Frequency converter control method, storage medium, controller and air conditioner

Abstract

The invention discloses a control method of a frequency converter, a storage medium, a controller and an air conditioner. The frequency converter comprises an inverter bridge and an electrolytic capacitor connected with the direct current end of the inverter bridge in parallel, the alternating current end of the inverter bridge is used for being connected with a load, the electrolytic capacitor is further used for being connected with a direct current bus, and the method comprises the steps of determining a comparison value of a switching device on each bridge arm according to a duty ratio and a carrier period of a state signal output by the switching device on each bridge arm of the inverter bridge; according to the comparison value and the carrier wave of the state signal, adjusting the state signal output by the switching device on each bridge arm so as to reduce the fluctuation frequency of the direct-current bus current. According to the method, a comparison value of a switching device on each bridge arm is determined, and a state signal output by the switching device on each bridge arm is adjusted according to the comparison value and a carrier wave of the state signal, so that the frequency of large fluctuation of current on a direct-current bus is reduced, the frequency of violent charging and discharging of an electrolytic capacitor is reduced, and the purpose of prolonging the service life of the electrolytic capacitor is achieved.

Description

Technical Field

[0001] The present invention relates to the field of inverter control methods, and in particular to an inverter control method and storage medium, a controller, and an air conditioner. Background Art

[0002] The compressor in the inverter air conditioner is usually driven and controlled by an AC-DC-AC inverter. The AC power outputs a DC voltage through a rectifier, and then passes through an electrolytic capacitor to provide a stable DC voltage to the inverter.

[0003] Related technologies generally use voltage space vector modulation to control the switching devices of the three bridge arms of the inverter, thereby outputting AC voltage to control the compressor. However, in each switching cycle of the inverter switching device, this technology will cause the bus current to fluctuate twice, causing drastic charging and discharging of the electrolytic capacitor, reducing the service life of the electrolytic capacitor. Summary of the invention

[0004] The present invention aims to solve one of the technical problems in the related art to at least a certain extent. To this end, one object of the present invention is to provide a control method for a frequency converter, which can extend the service life of an electrolytic capacitor and improve the stability of the frequency converter by reducing the number of fluctuations of the DC bus current.

[0005] A second object of the present invention is to provide a computer-readable storage medium.

[0006] The third object of the present invention is to provide a controller.

[0007] A fourth object of the present invention is to provide an air conditioner.

[0008] To achieve the above-mentioned purpose, the first aspect of the present invention proposes a control method for a frequency converter, wherein the frequency converter includes an inverter bridge and an electrolytic capacitor connected in parallel with the DC end of the inverter bridge, the AC end of the inverter bridge is used to connect the load, and the electrolytic capacitor is also used to connect the DC bus. The method includes: determining a comparison value of the switching devices on each bridge arm of the inverter bridge according to the duty cycle and carrier period of the output status signal of the switching devices on each bridge arm of the inverter bridge; adjusting the status signal output by the switching devices on each bridge arm according to the comparison value and the carrier of the status signal to reduce the number of fluctuations of the DC bus current.

[0009] According to the control method of the inverter of the embodiment of the present invention, by re-determining the comparison value of the switching device on each bridge arm, the state signal output by the switching device on each bridge arm is adjusted according to the comparison value and the carrier of the state signal, so as to reduce the number of large fluctuations of the current on the DC bus, thereby reducing the number of violent charging and discharging of the electrolytic capacitor, thereby achieving the purpose of extending the service life of the electrolytic capacitor.

[0010] In addition, the control method of the frequency converter proposed in the above embodiment of the present invention may also have the following additional technical features:

[0011] According to one embodiment of the present invention, the inverter bridge includes a three-phase bridge arm, and the state signal output by the switch device on each bridge arm is adjusted according to the comparison value and the carrier of the state signal, including: determining the maximum value, the middle value and the minimum value in the comparison value; obtaining the direction of the load phase current connected to the bridge arm corresponding to the middle value; if it is flowing out of the load direction, determining a new middle value and a new minimum value according to the maximum value, the middle value, the minimum value and the amplitude of the carrier; controlling the switch device on the bridge arm corresponding to the maximum value to continuously output a high level, and adjusting the output level of the switch device on the bridge arm corresponding to the new middle value according to the new middle value and the instantaneous value of the carrier, and adjusting the output level of the switch device on the bridge arm corresponding to the new minimum value according to the new minimum value and the instantaneous value of the carrier.

