Demagnetization current protection circuit, motor controller and motor

Abstract

The utility model provides a demagnetization current protection circuit, a motor controller and a motor, and belongs to the field of electronic circuits, and the scheme is that the demagnetization current protection circuit comprises a voltage sampling circuit used for collecting voltage values on three bridge arms of a rectification circuit; the synonym end of the first comparison circuit is connected with the first output end of the voltage sampling circuit; the synonym end of the second comparison circuit is connected with the second output end of the voltage sampling circuit; the synonym end of the second comparison circuit is connected with the third output end of the voltage sampling circuit; the temperature sampling circuit is used for collecting the actual temperature of the protected motor; the output end of the reference voltage generation circuit is used for outputting a demagnetization protection voltage value generated at least based on the sampling result of the temperature sampling circuit and sending the demagnetization protection voltage value to the comparison circuit, and the value of the demagnetization protection voltage value is related to the motor temperature and changes along with the change of the motor temperature. Therefore, whether the motor has a demagnetization risk or not can be judged more accurately.

Description

Technical Field

[0001] The utility model relates to the field of electronic circuit design, in particular to a demagnetization current protection circuit and electrical equipment. Background Art

[0002] In the application of air conditioning systems, the motors of fans and compressors are made of permanent magnets. At a certain temperature, permanent magnets have requirements for the current flowing through the motor windings. Once the current exceeds the limit, the permanent magnet magnetic field will disappear, that is, the permanent magnet will be demagnetized. After the permanent magnet of the motor is demagnetized, the motor will not be able to be controlled normally; therefore, the demagnetization current protection circuit is included in the driver of the fan and the compressor, and the current of the motor winding is controlled by the demagnetization current protection circuit to avoid the phenomenon of permanent magnet demagnetization due to excessive current.

[0003] After research, the applicant found that the magnitude of the demagnetization current that causes the demagnetization of the permanent magnet is not fixed. The magnitude of the current is affected by the temperature of the environment in which the permanent magnet is located. When the temperature rises, the critical value of the demagnetization current decreases, and when the temperature decreases, the critical value of the demagnetization current increases. The demagnetization current protection circuit in the prior art usually uses a fixed demagnetization protection voltage value to limit the current of the motor winding, which makes it difficult to provide accurate protection for the motor. Utility Model Content

[0004] In view of this, an embodiment of the utility model provides a demagnetization current protection circuit, a motor controller and a motor, so as to provide more accurate demagnetization protection for the motor.

[0005] To achieve the above purpose, the present invention provides the following technical solutions:

[0006] A demagnetization current protection circuit, comprising:

[0007] A voltage sampling circuit, wherein the three input terminals of the voltage sampling circuit are respectively connected to the three bridge arms of the rectifier circuit in a one-to-one correspondence to collect voltage values ​​on the three bridge arms of the rectifier circuit, and the rectifier circuit is arranged between the motor inverter driver and the protected motor;

[0008] A first comparison circuit, wherein an opposite-signal terminal of the first comparison circuit is connected to a first output terminal of the voltage sampling circuit;

[0009] A second comparison circuit, wherein an opposite-signal terminal of the second comparison circuit is connected to a second output terminal of the voltage sampling circuit;

[0010] a third comparison circuit, wherein the opposite-name terminal of the second comparison circuit is connected to the third output terminal of the voltage sampling circuit;

[0011] Temperature sampling circuit, used to collect the actual temperature of the protected motor;

[0012] A reference voltage generating circuit, wherein a first input end of the reference voltage generating circuit is connected to an output end of the temperature sampling circuit, a second input end of the reference voltage generating circuit is connected to the first comparison circuit, the third comparison circuit and an output end of the third comparison circuit, an output end of the reference voltage generating circuit is connected to the same-name ends of the first comparison circuit, the second comparison circuit and the third comparison circuit, and an output end of the reference voltage generating circuit is used to output a demagnetization protection voltage value generated at least based on a sampling result of the temperature sampling circuit.

