JP2007198792A - Temperature detection circuit, controller, and electric vehicle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a high-precision temperature detection circuit which can be used when temperature detection elements having different characteristics are used and which is resistant to accuracy deterioration even for long-term use. <P>SOLUTION: The temperature detection circuit for at least one temperature detection element of which the output value changes in response to temperature comprises a conversion circuit and an adder circuit. The conversion circuit converts the output value from the temperature detection element into a first signal having a signal level corresponding to the output value and outputs it. The adder circuit, on the basis of the first signal, performs addition of a temperature compensation offset signal, which corresponds to the signal level of the first signal read from a storage section storing the correspondence relation between the signal level of the first signal and the signal level of the temperature compensation offset signal, and the first signal and outputs a second signal indicating a signal level indicating the addition result. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a temperature detection circuit, a control device for the temperature detection circuit, and an electric vehicle including the same. In particular, the present invention relates to a temperature detection circuit for at least one temperature detection element whose output value changes according to temperature, and an electric vehicle including the same.

  Conventionally, a temperature detection circuit using a thermistor as a temperature detection element is known. The thermistor detects the temperature by a change in resistance value. However, the temperature-voltage characteristics of the thermistor are not linear, and the voltage change for a certain temperature change tends to flatten in the high temperature range and the low temperature range, and the temperature detection accuracy decreases in the high temperature range and the low temperature range. was there.

  Prior art for solving this problem is disclosed in Patent Document 1. The temperature detection circuit described in Patent Document 1 pays attention to the fact that the temperature-voltage characteristic of the thermistor is exponential, and has a logarithmic amplifier circuit having the opposite characteristic. The temperature detection circuit described in Patent Document 1 is intended to improve the temperature detection accuracy by correcting the output so that the temperature-voltage characteristic of the thermistor is linear with the above configuration.

Japanese Patent Laid-Open No. 05-282569.

  However, in the temperature detection circuit of the prior art, for the thermistor having a plurality of different characteristics, a different circuit having a characteristic opposite to that of the thermistor must be selected, and there is a problem that versatility is low. Further, the thermistor deteriorates with long-term use, and as a result, when the thermistor characteristics change, there is a problem that output correction cannot be performed accurately.

  In view of the above problems, the temperature detection circuit of the present invention provides a high-accuracy temperature detection circuit that can be used even when temperature detection elements having different characteristics are used and whose accuracy is unlikely to deteriorate even after long-term use. For the purpose.

In order to solve the above problems, the present invention has the following configuration.
The temperature detection circuit according to the invention according to the first aspect is a temperature detection circuit for at least one temperature detection element whose output value changes according to temperature, and outputs an output value from the temperature detection element as the output. A conversion circuit that converts and outputs a first signal having a signal level corresponding to the value; and, based on the first signal, a signal level of the first signal and a signal level of the temperature compensation offset signal A signal indicating the addition result obtained by adding the temperature compensation offset signal corresponding to the signal level of the first signal read from the storage unit storing the correspondence relationship between the first signal and the first signal And an adder circuit for outputting a second signal indicating the level.

  A control device for a temperature detection circuit according to a second aspect of the invention stores a correspondence relationship between the temperature detection circuit and the signal level of the first signal and the signal level of the temperature compensation offset signal. Based on the first signal, the storage unit reads out the signal level of the temperature compensation offset signal corresponding to the signal level of the first signal from the storage unit, and the temperature compensation having the read signal level And a control means for converting the second signal from the temperature detection circuit into corresponding temperature information and outputting it after outputting the offset signal for operation.

  A control device for a temperature detection circuit according to a third aspect of the invention stores the correspondence relationship between the temperature detection circuit and the signal level of the first signal and the signal level of the temperature compensation offset signal. A storage unit and an A / D converter for A / D converting the first signal into a first digital signal for output and A / D converting the second signal into a second digital signal for output A D / A converter that D / A converts the temperature compensation digital offset signal into a temperature compensation offset signal, and outputs the signal level of the first digital signal based on the first digital signal. The signal level of the corresponding temperature compensation offset signal is read from the storage unit, and the temperature compensation digital offset signal having the read signal level is output to the temperature detection circuit via the D / A converter. And then, characterized in that a control means for converting the second digital signal inputted through the A / D converter from the temperature detection circuit to the corresponding temperature information.

