Demagnetization protection circuit and compressor

Abstract

The invention discloses a demagnetization protection circuit and a compressor. The demagnetization protection circuit comprises a driving chip, a reference voltage generation circuit and an acquisition circuit, wherein the driving chip is used for driving equipment with a permanent magnet material; the reference voltage generation circuit is used for acquiring the operating temperature of the equipment with the permanent magnet material and converting the operating temperature into reference voltage; the acquisition circuit is used for acquiring the operating current of the equipment with the permanent magnet material and converting the operating current into output voltage; the comparison circuit is used for generating a trigger signal capable of representing whether the equipment with the permanent magnet material has a demagnetization risk or not according to the reference voltage and the output voltage; and the driving chip can receive the trigger signal and drive the equipment with the permanent magnet material to stop when the equipment with the permanent magnet material has a demagnetization risk. Compared with the prior art, the demagnetization protection threshold value can be dynamically adjusted according to different operation temperatures, performance waste caused by fixed demagnetization protection threshold value limitation can be avoided, the compressor can output higher operation current under the normal working condition, and the overall performance is improved.

Description

Technical Field

[0001] This invention relates to the field of compressor control, and in particular to a demagnetization protection circuit and a compressor. Background Technology

[0002] In the drive systems of motors or compressors, permanent magnets may demagnetize when subjected to transient high-current surges, leading to a decrease in their magnetic properties. This, in turn, reduces the output performance of the motor or compressor, or even causes it to malfunction. Once demagnetized, the magnetic properties of permanent magnets cannot be restored, potentially resulting in equipment malfunction and economic losses.

[0003] The demagnetizing critical current value of permanent magnets is closely related to temperature; generally, permanent magnets are more prone to demagnetization in low-temperature environments. Existing demagnetization protection circuits typically use a fixed demagnetizing current threshold, set as the critical demagnetizing current under the lowest operating temperature condition of the equipment. While this design provides effective protection under low-temperature conditions, it limits the operating current output within the normal operating temperature range, causing the motor or compressor to not fully utilize its rated performance. This results in a fixed demagnetizing current threshold that is difficult to dynamically adjust based on the permanent magnet's operating temperature, impacting equipment performance and operating efficiency.

[0004] Therefore, how to design a demagnetization protection circuit and compressor that can dynamically adjust the demagnetization current threshold according to the operating temperature is a technical problem that the industry urgently needs to solve. Summary of the Invention

[0005] In view of the problem that the demagnetizing current threshold is set in a fixed manner in the existing technology, and it is difficult to dynamically adjust it according to the operating temperature of the permanent magnet, which affects the performance and operating efficiency of the equipment, this invention proposes a demagnetizing protection circuit and compressor.

[0006] The technical solution of the present invention is to propose a demagnetization protection circuit, including a driving chip for driving a device with permanent magnet material, a reference voltage generation circuit for collecting the operating temperature of the device with permanent magnet material and converting it into a reference voltage, a collection circuit for collecting the operating current of the device with permanent magnet material and converting it into an output voltage, and a comparison circuit for generating a trigger signal that characterizes whether the device with permanent magnet material has a risk of demagnetization based on the reference voltage and the output voltage.

[0007] The drive chip can receive the trigger signal and drive the device with permanent magnet material to stop when there is a risk of demagnetization.

[0008] Furthermore, the reference voltage generation circuit includes a temperature sensor for acquiring the operating temperature, a digital signal processor for converting the operating temperature into a digital signal corresponding to the reference voltage, and an output circuit for converting the digital signal into a reference voltage for output.

[0009] Furthermore, the calculation model for the reference voltage is as follows:

[0010]

[0011] in, The operating temperature, The reference voltage for the operating temperature. For operating temperature is The reference voltage at that time This is the compensation coefficient.

[0012] Furthermore, the output circuit includes: amplifier U1, resistor R5, resistor R6, capacitor C2, and capacitor C3;

[0013] The non-inverting input terminal of the amplifier U1 is connected in series with the resistors R6 and R5 to serve as the input terminal of the output circuit and is connected to the digital signal. The output terminal of the amplifier U1 serves as the output terminal of the reference voltage generation circuit and outputs the reference voltage. The inverting input terminal of the amplifier U1 is connected to the output terminal of the amplifier U1.

