Motor temperature detection circuit for new energy automobile

Abstract

The utility model 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] This utility model relates to the field of motor temperature detection technology for new energy vehicles, and specifically to a motor temperature detection circuit for new energy vehicles. Background Technology

[0002] For commercially available electric motors, their internal structure mainly consists of two parts: a coil made of enameled wire and a magnet made of magnetic materials. The coil and magnet are crucial for ensuring the motor's normal operation and converting electrical energy into kinetic energy. The enameled wire used to make the coil is usually made by coating bare wire with insulating varnish. This varnish ensures electrical insulation between different numbers of turns of enameled wire wound on the same coil. However, due to its material properties, the insulating varnish can only provide insulation at certain temperatures. When the temperature of the enameled wire exceeds the varnish's temperature resistance point, its insulation performance decreases. Furthermore, as a conductor, the inherent volume resistance of the enameled wire itself generates heat when the motor's operating current flows. When this heat accumulates to a certain level, it risks exceeding the varnish's maximum temperature resistance point, ultimately leading to a decrease in the electrical insulation performance of the enameled wire and a reduction in the withstand voltage between different numbers of turns. In addition, the magnet, another important component of the motor, is usually made of materials such as neodymium iron boron sintered at high temperatures, which inevitably makes it temperature-sensitive. Furthermore, inside the motor, the coil and the magnet are located in the same chamber and are closely adjacent to each other. Therefore, when the enameled wire heats up, it will also transfer heat to the magnet simultaneously, indirectly causing the magnet's temperature to rise. Once the magnet's temperature rises above its temperature resistance point (commonly 150°C), there is a risk of demagnetization, which may even damage the motor.

[0003] To prevent excessively high operating temperatures of the internal coils and magnets of a motor, and to avoid overheating damage, motor manufacturers often install motor temperature sensors in the gaps between the coils. These sensors monitor the internal temperature of the motor in real time and provide temperature sampling signals to the motor temperature detection circuit within the motor controller, enabling the controller to determine and implement over-temperature protection. However, because different manufacturers and even different models of motors use different enameled wires and magnet materials, the temperature rise characteristics and allowable operating temperature ranges of each motor vary. Therefore, to more accurately monitor motor temperature, the temperature sensors installed in different manufacturers and even different models of motors from the same manufacturer may also differ. Common types include PT100, PT1000, NTC, and KTY130 temperature sensors. The PT100 and KTY130 temperature sensors are the most common temperature sensors used in new energy vehicle motors and industrial motors, respectively. Therefore, currently, it is not possible to detect and ensure compatibility between different types of motor temperature sensors. Summary of the Invention

[0004] The purpose of this invention is to provide a motor temperature detection circuit for new energy vehicles.

[0005] To achieve the above objectives, this utility model provides the following technical solution: a motor temperature detection circuit for new energy vehicles, comprising:

[0006] A voltage divider circuit is used to obtain the output voltage value after voltage division.

[0007] A resistor switching circuit is used to switch the series and parallel connections of resistors in a voltage divider circuit, thereby changing the output voltage value of the voltage divider circuit, and then outputting a voltage sampling signal; and

[0008] The operational amplifier circuit amplifies and filters the acquired voltage sampling signal to output the motor temperature processing signal.

[0009] Furthermore, the voltage divider circuit includes ferrite beads L7 and L8, and resistors R237, R238, R223, R31, R33, and R170. One end of ferrite bead L7 is connected to the non-inverting input of the operational amplifier circuit through R170. One end of ferrite bead L8 is connected to the inverting input of the operational amplifier circuit through parallel resistors R31 and R3. One end of resistor R223 is connected between L8 and R31, and the other end is connected between L7 and the operational amplifier circuit. One end of resistors R237 and R238 connected in parallel is connected to resistor R223, and the other end is connected to the inverting input of the operational amplifier circuit.

