CN116154722A - Protection circuit of three-phase motor and protection method of three-phase motor - Google Patents
Protection circuit of three-phase motor and protection method of three-phase motor Download PDFInfo
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Abstract
The invention discloses a protection circuit of a three-phase motor and a protection method of the three-phase motor, relates to the technical field of motor protection, and aims to solve the problems that an existing protection scheme of the three-phase motor is slow in response time and occupies software and hardware resources of a main control platform. The protection circuit of the three-phase motor comprises: a driving sub-circuit, an abnormality detection sub-circuit, a logic judgment sub-circuit and a switching sub-circuit; the driving sub-circuit controls the first power supply to supply power to the three-phase motor based on the pulse width modulation signal; the abnormal detection sub-circuit detects working parameters of the three-phase motor in real time and outputs corresponding logic signals to the logic judgment sub-circuit; when the logic signal is an effective signal, the logic judging sub-circuit drives the switch sub-circuit to be conducted, so that the drive sub-circuit is in an off state, and the first power supply stops supplying power to the three-phase motor; when the logic signal is an invalid signal, the logic judging sub-circuit drives the switch sub-circuit to be turned off, so that the drive sub-circuit is in a conducting state, and the first power supply supplies power to the three-phase motor.
Description
Technical Field
The invention relates to the technical field of motor protection, in particular to a protection circuit of a three-phase motor and a protection method of the three-phase motor.
Background
The three-phase motor is used as one of the essential core devices in the household appliances and is mainly used for providing driving energy to enable corresponding mechanical equipment to normally operate. The three-phase motor is mainly composed of coil windings and other components, and when the motor is overloaded, such as under-voltage, over-current and/or over-temperature, winding faults can be caused, so that the motor works abnormally or is damaged.
At present, most of three-phase motor protection schemes in the industry need to be controlled through a main control platform of equipment, and the main control platform is controlled through software after relevant parameters of a motor are acquired so as to achieve the purpose of protecting the motor. And when the collected related parameters are judged to be abnormal in the main control platform, the main control platform can send out a response to take measures to correspondingly protect the three-phase motor. However, when the scheme is used for protecting the three-phase motor, the response time is slow, and the defect that software and hardware resources of a main control platform are occupied is also caused.
Disclosure of Invention
The invention aims to provide a protection circuit of a three-phase motor and a protection method of the three-phase motor, which are used for solving the problems that the response time of the existing protection scheme of the three-phase motor is slower and software and hardware resources of a main control platform are occupied.
In order to achieve the above object, the present invention provides the following technical solutions:
in a first aspect, the present invention provides a protection circuit for a three-phase motor, comprising: a driving sub-circuit, an abnormality detection sub-circuit, a logic judgment sub-circuit, and a switching sub-circuit, wherein:
the first power supply is electrically connected with the three-phase motor through a driving sub-circuit, the abnormality detection sub-circuit, the logic judgment sub-circuit and the input end of the switch sub-circuit are sequentially electrically connected, and the output end of the switch sub-circuit is also electrically connected with the driving sub-circuit;
a driving sub-circuit for controlling the first power supply to supply power to the three-phase motor based on the pulse width modulation signal;
the abnormality detection sub-circuit is used for detecting the working parameters of the three-phase motor in real time and outputting corresponding logic signals to the logic judgment sub-circuit;
the logic judgment sub-circuit is used for driving the switch sub-circuit to be conducted under the condition that the logic signal is an effective signal so as to enable the driving sub-circuit to be in an off state, and the first power supply stops supplying power to the three-phase motor;
the logic judgment sub-circuit is used for driving the switch sub-circuit to be turned off under the condition that the logic signal is an invalid signal so as to enable the driving sub-circuit to be in a conducting state, and the first power supply supplies power to the three-phase motor normally.
Compared with the prior art, in the protection circuit of the three-phase motor, the driving sub-circuit is used for controlling the first power supply to supply power to the three-phase motor according to the pulse width modulation signal. The abnormality detection sub-circuit is used for detecting working parameters of the three-phase motor so as to output corresponding logic signals to the logic judgment sub-circuit in real time. When the working parameters detected by the abnormality detection sub-circuit are not consistent with the preset parameters, the abnormal working parameters can be determined, at the moment, the logic signals output by the abnormality detection sub-circuit to the logic judgment sub-circuit are effective signals, and the logic judgment sub-circuit can drive the switch sub-circuit to be conducted based on the effective signals, so that the drive sub-circuit is in an off state, the first power supply cannot supply power to the three-phase motor, namely, the purpose that the first power supply stops supplying power to the three-phase motor is achieved, the three-phase motor stops working, windings in the three-phase motor can be prevented from being damaged, and real-time protection of the three-phase motor is achieved. When the working parameter abnormality is not detected or the abnormal state disappears, the abnormality detection sub-circuit outputs a logic signal to the logic judgment sub-circuit as an invalid signal, and the logic judgment sub-circuit can drive the switch sub-circuit to be turned off based on the invalid signal, so that the drive sub-circuit is in a conducting state, and the first power supply can normally supply power to the three-phase motor under the condition that the drive sub-circuit is conducted, so that the three-phase motor can normally work. Based on the above, the protection circuit of the three-phase motor provided by the invention can grasp the working state of the three-phase motor in real time by detecting the working parameters of the three-phase motor. When an abnormality occurs, the switch sub-circuit is controlled to be turned off to drive the sub-circuit in real time, so that the three-phase motor can stop working.
From the above, the protection circuit of the three-phase motor provided by the invention can realize real-time protection of the three-phase motor without a main control platform of the device, so that not only does not occupy software and hardware resources of the main control platform, but also the response time is faster, and the problems in the prior art can be solved.
