CN114567232A - Overtemperature protection method of variable frequency driving device and variable frequency driving device - Google Patents

Overtemperature protection method of variable frequency driving device and variable frequency driving device Download PDF

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Publication number
CN114567232A
CN114567232A CN202210095597.7A CN202210095597A CN114567232A CN 114567232 A CN114567232 A CN 114567232A CN 202210095597 A CN202210095597 A CN 202210095597A CN 114567232 A CN114567232 A CN 114567232A
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circuit
power
temperature
over
temperature threshold
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Inventor
林晓词
汪号芝
苏永权
许荣再
颜培炎
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Xiamen Hualian Electronics Co Ltd
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Xiamen Hualian Electronics Co Ltd
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    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02P—CONTROL OR REGULATION OF ELECTRIC MOTORS, ELECTRIC GENERATORS OR DYNAMO-ELECTRIC CONVERTERS; CONTROLLING TRANSFORMERS, REACTORS OR CHOKE COILS
    • H02P29/00—Arrangements for regulating or controlling electric motors, appropriate for both AC and DC motors
    • H02P29/60—Controlling or determining the temperature of the motor or of the drive
    • H02P29/68—Controlling or determining the temperature of the motor or of the drive based on the temperature of a drive component or a semiconductor component
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02P—CONTROL OR REGULATION OF ELECTRIC MOTORS, ELECTRIC GENERATORS OR DYNAMO-ELECTRIC CONVERTERS; CONTROLLING TRANSFORMERS, REACTORS OR CHOKE COILS
    • H02P21/00—Arrangements or methods for the control of electric machines by vector control, e.g. by control of field orientation
    • H02P21/22—Current control, e.g. using a current control loop
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02P—CONTROL OR REGULATION OF ELECTRIC MOTORS, ELECTRIC GENERATORS OR DYNAMO-ELECTRIC CONVERTERS; CONTROLLING TRANSFORMERS, REACTORS OR CHOKE COILS
    • H02P23/00—Arrangements or methods for the control of AC motors characterised by a control method other than vector control
    • H02P23/26—Power factor control [PFC]
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02P—CONTROL OR REGULATION OF ELECTRIC MOTORS, ELECTRIC GENERATORS OR DYNAMO-ELECTRIC CONVERTERS; CONTROLLING TRANSFORMERS, REACTORS OR CHOKE COILS
    • H02P27/00—Arrangements or methods for the control of AC motors characterised by the kind of supply voltage
    • H02P27/04—Arrangements or methods for the control of AC motors characterised by the kind of supply voltage using variable-frequency supply voltage, e.g. inverter or converter supply voltage
    • H02P27/06—Arrangements or methods for the control of AC motors characterised by the kind of supply voltage using variable-frequency supply voltage, e.g. inverter or converter supply voltage using dc to ac converters or inverters
    • H02P27/08—Arrangements or methods for the control of AC motors characterised by the kind of supply voltage using variable-frequency supply voltage, e.g. inverter or converter supply voltage using dc to ac converters or inverters with pulse width modulation
    • H02P27/085—Arrangements or methods for the control of AC motors characterised by the kind of supply voltage using variable-frequency supply voltage, e.g. inverter or converter supply voltage using dc to ac converters or inverters with pulse width modulation wherein the PWM mode is adapted on the running conditions of the motor, e.g. the switching frequency
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02B—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO BUILDINGS, e.g. HOUSING, HOUSE APPLIANCES OR RELATED END-USER APPLICATIONS
    • Y02B70/00—Technologies for an efficient end-user side electric power management and consumption
    • Y02B70/10—Technologies improving the efficiency by using switched-mode power supplies [SMPS], i.e. efficient power electronics conversion e.g. power factor correction or reduction of losses in power supplies or efficient standby modes

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  • Engineering & Computer Science (AREA)
  • Power Engineering (AREA)
  • Inverter Devices (AREA)

Abstract

The invention provides an over-temperature protection method of a variable frequency driving device and the variable frequency driving device, wherein the method comprises the following steps: in the running process of the alternating current motor, acquiring the input voltage of a power supply circuit, the output voltage and the output current of a driving circuit in real time, and calculating a preliminary over-temperature threshold value of a power module of the driving circuit; comparing the preliminary over-temperature threshold value with the maximum temperature value allowed by the power module to determine a final over-temperature threshold value; acquiring the temperature of the power module, and judging whether the temperature of the power module exceeds a final over-temperature threshold value or not so as to adjust the speed instruction when the temperature of the power module exceeds the final over-temperature threshold value, so that the driving circuit drives the alternating current motor to work according to the adjusted speed instruction; therefore, the over-temperature threshold of the power module is adaptively adjusted according to the input voltage, the output voltage and the output current, and the rotating speed instruction is adjusted according to the over-temperature threshold, so that the power devices of the power factor correction circuit and the inverter circuit power module are prevented from being overhigh in temperature.

Description

Overtemperature protection method of variable frequency driving device and variable frequency driving device
Technical Field
The invention relates to the technical field of variable frequency driving, in particular to an over-temperature protection method of a variable frequency driving device and the variable frequency driving device.
Background
In the related art, in order to improve the overall efficiency of the variable frequency driver and solve the problem of power harmonic pollution, the power factor correction technology is widely applied to various variable frequency driving systems, such as an air purification fan driver, a variable frequency air conditioner driver, a variable frequency refrigerator driver and the like; the power tube of the power factor correction circuit and the power module (IPM module) of the inverter circuit are main heating devices, the heating value of the devices is large when the devices work, the temperature can rise sharply when the heat dissipation condition is not good, and the circuit can be damaged when the temperature of the power devices exceeds the junction temperature, so that the whole system can not work normally.
