CN112003544B - Control method, control device and controller - Google Patents
Control method, control device and controller Download PDFInfo
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- CN112003544B CN112003544B CN201910542877.6A CN201910542877A CN112003544B CN 112003544 B CN112003544 B CN 112003544B CN 201910542877 A CN201910542877 A CN 201910542877A CN 112003544 B CN112003544 B CN 112003544B
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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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Abstract
The embodiment of the application provides a control method, a control device and a controller, wherein the control method comprises the following steps: determining a reference signal Err _ AD; acquiring a digital sampling signal V1 of the motor driving current in a system operation mode; comparing the magnitude of the digital sampling signal V1 with the reference signal Err _ AD; judging whether overcurrent occurs according to the comparison result; and if the overcurrent occurs, controlling the motor to drive the current to be reduced. The method and the device can automatically acquire the standby standard signal in the standby mode of the system, thereby providing an accurate reference signal and further ensuring the reliability of overcurrent protection.
Description
The present application claims priority of chinese patent application having application date of 27/2019, application number of 201910443692.X, and title of "reference signal determining method and overcurrent protection method, apparatus and controller", which is incorporated herein by reference in its entirety.
Technical Field
The present disclosure relates to the field of circuit control technologies, and more particularly, to a control method, a control device, and a controller for overcurrent protection.
Background
In the field of circuit control technology, device or system damage can occur when the current exceeds a certain limit.
Disclosure of Invention
In view of this, the present application provides a control method, a control device and a controller, which can implement overcurrent protection.
In order to solve the technical problem, the following technical scheme is adopted in the application:
a control method for overcurrent protection comprises the following steps:
determining a reference signal Err _ AD;
acquiring a digital sampling signal V1 of the motor driving current in a system operation mode;
comparing the magnitude of the digital sampling signal V1 with the reference signal Err _ AD;
judging whether overcurrent occurs according to the comparison result; if the overcurrent occurs, controlling the motor to drive the current to be reduced;
wherein the determining the reference signal comprises the steps of:
periodically acquiring sampling signal Vs in system standby mode[n]According to said sampling signal Vs[n]Calculating digital signal Val[n]Wherein Vs[n]And Val[n]Respectively corresponding to the sampling signal and the digital signal under the nth sampling period;
for the digital signal Val within a preset period number or preset time[n]Filtering to obtain a filtered signal Iofs[n](ii) a The time corresponding to the preset periodicity and the preset time are not less than the time required by the filtering signal to reach a stable state;
the stabilized filtered signal Iofs[n]Set as a standby standard signal Iref；
According to the standby standard signal IrefAnd a guard threshold lossenc determining the reference signal Err _ AD;
wherein n is a positive integer.
A control method for overcurrent protection comprises the following steps:
determining a reference signal;
acquiring a digital sampling signal V1 of the motor driving current in a system operation mode;
comparing the magnitude of the digital sampling signal V1 with the reference signal;
judging whether overcurrent occurs according to the comparison result; if the overcurrent occurs, controlling the motor to drive the current to be reduced;
wherein the determining the reference signal comprises the steps of:
periodically acquiring sampling signal Vs in system standby mode[n]According to said sampling signal Vs[n]Calculating digital signal Val[n]Until the system is in a non-standby mode; wherein Vs[n]And Val[n]Respectively corresponding to the sampling signal and the digital signal under the nth sampling period;
for said digital signal Val[n]Filtering to obtain a filtered signal Iofs[n]；
Filtering signal I corresponding to the last sampling period in the system standby modeofsSet as a standby standard signal Iref；
According to the standby standard signal IrefAnd a guard threshold lossenc determining the reference signal Err _ AD;
wherein n is a positive integer.
Optionally, said pair of said digital signals Val[n]Filtering to obtain a filtered signal Iofs[n]The calculation is carried out according to the following formula:
Iofs[n]＝Iofs[n-1]+(Val[n]-Iofs[n-1])*G；
wherein n is a positive integer, when n is 1, Iofs[n-1]0; g is a low-pass filter coefficient;
G＝(fcut*2π)/fc；
wherein f iscutIs the cut-off frequency; f. ofcIs the carrier frequency.
