CN108233824A - Compressor current foldback circuit, compressor and air conditioner - Google Patents
Compressor current foldback circuit, compressor and air conditioner Download PDFInfo
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- CN108233824A CN108233824A CN201810306853.6A CN201810306853A CN108233824A CN 108233824 A CN108233824 A CN 108233824A CN 201810306853 A CN201810306853 A CN 201810306853A CN 108233824 A CN108233824 A CN 108233824A
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- 238000005070 sampling Methods 0.000 claims abstract description 45
- 230000003321 amplification Effects 0.000 claims abstract description 34
- 238000003199 nucleic acid amplification method Methods 0.000 claims abstract description 34
- 230000001105 regulatory effect Effects 0.000 claims abstract description 13
- 230000001276 controlling effect Effects 0.000 claims abstract description 5
- 239000003990 capacitor Substances 0.000 claims description 20
- 230000005347 demagnetization Effects 0.000 abstract description 22
- 230000008859 change Effects 0.000 abstract description 4
- 238000012423 maintenance Methods 0.000 abstract description 4
- 238000004519 manufacturing process Methods 0.000 abstract description 3
- 230000006835 compression Effects 0.000 abstract 1
- 238000007906 compression Methods 0.000 abstract 1
- 238000004804 winding Methods 0.000 description 9
- 238000006243 chemical reaction Methods 0.000 description 8
- 230000009286 beneficial effect Effects 0.000 description 4
- 238000000034 method Methods 0.000 description 4
- 230000000694 effects Effects 0.000 description 3
- 238000001914 filtration Methods 0.000 description 3
- 238000010586 diagram Methods 0.000 description 2
- 230000004048 modification Effects 0.000 description 2
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Classifications
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02P—CONTROL OR REGULATION OF ELECTRIC MOTORS, ELECTRIC GENERATORS OR DYNAMO-ELECTRIC CONVERTERS; CONTROLLING TRANSFORMERS, REACTORS OR CHOKE COILS
- H02P29/00—Arrangements for regulating or controlling electric motors, appropriate for both AC and DC motors
- H02P29/02—Providing protection against overload without automatic interruption of supply
- H02P29/032—Preventing damage to the motor, e.g. setting individual current limits for different drive conditions
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02P—CONTROL OR REGULATION OF ELECTRIC MOTORS, ELECTRIC GENERATORS OR DYNAMO-ELECTRIC CONVERTERS; CONTROLLING TRANSFORMERS, REACTORS OR CHOKE COILS
- H02P25/00—Arrangements or methods for the control of AC motors characterised by the kind of AC motor or by structural details
- H02P25/16—Arrangements or methods for the control of AC motors characterised by the kind of AC motor or by structural details characterised by the circuit arrangement or by the kind of wiring
- H02P25/18—Arrangements or methods for the control of AC motors characterised by the kind of AC motor or by structural details characterised by the circuit arrangement or by the kind of wiring with arrangements for switching the windings, e.g. with mechanical switches or relays
- H02P25/184—Arrangements or methods for the control of AC motors characterised by the kind of AC motor or by structural details characterised by the circuit arrangement or by the kind of wiring with arrangements for switching the windings, e.g. with mechanical switches or relays wherein the motor speed is changed by switching from a delta to a star, e.g. wye, connection of its windings, or vice versa
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02P—CONTROL OR REGULATION OF ELECTRIC MOTORS, ELECTRIC GENERATORS OR DYNAMO-ELECTRIC CONVERTERS; CONTROLLING TRANSFORMERS, REACTORS OR CHOKE COILS
- H02P27/00—Arrangements or methods for the control of AC motors characterised by the kind of supply voltage
- H02P27/04—Arrangements or methods for the control of AC motors characterised by the kind of supply voltage using variable-frequency supply voltage, e.g. inverter or converter supply voltage
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- Engineering & Computer Science (AREA)
- Power Engineering (AREA)
- Control Of Ac Motors In General (AREA)
Abstract
The present invention provides a kind of compressor current foldback circuit, compressor and air conditioners.Wherein, a kind of compressor demagnetization protection circuit, including：Regulating circuit, the pwm signal that the control unit for receiving compressor is sent out, and according to the bias voltage of pwm signal adjusting operational amplification circuit；Wherein, the duty ratio of pwm signal is corresponding with the overcurrent protection threshold value of compressor；Sample circuit, for Sampling Compression machine electric current and be converted into sampled voltage；Operational amplification circuit, for being amplified to bias voltage and sampled voltage, output first voltage to IPM protects circuit；IPM protects circuit, for controlling the operating condition of compressor according to first voltage.The present invention is by adjusting the bias voltage of operational amplification circuit; change the output of operational amplification circuit; so as to change the protection value of overcurrent; it is required with adapting to the different of the demagnetization current under compressor different frequency; and electric-controlled plate hardware configuration need not be changed; effectively reduce production, maintenance cost and serious forgiveness.