[0010] Furthermore, the resistor switching circuit includes voltage divider resistors R26, R74, R29, R30, and photorelays U14 and U18. Pin 4 of the photorelay U14 is connected to one end of R74 through voltage divider resistor R26, and the other end of resistor R74 is connected to the voltage divider circuit through parallel R29 and R30. Pin 4 of the photorelay U18 is connected between R74 and R29.

[0011] Further, the operational amplifier circuit includes an operational amplifier U13, resistors R239, R216, R217, R218, R170, R234, R241, and capacitors C131, C130, and C112. Resistors R239 and R216 are connected in series to the inverting input terminal of operational amplifier U13. Resistors R217 and R218 are connected in series to the non-inverting input terminal of operational amplifier U13. Resistors R170 and C131 are connected in parallel between R218 and operational amplifier U13. One end of resistor R241 is connected to the output terminal of operational amplifier U13, and the other end of resistor R241 is connected to capacitor C112. One end of capacitor C130 is connected in parallel with R23 to R216 and operational amplifier U13, and the other end is connected to resistor R241 and operational amplifier U13.

[0012] Furthermore, the resistor switching circuit also includes resistors R122, R124, R125, and R123. One end of resistor R122 is connected to pin 2 of opto-relay U14 through one end of resistor R124, and the other end of resistor R124 is connected to pin 1 of opto-relay U14. One end of resistor R123 is connected to pin 2 of opto-relay U18 through one end of resistor R125, and the other end of resistor R125 is connected to pin 1 of opto-relay U18.

[0013] Furthermore, the optical relays U14 and U18 are model number QX172-CuH-S.

[0014] Furthermore, the operational amplifier U13 is model number TL084QDR.

[0015] As can be seen from the above technical solution, this utility model has the following beneficial effects:

[0016] This motor temperature detection circuit for new energy vehicles consists of three sub-circuits: a voltage divider circuit, a resistor switching circuit, and an operational amplifier circuit. While fulfilling the basic function of motor temperature sampling, it also achieves compatibility and switching between different types of motor temperature sensors. Compatibility between two different types of motor temperature sensors is achieved by adjusting the internal resistance values ​​of the voltage divider circuit and the resistor switching circuit. Attached Figure Description

[0017] Figure 1 This is the overall circuit diagram of this utility model;

[0018] Figure 2 This is the voltage divider circuit diagram of this utility model;

[0019] Figure 3 This is the circuit diagram for the resistor switching of this utility model;

[0020] Figure 4 This is the circuit diagram of the operational amplifier of this utility model. Detailed Implementation

[0021] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the protection scope of the present utility model.

[0022] Please see Figure 1-4This utility model 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 ferrite beads L7 and L8, and resistors R237, R238, R223, R31, R33, and R170. One end of the ferrite bead L7 is connected to the non-inverting input of the operational amplifier circuit through R170. One end of the ferrite bead L8 is connected to the inverting input of the operational amplifier circuit through parallel resistors R31 and R3. 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. One end of the parallel resistors R237 and R238 is connected to resistor R223, and the other end is connected to the inverting input of the operational amplifier circuit.

[0023] Resistors R238, R31, and R33 are used to supply the reference power supply +5V1 (i.e., V). +5V1 After voltage division, the resistors provide a signal input to the inverting input of the operational amplifier circuit. Unlike the resistors that divide the voltage at the non-inverting input, the voltage dividing resistors R238, R31, and R33 at the inverting input all have constant values. Therefore, the voltage signal obtained at the inverting input is also a constant value. This can be used to... Figure 1 The voltage value V at the inverting input terminal of the operational amplifier circuit is calculated. 反相输入 =V +5V1 *{(R31 / / R33) / [R238+(R31 / / R33)]}. Similarly, the remaining voltage divider resistors (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...) connected to PT+ and PT- and filtered by ferrite beads L7 and L8... PT+PT- This can also be considered an equivalent voltage divider resistor, working together with the aforementioned resistors R237, R223, R217, R218, and R170, which have constant resistance values, to divide the voltage. From this, the voltage V at the non-inverting input 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)]}.