  According to a fourth aspect of the present invention, there is provided a control device for a temperature detection circuit, wherein the A / D converter converts the first signal into a first digital signal and outputs the first signal. And a second A / D converter unit that performs A / D conversion of the second signal into a second digital signal and outputs the second digital signal. .

  An electric vehicle according to an invention according to a fifth aspect includes an assembled battery in which at least one secondary battery is connected in series, and at least one of which is disposed in the vicinity of the assembled battery and whose output value changes according to temperature. A temperature detection element and the control device are provided.

  According to the temperature detection circuit of the present invention, it is possible to realize a highly accurate temperature detection circuit that can be used even when temperature detection elements having different characteristics are used, and that accuracy is not easily lowered even after long-term use. There is an advantageous effect.

  DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments that specifically show the best mode for carrying out the present invention will be described below with reference to the drawings.

Embodiment.
With reference to FIGS. 1-5, the electric vehicle provided with the temperature detection circuit which concerns on embodiment is demonstrated. FIG. 1 is a block diagram illustrating a configuration of an electric vehicle including a temperature detection circuit according to the present embodiment. The electric vehicle includes, for example, an electric vehicle (PEV: Pure Electric Vehicle) driven only by a secondary battery, a hybrid vehicle (HEV: Hybrid Electric Vehicle) having an engine and a secondary battery, a fuel cell and a secondary battery. It is a hybrid electric vehicle.

  In FIG. 1, the electric vehicle includes an assembled battery 1, a contactor 2, a contactor 3, a capacitor 4, an inverter 5, a motor generator 6, an engine 7, a cooling fan 8, a temperature detection element 9, and a control unit 10. .

  The assembled battery 1 is configured by connecting a plurality of relatively low voltage secondary batteries in series. The secondary battery is, for example, a sealed nickel hydride battery (nickel metal hydride storage battery) excellent in basic characteristics such as energy density, output density, and cycle life. However, the present invention is not limited to this, and the lithium ion secondary battery is not limited thereto. A nickel cadmium storage battery, a lead storage battery, or the like may be used.

  One end of the contactor 2 is connected to the positive electrode side (high potential side) of the assembled battery 1, and one end of the contactor 3 is connected to the negative electrode side (low potential side) of the assembled battery 1. The contactors 2 and 3 are, for example, contact conduction type switches each having a movable contact and a fixed contact. Each contactor is turned on (conductive state) and off (cut off state) by moving the movable contact under the control of the control unit 10.

  The capacitor 4 is connected between the other end of the contactor 2 and the other end of the contactor 3. Capacitor 4 is provided to suppress fluctuations in the voltage applied to inverter 5 and to supply a stable voltage to motor generator 6.

  The inverter 5 includes a plurality of sets of transistors and diodes. As the transistor, for example, an IGBT (Insulated Gate Bipolar Transistor) capable of high-speed switching can be used. Inverter 5 converts the DC power input from both ends of capacitor 4 into a three-phase AC voltage, and sequentially applies the voltage to each phase of motor generator 6. Thereby, the motor generator 6 is rotationally driven. The inverter 5 is controlled by the control unit 10.

  Motor generator 6 is controlled by a three-phase AC voltage applied from inverter 5. The motor generator 6 is driven to rotate when, for example, a magnet embedded in the rotor is given a rotational force by a voltage applied to the stator coil. The motor generator 6 functions as a three-phase AC generator or a three-phase AC motor. The motor generator 6 charges the assembled battery 1 with the power of the engine 7 while functioning as a generator, and outputs power by consuming electric power supplied from the assembled battery 1 while functioning as an electric motor. . The engine 7 is controlled by the control unit 10.