In a second aspect, the present invention further provides a protection method for a three-phase motor, which is applied to the protection circuit for a three-phase motor according to the above technical solution, where the protection method for a three-phase motor includes:
the driving sub-circuit controls the first power supply to supply power to the three-phase motor based on the pulse width modulation signal;
the abnormal detection sub-circuit detects working parameters of the three-phase motor and outputs corresponding logic signals to the logic judgment sub-circuit;
the logic judgment sub-circuit drives the switch sub-circuit to be conducted under the condition that the logic signal is an effective signal, so that the drive sub-circuit is in an off state, and the first power supply stops supplying power to the three-phase motor;
and under the condition that the logic signal is an invalid signal, the logic judging sub-circuit drives the switch sub-circuit to be turned off so that the driving sub-circuit is in a conducting state, and the first power supply supplies power to the three-phase motor normally.
Compared with the prior art, the protection method of the three-phase motor has the same beneficial effects as the protection circuit of the three-phase motor in the technical scheme, and the description is omitted here.
Drawings
The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and together with the description serve to explain the invention and do not constitute a limitation on the invention. In the drawings:
fig. 1 is a circuit schematic diagram of a protection circuit of a three-phase motor according to an embodiment of the present invention.
Reference numerals:
a 1-drive sub-circuit, a 2-abnormality detection sub-circuit,
a 3-logic determination sub-circuit, a 4-switching sub-circuit,
a 5-three-phase motor, an 11-pulse width modulation module,
a 12-half-bridge pre-drive module, a 13-transistor drive module,
121-half-bridge pre-drive unit, 131-transistor drive unit,
21-an over-temperature detection module, 22-an over-current detection module,
221-overcurrent detection unit, 23-voltage detection module.
Description of the embodiments
In order to clearly describe the technical solution of the embodiments of the present invention, in the embodiments of the present invention, the words "first", "second", etc. are used to distinguish the same item or similar items having substantially the same function and effect. For example, the first threshold and the second threshold are merely for distinguishing between different thresholds, and are not limited in order. It will be appreciated by those of skill in the art that the words "first," "second," and the like do not limit the amount and order of execution, and that the words "first," "second," and the like do not necessarily differ.
In the present invention, the words "exemplary" or "such as" are used to mean serving as an example, instance, or illustration. Any embodiment or design described herein as "exemplary" or "for example" should not be construed as preferred or advantageous over other embodiments or designs. Rather, the use of words such as "exemplary" or "such as" is intended to present related concepts in a concrete fashion.
In the present invention, "at least one" means one or more, and "a plurality" means two or more. "and/or", describes an association relationship of an association object, and indicates that there may be three relationships, for example, a and/or B, and may indicate: a alone, a and B together, and B alone, wherein a, B may be singular or plural. The character "/" generally indicates that the context-dependent object is an "or" relationship. "at least one of" or the like means any combination of these items, including any combination of single item(s) or plural items(s). For example, at least one (one) of a, b or c may represent: a, b, c, a and b, a and c, b and c, or a, b and c, wherein a, b, c can be single or multiple.
Along with the rapid development of social economy and the continuous improvement of the living standard of people, the pursuit of people on quality life is gradually increased, the varieties of household appliances are more and more, and the household appliances are comprehensively integrated into the daily life of the families of people. As one of essential core devices in home appliances, the interior thereof is mainly composed of components such as coil windings, etc., to provide driving power for proper operation of the corresponding mechanical devices. When the motor is overloaded, such as under-voltage, over-current and/or over-temperature, the winding can be caused to fail, thereby causing abnormal or damaged motor operation.
In the prior art, most of three-phase motor protection schemes realize the purpose of protecting the motor through software control after a main control platform of equipment collects relevant parameters of the motor. When the main control platform judges that the related parameters are abnormal, the main control platform can send out a response and take corresponding protective measures to protect the three-phase motor. The scheme not only needs to occupy software and hardware resources of the main control platform, but also has slower response time, and cannot realize real-time protection on the three-phase motor.
In order to solve the above technical problems, as shown in fig. 1, an embodiment of the present invention provides a protection circuit for a three-phase motor, including: a driving sub-circuit 1, an abnormality detection sub-circuit 2, a logic judgment sub-circuit 3, and a switching sub-circuit 4, wherein:
the first power supply VCCA is electrically connected with the three-phase motor 5 through the driving sub-circuit 1, the abnormality detection sub-circuit 2, the logic judgment sub-circuit 3 and the input end of the switch sub-circuit 4 are sequentially electrically connected, and the output end of the switch sub-circuit 4 is also electrically connected with the driving sub-circuit 1;
a driving sub-circuit 1 for controlling the first power supply VCCA to supply power to the three-phase motor 5 based on the pulse width modulation signal;
the abnormality detection sub-circuit 2 is used for detecting the working parameters of the three-phase motor 5 in real time and outputting corresponding logic signals to the logic judgment sub-circuit 3;
the logic judgment sub-circuit 3 is used for driving the switch sub-circuit 4 to be conducted under the condition that the logic signal is an effective signal so as to enable the drive sub-circuit 1 to be in an off state, and the first power supply VCCA stops supplying power to the three-phase motor 5;
the logic judgment sub-circuit 3 is used for turning off the driving switch sub-circuit 4 under the condition that the logic signal is an invalid signal, so that the driving sub-circuit 1 is in a conducting state, and the first power supply VCCA supplies power to the three-phase motor 5 normally.
It should be appreciated that the first power source VCCA may be an industrial power dedicated to the three-phase motor 5, specifically 380V (volt) ac power.