[0014] One end of capacitor C2 is connected between resistor R5 and resistor R6, and the other end of capacitor C2 is grounded;

[0015] One end of capacitor C3 is connected between the non-inverting input terminal of amplifier U1 and resistor R6, and the other end of capacitor C3 is grounded.

[0016] Furthermore, the acquisition circuit includes: a sampling resistor RS1;

[0017] The sampling resistor RS1 is installed in the device with permanent magnet material to obtain the operating current, and one side of the sampling resistor RS1 is grounded to convert the operating current into an output voltage.

[0018] Furthermore, it also includes an amplifier circuit connected to the acquisition circuit and used to amplify the output voltage, the amplifier circuit including: amplifier U2, resistor R2, resistor R3, and resistor R4;

[0019] The non-inverting input terminal of the amplifier U2 is connected to the acquisition circuit as the input terminal of the amplification circuit to obtain the output voltage. The inverting input terminal of the amplifier U2 is connected in series with the resistor R2 and then grounded. The output terminal of the amplifier U2 is connected in series with the resistor R4 and then serves as the output terminal of the acquisition circuit to output the amplified output voltage.

[0020] One end of resistor R3 is connected between the inverting input terminal of amplifier U2 and resistor R2, and the other end of resistor R3 is connected between the output terminal of amplifier U2 and resistor R4.

[0021] Furthermore, the amplification factor of the amplifier circuit is: ;

[0022] Wherein, R2 is the resistance value of resistor R2, and R3 is the resistance value of resistor R3.

[0023] Furthermore, the comparison circuit includes: comparator U3, resistor R7, resistor R8, resistor R9, and capacitor C5;

[0024] The non-inverting input of the comparator U3 is connected in series with the resistor R7 and then connected to the output of the reference voltage generation circuit to obtain the reference voltage. The inverting input of the comparator U3 is connected in series with the resistor R8 and then connected to the output of the amplifier circuit to obtain the amplified output voltage. The output of the comparator U3 serves as the output of the comparator circuit to output the trigger signal.

[0025] One end of resistor R9 is connected to the output terminal of comparator U3, and the other end of resistor R9 is connected to a 3.3V power supply.

[0026] One end of capacitor C5 is connected to the output of comparator U3, and the other end of capacitor C5 is grounded.

[0027] Furthermore, it also includes a delay latch circuit for continuously outputting the trigger signal, the delay latch circuit including: a 555 timer, a transistor Q7, resistors R10, R11, and R12, and capacitors C6 and C7.

[0028] The TR pin of the 555 timer is connected to the output of the comparator circuit to obtain the trigger signal. The OUT pin of the 555 timer is connected to the base of the transistor Q7. The emitter of the transistor Q7 is grounded. The collector of the transistor Q7 is connected in series with the resistor R12 and then connected to a 3.3V power supply. The driver chip is connected between the collector of the transistor Q7 and the resistor R12.

[0029] The 555 timer's pin VCC is connected in series with the resistor R11 and then connected between the 555 timer's pin OUT and the base of the transistor Q7. One end of the resistor R10 is connected between the 555 timer's pin VCC and the resistor R11, and the other end of the resistor R10 is connected in series with the capacitor C6 and then grounded.

[0030] The RS pin of the 555 timer is connected between resistors R10 and R11. The THR and DIS pins of the 555 timer are connected between resistor R10 and capacitor C6. The CV pin of the 555 timer is connected in series with capacitor C7 and then grounded. The GND pin of the 555 timer is grounded.

[0031] The present invention also proposes a compressor having a permanent magnet material and having the above-mentioned demagnetization protection circuit.

[0032] Compared with the prior art, the present invention has at least the following beneficial effects:

[0033] This invention can detect the operating temperature of equipment with permanent magnet materials and dynamically adjust the demagnetization protection threshold according to the operating temperature to generate a corresponding reference voltage. While ensuring the demagnetization safety margin, it can avoid performance waste caused by a fixed low demagnetization protection threshold, enabling the motor or compressor to output higher operating current under normal operating conditions and improve overall performance. Attached Figure Description

[0034] To more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0035] Figure 1 This is a topology diagram of the demagnetization protection circuit in this invention;

[0036] Figure 2 This is a topology diagram of the output circuit in this invention;

[0037] Figure 3 This is a topology diagram of the amplifier circuit in this invention;

[0038] Figure 4 This is a topology diagram of the comparison circuit in this invention;

[0039] Figure 5 This is a topology diagram of the delay latch circuit in this invention;

[0040] Figure 6This is a waveform diagram of the demagnetization protection circuit in this invention. Detailed Implementation

[0041] To make the technical problems to be solved, the technical solutions, and the beneficial effects of the present invention clearer, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the present invention and are not intended to limit the present invention.