Optionally, the protection threshold lossenc is determined by a system operation parameter; when a system carries out forward operation parameter protection, setting the reference signal Err _ AD as the sum of the standby standard signal Iref and the protection threshold LOSSYNC; judging whether the overcurrent occurs according to the comparison result; if the overcurrent occurs, the step of controlling the motor driving current to be reduced comprises the following steps: and when the digital sampling signal V1 is greater than the reference signal Err _ AD, judging that overcurrent occurs, and controlling the motor driving current to be reduced.
Optionally, the protection threshold lossenc is determined by a system operation parameter; when a system carries out negative operation parameter protection, setting the reference signal Err _ AD as the difference between the standby standard signal Iref and the protection threshold LOSSYNC; judging whether the overcurrent occurs according to the comparison result; if the overcurrent occurs, the step of controlling the drive current of the motor to be reduced comprises the following steps: and when the digital sampling signal V1 is smaller than the reference signal Err _ AD, judging that overcurrent occurs, and controlling the motor driving current to be reduced.
Optionally, the control method is used for negative overcurrent protection control of a three-phase motor, and the obtaining of the digital sampling signal V1 of the motor driving current in the system operation mode includes obtaining digital sampling signals V11 and V12 of any two-phase driving current of the three-phase motor;
comparing the magnitudes of the digital sampling signals V11, V12 and the reference signal;
and when the digital sampling signal V11 or V12 is smaller than the reference signal, controlling a driving signal of the motor and reducing the driving current of the motor.
Optionally, the reference signal is a reference signal,
when I isrefIf the reference signal Err _ AD is greater than LOSSYNC, the reference signal Err _ AD is equal to Iref–LOSSYNC；
When I isrefWhen the reference signal is smaller than LOSSYNC, the reference signal Err _ AD is 1.
A control device for over-current protection, comprising:
a reference signal determination unit for periodically acquiring the sampling signal Vs in the system standby mode[n]According to said sampling signal Vs[n]Calculating digital signal Val[n]Wherein Vs[n]And Val[n]Respectively corresponding to the sampling signal and the digital signal under the nth sampling period; for the digital signal Val within a preset period number or preset time[n]Filtering to obtain a filtered signal Iofs[n](ii) a The time corresponding to the preset periodicity and the preset time are not less than the time required by the filtering signal to reach a stable state; the stabilized filtered signal Iofs[n]Set as a standby standard signal Iref(ii) a According to the standby standard signal IrefAnd a guard threshold lossenc determining the reference signal Err _ AD; wherein n is a positive integer; or, the reference signal determination unit is used for periodically acquiring the sampling signal Vs in the system standby mode[n]According to said sampling signal Vs[n]Calculating digital signal Val[n]Until the system is in a non-standby mode; wherein Vs[n]And Val[n]Respectively corresponding to the sampling signals in the nth sampling periodA number and a digital signal; for said digital signal Val[n]Filtering to obtain a filtered signal Iofs[n](ii) a Filtering signal I corresponding to the last sampling period in the system standby modeofsSet as a standby standard signal Iref(ii) a According to the standby standard signal IrefAnd a guard threshold lossenc determining the reference signal Err _ AD; wherein n is a positive integer;
the digital signal acquisition unit is used for acquiring a digital sampling signal V1 of the motor driving current in the system operation mode;
a comparison unit for comparing the magnitude of the digital sampling signal V1 with the reference signal Err _ AD;
the control unit is used for judging whether the overcurrent occurs according to the comparison result; and if the overcurrent occurs, controlling the motor to drive the current to be reduced.
A controller for controlling an air conditioner comprises the control device.
A controller for controlling an air conditioner, comprising at least one processor and a memory, the memory for storing a computer program or instructions, the processor for executing the computer program or instructions to cause the controller to implement a control method as described above.
Optionally, when the controller is used to implement negative current overcurrent protection of the motor, the controller further includes a negative current sampling signal biasing circuit, configured to forward bias the negative current sampling signal to obtain a positive sampling signal corresponding to a negative current.
The embodiment of the application provides a control method, a control device and a controller, wherein in a system standby mode, a sampling signal is periodically acquired, and a corresponding digital signal is calculated according to the sampling signal; filtering the digital signal to obtain a filtering signal, and taking the stable filtering signal as a standby standard signal when the filtering signal is stable; and determining a reference signal according to the standby standard signal and a protection threshold corresponding to the system. And acquiring a digital sampling signal of the motor driving current in a system running mode. The motor driving current is controlled through the comparison of the digital sampling signal and the reference signal, so that the control of overcurrent protection is realized. The control method can acquire different reference signals under different systems or different hardware designs, and is beneficial to providing the accuracy of the reference signals, thereby providing more reliable overcurrent protection.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to the provided drawings without creative efforts.
