Motor temperature detection circuit for new energy automobile

Abstract

The invention discloses a motor temperature detection circuit for a new energy automobile, and the circuit comprises a voltage division circuit which is used for obtaining a voltage, carrying out the voltage division, and outputting a voltage value; the resistor switching circuit is used for switching to change the voltage value output by the voltage division circuit after being connected in parallel with the resistor of the voltage division circuit, and then outputting a voltage sampling signal; and the operational amplification circuit is used for amplifying and filtering the acquired voltage sampling signal and outputting a motor temperature processing signal. According to the motor temperature detection circuit for the new energy automobile, through the voltage division circuit, the resistance switching circuit and the operation amplification circuit, the basic function of motor temperature sampling is achieved, and meanwhile detection compatibility and switching of different types of motor temperature sensors are achieved. Detection compatibility of two different types of motor temperature sensors is realized by adjusting internal resistance values of the voltage division circuit and the resistance switching circuit.

Description

Technical Field

[0001] The present invention relates to the technical field of motor temperature detection for new energy vehicles, and in particular to a motor temperature detection circuit for new energy vehicles. Background Art

[0002] For the motors on the market, their interior is mainly composed of two parts: the wire package made of enameled wire and the magnetic steel made of magnetic material. The wire package and the magnetic steel are the key to ensure the normal operation of the motor and convert electrical energy into kinetic energy. Among them, the enameled wire wound into the wire package is usually made by applying insulating paint on the bare wire. The insulating paint can ensure the mutual electrical insulation between the enameled wires with different turns wound on the same wire package. However, due to its material properties, the insulating paint can only play an insulating role at a certain temperature. When the temperature of the enameled wire exceeds the temperature resistance point of the insulating paint, its insulation performance will decrease. As a conductor, the inherent body resistance of the enameled wire itself will cause it to generate a certain amount of heat when the working current of the motor flows through it. When the heat accumulates to a certain extent, there is a risk of exceeding the highest temperature resistance point of the insulating paint, which ultimately leads to a decrease in the electrical insulation performance of the enameled wire and a decrease in the withstand voltage strength between enameled wires with different turns. In addition, the magnetic steel, another important component of the motor, is usually sintered at high temperature by materials such as neodymium iron boron, which inevitably makes it also have temperature-sensitive characteristics. Furthermore, inside the motor, the wire package and the magnet are in the same chamber and are closely adjacent to each other. Therefore, when the enameled wire is heated, it will also transfer heat to the magnet, which will indirectly cause the temperature of the magnet to rise. Once the temperature of the magnet rises above its temperature resistance point (usually 150°C), there is a risk of demagnetization, which may even cause damage to the motor.

[0003] In order to prevent the internal winding and magnetic steel of the motor from working at too high a temperature and to avoid overheating and damage to the motor, motor manufacturers often install motor temperature sensors in the gaps between the windings inside the motor. The motor temperature sensor can detect the internal temperature of the motor in real time, and provide a temperature sampling signal to the motor temperature detection circuit in the motor controller so that the controller can determine and execute motor overtemperature protection. However, because the enameled wire and magnetic steel materials used by different manufacturers and different models of motors from the same manufacturer are different, the temperature rise characteristics and allowable operating temperature ranges of each motor are also different. Therefore, in order to monitor the motor temperature more accurately, the temperature sensors installed in motors of different manufacturers and different models of the same manufacturer may also be different. Common ones are PT100, PT1000, NTC, and KTY130 temperature sensors. Among them, PT100 temperature sensors and KTY130 temperature sensors are the most common temperature sensors in new energy vehicle motors and industrial motors, respectively. Therefore, it is currently impossible to detect and be compatible with different types of motor temperature sensors. Summary of the invention

[0004] The object of the present invention is to provide a motor temperature detection circuit for new energy vehicles.

[0005] To achieve the above object, the present invention provides the following technical solution: a motor temperature detection circuit for a new energy vehicle, comprising: A voltage divider circuit is used to obtain a voltage and then divide it to output a voltage value; A resistor switching circuit, used for switching the resistors in series and parallel with the voltage divider circuit to change the voltage value output by the voltage divider circuit, and then output a voltage sampling signal; and The operational amplifier circuit obtains the voltage sampling signal, amplifies and filters it, and outputs the motor temperature processing signal.