The power module of the existing variable frequency driving system is usually internally provided with a temperature sensor, can acquire more accurate temperature, and adopts the protection actions of limiting frequency, reducing frequency or stopping, and the like to prevent over-temperature when the temperature is higher; different input voltages, input powers, switching frequencies and environmental temperatures can affect the temperature rise of a power tube of the power factor correction circuit, and the power tube is difficult to directly acquire a real-time temperature value for over-temperature protection because a built-in temperature sensor is not arranged in the power tube; for example, when the switching frequency of the PFC is higher, the loss of the power tube of the PFC is higher, and the temperature rise thereof is higher and faster than that of the IPM module; if the temperature sensor is arranged on the power tube, the heat conductivity coefficient is low, the temperature of the power tube rises quickly, the temperature of the power tube is difficult to accurately reflect, and the power tube is complex to install, poor in consistency and high in cost.
Disclosure of Invention
The present invention is directed to solving at least one of the technical problems in the art to some extent. Therefore, an object of the present invention is to provide an over-temperature protection method for a variable frequency driving device, which adaptively adjusts an over-temperature threshold of a power module according to an input voltage, an output voltage and an output current, and adjusts a rotation speed command according to the over-temperature threshold, so as to prevent the power devices of a power factor correction circuit and an inverter circuit power module from having too high temperatures.
The second purpose of the invention is to provide a variable frequency driving device.
In order to achieve the above object, an embodiment of the first aspect of the present invention provides an over-temperature protection method for a variable frequency driving apparatus, where the variable frequency driving apparatus includes a power circuit, a power factor correction circuit, a driving circuit, a sampling circuit, an interface circuit, and a control circuit, the interface circuit is connected to the control circuit, the control circuit is respectively connected to the power circuit, the driving circuit, and the sampling circuit, the power circuit is respectively connected to the power factor correction circuit and the sampling circuit, the power factor correction circuit is connected to the driving circuit, the driving circuit is respectively connected to the sampling circuit and an ac motor, the control circuit receives a speed command sent by the interface circuit, and adjusts the driving circuit to drive the ac motor to operate according to the speed command, the over-temperature protection method comprises the following steps: in the running process of the alternating current motor, the control circuit acquires the input voltage of the power supply circuit and the output voltage and the output current of the driving circuit, which are acquired by the sampling circuit, in real time; calculating a preliminary over-temperature threshold value of a power module of the driving circuit according to the input voltage of the power circuit, the output voltage and the output current of the driving circuit; comparing the preliminary over-temperature threshold value with a maximum temperature value allowed by the power module to determine a final over-temperature threshold value; and acquiring the temperature of the power module, and judging whether the temperature of the power module exceeds the final over-temperature threshold value or not so as to adjust the speed instruction when the temperature of the power module exceeds the final over-temperature threshold value, so that the driving circuit drives the alternating current motor to work according to the adjusted speed instruction.
According to the over-temperature protection method of the variable frequency driving device, in the running process of the alternating current motor, the control circuit obtains the input voltage of the power circuit and the output voltage and the output current of the driving circuit which are acquired by the sampling circuit in real time; calculating a preliminary over-temperature threshold of a power module of the driving circuit according to the input voltage of the power circuit, the output voltage and the output current of the driving circuit; comparing the preliminary over-temperature threshold value with the maximum temperature value allowed by the power module to determine a final over-temperature threshold value; acquiring the temperature of the power module, and judging whether the temperature of the power module exceeds a final over-temperature threshold value or not so as to adjust the speed instruction when the temperature of the power module exceeds the final over-temperature threshold value, so that the driving circuit drives the alternating current motor to work according to the adjusted speed instruction; therefore, the over-temperature threshold of the power module is adaptively adjusted according to the input voltage, the output voltage and the output current, and the rotating speed instruction is adjusted according to the over-temperature threshold, so that the power devices of the power factor correction circuit and the inverter circuit power module are prevented from being overhigh in temperature.
In addition, the method for protecting the variable frequency driving device from the over-temperature according to the above embodiment of the present invention may further have the following additional technical features:
Optionally, the power supply circuit includes a filter circuit and a rectifier circuit, and the filter circuit and the rectifier circuit are configured to perform rectification and filtering processing on input alternating current, so that the sampling circuit collects an input voltage after the rectification and filtering.
Optionally, the driving circuit includes an inverter circuit and a PWM driving circuit, and the PWM driving circuit drives a power module of the inverter circuit according to a PWM signal output by the control circuit, so as to drive the ac motor to operate according to the speed command.
Optionally, the preliminary over-temperature threshold of the power module of the driving circuit is calculated according to the following formula:
Pin＝A1Pout+B1
Figure BDA0003490903790000021
Tprot＝A2Iin+B2
wherein, PinTo input power, PoutTo output power, A1And B1Taking a plurality of power points in an input power range, recording measured input power and calculated output power, and linearly fitting to obtain a coefficient; i isinFor input of current, VinIn order to input the voltage, the voltage is,
Figure BDA0003490903790000022
determining according to the power factor of an input power supply, wherein the value is between 0 and 1; t isprotTo obtain a preliminary over-temperature threshold, A2And B2In order to obtain a plurality of voltage points in an input voltage range, an alternating current motor runs at a plurality of input power points, a precise temperature acquisition instrument is utilized to measure the real-time temperature of a power tube of a power factor correction circuit, and the corresponding input current I when the power tube of the power factor correction circuit reaches a required over-temperature threshold value is recorded inTemperature T of power moduleIPMAnd fitting the coefficients linearly.
