CN117791509A - Control method and device of IPM overcurrent protection device, air conditioner and storage medium - Google Patents

Control method and device of IPM overcurrent protection device, air conditioner and storage medium Download PDF

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Publication number
CN117791509A
CN117791509A CN202311795330.XA CN202311795330A CN117791509A CN 117791509 A CN117791509 A CN 117791509A CN 202311795330 A CN202311795330 A CN 202311795330A CN 117791509 A CN117791509 A CN 117791509A
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China
Prior art keywords
ipm
overcurrent protection
module
current
voltage
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CN202311795330.XA
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Chinese (zh)
Inventor
陈良
李林洪
黄翰
刘杰
庞伟
廖禛
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Gree Electric Appliances Inc of Zhuhai
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Gree Electric Appliances Inc of Zhuhai
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Priority to CN202311795330.XA priority Critical patent/CN117791509A/en
Publication of CN117791509A publication Critical patent/CN117791509A/en
Pending legal-status Critical Current

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Abstract

The invention discloses a control method and a control device of an IPM overcurrent protection device, an air conditioner and a storage medium, wherein the method comprises the following steps: in the development stage, controlling two IGBT tubes of a current bridge arm in the IPM module to be simultaneously switched on and switched off, and recording sampling voltages input at the non-inverting input end of the comparison module under each PWM duty ratio; in the working stage, before driving a load, two IGBT tubes of a current bridge arm are controlled to be simultaneously on-off, and during the period, an over-current protection voltage under the over-current condition of an IPM module and the output current PWM duty ratio are combined to determine whether an IPM over-current protection circuit has faults or not; if yes, the load is controlled to stop and a warning message of the fault of the IPM overcurrent protection circuit is initiated, and if not, the load is controlled to start and operate. According to the scheme, the switch logic of the two IGBT tubes of the same bridge arm in the IPM module is changed to synchronously detect the overcurrent signals so as to perform fault detection, and safety and user experience are improved.

Description

Control method and device of IPM overcurrent protection device, air conditioner and storage medium
Technical Field
The invention belongs to the technical field of fault detection of air conditioners, and particularly relates to a control method and device of an IPM overcurrent protection device, an air conditioner and a storage medium, in particular to a method and device for automatic fault detection of an IPM overcurrent protection circuit of an air conditioner, an air conditioner and a storage medium.
Background
As countries continue to push air conditioning energy efficiency to upgrade, variable frequency air conditioners have been dominant in the market. The variable frequency air conditioner uses an IPM (intelligent power module) to invert direct current into alternating current and control the operation of a compressor. If the IPM is provided with an overcurrent protection circuit, if the IPM overcurrent protection circuit fails or the overcurrent protection value of the IPM overcurrent protection circuit is set to be too large, the IPM is possibly damaged or a magnetic core of a compressor is possibly damaged due to the too large current of the IPM overcurrent protection circuit, so that higher potential safety hazards exist; if the overcurrent protection value of the IPM overcurrent protection circuit is set to be too low, the air conditioner is frequently protected and stopped, the maximum refrigerating capacity or heating capacity of the air conditioner is limited, and the use experience of a customer is poor.
The foregoing is provided merely for the purpose of facilitating understanding of the technical solutions of the present invention and is not intended to represent an admission that the foregoing is prior art.
Disclosure of Invention
The invention aims to provide a control method and device of an IPM overcurrent protection device, an air conditioner and a storage medium, so as to solve the problem that if an IPM overcurrent protection circuit of the air conditioner fails or an overcurrent protection value is set to be too large, an IPM or a magnetic core of a compressor is damaged, and higher potential safety hazards exist; if the over-current protection value of the IPM over-current protection circuit of the air conditioner is set to be too small, the air conditioner can frequently protect and stop to influence the user experience, so that the effects of changing the switch logic of two IGBT tubes of the same bridge arm in the IPM module before the permanent magnet synchronous motor is driven by the IPM module, synchronously detecting the voltage drop at two ends of the current sampling resistor of the compressor as an over-current signal to perform fault detection on the IPM over-current protection circuit, avoiding long-time operation of the air conditioner in an abnormal state of the IPM over-current protection circuit and being beneficial to improving safety and user experience are achieved.
The invention provides a control method of an IPM overcurrent protection device, which comprises the following steps: the device comprises an IPM module, a sampling module and an IPM overcurrent protection circuit; the IPM module includes: an inverter bridge composed of six IGBT tubes; the IPM overcurrent protection circuit includes: a comparison module; direct current bus voltage is connected to the collectors of IGBT tubes of upper bridges of three bridge arms in the inverter bridge; the emitters of IGBT tubes of lower bridges of three bridge arms in the inverter bridge are connected and then connected to the first connecting end of the sampling module; the second connecting end of the sampling module is grounded; the first connecting end of the sampling module is also connected to the non-inverting input end of the comparison module and is used for inputting the sampling voltage obtained by sampling by the sampling module; the inverting input end of the comparison module is used for inputting a set reference voltage; the output end of the comparison module is used for outputting the overcurrent signal of the IPM module under the condition that the sampling voltage input by the non-inverting input end of the comparison module is the same as the set reference voltage input by the inverting input end of the comparator; the control method of the IPM overcurrent protection device comprises the following steps: determining any one of three bridge arms in the IPM module, and marking the determined bridge arm as a current bridge arm in the IPM module; in the development stage of the IPM overcurrent protection device, a set series of PWM duty ratios are output for two IGBT tubes of a current bridge arm in the IPM module so as to control the two IGBT tubes of the current bridge arm in the IPM module to be simultaneously switched on and off, and sampling voltages input at the non-inverting input end of the comparison module under each PWM duty ratio output are recorded in the period; before the IPM module drives a load, outputting a set series of PWM duty ratios for two IGBT tubes of a current bridge arm in the IPM module so as to control the two IGBT tubes of the current bridge arm in the IPM module to be simultaneously on-off, and determining whether the IPM overcurrent protection circuit has faults by combining whether an output end of the comparison module outputs an overcurrent signal of the IPM module, an overcurrent protection voltage of the IPM overcurrent protection circuit under a corresponding PWM duty ratio under the condition that the output end of the comparison module outputs the overcurrent signal of the IPM module, and whether the output current PWM duty ratio is a set PWM maximum duty ratio; if the IPM overcurrent protection circuit is determined to have faults, controlling the load to stop and initiating reminding information of the faults of the IPM overcurrent protection circuit; and if the IPM overcurrent protection circuit is determined not to have faults, controlling the load to start and operate.
In some embodiments, in a development stage of the IPM overcurrent protection device, for two IGBT tubes of a current bridge arm in the IPM module, a set series of PWM duty cycles are output to control the two IGBT tubes of the current bridge arm in the IPM module to be turned on and off simultaneously, including: in the development stage of the IPM overcurrent protection device, outputting a set PWM duty ratio according to a set control period aiming at two IGBT tubes of a current bridge arm in the IPM module, so as to control the two IGBT tubes of the current bridge arm in the IPM module to be simultaneously switched on and off; wherein, the set PWM duty ratios output in different control periods form a set series of PWM duty ratios; wherein outputting a set PWM duty cycle per control period, comprising: in the first control period, outputting a set PWM initial duty ratio; the PWM duty cycle output by each control period is increased by a set amplitude from the second control period to the set PWM maximum duty cycle based on the PWM duty cycle output by the previous control period.
In some embodiments, wherein outputting the set series of PWM duty cycles comprises: starting from the set PWM initial duty ratio, gradually increasing the set amplitude until the set PWM maximum duty ratio is increased; before the IPM module drives a load, outputting a set series of PWM duty ratios for two IGBT tubes of a current bridge arm in the IPM module to control the two IGBT tubes of the current bridge arm in the IPM module to be simultaneously turned on and off, wherein during the period, whether the output end of the comparison module outputs the IPM module overcurrent signal, the overcurrent protection voltage of the IPM overcurrent protection circuit under the corresponding PWM duty ratio under the condition that the output end of the comparison module outputs the IPM module overcurrent signal, and whether the output current PWM duty ratio is the set PWM maximum duty ratio are combined, and determining whether the IPM overcurrent protection circuit has a fault comprises the following steps: in the working stage of the IPM overcurrent protection device, before the IPM module drives a load, aiming at two IGBT tubes of a current bridge arm in the IPM module, taking a set PWM initial duty ratio as the current PWM duty ratio, and outputting the current PWM duty ratio so as to control the two IGBT tubes of the current bridge arm in the IPM module to be simultaneously switched on and off; determining whether the output end of the comparison module outputs an overcurrent signal of the IPM module; if the fact that the output end of the comparison module does not output the overcurrent signal of the IPM module is determined, whether the IPM overcurrent protection circuit fails or not is determined by combining whether the output current PWM duty ratio is the set PWM maximum duty ratio or not; if it is determined that the output end of the comparison module outputs the IPM module overcurrent signal, determining whether the IPM overcurrent protection circuit has a fault according to the overcurrent protection voltage of the IPM overcurrent protection circuit under the PWM duty ratio corresponding to the condition that the output end of the comparison module outputs the IPM module overcurrent signal.
In some embodiments, determining whether the IPM over-current protection circuit has failed in combination with whether the current PWM duty cycle of the output is the set PWM maximum duty cycle comprises: after increasing the set amplitude by the set PWM initial duty cycle, taking the set amplitude as a new current PWM duty cycle, and determining whether the new current PWM duty cycle reaches the set PWM maximum duty cycle; if the new current PWM duty cycle is determined to reach the set PWM maximum duty cycle, determining that the IPM overcurrent protection circuit fails; and if the new current PWM duty ratio is not up to the set PWM maximum duty ratio, returning to continuously determine whether the output end of the comparison module outputs the overcurrent signal of the IPM module.
In some embodiments, determining whether the IPM overcurrent protection circuit has a fault according to an overcurrent protection voltage of the IPM overcurrent protection circuit under a PWM duty ratio corresponding to a case where the output terminal of the comparison module outputs the signal of the IPM module overcurrent, includes: recording the PWM duty cycle output when the output end of the comparison module outputs the overcurrent signal of the IPM module, and recording the PWM duty cycle as the overcurrent PWM duty cycle; according to the sampling voltage which is recorded in the development stage of the IPM overcurrent protection device and is input at the non-inverting input end of the comparison module under each output PWM duty cycle, the sampling voltage which is recorded in the development stage of the IPM overcurrent protection device and is input at the non-inverting input end of the comparison module under the overcurrent PWM duty cycle is used as the overcurrent protection voltage of the IPM module; and determining whether the IPM overcurrent protection circuit has faults according to the overcurrent protection voltage of the IPM module.
In some embodiments, determining whether the IPM overcurrent protection circuit fails according to the overcurrent protection voltage of the IPM module includes: determining whether a difference between an over-current protection voltage of the IPM module and a set reference voltage is greater than a first set voltage threshold; if the difference value between the over-current protection voltage of the IPM module and the set reference voltage is larger than the first set voltage threshold value, the over-current protection circuit is determined to have a fault that the over-current protection value of the IPM over-current protection circuit is set to be too large.
In some embodiments, determining whether the IPM overcurrent protection circuit has a fault according to the overcurrent protection voltage of the IPM module further includes: if the difference value between the overcurrent protection voltage of the IPM module and the set reference voltage is smaller than or equal to a first set voltage threshold value, determining whether the difference value between the overcurrent protection voltage of the IPM module and the set reference voltage is smaller than a second set voltage threshold value; wherein the second set voltage threshold is less than the first set voltage threshold; if the difference value between the overcurrent protection voltage of the IPM module and the set reference voltage is smaller than a second set voltage threshold value, determining that the overcurrent protection circuit of the IPM module has a fault that the overcurrent protection value of the overcurrent protection circuit is set to be too small; and if the difference value between the overcurrent protection voltage of the IPM module and the set reference voltage is larger than or equal to a second set voltage threshold value, determining that the IPM overcurrent protection circuit has no fault.
In accordance with another aspect of the present invention, there is provided a control device for an IPM overcurrent protection device, the IPM overcurrent protection device comprising: the device comprises an IPM module, a sampling module and an IPM overcurrent protection circuit; the IPM module includes: an inverter bridge composed of six IGBT tubes; the IPM overcurrent protection circuit includes: a comparison module; direct current bus voltage is connected to the collectors of IGBT tubes of upper bridges of three bridge arms in the inverter bridge; the emitters of IGBT tubes of lower bridges of three bridge arms in the inverter bridge are connected and then connected to the first connecting end of the sampling module; the second connecting end of the sampling module is grounded; the first connecting end of the sampling module is also connected to the non-inverting input end of the comparison module and is used for inputting the sampling voltage obtained by sampling by the sampling module; the inverting input end of the comparison module is used for inputting a set reference voltage; the output end of the comparison module is used for outputting the overcurrent signal of the IPM module under the condition that the sampling voltage input by the non-inverting input end of the comparison module is the same as the set reference voltage input by the inverting input end of the comparator; the control device of the IPM overcurrent protection device comprises: the control unit is configured to determine any one of three bridge arms in the IPM module and record the determined bridge arm as a current bridge arm in the IPM module; the control unit is further configured to output a set series of PWM duty ratios for the two IGBT tubes of the current bridge arm in the IPM module in a development stage of the IPM overcurrent protection device so as to control the two IGBT tubes of the current bridge arm in the IPM module to be simultaneously switched on and switched off, and record sampling voltages input at the non-inverting input end of the comparison module under each PWM duty ratio output during the period; the control unit is further configured to output a set series of PWM duty cycles for two IGBT tubes of a current bridge arm in the IPM module before the IPM module drives a load in an operation stage of the IPM overcurrent protection device, so as to control the two IGBT tubes of the current bridge arm in the IPM module to be simultaneously turned on and off, and determine whether the IPM overcurrent protection circuit fails according to whether an output end of the comparison module outputs an IPM module overcurrent signal, an overcurrent protection voltage of the IPM overcurrent protection circuit under a corresponding PWM duty cycle when the output end of the comparison module outputs the IPM module overcurrent signal, and whether the output current PWM duty cycle is a set PWM maximum duty cycle; the control unit is further configured to control the load to stop and initiate a reminding message of the fault of the IPM overcurrent protection circuit if the fault of the IPM overcurrent protection circuit is determined; and the control unit is further configured to control the load to start and operate if the IPM overcurrent protection circuit is determined to not have a fault.