Fig. 1 is a flowchart of an overcurrent protection method according to an embodiment of the present application;
fig. 2 is a flowchart of a method for determining a reference signal according to an embodiment of the present disclosure;
FIG. 3 is a schematic diagram of a driving circuit of a three-phase driving motor;
fig. 4 is a flowchart of another overcurrent protection method according to an embodiment of the present application.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
In the compressor control system, in the standby mode, the compressor driving current is 0, and corresponds to a sampling signal V at the momentsf. When the system is running, if the current reaches an overcurrent protection value, the sampling signal Vs correspondingly exceeds the sampling signal VsfAn amplitude A; when the system is designed, the current sampling signal is designed to be larger than (the sampling signal V)sf+ amplitude a), over-current protection occurs. However, in practice, the reason is thatFor the design and difference of hardware circuit, in the standby mode, even if the compressor driving current is 0, its corresponding sampling signal VsfMay be different; if a same sampling signal V is set for different compressors and different hardware circuitssfAs a reference, it is obvious that a control error or even a control error is caused. Based on the reference signal determination method, sampling signals V caused by different hardware designs and compressors or other reasons can be consideredsfDifferent effects, thereby providing an accurate reference signal.
An embodiment of the present application provides a control method for overcurrent protection, specifically, for overcurrent protection of the compressor control system, as shown in fig. 1, including the following steps:
s1: determining a reference signal Err _ AD;
s2: acquiring a digital sampling signal V1 of the motor driving current in a system operation mode;
s3: comparing the magnitude of the digital sampling signal V1 with the reference signal Err _ AD;
s4: judging whether overcurrent occurs according to the comparison result; and if the overcurrent occurs, controlling the motor to drive the current to be reduced.
As shown in fig. 2, step S1: determining the reference signal may specifically comprise the steps of:
s11, periodically acquiring the sampling signal in the system standby mode, and calculating the corresponding digital signal: periodically acquiring sampling signal Vs in system standby mode[n]According to said sampling signal Vs[n]Calculating digital signal Val[n]Wherein Vs[n]And Val[n]Respectively corresponding to the sampling signal and the digital signal in the nth sampling period. The sampling period may be the same as the compressor drive current period.
S12, filtering the digital signal to obtain a filtered signal: filtering the digital signal Val [ n ] within a preset period number or preset time to obtain a filtering signal Iofs [ n ]; the time corresponding to the preset periodicity and the preset time are not less than the time required by the filtering signal to reach a stable state; specifically, the filtering method may use low-pass filtering or average filtering.
For said digital signal Val [ n]Filtering to obtain a filtered signal Iofs[n](ii) a The system is prevented from being interfered by the outside, the hardware reference current self-correcting function is added, and the obtained digital signal is subjected to software filtering.
S13, setting the stabilized filtered signal as a standby standard signal: the stabilized filtered signal Iofs [ n ] is set as the standby standard signal Iref. When low-pass filtering is adopted, after the filtering frequency is determined, the time for the filtering signal to tend to be stable is basically fixed, namely, the time for the filtering signal to reach a stable state is basically fixed, for example, for the low-pass filtering of 1Hz, 1 second can reach 67% of a stable value, and about 3 seconds can basically reach the stable value; it should be noted that, here, stabilization is a relative concept, and in a specific embodiment, 99% of the limit stable value may be set as the stabilized filtered signal mentioned in the present application, and 96% of the limit stable value may also be set as the stabilized filtered signal mentioned in the present application.
And S14, determining a reference signal according to the standby standard signal and the protection threshold value: according to the standby standard signal IrefAnd a protection threshold lossenc determining the reference signal; the protection threshold lossenc corresponds to the overcurrent protection value. The greater the magnitude of the over-current protection value, the greater LOSSYNC.
In the above description, n is a positive integer.