Optionally, comparing the preliminary over-temperature threshold with a maximum temperature value allowed by the power module to determine a final over-temperature threshold, including: judging whether the preliminary over-temperature threshold value is larger than the maximum temperature value allowed by the power module; if the preliminary over-temperature threshold value is larger than the maximum temperature value allowed by the power module, taking the maximum temperature value allowed by the power module as a final over-temperature threshold value; and if the preliminary over-temperature threshold value is less than or equal to the maximum temperature value allowed by the power module, taking the preliminary over-temperature threshold value as a final over-temperature threshold value.
Optionally, if the temperature of the power module exceeds the final over-temperature threshold, subtracting a preset speed difference value from the speed instruction to obtain a current speed instruction, and adjusting the driving circuit to drive the alternating current motor to work according to the current speed instruction.
In order to achieve the above object, a second embodiment of the present invention provides a variable frequency driving apparatus, including: the power supply circuit is used for rectifying and filtering input alternating current to obtain processed input voltage; the power factor correction circuit is connected with the power circuit and improves the input power factor by controlling the on-off of a power tube; the driving circuit is connected with the power factor correction circuit and is used for driving the alternating current motor to work; the sampling circuit is respectively connected with the power circuit and the driving circuit and is used for acquiring the input voltage of the power circuit and the output voltage of the driving circuit in real time; an interface circuit for obtaining a speed command signal; the control circuit is respectively connected with the interface circuit, the sampling circuit and the driving circuit, receives a speed instruction sent by the interface circuit, adjusts the driving circuit to drive the alternating current motor to work according to the speed instruction, and acquires the input voltage of the power supply circuit and the output voltage and the output current of the driving circuit, which are acquired by the sampling circuit, in real time in the running process of the alternating current motor; calculating a preliminary over-temperature threshold value of a power module of the driving circuit according to the input voltage of the power circuit, the output voltage and the output current of the driving circuit; comparing the preliminary over-temperature threshold value with a maximum temperature value allowed by the power module to determine a final over-temperature threshold value; and acquiring the temperature of the power module, and judging whether the temperature of the power module exceeds the final over-temperature threshold value or not so as to adjust the speed instruction when the temperature of the power module exceeds the final over-temperature threshold value, so that the driving circuit drives the alternating current motor to work according to the adjusted speed instruction.
According to the variable frequency driving device disclosed by the embodiment of the invention, the input alternating current is subjected to rectification filtering processing through the power circuit so as to obtain the processed input voltage; the power factor correction circuit is connected with the power circuit and is used for improving the input power factor by controlling the on-off of the power tube; the driving circuit is connected with the power factor correction circuit and is used for driving the alternating current motor to work; the sampling circuit is respectively connected with the power circuit and the driving circuit and is used for acquiring the input voltage of the power circuit and the output voltage of the driving circuit in real time; the interface circuit is used for acquiring a speed command signal; the control circuit is respectively connected with the interface circuit, the sampling circuit and the driving circuit, receives a speed instruction sent by the interface circuit, adjusts the driving circuit to drive the alternating current motor to work according to the speed instruction, and acquires the input voltage of the power circuit and the output voltage and the output current of the driving circuit which are acquired by the sampling circuit in real time in the running process of the alternating current motor; calculating a preliminary over-temperature threshold of a power module of the driving circuit according to the input voltage of the power circuit, the output voltage and the output current of the driving circuit; comparing the preliminary over-temperature threshold value with the maximum temperature value allowed by the power module to determine a final over-temperature threshold value; acquiring the temperature of the power module, and judging whether the temperature of the power module exceeds a final over-temperature threshold value or not so as to adjust the speed instruction when the temperature of the power module exceeds the final over-temperature threshold value, so that the driving circuit drives the alternating current motor to work according to the adjusted speed instruction; therefore, the over-temperature threshold of the power module is adaptively adjusted according to the input voltage, the output voltage and the output current, and the rotating speed instruction is adjusted according to the over-temperature threshold, so that the power devices of the power factor correction circuit and the inverter circuit power module are prevented from being overhigh in temperature.
In addition, the variable frequency driving device proposed according to the above embodiment of the present invention may have the following additional technical features:
optionally, the preliminary over-temperature threshold of the power module of the driving circuit is calculated according to the following formula:
Pin＝A1Pout+B1
Figure BDA0003490903790000041
Tprot＝A2Iin+B2
wherein, PinTo input power, PoutTo output power, A1And B1Taking a plurality of power points in an input power range, recording measured input power and calculated output power, and linearly fitting to obtain a coefficient; i isinFor inputting current，VinIn order to input the voltage, the voltage is,
Figure BDA0003490903790000042
determining according to the power factor of an input power supply, wherein the value is between 0 and 1; t isprotTo obtain a preliminary over-temperature threshold, A2And B2In order to obtain a plurality of voltage points in an input voltage range, an alternating current motor runs at a plurality of input power points, a precise temperature acquisition instrument is utilized to measure the real-time temperature of a power tube of a power factor correction circuit, and the corresponding input current I when the power tube of the power factor correction circuit reaches a required over-temperature threshold value is recordedinTemperature T of power moduleIPMAnd fitting the obtained coefficients linearly.
Optionally, the control circuit is further configured to determine whether the preliminary over-temperature threshold is greater than a maximum temperature value allowed by the power module; if the preliminary over-temperature threshold value is larger than the maximum temperature value allowed by the power module, taking the maximum temperature value allowed by the power module as a final over-temperature threshold value; and if the preliminary over-temperature threshold value is less than or equal to the maximum temperature value allowed by the power module, taking the preliminary over-temperature threshold value as a final over-temperature threshold value.