Description
Technical Field
The invention relates to the technical field of motor control, in particular to an over-current protection circuit of a compressor, the compressor and an air conditioner.
Background
The variable frequency air conditioner has the advantages of electricity saving, high energy efficiency, low noise and the like, and is approved by broad users. The principle of the inverter air conditioner is to control the room temperature by adjusting the operating frequency of the compressor. When the difference between the room temperature and the set temperature is large, the operating frequency of the compressor needs to be increased; when the difference between the room temperature and the set temperature is small, it is necessary to reduce the operating frequency of the compressor. In addition, the energy efficiency of the air conditioner is closely related to the motor conversion efficiency of the motor of the compressor, and the motor conversion efficiency is related to the wiring mode of the electronic winding. The high-frequency energy efficiency of the delta connection method is high, the demagnetization current is large, the low-frequency energy efficiency of the star connection method is high, and the demagnetization current is small.
At present, the delta-star connection method has the advantages of both delta connection and star connection, is a combination of the delta connection and the star connection, and achieves the purpose of improving energy efficiency by switching windings according to different frequencies, but the overcurrent protection of the compressor is particularly important. The overcurrent protection value needs to be switched at different frequencies to prevent the compressor from demagnetizing. And the demagnetization currents of different compressors are different, and the demagnetization protection of different compressors is usually satisfied by modifying the hardware of the electric control board, so that the maintenance cost and the fault tolerance rate are increased.
Therefore, how to realize that the over-current protection value of the demagnetization current is automatically changed through software when the windings are switched in the running process of the compressor becomes a technical problem to be solved urgently at present.
Disclosure of Invention
The present invention is directed to solving at least one of the problems of the prior art or the related art.
To this end, an aspect of the present invention is to provide an overcurrent protection circuit for a compressor.
Another aspect of the present invention is to provide a compressor.
Another aspect of the present invention is to provide an air conditioner.
In view of the above, the present invention provides an over-current protection circuit for a compressor, including: the Intelligent Power Module comprises an operational amplifier circuit, and a voltage regulating circuit, a sampling circuit and an IPM (Intelligent Power Module) protection circuit which are respectively connected with the operational amplifier circuit; the voltage regulating circuit is used for receiving a PWM signal sent by a control unit of the compressor and regulating the bias voltage of the operational amplification circuit according to the PWM signal; the duty ratio of the PWM signal corresponds to an overcurrent protection threshold value of the compressor; the sampling circuit is used for sampling the current of the compressor and converting the current into sampling voltage; the operation amplifying circuit is used for amplifying the bias voltage and the sampling voltage and outputting a first voltage to the IPM protection circuit; and the IPM protection circuit is used for controlling the running state of the compressor according to the first voltage.
According to the compressor overcurrent protection circuit, when a motor of a compressor needs winding switching, the control unit sends out a stator winding wiring switching signal to control wiring switching, at the moment, the control unit can output PWM signals with different duty ratios according to overcurrent protection threshold values of the compressor under different frequencies, a voltage regulating circuit is used for realizing DC/DC conversion voltage regulation to obtain bias voltage, and the bias voltage is applied to the in-phase end of an operational amplifier to change the output of the operational amplifier circuit; the actual voltage of the compressor obtained by the sampling circuit is input to the operational amplification circuit in a differential input mode, and when the winding is switched, the bias voltage compensates the sampling voltage, so that the output of the operational amplification circuit is changed, and the overcurrent protection value is changed; after the operation amplification circuit amplifies the voltage, the first voltage is output to a protection pin of the IPM and is compared with a reference voltage built in the IPM, when the first voltage is higher than the reference voltage, the IPM protection circuit directly stops outputting the driving voltage to the compressor, so that the compressor stops running, the phenomenon of demagnetization of the compressor due to overlarge current is avoided, and the purpose of protecting the compressor is achieved. The invention changes the output of the operational amplification circuit by adjusting the bias voltage of the operational amplification circuit, thereby changing the over-current protection value to adapt to different requirements of demagnetization current of the compressor under different frequencies, realizing the over-current protection of the compressor, avoiding the damage of the compressor, avoiding changing the hardware structure of an electric control board, and effectively reducing the production and maintenance costs and the fault tolerance rate.