  The temperature detection element 9 is a thermistor whose resistance value changes with temperature. In the following description of the present embodiment, a thermistor having a negative characteristic is used as the temperature detection element 9. However, the present invention is not limited to this, and a thermistor having a positive characteristic may be used, or another temperature detection element whose output value changes depending on the temperature may be used. The temperature detection element 9 is provided near the assembled battery 1, and the temperature near the assembled battery 1 is detected by the control unit 10. The cooling fan 8 is rotated by the control unit 10 and supplies cooling air to the vicinity of the assembled battery 1 to cool the assembled battery 1.

  The control unit 10 controls the contactors 2 and 3, the inverter 5, the engine 7, the cooling fan 8, and the like according to the operation signal. The operation signal is a signal generated when, for example, an ignition key, an accelerator, a brake, or the like is operated by a driver of the electric vehicle.

Next, with reference to FIG.2 and FIG.3, the control part 10 of the electric vehicle which concerns on this embodiment is demonstrated in detail. FIG. 2 is a block diagram illustrating a detailed configuration of the control unit 10 according to the present embodiment. In FIG. 2, the control unit 10 includes a temperature detection circuit 100, a CPU 101, a storage unit 102, A / D converters 103 and 104, and a D / A converter 105. FIG. 3 is a circuit diagram showing a detailed configuration of the temperature detection circuit 100 of the control unit 10 of the electric vehicle according to the present embodiment. In FIG. 3, the temperature detection circuit 100 includes a reference voltage source V _ref , resistors 1001, 1002, and 1003, and an adder circuit 1004.

In FIG. 3, resistors 1001 and 1002 are serially connected in series between the reference voltage source V _ref and the ground potential. The temperature detection element 9 is connected to the resistor 1002 in parallel. One end of the resistor 1003 is connected to a connection point between the resistors 1001 and 1002, and the other end of the resistor 1003 is connected to one input end of the adder circuit 1004 and the input end of the A / D converter 103. Resistors 1001, 1002 and 1003 is the conversion circuit for converting the resistance value of the temperature detecting element 9 which changes with temperature to an input voltage value _{V in.}

One input terminal of the adder circuit 1004 is connected to the other terminal of the resistor 1003, the other input terminal is connected to the output terminal of the D / A converter 105, and the output terminal is connected to the input terminal of the A / D converter 104. Is done. To one input of the adding circuit 1004, an input voltage value _{V in} is input, the offset voltage _{V ofs} is input to the other input terminal of the adding circuit 1004. From the output terminal of the adder circuit 1004, an output voltage value _Vout, which is the result of the addition of both, is output.

  The adder circuit 1004 includes resistors 1005, 1006, and 1007, and an operational amplifier 1008. In the adding circuit 1004, one end of the resistor 1005 is connected to the other end of the resistor 1003 through one input terminal of the adding circuit 1004, and the other end of the resistor 1005 is connected to a non-inverting input terminal of the operational amplifier 1008. One end of the resistor 1006 is connected to the output end of the D / A converter 105 via the other input end of the adder circuit 1004, and the other end of the resistor 1006 is connected to the other end of the resistor 1005. One end of the resistor 1007 is connected to the other end of the resistor 1005, and the other end of the resistor 1007 is connected to the output end of the operational amplifier 1008. The non-inverting input terminal of the operational amplifier 1008 is connected to the other end of the resistor 1005, the inverting input terminal is connected to the ground potential, and the output terminal is connected to the A / D converter 104 via the output terminal of the adding circuit 1004.

In FIG. 2, A / D converter 103 converts the input voltage value _{V in} is an analog signal inputted from the input terminal into a digital signal, and outputs the CPU 101. The A / D converter 104 converts the output voltage value _Vout , which is an analog signal input from the input terminal, into a digital signal and outputs the digital signal to the CPU 101. The D / A converter 105 converts the offset voltage value V _ofs that is a digital signal input from the CPU 101 into an analog signal, and outputs the analog signal to the other input terminal of the addition circuit 1004.