Optionally, the control circuit is further configured to subtract a preset speed difference from the speed instruction to obtain a current speed instruction if the temperature of the power module exceeds the final over-temperature threshold, and adjust the driving circuit to drive the ac motor to operate according to the current speed instruction.
Drawings
Fig. 1 is a schematic flow chart of an over-temperature protection method for a variable frequency drive according to an embodiment of the present invention;
FIG. 2 is a schematic flow chart illustrating an over-temperature protection method for a variable frequency drive according to an embodiment of the present invention;
FIG. 3 is a block diagram of a variable frequency drive according to an embodiment of the present invention;
fig. 4 is a block schematic diagram of a variable frequency drive according to an embodiment of the present invention.
Detailed Description
Reference will now be made in detail to embodiments of the present invention, examples of which are illustrated in the accompanying drawings, wherein like or similar reference numerals refer to the same or similar elements or elements having the same or similar function throughout. The embodiments described below with reference to the drawings are illustrative and intended to be illustrative of the invention and are not to be construed as limiting the invention.
In order to better understand the above technical solutions, exemplary embodiments of the present invention will be described in more detail below with reference to the accompanying drawings. While exemplary embodiments of the invention are shown in the drawings, it should be understood that the invention can be embodied in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art.
In order to better understand the technical scheme, the technical scheme is described in detail in the following with reference to the attached drawings of the specification and specific embodiments.
As shown in fig. 1 and fig. 3, the variable frequency driving apparatus 10 includes a power circuit 15, a power factor correction circuit 11, a driving circuit 12, a sampling circuit 16, an interface circuit 14, and a control circuit 13, the interface circuit 14 is connected to the control circuit 13, the control circuit 13 is respectively connected to the power circuit 15, the driving circuit 12, and the sampling circuit 16, the power circuit 15 is respectively connected to the power factor correction circuit 11 and the sampling circuit 16, the power factor correction circuit 11 is connected to the driving circuit 12, the driving circuit 12 is respectively connected to an ac motor 10a and the sampling circuit 16, the control circuit 13 receives a speed command sent by the interface circuit 14, and adjusts the driving circuit 12 to drive the ac motor 10a to operate according to the speed command, and the over-temperature protection method includes the following steps:
step 101, in the running process of the alternating current motor, a control circuit obtains the input voltage of the power circuit and the output voltage and the output current of the driving circuit, which are acquired by a sampling circuit, in real time.
As an embodiment, as shown in fig. 4, the power supply circuit 15 includes a filter circuit 151 and a rectifier circuit 152, and the filter circuit 151 and the rectifier circuit 152 are configured to perform rectification and filtering processing on the input alternating current, so that the sampling circuit 16 collects the rectified and filtered input voltage.
That is, the input voltage collected by the sampling circuit 16 is a voltage obtained by rectifying an ac voltage.
The power supply circuit 15 further includes a switching power supply circuit 153.
As an embodiment, as shown in fig. 4, the driving circuit 12 includes an inverter circuit 121 and a PWM driving circuit 123, and the PWM driving circuit 123 drives a power module of the inverter circuit 121 according to a PWM signal output by the control circuit 13 so as to drive the ac motor 10a to operate according to a speed command.
As one embodiment, as shown in fig. 4, the control circuit 13 includes a memory 131 and a processing circuit 132.
And 102, calculating a preliminary over-temperature threshold value of a power module of the driving circuit according to the input voltage of the power circuit, the output voltage and the output current of the driving circuit.
As an embodiment, the preliminary over-temperature threshold of the power module of the driving circuit is calculated according to the following formula:
Pin＝A1Pout+B1
Figure BDA0003490903790000061
Tprot＝A2Iin+B2
wherein, PinFor input power, PoutTo output power, A1And B1Taking a plurality of power points in an input power range, recording measured input power and calculated output power, and linearly fitting to obtain a coefficient; i isinFor input of current, VinIn order to input the voltage, the voltage is,
Figure BDA0003490903790000062
determining according to the power factor of an input power supply, wherein the value is between 0 and 1; t is protTo preliminary over-temperature threshold, A2And B2In order to obtain a plurality of voltage points in an input voltage range, an alternating current motor runs at a plurality of input power points, a precise temperature acquisition instrument is utilized to measure the real-time temperature of a power tube of a power factor correction circuit, and the corresponding input current I when the power tube of the power factor correction circuit reaches a required over-temperature threshold value is recordedinTemperature T of power moduleIPMAnd fitting the obtained coefficients linearly.
Step 103, comparing the preliminary over-temperature threshold value with the maximum temperature value allowed by the power module to determine a final over-temperature threshold value.
As an embodiment, determining whether the preliminary over-temperature threshold is greater than a maximum temperature value allowed by the power module; if the preliminary over-temperature threshold value is larger than the maximum temperature value allowed by the power module, taking the maximum temperature value allowed by the power module as a final over-temperature threshold value; and if the preliminary over-temperature threshold value is less than or equal to the maximum temperature value allowed by the power module, taking the preliminary over-temperature threshold value as a final over-temperature threshold value.
It should be noted that the maximum temperature allowed by the power module is determined by the power module.
And 104, acquiring the temperature of the power module, and judging whether the temperature of the power module exceeds a final over-temperature threshold value or not so as to adjust the speed instruction when the temperature exceeds the final over-temperature threshold value, so that the driving circuit drives the alternating current motor to work according to the adjusted speed instruction.