[0013] Optionally, in the above demagnetization current protection circuit, the voltage sampling circuit includes:

[0014] A first sampling resistor, a second sampling resistor, and a third sampling resistor;

[0015] The first sampling resistor is arranged in series in the first bridge arm of the rectifier circuit, the first end of the first sampling resistor is connected to the switch tube in the first bridge arm, and the second end of the first sampling resistor is connected to the negative input end of the rectifier circuit;

[0016] The second sampling resistor is arranged in series in the second bridge arm of the rectifier circuit, the first end of the second sampling resistor is connected to the switch tube in the second bridge arm, and the second end of the second sampling resistor is connected to the negative input end of the rectifier circuit;

[0017] The third sampling resistor is arranged in series in the third bridge arm of the rectifier circuit, the first end of the third sampling resistor is connected to the switch tube in the third bridge arm, and the second end of the third sampling resistor is connected to the negative input end of the rectifier circuit.

[0018] Optionally, in the above demagnetization current protection circuit, the voltage sampling circuit further includes:

[0019] a first filtering circuit, a second filtering circuit and a third filtering circuit;

[0020] The first filter circuit is arranged between the first sampling resistor and the first output end of the voltage sampling circuit;

[0021] The second filter circuit is arranged between the second sampling resistor and the second output terminal of the voltage sampling circuit;

[0022] The third filtering circuit is arranged between the third sampling resistor and the third output terminal of the voltage sampling circuit.

[0023] Optionally, the above demagnetization current protection circuit further includes:

[0024] A voltage follower is provided between an output terminal of the reference voltage generating circuit and the same-name terminals of the first comparison circuit, the second comparison circuit and the third comparison circuit.

[0025] Optionally, in the above-mentioned demagnetization current protection circuit, the temperature sampling circuit is arranged on the housing of the protected motor or on a control circuit board.

[0026] Optionally, in the above demagnetization current protection circuit, the reference voltage generating circuit includes:

[0027] Microprocessor and DAC circuit;

[0028] The first input terminal of the microprocessor serves as the first input terminal of the reference voltage generating circuit, and the second input terminal of the microprocessor serves as the second input terminal of the reference voltage generating circuit;

[0029] The output end of the DAC circuit serves as the output end of the reference voltage generating circuit;

[0030] The output end of the microprocessor is connected to the input end of the DAC circuit, and the output end of the microprocessor is used to output a demagnetization protection voltage value generated at least based on the sampling result of the temperature sampling circuit.

[0031] Optionally, in the above-mentioned demagnetization current protection circuit, the rectifier circuit is a full-bridge rectifier circuit.

[0032] Optionally, the above demagnetization current protection circuit further includes:

[0033] a first voltage stabilizing capacitor and a second voltage stabilizing capacitor;

[0034] The first voltage stabilizing capacitor is connected to the output ends of the first comparison circuit, the second comparison circuit and the third comparison circuit;

[0035] The second voltage stabilizing capacitor is connected to the output end of the follower.

[0036] A motor controller is provided, using any one of the above-mentioned demagnetization current protection circuits.

[0037] A motor is applied with the motor controller mentioned above.