In the above technical solution, preferably, the voltage regulating circuit includes a switching tube, and an input end of the switching tube receives the PWM signal.
In the technical scheme, the voltage regulating circuit outputs PWM with different duty ratios to a switching tube through a master controller to chop, DC/DC conversion voltage regulation is achieved, continuously adjustable bias voltage is obtained, sampling voltage is amplified and output through the operational amplifying circuit, and output reference adjustment of amplified voltage is achieved, so that an overcurrent protection value is changed, and overcurrent of a compressor is prevented. According to the compressor overcurrent protection circuit provided by the invention, different overcurrent protection values can be obtained by outputting PWM with different duty ratios through main control, and different overcurrent protection values required by star-delta connection switching are met.
In any of the above technical solutions, preferably, the switching tube is a triode or a MOS tube.
In the technical scheme, the triode is low in price, but large in power consumption loss, the MOS transistor is high in price, but relatively small in power consumption loss and strong in driving capability, and the type of the switching tube can be comprehensively selected according to actual conditions.
In any of the above technical solutions, preferably, the sampling circuit includes a first resistor, the first resistor is connected to the power main loop, and one end of the first resistor is connected to the power ground.
In the technical scheme, a first resistor is used as a current sampling resistor and connected to a power main loop of a circuit, one end of the first resistor is connected to a power ground to sample the actual working current of the compressor, the actual working voltage (namely the sampling voltage) of the compressor is obtained through corresponding conversion, the actual working voltage is sent to an operational amplifier circuit through a differential input mode, and after the actual working current is amplified by the operational amplifier circuit, the first voltage is output to a protection pin of the IPM and is compared with a reference voltage built in the IPM. When the star-delta connection is switched, the output of the operational amplifier circuit is changed by adjusting the duty ratio of PWM according to different overcurrent protection points, controlling the magnitude of bias voltage and changing the output of the operational amplifier circuit, so that the overcurrent protection value is changed to adapt to different requirements of demagnetization current of the motor under different frequencies, and the overcurrent protection of the compressor is realized.
Those skilled in the art will appreciate that the sampling circuit includes the first resistor, but the number of the first resistors is not limited to one.
In any of the above technical solutions, preferably, the operational amplifier circuit is a negative feedback.
In the technical scheme, the closed loop of the operational amplifier tends to be stable by adopting negative feedback, the influence of open loop gain is eliminated, the distortion of the amplifier in a stable state can be greatly reduced by utilizing the negative feedback, and various interference levels in the amplifier can be weakened, so that the stability of the whole circuit is improved, and the accuracy of judging the overcurrent protection of the compressor is improved.
In any one of the above technical solutions, preferably, the operational amplifier circuit includes: an operational amplifier; one end of the second resistor is connected with the sampling connection point of the first resistor, and the other end of the second resistor is connected with the in-phase end of the operational amplifier; one end of the third resistor is connected with the power ground, and the other end of the third resistor is connected with the inverting end of the operational amplifier; and one end of the fourth resistor is connected with the inverting end of the operational amplifier, and the other end of the fourth resistor is connected with the output end of the operational amplifier.
In the technical scheme, the output end of the operational amplifier is connected with the inverting input end through the fourth resistor, so that negative feedback is formed, and the function of adjusting the amplification factor of the operational amplifier is achieved; similarly, the second resistor and the third resistor also have the function of adjusting the amplification factor of the operational amplifier and the function of limiting current. In specific implementation, the in-phase terminal and the anti-phase terminal of the operational amplifier should be configured to be balanced as much as possible to meet the requirement of the amplification factor of the sampling voltage.
In any of the above technical solutions, preferably, the IPM protection circuit includes a first comparator; the inverting terminal of the first comparator is connected to the output terminal of the operational amplifier.
In the technical scheme, after the sampling voltage is amplified by the operational amplifier, a first voltage is output to the inverting end of a first comparator of the IPM protection circuit and is compared with a reference voltage built in the IPM, and when the first voltage is lower than the reference voltage, the compressor normally operates; when the first voltage is higher than the reference voltage, the IPM protection circuit controls the compressor to stop operating.