[0012] According to one embodiment of the present invention, if the current is flowing in the load direction, a new maximum value and a new intermediate value are determined based on the minimum value, the maximum value and the intermediate value; the switch device on the bridge arm corresponding to the minimum value is controlled to continuously output a low level, and the output level of the switch device on the bridge arm corresponding to the new intermediate value is adjusted according to the new intermediate value and the instantaneous value of the carrier, and the output level of the switch device on the bridge arm corresponding to the new maximum value is adjusted according to the new maximum value and the instantaneous value of the carrier.

[0013] According to one embodiment of the present invention, a new intermediate value and a new minimum value are determined based on the maximum value, the intermediate value, the minimum value and the amplitude of the carrier, including: calculating the difference between the maximum value and the amplitude to obtain a first offset value; calculating the sum of the intermediate value and the first offset value to obtain the new intermediate value; calculating the sum of the minimum value and the first offset value to obtain the new minimum value.

[0014] According to one embodiment of the present invention, a new maximum value and a new intermediate value are determined based on the minimum value, the maximum value and the intermediate value, including: calculating the difference between the minimum value and the intermediate value to obtain a new intermediate value; calculating the difference between the minimum value and the maximum value to obtain a new maximum value.

[0015] According to one embodiment of the present invention, adjusting the output level of the switch device on the bridge arm corresponding to the new intermediate value according to the new intermediate value and the instantaneous value of the carrier includes: if the instantaneous value of the carrier is greater than the new intermediate value, controlling the switch device on the bridge arm corresponding to the new intermediate value to output a low level; if the instantaneous value of the carrier is less than or equal to the new intermediate value, controlling the switch device on the bridge arm corresponding to the new intermediate value to output a high level; or, if the instantaneous value of the carrier is greater than the new intermediate value, controlling the switch device on the bridge arm corresponding to the new intermediate value to output a high level; if the instantaneous value of the carrier is less than or equal to the new intermediate value, controlling the switch device on the bridge arm corresponding to the new intermediate value to output a low level.

[0016] According to one embodiment of the present invention, adjusting the output level of the switching device on the bridge arm corresponding to the new minimum value according to the new minimum value and the instantaneous value of the carrier includes: if the instantaneous value of the carrier is greater than the new minimum value, controlling the output low level of the switching device on the bridge arm corresponding to the new minimum value; if the instantaneous value of the carrier is less than the new minimum value, controlling the output high level of the switching device on the bridge arm corresponding to the new minimum value.

[0017] According to one embodiment of the present invention, the step of adjusting the output level of the switch device on the bridge arm corresponding to the new maximum value according to the new maximum value and the instantaneous value of the carrier comprises: if the instantaneous value of the carrier is greater than the new maximum value, controlling the output low level of the switch device on the bridge arm corresponding to the new maximum value; if the instantaneous value of the carrier is less than the new maximum value, controlling the output high level of the switch device on the bridge arm corresponding to the new maximum value.

[0018] To achieve the above objectives, a second aspect of the present invention provides a computer-readable storage medium having a computer program stored thereon. When the computer program is executed by a processor, the control method of the frequency converter provided in the first aspect of the present invention is implemented.

[0019] To achieve the above-mentioned purpose, the third aspect of the present invention proposes a controller, including a memory and a processor, wherein a computer program is stored in the memory, and when the computer program is executed by the processor, the control method of the inverter proposed in the first aspect of the present invention is implemented.

[0020] To achieve the above-mentioned purpose, a fourth embodiment of the present invention provides an air conditioner, comprising a frequency converter and a controller as provided in the third embodiment of the present invention.

[0021] Additional aspects and advantages of the present invention will be given in part in the following description and in part will be obvious from the following description, or will be learned through practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 It is the output state diagram of the switch devices on each bridge arm of the inverter bridge in the related space vector modulation technology;

[0023] Figure 2 is a control circuit diagram of a frequency converter according to an embodiment of the present invention;

[0024] Figure 3 is a flow chart of a method for controlling a frequency converter according to an embodiment of the present invention;

[0025] Figure 4 is a flow chart of adjusting the state signal output by the switch devices on each bridge arm according to an embodiment of the present invention;

[0026] Figure 5 is a flow chart of determining a new intermediate value and a new minimum value according to an embodiment of the present invention;

[0027] Figure 6 is a flow chart of determining a new maximum value and a new intermediate value according to an embodiment of the present invention;

[0028] Figure 7 It is a state diagram of the output of the switch devices on each bridge arm corresponding to the load phase current connected to the bridge arm corresponding to the intermediate value of a specific embodiment of the present invention flowing out of the load direction;