As an embodiment, if the temperature of the power module exceeds the final over-temperature threshold, the current speed instruction is obtained by subtracting a preset speed difference from the speed instruction, and the driving circuit is adjusted according to the current speed instruction to drive the ac motor to work.
That is, if the temperature of the power module exceeds the final over-temperature threshold, performing over-temperature protection, namely subtracting a preset speed difference value from the speed instruction to obtain a current speed instruction, and adjusting the driving circuit to drive the alternating current motor to work according to the current speed instruction; and if the temperature of the power module does not exceed the final over-temperature threshold, the speed instruction is not adjusted, and the operation is carried out according to the originally set speed instruction.
As a specific embodiment, as shown in fig. 4, the method includes the following steps:
s1, measuring the input rectified voltage Vin。
S2, measuring the driving output voltage Vd、VqOutput current Id、IqCalculating the output power P according to the relationout：
Figure BDA0003490903790000071
S3, calculating the output power P according to the relationin：
Pin＝A1Pout+B1
Wherein A is1And B1In order to take a plurality of power points in the input power range, the measured input power and the calculated output power are recorded, and coefficients obtained by linear fitting are recorded.
S4, calculating the input current I according to the relational expression in：
Figure BDA0003490903790000072
Wherein, the first and the second end of the pipe are connected with each other,
Figure BDA0003490903790000073
the value is determined according to the power factor of the input power supply and ranges from 0 to 1.
S5, calculating the over-temperature threshold T of the inverter circuit power module according to the relational expressionprot：
Tprot＝A2Iin+B2
Wherein A is2And B2In order to obtain a plurality of voltage points in an input voltage range, an alternating current motor runs at a plurality of input power points, a precise temperature acquisition instrument is utilized to measure the real-time temperature of a power tube of a power factor correction circuit, and the corresponding input current I when the power tube of the power factor correction circuit reaches a required over-temperature threshold value is recordedinTemperature T of power moduleIPMAnd fitting the obtained coefficients linearly.
S6, according to the over-temperature threshold TprotAnd the maximum allowable temperature T of the power modulemaxComparing and determining the final over-temperature threshold value Tth。
That is, based on the calculated over-temperature threshold TprotAnd the maximum allowable temperature T of the power modulemaxComparing and determining the final over-temperature threshold value TthIf T isprot＞TmaxThen T isth＝TmaxOtherwise Tth＝Tprot。
S7, measuring the temperature T of the power moduleIPMJudging whether the temperature of the power module exceeds an over-temperature threshold value T or notthAfter the speed command is determined, execution returns to S1.
That is, the temperature T of the power module is measuredIPMDetermining the temperature T of the power moduleIPMWhether exceeding the over-temperature threshold TthIf T isIPM＞TthAnd if not, operating according to the current speed instruction, and returning to the step S1 for execution.
In summary, according to the over-temperature protection method for the variable frequency driving device in the embodiment of the invention, in the running process of the alternating current motor, the control circuit obtains the input voltage of the power circuit and the output voltage and the output current of the driving circuit, which are acquired by the sampling circuit, in real time; calculating a preliminary over-temperature threshold of a power module of the driving circuit according to the input voltage of the power circuit, the output voltage and the output current of the driving circuit; comparing the preliminary over-temperature threshold value with the maximum temperature value allowed by the power module to determine a final over-temperature threshold value; acquiring the temperature of the power module, and judging whether the temperature of the power module exceeds a final over-temperature threshold value or not so as to adjust the speed instruction when the temperature of the power module exceeds the final over-temperature threshold value, so that the driving circuit drives the alternating current motor to work according to the adjusted speed instruction; therefore, the over-temperature threshold of the power module is adaptively adjusted according to the input voltage, the output voltage and the output current, and the rotating speed instruction is adjusted according to the over-temperature threshold, so that the power devices of the power factor correction circuit and the inverter circuit power module are prevented from being overhigh in temperature.
As shown in fig. 3 and 4, the variable frequency drive apparatus 10 according to the embodiment of the present invention includes: a power supply circuit 15, a power factor correction circuit 11, a drive circuit 12, a sampling circuit 16, an interface circuit 14, and a control circuit 13.
The power supply circuit 15 performs rectification and filtering processing on the input alternating current to obtain a processed input voltage; the power factor correction circuit 11 is connected with the power circuit 15, and the power factor correction circuit 11 improves the input power factor by controlling the on-off of a power tube; the driving circuit 12 is connected with the power factor correction circuit 11, and the driving circuit 12 is used for driving the alternating current motor 10a to work; the sampling circuit 16 is respectively connected with the power circuit 15 and the driving circuit 12, and the sampling circuit 16 is used for collecting the input voltage of the power circuit and the output voltage of the driving circuit in real time; the interface circuit 14 is used for acquiring a speed command signal; the control circuit 13 is respectively connected with the interface circuit 14, the sampling circuit 16 and the driving circuit 12, the control circuit 13 receives a speed instruction sent by the interface circuit 14, adjusts the driving circuit 12 to drive the alternating current motor to work according to the speed instruction, and obtains the input voltage of the power supply circuit 15 and the output voltage and the output current of the driving circuit 12 which are acquired by the sampling circuit in real time in the running process of the alternating current motor 10 a; calculating a preliminary over-temperature threshold of the power module of the driving circuit 12 according to the input voltage of the power circuit 15 and the output voltage and the output current of the driving circuit 12; comparing the preliminary over-temperature threshold value with the maximum temperature value allowed by the power module to determine a final over-temperature threshold value; and acquiring the temperature of the power module, and judging whether the temperature of the power module exceeds a final over-temperature threshold value or not so as to adjust the speed instruction when the temperature exceeds the final over-temperature threshold value, so that the driving circuit drives the alternating current motor to work according to the adjusted speed instruction.