In any of the above technical solutions, preferably, the compressor overcurrent protection circuit further includes: and one end of the first filter circuit is connected with the output end of the operational amplifier circuit, and the other end of the first filter circuit is connected with the input end of the IPM protection circuit.
In the technical scheme, the interference of the output voltage of the operational amplifier is filtered by the first filter circuit, so that the misoperation of the IPM protection circuit is prevented. Preferably, the first filter circuit is an RC filter circuit, which is simple and low cost.
In any of the above technical solutions, preferably, the first filter circuit includes a fifth resistor, one end of the fifth resistor is connected to the output end of the operational amplifier, and the other end of the fifth resistor is connected to the inverting end of the first comparator; the first filter circuit further comprises a first capacitor, one end of the first capacitor is connected with the inverting end of the first comparator, and the other end of the first capacitor is connected to the ground.
In the technical scheme, the fifth resistor is connected in series between the output end of the operational amplifier and the inverting end of the first comparator, and the first capacitor is connected in series between the inverting end of the first comparator and the ground to form the RC filter circuit, so that the interference of the output voltage of the operational amplifier is effectively filtered, the misoperation of the IPM protection circuit is prevented, and the IPM protection circuit can be prevented from being burnt when the current is too large.
In any one of the above technical solutions, preferably, the switching tube is a triode, and the voltage regulating circuit further includes: one end of the first inductor is connected with a power supply VCC, and the other end of the first inductor is connected with an emitting electrode of the triode; one end of the sixth resistor is connected with the collector of the triode, and the other end of the sixth resistor is connected with the in-phase end of the operational amplifier; and one end of the seventh resistor is connected with the emitting electrode of the triode, and the other end of the seventh resistor is connected with the base electrode of the triode.
In the technical scheme, the switch tube preferably adopts a triode, and a collector and an emitter of the triode are connected with a seventh resistor, so that the reliable cut-off of the triode can be ensured when no input voltage (or the input end is suspended). Even first inductance between the projecting pole of power VCC and triode, can the filtering exchange interference signal, help increasing the life-span of triode. The sixth resistor is arranged at the non-inverting end of the operational amplifier and has the function of adjusting the amplification factor of the operational amplifier.
In any one of the above technical solutions, preferably, a resistance value of the third resistor connected in parallel with the fourth resistor is equal to a resistance value of the second resistor connected in parallel with the sixth resistor.
In the technical scheme, the resistance value of the third resistor and the fourth resistor after being connected in parallel and the resistance value of the second resistor and the sixth resistor after being connected in parallel satisfy the equal relation so as to balance the amplification factor of the operational amplifier,
in any one of the above technical solutions, preferably, the voltage regulating circuit further includes: and one end of the second filter circuit is connected to the ground, and the other end of the second filter circuit is connected with the collector of the triode.
In the technical scheme, the second filter circuit can obtain clean bias voltage, and the anti-interference performance of the whole circuit is improved, so that the stability and the reliability of the protection circuit are improved.
In any one of the above technical solutions, preferably, the second filter circuit includes a first electrolytic capacitor and a second capacitor connected in parallel.
In the technical scheme, the electrolytic capacitor and the common capacitor are connected in parallel to form the filter circuit, so that high-frequency interference and low-frequency interference can be filtered, the filter effect is better, and the stability of the circuit is improved.
The invention also proposes a compressor comprising: the compressor overcurrent protection circuit according to any one of the above technical solutions.
According to the compressor of the present invention, the compressor overcurrent protection circuit in any one of the above technical solutions is adopted, so that the compressor overcurrent protection circuit has all the beneficial effects of the compressor overcurrent protection circuit, and details are not repeated.
The present invention also provides an air conditioner, comprising: the compressor overcurrent protection circuit according to any one of the above technical solutions; or a compressor as in the above solutions.
According to the air conditioner of the present invention, the compressor overcurrent protection circuit in any one of the above technical solutions or the compressor in the above technical solutions is adopted, so that all the beneficial effects of the compressor overcurrent protection circuit are achieved, and further description is omitted.
Additional aspects and advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention.
Drawings
The above and/or additional aspects and advantages of the present invention will become apparent and readily appreciated from the following description of the embodiments, taken in conjunction with the accompanying drawings of which:
fig. 1 shows a schematic diagram of a compressor demagnetization protection circuit according to an embodiment of the present invention;
fig. 2 shows a schematic diagram of a compressor demagnetization protection circuit according to another embodiment of the present invention.