In the present application, the above-mentioned operation parameters include at least a current parameter, a voltage parameter, and a temperature parameter when the three-phase motor is operated, and when any one of the following is satisfied, the abnormality detection sub-circuit 2 may output a valid logic signal to the logic determination sub-circuit 3. For example: the current parameter exceeds the standard current, and/or the voltage parameter is below the minimum value of the standard voltage range, and/or the voltage parameter exceeds the maximum value of the standard voltage range, and/or the temperature parameter exceeds the range of the standard temperature, which is not particularly limited in the embodiments of the present invention.
As is known from the structure of the protection circuit of the three-phase motor, the driving sub-circuit 1 is configured to control the power supply of the first power supply VCCA to the three-phase motor 5 according to the pulse width modulation signal. The abnormality detection sub-circuit 2 is configured to detect an operating parameter of the three-phase motor 5, so as to output a corresponding logic signal to the logic determination sub-circuit 3 in real time. When the working parameter detected by the abnormality detection sub-circuit 2 is not consistent with the preset parameter, it can be determined that the working parameter is abnormal, at this time, the logic signal output by the abnormality detection sub-circuit 2 to the logic judgment sub-circuit 3 is an effective signal, and based on the effective signal, the logic judgment sub-circuit 3 can drive the switch sub-circuit 4 to be turned on, so that the drive sub-circuit 1 is in a turned-off state, the first power supply VCCA cannot supply power to the three-phase motor 5, that is, the purpose that the first power supply VCCA stops supplying power to the three-phase motor 5 is achieved, the three-phase motor 5 stops working, the winding in the three-phase motor 5 can be prevented from being damaged, and then real-time protection of the three-phase motor 5 is achieved. When the abnormality of the working parameter is not detected or the abnormal state disappears, the abnormality detection sub-circuit 2 outputs a logic signal to the logic judgment sub-circuit 3 as an invalid signal, and based on the invalid signal, the logic judgment sub-circuit 3 can drive the switch sub-circuit 4 to be turned off, so that the drive sub-circuit 1 is in a conducting state, and under the condition that the drive sub-circuit 1 is conducted, the first power supply VCCA can normally supply power to the three-phase motor 5, so that the three-phase motor 5 can normally work. Based on this, the protection circuit for the three-phase motor provided by the embodiment of the invention can grasp the working state of the three-phase motor 5 in real time by detecting the working parameters of the three-phase motor 5. When an abnormality occurs, the real-time control switch sub-circuit 4 turns off the drive sub-circuit 1 so that the three-phase motor 5 can stop operating.
As can be seen from the above, the protection circuit for the three-phase motor provided by the embodiment of the invention can realize real-time protection of the three-phase motor 5 without a main control platform of the device, so that not only does not occupy software and hardware resources of the main control platform, but also the response time is faster, and the problems existing in the prior art can be solved.
In one possible implementation, the driving sub-circuit 1 includes a pulse width modulation module 11, a half-bridge pre-driving module 12, and a transistor driving module 13 electrically connected in sequence;
the output end of the switch sub-circuit 4 is electrically connected with the half-bridge pre-driving module 12, the second power supply VCCB is grounded through the switch sub-circuit 4, the second power supply VCCB is also electrically connected with the input end of the half-bridge pre-driving module 12 through the switch sub-circuit 4, and the first power supply VCCA is electrically connected with the three-phase motor 5 through the transistor driving module 13, wherein:
a pulse width modulation module 11 for providing a pulse width modulation signal to the half-bridge pre-drive module 12;
when the switch sub-circuit 4 is in a conducting state, the half-bridge pre-driving module 12 is used for controlling the transistor driving module 13 to be turned off under the action of the switch sub-circuit 4 so as to control the first power supply VCCA to stop supplying power to the three-phase motor 5;
when the switch sub-circuit 4 is in the off state, the half-bridge pre-driving module 12 is configured to control the transistor driving module 13 to be turned on based on the accessed second power supply voltage in combination with the pulse width modulation signal, so as to control the first power supply VCCA to normally supply power to the three-phase motor 5.
In the present application, the pulse width modulation module 11 may be a pulse width modulation (Pulse Width Modulation, PWM) controller, which is configured to provide a standard PWM signal, for example, a voltage signal of 3.3V or 5V, to the half-bridge pre-driving module 12 to drive the half-bridge pre-driving module 12 to be turned on. It should be appreciated that the second power supply voltage should be matched to the threshold voltage of the transistor driving module 13, so that the driving signal output by the half-bridge pre-driving module 12 based on the second power supply voltage may turn on the transistor driving module 13. For example, the second power supply voltage may be 15V, which is not particularly limited in the embodiment of the present invention.
When the switch sub-circuit 4 is in an off state, the second power supply VCCB is disconnected from the ground terminal, and the half-bridge pre-driving module 12 outputs a PWM-modulated driving signal based on the accessed second power supply voltage, at this time, the amplitude of the driving signal is equal to the second power supply voltage VCCB, so that the transistor driving module 13 can be controlled to be turned on, so that the first power supply VCCA can normally supply power to the three-phase motor 5 through the transistor driving module 13, and 380V of alternating voltage and large current can be provided for normal operation of the three-phase motor 5.
When the switch sub-circuit 4 is in the on state, the second power VCCB is grounded through the switch sub-circuit 4, that is, the potential of the second power VCCB is pulled down, and the actual voltage output to the half-bridge pre-driving module 12 is smaller than the second power voltage. When the half-bridge pre-driving module 12 receives the pulled-down second power supply voltage, the half-bridge pre-driving module 12 stops working, so that the transistor driving module 13 cannot be turned on, the transistor driving module 13 is in a turned-off state, and the first power supply VCCA cannot supply power to the three-phase motor 5 through the turned-off transistor driving module 13, so that the three-phase motor 5 can stop working.