As an embodiment, the power circuit 15 includes a filter circuit 151 and a rectifier circuit 152, and the filter circuit 151 and the rectifier circuit 152 are used for performing rectification and filtering processing on the input alternating current so that the sampling circuit 16 collects the rectified and filtered input voltage.
As an embodiment, the driving circuit 12 includes an inverter circuit 121 and a PWM driving circuit 123, and the PWM driving circuit 123 drives a power module of the inverter circuit 121 according to a PWM signal output by the control circuit 13 so as to drive the ac motor 10a to operate according to a speed command.
That is, the power factor correction circuit 11 controls the power tube to adjust the input voltage and current phase according to a certain switching frequency and duty ratio, so as to improve the input power factor. The sampling circuit 16 collects the temperature, voltage and current of the power module in real time. The driving circuit 12 includes an inverter circuit 121 and a PWM driving circuit 123. The control circuit 13 receives the speed command signal transmitted from the interface circuit 14, and adjusts the drive circuit 12 in accordance with the speed command signal to drive the ac motor 10a to operate. In the running process of the alternating current motor 10a, the control circuit 13 calculates input current according to signals sent by the sampling circuit 16, calculates an over-temperature threshold value, monitors whether the temperature of the power driving module reaches the over-temperature threshold value in real time, and determines a current speed instruction; the PWM driving circuit 123 drives the power module of the inverter circuit 121 according to the PWM signal to drive the ac motor 10a to operate according to the speed command.
As an embodiment, the preliminary over-temperature threshold of the power module of the driving circuit is calculated according to the following formula:
Pin＝A1Pout+B1
Figure BDA0003490903790000091
Tprot＝A2Iin+B2
wherein, PinFor input power, PoutTo output power, A1And B1Taking a plurality of power points in an input power range, recording measured input power and calculated output power, and linearly fitting to obtain a coefficient; i isinFor input of current, VinIn order to input the voltage, the voltage is,
Figure BDA0003490903790000092
determining according to the power factor of an input power supply, wherein the value is between 0 and 1; t isprotTo obtain a preliminary over-temperature threshold, A2And B2In order to obtain a plurality of voltage points in an input voltage range, an alternating current motor runs at a plurality of input power points, a precise temperature acquisition instrument is utilized to measure the real-time temperature of a power tube of a power factor correction circuit, and the corresponding input current I when the power tube of the power factor correction circuit reaches a required over-temperature threshold value is recordedinTemperature T of power moduleIPMAnd fitting the obtained coefficients linearly.
As an embodiment, the control circuit 13 is further configured to determine whether the preliminary over-temperature threshold is greater than a maximum temperature value allowed by the power module; if the preliminary over-temperature threshold value is larger than the maximum temperature value allowed by the power module, taking the maximum temperature value allowed by the power module as a final over-temperature threshold value; and if the preliminary over-temperature threshold value is less than or equal to the maximum temperature value allowed by the power module, taking the preliminary over-temperature threshold value as a final over-temperature threshold value.
As an embodiment, the control circuit 13 is further configured to subtract a preset speed difference from the speed command to obtain a current speed command if the temperature of the power module exceeds the final over-temperature threshold, and adjust the driving circuit to drive the ac motor to operate according to the current speed command.
It should be noted that the foregoing description of the over-temperature protection method for the variable frequency driving apparatus is also applicable to the variable frequency driving apparatus of this embodiment, and is not repeated herein.
In summary, according to the variable frequency driving apparatus of the embodiment of the present invention, the power circuit performs rectification and filtering processing on the input ac to obtain a processed input voltage; the power factor correction circuit is connected with the power circuit and improves the input power factor by controlling the on-off of the power tube; the driving circuit is connected with the power factor correction circuit and is used for driving the alternating current motor to work; the sampling circuit is respectively connected with the power circuit and the driving circuit and is used for acquiring the input voltage of the power circuit and the output voltage of the driving circuit in real time; the interface circuit is used for acquiring a speed command signal; the control circuit is respectively connected with the interface circuit, the sampling circuit and the driving circuit, receives a speed instruction sent by the interface circuit, adjusts the driving circuit to drive the alternating current motor to work according to the speed instruction, and acquires the input voltage of the power circuit and the output voltage and the output current of the driving circuit which are acquired by the sampling circuit in real time in the running process of the alternating current motor; calculating a preliminary over-temperature threshold of a power module of the driving circuit according to the input voltage of the power circuit, the output voltage and the output current of the driving circuit; comparing the preliminary over-temperature threshold value with the maximum temperature value allowed by the power module to determine a final over-temperature threshold value; acquiring the temperature of the power module, and judging whether the temperature of the power module exceeds a final over-temperature threshold value or not so as to adjust the speed instruction when the temperature of the power module exceeds the final over-temperature threshold value, so that the driving circuit drives the alternating current motor to work according to the adjusted speed instruction; therefore, the over-temperature threshold of the power module is adaptively adjusted according to the input voltage, the output voltage and the output current, and the rotating speed instruction is adjusted according to the over-temperature threshold, so that the power devices of the power factor correction circuit and the inverter circuit power module are prevented from being overhigh in temperature.
As will be appreciated by one skilled in the art, embodiments of the present invention may be provided as a method, system, or computer program product. Accordingly, the present invention may take the form of an entirely hardware embodiment, an entirely software embodiment or an embodiment combining software and hardware aspects. Furthermore, the present invention may take the form of a computer program product embodied on one or more computer-usable storage media (including, but not limited to, disk storage, CD-ROM, optical storage, and the like) having computer-usable program code embodied therein.