[0029] Figure 8 It is a state diagram of the output of the switch devices on each bridge arm corresponding to the load phase current connected to the bridge arm corresponding to the direction of flowing into the load in a specific embodiment of the present invention;

[0030] Fig. 9 is a state diagram of the output of the switch devices on each bridge arm corresponding to the load phase current connected to the bridge arm corresponding to the intermediate value of another specific embodiment of the present invention flowing out of the load direction;

[0031] Fig.10 is a state diagram of the output of the switch devices on each bridge arm corresponding to the load phase current connected to the bridge arm corresponding to the direction of flowing into the load in another specific embodiment of the present invention;

[0032] Fig.11 is a structural block diagram of a controller according to an embodiment of the present invention;

[0033] Fig.12 Schematic diagram of an air conditioner according to an embodiment of the present invention. DETAILED DESCRIPTION

[0034] Embodiments of the present invention are described in detail below, examples of which are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are intended to be used to explain the present invention, and should not be construed as limiting the present invention.

[0035] The following is attached to the instruction manual Figure 1-12 And specific implementation methods are described in detail for the control method of the inverter and the storage medium, the controller, and the air conditioner in the embodiments of the present invention.

[0036] Figure 1 The output state diagram of the switching devices on each bridge arm of the inverter bridge in the related space vector modulation method is shown. It should be noted that, according to the working state of the switching devices in the three bridge arms of the inverter, the space vector modulation has a total of 8 basic voltage vectors, namely 6 effective voltage vectors and 2 zero voltage vectors. In each switching cycle of the switching device, the space vector modulation uses 2 effective voltage vectors and 2 zero voltage vectors to synthesize the required voltage vector. The zero voltage vector in the space vector modulation method will form a current on the DC bus, while the effective voltage vector will not form a current on the DC bus. Therefore, in each switching cycle of the switching devices on each bridge arm of the inverter, the bus current will fluctuate significantly twice, causing violent charging and discharging of the electrolytic capacitor.

[0037] The inverter in the inverter control method of the embodiment of the present invention may include an inverter bridge and an electrolytic capacitor connected in parallel with the DC end of the inverter bridge, the AC end of the inverter bridge is used to connect the load, and the electrolytic capacitor is also used to connect the DC bus. Figure 2 A control circuit diagram of a frequency converter according to an embodiment of the present invention is shown.

[0038] Figure 3 FIG. 1 is a flow chart of a method for controlling a frequency converter according to an embodiment of the present invention. Figure 3 As shown, the control method of the frequency converter may include:

[0039] S101, determining a comparison value of a switch device on each bridge arm according to a duty cycle and a carrier cycle of an output state signal of a switch device on each bridge arm of an inverter bridge;

[0040] S102, adjusting the state signal output by the switch device on each bridge arm according to the comparison value and the carrier of the state signal, so as to reduce the number of fluctuations of the DC bus current.

[0041] In order to extend the service life of the electrolytic capacitor, the embodiment of the present invention re-determines the comparison value of the switching device on each bridge arm, and adjusts the state signal output by the switching device on each bridge arm according to the comparison value and the instantaneous value of the carrier, so as to reduce the number of large fluctuations in the current on the DC bus, thereby reducing the number of violent charging and discharging of the electrolytic capacitor, thereby achieving the purpose of extending the service life of the electrolytic capacitor, and at the same time improving the stability of the inverter.

[0042] Specifically, according to the output state signal of the switch device on each bridge arm in the inverter bridge, that is, PWM (Pulse

[0043] The duty cycle and carrier cycle of the pulse width modulation (PWM) signal are used to determine the comparison value of the switch devices on each bridge arm. The comparison values ​​of the switch devices on each bridge arm are compared, and the comparison values ​​of the switch devices on each bridge arm are re-determined according to the comparison results (maximum value, middle value and minimum value) and the load phase current direction of the bridge arm corresponding to the middle value. The output state of the switch devices on each bridge arm is adjusted according to the re-determined comparison value and the instantaneous value of the carrier to reduce the number of fluctuations of the DC bus current, thereby reducing the number of violent charging and discharging of the electrolytic capacitor, so as to achieve the purpose of extending the service life of the electrolytic capacitor, and at the same time improve the stability of the inverter.