In some embodiments, in a development stage of the IPM overcurrent protection device, the control unit outputs a set series of PWM duty cycles for two IGBT tubes of a current bridge arm in the IPM module to control the two IGBT tubes of the current bridge arm in the IPM module to be turned on and off simultaneously, including: in the development stage of the IPM overcurrent protection device, outputting a set PWM duty ratio according to a set control period aiming at two IGBT tubes of a current bridge arm in the IPM module, so as to control the two IGBT tubes of the current bridge arm in the IPM module to be simultaneously switched on and off; wherein, the set PWM duty ratios output in different control periods form a set series of PWM duty ratios; wherein the control unit outputs a set PWM duty cycle per control period, comprising: in the first control period, outputting a set PWM initial duty ratio; the PWM duty cycle output by each control period is increased by a set amplitude from the second control period to the set PWM maximum duty cycle based on the PWM duty cycle output by the previous control period.
In some embodiments, wherein the control unit outputs a set series of PWM duty cycles, comprising: starting from the set PWM initial duty ratio, gradually increasing the set amplitude until the set PWM maximum duty ratio is increased; the control unit, before the IPM module drives a load in the working phase of the IPM overcurrent protection device, outputs a set series of PWM duty ratios for two IGBT tubes of a current bridge arm in the IPM module to control the two IGBT tubes of the current bridge arm in the IPM module to be simultaneously turned on and off, combines whether the output end of the comparison module outputs the IPM module overcurrent signal during the period, and determines whether the IPM overcurrent protection circuit fails or not according to the overcurrent protection voltage of the IPM overcurrent protection circuit and whether the output current PWM duty ratio is the set PWM maximum duty ratio under the condition that the output end of the comparison module outputs the IPM module overcurrent signal, and includes: in the working stage of the IPM overcurrent protection device, before the IPM module drives a load, aiming at two IGBT tubes of a current bridge arm in the IPM module, taking a set PWM initial duty ratio as the current PWM duty ratio, and outputting the current PWM duty ratio so as to control the two IGBT tubes of the current bridge arm in the IPM module to be simultaneously switched on and off; determining whether the output end of the comparison module outputs an overcurrent signal of the IPM module; if the fact that the output end of the comparison module does not output the overcurrent signal of the IPM module is determined, whether the IPM overcurrent protection circuit fails or not is determined by combining whether the output current PWM duty ratio is the set PWM maximum duty ratio or not; if it is determined that the output end of the comparison module outputs the IPM module overcurrent signal, determining whether the IPM overcurrent protection circuit has a fault according to the overcurrent protection voltage of the IPM overcurrent protection circuit under the PWM duty ratio corresponding to the condition that the output end of the comparison module outputs the IPM module overcurrent signal.
In some embodiments, the control unit determining whether the IPM overcurrent protection circuit has a fault in combination with whether the current PWM duty cycle of the output is the set PWM maximum duty cycle, includes: after increasing the set amplitude by the set PWM initial duty cycle, taking the set amplitude as a new current PWM duty cycle, and determining whether the new current PWM duty cycle reaches the set PWM maximum duty cycle; if the new current PWM duty cycle is determined to reach the set PWM maximum duty cycle, determining that the IPM overcurrent protection circuit fails; and if the new current PWM duty ratio is not up to the set PWM maximum duty ratio, returning to continuously determine whether the output end of the comparison module outputs the overcurrent signal of the IPM module.
In some embodiments, the control unit determines whether the IPM overcurrent protection circuit has a fault according to an overcurrent protection voltage of the IPM overcurrent protection circuit at a PWM duty ratio corresponding to a case where the output terminal of the comparison module outputs the signal of the IPM module overcurrent, and includes: recording the PWM duty cycle output when the output end of the comparison module outputs the overcurrent signal of the IPM module, and recording the PWM duty cycle as the overcurrent PWM duty cycle; according to the sampling voltage which is recorded in the development stage of the IPM overcurrent protection device and is input at the non-inverting input end of the comparison module under each output PWM duty cycle, the sampling voltage which is recorded in the development stage of the IPM overcurrent protection device and is input at the non-inverting input end of the comparison module under the overcurrent PWM duty cycle is used as the overcurrent protection voltage of the IPM module; and determining whether the IPM overcurrent protection circuit has faults according to the overcurrent protection voltage of the IPM module.
In some embodiments, the control unit determines whether the IPM overcurrent protection circuit fails according to the overcurrent protection voltage of the IPM module, including: determining whether a difference between an over-current protection voltage of the IPM module and a set reference voltage is greater than a first set voltage threshold; if the difference value between the over-current protection voltage of the IPM module and the set reference voltage is larger than the first set voltage threshold value, the over-current protection circuit is determined to have a fault that the over-current protection value of the IPM over-current protection circuit is set to be too large.
In some embodiments, the control unit determines whether the IPM overcurrent protection circuit has a fault according to an overcurrent protection voltage of the IPM module, and further includes: if the difference value between the overcurrent protection voltage of the IPM module and the set reference voltage is smaller than or equal to a first set voltage threshold value, determining whether the difference value between the overcurrent protection voltage of the IPM module and the set reference voltage is smaller than a second set voltage threshold value; wherein the second set voltage threshold is less than the first set voltage threshold; if the difference value between the overcurrent protection voltage of the IPM module and the set reference voltage is smaller than a second set voltage threshold value, determining that the overcurrent protection circuit of the IPM module has a fault that the overcurrent protection value of the overcurrent protection circuit is set to be too small; and if the difference value between the overcurrent protection voltage of the IPM module and the set reference voltage is larger than or equal to a second set voltage threshold value, determining that the IPM overcurrent protection circuit has no fault.
In accordance with another aspect of the present invention, there is provided an air conditioner including: the control device of the IPM overcurrent protection device described above.
In accordance with the foregoing method, a further aspect of the present invention provides a storage medium, where the storage medium includes a stored program, where the program, when executed, controls a device where the storage medium is located to execute the foregoing method for controlling the IPM overcurrent protection apparatus.
Therefore, according to the scheme of the invention, the IPM overcurrent protection circuit is arranged on the IPM module on the control panel of the air conditioner; a sampling resistor (such as a sampling resistor RS 1) is arranged between the IPM module and the ground; in the development stage of a control board of the air conditioner, when two IGBT tubes of the same bridge arm in the IPM module are controlled to be simultaneously turned on and off, the output PWM duty ratio is increased from the PWM initial duty ratio to the PWM maximum duty ratio according to a set amplitude, and the forward input voltage of a comparator in an IPM overcurrent protection circuit under each output PWM duty ratio is tested and recorded to be used as the overcurrent protection voltage of the IPM overcurrent protection circuit under each PWM duty ratio in the working stage of the control board of the air conditioner; before the IPM module drives the permanent magnet synchronous motor in the working stage of a control panel of the air conditioner, controlling two IGBT tubes of the same bridge arm in the IPM module to be simultaneously turned on and off, increasing the output PWM duty ratio from the PWM initial duty ratio to the PWM maximum duty ratio according to a set amplitude, and detecting whether the forward input voltage and the reverse input voltage of a comparator in the IPM overcurrent protection circuit are equal or not; if the forward input voltage and the reverse input voltage of the comparator in the IPM overcurrent protection circuit are not detected to be equal, judging that the IPM overcurrent protection circuit fails; if the forward input voltage and the reverse input voltage of the comparator in the IPM overcurrent protection circuit are detected to be equal, judging whether the protection value set by the IPM overcurrent protection circuit is too large or too small according to the overcurrent protection voltage of the IPM overcurrent protection circuit under the PWM duty ratio at the moment; therefore, before the permanent magnet synchronous motor is driven by the IPM module, the switching logic of the two IGBT tubes of the same bridge arm in the IPM module is changed, and the voltage drop at the two ends of the current sampling resistor of the compressor is synchronously detected to serve as an overcurrent signal so as to perform fault detection on the IPM overcurrent protection circuit, thereby avoiding the air conditioner from running for a long time in the abnormal state of the IPM overcurrent protection circuit and being beneficial to improving the safety and the user experience.
Additional features and advantages of the invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention.
The technical scheme of the invention is further described in detail through the drawings and the embodiments.
Drawings
FIG. 1 is a flow chart illustrating an embodiment of a control method of an IPM overcurrent protection device according to the present invention;
FIG. 2 is a flow chart of an embodiment of a method for determining whether an IPM overcurrent protection circuit is faulty;
FIG. 3 is a flow chart of an embodiment of the method of determining whether the IPM overcurrent protection circuit fails in combination with the current PWM duty cycle of the output;
FIG. 4 is a flow chart illustrating an embodiment of determining whether the IPM current foldback circuit fails according to the foldback voltage of the IPM current foldback circuit in the method of the present invention;
FIG. 5 is a flowchart illustrating an exemplary process for determining whether an IPM over-current protection circuit fails according to an over-current protection voltage of the IPM module according to the method of the present invention;
FIG. 6 is a flowchart illustrating an embodiment of a second process for determining whether the IPM current foldback circuit fails according to the foldback voltage of the IPM module according to the method of the present invention;
FIG. 7 is a schematic diagram of an embodiment of an IPM over-current protection circuit of an air conditioner;
FIG. 8 is a flow chart of an embodiment of a voltage measurement flow of a current sampling resistor of a compressor of an air conditioner;
fig. 9 is a flowchart illustrating an embodiment of a method for automatic fault detection in an IPM overcurrent protection circuit of an air conditioner.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more apparent, the technical solutions of the present invention will be clearly and completely described below with reference to specific embodiments of the present invention and corresponding drawings. It will be apparent that the described embodiments are only some, but not all, embodiments of the invention. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.
Considering that if the IPM overcurrent protection circuit of the air conditioner fails or the overcurrent protection value is set to be too large, the IPM is damaged or the magnetic core of the compressor is damaged, so that higher potential safety hazards exist; if the overcurrent protection value of the IPM overcurrent protection circuit of the air conditioner is set to be too small, the air conditioner can frequently protect the machine from being stopped to influence the use experience of a user. Wherein the current of the IPM overcurrent protection circuit is too high or too low, for example: the overcurrent protection value of the IPM overcurrent protection circuit is set to 18A, and the IPM overcurrent protection circuit becomes 38A or 8A due to defects of the component itself or poor welding, so that the current of the IPM is excessively large or excessively low.
In addition, reasons for failure or excessive use of the IPM overcurrent protection circuit include: the control panel produces the bad welding of the components or the defect failure of the components. For example: a controller design stage may set the over-current value of the IPM over-current protection circuit, e.g., 18A. During the production and use stages, failure of components or poor welding may cause failure of the over-current protection circuit, so that the over-current value of the IPM over-current protection circuit is far greater than 18A or far less than 18A. And the system runs for a long time under the abnormal condition, so that the safety risk is high and the user experience is poor.
In the related scheme, an automatic fault detection scheme for the IPM overcurrent protection circuit is absent.
Therefore, the scheme of the invention provides a control method of an IPM overcurrent protection device, in particular to a method for automatically detecting faults of an IPM overcurrent protection circuit of an air conditioner, before an IPM module of the air conditioner drives a permanent magnet synchronous motor, the automatic fault detection function of the IPM overcurrent protection circuit is started, only the switch logic of two IGBT tubes of the same bridge arm in the IPM module is changed, and the voltage drop at two ends of a current sampling resistor of a compressor is synchronously detected to serve as an overcurrent signal, so that whether the IPM overcurrent protection circuit works abnormally or not can be judged, the air conditioner is prevented from running for a long time in the abnormal state of the IPM overcurrent protection circuit, and the running safety of the air conditioner and the use experience of users can be improved.
According to an embodiment of the present invention, a control method of an IPM overcurrent protection device is provided, and a flowchart of an embodiment of the method of the present invention is shown in fig. 1. The IPM overcurrent protection device includes: the IPM module, sampling module, and IPM overcurrent protection circuit, sampling module such as sampling resistor RS1; the IPM module includes: an inverter bridge composed of six IGBT tubes; the IPM overcurrent protection circuit includes: a comparison module, such as a comparator; direct current bus voltage is connected to the collectors of IGBT tubes of upper bridges of three bridge arms in the inverter bridge; the emitters of IGBT tubes of lower bridges of three bridge arms in the inverter bridge are connected and then connected to the first connecting end of the sampling module; the second connecting end of the sampling module is grounded; the first connecting end of the sampling module is also connected to the non-inverting input end of the comparison module, namely to the positive input end of the comparator, and is used for inputting the sampling voltage obtained by sampling by the sampling module; the inverting input of the comparison module, i.e. the inverting input of the comparator, is used for inputting a set reference voltage, such as the inverting input voltage V of a preset comparator Preset reverse direction The method comprises the steps of carrying out a first treatment on the surface of the An output end of the comparison module for outputting the IPM mode when the sampling voltage inputted from the non-inverting input end of the comparison module is the same as the set reference voltage inputted from the inverting input end of the comparatorBlock over-current signal. Specifically, fig. 7 is a schematic structural diagram of an embodiment of an IPM overcurrent protection circuit of an air conditioner. The IPM overcurrent protection circuit of the air conditioner as shown in fig. 7 includes: the intelligent power supply comprises an IPM module, a current sampling resistor RS1 of the compressor, a motor (such as a permanent magnet synchronous motor) in the compressor, an IPM overcurrent protection circuit and the like. Six IGBT tubes, namely an IGBT tube G1, an IGBT tube G2, an IGBT tube G3, an IGBT tube G4, an IGBT tube G5 and an IGBT tube G6 are arranged in the IPM module. An IPM overcurrent protection circuit comprising: resistor R1, resistor R2, comparator, capacitor C1.DC+ is a DC bus voltage signal, V Reverse direction For inverting the input voltage signal of the comparator, V Forward direction For the forward input voltage signal of the comparator, ipm_oc is the output voltage signal of the comparator.