[0024] Given the temperature sampling signal R output by the motor temperature sensor PT+PT- It is not a constant value; it changes depending on the type of motor temperature sensor and the motor's operating temperature. Therefore, the final voltage value V at the non-inverting input terminal obtained by voltage division varies. 同相输入 It will also be with R PT+PT-Change. Furthermore, because each motor temperature sensor is manufactured according to standards, the temperature sampling signal (R) output by the same model motor temperature sensor... PT+PT- The variation range and temperature change curve are consistent (e.g., the R value of the PT100 type motor temperature sensor). PT+PT -The range of variation is 82.29Ω~175.84Ω), therefore, the non-inverting input voltage value (V) can be determined from this. 同相输入 The maximum value of (V) 同相输入-max ) and minimum value (V) 同相输入-min ).

[0025] Taking into account the above inverting input voltage value V 反相输入 (Fixed value), maximum voltage value of non-inverting input terminal V 同相输入-max (Constant value) Minimum value V 同相输入-min (Constant value), operational amplifier circuit signal amplification factor (constant value), DSP signal input pin signal maximum value (3V) minimum value (0V), can then be determined based on V 同相输入 The calculation formula determines the constant resistance values ​​of the voltage divider resistors within the aforementioned voltage divider circuit. If the type of motor temperature sensor to be supported changes (i.e., R...) PT+PT -If the range of change changes, then only V above needs to be applied. 同相输入 The calculation formula can be used to maintain V by adjusting the resistance value of the voltage divider resistor within the formula. 同相输入-max V 同相输入-min The process remains unchanged, ultimately achieving the goal of adapting to any type of motor temperature sensor by altering the internal resistance value of the voltage divider circuit.

[0026] The resistor switching circuit includes voltage divider resistors R26, R74, R29, and R30, and photorelays U14 and U18. Pin 4 of photorelay U14 is connected to one end of R74 through voltage divider resistor R26. The other end of resistor R74 is connected to the voltage divider circuit through parallel connections R29 and R30. Pin 4 of photorelay U18 is connected between R74 and R29. The resistor switching circuit also includes resistors R122, R124, R125, and R123. One end of resistor R122 is connected to pin 2 of photorelay U14 through one end of resistor R124. The other end of resistor R124 is connected to pin 1 of photorelay U14. One end of resistor R123 is connected to pin 2 of photorelay U18 through one end of resistor R125. The other end of resistor R125 is connected to pin 1 of photorelay U18. Photorelays U14 and U18 are model number QX172-CuH-S.

[0027] The resistor switching circuit is connected in parallel with the voltage divider circuit, further implementing the resistor switching function based on 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 diagram 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 of the subsequent 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.

[0028] When the resistor switching operation is not performed, the resistor switching control signal MTR_TMP_CTL0 output by the DSP is at a high level of 3.3V. After passing through the current-limiting resistor R122, it indirectly pulls pin 2 of the photorelay U14 up to a high level of 3.3V. Therefore, at this time, the infrared LED on the primary control side of the photorelay U14 is not conducting, meaning that the photoMOSFET on the secondary power side of U14 has no infrared light wave drive signal input. Without a drive signal input, the photoMOSFET is not conducting, and pins 3 and 4 of U14 are in an open circuit state. If pins 3 and 4 of U14 are in an open circuit state, it means that the voltage divider resistor R26 of the resistor switching circuit is not connected to the non-inverting input of the operational amplifier circuit. That is, R26 and the voltage divider resistor R237 of the voltage divider circuit are not in parallel, and R26 has no effect on the role of R237 in the voltage divider circuit.