[0044] In one embodiment of the present invention, Figure 4 As shown, the inverter bridge includes three-phase bridge arms, and the state signal output by the switch device on each bridge arm is adjusted according to the comparison value and the carrier of the state signal, including:

[0045] S201, determining the maximum value, the middle value and the minimum value among the comparison values;

[0046] S202, obtaining the load phase current direction connected to the bridge arm corresponding to the intermediate value;

[0047] S203, if it is an outflow load direction, determine a new middle value and a new minimum value according to the maximum value, the middle value, the minimum value and the amplitude of the carrier;

[0048] S204, controlling the switch device on the bridge arm corresponding to the maximum value to continuously output a high level, and adjusting the output level of the switch device on the bridge arm corresponding to the new intermediate value according to the new intermediate value and the instantaneous value of the carrier, and adjusting the output level of the switch device on the bridge arm corresponding to the new minimum value according to the new minimum value and the instantaneous value of the carrier.

[0049] Since the inverter bridge includes three-phase bridge arms, the comparison values ​​of the switching devices on the three-phase bridge arms can be obtained according to the duty ratio and carrier period of the output state signals of the switching devices on each bridge arm, that is, three comparison values ​​can be obtained.

[0050] The embodiment of the present invention compares the three obtained comparison values ​​to determine the largest comparison value (maximum value), the middle comparison value (middle value) and the smallest comparison value (minimum value) among the three comparison values.

[0051] In the embodiment of the present invention, when the comparison value of the switch device on each bridge arm is re-determined, the load phase current direction of the bridge arm corresponding to the intermediate value (intermediate comparison value) is also obtained. According to the load phase current direction of the bridge arm corresponding to the intermediate value (intermediate comparison value), the comparison value that needs to be re-determined is determined.

[0052] Specifically, if the load phase current direction of the bridge arm corresponding to the intermediate value (intermediate comparison value) is the direction of outflow from the load, the comparison value needs to be re-determined as the intermediate value (intermediate comparison value) and the minimum value (minimum comparison value). Further specifically, the new intermediate value and the new minimum value can be determined according to the maximum value, the intermediate value, the minimum value and the amplitude of the carrier.

[0053] In this embodiment, if Figure 5 As shown, determining a new middle value and a new minimum value according to the maximum value, the middle value, the minimum value and the amplitude of the carrier may include:

[0054] S301, calculating the difference between the maximum value and the amplitude to obtain a first offset value;

[0055] S302, calculating the sum of the intermediate value and the first offset value to obtain a new intermediate value;

[0056] S303: Calculate the sum of the minimum value and the first offset value to obtain a new minimum value.

[0057] Specifically, the difference between the maximum value (maximum comparison value) of the switching devices on the three bridge arms and the amplitude of the carrier is calculated to obtain a first offset value. A new intermediate value and a new minimum value are re-determined according to the first offset value. Further specifically, the sum of the intermediate value (intermediate comparison value) and the first offset value is calculated to obtain a new intermediate value. The sum of the minimum value (minimum comparison value) and the first offset value is calculated to obtain a new minimum value.

[0058] After determining the new intermediate value and the new minimum value, control the switch device on the bridge arm corresponding to the maximum value (the largest comparison value) to continuously output a high level. Adjust the output level of the switch device on the bridge arm corresponding to the new intermediate value according to the new intermediate value and the instantaneous value of the carrier. Adjust the output level of the switch device on the bridge arm corresponding to the new minimum value according to the new minimum value and the instantaneous value of the carrier.

[0059] In another embodiment of the present invention, Figure 4 As shown,

[0060] S205, if it is the inflow load direction, determine a new maximum value and a new middle value according to the minimum value, the maximum value and the middle value;

[0061] S206, controlling the switch device on the bridge arm corresponding to the minimum value to continuously output a low level, and adjusting the output level of the switch device on the bridge arm corresponding to the new intermediate value according to the new intermediate value and the instantaneous value of the carrier, and adjusting the output level of the switch device on the bridge arm corresponding to the new maximum value according to the new maximum value and the instantaneous value of the carrier.

[0062] Specifically, if the load phase current direction of the bridge arm corresponding to the intermediate value (intermediate comparison value) is the direction of the load flow, the maximum value (maximum comparison value) and the intermediate value (intermediate comparison value) need to be re-determined. Further specifically, a new maximum value and a new intermediate value are determined based on the minimum value (minimum comparison value), the maximum value (maximum comparison value) and the intermediate value (intermediate comparison value).

[0063] In this embodiment, if Figure 6 As shown, determining a new maximum value and a new middle value according to the minimum value, the maximum value and the middle value may include:

[0064] S401, calculating the difference between the minimum value and the middle value to obtain a new middle value;

[0065] S402, calculating the difference between the minimum value and the maximum value to obtain a new maximum value.