The IGBT tube G1, the IGBT tube G2, the IGBT tube G3, the IGBT tube G4, the IGBT tube G5 and the IGBT tube G6 form an inversion bridge, the IGBT tube G1 and the IGBT tube G4 form a first bridge arm, the IGBT tube G2 and the IGBT tube G5 form a second bridge arm, the IGBT tube G3 and the IGBT tube G6 form a third bridge arm, the common ends of the emitter of the IGBT tube G1 and the collector of the IGBT tube G4 in the first bridge arm are connected to a first phase winding in the three-phase winding of the permanent magnet synchronous motor, the common ends of the emitter of the IGBT tube G2 and the collector of the IGBT tube G5 in the second bridge arm are connected to a second phase winding in the three-phase winding of the permanent magnet synchronous motor, and the common ends of the emitter of the IGBT tube G3 and the collector of the IGBT tube G6 in the third bridge arm are connected to a third phase winding in the three-phase winding of the permanent magnet synchronous motor. The direct-current bus voltage signal DC+ is respectively connected with the collector of the IGBT tube G1, the collector of the IGBT tube G2 and the collector of the IGBT tube G3; the emitter of the IGBT tube G4, the emitter of the IGBT tube G5 and the emitter of the IGBT tube G6 are connected and then connected to a first connection end of a current sampling resistor RS1 of the compressor; the second connection end of the current sampling resistor RS1 of the compressor is grounded GND. The second connecting end of the current sampling resistor RS1 of the compressor is grounded GND after passing through the capacitor C1; the second connection end of the current sampling resistor RS1 of the compressor is also connected to the positive input end of the comparator for inputting the positive input voltage V Forward direction The method comprises the steps of carrying out a first treatment on the surface of the The +3.3V voltage is grounded GND after passing through the resistor R2 and the resistor R1, the common terminal of the resistor R2 and the resistor R1 is connected to the inverting input terminal of the comparator for inputting the inverting inputVoltage V Reverse direction . And an output terminal of the comparator is used for outputting a voltage signal IPM_OC. When the forward input voltage V of the comparator Forward direction Is equal to the reverse input voltage V of the comparator Reverse direction The output voltage signal ipm_oc of the comparator is normally at a high level.
In an aspect of the present invention, as shown in fig. 1, the control method of the IPM overcurrent protection device includes: step S110 to step S150.
At step S110, any one of the three bridge arms in the IPM module is determined and recorded as a current bridge arm in the IPM module.
At step S120, in the development stage of the IPM overcurrent protection device, a set series of PWM duty ratios are output for the two IGBT tubes of the current bridge arm in the IPM module to control the two IGBT tubes of the current bridge arm in the IPM module to be turned on and off simultaneously, and the sampling voltage input at the non-inverting input terminal of the comparison module at each PWM duty ratio output is recorded during the period to be used as the overcurrent protection voltage of the IPM overcurrent protection circuit at each PWM duty ratio in the working stage of the IPM overcurrent protection device.
In some embodiments, in step S120, in a development stage of the IPM overcurrent protection device, a set series of PWM duty cycles are output for two IGBT tubes of a current bridge arm in the IPM module, so as to control the two IGBT tubes of the current bridge arm in the IPM module to be turned on and off simultaneously, including: in the development stage of the IPM overcurrent protection device, outputting a set PWM duty ratio according to a set control period aiming at two IGBT tubes of a current bridge arm in the IPM module, so as to control the two IGBT tubes of the current bridge arm in the IPM module to be simultaneously switched on and off; wherein the set PWM duty cycles output in different control periods form a set series of PWM duty cycles.
Wherein outputting a set PWM duty cycle per control period, comprising: in the first control period, outputting a set PWM initial duty ratio; the PWM duty cycle output by each control period is increased based on the PWM duty cycle output by the previous control period from the second control periodAdding a set amplitude, e.g. increasing the amplitude T of each change of PWM duty cycle x Until the set PWM maximum duty cycle is increased.
Specifically, fig. 8 is a flow chart of an embodiment of a voltage measurement flow of a current sampling resistor of a compressor of an air conditioner. In the example shown in FIG. 8, T i To drive the PWM duty ratio, T of two IGBT tubes of the same bridge arm in the IPM module to switch simultaneously x For each change in amplitude, T, of PWM duty cycle 0 For PWM initial duty cycle, T max For the maximum PWM duty cycle, the amplitude T of each change of the PWM duty cycle x PWM initial duty cycle T 0 PWM maximum duty cycle T max Can be adjusted according to practical application, and the PWM initial duty ratio T 0 PWM duty ratio T for simultaneously switching two IGBT tubes of same bridge arm in IPM module i PWM maximum duty cycle T max . The MCU is a main control chip of the air conditioner.
As shown in fig. 8, a voltage measurement flow of a current sampling resistor of a compressor includes:
step 11, controlling PWM duty ratio T of two IGBT tubes for driving the same bridge arm in the IPM module to switch simultaneously i Amplitude T varied each time with PWM duty cycle x For amplitude, from PWM initial duty cycle T 0 Up to PWM maximum duty cycle T max Step 12 is then performed.
Step 12, voltage of current sampling resistor of compressor and forward input voltage V of comparator Forward direction Is of the same voltage. Changing PWM duty ratio T of two IGBT tubes for driving same bridge arm in IPM module to switch simultaneously i The magnitude of the voltage is changed, namely the voltage at two ends of a sampling resistor of the compressor is changed, and the PWM duty ratio T of two IGBT tubes which drive the same bridge arm in the IPM module and are simultaneously switched is tested i Forward input voltage V of lower comparator Forward direction The PWM duty ratio T of two IGBT tubes simultaneously switching on and off of the same bridge arm in each driving IPM module is recorded and stored i The lower voltage value is reserved for subsequent inquiry and judgment.
When the IPM overcurrent protection circuit is used as an automatic fault detection component, the MCU of the main control chip outputs a PWM duty ratio T i And the same PWM duty ratio signal is used for controlling two IGBT tubes of the same bridge arm in the IPM module to be simultaneously turned on and turned off, such as an IGBT tube G1 and an IGBT tube G4, an IGBT tube G2 and an IGBT tube G5, and an IGBT tube G3 and an IGBT tube G6. When the direct-current bus is switched on, current flows from the positive end DC+ of the direct-current bus to the ground GND through the IGBT tube G1, the IGBT tube G4 and the sampling resistor RS 1; when turned off, the current is cut off. By varying the PWM duty cycle T i Can change the voltage across the sampling resistor RS1, i.e. the forward input voltage V of the comparator Forward direction . When the IPM module is used as a component for driving the permanent magnet synchronous motor, two IGBT tubes of the same bridge arm in the IPM module cannot be simultaneously switched, but are complementarily switched. During complementary switching, a current signal passes through the IGBT tube G1 from the positive end DC+ of the direct current bus to the permanent magnet synchronous motor, then passes through the IGBT tube G5 and the IGBT tube G6, and finally passes through the sampling resistor RS1 to the ground GND. When two IGBT tubes of the same bridge arm in the IPM module are simultaneously switched, current does not pass through the permanent magnet synchronous motor, and therefore the problem that the compressor is demagnetized due to overlarge current during fault self-detection is avoided.
In the development stage (such as design stage) of the control board of the air conditioner, the resistance values of the resistor R1 and the resistor R2 are adjusted according to the requirements, and the reverse input voltage V of the comparator is preset Preset reverse direction And recording and storing in the MCU, and reserving for subsequent inquiry and judgment. When the IPM overcurrent protection circuit works normally, the reverse input voltage V of the comparator Reverse direction For the reverse input voltage V Preset reverse direction Known and unique, records and stores for subsequent judgment. For example: in the design stage of the control panel of the air conditioner, according to the demagnetizing current of the compressor, the IPM overcurrent protection circuit sets a protection current, for example, 27.5A, the resistance value of the sampling resistor RS1 is 0.01Ω, the resistance value of the resistor R1 is determined to be 20Ω, and the resistance value of the resistor R2 is determined to be 220Ω, so that the design requirement is met. If the protection current of the IPM overcurrent protection circuit changes, the resistance values of the resistor R1, the resistor R2, and the resistor RS1 change accordingly.
In the development stage, the MCU of the main control chip outputs a PWM duty ratio T i From PWM initial duty cycle T 0 Up to PWM maximum duty cycle T max The increment amplitude of each cycle is T x Each PWM duty cycle T is tested i Positive of time comparatorTo input voltage V Forward direction The value is recorded and stored in the MCU, and is reserved for subsequent inquiry and judgment. Wherein the PWM initial duty cycle T 0 PWM maximum duty cycle T max Can be adjusted according to practical application, as shown in fig. 8. Changing PWM duty cycle T i The voltage of the sampling resistor RS1 of the compressor is changed, and the voltage is measured and recorded and stored in each PWM duty ratio T i The lower voltage value is reserved for subsequent inquiry.
In the scheme of the invention, the switching logic of two IGBT tubes of the same bridge arm in the IPM module is changed, the two IGBT tubes of the same bridge arm in the IPM module are driven to be simultaneously switched by presetting different PWM duty ratio signals, the voltage drop at two ends of a current sampling resistor of the compressor is measured, and the measured voltage drop at two ends of the current sampling resistor of the compressor is recorded and stored in a main control chip. Specifically, in the development stage of the air conditioner, the PWM duty ratio signal is changed, the voltages at two ends of the sampling resistor under different PWM duty ratio signals are recorded, namely, the list of different voltages corresponding to different PWM duty ratios is stored in the main control chip and is reserved for subsequent inquiry.
In step S130, before the IPM module drives a load, a set series of PWM duty cycles are output for the two IGBT tubes of the current bridge arm in the IPM module to control the two IGBT tubes of the current bridge arm in the IPM module to be turned on and off simultaneously, during which, whether the output end of the comparison module outputs the IPM module overcurrent signal or not is combined with the output end of the comparison module, the overcurrent protection voltage of the IPM overcurrent protection circuit under the corresponding PWM duty cycle under the condition that the output end of the comparison module outputs the IPM module overcurrent signal, and whether the output current PWM duty cycle is the set PWM maximum duty cycle are determined whether the IPM overcurrent protection circuit has a fault.
In some embodiments, in step S130, before the IPM module drives a load in the working phase of the IPM overcurrent protection device, a set series of PWM duty cycles are output for the two IGBT tubes of the current bridge arm in the IPM module to control the two IGBT tubes of the current bridge arm in the IPM module to be turned on and off simultaneously, including: and in the working stage of the IPM overcurrent protection device, before the IPM module drives a load, aiming at two IGBT tubes of a current bridge arm in the IPM module, starting from a set PWM initial duty ratio, gradually increasing a set amplitude until the set PWM maximum duty ratio is increased, so as to control the two IGBT tubes of the current bridge arm in the IPM module to be simultaneously on-off.
In step S130, before the IPM module drives the load, a set series of PWM duty cycles are output for the two IGBT tubes of the current bridge arm in the IPM module to control the two IGBT tubes of the current bridge arm in the IPM module to be turned on and off simultaneously, during which, in combination with whether the output terminal of the comparison module outputs the IPM module overcurrent signal, the overcurrent protection voltage of the IPM overcurrent protection circuit under the corresponding PWM duty cycle when the output terminal of the comparison module outputs the IPM module overcurrent signal, and whether the output current PWM duty cycle is the set PWM maximum duty cycle are determined, see the following exemplary description.
An exemplary process for determining whether the IPM overcurrent protection circuit has a fault in step S130 is further described below with reference to fig. 2, which is a flowchart of an embodiment of the method of the present invention, and includes: step S210 to step S240.
Step S210, in the working stage of the IPM overcurrent protection device, before the IPM module drives a load, for two IGBT tubes of a current bridge arm in the IPM module, the set PWM initial duty ratio is used as the current PWM duty ratio, and the current PWM duty ratio is output, so as to control the two IGBT tubes of the current bridge arm in the IPM module to be turned on and off simultaneously.
Step S220, determining whether the output end of the comparison module outputs the signal of the IPM module overcurrent.
Specifically, fig. 9 is a flowchart illustrating an embodiment of a method for automatic fault detection of an IPM overcurrent protection circuit of an air conditioner. In the example shown in FIG. 9, V Preset reverse direction For a preset comparatorThe resistance values of the resistor R1 and the resistor R2 can be adjusted to obtain the required preset value V Threshold 1 、V Threshold 2 The threshold voltage for abnormality determination can be adjusted according to actual use. Referring to the example shown in fig. 7, six IGBT tubes G1 to G6 are provided in the IPM module, and are controlled by PWM1 signals to PWM6 signals output by the main control chip MCU, respectively, to drive the permanent magnet synchronous motor to operate. RS1 is a current sampling resistor, and an IPM overcurrent protection circuit is formed by a resistor R1, a resistor R2, a capacitor C1, a comparator and the like. The larger the current through the sampling resistor RS1, the forward input voltage V of the comparator Forward direction The larger the positive input voltage V of the comparator Forward direction With negative input voltage V Negative going In the same case, the output voltage signal ipm_oc of the comparator is an overcurrent signal. For different compressors and different IPM modules, the negative input voltage V of the comparator can be changed by adjusting the resistance values of the resistor R1 and the resistor R2 Negative going The purpose of adjusting the magnitude of the protection current is achieved. For example: resistor R1 is 20Ω, resistor R2 is 220Ω, and voltage division calculation is performed to obtain V Reverse direction Is 0.275V. Sampling resistor RS1 is 0.01Ω, and when current I through the sampling resistor is equal to 27.5A, V Forward direction Equal to 0.275V, the comparator outputs an over-current signal ipm_oc at this time.