[0029] Conversely, if the resistor switching operation is in progress, the resistor switching control signal MTR_TMP_CTL0 output by the DSP will be at a low level of 0V. At this time, the infrared LED on the primary control side of the photorelay U14 is turned on and generates an infrared light wave signal. The power-side photoMOSFET receives this infrared light wave drive signal and turns on, causing pins 3 and 4 of U14 to be in a conducting state. This connects the voltage divider resistor R26 in the resistor switching circuit to the non-inverting input of the operational amplifier circuit, i.e., connecting resistor R26 in parallel with the voltage divider resistor R237. Based on the formula for calculating the non-inverting input voltage V of the operational amplifier circuit, Vinverting can be calculated when the resistor switching operation is in progress. 同相输入 = V +5V1 *[R PT+PT - / / R223 / / (R217+R218+R170)] / {R237 / / R26+[(R PT+PT - / / R223 / / (R217+R218+R170)]}.

[0030] Similarly, if the other photorelay U18 in the resistor switching circuit is in the resistor switching operation state, the resistor switching control signal MTR_TMP_CTL1 output by the DSP will also be at a low level of 0V, thus making pins 3 and 4 of U18 in a conducting state. This connects the voltage divider resistors R74, R29, and R30 in the resistor switching circuit to the inverting input of the operational amplifier circuit. That is, resistor R74 is connected in parallel with the voltage divider resistor R238 in the voltage divider circuit, and resistors R29 and R30 are connected in parallel with the voltage divider resistors R31 and R33 in the voltage divider circuit. Then, based on the voltage value V at the inverting input of the operational amplifier circuit... 反相输入 The calculation formula can be used to calculate V when the resistance switching operation is performed. 反相输入 =V +5V1 *{(R31 / / R33 / / R29 / / R30) / [R238 / / R74+ (R31 / / R33 / / R29 / / R30)]}.

[0031] In summary, by controlling the opto-relays U14 and U18 via software instructions issued by the DSP (i.e., resistor switching control signals MTR_TMP_CTL0 and MTR_TMP_CTL1), the series-parallel connection configuration between the internal resistors of the voltage divider circuit and the internal resistors of the resistor switching circuit can be changed. This ensures that, without altering the resistance values ​​within the aforementioned circuits, the signal difference (i.e., V0) between the non-inverting and inverting inputs of the operational amplifier circuit is maintained after switching the type of the electrical temperature sensor. 同相输入 -V 反相输入 This means ensuring that the final output range of the operational amplifier circuit matches the value before the motor temperature sensor type was switched. Ultimately, this allows for software control and switching of the currently supported temperature sensor type.

[0032] The operational amplifier circuit includes operational amplifier U13, resistors R239, R216, R217, R218, R170, R234, R241, and capacitors C131, C130, and C112. The operational amplifier U13 is a TL084QDR. Resistors R239 and R216 are connected in series to the inverting input terminal of operational amplifier U13. Resistors R217 and R218 are connected in series to the non-inverting input terminal of operational amplifier U13. Resistors R170 and C131 are connected in parallel between R218 and operational amplifier U13. One end of resistor R241 is connected to the output terminal of operational amplifier U13, and the other end of resistor R241 is connected to capacitor C112. Capacitor C130 is connected in parallel with R23, with one end connected between R216 and operational amplifier U13, and the other end connected between resistor R241 and operational amplifier U13.

[0033] Resistors R234, R239, R216, R217, and R218 are used to adjust the signal amplification factor of the operational amplifier circuit, while 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 sampled signal received at the input of this operational amplifier circuit. Resistor R241 and capacitor C112 perform RC filtering on the signal output from the output of this operational amplifier processing circuit.

[0034] Once the signals at the non-inverting and inverting input terminals of the operational amplifier circuit are transmitted to this 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)]. V MTE_TMP_AD This refers to the final motor temperature processing signal that this motor temperature detection solution will output to the DSP. Based on this, the operational amplifier circuit outputs signal V. MTE_TMP_AD The DSP can then perform subsequent corresponding operations such as displaying the motor temperature value or executing the motor over-temperature protection operation.