In another embodiment, the system standby time is longer than the time required for the filtered signal to reach a steady state; therefore, step S1: determining the reference signal may also be determined by: periodically acquiring sampling signal Vs in system standby mode[n]According to said sampling signal Vs[n]Calculating digital signal Val[n]Until the system is in a non-standby mode; wherein Vs[n]And Val[n]Respectively corresponding to the sampling signal and the digital signal under the nth sampling period;
for said digital signal Val[n]Filtering to obtain a filtered signal Iofs[n]；
The filtered signal I corresponding to the last sampling period in the system standby modeofsIs a standby standard signal Iref；
According to the standby standard signal IrefAnd a guard threshold lossenc determining the reference signal Err _ AD;
wherein n is a positive integer.
In the above embodiment, the digital signal Val is subjected to[n]Filtering to obtain a filtered signal Iofs[n]Specifically, the calculation is carried out according to the following formula:
Iofs[n]＝Iofs[n-1]+(Val[n]-Iofs[n-1])*G；
wherein n is a positive integer, when n is 1, Iofs[n-1]0; g is a low-pass filter coefficient;
G＝(fcut*2π)/fc；
wherein f iscutIs the cut-off frequency; f. ofcIs the carrier frequency.
In the drive of three-phase asynchronous motors, such as air conditioning compressors, the method can be used to calculate the per-phase reference signal Err _ AD. In one embodiment, to prevent the compressor from over-current in the negative direction, the negative reference signal is determined by:
assuming that the sampling precision of the digital signal is ten bits, assuming that the variation range of the compressor current is [ -B, A ], the hardware circuit carries out forward bias on the sampling signal of the compressor current and then outputs the sampling signal to the MCU, and the sampling signal output to the MCU varies within the range of [0,5] V. In the system standby mode, a voltage signal detected by the phase current AD port of the MCU is a sampling voltage V, and the voltage signal is obtained by the conversion relation between the voltage and the AD:
reference AD value V1024/5
As shown in fig. 3, the three-phase drive circuit takes three-phase (U/V/W phase) AD values of Val1_ s, Val2_ s, and Val3_ s, and in the standby mode, three AD values of Val1_ s, Val2_ s, and Val3_ s are the same. The system is prevented from being interfered by the outside, a hardware reference current self-correcting function is added, and the obtained three-phase AD value is subjected to software filtering.
The formula is as follows:
Iu_ofs[n]＝Iu_ofs[n]+(Val1_s-Iu_ofs[n-1])*G①
Iv_ofs[n]＝Iv_ofs[n]+(Val2_s-Iv_ofs[n-1])*G②
Iw_ofs[n]＝Iw_ofs[n]+(Val2_s-Iw_ofs[n-1])*G③
g is the low pass filter coefficient (for example, with a 1Hz cutoff frequency, G ═ 2 × pi/fc, fc is the carrier frequency).
When the filtered signal is stable, or when the system is in the standby mode, I corresponding to the last sampling period nofs[n]Is a standby standard signal IrefI.e. by
Iu_ofs[n]For software self-correcting functional U-phase standby standard signal Iu_ref。
Iv_ofs[n]For the standard signal I of the V-phase standby after the software self-correcting functionv_ref。
Iw_ofs[n]For W-phase standby standard signal I after software self-correcting functionw_ref。
In a specific embodiment, the protection threshold lossyn is determined by a system operating parameter, such as a maximum current value that the system or a device can withstand. When the system performs forward operation parameter protection, i.e. forward overcurrent protection, the reference signal Err _ AD may be set as the standby standard signal IrefAnd a guard threshold lossyn; at this time, step S4 determines whether an overcurrent occurs according to the comparison result; if the overcurrent occurs, the step of controlling the motor driving current to be reduced comprises the following steps: when the digital sampling signal V1 is greater than the reference signal Err _ AD, the overcurrent of the system is judged, and the controller controls the motor driving current to be reduced.
When the system performs negative-going operation parameter protection, i.e. negative-going overcurrent protection, the reference signal Err _ AD may be set as the standby standard signal IrefAnd a guard threshold lossyn. Wherein the protection threshold is related to the compressor demagnetization current. At this time, step S4 determines whether an overcurrent occurs according to the comparison result; if the overcurrent occurs, the step of controlling the drive current of the motor to be reduced comprises the following steps: when the digital sampling signal V1 is less thanAnd when the reference signal Err _ AD is detected, the overcurrent of the system is judged, and the controller controls the motor driving current to be reduced.
Further, when the control method provided by the above embodiment is applied to negative current over-current protection of a motor, the control method for over-current protection includes the following steps:
acquiring at least a digital sampling signal V1 of any phase motor driving current in a system operation mode;
comparing the magnitude of the digital sampling signal V1 with the reference signal of the claims;
and when the digital sampling signal V1 is smaller than the reference signal, controlling a driving signal of the motor and reducing the driving current of the motor.