As shown in fig. 9, the fault detection flow of the IPM overcurrent protection circuit includes:
step 21, before the IPM module drives the permanent magnet synchronous motor, starting an automatic fault detection function of the IPM overcurrent protection circuit, and outputting a PWM1 driving signal, a PWM4 driving signal and a PWM duty ratio T by the MCU i For PWM initial duty cycle T 0 And controlling synchronous switching of the IGBT tube G1 and the IGBT tube G4, and synchronously executing step 22, namely synchronously detecting whether the overcurrent signal IPM_OC is detected.
Step 22 synchronously detects whether an over-current signal ipm_oc is detected: if not, go to step 23 to make PWM duty cycle T i Increasing the amplitude T of each change of PWM duty cycle x The method comprises the steps of carrying out a first treatment on the surface of the If yes, step 24 is performed to record the value of the PWM duty cycle at the time of over-current protection.
Step S230, if it is determined that the output end of the comparison module does not output the IPM module overcurrent signal, determining whether the IPM overcurrent protection circuit has a fault by combining whether the output current PWM duty cycle is the set PWM maximum duty cycle.
In some embodiments, in step S230, when it is determined that the output terminal of the comparison module does not output the signal of the IPM module overcurrent, a specific process of determining whether the IPM overcurrent protection circuit fails is described in the following exemplary description, in combination with whether the current PWM duty ratio of the output is the set PWM maximum duty ratio.
An embodiment of the method of the present invention for determining whether the IPM over-current protection circuit has a fault by combining the output current PWM duty cycle shown in fig. 3 is further described as a specific process for determining whether the IPM over-current protection circuit has a fault by combining the output current PWM duty cycle in step S230, which includes: step S310 to step S330.
Step S310, when it is determined that the output end of the comparison module does not output the signal of the IPM module overcurrent, the set amplitude is increased with the set PWM initial duty cycle, and then the new current PWM duty cycle is used as the new current PWM duty cycle, and it is determined whether the new current PWM duty cycle reaches the set PWM maximum duty cycle.
Step S320, if it is determined that the new current PWM duty cycle has reached the set PWM maximum duty cycle under the condition that the output end of the comparison module does not output the IPM module overcurrent signal, determining that the IPM overcurrent protection circuit fails.
Step S330, if it is determined that the new current PWM duty cycle does not reach the set PWM maximum duty cycle under the condition that the output end of the comparison module does not output the IPM module overcurrent signal, returning to continuously determine whether the output end of the comparison module outputs the IPM module overcurrent signal.
Specifically, as shown in fig. 9, the fault detection flow of the IPM overcurrent protection circuit further includes: step 23, if no over-current signal ipm_oc is detected, PWM duty cycle T i Increasing the amplitude T of each change of PWM duty cycle x PWM duty cycle T thereafter i Judging whether the maximum PWM duty cycle is reachedT max : if yes, it is determined that the IPM overcurrent protection circuit fails, otherwise, the process returns to step 22.
PWM duty cycle T i Increasing the amplitude T of each change of PWM duty cycle x Up to the maximum PWM duty cycle T max Exceeding the PWM maximum duty cycle T max And if the overcurrent signal IPM_OC is not detected, judging that the IPM overcurrent protection circuit fails. PWM maximum duty cycle T max In order to develop the stage, according to the actual application set value, PWM duty ratio T i On to PWM maximum duty cycle T max And if the current flowing through the sampling resistor of the compressor reaches the maximum and exceeds the protection current normally set by the IPM overcurrent protection circuit, judging that the IPM overcurrent protection circuit fails.
Step S240, if it is determined that the output end of the comparison module has output the IPM module overcurrent signal, determining whether the IPM overcurrent protection circuit has a fault according to the overcurrent protection voltage of the IPM overcurrent protection circuit under the PWM duty ratio corresponding to the condition that the output end of the comparison module outputs the IPM module overcurrent signal.
In some embodiments, in step S230, when it is determined that the output terminal of the comparison module has output the IPM module overcurrent signal and the current PWM duty cycle of the output does not reach the set PWM maximum duty cycle, a specific process of determining whether the IPM overcurrent protection circuit has a fault according to the overcurrent protection voltage of the IPM overcurrent protection circuit at the PWM duty cycle corresponding to the output terminal of the comparison module output the IPM module overcurrent signal is described below as an example.
In the following, a flowchart of an embodiment of determining whether the IPM over-current protection circuit has a fault according to the over-current protection voltage of the IPM over-current protection circuit in the method of the present invention shown in fig. 4 is further described, where the specific process of determining whether the IPM over-current protection circuit has a fault according to the over-current protection voltage of the IPM over-current protection circuit in step S240 includes: step S410 to step S430.
In step S410, when it is determined that the output end of the comparison module has output the IPM module overcurrent signal and the output current PWM duty ratio does not reach the set PWM maximum duty ratio, the PWM duty ratio output when the output end of the comparison module has output the IPM module overcurrent signal is recorded as the overcurrent PWM duty ratio.
Step S420, when it is determined that the output terminal of the comparison module has output the IPM module overcurrent signal and the current PWM duty ratio of the output does not reach the set PWM maximum duty ratio, the sampling voltage recorded in the development stage of the IPM overcurrent protection device and input to the non-inverting input terminal of the comparison module at the overcurrent PWM duty ratio is used as the overcurrent protection voltage of the IPM module according to the sampling voltage recorded in the development stage of the IPM overcurrent protection device and input to the non-inverting input terminal of the comparison module at each PWM duty ratio of the output.
Step S430, when it is determined that the output end of the comparison module has output the IPM module overcurrent signal and the output current PWM duty cycle does not reach the set PWM maximum duty cycle, determining whether the IPM overcurrent protection circuit has a fault according to the overcurrent protection voltage of the IPM module.
Specifically, as shown in fig. 9, the fault detection flow of the IPM overcurrent protection circuit further includes: step 24, if PWM duty cycle T i From PWM initial duty cycle T 0 To PWM maximum duty cycle T max If an overcurrent signal is detected, the value of PWM duty ratio at the time of overcurrent protection is recorded and is recorded as T Overcurrent flow Querying a value T of PWM duty cycle in overcurrent protection Overcurrent flow The positive input voltage of the corresponding comparator is denoted as V Overcurrent flow Step 25 is then performed to determine whether the value T of the PWM duty cycle at the time of over-current protection is satisfied Overcurrent flow The forward input voltage V of the corresponding comparator Overcurrent flow -preset comparator reverse input voltage V Preset reverse direction > voltage threshold V Threshold 1 。V Overcurrent flow Is the recorded value in the example shown in fig. 8.
In some embodiments, in step S240, when it is determined that the output terminal of the comparison module has output the signal of the IPM module overcurrent and the current PWM duty cycle of the output does not reach the set PWM maximum duty cycle, determining whether the IPM overcurrent protection circuit has a fault according to the overcurrent protection voltage of the IPM module includes: and a first process of determining whether the IPM overcurrent protection circuit has a fault according to the overcurrent protection voltage of the IPM module.
In the following, a flowchart of a first process for determining whether the IPM overcurrent protection circuit has a fault according to the overcurrent protection voltage of the IPM module in the method of the present invention shown in fig. 5 is further described, where the specific process for determining whether the IPM overcurrent protection circuit has a fault according to the overcurrent protection voltage of the IPM module in step S430 includes: step S510 to step S520.
Step S510, determining whether a difference between the overcurrent protection voltage of the IPM module and the set reference voltage is greater than a first set voltage threshold when it is determined that the output end of the comparison module has output the signal of the overcurrent of the IPM module and the current PWM duty ratio of the output signal does not reach the set PWM maximum duty ratio. Wherein the first set voltage threshold is as voltage threshold V Threshold 1 。
Step S520, when it is determined that the output end of the comparison module has output the signal of the IPM module over-current and the current PWM duty cycle of the output does not reach the set PWM maximum duty cycle, if it is determined that the difference between the over-current protection voltage of the IPM module and the set reference voltage is greater than the first set voltage threshold, it is determined that the IPM over-current protection circuit has a fault that the over-current protection value of the IPM over-current protection circuit is set to be too large.
Specifically, as shown in fig. 9, the fault detection flow of the IPM overcurrent protection circuit further includes: step 25, judging whether the value T of PWM duty ratio in overcurrent protection is satisfied Overcurrent flow The forward input voltage V of the corresponding comparator Overcurrent flow -preset comparator reverse input voltage V Preset reverse direction > voltage threshold V Threshold 1 : if yes, judging that the protection current value of the IPM overcurrent protection circuit is set to be too large; otherwise, step 26 is performed to determine whether the value T of the PWM duty cycle at the time of over-current protection is satisfied Overcurrent flow The forward input voltage V of the corresponding comparator Overcurrent flow -preset comparator reverse input voltage V Preset reverse direction < voltage threshold V Threshold 2 。
In some embodiments, in step S240, when it is determined that the output terminal of the comparison module has output the signal of the IPM module overcurrent and the current PWM duty cycle of the output does not reach the set PWM maximum duty cycle, determining whether the IPM overcurrent protection circuit has a fault according to the overcurrent protection voltage of the IPM module further includes: and a second process of determining whether the IPM overcurrent protection circuit has a fault according to the overcurrent protection voltage of the IPM module.
In the following, a flowchart of an embodiment of a second process for determining whether the IPM overcurrent protection circuit has a fault according to the overcurrent protection voltage of the IPM module in the method of the present invention shown in fig. 6 is further described, where the specific process for determining whether the IPM overcurrent protection circuit has a fault according to the overcurrent protection voltage of the IPM module in step S430 includes: step S610 to step S630.
Step S610, when it is determined that the output end of the comparison module has output the signal of the IPM module over-current and the current PWM duty cycle of the output does not reach the set PWM maximum duty cycle, if it is determined that the difference between the over-current protection voltage of the IPM module and the set reference voltage is less than or equal to the first set voltage threshold, it is determined whether the difference between the over-current protection voltage of the IPM module and the set reference voltage is less than the second set voltage threshold; wherein the second set voltage threshold is smaller than the first set voltage threshold, such as voltage threshold V Threshold 2 。
Step S620, when it is determined that the output terminal of the comparison module has output the signal of the IPM module overcurrent and the current PWM duty ratio of the output signal does not reach the set PWM maximum duty ratio, and when it is determined that the difference between the overcurrent protection voltage of the IPM module and the set reference voltage is less than or equal to the first set voltage threshold, if it is determined that the difference between the overcurrent protection voltage of the IPM module and the set reference voltage is less than the second set voltage threshold, it is determined that the IPM overcurrent protection circuit has a fault that the overcurrent protection value of the IPM overcurrent protection circuit is set too small.
Step S630, when it is determined that the output end of the comparison module has output the signal of the IPM module over-current and the current PWM duty ratio of the output does not reach the set PWM maximum duty ratio, and when it is determined that the difference between the over-current protection voltage of the IPM module and the set reference voltage is less than or equal to the first set voltage threshold, if it is determined that the difference between the over-current protection voltage of the IPM module and the set reference voltage is greater than or equal to the second set voltage threshold, it is determined that the IPM over-current protection circuit has not failed.
Specifically, as shown in fig. 9, the fault detection flow of the IPM overcurrent protection circuit further includes:
step 26, judging whether the value T of PWM duty ratio in overcurrent protection is satisfied Overcurrent flow The forward input voltage V of the corresponding comparator Overcurrent flow -preset comparator reverse input voltage V Preset reverse direction < voltage threshold V Threshold 2 : if yes, judging that the protection current value of the IPM overcurrent protection circuit is set to be too small; otherwise, step 27 is performed.
Step 27, if the voltage threshold V Threshold 2 Value T of PWM duty cycle at overcurrent protection Overcurrent flow The forward input voltage V of the corresponding comparator Overcurrent flow -preset comparator reverse input voltage V Preset reverse direction < voltage threshold V Threshold 1 And judging that the IPM overcurrent protection circuit is normal.
If judging that the IPM overcurrent protection circuit fails, is too large and too small, displaying corresponding fault codes, and reporting and repairing by a user; and if no abnormality exists, the operation is continued. V (V) Threshold 1 、V Threshold 2 According to the detection precision and the error requirement, setting and according to the overcurrent protection voltage V Overcurrent flow With a preset voltage V Preset reverse direction The difference value between the two is used for judging whether the IPM overcurrent protection circuit works abnormally or not. If the overcurrent protection voltage V Overcurrent flow Than a preset voltage V Preset reverse direction Much greater than IPM overcurrent protectionThe normally set protection current of the protection circuit is too much, and the over-current protection circuit is judged to be too large; if the overcurrent protection voltage V Overcurrent flow Than a preset voltage V Preset reverse direction If the current is too small, the current flowing through the sampling resistor of the compressor is too small compared with the protection current which is normally set by the IPM overcurrent protection circuit, and the overcurrent protection circuit is judged to be too small.