Detailed Description
In order that the above objects, features and advantages of the present invention can be more clearly understood, a more particular description of the invention will be rendered by reference to the appended drawings. It should be noted that the embodiments and features of the embodiments of the present application may be combined with each other without conflict.
In the following description, numerous specific details are set forth in order to provide a thorough understanding of the present invention, however, the present invention may be practiced in other ways than those specifically described herein, and therefore the scope of the present invention is not limited by the specific embodiments disclosed below.
The compressor demagnetization protection circuit according to some embodiments of the present invention is described below with reference to fig. 1 and 2.
As shown in fig. 1, according to an embodiment of the present invention, there is provided a compressor demagnetization protection circuit, including: the device comprises an operational amplifier circuit, an adjustable bias voltage circuit, a sampling circuit and an IPM built-in protection circuit, wherein the adjustable bias voltage circuit, the sampling circuit and the IPM built-in protection circuit are respectively connected with the operational amplifier circuit; the adjustable bias voltage circuit is used for receiving a PWM signal sent by a control unit of the compressor and adjusting the bias voltage of the operational amplification circuit according to the PWM signal; the duty ratio of the PWM signal corresponds to an overcurrent protection threshold value of the compressor; the sampling circuit is used for sampling the three-phase current of the compressor and converting the three-phase current into sampling voltage; the operation amplifying circuit is used for amplifying the bias voltage and the sampling voltage and outputting a first voltage to the IPM built-in protection circuit; and the IPM built-in protection circuit is used for controlling the running state of the compressor according to the first voltage.
According to the compressor overcurrent protection circuit provided by the invention, when a motor needs winding switching, a control unit controlled by the motor sends a stator winding wiring switching signal to control wiring switching, at this time, the control unit can output PWM control signals with different duty ratios according to overcurrent protection threshold values of the compressor under different frequencies, DC/DC conversion voltage regulation is realized by using an adjustable bias voltage circuit to obtain bias voltage, and the bias voltage is added at a same-phase end of an operational amplifier to change the output of the operational amplifier circuit; the actual voltage of the compressor obtained by the sampling circuit is input to the operational amplification circuit in a differential input mode, and when the winding is switched, the bias voltage compensates the sampling voltage, so that the output of the operational amplification circuit is changed, and the overcurrent protection value is changed; after the operation amplification circuit amplifies the voltage, the first voltage is output to a protection pin of the IPM and is compared with the reference voltage built in the IPM, when the first voltage is higher than the reference voltage, the IPM built-in protection circuit directly stops outputting the driving voltage to the compressor, so that the compressor stops running, the phenomenon of demagnetization of the compressor due to overlarge current is avoided, and the purpose of protecting the compressor is achieved. The invention changes the output of the operational amplification circuit by adjusting the bias voltage of the operational amplification circuit, thereby changing the over-current protection value to adapt to different requirements of demagnetization current of the compressor under different frequencies, realizing the over-current protection of the compressor, avoiding the damage of the compressor, avoiding changing the hardware structure of an electric control board, and effectively reducing the production and maintenance costs and the fault tolerance rate.
As shown in fig. 2, in one embodiment of the present invention, the adjustable bias voltage circuit preferably includes a switch transistor (transistor D1), and the base of transistor D1 receives the PWM signal and controls transistor D1 to chop the output according to the PWM signal.
In the embodiment, the adjustable bias voltage circuit outputs PWM with different duty ratios to a switching tube for chopping through a master controller, so that DC/DC conversion voltage regulation is realized, a continuously adjustable bias voltage is obtained, a sampling voltage is amplified and output through an operational amplification circuit, and the output reference of the amplified voltage is adjustable, so that an overcurrent protection value is changed, and demagnetization of a compressor is prevented. According to the compressor demagnetization protection circuit, different overcurrent protection values can be obtained by outputting PWM with different duty ratios through main control, and the requirements of different overcurrent protection values during star-delta connection switching are met.
In another embodiment of the present invention, preferably, the switching tube is a MOS tube.
The triode is low in price, large in power consumption loss, high in price of the MOS transistor, relatively small in power consumption loss and high in driving capability, and therefore the type of the switching tube can be comprehensively selected according to actual conditions.