Input voltage _{V in} from the temperature detection circuit 100 is input to the A / D converter 103 can be expressed by the following formula (1) and (2). In the following equation, the resistance value of the temperature detecting element 9 and _{R th,} the resistance value of the resistor 1001 and _{R 1,} the resistance value of the resistor 1002 and _{R 2,} combined resistance of the temperature sensing element 9 and the resistor 1002 to Z The value of Note that the resistance value _Rth of the temperature detection element 9 changes with a change in temperature in the vicinity of the assembled battery 1, but the resistance values of the other resistors are fixed. Further, since the temperature detecting element 9 is a thermistor having a negative characteristic, as the temperature of the assembled battery 1 near becomes higher, the input voltage value V _in the resistance value R _th is lower lower. As the temperature of the assembled battery 1 near decreases, the resistance value R _th is also higher and higher becomes the input voltage V _in.

[Equation 1]
Z = (R _th · R ₂ ) / (R _th + R ₂ ) (1)
[Equation 2]
V _in = (Z / (Z + R ₁ )) · V _ref (2)

The storage unit 102 stores a function or table indicating a correspondence relationship between the input voltage value V _in and the offset voltage value V _ofs, and a function or table indicating a correspondence relationship between the output voltage value V _out and the temperature T. I remember it as a part. The storage information stored in the storage unit 102 is read or written from the CPU 101 as necessary. In the storage unit 102, a plurality of functions or tables may be stored in advance for each type of the temperature detection element 9.

The CPU 101 controls the contactors 2 and 3, the inverter 5, the engine 7, the cooling fan 8 and the like according to the input operation signal. Further, CPU 101 is a digital signal input from the A / D converter 103, the equation (1) and receives the input voltage _{V in} of the formula (2), corresponding to the input voltage value _{V in} a digital The offset voltage value V _ofs as a signal is read from the storage unit 102. The read offset voltage value V _ofs is output to the D / A converter 105.

The offset voltage value V _ofs is converted into an analog signal by the D / A converter 105 and then input to the other input terminal of the addition circuit 1004 of the temperature detection circuit 100. The adder circuit 1004 adds the input voltage value V _in input to one input terminal and the offset voltage value V _ofs input to the other input terminal, and uses the addition result as an output voltage value V _out for A / D Output to the converter 104. The output voltage value V _out is expressed by the following equation (3). However, at this time, the resistance values of the resistors 1005, 1006, and 1007 are equal.
[Equation 3]
V _out = V _in + V _ofs (3)

Further, the CPU 101 determines the output voltage value V _out and the temperature T stored in the storage unit 102 in accordance with the output voltage value V _out which is a digital signal input from the temperature detection circuit 100 via the A / D converter 104. Is used to calculate the temperature T of the battery pack 1. The CPU 101 controls the cooling fan 8 according to the calculated temperature T of the assembled battery 1. For example, when the temperature T of the assembled battery 1 is higher than a predetermined temperature, the assembled fan 1 is cooled by controlling the cooling fan 8 at a high speed, and when the temperature T of the assembled battery 1 is equal to or lower than the predetermined temperature, the cooling is performed. The fan 8 is controlled to low rotation.

Next, operations in the temperature detection circuit configured as described above will be described with reference to FIGS. Figure 4 is a graph showing an example of a correspondence relationship between the input voltage value V _in stored in the storage unit 102 and the offset voltage value V _ofs. The horizontal axis represents the input voltage value _{V in,} the vertical axis represents the offset voltage value _{V ofs.} Figure 5 is a graph showing the input voltage value V _in and the output voltage value V _out in the case of performing correction based on the correspondence relationship shown in FIG. The horizontal axis represents temperature, and the vertical axis represents voltage.

4, when the value of the input voltage _{V in} is less than _{V a} or more and _{V b,} corresponding offset voltage _{V ofs} is zero, i.e., correction for the input voltage _{V in} is not performed. This is because when the value of the input voltage V _in is less than V _a or more and V _b is the change is relatively large input voltage V _in with a change in temperature of the assembled battery 1 near its remains even sufficient temperature detection This is because accuracy can be obtained. However, if the input voltage V _in is less than V _a, and, when the input voltage value V _in exceeds V _b, the change in the input voltage V _in with a change in temperature of the assembled battery 1 near decreases Therefore, sufficient temperature detection accuracy cannot be obtained. The temperature detection accuracy mentioned here is mainly a reading error at the time of sampling when the A / D converters 103 and 104 convert an analog signal into a digital signal.