In some embodiments, the half-bridge pre-drive module 12 includes three half-bridge pre-drive units 121, and the transistor drive module 13 includes three transistor drive units 131, wherein:
the input end of each half-bridge pre-driving unit 121 is electrically connected with the output end of the pulse width modulation module 11, the output end of each half-bridge pre-driving unit 121 is respectively and correspondingly connected with the input end of the corresponding transistor driving unit 131 one by one, and the first power supply VCCA is respectively and electrically connected with the three-phase motor 5 through each transistor driving unit 131;
when the switch sub-circuit 4 is in an off state, each half-bridge pre-driving unit 121 is configured to control the corresponding transistor driving unit 131 to be turned on, so as to respectively control the first power supply VCCA to provide voltages of three phases to the three-phase motor 5;
when the switching sub-circuit 4 is in an on state, each half-bridge pre-driving unit 121 is configured to control the corresponding transistor driving unit 131 to be turned off, so as to control the first power VCCA to stop supplying voltages of three phases to the three-phase motor 5.
It should be understood that, in order to match voltages of three phases of the three-Phase motor 5, such as a U-Phase voltage (U-Phase), a V-Phase voltage (V-Phase), and a W-Phase voltage (W-Phase), the half-bridge pre-driving module 12 should include three half-bridge pre-driving units 121, and the transistor driving module 13 includes three transistor driving units 131, and the half-bridge pre-driving units 121 are in one-to-one correspondence with the transistor driving units 131, so as to control the first power VCCA to supply voltages of three phases to the three-Phase motor 5.
Referring to fig. 1, each half-bridge pre-driving unit 121 includes a half-bridge pre-driving chip U and a diode D, and a capacitor C, for example, the half-bridge pre-driving chip U1, the half-bridge pre-driving chip U2, and the half-bridge pre-driving chip U3, the diode D1 and the capacitor C1, the diode D2 and the capacitor C2, and the diode D3 and the capacitor C3 are respectively connected with the corresponding half-bridge pre-driving chips in a one-to-one correspondence manner, so as to ensure that the half-bridge pre-driving chips can work normally.
Each transistor driving unit 131 comprises two insulated gate bipolar transistors (Insulated Gate Bipolar Transistor, IGBTs) and a first base resistor and a second base resistor, and the IGBT transistors have the characteristics of small driving power, reduced saturation voltage, high current and high speed. It can be appreciated that since each half-bridge pre-drive chip U is electrically connected to the gate of the pull-up transistor only through the corresponding first base resistor to individually control whether the pull-up transistor is turned on or not, and is also electrically connected to the gate of the pull-down transistor through the corresponding second base resistor to individually control whether the pull-down transistor is turned on or not, in the transistor driving unit 131, the pull-up transistor and the pull-down transistor are alternately turned on or not.
Taking the transistor driving unit 131 corresponding to the U-Phase as an example, as shown in fig. 1, the half-bridge pre-driving chip U1 is electrically connected to the base of the transistor Q1 through the first base resistor R1, the collector of the transistor Q1 is electrically connected to the first power supply VCCA, the emitter of the transistor Q1 is electrically connected to the collector of the transistor Q2, and the emitter of the transistor Q1 is also electrically connected to the three-Phase motor 5 for providing the U-Phase to the three-Phase motor 5. The half-bridge pre-driving chip U1 is electrically connected with the base electrode of the transistor Q2 through a second base electrode resistor R2, and the emitter electrode of the transistor Q2 is grounded.
Similarly, the transistor driving unit 131 corresponding to V-Phase includes a third base resistor R3, a fourth base resistor R4, a transistor Q3 and a transistor Q4, and the transistor driving unit 131 corresponding to W-Phase includes a fifth base resistor R5, a sixth base resistor R6, a transistor Q5 and a transistor Q6, and the connection manners thereof are consistent with those of the transistor driving unit 131 corresponding to U-Phase, which are not described herein.
In some embodiments, the anomaly detection sub-circuit 2 includes an over-temperature detection module 21, an over-current detection module 22, and a voltage detection module 23, wherein:
the input end of the over-temperature detection module 21 is electrically connected with the second power supply VCCB, and the output end of the over-temperature detection module 21 is electrically connected with the input end of the logic judgment sub-circuit 3 and is used for detecting the temperature parameter of the three-phase motor 5 during operation;
the input end of the overcurrent detection module 22 is electrically connected with the transistor driving module 13, and the output end of the overcurrent detection module 22 is electrically connected with the input end of the logic judgment sub-circuit 3 and is used for detecting current parameters when the three-phase motor 5 works;
the input end of the voltage detection module 23 is electrically connected with the first power supply VCCA, and the output end of the voltage detection module 23 is electrically connected with the input end of the logic judgment sub-circuit 3, and is used for detecting the voltage parameter of the three-phase motor 5 during operation.
Specifically, the over-temperature detection module 21 is configured to detect a temperature parameter of the three-phase motor 5 during operation, so as to determine whether the current operating temperature of the three-phase motor 5 exceeds a standard temperature. When the current operating temperature exceeds the standard temperature range, the over-temperature detection module 21 outputs a valid logic signal to the logic determination sub-circuit 3, and otherwise outputs an invalid logic signal.
The overcurrent detection module 22 is configured to detect a current parameter when the three-phase motor 5 is operating, so as to determine whether the current operating current of the three-phase motor 5 is within a standard current range. When the current operating current exceeds the standard current range, the overcurrent detection module 22 outputs a valid logic signal to the logic determination sub-circuit 3, and otherwise outputs an invalid logic signal.