In one embodiment of the present invention, preferably, the sampling circuit includes a first resistor R1, the first resistor R1 is connected to the power main loop, and one end of the first resistor R1 is connected to the power ground.
In this embodiment, the first resistor R1 is used as a current sampling resistor, and is connected to the power main loop of the circuit, and one end of the first resistor R1 is connected to the power ground, so as to sample the actual operating current of the compressor, and obtain the actual operating voltage of the compressor through corresponding conversion. The sampling voltage is input to the operational amplification circuit in a differential input mode, and when the star-delta connection is switched, the output of the operational amplification circuit is changed by adjusting the bias voltage, so that the over-current protection value is changed, different requirements of demagnetization currents of the motor under different frequencies are met, and demagnetization protection of the compressor is realized.
It will be understood by those skilled in the art that the sampling circuit includes single resistance sampling, multiple resistance sampling, and the description is made only with respect to single resistance sampling. Here, the resistance value of the sampling resistor is represented by R; the overcurrent protection threshold of the compressor is represented by A; b represents the magnification of the comparator; the adjustable bias voltage is denoted by C; the reference voltage built in the IPM is denoted by V; then, as long as the above parameters satisfy the following relationship: r × a × B + C ═ V, can be achieved.
In one embodiment of the present invention, preferably, the operational amplification circuit is negative feedback.
In the embodiment, the closed loop of the operational amplifier tends to be stable by adopting negative feedback, the influence of open loop gain is eliminated, the distortion of the amplifier in a stable state can be greatly reduced by utilizing the negative feedback, various interference levels in the amplifier can be weakened, and therefore the stability of the whole circuit is improved, and the accuracy of demagnetization protection judgment of the compressor is improved.
In one embodiment of the present invention, preferably, the operational amplification circuit includes: an operational amplifier IC 1; one end of a second resistor R2, one end of a second resistor R2 is connected with the sampling connection point of the first resistor R1, and the other end of the second resistor R2 is connected with the in-phase end of the operational amplifier IC 1; a third resistor R3, one end of the third resistor R3 is connected to power ground, and the other end is connected to the inverting terminal of the operational amplifier IC 1; and a fourth resistor R4, wherein one end of the fourth resistor R4 is connected to the inverting terminal of the operational amplifier IC1, and the other end is connected to the output terminal of the operational amplifier IC 1.
In this embodiment, the output terminal of the operational amplifier IC1 is connected to the inverting input terminal through the fourth resistor R4, thereby forming negative feedback and having the effect of adjusting the amplification factor of the operational amplifier; similarly, the second resistor R2 and the third resistor R3 also have the function of adjusting the amplification factor of the operational amplifier, and also have the function of limiting the current. In specific implementation, the in-phase terminal and the anti-phase terminal of the operational amplifier should be configured to be balanced as much as possible to meet the requirement of the amplification factor of the sampling voltage.
In one embodiment of the present invention, preferably, the IPM built-in protection circuit includes a first comparator IC 2; the inverting terminal of the first comparator IC2 is connected to the output terminal of the operational amplifier IC 1.
In this embodiment, the sampled voltage is amplified by the operational amplifier IC1, and then a first voltage is outputted to the inverting terminal of the first comparator IC2 of the IPM built-in protection circuit, and compared with the IPM built-in reference voltage, when the first voltage is lower than the reference voltage, the compressor is normally operated; when the first voltage is higher than the reference voltage, the IPM built-in protection circuit controls the compressor to stop operating.
In one embodiment of the present invention, preferably, the compressor overcurrent protection circuit further includes: and one end of the first filter circuit is connected with the output end of the operational amplifier circuit, and the other end of the first filter circuit is connected with the input end of the IPM built-in protection circuit.
In this embodiment, the first filter circuit filters the interference of the output voltage of the operational amplifier IC1, thereby preventing the IPM internal protection circuit from malfunctioning. Preferably, the first filter circuit is an RC filter circuit, which is simple and low cost.
In one embodiment of the present invention, preferably, the first filter circuit includes a fifth resistor R5, one end of the fifth resistor R5 is connected to the output terminal of the operational amplifier IC1, and the other end is connected to the inverting terminal of the first comparator IC 2; the first filter circuit further includes a first capacitor C1, one end of the first capacitor C1 is connected to the inverting terminal of the first comparator IC2, and the other end is connected to ground.