[0042] Therefore, a feature pointed out in this specification is used to describe one feature of one embodiment of the invention, and does not imply that every embodiment of the invention must have the described feature. Furthermore, it should be noted that this specification describes many features. Although certain features may be combined to illustrate possible system designs, these features may also be used in other combinations not explicitly stated. Therefore, unless otherwise stated, the described combinations are not intended to be limiting.

[0043] The principles and structure of the present invention will be described in detail below with reference to the accompanying drawings and embodiments.

[0044] Existing demagnetization protection circuits typically use a fixed demagnetization current threshold, which is set as the critical demagnetization current under the lowest operating temperature condition of the equipment. While this design can provide effective protection at low temperatures, it limits the operating current output within the normal operating temperature range, causing the motor or compressor to not fully utilize its rated performance, thus affecting the performance and operating efficiency of the equipment.

[0045] To address the aforementioned issues, the present invention involves detecting the operating temperature of a device with permanent magnet materials and generating a corresponding reference voltage based on this temperature. Then, by detecting the operating current of the device and converting it into an output voltage, the risk of demagnetization can be determined. This reference voltage is equivalent to the demagnetizing current threshold in existing solutions, except that in this invention, it is dynamically adjusted to adapt to the operating temperature, avoiding a fixed demagnetizing current threshold corresponding to the minimum operating temperature, which would affect the operating efficiency of the device with permanent magnet materials within its normal operating temperature range.

[0046] Based on this design concept, the demagnetization protection circuit proposed in this invention includes a driving chip for driving a device with permanent magnet material, a reference voltage generation circuit for collecting the operating temperature of the permanent magnet material and converting it into a reference voltage, a collection circuit for collecting the operating current of the device with permanent magnet material and converting it into an output voltage, and a comparison circuit for generating a trigger signal that characterizes whether the device with permanent magnet material is at risk of demagnetization based on the reference voltage and the output voltage.

[0047] The driver chip can receive the trigger signal and drive the device with permanent magnet material to stop when there is a risk of demagnetization.

[0048] Here, the reference voltage is equivalent to the demagnetizing current threshold in the prior art. That is, when the output voltage corresponding to the operating current in the device with permanent magnet material reaches the reference voltage, there is a risk of demagnetization. The relationship between the operating temperature and the reference voltage can be obtained from experiments and recorded in the DSP in advance. After the DSP obtains the operating temperature, it can output the corresponding reference voltage.

[0049] In traditional solutions, the demagnetizing current threshold is a fixed threshold set based on the lowest operating temperature. This threshold is relatively small, and to avoid demagnetizing risks, the operating current must generally be kept below this threshold. This limits the operating current of devices with permanent magnets, restricting their efficiency within the normal operating temperature range. In contrast, this invention dynamically sets the reference voltage by collecting the operating temperature. When the device is within its normal operating temperature range, this reference voltage is also the critical voltage that prevents demagnetizing risks at the current operating temperature. It is higher than the critical voltage at the lowest operating temperature, allowing the device to operate at a higher current without demagnetizing risks, thus improving the overall performance of the device.

[0050] To achieve the above principle, the reference voltage generation circuit in this invention includes at least a temperature sensor for acquiring the operating temperature, a digital signal processor for converting the operating temperature into a digital signal corresponding to the reference voltage, and an output circuit for converting the digital signal into a reference voltage and outputting it.