[0006] Furthermore, the voltage divider circuit includes magnetic beads L7, L8, resistors R237, R238, R223, R31, R33, and R170, one end of the magnetic bead L7 is connected to the non-inverting input terminal of the operational amplifier circuit through R170, one end of the magnetic bead L8 is connected to the inverting input terminal of the operational amplifier circuit through R31 and R3 in parallel, one end of the resistor R223 is connected between L8 and R31, and the other end is connected between L7 and the operational amplifier circuit, and after the resistor R237 and R238 are connected in parallel, one end is connected to the resistor R223, and the other end is connected to the inverting input terminal of the operational amplifier circuit.

[0007] Furthermore, the resistance switching circuit includes voltage-dividing resistors R26, R74, R29, R30, photorelays U14 and U18, pin 4 of the photorelay U14 is connected to one end of R74 through the voltage-dividing resistor R26, the other end of the resistor R74 is connected to the voltage-dividing circuit through R29 and R30 connected in parallel, and pin 4 of the photorelay U18 is connected between R74 and R29.

[0008] Furthermore, the operational amplifier circuit includes an operational amplifier U13, resistors R239, R216, R217, R218, R170, R234, R241, capacitors C131, C130, and C112. The resistors R239 and R216 are connected in series and connected to the inverting input terminal of the operational amplifier U13. The resistors R217 and R218 are connected in series and connected to the non-inverting input terminal of the operational amplifier U13. The resistor R170 and C131 are connected in parallel and connected between R218 and the operational amplifier U13. One end of the resistor R241 is connected to the output terminal of the operational amplifier U13, and the other end of the resistor R241 is connected to the capacitor C112. After the capacitor C130 and R23 are connected in parallel, one end is connected between R216 and the operational amplifier U13, and the other end is connected between the resistor R241 and the operational amplifier U13.

[0009] Furthermore, the resistance switching circuit also includes resistors R122, R124, R125, and R123, one end of the resistor R122 is connected to pin 2 of the photorelay U14 through one end of the resistor R124, the other end of the resistor R124 is connected to pin 1 of the photorelay U14, one end of the resistor R123 is connected to pin 2 of the photorelay U18 through one end of the resistor R125, and the other end of the resistor R125 is connected to pin 1 of the photorelay U18.

[0010] Furthermore, the models of the optical relay U14 and the optical relay U18 are QX172-CuH-S.

[0011] Furthermore, the operational amplifier U13 has a model of TL084QDR.

[0012] It can be seen from the above technical solution that the present invention has the following beneficial effects: The motor temperature detection circuit for new energy vehicles uses three sub-circuits: voltage divider circuit, resistor switching circuit, and operational amplifier circuit. While meeting the basic function of motor temperature sampling, it also realizes detection compatibility and switching of different types of motor temperature sensors. The detection compatibility of two different types of motor temperature sensors is achieved by adjusting the internal resistance value of the voltage divider circuit and resistor switching circuit. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 It is the overall circuit diagram of the present invention; Figure 2 This is a voltage divider circuit diagram of the present invention; Figure 3 This is a resistance switching circuit diagram of the present invention; Figure 4 This is the operational amplifier circuit diagram of the present invention. DETAILED DESCRIPTION

[0014] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0015] See also Figure 1-4The present invention provides a motor temperature detection circuit for new energy vehicles, including a voltage divider circuit, a resistor switching circuit and an operational amplifier circuit. The voltage divider circuit includes magnetic beads L7, L8, resistors R237, R238, R223, R31, R33, and R170. One end of the magnetic bead L7 is connected to the non-inverting input end of the operational amplifier circuit through R170, one end of the magnetic bead L8 is connected to the inverting input end of the operational amplifier circuit through R31 and R3 connected in parallel, one end of the resistor R223 is connected between L8 and R31, and the other end is connected between L7 and the operational amplifier circuit. After the resistor R237 and R238 are connected in parallel, one end is connected to the resistor R223, and the other end is connected to the inverting input end of the operational amplifier circuit.

[0016] Resistors R238, R31, and R33 are used to connect the reference power supply +5V1 (i.e. V +5V1 ) is used to divide the voltage for the inverting input of the operational amplifier circuit. Different from the resistors that divide the voltage at the non-inverting input, the resistors R238, R31, and R33 used for voltage division at the inverting input are all constant values, so the voltage signal obtained at the inverting input is also a constant value. Figure 1 The calculated voltage value V at the inverting input terminal of the operational amplifier circuit is 反相输入 =V +5V1 *{(R31 / / R33) / [ R238+(R31 / / R33)]}. Similarly, the remaining voltage-dividing resistors in the voltage-dividing circuit (i.e. R237, R223, R217, R218, R170) are also used to divide the reference power supply +5V1, thus serving as the signal input to the non-inverting input of the operational amplifier circuit. However, unlike the resistors that divide the voltage at the inverting input, the temperature sampling signal (i.e. R PT+PT- ) can also be equivalent to a voltage-dividing resistor, which plays a voltage-dividing role together with the above-mentioned constant resistance R237, R223, R217, R218, and R170. From this, the voltage value V at the non-inverting input terminal of the operational amplifier circuit can be calculated. 同相输入 = V +5V1 *[R PT+PT - / / R223 / / (R217+R218+R170)] / {R237+[(R PT+PT - / / R223 / / (R217+R218+R170)]}.