In this embodiment, the fifth resistor R5 is connected in series between the output terminal of the operational amplifier IC1 and the inverting terminal of the first comparator IC2, and the first capacitor C1 is connected in series between the inverting terminal of the first comparator IC2 and the ground, so as to form an RC filter circuit, which effectively filters out the interference of the output voltage of the operational amplifier IC1, prevents the IPM internal protection circuit from malfunctioning, and can prevent the IPM internal protection circuit from being burned out when the current is too large.
In one embodiment of the present invention, preferably, the adjustable bias voltage circuit further includes: one end of the first inductor L1 is connected with a power supply VCC, and the other end of the first inductor L1 is connected with an emitting electrode of the triode; one end of a sixth resistor R6, one end of the sixth resistor R6 is connected with the collector of the triode, and the other end of the sixth resistor R6 is connected with the non-inverting end of the operational amplifier IC 1; and one end of the seventh resistor R7 and one end of the seventh resistor R7 are connected with the emitter of the triode, and the other end of the seventh resistor R8932 are connected with the base of the triode.
In this embodiment, the seventh resistor R7 is connected between the base and the emitter of the transistor, so that the transistor can be reliably turned off when there is no input voltage (or the input terminal is floating). Connect first inductance L1 between power VCC and the projecting pole of triode, can the filtering exchange interference signal, help increasing the life-span of triode. The sixth resistor R6 has the function of adjusting the amplification factor of the operational amplifier at the non-inverting terminal of the operational amplifier IC 1.
In one embodiment of the present invention, preferably, the resistance of the third resistor R3 connected in parallel with the fourth resistor R4 is equal to the resistance of the second resistor R2 connected in parallel with the sixth resistor R6.
In this embodiment, the resistances of the third resistor R3 and the fourth resistor R4 connected in parallel and the resistances of the second resistor R2 and the sixth resistor R6 connected in parallel satisfy an equal relationship to balance the amplification factors of the operational amplifier IC1, that is, satisfy the following relationship: r6// R2 ═ R3// R4.
In one embodiment of the present invention, preferably, the adjustable bias voltage circuit further includes: and one end of the second filter circuit is connected to the ground, and the other end of the second filter circuit is connected with the collector of the triode.
In the embodiment, the second filter circuit can obtain clean bias voltage, so that the anti-interference performance of the whole circuit is increased, and the stability and the reliability of the protection circuit are improved.
In any of the above embodiments, preferably, the second filter circuit comprises a first electrolytic capacitor E1 and a second capacitor C2 connected in parallel.
In the embodiment, the first electrolytic capacitor E1 and the second capacitor C2 are connected in parallel to form a filter circuit, so that high-frequency interference and low-frequency interference can be filtered, the filter effect is better, and the stability of the circuit is improved.
In the overcurrent protection circuit for the compressor provided by the embodiment of the invention, the adjustable bias voltage circuit outputs the PWM with different duty ratios through the master control to control the magnitude of the bias voltage, the bias voltage is 0-VCC and can be continuously adjusted, the clean bias voltage is obtained through filtering, the bias voltage is added at the in-phase end of the operational amplifier, the voltages at the two ends of the sampling resistor are input to the operational amplifier in a differential input mode, and after the sampling resistor is amplified by the operational amplifier, the sampling resistor outputs the voltages to the protection pin of the IPM to be compared with the reference voltage built in the IPM. The output of the operational amplification circuit is changed by adjusting the bias voltage, so that the overcurrent protection value is changed to adapt to different requirements of demagnetization currents of the motor under different frequencies, and different overcurrent protection values required by star delta connection switching are met.
In another embodiment of the present invention, the adjustable bias voltage circuit is preferably closed loop controlled.
The invention also proposes a compressor comprising: the compressor over-current protection circuit in the above embodiment.
According to the compressor of the present invention, the compressor overcurrent protection circuit in the above embodiment is adopted, so that the compressor overcurrent protection circuit has all the beneficial effects of the compressor overcurrent protection circuit, and details are not repeated.
The present invention also provides an air conditioner, comprising: the compressor overcurrent protection circuit in the above embodiment; or a compressor as in the previous embodiments.
According to the air conditioner of the present invention, the compressor overcurrent protection circuit in the above embodiment or the compressor in the above embodiment is adopted, so that the air conditioner has all the beneficial effects of the compressor overcurrent protection circuit, and further description is omitted.
The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention, and various modifications and changes may be made by those skilled in the art. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.