In the scheme of the invention, a fault self-checking function of the IPM overcurrent protection circuit is started, two IGBT tubes of the same bridge arm in the IPM module are driven to be simultaneously switched, so that the PWM duty ratio of the two IGBT tubes of the same bridge arm in the IPM module is increased, an overcurrent signal is detected in the process of increasing the PWM duty ratio of the two IGBT tubes of the same bridge arm in the IPM module, and whether the IPM overcurrent protection circuit is abnormal is judged according to the time and conditions (such as the equal forward input voltage and the equal reverse input voltage of a comparator) of the detected overcurrent signal. Specifically, in the working stage, the fault self-checking function of the IPM overcurrent protection circuit is started, PWM duty ratio signals are changed according to preset conditions, voltage drops at two ends of a current sampling resistor of a compressor are synchronously detected to serve as the overcurrent signals, PWM duty ratios at the moment of the overcurrent signals are generated, a voltage value corresponding to the PWM duty ratios is inquired through a list of different voltages corresponding to different PWM duty ratios stored in the development stage, and whether the IPM overcurrent protection circuit works normally is judged through deviation of the voltage value and the preset voltage value.
The driving circuit of the control board PWM duty ratio signal is the same in the development stage and the working stage, and the PWM duty ratio in the working stage is consistent with the voltage at two ends of the sampling resistor corresponding to the PWM duty ratio in the development stage. The working phase requires the voltage values recorded with the development phase. In the scheme of the invention, the PWM duty ratio signal of the original driving IPM module of the air conditioner is used, and a specific implementation method is provided, so that the PWM resource of the main control chip is not occupied. In the scheme of the invention, the PWM duty ratio is changed according to preset conditions, whether the IPM overcurrent circuit is abnormal or not is judged, and after the judgment of the abnormality of the IPM overcurrent protection circuit, the fault shutdown of the air conditioner is controlled.
At step S140, if it is determined that the IPM overcurrent protection circuit has failed, the load is controlled to stop and a warning message of the IPM overcurrent protection circuit failure is initiated.
At step S150, if it is determined that the IPM overcurrent protection circuit has not failed, the load is controlled to be started and operated.
According to the scheme provided by the invention, before the IPM module of the air conditioner drives the permanent magnet synchronous motor, the automatic fault detection function of the IPM overcurrent protection circuit is started, the MCU outputs PWM driving signals which enable the PWM duty ratios of two IGBT tubes of the same bridge arm in the IPM module to be increased, the two IGBT tubes of the same bridge arm in the IPM module are controlled to be simultaneously turned on and off, the protection voltage triggering the IPM overcurrent protection circuit during overcurrent protection is obtained, and the protection voltage is compared with a preset voltage value, so that whether the IPM overcurrent protection circuit works normally is judged. Therefore, only the switching logic of two IGBT tubes of the same bridge arm in the IPM module is changed, the voltage drops at the two ends of the current sampling resistor of the compressor are synchronously detected to serve as overcurrent signals, whether the IPM overcurrent protection circuit works abnormally or not can be judged, the air conditioner is prevented from running for a long time in the abnormal state of the IPM overcurrent protection circuit, the reliability of the variable-frequency air conditioner is improved through the automatic fault detection function without increasing the circuit structure and the cost, the running reliability of the air conditioner is improved, and the use experience of a user is improved.
By adopting the technical scheme of the embodiment, an IPM overcurrent protection circuit is arranged by aiming at an IPM module on a control panel of the air conditioner; a sampling resistor (such as a sampling resistor RS 1) is arranged between the IPM module and the ground; in the development stage of a control board of the air conditioner, when two IGBT tubes of the same bridge arm in the IPM module are controlled to be simultaneously turned on and off, the output PWM duty ratio is increased from the PWM initial duty ratio to the PWM maximum duty ratio according to a set amplitude, and the forward input voltage of a comparator in an IPM overcurrent protection circuit under each output PWM duty ratio is tested and recorded to be used as the overcurrent protection voltage of the IPM overcurrent protection circuit under each PWM duty ratio in the working stage of the control board of the air conditioner; before the IPM module drives the permanent magnet synchronous motor in the working stage of a control panel of the air conditioner, controlling two IGBT tubes of the same bridge arm in the IPM module to be simultaneously turned on and off, increasing the output PWM duty ratio from the PWM initial duty ratio to the PWM maximum duty ratio according to a set amplitude, and detecting whether the forward input voltage and the reverse input voltage of a comparator in the IPM overcurrent protection circuit are equal or not; if the forward input voltage and the reverse input voltage of the comparator in the IPM overcurrent protection circuit are not detected to be equal, judging that the IPM overcurrent protection circuit fails; if the forward input voltage and the reverse input voltage of the comparator in the IPM overcurrent protection circuit are detected to be equal, judging whether the protection value set by the IPM overcurrent protection circuit is too large or too small according to the overcurrent protection voltage of the IPM overcurrent protection circuit under the PWM duty ratio at the moment; therefore, before the permanent magnet synchronous motor is driven by the IPM module, the switching logic of the two IGBT tubes of the same bridge arm in the IPM module is changed, and the voltage drop at the two ends of the current sampling resistor of the compressor is synchronously detected to serve as an overcurrent signal so as to perform fault detection on the IPM overcurrent protection circuit, thereby avoiding the air conditioner from running for a long time in the abnormal state of the IPM overcurrent protection circuit and being beneficial to improving the safety and the user experience.
According to an embodiment of the present invention, there is also provided a control device of an IPM overcurrent protection device corresponding to the control method of the IPM overcurrent protection device. The IPM overcurrent protection device includes: the IPM module, sampling module, and IPM overcurrent protection circuit, sampling module such as sampling resistor RS1; the IPM module includes: an inverter bridge composed of six IGBT tubes; the IPM overcurrent protection circuit includes: a comparison module, such as a comparator; direct current bus voltage is connected to the collectors of IGBT tubes of upper bridges of three bridge arms in the inverter bridge; the emitters of IGBT tubes of lower bridges of three bridge arms in the inverter bridge are connected and then connected to the first connecting end of the sampling module; the second connecting end of the sampling module is grounded; the first connecting end of the sampling module is also connected to the non-inverting input end of the comparison module, namely to the positive input end of the comparator, and is used for inputting the sampling voltage obtained by sampling by the sampling module; the inverting input of the comparison module, i.e. the inverting input of the comparator, is used for inputting a set reference voltage, such as the inverting input voltage V of a preset comparator Preset reverse direction The method comprises the steps of carrying out a first treatment on the surface of the The output end of the comparison module is used for sampling input at the non-inverting input end of the comparison module And outputting the overcurrent signal of the IPM module under the condition that the sample voltage is the same as the set reference voltage input by the inverting input end of the comparator. Specifically, fig. 7 is a schematic structural diagram of an embodiment of an IPM overcurrent protection circuit of an air conditioner. The IPM overcurrent protection circuit of the air conditioner as shown in fig. 7 includes: the intelligent power supply comprises an IPM module, a current sampling resistor RS1 of the compressor, a motor (such as a permanent magnet synchronous motor) in the compressor, an IPM overcurrent protection circuit and the like. Six IGBT tubes, namely an IGBT tube G1, an IGBT tube G2, an IGBT tube G3, an IGBT tube G4, an IGBT tube G5 and an IGBT tube G6 are arranged in the IPM module. An IPM overcurrent protection circuit comprising: resistor R1, resistor R2, comparator, capacitor C1.DC+ is a DC bus voltage signal, V Reverse direction For inverting the input voltage signal of the comparator, V Forward direction For the forward input voltage signal of the comparator, ipm_oc is the output voltage signal of the comparator.
The IGBT tube G1, the IGBT tube G2, the IGBT tube G3, the IGBT tube G4, the IGBT tube G5 and the IGBT tube G6 form an inversion bridge, the IGBT tube G1 and the IGBT tube G4 form a first bridge arm, the IGBT tube G2 and the IGBT tube G5 form a second bridge arm, the IGBT tube G3 and the IGBT tube G6 form a third bridge arm, the common ends of the emitter of the IGBT tube G1 and the collector of the IGBT tube G4 in the first bridge arm are connected to a first phase winding in the three-phase winding of the permanent magnet synchronous motor, the common ends of the emitter of the IGBT tube G2 and the collector of the IGBT tube G5 in the second bridge arm are connected to a second phase winding in the three-phase winding of the permanent magnet synchronous motor, and the common ends of the emitter of the IGBT tube G3 and the collector of the IGBT tube G6 in the third bridge arm are connected to a third phase winding in the three-phase winding of the permanent magnet synchronous motor. The direct-current bus voltage signal DC+ is respectively connected with the collector of the IGBT tube G1, the collector of the IGBT tube G2 and the collector of the IGBT tube G3; the emitter of the IGBT tube G4, the emitter of the IGBT tube G5 and the emitter of the IGBT tube G6 are connected and then connected to a first connection end of a current sampling resistor RS1 of the compressor; the second connection end of the current sampling resistor RS1 of the compressor is grounded GND. The second connecting end of the current sampling resistor RS1 of the compressor is grounded GND after passing through the capacitor C1; the second connection end of the current sampling resistor RS1 of the compressor is also connected to the positive input end of the comparator for inputting the positive input voltage V Forward direction The method comprises the steps of carrying out a first treatment on the surface of the After +3.3V voltage passes through resistor R2 and resistor R1A common terminal of the ground GND, the resistor R2 and the resistor R1 connected to the inverting input terminal of the comparator for inputting the inverting input voltage V Reverse direction . And an output terminal of the comparator is used for outputting a voltage signal IPM_OC. When the forward input voltage V of the comparator Forward direction Is equal to the reverse input voltage V of the comparator Reverse direction The output voltage signal ipm_oc of the comparator is normally at a high level.
In an aspect of the present invention, a control device of the IPM overcurrent protection device includes: and a control unit.
The control unit is configured to determine any one of three bridge arms in the IPM module and record the determined bridge arm as a current bridge arm in the IPM module. The specific function and process of the control unit are shown in step S110.
The control unit is further configured to output a set series of PWM duty ratios for the two IGBT tubes of the current bridge arm in the IPM module in a development stage of the IPM overcurrent protection device, so as to control the two IGBT tubes of the current bridge arm in the IPM module to be turned on and off simultaneously, and record the sampling voltage input at the non-inverting input end of the comparison module under each PWM duty ratio output during the period as the overcurrent protection voltage of the IPM overcurrent protection circuit under each PWM duty ratio in an operation stage of the IPM overcurrent protection device. The specific function and processing of the control unit is also referred to in step S120.
In some embodiments, in a development stage of the IPM overcurrent protection device, the control unit outputs a set series of PWM duty cycles for two IGBT tubes of a current bridge arm in the IPM module to control the two IGBT tubes of the current bridge arm in the IPM module to be turned on and off simultaneously, including: the control unit is specifically configured to output a set PWM duty cycle according to a set control period for two IGBT tubes of a current bridge arm in the IPM module in a development stage of the IPM overcurrent protection device so as to control the two IGBT tubes of the current bridge arm in the IPM module to be simultaneously turned on and turned off; wherein the set PWM duty cycles output in different control periods form a set series of PWM duty cycles.
Wherein the control unit outputs a set PWM duty cycle per control period, comprising: the control unit is specifically configured to output a set PWM initial duty cycle in a first control period; the PWM duty cycle output from the second control period is increased by a set amplitude, e.g. by the amplitude T of each change of the PWM duty cycle, based on the PWM duty cycle output from the previous control period x Until the set PWM maximum duty cycle is increased.
Specifically, fig. 8 is a flow chart of an embodiment of a voltage measurement flow of a current sampling resistor of a compressor of an air conditioner. In the example shown in FIG. 8, T i To drive the PWM duty ratio, T of two IGBT tubes of the same bridge arm in the IPM module to switch simultaneously x For each change in amplitude, T, of PWM duty cycle 0 For PWM initial duty cycle, T max For the maximum PWM duty cycle, the amplitude T of each change of the PWM duty cycle x PWM initial duty cycle T 0 PWM maximum duty cycle T max Can be adjusted according to practical application, and the PWM initial duty ratio T 0 PWM duty ratio T for simultaneously switching two IGBT tubes of same bridge arm in IPM module i PWM maximum duty cycle T max . The MCU is a main control chip of the air conditioner.
As shown in fig. 8, a voltage measurement flow of a current sampling resistor of a compressor includes:
step 11, controlling PWM duty ratio T of two IGBT tubes for driving the same bridge arm in the IPM module to switch simultaneously i Amplitude T varied each time with PWM duty cycle x For amplitude, from PWM initial duty cycle T 0 Up to PWM maximum duty cycle T max Step 12 is then performed.
Step 12, voltage of current sampling resistor of compressor and forward input voltage V of comparator Forward direction Is of the same voltage. Changing PWM duty ratio T of two IGBT tubes for driving same bridge arm in IPM module to switch simultaneously i The magnitude of the voltage is changed, namely the voltage at two ends of a sampling resistor of the compressor is changed, and the PWM duty ratio T of two IGBT tubes which drive the same bridge arm in the IPM module and are simultaneously switched is tested i Forward input voltage V of lower comparator Forward direction The PWM duty ratio T of two IGBT tubes simultaneously switching on and off of the same bridge arm in each driving IPM module is recorded and stored i The lower voltage value is reserved for subsequent inquiry and judgment.