[0066] Specifically, the difference between the minimum value (minimum comparison value) and the middle value (middle comparison value) of the switch devices on the three bridge arms is calculated, and the difference is used as the new middle value. The difference between the minimum value (minimum comparison value) and the maximum value (maximum comparison value) of the switch devices on the three bridge arms is calculated, and the difference is used as the new maximum value.

[0067] After determining the new maximum value and the new middle value, the switch device on the bridge arm corresponding to the minimum value (the minimum comparison value) is controlled to continuously output a low level. The output level of the switch device on the bridge arm corresponding to the new middle value is adjusted according to the new middle value and the instantaneous value of the carrier. The output level of the switch device on the bridge arm corresponding to the new maximum value is adjusted according to the new maximum value and the instantaneous value of the carrier.

[0068] In one embodiment of the present invention, adjusting the output level of the switch device on the bridge arm corresponding to the new intermediate value according to the new intermediate value and the instantaneous value of the carrier may include:

[0069] If the instantaneous value of the carrier is greater than the new intermediate value, the switch device on the bridge arm corresponding to the new intermediate value is controlled to output a low level; if the instantaneous value of the carrier is less than or equal to the new intermediate value, the switch device on the bridge arm corresponding to the new intermediate value is controlled to output a high level; or,

[0070] If the instantaneous value of the carrier is greater than the new intermediate value, the switch device on the bridge arm corresponding to the new intermediate value is controlled to output a high level; if the instantaneous value of the carrier is less than or equal to the new intermediate value, the switch device on the bridge arm corresponding to the new intermediate value is controlled to output a low level.

[0071] In the embodiment of the present invention, the output level of the switch device on the bridge arm corresponding to the new intermediate value has the above two output control modes.

[0072] In one embodiment of the present invention, adjusting the output level of the switch device on the bridge arm corresponding to the new minimum value according to the new minimum value and the instantaneous value of the carrier may include:

[0073] If the instantaneous value of the carrier is greater than the new minimum value, the output level of the switch device on the bridge arm corresponding to the new minimum value is controlled to be low; if the instantaneous value of the carrier is less than the new minimum value, the output level of the switch device on the bridge arm corresponding to the new minimum value is controlled to be high.

[0074] In an embodiment of the present invention, the output level of the switch device on the bridge arm corresponding to the new minimum value is controlled by the above-mentioned output control method.

[0075] In one embodiment of the present invention, adjusting the output level of the switch device on the bridge arm corresponding to the new maximum value according to the new maximum value and the instantaneous value of the carrier may include:

[0076] If the instantaneous value of the carrier is greater than the new maximum value, the output level of the switch device on the bridge arm corresponding to the new maximum value is controlled to be low; if the instantaneous value of the carrier is less than the new maximum value, the output level of the switch device on the bridge arm corresponding to the new maximum value is controlled to be high.

[0077] In an embodiment of the present invention, the output level of the switch device on the bridge arm corresponding to the new maximum value is controlled by the above-mentioned output control method.

[0078] As a specific embodiment, when the load phase current connected to the bridge arm corresponding to the intermediate value is flowing out of the load direction, the comparison value needs to be re-determined as the intermediate value (intermediate comparison value) and the minimum value (minimum comparison value). After obtaining the new intermediate value and the new minimum value by using the above-mentioned method of calculating the new intermediate value and the new minimum value, the level state of the switch device output on the bridge arm corresponding to the maximum value, the new intermediate value and the new minimum value is controlled by using the above-mentioned control output method. Among them, the level state of the switch device output on the bridge arm corresponding to the maximum value, the new intermediate value and the new minimum value is as follows: Figure 7 It should be noted that Figure 7The level of the output of the switch device on the bridge arm corresponding to the new intermediate value, when the instantaneous value of the carrier is greater than the new intermediate value, controls the switch device on the bridge arm corresponding to the new intermediate value to output a low level; when the instantaneous value of the carrier is less than or equal to the new intermediate value, controls the switch device on the bridge arm corresponding to the new intermediate value to output a high level, so that the three-phase bridge arm of the inverter bridge has only one state where the three-phase bridge arm outputs are all high level, and there is no state where the three-phase bridge arm outputs are all low level, that is, there is only one zero voltage vector. The control method of the inverter of the embodiment of the present invention reduces the number of zero voltage vectors, thereby reducing the number of fluctuations of the DC bus current, so as to reduce the number of violent charging and discharging of the electrolytic capacitor, thereby achieving the purpose of extending the service life of the electrolytic capacitor.