[0051] Please see Figure 1 The device with permanent magnet material is a motor (M). In the demagnetization protection circuit, the temperature sensor is set at the motor to obtain the motor's operating temperature. It is connected to the TEMP pin of the DSP. The DSP stores the correspondence between the operating temperature and the reference voltage. After obtaining the operating temperature, the corresponding reference voltage can be calculated. The DSP itself cannot output a specific voltage value. It has a digital signal processor inside that can generate a digital signal corresponding to the reference voltage and output it through the PWM-DA pin of the DSP. After the input terminal of the output circuit is connected to the PWM-DA pin to obtain the corresponding digital signal, the corresponding reference voltage VREF can be output for subsequent judgment of whether there is a risk of demagnetization.

[0052] In other words, the present invention, based on the setting of the reference voltage generation circuit, can dynamically set the reference voltage according to the operating temperature, ensuring that the reference voltage for demagnetization protection matches the current operating temperature, and avoiding performance waste caused by setting the demagnetization protection threshold too low.

[0053] The calculation model for the aforementioned reference voltage is as follows:

[0054]

[0055] in, For operating temperature, The reference voltage for the operating temperature. For operating temperature is The reference voltage at that time This is the compensation coefficient.

[0056] In this computational model For a known quantity, it can be derived from experiments or experience. The compensation coefficient, determined experimentally, is typically set to 0.10%~0.15% / °C to match the remanence (Br) temperature coefficient of the permanent magnet material.

[0057] After using the above calculation model, this invention correlates the operating temperature with the reference voltage, so that each operating temperature has a reference voltage that can be used for demagnetization protection. This allows the operating current to fit the current operating temperature range, ensuring the maximum operating capacity of the motor or compressor.

[0058] Please see Figure 1 and Figure 2 The output circuit of this invention includes: amplifier U1, resistor R5, resistor R6, capacitor C2, and capacitor C3;

[0059] The non-inverting input of amplifier U1 is connected in series with resistors R6 and R5 to serve as the input of the output circuit to receive the digital signal. The output of amplifier U1 serves as the output of the reference voltage generation circuit to output the reference voltage. The inverting input of amplifier U1 is connected to the output of amplifier U1.

[0060] One end of capacitor C2 is connected between resistors R5 and R6, and the other end of capacitor C2 is grounded.

[0061] One end of capacitor C3 is connected between the non-inverting input of amplifier U1 and resistor R6, and the other end of capacitor C3 is grounded.

[0062] This part of the circuit actually forms a voltage follower, which can convert the digital signal output by the DSP into the corresponding reference voltage VREF. The function of capacitors C2 and C3 is to filter and avoid errors caused by noise interference.

[0063] Please see Figure 1 The acquisition circuit includes: sampling resistor RS1;

[0064] The sampling resistor RS1 is placed in the device with permanent magnet material to obtain the operating current, and one side of the sampling resistor RS1 is grounded to convert the operating current into the output voltage.

[0065] In this embodiment, the motor is a three-phase motor. Switches Q1, Q2, Q3, Q4, Q5, and Q6 on the left side constitute the drive circuit for the three-phase motor. A sampling resistor RS1 is set in the drive circuit to obtain the operating current. When the operating current flowing through the motor passes through the sampling resistor RS1, a voltage difference will be generated across the resistor. Since one end of the sampling resistor RS1 is grounded, the voltage at the other end of the sampling resistor RS1 is actually the output voltage corresponding to the operating current of the motor. An amplifier circuit can be connected to the other end of the sampling resistor RS1 to obtain the output voltage.

[0066] The relationship between output voltage and operating current is as follows: ;

[0067] in, For output voltage, For operating current, Let RS1 be the resistance value of the sampling resistor.

[0068] In other words, by setting the sampling resistor RS1 as described above, the operating current of the device with permanent magnet material can be collected and converted into an output voltage, providing a basis for subsequent judgment on whether the device with permanent magnet material is at risk of demagnetization.

[0069] In practical applications, the resistance of the sampling resistor RS1 is typically in the milliohm range. The output voltage is directly proportional to the resistance of RS1. Therefore, the output voltage generated by the sampling resistor RS1 is relatively small. To facilitate subsequent processing, this invention also includes an amplifier circuit to amplify the output voltage. Please refer to [link to relevant documentation]. Figure 1 and Figure 3 The amplifier circuit in this invention includes: amplifier U2, resistor R2, resistor R3, and resistor R4;

[0070] The non-inverting input of amplifier U2 is connected to the acquisition circuit as the input of the amplifier circuit to obtain the output voltage. The inverting input of amplifier U2 is connected to ground after series with resistor R2. The output of amplifier U2 is connected to the acquisition circuit after series with resistor R4 to output the amplified output voltage.