[0017] Given that the temperature sampling signal R output by the motor temperature sensor PT+PT- It is not a constant value. It will change with the change of the motor temperature sensor type and the motor operating temperature. Therefore, the final voltage value V obtained by voltage division is 同相输入 Also with R PT+PT-Because each motor temperature sensor is made according to the standard, the temperature sampling signal (R PT+PT- ) The change range and its temperature change curve are consistent (such as the R of the PT100 motor temperature sensor PT+PT -The range is 82.29Ω~175.84Ω, so the voltage value of the common-mode input terminal (V 同相输入 ) maximum value (V 同相输入-max ) and minimum value (V 同相输入-min ).

[0018] Considering the above inverting input voltage value V 反相输入 (fixed value), maximum voltage value of the same-phase input terminal V 同相输入-max (fixed value) minimum value V 同相输入-min (fixed value), operational amplifier circuit signal amplification factor (fixed value), DSP signal input pin signal input maximum value (3V) minimum value (0V), then according to V 同相输入 The calculation formula determines the resistance of the voltage divider resistors with constant resistance in the above voltage divider circuit. PT+PT -change range), then only the above V 同相输入 Calculate the formula and adjust the resistance of the voltage divider resistor in the formula to maintain V 同相输入-max 、V 同相输入-min The purpose of adapting any type of motor temperature sensor to the voltage divider circuit is ultimately achieved by changing the internal resistance value of the voltage divider circuit.

[0019] The resistance switching circuit includes voltage-dividing resistors R26, R74, R29, R30, photorelays U14 and U18. Pin 4 of the photorelay U14 is connected to one end of R74 through the voltage-dividing resistor R26, and the other end of the resistor R74 is connected to the voltage-dividing circuit through R29 and R30 connected in parallel. Pin 4 of the photorelay U18 is connected between R74 and R29. The resistance switching circuit also includes resistors R122, R124, R125 and R123. One end of the resistor R122 is connected to pin 2 of the photorelay U14 through one end of the resistor R124, and the other end of the resistor R124 is connected to pin 1 of the photorelay U14. One end of the resistor R123 is connected to pin 2 of the photorelay U18 through one end of the resistor R125, and the other end of the resistor R125 is connected to pin 1 of the photorelay U18. The models of the photorelays U14 and U18 are QX172-CuH-S.

[0020] The resistor switching circuit is connected in parallel with the voltage divider circuit to further realize the resistor switching function on the basis of the voltage divider circuit. The photorelay, as the core component, is responsible for performing the specific resistor switching operation in this circuit. As shown in the figure above, pin 1 of the photorelay U14 is a 3.3V high-level input, pin 2 is connected to the resistor switching control signal MTR_TMP_CTL0 output by the DSP through the current limiting resistor R122, pin 3 is directly connected to the non-inverting input terminal of the post-stage operational amplifier circuit, and pin 4 is connected to the voltage divider resistor R26 of the resistor switching circuit and the reference power supply +5V1.

[0021] When the resistor switching operation is not performed, the resistor switching control signal MTR_TMP_CTL0 output by the DSP is a 3.3V high level, and the pin 2 of the photorelay U14 is also pulled up to a 3.3V high level after passing through the current limiting resistor R122. Therefore, at this time, the infrared light-emitting diode on the primary control side of the photorelay U14 is not turned on, that is, the photo MOSFET on the secondary power side of the internal U14 has no infrared light wave drive signal input. Without the drive signal input, the photo MOSFET is not turned on, and the 3rd and 4th pins of U14 are in an open circuit state. If the 3rd and 4th pins of U14 are in an open circuit state, it means that the voltage divider resistor R26 of the resistor switching circuit cannot be connected to the in-phase input terminal of the operational amplifier circuit, that is, R26 and the voltage divider resistor R237 of the voltage divider circuit are in a non-parallel state, and R26 has no effect on the role of R237 in the voltage divider circuit.