Therefore, the corresponding relationship between the input voltage value _{V in} and the offset voltage value _{V ofs} shown in FIG. 4, as the input voltage _{V in} is smaller is smaller than _{V a,} offset voltage _{V ofs} is increased on the negative side, as a result, correction is performed so as to reduce the input voltage V _in. Further, as the input voltage V _in is greater is greater than V _b, the offset voltage V _ofs is increased to the positive side, as a result, correction is performed so as to increase the input voltage V _in.

Based on the correspondence relationship shown in FIG. 4, in the case of correcting the input voltage V _in by the adding circuit 1004, the relationship between the input voltage value V _in and the output voltage value V _out is shown in FIG. Since the corrected output voltage value V _out output from the adder circuit 1004 is not flattened in _a low temperature region lower than the temperature T _a and in a high temperature region higher than the temperature T _b , an analog signal is output from the A / D converter 104. A reading error at the time of sampling when converting to a digital signal is small, and sufficient temperature detection accuracy can be obtained when the temperature T is calculated by the CPU 101.

As described above, by correcting the input voltage V _in prior to be incorporated in the A / D converter 104 to the adder circuit 1004 is provided to the temperature detection circuit 100, the low temperature region and high temperature region, to a digital signal It is possible to suppress a reading error during sampling during conversion.

As the temperature detection element 9, the input if another thermistor having different characteristics are connected, rewrites the correspondence relation between the input voltage value V _in stored in the storage unit 102 and the offset voltage value V _ofs, or in advance a plurality prepared of correspondence between the voltage value V _in and the offset voltage value V _ofs, it is only necessary to select the appropriate configuration of the temperature detection circuit of this embodiment is excellent in versatility. Furthermore, at regular intervals (e.g., about once a year), automatically the correspondence between the input voltage value V _in stored in the storage unit 102 and the offset voltage value V _ofs along aging characteristics of the thermistor By updating, it becomes possible to maintain the accuracy of temperature detection even when the thermistor deteriorates with long-term use, and the reliability is high.

  According to the temperature detection circuit according to the present embodiment, it is possible to realize a highly accurate temperature detection circuit that can be used even when temperature detection elements having different characteristics are used and the accuracy is not easily lowered even when used for a long period of time.

In the electric vehicle of the present embodiment, two A / D converters 103 and 104 are used as A / D converters. However, the present invention is not limited to this configuration, and may be configured to share one A / D converter. In that case, it may be provided a switch for selecting whether to enter one of the input voltages V _in and the output voltage value V _out.

Further, in FIG. 4, when the value of the input voltage V _in is less than V _a or more and V _b, corresponding offset voltage V _ofs is zero, the correction is not performed settings for the input voltage V _in there were. However, the present invention is not limited to this configuration, even if the value of the input voltage V _in is less than V _a or more and V _b, for the purpose of further improving the temperature detection accuracy, a correction to the input voltage value V _in row It may be broken.

  Further, the electric vehicle of the present embodiment has a configuration in which only one temperature detection element 9 is provided. However, the present invention is not limited to this configuration, and a configuration in which a temperature difference in the assembled battery 1 is compensated by using a plurality of temperature detection elements may be used. In this case, for example, by applying the configuration shown in FIG. 6, the same effect as that of the present embodiment can be obtained.

  FIG. 6 is a diagram illustrating a configuration of the control unit 60 when three temperature detection elements 9A, 9B, and 9C are provided. The control unit 60 includes two switches SW1 and SW2 for switching the temperature detection elements 9A, 9B, and 9C connected to the control unit 60. The CPU 601 connects the temperature detection circuit 100 to any one of the temperature detection elements 9A, 9B, and 9C by controlling the switches SW1 and SW2 to be interlocked with each other. The temperature detection operation is as described above. The CPU 601 changes the wind direction of the cooling fan 8 according to the part of the assembled battery 1 where the temperature is high, or each of the parts depending on the part of the assembled battery 1 where the temperature is high by providing a plurality of cooling fans. The cooling fan may be controlled.