The present invention is described with reference to flowchart illustrations and/or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of the invention. It will be understood that each flow and/or block of the flow diagrams and/or block diagrams, and combinations of flows and/or blocks in the flow diagrams and/or block diagrams, can be implemented by computer program instructions. These computer program instructions may be provided to a processor of a general purpose computer, special purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, create means for implementing the functions specified in the flowchart flow or flows and/or block diagram block or blocks.
These computer program instructions may also be stored in a computer-readable memory that can direct a computer or other programmable data processing apparatus to function in a particular manner, such that the instructions stored in the computer-readable memory produce an article of manufacture including instruction means which implement the function specified in the flowchart flow or flows and/or block diagram block or blocks.
These computer program instructions may also be loaded onto a computer or other programmable data processing apparatus to cause a series of operational steps to be performed on the computer or other programmable apparatus to produce a computer implemented process such that the instructions which execute on the computer or other programmable apparatus provide steps for implementing the functions specified in the flowchart flow or flows and/or block diagram block or blocks.
It should be noted that in the claims, any reference signs placed between parentheses shall not be construed as limiting the claim. The word "comprising" does not exclude the presence of elements or steps not listed in a claim. The word "a" or "an" preceding an element does not exclude the presence of a plurality of such elements. The invention may be implemented by means of hardware comprising several distinct elements, and by means of a suitably programmed computer. In the unit claims enumerating several means, several of these means can be embodied by one and the same item of hardware. The usage of the words first, second and third, etcetera do not indicate any ordering. These words may be interpreted as names.
While preferred embodiments of the present invention have been described, additional variations and modifications in those embodiments may occur to those skilled in the art once they learn of the basic inventive concepts. Therefore, it is intended that the appended claims be interpreted as including the preferred embodiment and all changes and modifications that fall within the scope of the invention.
It will be apparent to those skilled in the art that various changes and modifications may be made in the present invention without departing from the spirit and scope of the invention. Thus, if such modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalents, the present invention is also intended to include such modifications and variations.
In the description of the present invention, it is to be understood that the terms "first", "second" and the like are used for descriptive purposes only and are not to be construed as indicating or implying relative importance or implying any number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of the present invention, "a plurality" means two or more unless specifically defined otherwise.
In the present invention, unless otherwise expressly stated or limited, the terms "mounted," "connected," "secured," and the like are to be construed broadly and can, for example, be fixedly connected, detachably connected, or integrally formed; can be mechanically or electrically connected; either directly or indirectly through intervening media, either internally or in any other relationship. The specific meanings of the above terms in the present invention can be understood by those skilled in the art according to specific situations.
In the present invention, unless otherwise expressly stated or limited, the first feature "on" or "under" the second feature may be directly contacting the first and second features or indirectly contacting the first and second features through an intermediate. Also, a first feature "on," "over," and "above" a second feature may be directly or diagonally above the second feature, or may simply indicate that the first feature is at a higher level than the second feature. A first feature being "under," "below," and "beneath" a second feature may be directly under or obliquely under the first feature, or may simply mean that the first feature is at a lesser elevation than the second feature.
In the description herein, references to the description of the term "one embodiment," "some embodiments," "an example," "a specific example," or "some examples," etc., mean that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the invention. In this specification, the schematic representations of the terms used above should not be understood to necessarily refer to the same embodiment or example. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples. Furthermore, various embodiments or examples and features of different embodiments or examples described in this specification can be combined and combined by one skilled in the art without contradiction.
Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention, and that variations, modifications, substitutions and alterations can be made to the above embodiments by those of ordinary skill in the art within the scope of the present invention.

Claims (10)

1. An over-temperature protection method of a variable frequency driving device is characterized in that the variable frequency driving device comprises a power supply circuit, a power factor correction circuit, a driving circuit, a sampling circuit, an interface circuit and a control circuit, the interface circuit is connected with the control circuit, the control circuit is respectively connected with the power circuit, the drive circuit and the sampling circuit, the power supply circuit is respectively connected with the power factor correction circuit and the sampling circuit, the power factor correction circuit is connected with the drive circuit, the driving circuit is respectively connected with the sampling circuit and the alternating current motor, the control circuit receives the speed instruction sent by the interface circuit, and adjusting the driving circuit to drive the alternating current motor to work according to the speed instruction, wherein the over-temperature protection method comprises the following steps:
In the running process of the alternating current motor, the control circuit acquires the input voltage of the power supply circuit and the output voltage and the output current of the driving circuit, which are acquired by the sampling circuit, in real time;
calculating a preliminary over-temperature threshold value of a power module of the driving circuit according to the input voltage of the power circuit and the output voltage and the output current of the driving circuit;
comparing the preliminary over-temperature threshold value with a maximum temperature value allowed by the power module to determine a final over-temperature threshold value;
and acquiring the temperature of the power module, and judging whether the temperature of the power module exceeds the final over-temperature threshold value or not so as to adjust the speed instruction when the temperature of the power module exceeds the final over-temperature threshold value, so that the driving circuit drives the alternating current motor to work according to the adjusted speed instruction.
2. The method for protecting the variable frequency drive device from the over-temperature according to claim 1, wherein the power circuit comprises a filter circuit and a rectifier circuit, and the filter circuit and the rectifier circuit are used for rectifying and filtering the input alternating current so that the sampling circuit collects the rectified and filtered input voltage.