When the IPM overcurrent protection circuit is used as an automatic fault detection component, the MCU of the main control chip outputs a PWM duty ratio T i And the same PWM duty ratio signal is used for controlling two IGBT tubes of the same bridge arm in the IPM module to be simultaneously turned on and turned off, such as an IGBT tube G1 and an IGBT tube G4, an IGBT tube G2 and an IGBT tube G5, and an IGBT tube G3 and an IGBT tube G6. When the direct-current bus is switched on, current flows from the positive end DC+ of the direct-current bus to the ground GND through the IGBT tube G1, the IGBT tube G4 and the sampling resistor RS 1; when turned off, the current is cut off. By varying the PWM duty cycle T i Can change the voltage across the sampling resistor RS1, i.e. the forward input voltage V of the comparator Forward direction . When the IPM module is used as a component for driving the permanent magnet synchronous motor, two IGBT tubes of the same bridge arm in the IPM module cannot be simultaneously switched, but are complementarily switched. During complementary switching, a current signal passes through the IGBT tube G1 from the positive end DC+ of the direct current bus to the permanent magnet synchronous motor, then passes through the IGBT tube G5 and the IGBT tube G6, and finally passes through the sampling resistor RS1 to the ground GND. When two IGBT tubes of the same bridge arm in the IPM module are simultaneously switched, current does not pass through the permanent magnet synchronous motor, and therefore the problem that the compressor is demagnetized due to overlarge current during fault self-detection is avoided.
In the development stage (such as design stage) of the control board of the air conditioner, the resistance values of the resistor R1 and the resistor R2 are adjusted according to the requirements, and the reverse input voltage V of the comparator is preset Preset reverse direction And recording and storing in the MCU, and reserving for subsequent inquiry and judgment. When the IPM overcurrent protection circuit works normally, the reverse input voltage V of the comparator Reverse direction For the reverse input voltage V Preset reverse direction Known and unique, records and stores for subsequent judgment. For example: in the design stage of the control panel of the air conditioner, according to the demagnetizing current of the compressor, the IPM overcurrent protection circuit sets a protection current, for example, 27.5A, the resistance value of the sampling resistor RS1 is 0.01Ω, the resistance value of the resistor R1 is determined to be 20Ω, and the resistance value of the resistor R2 is determined to be 220Ω, so that the design requirement is met. If IPM overcurrent protectionWhen the protection current of the circuit is changed, the resistance values of the resistor R1, the resistor R2 and the resistor RS1 are correspondingly changed.
In the development stage, the MCU of the main control chip outputs a PWM duty ratio T i From PWM initial duty cycle T 0 Up to PWM maximum duty cycle T max The increment amplitude of each cycle is T x Each PWM duty cycle T is tested i Forward input voltage V of time comparator Forward direction The value is recorded and stored in the MCU, and is reserved for subsequent inquiry and judgment. Wherein the PWM initial duty cycle T 0 PWM maximum duty cycle T max Can be adjusted according to practical application, as shown in fig. 8. Changing PWM duty cycle T i The voltage of the sampling resistor RS1 of the compressor is changed, and the voltage is measured and recorded and stored in each PWM duty ratio T i The lower voltage value is reserved for subsequent inquiry.
In the scheme of the invention, the switching logic of two IGBT tubes of the same bridge arm in the IPM module is changed, the two IGBT tubes of the same bridge arm in the IPM module are driven to be simultaneously switched by presetting different PWM duty ratio signals, the voltage drop at two ends of a current sampling resistor of the compressor is measured, and the measured voltage drop at two ends of the current sampling resistor of the compressor is recorded and stored in a main control chip. Specifically, in the development stage of the air conditioner, the PWM duty ratio signal is changed, the voltages at two ends of the sampling resistor under different PWM duty ratio signals are recorded, namely, the list of different voltages corresponding to different PWM duty ratios is stored in the main control chip and is reserved for subsequent inquiry.
The control unit is further configured to output a set series of PWM duty cycles for the two IGBT tubes of the current bridge arm in the IPM module before the IPM module drives the load in the working stage of the IPM overcurrent protection device, so as to control the two IGBT tubes of the current bridge arm in the IPM module to be simultaneously turned on and off, and during the period, combine whether the output end of the comparison module outputs the signal of the IPM module overcurrent, the overcurrent protection voltage of the IPM overcurrent protection circuit under the corresponding PWM duty cycle under the condition that the output end of the comparison module outputs the signal of the IPM module overcurrent, and whether the output current PWM duty cycle is the set PWM maximum duty cycle, so as to determine whether the IPM overcurrent protection circuit has a fault. The specific function and processing of the control unit is also referred to in step S130.
In some embodiments, the control unit outputs a set series of PWM duty cycles for two IGBT tubes of a current bridge arm in the IPM module before the IPM module drives a load in an operation stage of the IPM overcurrent protection device, to control the two IGBT tubes of the current bridge arm in the IPM module to be turned on and off simultaneously, including: the control unit is specifically configured to gradually increase a set amplitude from a set PWM initial duty ratio to a set PWM maximum duty ratio for two IGBT tubes of a current bridge arm in the IPM module before the IPM module drives a load in the working stage of the IPM overcurrent protection device so as to control the two IGBT tubes of the current bridge arm in the IPM module to be simultaneously on-off.
The control unit, before the IPM module drives a load in the working phase of the IPM overcurrent protection device, outputs a set series of PWM duty ratios for two IGBT tubes of a current bridge arm in the IPM module to control the two IGBT tubes of the current bridge arm in the IPM module to be simultaneously turned on and off, combines whether the output end of the comparison module outputs the IPM module overcurrent signal during the period, and determines whether the IPM overcurrent protection circuit fails or not according to the overcurrent protection voltage of the IPM overcurrent protection circuit and whether the output current PWM duty ratio is the set PWM maximum duty ratio under the condition that the output end of the comparison module outputs the IPM module overcurrent signal, and includes:
The control unit is specifically configured to output a current PWM duty ratio for two IGBT tubes of a current bridge arm in the IPM module by taking the set PWM initial duty ratio as the current PWM duty ratio before the IPM module drives a load in the working stage of the IPM overcurrent protection device so as to control the two IGBT tubes of the current bridge arm in the IPM module to be simultaneously turned on and turned off. The specific function and processing of the control unit is also referred to in step S210.
The control unit is specifically further configured to determine whether the output end of the comparison module outputs the signal of the IPM module overcurrent. The specific function and processing of the control unit is also referred to in step S220.
Specifically, fig. 9 is a flowchart illustrating an embodiment of a method for automatic fault detection of an IPM overcurrent protection circuit of an air conditioner. In the example shown in FIG. 9, V Preset reverse direction For the reverse input voltage of the preset comparator, the resistance values of the resistor R1 and the resistor R2 are adjusted to obtain the required preset value, V Threshold 1 、V Threshold 2 The threshold voltage for abnormality determination can be adjusted according to actual use. Referring to the example shown in fig. 7, six IGBT tubes G1 to G6 are provided in the IPM module, and are controlled by PWM1 signals to PWM6 signals output by the main control chip MCU, respectively, to drive the permanent magnet synchronous motor to operate. RS1 is a current sampling resistor, and an IPM overcurrent protection circuit is formed by a resistor R1, a resistor R2, a capacitor C1, a comparator and the like. The larger the current through the sampling resistor RS1, the forward input voltage V of the comparator Forward direction The larger the positive input voltage V of the comparator Forward direction With negative input voltage V Negative going In the same case, the output voltage signal ipm_oc of the comparator is an overcurrent signal. For different compressors and different IPM modules, the negative input voltage V of the comparator can be changed by adjusting the resistance values of the resistor R1 and the resistor R2 Negative going The purpose of adjusting the magnitude of the protection current is achieved. For example: resistor R1 is 20Ω, resistor R2 is 220Ω, and voltage division calculation is performed to obtain V Reverse direction Is 0.275V. Sampling resistor RS1 is 0.01Ω, and when current I through the sampling resistor is equal to 27.5A, V Forward direction Equal to 0.275V, the comparator outputs an over-current signal ipm_oc at this time.
As shown in fig. 9, the fault detection flow of the IPM overcurrent protection circuit includes:
step 21, before the IPM module drives the permanent magnet synchronous motor, starting an automatic fault detection function of the IPM overcurrent protection circuit, and outputting a PWM1 driving signal, a PWM4 driving signal and a PWM duty ratio T by the MCU i For PWM initial duty cycle T 0 And controlling synchronous switching of the IGBT tube G1 and the IGBT tube G4, and synchronously executing step 22, namely synchronously detecting whether the overcurrent signal IPM_OC is detected.
Step 22 synchronously detects whether an over-current signal ipm_oc is detected: if it isIf not, go to step 23 to make PWM duty cycle T i Increasing the amplitude T of each change of PWM duty cycle x The method comprises the steps of carrying out a first treatment on the surface of the If yes, step 24 is performed to record the value of the PWM duty cycle at the time of over-current protection.
And the control unit is specifically configured to determine whether the IPM overcurrent protection circuit has a fault by combining whether the output current PWM duty ratio is the set PWM maximum duty ratio if it is determined that the output end of the comparison module does not output the IPM module overcurrent signal. The specific function and processing of the control unit is also referred to in step S230.
In some embodiments, the control unit, when determining that the output terminal of the comparison module does not output the IPM module overcurrent signal, determines whether the IPM overcurrent protection circuit has a fault in combination with whether the output current PWM duty cycle is the set PWM maximum duty cycle, including:
the control unit is specifically further configured to increase the set amplitude with the set PWM initial duty ratio under the condition that it is determined that the output end of the comparison module does not output the signal of the IPM module overcurrent, to serve as a new current PWM duty ratio, and to determine whether the new current PWM duty ratio reaches the set PWM maximum duty ratio. The specific function and processing of the control unit is also referred to in step S310.
And the control unit is specifically configured to determine that the IPM overcurrent protection circuit fails if the new current PWM duty ratio is determined to reach the set PWM maximum duty ratio under the condition that the output end of the comparison module does not output the IPM module overcurrent signal. The specific function and processing of the control unit is also referred to in step S320.
And the control unit is specifically configured to return to continuously determine whether the output end of the comparison module outputs the signal of the IPM module overcurrent if the new current PWM duty ratio is determined not to reach the set PWM maximum duty ratio under the condition that the output end of the comparison module does not output the signal of the IPM module overcurrent. The specific function and processing of the control unit is also referred to in step S330.
Specifically, as shown in fig. 9, the fault detection flow of the IPM overcurrent protection circuit further includes: step 23, if no over-current signal ipm_oc is detected, PWM duty cycle T i Increasing the amplitude T of each change of PWM duty cycle x PWM duty cycle T thereafter i Judging whether the maximum duty ratio T of PWM is reached max : if yes, it is determined that the IPM overcurrent protection circuit fails, otherwise, the process returns to step 22.
PWM duty cycle T i Increasing the amplitude T of each change of PWM duty cycle x Up to the maximum PWM duty cycle T max Exceeding the PWM maximum duty cycle T max And if the overcurrent signal IPM_OC is not detected, judging that the IPM overcurrent protection circuit fails. PWM maximum duty cycle T max In order to develop the stage, according to the actual application set value, PWM duty ratio T i On to PWM maximum duty cycle T max And if the current flowing through the sampling resistor of the compressor reaches the maximum and exceeds the protection current normally set by the IPM overcurrent protection circuit, judging that the IPM overcurrent protection circuit fails.
The control unit is specifically further configured to determine whether the IPM overcurrent protection circuit has a fault according to an overcurrent protection voltage of the IPM overcurrent protection circuit under a PWM duty ratio corresponding to the condition that the output end of the comparison module outputs the IPM module overcurrent signal if it is determined that the output end of the comparison module has output the IPM module overcurrent signal. The specific function and processing of the control unit is also referred to in step S240.
In some embodiments, the control unit, when determining that the output terminal of the comparison module has output the IPM module overcurrent signal and the current PWM duty cycle of the output has not reached the set PWM maximum duty cycle, determines whether the IPM overcurrent protection circuit has a fault according to the overcurrent protection voltage of the IPM overcurrent protection circuit at the PWM duty cycle corresponding to the output terminal of the comparison module output the IPM module overcurrent signal, including:
The control unit is specifically further configured to record the PWM duty cycle output when the output end of the comparison module has output the IPM module overcurrent signal, and the output current PWM duty cycle does not reach the set PWM maximum duty cycle, and record the PWM duty cycle as the overcurrent PWM duty cycle. The specific function and processing of the control unit is also referred to in step S410.
The control unit is specifically further configured to, when it is determined that the output end of the comparison module has output the IPM module overcurrent signal and the output current PWM duty ratio does not reach the set PWM maximum duty ratio, take, as the overcurrent protection voltage of the IPM module, the sampling voltage recorded in the development stage of the IPM overcurrent protection device and input at the non-inverting input end of the comparison module at each output PWM duty ratio recorded in the development stage of the IPM overcurrent protection device. The specific function and processing of the control unit is also referred to in step S420.
The control unit is specifically further configured to determine whether the IPM overcurrent protection circuit fails according to the overcurrent protection voltage of the IPM module when it is determined that the output end of the comparison module has output the signal of the overcurrent of the IPM module and the current PWM duty ratio of the output signal does not reach the set PWM maximum duty ratio. The specific function and processing of the control unit is also referred to in step S430.
Specifically, as shown in fig. 9, the fault detection flow of the IPM overcurrent protection circuit further includes: step 24, if PWM duty cycle T i From PWM initial duty cycle T 0 To PWM maximum duty cycle T max If an overcurrent signal is detected, the value of PWM duty ratio at the time of overcurrent protection is recorded and is recorded as T Overcurrent flow Querying a value T of PWM duty cycle in overcurrent protection Overcurrent flow The positive input voltage of the corresponding comparator is denoted as V Overcurrent flow Step 25 is then performed to determine whether the value T of the PWM duty cycle at the time of over-current protection is satisfied Overcurrent flow The forward input voltage V of the corresponding comparator Overcurrent flow -preset comparator reverse input voltage V Preset reverse direction > voltage threshold V Threshold 1 。V Overcurrent flow Is the recorded value in the example shown in fig. 8.