[0038] Based on the above technical scheme, the above scheme provided by the embodiment of the utility model is that when the protected motor is working, the temperature sampling circuit collects the real-time temperature of the protected motor, and sends the collected temperature to the reference voltage generating circuit. The reference voltage generating circuit generates a demagnetization protection voltage value based on the real-time temperature, and sends the demagnetization protection voltage value to the same-name end of the first comparison circuit, the second comparison circuit and the third comparison circuit respectively. At the same time, the voltages on the three bridge arms of the rectifier circuit are respectively collected by the voltage sampling circuit, and the collected voltages are respectively sent to the opposite-name ends of the first comparison circuit, the second comparison circuit and the third comparison circuit. The three comparison circuits compare the input signals of the same-name end and the opposite-name end respectively, and output the comparison results. The comparison results can indicate whether the motor has a demagnetization risk. Specifically, when the input voltage of the opposite-name end of the comparison circuit is less than the input voltage of the same-name end, the comparison circuit outputs a low-level signal, and the low-level signal is used to indicate that the motor has no demagnetization risk. When the input voltage of the opposite-name end of the comparison circuit is greater than the input voltage of the same-name end, the comparison circuit outputs a high-level signal, and the high-level signal is used to indicate that the motor has a demagnetization risk. It can be seen from the above process that in this solution, the value of the demagnetization protection voltage is related to the motor temperature, and its value changes with the change of the motor temperature, so that it can more accurately judge whether the motor has a demagnetization risk. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] In order to more clearly illustrate the embodiments of the utility model or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings in the following description are only embodiments of the utility model. For ordinary technicians in this field, other drawings can be obtained based on the provided drawings without paying creative work.

[0040] Figure 1 A schematic diagram of the structure of a demagnetization current protection circuit disclosed in an embodiment of the present application;

[0041] Figure 2 It is a structural schematic diagram of a full-bridge rectifier circuit;

[0042] Figure 3 A schematic diagram of the structure of a voltage sampling circuit disclosed in an embodiment of the present application;

[0043] Figure 4 It is a schematic structural diagram of a demagnetization current protection circuit disclosed in another embodiment of the present application. DETAILED DESCRIPTION

[0044] The following will be combined with the drawings in the embodiments of the utility model to clearly and completely describe the technical solutions in the embodiments of the utility model. Obviously, the described embodiments are only part of the embodiments of the utility model, not all of the embodiments. Based on the embodiments in the utility model, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the utility model.

[0045] The technical solution disclosed in this embodiment collects the temperature of the protected motor through the temperature sampling circuit 300, and dynamically adjusts the demagnetization protection voltage value based on the collected temperature, so that the demagnetization protection voltage value changes with the temperature change of the environment in which the permanent magnet is located, thereby providing an accurate demagnetization protection voltage value for the permanent magnet.

[0046] For details, see Figure 1 The demagnetization current protection circuit disclosed in this embodiment includes: a voltage sampling circuit 100, a first comparison circuit IC1A, a second comparison circuit IC1B, a third comparison circuit IC2A, a temperature sampling circuit 300 and a reference voltage generating circuit 400.

[0047] The three input ends of the voltage sampling circuit 100 are respectively connected to the three bridge arms of the rectifier circuit in a one-to-one correspondence to collect the voltage values ​​on the three bridge arms of the rectifier circuit. The rectifier circuit is arranged between the motor inverter driver and the protected motor. Common types of voltage sampling circuits 100 include resistor voltage divider circuits, differential amplifier circuits, and integration circuits. In this scheme, a resistor voltage divider circuit can be used. A rectifier circuit is a circuit that converts AC power into DC power. Among them, the rectifier diode is the core part of the rectifier circuit. By using the unidirectional conductivity of the diode, the negative half cycle of the sinusoidal AC power is cut off, and only the positive half cycle is retained, thereby obtaining DC power. A comparison circuit is a circuit that compares two signals and judges whether the two input signals are equal and the relative size by the "presence", "absence" and polarity of the output signal. This circuit is mainly used to compare the size of two voltages and output corresponding voltage signals. The comparison circuit disclosed in this embodiment can be a comparison circuit composed of an operational amplifier. Specifically, the comparison circuit can be a common-phase comparison circuit or a reverse-phase comparison circuit. In the common-phase comparison circuit, when the input voltage exceeds the reverse-phase terminal voltage, the output voltage will be converted from 0 to a high level (positive voltage). In the reverse-phase comparison circuit, when the input voltage exceeds the reference voltage (Vref) applied to the common-phase terminal, the output will be converted from a high level to a low level. Each comparison circuit involved in this embodiment can be a positive-phase comparison circuit.