In order to solve the problem of compressor demagnetization damage caused by overlarge negative current, when the controller is used for realizing the negative current overcurrent protection of a motor (such as an air conditioner compressor), the controller also comprises a negative current sampling signal biasing circuit, and the negative current sampling signal biasing circuit is used for positively biasing the negative current sampling signal to obtain a positive sampling signal corresponding to the negative current. The embodiment of the application provides a negative current protection function, the larger the negative current is, the smaller the sampling signal is, and the smaller the corresponding digital signal is, and the digital sampling of the negative overcurrent protection is independently set in the embodiment, so that the sampling value can be ensured not to be influenced by other factors of the system; and a hardware reference current sampling self-correction function is added, so that the accuracy of the AD sampling value is ensured.
And setting a protection threshold LOSSYNC according to different overcurrent protection points of the compressor and hardware design. Will stand by standard signal IrefAnd compared with a protection threshold lossenc.
When I isrefAnd when the temperature is higher than LOSSYNC:
Err_AD＝Iref–LOSSYNC；
when I isrefAnd when the temperature is less than LOSSYNC:
Err_AD＝1。
when the Err _ AD is 1, the protection value reaches the lower limit of the sampling range, and the software may not process the protection value.
As shown in fig. 4, in the case of three-phase motor driving, in order to implement negative overcurrent protection, the step S2 of obtaining the digital sampling signal V1 of the motor driving current in the system operation mode includes the steps S21: acquiring digital sampling signals V11 and V12 of any two-phase driving current of a three-phase motor;
s22, comparing the magnitudes of the digital sampling signals V11 and V12 with the reference signal;
and S23, when the digital sampling signal V11 or V12 is smaller than the reference signal, judging that overcurrent occurs, controlling a driving signal of the motor, and reducing the driving current of the motor.
Specifically, digital sampling signals V11, V12 of any two-phase driving current are acquired; comparing the current sampling signals V11 and V12 with Err _ AD respectively; when one of the V11 and V12 values is smaller than the Err _ AD value, software protection is started, and the driving current is reduced. Specifically, the purpose of protecting the compressor can be achieved by cutting off the six-phase IGBT driving signal output.
The embodiment of the present application further provides a control device, which is used for overcurrent protection, and the device includes:
a reference signal determination unit for periodically acquiring the sampling signal Vs in the system standby mode[n]According to said sampling signal Vs[n]Calculating digital signal Val[n]Wherein Vs[n]And Val[n]Respectively corresponding to the sampling signal and the digital signal under the nth sampling period; for the digital signal Val within a preset period number or preset time[n]Filtering to obtain a filtered signal Iofs[n](ii) a The time corresponding to the preset periodicity and the preset time are not less than the time required by the filtering signal to reach a stable state; the stabilized filtered signal Iofs[n]Set as a standby standard signal Iref(ii) a According to the standby standard signal IrefAnd a guard threshold lossenc determining the reference signal Err _ AD; wherein n is a positive integer;
the digital signal acquisition unit is used for acquiring a digital sampling signal V1 of the motor driving current in the system operation mode;
a comparison unit for comparing the magnitude of the digital sampling signal V1 with the reference signal Err _ AD;
the control unit is used for judging whether the overcurrent occurs according to the comparison result; and if the overcurrent occurs, controlling the motor to drive the current to be reduced.
In another embodiment, the control device for overcurrent protection is provided, wherein the reference signal determination unit is configured to periodically obtain a sampling signal Vs in a system standby mode[n]According to said sampling signal Vs[n]Calculating digital signal Val[n]Until the system is in a non-standby mode; wherein Vs[n]And Val[n]Respectively corresponding to the sampling signal and the digital signal under the nth sampling period; for said digital signal Val[n]Filtering to obtain a filtered signal Iofs[n](ii) a The filtered signal I corresponding to the last sampling period in the system standby modeofsIs a standby standard signal Iref(ii) a According to the standby standard signal IrefAnd a guard threshold lossenc determining the reference signal Err _ AD; wherein n is a positive integer. In this embodiment, the system standby time is longer than the time required for the filtered signal to reach the steady state.