[0079] When the load phase current connected to the bridge arm corresponding to the intermediate value is flowing out of the load direction, the maximum value (maximum comparison value) and the intermediate value (intermediate comparison value) need to be re-determined, and the new intermediate value and the new maximum value are obtained by using the above method of calculating the new intermediate value and the new maximum value, and then the level state of the switch device output on the bridge arm corresponding to the minimum value, the new intermediate value and the new maximum value is controlled by using the above control output method. Among them, the level state of the switch device output on the bridge arm corresponding to the minimum value, the new intermediate value and the new maximum value is as follows: Figure 8 It should be noted that Figure 8 The level of the output of the switch device on the bridge arm corresponding to the new intermediate value, when the instantaneous value of the carrier is greater than the new intermediate value, controls the switch device on the bridge arm corresponding to the new intermediate value to output a low level; when the instantaneous value of the carrier is less than or equal to the new intermediate value, controls the switch device on the bridge arm corresponding to the new intermediate value to output a high level. The three-phase bridge arm of the inverter bridge only has one state where the three-phase bridge arm outputs all low levels, and there is no state where the three-phase bridge arm outputs all high levels, that is, there is only one zero voltage vector. The control method of the inverter of the embodiment of the present invention reduces the number of zero voltage vectors, thereby reducing the number of fluctuations of the DC bus current, so as to reduce the number of violent charging and discharging of the electrolytic capacitor, thereby achieving the purpose of extending the service life of the electrolytic capacitor.

[0080] In another specific embodiment of the present invention, the level of the output of the switch device on the bridge arm corresponding to the new intermediate value is, when the instantaneous value of the carrier is greater than the new intermediate value, the switch device on the bridge arm corresponding to the new intermediate value outputs a high level; when the instantaneous value of the carrier is less than or equal to the new intermediate value, the switch device on the bridge arm corresponding to the new intermediate value outputs a low level. The load phase current connected to the bridge arm corresponding to the intermediate value flows out of the load direction, so that the three-phase bridge arm of the inverter bridge does not have a state where the three-phase bridge arm outputs all high levels or all low levels, see Fig. 9The load phase current connected to the bridge arm corresponding to the intermediate value flows into the load direction, so that the three-phase bridge arm of the inverter bridge does not have a state where the three-phase bridge arm outputs all low levels or all high levels, see Fig.10 It can be seen that in this embodiment, there is no zero voltage vector, thereby further reducing the number of times the electrolytic capacitor is violently charged and discharged, thereby achieving the purpose of extending the service life of the electrolytic capacitor.

[0081] The control method of the frequency converter of the embodiment of the present invention adjusts the state signal output by the switching device on each bridge arm according to the direction of the motor phase current, the comparison value of the switching device on each bridge arm and the instantaneous value of the carrier, thereby reducing the number of bus current fluctuations and the number of charge and discharge times of the electrolytic capacitor, and improving the service life of the electrolytic capacitor.

[0082] The present invention provides a computer-readable storage medium.

[0083] In this embodiment, a computer program is stored on a computer-readable storage medium. When the computer program is executed by a processor, the control method of the frequency converter as described above is implemented.

[0084] The invention provides a controller.

[0085] In this embodiment, the controller includes a memory and a processor. The memory stores a computer program. When the computer program is executed by the processor, the control method of the frequency converter as described above is implemented.

[0086] Fig.11 is a block diagram of a controller according to an embodiment of the present invention. Fig.11 As shown, the controller 500 includes: a processor 501 and a memory 503. The processor 501 and the memory 503 are connected, such as through a bus 502. Optionally, the controller 500 may also include a transceiver 504. It should be noted that in actual applications, the transceiver 504 is not limited to one, and the structure of the controller 500 does not constitute a limitation on the embodiments of the present invention.

[0087] Processor 501 may be a CPU (Central Processing Unit), a general-purpose processor, a DSP (Digital Signal Processor), an ASIC (Application Specific Integrated Circuit), an FPGA (Field Programmable Gate Array), or other programmable logic devices, transistor logic devices, hardware components, or any combination thereof. It may implement or execute various exemplary logic blocks, modules, and circuits described in conjunction with the disclosure of the present invention. Processor 501 may also be a combination that implements computing functions, such as a combination of one or more microprocessors, a combination of a DSP and a microprocessor, and the like.

[0088] The bus 502 may include a path to transmit information between the above components. The bus 502 may be a PCI (Peripheral Component Interconnect) bus or an EISA (Extended Industry Standard Architecture) bus. The bus 502 may be divided into an address bus, a data bus, a control bus, etc. For ease of representation, Fig.11 Only one thick line is used in the diagram, but this does not mean that there is only one bus or only one type of bus.