The voltage detection module 23 is configured to detect a voltage parameter of the three-phase motor 5 during operation to determine whether the current operating voltage of the three-phase motor 5 exceeds a maximum value exceeding a standard voltage range or falls below a minimum value of the standard voltage range. The current operating voltage exceeds the maximum value of the standard voltage range or is lower than the minimum value of the standard voltage range. When the voltage detection module 23 outputs a valid logic signal to the logic determination sub-circuit 3, an invalid logic signal is output, otherwise.
In one example, the over-temperature detection module 21 includes a first comparator A1, a first voltage dividing resistor R9, and a thermistor R10, wherein:
the second power supply VCCB is electrically connected with the non-inverting input end of the first comparator A1 through a first voltage dividing resistor R9, and the second end of the first voltage dividing resistor R9 is grounded through a thermistor R10;
the inverting input terminal of the first comparator A1 is used for accessing the first reference voltage Vref1, and the output terminal of the first comparator is electrically connected with the input terminal of the logic judgment sub-circuit 3.
Specifically, the thermistor R10 may be a positive thermistor, that is, a resistor having a resistance value proportional to temperature, and the resistance value increases with an increase in ambient temperature. Along with the temperature change, the environmental temperature of the three-phase motor during working can be calculated through the partial pressure value of the first partial pressure resistor R9 and the thermistor R10, and the value range of the first reference voltage Vref1 can be set according to the standard temperature range, which is not particularly limited in the embodiment of the invention. When the ambient temperature increases, the resistance value of the thermistor R10 also increases, that is, the voltage at both ends of the thermistor R10 also increases, the voltage at the positive input end of the first comparator A1 also increases, and when the voltage at the positive input end of the first comparator A1 is greater than the first reference voltage Vref1 at the negative input end, it can be determined that the ambient temperature at that time exceeds the standard temperature range, and it is determined that an over-temperature phenomenon currently occurs, the first comparator A1 outputs a valid logic signal to the logic determination sub-circuit 3, and otherwise, the first comparator A1 outputs an invalid logic signal to the logic determination sub-circuit 3.
In one example, the overcurrent detection module 22 includes two overcurrent detection units 221, where both the two overcurrent detection units 221 are electrically connected to the transistor driving module 13 and are used to detect current parameters of any two phases when the three-phase motor 5 works;
each of the overcurrent detection units 221 includes a sampling resistor, a second comparator, a first resistor, a second resistor, a third resistor, and a fourth resistor, wherein:
the transistor driving module 13 is grounded through a sampling resistor, a first end of the sampling resistor is electrically connected with the transistor driving module 13, and a second end of the sampling resistor is grounded;
the first end of the sampling resistor is also electrically connected with the non-inverting input end of the second comparator through the first resistor, the second power supply VCCB is electrically connected with the non-inverting input end of the second comparator through the second resistor, the second power supply VCCB is electrically connected with the inverting input end of the second comparator through the third resistor, the second end of the sampling resistor is also electrically connected with the inverting input end of the second comparator through the fourth resistor, and the output end of the second comparator is electrically connected with the input end of the logic judgment sub-circuit 3.
In practice, since the sum of the three-phase branch currents of the three-phase motor 5 is zero, it is only necessary to sample the current value of any two of the three-phase branches, so as to determine whether the current parameter of the three-phase motor 5 is in the normal range. For example, only the transistor driving unit 131 corresponding to U-Phase and the transistor driving unit 131 corresponding to V-Phase may be subjected to current detection, and the two overcurrent detecting units 221 may be connected to the transistor driving unit 131 corresponding to U-Phase and the transistor driving unit 131 corresponding to V-Phase in one-to-one correspondence. Based on this, a sampling resistor R7 may be connected between the emitter of the transistor Q2 and the ground terminal, and a sampling resistor R8 may be connected between the emitter of the transistor Q4 and the ground terminal, so as to implement detection of the current parameter during operation of the three-phase motor 5 by detecting the current parameter at both ends of the sampling resistor.
Specifically, taking the over-current detection unit 221 corresponding to the U-Phase as an example, the over-current detection unit 221 includes a sampling resistor R7, a second comparator A2, a first resistor R11, a second resistor R12, a third resistor R13, and a fourth resistor R14, where Va represents the voltage at the first end of the sampling resistor R7, vb represents the voltage at the second end of the sampling resistor R7, VP1 represents the voltage at the non-inverting input end of the second comparator, VN1 represents the voltage at the inverting input end of the second comparator, and VN 1=vp 1 is known from the short and broken states, since Vb is the ground end, according to the resistance voltage division, the following formula can be obtained:
；
and because the current flowing through the first resistor R11 is equal to the current flowing through the second resistor R12
；
Thus, the first and second substrates are bonded together,
；
as can be seen from the current flowing through the sampling resistor R7 is i1=va/R7, the current I1 at the overcurrent point is:
。
similarly, in the over-current detection unit 221 corresponding to V-Phase, the over-current detection unit 221 includes a sampling resistor R8, a second comparator A2, a first resistor R15, a second resistor R16, a third resistor R17, and a fourth resistor R18, where Vc represents the voltage at the first end of the sampling resistor R8, vd represents the voltage at the second end of the sampling resistor R8, VP2 represents the voltage at the non-inverting input end of the third comparator, VN2 represents the voltage at the inverting input end of the second comparator, and the current I2 at the over-current point in the over-current detection unit 221 corresponding to V-Phase may be expressed as:
。
as is clear from the above, when the overcurrent detecting unit 221 detects that the current operating current exceeds the current I1 or I2 of the overcurrent point, it is determined that the overcurrent phenomenon currently occurs, the second comparator A2 outputs a valid logic signal to the logic determination sub-circuit 3, and otherwise, the second comparator A2 outputs an invalid logic signal to the logic determination sub-circuit 3.