[0022] On the contrary, if the resistor switching operation is executed, the resistor switching control signal MTR_TMP_CTL0 output by the DSP is 0V low level. At this time, the infrared light emitting diode on the primary control side of the photorelay U14 is turned on and generates an infrared light wave signal. After receiving the infrared light wave drive signal, the optical MOSFET on the power side drives the optical MOSFET to turn on, so that pins 3 and 4 of U14 are in the on state, thereby connecting the voltage divider resistor R26 in the resistor switching circuit to the non-inverting input terminal of the operational amplifier circuit, that is, connecting the resistor R26 in parallel with the voltage divider resistor R237 of the voltage divider circuit. According to the calculation formula of the voltage value V non-inverting input terminal of the operational amplifier circuit, it can be calculated that V 同相输入 = V +5V1 *[R PT+PT - / / R223 / / (R217+R218+R170)] / {R237 / / R26+[(R PT+PT - / / R223 / / (R217+R218+R170)]}.

[0023] Similarly, if another photorelay U18 in the resistor switching circuit is in the state of executing the resistor switching operation, the resistor switching control signal MTR_TMP_CTL1 output by the DSP is also 0V low level, so that the 3rd and 4th pins of U18 are in the on state, thereby connecting the voltage-dividing resistors R74, R29, and R30 in the resistor switching circuit to the inverting input terminal of the operational amplifier circuit. That is, the resistor R74 is connected in parallel with the voltage-dividing resistor R238 of the voltage-dividing circuit, and the resistors R29 and R30 are connected in parallel with the voltage-dividing resistors R31 and R33 in the voltage-dividing circuit. Then according to the voltage value V at the inverting input terminal of the above-mentioned operational amplifier circuit 反相输入 The calculation formula can be used to calculate V under the state of performing resistance switching operation. 反相输入 =V +5V1 *{(R31 / / R33 / / R29 / / R30) / [R238 / / R74+ (R31 / / R33 / / R29 / / R30)]}.

[0024] In summary, the photorelays U14 and U18 controlled by the software instructions (i.e., the resistance switching control signals MTR_TMP_CTL0 and MTR_TMP_CTL1) issued by the DSP can realize the change of the series-parallel connection between the internal resistors of the voltage divider circuit and the internal resistors of the resistance switching circuit. Thus, without changing the resistance values ​​of the resistors in the above circuit, the signal difference (i.e., V 同相输入 -V 反相输入 ), that is, the final output range value of the operational amplifier circuit is consistent with the motor temperature sensor type before switching. And finally, the purpose of switching the currently supported temperature sensor type through software control is achieved.

[0025] The operational amplifier circuit includes an operational amplifier U13, resistors R239, R216, R217, R218, R170, R234, R241, capacitors C131, C130, and C112. The model of the operational amplifier U13 is TL084QDR. The resistors R239 and R216 are connected in series and connected to the inverting input terminal of the operational amplifier U13. The resistors R217 and R218 are connected in series and connected to the non-inverting input terminal of the operational amplifier U13. The resistor R170 is connected in parallel with C131 and connected between R218 and the operational amplifier U13. One end of the resistor R241 is connected to the output terminal of the operational amplifier U13, and the other end of the resistor R241 is connected to the capacitor C112. After the capacitor C130 is connected in parallel with R23, one end is connected between R216 and the operational amplifier U13, and the other end is connected between the resistor R241 and the operational amplifier U13.

[0026] Resistors R234, R239, R216, R217, and R218 are used to adjust the signal amplification factor of the operational amplifier circuit, and capacitor C130 is used to adjust the negative feedback speed of the operational amplifier. Resistor R170 and capacitor C131 together form a second-order active filter to filter the sampling signal received at the input end of the operational amplifier circuit. Resistor R241 and capacitor C112 perform RC filtering on the signal output from the output end of the operational amplifier processing circuit.

[0027] When the signals at the non-inverting input and inverting input of the operational amplifier circuit are transmitted to the operational amplifier circuit, the output value V of the operational amplifier circuit can be calculated according to the formula: MTE_TMP_AD = (V 同相输入 -V 反相输入 )*[R234 / (R239+R215)]. MTE_TMP_AD That is, the motor temperature processing signal that the motor temperature detection solution ultimately outputs and supplies to the DSP. MTE_TMP_AD , DSP can then perform the corresponding subsequent motor temperature value display operation or motor over-temperature protection execution operation.