[0048] The opposite-name terminal (inverting input terminal) of the first comparison circuit IC1A is connected to the first output terminal of the voltage sampling circuit 100; the opposite-name terminal of the second comparison circuit IC1B is connected to the second output terminal of the voltage sampling circuit 100; the opposite-name terminal of the third comparison circuit IC2A is connected to the third output terminal of the voltage sampling circuit 100; the same-name terminals (non-inverting input terminals) of the first comparison circuit IC1A, the second comparison circuit IC1B and the third comparison circuit IC2A are connected to the second output terminal of the reference voltage generating circuit 400, and the first comparison circuit IC1A, the second comparison circuit IC1B and the third comparison circuit IC2A use the signal output from the second output terminal of the reference voltage generating circuit 400 as a reference signal to compare with the output signal of the corresponding sampling circuit, and output the comparison result.

[0049] The temperature sampling circuit 300 is used to collect the actual temperature of the protected motor. The temperature sampling circuit 300 is a circuit for collecting temperature information and converting it into a voltage signal. The temperature sampling circuit 300 can be a temperature sensor. In the technical solution disclosed in this embodiment, the temperature sampling circuit 300 can be set on the housing of the voltage protected motor or on the control circuit board, and of course it can also be other places where the permanent magnet temperature can be collected.

[0050] A first input end of the reference voltage generating circuit 400 is connected to an output end of the temperature sampling circuit 300, a second input end of the reference voltage generating circuit 400 is connected to output ends of the first comparison circuit IC1A, the second comparison circuit IC1B and the third comparison circuit IC2A, an output end of the reference voltage generating circuit 400 is connected to the same-name ends of the first comparison circuit IC1A, the second comparison circuit IC1B and the third comparison circuit IC2A, and an output end of the reference voltage generating circuit 400 is used to output a demagnetization protection voltage value generated at least based on a sampling result of the temperature sampling circuit 300. In this solution, the correspondence between the demagnetization protection voltage value y and the output result TMagnet of the temperature sampling circuit 300 can be calculated based on the formula y=k*TMagnet+b, and the relationship can be stored in a mapping list. The demagnetization protection voltage value y that matches the output result of the current temperature sampling circuit 300 can be obtained by directly looking up the table. In the above formula, k and b are preset coefficients. k and b are related to the model and type of the motor. When the model and type of the motor are determined, the value of b is also determined. Of course, the present application can also store the mapping relationship between the model and type of the motor and k and b in the corresponding list. After the model and type of the motor are determined, the corresponding k and b can be obtained by looking up the table.

[0051] The reference voltage generating circuit 400 is a circuit for generating a stable voltage, which plays an important role in electronic devices. The main purpose of the circuit is to provide an accurate reference voltage for other circuits to ensure the stability and reliability of the circuit. The reference voltage generating circuit 400 usually includes a voltage stabilizer and a reference voltage source. The voltage stabilizer is responsible for stabilizing the input voltage at a fixed value, while the reference voltage source generates a stable reference voltage. In this solution, the reference voltage is the demagnetization protection voltage value.

[0052] The working principle of the above circuit disclosed in this application is introduced below:

