein the time measuring means is configured by software.   4. The transmission device according to claim 1, wherein the transmitting unit sets the signal to be transmitted to a high frequency so that the information on the state is required to be quickly acquired by the receiving unit. The in-vehicle information transmission device according to item 1. The state detecting means is means for detecting the temperature of a predetermined location of the vehicle,
The in-vehicle information transmission apparatus according to claim 1, wherein the transmission unit sets the frequency to a higher frequency as the temperature is higher. The temperature detection means is for detecting the temperature of the in-vehicle power conversion circuit,
6. The in-vehicle device according to claim 5, further comprising a restricting unit that restricts an operation of the in-vehicle power conversion circuit when a temperature of the in-vehicle power conversion circuit is equal to or higher than a predetermined temperature based on a signal received by the receiving unit. Information transmission device. The state detection means detects the temperature in the in-vehicle high-pressure system,
The in-vehicle information transmission apparatus according to claim 1, wherein the receiving unit receives a signal transmitted from the transmitting unit via an insulating unit.

Images