Based on the control device, the embodiment of the application also provides a controller, which is used for controlling the air conditioner, particularly controlling the air conditioner compressor, and the controller comprises the control device.
Further, an embodiment of the present application further provides a controller, configured to control an air conditioner, and in particular, an air conditioner compressor, where the controller includes at least one processor and a memory, where the memory is configured to store a computer program or an instruction, and the processor is configured to execute the computer program or the instruction, so that the controller implements the above-mentioned control method for overcurrent protection.
Based on the controller provided by the embodiment of the application, when the controller is used for realizing the negative current overcurrent protection of a motor (such as an air conditioner compressor), the controller further comprises a negative current sampling signal biasing circuit, and the negative current sampling signal biasing circuit is used for carrying out positive biasing on the negative current sampling signal to obtain a positive sampling signal corresponding to a negative current.
The previous description of the disclosed embodiments is provided to enable any person skilled in the art to make or use the present invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other embodiments without departing from the spirit or scope of the invention. Thus, the present invention is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.
Claims (10)
1. A control method is used for overcurrent protection and is characterized by comprising the following steps:
determining a reference signal Err _ AD;
acquiring a digital sampling signal V1 of the motor driving current in a system operation mode;
comparing the magnitude of the digital sampling signal V1 with the reference signal Err _ AD;
judging whether overcurrent occurs according to the comparison result; if the overcurrent occurs, controlling the motor to drive the current to be reduced;
wherein the determining the reference signal Err _ AD comprises the steps of:
periodically acquiring sampling signal Vs in system standby mode[n]According to said sampling signal Vs[n]Calculating digital signal Val[n]Wherein Vs[n]And Val[n]Respectively corresponding to the sampling signal and the digital signal under the nth sampling period;
for the digital signal Val within a preset period number or preset time[n]Filtering to obtain a filtered signal Iofs[n](ii) a The time corresponding to the preset periodicity and the preset time are not less than the time required by the filtering signal to reach a stable state;
the stabilized filtered signal Iofs[n]Set as a standby standard signal Iref；
According to the standby standard signal IrefAnd a guard threshold lossenc determining the reference signal Err _ AD;
said pair of said digital signals Val[n]Filtering to obtain a filtered signal Iofs[n]，The calculation is carried out according to the following formula:
Iofs[n]＝Iofs[n-1]+(Val[n]-Iofs[n-1])*G；
wherein n is a positive integer, when n is 1, Iofs[n-1]0; g is a low-pass filter coefficient;
G＝(fcut*2π)/fc；
wherein f iscutIs the cut-off frequency; f. ofcIs the carrier frequency.
2. A control method is used for overcurrent protection and is characterized by comprising the following steps:
determining a reference signal Err _ AD;
acquiring a digital sampling signal V1 of the motor driving current in a system operation mode;
comparing the magnitude of the digital sampling signal V1 with the reference signal Err _ AD;
judging whether overcurrent occurs according to the comparison result; if the overcurrent occurs, controlling the motor to drive the current to be reduced;
wherein the determining the reference signal Err _ AD comprises the steps of:
periodically acquiring sampling signal Vs in system standby mode[n]According to said sampling signal Vs[n]Calculating digital signal Val[n]Until the system is in a non-standby mode; wherein Vs[n]And Val[n]Respectively corresponding to the sampling signal and the digital signal under the nth sampling period;
for said digital signal Val[n]Filtering to obtain a filtered signal Iofs[n]；
Filtering signal I corresponding to the last sampling period in the system standby modeofs[n]Set as a standby standard signal Iref；
According to the standby standard signal IrefAnd a guard threshold lossenc determining the reference signal Err _ AD;
said pair of said digital signals Val[n]Filtering to obtain a filtered signal Iofs[n]，According to the followingThe formula is calculated to obtain:
Iofs[n]＝Iofs[n-1]+(Val[n]-Iofs[n-1])*G；
wherein n is a positive integer, when n is 1, Iofs[n-1]0; g is a low-pass filter coefficient;
G＝(fcut*2π)/fc；
wherein f iscutIs the cut-off frequency; f. ofcIs the carrier frequency.
3. Control method according to claim 1 or 2, characterized in that the protection threshold lossenc is determined by system operating parameters;
when the system carries out forward operation parameter protection, the reference signal Err _ AD is set as the standby standard signal IrefAnd the sum of the protection threshold lossyn; judging whether the overcurrent occurs according to the comparison result; if the overcurrent occurs, the step of controlling the motor driving current to be reduced comprises the following steps: and when the digital sampling signal V1 is greater than the reference signal Err _ AD, judging that overcurrent occurs, and controlling the motor driving current to be reduced.