[0071] One end of resistor R3 is connected between the inverting input terminal of amplifier U2 and resistor R2, and the other end of resistor R3 is connected between the output terminal of amplifier U2 and resistor R4.

[0072] In this setting, amplifier U2 constitutes a non-inverting amplifier, which can amplify the output voltage, and the amplification factor can be set according to the resistor connected to it, which facilitates the subsequent processing of the output voltage;

[0073] Based on the working principle of the non-inverting amplifier, its output and input satisfy the following:

[0074]

[0075] Here, OC is the output of the non-inverting amplifier, that is, the amplified output voltage. For output voltage, In other words, the amplification factor of the output voltage of the non-inverting amplifier can be adjusted by setting the resistance values ​​of resistors R2 and R3 to ensure that the amplitude of the output voltage meets the input requirements of the comparator circuit.

[0076] After obtaining the output voltage OC and the reference voltage VREF, they can be compared to determine whether there is a risk of demagnetization. Generally, a risk of demagnetization exists when the output voltage OC is higher than the reference voltage VREF. To implement this logic, a comparison circuit is provided in this invention. Please refer to [link to relevant documentation]. Figure 1 and Figure 4 The comparator circuit includes: comparator U3, resistor R7, resistor R8, resistor R9, and capacitor C5;

[0077] The non-inverting input of comparator U3 is connected in series with resistor R7 and then connected to the output of the reference voltage generation circuit to obtain the reference voltage. The inverting input of comparator U3 is connected in series with resistor R8 and then connected to the output of the amplifier circuit to obtain the amplified output voltage. The output of comparator U3 serves as the output of the comparator circuit to output the trigger signal.

[0078] One end of resistor R9 is connected to the output of comparator U3, and the other end of resistor R9 is connected to a 3.3V power supply.

[0079] One end of capacitor C5 is connected to the output of comparator U3, and the other end of capacitor C5 is grounded.

[0080] The high level output of comparator U3 is unstable. The 3.3V power supply and resistor R9 are set here to ensure that the high level output of comparator U3 is more stable. According to the working principle of comparator U3, when the amplified output voltage OC is less than the reference voltage VREF, the output of comparator U3 is pulled up to 3.3V through resistor R9, which is a high level signal, indicating that there is no risk of demagnetization. When the amplified output voltage OC is greater than the reference voltage VREF, the output of comparator U3 outputs a low level signal, indicating that there is a risk of demagnetization.

[0081] In other words, by setting up this comparison circuit, the present invention can accurately determine whether there is a risk of demagnetization in equipment containing permanent magnet materials, thereby controlling the timely shutdown of the equipment to prevent further damage. Furthermore, since the sampling resistor RS1 actually collects the operating current, the comparison circuit can also be used to determine whether the equipment containing permanent magnet materials has an overcurrent problem.

[0082] Because the output level of comparator U3 is short, to ensure reliable triggering and maintenance of the demagnetization protection, the trigger signal needs to be maintained for a period of time. Therefore, this invention also includes a delay latch circuit for continuously outputting the trigger signal. Please refer to [link to relevant documentation]. Figure 1 and Figure 5 The delay latch circuit includes: 555 timer, transistor Q7, resistor R10, resistor R11, resistor R12, capacitor C6, and capacitor C7.

[0083] The TR pin of the 555 timer is connected to the output of the comparator circuit to obtain the trigger signal. The OUT pin of the 555 timer is connected to the base of transistor Q7. The emitter of transistor Q7 is grounded. The collector of transistor Q7 is connected to a 3.3V power supply after being connected in series with resistor R12. The driver chip is connected between the collector of transistor Q7 and resistor R12.

[0084] The 555 timer's VCC pin is connected in series with resistor R11 and then connected between the 555 timer's OUT pin and the base of transistor Q7. One end of resistor R10 is connected between the 555 timer's VCC pin and resistor R11, and the other end of resistor R10 is connected in series with capacitor C6 and then grounded.