3. The over-temperature protection method of the variable frequency driving device according to claim 2, wherein the driving circuit comprises an inverter circuit and a PWM driving circuit, and the PWM driving circuit drives a power module of the inverter circuit according to the PWM signal output by the control circuit so as to drive the ac motor to operate according to the speed command.
4. The method of claim 3, wherein the preliminary over-temperature threshold of the power module of the drive circuit is calculated according to the following equation:
Pin＝A1Pout+B1
Figure FDA0003490903780000011
Tprot＝A2Iin+B2
wherein, PinFor input power, PoutTo output power, A1And B1Taking a plurality of power points in an input power range, recording measured input power and calculated output power, and linearly fitting to obtain a coefficient; i isinFor input of current, VinIn order to input the voltage, the voltage is,
Figure FDA0003490903780000012
determining according to the power factor of an input power supply, wherein the value is between 0 and 1; t isprotTo obtain a preliminary over-temperature threshold, A2And B2In order to obtain a plurality of voltage points in an input voltage range, an alternating current motor runs at a plurality of input power points, a precise temperature acquisition instrument is utilized to measure the real-time temperature of a power tube of a power factor correction circuit, and the corresponding input current I when the power tube of the power factor correction circuit reaches a required over-temperature threshold value is recorded inTemperature T of power moduleIPMAnd fitting the coefficients linearly.
5. The method for protecting variable frequency drive device from over-temperature according to claim 1, wherein comparing the preliminary over-temperature threshold with a maximum temperature value allowed by the power module to determine a final over-temperature threshold comprises:
judging whether the preliminary over-temperature threshold value is larger than the maximum temperature value allowed by the power module;
if the preliminary over-temperature threshold value is larger than the maximum temperature value allowed by the power module, taking the maximum temperature value allowed by the power module as a final over-temperature threshold value;
and if the preliminary over-temperature threshold value is less than or equal to the maximum temperature value allowed by the power module, taking the preliminary over-temperature threshold value as a final over-temperature threshold value.
6. The over-temperature protection method of the variable frequency driving device according to claim 1, wherein if the temperature of the power module exceeds the final over-temperature threshold, a preset speed difference value is subtracted from the speed command to obtain a current speed command, and the driving circuit is adjusted according to the current speed command to drive the alternating current motor to work.
7. A variable frequency drive, comprising:
The power supply circuit is used for rectifying and filtering the input alternating current to obtain a processed input voltage;
the power factor correction circuit is connected with the power circuit and improves the input power factor by controlling the on-off of a power tube;
the driving circuit is connected with the power factor correction circuit and is used for driving the alternating current motor to work;
the sampling circuit is respectively connected with the power circuit and the driving circuit and is used for acquiring the input voltage of the power circuit and the output voltage of the driving circuit in real time;
an interface circuit for obtaining a speed command signal;
the control circuit is respectively connected with the interface circuit, the sampling circuit and the driving circuit, receives a speed instruction sent by the interface circuit, adjusts the driving circuit to drive the alternating current motor to work according to the speed instruction, and acquires the input voltage of the power supply circuit and the output voltage and the output current of the driving circuit, which are acquired by the sampling circuit, in real time in the running process of the alternating current motor; calculating a preliminary over-temperature threshold value of a power module of the driving circuit according to the input voltage of the power circuit, the output voltage and the output current of the driving circuit; comparing the preliminary over-temperature threshold value with a maximum temperature value allowed by the power module to determine a final over-temperature threshold value; and acquiring the temperature of the power module, and judging whether the temperature of the power module exceeds the final over-temperature threshold value or not so as to adjust the speed instruction when the temperature of the power module exceeds the final over-temperature threshold value, so that the driving circuit drives the alternating current motor to work according to the adjusted speed instruction.
8. The variable frequency drive of claim 7, wherein the preliminary over-temperature threshold for the power module of the drive circuit is calculated according to the following equation:
Pin＝A1Pout+B1
Figure FDA0003490903780000031
Tprot＝A2Iin+B2
wherein, PinFor input power, PoutTo output power, A1And B1Taking a plurality of power points in an input power range, recording measured input power and calculated output power, and linearly fitting to obtain a coefficient; i isinFor input of current, VinIn order to input the voltage, the voltage is,
Figure FDA0003490903780000032
determining according to the power factor of an input power supply, wherein the value is between 0 and 1; t isprotTo obtain a preliminary over-temperature threshold, A2And B2In order to obtain a plurality of voltage points in an input voltage range, an alternating current motor runs at a plurality of input power points, a precise temperature acquisition instrument is utilized to measure the real-time temperature of a power tube of a power factor correction circuit, and the corresponding input current I when the power tube of the power factor correction circuit reaches a required over-temperature threshold value is recordedinTemperature T of power moduleIPMAnd fitting the obtained coefficients linearly.
9. The variable frequency drive of claim 7, wherein the control circuit is further configured to determine whether the preliminary over-temperature threshold is greater than a maximum temperature value allowed by the power module; if the preliminary over-temperature threshold value is larger than the maximum temperature value allowed by the power module, taking the maximum temperature value allowed by the power module as a final over-temperature threshold value; and if the preliminary over-temperature threshold value is less than or equal to the maximum temperature value allowed by the power module, taking the preliminary over-temperature threshold value as a final over-temperature threshold value.
10. The variable frequency drive of claim 7, wherein the control circuit is further configured to subtract a preset speed difference from the speed command to obtain a current speed command if the temperature of the power module exceeds the final over-temperature threshold, and to adjust the drive circuit to drive the ac motor to operate according to the current speed command.
CN202210095597.7A 2022-01-26 2022-01-26 Overtemperature protection method of variable frequency driving device and variable frequency driving device Pending CN114567232A (en)

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