In one example, the voltage detection module 23 includes a third comparator A3, a fourth comparator A4, a second voltage dividing resistor R19, and a third voltage dividing resistor R20, wherein:
the first power supply VCCA is respectively and electrically connected with an inverting input end of the third comparator A3 and a non-inverting input end of the fourth comparator A4 through a second voltage dividing resistor R19, the non-inverting input end of the third comparator A3 is used for accessing the second reference voltage Vref2, the inverting input end of the fourth comparator A4 is used for accessing the third reference voltage Vref2, and the output end of the third comparator A3 and the output end of the fourth comparator A4 are electrically connected with the input end of the logic judgment sub-circuit 3; the first power supply VCCA is also grounded through the second voltage dividing resistor R19 and the third voltage dividing resistor R20 in sequence.
Specifically, when the voltage at the inverting input terminal of the third comparator A3 is smaller than the voltage at the non-inverting input terminal of the third comparator A3, it is determined that the undervoltage phenomenon currently occurs, the third comparator A3 outputs a valid logic signal to the logic determination sub-circuit 3, and otherwise, the third comparator A3 outputs an invalid logic signal to the logic determination sub-circuit 3.
When the voltage at the non-inverting input terminal of the fourth comparator A4 is smaller than the voltage at the inverting input terminal of the fourth comparator A4, it is determined that the undervoltage phenomenon currently occurs, the fourth comparator A4 outputs a valid logic signal to the logic determination sub-circuit 3, and otherwise, the fourth comparator A4 outputs an invalid logic signal to the logic determination sub-circuit 3.
In one example, the logic determination subcircuit 3 includes at least one OR gate. Among the logic signals outputted from the over-temperature detection module 21, the over-current detection module 22, and the voltage detection module 23, when at least one logic signal is a valid signal, the or gate is used to control the switch sub-circuit 4 to be turned on based on the valid signal, so that the driving sub-circuit 1 is in an off state. When the logic signals output by the over-temperature detection module 21, the over-current detection module 22 and the voltage detection module 23 are all inactive signals, the or gate is used for controlling the switch sub-circuit 4 to be turned off based on the inactive signals, so that the driving sub-circuit 1 is in a conducting state.
It should be appreciated that an or gate acts as a basic logic circuit in a digital circuit. Having at least two inputs and an output, the circuit output is low (logic "0") only if all inputs are low (logic "0"), otherwise the output is high (logic "1").
Therefore, a low level (logic "0") may be used as an inactive signal, and a high level (logic "1") may be used as an active signal. Among the logic signals outputted from the over-temperature detection module 21, the over-current detection module 22, and the voltage detection module 23, when at least one logic signal is at a high level (logic "1"), the or gate may output a high level (logic "1"), thereby controlling the switching sub-circuit 4 to be turned on to put the driving sub-circuit 1 in an off state. When the logic signals output from the over-temperature detection module 21, the over-current detection module 22 and the voltage detection module 23 are all low level (logic "0"), the or gate outputs low level (logic "0"), so that the switch sub-circuit 4 is controlled to be turned off to make the driving sub-circuit 1 be in an on state.
Illustratively, the truth table of the over-temperature detection module 21 is shown in Table one below:
list one
The truth table of the overcurrent detection module 22 is shown in table two below:
watch II
The truth table of the voltage detection module 23 is shown in table three below:
watch III
In some embodiments, the switching sub-circuit 4 includes a transistor Q7, a fourth voltage dividing resistor R21 and a fifth voltage dividing resistor R22, the base of the transistor Q7 is electrically connected to the output terminal of the logic determination sub-circuit 3, the second power VCCB is electrically connected to the collector of the transistor Q7 through the fourth voltage dividing resistor R21, the emitter of the transistor Q7 is grounded through the fifth voltage dividing resistor R22, and the second power VCCB is also electrically connected to the input terminal of the half-bridge pre-driving module 12 through the fourth voltage dividing resistor R21.
Therefore, when the base of the transistor Q7 receives the high level (logic "1") output by the logic determination sub-circuit 3, the transistor Q7 is turned on, the voltage of the second power VCCB is set to the low level through the fourth voltage dividing resistor R21, the transistor Q7 and the fifth voltage dividing resistor R22, and when the half-bridge pre-driving module 12 receives the second power VCCB after being pulled down, the half-bridge pre-driving module 12 stops working, so that the transistor driving module 13 cannot be turned on, and the first power VCCA cannot supply power to the three-phase motor 5 through the transistor driving module 13.
When the abnormal state disappears and the base of the transistor Q7 receives the low level (logic "0") output by the logic determination sub-circuit 3, the transistor Q7 is turned off, the voltage of the second power VCCB may be directly input to the half-bridge pre-driving module 12 through the fourth voltage dividing resistor R21, after the voltage of the second power VCCB is modulated by the half-bridge pre-driving module 12, the voltage of the output driving signal matches the threshold voltage of the transistor driving module 13, and the transistor driving module 13 may be turned on, so that the first power VCCA may supply power to the three-phase motor 5 through the transistor driving module 13.
The embodiment of the invention also provides a protection method for the three-phase motor, which is applied to the protection circuit for the three-phase motor, and comprises the following steps:
the driving sub-circuit 1 controls the first power supply VCCA to supply power to the three-phase motor 5 based on the pulse width modulation signal;
the abnormality detection sub-circuit 2 detects the working parameters of the three-phase motor 5 in real time and outputs corresponding logic signals to the logic judgment sub-circuit 3;
the logic judgment sub-circuit 3 drives the switch sub-circuit 4 to be conducted under the condition that the logic signal is an effective signal, so that the drive sub-circuit 1 is in an off state, and the first power supply VCCA stops supplying power to the three-phase motor 5;
when the logic signal is an invalid signal, the logic judgment sub-circuit 3 drives the switch sub-circuit 4 to be turned off, so that the drive sub-circuit 1 is in a conducting state, and the first power supply VCCA supplies power to the three-phase motor 5 normally.