[0089] The memory 503 is used to store a computer program corresponding to the control method of the frequency converter of the above embodiment of the present invention, and the computer program is controlled and executed by the processor 501. The processor 501 is used to execute the computer program stored in the memory 503 to implement the contents shown in the above method embodiment. Fig.11 The controller 500 shown is only an example and should not bring any limitation to the functions and scope of use of the embodiments of the present invention.

[0090] The invention provides an air conditioner.

[0091] Fig.12 Schematic diagram of an air conditioner according to an embodiment of the present invention. Fig.12 As shown, the air conditioner 1000 may include an inverter 600 and the controller 500 as described above.

[0092] The inverter 600 in the air conditioner of the embodiment of the present invention is controlled by the inverter control method stored in the above-mentioned controller 500, which reduces the number of times the electrolytic capacitor is violently charged and discharged, and extends the service life of the electrolytic capacitor, thereby improving the stability of the inverter and improving the performance of the air conditioner.

[0093] It should be noted that the logic and / or steps represented in the flowchart or otherwise described herein, for example, can be considered as a sequenced list of executable instructions for implementing logical functions, and can be specifically implemented in any computer-readable medium for use by an instruction execution system, device or apparatus (such as a computer-based system, a system including a processor, or other system that can fetch instructions from an instruction execution system, device or apparatus and execute instructions), or in combination with these instruction execution systems, devices or apparatuses. For the purposes of this specification, "computer-readable medium" can be any device that can contain, store, communicate, propagate or transmit a program for use by an instruction execution system, device or apparatus, or in combination with these instruction execution systems, devices or apparatuses. More specific examples of computer-readable media (a non-exhaustive list) include the following: an electrical connection portion with one or more wirings (electronic device), a portable computer disk box (magnetic device), a random access memory (RAM), a read-only memory (ROM), an erasable and programmable read-only memory (EPROM or flash memory), an optical fiber device, and a portable compact disk read-only memory (CDROM). In addition, the computer-readable medium may even be paper or other suitable medium on which the program is printed, since the program may be obtained electronically, for example, by optically scanning the paper or other medium and then editing, interpreting or processing in other suitable ways if necessary, and then stored in a computer memory.

[0094] It should be understood that the various parts of the present invention can be implemented by hardware, software, firmware or a combination thereof. In the above-mentioned embodiments, a plurality of steps or methods can be implemented by software or firmware stored in a memory and executed by a suitable instruction execution system. For example, if implemented by hardware, as in another embodiment, it can be implemented by any one of the following technologies known in the art or their combination: a discrete logic circuit having a logic gate circuit for implementing a logic function for a data signal, a dedicated integrated circuit having a suitable combination of logic gate circuits, a programmable gate array (PGA), a field programmable gate array (FPGA), etc.

[0095] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "examples", "specific examples", or "some examples" means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner.

[0096] In the description of the present invention, it is to be understood that the terms “center”, “longitudinal”, “lateral”, “length”, “width”, “thickness”, “up”, “down”, “front”, “back”, “left”, “right”, “vertical”, “horizontal”, “top”, “bottom”, “inside”, “outside”, “clockwise”, “counterclockwise”, “axial”, “radial”, “circumferential”, etc., indicating orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as limiting the present invention.

[0097] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one of the features. In the description of the present invention, the meaning of "plurality" is at least two, such as two, three, etc., unless otherwise clearly and specifically defined.

[0098] In the present invention, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements, unless otherwise clearly defined. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0099] In the present invention, unless otherwise clearly specified and limited, a first feature being "above" or "below" a second feature may mean that the first and second features are in direct contact, or the first and second features are in indirect contact through an intermediate medium. Moreover, a first feature being "above", "above" or "above" a second feature may mean that the first feature is directly above or obliquely above the second feature, or simply means that the first feature is higher in level than the second feature. A first feature being "below", "below" or "below" a second feature may mean that the first feature is directly below or obliquely below the second feature, or simply means that the first feature is lower in level than the second feature.

[0100] Although the embodiments of the present invention have been shown and described above, it is to be understood that the above embodiments are exemplary and are not to be construed as limitations of the present invention. A person skilled in the art may change, modify, replace and vary the above embodiments within the scope of the present invention.

Claims

1. A control method for a frequency converter, characterized in that: The frequency converter includes an inverter bridge and an electrolytic capacitor connected in parallel with a DC terminal of the inverter bridge, the AC terminal of the inverter bridge is used to connect a load, and the electrolytic capacitor is also used to connect a DC bus. The method includes: Determine the comparison value of the switch devices on each bridge arm according to the duty cycle and carrier period of the output state signal of the switch devices on each bridge arm of the inverter bridge; The state signal output by the switch device on each bridge arm is adjusted according to the comparison value and the carrier of the state signal to reduce the number of fluctuations of the DC bus current.