Claims (15)
1. An over-current protection circuit for a compressor, comprising: the operation amplifier circuit, and a voltage regulating circuit, a sampling circuit and an IPM protection circuit which are respectively connected with the operation amplifier circuit;
the voltage regulating circuit is used for receiving a PWM signal sent by a control unit of the compressor and regulating the bias voltage of the operational amplification circuit according to the PWM signal; wherein,
the duty ratio of the PWM signal corresponds to an overcurrent protection threshold value of the compressor;
the sampling circuit is used for sampling the current of the compressor and converting the current into sampling voltage;
the operation amplifying circuit is used for amplifying the bias voltage and the sampling voltage and outputting a first voltage to the IPM protection circuit;
the IPM protection circuit is used for controlling the running state of the compressor according to the first voltage.
2. The compressor over-current protection circuit according to claim 1,
the voltage regulating circuit comprises a switch tube, and the input end of the switch tube receives the PWM signal.
3. The compressor over-current protection circuit according to claim 2,
the switch tube is a triode or an MOS tube.
4. The compressor over-current protection circuit according to claim 2,
the sampling circuit comprises a first resistor, wherein the first resistor is connected into the power main loop, and one end of the first resistor is connected to the power ground.
5. The compressor overcurrent protection circuit of any one of claims 1 to 4, wherein the operational amplification circuit is negative feedback.
6. The compressor overcurrent protection circuit of claim 4, wherein the operational amplifier circuit comprises:
an operational amplifier;
one end of the second resistor is connected with the sampling connection point of the first resistor, and the other end of the second resistor is connected with the in-phase end of the operational amplifier;
one end of the third resistor is connected with the power ground, and the other end of the third resistor is connected with the inverting end of the operational amplifier;
and one end of the fourth resistor is connected with the inverting end of the operational amplifier, and the other end of the fourth resistor is connected with the output end of the operational amplifier.
7. The compressor over-current protection circuit according to claim 6,
the IPM protection circuit comprises a first comparator;
and the inverting end of the first comparator is connected with the output end of the operational amplifier.
8. The compressor over-current protection circuit according to claim 7, further comprising:
and one end of the first filter circuit is connected with the output end of the operational amplifier circuit, and the other end of the first filter circuit is connected with the input end of the IPM protection circuit.
9. The compressor over-current protection circuit according to claim 8,
the first filter circuit comprises a fifth resistor, one end of the fifth resistor is connected with the output end of the operational amplifier, and the other end of the fifth resistor is connected with the inverting end of the first comparator;
the first filter circuit further comprises a first capacitor, one end of the first capacitor is connected with the inverting end of the first comparator, and the other end of the first capacitor is connected to the ground.
10. The compressor overcurrent protection circuit of any one of claims 6 to 9, wherein the switching tube is a triode, and the voltage regulator circuit further comprises:
one end of the first inductor is connected with a power supply VCC, and the other end of the first inductor is connected with an emitting electrode of the triode;
one end of the sixth resistor is connected with the collector of the triode, and the other end of the sixth resistor is connected with the in-phase end of the operational amplifier;
and one end of the seventh resistor is connected with the emitting electrode of the triode, and the other end of the seventh resistor is connected with the base electrode of the triode.
11. The compressor over-current protection circuit according to claim 10,
the resistance value of the third resistor and the fourth resistor after being connected in parallel is equal to the resistance value of the second resistor and the sixth resistor after being connected in parallel.
12. The compressor over-current protection circuit of claim 11, wherein the voltage regulator circuit further comprises:
and one end of the second filter circuit is connected to the ground, and the other end of the second filter circuit is connected with the collector of the triode.
13. The compressor over-current protection circuit of claim 12,
the second filter circuit comprises a first electrolytic capacitor and a second capacitor which are connected in parallel.
14. A compressor, comprising: the compressor over-current protection circuit of any one of claims 1 to 13.
15. An air conditioner, comprising:
the compressor over-current protection circuit of any one of claims 1 to 13; or
The compressor of claim 14.
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN2018100047881 | 2018-01-03 | ||
| CN201810004788 | 2018-01-03 |
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| CN108233824A true CN108233824A (en) | 2018-06-29 |
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| Application Number | Title | Priority Date | Filing Date |
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| CN201810306853.6A Active CN108233824B (en) | 2018-01-03 | 2018-04-08 | Compressor overcurrent protection circuit, compressor and air conditioner |
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| CN108233824B (en) | 2020-12-18 |
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