[0053] When the protected motor is working, the temperature sampling circuit 300 collects the real-time temperature of the protected motor, and sends the collected temperature to the reference voltage generating circuit 400. The reference voltage generating circuit 400 generates a demagnetization protection voltage value based on the real-time temperature, and sends the demagnetization protection voltage value to the same-name end of the first comparison circuit, the second comparison circuit and the third comparison circuit respectively. At the same time, the voltages on the three bridge arms of the rectifier circuit are collected respectively by the voltage sampling circuit 100, and the collected voltages are sent to the opposite-name ends of the first comparison circuit, the second comparison circuit and the third comparison circuit respectively. The three comparison circuits compare the input signals of the same-name end and the opposite-name end respectively, and output the comparison results. The comparison results can indicate whether the motor has a demagnetization risk. Specifically, when the input voltage of the opposite-name end of the comparison circuit is less than the input voltage of the same-name end, the comparison circuit outputs a low-level signal, and the low-level signal is used to indicate that the motor has no demagnetization risk. When the input voltage of the opposite-name end of the comparison circuit is greater than the input voltage of the same-name end, the comparison circuit outputs a high-level signal, and the high-level signal is used to indicate that the motor has a demagnetization risk. It can be seen from the above process that in this solution, the value of the demagnetization protection voltage is related to the motor temperature, and its value changes with the change of the motor temperature, so that it can more accurately judge whether the motor has a demagnetization risk.

[0054] The specific structures of the voltage sampling circuit 100 and the rectifier circuit can be set according to user needs, for example, see Figure 2As shown, the rectifier circuit can be a full-bridge rectifier circuit, and the voltage sampling circuit 100 includes: a first sampling resistor RS1, a second sampling resistor RS2, and a third sampling resistor RS3; the first sampling resistor RS1 is arranged in series in the first bridge arm (composed of switch tubes G1 and G2) of the rectifier circuit, the first end of the first sampling resistor RS1 is connected to the switch tube (G2) in the first bridge arm, and the second end of the first sampling resistor RS1 is connected to the negative input end of the rectifier circuit; the second sampling resistor RS2 is arranged in series in the second bridge arm (composed of switch tubes G3 and G4) of the rectifier circuit, the first end of the second sampling resistor RS2 is connected to the switch tube (G4) in the second bridge arm, and the second end of the second sampling resistor RS2 is connected to the negative input end of the rectifier circuit; the third sampling resistor RS3 is arranged in series in the third bridge arm (composed of switch tubes G5 and G6) of the rectifier circuit, the first end of the third sampling resistor RS3 is connected to the switch tube (G6) in the third bridge arm, and the second end of the third sampling resistor RS3 is connected to the negative input end of the rectifier circuit. The first sampling resistor RS1, the second sampling resistor RS2 and the third sampling resistor RS3 are used as voltage divider circuits in the first bridge arm, the second bridge arm and the third bridge arm, respectively. By measuring the voltages across the first sampling resistor RS1, the second sampling resistor RS2 and the third sampling resistor, the three-phase input voltage of the motor can be determined, and the three-phase input voltage is input into the opposite-name terminals of the first comparison circuit, the second comparison circuit and the third comparison circuit, respectively.

[0055] Further, in order to improve the reliability of the signal obtained by the comparison circuit, in the technical solution disclosed in this embodiment, the voltage sampling circuit 100 may also include a filtering circuit, and the filtering circuit specifically includes a first filtering circuit, a second filtering circuit and a third filtering circuit. The filtering circuit may be an RC filtering circuit, and the working principle of the RC filtering circuit is mainly based on the response characteristics of the resistor and the capacitor to signals of different frequencies. The capacitor has a smaller impedance to high-frequency signals and a larger impedance to low-frequency signals; while the resistor presents the same impedance to signals of all frequencies. Therefore, when the signal passes through the RC filtering circuit, high-frequency signals are more likely to pass through the capacitor, while low-frequency signals are more likely to pass through the resistor. By adjusting the values ​​of the resistor and the capacitor, the filtering effect of signals of different frequencies can be achieved to filter out interference signals and burr signals.

[0056] The first filter circuit is disposed between the first sampling resistor RS1 and the first output terminal of the voltage sampling circuit 100, and the first filter circuit is used to filter the voltage across the first sampling resistor RS1;

[0057] The second filtering circuit is disposed between the second sampling resistor RS2 and the second output terminal of the voltage sampling circuit 100, and the second filtering circuit is used to filter the voltage across the second sampling resistor RS2;

[0058] The third filtering circuit is disposed between the third sampling resistor RS3 and the third output terminal of the voltage sampling circuit 100 , and the third filtering circuit is used for filtering the voltage across the third sampling resistor RS3 .