Compared with the prior art, the protection method of the three-phase motor has the same beneficial effects as the protection circuit of the three-phase motor in the above embodiment, and is not repeated here.
Although the invention is described herein in connection with various embodiments, other variations to the disclosed embodiments can be understood and effected by those skilled in the art in practicing the claimed invention, from a study of the drawings, the disclosure, and the appended claims. In the claims, the word "comprising" does not exclude other elements or steps, and the "a" or "an" does not exclude a plurality. A single processor or other unit may fulfill the functions of several items recited in the claims. The mere fact that certain measures are recited in mutually different dependent claims does not indicate that a combination of these measures cannot be used to advantage.
Although the invention has been described in connection with specific features and embodiments thereof, it will be apparent that various modifications and combinations can be made without departing from the spirit and scope of the invention. Accordingly, the specification and drawings are merely exemplary illustrations of the present invention as defined in the appended claims and are considered to cover any and all modifications, variations, combinations, or equivalents that fall within the scope of the invention. It will be apparent to those skilled in the art that various modifications and variations can be made to the present invention without departing from the spirit or scope of the invention. Thus, it is intended that the present invention also include such modifications and alterations insofar as they come within the scope of the appended claims or the equivalents thereof.
Claims (10)
1. A protection circuit for a three-phase motor, comprising: a driving sub-circuit, an abnormality detection sub-circuit, a logic judgment sub-circuit, and a switching sub-circuit, wherein:
the first power supply is electrically connected with the three-phase motor through the driving sub-circuit, the abnormality detection sub-circuit, the logic judgment sub-circuit and the input end of the switch sub-circuit are sequentially electrically connected, and the output end of the switch sub-circuit is also electrically connected with the driving sub-circuit;
the driving sub-circuit is used for controlling the first power supply to supply power to the three-phase motor based on a pulse width modulation signal;
the abnormality detection sub-circuit is used for detecting the working parameters of the three-phase motor in real time and outputting corresponding logic signals to the logic judgment sub-circuit;
the logic judgment sub-circuit is used for driving the switch sub-circuit to be conducted under the condition that the logic signal is an effective signal so as to enable the driving sub-circuit to be in an off state, and the first power supply stops supplying power to the three-phase motor;
the logic judgment sub-circuit is used for driving the switch sub-circuit to be turned off under the condition that the logic signal is an invalid signal so as to enable the driving sub-circuit to be in a conducting state, and the first power supply is used for normally supplying power to the three-phase motor.
2. The protection circuit of a three-phase motor according to claim 1, wherein the driving sub-circuit comprises a pulse width modulation module, a half-bridge pre-driving module and a transistor driving module electrically connected in sequence;
the output of switch sub-circuit with half-bridge is driven the module electricity in advance and is connected, and the second power passes through switch sub-circuit ground connection, the second power still passes through switch sub-circuit with half-bridge is driven the input of module electricity in advance and is connected, first power passes through transistor drive module with three-phase motor electricity is connected, wherein:
the pulse width modulation module is used for providing the pulse width modulation signal for the half-bridge pre-driving module;
when the switch sub-circuit is in a conducting state, the half-bridge pre-driving module is used for controlling the transistor driving module to be turned off under the action of the switch sub-circuit so as to control the first power supply to stop supplying power to the three-phase motor;
when the switch sub-circuit is in an off state, the half-bridge pre-driving module is used for controlling the transistor driving module to be conducted based on the accessed second power supply voltage and the pulse width modulation signal so as to control the first power supply to normally supply power to the three-phase motor.
3. The protection circuit of a three-phase motor according to claim 2, wherein the half-bridge pre-drive module includes three half-bridge pre-drive units, and the transistor drive module includes three transistor drive units, wherein:
the input end of each half-bridge pre-driving unit is electrically connected with the output end of the pulse width modulation module, the output end of each half-bridge pre-driving unit is respectively and correspondingly connected with the input end of the corresponding transistor driving unit one by one, and the first power supply is respectively and electrically connected with the three-phase motor through each transistor driving unit;
when the switch sub-circuit is in an off state, each half-bridge pre-driving unit is used for controlling the corresponding transistor driving unit to be conducted so as to respectively control the first power supply to provide three-phase voltages for the three-phase motor;
when the switch sub-circuits are in a conducting state, each half-bridge pre-driving unit is used for controlling the corresponding transistor driving unit to be turned off so as to control the first power supply to stop providing voltages of three phases for the three-phase motor.
4. The protection circuit of a three-phase motor according to claim 2, wherein the abnormality detection sub-circuit includes an over-temperature detection module, an over-current detection module, and a voltage detection module, wherein:
the input end of the over-temperature detection module is electrically connected with the second power supply, and the output end of the over-temperature detection module is electrically connected with the input end of the logic judgment sub-circuit and is used for detecting the temperature parameter of the three-phase motor during operation;
the input end of the overcurrent detection module is electrically connected with the transistor driving module, and the output end of the overcurrent detection module is electrically connected with the input end of the logic judgment sub-circuit and is used for detecting current parameters when the three-phase motor works;
the input end of the voltage detection module is electrically connected with the first power supply, and the output end of the voltage detection module is electrically connected with the input end of the logic judgment sub-circuit and is used for detecting voltage parameters when the three-phase motor works.