2. The control method of the frequency converter according to claim 1, characterized in that: The inverter bridge includes three-phase bridge arms, and the state signal output by the switch device on each bridge arm is adjusted according to the comparison value and the carrier of the state signal, including: Determine the maximum value, the middle value and the minimum value among the comparison values; Obtaining the load phase current direction connected to the bridge arm corresponding to the intermediate value; If the flow is out of the load direction, a new middle value and a new minimum value are determined according to the maximum value, the middle value, the minimum value and the amplitude of the carrier; Control the switch device on the bridge arm corresponding to the maximum value to continuously output a high level, and adjust the output level of the switch device on the bridge arm corresponding to the new intermediate value according to the new intermediate value and the instantaneous value of the carrier, and adjust the output level of the switch device on the bridge arm corresponding to the new minimum value according to the new minimum value and the instantaneous value of the carrier.

3. The control method of the frequency converter according to claim 2, characterized in that: If it is flowing into the load direction, determining a new maximum value and a new middle value according to the minimum value, the maximum value and the middle value; Control the switch device on the bridge arm corresponding to the minimum value to continuously output a low level, and adjust the output level of the switch device on the bridge arm corresponding to the new intermediate value according to the new intermediate value and the instantaneous value of the carrier, and adjust the output level of the switch device on the bridge arm corresponding to the new maximum value according to the new maximum value and the instantaneous value of the carrier.

4. The control method of the frequency converter according to claim 3, characterized in that: Determining a new intermediate value and a new minimum value according to the maximum value, the intermediate value, the minimum value, and the amplitude of the carrier wave comprises: Calculate the difference between the maximum value and the amplitude to obtain a first offset value; Calculating a sum of the intermediate value and the first offset value to obtain the new intermediate value; The sum of the minimum value and the first offset value is calculated to obtain the new minimum value.

5. The control method of the frequency converter according to claim 3, characterized in that: Determining a new maximum value and a new middle value according to the minimum value, the maximum value and the middle value includes: Calculate the difference between the minimum value and the intermediate value to obtain a new intermediate value; The difference between the minimum value and the maximum value is calculated to obtain a new maximum value.

6. The control method of the frequency converter according to claim 3, characterized in that: The adjusting the output level of the switch device on the bridge arm corresponding to the new intermediate value according to the new intermediate value and the instantaneous value of the carrier comprises: If the instantaneous value of the carrier is greater than the new intermediate value, the switch device on the bridge arm corresponding to the new intermediate value is controlled to output a low level; if the instantaneous value of the carrier is less than or equal to the new intermediate value, the switch device on the bridge arm corresponding to the new intermediate value is controlled to output a high level; or, If the instantaneous value of the carrier is greater than the new intermediate value, the switch device on the bridge arm corresponding to the new intermediate value is controlled to output a high level; if the instantaneous value of the carrier is less than or equal to the new intermediate value, the switch device on the bridge arm corresponding to the new intermediate value is controlled to output a low level.

7. The control method of the frequency converter according to claim 2, characterized in that: The adjusting the output level of the switch device on the bridge arm corresponding to the new minimum value according to the new minimum value and the instantaneous value of the carrier comprises: If the instantaneous value of the carrier is greater than the new minimum value, the output level of the switch device on the bridge arm corresponding to the new minimum value is controlled to be low; if the instantaneous value of the carrier is less than the new minimum value, the output level of the switch device on the bridge arm corresponding to the new minimum value is controlled to be high.

8. The control method of the frequency converter according to claim 3, characterized in that: The step of adjusting the output level of the switch device on the bridge arm corresponding to the new maximum value according to the new maximum value and the instantaneous value of the carrier wave comprises: If the instantaneous value of the carrier is greater than the new maximum value, the output level of the switch device on the bridge arm corresponding to the new maximum value is controlled to be low; if the instantaneous value of the carrier is less than the new maximum value, the output level of the switch device on the bridge arm corresponding to the new maximum value is controlled to be high.

9. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the computer program is executed by a processor, the control method of the frequency converter according to any one of claims 1 to 8 is implemented.

10. A controller, comprising a memory and a processor, wherein a computer program is stored in the memory, wherein: When the computer program is executed by the processor, the control method of the frequency converter according to any one of claims 1 to 8 is implemented.

11. An air conditioner, characterized in that: It comprises a frequency converter and a controller as claimed in claim 10.

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