  The temperature detection circuit according to the present invention is used as a temperature detection circuit used in an electric vehicle such as an electric vehicle (PEV), a hybrid electric vehicle (HEV), a hybrid electric vehicle having a fuel cell and a secondary battery, for example. Can do.

It is a block diagram which shows the structure of the electric vehicle provided with the temperature detection circuit which concerns on embodiment of this invention. It is a block diagram which shows the detailed structure of the control part of the electric vehicle provided with the temperature detection circuit which concerns on embodiment of this invention. It is a circuit diagram which shows the detailed structure of the temperature detection circuit of the control part of the electric vehicle provided with the temperature detection circuit which concerns on embodiment of this invention. An example of a correspondence between the embodiment the temperature detection input voltage stored in the storage unit of the electric vehicle equipped with a circuit value V _in and the offset voltage value V _ofs according to an embodiment of the present invention is a graph showing. It is a graph showing the input voltage value V _in and the output voltage value V _out in the case of performing correction based on the correspondence relationship shown in FIG. It is a figure which shows another structure of the control part of the electric vehicle provided with the temperature detection circuit which concerns on embodiment of this invention.

Explanation of symbols

1 ... Battery,
2 ... First contactor,
3 ... second contactor,
4 ... Capacitor
5 ... Inverter,
6 ... motor,
8 ... Cooling fan,
9A, 9B, 9C ... temperature detecting element,
10, 60 ... control unit,
100: temperature detection circuit,
101, 601 ... CPU,
102 ... storage part,
103, 104 ... A / D converter,
105 ... D / A converter,
1001, 1002, 1003, 1005, 1006, 1007 ... resistance,
1004 ... Adder circuit,
1008 ... Operational amplifier.

Claims (5)

A temperature detection circuit for at least one temperature detection element whose output value changes according to temperature,
A conversion circuit that converts an output value from the temperature detection element into a first signal having a signal level corresponding to the output value and outputs the first signal;
Based on the first signal, the signal level of the first signal read from the storage unit that stores the correspondence between the signal level of the first signal and the signal level of the offset signal for temperature compensation The temperature compensation offset signal corresponding to the above and the first signal are added, and an addition circuit that outputs a second signal indicating a signal level indicating the addition result is provided. Detection circuit. A temperature detection circuit according to claim 1;
A storage unit for storing a correspondence relationship between the signal level of the first signal and the signal level of the offset signal for temperature compensation;
Based on the first signal, a signal level of the temperature compensation offset signal corresponding to the signal level of the first signal is read from the storage unit, and a temperature compensation offset signal having the read signal level is obtained. And a control means for converting the second signal from the temperature detection circuit into corresponding temperature information and outputting it after output. A temperature detection circuit according to claim 1;
A storage unit for storing a correspondence relationship between the signal level of the first signal and the signal level of the offset signal for temperature compensation;
An A / D converter for A / D converting and outputting the first signal to a first digital signal, and A / D converting the second signal to a second digital signal;
A D / A converter for D / A converting the temperature compensation digital offset signal into a temperature compensation offset signal;
Based on the first digital signal, the signal level of the temperature compensation offset signal corresponding to the signal level of the first digital signal is read from the storage unit, and the temperature compensation digital having the read signal level After the offset signal is output to the temperature detection circuit via the D / A converter, the second digital signal input from the temperature detection circuit via the A / D converter is converted into corresponding temperature information. And a control means for outputting the temperature control circuit. The A / D converter is
A first A / D converter section for A / D converting the first signal into a first digital signal and outputting the first digital signal;
4. The control for a temperature detection circuit according to claim 3, further comprising: a second A / D converter unit that performs A / D conversion on the second signal into a second digital signal and outputs the second digital signal. apparatus. An assembled battery formed by connecting at least one secondary battery in series;
At least one temperature detection element disposed in the vicinity of the assembled battery, the output value of which varies with temperature,
An electric vehicle comprising the control device for a temperature detection circuit according to any one of claims 2 to 4.

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