5. The protection circuit of the three-phase motor according to claim 4, wherein the over-temperature detection module comprises a first comparator, a first voltage dividing resistor, and a thermistor, wherein:
the second power supply is electrically connected with the non-inverting input end of the first comparator through a first voltage dividing resistor, and the second end of the first voltage dividing resistor is grounded through the thermistor;
the inverting input end of the first comparator is used for accessing a first reference voltage, and the output end of the first comparator is electrically connected with the input end of the logic judgment sub-circuit.
6. The protection circuit of a three-phase motor according to claim 4, wherein the overcurrent detection module comprises two overcurrent detection units, and the two overcurrent detection units are electrically connected with the transistor driving module and are used for detecting current parameters of any two phases when the three-phase motor works;
each overcurrent detection unit comprises a sampling resistor, a second comparator, a first resistor, a second resistor, a third resistor and a fourth resistor, wherein:
the transistor driving module is grounded through the sampling resistor, a first end of the sampling resistor is electrically connected with the transistor driving module, and a second end of the sampling resistor is grounded;
the first end of the sampling resistor is also electrically connected with the normal phase input end of the second comparator through the first resistor, the second power supply is electrically connected with the normal phase input end of the second comparator through the second resistor, the second power supply is electrically connected with the reverse phase input end of the second comparator through the third resistor, the second end of the sampling resistor is also electrically connected with the reverse phase input end of the second comparator through the fourth resistor, and the output end of the second comparator is electrically connected with the input end of the logic judgment sub-circuit.
7. The protection circuit of a three-phase motor of claim 4, wherein the voltage detection module comprises a third comparator, a fourth comparator, a second voltage divider resistor, and a third voltage divider resistor, wherein:
the first power supply is respectively and electrically connected with the inverting input end of the third comparator and the non-inverting input end of the fourth comparator through the second voltage dividing resistor, the non-inverting input end of the third comparator is used for accessing the second reference voltage, the inverting input end of the fourth comparator is used for accessing the third reference voltage, and the output end of the third comparator and the output end of the fourth comparator are electrically connected with the input end of the logic judgment sub-circuit;
the first power supply is grounded through the second voltage dividing resistor and the third voltage dividing resistor in sequence.
8. The protection circuit of a three-phase motor according to claim 4, wherein the logic determination sub-circuit includes at least one or gate;
in the logic signals output by the over-temperature detection module, the over-current detection module and the voltage detection module, when at least one logic signal is an effective signal, the or gate is used for controlling the switch sub-circuit to be conducted based on the effective signal so as to enable the driving sub-circuit to be in an off state;
when the logic signals output by the over-temperature detection module, the over-current detection module and the voltage detection module are all invalid signals, the OR gate is used for controlling the switch sub-circuit to be turned off based on the invalid signals so as to enable the driving sub-circuit to be in a conducting state.
9. The protection circuit of the three-phase motor according to claim 2, wherein the switching sub-circuit comprises a transistor, a fourth voltage dividing resistor and a fifth voltage dividing resistor, a base electrode of the transistor is electrically connected with an output end of the logic judgment sub-circuit, the second power supply is electrically connected with a collector electrode of the transistor through the fourth voltage dividing resistor, and an emitter electrode of the transistor is grounded through the fifth voltage dividing resistor;
the second power supply is also electrically connected with the input end of the half-bridge pre-driving module through the fourth voltage dividing resistor.
10. A protection method for a three-phase motor, characterized in that the protection method is applied to the protection circuit for a three-phase motor according to any one of claims 1 to 9, and the protection method for a three-phase motor comprises:
the driving sub-circuit controls the first power supply to supply power to the three-phase motor based on a pulse width modulation signal;
the abnormal detection sub-circuit detects working parameters of the three-phase motor in real time and outputs corresponding logic signals to the logic judgment sub-circuit;
the logic judgment sub-circuit drives the switch sub-circuit to be conducted under the condition that the logic signal is an effective signal so as to enable the drive sub-circuit to be in an off state, and the first power supply stops supplying power to the three-phase motor;
and the logic judgment sub-circuit drives the switch sub-circuit to be turned off under the condition that the logic signal is an invalid signal so as to enable the drive sub-circuit to be in a conducting state, and the first power supply supplies power to the three-phase motor normally.
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| CN103715655A (en) * | 2012-09-28 | 2014-04-09 | 松下电器产业株式会社 | Overcurrent protection device, power tool and overcurrent protection circuit |
| CN104092415A (en) * | 2006-11-30 | 2014-10-08 | 株式会社电装 | Apparatus and method for driving rotary machine |
| CN109818334A (en) * | 2019-02-26 | 2019-05-28 | 上海思致汽车工程技术有限公司 | A kind of three-phase motor Drive Protecting Circuit |
| CN114792966A (en) * | 2021-01-25 | 2022-07-26 | 青岛海尔智能技术研发有限公司 | Overcurrent protection circuit for motor drive circuit, motor drive circuit and electric equipment |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN104092415A (en) * | 2006-11-30 | 2014-10-08 | 株式会社电装 | Apparatus and method for driving rotary machine |
| CN103715655A (en) * | 2012-09-28 | 2014-04-09 | 松下电器产业株式会社 | Overcurrent protection device, power tool and overcurrent protection circuit |
| CN109818334A (en) * | 2019-02-26 | 2019-05-28 | 上海思致汽车工程技术有限公司 | A kind of three-phase motor Drive Protecting Circuit |
| CN114792966A (en) * | 2021-01-25 | 2022-07-26 | 青岛海尔智能技术研发有限公司 | Overcurrent protection circuit for motor drive circuit, motor drive circuit and electric equipment |
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