[0085] The RS pin of the 555 timer is connected between resistors R10 and R11. The THR and DIS pins of the 555 timer are connected between resistor R10 and capacitor C6. The CV pin of the 555 timer is connected to ground in series with capacitor C7. The GND pin of the 555 timer is grounded.

[0086] This delay latch circuit is mainly implemented using a 555 timer. The TR pin is the trigger terminal, which is driven by the output of comparator U3. When the TR pin receives a low-level signal, it is triggered. The 555 timer can set the output delay through external resistor and capacitor components, so that the trigger signal is continuously output for a certain period of time.

[0087] When pin TR is triggered, pin OUT outputs a low-level signal for a duration of: ;

[0088] By setting the resistance value of resistor R10 and the capacitance value of capacitor C6, the continuous output time can be set. In this invention, the continuous output time is set to 5ms to facilitate stable acquisition by the driver chip, thereby enhancing the reliability of the protection action and improving the accuracy of triggering.

[0089] As mentioned earlier, when there is a risk of demagnetization, the comparator circuit outputs a low-level trigger signal, and the 555 timer can continuously output this low-level trigger signal for 5ms. Figure 1 U4 is the driver chip. When its signal node CIN receives a high level, it can cut off the subsequent power drive signal, thereby stopping the equipment with permanent magnet materials for demagnetization protection. Therefore, this invention also needs to convert the low-level signal output by the comparator circuit into a high-level signal when there is a risk of demagnetization and transmit it to the driver chip. This is achieved by transistor Q7 and resistor R12 in the delay latch circuit. After the signal node CIN is connected between the collector of transistor Q7 and resistor R12, when the comparator circuit outputs a low-level signal, the 555 timer continues to output the low-level signal, making transistor Q7 in the off state. At this time, the signal node CIN is pulled up to a high-level signal of 3.3V through the pull-up resistor R12. The signal node CIN is connected to the IN- pin of the driver chip. When the IN- pin is high, the driver chip stops outputting, thereby cutting off the subsequent power drive signal and realizing self-locking protection for the motor or compressor.

[0090] This self-locking protection state will remain until the system is reset or the protection conditions are released, ensuring that the equipment can be shut down in time in the event of demagnetization risk or overcurrent fault to prevent further damage;

[0091] Figure 6 The trigger waveform of this invention is as follows: when the output OC of the amplifier circuit is higher than the reference voltage VREF, the system protection is triggered, the output voltage is pulled down, the FO signal is simultaneously pulled down to a low level, the CIN signal is pulled up to 3.3V, the driver chip stops outputting the power drive signal, and the motor or compressor stops to prevent further damage.

[0092] In summary, compared with the prior art, the present invention has at least the following beneficial effects:

[0093] This invention can detect the operating temperature of equipment with permanent magnet materials and dynamically adjust the demagnetization protection threshold according to the operating temperature to generate a corresponding reference voltage. While ensuring the demagnetization safety margin, it can avoid performance waste caused by a fixed low demagnetization protection threshold, enabling the motor or compressor to output higher operating current under normal operating conditions and improve overall performance.

[0094] The present invention also proposes a compressor with permanent magnet material, which has the above-mentioned demagnetization protection circuit.

[0095] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A demagnetization protection circuit, comprising a driver chip for driving a device with a permanent magnet material, characterized in that, It also includes a reference voltage generation circuit for collecting the operating temperature of the device with permanent magnet material and converting it into a reference voltage, a collection circuit for collecting the operating current of the device with permanent magnet material and converting it into an output voltage, and a comparison circuit for generating a trigger signal that characterizes whether the device with permanent magnet material has a risk of demagnetization based on the reference voltage and the output voltage. The drive chip can receive the trigger signal and drive the device with permanent magnet material to stop when there is a risk of demagnetization.

2. The demagnetization protection circuit according to claim 1, characterized in that, The reference voltage generation circuit includes a temperature sensor for acquiring the operating temperature, a digital signal processor for converting the operating temperature into a digital signal corresponding to the reference voltage, and an output circuit for converting the digital signal into a reference voltage for output.

3. The demagnetization protection circuit according to claim 2, characterized in that, The calculation model for the reference voltage is as follows: ； in, The operating temperature, The reference voltage for the operating temperature. For operating temperature is The reference voltage at that time This is the compensation coefficient.