[0028] This circuit uses a voltage divider circuit, a resistor switching circuit and an operational amplifier circuit to support both PT100 and KTY130 temperature sensors. The temperature sampling signal output by the motor internal temperature sensor is Figure 1 The PT+ and PT- networks in the temperature detection circuit are connected to the temperature detection circuit. The temperature sampling signal is transmitted to the subsequent voltage divider circuit after being filtered by magnetic beads. In the voltage divider circuit, the temperature sampling signal can be equivalent to one of the voltage divider resistors, which plays a voltage divider role together with the other voltage divider resistors with constant resistance inside the circuit. In addition to the voltage divider resistor, the voltage divider circuit also includes a reference power supply (i.e. +5V1). After the reference power supply is divided by the voltage divider resistor, it can be used as a specific voltage value input of the in-phase input terminal and the inverting input terminal of the subsequent operational amplifier circuit. The resistor switching circuit composed of the photorelay is responsible for switching the series-parallel combination form between the voltage divider resistors according to the software instructions. Through different series-parallel combinations of voltage divider resistors, the purpose of adapting the corresponding motor temperature sensor type and its output temperature sampling signal is achieved. After receiving the specific voltage value input generated by the voltage divider resistor and the reference power supply according to the corresponding temperature sampling signal, the operational amplifier circuit will amplify the voltage value by a certain multiple so that it can be transmitted to the DSP for processing. The above is the implementation process of the motor temperature sampling function of this solution, in which the voltage divider circuit supports any two types of temperature sensors, and the resistor switching circuit realizes software control and switching of the currently supported temperature sensor types.

[0029] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A motor temperature detection circuit for new energy vehicles, characterized in that: include: A voltage divider circuit is used to obtain a voltage and then divide it to output a voltage value; A resistor switching circuit is used to switch the resistors in series and parallel with the voltage divider circuit to change the voltage value output by the voltage divider circuit, and then output a voltage sampling signal; as well as The operational amplifier circuit obtains the voltage sampling signal, amplifies and filters it, and outputs the motor temperature processing signal.

2. A motor temperature detection circuit for new energy vehicles according to claim 1, characterized in that: The voltage divider circuit includes magnetic beads L7, L8, resistors R237, R238, R223, R31, R33, and R170. One end of the magnetic bead L7 is connected to the non-inverting input end of the operational amplifier circuit through R170, one end of the magnetic bead L8 is connected to the inverting input end of the operational amplifier circuit through R31 and R3 connected in parallel, one end of the resistor R223 is connected between L8 and R31, and the other end is connected between L7 and the operational amplifier circuit. After the resistor R237 and R238 are connected in parallel, one end is connected to the resistor R223, and the other end is connected to the inverting input end of the operational amplifier circuit.

3. The motor temperature detection circuit for new energy vehicles according to claim 1 is characterized in that: The resistance switching circuit includes voltage-dividing resistors R26, R74, R29, R30, photorelays U14 and U18. Pin 4 of the photorelay U14 is connected to one end of R74 via the voltage-dividing resistor R26, and the other end of the resistor R74 is connected to the voltage-dividing circuit via R29 and R30 connected in parallel. Pin 4 of the photorelay U18 is connected between R74 and R29.

4. The motor temperature detection circuit for new energy vehicles according to claim 1, characterized in that: The operational amplifier circuit includes an operational amplifier U13, resistors R239, R216, R217, R218, R170, R234, R241, capacitors C131, C130, and C112. The resistors R239 and R216 are connected in series and connected to the inverting input terminal of the operational amplifier U13. The resistors R217 and R218 are connected in series and connected to the non-inverting input terminal of the operational amplifier U13. The resistor R170 and C131 are connected in parallel and connected between R218 and the operational amplifier U13. One end of the resistor R241 is connected to the output terminal of the operational amplifier U13, and the other end of the resistor R241 is connected to the capacitor C112. The capacitor C130 and R23 are connected in parallel and one end is connected between R216 and the operational amplifier U13, and the other end is connected between the resistor R241 and the operational amplifier U13.

5. The motor temperature detection circuit for new energy vehicles according to claim 3 is characterized in that: The resistance switching circuit also includes resistors R122, R124, R125, and R123. One end of the resistor R122 is connected to pin 2 of the photorelay U14 through one end of the resistor R124, and the other end of the resistor R124 is connected to pin 1 of the photorelay U14. One end of the resistor R123 is connected to pin 2 of the photorelay U18 through one end of the resistor R125, and the other end of the resistor R125 is connected to pin 1 of the photorelay U18.

6. A motor temperature detection circuit for new energy vehicles according to claim 3, characterized in that: The models of the photorelay U14 and the photorelay U18 are QX172-CuH-S.

7. The motor temperature detection circuit for new energy vehicles according to claim 5, characterized in that: The model of the operational amplifier U13 is TL084QDR.

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