[0059] See also Figure 3 The first filter circuit is composed of a resistor R8 and a capacitor C5, the second filter circuit is composed of a resistor R6 and a capacitor C4, and the third filter circuit is composed of a resistor R4 and a capacitor C1. Figure 3 The middle resistor R2, the resistor R5 and the resistor R7 are voltage drop resistors used to reduce the sampling voltage.

[0060] The technical solution disclosed in the above embodiment filters the collected voltage signal through the first filter circuit, the second filter circuit and the third filter circuit to filter out glitches and interference signals in the collected voltage, thereby preventing incorrect protection of the motor caused by interference and glitches in the collected voltage.

[0061] A voltage follower is a basic analog circuit whose function is to "follow" the input voltage signal to the output, that is, to copy the input voltage directly to the output terminal without changing the current and voltage. Figure 4 A voltage follower IC3B may be provided between the output end of the reference voltage generating circuit 400 and the first comparison circuit IC1A, the second comparison circuit IC1B and the third comparison circuit IC2A, the input end of the voltage follower being connected to the output end of the reference voltage generating circuit 400, and the output end of the voltage follower being connected to the same-name ends of the first comparison circuit IC1A, the second comparison circuit IC1B and the third comparison circuit IC2A, so as to perform signal buffering, impedance matching and signal isolation on the output signal of the reference voltage generating circuit 400 through the voltage follower, thereby improving the stability and performance of the circuit.

[0062] See also Figure 4In order to further improve the stability of the signal output by the reference voltage generating circuit 400, an RC filter circuit can be set between the voltage follower and the reference voltage generating circuit 400. The RC filter circuit is composed of a resistor R11 and a capacitor C6. Furthermore, a voltage drop resistor R10 is set between the output end of the voltage follower and the first comparison circuit IC1A, the second comparison circuit IC1B and the third comparison circuit IC2A, and a resistor R12 connected to the voltage drop resistor R10 and the other end of which is grounded.

[0063] See also Figure 4 In the technical solution disclosed in this embodiment, the reference voltage generating circuit 400 can be composed of a microprocessor MCU and a DAC circuit, the first input end of the microprocessor serves as the first input end of the reference voltage generating circuit 400, and the second input end of the microprocessor serves as the second input end of the reference voltage generating circuit 400; the output end of the DAC circuit serves as the output end of the reference voltage generating circuit 400; the output end of the microprocessor is connected to the input end of the DAC circuit, and the output end of the microprocessor is used to output a demagnetization protection voltage value generated at least based on the sampling result of the temperature sampling circuit 300.

[0064] The demagnetization protection current initial value Ip of the protected motor can be pre-written into the ROM of the microprocessor. The demagnetization protection current initial value Ip can be matched automatically or manually input according to the model of the protected motor. The microprocessor MCU simultaneously detects the temperature TE output by the protected motor, and performs a certain gain adjustment on the demagnetization protection current initial value Ip according to the temperature to obtain the current actual corresponding demagnetization protection current value, and then converts the demagnetization protection current value into the corresponding demagnetization protection voltage value; for example, when calculating the demagnetization protection voltage value of the compressor, a 53 displacement compressor can be taken as an example, the demagnetization The initial value of the protection current Ip is 70.8Apeak. When the detection temperature TE is 130°C, the demagnetization current setting value Ip is multiplied by the preset correction coefficient (94.5 / 70.8) to obtain the demagnetization protection current value to ensure that the compressor runs at full load capacity without premature protection. This preset correction coefficient can be written into the ROM of the microprocessor MCU in advance, and the correction coefficient can be automatically changed by looking up a table. A mapping relationship between the actual temperature of the protected motor and the correction coefficient is established in the table. After the actual temperature of the protected motor is determined, the corresponding correction coefficient can be determined by looking up the table.