In some embodiments, the control unit, when determining that the output terminal of the comparison module has output the signal of the IPM module overcurrent and the current PWM duty cycle of the output does not reach the set PWM maximum duty cycle, determines, according to the overcurrent protection voltage of the IPM module, whether the IPM overcurrent protection circuit has a fault, including: the first process of determining whether the IPM overcurrent protection circuit has a fault according to the overcurrent protection voltage of the IPM module is specifically as follows:
The control unit is specifically further configured to determine whether a difference between the overcurrent protection voltage of the IPM module and a set reference voltage is greater than a first set voltage threshold when it is determined that the output end of the comparison module has output the signal of the overcurrent of the IPM module and the current PWM duty ratio of the output does not reach the set PWM maximum duty ratio. The specific function and processing of the control unit is also referred to in step S510. Wherein the first set voltage threshold is as voltage threshold V Threshold 1 。
The control unit is specifically further configured to determine that the IPM overcurrent protection circuit has a fault that the overcurrent protection value of the IPM overcurrent protection circuit is set to be too large if it is determined that the difference between the overcurrent protection voltage of the IPM module and the set reference voltage is greater than the first set voltage threshold under the condition that it is determined that the output end of the comparison module has output the signal of the IPM module overcurrent and the output current PWM duty ratio does not reach the set PWM maximum duty ratio. The specific function and processing of the control unit is also referred to in step S520.
Specifically, as shown in fig. 9, the fault detection flow of the IPM overcurrent protection circuit further includes: step 25, judging whether the value T of PWM duty ratio in overcurrent protection is satisfied Overcurrent flow The forward input voltage V of the corresponding comparator Overcurrent flow -preset comparator reverse input voltage V Preset reverse direction > voltage threshold V Threshold 1 : if yes, judging that the protection current value of the IPM overcurrent protection circuit is set to be too large; otherwise, step 26 is performed to determine whether PWM at the time of over-current protection is satisfiedValue T of duty cycle Overcurrent flow The forward input voltage V of the corresponding comparator Overcurrent flow -preset comparator reverse input voltage V Preset reverse direction < voltage threshold V Threshold 2 。
In some embodiments, the control unit determines, according to the overcurrent protection voltage of the IPM module, whether the IPM overcurrent protection circuit has a fault, if it is determined that the output terminal of the comparison module has output the signal of the IPM module overcurrent and the current PWM duty ratio of the output does not reach the set PWM maximum duty ratio, and further includes: and a second process of determining whether the IPM overcurrent protection circuit has a fault according to the overcurrent protection voltage of the IPM module, specifically as follows:
the control unit is specifically configured to determine, if it is determined that the difference between the overcurrent protection voltage of the IPM module and the set reference voltage is less than or equal to a first set voltage threshold, whether the difference between the overcurrent protection voltage of the IPM module and the set reference voltage is less than a second set voltage threshold, if it is determined that the output end of the comparison module has output the signal of the overcurrent of the IPM module and the current PWM duty ratio of the output does not reach the set PWM maximum duty ratio; wherein the second set voltage threshold is smaller than the first set voltage threshold, such as voltage threshold V Threshold 2 . The specific function and processing of the control unit is also referred to in step S610.
The control unit is specifically further configured to, when it is determined that the output end of the comparison module has output the signal of the IPM module over-current and the current PWM duty ratio of the output does not reach the set PWM maximum duty ratio, determine that the IPM over-current protection circuit has a fault that the over-current protection value of the IPM over-current protection circuit is set too small if it is determined that the difference between the over-current protection voltage of the IPM module and the set reference voltage is smaller than or equal to the first set voltage threshold. The specific function and processing of the control unit is also referred to in step S620.
The control unit is specifically further configured to, when it is determined that the output end of the comparison module has output the signal of the IPM module over-current and the current PWM duty ratio of the output does not reach the set PWM maximum duty ratio, determine that the IPM over-current protection circuit has no fault if it is determined that the difference between the over-current protection voltage of the IPM module and the set reference voltage is less than or equal to the first set voltage threshold and that the difference between the over-current protection voltage of the IPM module and the set reference voltage is greater than or equal to the second set voltage threshold. The specific function and processing of the control unit is also referred to step S630.
Specifically, as shown in fig. 9, the fault detection flow of the IPM overcurrent protection circuit further includes:
step 26, judging whether the value T of PWM duty ratio in overcurrent protection is satisfied Overcurrent flow The forward input voltage V of the corresponding comparator Overcurrent flow -preset comparator reverse input voltage V Preset reverse direction < voltage threshold V Threshold 2 : if yes, judging that the protection current value of the IPM overcurrent protection circuit is set to be too small; otherwise, step 27 is performed.
Step 27, if the voltage threshold V Threshold 2 Value T of PWM duty cycle at overcurrent protection Overcurrent flow The forward input voltage V of the corresponding comparator Overcurrent flow -preset comparator reverse input voltage V Preset reverse direction < voltage threshold V Threshold 1 And judging that the IPM overcurrent protection circuit is normal.
If judging that the IPM overcurrent protection circuit fails, is too large and too small, displaying corresponding fault codes, and reporting and repairing by a user; and if no abnormality exists, the operation is continued. V (V) Threshold 1 、V Threshold 2 According to the detection precision and the error requirement, setting and according to the overcurrent protection voltage V Overcurrent flow With a preset voltage V Preset reverse direction The difference value between the two is used for judging whether the IPM overcurrent protection circuit works abnormally or not. If the overcurrent protection voltage V Overcurrent flow Than a preset voltage V Preset reverse direction If the current is too large, the current flowing through the sampling resistor of the compressor is too large compared with the protection current normally set by the IPM overcurrent protection circuit, and the overcurrent protection circuit is judged to be excessively largeThe method comprises the steps of carrying out a first treatment on the surface of the If the overcurrent protection voltage V Overcurrent flow Than a preset voltage V Preset reverse direction If the current is too small, the current flowing through the sampling resistor of the compressor is too small compared with the protection current which is normally set by the IPM overcurrent protection circuit, and the overcurrent protection circuit is judged to be too small.
In the scheme of the invention, a fault self-checking function of the IPM overcurrent protection circuit is started, two IGBT tubes of the same bridge arm in the IPM module are driven to be simultaneously switched, so that the PWM duty ratio of the two IGBT tubes of the same bridge arm in the IPM module is increased, an overcurrent signal is detected in the process of increasing the PWM duty ratio of the two IGBT tubes of the same bridge arm in the IPM module, and whether the IPM overcurrent protection circuit is abnormal is judged according to the time and conditions (such as the equal forward input voltage and the equal reverse input voltage of a comparator) of the detected overcurrent signal. Specifically, in the working stage, the fault self-checking function of the IPM overcurrent protection circuit is started, PWM duty ratio signals are changed according to preset conditions, voltage drops at two ends of a current sampling resistor of a compressor are synchronously detected to serve as the overcurrent signals, PWM duty ratios at the moment of the overcurrent signals are generated, a voltage value corresponding to the PWM duty ratios is inquired through a list of different voltages corresponding to different PWM duty ratios stored in the development stage, and whether the IPM overcurrent protection circuit works normally is judged through deviation of the voltage value and the preset voltage value.
The driving circuit of the control board PWM duty ratio signal is the same in the development stage and the working stage, and the PWM duty ratio in the working stage is consistent with the voltage at two ends of the sampling resistor corresponding to the PWM duty ratio in the development stage. The working phase requires the voltage values recorded with the development phase. In the scheme of the invention, the PWM duty ratio signal of the original driving IPM module of the air conditioner is used, and a specific implementation method is provided, so that the PWM resource of the main control chip is not occupied. In the scheme of the invention, the PWM duty ratio is changed according to preset conditions, whether the IPM overcurrent circuit is abnormal or not is judged, and after the judgment of the abnormality of the IPM overcurrent protection circuit, the fault shutdown of the air conditioner is controlled.
The control unit is further configured to control the load to stop and initiate a warning message of the IPM overcurrent protection circuit failure if it is determined that the IPM overcurrent protection circuit has failed. The specific function and processing of the control unit is also referred to in step S140.
And the control unit is further configured to control the load to start and operate if the IPM overcurrent protection circuit is determined to not have a fault. The specific function and processing of the control unit is also referred to in step S150.
According to the scheme provided by the invention, before the IPM module of the air conditioner drives the permanent magnet synchronous motor, the automatic fault detection function of the IPM overcurrent protection circuit is started, the MCU outputs PWM driving signals which enable the PWM duty ratios of two IGBT tubes of the same bridge arm in the IPM module to be increased, the two IGBT tubes of the same bridge arm in the IPM module are controlled to be simultaneously turned on and off, the protection voltage triggering the IPM overcurrent protection circuit during overcurrent protection is obtained, and the protection voltage is compared with a preset voltage value, so that whether the IPM overcurrent protection circuit works normally is judged. Therefore, only the switching logic of two IGBT tubes of the same bridge arm in the IPM module is changed, the voltage drops at the two ends of the current sampling resistor of the compressor are synchronously detected to serve as overcurrent signals, whether the IPM overcurrent protection circuit works abnormally or not can be judged, the air conditioner is prevented from running for a long time in the abnormal state of the IPM overcurrent protection circuit, the reliability of the variable-frequency air conditioner is improved through the automatic fault detection function without increasing the circuit structure and the cost, the running reliability of the air conditioner is improved, and the use experience of a user is improved.
Since the processes and functions implemented by the apparatus of the present embodiment substantially correspond to the embodiments, principles and examples of the foregoing methods, the descriptions of the embodiments are not exhaustive, and reference may be made to the descriptions of the foregoing embodiments and their descriptions are omitted herein.
By adopting the technical scheme of the invention, the IPM overcurrent protection circuit is arranged on the IPM module on the control panel of the air conditioner; a sampling resistor (such as a sampling resistor RS 1) is arranged between the IPM module and the ground; in the development stage of a control board of the air conditioner, when two IGBT tubes of the same bridge arm in the IPM module are controlled to be simultaneously turned on and off, the output PWM duty ratio is increased from the PWM initial duty ratio to the PWM maximum duty ratio according to a set amplitude, and the forward input voltage of a comparator in an IPM overcurrent protection circuit under each output PWM duty ratio is tested and recorded to be used as the overcurrent protection voltage of the IPM overcurrent protection circuit under each PWM duty ratio in the working stage of the control board of the air conditioner; before the IPM module drives the permanent magnet synchronous motor in the working stage of a control panel of the air conditioner, controlling two IGBT tubes of the same bridge arm in the IPM module to be simultaneously turned on and off, increasing the output PWM duty ratio from the PWM initial duty ratio to the PWM maximum duty ratio according to a set amplitude, and detecting whether the forward input voltage and the reverse input voltage of a comparator in the IPM overcurrent protection circuit are equal or not; if the forward input voltage and the reverse input voltage of the comparator in the IPM overcurrent protection circuit are not detected to be equal, judging that the IPM overcurrent protection circuit fails; if the forward input voltage and the reverse input voltage of the comparator in the IPM overcurrent protection circuit are detected to be equal, judging whether the protection value set by the IPM overcurrent protection circuit is too large or too small according to the overcurrent protection voltage of the IPM overcurrent protection circuit under the PWM duty ratio at the moment; the PWM duty ratio is changed according to preset conditions, whether the IPM overcurrent circuit is abnormal or not is judged, and after the judgment of the abnormality of the IPM overcurrent protection circuit, the air conditioner is controlled to stop in a fault mode, so that the safety is improved.
According to an embodiment of the present invention, there is also provided an air conditioner corresponding to a control device of an IPM overcurrent protection device. The air conditioner may include: the control device of the IPM overcurrent protection device described above.
Since the processes and functions implemented by the air conditioner of the present embodiment basically correspond to the embodiments, principles and examples of the foregoing apparatus, the description of the present embodiment is not exhaustive, and reference may be made to the related descriptions of the foregoing embodiments, which are not repeated herein.
By adopting the technical scheme of the invention, the IPM overcurrent protection circuit is arranged on the IPM module on the control panel of the air conditioner; a sampling resistor (such as a sampling resistor RS 1) is arranged between the IPM module and the ground; in the development stage of a control board of the air conditioner, when two IGBT tubes of the same bridge arm in the IPM module are controlled to be simultaneously turned on and off, the output PWM duty ratio is increased from the PWM initial duty ratio to the PWM maximum duty ratio according to a set amplitude, and the forward input voltage of a comparator in an IPM overcurrent protection circuit under each output PWM duty ratio is tested and recorded to be used as the overcurrent protection voltage of the IPM overcurrent protection circuit under each PWM duty ratio in the working stage of the control board of the air conditioner; before the IPM module drives the permanent magnet synchronous motor in the working stage of a control panel of the air conditioner, controlling two IGBT tubes of the same bridge arm in the IPM module to be simultaneously turned on and off, increasing the output PWM duty ratio from the PWM initial duty ratio to the PWM maximum duty ratio according to a set amplitude, and detecting whether the forward input voltage and the reverse input voltage of a comparator in the IPM overcurrent protection circuit are equal or not; if the forward input voltage and the reverse input voltage of the comparator in the IPM overcurrent protection circuit are not detected to be equal, judging that the IPM overcurrent protection circuit fails; if the forward input voltage and the reverse input voltage of the comparator in the IPM overcurrent protection circuit are detected to be equal, judging whether the protection value set by the IPM overcurrent protection circuit is too large or too small according to the overcurrent protection voltage of the IPM overcurrent protection circuit under the PWM duty ratio at the moment; through the automated inspection fault function that does not increase circuit structure and cost, improve variable frequency air conditioner reliability, improve the operational reliability of air conditioner, promote user's use experience.
According to an embodiment of the present invention, there is further provided a storage medium corresponding to a control method of an IPM overcurrent protection device, the storage medium including a stored program, wherein an apparatus in which the storage medium is controlled to execute the control method of the IPM overcurrent protection device described above when the program runs.