4. Control method according to claim 1 or 2, characterized in that the protection threshold lossenc is determined by system operating parameters;
when the system carries out negative current overcurrent protection, setting the reference signal Err _ AD as the standby standard signal IrefAnd the protection threshold lossenc; judging whether the overcurrent occurs according to the comparison result; if the overcurrent occurs, the step of controlling the drive current of the motor to be reduced comprises the following steps: and when the digital sampling signal V1 is smaller than the reference signal Err _ AD, judging that overcurrent occurs, and controlling the motor driving current to be reduced.
5. The control method according to claim 4, wherein the control method is used for negative current overcurrent protection of a three-phase motor, and the obtaining of the digital sampling signal V1 of the motor driving current in the system operation mode comprises obtaining digital sampling signals V11, V12 of any two-phase driving current of the three-phase motor;
comparing the magnitudes of the digital sample signals V11, V12 and the reference signal Err _ AD;
and when the digital sampling signal V11 or V12 is smaller than the reference signal Err _ AD, controlling a driving signal of the motor and reducing the driving current of the motor.
6. The control method according to claim 5, wherein the reference signal is,
when I isrefIf the reference signal Err _ AD is greater than LOSSYNC, the reference signal Err _ AD is equal to Iref–LOSSYNC；
When I isrefWhen the reference signal is smaller than LOSSYNC, the reference signal Err _ AD is 1.
7. A control device for overcurrent protection, comprising:
a reference signal determination unit for periodically acquiring the sampling signal Vs in the system standby mode[n]According to said sampling signal Vs[n]Calculating digital signal Val[n]Wherein Vs[n]And Val[n]Respectively corresponding to the sampling signal and the digital signal under the nth sampling period; for the digital signal Val within a preset period number or preset time[n]Filtering to obtain a filtered signal Iofs[n](ii) a The time corresponding to the preset periodicity and the preset time are not less than the time required by the filtering signal to reach a stable state; the stabilized filtered signal Iofs[n]Set as a standby standard signal Iref(ii) a According to the standby standard signal IrefAnd a guard threshold lossenc determining the reference signal Err _ AD; or, the reference signal determination unit is used for periodically acquiring the sampling signal Vs in the system standby mode[n]According to said sampling signal Vs[n]Calculating digital signal Val[n]Until the system is in a non-standby mode; wherein Vs[n]And Val[n]Respectively corresponding to the sampling signal and the digital signal under the nth sampling period; for said digital signal Val[n]Filtering to obtain a filtered signal Iofs[n](ii) a Filtering signal I corresponding to the last sampling period in the system standby modeofs[n]Set as a standby standard signal Iref(ii) a According to the standby standard signal IrefAnd a guard threshold lossenc determining the reference signal Err _ AD;
said pair of said digital signals Val[n]Filtering to obtain a filtered signal Iofs[n]The calculation is carried out according to the following formula:
Iofs[n]＝Iofs[n-1]+(Val[n]-Iofs[n-1])*G；
wherein n is a positive integer; when n is 1, Iofs[n-1]0; g is a low-pass filter coefficient;
G＝(fcut*2π)/fc；
wherein f iscutIs the cut-off frequency; f. ofcIs the carrier frequency;
the digital signal acquisition unit is used for acquiring a digital sampling signal V1 of the motor driving current in the system operation mode;
a comparison unit for comparing the magnitude of the digital sampling signal V1 with the reference signal Err _ AD;
the control unit is used for judging whether the overcurrent occurs according to the comparison result; and if the overcurrent occurs, controlling the motor to drive the current to be reduced.
8. A controller for controlling an air conditioner, characterized by comprising the control device according to claim 7.
9. A controller for controlling an air conditioner, comprising at least one processor and a memory, the memory being configured to store a computer program or instructions, the processor being configured to execute the computer program or instructions to cause the controller to implement the control method of any one of claims 1-6.
10. The controller according to claim 8 or 9, wherein when the controller is used for implementing a negative current overcurrent protection of a motor, the controller further comprises a negative current sampling signal biasing circuit, configured to forward bias the negative current sampling signal to obtain a positive sampling signal corresponding to a negative current.
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