[0065] The DAC circuit is used to realize digital-to-analog conversion and convert digital signals into analog signals. After obtaining the demagnetization protection voltage value output by the microprocessor MCU, the DAC circuit converts it and the DAC to obtain a PWM signal with a certain duty cycle (the size of the duty cycle matches the demagnetization protection voltage value). The PWM signal is used to characterize the demagnetization protection voltage value. After the PWM signal passes through the RC filter circuit composed of a resistor R11 and a capacitor C6, a stable analog signal is formed; the analog signal passes through a voltage follower composed of IC3B to avoid the input impedance of the signal being too small; the signal output by the follower passes through a voltage divider circuit composed of a resistor R10 and a resistor R12 and is sent to the same-name terminals of the first comparison circuit IC1A, the second comparison circuit IC1B and the third comparison circuit IC2A. The voltage divider circuit is set to divide the output signal of the follower to avoid the output signal being too large and exceeding the input signal limit of the first comparison circuit, the second comparison circuit and the third comparison circuit; through such a setting, different motors and different demagnetization protection values ​​can be targeted without changing the hardware circuit;

[0066] For further information, see Figure 4 The technical solution disclosed in this embodiment may also include a first voltage-stabilizing capacitor C2 and a second voltage-stabilizing capacitor C3. The first voltage-stabilizing capacitor C2 is arranged at the output end of the first comparison circuit, the second comparison circuit and the third comparison circuit, and is used to stabilize the output signals of the three comparison circuits. The second voltage-stabilizing capacitor C3.

[0067] Correspondingly, the present application also discloses a motor controller, which can apply any of the demagnetization current protection circuits described above.

[0068] A motor uses the motor controller described above.

[0069] In the description of the present invention, it should be understood that the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one of the features. In the description of the present invention, the meaning of "plurality" is at least two, such as two, three, etc., unless otherwise clearly and specifically defined.

[0070] In the present invention, unless otherwise clearly defined and limited, the terms "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral one; it can be a mechanical connection, an electrical connection, or communication with each other; it can be a direct connection, or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements, unless otherwise clearly defined. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0071] In the present utility model, unless otherwise clearly specified and limited, a first feature being "above" or "below" a second feature may mean that the first and second features are in direct contact, or the first and second features are in indirect contact through an intermediate medium. Moreover, a first feature being "above", "above" or "above" a second feature may mean that the first feature is directly above or obliquely above the second feature, or simply means that the first feature is higher in level than the second feature. A first feature being "below", "below" or "below" a second feature may mean that the first feature is directly below or obliquely below the second feature, or simply means that the first feature is lower in level than the second feature.

[0072] In the present utility model, if the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" appear, it means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the utility model. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art can combine and combine different embodiments or examples described in this specification and the features of different embodiments or examples without contradiction.

[0073] Although the embodiments of the present invention have been shown and described above, it can be understood that the above embodiments are exemplary and cannot be understood as limitations of the present invention. Ordinary technicians in the field can change, modify, replace and modify the above embodiments within the scope of the present invention.

[0074] In this specification, each embodiment is described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the embodiments can be referred to each other. For the device disclosed in the embodiment, since it corresponds to the method disclosed in the embodiment, the description is relatively simple, and the relevant parts can be referred to the method part.