Since the processes and functions implemented by the storage medium of the present embodiment substantially correspond to the embodiments, principles and examples of the foregoing methods, the descriptions of the present embodiment are not exhaustive, and reference may be made to the related descriptions of the foregoing embodiments, which are not repeated herein.
By adopting the technical scheme of the invention, the IPM overcurrent protection circuit is arranged on the IPM module on the control panel of the air conditioner; a sampling resistor (such as a sampling resistor RS 1) is arranged between the IPM module and the ground; in the development stage of a control board of the air conditioner, when two IGBT tubes of the same bridge arm in the IPM module are controlled to be simultaneously turned on and off, the output PWM duty ratio is increased from the PWM initial duty ratio to the PWM maximum duty ratio according to a set amplitude, and the forward input voltage of a comparator in an IPM overcurrent protection circuit under each output PWM duty ratio is tested and recorded to be used as the overcurrent protection voltage of the IPM overcurrent protection circuit under each PWM duty ratio in the working stage of the control board of the air conditioner; before the IPM module drives the permanent magnet synchronous motor in the working stage of a control panel of the air conditioner, controlling two IGBT tubes of the same bridge arm in the IPM module to be simultaneously turned on and off, increasing the output PWM duty ratio from the PWM initial duty ratio to the PWM maximum duty ratio according to a set amplitude, and detecting whether the forward input voltage and the reverse input voltage of a comparator in the IPM overcurrent protection circuit are equal or not; if the forward input voltage and the reverse input voltage of the comparator in the IPM overcurrent protection circuit are not detected to be equal, judging that the IPM overcurrent protection circuit fails; if the forward input voltage and the reverse input voltage of the comparator in the IPM overcurrent protection circuit are detected to be equal, judging whether the protection value set by the IPM overcurrent protection circuit is too large or too small according to the overcurrent protection voltage of the IPM overcurrent protection circuit under the PWM duty ratio at the moment; the air conditioner is prevented from running for a long time in the abnormal state of the IPM overcurrent protection circuit, and the running safety of the air conditioner and the use experience of a user can be improved.
In summary, it is readily understood by those skilled in the art that the above-described advantageous ways can be freely combined and superimposed without conflict.
The above description is only an example of the present invention and is not intended to limit the present invention, but various modifications and variations can be made to the present invention by those skilled in the art. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention should be included in the scope of the claims of the present invention.

Claims (10)

1. A control method of an IPM overcurrent protection device, wherein the IPM overcurrent protection device includes: the device comprises an IPM module, a sampling module and an IPM overcurrent protection circuit; the IPM module includes: an inverter bridge composed of six IGBT tubes; the IPM overcurrent protection circuit includes: a comparison module; direct current bus voltage is connected to the collectors of IGBT tubes of upper bridges of three bridge arms in the inverter bridge; the emitters of IGBT tubes of lower bridges of three bridge arms in the inverter bridge are connected and then connected to the first connecting end of the sampling module; the second connecting end of the sampling module is grounded; the first connecting end of the sampling module is also connected to the non-inverting input end of the comparison module and is used for inputting the sampling voltage obtained by sampling by the sampling module; the inverting input end of the comparison module is used for inputting a set reference voltage; the output end of the comparison module is used for outputting the overcurrent signal of the IPM module under the condition that the sampling voltage input by the non-inverting input end of the comparison module is the same as the set reference voltage input by the inverting input end of the comparator; the control method of the IPM overcurrent protection device comprises the following steps:
Determining any one of three bridge arms in the IPM module, and marking the determined bridge arm as a current bridge arm in the IPM module;
in the development stage of the IPM overcurrent protection device, a set series of PWM duty ratios are output for two IGBT tubes of a current bridge arm in the IPM module so as to control the two IGBT tubes of the current bridge arm in the IPM module to be simultaneously switched on and off, and sampling voltages input at the non-inverting input end of the comparison module under each PWM duty ratio output are recorded in the period;
before the IPM module drives a load, outputting a set series of PWM duty ratios for two IGBT tubes of a current bridge arm in the IPM module so as to control the two IGBT tubes of the current bridge arm in the IPM module to be simultaneously on-off, and determining whether the IPM overcurrent protection circuit has faults by combining whether an output end of the comparison module outputs an overcurrent signal of the IPM module, an overcurrent protection voltage of the IPM overcurrent protection circuit under a corresponding PWM duty ratio under the condition that the output end of the comparison module outputs the overcurrent signal of the IPM module, and whether the output current PWM duty ratio is a set PWM maximum duty ratio;
If the IPM overcurrent protection circuit is determined to have faults, controlling the load to stop and initiating reminding information of the faults of the IPM overcurrent protection circuit;
and if the IPM overcurrent protection circuit is determined not to have faults, controlling the load to start and operate.
2. The method for controlling an IPM overcurrent protection apparatus according to claim 1, wherein in a development stage of the IPM overcurrent protection apparatus, outputting a set series of PWM duty cycles for two IGBT tubes of a current bridge arm in the IPM module to control simultaneous on-off of the two IGBT tubes of the current bridge arm in the IPM module, comprising:
in the development stage of the IPM overcurrent protection device, outputting a set PWM duty ratio according to a set control period aiming at two IGBT tubes of a current bridge arm in the IPM module, so as to control the two IGBT tubes of the current bridge arm in the IPM module to be simultaneously switched on and off; wherein, the set PWM duty ratios output in different control periods form a set series of PWM duty ratios;
wherein outputting a set PWM duty cycle per control period, comprising: in the first control period, outputting a set PWM initial duty ratio; the PWM duty cycle output by each control period is increased by a set amplitude from the second control period to the set PWM maximum duty cycle based on the PWM duty cycle output by the previous control period.
3. The method of controlling an IPM overcurrent protection apparatus according to claim 1, wherein outputting the set series of PWM duty cycles comprises: starting from the set PWM initial duty ratio, gradually increasing the set amplitude until the set PWM maximum duty ratio is increased;
before the IPM module drives a load, outputting a set series of PWM duty ratios for two IGBT tubes of a current bridge arm in the IPM module to control the two IGBT tubes of the current bridge arm in the IPM module to be simultaneously turned on and off, wherein during the period, whether the output end of the comparison module outputs the IPM module overcurrent signal, the overcurrent protection voltage of the IPM overcurrent protection circuit under the corresponding PWM duty ratio under the condition that the output end of the comparison module outputs the IPM module overcurrent signal, and whether the output current PWM duty ratio is the set PWM maximum duty ratio are combined, and determining whether the IPM overcurrent protection circuit has a fault comprises the following steps:
in the working stage of the IPM overcurrent protection device, before the IPM module drives a load, aiming at two IGBT tubes of a current bridge arm in the IPM module, taking a set PWM initial duty ratio as the current PWM duty ratio, and outputting the current PWM duty ratio so as to control the two IGBT tubes of the current bridge arm in the IPM module to be simultaneously switched on and off;
Determining whether the output end of the comparison module outputs an overcurrent signal of the IPM module;
if the fact that the output end of the comparison module does not output the overcurrent signal of the IPM module is determined, whether the IPM overcurrent protection circuit fails or not is determined by combining whether the output current PWM duty ratio is the set PWM maximum duty ratio or not;
if it is determined that the output end of the comparison module outputs the IPM module overcurrent signal, determining whether the IPM overcurrent protection circuit has a fault according to the overcurrent protection voltage of the IPM overcurrent protection circuit under the PWM duty ratio corresponding to the condition that the output end of the comparison module outputs the IPM module overcurrent signal.
4. The method of controlling an IPM overcurrent protection apparatus according to claim 3, wherein determining whether the IPM overcurrent protection circuit has a fault in combination with whether the current PWM duty cycle of the output is the set PWM maximum duty cycle comprises:
after increasing the set amplitude by the set PWM initial duty cycle, taking the set amplitude as a new current PWM duty cycle, and determining whether the new current PWM duty cycle reaches the set PWM maximum duty cycle;
if the new current PWM duty cycle is determined to reach the set PWM maximum duty cycle, determining that the IPM overcurrent protection circuit fails;
And if the new current PWM duty ratio is not up to the set PWM maximum duty ratio, returning to continuously determine whether the output end of the comparison module outputs the overcurrent signal of the IPM module.
5. The method according to claim 3 or 4, wherein determining whether the IPM overcurrent protection circuit has a fault according to an overcurrent protection voltage of the IPM overcurrent protection circuit at a corresponding PWM duty ratio in a case where the output terminal of the comparison module outputs the signal of the IPM module overcurrent, comprises:
recording the PWM duty cycle output when the output end of the comparison module outputs the overcurrent signal of the IPM module, and recording the PWM duty cycle as the overcurrent PWM duty cycle;
according to the sampling voltage which is recorded in the development stage of the IPM overcurrent protection device and is input at the non-inverting input end of the comparison module under each output PWM duty cycle, the sampling voltage which is recorded in the development stage of the IPM overcurrent protection device and is input at the non-inverting input end of the comparison module under the overcurrent PWM duty cycle is used as the overcurrent protection voltage of the IPM module;
and determining whether the IPM overcurrent protection circuit has faults according to the overcurrent protection voltage of the IPM module.
6. The method of controlling an IPM overcurrent protection apparatus according to claim 5, wherein determining whether the IPM overcurrent protection circuit has a fault according to an overcurrent protection voltage of the IPM module comprises:
determining whether a difference between an over-current protection voltage of the IPM module and a set reference voltage is greater than a first set voltage threshold;
if the difference value between the over-current protection voltage of the IPM module and the set reference voltage is larger than the first set voltage threshold value, the over-current protection circuit is determined to have a fault that the over-current protection value of the IPM over-current protection circuit is set to be too large.
7. The method of controlling an IPM overcurrent protection apparatus according to claim 6, wherein determining whether the IPM overcurrent protection circuit has a fault according to an overcurrent protection voltage of the IPM module, further comprises:
if the difference value between the overcurrent protection voltage of the IPM module and the set reference voltage is smaller than or equal to a first set voltage threshold value, determining whether the difference value between the overcurrent protection voltage of the IPM module and the set reference voltage is smaller than a second set voltage threshold value; wherein the second set voltage threshold is less than the first set voltage threshold;
If the difference value between the overcurrent protection voltage of the IPM module and the set reference voltage is smaller than a second set voltage threshold value, determining that the overcurrent protection circuit of the IPM module has a fault that the overcurrent protection value of the overcurrent protection circuit is set to be too small;
and if the difference value between the overcurrent protection voltage of the IPM module and the set reference voltage is larger than or equal to a second set voltage threshold value, determining that the IPM overcurrent protection circuit has no fault.
8. A control device of an IPM overcurrent protection device, wherein the IPM overcurrent protection device includes: the device comprises an IPM module, a sampling module and an IPM overcurrent protection circuit; the IPM module includes: an inverter bridge composed of six IGBT tubes; the IPM overcurrent protection circuit includes: a comparison module; direct current bus voltage is connected to the collectors of IGBT tubes of upper bridges of three bridge arms in the inverter bridge; the emitters of IGBT tubes of lower bridges of three bridge arms in the inverter bridge are connected and then connected to the first connecting end of the sampling module; the second connecting end of the sampling module is grounded; the first connecting end of the sampling module is also connected to the non-inverting input end of the comparison module and is used for inputting the sampling voltage obtained by sampling by the sampling module; the inverting input end of the comparison module is used for inputting a set reference voltage; the output end of the comparison module is used for outputting the overcurrent signal of the IPM module under the condition that the sampling voltage input by the non-inverting input end of the comparison module is the same as the set reference voltage input by the inverting input end of the comparator; the control device of the IPM overcurrent protection device comprises:
The control unit is configured to determine any one of three bridge arms in the IPM module and record the determined bridge arm as a current bridge arm in the IPM module;
the control unit is further configured to output a set series of PWM duty ratios for the two IGBT tubes of the current bridge arm in the IPM module in a development stage of the IPM overcurrent protection device so as to control the two IGBT tubes of the current bridge arm in the IPM module to be simultaneously switched on and switched off, and record sampling voltages input at the non-inverting input end of the comparison module under each PWM duty ratio output during the period;
the control unit is further configured to output a set series of PWM duty cycles for two IGBT tubes of a current bridge arm in the IPM module before the IPM module drives a load in an operation stage of the IPM overcurrent protection device, so as to control the two IGBT tubes of the current bridge arm in the IPM module to be simultaneously turned on and off, and determine whether the IPM overcurrent protection circuit fails according to whether an output end of the comparison module outputs an IPM module overcurrent signal, an overcurrent protection voltage of the IPM overcurrent protection circuit under a corresponding PWM duty cycle when the output end of the comparison module outputs the IPM module overcurrent signal, and whether the output current PWM duty cycle is a set PWM maximum duty cycle;
The control unit is further configured to control the load to stop and initiate a reminding message of the fault of the IPM overcurrent protection circuit if the fault of the IPM overcurrent protection circuit is determined;
and the control unit is further configured to control the load to start and operate if the IPM overcurrent protection circuit is determined to not have a fault.
9. An air conditioner, comprising: the control device of IPM overcurrent protection device according to claim 8.
10. A storage medium comprising a stored program, wherein the program, when run, controls a device in which the storage medium is located to execute the control method of the IPM overcurrent protection apparatus according to any one of claims 1 to 7.
CN202311795330.XA 2023-12-25 2023-12-25 Control method and device of IPM overcurrent protection device, air conditioner and storage medium Pending CN117791509A (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
CN202311795330.XA CN117791509A (en) 2023-12-25 2023-12-25 Control method and device of IPM overcurrent protection device, air conditioner and storage medium

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
CN202311795330.XA CN117791509A (en) 2023-12-25 2023-12-25 Control method and device of IPM overcurrent protection device, air conditioner and storage medium

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CN117791509A true CN117791509A (en) 2024-03-29

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