[0035] This circuit, using a voltage divider circuit, a resistor switching circuit, and an operational amplifier circuit, takes the simultaneous support of PT100 and KTY130 temperature sensors as an example. The temperature sampling signal output by the internal temperature sensor of the motor is generated by... Figure 1 The PT+ and PT- networks are connected to this temperature detection circuit. The temperature sampling signal is filtered by ferrite beads and then transmitted to the subsequent voltage divider circuit. In the voltage divider circuit, the temperature sampling signal can be considered equivalent to one of the voltage divider resistors, which, together with the other voltage divider resistors with constant resistance, perform the voltage division function. In addition to the voltage divider resistors, the voltage divider circuit also includes a reference power supply (i.e., +5V1). The reference power supply, after being divided by the voltage divider resistors, can be used as the specific voltage input to the non-inverting and inverting input terminals of the subsequent operational amplifier circuit. The resistor switching circuit composed of opto-relays is responsible for switching the series and parallel combination of the voltage divider resistors according to software instructions. By using different series and parallel combinations of voltage divider resistors, the circuit aims to adapt to the corresponding motor temperature sensor type and its output temperature sampling signal. After receiving the specific voltage value input generated by the voltage divider resistors and the reference power supply based on the corresponding temperature sampling signal, the operational amplifier circuit will amplify the voltage value by a certain factor before transmitting it to the DSP for processing. The above describes the implementation process of the motor temperature sampling function in this solution. The voltage divider circuit enables support for any two types of temperature sensors, while the resistor switching circuit enables software control and switching of the currently supported temperature sensor types.

[0036] Although embodiments of the present invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the present invention, the scope of which 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 the output voltage value after voltage division. A resistor switching circuit is used to switch the series and parallel connections of resistors in a voltage divider circuit to change the output voltage value of the voltage divider circuit, and then output a voltage sampling signal. as well as The operational amplifier circuit amplifies and filters the acquired voltage sampling signal to output the motor temperature processing signal. The resistor switching circuit includes voltage divider resistors R26, R74, R29, R30, and photorelays U14 and U18. Pin 4 of the photorelay U14 is connected to one end of R74 through voltage divider resistor R26. The other end of resistor R74 is connected to the voltage divider circuit through parallel R29 and R30. Pin 4 of the photorelay U18 is connected between R74 and R29. The resistor switching circuit further includes resistors R122, R124, R125, and R123. One end of resistor R122 is connected to pin 2 of opto-relay U14 through one end of resistor R124, and the other end of resistor R124 is connected to pin 1 of opto-relay U14. One end of resistor R123 is connected to pin 2 of opto-relay U18 through one end of resistor R125, and the other end of resistor R125 is connected to pin 1 of opto-relay U18. The resistor switching circuit also includes resistors R122, R124, R125, and R123. One end of resistor R122 is connected to pin 2 of opto-relay U14 through one end of resistor R124, and the other end of resistor R124 is connected to pin 1 of opto-relay U14. One end of resistor R123 is connected to pin 2 of opto-relay U18 through one end of resistor R125, and the other end of resistor R125 is connected to pin 1 of opto-relay U18. The opto-relays U14 and U18 are of model number QX172-CuH-S. 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 of the subsequent operational amplifier circuit. Pin 4 is connected to the voltage divider resistor R26 of the resistor switching circuit and the reference power supply +5V1.

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

3. 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, and capacitors C131, C130, and C112. Resistors R239 and R216 are connected in series to the inverting input terminal of operational amplifier U13. Resistors R217 and R218 are connected in series to the non-inverting input terminal of operational amplifier U13. Resistors R170 and C131 are connected in parallel between R218 and operational amplifier U13. One end of resistor R241 is connected to the output terminal of operational amplifier U13, and the other end of resistor R241 is connected to capacitor C112. One end of capacitor C130 is connected in parallel between R216 and operational amplifier U13, and the other end is connected between resistor R241 and operational amplifier U13.

4. The motor temperature detection circuit for new energy vehicles according to claim 1, characterized in that: The photoresistors U14 and U18 are model number QX172-CuH-S.

5. A motor temperature detection circuit for new energy vehicles according to claim 3, characterized in that: The operational amplifier U13 is model number TL084QDR.

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