4. The demagnetization protection circuit according to claim 2, characterized in that, The output circuit includes: amplifier U1, resistor R5, resistor R6, capacitor C2, and capacitor C3; The non-inverting input terminal of the amplifier U1 is connected in series with the resistors R6 and R5 to serve as the input terminal of the output circuit and is connected to the digital signal. The output terminal of the amplifier U1 serves as the output terminal of the reference voltage generation circuit and outputs the reference voltage. The inverting input terminal of the amplifier U1 is connected to the output terminal of the amplifier U1. One end of capacitor C2 is connected between resistor R5 and resistor R6, and the other end of capacitor C2 is grounded; One end of capacitor C3 is connected between the non-inverting input terminal of amplifier U1 and resistor R6, and the other end of capacitor C3 is grounded.

5. The demagnetization protection circuit according to claim 1, characterized in that, The acquisition circuit includes: a sampling resistor RS1; The sampling resistor RS1 is installed in the device with permanent magnet material to obtain the operating current, and one side of the sampling resistor RS1 is grounded to convert the operating current into an output voltage.

6. The demagnetization protection circuit according to claim 1, characterized in that, It also includes an amplifier circuit connected to the acquisition circuit and used to amplify the output voltage, the amplifier circuit including: amplifier U2, resistor R2, resistor R3, and resistor R4; The non-inverting input terminal of the amplifier U2 is connected to the acquisition circuit as the input terminal of the amplification circuit to obtain the output voltage. The inverting input terminal of the amplifier U2 is connected in series with the resistor R2 and then grounded. The output terminal of the amplifier U2 is connected in series with the resistor R4 and then serves as the output terminal of the acquisition circuit to output the amplified output voltage. One end of resistor R3 is connected between the inverting input terminal of amplifier U2 and resistor R2, and the other end of resistor R3 is connected between the output terminal of amplifier U2 and resistor R4.

7. The demagnetization protection circuit according to claim 6, characterized in that, The amplification factor of the amplifier circuit is: ; Wherein, R2 is the resistance value of resistor R2, and R3 is the resistance value of resistor R3.

8. The demagnetization protection circuit according to claim 6, characterized in that, The comparison circuit includes: comparator U3, resistor R7, resistor R8, resistor R9, and capacitor C5; The non-inverting input of the comparator U3 is connected in series with the resistor R7 and then connected to the output of the reference voltage generation circuit to obtain the reference voltage. The inverting input of the comparator U3 is connected in series with the resistor R8 and then connected to the output of the amplifier circuit to obtain the amplified output voltage. The output of the comparator U3 serves as the output of the comparator circuit to output the trigger signal. One end of resistor R9 is connected to the output terminal of comparator U3, and the other end of resistor R9 is connected to a 3.3V power supply. One end of capacitor C5 is connected to the output of comparator U3, and the other end of capacitor C5 is grounded.

9. The demagnetization protection circuit according to claim 1, characterized in that, It also includes a delay latch circuit for continuously outputting the trigger signal, the delay latch circuit including: 555 timer, transistor Q7, resistor R10, resistor R11, resistor R12, capacitor C6, and capacitor C7. The TR pin of the 555 timer is connected to the output of the comparator circuit to obtain the trigger signal. The OUT pin of the 555 timer is connected to the base of the transistor Q7. The emitter of the transistor Q7 is grounded. The collector of the transistor Q7 is connected in series with the resistor R12 and then connected to a 3.3V power supply. The driver chip is connected between the collector of the transistor Q7 and the resistor R12. The 555 timer's pin VCC is connected in series with the resistor R11 and then connected between the 555 timer's pin OUT and the base of the transistor Q7. One end of the resistor R10 is connected between the 555 timer's pin VCC and the resistor R11, and the other end of the resistor R10 is connected in series with the capacitor C6 and then grounded. The RS pin of the 555 timer is connected between resistors R10 and R11. The THR and DIS pins of the 555 timer are connected between resistor R10 and capacitor C6. The CV pin of the 555 timer is connected in series with capacitor C7 and then grounded. The GND pin of the 555 timer is grounded.

10. A compressor having a permanent magnet material, characterized in that, The compressor also has a demagnetization protection circuit as described in any one of claims 1 to 9.

Images