[0075] The above description of the disclosed embodiments enables those skilled in the art to implement or use the present invention. Various modifications to these embodiments will be apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but will conform to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A demagnetization current protection circuit, characterized in that: include: A voltage sampling circuit, wherein the three input terminals of the voltage sampling circuit are respectively connected to the three bridge arms of the rectifier circuit in a one-to-one correspondence to collect voltage values ​​on the three bridge arms of the rectifier circuit, and the rectifier circuit is arranged between the motor inverter driver and the protected motor; A first comparison circuit, wherein an opposite-signal terminal of the first comparison circuit is connected to a first output terminal of the voltage sampling circuit; A second comparison circuit, wherein an opposite-signal terminal of the second comparison circuit is connected to a second output terminal of the voltage sampling circuit; a third comparison circuit, wherein the opposite-name terminal of the second comparison circuit is connected to the third output terminal of the voltage sampling circuit; Temperature sampling circuit, used to collect the actual temperature of the protected motor; A reference voltage generating circuit, wherein a first input end of the reference voltage generating circuit is connected to an output end of the temperature sampling circuit, a second input end of the reference voltage generating circuit is connected to the first comparison circuit, the third comparison circuit and an output end of the third comparison circuit, an output end of the reference voltage generating circuit is connected to the same-name ends of the first comparison circuit, the second comparison circuit and the third comparison circuit, and an output end of the reference voltage generating circuit is used to output a demagnetization protection voltage value generated at least based on a sampling result of the temperature sampling circuit.

2. The demagnetization current protection circuit according to claim 1, characterized in that: The voltage sampling circuit comprises: A first sampling resistor, a second sampling resistor, and a third sampling resistor; The first sampling resistor is arranged in series in the first bridge arm of the rectifier circuit, the first end of the first sampling resistor is connected to the switch tube in the first bridge arm, and the second end of the first sampling resistor is connected to the negative input end of the rectifier circuit; The second sampling resistor is arranged in series in the second bridge arm of the rectifier circuit, the first end of the second sampling resistor is connected to the switch tube in the second bridge arm, and the second end of the second sampling resistor is connected to the negative input end of the rectifier circuit; The third sampling resistor is arranged in series in the third bridge arm of the rectifier circuit, the first end of the third sampling resistor is connected to the switch tube in the third bridge arm, and the second end of the third sampling resistor is connected to the negative input end of the rectifier circuit.

3. The demagnetization current protection circuit according to claim 2, characterized in that: The voltage sampling circuit also includes: a first filtering circuit, a second filtering circuit and a third filtering circuit; The first filter circuit is arranged between the first sampling resistor and the first output end of the voltage sampling circuit; The second filter circuit is arranged between the second sampling resistor and the second output terminal of the voltage sampling circuit; The third filtering circuit is arranged between the third sampling resistor and the third output terminal of the voltage sampling circuit.

4. The demagnetization current protection circuit according to claim 1, characterized in that: Also includes: A voltage follower is provided between an output terminal of the reference voltage generating circuit and the same-name terminals of the first comparison circuit, the second comparison circuit and the third comparison circuit.

5. The demagnetization current protection circuit according to claim 1, characterized in that: The temperature sampling circuit is arranged on the housing of the protected motor or on a control circuit board.

6. The demagnetization current protection circuit according to claim 1, characterized in that: The reference voltage generating circuit comprises: Microprocessor and DAC circuit; The first input terminal of the microprocessor serves as the first input terminal of the reference voltage generating circuit, and the second input terminal of the microprocessor serves as the second input terminal of the reference voltage generating circuit; The output end of the DAC circuit serves as the output end of the reference voltage generating circuit; The output end of the microprocessor is connected to the input end of the DAC circuit, and the output end of the microprocessor is used to output a demagnetization protection voltage value generated at least based on the sampling result of the temperature sampling circuit.

7. The demagnetization current protection circuit according to claim 1, characterized in that: The rectifier circuit is a full-bridge rectifier circuit.

8. The demagnetization current protection circuit according to claim 4, characterized in that: Also includes: a first voltage stabilizing capacitor and a second voltage stabilizing capacitor; The first voltage stabilizing capacitor is connected to the output ends of the first comparison circuit, the second comparison circuit and the third comparison circuit; The second voltage stabilizing capacitor is connected to the output end of the follower.

9. A motor controller, characterized in that: The demagnetization current protection circuit according to any one of claims 1 to 8 is applied.

10. A motor, characterized in that: The motor controller according to claim 9 is used.

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